Axis Deviation Research Articles

Hemiepiphysiodesis for Lower Extremity Coronal Plane Angular Correction in the Distal Femur and Proximal Tibia in Children With Achondroplasia.

Achondroplasia is the most prevalent form of skeletal dysplasia, affecting more than 250,000 individuals. Lower extremity angular deformities, particularly genu varum, are common in children with achondroplasia, often resulting in pain and limitation of function. The authors aim to determine the utility of lower extremity growth modulation with hemiepiphysiodesis in children with achondroplasia for correction of coronal plane deformities about the knee. The authors performed a retrospective chart review of a single center from 1/1/2000 to 12/31/2020 to identify pediatric patients with achondroplasia treated with hemiepiphysiodesis as their initial procedure at the distal femur and/or proximal tibia. Patients with adequate records and who had completed their treatment were included. Data collected included duration of treatment, complications, need for osteotomy, and radiographic measurements including initial and final mechanical axis deviation, knee mechanical axis zone, mechanical lateral distal femoral angle and medial proximal tibia angle. Ten patients with 17 limbs met our criteria. Nine patients (15 limbs) were treated for genu varum and 1 patient (2 limbs) was treated for genu valgum. Prior to treatment, the mechanical axis fell in zone 3 in 59% of limbs and zone 2 in 41%. Average correction in mechanical axis deviation was 26.1mm. Average change in mechanical lateral distal femoral angle was 10.3 degrees per limb, and average change in medial proximal tibia angle was 7.1 degrees per limb. Average treatment duration was 909 days. At final follow up, 81% (14/17) of limbs had the mechanical axis in zone 1, with the remaining 18% (3/17) in zone 2. No patient/limb underwent subsequent distal femur or proximal tibia osteotomy for coronal plane alignment. Children with achondroplasia can successfully be treated with hemiepiphysiodesis to correct coronal plane deformities at the distal femur and proximal tibia. Using this technique, no patient in our series required an osteotomy for genu varum/valgum. Therapeutic level IV, Case series.

The V1 transition ratio: electrocardiographic criterion for predicting the success of ablation for outflow tract premature ventricular contractions

Abstract Funding Acknowledgements Type of funding sources: None. Background Several electrocardiographic (ECG) criteria have been proposed for distinguishing left from right ventricular outflow tract premature ventricular contractions (OTPVCs) origins. However, electrocardiographic criteria predicting successful catheter ablation (CA) for OTPVCs are still unknown regardless of right and left ventricular origins. Methods We enrolled 63 patients who underwent CA for OTPVCs from September 2020 to August 2022, except patients with bundle branch block and axis deviation in 12-lead ECG. Radiofrequency catheter ablation (RFCA) was performed using 3D-mapping system and irrigation catheter. Electrocardiographic parameters of successful and unsuccessful patients were retrospectively analyzed. The transition ratios were calculated by the percentage R-wave during PVC (R/R+S) PVC divided by the percentage R-wave in sinus rhythm (R/R+S) SR . Success of CA for OTPVCs was defined as absence of targeted PVCs during all follow up visits and PVC burden <5% on follow-up period. Results 54 patients (85.7%) were success and 9 patients (14.3%) were unsuccess. Age, sex, Ejection Fraction (EF) and the burden of PVCs before CA were similar between 2 group. (Age: 50±15 vs 54±12 years, p=0.51, male: 46.3 vs 53.7%, p=0.73, EF: 66(58-73) vs 69(59-74), p=0.52, burden of PVCs: 22(17-29) vs 15(13-33)%, p=0.45). V1 transition ratio of unsuccessful group was significantly higher than successful group. (0.70(0.32-1.49) vs 1.55(1.09-9.37), p=0.013) V2 and V3 transition ratios were not significantly different between the two groups. The best cutoff values of V1 transition ratio were 1.0 (AUC 0.78, 95%CI: 0.61-0.94, sensitivity 0.70, specificity 0.88). Conclusion V1 transition ratio>1.0 is more likely to be associated with a higher rate of RFCA failure of OTPVCs.

Myocardial Perfusion Scintigraphy in a Patient With Transposition of Great Arteries Post-Atrial Switch Surgery.

We report a case of a 33-year-old woman who underwent stress and rest myocardial perfusion scintigraphy (MPS) to exclude coronary artery disease. MPS images showed an apparent dextrocardia with a right-sided septal wall uptake. The electrocardiograph showed a right axis deviation with dominant R waves at leads aVR and V1. Upon retrieval of the patient's medical records, she had an underlying transposition of great arteries and underwent a Senning atrial switch surgery. Hence, the MPS images demonstrated a prominent right ventricular wall due to its function as the "systemic" ventricle with minimal uptake in the "pulmonary" left ventricle.

Age and Sex Determine Electrocardiogram Parameters in the Octodon degus.

Cardiovascular diseases represent the leading cause of mortality and morbidity worldwide, and age is an important risk factor. Preclinical models provide supportive evidence toward age-related cardiac changes, as well as allow for the study of pathological aspects of the disease. In the present work, we evaluated the electrocardiogram (ECG) recording in the O. degus during the aging process in both females and males. Taking into account the age and sex, our study provides the normal ranges for the heart rate, duration and voltage of the ECG waves and intervals, as well as electrical axis deviation. We found that the QRS complex duration and QTc significantly increased with age, whereas the heart rate significantly decreased. On the other hand, the P wave, PR and QTc segments durations, S wave voltage and electrical axis were found to be significantly different between males and females. The heart rhythm was also altered in aged animals, resulting in an increased incidence of arrhythmias, especially in males. Based on these results, we suggest that this rodent model could be useful for cardiovascular research, including impacts of aging and biological sex.

P180 EXTREMELY WIDE QRS TACHYCARDIA IN SEVERE HYPERKALEMIA: THE IMPORTANCE OF MONITORING MRA THERAPY

Abstract Although uncommon in the general population, hyperkalemia can affect up to 50% of patients with heart failure who are receiving MRA and/or are affected by CKD . Since potassium is the most abundant intracellular cation, hyperkaliemia causes a profound change in action potential, which manifests as expected electrocardiographic changes (lower voltage P wave, AV block, wide QRS, high voltage T wave) and arrhythmias. Clinic case. A 77–year–old woman was admitted to ED for dyspnea. She had a medical history of stage 3 CKD and a HFrEF with a recent admission in medical department for worsening congestion, from which was dimitted with a supratherapeutic dose of MRA (canrenone 300 mg/die). Physical examination at the admission excluded signs of central or peripheral congestion . An EKG was performed and revealed an heart rate of 95 beats per minute and extremely wide QRS (280 ms). Contextually, a blood gas analysis showed high potassium level (K 9 mmol/l) and metabolic acidosis. Due to the inability to demonstrate the presence of P wave and a regular A–V conduction, a differential diagnosis between a VT and a SVT with a wide QRS was required. The presence of a fusion beat, a negative concordance of QRS in the precordials derivation, and an extreme right axis deviation led to a diagnosis of slow VT. Cuncurrently with the onset of hyperkalemia therapy, an ECV with sinus rhythm restoration was done. The following EKGs showed expected electrical changes based on the measured potassium level. After ECV with K 8 mmol/l: QRS remained wide (180ms) with an heart rate of 65 beats per minute in the presence of possible junctional rhythm or sino–ventricular rhythm, which is sometimes described in hyperkalemia as an expression of atrial inectability with the exception of the conduction fibers. After 1 hour with K 6.3 mmol/l: QRS of normal duration with an HR of 60 bpm and a sinus rhythm but with low voltage P wave and concomitant AV block of I grade that was gradually restored with the normalization of potassium levels after canrenone suspension. Because the numerous side effects of hyperkaliemia careful monitoring of MRA therapy and potassium level plays a critical role in the prevention and diagnosis of arrhythmias and EKG changes in patients with HFrEF.

Gradual on top-of-acute correction of neglected adolescent tibia vara by percutaneous tibial osteotomy and two-ring Ilizarov frame.

This study aims to assess the effect of gradual correction after acute translation of the tibia in tibia vara using a two-ring Ilizarov frame on the correction of mechanical axis deviation (MAD), union time, and the rate of complications. Between September 2018 and January 2021, a total of 30 patients (25 males, 5 females; mean age: 20±5 years; range, 15 to 25 years) with adolescent tibia vara were included. The patients had a transverse fibular ostectomy and percutaneous tibial osteotomy below the level of the tibial tuberosity. Acute correction of the rotation deformity combined with acute translation was done. A two-ring Ilizarov frame with a medial distractor and two lateral hinges were used to fix the osteotomy and the coronal plane deformity was gradually corrected. The mean follow-up was 24±4 months. All patients had improvement in the mechanical medial proximal tibial angle (mMPTA) and MAD postoperatively. There was an improvement in the Hospital for Special Surgery knee score at one year postoperatively. No neurovascular complications or union complications were observed. Acute translation followed by gradual angulation of the proximal tibia in cases with adolescent tibia vara yields better correction of the mechanical axis with good functional and radiological outcomes.

P351 FATAL RECURRING SYSTEMIC THROMBOEMBOLYSM IN A PATIENT WITH CARDIAC AL AMYLOIDOSIS WITHOUT EVIDENCE OF ATRIAL FIBRILLATION

Abstract Backgound: Cardiac amyloidosis is associated with an increased thromboembolic risk. While the need to anticoagulate patients in atrial fibrillation regardless of the CHA2DS2–VASc score is evident, it is not clear whether and which patients in sinus rhythm should be treated with anticoagulant drugs Case Presentation A 51–year–old man presented with repeated episodes of chest pain and exertional dyspnea. The ECG showed synus rhythm, left–axis deviation, 1st degree AV–block, left anterior hemiblock and no significant anomalies of ventricular repolarisation. Transthoracic echocardiography revealed markedly thickened left ventricular (IN) walls (maximum interventricular septum dimension 18 mm) with a granular–sparkling appearance of the myocardium, bi–atrial enlargement, preserved LV ejection fraction (EF 52%), restrictive mitral flow pattern with a very small A–wave, thickened interatrial septum and atrio– ventricular valves; circumferential pericardial effusion ( maximum 11mm). Laboratory tests showed an increase in troponin and NTproBNP levels and serum and urine immunoelectrophoresis showed a monoclonal component in zone kappa. A periumbilical fat biopsy was negative for amyloidosis so the patient underwent an endomyocardial biopsy which showed positive Congo red, and immunohistochemistry positive for kappa light chains and negative for transthyretin. A diagnosis of cardiac amyloidosis AL was then made and the patient was referred to the hematologist to perform specific therapy. One week after discharge he was hospitalized for acute pain in the lower limbs due to acute thrombosis of the left common femoral artery treated with Fogarty embolectomy. Discharged in therapy with low molecular weight heparin after a few days he was again symptomatic for pain in the lower limbs and went to the emergency room where he died of electromechanical dissociation. Conclusions Our case demonstrates that cardiac AL amyloidosis is associated with an increased thromboembolic risk, irrespective of the presence of atrial fibrillation, for the hematological disease itself and for the infiltration of the atrium by the amyloid substance. This suggests that in selected cases, with reduced A–wave amplitude and evidence of impaired atrial mechanics, empirical anticoagulation should be considered even in sinus rhythm.

Study on Error Compensation Method of Online Roll Profile Measurement

Flatness and surface quality are important quality indexes of strip steel, and roll wear will directly affect the product's flatness and surface quality. Online roll profile measurement technology can obtain the information of roll profile in real time, guide the optimization of roll change rhythm, and improve the flatness control ability of rolling mill and surface quality of strip product. However, the error caused by roll displacement, clearance, roll thermal crown, and other factors is usually the same order of magnitude as the roll shape or roll wear, or even one order of magnitude higher. So error compensation is the key to ensuring the accuracy of online roll profile measurement. Herein, the position measurement technology of the roll bearing block is considered in the online roll profile measurement, and the measurement error caused by the deviation of the roll axis is separated. The thermal crown model is established to separate the measurement errors caused by the thermal crown. The error compensation model of online roll profile measurement is established, and the simulation calculation is carried out. This error compensation method is of great significance to improve the accuracy of online roll profile measurement and realize the fine management of mill roll in service.

Double Opposing U Suture For Septal Multiple Axis Deviations: A Multi-Vectoral Approach.

Septal cartilage deviations comprise the majority of deformities related to revision rhinoplasty operations. Therefore, the primary operation should be as eventless and durable as possible. Many techniques have been suggested, but most present with a monoplanar correction and fixation of the septum. This study aims to demonstrate a suture method that fixates and broadens the deviated septum. This method employs a single-stranded suture passing below the spinal periosteum, pulling the posterior and anterior portions of the septal base separately. It was utilized in 1578 patients, of which only 36 necessitated a revision of septoplasty in the past 11 years (2010-2021). With a revision rate of 2.29%, this method should be considered a preferable choice over many techniques described in the literature.

A Torn Discoid Lateral Meniscus Impacts Lower-Limb Alignment Regardless of Age: Surgical Treatment May Not Be Appropriate for an Asymptomatic Discoid Lateral Meniscus.

A discoid lateral meniscus (DLM) is more prone to tear, and treatment of this condition is challenging. The purpose of the present study was to investigate (1) whether a torn DLM is associated with more varus alignment than a torn semilunar lateral meniscus (SLM) and (2) whether the lower-limb alignment associated with a torn DLM changes with age. Consecutive patients who underwent arthroscopic knee surgery for a torn lateral meniscus were included. Patients with a torn DLM (confirmed on arthroscopy) were allocated to the DLM group; those with a torn SLM were allocated to the SLM group. After strict screening according to the inclusion and exclusion criteria, 436 and 423 patients were included in the DLM and SLM groups, respectively. The mechanical axis deviation (MAD), hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle, and medial proximal tibial angle were compared between the 2 groups after propensity score matching. Additionally, the correlation of the HKA and MAD with age was evaluated within the DLM group. After propensity score matching, all baseline characteristics were well balanced between the 2 groups. The DLM group had significantly more varus alignment than the SLM group (MAD: 3.6 mm ± 9.6 mm versus 1.1 mm ± 10.3 mm, respectively, p = 0.001; HKA: 179.1° ± 2.9° versus 179.9° ± 3.0°, respectively, p = 0.001). Within the DLM group, the MAD (R = 0.10, p = 0.032) and HKA (R = -0.13, p = 0.007) had a weak correlation with age. Patients with a torn DLM had more varus knee alignment than those with a torn SLM, and this trend did not increase with age after minimizing the effects of osteoarthritis. Therefore, surgical treatment may not be appropriate for asymptomatic DLM. Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

New characteristics in ECG induced by ultra-high altitude hypoxia

The partial pressure of oxygen decreases significantly with altitude elevation. Adaptive pathophysiological reactions and non-special electrocardiogram(ECG) changes are common in healthy individuals who are exposed to high altitude environments (greater than2500 m). However, previous literatures reported did not fully reflect the characteristics of the plateau ECG changes. A 27-year-old man living for more than 400 days at an ultra-high altitude (5400 m) presented with a rare but urgent ECG features including a right deviation of the electrical axis, pathological Q-wave, a poor increase of R-wave, and T-wave bidirectional/inversion. The erythrocytosis, pulmonary artery pressure, right heart overload and the reversible dynamic evolution of ECGs were gradually improved after he was rapidly transferred to the a low-altitude hospital. This study may provide a new feature of high-altitude induced ECG changes, indicate the potential mechanismand therapeutic value.

Assessment of Electrocardiographic Changes and Associated Factors Among Thyroid Dysfunction Patients Attending Jimma Medical Center, Southwest Ethiopia: A Cross-Sectional Study.

Thyroid dysfunction (TD) is a metabolic manifestation related to either excessive or inadequate production of thyroid hormones. It has been widely proven to have comorbidities like cardiovascular disease. An electrocardiograph is a simple investigative instrument used to assess cardiac status to prevent complications in the later stages of the disease. To assess electrocardiogram (ECG) changes and associated factors among TD patients. An institution-based cross-sectional study was conducted among 273 TD patients attending Jimma Medical Center from October 11 to December 11, 2021. An ECG tool with 12 leads was used to assess the cardiac status, and a semi-structured questionnaire was used to assess sociodemographic, behavioral, and comorbidity variables. Bodyweight, height, waist circumference (WC), hip circumference (HC), and blood pressure variables were recorded, and body mass index (BMI) and waist-to-hip ratio (WHR) were calculated. Out of a total of 273 analyzed and interpreted ECG results by the cardiologists, 185 (67.8%) had ECG alterations. The most common types of ECG changes were arrhythmia 153 (56%), followed by myocardial infarction 74 (27.1%), ventricular hypertrophy [left 20 (7.3%) and right 15 (5.5%)], left atrial enlargement 3 (1%), axis deviation, and other abnormalities 24 (8.8%) and 18 (6.6%), respectively. The identified predictor variables for the ECG changes were the age group of 41 to 60 years old [AOR = 2.5, 95% CI: 1.25, 5.05], being female [AOR = 2.7, 95% CI: 1.28, 5.59], having diabetes mellitus [AOR = 4.25, 95% CI: 1.6, 11.2], and not starting the treatment [AOR = 8.6, 95% CI: 3.45, 21.6]. This study revealed that the prevalence of ECG changes was high among TD patients. The most common type of ECG change observed was arrhythmia followed by myocardial infarction. The age range of 41-60 years old, being female, having diabetes mellitus, and not starting the treatment were significantly associated with the ECG changes. Implementing an efficient noninvasive screening of cardiac status can detect unrecognized and asymptomatic cardiac impairment in TD patients.

Loss of the Tbx5 gene in the ventricular conduction system induces spontaneous ventricular arrhythmias

The ventricular conduction system (VCS) and the working myocardium (WM) derive from the same myogenic progenitors during the embryonic development. The VCS development is regulated by numerous genes including the T-box transcription factor 5 (Tbx5). In human, Tbx5 mutations cause Holt-Oram syndrome, an autosomal dominant disease associated with heart abnormalities such as arrhythmias. In adult mice, the deletion of the Tbx5 gene provoked a slowing of ventricular conduction due to a loss of the gap junction Connexin 40 and dysfunction of cardiac channels. However, it is still unknown how Tbx5 deletion affects the development and the function of the VCS. The aim is to study the consequences of the Tbx5 deletion in embryonic progenitors of the ventricular conduction system on cardiac function in adult mice. Conditional deletion of Tbx5 alleles in mice was induced by expressing the Cre recombinase under the control of the Connexin 40 (Cx40) gene. We studied two groups of mutants: Tbx5 deletion at embryonic days E13-14 targeting both the ventricular conduction system and the working myocardium (“VCS + WM” group; n = 40) and mice deleted at E18-P2 targeting only the ventricular conduction system (“VCS” group; n = 17). Surface ECGs were achieved monthly until 3 months of age, when immunostaining was performed on the left VCS. Immunostaining showed a reduced expression of the two major connexines in the ventricle (Cx40 and Cx43) and a reduced number of conductive cells in both mutants, suggesting a defective maturation of the VCS (Fig. 1). Furthermore, the loss of Cx43 was correlated with that of Tbx5, reflecting a direct transcriptional effect. Surface ECG revealed a significant increase of the ventricular activation duration in both mutants (P < 0.01). Moreover, premature ventricular contractions (PVCs) and a left QRS axis deviation were observed in both mutants. Finally, these PVCs disappeared with age in both mutants under resting conditions, and are unmasked when the heart is challenged with a β-1 adrenergic agonist. Our results provide new insights into Tbx5 targets in the VCS. Tbx5 deletion impacts the maturation and the anatomy of the VCS as proved by the deviation of the ventricular electrical axis, which even occurs when the VCS is already formed. Tbx5 appears to have a direct impact on the Gja1 gene, encoding the gap junction Cx43, which is reduced at the junction between the VCS and the WM in both mutants and may be responsible for PVCs.

Treatment of Angular Deformity and Limb Length Discrepancy With a Retrograde Femur Magnetic Intramedullary Nail: A Fixator-assisted, Blocking Screw Technique.

Fixator-assisted nailing techniques that incorporate magnetic internal lengthening nails (MILNs) permit acute deformity correction and then gradual limb lengthening without needing postoperative external fixators. We sought to investigate the safety and accuracy of a fixator-assisted, blocking screw technique using retrograde MILNs for the correction of LLD and limb malalignment. Forty-one patients (13 patients with genu varum and 28 patients with genu valgum) with LLD treated with fixator-assisted, blocking screw retrograde MILN reconstruction were included. Preoperative LLD, mechanical axis deviation, and joint orientation angles were compared with values at the end of treatment, and bone healing indices were calculated. Perioperative complications were tracked. Preoperatively, the mean mechanical lateral distal femoral angle of the varus cohort was 98 ± 12°, whereas the mean lateral distal femoral angle of the valgus cohort was 82±4°. Both cohorts had an average 3-cm LLD. 99% of the planned limb lengthening was achieved. Final LDFAs were 91 ± 6° and 89 ± 4° in the varus and valgus cohorts, respectively, and the limb mechanical axis angles were normalized. 10 patients underwent a total of 21 returns to the operating room. Most commonly, this involved percutaneous injection of bone marrow aspirate concentrate to bone regenerate exhibiting delayed union (6 patients). The use of a retrograde MILN with a fixator-assisted, blocking screw technique is an effective means of acute deformity correction and gradual limb lengthening through minimal incisions. The accuracy of deformity correction relies on intraoperative execution of the appropriate nail start site, osteotomy location, and placement of blocking screws.

PO-05-147 RIGHT ON Q: WIDE-COMPLEX TACHYCARDIA IN SETTING OF DEXTROPOSITION

Dextroposition is a rare cardiac malformation defined as rightward cardiac displacement with leftward apex, vs. dextrocardia, which is rightward base-axis orientation. We report the second known case of dextroposition with accessory pathway, presenting as preexcited atrial tachycardia. Abnormal anatomy complicates ECG localization and pathway ablation. N/A N/A A 50-year-old woman was admitted with respiratory distress due to EBV infection. Chest X-ray showed right-sided heart. A month later, she presented in wide-complex tachycardia, rate 205 bpm. She was cardioverted after minimal response to procainamide/adenosine. Post-cardioversion ECG showed short PR interval and preexcitation, confirming presence of accessory pathway. However, the wide-complex tachycardia had morphology identical to baseline, supporting preexcited atrial tachycardia over AVRT. Despite X-ray findings and reverse R-wave progression in precordial leads, presence of left axis deviation and initial negative deflection in aVR argued against dextrocardia. Moreover, aVR had negative T- and P-waves, findings associated with levocardia. Thus, dextroposition was suspected. Millstein and Arruda criteria suggested posteroseptal accessory pathway, but no data on their applicability in right-sided heart exist. EP study was performed. Eccentric VA conduction was noted. Earliest activation was at proximal coronary sinus. During isoproterenol infusion, patient went into atrial tachycardia, cycle length 420ms. Multiple AT foci were identified, including at right atrial appendage and tricuspid annulus. During ablation, patient developed atrial fibrillation with preexcited RR <250ms, confirming high-risk accessory pathway. Given numerous AT foci and high risk, it was decided to focus on pathway over tachycardia sites. Pathway was successfully ablated at ostia of coronary sinus and middle cardiac vein. One prior case of accessory pathway ablation in dextroposition has been reported. This patient had left lateral pathway and multiple congenital abnormalities including lung hypoplasia. While our patient was found to have multifocal atrial tachycardia, she had no clinical or radiographic lung disease. ECG changes in dextroposition are less predictable than in dextrocardia; they vary with cardiac rotation, axis position, and lead position. Comorbid accessory pathway is rare; ECG-anatomy relationship is ill-defined. Structural abnormalities pose individual challenges during electrophysiologic procedures.

Nozzle Jet Deviation from Bucket Pitch Circle’s Effect on the Stability and Efficiency of Pelton Turbine

During the operation of a Pelton turbine, the centerline of the nozzle jet may deviate from the bucket pitch circle due to the low installation and maintenance accuracy, which will reduce the operating efficiency and the stability of the turbine and even cause severe vibrations and damages. Based on the VOF (Volume of Fluid) two-phase flow model and the SST k-ω turbulence model, the flow characteristics of a Pelton turbine were simulated with the nozzle jet deviating from the bucket pitch circle. The pressure pulsation inside the bucket and the force distribution of the runner were obtained, the turbine oscillation and efficiency were measured before and after the jet deviation, and the effects of the radial and axial deviations on the stability and efficiency of the Pelton turbine were analyzed. The results show that both the radial and axial deviations of the jet cause a significant increase in the axial force and the pressure pulsation amplitude of the turbine; the radial and tangential forces on the runner are slightly reduced; the maximum axial force on the runner is increased by 4 times and 2 times, respectively, after the axial and radial deviations within the maximum value allowed by the industry standard; and the efficiency of the turbine is reduced by 0.4% and 0.3%, respectively. The maximum relative amplitude of pressure pulsation in the radial offset case appears in the center of the bucket blade, while the axial offset case causes uneven pressure distribution on both sides of the diverter blade, uneven force on the bucket blade of the runner, and fatigue damage. By comparing the operation of the runner under the two offset cases, we can find that the axial offset of the jet has a greater impact on the stability of the runner than the radial offset, and the unit is more prone to vibration, increasing the risk of the unit lifting.

Chromatic confocal sensor-based on-machine measurement for microstructured optical surfaces featuring a self-aligned spiral center.

Chromatic confocal sensor-based on-machine measurement is effective for identifying and compensating for form errors of the ultra-precisely machined components. In this study, an on-machine measurement system was developed for an ultra-precision diamond turning machine to generate microstructured optical surfaces, for which the sensor probe adopts a uniform spiral scanning motion. To avoid the tedious spiral center alignment, a self-alignment method was proposed without additional equipment or artefact, which identified the deviation of the optical axis to the spindle axis by matching the measured surface points and the designed surface. The feasibility of the proposed method was demonstrated by numerical simulation with full consideration of noises and system dynamics. Practically, taking a typical microstructured surface as an example, the on-machine measured points were reconstructed after calibrating the alignment deviation, which was then verified by off-machine white light interferometry measurement. Avoiding tedious operations and special artefacts may significantly simplify the on-machine measurement process, thereby greatly improving the efficiency and flexibility for the measurement.

Upper body posture in Latin American dancers: a quantitative cross-sectional study comparing different postures

BackgroundIn Latin American dance sport (LD), the shoulder girdle and the torso area are particularly stressed due to the dance style specific requirements. The aim of the study was to define differences in various dance specific upper body postures in Latin American dancers and to show gender-specific differences.MethodsThree dimensional back scans were performed in n = 49 dancers (28 f/21 m). Five typical trunk positions in Latin American dance (habitual standing and 4 dance specific positions, P1–P5) were compared with each other. Statistical differences were calculated using the Man-Whitney U test, Friedmann test, Conover-Iman test and a Bonferroni-Holm correction.ResultsSignificant gender differences were found in P2, P3 and P4 (p ≤ 0.01–0.001). In P5, the frontal trunk decline, the axis deviation, the standard deviation of the rotation, the kyphosis angle and the shoulder as well as the pelvic rotation were also significantly different. The comparison of the postures showed significant differences between postures 1–5 (p ≤ 0.01–0.001) in the males, (scapular height, right and left scapular angles and pelvic torsion). Similar results were observed for the female dancers, with only the parameters of frontal trunk decline with the lordosis angle as well as the right and left scapular angles being non-significant.ConclusionsThis study is an approach to better understand the involved muscular structures in LD. Performing LD changes the static parameters of the upper body statics. Further projects are needed to analyse the field of dance even more thoroughly.

Prediction of lining upward movement during shield tunneling using machine learning algorithms and field monitoring data

During the construction of shield tunnels, the tunnel lining often has the problem of local or overall upward movement in soft soil areas. Excessive upward movement will lead to lining dislocation, cracks, damage, and even axis deviation. This paper elaborates on how to predict the process of tunnel lining upward movement using machine learning algorithms and field monitoring data systematically. First, fourteen input variables including shield operational parameters, tunnel geometry, geological conditions and anomalous condition are considered to predict the upward displacement of twelve output variables that represent the process of the upward movement of the tunnel lining. In addition, 80% field monitoring data (81 datasets) are selected randomly as the training set, and the remaining 20% (20 datasets) are the test set. Then, the average of 5-fold cross validation mean absolute error is regarded as the fitness function of optimization algorithms to find the optimal hyper-parameters. Finally, the prediction performance of four machine learning (ML) algorithms back-propagation neural network (BPNN), general regression neural network (GRNN), extreme learning machine (ELM), and support vector machine (SVM) optimized by particle swarm optimization (PSO) and genetic algorithm (GA) were compared. All ML algorithms except BPNN predicted successfully the trend of upward movement of tunnel lining. In particular, PSO-GRNN accurately captures the evolution of upward displacement in different periods of each ring with the lowest errors and the largest correlation coefficient values.

Frequency and Characterisation of Anomalies and Fractures of the Caudal Spine in Sheep with Undocked Tails.

As tails are often docked within the first days of life, studies investigating tail malformations and injuries in sheep do not exist thus far. To address this gap in the literature, this research aimed to analyse the occurrence of vertebral anomalies and fractures in the tail within an undocked Merinoland sheep population. At 14 weeks of age, the caudal spines of 216 undocked Merinoland lambs was radiographically examined, and tail length and circumference were measured. Anomalies were documented and statistical correlation and model calculations were performed. The occurrence of block vertebrae was observed in 12.96% and wedged vertebrae in 8.33% of the sample. Of the animals, 59 (27.31%) exhibited at least one vertebral fracture, which were observed in the middle and caudal third of the tail. A significant correlation was found between the occurrence of fractures and tail length (r = 0.168) and number of vertebrae (r = 0.155). Conversely, the presence of block and wedged vertebrae was not significantly correlated with tail length, circumference, or number of vertebrae. Only the sex showed significant differences in the probability of axis deviation. These results emphasize the importance of breeding for short tails to avoid fractures.