Total Rotation Research Articles

P-756 Assessment of an oocyte retrieval simulation training program for residents: from training to clinical practice

Abstract Study question Does an oocyte retrieval simulation training program (ORSTP) improve the clinical performance of residents ? Summary answer The ORSTP does not improve the residents’ clinical performance, but it helps lower their stress and improve their confidence during training. What is known already Simulation training currently plays an important role in medical education, and is recommended for residents and fellows in training by many international societies. Oocyte retrieval (OR) is an invasive procedure that has a direct impact on the success rate of an IVF cycle. Studies have shown that residents and fellows favor an ORSTP and find it beneficial, but few studies have assessed the actual impact of that training on their performance in clinical practice. Study design, size, duration We performed a prospective comparative study at the Angers university Hospital. We included all OR performed by residents between May 2017 and November 2020. The Simulation (S) group included OR performed by residents who had undergone an ORSTP before performing them on patients (n = 422), and the control (C) group included OR performed by residents who had not received simulation training, but had started practicing progressively on patients with attending physicians (n = 329). Participants/materials, setting, methods Residents in the S group answered a questionnaire about their impressions at the end of the rotation. Our main outcome measures were the OR rate (ORR) (number of oocytes collected/number of follicles aspirated) during the first 3 months of the rotation (total rotation duration is 6 months) in the two groups, and the satisfaction rate of residents in the S group. Secondary outcomes included ORR during each month and at the end of the rotation. Main results and the role of chance In the S group, 6 residents aspirated 657 ovaries while in the C group, 5 residents aspirated 508 ovaries. The mean ORR during the first 3 months of rotation were comparable between the S and C groups (59% vs 58%, p = 0.68). ORR during the first and second month, and at the end of the rotation were also comparable between the S and C groups (54% vs 63% (p = 0.13), 58% vs 59% (p = 0.82) et 58% vs 58% (p = 0.9), respectively). There was no significant difference in the rate of failed OR (3.3% vs 1.8%, p = 0.13) between the S and C group. There was one case of hemoperitoneum in both groups (p = 0.81). Finally, the satisfaction rate of residents in the S group was 83%. Out of the 6 residents in the S group, only one reported being stressed before the OR, and 5 were confident about the outcomes of their retrievals. Limitations, reasons for caution Our study is limited by the monocentric design and the limited number of residents included. Wider implications of the findings Even though the ORSTP did not improve the residents’ clinical performance, it had a positive psychological impact. Our findings need to be confirmed on a larger scale and in different settings in order to establish whether the ORSTP should be systematically added to the residents training programs. Trial registration number NCT0370025

Comparison of Shoulder Total Rotational Range of Motion and External to Internal Rotation Strength Ratio between Assembly Line Workers with and without Subacromial Pain Syndrome

Background Subacromial pain syndrome (SAPS) is one of the causes of shoulder pain in workers performing repetitive upper extremity movements. However, there have been no studies on physical characteristics such as shoulder total rotational range of motion (ROM) and external to internal rotation muscle strength ratio of workers. Purpose The purpose of this study was to compare the total rotational ROM and external to internal rotation muscle strength ratio in workers with and without SAPS. Study design A cross-sectional study Methods This study included 35 workers with SAPS and 32 workers without SAPS. The total rotational ROM were measured using Smart KEMA motion sensor, and external to internal rotation muscle strength were measured using Smart KEMA pulling sensor. Results The results showed that there were significant differences in the total rotation ROM between the groups (<italic>p</italic>&lt;0.05). However, no significant difference was found in the external to internal rotation muscle strength ratio (<italic>p</italic>&gt;0.05). Conclusions Assembly line workers with SAPS had limited total rotational ROM. However, the ratio of external to internal rotation muscle strength ratio was not different for workers without SAPS. These characteristics can be considered factors that should be considered in evaluating workers with SAPS and establishing a treatment plan.

Twisting of transobturator midurethral slings: does it matter?

We assessed rotation/twisting of transobturator midurethral slings (TOTs) and tested for associations with de novo chronic pain and voiding dysfunction. A retrospective pilot study including patients seen after Monarc™ TOT surgery at a single tertiary hospital in 2005-2016. Patients underwent an interview, clinical examination, uroflowmetry and 4D pelvic floor ultrasound. Volume datasets were analyzed blinded against all other data. Sling rotation/twisting was evaluated in volumes obtained at rest. The sling axis was measured relative to the vertical in the midline and in the most lateral parasagittal slice. Total sling rotation was calculated by summation of absolute angle differences between midline and lateral angles. "Corkscrew" rotation was noted when direction of rotation was opposite on the contra-lateral side. The study included 215 patients. Fifty-two (24%) were excluded, leaving 163. Mean age was 57 years (28-87; SD 12), mean BMI 29.4 kg/m2 (18.3-47.4, SD 6). Follow-up was at a median of 17 months (IQR 11-27). Chronic de novo pain was reported by 15 women (9%; dyspareunia by 11 and pelvic/vaginal pain by 4). On imaging, mean total sling rotation was 144° (12-335, SD 56). In the majority (n = 103, 63%) it rotated counter-clockwise from its midline position and in 30 (18%) it rotated clockwise. "Corkscrew" rotation was noted in 30 (18%). De novo chronic pain was associated with lower BMI and vaginal sling exposure but not with sling rotation. The latter was not found to be associated with voiding dysfunction either. Monarc™ TOTs rotate considerably throughout their course. The degree of twisting or rotation and its direction was not found to be associated with de novo postoperative chronic pain or voiding dysfunction.

Analysis of cervical and upper thoracic spinal segmental rotation angles during end-range neck rotation: Comparison with and without neck pain

ABSTRACT Background Neck pain is a common manifestation of musculoskeletal disorders of the cervical and thoracic spine. Manual therapy interventions to the thoracic spine are recommended for treating patients with several types of neck pain. However, only a few studies have investigated the thoracic spine mobility associated with neck movement. Objectives Compare cervical and upper thoracic rotation angles in subjects with and without neck pain. Methods The subjects included nine individuals who experienced neck pain (pain, Group P) and 11 who did not (non-pain, Group N). The rotation angle was measured using MRI. The imaging limb position was at 90% of the maximum neck rotation. The MR images were analyzed using image analysis software to calculate the rotation angle of C1 to Th3. The rotation angle of the segment was then calculated by subtracting the rotation angle corresponding to the lower vertebra from that corresponding to the upper vertebra. The total rotation of each segment was calculated as the sum of the right and left rotation angle. Then, the segmental rotation angles were compared between groups. Results/findings The rotation angles of C3-C4, C7-Th1, and Th1-Th2 were significantly smaller in Group P than in Group N, and C5-C6 and C6-C7 were significantly larger in Group P than in Group N. There was no statistical difference in rotational angle at all other spinal levels measured. Conclusions The results of this study indicate subjects with neck pain had hypermobility of the lower cervical spine and hypomobility of the cervico-thoracic junction and upper thoracic spine compared with subjects without neck pain. These results add to current understanding of biomechanical factors that may be related to neck pain.

IRotate: Active Visual SLAM for Omnidirectional Robots

In this paper, we present an active visual SLAM approach for omnidirectional robots. The goal is to generate control commands that allow such a robot to simultaneously localize itself and map an unknown environment while maximizing the amount of information gained and consuming as low energy as possible. Leveraging the robot’s independent translation and rotation control, we introduce a multi-layered approach for active V-SLAM. The top layer decides on informative goal locations and generates highly informative paths to them. The second and third layers actively re-plan and execute the path, exploiting the continuously updated map and local features information. Moreover, we introduce two utility formulations to account for the presence of obstacles in the field of view and the robot’s location. Through rigorous simulations, real robot experiments, and comparisons with state-of-the-art methods, we demonstrate that our approach achieves similar coverage results with lesser overall map entropy. This is obtained while keeping the traversed distance up to 39% shorter than the other methods and without increasing the wheels’ total rotation amount. Code and implementation details are provided as open-source, and all the generated data is available online for consultation.

Rotation of Stresses in French Wheel Tracking Test

The main function of a pavement is to distribute the traffic-induced load over its different layers. While the flexible pavement design methods are based on a linear elastic calculation, the real behavior of the different layers is highly non-linear and elastic. They can also, in some cases, be plastic and viscous. This research aims to develop a three-dimensional numerical model that is closely similar to the test FWTT conditions. The model will have a real geometry wheel footprint (rather than a rectangular shape). As a substitute for incremental loading, the wheel movement during its passage over the specimen will be simulated by a horizontal displacement. These important characteristics of the model represent the novelty and the major difference between the current research and previous studies. The current model, which is based on the finite elements method, uses Abaqus software and a viscoelastic constitutive model. The materials' viscoelastic properties have been described by the Prony series, also called the relaxation modulus, which is a function of time. This parameter can be defined in most computer-aided engineering (CAE) software. The procedure for calculating the Prony series from experimental data is explained. The results obtained agree with the stress signal amplitude, the stress rotation principal, and the total displacement rotation when the load approaches the node considered and located in the middle of the specimen. Doi: 10.28991/CEJ-2022-08-03-03 Full Text: PDF

Preoperative opioid usage predicts markedly inferior outcomes 2 years after reverse total shoulder arthroplasty.

Reverse total shoulder arthroplasty (RTSA) has proved to be a highly effective treatment for rotator cuff-deficient conditions and other end-stage shoulder pathologies. With value-based care emerging, identifying predictive factors of outcomes is of great interest. Although preoperative opioid use has been shown to predict inferior outcomes after anatomic total shoulder arthroplasty and rotator cuff repair, there is a paucity of data regarding its effect on outcomes after RTSA. We analyzed a series of RTSAs to determine the influence of preoperative opioid use on clinical and radiographic outcomes at a minimum of 2 years' follow-up. A retrospective review of primary RTSA patient data revealed 264 patients with ≥2 years of clinical and radiographic follow-up. Patients were classified as preoperative opioid users (71 patients) if they had taken narcotic pain medication for a minimum of 3 months prior to surgery or as opioid naive (193 patients) at the time of surgery. Assessments included preoperative and postoperative visual analog scale pain scores, American Shoulder and Elbow Surgeons scores, strength, and range of motion, as well as complications and revisions. Radiographs were analyzed for signs of loosening or mechanical failure. The Mann-Whitney U and Fisher exact tests were used for comparisons between groups. Statistical significance was set at P < .05. The mean patient age was 69.9 years, and the mean follow-up time was 2.8 years. Opioid users were significantly younger (66.1 years vs. 70.7 years, P < .001) at the time of surgery and had significantly higher preoperative rates of mood disorders, chronic pain disorders, and disability status (all P < .05). Postoperatively, opioid users had inferior visual analog scale pain scores (2.59 vs. 1.25, P < .001), American Shoulder and Elbow Surgeons scores (63.2 vs. 75.2, P < .001), active forward elevation (P < .001), and internal and external rotational shoulder strength (all P < .05) compared with opioid-naive patients. Periprosthetic radiolucency (8.45% vs. 2.07%, P = .026) and subsequent revision arthroplasty (14.1% vs. 4.66%, P = .014) occurred more frequently in opioid users than in opioid-naive patients. Both groups improved from baseline preoperatively to most recent follow-up in terms of functional outcomes and pain. Preoperative opioid use portended markedly inferior clinical outcomes in patients undergoing RTSA. Additionally, opioid users had significantly increased rates of periprosthetic radiolucency and revision. Preoperative opioid use appears to be a significant marker for adverse outcomes after RTSA.

FRB 121102: Drastic changes in the burst polarization contrasts with the stability of the persistent emission

ABSTRACT We study milliarcsecond-scale properties of the persistent radio counterpart to FRB 121102 and investigate the spectro-polarimetric properties of a bright burst. For the former, we use European VLBI Network (EVN) observations in 2017 at 1.7 and 4.8 GHz. For the latter, we reanalyse the 1.7-GHz data from the 100-m Effelseberg telescope taken in 2016. These observations predate other polarimetric studies of FRB 121102, and yield the highest burst Faraday rotation measure (RM) to date, RM = 1.27 · 105 rad m−2, consistent with the decreasing RM trend. The fractional polarization of the burst emission is 15 per cent at 1.7 GHz. This can be reconciled with the high-fractional polarization at higher frequencies if the Faraday width of the burst environment is 150 rad m−2 – a bare 0.1 per cent of the total Faraday rotation. The width may originate from minor non-uniformities in the Faraday screen, or from effects in the emitting region itself. The upper limit on the persistent source size is 1 pc, barely consistent with a young supernova (SN) scenario. The flux variability limit of $\lt 10{{\ \rm per\ cent}}$ is not in favour of the young SN scenario, and challenges other interpretations as well. The fractional polarization of the faint persistent source is constrained at $\lt 25{{\ \rm per\ cent}}$ at 4.8 GHz ruling out a common origin with the highly polarized individual bursts.

Large amplitude forced vibrations of Timoshenko beams using coupled displacement field method

Forced vibration behaviour of a Timoshenko beam, with a concentrated mass at the centre, subjected to a concentrated harmonic force is investigated using the coupled displacement field method. The expressions for the transverse displacement were deduced from the assumed admissible function having a single term undetermined coefficient for a total rotation of the beam using the coupled displacement field method. The equation of motion for the forced vibration condition is derived using the principle of conservation of total energy. The Newmark method is employed to solve the equation of motion to obtain the dynamic response of the Timoshenko beam. The dynamic forced vibration response for the two boundary conditions, simply supported and clamped-clamped, is computed by applying the mode superposition technique for the obtained coupled displacement field equations. The authors also carried out the finite element analysis using ANSYS 21 software to validate the results obtained by the coupled displacement field method, and the results are also validated with the existing literature wherever possible. The obtained results are very closely matching with the FEM and other published results.

Transcutaneous Electrical Acustimulation Ameliorates Motion Sickness Induced by Rotary Chair in Healthy Subjects: A Prospective Randomized Crossover Study

ObjectivesMotion sickness (MS) is a common physiological response to real or virtual motion. The purpose of this study was to investigate the effects of transcutaneous electrical acustimulation (TEA) on MS and the underlying mechanisms in healthy subjects. Materials and MethodsA total of 50 healthy participants were recruited and randomly assigned into two groups to complete two separate sessions in a crossover study. A Coriolis rotary chair was used as a model to provoke severe MS. The total tolerable rotation time and Graybiel scoring scale were recorded. Gastric slow waves were detected by electrogastrogram. The autonomic nervous function, including the vagal activity, was evaluated by the analysis of heart rate variability derived from the electrocardiogram recording. The serum levels of arginine vasopressin (AVP) and norepinephrine (NE) were examined. ResultsOf note, 22 participants in TEA and only 11 participants in the sham-TEA session completed the entire five-rotation MS stimuli (p = 0.019). TEA significantly prolonged the total tolerable rotation time of MS stimuli (220.4 ± 11.59 vs 173.6 ± 12.3 seconds, p < 0.001) and lowered MS symptom scores (12.56 ± 2.03 vs 22.06 ± 3.0, p < 0.001). TEA improved the percentage of normal gastric slow waves, compared with sham-TEA (56.0 ± 2.1% vs 51.6 ± 2.0%, p = 0.033). TEA also significantly enhanced vagal activity compared with sham-TEA (0.41 ± 0.02 vs 0.31 ± 0.02, p < 0.001). In addition, the increased serum levels of AVP and NE on MS stimulation were markedly suppressed by TEA treatment, compared with sham-TEA (AVP, 56.791 ± 4.057 vs 79.312 ± 10.036 ng/mL, p = 0.033; NE, 0.388 ± 0.037 vs 0.501 ± 0.055 ng/mL, p = 0.021). ConclusionsNeedleless TEA is a potent therapeutic approach for severe MS, as it increases participants' tolerance and ameliorates MS symptoms, which may be attributed to the integrative effects of TEA on autonomic functions and neuroendocrine balance.

Total elbow arthroplasty using an augmented reality-assisted surgical technique.

Precision placement of implants in total elbow arthroplasty (TEA) using conventional surgical techniques can be difficult and riddled with errors. Modern technologies such as augmented reality (AR) and 3-dimensional (3D) printing have already found useful applications in many fields of medicine. We proposed a cutting-edge surgical technique, augmented reality total elbow arthroplasty (ARTEA), that uses AR and 3D printing to provide 3D information for intuitive preoperative planning. The purpose of this study was to evaluate the accuracy of humeral and ulnar component placement using ARTEA. Twelve upper extremities from human frozen cadavers were used for experiments performed in this study. We scanned the extremities via computed tomography prior to performing TEA to plan placement sites using computer simulations. The ARTEA technique was used to perform TEA surgery on 6 of the extremities, whereas conventional (non-ARTEA) techniques were used on the other 6 extremities. Computed tomography scanning was repeated after TEA completion, and the error between the planned and actual placements of humeral and ulnar components was calculated and compared. For humeral component placement, the mean positional error ± standard deviation of ARTEA vs. non-ARTEA was 1.4° ± 0.6° vs. 4.4° ± 0.9° in total rotation (P = .002) and 1.5 ± 0.6 mm vs. 8.6 ± 1.3 mm in total translation (P = .002). For ulnar component placement, the mean positional error ± standard deviation of ARTEA vs. non-ARTEA was 5.5° ± 3.1° vs. 19.5° ± 9.8° in total rotation (P=.004) and 1.5 ± 0.4 mm vs. 6.9 ± 1.6 mm in total translation (P = .002). Both rotational accuracy and translational accuracy were greater for joint components replaced using the ARTEA technique compared with the non-ARTEA technique (P < .05). Compared with conventional surgical techniques, ARTEA had greater accuracy in prosthetic implant placement when used to perform TEA.

Motion is Maintained at the Tibial and Polyethylene Component Interface in a Mobile-Bearing Total Ankle Arthroplasty at Mid and Long-Term Follow-Up

Category:Ankle Arthritis; Ankle; HindfootIntroduction/Purpose:Normal biomechanics of the ankle joint includes sagittal motion, but also anterior-posterior (AP) translation (1mm) as well as axial rotation (5-8 degrees). Sagittal motion is well described in total ankle arthroplasty (TAA), however, current understanding of mobile-bearing motion at the tibial-polyethylene interface in TAA is limited to AP motion and short-term data on axial rotation. The purpose of our study was to determine if polyethylene components maintain mobility adjacent to the tibial component in mobile bearing TAA at mid and long-term follow-up in both the sagittal and axial planes in patients more than 48 months post-operatively.Methods:Patients who were a minimum of 48 months postoperative from a third-generation mobile-bearing TAAwere identified. Fluoroscopic images perpendicular to the tibial component were saved at maximum internal and external rotation on AP, and the lateral images were saved in maximum plantarflexion and dorsiflexion. Sagittal range of motion and AP translation of the polyethylene component were measured from the lateral images. Axial rotation was determined by measuring the relative position of the two wires within the polyethylene component on AP internal and external rotation imaging. This relationship was compared to a table previously developed from fluoroscopic images taken at standardized degrees of axial rotation of a nonimplanted polyethylene with the associated length relationship of the two imbedded wires. Total axial motion was determined by the difference between angle value determined for maximum internal and external rotation.Results:Eight patients were included in this investigation, 5 (62.5%) were female and average age was 72.6 (range, 59-83) years. Time from surgery averaged 94.2 (range, 54.7-118.6) months. Total sagittal range of motion between the talar and the polyethylene component averaged 20.3 (range, 10-30) degrees. All patients (100%) maintained motion at the tibia-polyethylene interface. Axial motion for total internal and external rotation of the polyethylene component articulation on the tibial component averaged 5.3 (range, 2-12) degrees. AP translation of the polyethylene component relative to the tibial component averaged 1.1 (range, 0.4-2.6) mm during plantarflexion and dorsiflexion. There was no relationship between axial rotation or AP translation of the polyethylene component and ankle joint range of motion (P >.05).Conclusion:To our knowledge, this is the first investigation to measure axial and sagittal motion of the polyethylene component in mobile bearing TAA at the tibial implant interface in patients at mid and long-term follow-up. Based on our results, motion is maintained an average of 8 years post-operatively and concludes that a mobile-bearing TAA has the potential to fall within the parameters of normal polyaxial ankle motion several years after implantation. Such maintenance of motion may have a positive influence on gait pattern, polyethylene wear, joint reaction forces and implant longevity.

Morphology and morphometric study of dry scapula, with emphasis on the glenoid fossa and acromion process in Chennai city, South India

Background: The morphology and morphometry of the scapula and its glenoid fossa and acromion process play a significant role in the mechanics of shoulder joint. A variable morphology is found in glenoid fossa that has clinical implications. Aims and Objectives: The aim of the study was to evaluate the morphology and morphometry of dry scapula with emphasis on glenoid fossa and acromion process. Materials and Methods: A cross-sectional study was conducted at the department of anatomy, for a period of 6 months from January 2021 to June 2021. A total of 100 unpaired dry scapula were included in the study. The morphology and dimensions were measured. The dimensions were summarized as mean and standard deviation. Statistical analysis was done Chi-square test and student’s t-test based on the variable types. Results: Out of 100 scapulae studied, 48 were right sided and 52 were left sided. The mean of maximum length of the right scapula was 149.58±10.33 mm and the left side was 148.63±10.33 mm. Among the glenoid cavities, 54 were inverted comma shaped, 30 were pear shaped, and 16 were oval shaped. In one right-sided scapula Bony Spur Extends from Base of coracoid process to supra Scapular Notch. Conclusion: Size and shape of the glenoid cavity are directly related to the dislocation of shoulder joint and may affect the results of total shoulder arthroplasty and rotator cuff surgeries. The present study analyzed the morphological types and diameters of the glenoid cavity in adult scapulae to improve the efficacy and minimize the failure rates in shoulder arthroplasty particularly those involving the glenoid component of the shoulder joint.

Large Amplitude Free and Forced Vibrations of Functionally Graded Timoshenko Beams Using Coupled Displacement Field Method

AbstractThe large amplitude vibrations of functionally graded (FG) beams consisting of metal rich layers at the bottom, ceramic rich layers at the top, and a concentrated mass at the mid-span have been studied using coupled displacement field method. Unlike traditional methods, the coupled displacement field method reduces the 2n undetermined coefficients problem, one each for total rotation and transverse displacement distribution of the beam at n modes, to n undetermined coefficients using a coupling equation obtained from the minimization of potential energy principle. A suitable admissible function having single undetermined coefficient has been assumed for total rotation distribution and the corresponding transverse displacement distribution of the beam has been obtained at each mode for hinged-hinged and clamped-clamped FG beams. The equations of motion for large amplitude vibrations of FG beams at each mode in terms of the undetermined coefficients are derived from the conservation of total energy principle. The free vibration problem is solved using harmonic balance method whereas the forced vibration problem is solved using the Newmark-β method to obtain the time response of the undetermined coefficients and the dynamic response of the beam has been computed from the modal superposition method. The proposed coupled displacement field approach has been successfully applied for the first time to study the large amplitude vibrations of FG beams with suitable validations, and the influence of power law index, slenderness ratio, harmonic load, and concentrated mass has been investigated.

Kinematically Aligned Total Knee Arthroplasty Using Medial Pivot Knee Prosthesis Enhances Medial Pivot Motion: A Comparative Kinematic Study With Mechanically Aligned Total Knee Arthroplasty.

BackgroundClinical outcomes of kinematically aligned total knee arthroplasty (KA-TKA) have been reported as comparable or superior to those of mechanically aligned TKA (MA-TKA). However, cruciate-retaining prostheses have mostly been used for KA-TKA. This study used medial pivot knee prostheses for KA-TKA, and knee kinematics after KA-TKA were assessed and compared with those after MA-TKA.MethodsThirteen knees in 9 patients undergoing primary TKA (8 KAs, 5 MAs) were subjected to two-dimensional (2D) to three-dimensional (3D) registration analysis at 1 year postoperatively. Each patient performed weight-bearing activities, and movements were recorded as intermittent digital radiographic images. Three-dimensional implant positions during activities were analyzed for anterior-posterior translation in the sagittal plane, condylar liftoff and mediolateral translation in the coronal plane, and femoral rotation in the axial plane.ResultsPosterior translation of the lateral femoral condyle from 0° to 100° was larger in KA-TKA than in MA-TKA (P = .006). The degrees of condylar liftoff and mediolateral translation were comparable between TKAs. Total external rotation of the femoral component relative to tibial component was significantly greater for KA-TKA (7.7 ± 5.2°) than for MA-TKA (1.3 ± 3.3°; P = .03). The kinematic path of the femoral component revealed greater medial pivoting motion in KA-TKA than in MA-TKA.ConclusionsKA-TKA using a medial pivot knee prosthesis successfully reproduced the medial pivot pattern and achieved larger femoral external rotation relative to the tibia than MA-TKA. KA-TKA was able to maximize the primary concept of the medial pivot knee prosthesis.

Experimental study of the flows in a non-axisymmetric ellipsoid under precession

Precession driven flows are of great interest for both, industrial and geophysical applications. While cylindrical, spherical and spheroidal geometries have been investigated in great detail, the numerically and theoretically more challenging case of a non-axisymmetric cavity has received less attention. We report experimental results on the flows in a precessing triaxial ellipsoid, with a focus on the base flow of uniform vorticity, which we show to be in good agreement with existing theoretical models. As predicted, the uniform vorticity component exhibits two branches of solutions leading to a hysteresis cycle as a function of the Poincaré number. The first branch is observed at low forcing and characterized by large amplitude of the total fluid rotation and a moderate tilt angle of the fluid rotation axis. In contrast, the second branch displays only a moderate fluid rotation and a large tilt angle of the fluid rotation axis, which tends to align with the precession axis. In addition, we observe the occurrence of parametric instabilities early in the first branch, which saturate in the second branch, where we observe the same order of the kinetic energy in the base flow and instabilities.

Long-Term Ecosystem Nutrient Pool Status for Aspen Forest Harvest Simulations on Glacial Till and Sandy Outwash Soils

Sandy outwash and glacial till soils compose large amounts of public forestland due to historically poor agricultural yields. The outwash soils have low fertility, poor nutrient retention and are restricted from whole-tree harvesting (WTH) in some states, whereas the glacial till has medium nutrient retention and fertility, and is unrestricted from WTH. To assess the long-term sustainability of harvesting, a nutrient budget was constructed from field measurements, the National Cooperative Soil Survey (NCSS) database, and literature values for stem-only harvesting (SOH) and WTH at a 45-year rotation length and 11 rotations were simulated. The budgets showed that SOH and WTH recovery years, or the time necessary for the inputs to match outputs through leaching and one harvest, exceeded common rotation lengths for both soil types under all weathering scenarios, and the average WTH reduced the total available rotations by one harvest. The large variation in soil nutrient pools and harvest removals complicated the ability to identify the difference between SOH and WTH early in the model, but differences became apparent with sequential harvests. The recovery years were 2–20 times the 45-year rotation length under all weathering rates. Taken together, models in this study bridge the gap between short- and long-term studies and bring into question the sustainability of WTH and SOH practices on nutrient-poor soils.

Comparing Effects of Six-week Active and Passive Static Stretching on Lumbar-Pelvic Rhythm In Males With Hamstring Shortness

Background and Aims: Forward bending is a coupled movement combining lumbar flexion and pelvic rotation, the so-called lumbar–pelvic rhythm. Clinical observations have suggested that hamstring tightness influences the lumbar pelvic rhythm and may be associated with modifications in the sagittal spine curvatures during trunk flexion. Moreover, there is still no agreement on the best stretching techniques. Therefore, the aim of the present study was to compare the effect of six weeks of active and inactive static training on lumbar-pelvic rhythm in forward flexion in men with hamstring shortness. Methods: This study was a quasi-experimental study with pretest/posttest with two groups. In this study, 26 men with hamstring shortness, with a Mean±SD age of 25.76±1.71 years were selected (via purposeful sampling). Hamstring muscle shortness was measured utilizing the SLR and 90-90SLR tests. Measurements of the lumbar pelvic rhythm were recorded in the three-phase forward bending by a spinal mouse. Variables included pelvic rotation and lumbar flexion. Active and passive static stretching were respectively jack-knife and kneeling hamstring stretching techniques. To compare pretest and posttest values of active and passive static stretching groups, the paired t-test and Wilcoxon test were utilized. Furthermore, to assess the difference between active and passive static stretching groups, the ANCOVA and Mann-Whitney U test were utilized. Results: After six weeks of active and passive static stretching, the total pelvic rotation significantly increased in contrast to total lumbar flexion (P&lt;0/05). A comparison of pelvic and lumbar ROM output did not reveal a significant difference between active and passive static groups (P&gt;0/05). Conclusion: Compliant with the findings, active and passive static stretching could change the lumbopelvic rhythm to a pelvic-dominant motion, indicating that a flexible hamstring is important for preventing low back pain and other problems associated with the disturbance of the lumbo-lumbar rhythm.

Laminectomy and fusion in multilevel degenerative cervical myelopathy – Correlation between objective and subjective postoperative restriction of cervical spine mobility

For patients with multilevel degenerative cervical myelopathy (DCM), laminectomy and fusion is an established technique. A concomitant effect of multilevel fusion is a restriction of cervical spine mobility. This retrospective study on DCM-patients with at least 4 laminectomy and fusion levels, compares data between objective and subjective restriction of the postoperative cervical spine mobility. The patient-reported restriction of cervical spine mobility was acquired by a five-step score. Measurements of cervical range of motion were performed using the CROM device and were correlated with the subjective scores. Fusion was performed over 6 levels in most of the 36 patients. For the subjective cervical spine mobility, 52.8% reported none to medium, 38.9% severe and 8.3% complete restriction. Mean objective cervical range of motion was 45.0° for flexion-extension, 26.3° for total lateral flexion and 51.4° for total rotation and therefore evidently reduced compared to non-operated patient cohorts in literature. There was a significant medium, negative correlation between the objective measurements and the patient-reported general restriction of cervical spine mobility, and with the physical component summary of SF-8. The significant objective reduction of cervical range of motion after laminectomy and multilevel fusion correlates with the patient-reported assessment for general restriction.

Biomechanical Comparison of Capsular Repair, Capsular Shift, and Capsular Plication for Hip Capsular Closure: Is a Single Repair Technique Best for All?

Background:In hip arthroscopy, the best capsular closure technique to prevent microinstability in some patients while preventing overconstraints in other patients has yet to be determined.Purpose:To evaluate the biomechanical effects of capsular repair, capsular shift, and combination capsular shift and capsular plication for closure of the hip capsule.Study Design:Controlled laboratory study.Methods:Eight cadaveric hips (4 male and 4 female hips; mean age, 55.7 years) were evaluated in 7 conditions: intact, vented, capsulotomy, side-to-side repair, side-to-side repair with capsular plication (interval closure between iliofemoral and ischiofemoral ligaments), capsular shift repair, and capsular shift repair with plication. Measurements, via a 360° goniometer, included internal and external rotation with 1.5 N·m of torque at 5° of extension and 0°, 30°, 60°, and 90° of flexion. In addition, the degree of maximum extension with 5 N·m of torque and the amount of femoral distraction with 40 N and 80 N of force were obtained. Repeated-measures analysis of variance and Tukey post hoc analyses were used to analyze differences between capsular conditions.Results:At lower hip positions (5° of extension, 0° and 30° of flexion), there was a significant increase in external rotation and total rotation after capsulotomy versus the intact state (P < .05). At all hip flexion angles, there was a significant increase in external rotation, internal rotation, and total rotation as well as a significant increase in maximum extension after capsulotomy versus capsular shift with plication (P < .05 for all). At all flexion angles, both capsular closure with side-to-side repair (with or without plication) and capsular shift without capsular plication were able to restore rotation, with no significant differences compared with the intact capsule (P > .05). Among repair constructs, there were significant differences in range of motion between side-to-side repair and combined capsular shift with plication (P < .05).Conclusion:At all positions, significantly increased rotational motion was seen after capsulotomy. Capsular closure was able to restore rotation similar to an intact capsule. Combined capsular shift and plication may provide more restrained rotation for conditions of hip microinstability but may overconstrain hips without laxity.Clinical Relevance:More advanced closure techniques or a combination of techniques may be needed for patients with hip laxity and microinstability. At the same time, simple repair may suffice for patients without these conditions.