Unloaded Condition Research Articles

Mechanical behavior of additively and conventionally manufactured 316L stainless steel plates joined by gas metal arc welding

Combining several additive manufactured (AM) parts to larger parts by welding may be required due the limited building volume of powder bed AM methods. Laser powder bed fusion (LPBF) has a great potential because it enables the production of nearly full-density components through AM processes; however, additional residual stresses and production defects are induced by LPBF. These residual stresses affect the residual stress state of welded AM parts. In combination with the production related defects, both alter the mechanical and—in particular—the fatigue behavior of these welded joints. In this study, various tests are performed to characterize the butt joints of 316L AM steel plates made by gas metal arc welding. To this goal, joints are produced with weld seams parallel and vertical to the layer orientation of AM plates. The results are compared to joints of conventionally rolled steel plates produced with the same welding parameter. The residual stress states in initial (unloaded) condition and after cyclic loading were determined by X-ray diffraction techniques for AM and rolled plates. Complex residual stress states were determined at the welds made of AM steel plates compared to the welds made of rolled steel plates; however, the residual stress level in the heat affected zone of the butt-welded AM steel plates was similar to the welds made of hot-rolled steel plates. After cyclic loading with a high load level, high residual stress relaxations were observed in the parent materials. The fatigue design curve for butt joints from international standards is exceeded by all three test series, but the fatigue strength of the butt joints made by LBPF and hot rolling vary significantly. This is thought to be related to differences between the AM and conventional joints in microstructure, static strength, residual stress level, and small crack-like defects that partially interact with stress concentrations at the weld transition.

Lower-limb wearable resistance overloads joint angular velocity during early acceleration sprint running

ABSTRACT Lower-limb wearable resistance (WR) facilitates targeted resistance-based training during sports-specific movement tasks. The purpose of this study was to determine the effect of two different WR placements (thigh and shank) on joint kinematics during the acceleration phase of sprint running. Eighteen participants completed maximal effort sprints while unloaded and with 2% body mass thigh- or shank-placed WR. The main findings were as follows: 1) the increase to 10 m sprint time was small with thigh WR (effect size [ES] = 0.24), and with shank WR, the increase was also small but significant (ES = 0.33); 2) significant differences in peak joint angles between the unloaded and WR conditions were small (ES = 0.23–0.38), limited to the hip and knee joints, and <2° on average; 3) aside from peak hip flexion angles, no clear trends were observed in individual difference scores; and, 4) thigh and shank WR produced similar reductions in average hip flexion and extension angular velocities. The significant overload to hip flexion and extension velocity with both thigh- and shank-placed WR may be beneficial to target the flexion and extension actions associated with fast sprint running.

Loaded and unloaded timed stair tests as tools for assessing advanced functional mobility in people with stroke.

The Timed Stair Test (TST) was originally designed to measure advanced functional mobility in patients who have undergone a total hip replacement. Its psychometric properties have not been examined systematically in people with stroke. The aims of this study were to: 1) determine the intra-rater reliability of TST under loaded and unloaded condition; 2) identify the minimal detectable changes (MDCs) in TST completion times; 3) investigate the concurrent validity between TST completion times and stroke-specific outcome measures; and 4) determine the cut-off TST completion time to differentiate the performance between people with stroke and healthy older adults. Cross-sectional study. A university-based rehabilitation center. Ninety-four people with stroke and 34 healthy older adults. TSTs were conducted under loaded and unloaded conditions. Two trials of the TST for each of the two conditions were performed on the same day. The Fugl-Meyer Assessment of Lower Extremity (FMA-LE), lower-limb muscle strength test assessed by a hand held dynamometer, Berg Balance Scale (BBS), Limit of Stability (LOS) Test, Timed Up and Go (TUG) Test, and the Cantonese version of the Community Integration Measure (CIM) were also used to assess the subjects. Excellent intra-rater reliability was demonstrated for TST completion times under loaded (intraclass correlation coefficient [ICC<inf>2,1</inf>]=0.991) and unloaded (ICC<inf>2,1</inf>=0.985) conditions. The MDCs in TST completion times were 6.55 seconds and 7.25 seconds under loaded and unloaded conditions, respectively. FMA-LE scores, mean strength of the affected-side dorsiflexors and plantar flexors, BBS scores, and LOS movement velocity and maximum excursion scores demonstrated fair to excellent negative correlations with TST completion times under both loaded (r=-0.314 to -0.786) and unloaded (r=-0.296 to -0.794) conditions. TUG results demonstrated good to excellent positive correlations with TST completion times under both loaded (r=0.875, P<0.001) and unloaded (r=0.872, P<0.001) conditions. The TST completion times of 26.3 seconds and 23.4 seconds under loaded and unloaded conditions, respectively, differentiated between people with stroke and healthy older adults. The TST is a reliable clinical tool for evaluating advanced functional mobility in people with stroke. TST is a fast and simple test that does not require sophisticated equipment, making it suitable for busy hospital and rehabilitation settings.

Kinetic and Kinematic Assessment of the Band-Assisted Countermovement Jump.

Fernandes, JFT, Arede, J, Clarke, H, Garcia-Ramos, A, Perez-Castilla, A, Norris, JP, Wilkins, CA, and Dingley, AF. Kinetic and kinematic assessment of the band-assisted countermovement jump. J Strength Cond Res 37(8): 1588-1593, 2023-This study sought to elucidate kinetic and kinematic differences between unloaded and band-assisted countermovement jumps (CMJs). In a randomized order, 20 healthy subjects (mass 84.5 ± 18.6 kg) completed 3 repetitions of CMJs across 3 conditions: unloaded (at body mass), low, and moderate band (8.4 ± 1.9 and 13.3 ± 3.3 kg body mass reduction, respectively). For all repetitions, a force platform and linear position transducer were used to record and calculate kinetic and kinematic data. Body mass was significantly different between the unloaded, low, and moderate band conditions ( p < 0.05). Peak velocity, absolute peak, and mean force and movement duration displayed a trend that was mostly related to the condition (i.e., unloaded > low > moderate) ( p < 0.05). The opposing trend (i.e., moderate > low > unloaded) was generally observed for relative peak and mean force, reactive strength index modified, and flight time ( p < 0.05). No differences were observed for mean velocity, movement duration, and absolute and relative landing forces ( p > 0.05). The use of band assistance during CMJs can alter force, time, and velocity variables. Practitioners should be aware of the potential positive and negative effects of band assistance during CMJs.

Do Patients With Functional Hallux Limitus Have a Low-Lying or Bulky FHL Muscle Belly?

Functional hallux limitus (FHLim) refers to a limitation of hallux dorsiflexion when the first metatarsal head is under load, whereas physiologic dorsiflexion is measured in the unloaded condition. Limited excursion of the flexor hallucis longus (FHL) in the retrotalar pulley has been identified as a possible cause of FHLim. A low-lying or bulky FHL muscle belly could be the cause of this limitation. However, to date, there are no published data regarding the association between clinical and anatomical findings. The purpose of this anatomical study is to correlate the presence of FHLim and objective morphologic findings through magnetic resonance imaging (MRI). Twenty-six patients (27 feet) were included in this observational study. They were divided into 2 groups, based on positive and negative Stretch Tests. In both groups, we measured on MRI the distance from the most inferior part of the FHL muscle belly and the retrotalar pulley as well as the cross-sectional area of the muscle belly 20, 30, and 40 mm proximal to the retrotalar pulley. Eighteen patients had a positive Stretch Test and 9 patients had a negative Stretch Test. The mean distance between the most inferior part of the FHL muscle belly and the retrotalar pulley was 6.0 ± 6.4 mm for the positive group and 11.8 ± 9.4 mm for the negative group (P = .039). The mean cross section of the muscle measured at 20, 30, and 40 mm from the pulley were 190 ± 90, 300 ± 112, and 395 ± 123 mm2 for the positive group and 98 ± 44, 206 ± 72, and 294 ± 61mm2 for the negative group (P values .005, .019, and .017). Based on these findings, we can conclude that patients with FHLim do have a low-lying FHL muscle belly causing limited excursion in the retrotalar pulley. However, the mean volume of the muscle belly was comparable in both groups, and therefore bulkiness was not found to be a contributing factor. Level III, observational study.

Development of a video camera-type kayak motion capture system to measure water kayaking.

In kayaking, trunk motion is one of the important factors that prevent injury and improve performance. Kinematic studies in kayaking have been reported in laboratory settings using paddling simulators and ergometers. However, such studies do not reflect kayaking on water, the actual competitive environment. Therefore, we developed a video camera-type kayak motion capture system (KMCS) wherein action cameras were fixed to a kayak to capture images of markers attached to an athlete's body. This study aimed to compare the kinematic data between KMCS and an optical motion capture system (OMCS) in kayaking and to determine the accuracy of the KMCS analysis. In a competition, five elite junior female kayak athletes performed kayak paddling under the unloaded condition using a kayak. The kayak was secured using a tri-folding bench and a towel, and twenty strokes were recorded during maximal paddling. One stroke was defined as the period from right catch to left catch, and the first six strokes were used to evaluate the accuracy. Trunk angles (tilting, turning, and rotation) were examined with the simultaneous use of KMCS and OMCS, and the differences between these systems were evaluated. To ensure reliability, intraclass correlation coefficient (ICC; a two-way mixed model for absolute agreement) was calculated for each angle. Furthermore, Bland-Altman analysis was performed to understand the agreement between the two systems. Root mean square errors (RMSEs) were 1.42° and 3.94° for turning and rotation, respectively, and mean absolute errors (MAEs) were 1.08° and 3.00° for turning and rotation, respectively. The RMSE and MAE for tilting were 2.43° and 1.76°, respectively, which indicated that the validity was comparable to that of other angles. However, the range of motion in tilting was lower than that in turning and rotation. Bland-Altman analysis showed good agreement in the total range of motion, with mean bias values of -0.84°, -0.07°, and -0.41° for tilting, turning, and rotation, respectively. The ICCs for tilting, turning, and rotation were 0.966, 0.985, and 0.973, respectively, and showed excellent reliability. The newly developed KMCS effectively measured the trunk motion with good accuracy in kayaking. In future studies, we intend to use KMCS to measure kayaking on water and collect data for performance improvement and injury prevention.

Effect of backpack load on nerve conduction velocity and risk of peripheral neuropathy in upper extremities of undergraduate medical students carrying backpack

Background: Prolonged load carriage can potentially affect hand and upper limb use through compression of the nerves, reduction in blood flow, and muscle fatigue. Backpacks of undergraduate medical student are not much different from their syllabus. They carry heavy backpacks on regular basis and many times they wear it incorrectly. Aims and Objectives: We aimed to see the effect of backpack load on motor nerve conduction velocity and hand grip strength in the upper extremities. Materials and Methods: The present study included 31 undergraduate medical students between the age of 18 and 25 years. The procedure is conducted in three phases on different days. In each phase, participants were asked to walk for 5 min with load. In Phase 1, nerve conduction velocity and grip strength weere measured in unloaded condition and after carrying load &lt;10% of body weight. To limit the effect of fatigue, participants are instructed to return to laboratory in next consecutive weeks to repeat the procedure for Phase 2 and 3 as in Phase 1 by increasing load to 10–20% and 20–30% of their body weight respectively. Results: Values of median and ulnar motor nerve conduction velocity obtained without and with increasing % of backpack load after 5 min walk were decreased non-significantly as load increased. There was significant (P&gt;0.001) difference in grip strength of medical students carrying backpack with increasing load after 5 min walk. Conclusion: In this study, we aimed at quantifying the effects of load carriage on overall upper limb performance, with a focus on conduction velocity of motor nerves. This has implications for occupations such as soldiers, firefighters, paramedics, and others who may be required to operate machinery, equipment, tools, or systems that require precise motor control.

Optimasi Konsumsi Fuel Dump Truck Terhadap Pengaruh Grade Jalan Pada Aktivitas Penambangan Pada PT. Pamapersada Nusantara Kecamatan Sangatta Utara Kabupaten Kutai Timur

The grade or slope of the road in a mining activity is certainly unavoidable. In addition to naturally following topographical contours, the shape of the mining pit is carried out from a high elevation leading to the lowest elevation following the slope level and the continuity of the excavation material makes the road should be made sloping. The high or low value of the road grade in addition to affecting the speed and travel time required by the unit, of course, also affects the level of fuel consumption. PT. Pamapersada Nusantara uses a conveyance unit with the HD Komatsu 785-7 type to move overburden material. Based on the results of the analysis, in the loaded condition, grade 2% uses 0.45 liters of fuel, 5% grades 0.77 liters, 6% grades 0.89 liters, 8% grades 1.09 liters and grades . While in the unloaded condition, grade 2% uses 0.19 liters of fuel, 5% grades 0.35 liters, 6% grades 0.4 liters, 8% grades 0.47 liters and 9% grades 0. 52 liters.

Quantification of the in vivo stiffness and natural length of the human plantar aponeurosis during quiet standing using ultrasound elastography

This study aimed to identify the stiffness and natural length of the human plantar aponeurosis (PA) during quiet standing using ultrasound shear wave elastography. The shear wave velocity (SWV) of the PA in young healthy males and females (10 participants each) was measured by placing a probe in a hole in the floor plate. The change in the SWV with the passive dorsiflexion of the metatarsophalangeal (MP) joint was measured. The Young’s modulus of the PA was estimated to be 64.7 ± 9.4 kPa, which exponentially increased with MP joint dorsiflexion. The PA was estimated to have the natural length when the MP joint was plantarflexed by 13.8°, indicating that the PA is stretched by arch compression during standing. However, the present study demonstrated that the estimated stiffness for the natural length in quiet standing was significantly larger than that in the unloaded condition, revealing that the PA during standing is stiffened by elongation and through the possible activation of intrinsic muscles. Such quantitative information possibly contributes to the detailed biomechanical modeling of the human foot, facilitating an improved understanding of the mechanical functions and pathogenetic mechanisms of the PA during movements.

Arthroscopic centralization reduces extrusion of the medial meniscus with posterior root defect in the ACL reconstructed knee.

The purpose of this study was to evaluate the effects of arthroscopic meniscal centralization reinforcement for a medial meniscus (MM) posterior root defect on knee kinematics and meniscal extrusion in the anterior cruciate ligament reconstructed (ACLR) knee. The hypothesis was that the medial meniscus centralization would reduce extrusion and anterior laxity in ACLR knee with a medical meniscal defect. Fourteen fresh-frozen human cadaveric knees were tested using a six-degrees-of-freedom robotic system under the following loading conditions: (a) an 89.0N anterior tibial load, (b) 5.0 Nm internal and external rotational torques, (c) a 10.0Nm valgus and varus loadings, and (d) a combined 7.0Nm valgus moment and then a 5.0Nm internal rotation torque as a static simulated pivot shift. The tested knee states included: (1) anatomic single-bundle cruciate ligament reconstruction with intact medial meniscus (MM Intact), (2) anatomic single-bundle cruciate ligament reconstruction with medial meniscus posterior root defect (MM Defect), (3) Anatomic single-bundle cruciate ligament reconstruction with medial meniscus arthroscopic centralization (MM Centralization). Medial meniscus arthroscopic centralization was performed using 1.4mm anchors with #2 suture. The MM extrusion (MME) was measured using ultrasound under unloaded and varus loading conditions at 0° and 30° of flexion. Anterior tibial translation (ATT) increased significantly with MM posterior root defect compared to MM intact at all flexion angles. With MM centralization, ATT was not significantly different from the intact meniscus at 15° and 30° of flexion. Meniscus extrusion increased significantly with the root defect compared to intact meniscus and decreased significantly with meniscal centralization compared to the root defect at both flexion angles. In ACL reconstruction, cases involving irreparable medial meniscal posterior root tears, applying arthroscopic centralization for avoiding the meniscal extrusion should be considered. Clinically, in ACL reconstruction cases with irreparable medial meniscal posterior root tears, applying arthroscopic meniscal centralization for avoiding the meniscal extrusion should be considered. Meniscal centralization decreases the extrusion of the MM and offers improvements in knee laxity.

Effect of using hybrid nanofluids as a coolant on the thermal performance of portable thermoelectric refrigerators

This study investigated the effect of using hybrid nanofluids as a refrigerant in portable thermoelectric refrigerator applications on thermal performance. For this purpose, a cooling cabinet with an internal volume of 36 L was designed and produced. Then, the Peltier assembly, with a water-cooled block attached to its hot surface, was placed in this cooling cabinet from the middle of its front cover. With the help of a refrigerant, the heat was removed from the Peltier’s hot surface and transferred to the atmosphere via a water-to-air heat exchanger. Hybrid nanofluids prepared with Al2O3-TiO2-SiO2 and nanoparticles and water were used as the refrigerant in the system. To evaluate the thermal performances of these hybrid nanofluids, the tests were repeated using water without added nanoparticles as the reference case. According to the results obtained from the experimental study, it was observed that in all cases, tests using nanofluids gave better results than the reference cases. In addition, it was determined that the efficiency obtained from the system increased as the nanoparticle ratio in the mixture increased in all cases. Despite significant improvements in cooling cabinet and cooled product temperatures in hybrid nanofluids, the COP values ​​of the systems are slightly lower than in the reference case due to the Peltier effect. Considering the difference between the first and last temperatures of the cooled cabinet, the greatest improvement compared to the reference situation was determined as 30.3 % in the case of loaded state conditions and in the case of using 2 % Al2O3-TiO2-SiO2-Water nanofluid. For the unloaded conditions, this value was obtained as 25.1 % in the case of using 2 % Al2O3-TiO2-SiO2-Water nanofluid. On the other hand, for the unloaded condition, the lowest COP value was calculated as 0.47 and 0.45 when Al2O3-TiO2-SiO2-Water nanofluid was used in 1 % and 2 % mass fraction, respectively. For the loaded condition, this value was found as 0.48 in the case where 1 % Al2O3-TiO2-SiO2-Water and 0.47 in the case where 2 % Al2O3-TiO2-SiO2-Water nanofluid was used.

Techno-environmental assessment of a hydrogen-fuelled combined-cycle gas turbine for a liquid hydrogen tanker

The purpose of this study was a techno-environmental assessment analysis for a 280,000 m3 liquid hydrogen (LH2) tanker powered by a hydrogen-fuelled combined-cycle gas turbine (COGAS) as the prime mover. This study utilised established and reliable methods to simulate the LH2 tanker in different journeys and conditions for analysing the advantages of the hydrogen-fuelled COGAS in terms of performance and emission reduction. The assessment was based on engine behaviour on different journeys under cargo loaded and unloaded conditions, with a normal and a 6% degraded engine, and under various ambient conditions. According to the results, the single-pressure hydrogen-fuelled COGAS reached a maximum overall thermal efficiency of 55.5% in winter under unloaded and normal engine conditions at a ship speed of 18 knots during the journey from Marseille to Algeria. From an environmental perspective, the maximum NOx emission of the COGAS was 3.5 kg/h during the journey from Tangier to Southampton in summer with a 6% degraded engine under the loaded condition at a ship speed of 18 knots. The results of the techno-environmental assessment indicated that the LH2 tanker powered by the hydrogen-fuelled COGAS could successfully achieve high efficiency and low emission targets in off-design conditions. The outcome of this study will lead to a future investigation of the LH2 tankers operation economic aspects.

Locomotion of an untethered, worm-inspired soft robot driven by a shape-memory alloy skeleton

Soft, worm-like robots show promise in complex and constrained environments due to their robust, yet simple movement patterns. Although many such robots have been developed, they either rely on tethered power supplies and complex designs or cannot move external loads. To address these issues, we here introduce a novel, maggot-inspired, magnetically driven “mag-bot” that utilizes shape memory alloy-induced, thermoresponsive actuation and surface pattern-induced anisotropic friction to achieve locomotion inspired by fly larvae. This simple, untethered design can carry cargo that weighs up to three times its own weight with only a 17% reduction in speed over unloaded conditions thereby demonstrating, for the first time, how soft, untethered robots may be used to carry loads in controlled environments. Given their small scale and low cost, we expect that these mag-bots may be used in remote, confined spaces for small objects handling or as components in more complex designs.

Poster 185: Flexor Pronator Mass Contribution to Elbow Valgus Stability: A Biomechanical Project

Objectives:Identify the main muscle in the flexor pronator mass (the pronator teres (PT), flexor carpi radialis (FCR), flexor digitorum superficialis (FDS), and flexor carpi ulnaris (FCU)) that contributes most to valgus stability at a greater range of elbow motion (60-150 degrees) than in previous studies.Methods:8 cadaveric elbows in an in vitro biomechanical study were investigated. The specimens were mounted on a custom apparatus from the distal humerus to the fingers. Each muscle group of the flexor pronator mass was relatively loaded based on physiologic cross-sectional area. There were 6 loaded conditions: all loaded, unloaded PT, unloaded FCR, unloaded FDS, unloaded FCU, and all unloaded. A 2 N-m valgus torque was applied at a rate of 1 mm/sec. Valgus angle was measured for each loaded condition, especially between all loaded and one unloaded muscle. This allowed an increase in valgus angle for one unloaded muscle. The higher increase in valgus angle indicated the higher the contribution of that released muscle to valgus stability. This was performed at 60, 90, 120, and 150 degrees of elbow flexion to cover the range at which the UCL tears during the late cocking and early acceleration phases of throwing. The measurements were made in two conditions: first with the UCL intact and second with the UCL resected at the anterior bundle.Results: There was a statistical significance in the mean change in valgus angle at all flexion angles and load conditions when the UCL was intact vs when it was resected (3.76 ± 2.78 SD vs 4.82 ± 2.99 SD degrees).The valgus angle was statistically mostly increased in the “all unloaded” condition when compared to all the other loaded conditions at all flexion angles involving both when the UCL was intact and resected.Unloading one individual flexor pronator muscle did not significantly affect the valgus stability of the elbow.There was a trend towards FDS as being the primary flexor pronator stabilizer when the elbow was taken from an all-loaded condition to one muscle that was unloaded (P value = 0.169).At 150 degrees, the elbow was statistically significantly most stable compared to all the other flexion angles.At 90 degrees, the elbow was most unstable with an increase in valgus angle of 1.2 degrees between intact and resected UCL conditions.At 60 degrees with the UCL resected, there was not a statistical significant difference in valgus angle between all unloaded and unloaded FDS conditions signifying that the FDS contributed most to valgus stability. Conclusions: Physical examination of the UCL is best performed with the elbow at 90 degrees with the forearm in neutral (most unstable out of the flexion angles we tested).At 150 degrees, the elbow is most stable to valgus stress.When the UCL is injured, the FDS appeared to contribute most to valgus stability at 60 degrees out of the four flexor pronator muscles.There was a trend towards FDS as being the primary flexor pronator stabilizer.Rehabilitation of the flexor-pronator mass should focus on the FDS. Figure 1.Figure 2.Table 1.Two-group comparisons of mean valgu angle under different loading conditionsTable 2.Two-group comparisons between all unloaded condition and other loaded conditions at 60˚ elbow flexion with resected UCL.

Investigation of deep learning models on identification of minimum signal length for precise classification of conveyor rubber belt loads

In this paper, long short-term memory (LSTM) and Transformer neural network models were developed for classification of different conveyor belt conditions (loaded and unloaded). Comparative shallow models such as logistic regression, support vector machine and random forest were also developed and summarized. Six different-length belt pressure signals were analyzed: 0.2, 0.4, 0.8, 1.6, 3.2, and 5.0 s. Both LSTM and Transformer models achieved 100% accuracy using pressure raw signal. Furthermore, LSTM model reached the highest classification level with the shortest signals. Accuracy and F1-score of 98% and 100% were reached using only 0.8 and 1.6 s-length signals, respectively. Also, LSTM model performed training and testing procedures faster than Transformer. Random forest model demonstrated the best classification level using aggregated signal data with accuracy of 85% and F1-score for loaded and unloaded conditions of 85% and 69%, respectively. Loaded conveyor belt condition was significantly easier to classify than the unloaded one in all models. Only LSTM showed better classification recall for unloaded conveyor belt condition using short signal. Experimental research dataset CORBEL (Conveyor belt pressure signal dataset) and models are open-sourced and accessible on GitHub https://github.com/TadasZvirblis/CORBEL .

Utility of Diagnostic Ultrasound in the Assessment of Patellar Instability.

Background:The use of imaging to diagnose patellofemoral instability is often limited by the inability to dynamically load the joint during assessment. Therefore, the diagnosis is typically based on physical examination using the glide test to assess and quantify lateral patellar translation. However, precise quantification with this technique remains difficult.Purpose:To quantify patellar position using ultrasound imaging under dynamic loading conditions to distinguish between knees with and without medial patellofemoral complex (MPFC) injury.Study Design:Controlled laboratory study.Methods:In 10 cadaveric knees, the medial patellofemoral distance was measured to quantify patellar position from 0° to 40° of knee flexion at 10° increments. Knees were evaluated at each flexion angle under unloaded conditions and with 20 N of laterally directed force on the patella to mimic the glide test. Patellar position measurements were made on ultrasound images obtained before and after MPFC transection and compared for significant differences. To determine the ability of medial patellofemoral measurements to differentiate between MPFC-intact and MPFC-deficient states, area under the receiver operating characteristic (ROC) curve analysis and the Delong test were used. The optimal cutoff value to distinguish between the deficient and intact states was determined using the Youden J statistic.Results:A significant increase in medial patellofemoral distance was observed in the MPFC-deficient state as compared with the intact state at all flexion angles (P = .005 to P < .001). When compared with the intact state, MPFC deficiency increased medial patellofemoral distance by 32.8% (6 mm) at 20° of knee flexion under 20-N load. Based on ROC analysis and the J statistic, the optimal threshold for identifying MPFC injury was 19.2 mm of medial patellofemoral distance at 20° of flexion under dynamic loading conditions (area under the ROC curve = 0.93, sensitivity = 77.8%, specificity = 100%, accuracy = 88.9%).Conclusion:Using dynamic ultrasound assessment, we found that medial patellofemoral distance significantly increases with disruption of the MPFC.Clinical Relevance:Dynamic ultrasound measurements can be used to accurately detect the presence of complete MPFC injury.

Osteocytes: Their Lacunocanalicular Structure and Mechanoresponses.

Osteocytes connect with neighboring osteocytes and osteoblasts through their processes and form an osteocyte network. Shear stress on osteocytes, which is induced by fluid flow in the lacunae and canaliculi, has been proposed as an important mechanism for mechanoresponses. The lacunocanalicular structure is differentially developed in the compression and tension sides of femoral cortical bone and the compression side is more organized and has denser and thinner canaliculi. Mice with an impaired lacunocanalicular structure may be useful for evaluation of the relationship between lacunocanalicular structure and mechanoresponses, although their bone component cells are not normal. We show three examples of mice with an impaired lacunocanalicular structure. Ablation of osteocytes by diphtheria toxin caused massive osteocyte apoptosis, necrosis or secondary necrosis that occurred after apoptosis. Osteoblast-specific Bcl2 transgenic mice were found to have a reduced number of osteocyte processes and canaliculi, which caused massive osteocyte apoptosis and a completely interrupted lacunocanalicular network. Osteoblast-specific Sp7 transgenic mice were also revealed to have a reduced number of osteocyte processes and canaliculi, as well as an impaired, but functionally connected, lacunocanalicular network. Here, we show the phenotypes of these mice in physiological and unloaded conditions and deduce the relationship between lacunocanalicular structure and mechanoresponses.

Torque Pulsation Reduction During Magnetization in Variable Flux Machines

This paper proposes two methods to minimize the pulsating torque during magnetization in a variable flux - permanent magnet synchronous machine (VF-PMSM). The VF-PMSM is demagnetized and remagnetized by injecting a current pulse to achieve the high speed and high torque requirements. During demagnetization and remagnetization, a d – axis current pulse is injected to change the magnetization state (MS). These MS changing current pulses will change the magnet flux linkage based on the amplitude of the pulse. However, the injected d – axis current abruptly changes the magnet torque as well as reluctance torque and results in a pulsating torque. Since the remagnetization current is much higher than the machine rated current, the pulsating torque is more severe during the remagnetization process. Thus, it is preferred to magnetize the magnet at zero speed and unloaded conditions. To solve this problem, a q – axis current reference during the remagnetization is determined by two different methods: voltage limit method and load torque method. The derived q – axis current reduces the torque pulsation during the remagnetization. The effectiveness of the proposed scheme is experimentally verified on a manufactured VF-PMSM prototype.

A resonant cavity system for exposing cell cultures to intense pulsed RF fields

The IEEE and ICNIRP had specified a maximum permissible exposure for instantaneous peak electric field of 100 kV/m. However, no rationale was given for this limit. A novel exposure system was designed through a detailed process of analytical analysis, numerical modelling and prototype testing. The system consists of a cylindrical re-entrant resonant cavity that can achieve an electric field strength of more than 100 kV/m with an input power of 200 W. The working of the system was evaluated in simulation and experiment in terms of scattering parameters, electric field distributions and specific absorption rate. The system was then used to carry out in-vitro exposures of a human lymphoid cell line (GG0257) to a 1195 MHz signal at 53 dBm peak power and a pulse width of 550 ns at a range of interpulse intervals to identify heating-induced changes in cell viability. The proposed system offers high Q value of 5920 in unloaded condition which was reduced to 57 when loaded with 12 ml of cell culture but still offering 67 kV/m of the field intensity. Using the system for the exposure of GG0257 cells lasting 18 min, interpulse intervals of 11 μs or less caused a reduction in the number of viable cells and a corresponding increase in necrotic cells. For a shorter exposure duration of 6 min, the reduction in cell viability was seen at interpulse intervals of 5.5 μs or less. The designed exposure system is well capable of handling high intensity electric fields. Temperature measurements with a fibre optic probe and temperature sensitive labels showed that changes in viability were associated with temperature increases above 46 °C. This novel exposure system is an efficient means to investigate the possible relationship between peak field intensity and biological effects to provide a rationale behind the maximum exposure limit of 100 kV/m.

An Ultra-Thin Multiband Refractive Index-Based Carcinoma Sensor Using THz Radiation

A novel multiband terahertz (THz) refractive index-based carcinoma sensor is designed and investigated in this paper. The proposed THz sensor is constructed using meandered sectoral stubs enclosed in a square loop. The proposed sensor has a footprint of <inline-formula> <tex-math notation="LaTeX">$1.019 \lambda _{eff} 1.019 \lambda _{eff}$ </tex-math></inline-formula> and operates at three distinct frequencies, viz. 1.095 THz, 2.865 THz, and 4.065 THz. The absorption characteristics of the sensor are analyzed to estimate the performance of the proposed sensor. The free space absorptivity is estimated as 99.6&#x0025;, 99.1&#x0025; and 99.2&#x0025; at the said three resonant frequencies. The peak Q factor of 22.58 is realized at 4.065 THz under free space unloaded condition. Further, a study on different design parameters on absorption peaks and polarization independency is conducted and the results are presented. Followed by these, the sensitivity performance of the proposed carcinoma THz sensor is analyzed for healthy and cancerous cells of blood, skin and breast based on their unique refractive index profile. The peak sensitivity of 514.28 GHz/RIU at 2.865 THz, 476.35 GHz/RIU at 4.065 THz, and 476.91 GHz/RIU at 4.065 THz is theoretically observed for blood, skin and breast cancer cells respectively. Similarly, the high Q factor of 21.85, 18.06, 19.21 at 4.065 THz with FoM of 2.8, 2.38 and 2.384 are also observed for blood, skin and breast cancer respectively. Furthermore, the influence of the sample thickness on the THz sensor performance is analyzed. Thus, the proposed THz sensor is a promising entity for the detection and early diagnosis of cancer cells using THz radiation.