Lateral Displacement Test Research Articles

Analysis of Specific Physical Fitness in High-Level Table Tennis Players-Sex Differences.

Table tennis performance depends on multiple factors such as technique, tactics and fitness. Several studies have focused on investigating different technical-tactical variables. However, research analysing the specific physical qualities of this sport is scarce, particularly in the female sex. The aim of the present study was to assess the physical fitness variables associated with individual performance in elite table tennis players according to sex. Forty-eight elite players divided into males (n = 24; 25.38 ± 4.01 years) and females (n = 24; 22.33 ± 3.83 years) participated in the study. To determine physical fitness, participants performed vertical jump, hand grip strength, ergospirometry and lateral displacement tests (reaction time, displacement time and lateral acceleration). Male players showed higher values in vertical jump, hand grip strength and maximum oxygen consumption (p < 0.001). Likewise, male players moved laterally faster (p < 0.001). On the other hand, female players had a better reaction time towards the dominant side (p < 0.01). Elite male table tennis players showed better physical fitness compared to female players. Due to the scarcity of data on elite table tennis players, these results can serve as reference values for different table tennis practitioners.

Cyclic testing of moment-shear force interaction in reinforced concrete shear wall substructures

Previous quasi-static cyclic tests of shear walls, which routinely used an incremental lateral displacement test protocol with a constant axial load, failed to reflect the character of moment-shear force interaction of prototype buildings. To study the effect of the moment-shear force interaction on the seismic performance of shear walls, three identical 2-story shear wall specimens with different loading patterns were constructed at 1/2 scale, to represent the lower portion of an 11-story high-rise building, and were tested under reversed cyclic loads. The axial force, shear force and bending moment were simultaneously applied to simulate the effects of gravity loads and earthquake excitations on the prototype. The axial force and bending moment delivered from the upper structure were applied to the top of the specimens by two vertical actuators, and the shear force was applied to the specimens by two horizontal actuators. A mixed force-displacement control test program was adopted to ensure that the bending moment and the lateral shear were increased proportionally. The experimental results show that the moment-shear force interaction had a significant effect on the failure pattern, hysteretic characteristics, ductility and energy dissipation of the specimens. It is recommended that moment-shear force interaction should be considered in the loading condition of RC shear wall substructures cyclic tests.

Evaluation of miniscrew stability using an automatic embedding auxiliary skeletal anchorage device.

To clarify the in vivo effect of an automatic embedding device on miniscrew stability. 42 miniscrews were implanted into rabbit femurs. The miniscrews with the novel auxiliary device formed the auxiliary group (n = 11 at 4 weeks; n = 11 at 8 weeks) and the miniscrews without the auxiliary device formed the nonauxiliary control group (n = 9 at 4 weeks; n = 11 at 8 weeks). Cortical bone thickness, distance from the cortical bone surface to the miniscrew head, and implantation depth of the spike were measured using micro-computed tomography. The mechanical retention force was evaluated by measuring the displacement of the miniscrew head after it was loaded perpendicular to its long axis. In the lateral displacement test, effects of the auxiliary (with vs without auxiliary), and time (4 vs 8 weeks) were assessed using the Brunner-Langer nonparametric analysis of longitudinal data in factorial experiments. The mean implantation depth of the spike in the auxiliary group at 4 and 8 weeks was 0.28 mm (median: 0.33; SD: 0.12) and 0.37 mm (median: 0.33; SD: 0.19), respectively. The retention force was approximately 2.0 to 2.8 and 1.6 to 1.8 times greater in the auxiliary group than in the nonauxiliary group at 4 and 8 weeks, respectively. The auxiliary device improved the mechanical retention force without the need to increase miniscrew length or diameter. This may enable the safe use of miniscrews in difficult areas.

Comparison of mechanical and biological properties of zirconia and titanium alloy orthodontic micro-implants.

ObjectiveThe aim of this study was to compare the initial stability as insertion and removal torque and the clinical applicability of novel orthodontic zirconia micro-implants made using a powder injection molding (PIM) technique with those parameters in conventional titanium micro-implants.MethodsSixty zirconia and 60 titanium micro-implants of similar design (diameter, 1.6 mm; length, 8.0 mm) were inserted perpendicularly in solid polyurethane foam with varying densities of 20 pounds per cubic foot (pcf), 30 pcf, and 40 pcf. Primary stability was measured as maximum insertion torque (MIT) and maximum removal torque (MRT). To investigate clinical applicability, compressive and tensile forces were recorded at 0.01, 0.02, and 0.03 mm displacement of the implants at angles of 0°, 10°, 20°, 30°, and 40°. The biocompatibility of zirconia micro-implants was assessed via an experimental animal study.ResultsThere were no statistically significant differences between zirconia micro-implants and titanium alloy implants with regard to MIT, MRT, or the amount of movement in the angulated lateral displacement test. As angulation increased, the mean compressive and tensile forces required to displace both types of micro-implants increased substantially at all distances. The average bone-to-implant contact ratio of prototype zirconia micro-implants was 56.88 ± 6.72%.ConclusionsZirconia micro-implants showed initial stability and clinical applicability for diverse orthodontic treatments comparable to that of titanium micro-implants under compressive and tensile forces.

Experimental evaluation of a distributed Brillouin sensing system for measuring extensional and shear deformation in rock

Distributed Brillouin sensing systems (DBSs) have growing applications in engineering and are attracting attention in the field of underground structures, including mining. The capability for continuous measurements of strain over large distances makes DBSs a promising monitoring approach for understanding deformation field evolution within a rock mass, particularly when the sensor is installed away from excavation damaged zone (EDZ). A purpose-built fiber optic sensing cable, a vital component of DBSs, was assessed in laboratory conditions.A test program was performed to observe DBSs response to various perturbations including strain and joint movements, including opening and shearing of joints. These tests included assessment of the strain-free cable response and the application of extensional and lateral displacement to various sensing cable lengths (strained lengths), from 1m down to 1cm. Furthermore, tests were done to evaluate the time-dependent behavior of the cable and to observe the effect of strain transfer using a soft host material (e.g. a soft grout) under lateral displacement.The noise level of the DBSs range was ±77με, determined through repeated measurements on an unstrained cable. Stretching test results showed a clear linear correlation between applied strain and Brillouin frequency shift change for all strained lengths above half the spatial resolution of the DBSs. However, for strained lengths shorter than half the spatial resolution, no strain response was measurable and this is due to the applied internal signal processing of the DBSs to detect peak Brillouin gain spectrum and noise level. The stability with time of the measurements was excellent for test periods up to 15h.Lateral displacement test results showed a less consistent response compared to tension tests for a given applied displacement. Although the Brillouin frequency shift change is correlated linearly with the applied displacement in tension, it shows a parabolic variation with lateral displacement. Moreover, the registered frequency response (correlated with strain) of the system decreased significantly when the sensing cable was embedded in a sand-filled tube compared with direct cable displacement.

Seismic behavior of slender reinforced concrete walls

Residential reinforced concrete buildings performed well during the 2010 Mw 8.8 Maule, Chile earthquake. However, brittle damage was observed in reinforced concrete structural walls. The most frequent observed damage in such walls was crushing of concrete due to flexural-compressive interaction, buckling and fracture of longitudinal reinforcement, and opening of the horizontal reinforcement. The main objective of this study is to understand the observed damage in slender walls after 2010 Maule earthquake and to reproduce and analyze experimentally the seismic behavior of such walls. The second objective is to provide recommendations to estimate the lateral displacement and the effective stiffness of slender walls. To achieve these objectives, six ½-scale slender reinforced concrete walls were tested using a conventional quasi-static cyclic incremental lateral displacement test protocol with a constant axial load. The test results are compared to a reference wall tested previously in the same research project. The variables analyzed in this study are: wall thickness, wall aspect ratio, use of uniformly distributed vertical reinforcement, detailing of 135-degree hooks for the horizontal reinforcement, addition of closed stirrups in the wall boundaries, and addition of transverse cross-ties. The observed damage in the tested walls was similar to that observed in walls of buildings damaged during the 2010 Maule earthquake. The behavior of the tested walls was dominated by bending due to their relatively large aspect ratio. The failure, determined by the loss of ability to carry axial load, occurred suddenly as a compression failure along the entire cross section at the base of the tested walls. Test results showed that a 25% reduction in wall thickness reduced the ultimate displacement capacity, ductility, and energy dissipation ability of the wall. Closed stirrups and cross-ties were effective in increasing displacement capacity and ductility, and closed stirrups were effective in preventing out-of-plane buckling of the wall after compression failure. The average effective stiffness ratio of the tested walls was 0.39, which is slightly larger than the ACI 318 suggestion of 0.35.

Is there a difference between the primary stability of anodized and non-anodized mini-screws subjected to repeated cycles of autoclave sterilization?

Objective: To determine if autoclave sterilization has any deleterious effects on the clinical stability of anodized versus non-anodized mini-screws. Materials and Methods: Thirty anodized and thirty non-anodized Aarhus System mini-screws (American Orthodontics, Sheboygan, WI) were utilized. Each group was divided into three test groups. In each group, mini-screws that were sterilized once using a steam autoclave (Statim 5000, SciCan USA, Canonsburg, Pa) served as the control group (n=10). The other two test groups involved mini-screws that were subjected to a repeated cycles of sterilization for five (n=10) and ten (n=10) times. All sixty mini-screws were inserted at a 90 ° angle into custom-designed synthetic blocks that simulated the average mandible of a healthy adult. The maximum insertion torque and the lateral displacement at 0.025, 0.05, 0.1, 0.25, 0.5, and 1 mm were recorded for each sample and subjected to statistical testing. A two-way ANOVA, and a three-way mixed ANOVA were used for statistical analyses. Results: Maximum insertion torque values displayed significant differences between the anodized and non-anodized groups (p<0.001) as well as the sterilization cycles (p<0.001). No significant group and cycle interaction was observed. No significant differences were found between the groups and sterilization cycles in the evaluation of the lateral displacement test. However, there was a significant group/cycle/displacement interaction (p<0.001). Conclusion: Surface treatment of mini-screws with anodization produced differences when compared to standard surface mini-screws following autoclave sterilization. The differences between the two types of mini-screws did not indicate a potential stability concern.

Dynamic KINE-MRI in patellofemoral instability in adolescents

The impact of kinematic MRI (KINE-MRI) in the patellofemoral instability and anterior knee pain of the adolescents is rarely reported. Our special interest was to evaluate the patellofemoral joint biomechanics with KINE-MRI in adolescents with affected and unaffected knees in a case-control study. KINE-MRI was performed in 29 adolescents (affected knee group, n = 29 and unaffected knee group, n = 26) aged 11-16 years with unilateral patellofemoral instability. For the control group, we enrolled ten healthy age- and sex-matched volunteers (healthy knee group, n = 19). The study parameters, bisect offset, lateral patellar displacement, patellar tilt angle, sulcus angle and Insall-Salvati ratio at 0, 10, 20 and 30° of flexion-extension, were measured for the affected knee patients (n = 29), unaffected knee patients (n = 26) and the healthy knee subjects (n = 19). The affected knee and the healthy knee subjects had a significant difference in the bisect offset ratio, lateral patellar displacement test and patellar tilt angle test. In these parameters, the difference between the affected knee patients and the healthy knee subjects progressively increased towards the full extension of the knee. In the affected knee and unaffected knee patients, bisect offset ratio at 0° ranged between 0.50 and 1.20 in both groups, whereas the bisect offset ratio in the healthy knee subjects ranged between 0.33 and 0.75 (p < 0.001). At the 0°, the lateral patellar displacement test ranged between 0 and 10 mm in the affected knee patients and between 0 and 35 mm in the unaffected knee patients, whereas the lateral displacement test ranged between 0 and 5 mm in the healthy knee subjects (p = 0.003). Patellar tilt angle test ranged between -30 and 20° in the affected knee patients and between -30 and 24° in the unaffected knee patients, and in the healthy knee subjects, the patellar tilt angle test ranged between 10 and 24° (p < 0.001). The KINE-MRI was able to detect significant differences in patellofemoral joint kinematics between the patients and the healthy subjects. A new finding with clinical relevance in our work is that the unaffected knee is very similar to the dislocated knee in adolescents and this should be taken in account in rehabilitation of patients. II.

Mechanical stability assessment of novel orthodontic mini-implant designs: Part 2

To assess the mechanical stability of a newly revised orthodontic mini-implant design (N2) compared with a design introduced in Part 1 of the study (N1) and the most widely-used commercially-available design (CA). To evaluate the mean buccal bone thickness of maxillary and mandibular posterior teeth using cone-beam computed tomography (CBCT). From the CBCT scans of 20 patients, six tomographic cross-sections were generated for each tooth. Buccal bone thickness was measured from the most convex point on the bone to the root surface. CA (1.5 mm in diameter and 6 mm in length), N1, and N2 (shorter and narrower than N1) were inserted in simulated bone with cortical and trabecular bone layers. Mechanical stability was compared in vitro through torque and lateral displacement tests. The bone thickness ranged from 2.26 to 3.88 mm. Maximum insertion torque was decreased significantly in N2 compared to N1. However, force levels for all displacement distances and torque ratio were the highest in N2, followed by N1 and CA (α = .05). Both torque and lateral displacement tests highlighted the enhanced stability of N2 compared with CA. Design revisions to N1 effectively mitigated N1's high insertion torque and thus potentially reduced microdamage to the surrounding bone. The N2 design is promising as evidenced by enhanced stability and high mechanical efficiency. Moreover, N2 is not limited to placement in interradicular spaces and has the capacity to be placed in the buccal bone superficial to the root surface with diminished risk of endangering nearby anatomic structures during placement and treatment.

Stability comparison between commercially available mini-implants and a novel design: Part 1

To compare mechanical stability among five mini-implant designs--a newly invented design and four commercially available designs that vary by shape and threading; to calculate external surface area of each design using high-resolution micro-computed tomography; and to evaluate the relationship between surface area and stability results. The four commercially available mini-implants--single-threaded and cylindrical (SC), single-threaded and tapered (ST), double-threaded and cylindrical (DC), double-threaded and tapered (DT)--and a new implant that is designed to engage mostly in cortical bone with shorter and wider dimensions (N1) were inserted in simulated bone with cortical and trabecular bone layers. The mechanical study consisted of torque measurements and lateral displacement tests. External surface area was computed using a 25-µm micro-CT. Maximum insertion torque, maximum removal torque, and force levels for displacements were the highest in N1, followed by DT, ST, DC, and SC (α = .05). The surface area was largest in DT, followed by N1, ST, DC, and SC. Surface area engaged in cortical bone, however, was the greatest in N1. The surface area of mini-implants had positive correlation with stability. Among commercial designs, both added tapering and double threading improved stability. N1 was the most stable design within this research design. The new design has the potential to be clinically superior; it has enhanced stability and there is diminished risk of endangering nearby anatomic structures during placement and orthodontic treatment, but the design requires refinements to reduce insertion torque to avoid clinical difficulty and patient discomfort.

Lateral Stiffness of Steel Bridge I-Girders Braced by Metal Deck Forms

The lateral-torsional buckling capacity of steel bridge girders is often increased by incorporating bracing along the girder length. Permanent metal deck forms (PMDF) that are used to support the wet concrete deck during bridge construction are a likely source of stability bracing; however, their bracing performance is greatly limited by flexibility in the connections currently used with the formwork. This paper outlines results from a research study that assessed and improved the bracing potential of metal deck forms used in bridge applications. The research study included shear tests of PMDF panels, and also lateral displacement and buckling tests of twin girder systems braced with PMDF. This paper will provide key results from the shear panel tests and then focus on the lateral displacement tests. Parametric investigations of PMDF bracing behavior were conducted using finite-element analyses and the results from the lateral displacement tests served a critical role in calibrating the finite element mod...

Upper cervical instability: are clinical tests reliable?

SUMMARY. The aim of this preliminary study was to investigate the reliability of a selection of manual tests used for the examination of instability of the upper cervical region.Eleven children with Down's syndrome were examined by four independent examiners with different levels of experience in manual therapy. Three tests as described by Van der El (1992) were used: the lateral displacement test, the Sharp-Purser test, and the upper cervical flexion test.Scores of tests and retests were statistically analysed by calculating the percentage of agreement, and Brennan and Prediger's modified kappa, and with the binomial test.The results showed a significant agreement between test and retest for the upper cervical flexion test in three out of four investigators. Agreement between investigators was significant in four out of six combinations between two investigators, and near to significant for this test (Pbin = .07) in the two remaining combinations.The other two investigated tests and the total score showed no tendancy towards a consistent level of significant intra- or interobserver reliability.

Two-Dimensional Stress-Strain Relationship for Canine Pericardium

Two-dimensional pseudoelastic mechanical properties of the canine pericardium were investigated in vitro. The pericardium was assumed to be orthotropic. The material symmetry axis was determined a priori and aligned with the stretching axis. Various biaxial stretching tests were then performed and a set of data covering a wide range of strains was constructed. This complete data set was fitted to a new exponential type constitutive model, and a set of true material constants was determined for each specimen. Using the constitutive model and the true material constants, the results from constant lateral force tests and constant lateral displacement tests were predicted and compared with experiment.