AMBAND Bone-Conduction Headband.

Nowadays, the large majority of the instrumentation for orthopaedic surgery consists of mechanical tools with varying degrees of complexity. To increase the accuracy and the safety of orthopaedic interventions, sensors and computers were recently introduced in the operating room. Computer Assisted Orthopaedic Surgery (CAOS) uses a navigation system that tracks the movements of surgical instruments in real-time and displays their exact location in relation to the operative area. Such technology improved the quality of orthopaedic arthroplasties, but it is still limited to the measurement of kinematic parameters such as axial alignments, position and angle measurements. In Total Knee Arthroplasty (TKA), the ligament balance, which is crucial for the stability and lifetime of implants, is currently only qualitatively assessed. The goal of this thesis was therefore to demonstrate the importance of intraoperative measurement of musculoskeletal forces through the development of a force-sensing device designed to improve the ligament balancing procedure during TKA. Three possible device designs were proposed and evaluated using finite element analysis in an iterative optimization process. The final design consists of two sensitive plates, one for each condyle, a tibial base plate and a set of spacers to adapt the device thickness to the patient-specific tibiofemoral gaps. Each sensitive plate is equipped with three deformable bridges instrumented with thick-film piezoresistive sensors, which allow accurate measurements of the amplitude and location of the tibiofemoral contact forces. The net varus-valgus moment is then computed to characterize the ligament imbalance. Laboratory experiments showed that the device has appropriate accuracy and dynamic range for the intended application. The first experimental trials on a plastic knee joint model and on a cadaver specimen demonstrated the proper in-situ functioning of the device. The performance and surgical advantages of the device were then evaluated in an in-vitro study including four different experiments: 1) Six knee joints were axially loaded. Comparing applied and measured compressive forces demonstrated the accuracy and reliability of in-situ measurements. 2) To estimate the importance of keeping the patella in its anatomical place during imbalance assessment, the effect of patellar eversion on the mediolateral distribution of tibiofemoral contact forces was measured. One fourth of the patellar load was shifted to the lateral compartment. 3) Assessment of knee stability based on condyle contact forces or varus-valgus moments were compared to the current surgical method (difference of varus-valgus loads causing condyle lift-off). The force-based assessment found to be equivalent to the surgical method while the moment-based technique, which is considered optimal, showed a tendency of lateral imbalance. 4) Finally the effect of minor and major medial collateral ligament releases was biomechanically quantified. Large variation among specimens reflected the difficulty of ligament release and the need for intraoperative force monitoring. Two clinical trials were carried out to evaluate the device performance in a surgical environment. After the tibial cut, the medial and lateral tibiofemoral gaps ensuring the knee stability were determined from the device measurements and compared to the femoral cuts performed on the basis of standard instrumentation. The agreement between the two approaches was generally good. The only significant difference was measured on the first patient at 90° flexion. At this point, the surgeon also estimated that the knee was not optimally balanced, thus demonstrating the consistency between his perception and the device measurements. In conclusion, the proposed force-sensing device for assistance in ligament balancing during TKA provides accurate, reliable and useful measurements. In addition to the precise imbalance assessment based on the measurement of forces and moments, important clinical advantages, such as the possibility to keep the patella in its anatomical place during the measurement or the real-time force monitoring during the delicate phase of ligament release, were demonstrated. The encouraging results of the in-vivo trial proved the usability of the device in a surgical environment and opens the way for larger clinical studies. The developed device has thus potential to improve the ligament balancing procedure, the consistency of surgery and the lifetime of TKA, illustrating thereby the clinical benefit of measuring forces during orthopaedic surgeries.

Impairments of prehension kinematics and grasping forces in patients with cerebellar degeneration and the relationship to cerebellar atrophy

Hemidactylus turcicus is a small gekkonid lizard native to the Middle East and Asia that is known to exhibit sexual dimorphism in head size. Several potential explanations exist for the evolution and maintenance of sexual dimorphism in lizards. We tested 2 of these competing hypotheses concerning diet partitioning and differential growth. We found no differences in average meal size (volume) or in any single dimension of prey size for similarly sized males and females. Allometric patterns of increases in head size also were measured in males and females. We found that males exhibited a mixture of isometric and positively allometric patterns of head size increase, whereas females exhibited isometric and negatively allometric patterns. Thus, we concluded that sexual dimorphism in head size is not the result of diet partitioning but instead of differential growth patterns following sexual maturity in males and females.

This paper describes the development of processing techniques to extract roller cone bit wear information from near-bit force and acceleration measurements. Laboratory data have been col-lected for bits in a variety of wear states operating in a small atmospheric drilling machine and under the simulated downhole conditions provided by a fullscale drilling test station. This has given information on how bit cone speed increases as the wear process progressively reduces the cone radius. Recent studies are reported and the detailed dynamic features of force mea-surements made on laboratory drilling machines are described. The improved understanding of the nature of the bit signature has led to the development of novel processing techniques for the detection of bit wear from near-bit measurements. A com-parison with results obtained from bit modelling work is also presented.

Background: The most important diagnostic feature of the audiogram is the air-bone gap. Both false and missed air-bone gap lead to misdiagnosed. Acoustic radiation from the bone vibrator, especially at high frequency, causes hearing through the air-conduction reflects false air-bone gap. Materials and Methods: A total of 67 (134 ears) individuals with age ranged between 14 and 48 years (mean age: 36.1 years) were taken in this study. Who had external auditory canal clean and dry with intact tympanic membrane and the air-bone gap >10 dB in high frequencies (i.e., 2000 Hz, 3000 Hz, and 4000 Hz) were included in the study. All the clients who had air-bone gap >10 dB in the frequencies of 2000, 3000, and 4000 Hz were reassessed for their bone-conduction thresholds by closing the external ear canal with the patient's own index finger during testing. Study Design and Statistics: This was an experimental study where statistical analysis and ANOVA was done to compare between open ear canal and closed ear canal condition among frequencies. One-way repeated measure ANOVA along with Bonferroni comparison test was done separately for open ear canal and closed ear canal conditions. Results: Results revealed significant difference in air-bone gap (ABG) between two conditions which were increasingly more for higher frequencies, that is, 2000 Hz, 3000 Hz, and 4000 Hz compared to lower frequencies. Conclusion: Acoustic radiation is the sound energy that may be detected by air-conduction mechanisms which escape from a bone vibrator. When the external auditory meatus is occluded, the acoustic radiation phenomenon can be controlled or avoided, enabling bone measures at the higher frequencies, especially at 2000, 3000, and 4,000 Hz to be more accurate. Thus provides more accurate audiometric diagnosis which is most importantly based on ABG.

Accurate Measurement of High-Bandwidth Nanomilling Forces

The purposes of the study were to establish isometric torque reference values for healthy 6- to 8-year-old children for 6 lower extremity muscles and determine the effects of gender, age, height, weight, and physical activity upon strength. A hand-held dynamometer was used to obtain force/torque values for 154 children. Age-referenced force/torque and cutoff values are provided for each muscle group. Torque increased with age and height for all muscles and with weight for all muscles except knee extensors. No gender differences were found. Children who participated in 3 or more hours per week in organized sports were stronger in 4 of 6 muscles; the number of hours spent in active play did not affect torque. This study provides hand-held dynamometer strength reference values to enable clinicians to determine if clients of the same age, height, and weight have muscle weakness.

Prey selection in many species is known to change ontogenetically, suggesting that associated changes in trophic structure may also be important. Several studies have examined relationships between prey selection and the size of trophic structures; however, few have explored these changes over ontogeny or the effects that they may have on a species broader ecology. The present study addressed this issue by examining relationships between changes in head size and prey selection in juveniles and adults from three populations of the python Morelia viridis and related them to changes in sexual maturity and ontogenetic changes in colour (OCC). Our scaling data for head size showed that juveniles and adults scaled mostly with negative allometry, and allometric slopes were significantly different before and after OCC. The change in head shape allometry was strongly associated with changes in prey selection from ectothermic to endothermic prey and with OCC in two of the three populations studied. OCC in the other population varied widely and may be the result of isolation on an oceanic island. Negatively allometric head growth is common in vertebrates and may serve a functional role in M. viridis by reducing the maximum ingestible prey size in adults, thus aiding arboreality. Our data do not allow us to test which of these changes have causal or resultant effects on one another; however, we suggest they may be part of an overall evolutionary defence‐foraging strategy that circumvents costs imposed by restricting foraging opportunities to certain habitats. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, , ••‐••.

The magnitude and origin of audiometric air-bone gaps in the range 3 kHz to 8 kHz was investigated in 20 normal subjects. The average gap ranged from a minimum of about 3 dB at 3 kHz to a maximum of about 19 dB at 6 kHz. Approximately 5 dB of the gap at high frequencies is caused by excess air-radiated sound from the bone vibrator. A larger error appears to result from discrepancies between the air and bone conduction standards to which audiometers are calibrated. These errors may influence diagnosis and we recommend that bone conduction tests at frequencies greater than 4 kHz are avoided. These findings have implications for medico-legal work where small air-bone gaps have diagnostic significance.

Robotics is one area where biomimetics, a field devoted to mimicking natural systems to address difficult human problems, has made great strides. Precise force measurement and analysis are vital to this field because they are necessary to reproduce and comprehend natural phenomena. This study addresses the challenge of accurate force measurement by developing a load cell-based device. It specifically assesses the impact of the taring process on measurement accuracy. The Weighted Least Squares (WLS) method is employed to thoroughly quantify the uncertainty of the device, ensuring reliability. The findings suggest that the single-input taring process contributes to variations in standard deviation, with accuracy peaking near the tared value and decreasing as the mass deviates from it. The linear calibration equation derived from WLS showed minimal variation in estimated mass values, with uncertainties ua = 2 10-6 and ub = 8 10-4. However, the expanded uncertainty increased with the input mass, largely due to the inherent uncertainty of the mass balance. Despite this, the hysteresis of the system was negligible, and its sensitivity of 0.01 N/g made it suitable for detecting small force fluctuations in biomimetic models. The study concludes that while the relative value of the maximum combined uncertainty, ULc = ±0.2% FSS, exceeds the reference specifications of the load cell, it remains adequate for applications requiring moderate precision. Future research will reduce mass balance uncertainty and consider environmental factors, thereby improving system effectiveness in biomimetic research.

Prototype cantilevers are presented that enable quantitative surface force measurements using contact-mode atomic force microscopy (AFM). The "hammerhead" cantilevers facilitate precise optical lever system calibrations for cantilever flexure and torsion, enabling quantifiable adhesion measurements and friction measurements by lateral force microscopy (LFM). Critically, a single hammerhead cantilever of known flexural stiffness and probe length dimension can be used to perform both a system calibration as well as surface force measurements in situ, which greatly increases force measurement precision and accuracy. During LFM calibration mode, a hammerhead cantilever allows an optical lever "torque sensitivity" to be generated for the quantification of LFM friction forces. Precise calibrations were performed on two different AFM instruments, in which torque sensitivity values were specified with sub-percent relative uncertainty. To examine the potential for accurate lateral force measurements using the prototype cantilevers, finite element analysis predicted measurement errors of a few percent or less, which could be reduced via refinement of calibration methodology or cantilever design. The cantilevers are compatible with commercial AFM instrumentation and can be used for other AFM techniques such as contact imaging and dynamic mode measurements.

Accurate time-resolved force measurements for complex experimental systems are important for minimizing erroneous and misleading data. These measurements become difficult when a natural frequency of the system is in or near the expected frequency domain of the time-varying force being applied. In the cases where it is not possible to avoid this occurrence, the experimenter typically abandons the setup. This work presents an inverse filter method to compensate for the dynamic response of the measurement system. A two degree-of-freedom measurement system is used to obtain force measurements with dominant forcing frequencies above and below the first natural frequency of the system. The results show that inverse filtering can be used along with digital low pass filters to correct amplification and phase shift due to the dynamic response of the measurement system to within ±4.0 % of total forcing amplitude and ±5.0∘. A simple cam follower mechanism is proposed as a method of low-frequency dynamic testing.

Auditory brainstem response (ABR) is a valuable tool for the diagnosis of hearing disorders in dogs, but is hampered by the lack of published normative data. The aim of the present study was to obtain normative data for bone conduction, without masking, under clearly defined conditions. Subjects comprised 20 Dalmatians and 20 Jack Russell terriers. Two methods were investigated: holding the bone vibrator against the head by hand or by applying a 500 g weight. The results revealed no difference in hearing threshold between the two breeds or for the two methods of applying the bone vibrator to the head. The mean hearing threshold was close to 0 decibels re normal hearing level (dB nHL), which is the biological norm for humans. Hence, bone conduction thresholds can be used for confirmation of conductive hearing impairment in the dog, in the same way as in humans.

The Swamp Skink, Egernia coventryi, is an uncommon species that inhabits wetlands and swampy heaths in predominantly coastal regions of southeastern Australia. We examined museum specimens to quantify the diet, reproduction, and sexual dimorphism of E. coventryi. The mean SVL of both adult males and females was 85–86 mm, and individuals attain sexual maturity at about 72–74 mm SVL. Although the sexes did not differ in body size (SVL), males have longer and broader heads than females, both in terms of absolute head size and head size relative to body size. Females ovulate in September and October with parturition occurring in late January or early February. However, not all adult females collected during the breeding season were pregnant, suggesting that female E. coventryi may not always breed annually. Litter size in E. coventryi ranged from 1–4, with a mean litter size of 2.6. Egernia coventryi is omnivorous and a largely opportunistic forager, with spiders (found in 16 of 47 individuals, 34%), beetles (26%), lepidopterans (17%), ants (11%), hemipterans (9%) and aquatic amphipods (9%) the most common animal prey items found in the alimentary canals of individuals. However, plant materials (e.g., fruits/berries, seeds, other vegetation) also were found in the stomachs of the majority of the specimens (66%). Sloughed skin (26%) and the tail fragment of another E. coventryi were found in the alimentary tracts of preserved specimens. The majority of specimens (76%) were infested with endoparasites, with one specimen containing 130 nematodes, although the mean number of nematodes per specimen was 8.87.

Sexual Dimorphism, Reproduction and Prey of Long Tailed Lizard Takydromus sexlineatus Daudin, 1802 (Lacertilia :Lacertidae). The morphology and reproductive biology of Takydromus sexlineatus were studied in Bogor. Males are larger than females. There is sexual dimorphism on head size and tail length (larger and longer tail on males) of body size among sexually mature adults, apparently as a consequence of sexual selection. The diet of T. sexlineatus consists of variety of insects and their larvae, arachnids, decapods and snails. Most of the diet are insect (more than 70 % for adults and juveniles). There are higher prey competitions at adult skinks between males and females, adult females and juveniles, but not between adult males and juveniles. The length of adult males and females are 44.6 - 58.1 mm and 49.6 - 62.3 mm respectively, lay eggs throughout the year with 2 -3 clutches, per clutch consists of 1 - 3 eggs. Key words: Lizard, Takydromus, Ecology, Sexual Dimorphism, Prey, Reproduction, Bogor, Indonesia