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Sample records for biomechanical effects decline

  1. Laterally wedged insoles in knee osteoarthritis: do biomechanical effects decline after one month of wear?

    Directory of Open Access Journals (Sweden)

    Bennell Kim L

    2009-11-01

    Full Text Available Abstract Objective This study aimed to determine whether the effect of laterally wedged insoles on the adduction moment in knee osteoarthritis (OA declined after one month of wear, and whether higher reported use of insoles was associated with a reduced effect on the adduction moment at one month. Methods Twenty people with medial compartment OA underwent gait analysis in their own shoes wearing i no insoles and; ii insoles wedged laterally 5° in random order. Testing occurred at baseline and after one month of use of the insoles. Participants recorded daily use of insoles in a log-book. Outcomes were the first and second peak external knee adduction moment and the adduction angular impulse, compared across conditions and time with repeated measures general linear models. Correlations were obtained between total insole use and change in gait parameters with used insoles at one month, and change scores were compared between high and low users of insoles using general linear models. Results There was a significant main effect for condition, whereby insoles significantly reduced the adduction moment (all p Conclusion Effects of laterally wedged insoles on the adduction moment do not appear to decline after one month of continuous use, suggesting that significant wedge degradation does not occur over the short-term.

  2. The effect of different decline angles on the biomechanics of double limb squats and the implications to clinical and training practice

    Directory of Open Access Journals (Sweden)

    Richards Jim

    2016-09-01

    Full Text Available Bilateral decline squatting has been well documented as a rehabilitation exercise, however, little information exists on the optimum angle of decline. The aim of this study was to determine the ankle and knee angle, moments, the patellofemoral joint load, patellar tendon load and associated muscle activity while performing a double limb squat at different decline angles and the implications to rehabilitation. Eighteen healthy subjects performed double limb squats at 6 angles of declination: 0, 5, 10, 15, 20 and 25 degrees. The range of motion of the knee and ankle joints, external moments, the patellofemoral/patellar tendon load and integrated EMG of gastrocnemius, tibialis anterior, rectus femoris and biceps femoris were evaluated. As the decline angle increased up to 20 degrees, the range of motion possible at the ankle and knee increased. The joint moments showed a decrease at the ankle up to 15 degrees and an increase at the knee up to 25 degrees, indicating a progressive reduction in loading around the ankle with a corresponding increase of the load in the patellar tendon and patellofemoral joint. These trends were supported by a decrease in tibialis anterior activity and an increase in the rectus femoris activity up to 15 degrees declination. However, gastrocnemius and biceps femoris activity increased as the decline angle increased above 15 degrees. The action of gastrocnemius and biceps femoris stabilises the knee against an anterior displacement of the femur on the tibia. These findings would suggest that there is little benefit in using a decline angle greater than 15-20 degrees unless the purpose is to offer an additional stability challenge to the knee joint.

  3. Biomechanical analysis of the single-leg decline squat

    NARCIS (Netherlands)

    Zwerver, J.; Bredeweg, S. W.; Hof, A. L.

    2007-01-01

    Background: The single-leg squat on a 25 decline board has been described as a clinical assessment tool and as a rehabilitation exercise for patients with patellar tendinopathy. Several assumptions have been made about its working mechanism on patellar load and patellofemoral forces, but these are n

  4. The biomechanical and physiological effect of two dynamic workstations

    NARCIS (Netherlands)

    Botter, J.; Burford, E.M.; Commissaris, D.; Könemann, R.; Mastrigt, S.H.V.; Ellegast, R.P.

    2013-01-01

    The aim of this research paper was to investigate the effect, both biomechanically and physiologically, of two dynamic workstations currently available on the commercial market. The dynamic workstations tested, namely the Treadmill Desk by LifeSpan and the LifeBalance Station by RightAngle, were com

  5. Weightbath hydrotraction treatment: application, biomechanics, and clinical effects

    Directory of Open Access Journals (Sweden)

    Márta Kurutz

    2010-04-01

    Full Text Available Márta Kurutz1, Tamás Bender21Department of Structural Mechanics, Budapest University of Technology and Economics, Hungary; 2Department of Physical Medicine, Polyclinic and Hospital of the Hospitaller Brothers of St. John of God, Budapest, Medical University of Szeged, HungaryBackground and purpose: Weightbath hydrotraction treatment (WHT is a simple noninvasive effective method of hydro- or balneotherapy to stretch the spine or lower limbs, applied successfully in hospitals and health resort sanitaria in Hungary for more than fifty years. This study aims to introduce WHT with its biomechanical and clinical effects. History, development, equipment, modes of application, biomechanics, spinal traction forces and elongations, indications and contraindications of WHT are precented.Subjects and methods: The calculation of traction forces acting along the spinal column during the treatment is described together with the mode of suspension and the position of extra weight loads applied. The biomechanics of the treatment are completed by in vivo measured elongations of lumbar segments using a special underwater ultrasound measuring method. The clinical effects, indications, and contraindications of the treatment are also presented.Results: In the underwater cervical suspension of a human body, approximately 25 N stretching load occurs in the cervical spine, and about 11 N occurs in the lumbar spine. By applying extra weights, the above tensile forces along the spinal column can be increased. Thus, the traction effect can be controlled by applying such loads during the treatment. Elongations of segments L3–L4, L4–L5, and L5–S1 were measured during the usual WHT of patients suspended cervically in water for 20 minutes, loaded by 20–20 N lead weights on the ankles. The mean initial elastic elongations of spinal segments were about 0.8 mm for patients aged under 40 years, 0.5 mm between 40–60 years, and 0.2 mm for patients over 60 years. The mean

  6. Biomechanical Analysis of the Effects of Bilateral Hinged Knee Bracing

    Science.gov (United States)

    Lee, Hangil; Ha, Dokyeong; Kang, Yeoun-Seung; Park, Hyung-Soon

    2016-01-01

    This research analyzed the effect of bilateral hinged knee braces on a healthy knee from a biomechanical frame in vivo. This was accomplished by fitting a knee brace with two customized wireless force/torque (F/T) sensors that could readily record force and torque during live motion, while the kinetics at the knee were computed using the inverse dynamics of the motion capture and force plate data. Four tasks to test the brace’s effects were drop vertical jumping, pivoting, stop vertical jumping, and cutting. The results showed that the hinges in the knee brace can absorb up to 18% of the force and 2.7% of the torque at the knee during various athletic motions. Thus, the hinges demonstrated minimal effect in reducing the mechanical load on the knee. There were limitations concerning the consistency of the motions performed by the subjects during the trials and the influence of the other portions of the brace to evaluate the overall effectiveness of the brace as a whole. Future works may incorporate a fatigue protocol and injured subjects to better determine the effects of the brace. There is still a need for more research on the biomechanical influence of knee braces to develop safer and more effective products. PMID:27379233

  7. Declining ecosystem health and the dilution effect.

    Science.gov (United States)

    Khalil, Hussein; Ecke, Frauke; Evander, Magnus; Magnusson, Magnus; Hörnfeldt, Birger

    2016-01-01

    The "dilution effect" implies that where species vary in susceptibility to infection by a pathogen, higher diversity often leads to lower infection prevalence in hosts. For directly transmitted pathogens, non-host species may "dilute" infection directly (1) and indirectly (2). Competitors and predators may (1) alter host behavior to reduce pathogen transmission or (2) reduce host density. In a well-studied system, we tested the dilution of the zoonotic Puumala hantavirus (PUUV) in bank voles (Myodes glareolus) by two competitors and a predator. Our study was based on long-term PUUV infection data (2003-2013) in northern Sweden. The field vole (Microtus agrestis) and the common shrew (Sorex araneus) are bank vole competitors and Tengmalm's owl (Aegolius funereus) is a main predator of bank voles. Infection probability in bank voles decreased when common shrew density increased, suggesting that common shrews reduced PUUV transmission. Field voles suppressed bank vole density in meadows and clear-cuts and indirectly diluted PUUV infection. Further, Tengmalm's owl decline in 1980-2013 may have contributed to higher PUUV infection rates in bank voles in 2003-2013 compared to 1979-1986. Our study provides further evidence for dilution effect and suggests that owls may have an important role in reducing disease risk. PMID:27499001

  8. Effects of cyclosporin-a on rat skeletal biomechanical properties

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    Wang Junfei

    2011-10-01

    Full Text Available Abstract Background Cyclosprin A (CsA has been widely used clinically to treat the patients who have undergone organ transplantation or acquired autoimmune disease. The purpose of this study is to determine the effects of three different doses of CsA (1.5, 7.5, 15 mg/kg body weight on the skeletal biomechanical proprieties at different anatomic sites in rats. Methods Fifty-six male 3-month-old Wistar rats were divided into five groups. Eight rats were randomly chosen as the basal group, while the others were randomly distributed into four groups of 12 animals each. One group was used as controls and received daily subcutaneous injection of 1 ml of saline solution; another three experimental groups were injected subcutaneously with CsA in a daily dose of 1.5, 7.5, and 15 mg/kg body weight respectively for 60 days. The bone biomechanical proprieties, the bone mineral density, as well as the trabecular bone architecture were measured at different anatomic sites, i.e. the lumbar vertebra, the middle femur shaft, and the proximal femur. Results CsA therapy at 7.5 and 1.5 mg/kg can significantly reduce the ultimate force, the ultimate stress and the energy absorption per unit of bone volume of the lumbar vertebra, with no effect on the middle femur. CsA therapy at 7.5 mg/kg can significantly reduce the ultimate force, the ultimate stress and the Young's modulus of the femoral neck, but not CsA at 1.5 mg/kg. Furthermore, CsA therapy at 7.5 and 1.5 mg/kg can significantly reduce the bone mineral density of the lumber vertebra and the proximal femur, but have no effect on the middle femur. CsA therapy at 7.5 and 1.5 mg/kg can also significantly reduce the bone volume fraction of the proximal tibia and the lumber vertebra, but has no effect on the cortical thickness of the middle femoral shaft. In the 15 mg/kg CsA group only one rat survived, and the kidney and liver histology of the survived rat showed extensive tissue necrosis. Conclusion Long-term use

  9. Biomechanical Effect of Chinese Immobilization Using Little Splint

    Institute of Scientific and Technical Information of China (English)

    WANG Mei; ZHAO Namula

    2014-01-01

    Immobilization using little splint is an original innovation of Chinese people for the fracture fixation, which is simple to use and clinically effective. It was found that Chinese immobilization using little splint can make the non-invasive, uncovering, and trouble free healing of bone fracture via harmonious unity of the structure stability and the force balance, of the motion stability and the stress adaptability, of the constant and discontinuous physiological stress. The biomechanical effect of Chinese immobilization using little splint, including entirety, dynamic, and functional fixity, is the root cause of its inheritance and the use up to now, and also is a direction of today's fracture fixation towards personalization, individuality and entirety.

  10. Organizational Decline and Effectiveness in Private Higher Education.

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    Smart, John C.

    1989-01-01

    A study to determine the relationship between organizational decline and three domains of effectiveness (academic, morale, and external adaptation) in private colleges and universities is discussed. The results demonstrate that the relationship between decline and effectiveness is not uniform across three types of institutions. (Author/MLW)

  11. Effects of resistance training fatigue on joint biomechanics.

    Science.gov (United States)

    Hooper, David R; Szivak, Tunde K; Distefano, Lindsay J; Comstock, Brett A; Dunn-Lewis, Courtenay; Apicella, Jenna M; Kelly, Neil A; Creighton, Brent C; Volek, Jeff S; Maresh, Carl M; Kraemer, William J

    2013-01-01

    Resistance training has been found to have a multitude of benefits. However, when performed with short rest, resistance training can result in substantial fatigue, which may have a negative impact on exercise technique. The purpose of this study is to examine the effects of fatigue from resistance exercise on joint biomechanics to determine what residual movement effects may exist after the workout. Twelve men with at least 6 months of resistance training experience (age 24 ± 4.2 years, height 173.1 ± 3.6 cm, weight 76.9 ± 7.8 kg) performed 5 body weight squats before (pretest) and after (posttest) a highly fatiguing resistance training workout. Lower extremity biomechanics were assessed using a 3-dimensional motion analysis system during these squats. Peak angle, total displacement, and rate were assessed for knee flexion, trunk flexion, hip flexion, hip rotation, and hip adduction. Results showed a significant decrease in peak angle for knee flexion (Pre: 120.28 ± 11.93°, Post: 104.46 ± 9.85°), hip flexion (Pre: -109.42 ± 12.49°, Post: -95.8 ± 12.30°), and hip adduction (Pre: -23.32 ± 7.04°, Post: -17.30 ± 8.79°). There was a significant reduction in angular displacement for knee flexion (Pre: 115.56 ± 10.55°, Post: 103.35 ± 10.49°), hip flexion (Pre: 97.94 ± 10.69°, Post: 90.51 ± 13.22°), hip adduction (Pre: 17.79 ± 7.36°, Post: 11.89 ± 4.34°), and hip rotation (Pre: 30.72 ± 12.28, Post: 20.48 ± 10.12). There was also a significant reduction in displacement rate for knee flexion (Pre: 2.20 ± 0.20, Post: 1.98 ± 0.20), hip flexion (Pre: 1.92 ± 0.20, Post: 1.76 ± 0.27), hip adduction (Pre: -0.44 ± 0.17, Post: -0.31 ± 0.17), and hip rotation (Pre: 0.59 ± 0.23, Post: 0.38 ± 0.21). This study demonstrated that there are lasting residual effects on movement capabilities after a high-intensity short rest protocol. Thus, strength and conditioning coaches must be careful to monitor movements and exercise techniques after such workouts

  12. Effects of spaceflight on rat humerus geometry, biomechanics, and biochemistry

    Science.gov (United States)

    Vailas, A. C.; Zernicke, R. F.; Grindeland, R. E.; Kaplansky, A.; Durnova, G. N.; Li, K. C.; Martinez, D. A.

    1990-01-01

    The effects of a 12.5-day spaceflight (Cosmos 1887 biosatellite) on the geometric, biomechanical, and biochemical characteristics of humeri of male specific pathogen-free rats were examined. Humeri of age-matched basal control, synchronous control, and vivarium control rats were contrasted with the flight bones to examine the influence of growth and space environment on bone development. Lack of humerus longitudinal growth occurred during the 12.5 days in spaceflight. In addition, the normal mid-diaphysial periosteal appositional growth was affected; compared with their controls, the spaceflight humeri had less cortical cross-sectional area, smaller periosteal circumferences, smaller anterior-posterior periosteal diameters, and smaller second moments of area with respect to the bending and nonbending axes. The flexural rigidity of the flight humeri was comparable to that of the younger basal control rats and significantly less than that of the synchronous and vivarium controls; the elastic moduli of all four groups, nonetheless, were not significantly different. Generally, the matrix biochemistry of the mid-diaphysial cross sections showed no differences among groups. Thus, the spaceflight differences in humeral mechanical strength and flexural rigidity were probably a result of the differences in humeral geometry rather than material properties.

  13. WHAT IS A MOMENT ARM? CALCULATING MUSCLE EFFECTIVENESS IN BIOMECHANICAL MODELS USING GENERALIZED COORDINATES

    OpenAIRE

    Sherman, Michael A.; Seth, Ajay; Delp, Scott L.

    2013-01-01

    Biomechanics researchers often use multibody models to represent biological systems. However, the mapping from biology to mechanics and back can be problematic. OpenSim is a popular open source tool used for this purpose, mapping between biological specifications and an underlying generalized coordinate multibody system called Simbody. One quantity of interest to biomechanical researchers and clinicians is “muscle moment arm,” a measure of the effectiveness of a muscle at contributing to a pa...

  14. Raster-stereographic evaluation of the effects of biomechanical foot orthoses in patients with scoliosis

    Science.gov (United States)

    Park, So Min; Ahn, Sang-Ho; Lee, A-Young; Park, In-Sik; Cho, Yun-Woo

    2016-01-01

    [Purpose] Little is known about the effects of biomechanical foot orthoses in scoliosis, as determined by raster stereography. The objective of this study was to investigate the effect of individually manufactured biomechanical foot orthoses on scoliosis angle, trunk imbalance, and pelvic obliquity by comparing them with general insoles by using DIERS formetric 4 dimensional in patients with scoliosis. [Subjects and Methods] Twenty-six patients with scoliosis were recruited at Yeungnam University Hospital and allocated equally to one of two groups, the biomechanical foot orthoses group or the control group. Parameters, such as, trunk rotation, imbalance, and scoliosis angle, were obtained using a DIERS formetric 4D. [Results] Scoliosis angle, pelvic obliquity, and trunk imbalance were significantly different between the two groups and improved in the biomechanical foot orthoses group with time, but no significant improvement in any parameter was observed in the control group. [Conclusion] Biomechanical foot orthoses could be effective in patients with scoliosis, and DIERS formetric 4D provides a useful method for evaluating scoliosis parameters. PMID:27512245

  15. Raster-stereographic evaluation of the effects of biomechanical foot orthoses in patients with scoliosis.

    Science.gov (United States)

    Park, So Min; Ahn, Sang-Ho; Lee, A-Young; Park, In-Sik; Cho, Yun-Woo

    2016-07-01

    [Purpose] Little is known about the effects of biomechanical foot orthoses in scoliosis, as determined by raster stereography. The objective of this study was to investigate the effect of individually manufactured biomechanical foot orthoses on scoliosis angle, trunk imbalance, and pelvic obliquity by comparing them with general insoles by using DIERS formetric 4 dimensional in patients with scoliosis. [Subjects and Methods] Twenty-six patients with scoliosis were recruited at Yeungnam University Hospital and allocated equally to one of two groups, the biomechanical foot orthoses group or the control group. Parameters, such as, trunk rotation, imbalance, and scoliosis angle, were obtained using a DIERS formetric 4D. [Results] Scoliosis angle, pelvic obliquity, and trunk imbalance were significantly different between the two groups and improved in the biomechanical foot orthoses group with time, but no significant improvement in any parameter was observed in the control group. [Conclusion] Biomechanical foot orthoses could be effective in patients with scoliosis, and DIERS formetric 4D provides a useful method for evaluating scoliosis parameters. PMID:27512245

  16. The effect of bacterial infection on the biomechanical properties of biological mesh in a rat model.

    Directory of Open Access Journals (Sweden)

    Charles F Bellows

    Full Text Available BACKGROUND: The use of biologic mesh to repair abdominal wall defects in contaminated surgical fields is becoming the standard of practice. However, failure rates and infections of these materials persist clinically. The purpose of this study was to determine the mechanical properties of biologic mesh in response to a bacterial encounter. METHODS: A rat model of Staphylococcus aureus colonization and infection of subcutaneously implanted biologic mesh was used. Samples of biologic meshes (acellular human dermis (ADM and porcine small intestine submucosa (SIS were inoculated with various concentrations of methicillin-resistant Staphylococcus aureus [10(5, 10(9 colony-forming units] or saline (control prior to wound closure (n = 6 per group. After 10 or 20 days, meshes were explanted, and cultured for bacteria. Histological changes and bacterial recovery together with biomechanical properties were assessed. Data were compared using a 1-way ANOVA or a Mann-Whitney test, with p0.05. After inoculation with MRSA, a time, dose and material dependent decrease in the ultimate tensile strength and modulus of elasticity of SIS and ADM were noted compared to control values. CONCLUSION: The biomechanical properties of biologic mesh significantly decline after colonization with MRSA. Surgeons selecting a repair material should be aware of its biomechanical fate relative to other biologic materials when placed in a contaminated environment.

  17. Research and Teaching: Assessing the Effect of Problem-Based Learning on Undergraduate Student Learning in Biomechanics

    Science.gov (United States)

    Mandeville, David; Stoner, Mark

    2015-01-01

    The aim of this study was to assess the effect of using the problem-based learning (PBL) teaching strategy on student academic achievement and secondary learning outcomes when compared with the traditional lecture (TL) for an undergraduate Biomechanics course. Successive undergraduate Biomechanics courses--a TL cohort and a PBL cohort--were…

  18. Multiple stressor effects in relation to declining amphibian populations

    Science.gov (United States)

    2003-01-01

    This book represents the work of several authors who participated in the symposium entitled 'Multiple Stressor Effects in Relation to Declining Amphibian Populations' convened 16-17 April, 2002, in Pittsburgh, Pennsylvania. Declines of amphibian populations of varying severity have been observed for many years, and in the last 8 to 10 years considerable progress has been made in documenting the status and distribution of a range of amphibian species. Habitat alteration and destruction are likely linked to many amphibian declines, but a variety of other factors, both anthropogenic and natural, have been observed or proposed to have caused declines or extinctions of amphibian populations. Unfortunately, determining the environmental causes for the decline of many species has proven difficult. The goals of this symposium were three-fold. First, highlight ASTM's historic role in providing a forum for the standardization of amphibian toxicity test methods and the characterization of adverse effects potentially associated with chemical stressors. Second, demonstrate through case studies the current state of technical 'tools' available to biologists, ecologists, environmental scientists and natural resource professionals for assessing amphibian populations exposed to various environmental stressors. And third, characterize a process that brings a range of interdisciplinary technical and management tools to the tasks of causal analysis, especially as those relate to a multiple stressor risk assessment 'mind-set.' As part of the symposium, scientists and resource management professionals from diverse fields including ecotoxicology and chemistry, ecology and field biology, conservation biology, and natural resource management and policy contributed oral presentations and posters that addressed topics related to declining amphibian populations and the role that various stressors have in those losses. The papers contained in this publication reflect the commitment of ASTM

  19. Spaceflight effects on biomechanical and biochemical properties of rat vertebrae

    Science.gov (United States)

    Zernicke, R. F.; Vailas, A. C.; Grindeland, R. E.; Kaplansky, A.; Salem, G. J.; Martinez, D. A.

    1990-01-01

    The biomechanical and biochemical responses of lumbar vertebral bodies during a 12.5-day spaceflight (Cosmos 1887 biosatellite) were determined for rapidly growing rats (90-day-old, Czechoslovakian-Wistar). By use of age-matched vivarium controls (normal cage environment) and synchronous controls (simulated flight conditions), as well as a basal control group (killed before lift-off on the 1st day of flight), the combined influences of growth and space-flight could be examined. Centra of the sixth lumbar vertebrae (L6) were compressed to 50% strain at a fast strain rate while immersed in physiological buffer (37 degrees C). The body masses of vivarium and synchronous controls were significantly heavier than either the flight or basal controls. The flight group had an L6 vertebral body compressional stiffness that was 39% less than the vivarium controls, 47% less than the synchronous control, and 16% less than the basal controls. In addition, the average initial maximum load of the flight L6 was 22% less than vivarium controls and 18% less than the synchronous controls, whereas the linear compressional load of the flight group averaged 34% less than the vivarium and 25% less than the synchronous groups. The structural properties of the vertebrae from the 12.5-day-younger basal group closely resembled the flight vertebrae. Calcium, phosphorous, and hydroxyproline concentrations were not significantly different among the groups. Nevertheless, the lack of strength and stiffness development in spaceflight, coupled with a smaller proportion of mature hydroxypyridinoline cross-links, suggested that the 12.5 days of spaceflight slowed the maturation of trabecular bone in the vertebral bodies of rapidly growing rats.

  20. The effect of head trauma on fracture healing: biomechanical testing and finite element analysis

    OpenAIRE

    Ozan, Firat; Hasan YILDIZ; Bora, Osman Arslan; Pekedis, Mahmut; Coskun, Gulnihal Ay; Gore, Oya

    2010-01-01

    Objectives: We aimed to evaluate the effect of head trauma on fracture healing with biomechanical testing, to compare the results obtained from a femur model created by finite element analysis with experimental data, and to develop a finite element model that can be employed in femoral fractures. Methods: Twenty-two Wistar albino rats were randomized into two groups. The control group was subjected to femoral fracture followed by intramedullary fixation, whereas the head trauma group was ...

  1. Effects of heat treatment of wood on hydroxylapatite type mineral precipitation and biomechanical properties in vitro.

    Science.gov (United States)

    Rekola, J; Lassila, L V J; Hirvonen, J; Lahdenperä, M; Grenman, R; Aho, A J; Vallittu, P K

    2010-08-01

    Wood is a natural fiber reinforced composite. It structurally resembles bone tissue to some extent. Specially heat-treated birch wood has been used as a model material for further development of synthetic fiber reinforced composites (FRC) for medical and dental use. In previous studies it has been shown, that heat treatment has a positive effect on the osteoconductivity of an implanted wood. In this study the effects of two different heat treatment temperatures (140 and 200 degrees C) on wood were studied in vitro. Untreated wood was used as a control material. Heat treatment induced biomechanical changes were studied with flexural and compressive tests on dry birch wood as well as on wood after 63 days of simulated body fluid (SBF) immersion. Dimensional changes, SBF sorption and hydroxylapatite type mineral formation were also assessed. The results showed that SBF immersion decreases the biomechanical performance of wood and that the heat treatment diminishes the effect of SBF immersion on biomechanical properties. With scanning electron microscopy and energy dispersive X-ray analysis it was shown that hydroxylapatite type mineral precipitation formed on the 200 degrees C heat-treated wood. An increased weight gain of the same material during SBF immersion supported this finding. The results of this study give more detailed insight of the biologically relevant changes that heat treatment induces in wood material. Furthermore the findings in this study are in line with previous in vivo studies.

  2. The effect of substrate compliance on the biomechanics of gibbon leaps.

    Science.gov (United States)

    Channon, Anthony J; Günther, Michael M; Crompton, Robin H; D'Août, Kristiaan; Preuschoft, Holger; Vereecke, Evie E

    2011-02-15

    The storage and recovery of elastic strain energy in the musculoskeletal systems of locomoting animals has been extensively studied, yet the external environment represents a second potentially useful energy store that has often been neglected. Recent studies have highlighted the ability of orangutans to usefully recover energy from swaying trees to minimise the cost of gap crossing. Although mechanically similar mechanisms have been hypothesised for wild leaping primates, to date no such energy recovery mechanisms have been demonstrated biomechanically in leapers. We used a setup consisting of a forceplate and two high-speed video cameras to conduct a biomechanical analysis of captive gibbons leaping from stiff and compliant poles. We found that the gibbons minimised pole deflection by using different leaping strategies. Two leap types were used: slower orthograde leaps and more rapid pronograde leaps. The slower leaps used a wider hip joint excursion to negate the downward movement of the pole, using more impulse to power the leap, but with no increase in work done on the centre of mass. Greater hip excursion also minimised the effective leap distance during orthograde leaps. The more rapid leaps conversely applied peak force earlier in stance where the pole was effectively stiffer, minimising deflection and potential energy loss. Neither leap type appeared to usefully recover energy from the pole to increase leap performance, but the gibbons demonstrated an ability to best adapt their leap biomechanics to counter the negative effects of the compliant pole.

  3. A novel technique of unilateral percutaneous kyphoplasty achieves effective biomechanical strength and reduces radiation exposure

    Science.gov (United States)

    Zhuang, Yan; Yang, Lei; Li, Haijun; Ren, Yajun; Cao, Xiaojian

    2016-01-01

    Purpose: To develop a novel technique of percutaneous kyphoplasty (PKP) with effective biomechanical strength and lower radiation exposure. Methods: Thirty fresh lumbar vertebrae isolated from six hogs were decalcified and compressed to induce osteoporotic vertebral compression fractures. Kyphoplasty was performed using three different techniques (ten for each group): conventional unilateral approach (group A), conventional bilateral approach (group B) and novel unilateral approach (group C). Biomechanical indexes including Yield load and stiffness were tested before and after kyphoplasty. The anterior height of each vertebral body (AHVB) was measured before compression, after compression and after kyphoplasty. Frequency of C-arm use and volume of bone cement were also recorded in the process. Results: Compared with group A, our novel technique in group C can significantly improve the recovery of AHVB after compression fractures. However, there was no statistical difference between group B and group C. Values of Yield load in both group B and group C were statistically higher than that in group A, however, no significant difference was found between group B and C. Statistical results of stiffness were similar to Yield load. Regarding volume of bone cement and radiation exposure, the novel technique in group C needed more bone cement and fluoroscopy use than in group A but less than in group B. Conclusions: This novel device makes unilateral kyphoplasty feasible, safe and effective. In the premise of guaranteed biomechanical strength, the new technique significantly reduces risk of radiation exposure in kyphoplasty. PMID:27158403

  4. Effects of refrigeration and freezing on the electromechanical and biomechanical properties of articular cartilage.

    Science.gov (United States)

    Changoor, Adele; Fereydoonzad, Liah; Yaroshinsky, Alex; Buschmann, Michael D

    2010-06-01

    In vitro electromechanical and biomechanical testing of articular cartilage provide critical information about the structure and function of this tissue. Difficulties obtaining fresh tissue and lengthy experimental testing procedures often necessitate a storage protocol, which may adversely affect the functional properties of cartilage. The effects of storage at either 4°C for periods of 6 days and 12 days, or during a single freeze-thaw cycle at -20°C were examined in young bovine cartilage. Non-destructive electromechanical measurements and unconfined compression testing on 3 mm diameter disks were used to assess cartilage properties, including the streaming potential integral (SPI), fibril modulus (Ef), matrix modulus (Em), and permeability (k). Cartilage disks were also examined histologically. Compared with controls, significant decreases in SPI (to 32.3±5.5% of control values, prefrigeration at 4°C, but no significant changes were detected at day 6. A trend toward detecting a decrease in SPI (to 94.2±6.2% of control values, p=0.083) was identified following a single freeze-thaw cycle, but no detectable changes were observed for any biomechanical parameters. All numbers are mean±95% confidence interval. These results indicate that fresh cartilage can be stored in a humid chamber at 4°C for a maximum of 6 days with no detrimental effects to cartilage electromechanical and biomechanical properties, while one freeze-thaw cycle produces minimal deterioration of biomechanical and electromechanical properties. A comparison to literature suggested that particular attention should be paid to the manner in which specimens are thawed after freezing, specifically by minimizing thawing time at higher temperatures. PMID:20887036

  5. Detecting Early Biomechanical Effects of Zoledronic Acid on Femurs of Osteoporotic Female Rats

    Directory of Open Access Journals (Sweden)

    Evandro Pereira Palacio

    2012-01-01

    Full Text Available Aim. To investigate the biomechanical effects of zoledronic acid (ZA on femurs of female osteoporotic rats after follow-up periods of 9 and 12 months. Methods. Eighty female Wistar rats were prospectively assessed. At 60 days of age, the animals were randomly divided into two groups: bilateral oophorectomy (O (n=40 and sham surgery (S (n=40. At 90 days of age, groups O and S were randomly subdivided into four groups, according to whether 0.1 mg/kg of ZA or distilled water (DW was intraperitoneally administered: OZA (n=20, ODW (n=20, SZA (n=20, and SDW (n=20. The animals were sacrificed at 9 and 12 months after the administration of the substances, and then their right femurs were removed and analyzed biomechanically. Axial compression tests that focused on determining the maximum load (N, yield point (N, and stiffness coefficient (N/mm of the proximal femur were performed in the biomechanical study. Results. ZA significantly increased the maximum load and yield point, reducing the stiffness coefficient concerning the oophorectomy status and follow-up period. Conclusion. Zoledronic acid, at a dose of 0.1 mg/kg, significantly increased the maximum loads and yield points and reduced the stiffness coefficients in the femurs of female rats with osteoporosis caused by bilateral oophorectomy.

  6. Effects of Ankle Arthrodesis on Biomechanical Performance of the Entire Foot.

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    Yan Wang

    Full Text Available Ankle arthrodesis is one popular surgical treatment for ankle arthritis, chronic instability, and degenerative deformity. However, complications such as foot pain, joint arthritis, and bone fracture may cause patients to suffer other problems. Understanding the internal biomechanics of the foot is critical for assessing the effectiveness of ankle arthrodesis and provides a baseline for the surgical plan. This study aimed to understand the biomechanical effects of ankle arthrodesis on the entire foot and ankle using finite element analyses. A three-dimensional finite element model of the foot and ankle, involving 28 bones, 103 ligaments, the plantar fascia, major muscle groups, and encapsulated soft tissue, was developed and validated. The biomechanical performances of a normal foot and a foot with ankle arthrodesis were compared at three gait instants, first-peak, mid-stance, and second-peak.Changes in plantar pressure distribution, joint contact pressure and forces, von Mises stress on bone and foot deformation were predicted. Compared with those in the normal foot, the peak plantar pressure was increased and the center of pressure moved anteriorly in the foot with ankle arthrodesis. The talonavicular joint and joints of the first to third rays in the hind- and mid-foot bore the majority of the loading and sustained substantially increased loading after ankle arthrodesis. An average contact pressure of 2.14 MPa was predicted at the talonavicular joint after surgery and the maximum variation was shown to be 80% in joints of the first ray. The contact force and pressure of the subtalar joint decreased after surgery, indicating that arthritis at this joint was not necessarily a consequence of ankle arthrodesis but rather a progression of pre-existing degenerative changes. Von Mises stress in the second and third metatarsal bones at the second-peak instant increased to 52 MPa and 34 MPa, respectively, after surgery. These variations can provide

  7. Biomechanical analysis of hyoid bone displacement in videofluoroscopy: a systematic review of intervention effects.

    Science.gov (United States)

    van der Kruis, Jolien G J; Baijens, Laura W J; Speyer, Renée; Zwijnenberg, Iris

    2011-06-01

    This systematic review explores studies using biomechanical analysis of hyoid bone displacement in videofluoroscopy of swallowing as a spatial outcome parameter to evaluate intervention effects. Two authors independently carried out the literature search using the electronic databases Embase, PubMed, and Cochrane Library. Differences in their search findings were settled by discussion. The search was limited to publications in the English, German, French, Spanish, or Dutch language. MeSH terms were used, supplemented by free-text words to identify the most recent publications. In addition, reference lists were searched by hand. Only studies using videofluoroscopy to evaluate the biomechanical effects of swallowing interventions in dysphagic subjects were included in the review. While the body of literature on measuring hyoid bone displacement in videofluoroscopy has grown, only 12 studies met the inclusion criteria. Several of the 12 studies had methodological shortcomings. In general, the conclusions could not be compared across the studies because of their heterogeneous designs and outcome measures. Overall, several intervention effect studies reported significant results. In particular, bolus modification and swallowing maneuvers showed a greater range of hyoid bone displacement. In light of this review, further research on hyoid bone displacement as a spatial variable in well-defined patient populations using well-defined videofluoroscopic protocols to measure intervention effects is recommended.

  8. Amphibian decline: An integrated analysis of multiple stressor effects

    Science.gov (United States)

    Linder, G.; Krest, S.K.; Sparling, D. W.; Linder, G.; Krest, S.K.; Sparling, D.W.

    2003-01-01

    Capturing the attention and imagination of the public and the scientific community alike, the mysterious decline in amphibian populations drew scientists and resource managers from ecotoxicology and chemistry, ecology and field biology, conservation biology, and natural resource policy to a SETAC–Johnson Foundation workshop. Facilitating environmental stewardship, increasing capacity of the sciences to explain complex stressors, and educating the public on relationships among communities of all types motivated these experts to address amphibian decline and the role of various stressors in these losses.

  9. Biomechanical effects of lateral and medial wedge insoles on unilateral weight bearing.

    Science.gov (United States)

    Sawada, Tomonori; Kito, Nobuhiro; Yukimune, Masaki; Tokuda, Kazuki; Tanimoto, Kenji; Anan, Masaya; Takahashi, Makoto; Shinkoda, Koichi

    2016-01-01

    [Purpose] Lateral wedge insoles reduce the peak external knee adduction moment and are advocated for patients with knee osteoarthritis. However, some patients demonstrate adverse biomechanical effects with treatment. In this study, we examined the immediate effects of lateral and medial wedge insoles under unilateral weight bearing. [Subjects and Methods] Thirty healthy young adults participated in this study. The subjects were assessed by using the foot posture index, and were divided into three groups: normal foot, pronated foot, and supinated foot groups. The knee adduction moment and knee-ground reaction force lever arm under the studied conditions were measured by using a three-dimensional motion capture system and force plates. [Results] In the normal and pronated groups, the change in knee adduction moment significantly decreased under the lateral wedge insole condition compared with the medial wedge insole condition. In the normal group, the change in the knee-ground reaction force lever arm also significantly decreased under the lateral wedge insole condition than under the medial wedge insole condition. [Conclusion] Lateral wedge insoles significantly reduced the knee adduction moment and knee-ground reaction force lever arm during unilateral weight bearing in subjects with normal feet, and the biomechanical effects varied according to individual foot alignment.

  10. The effect of Masai Barefoot Technology (MBT) footwear on lower limb biomechanics: A systematic review.

    Science.gov (United States)

    Tan, Jade M; Auhl, Maria; Menz, Hylton B; Levinger, Pazit; Munteanu, Shannon E

    2016-01-01

    This systematic review evaluated the available evidence for the effects of Masai Barefoot Technology (MBT) footwear on lower limb biomechanics during gait. Electronic databases (MEDLINE, EMBASE, CINAHL, SPORTDiscus, and PubMed) were searched in January 2015. Methodological quality of included studies was evaluated using the Quality Index. Standardised mean differences and 95% confidence intervals were calculated, and meta-analysis was conducted where possible. 17 studies satisfied the inclusion criteria; 16 cross-sectional studies and one randomised control trial (RCT). Quality Index scores ranged from 7 to 12 (out of 15). All 17 studies investigated walking gait only. Evidence showed that MBT footwear caused asymptomatic individuals to walk with a shorter stride length, reduced peak hip flexion, increased peak knee extension, and reduced hip and knee range of motion throughout gait. All kinematic effects occurred in the sagittal plane. There was a trend towards a decrease in internal and external joint moments and power, except for the foot, where increases in force were observed. There were only a small number of changes to lower limb muscle amplitude and timing. No statistically significant effects were observed in symptomatic individuals with knee osteoarthritis or following total knee replacement, but there was an increase in cadence and a decrease in step length in individuals following tibiotalar arthrodesis. These findings suggest that MBT footwear does change lower limb biomechanics in both asymptomatic and symptomatic individuals during gait. However, further clinical trials need to be undertaken to determine whether these changes are therapeutically beneficial. PMID:26669956

  11. Aging of running shoes and its effect on mechanical and biomechanical variables: implications for runners.

    Science.gov (United States)

    Chambon, Nicolas; Sevrez, Violaine; Ly, Quoc Hung; Guéguen, Nils; Berton, Eric; Rao, Guillaume

    2014-01-01

    This study investigates the effect of running shoes' aging on mechanical and biomechanical parameters as a function of midsole materials (viscous, intermediate, elastic) and ground inclination. To this aim, heel area of the shoe (under calcaneal tuberosity) was first mechanically aged at realistic frequency and impact magnitudes based on a 660 km training plan. Stiffness (ST) and viscosity were then measured on both aged and matching new shoes, and repercussions on biomechanical variables (joint kinematics, muscular pre-activation, vertical ground reaction force and tibial acceleration) were assessed during a leg-extended stepping-down task designed to mimic the characteristics of running impacts. Shoes' aging led to increased ST (means: from 127 to 154 N ∙ mm(-1)) and decreased energy dissipation (viscosity) (means: from 2.19 to 1.88 J). The effects induced by mechanical changes on body kinematics were very small. However, they led with the elastic shoe to increased vastus lateralis pre-activation, tibial acceleration peak (means: from 4.5 g to 5.2 g) and rate. Among the three shoes tested, the shoe with intermediate midsole foam provided the best compromise between viscosity and elasticity. The optimum balance remains to be found for the design of shoes regarding at once cushioning, durability and injury prevention. PMID:24576090

  12. Study the effects of radon inhalation on biomechanical properties of blood in rats

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    Mostafa Fawzy Eissa

    2015-09-01

    Full Text Available Purpose: To investigate the effect of inhalation radon gas (Rn on the biomechanical properties of red blood cell of rats. Methods: 20 young healthy adult male albino rats were divided into equally 4 groups. The first group (0 served as control group, while the other three groups (I, II and III were exposed to Rn gas inside a chamber for 3, 5 and 7 weeks. The biomechanical properties of red blood cell of rats was performed by determine the rheological properties of blood and the osmotic fragility of red blood cells (RBCs. Results: The Rn doses received by every group of rats were found to 34.84, 58.07 and 81.30 mSv for 3, 5 and 7 weeks respectively (based on 12 exposure hours per week. The obtained results indicate that the viscosity, consistency index, yield stress and aggregation index increase with Rn doses. The osmotic fragility curves of irradiated groups shift toward lower values of NaCl concentration. The dispersion of hemolysis (S increased, at the same time an average osmotic fragility (H50% decreased. Conclusion: The results indicates that the exposure to radon alters the mechanical properties of red blood cells membrane (permeability and elasticity reflecting a change in its physiological properties. This mean that low levels of Rn gas are harmful to biological systems and the degree of damage was dose-dependent.

  13. Effects of antibacterial nanostructured composite films on vascular stents: hemodynamic behaviors, microstructural characteristics, and biomechanical properties.

    Science.gov (United States)

    Cheng, Han-Yi; Hsiao, Wen-Tien; Lin, Li-Hsiang; Hsu, Ya-Ju; Sinrang, Andi Wardihan; Ou, Keng-Liang

    2015-01-01

    The purpose of this research was to investigate stresses resulting from different thicknesses and compositions of hydrogenated Cu-incorporated diamond-like carbon (a-C:H/Cu) films at the interface between vascular stent and the artery using three-dimensional reversed finite element models (FEMs). Blood flow velocity variation in vessels with plaques was examined by angiography, and the a-C:H/Cu films were characterized by transmission electron microscopy to analyze surface morphology. FEMs were constructed using a computer-aided reverse design system, and the effects of antibacterial nanostructured composite films in the stress field were investigated. The maximum stress in the vascular stent occurred at the intersections of net-like structures. Data analysis indicated that the stress decreased by 15% in vascular stents with antibacterial nanostructured composite films compared to the control group, and the stress decreased with increasing film thickness. The present results confirmed that antibacterial nanostructured composite films improve the biomechanical properties of vascular stents and release abnormal stress to prevent restenosis. The results of the present study offer the clinical benefit of inducing superior biomechanical behavior in vascular stents.

  14. Investigation of chemical and physical properties of carbon nanotubes and their effects on cell biomechanics

    Science.gov (United States)

    Dong, Chenbo

    Cerasela Zoica Dinu, Effects of acid treatment on structure, properties and biocompatibility of carbon nanotubes, Applied Surface Science, 2013, 268, 261-268.) Chapter two shows how exposure to CNTs changes the biomechanical properties of fixed human lung epithelial cells (BEAS-2B cells). Specifically, by using Atomic Force Microscopy (AFM) nanoindentation technology, we demonstrated that cellular exposure to multi-walled carbon nanotubes (MWCNTs) for 24h induces significant changes in cellular biomechanics leading to increased cellular stiffness. The MWCNTs incubation also seemed to alter the surface area of the cells. Consequently, measures of the mechanical properties of the exposed cell could be used as indicators of its biological state and could offer valuable insights into the mechanisms associated with CNTs-induced genetic instability. (Publication: Chenbo Dong, Linda Sargent, Michael L Kashon, David Lowry, Jonathan S. Dordick, Steven H. Reynolds, Yon Rojanasakul and Cerasela Zoica Dinu, Expose to carbon nanotubes leads to change in cellular biomechanics, Advanced Healthcare Materials, 2013, 7, 945-951.) Chapter three links together the MWCNTs exposure duration, internalization and induced biomechanical changes in fixed cells. Our findings indicated that changes in biomechanical properties of the fixed cells are a function of the uptake and internalization of the MWCNTs as well as their uptake time. Specifically, short exposure time did not seem to lead to considerable changes in the elastic properties in the cellular system. However, longer cellular exposure to CNTs leads to a higher uptake and internalization of the nanotubes and a larger effect on the cell mechanics. Such changes could be related to CNTs interactions with cellular elements and could bring information on the CNT intrinsic toxicity. Chapter four talks about the potential of purified forms of CNTs with increased hydrophilicity to affect live human lung epithelial cells when used at occupational

  15. Effect of a biplanar osteotomy on primary stability following high tibial osteotomy: a biomechanical cadaver study.

    Science.gov (United States)

    Pape, Dietrich; Lorbach, Olaf; Schmitz, Christian; Busch, Lüder C; Van Giffen, Nicolien; Seil, Romain; Kohn, Dieter M

    2010-02-01

    Open-wedge high tibial osteotomy (HTO) is becoming increasingly popular for the treatment of varus gonarthrosis in the active patient. The various implants used in HTO differ with regard to its design, the fixation stability and osteotomy technique. It is assumed that the combination of a plate fixator with a biplanar, v-shaped osteotomy supports bone healing. So far, there are no biomechanical studies that quantify the stabilizing effect of a biplanar versus uniplanar osteotomy. We hypothesized that a significant increase in primary stability of bone-implant constructs is achieved when using a biplanar as opposed to a uniplanar osteotomy. Twenty-four fresh-frozen human tibiae were mounted in a metal cylinder, and open-wedge osteotomy (12 mm wedge size) was performed in a standardized fashion. Proximal and distal tibial segments were marked with tantalum markers of 0.8 mm diameter. Two different plates with locking screws were used for fixation: a short spacer plate (group 1, n = 12) and a plate fixator (group 2, n = 12). In six specimens of each group, a biplanar V-shaped osteotomy with a 110 degrees angulated anterior cut behind the tuberosity parallel to the ventral tibial shaft axis was performed. In the remaining six specimens of each group, a simple uniplanar osteotomy was performed in an oblique fashion. Axial compression of the tibiae was performed using a material testing machine under standardized alignment of the loading axis. Load-controlled cyclical staircase loading tests were performed. The specimens were radiographed simultaneously in two planes together with a biplanar calibration cage in front of a film plane with and without load after each subcycle. Radiostereometry allowed for serial quantification of plastic and elastic micromotion at the osteotomy site reflecting the stability provided by the combination of implant and osteotomy technique. No significant additional stabilizing effect of a biplanar osteotomy in craniocaudal and mediolateral

  16. Modeling the Effects of Harvest Alternatives on Mitigating Oak Decline in a Central Hardwood Forest Landscape.

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    Wen J Wang

    Full Text Available Oak decline is a process induced by complex interactions of predisposing factors, inciting factors, and contributing factors operating at tree, stand, and landscape scales. It has greatly altered species composition and stand structure in affected areas. Thinning, clearcutting, and group selection are widely adopted harvest alternatives for reducing forest vulnerability to oak decline by removing susceptible species and declining trees. However, the long-term, landscape-scale effects of these different harvest alternatives are not well studied because of the limited availability of experimental data. In this study, we applied a forest landscape model in combination with field studies to evaluate the effects of the three harvest alternatives on mitigating oak decline in a Central Hardwood Forest landscape. Results showed that the potential oak decline in high risk sites decreased strongly in the next five decades irrespective of harvest alternatives. This is because oak decline is a natural process and forest succession (e.g., high tree mortality resulting from intense competition would eventually lead to the decrease in oak decline in this area. However, forest harvesting did play a role in mitigating oak decline and the effectiveness varied among the three harvest alternatives. The group selection and clearcutting alternatives were most effective in mitigating oak decline in the short and medium terms, respectively. The long-term effects of the three harvest alternatives on mitigating oak decline became less discernible as the role of succession increased. The thinning alternative had the highest biomass retention over time, followed by the group selection and clearcutting alternatives. The group selection alternative that balanced treatment effects and retaining biomass was the most viable alternative for managing oak decline. Insights from this study may be useful in developing effective and informed forest harvesting plans for managing oak

  17. Effect of Body-Weight-Support Running on Lower-Limb Biomechanics.

    Science.gov (United States)

    Neal, Michael; Fleming, Neil; Eberman, Lindsey; Games, Kenneth; Vaughan, Jeremiah

    2016-09-01

    Study Design Controlled laboratory study. Background Body-weight-support (BWS) running is increasing in popularity, despite limited evidence of its effects on running mechanics. Objectives To determine the effect of increasing BWS on lower-limb biomechanics during lower-body positive-pressure (LBPP) treadmill running. Methods Fourteen male recreational runners completed 15 randomized trials on an LBPP treadmill at 5 levels of BWS and 3 velocities (1-minute trials with 3-minute recovery). Knee and ankle kinematic data were recorded continuously via electrogoniometry. Synchronous in-shoe plantar-pressure data identified stride onset and quantified foot-segment forces. Data were recorded during the final 30 seconds of each trial and averaged over 10 consecutive stride cycles. Results Higher levels of BWS resulted in significantly (Pdoi:10.2519/jospt.2016.6503. PMID:27581179

  18. The Effect of Lower Body Stabilization and Different Writing Tools on Writing Biomechanics in Children with Cerebral Palsy

    Science.gov (United States)

    Cheng, Hsin-Yi Kathy; Lien, Yueh-Ju; Yu, Yu-Chun; Ju, Yan-Ying; Pei, Yu-Cheng; Cheng, Chih-Hsiu; Wu, David Bin-Chia

    2013-01-01

    A high percentage of children with cerebral palsy (CP) have difficulty keeping up with the handwriting demands at school. Previous studies have addressed the effects of proper sitting and writing tool on writing performance, but less on body biomechanics. The aim of this study was to investigate the influence of lower body stabilization and pencil…

  19. THE EFFECT OF GENDER AND FATIGUE ON THE BIOMECHANICS OF BILATERAL LANDINGS FROM A JUMP: PEAK VALUES

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    Evangelos Pappas

    2007-03-01

    Full Text Available Female athletes are substantially more susceptible than males to suffer acute non-contact anterior cruciate ligament injury. A limited number of studies have identified possible biomechanical risk factors that differ between genders. The effect of fatigue on the biomechanics of landing has also been inadequately investigated. The objective of the study was to examine the effect of gender and fatigue on peak values of biomechanical variables during landing from a jump. Thirty-two recreational athletes performed bilateral drop jump landings from a 40 cm platform. Kinetic, kinematic and electromyographic data were collected before and after a functional fatigue protocol. Females landed with 9° greater peak knee valgus (p = 0.001 and 140% greater maximum vertical ground reaction forces (p = 0.003 normalized to body weight compared to males. Fatigue increased peak foot abduction by 1.7° (p = 0.042, peak rectus femoris activity by 27% (p = 0.018, and peak vertical ground reaction force (p = 0.038 by 20%. The results of the study suggest that landing with increased peak knee valgus and vertical ground reaction force may contribute to increased risk for knee injury in females. Fatigue caused significant but small changes on some biomechanical variables. Anterior cruciate ligament injury prevention programs should focus on implementing strategies to effectively teach females to control knee valgus and ground reaction force

  20. The effects of the arm swing on biomechanical and physiological aspects of roller ski skating.

    Science.gov (United States)

    Hegge, Ann Magdalen; Ettema, Gertjan; de Koning, Jos J; Rognstad, Asgeir Bakken; Hoset, Martin; Sandbakk, Øyvind

    2014-08-01

    This study analyzed the biomechanical and physiological effects of the arm swing in roller ski skating, and compared leg-skating (i.e. ski skating without poles) using a pronounced arm swing (SWING) with leg-skating using locked arms (LOCKED). Sixteen elite male cross-country skiers performed submaximal stages at 10, 15 and 20kmh(-1) on a 2% inclined treadmill in the two techniques. SWING demonstrated higher peak push-off forces and a higher force impulse at all speeds, but a longer cycle length only at the highest speed (all Pski skating increases the ski forces and aerobic energy cost at low and moderate speeds, whereas the greater forces at high speed lead to a longer cycle length and smaller anaerobic contribution.

  1. Immediate effects of an elastic knee sleeve on frontal plane gait biomechanics in knee osteoarthritis.

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    Raphael Schween

    Full Text Available Osteoarthritis of the knee affects millions of people. Elastic knee sleeves aim at relieving symptoms. While symptomatic improvements have been demonstrated as a consequence of elastic knee sleeves, evidence for biomechanical alterations only exists for the sagittal plane. We therefore asked what effect an elastic knee sleeve would have on frontal plane gait biomechanics.18 subjects (8 women, 10 men with osteoarthritis of the medial tibiofemoral joint walked over ground with and without an elastic knee sleeve. Kinematics and forces were recorded and joint moments were calculated using an inverse dynamics approach. Conditions with sleeve and without sleeve were compared with paired t-Tests.With the sleeve, knee adduction angle at ground contact was reduced by 1.9 ± 2.1° (P = 0.006. Peak knee adduction was reduced by 1.5 ± 1.6° (P = 0.004. The first peak knee adduction moment and positive knee adduction impulse were decreased by 10.1% (0.74 ± 0.9 Nm • kg-1; P = 0.002 and 12.9% (0.28 ± 0.3 Nm • s • kg-1; P < 0.004, respectively.Our study provides evidence that wearing an elastic knee sleeve during walking can reduce knee adduction angles, moments and impulse in subjects with knee osteoarthritis. As a higher knee adduction moment has previously been identified as a risk factor for disease progression in patients with medial knee osteoarthritis, we speculate that wearing a knee sleeve may be beneficial for this specific subgroup.

  2. Effect of the hydration on the biomechanical properties in a fibrin-agarose tissue-like model.

    Science.gov (United States)

    Scionti, Giuseppe; Moral, Monica; Toledano, Manuel; Osorio, Raquel; Durán, Juan D G; Alaminos, Miguel; Campos, Antonio; López-López, Modesto T

    2014-08-01

    The effect of hydration on the biomechanical properties of fibrin and fibrin-agarose (FA) tissue-like hydrogels is reported. Native hydrogels with approximately 99.5% of water content and hydrogels with water content reduced until 90% and 80% by means of plastic compression (nanostructuration) were generated. The biomechanical properties of the hydrogels were investigated by tensile, compressive, and shear tests. Experimental results indicate that nanostructuration enhances the biomechanical properties of the hydrogels. This improvement is due to the partial draining of the water that fills the porous network of fibers that the plastic compression generates, which produces a denser material, as confirmed by scanning electron microscopy. Results also indicate that the characteristic compressive and shear parameters increase with agarose concentration, very likely due to the high water holding capacity of agarose, which reduces the compressibility and gives consistency to the hydrogels. However, results of tensile tests indicate a weakening of the hydrogels as agarose concentration increases, which evidences the anisotropic nature of these biomaterials. Interestingly, we found that by adjusting the water and agarose contents it is possible to tune the biomechanical properties of FA hydrogels for a broad range, within which the properties of many native tissues fall. PMID:23963645

  3. The effect of intraosseous injection of calcium sulfate on microstructure and biomechanics of osteoporotic lumbar vertebrae in sheep

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    Da LIU

    2014-10-01

    Full Text Available Objective To investigate the effect of calcium sulfate (CS on improvement of microstructure and biomechanical performance of osteoporotic lumbar vertebrae in sheep. Methods Osteoporosis model was reproduced in 8 female sheep by bilateral ovariectomy and methylprednisolone administration. Then the lumbar vertebrae (L1-L4 in each sheep were randomly divided into CS group and blank group (2 vertebrae in each sheep. CS was injected into the vertebral bodies through the pedicle in CS group, and no treatment was given in blank group. All of the animals were sacrificed 3 months later, and vertebrae L1-L4 were harvested. The microstructure and biomechanical performance of vertebral bodies were assessed by micro-CT scanning, histological observation and biomechanical test. Results After ovariectomy and methylprednisolone administration, the mean bone mineral density of the lumbar vertebrae in the sheep was significantly decreased (>25% compared with that before induction (P<0.05, demonstrating a successful reproduction of osteoporosis model. Three months after injection, it was shown that CS was completely degraded without any remnant in the bone tissue. The quality of the bone tissue (trabecular number and tissue mineral density in CS group was significantly better than that in blank group (P<0.05, and the biomechanical performance in CS group was significantly superior to that in blank group (P<0.05. Conclusions  Local injection of CS could significantly improve the microstructure and biomechanical performance of osteoporotic vertebrae, and it may decrease the risk of fracture of patients with osteoporosis. DOI: 10.11855/j.issn.0577-7402.2014.09.02

  4. Radiation combined injury models to study the effects of interventions and wound biomechanics.

    Science.gov (United States)

    Zawaski, Janice A; Yates, Charles R; Miller, Duane D; Kaffes, Caterina C; Sabek, Omaima M; Afshar, Solmaz F; Young, Daniel A; Yang, Yunzhi; Gaber, M Waleed

    2014-12-01

    In the event of a nuclear detonation, a considerable number of projected casualties will suffer from combined radiation exposure and burn and/or wound injury. Countermeasure assessment in the setting of radiation exposure combined with dermal injury is hampered by a lack of animal models in which the effects of interventions have been characterized. To address this need, we used two separate models to characterize wound closure. The first was an open wound model in mice to study the effect of wound size in combination with whole-body 6 Gy irradiation on the rate of wound closure, animal weight and survival (morbidity). In this model the addition of interventions, wound closure, subcutaneous vehicle injection, topical antiseptic and topical antibiotics were studied to measure their effect on healing and survival. The second was a rat closed wound model to study the biomechanical properties of a healed wound at 10 days postirradiation (irradiated with 6 or 7.5 Gy). In addition, complete blood counts were performed and wound pathology by staining with hematoxylin and eosin, trichrome, CD68 and Ki67. In the mouse open wound model, we found that wound size and morbidity were positively correlated, while wound size and survival were negatively correlated. Regardless of the wound size, the addition of radiation exposure delayed the healing of the wound by approximately 5-6 days. The addition of interventions caused, at a minimum, a 30% increase in survival and improved mean survival by ∼9 days. In the rat closed wound model we found that radiation exposure significantly decreased all wound biomechanical measurements as well as white blood cell, platelet and red blood cell counts at 10 days post wounding. Also, pathological changes showed a loss of dermal structure, thickening of dermis, loss of collagen/epithelial hyperplasia and an increased density of macrophages. In conclusion, we have characterized the effect of a changing wound size in combination with radiation

  5. Maintaining Organizational Effectiveness during Periods of Financial Decline.

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    Askew, Jerry W.; Anderson, Beverly D.

    1989-01-01

    Notes that retrenchment has become part of institutional life for many college and university administrators. Highlights excerpts from relevant literature and presents series of recommendations for use by college and university administrators in mitigating negative effects of budget retrenchment. Concludes that thoughtful preparation for impending…

  6. Effect of prosthetic gel liner thickness on gait biomechanics and pressure distribution within the transtibial socket

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    Erin Boutwell, MS

    2012-04-01

    Full Text Available Prosthetic gel liners are often prescribed for persons with lower-limb amputations to make the prosthetic socket more comfortable. However, their effects on residual limb pressures and gait characteristics have not been thoroughly explored. This study investigated the effects of gel liner thickness on peak socket pressures and gait patterns of persons with unilateral transtibial amputations. Pressure and quantitative gait data were acquired while subjects walked on liners of two different uniform thicknesses. Fibular head peak pressures were reduced (p = 0.04 with the thicker liner by an average of 26 +/– 21%, while the vertical ground reaction force (GRF loading peak increased 3 +/– 3% (p = 0.02. Most subjects perceived increased comfort within the prosthetic socket with the thicker liner, which may be associated with the reduced fibular head peak pressures. Additionally, while the thicker liner presumably increased comfort by providing a more compliant limb-socket interface, the higher compliance may have reduced force and vibration feedback to the residual limb and contributed to the larger vertical GRF loading peaks. We conclude that determining optimal gel liner thickness for a particular individual will require further investigations to better identify and understand the compromises that occur between user perception, residual-limb pressure distribution, and gait biomechanics.

  7. Effect of prosthetic gel liner thickness on gait biomechanics and pressure distribution within the transtibial socket.

    Science.gov (United States)

    Boutwell, Erin; Stine, Rebecca; Hansen, Andrew; Tucker, Kerice; Gard, Steven

    2012-01-01

    Prosthetic gel liners are often prescribed for persons with lower-limb amputations to make the prosthetic socket more comfortable. However, their effects on residual limb pressures and gait characteristics have not been thoroughly explored. This study investigated the effects of gel liner thickness on peak socket pressures and gait patterns of persons with unilateral transtibial amputations. Pressure and quantitative gait data were acquired while subjects walked on liners of two different uniform thicknesses. Fibular head peak pressures were reduced (p = 0.04) with the thicker liner by an average of 26 +/- 21%, while the vertical ground reaction force (GRF) loading peak increased 3 +/- 3% (p = 0.02). Most subjects perceived increased comfort within the prosthetic socket with the thicker liner, which may be associated with the reduced fibular head peak pressures. Additionally, while the thicker liner presumably increased comfort by providing a more compliant limb-socket interface, the higher compliance may have reduced force and vibration feedback to the residual limb and contributed to the larger vertical GRF loading peaks. We conclude that determining optimal gel liner thickness for a particular individual will require further investigations to better identify and understand the compromises that occur between user perception, residual-limb pressure distribution, and gait biomechanics.

  8. Dietary xylitol in the prevention of experimental osteoporosis:beneficial effects on bone resorption, structure and biomechanics

    OpenAIRE

    Mattila, P.

    1999-01-01

    Abstract Dietary xylitol supplementation increases bone calcium and phosphorus concentrations in healthy rats, as well as protects against the decrease of bone minerals and bone density during experimental osteoporosis. This suggests that dietary xylitol might have a favorable effect on the prevention of osteoporosis. However, before any conclusions can be drawn about the usefulness of a compound, studies including structural evaluation and biomechanical testing of ...

  9. The effect of gender and fatigue on the biomechanics of bilateral landings from a jump: peak values.

    Science.gov (United States)

    Pappas, Evangelos; Sheikhzadeh, Ali; Hagins, Marshall; Nordin, Margareta

    2007-01-01

    Female athletes are substantially more susceptible than males to suffer acute non-contact anterior cruciate ligament injury. A limited number of studies have identified possible biomechanical risk factors that differ between genders. The effect of fatigue on the biomechanics of landing has also been inadequately investigated. The objective of the study was to examine the effect of gender and fatigue on peak values of biomechanical variables during landing from a jump. Thirty-two recreational athletes performed bilateral drop jump landings from a 40 cm platform. Kinetic, kinematic and electromyographic data were collected before and after a functional fatigue protocol. Females landed with 9° greater peak knee valgus (p = 0.001) and 140% greater maximum vertical ground reaction forces (p = 0.003) normalized to body weight compared to males. Fatigue increased peak foot abduction by 1.7° (p = 0.042), peak rectus femoris activity by 27% (p = 0.018), and peak vertical ground reaction force (p = 0.038) by 20%. The results of the study suggest that landing with increased peak knee valgus and vertical ground reaction force may contribute to increased risk for knee injury in females. Fatigue caused significant but small changes on some biomechanical variables. Anterior cruciate ligament injury prevention programs should focus on implementing strategies to effectively teach females to control knee valgus and ground reaction force. Key pointsFemale athletes landed with increased knee valgus and VGRF which may predispose them to ACL injury.Fatigue elicited a similar response in male and female athletes.The effectiveness of sports injury prevention programs may improve by focusing on teaching females to land softer and with less knee valgus. PMID:24149228

  10. Short-Term Effects of Overnight Orthokeratology on Corneal Epithelial Permeability and Biomechanical Properties

    Science.gov (United States)

    Yeh, Thao N.; Green, Harry M.; Zhou, Yixiu; Pitts, Julie; Kitamata-Wong, Britney; Lee, Sophia; Wang, Shiyin L.; Lin, Meng C.

    2013-01-01

    Purpose. To investigate the effects of 30 nights of overnight orthokeratology (OOK) on corneal epithelial permeability (Pdc) and corneal biomechanical properties. Methods. BE Retainer and Paragon CRT lenses were used. Visits were scheduled approximately 4 hours after awakening at baseline and after 1, 5, 10, 14, and 30 days of treatment. Pdc was measured at baseline and at day 30, whereas corneal biomechanical properties and visual acuities (VAs) were measured at all visits. Results. Thirty-nine neophytes and soft contact lens wearers completed the study. There was no difference in Pdc between baseline (ln[Pdc] [95% confidence interval (CI)] = −2.65 [−2.80 to −2.50]) and day 30 (ln[Pdc][CI] = −2.68 [−2.85 to −2.50]) (P = 0.88). Corneal hysteresis (CH) and corneal resistance factor (CRF) reduced significantly from baseline (CH [CI] = 10.89 [10.59–11.19] mm Hg and CRF [CI] = 10.35 [9.99–10.72] mm Hg) to day 30 (CH [CI] = 10.59 [10.31–10.87] mm Hg and CRF [CI] = 9.58 [9.26–9.89] mm Hg) (P = 0.001 for CH and P < 0.001 for CRF). Posttreatment VA did not reach baseline targets, and the difference was worse with low-contrast letters. Asian individuals (n = 18) had significantly worse VA than non-Asian individuals (n = 21) under most conditions through day 5, and the difference extended through day 14 with low-contrast letters under mesopic conditions. The percentage of participants who achieved 20/20 uncorrected was 17% Asian and 40% non-Asian individuals after day 1 and reached 69% Asian and 83% non-Asian individuals at day 30. Conclusions. Thirty nights of OOK did not alter Pdc when measured 4 hours after awakening. OOK caused CH and CRF to decrease, but the changes were not clinically significant compared with diseased and postsurgical cases. Asian individuals, who had lower baseline CH in this study, responded slower to OOK based on early uncorrected VA and overrefraction measurements. PMID:23652492

  11. The Effect of Phospholipids (Surfactant on Adhesion and Biomechanical Properties of Tendon: A Rat Achilles Tendon Repair Model

    Directory of Open Access Journals (Sweden)

    T. Kursat Dabak

    2015-01-01

    Full Text Available Adhesion of the tendon is a major challenge for the orthopedic surgeon during tendon repair. Manipulation of biological environment is one of the concepts to prevent adhesion. Lots of biochemicals have been studied for this purpose. We aimed to determine the effect of phospholipids on adhesion and biomechanical properties of tendon in an animal tendon repair model. Seventy-two Wistar rats were divided into 4 groups. Achilles tendons of rats were cut and repaired. Phospholipids were applied at two different dosages. Tendon adhesion was determined histopathologically and biomechanical test was performed. At macroscopic evaluation of adhesion, there are statistically significant differences between multiple-dose phospholipid injection group and Control group and also hyaluronic acid group and Control group (p0.008. Ultimate strength was highest at hyaluronic acid injection group and lowest at multiple-dose phospholipid injection group. Single-dose phospholipids (surfactant application may have a beneficial effect on the tendon adhesion. Although multiple applications of phospholipids seem the most effective regime to reduce the tendon adhesion among groups, it deteriorated the biomechanical properties of tendon.

  12. The Effect of an Open Carpal Tunnel Release on Thumb CMC Biomechanics

    Directory of Open Access Journals (Sweden)

    Marc A. Tanner

    2012-01-01

    Full Text Available Purpose. We have observed worsening thumb pain following carpal tunnel release (CTR in some patients. Our purpose was to determine the effect of open CTR on thumb carpometacarpal (CMC biomechanics. Methods. Five fresh-frozen cadaver arms with intact soft tissues were used. Each specimen was secured to a jig which fixed the forearm at 45° supination, and the wrist at 20° dorsiflexion, with thumb pointing up. The thumb was axially loaded with a force of 130 N. We measured 3D translation and rotation of the trapezium, radius, and first metacarpal, before and after open CTR. Motion between radius and first metacarpal, radius and trapezium, and first metacarpal and trapezium during loading was calculated using rigid body mechanics. Overall stiffness of each specimen was determined. Results. Total construct stiffness following CTR was reduced in all specimens but not significantly. No significant changes were found in adduction, pronation, or dorsiflexion of the trapezium with respect to radius after open CTR. Motion between radius and first metacarpal, between radius and trapezium, or between first metacarpal and trapezium after open CTR was not decreased significantly. Conclusion. From this data, we cannot determine if releasing the transverse carpal ligament alters kinematics of the CMC joint.

  13. Effect of gait retraining for reducing ambulatory knee load on trunk biomechanics and trunk muscle activity.

    Science.gov (United States)

    Nüesch, Corina; Laffer, Dominik; Netzer, Cordula; Pagenstert, Geert; Mündermann, Annegret

    2016-06-01

    The purpose of this study was to test the hypothesis that walking with increased medio-lateral trunk sway is associated with lower external knee adduction moment and lower extremity muscle activation, and higher external ipsilateral trunk moment and trunk muscle activity than walking with normal trunk sway in healthy participants. Fifteen participants performed walking trials with normal and increased medio-lateral trunk sway. Maximum trunk sway, first maximum knee adduction moment, lateral trunk bending moment, and bilateral vastus medialis, vastus lateralis, gluteus medius, rectus abdominis, external oblique and erector spinae muscle activity were computed. Walking with increased trunk sway was associated with lower maximum knee adduction moment (95% confidence interval (CI): 0.50-0.62Nm/kg vs. 0.62-0.76Nm/kg; P<.001) and ipsilateral gluteus medius (-17%; P=.014) and erector spinae muscle activity (-24%; P=.004) and greater maximum lateral trunk bending moment (+34%; P<.001) and contralateral external oblique muscle activity (+60%; P=.009). In all participants, maximum knee adduction moment was negatively correlated and maximum trunk moment was positively correlated with maximum trunk sway. The results of this study suggest that walking with increased trunk sway not only reduces the external knee adduction moment but also alters and possibly increases the load on the trunk. Hence, load-altering biomechanical interventions should always be evaluated not only regarding their effects on the index joint but on other load-bearing joints such as the spine. PMID:27264398

  14. The potential effects of meditation on age-related cognitive decline: a systematic review.

    Science.gov (United States)

    Gard, Tim; Hölzel, Britta K; Lazar, Sara W

    2014-01-01

    With a rapidly aging society it becomes increasingly important to counter normal age-related decline in cognitive functioning. Growing evidence suggests that cognitive training programs may have the potential to counteract this decline. On the basis of a growing body of research that shows that meditation has positive effects on cognition in younger and middle-aged adults, meditation may be able to offset normal age-related cognitive decline or even enhance cognitive function in older adults. In this paper, we review studies investigating the effects of meditation on age-related cognitive decline. We searched the Web of Science (1900 to present), PsycINFO (1597 to present), MEDLINE (1950 to present), and CABI (1910 to present) to identify original studies investigating the effects of meditation on cognition and cognitive decline in the context of aging. Twelve studies were included in the review, six of which were randomized controlled trials. Studies involved a wide variety of meditation techniques and reported preliminary positive effects on attention, memory, executive function, processing speed, and general cognition. However, most studies had a high risk of bias and small sample sizes. Reported dropout rates were low and compliance rates high. We conclude that meditation interventions for older adults are feasible, and preliminary evidence suggests that meditation can offset age-related cognitive decline.

  15. Gait biomechanics of individuals with transtibial amputation: effect of suspension system.

    Directory of Open Access Journals (Sweden)

    Arezoo Eshraghi

    Full Text Available Prosthetic suspension system is an important component of lower limb prostheses. Suspension efficiency can be best evaluated during one of the vital activities of daily living, i.e. walking. A new magnetic prosthetic suspension system has been developed, but its effects on gait biomechanics have not been studied. This study aimed to explore the effect of suspension type on kinetic and kinematic gait parameters during level walking with the new suspension system as well as two other commonly used systems (the Seal-In and pin/lock. Thirteen persons with transtibial amputation participated in this study. A Vicon motion system (six cameras, two force platforms was utilized to obtain gait kinetic and kinematic variables, as well as pistoning within the prosthetic socket. The gait deviation index was also calculated based on the kinematic data. The findings indicated significant difference in the pistoning values among the three suspension systems. The Seal-In system resulted in the least pistoning compared with the other two systems. Several kinetic and kinematic variables were also affected by the suspension type. The ground reaction force data showed that lower load was applied to the limb joints with the magnetic suspension system compared with the pin/lock suspension. The gait deviation index showed significant deviation from the normal with all the systems, but the systems did not differ significantly. Main significant effects of the suspension type were seen in the GRF (vertical and fore-aft, knee and ankle angles. The new magnetic suspension system showed comparable effects in the remaining kinetic and kinematic gait parameters to the other studied systems. This study may have implications on the selection of suspension systems for transtibial prostheses. Trial registration: Iranian Registry of Clinical Trials IRCT2013061813706N1.

  16. Radiographic, densitometric, and biomechanical effects of recombinant canine somatotropin in an unstable ostectomy gap model of bone healing in dogs

    International Nuclear Information System (INIS)

    Objective: To determine the effect of recombinant canine somatotropin (STH) on radiographic, densitometric, and biomechanical aspects of bone healing using an unstable ostectomy gap model. Study Design: After an ostectomy of the midshaft radius, bone healing was evaluated over an 8-week period in control dogs (n = 4) and dogs receiving recombinant canine STH (n = 4). Animals Or Sample Population: Eight sexually intact female Beagle dogs, 4 to 5 years old. Methods: Bone healing was evaluated by qualitative and quantitative evaluation of serial radiographs every 2 weeks. Terminal dual-energy x-ray absorptiometry and three-point bending biomechanical testing were also performed. Results: Dogs receiving STH had more advanced radiographic healing of ostectomy sites. Bone area, bone mineral content, and bone density were two to five times greater at the ostectomy sites of treated dogs. Ultimate load at failure and stiffness were three and five times greater in dogs receiving STH. Conclusions: Using the ostectomy gap model, recombinant canine STH enhanced the radiographic, densitometric, and biomechanical aspects of bone healing in dogs. Clinical Relevance: Dogs at risk for delayed healing of fractures may benefit from treatment with recombinant canine STH

  17. The Protective Effect of Kevlar ® Socks Against Hockey Skate Blade Injuries: A Biomechanical Study

    Science.gov (United States)

    Nauth, Aaron; Aziz, Mina; Tsuji, Matthew; Whelan, Daniel B.; Theodoropoulos, John S.; Zdero, Rad

    2014-01-01

    Objectives: Several recent high profile injuries to elite players in the National Hockey League (NHL) secondary to skate blade lacerations have generated significant interest in these injuries and possible methods to protect against them. These injuries are typically due to direct contact of the skate blade of another player with posterior aspect of the calf resulting in a range of potential injuries to tendons or neurovascular structures. The Achilles tendon is most commonly involved. Kevlar® reinforced socks have recently become available for hockey players to wear and are cited as providing possible protection against such injuries. However, there has been no investigation of the possible protective effects of Kevlar® reinforced socks against skate blade injuries, and it is currently unknown what protective effects, if any, that these socks provide against these injuries. The proposed study sought to address this by conducting a biomechanical investigation of the protective effects of Kevlar® reinforced socks against Achilles tendon injuries in a simulated model of skate blade injury using human cadaver limbs. This novel investigation is the first to address the possible benefits to hockey players of wearing Kevlar® reinforced socks. Methods: Seven matched pairs of human cadaver lower limbs were fitted with a Kevlar ® reinforced sock comprised of 60% Kevlar®/20% Coolmax® polyester/18 % Nylon/12% Spandex (Bauer Elite Performance Skate Sock) on one limb and a standard synthetic sock comprised of 51% polyester/47% nylon/2% spandex (Bauer Premium Performance Skate Sock) on the contralateral limb as a control. Each limb was then mounted on a Materials Testing System (MTS) with the ankle dorsiflexed to 90° and the knee held in full extension using a custom designed jig. Specimens were then impacted with a hockey skate blade directed at the posterior calf, 12 cm above the heel, at an angle of 45° and a speed of 31m/s, to a penetration depth of 4.3 cm, to

  18. Effect of estrogen on tendon collagen synthesis, tendon structural characteristics, and biomechanical properties in postmenopausal women

    DEFF Research Database (Denmark)

    Hansen, M.; Kongsgaard, M; Holm, Lars;

    2009-01-01

    and fibril characteristics were determined by MRI and transmission electron microscopy, whereas tendon biomechanical properties were measured during isometric maximal voluntary contraction by ultrasound recording. Tendon FSR was markedly higher in ERT users (P ... density, fibril volume fraction, and fibril mean area did not differ between groups. However, the percentage of medium-sized fibrils was higher in ERT users (P

  19. Effects of Bone Young’s Modulus on Finite Element Analysis in the Lateral Ankle Biomechanics

    Directory of Open Access Journals (Sweden)

    W. X. Niu

    2013-01-01

    Full Text Available Finite element analysis (FEA is a powerful tool in biomechanics. The mechanical properties of biological tissue used in FEA modeling are mainly from experimental data, which vary greatly and are sometimes uncertain. The purpose of this study was to research how Young’s modulus affects the computations of a foot-ankle FEA model. A computer simulation and an in-vitro experiment were carried out to investigate the effects of incremental Young’s modulus of bone on the stress and strain outcomes in the computational simulation. A precise 3-dimensional finite element model was constructed based on an in-vitro specimen of human foot and ankle. Young’s moduli were assigned as four levels of 7.3, 14.6, 21.9 and 29.2 GPa respectively. The proximal tibia and fibula were completely limited to six degrees of freedom, and the ankle was loaded to inversion 10° and 20° through the calcaneus. Six cadaveric foot-ankle specimens were loaded as same as the finite element model, and strain was measured at two positions of the distal fibula. The bone stress was less affected by assignment of Young’s modulus. With increasing of Young’s modulus, the bone strain decreased linearly. Young’s modulus of 29.2 GPa was advisable to get the satisfactory surface strain results. In the future study, more ideal model should be constructed to represent the nonlinearity, anisotropy and inhomogeneity, as the same time to provide reasonable outputs of the interested parameters.

  20. The biomechanics of point contact-dynamic compression plate and its effects on bone perfusion

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yu-feng; LI Qi-hong; GU Zu-chao; WANG Ai-min

    2006-01-01

    Objective: To compare the mechanical properties of point contact-dynamic compression plate (PC-DCP) and its effects on cortical bone perfusion with that of dynamic compression plates (DCP) in goat tibiae.Methods: Twenty pairs of matched fresh goat tibiae were used. A transverse fracture model was established.The fractures with a 3mm interspace between the fracture ends were subject to fixations with the DCPs and the PCDCPs respectively, then the four-points bending tests and the torsion tests were conducted to compare the mechanical properties of the PC-DCP with that of DCP. Another 13sexually mature goats underwent fixations with the DCPs and the PC-DCPs, respectively, at the mid-shafts of the intact bilateral tibiae. Ischemic zones were observed at four time points (1 day, 2, 6, and 12 weeks after operation)using disulphine blue staining technique.Results: There were no significant differences in mechanical properties, such as bend- and torsionresistance, between the DCPs and the PC-DCPs. One day,2, and 6 weeks after operation, on the side of DCP fixation, outer cortical bone iscbemia under the plate persisted, and this condition did not reverse until 12 weeks after operation. However, on the side of PC-DCP fixation,cortical bone ischemia occurred only in the periphery of the screw holes and at the contact sites of the PC NUTs 1 day after operation, and it disappeared at 2 weeks after operation.Conclusions: The PC-DCP has similar biomechanical properties of the DCP, but is less detrimental to local bone blood circulation than the conventional plates.

  1. DLS 5.0--the biomechanical effects of dynamic locking screws.

    Directory of Open Access Journals (Sweden)

    Stefan Döbele

    Full Text Available INTRODUCTION: Indirect reduction of dia-/metaphyseal fractures with minimally invasive implant application bridges the fracture zone in order to protect the soft-tissue and blood supply. The goal of this fixation strategy is to allow stable motion at the fracture site to achieve indirect bone healing with callus formation. However, concerns have arisen that the high axial stiffness and eccentric position of locked plating constructs may suppress interfragmentary motion and callus formation, particularly under the plate. The reason for this is an asymmetric fracture movement. The biological need for sufficient callus formation and secondary bone healing is three-dimensional micro movement in the fracture zone. The DLS was designed to allow for increased fracture site motion. The purpose of the current study was to determine the biomechanical effect of the DLS_5.0. METHODS: Twelve surrogate bone models were used for analyzing the characteristics of the DLS_5.0. The axial stiffness and the interfragmentary motion of locked plating constructs with DLS were compared to conventional constructs with Locking Head Screws (LS_5.0. A quasi-static axial load of 0 to 2.5 kN was applied. Relative motion was measured. RESULTS: The dynamic system showed a biphasic axial stiffness distribution and provided a significant reduction of the initial axial stiffness of 74.4%. Additionally, the interfragmentary motion at the near cortex increased significantly from 0.033 mm to 0.210 mm (at 200N. CONCLUSIONS: The DLS may ultimately be an improvement over the angular stable plate osteosynthesis. The advantages of the angular stability are not only preserved but even supplemented by a dynamic element which leads to homogenous fracture movement and to a potentially uniform callus distribution.

  2. Systems biomechanics of the cell

    CERN Document Server

    Maly, Ivan V

    2013-01-01

    Systems Biomechanics of the Cell attempts to outline systems biomechanics of the cell as an emergent and promising discipline. The new field owes conceptually to cell mechanics, organism-level systems biomechanics, and biology of biochemical systems. Its distinct methodology is to elucidate the structure and behavior of the cell by analyzing the unintuitive collective effects of elementary physical forces that interact within the heritable cellular framework. The problematics amenable to this approach includes the variety of cellular activities that involve the form and movement of the cell body and boundary (nucleus, centrosome, microtubules, cortex, and membrane). Among the elementary system effects in the biomechanics of the cell, instability of symmetry, emergent irreversibility, and multiperiodic dissipative motion can be noted. Research results from recent journal articles are placed in this unifying framework. It is suggested that the emergent discipline has the potential to expand the spectrum of ques...

  3. Combined effect of lung function level and decline increases morbidity and mortality risks

    DEFF Research Database (Denmark)

    Baughman, Penelope; Marott, Jacob Louis; Lange, Peter;

    2012-01-01

    Abstract Lung function level and decline are each pre- dictive of morbidity and mortality. Evaluation of the combined effect of these measurements may help further identify high-risk groups. Using Copenhagen City Heart Study longitudinal spirometry data (n = 10,457), 16–21 year risks of chronic...... obstructive pulmonary disease (COPD) morbidity, COPD or coronary heart disease mor- tality, and all-cause mortality were estimated from com- bined effects of level and decline in forced expiratory volume in one second (FEV1). Risks were evaluated using Cox proportional hazards models for individuals grouped...... by combinations of baseline predicted FEV1 and quartiles of slope. Hazard ratios (HR) and 95 % con¿dence intervals (CI) were estimated using strati¿ed analysis by gender, smoking status, and baseline age (B45 and [45). For COPD morbidity, quartiles of increasing FEV1 decline increased HRs (95 % CI...

  4. Trapped in the extinction vortex? Strong genetic effects in a declining vertebrate population

    Directory of Open Access Journals (Sweden)

    Larsson Mikael

    2010-02-01

    Full Text Available Abstract Background Inbreeding and loss of genetic diversity are expected to increase the extinction risk of small populations, but detailed tests in natural populations are scarce. We combine long-term population and fitness data with those from two types of molecular markers to examine the role of genetic effects in a declining metapopulation of southern dunlins Calidris alpina schinzii, an endangered shorebird. Results The decline is associated with increased pairings between related individuals, including close inbreeding (as revealed by both field observations of parentage and molecular markers. Furthermore, reduced genetic diversity seems to affect individual fitness at several life stages. Higher genetic similarity between mates correlates negatively with the pair's hatching success. Moreover, offspring produced by related parents are more homozygous and suffer from increased mortality during embryonic development and possibly also after hatching. Conclusions Our results demonstrate strong genetic effects in a rapidly declining population, emphasizing the importance of genetic factors for the persistence of small populations.

  5. Projected effects of declining anthropogenic aerosols on the southern annular mode

    International Nuclear Information System (INIS)

    Declining emissions of anthropogenic aerosols have been shown to contribute to global warming in climate projections from the Coupled Model Intercomparison Project Phase 5 (CMIP5). This study considers the response of the southern annular mode (SAM) in austral summer to declining aerosols in simulations forced by Representative Concentration Pathway 4.5 (RCP4.5) using CSIRO-Mk3.6, a CMIP5-generation model. A ten-member ensemble forced by RCP4.5 for the period 2006–2100 is compared with another experiment, which is identical except that emissions of anthropogenic aerosols are held fixed at their 2005 values. With fixed aerosol emissions, the model simulates a negative (but statistically insignificant) ensemble-mean SAM trend in austral summer, suggesting that the effects of recovering stratospheric ozone slightly outweigh the effects of increasing long-lived greenhouse gases (GHGs). In contrast, the standard RCP4.5 experiment (including additional warming due to declining aerosols) simulates a positive ensemble-mean SAM trend, and the difference between the two trends is significant at 5%. The response of Southern Hemisphere zonal-mean atmospheric circulation and temperature to declining aerosols resembles the response to increasing GHGs; this suggests that the positive SAM trend due to declining aerosols may be driven by mechanisms that are similar to those that cause the positive SAM trend in response to increasing GHGs. (letter)

  6. A comparison of the biomechanical effects of valgus knee braces and lateral wedged insoles in patients with knee osteoarthritis.

    Science.gov (United States)

    Jones, Richard K; Nester, Christopher J; Richards, Jim D; Kim, Winston Y; Johnson, David S; Jari, Sanjiv; Laxton, Philip; Tyson, Sarah F

    2013-03-01

    Increases in the external knee adduction moment (EKAM) have been associated with increased mechanical load at the knee and progression of knee osteoarthritis. Valgus knee braces and lateral wedged insoles are common approaches to reducing this loading; however no study has directly compared the biomechanical and clinical effects of these two treatments in patients with medial tibiofemoral osteoarthritis. A cross-over randomised design was used where each intervention was worn by 28 patients for a two week period. Pre- and post-intervention gait kinematic/kinetic data and clinical outcomes were collected to evaluate the biomechanical and clinical effects on the knee joint. The valgus knee brace and the lateral wedged insole significantly increased walking speed, reduced the early stance EKAM by 7% and 12%, and the knee adduction angular impulse by 8.6 and 16.1% respectively. The lateral wedged insole significantly reduced the early stance EKAM compared to the valgus knee brace (p=0.001). The valgus knee brace significantly reduced the knee varus angle compared to the baseline and lateral wedged insole. Improvements in pain and function subscales were comparable for the valgus knee brace and lateral wedged insole. There were no significant differences between the two treatments in any of the clinical outcomes; however the lateral wedged insoles demonstrated greater levels of acceptance by patients. This is the first study to biomechanically compare these two treatments, and demonstrates that given the potential role of knee loading in osteoarthritis progression, that both treatments reduce this but lateral wedge insoles appear to have a greater effect.

  7. A comparison of the biomechanical effects of valgus knee braces and lateral wedged insoles in patients with knee osteoarthritis.

    Science.gov (United States)

    Jones, Richard K; Nester, Christopher J; Richards, Jim D; Kim, Winston Y; Johnson, David S; Jari, Sanjiv; Laxton, Philip; Tyson, Sarah F

    2013-03-01

    Increases in the external knee adduction moment (EKAM) have been associated with increased mechanical load at the knee and progression of knee osteoarthritis. Valgus knee braces and lateral wedged insoles are common approaches to reducing this loading; however no study has directly compared the biomechanical and clinical effects of these two treatments in patients with medial tibiofemoral osteoarthritis. A cross-over randomised design was used where each intervention was worn by 28 patients for a two week period. Pre- and post-intervention gait kinematic/kinetic data and clinical outcomes were collected to evaluate the biomechanical and clinical effects on the knee joint. The valgus knee brace and the lateral wedged insole significantly increased walking speed, reduced the early stance EKAM by 7% and 12%, and the knee adduction angular impulse by 8.6 and 16.1% respectively. The lateral wedged insole significantly reduced the early stance EKAM compared to the valgus knee brace (p=0.001). The valgus knee brace significantly reduced the knee varus angle compared to the baseline and lateral wedged insole. Improvements in pain and function subscales were comparable for the valgus knee brace and lateral wedged insole. There were no significant differences between the two treatments in any of the clinical outcomes; however the lateral wedged insoles demonstrated greater levels of acceptance by patients. This is the first study to biomechanically compare these two treatments, and demonstrates that given the potential role of knee loading in osteoarthritis progression, that both treatments reduce this but lateral wedge insoles appear to have a greater effect. PMID:22920242

  8. A review of biomechanics of the shoulder and biomechanical concepts of rotator cuff repair

    Directory of Open Access Journals (Sweden)

    Nobuyuki Yamamoto

    2015-01-01

    Full Text Available In this article, we describe the basic knowledge about shoulder biomechanics, which is thought to be useful for surgeons. Some clinical reports have described that the excellent outcome after cuff repair without acromioplasty and a limited acromioplasty might be enough for subacromial decompression. It was biomechanically demonstrated that a 10-mm medial shift of the tendon repair site has a minimum effect on biomechanics. Many biomechanical studies reported that the transosseous equivalent repair was superior to other techniques, although the tendon may lose its inherent elasticity. We herein introduce our recent experiment data and latest information on biomechanics.

  9. Linking global warming to amphibian declines through its effects on female body condition and survivorship.

    Science.gov (United States)

    Reading, C J

    2007-02-01

    There is general consensus that climate change has contributed to the observed decline, and extinction, of many amphibian species throughout the world. However, the mechanisms of its effects remain unclear. A laboratory study in 1980-1981 in which temperate zone amphibians that were prevented from hibernating had decreased growth rates, matured at a smaller size and had increased mortality compared with those that hibernated suggested one possible mechanism. I used data from a field study of common toads (Bufo bufo) in the UK, between 1983 and 2005, to determine whether this also occurs in the field. The results demonstrated two pathways by which global warming may cause amphibian declines. First, there was a clear relationship between a decline in the body condition of female common toads and the occurrence of warmer than average years since 1983. This was paralleled by a decline in their annual survival rates with the relationship between these two declines being highly correlated. Second, there was a significant relationship between the occurrence of mild winters and a reduction in female body size, resulting in fewer eggs being laid annually. Climate warming can, therefore, act on wild temperate zone amphibians by deleteriously affecting their physiology, during and after hibernation, causing increased female mortality rates and decreased fecundity in survivors.

  10. Linking global warming to amphibian declines through its effects on female body condition and survivorship.

    Science.gov (United States)

    Reading, C J

    2007-02-01

    There is general consensus that climate change has contributed to the observed decline, and extinction, of many amphibian species throughout the world. However, the mechanisms of its effects remain unclear. A laboratory study in 1980-1981 in which temperate zone amphibians that were prevented from hibernating had decreased growth rates, matured at a smaller size and had increased mortality compared with those that hibernated suggested one possible mechanism. I used data from a field study of common toads (Bufo bufo) in the UK, between 1983 and 2005, to determine whether this also occurs in the field. The results demonstrated two pathways by which global warming may cause amphibian declines. First, there was a clear relationship between a decline in the body condition of female common toads and the occurrence of warmer than average years since 1983. This was paralleled by a decline in their annual survival rates with the relationship between these two declines being highly correlated. Second, there was a significant relationship between the occurrence of mild winters and a reduction in female body size, resulting in fewer eggs being laid annually. Climate warming can, therefore, act on wild temperate zone amphibians by deleteriously affecting their physiology, during and after hibernation, causing increased female mortality rates and decreased fecundity in survivors. PMID:17024381

  11. Effects of Mechanical Properties and Atherosclerotic Artery Size on Biomechanical Plaque Disruption - Mouse versus Human

    OpenAIRE

    Riou, Laurent M.; Broisat, Alexis; Ghezzi, Catherine; Finet, Gérard; Rioufol, Gilles; Gharib, Ahmed M.; Pettigrew, Roderic I.; Ohayon, Jacques

    2014-01-01

    Mouse models of atherosclerosis are extensively being used to study the mechanisms of atherosclerotic plaque development and the results are frequently extrapolated to humans. However, major differences have been described between murine and human atherosclerotic lesions and the determination of similarities and differences between these species has been largely addressed recently. This study takes over and extends previous studies performed by our group and related to the biomechanical chara...

  12. Declining efficacy in controlled trials of antidepressants: effects of placebo dropout

    NARCIS (Netherlands)

    Schalkwijk, S.J.; Undurraga, J.; Tondo, L.; Baldessarini, R.J.

    2014-01-01

    Drug-placebo differences (effect-sizes) in controlled trials of antidepressants for major depressive episodes have declined for several decades, in association with selectively increasing clinical improvement associated with placebo-treatment. As these trends require adequate explanation, we tested

  13. Quantitative evidence for the effects of multiple drivers on continental-scale amphibian declines

    Science.gov (United States)

    Grant, Evan H. Campbell; Miller, David A. W.; Schmidt, Benedikt R.; Adams, Michael J.; Amburgey, Staci M.; Chambert, Thierry A; Cruickshank, Sam S.; Fisher, Robert N.; Green, David M.; Hossack, Blake R.; Johnson, Pieter T.J.; Joseph, Maxwell B.; Rittenhouse, Tracy A. G.; Ryan, Maureen E.; Waddle, J. Hardin; Walls, Susan C.; Bailey, Larissa L.; Fellers, Gary M.; Gorman, Thomas A.; Ray, Andrew M.; Pilliod, David S.; Price, Steven J.; Saenz, Daniel; Sadinski, Walt; Muths, Erin L.

    2016-01-01

    Since amphibian declines were first proposed as a global phenomenon over a quarter century ago, the conservation community has made little progress in halting or reversing these trends. The early search for a “smoking gun” was replaced with the expectation that declines are caused by multiple drivers. While field observations and experiments have identified factors leading to increased local extinction risk, evidence for effects of these drivers is lacking at large spatial scales. Here, we use observations of 389 time-series of 83 species and complexes from 61 study areas across North America to test the effects of 4 of the major hypothesized drivers of declines. While we find that local amphibian populations are being lost from metapopulations at an average rate of 3.79% per year, these declines are not related to any particular threat at the continental scale; likewise the effect of each stressor is variable at regional scales. This result - that exposure to threats varies spatially, and populations vary in their response - provides little generality in the development of conservation strategies. Greater emphasis on local solutions to this globally shared phenomenon is needed.

  14. Quantitative evidence for the effects of multiple drivers on continental-scale amphibian declines.

    Science.gov (United States)

    Grant, Evan H Campbell; Miller, David A W; Schmidt, Benedikt R; Adams, Michael J; Amburgey, Staci M; Chambert, Thierry; Cruickshank, Sam S; Fisher, Robert N; Green, David M; Hossack, Blake R; Johnson, Pieter T J; Joseph, Maxwell B; Rittenhouse, Tracy A G; Ryan, Maureen E; Waddle, J Hardin; Walls, Susan C; Bailey, Larissa L; Fellers, Gary M; Gorman, Thomas A; Ray, Andrew M; Pilliod, David S; Price, Steven J; Saenz, Daniel; Sadinski, Walt; Muths, Erin

    2016-05-23

    Since amphibian declines were first proposed as a global phenomenon over a quarter century ago, the conservation community has made little progress in halting or reversing these trends. The early search for a "smoking gun" was replaced with the expectation that declines are caused by multiple drivers. While field observations and experiments have identified factors leading to increased local extinction risk, evidence for effects of these drivers is lacking at large spatial scales. Here, we use observations of 389 time-series of 83 species and complexes from 61 study areas across North America to test the effects of 4 of the major hypothesized drivers of declines. While we find that local amphibian populations are being lost from metapopulations at an average rate of 3.79% per year, these declines are not related to any particular threat at the continental scale; likewise the effect of each stressor is variable at regional scales. This result - that exposure to threats varies spatially, and populations vary in their response - provides little generality in the development of conservation strategies. Greater emphasis on local solutions to this globally shared phenomenon is needed.

  15. Patch size effects on plant species decline in an experimentally fragmented landscape.

    Science.gov (United States)

    Collins, Cathy D; Holt, Robert D; Foster, Bryan L

    2009-09-01

    Understanding local and global extinction is a fundamental objective of both basic and applied ecology. Island biogeography theory (IBT) and succession theory provide frameworks for understanding extinction in changing landscapes. We explore the relative contribution of fragment size vs. succession on species' declines by examining distributions of abundances for 18 plant species declining over time in an experimentally fragmented landscape in northeast Kansas, U.S.A. If patch size effects dominate, early-successional species should persist longer on large patches, but if successional processes dominate, the reverse should hold, because in our system woody plant colonization is accelerated on large patches. To compare the patterns in abundance among patch sizes, we characterize joint shifts in local abundance and occupancy with a new metric: rank occupancy-abundance profiles (ROAPs). As succession progressed, statistically significant patch size effects emerged for 11 of 18 species. More early-successional species persisted longer on large patches, despite the fact that woody encroachment (succession) progressed faster in these patches. Clonal perennial species persisted longer on large patches compared to small patches. All species that persisted longer on small patches were annuals that recruit from the seed bank each year. The degree to which species declined in occupancy vs. abundance varied dramatically among species: some species declined first in occupancy, others remained widespread or even expanded their distribution, even as they declined in local abundance. Consequently, species exhibited various types of rarity as succession progressed. Understanding the effect of fragmentation on extinction trajectories requires a species-by-species approach encompassing both occupancy and local abundance. We propose that ROAPs provide a useful tool for comparing the distribution of local abundances among landscape types, years, and species. PMID:19769135

  16. Biomechanical effect of vertebroplasty on the adjacent intervertebral levels using a three-dimensional finite element analysis

    Institute of Scientific and Technical Information of China (English)

    LU Sheng; XU Yong-qing; ZHANG Mei-chao; TANG Xun; WANG Yue-li; ZHONG Shi-zheng

    2007-01-01

    Objective: To investigate the biomechanical effect of different volume,distribution and leakage to adjacent disc of bone cement on the adjacent vertebral body by three-dimensional osteoporosis finite element model of lumbar.Methods: L4-L5 motion segment data of the cadaver of an old man who had no abnormal findings on roentgenograms were obtained from computed tomography (CT) scans. Three-dimensional model of L4-L5 was established with Mimics software, and finite element model of L4-L5 functional spinal unit (FSU) was established by Ansys 7.0 software. The effect of different loading conditions and distribution of bone cement after vertebroplasty on the adjacent vertebral body was investigated.Results: This study presented a validated finite element model of L4-L5 FSU with a simulated vertebroplasty augmentation to predict stresses and strains of adjacent untreated vertebral bodies. The findings from this FSU study suggested the endplate and disc stress of the adjacent vertebral body was not influenced by filling volume of bone cement but unipedicle injection and leakage to the disc of bone cement could concentrate the stress of adjacent endplate.Conclusions: Asymmetric distributions and leakage of cement into intervertebral disc can improve the stress of endplate in adjacent vertebral body. These results suggest that optimal biomechanical configuration should have symmetric placement and avoid leakage of cement in operation.

  17. Effects of declining aerosols on projections of zonally averaged tropical precipitation

    International Nuclear Information System (INIS)

    All of the representative concentration pathways (RCPs) assume that future emissions of aerosols and aerosol precursors will decline sharply. There is considerable evidence that historically increasing aerosols have substantially affected tropical precipitation, but the effects of projected aerosol declines have received little attention. We compare projections forced by the medium-low RCP4.5 pathway in two subsets of models from the Coupled Model Intercomparison Project Phase 5 (CMIP5): one group (HiForc) includes treatments of indirect aerosol effects on cloud albedo and cloud lifetime as well as direct aerosol effects, while the other group (LoForc) only treats direct aerosol effects. In this scenario we find that models in the HiForc group consistently project larger increases in both the mean and inter-hemispheric (north minus south) asymmetry of tropical sea-surface temperature (SST) and precipitation than do models in the LoForc group. Earlier projections from CMIP3, in which future aerosol declines were assumed to be smaller, behave more like the CMIP5 LoForc group. These results show that projected tropical SST and precipitation changes are sensitive to assumptions about aerosol emissions and indirect aerosol effects. If the real world resembles the HiForc group, then future aerosol changes are likely to be an important (even dominant) driver of tropical precipitation changes under low to moderate forcing scenarios. (letter)

  18. Synergistic Effect of β-Amyloid and Neurodegeneration on Cognitive Decline in Clinically Normal Individuals

    Science.gov (United States)

    Mormino, Elizabeth C.; Betensky, Rebecca A.; Hedden, Trey; Schultz, Aaron P.; Amariglio, Rebecca E.; Rentz, Dorene M.; Johnson, Keith A.; Sperling, Reisa A.

    2015-01-01

    IMPORTANCE Assessing the ability of Alzheimer disease neuroimaging markers to predict short-term cognitive decline among clinically normal (CN) individuals is critical for upcoming secondary prevention trials using cognitive outcomes. OBJECTIVE To determine whether neuroimaging markers of β-amyloid (Aβ) and neurodegeneration (ND) are independently or synergistically associated with longitudinal cognitive decline in CN individuals. DESIGN, SETTING, AND PARTICIPANTS Academic medical center longitudinal natural history study among 166 CN individuals (median age, 74 years; 92 women). MAIN OUTCOMES AND MEASURES The Aβ status was determined with Pittsburgh Compound B–positron emission tomography, while ND was assessed using 2 a priori measures, hippocampus volume (magnetic resonance imaging) and glucose metabolism (positron emission tomography with fludeoxyglucose F 18), extracted from Alzheimer disease–vulnerable regions. Based on imaging markers, CN individuals were categorized into the following preclinical Alzheimer disease stages: stage 0 (Aβ−/ND−), stage 1 (Aβ+/ND−), stage 2 (Aβ+/ND+), and suspected non–Alzheimer disease pathology (Aβ−/ND+). Cognition was assessed with a composite of neuropsychological tests administered annually. RESULTS The Aβ+ CN individuals were more likely to be classified as ND+: 59.6% of Aβ+ CN individuals were ND+, whereas 31.9% of Aβ− CN individuals were ND+ (odds ratio, 3.14; 95% CI, 1.44–7.02; P = .004). In assessing longitudinal cognitive performance, practice effects were evident in CN individuals negative for both Aβ and ND, whereas diminished practice effects were observed in CN individuals positive for either Aβ or ND. Decline over time was observed only in CN individuals positive for both Aβ and ND, and decline in this group was significantly greater than that in all other groups (P < .001 for all). A significant interaction term between Aβ and ND confirmed that this decline was greater than the

  19. Biomechanics in Schools.

    Science.gov (United States)

    Vincent, J. F. V.

    1980-01-01

    Examines current usage of the term "biomechanics" and emphasizes the importance of differentiating between structure and material. Describes current prolects in biomechanics and lists four points about the educational significance of the field. (GS)

  20. Effects of environmental regulations on heavy metal pollution decline in core sediments from Manila Bay

    International Nuclear Information System (INIS)

    We investigated the high-resolution heavy metal pollution history of Manila Bay using heavy metal concentrations and Pb isotope ratios together with 210Pb dating to find out the effects of environmental regulations after the 1990s. Our results suggested that the rate of decline in heavy metal pollution increased dramatically from the end of the 1990s due to stricter environmental regulations, Administrative Order No. 42, being enforced by the Philippines government. The presented data and methodology should form the basis for future monitoring, leading to pollution control, and to the generation of preventive measures at the pollution source for the maintenance of environmental quality in the coastal metropolitan city of Manila. Although this is the first report of a reduction in pollution in Asian developing country, our results suggest that we can expect to find similar signs of pollution decline in other parts of the world as well.

  1. Predicting effects of cold shock: modeling the decline of a thermal plume

    Energy Technology Data Exchange (ETDEWEB)

    Becker, C.D.; Trent, D.S.; Schneider, M.J.

    1977-10-01

    Predicting direct impact of cold shock on aquatic organisms after termination of power plant thermal discharges requires thermal tests that provide quantitative data on the resistance of acclimated species to lower temperatures. Selected examples from the literature on cold shock resistance of freshwater and marine fishes are illustrated to show predictive use. Abrupt cold shock data may be applied to field situations involving either abrupt or gradual temperature declines but yield conservative estimates under the latter conditions. Gradual cold shock data may be applied where heated plumes gradually dissipate because poikilotherms partially compensate for lowering temperature regimes. A simplified analytical model is presented for estimating thermal declines in terminated plumes originating from offshore, submerged discharges where shear current and boundary effects are minimal. When applied to site-specific conditions, the method provides time-temperature distributions for correlation with cold resistance data and, therefore, aids in assessing cold shock impact on aquatic biota.

  2. Research Techniques in Biomechanics.

    Science.gov (United States)

    Ward, Terry

    Biomechanics involves the biological human beings interacting with his/her mechanical environment. Biomechanics research is being done in connection with sport, physical education, and general motor behavior, and concerns mechanics independent of implements. Biomechanics research falls in the following two general categories: (1) that specific…

  3. Effects of gamma irradiation on the biomechanical properties of peroneus tendons

    Directory of Open Access Journals (Sweden)

    Aguila CM

    2016-09-01

    Full Text Available Christopher M Aguila,1 Gaëtan J-R Delcroix,2–5 David N Kaimrajh,6 Edward L Milne,6 H Thomas Temple,5,7 Loren L Latta2,6 1Department of Biological Sciences, Florida International University, Miami, FL, USA; 2Department of Orthopaedics, Miller School of Medicine, University of Miami, Miami, FL, USA; 3Research Service & Geriatric Research, Education, and Clinical Center, Bruce W. Carter Veterans Affairs Medical Center, Miami, FL, USA; 4Interdisciplinary Stem Cell Institute, University of Miami, Miami, FL, USA; 5Vivex Biomedical Inc., Marietta, GA, USA; 6Max Biedermann Institute for Biomechanics, Miami Beach, FL, USA; 7Translational Research and Economic Development, Nova Southeastern University, Fort-Lauderdale, FL, USA Purpose: This study was designed to investigate the biomechanical properties of nonirradiated (NI and irradiated (IR peroneus tendons to determine if they would be suitable allografts, in regards to biomechanical properties, for anterior cruciate ligament reconstruction after a dose of 1.5–2.5 Mrad.Methods: Seven pairs of peroneus longus (PL and ten pairs of peroneus brevis (PB tendons were procured from human cadavers. The diameter of each allograft was measured. The left side of each allograft was IR at 1.5–2.5 Mrad, whereas the right side was kept aseptic and NI. The allografts were thawed, kept wet with saline, and attached in a single-strand fashion to custom freeze grips using liquid nitrogen. A preload of 10 N was then applied and, after it had reached steady state, the allografts were pulled at 4 cm/sec. The parameters recorded were the displacement and force.Results: The elongation at the peak load was 10.3±2.3 mm for the PB NI side and 13.5±3.3 mm for the PB IR side. The elongation at the peak load was 17.4±5.3 mm for the PL NI side and 16.3±2.0 mm for the PL IR side. For PL, the ultimate load was 2,091.6±148.7 N for NI and 2,122.8±380.0 N for IR. The ultimate load for the PB tendons was 1,485.7±209.3 N for

  4. Effects of laser in situ keratomileusis (LASIK on corneal biomechanical measurements with the Corvis ST tonometer

    Directory of Open Access Journals (Sweden)

    Frings A

    2015-02-01

    Full Text Available Andreas Frings,1,* Stephan J Linke,1,2,* Eva L Bauer,1 Vasyl Druchkiv,1 Toam Katz,1,2 Johannes Steinberg1,2 1Department of Ophthalmology, University Medical Center Hamburg-Eppendorf (UKE, Hamburg, Germany; 2Care Vision Refractive Center, Hamburg, Germany *These authors contributed equally to this work Purpose: This study was initiated to evaluate biomechanical changes using the Corvis ST tonometer (CST on the cornea after laser in situ keratomileusis (LASIK. Setting: University Medical Center Hamburg-Eppendorf, Germany, and Care Vision Refractive Centers, Germany. Design: Retrospective cohort study. Methods: This retrospective study included 37 eyes of 37 refractive patients. All CST measurements were performed 1 day before surgery and at the 1-month follow-up examination. The LASIK procedure included mechanical flap preparation using a Moria SBKmicrokeratome and an Allegretto excimer laser platform. Results: Statistically significant differences were observed for mean first applanation length, mean first and second deflection lengths, mean first and second deflection amplitudes, radius of curvature, and peak distance. Significant positive correlations were found between the change (∆ of radius of curvature and manifest refraction spherical equivalent (MRSE, ablation depth, and ∆intraocular pressure as well as between AD and ∆HC-time. Each diopter of myopic correction in MRSE resulted in an increase in ∆radius of curvature of 0.2 mm. Conclusion: Several CST parameters were statistically significantly altered by LASIK, thereby indicating that flap creation, ablation, or both, significantly change the ability of the cornea to absorb or dissipate energy. Keywords: LASIK, corneal biomechanics, refractive surgery, Corvis ST

  5. The Effect of Contact Lens Usage on Corneal Biomechanical Parameters in Keratoconus Patients

    Directory of Open Access Journals (Sweden)

    Ali Bülent Çankaya

    2012-05-01

    Full Text Available Pur po se: To determine and compare the corneal biomechanical properties in keratoconus patients using rigid gas permeable contact lenses and keratoconus patients who do not use contact lenses. Ma te ri al and Met hod: The study consisted of 70 healthy controls (Group A, 27 ketatoconus subjects who do not use contact lens (Group B and 36 rigid gas permeable contact lens using keratoconic patients (Group C. Corneal viscoelastic parameters were measured with an Ocular response analyzer (ORA. Central corneal thickness was measured with an ultrasonic pachymeter. The differences in ORA parameters between the groups were compared. Re sults: The mean corneal hysteresis (CH in Groups A, B, and C were 10.3±1.5 mm Hg, 7.8±1.4 mm Hg, and 7.4±1.2 mm Hg, respectively. The differences in mean CH between Group A and the other two groups were statistically significant (p<0.01 for both comparisons, but no statistically significant difference was found between groups B and C in terms of mean CH (p=0.61. The mean corneal resistance factor (CRF was 10.7±1.9 in Group A compared with 6.6±1.6 in Group B and 6.1±1.5 in Group C. The differences in mean CRF between Group A and the other two groups were statistically significant (p<0.01 for both comparisons. There was no significant difference in CRF between the keratoconus eyes with or without rigid gas permeable contact lens usage (p=0.57. Dis cus si on: Our results suggest that ORA-generated parameters may be different in subjects with keratoconus. Corneal biomechanical parameters did not demonstrate a clear trend of change with rigid gas permeable contact lens usage. (Turk J Ophthalmol 2012; 42: 197-201

  6. The effect of a daily quiz (TOPday) on self-confidence, enthusiasm, and test results for biomechanics

    NARCIS (Netherlands)

    Tanck, E.J.M.; Maessen, M.F.H.; Hannink, G.J.; Kuppeveld, S.M. van; Bolhuis, S.M.; Kooloos, J.G.M.

    2014-01-01

    Many students in Biomedical Sciences have difficulty understanding biomechanics. In a second-year course, biomechanics is taught in the first week and examined at the end of the fourth week. Knowledge is retained longer if the subject material is repeated. However, how does one encourage students to

  7. Biomechanical supporting effect of tantalum rods for the femoral head with various sized lesions:a finite-element analysis

    Institute of Scientific and Technical Information of China (English)

    LIU Wen-guang; WANG Shao-jin; YIN Qing-feng; LIU Sheng-hou; GUAN Yan-jin

    2012-01-01

    Background Features of necrotic lesions and various interventions could affect the biomechanics of the femoral head.A three-dimensional finite-element analysis was designed to demonstrate necrotic femoral head stress changes with various sizes of necrotic lesions,and evaluate the effect of tantalum rods on preventing femoral head cracking.Methods Femoral computed tomography scans were used to build a normal three-dimensional finite-element femoral head model in a computer.Based on the normal model,necrotic models of different lesion diameters(15 mm,20 mm and 30 mm)were created,as were the repaired models with tantalum rods for each diameter.After a series of meshing and force loading,the von Mises stress distributions,simulating single-legged stance,and stresses on specific points under loaded conditions were determfned for each model.Results Deep exploration into the burdened area of the femoral head indicated that higher stresses to the femoral head were observed with a larger necrotic lesion;the largest stress concentration,91.3 MPa,was found on the femoral head with a lesion diameter of 30 mm.By contrast,topical stress on the surface of the necrotic regions was lowered following implantation of a tantalum rod,and the changesin stress were significant in models with lesions of 15 mm and 30 mm in diameter,with the best biomechanical benefit from the tantalum rod found with a lesion diameter of 15 mm.Conclusions Femoral heads with larger necrotic lesions usually have a higher stress concentration and a higher risk of collapse.Various sized lesions on the femoral head can benefit from the mechanical support offered by the implantation of a tantalum rod;however,femoral heads with smaller sized lesions may benefit more.A thorough evaluation of the lesion size should be conducted prior to the use of tantalum rod implants in the treatment of femoral head necrosis.

  8. Do ankle braces provide similar effects on ankle biomechanical variables in subjects with and without chronic ankle instability during landing?

    Institute of Scientific and Technical Information of China (English)

    Songning; Zhang; Michael; Wortley; Julia; Freedman; Silvernail; Daniel; Carson; Maxime; R.Paquette

    2012-01-01

    <正>Purpose:The purpose of this study was to examine effects of a sport version of a semi-rigid ankle brace(ElementTM) and a soft ankle brace (ASO) on ankle biomechanics and ground reaction forces(GRFs) during a drop landing activity in subjects with chronic ankle instability(CAD compared to healthy subjects with no history of CAI. Methods:Ten healthy subjects and 10 subjects who had multiple ankle sprains participated in the study as the control and unstable subjects, respectively.The CAI subjects were age,body mass index and gender matched with the control subjects.The arch index and ankle functions of the subjects were measured in a subject screening session.During the biomechanical test session,participants performed five trials of drop landing from 0.6 m,wearing no brace(NB).Element? brace and ASO brace.Simultaneous recording of three-dimensional kinematic(240 Hz) and GRF(1200 Hz) data were performed. Results:The CAI subjects had lower ankle functional survey scores.The arch index and deformity results showed greater arch deformity of ElementTM against a static load than in NB and ASO due to greater initial arch position held by the brace.CAI participants had greater eversion velocity than healthy controls.The ASO brace reduced the first peak vertical GRF whereas ElementTM increased 2nd peak vertical GRF. ElementTMbrace reduced eversion range of motion(ROM) and peak eversion velocity compared to NB and ASO.In addition,ElementTM reduced dorsiflexion ROM and increased peak plantarflexion moment compared to NB and ASO. Conclusion:Results of static arch measurements and dynamic ankle motion suggest that the restrictions offered by both braces are in part due to more dorsiflexed ankle positions at contact,and higher initial arch position and stiffer ankle for ElementTM.

  9. Effects of gamma irradiation on the biomechanical properties of peroneus tendons

    Science.gov (United States)

    Aguila, Christopher M; Delcroix, Gaëtan J-R; Kaimrajh, David N; Milne, Edward L; Temple, H Thomas; Latta, Loren L

    2016-01-01

    Purpose This study was designed to investigate the biomechanical properties of nonirradiated (NI) and irradiated (IR) peroneus tendons to determine if they would be suitable allografts, in regards to biomechanical properties, for anterior cruciate ligament reconstruction after a dose of 1.5–2.5 Mrad. Methods Seven pairs of peroneus longus (PL) and ten pairs of peroneus brevis (PB) tendons were procured from human cadavers. The diameter of each allograft was measured. The left side of each allograft was IR at 1.5–2.5 Mrad, whereas the right side was kept aseptic and NI. The allografts were thawed, kept wet with saline, and attached in a single-strand fashion to custom freeze grips using liquid nitrogen. A preload of 10 N was then applied and, after it had reached steady state, the allografts were pulled at 4 cm/sec. The parameters recorded were the displacement and force. Results The elongation at the peak load was 10.3±2.3 mm for the PB NI side and 13.5±3.3 mm for the PB IR side. The elongation at the peak load was 17.4±5.3 mm for the PL NI side and 16.3±2.0 mm for the PL IR side. For PL, the ultimate load was 2,091.6±148.7 N for NI and 2,122.8±380.0 N for IR. The ultimate load for the PB tendons was 1,485.7±209.3 N for NI and 1,318.4±296.9 N for the IR group. The ultimate stress calculations for PL were 90.3±11.3 MPa for NI and 94.8±21.0 MPa for IR. For the PB, the ultimate stress was 82.4±19.0 MPa for NI and 72.5±16.6 MPa for the IR group. The structural stiffness was 216.1±59.0 N/mm for the NI PL and 195.7±51.4 N/mm for the IR side. None of these measures were significantly different between the NI and IR groups. The structural stiffness was 232.1±45.7 N/mm for the NI PB and 161.9±74.0 N/mm for the IR side, and this was the only statistically significant difference found in this study (P=0.034). Conclusion Our statistical comparisons found no significant differences in terms of elongation, ultimate load, or ultimate stress between IR and NI

  10. Effect of Gengnianchun Recipe (更年春方) on Bone Mineral Density,Bone Biomechanical Parameters and Serum Lipid Level in Ovariectomized Rats

    Institute of Scientific and Technical Information of China (English)

    LIU Ke-ju; WANG Wen-jun; LI Da-jin; JIN Hui-fang; ZHOU Wen-jiang

    2006-01-01

    Objective: To observe the effect of Gengnianchun Recipe (更年春方, GNC) on bone mineral density (BMD), bone biomechanical parameters and serum lipid level in the bilaterally ovariectomized (OVX) rats and to explore the prophylactic and therapeutic action of GNC on ovariectomy induced osteoporosis and hyperlipidemia. Methods: OVX SD rats, 10- 12 months old, were divided into different groups and fed with GNC 2 g/d, GNC 1 g/d and Nilestriol 0. 125 mg/week, respectively for 4 months to observe the change of BMD and bone biomechanical parameters of the lumbar vertebrae, and the serum levels of total cholesterol (TC), triglyceride(TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C), and to compare the effect of the two drugs on the morphology of the uterus. Results:There was marked reduction in BMD and biomechanical parameters in lumbar vertebrae ( P<0.01 ) and increase of serum TC and LDL-C levels ( P<0.01 ) in rats after OVX. GNC or Nilestriol significantly improved the decreased BMD and biomechanical parameters of the lumbar vertebrae (P<0.05 or P<0.01), and reduced the serum TC and LDL-C levels (P<0.01). In the Nilestriol group, the wet weight of uterus got increased obviously ( P<0.01 ), the number of uterine glands increased, uterine columnar epithelium thickened, and the mitotic figures in the epithelial stroma and myointimal cells augmented. But no such effect in wet weight and morphology of uterus was found in the GNC group. Conclusion: GNC could increase the BMD and biomechanical parameters of the lumbar vertebrae, reduce the serum TC and LDL-C levels, yet produce no adverse reaction in stimulating proliferation and hypertrophy of uterus.

  11. Effects of vascular risk factors and APOE ε4 on white matter integrity and cognitive decline

    Science.gov (United States)

    Fratiglioni, Laura; Laukka, Erika J.; Lövdén, Martin; Kalpouzos, Grégoria; Keller, Lina; Graff, Caroline; Salami, Alireza; Bäckman, Lars

    2015-01-01

    Objective: To investigate the effects of vascular risk factors and APOE status on white matter microstructure, and subsequent cognitive decline among older people. Methods: This study included 241 participants (age 60 years and older) from the population-based Swedish National Study on Aging and Care in Kungsholmen in central Stockholm, Sweden, who were free of dementia and stroke at baseline (2001–2004). We collected data through interviews, clinical examinations, and laboratory tests. We measured fractional anisotropy (FA) and mean diffusivity (MD) on diffusion tensor imaging, and estimated volume of white matter hyperintensities using automatic segmentation. We assessed global cognitive function with the Mini-Mental State Examination at baseline and at 3- and/or 6-year follow-up. We analyzed the data using multivariate linear regression and linear mixed models. Results: Heavy alcohol consumption, hypertension, and diabetes were significantly associated with lower FA or higher MD (p < 0.05). When aggregating heavy alcohol consumption, hypertension, and diabetes together with current smoking, having an increasing number of these 4 factors concurrently was associated with decreasing FA and increasing MD (ptrend < 0.01), independent of white matter hyperintensities. Vascular risk factors and APOE ε4 allele interacted to negatively affect white matter microstructure; having multiple (≥2) vascular factors was particularly detrimental to white matter integrity among APOE ε4 carriers. Lower tertile of FA and upper tertile of MD were significantly associated with faster Mini-Mental State Examination decline. Conclusions: Vascular risk factors are associated with reduced white matter integrity among older adults, which subsequently predicted faster cognitive decline. The detrimental effects of vascular risk factors on white matter microstructure were exacerbated among APOE ε4 carriers. PMID:25672924

  12. The Contribution of Advanced Glycation End product (AGE) accumulation to the decline in motor function

    OpenAIRE

    Drenth, Hans; Zuidema, Sytse; Bunt, Steven; Bautmans, Ivan; Schans, Cees van der; Hobbelen, Hans

    2016-01-01

    Diminishing motor function is commonly observed in the elderly population and is associated with a wide range of adverse health consequences. Advanced Glycation End products (AGE’s) may contribute to age-related decline in the function of cells and tissues in normal ageing. Although the negative effect of AGE’s on the biomechanical properties of musculoskeletal tissues and the central nervous system have been previously described, the evidence regarding the effect on motor function is fragmen...

  13. Effect of Elastic Modulus on Biomechanical Properties of Lumbar Interbody Fusion Cage

    Institute of Scientific and Technical Information of China (English)

    Yue Zhu; Fusheng Li; Shujun Li; Yulin Hao; Rui Yang

    2009-01-01

    This work focuses on the influence of elastic modulus on biomechanical properties of lumbar interbody fusion cages by selecting two titanium alloys with different elastic modulus.They were made by a new β type alloy with chemical composition of Ti-24Nb-4Zr-7.6Sn having low Young's modulus ~50 GPa and by a conventional biomedical alloy Ti-6Al-4V having Young's modulus ~110 GPa.The results showed that the designed cages with low modulus (LMC) and high modulus (HMC) can keep identical compression load ~9.8 kN and endure fatigue cycles higher than 5× 106 without functional or mechanical failure under 2.0 kN axial compression.The anti-subsidence ability of both group cages were examined by axial compression of thoracic spine specimens (T9~T10) dissected freshly from the calf with averaged age of 6 months.The results showed that the LMC has better anti-subsidence ability than the HMC (p<0.05).The above results suggest that the cage with low elastic modulus has great potential for clinical applications.

  14. Boosting beauty in an economic decline: mating, spending, and the lipstick effect.

    Science.gov (United States)

    Hill, Sarah E; Rodeheffer, Christopher D; Griskevicius, Vladas; Durante, Kristina; White, Andrew Edward

    2012-08-01

    Although consumer spending typically declines in economic recessions, some observers have noted that recessions appear to increase women's spending on beauty products--the so-called lipstick effect. Using both historical spending data and rigorous experiments, the authors examine how and why economic recessions influence women's consumer behavior. Findings revealed that recessionary cues--whether naturally occurring or experimentally primed--decreased desire for most products (e.g., electronics, household items). However, these cues consistently increased women's desire for products that increase attractiveness to mates--the first experimental demonstration of the lipstick effect. Additional studies show that this effect is driven by women's desire to attract mates with resources and depends on the perceived mate attraction function served by these products. In addition to showing how and why economic recessions influence women's desire for beauty products, this research provides novel insights into women's mating psychology, consumer behavior, and the relationship between the two. PMID:22642483

  15. The declining effect of sibling size on children's education in Costa Rica

    Directory of Open Access Journals (Sweden)

    Jing Li

    2014-12-01

    Full Text Available Background: Costa Rica experienced a dramatic fertility decline in the 1960s and 1970s. The same period saw substantial improvement in children's educational attainment in Costa Rica. This correlation is consistent with household-level quantity-quality tradeoffs, but prior research on quantity-quality tradeoff magnitudes is mixed, and little research has estimated quantity-quality tradeoff behaviors in Latin America. Objective: This study explores one dimension of the potential demographic dividend from the fertility decline: the extent to which it was accompanied by quantity-quality tradeoffs leading to higher educational attainment. Specifically, we provide the first estimate of quantity-quality tradeoffs in Costa Rica, analyzing the increase in secondary school attendance among Costa Rican children as the number of siblings decreases. Furthermore, we advance the literature by exploring how that tradeoff has changed over time. Methods: We use 1984 and 2000 Costa Rican census data as well as survey data from the Costa Rican Longevity and Healthy Aging Study (CRELES. To address endogenous family size, the analysis uses an instrumental variable strategy based on the gender of the first two children to identify the causal relationship between number of siblings and children's education. Results: We find that, among our earlier cohorts, having fewer siblings is associated with a significantly higher probability of having attended at least one year of secondary school, particularly among girls. The effect is stronger after we account for the endogeneity of number of children born by the mother. For birth cohorts after 1980 this relationship largely disappears. Conclusions: This study provides strong evidence for a declining quantity-quality (Q-Q tradeoff in Costa Rica. This result suggests one potential explanation for the heterogeneous findings in prior studies elsewhere, but more work will be required to understand why such tradeoffs might vary

  16. FUNDAMENTALS OF BIOMECHANICS

    Directory of Open Access Journals (Sweden)

    Duane Knudson

    2007-09-01

    Full Text Available DESCRIPTION This book provides a broad and in-depth theoretical and practical description of the fundamental concepts in understanding biomechanics in the qualitative analysis of human movement. PURPOSE The aim is to bring together up-to-date biomechanical knowledge with expert application knowledge. Extensive referencing for students is also provided. FEATURES This textbook is divided into 12 chapters within four parts, including a lab activities section at the end. The division is as follows: Part 1 Introduction: 1.Introduction to biomechanics of human movement; 2.Fundamentals of biomechanics and qualitative analysis; Part 2 Biological/Structural Bases: 3.Anatomical description and its limitations; 4.Mechanics of the musculoskeletal system; Part 3 Mechanical Bases: 5.Linear and angular kinematics; 6.Linear kinetics; 7.Angular kinetics; 8.Fluid mechanics; Part 4 Application of Biomechanics in Qualitative Analysis :9.Applying biomechanics in physical education; 10.Applying biomechanics in coaching; 11.Applying biomechanics in strength and conditioning; 12.Applying biomechanics in sports medicine and rehabilitation. AUDIENCE This is an important reading for both student and educators in the medicine, sport and exercise-related fields. For the researcher and lecturer it would be a helpful guide to plan and prepare more detailed experimental designs or lecture and/or laboratory classes in exercise and sport biomechanics. ASSESSMENT The text provides a constructive fundamental resource for biomechanics, exercise and sport-related students, teachers and researchers as well as anyone interested in understanding motion. It is also very useful since being clearly written and presenting several ways of examples of the application of biomechanics to help teach and apply biomechanical variables and concepts, including sport-related ones

  17. Biomechanical analysis of rollator walking

    DEFF Research Database (Denmark)

    Alkjaer, T; Larsen, Peter K; Pedersen, Gitte;

    2006-01-01

    The rollator is a very popular walking aid. However, knowledge about how a rollator affects the walking patterns is limited. Thus, the purpose of the study was to investigate the biomechanical effects of walking with and without a rollator on the walking pattern in healthy subjects....

  18. Forest stand structure, productivity, and age mediate climatic effects on aspen decline.

    Science.gov (United States)

    Bell, David M; Bradford, John B; Lauenroth, William K

    2014-08-01

    Because forest stand structure, age, and productivity can mediate the impacts of climate on quaking aspen (Populus tremuloides) mortality, ignoring stand-scale factors limits inference on the drivers of recent sudden aspen decline. Using the proportion of aspen trees that were dead as an index of recent mortality at 841 forest inventory plots, we examined the relationship of this mortality index to forest structure and climate in the Rocky Mountains and Intermountain Western United States. We found that forest structure explained most of the patterns in mortality indices, but that variation in growing-season vapor pressure deficit and winter precipitation over the last 20 years was important. Mortality index sensitivity to precipitation was highest in forests where aspen exhibited high densities, relative basal areas, quadratic mean diameters, and productivities, whereas sensitivity to vapor pressure deficit was highest in young forest stands. These results indicate that the effects of drought on mortality may be mediated by forest stand development, competition with encroaching conifers, and physiological vulnerabilities of large trees to drought. By examining mortality index responses to both forest structure and climate, we show that forest succession cannot be ignored in studies attempting to understand the causes and consequences of sudden aspen decline.

  19. Age-related cognitive decline during normal aging: the complex effect of education.

    Science.gov (United States)

    Ardila, A; Ostrosky-Solis, F; Rosselli, M; Gómez, C

    2000-08-01

    The purpose of this study was to further analyze the effects of education on cognitive decline during normal aging. An 806-subject sample was taken from five different Mexican regions. Participants ranged in age from 16 to 85 years. Subjects were grouped into four educational levels: illiterate, 1-4, 5-9, and 10 or more years of education, and four age ranges: 16-30, 31-50, 51-65, and 66-85 years. A brief neuropsychological test battery (NEUROPSI), standardized and normalized in Spanish, was administered. The NEUROPSI test battery includes assessment of orientation, attention, memory, language, visuoperceptual abilities, motor skills, and executive functions. In general, test scores were strongly associated with level of educational, and differences among age groups were smaller than differences among education groups. However, there was an interaction between age and education such as that among illiterate individuals scores of participants 31-50 years old were higher than scores of participants 16-30 years old for over 50% of the tests. Different patterns of interaction among educational groups were distinguished. It was concluded that: (a) The course of life-span changes in cognition are affected by education. Among individuals with a low level of education, best neuropsychological test performance is observed at an older age than among higher-educated subjects; and (b) there is not a single relationship between age-related cognitive decline and education, but different patterns may be found, depending upon the specific cognitive domain. PMID:14590204

  20. Forest stand structure, productivity, and age mediate climatic effects on aspen decline

    Science.gov (United States)

    Bell, David M.; Bradford, John B.; Lauenroth, William K.

    2014-01-01

    Because forest stand structure, age, and productivity can mediate the impacts of climate on quaking aspen (Populus tremuloides) mortality, ignoring stand-scale factors limits inference on the drivers of recent sudden aspen decline. Using the proportion of aspen trees that were dead as an index of recent mortality at 841 forest inventory plots, we examined the relationship of this mortality index to forest structure and climate in the Rocky Mountains and Intermountain Western United States. We found that forest structure explained most of the patterns in mortality indices, but that variation in growing-season vapor pressure deficit and winter precipitation over the last 20 years was important. Mortality index sensitivity to precipitation was highest in forests where aspen exhibited high densities, relative basal areas, quadratic mean diameters, and productivities, whereas sensitivity to vapor pressure deficit was highest in young forest stands. These results indicate that the effects of drought on mortality may be mediated by forest stand development, competition with encroaching conifers, and physiological vulnerabilities of large trees to drought. By examining mortality index responses to both forest structure and climate, we show that forest succession cannot be ignored in studies attempting to understand the causes and consequences of sudden aspen decline.

  1. Trematode infection causes malformations and population effects in a declining New Zealand fish.

    Science.gov (United States)

    Kelly, David W; Thomas, Harriet; Thieltges, David W; Poulin, Robert; Tompkins, Daniel M

    2010-03-01

    1. Animal malformations engender wide public and scientific concern because of associated environmental health risks. This is highlighted by increased incidence of limb malformations in amphibians associated with trematode infections and disturbance. Malformations may signal new emerging disease threats, but whether the phenomenon is broadly applicable across taxa, or has population-scale impacts, is unknown. 2. Malformations are widely reported in fish and, until now, have been attributed mainly to contaminants. We tested whether the trematode Telogaster opisthorchis caused severe malformations, leading to population effects, in Galaxias anomalus, a threatened New Zealand freshwater fish. 3. Experimental infection of larval fish caused increasing spinal malformation and mortality with infection intensity that closely matched field patterns. Field malformation frequency peaked in January (65%), before declining sharply in February (25%) and remaining low thereafter. 4. The peak occurred during a 'critical window' of larval development, with the decline coincident with a population crash, indicating that malformation was causing mortality in the field. 5. The occurrence of such critical developmental windows may explain why this mechanism of population impact has been overlooked. With global environmental stressors predicted to enhance trematode infections, our results show that parasite-induced malformation, and its population-scale impacts, could be more widespread than previously considered. PMID:19886894

  2. Effect of pathological myopia on biomechanical properties : a study by ocular response analyzer

    Institute of Scientific and Technical Information of China (English)

    Veysi; ?ner; Mehmet; Tas; Erdal; ?zkaya; Yavuz; Oru?

    2015-01-01

    AIM: To evaluate the ocular response analyzer(ORA)measurements of patients with pathological myopia in comparison with those of emmetropic control subjects,and to investigate the correlation between these ORA measurements and spherical equivalent(SE).METHODS: Measurements of 53 eyes of 53 subjects with pathological myopia(SE >-6.00 D) were compared with those of 60 eyes of 60 emmetropic controls. Corneal hysteresis(CH), corneal resistance factor(CRF),noncontact tonometer intraocular pressure(IOPg), and corneal-compensated IOP(IOPcc) were obtained for each subject. The refractive error value was determined as SE via a cycloplegic refraction test.RESULTS: The mean age was 54.1±18.9y(ranging from5 to 88) in the pathological myopic group and 56.2±19.0y(ranging from 6 to 89) in the control group. There were no significant differences between the groups concerning age and sex. CH and CRF were significantly lower in the pathological myopic group than in the control group(P <0.001, P =0.005, respectively). IOPcc and IOPg were significantly higher in the pathological myopic group than in the control group(P <0.001, P =0.009,respectively). There were significantly positive correlations between CH and SE(r =0.565, P <0.001) and between CRF and SE(r =0.364, P =0.007). There were significantly negative correlations between IOPcc and SE(r =-0.432, P =0.001) and between IOPg and SE(r =-0.401,P =0.003).CONCLUSION: The present study displayed that pathological myopia affected biomechanical properties measured by ORA. The results of corneal biomechanicalproperties measured by ORA may need to be appreciated by taking refraction into account. Further, pathological myopia might be related with the increased IOP.

  3. Effects of a contoured articular prosthetic device on tibiofemoral peak contact pressure: a biomechanical study

    Science.gov (United States)

    Huber, Roland; Thermann, Hajo; Paessler, Hans H.; Skrbensky, Gobert

    2007-01-01

    Many middle-aged patients are affected by localized cartilage defects that are neither appropriate for primary, nor repeat biological repair methods, nor for conventional arthroplasty. This in vitro study aims to determine the peak contact pressure in the tibiofemoral joint with a partial femoral resurfacing device (HemiCAP®, Arthrosurface Inc., Franklin, MA, USA). Peak contact pressure was determined in eight fresh-frozen cadaveric specimens using a Tekscan sensor placed in the medial compartment above the menisci. A closed loop robotic knee simulator was used to test each knee in static stance positions (5°/15°/30°/45°) with body weight ground reaction force (GRF), 30° flexion with twice the body weight (2tBW) GRF and dynamic knee-bending cycles with body weight GRF. The ground reaction force was adjusted to the living body weight of the cadaver donor and maintained throughout all cycles. Each specimen was tested under four different conditions: Untreated, flush HemiCAP® implantation, 1-mm proud implantation and 20-mm defect. A paired sampled t test to compare means (significance, P ≤ 0.05) was used for statistical analysis. On average, no statistically significant differences were found in any testing condition comparing the normal knee with flush device implantation. With the 1-mm proud implant, statistically significant increase of peak contact pressures of 217% (5° stance), 99% (dynamic knee bending) and 90% (30° stance with 2tBW) compared to the untreated condition was seen. No significant increase of peak contact pressure was evaluated with the 20-mm defect. The data suggests that resurfacing with the HemiCAP® does not lead to increased peak contact pressure with flush implantation. However, elevated implantation results in increased peak contact pressure and might be biomechanically disadvantageous in an in vivo application. PMID:17934718

  4. Effect of Mulligan's and Kinesio knee taping on adolescent ballet dancers knee and hip biomechanics during landing.

    Science.gov (United States)

    Hendry, D; Campbell, A; Ng, L; Grisbrook, T L; Hopper, D M

    2015-12-01

    Taping is often used to manage the high rate of knee injuries in ballet dancers; however, little is known about the effect of taping on lower-limb biomechanics during ballet landings in the turnout position. This study investigated the effects of Kinesiotape (KT), Mulligan's tape (MT) and no tape (NT) on knee and hip kinetics during landing in three turnout positions. The effect of taping on the esthetic execution of ballet jumps was also assessed. Eighteen pain-free 12-15-year-old female ballet dancers performed ballet jumps in three turnout positions, under the three knee taping conditions. A Vicon Motion Analysis system (Vicon Oxford, Oxford, UK) and Advanced Mechanical Technology, Inc. (Watertown, Massa chusetts, USA) force plate collected lower-limb mechanics. The results demonstrated that MT significantly reduced peak posterior knee shear forces (P = 0.025) and peak posterior (P = 0.005), medial (P = 0.022) and lateral (P = 0.014) hip shear forces compared with NT when landing in first position. KT had no effect on knee or hip forces. No significant differences existed between taping conditions in all landing positions for the esthetic measures. MT was able to reduce knee and the hip forces without affecting the esthetic performance of ballet jumps, which may have implications for preventing and managing knee injuries in ballet dancers. PMID:25091570

  5. Effect of Mulligan's and Kinesio knee taping on adolescent ballet dancers knee and hip biomechanics during landing.

    Science.gov (United States)

    Hendry, D; Campbell, A; Ng, L; Grisbrook, T L; Hopper, D M

    2015-12-01

    Taping is often used to manage the high rate of knee injuries in ballet dancers; however, little is known about the effect of taping on lower-limb biomechanics during ballet landings in the turnout position. This study investigated the effects of Kinesiotape (KT), Mulligan's tape (MT) and no tape (NT) on knee and hip kinetics during landing in three turnout positions. The effect of taping on the esthetic execution of ballet jumps was also assessed. Eighteen pain-free 12-15-year-old female ballet dancers performed ballet jumps in three turnout positions, under the three knee taping conditions. A Vicon Motion Analysis system (Vicon Oxford, Oxford, UK) and Advanced Mechanical Technology, Inc. (Watertown, Massa chusetts, USA) force plate collected lower-limb mechanics. The results demonstrated that MT significantly reduced peak posterior knee shear forces (P = 0.025) and peak posterior (P = 0.005), medial (P = 0.022) and lateral (P = 0.014) hip shear forces compared with NT when landing in first position. KT had no effect on knee or hip forces. No significant differences existed between taping conditions in all landing positions for the esthetic measures. MT was able to reduce knee and the hip forces without affecting the esthetic performance of ballet jumps, which may have implications for preventing and managing knee injuries in ballet dancers.

  6. Biomechanics principles and practices

    CERN Document Server

    Peterson, Donald R

    2014-01-01

    Presents Current Principles and ApplicationsBiomedical engineering is considered to be the most expansive of all the engineering sciences. Its function involves the direct combination of core engineering sciences as well as knowledge of nonengineering disciplines such as biology and medicine. Drawing on material from the biomechanics section of The Biomedical Engineering Handbook, Fourth Edition and utilizing the expert knowledge of respected published scientists in the application and research of biomechanics, Biomechanics: Principles and Practices discusses the latest principles and applicat

  7. The effect of submerged aquatic vegetation expansion on a declining turbidity trend in the Sacramento-San Joaquin River Delta

    Science.gov (United States)

    Hestir, E.L.; Schoellhamer, David H.; Jonathan Greenberg,; Morgan, Tara; Ustin, S.L.

    2016-01-01

    Submerged aquatic vegetation (SAV) has well-documented effects on water clarity. SAV beds can slow water movement and reduce bed shear stress, promoting sedimentation and reducing suspension. However, estuaries have multiple controls on turbidity that make it difficult to determine the effect of SAV on water clarity. In this study, we investigated the effect of primarily invasive SAV expansion on a concomitant decline in turbidity in the Sacramento-San Joaquin River Delta. The objective of this study was to separate the effects of decreasing sediment supply from the watershed from increasing SAV cover to determine the effect of SAV on the declining turbidity trend. SAV cover was determined by airborne hyperspectral remote sensing and turbidity data from long-term monitoring records. The turbidity trends were corrected for the declining sediment supply using suspended-sediment concentration data from a station immediately upstream of the Delta. We found a significant negative trend in turbidity from 1975 to 2008, and when we removed the sediment supply signal from the trend it was still significant and negative, indicating that a factor other than sediment supply was responsible for part of the turbidity decline. Turbidity monitoring stations with high rates of SAV expansion had steeper and more significant turbidity trends than those with low SAV cover. Our findings suggest that SAV is an important (but not sole) factor in the turbidity decline, and we estimate that 21–70 % of the total declining turbidity trend is due to SAV expansion.

  8. Nikkomycin Z is an effective inhibitor of the chytrid fungus linked to global amphibian declines.

    Science.gov (United States)

    Holden, Whitney M; Fites, J Scott; Reinert, Laura K; Rollins-Smith, Louise A

    2014-01-01

    Fungal infections in humans, wildlife, and plants are a growing concern because of their devastating effects on human and ecosystem health. In recent years, populations of many amphibian species have declined, and some have become extinct due to chytridiomycosis caused by the fungal pathogen Batrachochytrium dendrobatidis. For some endangered amphibian species, captive colonies are the best intermediate solution towards eventual reintroduction, and effective antifungal treatments are needed to cure chytridiomycosis and limit the spread of this pathogen in such survival assurance colonies. Currently, the best accepted treatment for infected amphibians is itraconazole, but its toxic side effects reduce its usefulness for many species. Safer antifungal treatments are needed for disease control. Here, we show that nikkomycin Z, a chitin synthase inhibitor, dramatically alters the cell wall stability of B. dendrobatidis cells and completely inhibits growth of B. dendrobatidis at 250 μM. Low doses of nikkomycin Z enhanced the effectiveness of natural antimicrobial skin peptide mixtures tested in vitro. These studies suggest that nikkomycin Z would be an effective treatment to significantly reduce the fungal burden in frogs infected by B. dendrobatidis.

  9. Effects of ethanol consumption and alcohol detoxification on the biomechanics and morphology the bone in rat femurs.

    Science.gov (United States)

    Garcia, J A D; Souza, A L T; Cruz, L H C; Marques, P P; Camilli, J A; Nakagaki, W R; Esteves, A; Rossi-Junior, W C; Fernandes, G J M; Guerra, F D; Soares, E A

    2015-11-01

    The objective of this study was to verify the effects of ethanol consumption and alcohol detoxification on the biomechanics, area and thickness of cortical and trabecular bone in rat femur. This was an experimental study in which 18 male Wistar rats were used, with 40 days of age, weighing 179 ± 2.5 g. The rats were divided into three groups (n=06): CT (control), AC (chronic alcoholic), DT (detoxification). After experimental procedures, the animals were euthanized by an overdose of the anesthetic and their femurs were collected for mechanical testing and histological processing. All animals did not present malnutrition or dehydration during experimentation period. Morphometric analysis of cortical and trabecular bones in rat femurs demonstrated that AC animals showed inferior dimensions and alcohol detoxification (DT) allowed an enhancement in area and thickness of cortical and trabecular bone. Material and structural properties data of AC group highlighted the harmful effects of ethanol on bone mechanical properties. The results of this study demonstrated that chronic alcoholic rats (AC) presented major bone damage in all analyzed variables. Those findings suggested that alcohol detoxification is highly suggested in pre-operative planning and this corroborates to the success of bone surgery and bone tissue repair. Thanks to the financial support offered by PROBIC - UNIFENAS.

  10. Effect of Extension and Type of Composite-Restored Class II Cavities on Biomechanical Properties of Teeth: A Three Dimensional Finite Element Analysis

    OpenAIRE

    Azam Valian; Elham Moravej-Salehi; Allahyar Geramy; Elham Faramarzi

    2015-01-01

    Objectives: Controversy exists regarding cavity preparation for restoration of interproximal caries in posterior teeth in terms of preserving the tooth structure and suitable stress distribution. This study aimed to assess the effect of extension and type of class II cavities and the remaining tooth structure in maxillary premolars restored with composite resin on the biomechanical properties of teeth using finite element method (FEM). Materials and Methods: Using FEM, eight three-dimensional...

  11. Decline in child marriage and changes in its effect on reproductive outcomes in Bangladesh.

    Science.gov (United States)

    Kamal, S M Mostafa

    2012-09-01

    This paper explores the decline in child marriage and changes in its effect on reproductive outcomes of Bangladeshi women, using the 2007 Bangladesh Demographic and Health Survey data. Chi-square tests, negative binomial Poisson regression and binary logistic regression were performed in analyzing the data. Overall, 82% of women aged 20-49 years were married-off before 18 years of age, and 63% of the marriages took place before 16 years of age. The incidence of child marriage was significantly less among the young women aged 20-24 years compared to their older counterparts. Among others, women's education appeared as the most significant single determinant of child marriage as well as decline in child marriage. Findings revealed that, after being adjusted for sociodemographic factors, child marriage compared to adult marriage appeared to be significantly associated with lower age at first birth (OR=0.81, 95% CI=76-0.86), higher fertility (IRR=1.45, 95% WCI=1.35-1.55), increased risk of child mortality (IRR=1.64, 95% WCI=1.44-1.87), decreased risk of contraceptive-use before any childbirths (OR=0.56, 95% CI=0.50-0.63), higher risk of giving three or more childbirth (OR=3.94, 95% CI=3.38-4.58), elevated risk of unplanned pregnancies (OR=1.21, 95% CI=1.02-1.45), increased risk of pregnancy termination (OR=1.16, 95% CI=1.00-1.34), and higher risk of the use of any current contraceptive method (OR=1.20, 95% CI=1.06-1.35). Increased enforcement of existing policies is crucial for the prevention of child marriage. Special programmes should be undertaken to keep girls in school for longer period to raise the age of females at first marriage in Bangladesh and thereby reduce the adverse reproductive outcomes.

  12. Local bumble bee decline linked to recovery of honey bees, drought effects on floral resources.

    Science.gov (United States)

    Thomson, Diane M

    2016-10-01

    Time series of abundances are critical for understanding how abiotic factors and species interactions affect population dynamics, but are rarely linked with experiments and also scarce for bee pollinators. This gap is important given concerns about declines in some bee species. I monitored honey bee (Apis mellifera) and bumble bee (Bombus spp.) foragers in coastal California from 1999, when feral A. mellifera populations were low due to Varroa destructor, until 2014. Apis mellifera increased substantially, except between 2006 and 2011, coinciding with declines in managed populations. Increases in A. mellifera strongly correlated with declines in Bombus and reduced diet overlap between them, suggesting resource competition consistent with past experimental results. Lower Bombus numbers also correlated with diminished floral resources. Declines in floral abundances were associated with drought and reduced spring rainfall. These results illustrate how competition with an introduced species may interact with climate to drive local decline of native pollinators. PMID:27539950

  13. Biomechanical effect of altered lumbar lordosis on intervertebral lumbar joints during the golf swing: a simulation study.

    Science.gov (United States)

    Bae, Tae Soo; Cho, Woong; Kim, Kwon Hee; Chae, Soo Won

    2014-11-01

    Although the lumbar spine region is the most common site of injury in golfers, little research has been done on intervertebral loads in relation to the anatomical-morphological differences in the region. This study aimed to examine the biomechanical effects of anatomical-morphological differences in the lumbar lordosis on the lumbar spinal joints during a golf swing. The golf swing motions of ten professional golfers were analyzed. Using a subject-specific 3D musculoskeletal system model, inverse dynamic analyses were performed to compare the intervertebral load, the load on the lumbar spine, and the load in each swing phase. In the intervertebral load, the value was the highest at the L5-S1 and gradually decreased toward the T12. In each lumbar spine model, the load value was the greatest on the kypholordosis (KPL) followed by normal lordosis (NRL), hypolordosis (HPL), and excessive lordosis (EXL) before the impact phase. However, results after the follow-through (FT) phase were shown in reverse order. Finally, the load in each swing phase was greatest during the FT phase in all the lumbar spine models. The findings can be utilized in the training and rehabilitation of golfers to help reduce the risk of injury by considering individual anatomical-morphological characteristics. PMID:25162173

  14. The pizzicato knee-joint energy harvester: characterization with biomechanical data and the effect of backpack load

    Science.gov (United States)

    Pozzi, Michele; Aung, Min S. H.; Zhu, Meiling; Jones, Richard K.; Goulermas, John Y.

    2012-07-01

    The reduced power requirements of miniaturized electronics offer the opportunity to create devices which rely on energy harvesters for their power supply. In the case of wearable devices, human-based piezoelectric energy harvesting is particularly difficult due to the mismatch between the low frequency of human activities and the high-frequency requirements of piezoelectric transducers. We propose a piezoelectric energy harvester, to be worn on the knee-joint, that relies on the plucking technique to achieve frequency up-conversion. During a plucking action, a piezoelectric bimorph is deflected by a plectrum; when released due to loss of contact, the bimorph is free to vibrate at its resonant frequency, generating electrical energy with the highest efficiency. A prototype, featuring four PZT-5H bimorphs, was built and is here studied in a knee simulator which reproduces the gait of a human subject. Biomechanical data were collected with a marker-based motion capture system while the subject was carrying a selection of backpack loads. The paper focuses on the energy generation of the harvester and how this is affected by the backpack load. By altering the gait, the backpack load has a measurable effect on performance: at the highest load of 24 kg, a minor reduction in energy generation (7%) was observed and the output power is reduced by 10%. Both are so moderate to be practically unimportant. The average power output of the prototype is 2.06 ± 0.3 mW, which can increase significantly with further optimization.

  15. Reverse engineering of mandible and prosthetic framework: Effect of titanium implants in conjunction with titanium milled full arch bridge prostheses on the biomechanics of the mandible.

    Science.gov (United States)

    De Santis, Roberto; Gloria, Antonio; Russo, Teresa; D'Amora, Ugo; Varriale, Angelo; Veltri, Mario; Balleri, Piero; Mollica, Francesco; Riccitiello, Francesco; Ambrosio, Luigi

    2014-12-18

    This study aimed at investigating the effects of titanium implants and different configurations of full-arch prostheses on the biomechanics of edentulous mandibles. Reverse engineered, composite, anisotropic, edentulous mandibles made of a poly(methylmethacrylate) core and a glass fibre reinforced outer shell were rapid prototyped and instrumented with strain gauges. Brånemark implants RP platforms in conjunction with titanium Procera one-piece or two-piece bridges were used to simulate oral rehabilitations. A lateral load through the gonion regions was used to test the biomechanical effects of the rehabilitations. In addition, strains due to misfit of the one-piece titanium bridge were compared to those produced by one-piece cast gold bridges. Milled titanium bridges had a better fit than cast gold bridges. The stress distribution in mandibular bone rehabilitated with a one-piece bridge was more perturbed than that observed with a two-piece bridge. In particular the former induced a stress concentration and stress shielding in the molar and symphysis regions, while for the latter design these stresses were strongly reduced. In conclusion, prosthetic frameworks changed the biomechanics of the mandible as a result of both their design and manufacturing technology.

  16. Effects of conventional and slanted ventral slot procedures on the biomechanical behavior of the C5-C6 vertebral motion unit in dogs.

    Science.gov (United States)

    Yang, Haisheng; Lambrechts, Nicolaas E; Lehner, Michael; Adam, Gremah M; Packer, Rebecca A; Moore, Trevor W; Main, Russell P

    2016-08-01

    OBJECTIVE To compare the effects of conventional and slanted ventral slot procedures on the biomechanical behavior of the C5-C6 vertebral motion unit (VMU) in dogs. SAMPLE 14 vertebral columns (C4 through C7) from canine cadavers. PROCEDURES Specimens were assigned to a conventional or slanted ventral slot group (n = 7/group). For each specimen, the C5-C6 VMU was tested in ventral and dorsal bending and positive and negative axial torsion before and after surgery. Range of motion (ROM), stiffness, and energy absorption were compared between the 2 groups. RESULTS Both procedures significantly increased the ROM and stiffness and significantly decreased the energy absorption of the C5-C6 VMU in ventral and dorsal bending. Both procedures also increased the ROM in positive and negative axial torsion. In negative torsion, total stiffness and stiffness over the maximum ROM tested decreased less for the slanted slot procedure than for the conventional slot procedure. There were no significant differences between procedures for any of the other biomechanical outcomes examined. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the biomechanical response of the C5-C6 VMU to the conventional and slanted ventral slot procedures was not significantly different, especially when considering postsurgical instability induced by both procedures. This was most likely due to disruption of the nucleus pulposus and dorsal annulus fibrosus of the disk with both procedures. On the basis of these findings, neither procedure appeared biomechanically superior. Comparative clinical studies are warranted to further evaluate the 2 procedures. PMID:27463547

  17. Decline in effectiveness of antenatal corticosteroids with time to birth: real or artefact?

    OpenAIRE

    Gates, Simon; Brocklehurst, Peter

    2007-01-01

    The widely accepted notion that the benefits of antenatal corticosteroids decline with time to birth may not be correct, argue Simon Gates and Peter Brocklehurst, as the evidence is based on unsound subgroup analyses

  18. The employment effects of mergers in a declining industry: the case of South African gold mining.

    OpenAIRE

    Behar, Alberto; Hodge, James

    2007-01-01

    An industry in decline provides an appropriate setting for the theory that mergers and acquisitions destroy implicit contracts and allow for the shedding of excess labour. We test this theory using provincial data from the South African gold mining industry, which has been in decline over the last two decades. Our data clearly portray rises in real wages and falling employment after the end of apartheid and our econometric results are remarkably consistent with standard labour demand theory. ...

  19. Video Games as a Means to Reduce Age-related Cognitive Decline: Attitudes, Compliance, and Effectiveness

    Directory of Open Access Journals (Sweden)

    Walter R. Boot

    2013-02-01

    Full Text Available Recent research has demonstrated broad benefits of video game play to perceptual and cognitive abilities. These broad improvements suggest that video game-based cognitive interventions may be ideal to combat the many perceptual and cognitive declines associated with advancing age. Furthermore, game interventions have the potential to induce higher rates of intervention compliance compared to other cognitive interventions as they are assumed to be inherently enjoyable and motivating. We explored these issues in an intervention that tested the ability of an action game and a brain fitness game to improve a variety of abilities. Cognitive abilities did not significantly improve, suggesting caution when recommending video game interventions as a means to reduce the effects of cognitive aging. However, the game expected to produce the largest benefit based on previous literature (an action game induced the lowest intervention compliance. We explain this low compliance by participants’ ratings of the action game as less enjoyable and by their prediction that training would have few meaningful benefits. Despite null cognitive results, data provide valuable insights into the types of video games older adults are willing to play and why.

  20. Video games as a means to reduce age-related cognitive decline: attitudes, compliance, and effectiveness.

    Science.gov (United States)

    Boot, Walter R; Champion, Michael; Blakely, Daniel P; Wright, Timothy; Souders, Dustin J; Charness, Neil

    2013-01-01

    Recent research has demonstrated broad benefits of video game play to perceptual and cognitive abilities. These broad improvements suggest that video game-based cognitive interventions may be ideal to combat the many perceptual and cognitive declines associated with advancing age. Furthermore, game interventions have the potential to induce higher rates of intervention compliance compared to other cognitive interventions as they are assumed to be inherently enjoyable and motivating. We explored these issues in an intervention that tested the ability of an action game and a "brain fitness" game to improve a variety of abilities. Cognitive abilities did not significantly improve, suggesting caution when recommending video game interventions as a means to reduce the effects of cognitive aging. However, the game expected to produce the largest benefit based on previous literature (an action game) induced the lowest intervention compliance. We explain this low compliance by participants' ratings of the action game as less enjoyable and by their prediction that training would have few meaningful benefits. Despite null cognitive results, data provide valuable insights into the types of video games older adults are willing to play and why. PMID:23378841

  1. Effect of adipose-derived stromal cells and BMP12 on intrasynovial tendon repair: A biomechanical, biochemical, and proteomics study.

    Science.gov (United States)

    Gelberman, Richard H; Shen, Hua; Kormpakis, Ioannis; Rothrauff, Benjamin; Yang, Guang; Tuan, Rocky S; Xia, Younan; Sakiyama-Elbert, Shelly; Silva, Matthew J; Thomopoulos, Stavros

    2016-04-01

    The outcomes of flexor tendon repair are highly variable. As recent efforts to improve healing have demonstrated promise for growth factor- and cell-based therapies, the objective of the current study was to enhance repair via application of autologous adipose derived stromal cells (ASCs) and the tenogenic growth factor bone morphogenetic protein (BMP) 12. Controlled delivery of cells and growth factor was achieved in a clinically relevant canine model using a nanofiber/fibrin-based scaffold. Control groups consisted of repair-only (no scaffold) and acellular scaffold. Repairs were evaluated after 28 days of healing using biomechanical, biochemical, and proteomics analyses. Range of motion was reduced in the groups that received scaffolds compared to normal. There was no effect of ASC + BMP12 treatment for range of motion or tensile properties outcomes versus repair-only. Biochemical assays demonstrated increased DNA, glycosaminoglycans, and crosslink concentration in all repair groups compared to normal, but no effect of ASC + BMP12. Total collagen was significantly decreased in the acellular scaffold group compared to normal and significantly increased in the ASC + BMP12 group compared to the acellular scaffold group. Proteomics analysis comparing healing tendons to uninjured tendons revealed significant increases in proteins associated with inflammation, stress response, and matrix degradation. Treatment with ASC + BMP12 amplified these unfavorable changes. In summary, the treatment approach used in this study induced a negative inflammatory reaction at the repair site leading to poor healing. Future approaches should consider cell and growth factor delivery methods that do not incite negative local reactions. PMID:26445383

  2. A Biomechanical Modeling Study of the Effects of the Orbicularis Oris Muscle and Jaw Posture on Lip Shape

    Science.gov (United States)

    Stavness, Ian; Nazari, Mohammad Ali; Perrier, Pascal; Demolin, Didier; Payan, Yohan

    2013-01-01

    Purpose: The authors' general aim is to use biomechanical models of speech articulators to explore how possible variations in anatomical structure contribute to differences in articulatory strategies and phone systems across human populations. Specifically, they investigated 2 issues: (a) the link between lip muscle anatomy and variability in…

  3. Biomechanical and Macroscopic Evaluations of the Effects of 5-Fluorouracil on Partially Divided Flexor Tendon Injuries in Rabbits

    Institute of Scientific and Technical Information of China (English)

    Shkelzen B Duci; Hysni M Arifi; Hasan R Ahmeti; Suzana Manxhuka-Kerliu; Burim Neziri; Agon Y Mekaj; Shpetim Lajqi

    2015-01-01

    Background:The main goals of flexor tendon surgery are to restore digital motion by providing tendon healing and to preserve tendon gliding.Our purpose was to investigate the effects of 5-fluorouracil (5-FU) on tendon adhesions in partially divided profundus flexor tendons (flexor digitorum profundus [FDPs]) following surgical repair and in partially divided FDPs without surgical repair,and to compare the results of the repair versus the nonrepair of zone two injuries via macroscopic and biomechanical evaluations of tendon adhesions.Methods:We used 32 adult male European rabbits (Oryctolagus cunniculus) weighing from 2.5 to 3.5 kg.The study was performed on the deep flexor tendons of the second and third digits of the right hind paws of the rabbits;thus,a total of 64 tendons were examined in this study.Results:Based on the results achieved in our experimental study,the load (N) significantly increased in subgroup 1a in which the tendons were surgically repaired and were not treated with 5-FU compared with subgroup 2a in which tendons were surgically repaired and treated with 5-FU.Conclusions:The load (N) significantly increased in subgroup 1 a in which the tendons were surgically repaired and were not treated with 5-FU compared to subgroup 2a in which the tendons were surgically repaired and treated with 5-FU.Therefore,these results revealed a decrease in adhesion formation in the subgroup that was treated with 5-FU due to increased resistance to tendon adhesions during their excursion through the tendon sheath,which in this case required greater traction force.

  4. Declining Petroleum Production and the Effect Upon Communities in New Mexico's Permian Basin

    Science.gov (United States)

    Tipton, Ryan D.

    The petroleum industry, a vital component of New Mexico's economy, is in a gradual decline. As petroleum production is primarily focused in the southeastern corner of the state, this decline phenomenon is particularly relevant to area residents. The problem addressed in this study was that little information is available regarding the lived experiences of business and community leaders concerning this phenomenon, particularly in terms of future economic sustainability. The purpose of this qualitative phenomenological study was to interview a purposive sample of business and community leaders regarding their lived experiences and perceptions relating to the economic sustainability of the region. Research questions asked about the general awareness of the decline of oil production---data collected from federal and state databases---and potential options for alternative economic development. Coded data were analyzed and themes and patterns were identified. Findings included a general lack of awareness of area residents regarding a decline of production, assumed economic stability, and resistance to change based on a lack of incentive. Included in the findings were potential options for strategic economic diversification. Recommendations included a campaign to promote awareness of the decline of oil, provide incentives for change, and economic diversification as method of moving the local economy away from dependence upon the petroleum industry. Implications for positive social change were that the affected region can use the findings to identify sustainable alternative industries to support the communities into the future.

  5. Biomechanics of the brain

    CERN Document Server

    Miller, Karol

    2011-01-01

    With contributions from scientists at major institutions, this book presents an introduction to brain anatomy for engineers and scientists. It provides, for the first time, a comprehensive resource in the field of brain biomechanics.

  6. Computational modeling in biomechanics

    CERN Document Server

    Mofrad, Mohammad

    2010-01-01

    This book provides a glimpse of the diverse and important roles that modern computational technology is playing in various areas of biomechanics. It includes unique chapters on ab initio quantum mechanical, molecular dynamic and scale coupling methods..

  7. Partitioning of habitat effects casts light on the decline of the fen orchid, Liparis loeselii

    DEFF Research Database (Denmark)

    Andersen, Dagmar Kappel; Ejrnæs, Rasmus; Minter, Martine Olesen;

    2015-01-01

    Liparis loeselii is a rare and declining orchid species restricted to rich fens in the northern hemisphere. Suggested reasons for the decline are habitat destruction, eutrophication, altered hydrology and scrub encroachment after termination of traditional management such as grazing and hay making....... However, which parameters are most important is not well understood. We use data on vegetation and environmental parameters from extant, potential and historical L. loeselii habitats in Denmark to i) identify a relevant spatial scale for studying L. loeselii; 0.01 m2, 0.25 m2 and 78.5 m2 was tested, ii......) develop a habitat suitability model based on either Ellenberg indicator values or directly measured variables such as tissue nutrient concentrations and vegetation height, and iii) identify the primary reasons for the species decline. We found the largest spatial scale, 78.5 m2 to be superior...

  8. Effect of Nutrition on Biomechanical Properties of Bone in Laying Hens and Broilers

    OpenAIRE

    Osman Olgun

    2014-01-01

    Leg problems have caused significant economic losses in poultry sector. Bone quality and strong is related to nutrition. In this review, effects of nutrition on bone strength are given to laying hens and broilers. For this, effects of some minerals and feed additives on bone quality were reviewed. Calcium, phosphorus, boron and some feed additives in feeding of hens and broilers are important to strong bone. In addition, the form of calcium resources must be considered in laying hens.

  9. Pollen limitation may be a common Allee effect in marine hydrophilous plants: implications for decline and recovery in seagrasses.

    Science.gov (United States)

    Van Tussenbroek, B I; Soissons, L M; Bouma, T J; Asmus, R; Auby, I; Brun, F G; Cardoso, P G; Desroy, N; Fournier, J; Ganthy, F; Garmendia, J M; Godet, L; Grilo, T F; Kadel, P; Ondiviela, B; Peralta, G; Recio, M; Valle, M; Van der Heide, T; Van Katwijk, M M

    2016-10-01

    Pollen limitation may be an important factor in accelerated decline of sparse or fragmented populations. Little is known whether hydrophilous plants (pollen transport by water) suffer from an Allee effect due to pollen limitation or not. Hydrophilous pollination is a typical trait of marine angiosperms or seagrasses. Although seagrass flowers usually have high pollen production, floral densities are highly variable. We evaluated pollen limitation for intertidal populations of the seagrass Zostera noltei in The Netherlands and found a significant positive relation between flowering spathe density and fruit-set, which was suboptimal at seagrasses, potentially accelerating decline and impairing recovery even after environmental conditions have improved substantially. PMID:27272209

  10. Social Participation and the Prevention of Decline in Effectance among Community-Dwelling Elderly: A Population-Based Cohort Study.

    Directory of Open Access Journals (Sweden)

    Kimiko Tomioka

    Full Text Available We examined the association between a decline in effectance and social participation (SP from the perspective of the number and the type of SP in a prospective cohort study.Included in this analysis were community-dwelling elderly aged ≥ 65 without dependency on the basic activities of daily living and reporting a perfect baseline effectance score (n = 4,588; mean age 72.8 ± 5.7. SP was categorized into 5 types: neighborhood associations, hobby groups, local event groups, senior citizen clubs, and volunteer groups. Effectance was evaluated using the Tokyo Metropolitan Institute of Gerontology Index of Competence. Using logistic regression analysis, odds ratio (OR and a 95% confidence interval (CI for a decline in effectance were calculated. Age, family, BMI, pensions, medical history, medications, alcohol, smoking, cognitive function, depression, social support, ADL, and IADL were used as covariates.During the 3-year follow-up, 17.8% of eligible participants reported a decline in effectance. After adjustment for covariates, participation in various groups was associated with the preservation of effectance for both genders. Regarding the type of SP, among females, participation in neighborhood associations (OR: 0.62, 95%CI: 0.48-0.81, hobby groups (0.58, 0.43-0.77, local event groups (0.63, 0.47-0.86, and volunteer groups (0.53, 0.35-0.82 was inversely associated with a decline in effectance. Among males, the beneficial effect was more likely limited to hobby groups (0.59, 0.43-0.81 and volunteer groups (0.57, 0.39-0.83.Our results suggest that participation in a variety of social groups is effective for maintenance of older people's effectance, while the beneficial effect of each type of SP on effectance is stronger for females than for males. Recommending community-dwelling elderly to participate in social groups appropriate for their gender may be effective for successful aging.

  11. The effects of exercise on cognition in older adults with and without cognitive decline: A systematic review

    NARCIS (Netherlands)

    Uffelen, J.G.Z. van; Chin A Paw, M.J.M.; Hopman-Rock, M.; Mechelen, W. van

    2008-01-01

    Objective: To systematically review the effect of physical exercise on cognition in older adults with and without cognitive decline. Data sources: Randomized controlled trials were identified by literature searches in PubMed, EMBASE, CENTRAL, PsycINFO, and AgeLine. Study selection: Papers were inclu

  12. Decline of brown trout () in Switzerland - How to assess potential causes in a multi-factorial cause-effect relationship

    OpenAIRE

    Burkhardt-Holm, Patricia

    2008-01-01

    Decline of brown trout (Salmo trutta) in Switzerland - How to assess potential causes in a multi-factorial cause-effect relationship correspondence: Corresponding author. (Burkhardt-Holm, Patricia) (Burkhardt-Holm, Patricia) Institute Man-Society-Environment, Department of Environmental Sciences, University of Basel - Vesalgasse 1--> , CH-4051 Basel--> , Tel. +41 ? 61 ? 267 04 02--> - SWITZERL...

  13. An Evaluation of the Instructional Effectiveness of a Computer Lesson in Biomechanics.

    Science.gov (United States)

    Boysen, John P.; Francis, Peter R.

    1982-01-01

    One group of undergraduate students were taught a one-hour computerized lesson on free body diagram analysis, developed at Iowa State University for use with the PLATO system. Other students studied the same material using worksheets. Both methods appeared to be equally effective although the computer system offered some instructional advantages.…

  14. Effect of medial arch-heel support in inserts on reducing ankle eversion: a biomechanics study

    Directory of Open Access Journals (Sweden)

    Yung Patrick SH

    2008-02-01

    Full Text Available Abstract Background Excessive pronation (or eversion at ankle joint in heel-toe running correlated with lower extremity overuse injuries. Orthotics and inserts are often prescribed to limit the pronation range to tackle the problem. Previous studies revealed that the effect is product-specific. This study investigated the effect of medial arch-heel support in inserts on reducing ankle eversion in standing, walking and running. Methods Thirteen pronators and 13 normal subjects participated in standing, walking and running trials in each of the following conditions: (1 barefoot, and shod condition with insert with (2 no, (3 low, (4 medium, and (5 high medial arch-heel support. Motions were captured and processed by an eight-camera motion capture system. Maximum ankle eversion was calculated by incorporating the raw coordinates of 15 anatomical positions to a self-compiled Matlab program with kinematics equations. Analysis of variance with repeated measures with post-hoc Tukey pairwise comparisons was performed on the data among the five walking conditions and the five running conditions separately. Results Results showed that the inserts with medial arch-heel support were effective in dynamics trials but not static trials. In walking, they successfully reduced the maximum eversion by 2.1 degrees in normal subjects and by 2.5–3.0 degrees in pronators. In running, the insert with low medial arch support significantly reduced maximum eversion angle by 3.6 and 3.1 degrees in normal subjects and pronators respectively. Conclusion Medial arch-heel support in inserts is effective in reducing ankle eversion in walking and running, but not in standing. In walking, there is a trend to bring the over-pronated feet of the pronators back to the normal eversion range. In running, it shows an effect to restore normal eversion range in 84% of the pronators.

  15. Effect of passive acoustic sampling methodology on detecting bats after declines from white nose syndrome

    Science.gov (United States)

    Coleman, Laci S.; Ford, W. Mark; Dobony, Christopher A.; Britzke, Eric R.

    2014-01-01

    Concomitant with the emergence and spread of white-nose syndrome (WNS) and precipitous decline of many bat species in North America, natural resource managers need modified and/or new techniques for bat inventory and monitoring that provide robust occupancy estimates. We used Anabat acoustic detectors to determine the most efficient passive acoustic sampling design for optimizing detection probabilities of multiple bat species in a WNS-impacted environment in New York, USA. Our sampling protocol included: six acoustic stations deployed for the entire duration of monitoring as well as a 4 x 4 grid and five transects of 5-10 acoustic units that were deployed for 6-8 night sample durations surveyed during the summers of 2011-2012. We used Program PRESENCE to determine detection probability and site occupancy estimates. Overall, the grid produced the highest detection probabilities for most species because it contained the most detectors and intercepted the greatest spatial area. However, big brown bats (Eptesicus fuscus) and species not impacted by WNS were detected easily regardless of sampling array. Endangered Indiana (Myotis sodalis) and little brown (Myotis lucifugus) and tri-colored bats (Perimyotis subflavus) showed declines in detection probabilities over our study, potentially indicative of continued WNS-associated declines. Identification of species presence through efficient methodologies is vital for future conservation efforts as bat populations decline further due to WNS and other factors.   

  16. What Makes Clusters Decline?

    DEFF Research Database (Denmark)

    Østergaard, Christian Richter; Park, Eun Kyung

    2015-01-01

    Most studies on regional clusters focus on identifying factors and processes that make clusters grow. However, sometimes technologies and market conditions suddenly shift, and clusters decline. This paper analyses the process of decline of the wireless communication cluster in Denmark....... The longitudinal study on the high-tech cluster reveals that technological lock-in and exit of key firms have contributed to decline. Entrepreneurship has a positive effect on the cluster’s adaptive capabilities, while multinational companies have contradicting effects by bringing in new resources to the cluster...

  17. Elastodynamic analysis of the human aorta and the effect of biomechanical parameters on its behavior.

    Science.gov (United States)

    Najarian, Siamak; Dargahi, Javad; Farmanzad, Farhad

    2007-01-01

    In this work, a finite element formulation for the analysis of the elastodynamic behavior of the human aorta is presented. In this formulation, a one-dimensional approach was adopted and a comprehensive computer program was written and employed in the mathematical analysis. All the necessary material and geometrical parameters were appropriately incorporated in the simulation. A comparison was made between the simplified elasticity theory and the one proposed in this study using the poroelasticity theory. The effects of certain parameters including the fluid density and the material permeability of the matrix on the behavior of the aortic tissue were investigated. According to these findings, the higher the density of the liquid in the tissue, the more delay will be observed in the resonance frequencies. It was also concluded that in the poroelasticity theory, the resonance frequencies occur at a later stage compared with the elasticity theory. The permeability of liquid into the pores and its damping effect are the two factors that contributed to the delay in the resonance. It was observed that at a frequency of 10 Hz, up to a permeability of about 10(-8) m(4)/N.s, the effect on the magnitude of the amplitude is negligible. However, from this threshold value up to a point at which the permeability is equal to 10(-5) m(4)/N.s, there is a corresponding increase in the amplitude. PMID:17611299

  18. Immediate and 1 week effects of laterally wedge insoles on gait biomechanics in healthy females.

    Science.gov (United States)

    Weinhandl, Joshua T; Sudheimer, Sarah E; Van Lunen, Bonnie L; Stewart, Kimberly; Hoch, Matthew C

    2016-03-01

    It is estimated that approximately 45% of the U.S. population will develop knee osteoarthritis, a disease that creates significant economic burdens in both direct and indirect costs. Laterally wedged insoles have been frequently recommended to reduce knee abduction moments and to manage knee osteoarthritis. However, it remains unknown whether the lateral wedge will reduce knee abduction moments over a prolonged period of time. Thus, the purposes of this study were to (1) examine the immediate effects of a laterally wedged insole in individuals normally aligned knees and (2) determine prolonged effects after the insole was worn for 1 week. Gait analysis was performed on ten women with and without a laterally wedged insole. After participants wore the wedges for a week, a second gait analysis was performed with and without the insole. The wedged insole did not affect peak knee abduction moment, although there was a significant increase in knee abduction angular impulse after wearing the insoles for 1 week. Furthermore, there was a significant increase in vertical ground reaction force at the instance of peak knee abduction moment with the wedges. While the laterally wedged insole used in the current study did not alter knee abduction moments as expected, other studies have shown alterations. Future studies should also examine a longer acclimation period, the influence of gait speed, and the effect of different shoe types with the insole.

  19. A biomechanical modeling study of the effects of the orbicularis oris muscle and jaw posture on lip shape

    CERN Document Server

    Stavness, Ian; Perrier, Pascal; Demolin, Didier; Payan, Yohan

    2013-01-01

    Purpose: The authors' general aim is to use biomechanical models of speech articulators to explore how possible variations in anatomical structure contribute to differences in articulatory strategies and phone systems across human populations. Specifically, they investigated 2 issues: (a) the link between lip muscle anatomy and variability in lip gestures and (b) the constraints of coupled lip/jaw biomechanics on jaw posture in labial sounds. Method: The authors used a model coupling the jaw, tongue, and face. First, the influence of the orbicularis oris (OO) anatomical implementation was analyzed by assessing how changes in depth (from epidermis to the skull) and peripheralness (proximity to the lip horn center) affected lip shaping. Second, the capability of the lip/jaw system to generate protrusion and rounding, or labial closure, was evaluated for different jaw heights. Results: Results showed that a peripheral and moderately deep OO implementation is most appropriate for protrusion and rounding; a superf...

  20. The Biomechanical Effect of Loading Speed on Metal-on-UHMWPE Contact Mechanics.

    Science.gov (United States)

    Zdero, Radovan; Bagheri, Zahra S; Rezaey, Mojtaba; Schemitsch, Emil H; Bougherara, Habiba

    2014-01-01

    Ultra high molecular weight polyethylene (UHMWPE) is a material commonly used in total hip and knee joint replacements. Numerous studies have assessed the effect of its viscoelastic properties on phenomena such as creep, stress relaxation, and tensile stress. However, these investigations either use the complex 3D geometries of total hip and knee replacements or UHMWPE test objects on their own. No studies have directly measured the effect of vertical load application speed on the contact mechanics of a metal sphere indenting UHMWPE. To this end, a metal ball was used to apply vertical force to a series of UHMWPE flat plate specimens over a wide range of loading speeds, namely, 1, 20, 40, 60, 80, 100, and 120 mm/min. Pressure sensitive Fujifilm was placed at the interface to measure contact area. Experimental results showed that maximum contact force ranged from 3596 to 4520 N and was logarithmically related (R(2)=0.96) to loading speed. Average contact area ranged from 76.5 to 79.9 mm(2) and was linearly related (R(2)=0.56) to loading speed. Average contact stress ranged from 45.1 to 58.2 MPa and was logarithmically related (R(2)=0.95) to loading speed. All UHMWPE specimens displayed a circular area of permanent surface damage, which did not disappear with time. This study has practical implications for understanding the contact mechanics of hip and knee replacements for a variety of activities of daily living.

  1. Effects of type and mode of propulsion on hand-cycling biomechanics in nondisabled subjects

    Directory of Open Access Journals (Sweden)

    Arnaud Faupin, PhD

    2011-11-01

    Full Text Available This study investigated the range of motion (ROM (in degrees of the upper limb and trunk, forces (Newtons, two-dimensional fraction effective force (FEF2D (in percent, and torque (Newton meters during hand cycling. Seven nondisabled participants performed a 1 min exercise test at 70 rpm on a hand cycle (HC fixed to an ergometer in synchronous (SC mode versus asynchronous (AC mode and in arm-power (AP versus arm-trunk-power (ATP type of propulsion. Higher (p < 0.001 flexion/extension of the trunk was found during ATP versus AP type and higher (p < 0.001 lateral flexion and rotation of the trunk in AC versus SC mode. The trunk ROM should explain the different force generation patterns observed in this investigation between AC and SC modes and AP and ATP types. However, kinetic results do not allow the most effective type or mode of propulsion (FEF2D: from 72.9% to 89.3% to be established. We conclude that trunk movement is an important parameter to consider in ergonomically optimizing hand cycling. Nevertheless, future studies in experienced HC users, especially with limited trunk function, should be performed.

  2. Effects of target distance on select biomechanical parameters in taekwondo roundhouse kick.

    Science.gov (United States)

    Falco, Coral; Molina-García, Javier; Alvarez, Octavio; Estevan, Isaac

    2013-11-01

    The aim of this study was to investigate the effects of target distance on temporal and impact force parameters that are important performance factors in taekwondo kicks. Forty-nine taekwondo athletes (age = 24.5 +/- 5.9 years; mass = 79.9 +/- 10.8 kg) were recruited: 13 male experts, 21 male novices, 8 female experts, and 6 female novices. Impact force, reaction time, and execution time were computed. Three-way repeated measure ANOVAs revealed significant 'distance' effect on impact force, reaction time, and execution time (p = 0.001). Comparisons between distance conditions revealed that taekwondo athletes kicked with higher impact force from short distance (17.6 +/- 7.5 N/kg) than from long distance (13.1 +/- 5.7 N/kg) (p < 0.001), had lower reaction time from short distance (498 +/- 90 ms) and normal distance (521 +/- 111 ms) than from long distance (602 +/- 121 ms) (p < 0.001), and had lower execution time from short distance (261 +/- 69 ms/m) than from normal distance (306 +/- 105 ms/m) or from long distance (350 +/- 106 ms/m) (p = 0.003 and p < 0.001, respectively). In conclusion, target distance affected the kick performance; as distance increases, impact force decreased and reaction time increased. Therefore, when reaction to a simple visual stimulus is needed, kicking from a long distance is not recommended, as longer time is required to respond.

  3. Effect of Biometric Characteristics on the Change of Biomechanical Properties of the Human Cornea due to Cataract Surgery

    Directory of Open Access Journals (Sweden)

    Xuefei Song

    2014-01-01

    Full Text Available Purpose. To determine the impact of biometric characteristics on changes of biomechanical properties of the human cornea due to standard cataract surgery using biomechanical analysis. Patients and Methods. This prospective consecutive cross-sectional study comprised 54 eyes with cataract in stages I or II that underwent phacoemulsification and IOL implantation. CH, CRF, IOPg, and IOPcc intraocular pressure were measured by biomechanical analysis preoperatively and at 1 month postoperatively. Changes (Δ were calculated as preoperative value versus postoperative value. Biometrical data were extracted from TMS-5 (CSI and SAI, IOLMaster (AL, and EM-3000 (CCT and ECC preoperatively. Results. The average values of the changes were ΔCH=-0.45±1.27 mmHg, ΔCRF=-0.88±1.1 mmHg, ΔIOPg=-1.58±3.15 mmHg, and ΔIOPcc=-1.45±3.93 mmHg. The higher the CSI the smaller the decrease in CH (r=0.302, P=0.028. The higher the CCT the larger the decrease in CRF (r=-0.371, P=0.013. The higher the AL the smaller the decrease in IOPg (r=0.417, P=0.005. The higher the AL, SAI, and EEC the smaller the decrease in IOPcc (r=0.351, P=0.001; r=-0.478, P<0.001; r=0.339, P=0.013. Conclusions. Corneal biomechanical properties were affected by comprehensive factors after cataract surgery, including corneal endothelium properties, biometry, and geometrical characteristics.

  4. Biomechanical effects of polyaxial pedicle screw fixation on the lumbosacral segments with an anterior interbody cage support

    Directory of Open Access Journals (Sweden)

    Chen Hsiang-Ho

    2007-03-01

    Full Text Available Abstract Background Lumbosacral fusion is a relatively common procedure that is used in the management of an unstable spine. The anterior interbody cage has been involved to enhance the stability of a pedicle screw construct used at the lumbosacral junction. Biomechanical differences between polyaxial and monoaxial pedicle screws linked with various rod contours were investigated to analyze the respective effects on overall construct stiffness, cage strain, rod strain, and contact ratios at the vertebra-cage junction. Methods A synthetic model composed of two ultrahigh molecular weight polyethylene blocks was used with four titanium pedicle screws (two in each block and two rods fixation to build the spinal construct along with an anterior interbody cage support. For each pair of the construct fixed with polyaxial or monoaxial screws, the linked rods were set at four configurations to simulate 0°, 7°, 14°, and 21° lordosis on the sagittal plane, and a compressive load of 300 N was applied. Strain gauges were attached to the posterior surface of the cage and to the central area of the left connecting rod. Also, the contact area between the block and the cage was measured using prescale Fuji super low pressure film for compression, flexion, lateral bending and torsion tests. Results Our main findings in the experiments with an anterior interbody cage support are as follows: 1 large segmental lordosis can decrease the stiffness of monoaxial pedicle screws constructs; 2 polyaxial screws rather than monoaxial screws combined with the cage fixation provide higher compression and flexion stiffness in 21° segmental lordosis; 3 polyaxial screws enhance the contact surface of the cage in 21° segmental lordosis. Conclusion Polyaxial screws system used in conjunction with anterior cage support yields higher contact ratio, compression and flexion stiffness of spinal constructs than monoaxial screws system does in the same model when the spinal segment

  5. The effects of gastrocnemius-soleus muscle forces on ankle biomechanics during triple arthrodesis

    DEFF Research Database (Denmark)

    Hejazi, Shima; Rouhi, Gholamreza; Rasmussen, John

    2016-01-01

    This paper presents a finite element model of the ankle, taking into account the effects of muscle forces, determined by a musculoskeletal analysis, to investigate the contact stress distribution in the tibio-talar joint in patients with triple arthrodesis and in normal subjects. Forces of major...... ankle muscles were simulated and corresponded well with the trend of ‎their EMG signals. These forces were applied to the finite element model to obtain stress distributions for patients with triple arthrodesis and normal subjects in three stages of the gait cycle, i.e. heel strike, midstance and heel......-soleus muscle force reduces the stress on the medial malleolus compared with normal subjects....

  6. The effect of a cadence retraining protocol on running biomechanics and efficiency: a pilot study.

    Science.gov (United States)

    Hafer, Jocelyn F; Brown, Allison M; deMille, Polly; Hillstrom, Howard J; Garber, Carol Ewing

    2015-01-01

    Many studies have documented the association between mechanical deviations from normal and the presence or risk of injury. Some runners attempt to change mechanics by increasing running cadence. Previous work documented that increasing running cadence reduces deviations in mechanics tied to injury. The long-term effect of a cadence retraining intervention on running mechanics and energy expenditure is unknown. This study aimed to determine if increasing running cadence by 10% decreases running efficiency and changes kinematics and kinetics to make them less similar to those associated with injury. Additionally, this study aimed to determine if, after 6 weeks of cadence retraining, there would be carryover in kinematic and kinetic changes from an increased cadence state to a runner's preferred running cadence without decreased running efficiency. We measured oxygen uptake, kinematic and kinetic data on six uninjured participants before and after a 6-week intervention. Increasing cadence did not result in decreased running efficiency but did result in decreases in stride length, hip adduction angle and hip abductor moment. Carryover was observed in runners' post-intervention preferred running form as decreased hip adduction angle and vertical loading rate. PMID:25369525

  7. Biomechanical Effects of Stiffness in Parallel With the Knee Joint During Walking.

    Science.gov (United States)

    Shamaei, Kamran; Cenciarini, Massimo; Adams, Albert A; Gregorczyk, Karen N; Schiffman, Jeffrey M; Dollar, Aaron M

    2015-10-01

    The human knee behaves similarly to a linear torsional spring during the stance phase of walking with a stiffness referred to as the knee quasi-stiffness. The spring-like behavior of the knee joint led us to hypothesize that we might partially replace the knee joint contribution during stance by utilizing an external spring acting in parallel with the knee joint. We investigated the validity of this hypothesis using a pair of experimental robotic knee exoskeletons that provided an external stiffness in parallel with the knee joints in the stance phase. We conducted a series of experiments involving walking with the exoskeletons with four levels of stiffness, including 0%, 33%, 66%, and 100% of the estimated human knee quasi-stiffness, and a pair of joint-less replicas. The results indicated that the ankle and hip joints tend to retain relatively invariant moment and angle patterns under the effects of the exoskeleton mass, articulation, and stiffness. The results also showed that the knee joint responds in a way such that the moment and quasi-stiffness of the knee complex (knee joint and exoskeleton) remains mostly invariant. A careful analysis of the knee moment profile indicated that the knee moment could fully adapt to the assistive moment; whereas, the knee quasi-stiffness fully adapts to values of the assistive stiffness only up to ∼80%. Above this value, we found biarticular consequences emerge at the hip joint.

  8. Effects of fatigue from resistance training on barbell back squat biomechanics.

    Science.gov (United States)

    Hooper, David R; Szivak, Tunde K; Comstock, Brett A; Dunn-Lewis, Courtenay; Apicella, Jenna M; Kelly, Neil A; Creighton, Brent C; Flanagan, Shawn D; Looney, David P; Volek, Jeff S; Maresh, Carl M; Kraemer, William J

    2014-04-01

    Exhaustive resistance training programs that have been previously referred to as extreme conditioning protocols have increased in popularity in military and civilian populations in recent years. However, because of their highly fatiguing nature, proprioception is likely altered during such programs that would significantly affect the safety and efficacy of such programs. Therefore, the purpose of this study was to assess the alterations in movement patterns that result from extreme conditioning protocols and to evaluate if these protocols can be deemed safe and effective. Twelve men (age 24 ± 4.2 years, height 173.1 ± 3.6 cm, weight 76.9 ± 7.8 kg, body fat percentage 9.0 ± 2.2%) and 13 women (age 24.5 ± 3.8 years, height 166.9 ± 8.5 cm, weight 66.1 ± 9.2 kg, body fat percentage 18.6 ± 4.0%) with at least 6 months of resistance training experience involving barbell bench press, barbell deadlift, and barbell back squat performed a highly fatiguing resistance training workout. During the barbell back squat, a 2-dimensional analysis was performed where the knee and hip angles were recorded throughout the 55 repetitions of the workout. At the early stages of the protocol, knee angle was significantly lower in men and in women demonstrating less knee flexion. Also, hip angle was significantly lower early in the program in men and in women, demonstrating a greater forward lean. The technique changes that occur in high repetition sets do not favor optimal strength development and may increase the risk of injury, clearly questioning the safety and efficacy of such resistance training programming. This is likely a display of self-preservation by individuals who are faced with high repetition programs.

  9. Female-Specific Effects on Age-Related Spatial Learning Decline in Songbirds

    OpenAIRE

    Kosarussavadi, Saritha

    2015-01-01

    Spatial cognitive decline is a known hallmark for age-related deterioration in learning and memory, as neurobiological changes occur in the hippocampus with advancing age. Sexually dimorphic spatial abilities have also been consistently demonstrated in humans and other mammalian studies. Despite their extended lifespan and adaptations to aging, little is known about avian age-related cognition and physiology. In this experiment, we used zebra finches (Taeniopygia guttata) to investigate the e...

  10. Video Games as a Means to Reduce Age-Related Cognitive Decline: Attitudes, Compliance, and Effectiveness

    OpenAIRE

    Boot, Walter R.; Michael eChampion; Daniel Patrick Blakely; Timothy eWright; Dustin eSouders; Neil eCharness

    2013-01-01

    Recent research has demonstrated broad benefits of video game play to perceptual and cognitive abilities. These broad improvements suggest that video game-based cognitive interventions may be ideal to combat the many perceptual and cognitive declines associated with advancing age. Furthermore, game interventions have the potential to induce higher rates of intervention compliance compared to other cognitive interventions as they are assumed to be inherently enjoyable and motivating. We exp...

  11. The effect of starting point placement technique on thoracic transverse process strength: an ex vivo biomechanical study

    Directory of Open Access Journals (Sweden)

    Burton Douglas C

    2010-07-01

    Full Text Available Abstract Background The use of thoracic pedicle screws in spinal deformity, trauma, and tumor reconstruction is becoming more common. Unsuccessful screw placement may require salvage techniques utilizing transverse process hooks. The effect of different starting point placement techniques on the strength of the transverse process has not previously been reported. The purpose of this paper is to determine the biomechanical properties of the thoracic transverse process following various pedicle screw starting point placement techniques. Methods Forty-seven fresh-frozen human cadaveric thoracic vertebrae from T2 to T9 were disarticulated and matched by bone mineral density (BMD and transverse process (TP cross-sectional area. Specimens were randomized to one of four groups: A, control, and three others based on thoracic pedicle screw placement technique; B, straightforward; C, funnel; and D, in-out-in. Initial cortical bone removal for pedicle screw placement was made using a burr at the location on the transverse process or transverse process-laminar junction as published in the original description of each technique. The transverse process was tested measuring load-to-failure simulating a hook in compression mode. Analysis of covariance and Pearson correlation coefficients were used to examine the data. Results Technique was a significant predictor of load-to-failure (P = 0.0007. The least squares mean (LS mean load-to-failure of group A (control was 377 N, group B (straightforward 355 N, group C (funnel 229 N, and group D (in-out-in 301 N. Significant differences were noted between groups A and C, A and D, B and C, and C and D. BMD (0.925 g/cm2 [range, 0.624-1.301 g/cm2] was also a significant predictor of load-to-failure, for all specimens grouped together (P P 0.05. Level and side tested were not found to significantly correlate with load-to-failure. Conclusions The residual coronal plane compressive strength of the thoracic transverse process

  12. Biomechanical effects of sitting with adjustable ischial and lumbar support on occupational low back pain: evaluation of sitting load and back muscle activity

    Directory of Open Access Journals (Sweden)

    Lin Fang

    2009-02-01

    Full Text Available Abstract Background Compared to standing posture, sitting decreases lumbar lordosis, increases low back muscle activity, disc pressure, and pressure on the ischium, which are associated with occupational LBP. A sitting device that reduces spinal load and low back muscle activities may help increase sitting comfort and reduce LBP risk. The objective of this study is to investigate the biomechanical effect of sitting with a reduced ischial support and an enhanced lumbar support (Off-Loading on load, interface pressure and muscle activities. Methods A laboratory test in low back pain (LBP and asymptomatic subjects was designed to test the biomechanical effect of using the Off-Loading sitting posture. The load and interface pressure on seat and the backrest, and back muscle activities associated with usual and this Off-Loading posture were recorded and compared between the two postures. Results Compared with Normal (sitting upright with full support of the seat and flat backrest posture, sitting in Off-Loading posture significantly shifted the center of the force and the peak pressure on the seat anteriorly towards the thighs. It also significantly decreased the contact area on the seat and increased that on the backrest. It decreased the lumbar muscle activities significantly. These effects are similar in individuals with and without LBP. Conclusion Sitting with reduced ischial support and enhanced lumbar support resulted in reduced sitting load on the lumbar spine and reduced the lumbar muscular activity, which may potentially reduce sitting-related LBP.

  13. Corneal biomechanics: a review.

    Science.gov (United States)

    Piñero, David P; Alcón, Natividad

    2015-03-01

    Biomechanics is often defined as 'mechanics applied to biology'. Due to the variety and complexity of the behaviour of biological structures and materials, biomechanics is better defined as the development, extension and application of mechanics for a better understanding of physiology and physiopathology and consequently for a better diagnosis and treatment of disease and injury. Different methods for the characterisation of corneal biomechanics are reviewed in detail, including those that are currently commercially available (Ocular Response Analyzer and CorVis ST). The clinical applicability of the parameters provided by these devices are discussed, especially in the fields of glaucoma, detection of ectatic disorders and orthokeratology. Likewise, other methods are also reviewed, such as Brillouin microscopy or dynamic optical coherence tomography and others with potential application to clinical practice but not validated for in vivo measurements, such as ultrasonic elastography. Advantages and disadvantages of all these techniques are described. Finally, the concept of biomechanical modelling is revised as well as the requirements for developing biomechanical models, with special emphasis on finite element modelling. PMID:25470213

  14. The effects of biomechanical foot orthoses on the gait patterns of patients with malalignment syndrome as determined by three dimensional gait analysis

    Science.gov (United States)

    Kim, Soo-Hyun; Ahn, Sang-Ho; Jung, Gil-Su; Kim, Jin-Hyun; Cho, Yun-Woo

    2016-01-01

    [Purpose] The biomechanical effects of foot orthoses on malalignment syndrome have not been fully clarified. This experimental investigation was conducted to evaluate the effects of orthoses on the gait patterns of patients with malalignment syndrome. [Subjects and Methods] Ten patients with malalignment syndrome were recruited. For each participant, kinematic and kinetic data were collected under three test conditions: walking barefoot, walking with flat insoles in shoes, and walking with a biomechanical foot orthosis (BFO) in shoes. Gait patterns were analyzed using a motion analysis system. [Results] Spatiotemporal data showed the step and stride lengths when wearing shoes with flat insoles or BFO were significantly greater than when barefoot, and that the walking speed when wearing shoes with BFO was significantly faster than when walking barefoot or with shoes with flat insoles. Kinetic data, showed peak pelvic tilt and obliquity angle were significantly greater when wearing BFO in shoes than when barefoot, and that peak hip flexion/extension angle and peak knee flexion/extension and rotation angles were significantly greater when wearing BFO and flat insoles in shoes than when barefoot. [Conclusion] BFOs can correct pelvic asymmetry while walking. PMID:27190451

  15. Declining global warming effects on the phenology of spring leaf unfolding.

    Science.gov (United States)

    Fu, Yongshuo H; Zhao, Hongfang; Piao, Shilong; Peaucelle, Marc; Peng, Shushi; Zhou, Guiyun; Ciais, Philippe; Huang, Mengtian; Menzel, Annette; Peñuelas, Josep; Song, Yang; Vitasse, Yann; Zeng, Zhenzhong; Janssens, Ivan A

    2015-10-01

    Earlier spring leaf unfolding is a frequently observed response of plants to climate warming. Many deciduous tree species require chilling for dormancy release, and warming-related reductions in chilling may counteract the advance of leaf unfolding in response to warming. Empirical evidence for this, however, is limited to saplings or twigs in climate-controlled chambers. Using long-term in situ observations of leaf unfolding for seven dominant European tree species at 1,245 sites, here we show that the apparent response of leaf unfolding to climate warming (ST, expressed in days advance of leaf unfolding per °C warming) has significantly decreased from 1980 to 2013 in all monitored tree species. Averaged across all species and sites, ST decreased by 40% from 4.0 ± 1.8 days °C(-1) during 1980-1994 to 2.3 ± 1.6 days °C(-1) during 1999-2013. The declining ST was also simulated by chilling-based phenology models, albeit with a weaker decline (24-30%) than observed in situ. The reduction in ST is likely to be partly attributable to reduced chilling. Nonetheless, other mechanisms may also have a role, such as 'photoperiod limitation' mechanisms that may become ultimately limiting when leaf unfolding dates occur too early in the season. Our results provide empirical evidence for a declining ST, but also suggest that the predicted strong winter warming in the future may further reduce ST and therefore result in a slowdown in the advance of tree spring phenology.

  16. Nutritional decline in cystic fibrosis related diabetes: the effect of intensive nutritional intervention.

    LENUS (Irish Health Repository)

    White, H

    2012-02-01

    BACKGROUND: Reports indicate that nutritional and respiratory decline occur up to four years prior to diagnosis of cystic fibrosis related diabetes (CFRD). Our aim was to establish whether intensive nutritional intervention prevents pre-diabetic nutritional decline in an adult population with CFRD. METHODS: 48 adult patients with CFRD were matched to 48 controls with CF, for age, gender and lung pathogen status. Nutritional and other clinical indices were recorded at annual intervals from six years before until two years after diagnosis. Data were also analysed to examine the impact of early and late acquisition of CFRD. RESULTS: No important differences in weight, height, body mass index (BMI), lung function or intravenous treatment were found between groups in the six years prior to diagnosis, nor any significant deviation over time. In those who developed diabetes, use of overnight enteral tube feeding (ETF) was four times as likely at the time of diagnosis, compared to controls [ETF 43.8% (CFRD) v 18.8% (CF Controls), OR 4.0, CI 1.3 to 16.4, p=0.01]. Age at onset of CFRD played a significant role in determining the pre-diabetic clinical course. Younger diabetics with continued growth at study onset (n=17) had a lower BMI from 2 years prior to diagnosis compared to controls [BMI 18.9 kg\\/m(2) (CFRD) v 20.8 kg\\/m(2) (CF Controls), diff=1.9, CI -0.1 to 3.7 p=0.04]. The BMI of older diabetics (completed growth at study onset) was equal to that of controls throughout. CONCLUSION: Pre-diabetic nutritional decline is not inevitable in adults with CFRD, but is influenced by age of onset. In the group overall, those with CFRD are more likely to require ETF from 2 years prior to diagnosis. Despite intensive nutritional intervention, patients who continue to grow throughout the pre-diabetic years, show a level of nutritional decline absent in older adults.

  17. Effects of education and race on cognitive decline: An integrative study of generalizability versus study-specific results.

    Science.gov (United States)

    Gross, Alden L; Mungas, Dan M; Crane, Paul K; Gibbons, Laura E; MacKay-Brandt, Anna; Manly, Jennifer J; Mukherjee, Shubhabrata; Romero, Heather; Sachs, Bonnie; Thomas, Michael; Potter, Guy G; Jones, Richard N

    2015-12-01

    The objective of the study was to examine variability across multiple prospective cohort studies in level and rate of cognitive decline by race/ethnicity and years of education. We compare data across studies, we harmonized estimates of common latent factors representing overall or general cognitive performance, memory, and executive function derived from the: (a) Washington Heights, Hamilton Heights, Inwood Columbia Aging Project (N = 4,115), (b) Spanish and English Neuropsychological Assessment Scales (N = 525), (c) Duke Memory, Health, and Aging study (N = 578), and (d) Neurocognitive Outcomes of Depression in the Elderly (N = 585). We modeled cognitive change over age for cognitive outcomes by race, education, and study. We adjusted models for sex, dementia status, and study-specific characteristics. The results found that for baseline levels of overall cognitive performance, memory, and executive function, differences in race and education tended to be larger than between-study differences and consistent across studies. This pattern did not hold for rate of cognitive decline: effects of education and race/ethnicity on cognitive change were not consistently observed across studies, and when present were small, with racial/ethnic minorities and those with lower education declining at faster rates. In this diverse set of datasets, non-Hispanic Whites and those with higher education had substantially higher baseline cognitive test scores. However, differences in the rate of cognitive decline by race/ethnicity and education did not follow this pattern. This study suggests that baseline test scores and longitudinal change have different determinants, and future studies to examine similarities and differences of causes of cognitive decline in racially/ethnically and educationally diverse older groups is needed.

  18. A preliminary case study of the effect of shoe-wearing on the biomechanics of a horse’s foot

    Science.gov (United States)

    Rankin, Jeffery W.; Gatesy, Stephen M.

    2016-01-01

    Horse racing is a multi-billion-dollar industry that has raised welfare concerns due to injured and euthanized animals. Whilst the cause of musculoskeletal injuries that lead to horse morbidity and mortality is multifactorial, pre-existing pathologies, increased speeds and substrate of the racecourse are likely contributors to foot disease. Horse hooves have the ability to naturally deform during locomotion and dissipate locomotor stresses, yet farriery approaches are utilised to increase performance and protect hooves from wear. Previous studies have assessed the effect of different shoe designs on locomotor performance; however, no biomechanical study has hitherto measured the effect of horseshoes on the stresses of the foot skeleton in vivo. This preliminary study introduces a novel methodology combining three-dimensional data from biplanar radiography with inverse dynamics methods and finite element analysis (FEA) to evaluate the effect of a stainless steel shoe on the function of a Thoroughbred horse’s forefoot during walking. Our preliminary results suggest that the stainless steel shoe shifts craniocaudal, mediolateral and vertical GRFs at mid-stance. We document a similar pattern of flexion-extension in the PIP (pastern) and DIP (coffin) joints between the unshod and shod conditions, with slight variation in rotation angles throughout the stance phase. For both conditions, the PIP and DIP joints begin in a flexed posture and extend over the entire stance phase. At mid-stance, small differences in joint angle are observed in the PIP joint, with the shod condition being more extended than the unshod horse, whereas the DIP joint is extended more in the unshod than the shod condition. We also document that the DIP joint extends more than the PIP after mid-stance and until the end of the stance in both conditions. Our FEA analysis, conducted solely on the bones, shows increased von Mises and Maximum principal stresses on the forefoot phalanges in the shod

  19. Gingival Recessions and Biomechanics

    DEFF Research Database (Denmark)

    Laursen, Morten Godtfredsen

    Gingival recessions and biomechanics “Tissue is the issue, but bone sets the tone.“ A tooth outside the cortical plate can result in loss of bone and development of a gingival recession. The presentation aims to show biomechanical considerations in relation to movement of teeth with gingival...... recessions. Gingival recession is a problem often in the region of the lower incisors. A micro-CT study on human autopsy material, performed at the University of Aarhus, confirmed that the anterior mandibular alveolar envelope is indeed very thin. The prognosis of a gingival recession can be improved...

  20. Effect of age on the biomechanical and microcirculatory properties of the skin in healthy individuals and during venous ulceration

    Directory of Open Access Journals (Sweden)

    Essam H Mattar

    2011-01-01

    Full Text Available Background: With aging there is alteration of elastic properties of the skin and skin-blood flow. Aim: The purpose of this study was to compare age-related changes in selected biomechanical parameters of the skin (skin hardness, skin extensibility, relaxation time constant, τ and subcutaneous microcirculatory quality (SMQ in individuals with and without venous diseases. Materials and Methods: Two groups were studied: the first group was of asymptomatic healthy individuals and the second group included patients with chronic venous insufficiency (CVI and venous ulceration, without edema. Both groups were subdivided to three age categories (21-40, 41-60 and 61-90 years old. Skin hardness was measured by durometer, extensibility and τ were measured using extensometer and SQM was assessed via postural vasoconstrictive response (LDF. Results: Results showed that skin hardness, extensibility, and τ-values were increased, whereas LDF was decreased in the older groups as compared with younger groups. These changes are attributed to alterations in the skin structure and reduced capillaries density networks. Similar behavior was found in the biomechanical and microcirculatory changes in patients with venous ulceration and CVI, but these changes were more increased further in older patients with venous ulceration as compared with older patients with CVI and that can be attribute to more intense response against tissue injury. Conclusions: Since aging elevated skin hardness and extensibility, but lowered vasoconstrictive response in individuals, with and without, venous diseases, we conclude that aging process is likely to cause an accumulation of damaged skin tissues and that could induce an apparent antigen-driven response that altered skin structure and the subsequent biomechanical properties obtained in this study.

  1. Common SIRT1 variants modify the effect of abdominal adipose tissue on aging-related lung function decline.

    Science.gov (United States)

    Curjuric, Ivan; Imboden, Medea; Bridevaux, Pierre-Olivier; Gerbase, Margaret W; Haun, Margot; Keidel, Dirk; Kumar, Ashish; Pons, Marco; Rochat, Thierry; Schikowski, Tamara; Schindler, Christian; von Eckardstein, Arnold; Kronenberg, Florian; Probst-Hensch, Nicole M

    2016-06-01

    Lung function is an independent predictor of mortality and serves as an aging marker in never smokers. The protein sirtuin-1 of gene SIRT1 has profound anti-inflammatory effects and regulates metabolic pathways. Its suggested longevity effects on lower organisms remain poorly studied in humans. In 1132 never smokers of the population-based SAPALDIA cohort, we investigated associations between single nucleotide polymorphisms (SNPs; rs730821, rs10997868, rs10823116) of SIRT1 and aging-related lung function decline over 11 years in terms of change in forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, and forced expiratory flow between 25 and 75 % of FVC (FEF25-75) using multiple linear regression models. Interactions between the SIRT1 SNPs and adiposity parameters (body mass index (BMI), its change and weight gain) were tested by including multiplicative interaction terms into the models. SIRT1 polymorphisms exhibited no main effects, but modified the association between obesity measures and FEV1/FVC and FEF25-75 decline (p = 0.009-0.046). Per risk allele, FEV1/FVC decline was accelerated up to -0.5 % (95 % CI -1.0 to 0 %) and -0.7 % (-1.3 to -0.2 %) over interquartile range increases in BMI (2.4 kg/m(2)) or weight (6.5 kg), respectively. For FEF25-75 decline, corresponding estimates were -57 mL/s (-117 to 4 mL/s) and -76 mL/s (-1429 to -9 mL/s). Interactions were not present in participants with genetically lowered C-reactive protein concentrations. Genetic variation in SIRT1 might therefore affect lung function and human longevity by modifying subclinical inflammation arising from abdominal adipose tissue. PMID:27125385

  2. Effects of n-3 fatty acids on cognitive decline: A randomized double-blind, placebo-controlled trial in stable myocardial infarction patients

    NARCIS (Netherlands)

    Geleijnse, J.M.; Giltay, E.J.; Kromhout, D.

    2012-01-01

    Background Epidemiological studies suggest a protective effect of n-3 fatty acids derived from fish (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) against cognitive decline. For a-linolenic acid (ALA) obtained from vegetable sources, the effect on cognitive decline is unknown. We exami

  3. The Decline of University Patenting and the End of the Bayh-Dole Effect

    CERN Document Server

    Leydesdorff, Loet

    2010-01-01

    University patenting has been heralded as a symbol of changing relations between universities and their social environments. The Bayh-Dole Act of 1980 in the USA was eagerly promoted by the OECD as a recipe for the commercialization of university research, and the law was imitated by a number of national governments. However, since the 2000s university patenting in the most advanced economies has been on the decline both as a percentage and in absolute terms. We suggest that the institutional incentives for university patenting have disappeared with the new regime of university ranking. Patents and spin-offs are not counted in university rankings. In the new arrangements of university-industry-government relations, universities have become very responsive to changes in their relevant environments.

  4. Mathematical foundations of biomechanics.

    Science.gov (United States)

    Niederer, Peter F

    2010-01-01

    The aim of biomechanics is the analysis of the structure and function of humans, animals, and plants by means of the methods of mechanics. Its foundations are in particular embedded in mathematics, physics, and informatics. Due to the inherent multidisciplinary character deriving from its aim, biomechanics has numerous connections and overlapping areas with biology, biochemistry, physiology, and pathophysiology, along with clinical medicine, so its range is enormously wide. This treatise is mainly meant to serve as an introduction and overview for readers and students who intend to acquire a basic understanding of the mathematical principles and mechanics that constitute the foundation of biomechanics; accordingly, its contents are limited to basic theoretical principles of general validity and long-range significance. Selected examples are included that are representative for the problems treated in biomechanics. Although ultimate mathematical generality is not in the foreground, an attempt is made to derive the theory from basic principles. A concise and systematic formulation is thereby intended with the aim that the reader is provided with a working knowledge. It is assumed that he or she is familiar with the principles of calculus, vector analysis, and linear algebra. PMID:21303323

  5. [Three-dimensional Finite Element Analysis of Biomechanical Effect of Rigid Fixation and Elastic Fixation on Lumbar Interbody Fusion].

    Science.gov (United States)

    Wei, Jiangbo; Song, Yueming; Liu, Limin; Zhou, Chunguan; Yang, Xi

    2015-04-01

    This study was aimed to compare the mechanical characteristics under different physiological load conditions with three-dimensional finite element model of rigid fixation and elastic fixation in the lumbar. We observed the stress distribution characteristics of a sample of healthy male volunteer modeling under vertical, flexion and extension torque situation. The outcomes showed that there existed 4-6 times pressure on the connecting rod of rigid fixation compared with the elastic fixations under different loads, and the stress peak and area of force on elastic fixation were much higher than that of the rigid fixations. The elastic fixation has more biomechanical advantages than rigid fixation in promoting interbody lumbar fusion after surgery. PMID:26211247

  6. Effect of ruboxistaurin (RBX) On visual acuity decline over a 6-year period with cessation and reinstitution of therapy

    DEFF Research Database (Denmark)

    Sheetz, Matthew J; Aiello, Lloyd Paul; Shahri, Nazila;

    2011-01-01

    The PKC-DRS2 was a Phase 3, randomized, double-masked, placebo (PBO)-controlled, 3-year study of the effect of 32 mg/day of ruboxistaurin (RBX), an orally administered protein kinase C inhibitor, on vision loss in patients with moderate to severe nonproliferative diabetic retinopathy. Ruboxistaurin...... reduced the occurrence of sustained moderate visual loss (SMVL; ≥15-letter decline in visual acuity sustained for the last 6 months of study participation) from 9.1% in the PBO group (N = 340) to 5.5% in the RBX group (N = 345, P = 0.034). This study evaluates the primary end point of SMVL in a 2-year...

  7. Effect of dexamethasone on mandibular bone biomechanics in rats during the growth phase as assessed by bending test and peripheral quantitative computerized tomography.

    Science.gov (United States)

    Bozzini, Clarisa; Champin, Graciela; Alippi, Rosa M; Bozzini, Carlos E

    2015-04-01

    Long-term glucocorticoid administration to growing rats induces osteopenia and alterations in the biomechanical behavior of the bone. This study was performed to estimate the effects of dexamethasone (DTX), a synthetic steroid with predominant glucocorticoid activity, on the biomechanical properties of the mandible of rats during the growth phase, as assessed by bending test and peripheral quantitative computed tomographic (pQCT) analysis. The data obtained by the two methods will provide more precise information when analyzed together than separately. Female rats aged 23 d (n=7) received 500μg.kg-1 per day of DXT for 4 weeks. At the end of the treatment period, their body weight and body length were 51.3% and 20.6% lower, respectively, than controls. Hemimandible weight and area (an index of mandibular size) were 27.3% and 9.7% lower, respectively. The right hemimandible of each animal was subjected to a mechanical 3-point bending test. Significant weakening of the bone, as shown by a correlative impairment of strength and stiffness, was observed in experimental rats. Bone density and cross-sectional area were measured by pQCT. Cross-sectional, cortical and trabecular areas were reduced by 20% to 30% in the DTX group, as were other cortical parameters, including the bone density, mineral content and cross-sectional moment of inertia. The "bone strength index" (BSI, the product of the pQCT-assessed xCSMI and vCtBMD) was 56% lower in treated rats, which compares well with the 54% and 52% reduction observed in mandibular strength and stiffness determined through the bending test. Data suggest that the corticosteroid exerts a combined, negative action on bone geometry (mass and architecture) and volumetric bone mineral density of cortical bone, which would express independent effects on both cellular (material quality) and tissue (cross-sectional design) levels of biological organization of the skeleton in the species.

  8. Does Anticoagulant Medication Alter Fracture-Healing? A Morphological and Biomechanical Evaluation of the Possible Effects of Rivaroxaban and Enoxaparin Using a Rat Closed Fracture Model.

    Science.gov (United States)

    Prodinger, Peter Michael; Burgkart, Rainer; Kreutzer, Kilian; Liska, Franz; Pilge, Hakan; Schmitt, Andreas; Knödler, Martina; Holzapfel, Boris Michael; Hapfelmeier, Alexander; Tischer, Thomas; Bissinger, Oliver

    2016-01-01

    Low molecular weight heparin (LMWH) is routinely used to prevent thromboembolism in orthopaedic surgery, especially in the treatment of fractures or after joint-replacement. Impairment of fracture-healing due to increased bone-desorption, delayed remodelling and lower calcification caused by direct osteoclast stimulation is a well-known side effect of unfractioned heparin. However, the effect of LMWH is unclear and controversial. Recent studies strongly suggest impairment of bone-healing in-vitro and in animal models, characterized by a significant decrease in volume and quality of new-formed callus. Since October 2008, Rivaroxaban (Xarelto) is available for prophylactic use in elective knee- and hip-arthroplasty. Recently, some evidence has been found indicating an in vitro dose independent reduction of osteoblast function after Rivaroxaban treatment. In this study, the possible influence of Rivaroxaban and Enoxaparin on bone-healing in vivo was studied using a standardized, closed rodent fracture-model. 70 male Wistar-rats were randomized to Rivaroxaban, Enoxaparin or control groups. After pinning the right femur, a closed, transverse fracture was produced. 21 days later, the animals were sacrificed and both femora harvested. Analysis was done by biomechanical testing (three-point bending) and micro CT. Both investigated substances showed histomorphometric alterations of the newly formed callus assessed by micro CT analysis. In detail the bone (callus) volume was enhanced (sign. for Rivaroxaban) and the density reduced. The bone mineral content was enhanced accordingly (sign. for Rivaroxaban). Trabecular thickness was reduced (sign. for Rivaroxaban). Furthermore, both drugs showed significant enlarged bone (callus) surface and degree of anisotropy. In contrast, the biomechanical properties of the treated bones were equal to controls. To summarize, the morphological alterations of the fracture-callus did not result in functionally relevant deficits. PMID:27455072

  9. Does Anticoagulant Medication Alter Fracture-Healing? A Morphological and Biomechanical Evaluation of the Possible Effects of Rivaroxaban and Enoxaparin Using a Rat Closed Fracture Model

    Science.gov (United States)

    Prodinger, Peter Michael; Burgkart, Rainer; Kreutzer, Kilian; Liska, Franz; Pilge, Hakan; Schmitt, Andreas; Knödler, Martina; Holzapfel, Boris Michael; Hapfelmeier, Alexander; Tischer, Thomas; Bissinger, Oliver

    2016-01-01

    Low molecular weight heparin (LMWH) is routinely used to prevent thromboembolism in orthopaedic surgery, especially in the treatment of fractures or after joint-replacement. Impairment of fracture-healing due to increased bone-desorption, delayed remodelling and lower calcification caused by direct osteoclast stimulation is a well-known side effect of unfractioned heparin. However, the effect of LMWH is unclear and controversial. Recent studies strongly suggest impairment of bone-healing in-vitro and in animal models, characterized by a significant decrease in volume and quality of new-formed callus. Since October 2008, Rivaroxaban (Xarelto) is available for prophylactic use in elective knee- and hip-arthroplasty. Recently, some evidence has been found indicating an in vitro dose independent reduction of osteoblast function after Rivaroxaban treatment. In this study, the possible influence of Rivaroxaban and Enoxaparin on bone-healing in vivo was studied using a standardized, closed rodent fracture-model. 70 male Wistar-rats were randomized to Rivaroxaban, Enoxaparin or control groups. After pinning the right femur, a closed, transverse fracture was produced. 21 days later, the animals were sacrificed and both femora harvested. Analysis was done by biomechanical testing (three-point bending) and micro CT. Both investigated substances showed histomorphometric alterations of the newly formed callus assessed by micro CT analysis. In detail the bone (callus) volume was enhanced (sign. for Rivaroxaban) and the density reduced. The bone mineral content was enhanced accordingly (sign. for Rivaroxaban). Trabecular thickness was reduced (sign. for Rivaroxaban). Furthermore, both drugs showed significant enlarged bone (callus) surface and degree of anisotropy. In contrast, the biomechanical properties of the treated bones were equal to controls. To summarize, the morphological alterations of the fracture-callus did not result in functionally relevant deficits. PMID:27455072

  10. Biomechanics of Rowing

    Science.gov (United States)

    Hase, Kazunori; Andrews, Brian J.; Zavatsky, Amy B.; Halliday, Suzanne E.

    A new control model for the study of biomechanical simulation of human movement was investigated using rowing as an example. The objectives were to explore biological and mechanical alternatives to optimal control methods. The simulation methods included simple control mechanisms based on proportional and derivative (PD) control, consideration of a simple neural model, introduction of an inverse dynamics system for feedback, and computational adjustment of control parameters by using an evaluative criterion and optimization method. By using simulation, appropriate rowing motions were synthesized. The generated rowing motion was periodic, continuous, and adaptable so that the pattern was stable against the mechanical force and independent of the initial condition. We believe that the simulation model is not only practical as a computational research tool from a biomechanical-engineering viewpoint but also significant from the point of view of fundamental biological theories of movement.

  11. Biomechanics of Tendon Transfers.

    Science.gov (United States)

    Livermore, Andrew; Tueting, Jonathan L

    2016-08-01

    The transfer of tendons in the upper extremity is a powerful technique to restore function to a partially paralyzed hand. The biomechanical principles of muscle tension and tendon excursion dictate motor function both in the native as well as transferred states. Appropriately tensioning transferred tendons to maximize the function of the associated muscle remains an area of focused research. Newer methods of tendon coaptation have proven similar in strength to the standard Pulvertaft weave, affording more options to the surgeon. PMID:27387073

  12. Teaching undergraduate biomechanics with Just-in-Time Teaching.

    Science.gov (United States)

    Riskowski, Jody L

    2015-06-01

    Biomechanics education is a vital component of kinesiology, sports medicine, and physical education, as well as for many biomedical engineering and bioengineering undergraduate programmes. Little research exists regarding effective teaching strategies for biomechanics. However, prior work suggests that student learning in undergraduate physics courses has been aided by using the Just-in-Time Teaching (JiTT). As physics understanding plays a role in biomechanics understanding, the purpose of study was to evaluate the use of a JiTT framework in an undergraduate biomechanics course. This two-year action-based research study evaluated three JiTT frameworks: (1) no JiTT; (2) mathematics-based JiTT; and (3) concept-based JiTT. A pre- and post-course assessment of student learning used the biomechanics concept inventory and a biomechanics concept map. A general linear model assessed differences between the course assessments by JiTT framework in order to evaluate learning and teaching effectiveness. The results indicated significantly higher learning gains and better conceptual understanding in a concept-based JiTT course, relative to a mathematics-based JiTT or no JiTT course structure. These results suggest that a course structure involving concept-based questions using a JiTT strategy may be an effective method for engaging undergraduate students and promoting learning in biomechanics courses.

  13. Advances of air pollution science: from forest decline to multiple-stress effects on forest ecosystem services.

    Science.gov (United States)

    Paoletti, E; Schaub, M; Matyssek, R; Wieser, G; Augustaitis, A; Bastrup-Birk, A M; Bytnerowicz, A; Günthardt-Goerg, M S; Müller-Starck, G; Serengil, Y

    2010-06-01

    Over the past 20 years, the focus of forest science on air pollution has moved from forest decline to a holistic framework of forest health, and from the effects on forest production to the ecosystem services provided by forest ecosystems. Hence, future research should focus on the interacting factorial impacts and resulting antagonistic and synergistic responses of forest trees and ecosystems. The synergistic effects of air pollution and climatic changes, in particular elevated ozone, altered nitrogen, carbon and water availability, must be key issues for research. Present evidence suggests air pollution will become increasingly harmful to forests under climate change, which requires integration amongst various stressors (abiotic and biotic factors, including competition, parasites and fire), effects on forest services (production, biodiversity protection, soil protection, sustained water balance, socio-economical relevance) and assessment approaches (research, monitoring, modeling) to be fostered.

  14. Advances of air pollution science: from forest decline to multiple-stress effects on forest ecosystem services.

    Science.gov (United States)

    Paoletti, E; Schaub, M; Matyssek, R; Wieser, G; Augustaitis, A; Bastrup-Birk, A M; Bytnerowicz, A; Günthardt-Goerg, M S; Müller-Starck, G; Serengil, Y

    2010-06-01

    Over the past 20 years, the focus of forest science on air pollution has moved from forest decline to a holistic framework of forest health, and from the effects on forest production to the ecosystem services provided by forest ecosystems. Hence, future research should focus on the interacting factorial impacts and resulting antagonistic and synergistic responses of forest trees and ecosystems. The synergistic effects of air pollution and climatic changes, in particular elevated ozone, altered nitrogen, carbon and water availability, must be key issues for research. Present evidence suggests air pollution will become increasingly harmful to forests under climate change, which requires integration amongst various stressors (abiotic and biotic factors, including competition, parasites and fire), effects on forest services (production, biodiversity protection, soil protection, sustained water balance, socio-economical relevance) and assessment approaches (research, monitoring, modeling) to be fostered. PMID:20036449

  15. The long-term effect of the timing of fertility decline on population size

    NARCIS (Netherlands)

    O'Neill, BC; Scherbov, S; Lutz, W

    1999-01-01

    Existing long-range population projections imply that the timing of the fertility transition has a relatively unimportant effect on long-term population size when compared with the impact of the level at which fertility is assumed eventually to stabilize. However, this note shows that the effect of

  16. 运动性疲劳对跳深动作结构影响的生物力学分析%Effect of fatigue on the biomechanics characteristics in drop-jumps

    Institute of Scientific and Technical Information of China (English)

    邹晓峰; 陈民盛

    2009-01-01

    The aims of the study were to determine the structure change of drop-jump training and how it affect the lower joints and muscles when fatigued. Three-dimensional platform, Panasonic camera and MONARK 834E power-cycling was used to test 20 male athletes when unfatigued and fatigued, result indicated that the structure of the drop-jump is significant changed after fatigued, the center of gravity for the speed is Declined to reduce the flight distance, as well as access to significant increase in time, and other characteristics of declining knee function, changes in the scope of the knee point of view of the apparent increase, knee peak power significantly lower, the largest horizontal and vertical impact, Increased significantly, push the vertical stretch significantly less power. Biomechanics of these parameters change, we can see it not only significantly reduces the effect of jump training, while the muscles and joints increases the risk of injury.%使用三维测力平台、Panasonic摄像机和MONARK 834E型功率自行车对20名男学生疲劳前后跳深动作进行测试,结果表明运动性疲劳引起跳深动作结构发生了显著性的变化,表现为重心速度的下降、腾起距离减少,以及与地接触时间显著性增加等特点;膝关节功能不断下降,膝关节角度变化范围明显增大,膝关节峰值功率显著性降低,最大横向和纵向的冲击力明显增大,垂直蹬伸力显著性降低.这些生物力学参数的改变,不但大幅降低了跳深训练的效果,同时增大了关节和肌肉损伤的风险.

  17. Effects of population based screening for Chlamydia infections in the Netherlands limited by declining participation rates.

    Directory of Open Access Journals (Sweden)

    Boris V Schmid

    Full Text Available BACKGROUND: A large trial to investigate the effectiveness of population based screening for chlamydia infections was conducted in the Netherlands in 2008-2012. The trial was register based and consisted of four rounds of screening of women and men in the age groups 16-29 years in three regions in the Netherlands. Data were collected on participation rates and positivity rates per round. A modeling study was conducted to project screening effects for various screening strategies into the future. METHODS AND FINDINGS: We used a stochastic network simulation model incorporating partnership formation and dissolution, aging and a sexual life course perspective. Trends in baseline rates of chlamydia testing and treatment were used to describe the epidemiological situation before the start of the screening program. Data on participation rates was used to describe screening uptake in rural and urban areas. Simulations were used to project the effectiveness of screening on chlamydia prevalence for a time period of 10 years. In addition, we tested alternative screening strategies, such as including only women, targeting different age groups, and biennial screening. Screening reduced prevalence by about 1% in the first two screening rounds and leveled off after that. Extrapolating observed participation rates into the future indicated very low participation in the long run. Alternative strategies only marginally changed the effectiveness of screening. Higher participation rates as originally foreseen in the program would have succeeded in reducing chlamydia prevalence to very low levels in the long run. CONCLUSIONS: Decreasing participation rates over time profoundly impact the effectiveness of population based screening for chlamydia infections. Using data from several consecutive rounds of screening in a simulation model enabled us to assess the future effectiveness of screening on prevalence. If participation rates cannot be kept at a sufficient level

  18. The effect of parameters of equilibrium-based 3-D biomechanical models on extracted muscle synergies during isometric lumbar exertion.

    Science.gov (United States)

    Eskandari, A H; Sedaghat-Nejad, E; Rashedi, E; Sedighi, A; Arjmand, N; Parnianpour, M

    2016-04-11

    A hallmark of more advanced models is their higher details of trunk muscles represented by a larger number of muscles. The question is if in reality we control these muscles individually as independent agents or we control groups of them called "synergy". To address this, we employed a 3-D biomechanical model of the spine with 18 trunk muscles that satisfied equilibrium conditions at L4/5, with different cost functions. The solutions of several 2-D and 3-D tasks were arranged in a data matrix and the synergies were computed by using non-negative matrix factorization (NMF) algorithms. Variance accounted for (VAF) was used to evaluate the number of synergies that emerged by the analysis, which were used to reconstruct the original muscle activations. It was showed that four and six muscle synergies were adequate to reconstruct the input data of 2-D and 3-D torque space analysis. The synergies were different by choosing alternative cost functions as expected. The constraints affected the extracted muscle synergies, particularly muscles that participated in more than one functional tasks were influenced substantially. The compositions of extracted muscle synergies were in agreement with experimental studies on healthy participants. The following computational methods show that the synergies can reduce the complexity of load distributions and allow reduced dimensional space to be used in clinical settings.

  19. Dynamic Observation on the Effects of Different Suture Techniques on the Biomechanical Properties in the Healing of Tendons

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    To identify the best suture techniques for the tendon repair, the biomechanical properties of tendons sutured by different methods were dynamically examined. 140 chickens were divided into 2 groups equally: group A and group B. The tendon of the right side was subjected to injury-repair process, and the tendons of the left sides served as controls in both groups. In group A, "figure-of8" suture, modified Kessler suture and Bunnell suture were used for the 2nd to 4th paws respectively, while in group B, Kleinert suture, Tsuge suture and Ikuta suture were used. On the day 0, 3,7, 14, 21, 28, 42 after operation, 10 animals were sacrificed and the flexor tendons of both sides were harvested for strength test. The results showed that the initial strength of the repaired tendons and the strength after 6 weeks following tendon cut were far below those of intact tendons, irrespective of suture techniques used. With the 6 techniques, the Pmax of tendons repaired by Tsuge suture was increased continually, reaching the highest value on the 42nd day. The Pmax of tendons sutured by the modified Kessler suture was slightly lower than that by Tsuge suture, but it was increased steadily in healing. The tendons repaired by figure-of-8 suture yielded the lowest Pmax. It was concluded that Tsuge suture and modified Kessler suture were the best techniques for tendon repair.

  20. Age-Related Decline in Brain Resources Modulates Genetic Effects on Cognitive Functioning

    Science.gov (United States)

    Lindenberger, Ulman; Nagel, Irene E.; Chicherio, Christian; Li, Shu-Chen; Heekeren, Hauke R.; Bäckman, Lars

    2008-01-01

    Individual differences in cognitive performance increase from early to late adulthood, likely reflecting influences of a multitude of factors. We hypothesize that losses in neurochemical and anatomical brain resources in normal aging modulate the effects of common genetic variations on cognitive functioning. Our hypothesis is based on the assumption that the function relating brain resources to cognition is nonlinear, so that genetic differences exert increasingly large effects on cognition as resources recede from high to medium levels in the course of aging. Direct empirical support for this hypothesis comes from a study by Nagel et al. (2008), who reported that the effects of the Catechol-O-Methyltransferase (COMT) gene on cognitive performance are magnified in old age and interacted with the Brain-Derived Neurotrophic Factor (BDNF) gene. We conclude that common genetic polymorphisms contribute to the increasing heterogeneity of cognitive functioning in old age. Extensions of the hypothesis to other polymorphisms are discussed. (150 of 150 words) PMID:19225597

  1. Age-related decline in brain resources modulates genetic effects on cognitive functioning

    Directory of Open Access Journals (Sweden)

    Ulman Lindenberger

    2008-12-01

    Full Text Available Individual differences in cognitive performance increase from early to late adulthood, likely reflecting influences of a multitude of factors. We hypothesize that losses in neurochemical and anatomical brain resources in normal aging modulate the effects of common genetic variations on cognitive functioning. Our hypothesis is based on the assumption that the function relating brain resources to cognition is nonlinear, so that genetic differences exert increasingly large effects on cognition as resources recede from high to medium levels in the course of aging.Direct empirical support for this hypothesis comes from a study by Nagel et al. (2008, who reported that the effects of the Catechol-O-Methyltransferase (COMT gene on cognitive performance are magnified in old age and interacted with the Brain-Derived Neurotrophic Factor (BDNF gene. We conclude that common genetic polymorphisms contribute to the increasing heterogeneity of cognitive functioning in old age. Extensions of the hypothesis to other polymorphisms are discussed.

  2. Stories of Hope and Decline: Interest Group Effectiveness in National Special Education Policy

    Science.gov (United States)

    Itkonen, Tiina

    2009-01-01

    This study analyzes parent and professional organizations' effectiveness in national special education policy from 1975 to the present. Of specific interest are the relationships between groups' policy victories, how groups construct their political messages, and organizational characteristics. The research is significant in that it is one of the…

  3. "Industrialization and the Fertility Decline"

    OpenAIRE

    Raphael Franck; Oded Galor

    2015-01-01

    The research provides the first empirical examination of the hypothesized effect of industrialization on the fertility decline. Exploiting exogenous source of regional variations in the adoption of steam engines across France, the study establishes that industrialization was a major catalyst in the fertility decline in the course of the demographic transition. Moreover, the analysis further suggests that the contribution of industrialization to the decline in fertility plausibly operated thro...

  4. Protective effect of myostatin gene deletion on aging-related muscle metabolic decline

    OpenAIRE

    Chabi, Beatrice; Pauly, Marion; Carillon, Julie; Carnac, Gilles; Favier, François; Fouret, Gilles; Bonafos, Béatrice; Vanterpool, Frankie; Vernus, Barbara,; Coudray, Charles; Feillet Coudray, Christine; Bonnieu, Anne; Lacan, Dominique

    2016-01-01

    While myostatin gene deletion is a promising therapy to fight muscle loss during aging, this approach induces also skeletal muscle metabolic changes such as mitochondrial deficits, redox alteration and increased fatigability. In the present study, we evaluated the effects of aging on these features in aged wild-type (WT) and mstn knockout (KO) mice. Moreover, to determine whether an enriched-antioxidant diet may be useful to prevent agerelated disorders, we orally administered to the...

  5. Protective effect of myostatin gene deletion on aging-related muscle metabolic decline.

    Science.gov (United States)

    Chabi, B; Pauly, M; Carillon, J; Carnac, G; Favier, F B; Fouret, G; Bonafos, B; Vanterpool, F; Vernus, B; Coudray, C; Feillet-Coudray, C; Bonnieu, A; Lacan, D; Koechlin-Ramonatxo, C

    2016-06-01

    While myostatin gene deletion is a promising therapy to fight muscle loss during aging, this approach induces also skeletal muscle metabolic changes such as mitochondrial deficits, redox alteration and increased fatigability. In the present study, we evaluated the effects of aging on these features in aged wild-type (WT) and mstn knockout (KO) mice. Moreover, to determine whether an enriched-antioxidant diet may be useful to prevent age-related disorders, we orally administered to the two genotypes a melon concentrate rich in superoxide dismutase for 12 weeks. We reported that mitochondrial functional abnormalities persisted (decreased state 3 and 4 of respiration; p<0.05) in skeletal muscle from aged KO mice; however, differences with WT mice were attenuated at old age in line with reduced difference on running endurance between the two genotypes. Interestingly, we showed an increase in glutathione levels, associated with lower lipid peroxidation levels in KO muscle. Enriched antioxidant diet reduced the aging-related negative effects on maximal aerobic velocity and running limit time (p<0.05) in both groups, with systemic adaptations on body weight. The redox status and the hypertrophic phenotype appeared to be beneficial to KO mice, mitigating the effect of aging on the skeletal muscle metabolic remodeling. PMID:26944368

  6. Declining Dioxin concentrations in the Rhone River, France, attest to the effectiveness of emissions controls

    Science.gov (United States)

    Van Metre, Peter C.; Babut, Marc; Mourier, Brice; Mahler, Barbara J.; Roux, Gwenaelle; Desmet, Marc

    2015-01-01

    Emission-control policies have been implemented in Europe and North America since the 1990s for polychlorodibenzodioxins (PCDDs) and furans (PCDFs). To assess the effect of these policies on temporal trends and spatial patterns for these compounds in a large European river system, sediment cores were collected in seven depositional areas along the Rhone River in France, dated, and analyzed for PCDDs and PCDFs. Results show concentrations increase in the downstream direction and have decreased temporally at all sites during the last two decades, with an average decrease of 83% from 1992 to 2010. The time for a 50% decrease in concentrations (t1/2) averaged 6.9 ± 2.6 and 9.1 ± 2.9 years for the sum of measured PCDDs and PCDFs, respectively. Congener patterns are similar among cores and indicate dominance of regional atmospheric deposition and possibly weathered local sources. Local sources are clearly indicated at the most downstream site, where concentrations of the most toxic dioxin, TCDD, are about 2 orders of magnitude higher than at the other six sites. The relatively steep downward trends attest to the effects of the dioxin emissions reduction policy in Europe and suggest that risks posed to aquatic life in the Rhone River basin from dioxins and furans have been greatly reduced.

  7. Effects of climate warming and declining species richness in grassland model ecosystems: acclimation of CO2 fluxes

    Directory of Open Access Journals (Sweden)

    A. S. Kowalski

    2006-09-01

    Full Text Available To study the effects of warming and declining species richness on the carbon balance of grassland communities, model ecosystems containing one, three or nine species were exposed to ambient and elevated (ambient +3°C air temperature. In this paper, we analyze measured ecosystem CO2 fluxes to test whether ecosystem photosynthesis and respiration had acclimated to warming after 28 months of continuous heating, and whether the degree of acclimation depended on species richness. At first sight, we found no signs of acclimation in photosynthesis or respiration. However, because plant cover was significantly higher in the heated treatment, normalization for plant cover revealed down-regulation of both photosynthesis and respiration. Although CO2 fluxes were larger in communities with higher species richness, species richness did not affect the degree of acclimation to warming. These results imply that models need to take into account thermal acclimation to simulate photosynthesis and respiration in a warmer world.

  8. Effect of biomechanical disturbance of the temporomandibular joint on the prevalence of internal derangement in mandibular asymmetry.

    Science.gov (United States)

    Buranastidporn, B; Hisano, M; Soma, K

    2006-06-01

    The aim of the present study was to elucidate the relationship between biomechanical changes of the temporomandibular joint (TMJ) and internal derangement (ID) symptoms in mandibular asymmetry. Posteroanterior cephalograms (PA) of 140 patients with TMJ ID associated with mandibular asymmetry were used to investigate the inclination of the frontal occlusal plane (FOP), and were analysed in conjunction with the results of a report providing information on ID symptoms. A three-dimensional (3D) finite element model (FEM) of the entire mandible was created to investigate the distribution of TMJ forces during clenching. The inclination of the FOP was modified to simulate various degrees of vertical asymmetry. The stresses on the TMJ on the ipsilateral and contralateral sides were analysed and their values were compared with those of the standard model. The results showed that the symptomatic sides were significantly related to the degree of inclination of the FOP. Increasing its angulation resulted in a decrease of the symptoms on the ipsilateral side and an increase of those on the contralateral side. The analysis showed that stress-distribution patterns and overall stresses of the articular disc were influenced by the angulation of inclination of the FOP. These mechanical changes exhibited a distinct relationship with the prevalence of ID in the patients. These results suggest that disturbances in the stresses either in amount or direction due to occlusal inclination can be responsible for ID. Therefore, an attempt to establish a flat occlusal plane is an important orthodontic treatment objective in maintaining the normal health and structure of the TMJ. PMID:16230327

  9. Effect of ovariectomy on BMD, micro-architecture and biomechanics of cortical and cancellous bones in a sheep model.

    Science.gov (United States)

    Wu, Zi-xiang; Lei, Wei; Hu, Yun-yu; Wang, Hai-qiang; Wan, Shi-yong; Ma, Zhen-sheng; Sang, Hong-xun; Fu, Suo-chao; Han, Yi-sheng

    2008-11-01

    Osteoporotic/osteopenia fractures occur most frequently in trabeculae-rich skeletal sites. The purpose of this study was to use a high-resolution micro-computed tomography (micro-CT) and dual energy X-ray absorptionmeter (DEXA) to investigate the changes in micro-architecture and bone mineral density (BMD) in a sheep model resulted from ovariectomy (OVX). Biomechanical tests were performed to evaluate the strength of the trabecular bone. Twenty adult sheeps were randomly divided into three groups: sham group (n=8), group 1 (n=4) and group 2 (n=8). In groups 1 and 2, all sheep were ovariectomized (OVX); in the sham group, the ovaries were located and the oviducts were ligated. In all animals, BMD for lumbar spine was obtained during the surgical procedure. BMD at the spine, femoral neck and femoral condyle was determined 6 months (group 1) and 12 months (group 2) post-OVX. Lumbar spines and femora were obtained and underwent BMD scan, micro-CT analysis. Compressive mechanical properties were determined from biopsies of vertebral bodies and femoral condyles. BMD, micro-architectural parameters and mechanical properties of cancellous bone did not decrease significantly at 6 months post-OVX. Twelve months after OVX, BMD, micro-architectural parameters and mechanical properties decreased significantly. The results of linear regression analyses showed that trabecular thickness (Tb.Th) (r=0.945, R2=0.886) and bone volume fraction (BV/TV) (r=0.783, R2=0.586) had strong (R2>0.5) correlation to compression stress. In OVX sheep, changes in the structural parameters of trabecular bone are comparable to the human situation during osteoporosis was induced. The sheep model presented seems to meet the criteria for an osteopenia model for fracture treatment with respect to morphometric and mechanical properties. But the duration of OVX must be longer than 12 months to ensure the animal model can be established successfully.

  10. Finite element analysis of the biomechanical effects of PEEK dental implants on the peri-implant bone.

    Science.gov (United States)

    Schwitalla, A D; Abou-Emara, M; Spintig, T; Lackmann, J; Müller, W D

    2015-01-01

    Dental implants are mostly fabricated of titanium. Potential problems associated with these implants are discussed in the literature, for example, overloading of the jawbone during mastication due to the significant difference in the elastic moduli of titanium (110 GPa) and bone (≈1-30 GPa). Therefore poly-ether-ether-ketone (PEEK) could represent an alternative biomaterial (elastic modulus 3-4 GPa). Endolign(®) represents an implantable carbon fiber reinforced (CFR)-PEEK including parallel oriented endless carbon fibers. According to the manufacturer it has an elastic modulus of 150 GPa. PEEK compounds filled with powders show an elastic modulus around 4 GPa. The aim of the present finite element analysis was to point out the differences in the biomechanical behavior of a dental implant of Endolign(®) and a commercial powder-filled PEEK. Titanium served as control. These three materials were used for a platform-switched dental implant-abutment assembly, whereas Type 1 completely consisted of titanium, Type 2 of a powder-filled PEEK and Type 3 of Endolign(®). A force of 100 N was applied vertically and of 30° to the implant axis. All types showed a minimum safety factor regarding the yield strength of cortical bone. However, within the limits of this study the Type 2 implant showed higher stresses within the adjacent cortical bone than Type 1 and Type 3. These implant assemblies showed similar stress distributions. Endless carbon fibers give PEEK a high stability. Further investigations are necessary to evaluate whether there is a distinct amount of endless carbon fibers causing an optimal stress distribution behavior of CFR-PEEK. PMID:25435385

  11. Reversing introduced species effects: Experimental removal of introduced fish leads to rapid recovery of a declining frog

    OpenAIRE

    Vredenburg, Vance T.

    2004-01-01

    Amphibian population declines and extinctions are occurring even in the world's least impacted areas. The introduction and spread of nonnative predators is one of many proposed causes of amphibian declines. Correlational studies have shown a negative relationship between introduced fishes and declining amphibians, but little direct experimental evidence is available. This study experimentally manipulated the presence and absence of widely introduced salmonids rainbow trout (Oncorhynchus mykis...

  12. Mistletoe effects on Scots pine decline following drought events: insights from within-tree spatial patterns, growth and carbohydrates.

    Science.gov (United States)

    Sangüesa-Barreda, Gabriel; Linares, Juan Carlos; Camarero, J Julio

    2012-05-01

    Forest decline has been attributed to the interaction of several stressors including biotic factors such as mistletoes and climate-induced drought stress. However, few data exist on how mistletoes are spatially arranged within trees and how this spatial pattern is related to changes in radial growth, responses to drought stress and carbon use. We used dendrochronology to quantify how mistletoe (Viscum album L.) infestation and drought stress affected long-term growth patterns in Pinus sylvestris L. at different heights. Basal area increment (BAI) trends and comparisons between trees of three different infestation degrees (without mistletoe, ID1; moderately infested trees, ID2; and severely infested trees, ID3) were performed using linear mixed-effects models. To identify the main climatic drivers of tree growth tree-ring widths were converted into indexed chronologies and related to climate data using correlation functions. We performed spatial analyses of the 3D distribution of mistletoe individuals and their ages within the crowns of three severely infested pines to describe their patterns. Lastly, we quantified carbohydrate and nitrogen concentrations in needles and sapwood of branches from severely infested trees and from trees without mistletoe. Mistletoe individuals formed strongly clustered groups of similar age within tree crowns and their age increased towards the crown apex. Mistletoe infestation negatively impacted growth but this effect was stronger near the tree apex than in the rest of sampled heights, causing an average loss of 64% in BAI (loss of BAI was ∼51% at 1.3 m or near the tree base). We found that BAI of severely infested trees and moderately or non-infested trees diverged since 2001 and such divergence was magnified by drought. Infested trees had lower concentrations of soluble sugars in their needles than non-infested ones. We conclude that mistletoe infestation causes growth decline and increases the sensitivity of trees to drought

  13. Decline in urinary retention incidence in 805 patients after prostate brachytherapy: The effect of learning curve?

    International Nuclear Information System (INIS)

    Purpose: To evaluate the incidence and factors predictive of acute urinary retention (AUR) in 805 consecutive patients treated with prostate brachytherapy monotherapy and to examine the possible effect of a learning curve. Methods and Materials: Between July 1998 and November 2002, 805 patients were treated with prostate brachytherapy. Low-risk patients (Gleason Score (GS) ≤6; prostate specific antigen (PSA) ≤10, and ≤ T2b [UICC 1997]) received implant alone. Patients with prostate volume of 50 cc or more, GS = 7, or PSA = 10 to 15 received 6 months of androgen suppression (AS) with brachytherapy. Patient, treatment, and dosimetric factors examined include baseline prostate symptom score (IPSS), diabetes, vascular disease, PSA, Gleason score, clinical stage, AS, ultrasound planning target volume (PUTV), postimplant prostate volume (obtained with 'Day 30' postimplant CT), CT:PUTV ratio (surrogate for postimplant edema), number of seeds, number of needles, number of seeds per needle, dosimetric parameters (V100, V150, and D90), date of implant (learning curve), and implanting oncologists. Univariate and multivariate analyses were carried out. Results: Acute urinary retention in the first 200 patients was 17% vs. 6.3% in the most recently treated 200 patients (p = 0.002). Overall AUR was 12.7%, and prolonged urinary obstruction incidence (>20 days) was 5%. On multivariate analysis, factors predictive of any AUR include baseline IPSS (p = 20 days) on multivariate analysis include IPSS (p < 0.01), number of needles (p < 0.001), diabetes mellitus (p = 0.048), and CT:PUTV ratio (p < 0.001) Conclusion: Over the years, our AUR rate has fallen significantly (from 17% to 6.3%). On multivariate analysis, highly significant factors include IPSS, PUTV, CT:PUTV ratio (i.e., degree of prostate edema), and order of implant (learning curve). Over the course of the program, we have deliberately reduced the number of needles and OR time per patient, which have potentially

  14. Biomechanical strain of goldsmiths.

    Science.gov (United States)

    Cândido, Paula Emanuela Fernandes; Teixeira, Juliana Vieira Schmidt; Moro, Antônio Renato Pereira; Gontijo, Leila Amaral

    2012-01-01

    The work of the goldsmiths consists in the manufacture of jewelry. The piece, be it an earring, bracelet or necklace, is hand-assembled. This task requires precision, skill, kindness and patience. In this work, we make use of tools such as cuticle clippers and rounded tip, beads or precious stones and also pieces of metal. This type of activity requires a biomechanical stress of hands and wrists. In order to quantify the biomechanical stress, we performed a case study to measure the movements performed by an assembly of pieces of jewelry. As method for research, filming was done during assembly of parts to a paste, using a Nikon digital camera, for 1 (one) hour. The film was edited by Kinovea software, and the task was divided into cycles, each cycle corresponds to a complete object. In one cycle, there are four two movements of supination and pronation movements of the forearm. The cycle lasts approximately sixteen seconds, totaling 1800 cycles in eight hours. Despite the effort required of the wrists, the activity shows no complaints from the employees, but this fact does not mischaracterizes the ability of employees to acquire repetitive strain injuries and work-related musculoskeletal disorders. PMID:22317096

  15. Effects of local delivery of BMP2, zoledronate and their combination on bone microarchitecture, biomechanics and bone turnover in osteoporotic rabbits.

    Science.gov (United States)

    Jing, Da; Hao, Xuguang; Xu, Fang; Liu, Jian; Xu, Fei; Luo, Erping; Meng, Guolin

    2016-01-01

    The hip fracture is one major clinical challenge associated with osteoporosis, resulting in heavy socioeconomic burdens and high mortality. Systemic therapies of anti-osteoporosis drugs are expensive, time-consuming and also evoke substantial side effects, which fails to provide early protection from fractures. Accumulating evidence demonstrates the high bioavailability and therapeutic efficacy of local drug delivery in accelerating facture healing and bone defect repair. This study aims at investigating the effects of local delivery of BMP2 and zoledronate (two promising anabolic/anti-catobolic reagents) encapsulated by fibrin sealants into femoral necks on regulating bone quality and remodeling in osteoporotic rabbits subjected to combined ovariectomy and glucocorticoid injection. We show that 6-week BMP2 delivery exhibited more prominent effect on mitigating trabecular bone microarchitecture deterioration and mechanical strength reduction of femoral necks than local zoledronate treatment. BMP2 plus zoledronate showed more significant improvement of bone microstructure, mechanical strength and bone formation rate at 12 weeks post injection than single BMP2 or zoledronate delivery via μCT, biomechanical, histomorphometric and serum biochemical analyses. This study enriches our knowledge for understanding the availability of local drug delivery for improving bone quantity and quality, which may lead to earlier, safer and more efficient protection from osteoporosis-induced fractures in clinics. PMID:27329730

  16. Supplementing biomechanical modeling with EMG analysis

    Science.gov (United States)

    Lewandowski, Beth; Jagodnik, Kathleen; Crentsil, Lawton; Humphreys, Bradley; Funk, Justin; Gallo, Christopher; Thompson, William; DeWitt, John; Perusek, Gail

    2016-01-01

    It is well established that astronauts experience musculoskeletal deconditioning when exposed to microgravity environments for long periods of time. Spaceflight exercise is used to counteract these effects, and the Advanced Resistive Exercise Device (ARED) on the International Space Station (ISS) has been effective in minimizing musculoskeletal losses. However, the exercise devices of the new exploration vehicles will have requirements of limited mass, power and volume. Because of these limitations, there is a concern that the exercise devices will not be as effective as ARED in maintaining astronaut performance. Therefore, biomechanical modeling is being performed to provide insight on whether the small Multi-Purpose Crew Vehicle (MPCV) device, which utilizes a single-strap design, will provide sufficient physiological loading to maintain musculoskeletal performance. Electromyography (EMG) data are used to supplement the biomechanical model results and to explore differences in muscle activation patterns during exercises using different loading configurations.

  17. Single Cell Biomechanical Phenotyping using Microfluidics and Nanotechnology

    OpenAIRE

    Babahosseini, Hesam

    2016-01-01

    Cancer progression is accompanied with alterations in the cell biomechanical phenotype, including changes in cell structure, morphology, and responses to microenvironmental stress. These alterations result in an increased deformability of transformed cells and reduced resistance to mechanical stimuli, enabling motility and invasion. Therefore, single cell biomechanical properties could be served as a powerful label-free biomarker for effective characterization and early detection of single ca...

  18. 司坦唑醇对实验性骨质疏松大鼠骨密度和力学性能的影响%Effects of stanozolol on bone mineral density and bone biomechanical properties of osteoporotic rats

    Institute of Scientific and Technical Information of China (English)

    廖进民; 吴铁; 李青南; 胡彬; 黄连芳; 李忠华; 王原林; 钟世镇

    2003-01-01

    Objective To evaluate the effects of stanozolol on the bone mineral density (BMD) and bone biomechanical prop-erties of rats with glucocorticoid (GC)-induced osteoporosis (OP). Methods Twenty-eight male Sprague-Dawley rats of3-month old were randomly divided into Group A (the basal control group), Group B (the age-matched control group), GroupC (GC-induced OP group) and Group D (stanozolol-administtated group), 7 in each group. The rats in Group A were killedwhen experiment commenced, and those in Group B were given normal saline ig., while those in Groups C and D received theprednisone acetate (4.5 mg/kg, twice a week) alone and in combination with stanozolol (0.5 mg/kg, 6 times a week), respec-tively. Ninety days later, the bilateral femur and the 5th lumbar vertebra of the rats were isolated for BMD test using dual-en-ergy X-ray absorptiometry scanner, and the torsion test, three-point bending test and compression test using electronic testingdevice. Results Compared with Group B, the mean BMD of the femur and the 5th lumbar vertebra in Group C decreased by14.64% (P<0.01), the BMD of the bilateral distal femoral segment and the 5th lumbar vertebra decreased by 21.42% (P<0.01),19.62% (P<0.05) and 23.48% (P<0.01) respectively. The load that the femur withstood in three-point bending test decreasedby 17.1% (P<0.05), and the other biomechanical parameters also declined. When compared with Group C, the BMD in GroupD increased, the torsional angle of the femur increased by 72.5% (P<0.05) and the other biomechanical parameters also tendedto increase. Conclusions BMD and biomechanical properties of the rat femur and the 5th lumbar vertebra decrease in re-sponse to a long-term GC administration, which can be prevented by stanozolol.%目的:探讨司坦唑醇对糖皮质激素(GC)所致大鼠骨质疏松的骨密度和力学性能影响.方法28只3月龄雄性SD大鼠,体质量(226±12)g,随机等分为基础对照(A)组、年龄对照(B)组、

  19. Effect of SqVYV-resistant pollenizers on development and spread of watermelon vine decline in seedless watermelon

    Science.gov (United States)

    Watermelon vine decline (WVD) caused by the whitefly-transmitted Squash vein yellowing virus (SqVYV) has been a major limiting factor in watermelon (Citrullus lanatus) production in south Florida for the past several years. The disease causes sudden decline of the vines and affects the internal fru...

  20. The effects of ischemia with and without remote conditioning on hyperemia induced decline in carotid-radial pulse wave velocity.

    Science.gov (United States)

    Onegbu, Nwamaka; Kamran, Haroon; Sharma, Bhawna; Bapat, Manasi; Littman, Stephen; Warrier, Nikhil; Patel, Rinkesh; Khalid, Muhammad Tanweer; Salciccioli, Louis; Lazar, Jason M

    2012-01-01

    Ischemic conditioning has long held promise for preventing ischemic-reperfusion (I-R) injury. Although a number of studies have evaluated the effects of brief repeated episodes of ischemia before a prolonged ischemic episode on the cardiovascular system using clinical endpoints, more sensitive techniques by which to measure its effects are lacking. Since endothelial function is sensitive to I-R injury, flow mediated dilation of the brachial artery has been proposed for this purpose, but has significant limitations. Hyperemia normally decreases carotid to radial pulse wave velocity (PWV). Accordingly, we sought to determine the effects of I-R injury and ischemic conditioning on the hyperemic change (Δ) in PWV. We induced hyperemia by release of arterial cuff occlusion before and after ipsilateral arm I-R injury (7.5min occlusion) in 25 healthy males, age 29±6 years. The protocol was repeated on 2 occasions in combination with either pre- or post- conditioning stimuli (3× 30s contralateral arm occlusions). Hyperemia resulted in a significant decrease (-13.7%, pconditioning restored the PWV decline (pre: -11.0%, pconditioning restores this response. This technique may be useful for the assessment of novel treatment strategies and mechanisms underlying remote pre- and post-ischemic conditioning in protecting the cardiovascular system.

  1. Biomechanical conditions of walking

    CERN Document Server

    Fan, Y F; Luo, L P; Li, Z Y; Han, S Y; Lv, C S; Zhang, B

    2015-01-01

    The development of rehabilitation training program for lower limb injury does not usually include gait pattern design. This paper introduced a gait pattern design by using equations (conditions of walking). Following the requirements of reducing force to the injured side to avoid further injury, we developed a lower limb gait pattern to shorten the stride length so as to reduce walking speed, to delay the stance phase of the uninjured side and to reduce step length of the uninjured side. This gait pattern was then verified by the practice of a rehabilitation training of an Achilles tendon rupture patient, whose two-year rehabilitation training (with 24 tests) has proven that this pattern worked as intended. This indicates that rehabilitation training program for lower limb injury can rest on biomechanical conditions of walking based on experimental evidence.

  2. Effect of Extension and Type of Composite-Restored Class II Cavities on Biomechanical Properties of Teeth: A Three Dimensional Finite Element Analysis.

    Directory of Open Access Journals (Sweden)

    Azam Valian

    2015-04-01

    Full Text Available Controversy exists regarding cavity preparation for restoration of interproximal caries in posterior teeth in terms of preserving the tooth structure and suitable stress distribution. This study aimed to assess the effect of extension and type of class II cavities and the remaining tooth structure in maxillary premolars restored with composite resin on the biomechanical properties of teeth using finite element method (FEM.Using FEM, eight three-dimensional (3D models of class II cavities in maxillary premolars with variable mesiodistal (MD dimensions, variable thickness of the residual wall in-between the mesial and distal cavities and different locations of the wall were designed. Other dimensions were the same in all models. Cavities were restored with composite resin. A load equal to the masticatory force (200N was applied to the teeth. Finite element analysis (FEA was used to calculate the von Mises stress.Stress in the enamel margin increased by increasing the MD dimensions of the cavities. Deviation of the residual wall between the mesial and distal cavities from the tooth center was found to be an important factor in increasing stress concentration in the enamel. Increasing the MD dimensions of the cavity did not cause any increase in stress concentration in dentin.Increasing the MD dimensions of the cavities, decreasing the thickness of the residual wall between the mesial and distal cavities and its deviation from the tooth center can increase stress concentration in the enamel but not in dentin.

  3. Long-term decline in the calanoid copepod Acartia tonsa in central Chesapeake Bay, USA: An indirect effect of eutrophication?

    Science.gov (United States)

    Kimmel, David G.; Boynton, Walter R.; Roman, Michael R.

    2012-04-01

    A long-term abundance record of the calanoid copepod Acartia tonsa in the Maryland portion of Chesapeake Bay was compiled from 1966 to 2002. A significant downward trend in the summertime abundance of Acartia tonsa was found in central Chesapeake Bay. We propose that environmental and food web changes occurred as the Chesapeake Bay became increasingly impacted by human activity which eventually led to the overall decline of A. tonsa. Environmental changes included a long-term rise in water temperature and the volume of hypoxic water during the summer. These changes occurred during the same time period as increases in chlorophyll a concentration, declines in the landings of the eastern oyster Crassostrea virginica, and declines in abundance of the sea nettle Chrysaora quinquecirrha. A CUSUM analysis showed that each time-series experienced a change point during over the past 50 years. These changes occurred sequentially, with chlorophyll a concentration increasing beginning in 1969, water temperature and hypoxic volume increasing beginning in the early 1980s, more recent Maryland C. virginica landings begin declining in the early 1980s and A. tonsa and C. quinquecirrha declining starting in 1989. A stepwise regression analysis revealed that the reduction in A. tonsa abundance appeared to be most associated with a decreasing trend in C. quinquecirrha abundance, though only when trends in the two time-series were present. The drop in C. quinquecirrha abundance is associated with reduced predation on the ctenophore, Mnemiopsis leidyi, a key predator of A. tonsa. The long-term decline of A. tonsa has likely impacted trophic transfer to fish, particularly the zooplanktivorous bay anchovy (Anchoa mitchilli). A time-series of bay anchovy juvenile index showed a negative trend and the CUSUM analysis revealed 1993 as its starting point. Total fisheries landings, excluding menhaden (Brevoortia tyrannus), in Chesapeake Bay have also declined during the same period and this

  4. The Accommodative Function of Myosin on Cell Biomechanics Effect%肌球蛋白在生物力学效应中的调控作用

    Institute of Scientific and Technical Information of China (English)

    胡鸣(综述); 洪莉(审校)

    2015-01-01

    Cytoskeleton is a component of mechanical force transmission chain .As the main protein in forming cytoskeleton in cells, myosin plays a role in regulating the effect produced by cells when they are forced by the external force.When the expression, structure and activity of myosin changes, mechanical effi-ciency of cells will have a corresponding change, thus affecting the cell function and organizational structure. Phosphorylated myosin light chain, transformation of subtypes in myosin heavy chain , and Rho GTPases sig-naling pathway play an important role in the regulation of cellular biological effects .In this article, we try to express the advanced research in myosin′s impact on cell biomechanics effect.In addition, we also discuss the generation mechanism of such effects.%细胞骨架是细胞内机械力传递链的一个组分,肌球蛋白作为细胞骨架的主要组成蛋白,对细胞受到外界力作用时产生的效应具有一定的调控作用,当细胞内的肌球蛋白的表达、结构以及活性发生改变时,细胞的力学效能也会发生相应的改变,从而影响细胞的功能以及组织结构的改变。肌球蛋白轻链的磷酸化、重链各亚型间的转化以及Rho GTP酶信号通路在对细胞生物力学效应的调控中起着一定的作用。

  5. 肌球蛋白在生物力学效应中的调控作用%The Accommodative Function of Myosin on Cell Biomechanics Effect

    Institute of Scientific and Technical Information of China (English)

    胡鸣(综述); 洪莉(审校)

    2015-01-01

    细胞骨架是细胞内机械力传递链的一个组分,肌球蛋白作为细胞骨架的主要组成蛋白,对细胞受到外界力作用时产生的效应具有一定的调控作用,当细胞内的肌球蛋白的表达、结构以及活性发生改变时,细胞的力学效能也会发生相应的改变,从而影响细胞的功能以及组织结构的改变。肌球蛋白轻链的磷酸化、重链各亚型间的转化以及Rho GTP酶信号通路在对细胞生物力学效应的调控中起着一定的作用。%Cytoskeleton is a component of mechanical force transmission chain .As the main protein in forming cytoskeleton in cells, myosin plays a role in regulating the effect produced by cells when they are forced by the external force.When the expression, structure and activity of myosin changes, mechanical effi-ciency of cells will have a corresponding change, thus affecting the cell function and organizational structure. Phosphorylated myosin light chain, transformation of subtypes in myosin heavy chain , and Rho GTPases sig-naling pathway play an important role in the regulation of cellular biological effects .In this article, we try to express the advanced research in myosin′s impact on cell biomechanics effect.In addition, we also discuss the generation mechanism of such effects.

  6. Effects of climate warming and declining species richness in grassland model ecosystems: acclimation of CO2 fluxes

    Directory of Open Access Journals (Sweden)

    S. Vicca

    2007-01-01

    Full Text Available To study the effects of warming and declining species richness on the carbon balance of grassland communities, model ecosystems containing one, three or nine species were exposed to ambient and elevated (ambient +3°C air temperature. In this paper, we analyze measured ecosystem CO2 fluxes to test whether ecosystem photosynthesis and respiration had acclimated to warming after 28 months of continuous heating, and whether the degree of acclimation depended on species richness. In order to test whether acclimation occurred, short term temperature response curves were established for all communities in both treatments. At similar temperatures, lower flux rates in the heated communities as compared to the unheated communities would indicate thermal acclimation. Because plant cover was significantly higher in the heated treatment, we normalized the data for plant cover. Subsequently, down-regulation of both photosynthesis and respiration was observed. Although CO2 fluxes were larger in communities with higher species richness, species richness did not affect the degree of acclimation to warming. These results imply that models need to take thermal acclimation into account to simulate photosynthesis and respiration in a warmer world.

  7. Energetics, Biomechanics, and Performance in Masters' Swimmers: A Systematic Review.

    Science.gov (United States)

    Ferreira, Maria I; Barbosa, Tiago M; Costa, Mário J; Neiva, Henrique P; Marinho, Daniel A

    2016-07-01

    Ferreira, MI, Barbosa, TM, Costa, MJ, Neiva, HP, and Marinho, DA. Energetics, biomechanics, and performance in masters' swimmers: a systematic review. J Strength Cond Res 30(7): 2069-2081, 2016-This study aimed to summarize evidence on masters' swimmers energetics, biomechanics, and performance gathered in selected studies. An expanded search was conducted on 6 databases, conference proceedings, and department files. Fifteen studies were selected for further analysis. A qualitative evaluation of the studies based on the Quality Index (QI) was performed by 2 independent reviewers. The studies were thereafter classified into 3 domains according to the reported data: performance (10 studies), energetics (4 studies), and biomechanics (6 studies). The selected 15 articles included in this review presented low QI scores (mean score, 10.47 points). The biomechanics domain obtained higher QI (11.5 points), followed by energetics and performance (10.6 and 9.9 points, respectively). Stroke frequency (SF) and stroke length (SL) were both influenced by aging, although SF is more affected than SL. Propelling efficiency (ηp) decreased with age. Swimming performance declined with age. The performance declines with age having male swimmers deliver better performances than female counterparts, although this difference tends to be narrow in long-distance events. One single longitudinal study is found in the literature reporting the changes in performance over time. The remaining studies are cross-sectional designs focusing on the energetics and biomechanics. Overall, biomechanics parameters, such as SF, SL, and ηp, tend to decrease with age. This review shows the lack of a solid body of knowledge (reflected in the amount and quality of the articles published) on the changes in biomechanics, energetics, and performance of master swimmers over time. The training programs for this age-group should aim to preserve the energetics as much as possible and, concurrently, improve the

  8. Energetics, Biomechanics, and Performance in Masters' Swimmers: A Systematic Review.

    Science.gov (United States)

    Ferreira, Maria I; Barbosa, Tiago M; Costa, Mário J; Neiva, Henrique P; Marinho, Daniel A

    2016-07-01

    Ferreira, MI, Barbosa, TM, Costa, MJ, Neiva, HP, and Marinho, DA. Energetics, biomechanics, and performance in masters' swimmers: a systematic review. J Strength Cond Res 30(7): 2069-2081, 2016-This study aimed to summarize evidence on masters' swimmers energetics, biomechanics, and performance gathered in selected studies. An expanded search was conducted on 6 databases, conference proceedings, and department files. Fifteen studies were selected for further analysis. A qualitative evaluation of the studies based on the Quality Index (QI) was performed by 2 independent reviewers. The studies were thereafter classified into 3 domains according to the reported data: performance (10 studies), energetics (4 studies), and biomechanics (6 studies). The selected 15 articles included in this review presented low QI scores (mean score, 10.47 points). The biomechanics domain obtained higher QI (11.5 points), followed by energetics and performance (10.6 and 9.9 points, respectively). Stroke frequency (SF) and stroke length (SL) were both influenced by aging, although SF is more affected than SL. Propelling efficiency (ηp) decreased with age. Swimming performance declined with age. The performance declines with age having male swimmers deliver better performances than female counterparts, although this difference tends to be narrow in long-distance events. One single longitudinal study is found in the literature reporting the changes in performance over time. The remaining studies are cross-sectional designs focusing on the energetics and biomechanics. Overall, biomechanics parameters, such as SF, SL, and ηp, tend to decrease with age. This review shows the lack of a solid body of knowledge (reflected in the amount and quality of the articles published) on the changes in biomechanics, energetics, and performance of master swimmers over time. The training programs for this age-group should aim to preserve the energetics as much as possible and, concurrently, improve the

  9. Biomechanics of whiplash injury

    Institute of Scientific and Technical Information of China (English)

    CHEN Hai-bin; King H YANG; WANG Zheng-guo

    2009-01-01

    Despite a large number of rear-end collisions on the road and a high frequency of whiplash injuries reported, the mechanism of whiplash injuries is not completely understood. One of the reasons is that the injury is not necessarily accompanied by obvious tissue damage detectable by X-ray or MRI. An extensive series of biomechanics studies, including injury epidemiology, neck kinematics,facet capsule ligament mechanics, injury mechanisms and injury criteria, were undertaken to help elucidate these whiplash injury mechanisms and gain a better understanding of cervical facet pain. These studies provide the following evidences to help explain the mechanisms of the whiplash injury: (1) Whiplash injuries are generally considered to be a soft tissue injury of the neck with symptoms such as neck pain and stiffness, shoulder weakness, dizziness, headache and memory loss, etc. (2) Based on kinematical studies on the cadaver and volunteers, there are three distinct periods that have the potential to cause injury to the neck. In the first stage, flexural deformation of the neck is observed along with a loss of cervical lordosis; in the second stage, the cervical spine assumes an S-shaped curve as the lower vertebrae begin to extend and gradually cause the upper vertebrae to extend; during the final stage, the entire neck is extended due to the extension moments at both ends. (3)The in vivo environment afforded by rodent models of injury offers particular utility for linking mechanics, nociception and behavioral outcomes. Experimental findings have examined strains across the facet joint as a mechanism of whiplash injury, and suggested a capsular strain threshold or a vertebral distraction threshold for whiplash-related injury,potentially producing neck pain. (4) Injuries to the facet capsule region of the neck are a major source of post-crash pain. There are several hypotheses on how whiplash-associated injury may occur and three of these injuries are related to strains within

  10. Effect of pharmacotherapy on rate of decline of lung function in chronic obstructive pulmonary disease: results from the TORCH study

    DEFF Research Database (Denmark)

    Celli, Bartolomé R; Thomas, Nicola E; Anderson, Julie A;

    2008-01-01

    of combined salmeterol 50 microg plus fluticasone propionate 500 microg, either component alone or placebo, on the rate of post-bronchodilator FEV(1) decline in patients with moderate or severe COPD. METHODS: A randomized, double-blind, placebo-controlled study was conducted from September 2000 to November...... 2005 in 42 countries. Of 6,112 patients from the efficacy population, 5,343 were included in this analysis. MEASUREMENTS AND MAIN RESULTS: Spirometry was measured every 24 weeks for 3 years. There were 26,539 on-treatment observations. The adjusted rate of decline in FEV(1) was 55 ml/year for placebo......, 42 ml/year for salmeterol, 42 ml/year for fluticasone propionate, and 39 ml/year for salmeterol plus fluticasone propionate. Salmeterol plus fluticasone propionate reduced the rate of FEV(1) decline by 16 ml/year compared with placebo (95% confidence interval [CI], 7-25; P

  11. Judo Biomechanical Optimization

    CERN Document Server

    Sacripanti, Attilio

    2016-01-01

    In this paper, for the first time, there is comprehensively tackling the problem of biomechanical optimization of a sport of situation such as judo. Starting from the optimization of more simple sports, optimization of this kind of complex sports is grounded on a general physics tool such as the analysis of variation. The objective function is divided for static and dynamic situation of Athletes couple, and it is proposed also a sort of dynamic programming problem Strategic Optimization. A dynamic programming problem is an optimization problem in which decisions have to be taken sequentially over several time periods linked in some fashion. A strategy for a dynamic programming problem is just a contingency plan, a plan that specifies what is to be done at each stage as a function of all that has transpired up to that point. It is possible to demonstrate, under some conditions, that a Markovian optimal strategy is an optimal strategy for the dynamic programming problem under examination. At last we try to appr...

  12. Pulse Pressure Is Associated With Early Brain Atrophy and Cognitive Decline: Modifying Effects of APOE-ε4.

    Science.gov (United States)

    Nation, Daniel A; Preis, Sarah R; Beiser, Alexa; Bangen, Katherine J; Delano-Wood, Lisa; Lamar, Melissa; Libon, David J; Seshadri, Sudha; Wolf, Philip A; Au, Rhoda

    2016-01-01

    We investigated whether midlife pulse pressure is associated with brain atrophy and cognitive decline, and whether the association was modified by apolipoprotein-E ε4 (APOE-ε4) and hypertension. Participants (549 stroke-free and dementia-free Framingham Offspring Cohort Study participants, age range=55.0 to 64.9 y) underwent baseline neuropsychological and magnetic resonance imaging (subset, n=454) evaluations with 5- to 7-year follow-up. Regression analyses investigated associations between baseline pulse pressure (systolic-diastolic pressure) and cognition, total cerebral volume and temporal horn ventricular volume (as an index of smaller hippocampal volume) at follow-up, and longitudinal change in these measures. Interactions with APOE-ε4 and hypertension were assessed. Covariates included age, sex, education, assessment interval, and interim stroke. In the total sample, baseline pulse pressure was associated with worse executive ability, lower total cerebral volume, and greater temporal horn ventricular volume 5 to 7 years later, and longitudinal decline in executive ability and increase in temporal horn ventricular volume. Among APOE-ε4 carriers only, baseline pulse pressure was associated with longitudinal decline in visuospatial organization. Findings indicate arterial stiffening, indexed by pulse pressure, may play a role in early cognitive decline and brain atrophy in mid to late life, particularly among APOE-ε4 carriers. PMID:27556935

  13. Addressing the Declining Productivity of Higher Education Using Cost-Effectiveness Analysis. Stretching the Higher Education Dollar. Special Report 2

    Science.gov (United States)

    Harris, Douglas N.

    2013-01-01

    Higher education productivity, as measured by academic degrees granted by American colleges and universities, is declining. Since the early 1990s, real expenditures on higher education have grown by more than 25 percent, now amounting to 2.9 percent of US gross domestic product (GDP)--greater than the percentage of GDP spent on higher education in…

  14. The Decline of Academic Motivation during Adolescence: An Accelerated Longitudinal Cohort Analysis on the Effect of Psychological Need Satisfaction

    Science.gov (United States)

    Gnambs, Timo; Hanfstingl, Barbara

    2016-01-01

    Adolescents typically exhibit a marked decline in academic intrinsic motivation throughout their school careers. Following self-determination theory, it is hypothesised that traditional school environments insufficiently satisfy three basic psychological needs of youths during maturation, namely the needs for autonomy, competence and relatedness.…

  15. [Hoarseness: biomechanisms and quantitative laryngoscopy].

    Science.gov (United States)

    Eysholdt, U

    2014-07-01

    Every phonosurgical procedure alters endolaryngeal anatomy; be it by removing tissue, or injection or implantation of autologous or foreign material. However, the effect that an altered airflow cross section and changed soft tissue elasticity will have on the voice cannot be predicted. With the aim of promoting rational indications for phonosurgery, the current article explains the biomechanisms of the normal and the disordered voice, including the complex interdependence of tissue viscoelasticity, glottal airstream and sound production. According to European Laryngological Society (ELS) recommendations, five - not entirely mutually independent - evaluation criteria form the basis of indication assessments: self-rating (by the patient), proxy rating (by the physician), technical signal analysis (computerized), aerodynamics (spirometry) and vibration analysis (stroboscopy). The ELS evaluation standards agreed upon in 2001 enable indications and - by virtue of pre- and postoperative comparisons - therapeutic successes to be assessed. The 10-year-old ELS protocol has been updated by a real-time method for visualizing vocal fold vibrations: the phonovibrogram (PVG) has replaced stroboscopy. Independently of the morphological anatomic details of the larynx, PVG visualizes the symmetry and regularity of vocal fold motion, thus allowing preoperative estimation of tissue elasticity. PMID:25056650

  16. Kinesiology/Biomechanics: Perspectives and Trends.

    Science.gov (United States)

    Atwater, Anne E.

    1980-01-01

    Past and recent developments and future directions in kinesiology and biomechanics are reviewed. Similarities and differences between these two areas are clarified. The areas of kinesiology and biomechanics have distinct unique qualities and should be treated as separate disciplines. (CJ)

  17. The effect of three-dimensional geometrical changes during adolescent growth on the biomechanics of a spinal motion segment

    NARCIS (Netherlands)

    Homminga, J.; Hekman, E. E. G.; Veldhuizen, A. G.; Verkerke, G. J.; Meijer, G.

    2010-01-01

    During adolescent growth, vertebrae and intervertebral discs undergo various geometrical changes. Although such changes in geometry are well known, their effects on spinal stiffness remains poorly understood. However, this understanding is essential in the treatment of spinal abnormalities during gr

  18. Declining caries trends: are we satisfied?

    NARCIS (Netherlands)

    M.D. Lagerweij; C. van Loveren

    2015-01-01

    WHO data suggest that all over the world the prevalence of caries has declined at the end of the previous and in the first decade of the present century. This decline started wherever the use of effective fluoride toothpaste became commonplace. Even though the decline is considerable with a 90 % red

  19. Problems of Sport Biomechanics and Robotics

    OpenAIRE

    Erdmann, Wlodzimierz S.

    2013-01-01

    This paper presents many common areas of interest of different specialists. There are problems described from sport, biomechanics, sport biomechanics, sport engineering, robotics, biomechanics and robotics, sport biomechanics and robotics. There are many approaches to sport from different sciences and engineering. Robotics is a relatively new area and has had moderate attention from sport specialists. The aim of this paper is to present several areas necessary to develop sport robots based on...

  20. Individual differences in the biomechanical effect of loudness and tempo on upper-limb movements during repetitive piano keystrokes.

    Science.gov (United States)

    Furuya, Shinichi; Aoki, Tomoko; Nakahara, Hidehiro; Kinoshita, Hiroshi

    2012-02-01

    The present study addressed the effect of loudness and tempo on kinematics and muscular activities of the upper extremity during repetitive piano keystrokes. Eighteen pianists with professional music education struck two keys simultaneously and repetitively with a combination of four loudness levels and four tempi. The results demonstrated a significant interaction effect of loudness and tempo on peak angular velocity for the shoulder, elbow, wrist and finger joints, mean muscular activity for the corresponding flexors and extensors, and their co-activation level. The interaction effect indicated greater increases with tempo when eliciting louder tones for all joints and muscles except for the elbow velocity showing a greater decrease with tempo. Multiple-regression analysis and K-means clustering further revealed that 18 pianists were categorized into three clusters with different interaction effects on joint kinematics. These clusters were characterized by either an elbow-velocity decrease and a finger-velocity increase, a finger-velocity decrease with increases in shoulder and wrist velocities, or a large elbow-velocity decrease with a shoulder-velocity increase when increasing both loudness and tempo. Furthermore, the muscular load considerably differed across the clusters. These findings provide information to determine muscles with the greatest potential risk of playing-related disorders based on movement characteristics of individual pianists. PMID:21816497

  1. Foraging Habitat Quality Constrains Effectiveness of Artificial Nest-Site Provisioning in Reversing Population Declines in a Colonial Cavity Nester

    Science.gov (United States)

    Catry, Inês; Franco, Aldina M. A.; Rocha, Pedro; Alcazar, Rita; Reis, Susana; Cordeiro, Ana; Ventim, Rita; Teodósio, Joaquim; Moreira, Francisco

    2013-01-01

    Among birds, breeding numbers are mainly limited by two resources of major importance: food supply and nest-site availability. Here, we investigated how differences in land-use and nest-site availability affected the foraging behaviour, breeding success and population trends of the colonial cavity-dependent lesser kestrel Falco naumanni inhabiting two protected areas. Both areas were provided with artificial nests to increase nest-site availability. The first area is a pseudo-steppe characterized by traditional extensive cereal cultivation, whereas the second area is a previous agricultural zone now abandoned or replaced by forested areas. In both areas, lesser kestrels selected extensive agricultural habitats, such as fallows and cereal fields, and avoided scrubland and forests. In the second area, tracked birds from one colony travelled significantly farther distances (6.2 km ±1.7 vs. 1.8 km ±0.4 and 1.9 km ±0.6) and had significant larger foraging-ranges (144 km2 vs. 18.8 and 14.8 km2) when compared to the birds of two colonies in the extensive agricultural area. Longer foraging trips were reflected in lower chick feeding rates, lower fledging success and reduced chick fitness. Availability and occupation of artificial nests was high in both areas but population followed opposite trends, with a positive increment recorded exclusively in the first area with a large proportion of agricultural areas. Progressive habitat loss around the studied colony in the second area (suitable habitat decreased from 32% in 1990 to only 7% in 2002) is likely the main driver of the recorded population decline and suggests that the effectiveness of bird species conservation based on nest-site provisioning is highly constrained by habitat quality in the surrounding areas. Therefore, the conservation of cavity-dependent species may be enhanced firstly by finding the best areas of remaining habitat and secondly by increasing the carrying capacity of high-quality habitat areas

  2. Effect of dominant ground vegetation on soil organic matter quality in a declining mountain spruce forest of central Europe

    Energy Technology Data Exchange (ETDEWEB)

    Bonifacio, E.; Santoni, S.; Zanini, E. (Universita degli Studi di Torino (Italy)); Cudlin, P. (Inst. of Systems Biology and Ecology, Czech Academy of Sciences (Czech Republic))

    2008-07-01

    Grasses and shrubs constitute a high proportion of the total biomass in declining forest stands and may deeply affect soil organic matter. We fractionated the organic matter of 45 Oa horizons from the Krkonose Mts. into humic and fulvic acids (HA and FA) and related the differences to the dominant ground vegetation Vaccinium myrtillus, Deschampsia flexuosa and Molinia caerulea. Organic C was higher under M. caerulea than under Vaccinium myrtillus, but the humification rate was similar at all sites. A higher proportion of HA was found under M. caerulea, indicating that differences in species lead to variations in the quality of humic substances, but not in the quantitative aspects of the humification process. Regarding the importance of HA and FA in soil development, the findings suggest that, upon forest decline, major changes may be expected not only in the O horizons, but also in the whole soil profile. (orig.)

  3. Gender bias in China, the Republic of Korea, and India 1920-90 - effects of war, famine, and fertility decline

    OpenAIRE

    Das Gupta, Monica; Li Shuzhuo

    1999-01-01

    Kinship systems in China, the Republic of Korea, and North India have similar features that generate discrimination against girls, and these countries have some of the highest proportions of girls"missing"in the world. The authors document how the excess mortality of girls was increased by war, famine, and fertility decline - all of which constrained household resources - between 1920 and 1990. Of the three countries, China experienced the most crises during this period (with civil war, invas...

  4. Who fears and who welcomes population decline?

    Directory of Open Access Journals (Sweden)

    Hendrik P. Van Dalen

    2011-08-01

    Full Text Available European countries are experiencing population decline and the tacit assumption in most analyses is that the decline may have detrimental welfare effects. In this paper we use a survey among the population in the Netherlands to discover whether population decline is always met with fear. A number of results stand out: population size preferences differ by geographic proximity: at a global level the majority of respondents favors a (global population decline, but closer to home one supports a stationary population. Population decline is clearly not always met with fear: 31 percent would like the population to decline at the national level and they generally perceive decline to be accompanied by immaterial welfare gains (improvement environment as well as material welfare losses (tax increases, economic stagnation. In addition to these driving forces it appears that the attitude towards immigrants is a very strong determinant at all geographical levels: immigrants seem to be a stronger fear factor than population decline.

  5. Biomechanics for inclusive urban design: Effects of tactile paving on older adults' gait when crossing the street.

    Science.gov (United States)

    Thies, S B; Kenney, L P J; Howard, D; Nester, C; Ormerod, M; Newton, R; Baker, R; Faruk, M; MacLennan, H

    2011-05-17

    In light of our ageing population it is important that the urban environment is easily accessible and hence supports older adults' independence. Tactile 'blister' paving was originally designed to provide guidance for visually impaired people at pedestrian crossings. However, as research links irregular surfaces to falls in older adults, such paving may have an adverse effect on older people. We investigated the effects of tactile paving on older adults' gait in a scenario closely resembling crossing the street. Gait analysis of 32 healthy older adults showed that tactile, as compared to smooth, paving increases the variability in timing of foot placement by 20%, thereby indicating a disturbance of the rhythmic gait pattern. Moreover, toe clearance during the swing phase increased by 7% on tactile paving, and the ability to stop upon cue from the traffic light was compromised. These results need to be viewed under the consideration of limitations associated with laboratory studies and real world analysis is needed to fully understand their implications for urban design.

  6. A Biomechanical Comparison of Expansive Pedicle Screws for Severe Osteoporosis: The Effects of Screw Design and Cement Augmentation.

    Science.gov (United States)

    Tai, Ching-Lung; Tsai, Tsung-Ting; Lai, Po-Liang; Chen, Yi-Lu; Liu, Mu-Yi; Chen, Lih-Huei

    2015-01-01

    Expansive pedicle screws significantly improve fixation strength in osteoporotic spines. However, the previous literature does not adequately address the effects of the number of lengthwise slits and the extent of screw expansion on the strength of the bone/screw interface when expansive screws are used with or without cement augmentation. Herein, four designs for expansive pedicle screws with different numbers of lengthwise slits and different screw expansion levels were evaluated. Synthetic bones simulating severe osteoporosis were used to provide a comparative platform for each screw design. The prepared specimens were then tested for axial pullout failure. Regardless of screw design, screws with cement augmentation demonstrated significantly higher pullout strength than pedicle screws without cement augmentation (p screws without cement augmentation, solid screws exhibited the lowest pullout strength compared to the four expansive groups (p screws with different designs (p > 0.05). Taken together, our results show that pedicle screws combined with cement augmentation may greatly increase screw fixation regardless of screws with or without expansion. An increase in both the number of slits and the extent of screw expansion had little impact on the screw-anchoring strength. Cement augmentation is the most influential factor for improving screw pullout strength. PMID:26720724

  7. A Biomechanical Comparison of Expansive Pedicle Screws for Severe Osteoporosis: The Effects of Screw Design and Cement Augmentation.

    Directory of Open Access Journals (Sweden)

    Ching-Lung Tai

    Full Text Available Expansive pedicle screws significantly improve fixation strength in osteoporotic spines. However, the previous literature does not adequately address the effects of the number of lengthwise slits and the extent of screw expansion on the strength of the bone/screw interface when expansive screws are used with or without cement augmentation. Herein, four designs for expansive pedicle screws with different numbers of lengthwise slits and different screw expansion levels were evaluated. Synthetic bones simulating severe osteoporosis were used to provide a comparative platform for each screw design. The prepared specimens were then tested for axial pullout failure. Regardless of screw design, screws with cement augmentation demonstrated significantly higher pullout strength than pedicle screws without cement augmentation (p 0.05. Taken together, our results show that pedicle screws combined with cement augmentation may greatly increase screw fixation regardless of screws with or without expansion. An increase in both the number of slits and the extent of screw expansion had little impact on the screw-anchoring strength. Cement augmentation is the most influential factor for improving screw pullout strength.

  8. The effect of wind exposure on the tree aerial architecture and biomechanics of Sitka spruce (Picea sitchensis, Pinaceae).

    Science.gov (United States)

    Brüchert, Franka; Gardiner, Barry

    2006-10-01

    This paper reports on the effect of wind loading below damaging strength on tree mechanical and physical properties. In a wind-exposed Sitka spruce stand in western Scotland, 60 trees at four different levels of wind exposure (10 m, 30 m, 50 m, 90 m from edge) were characterized for stem and crown size and shape and mechanical properties, including structural Young's modulus (E(struct)), natural frequency, and damping ratio. E(struct) increased from the stand edge to the mid-forest, but with a large inter-tree variation. Swaying frequency and damping ratio of the trees also increased with distance from edge. Wind-exposed edge trees grew shorter, but more tapered with an overall lower E(struct), allowing for greater flexural stiffness at the stem base due to the larger diameter and for higher flexibility in the crown region of the stem. The trees at the middle of the stand compensated for their increased slenderness with a higher E(struct). Thus, for the different requirements for wind-firmness at stand edge and mid-forest, an adapted combination of tree form and mechanical properties allows the best withstanding of wind loads. The results show the requirement to understand the different strategies of trees to adapt to environmental constraints and the heterogeneity of their growth reactions in response to these strategies.

  9. A Comparative Study on the Kinematic Biomechanical Effects of Tibia Vara in the Healthy and Diseased Individuals

    Science.gov (United States)

    Shahmohammadi, Mehrdad; Karami, Hossein; Bani, Milad Salimi; Zadeh, Hossein Bahreini; Karimi, Alireza; Navidbakhsh, Mahdi

    2016-08-01

    BACKGROUND: Malalignment about the knee leads to a pathological-mechanical load that may cause early osteoarthritis of the knee joint and high degree of deformity which may need surgical treatment. Analysis of the leg movements in the experimental cases and comparing acquired results to the normal ones during the gait is used as a practical method to evaluate the effects of the disease. METHOD: In this study, gait differences between the patients with tibia vara and normal people were studied according to the data obtained from a three-dimensional (3D) motion analyzer. Various parameters, including positions, linear and angular velocities, linear and angular accelerations, total velocity, total acceleration, and path length at different angels were extracted and processed via a 3D motion analyzer. Then the results of the patient and control groups were compared to identify the differences. RESULTS: The maximum and average values as well as sample entropy were also calculated for all the mentioned parameters. Among all, only nine remarkable differences between these two groups were observed. The results revealed that the great difference between the patients with tibia vara compared to the normal ones in gait cycle lies on the abnormal movement of fibula bone and less irregularities along the z-axis. CONCLUSIONS: These findings may have implications not only for understanding the differences between the tibia vara in the healthy and diseased individuals, but also for providing a practical understanding for the medical and orthopedic experts to propose a better treatment method.

  10. Distributed Data Acquisition For Biomechanics Research

    Science.gov (United States)

    Myklebust, J.; Geisler, M.; Prieto, T.; Weiss, R.

    1987-01-01

    Biomechanics research at the Medical College of Wisconsin is directed to the determination of the mechanisms of head and spine injury and the evaluation of surgical treatments for these injuries. This work involves mechanical testing of components of the spine (disks, vertebral bodies, and ligaments) as well as testing of composite spines and in situ evaluation of intact human cadavers (1,3). Other studies utilize experimental animals to measure neurologic and physiologic effects due to injury producing loads and accelerations (2). An integrated system has been developed to facilitate the acquisition and analysis of the diverse types of data from these experiments.

  11. Effects of methionine restriction and endurance exercise on bones of ovariectomized rats: a study of histomorphometry, densitometry, and biomechanical properties.

    Science.gov (United States)

    Huang, Tsang-Hai; Su, I-Hsiu; Lewis, Jack L; Chang, Ming-Shi; Hsu, Ar-Tyan; Perrone, Carmen E; Ables, Gene P

    2015-09-01

    To investigate the effects of dietary methionine restriction (MetR) and endurance exercise on bone quality under a condition of estrogen deficiency, female Sprague-Dawley rats (36-wk-old) were assigned to a sham surgery group or one of five ovariectomized groups subjected to interventions of no treatment (Ovx), endurance exercise (Exe), methionine restriction (MetR), methionine restriction plus endurance exercise (MetR + Exe), and estrogen treatment (Est). Rats in the exercise groups were subjected to a treadmill running regimen. MetR and control diets contained 0.172 and 0.86% methionine, respectively. After the 12-wk intervention, all animals were killed, and serum and bone tissues were collected for analyses. Compared with estrogen treatment, MetR diet and endurance exercise showed better or equivalent efficiency in reducing body weight gain caused by ovariectomy (P < 0.05). Whereas only the Est group showed evidence for reduced bone turnover compared with the Ovx group, MetR diet and/or endurance exercise demonstrated efficiencies in downregulating serum insulin, leptin, triglyceride, and thiobarbituric acid reactive substances (P < 0.05). Both the Exe and MetR groups showed higher femoral cortical and total volumetric bone mineral density (vBMD), but only the Exe and Est groups preserved cancellous bone volume and/or vBMD of distal femora (P < 0.05) compared with the Ovx group. After being normalized to body mass, femora of the MetR and MetR + Exe groups had relatively higher bending strength and dimension values followed by the Sham, Exe, and Est groups (P < 0.05). In conclusion, both MetR diet and endurance exercise improved cortical bone properties, but only endurance exercise preserved cancellous bone under estrogen deficiency.

  12. Effect of anterior cruciate ligament reconstruction on biomechanical features of knee in level walking: a meta-analysis

    Institute of Scientific and Technical Information of China (English)

    SHI Dong-liang; WANG Yu-bin; AI Zi-sheng

    2010-01-01

    Background The anterior cruciate ligament (ACL) is one of the most commonly injured knee ligaments. Even following ACL reconstruction, significant articular cartilage degeneration can be observed and most patients suffer from premature osteoarthritis. Articular cartilage degeneration and osteoarthritis development after ACL injury are regarded as progressive process that are affected by cyclic loading during frequently performed low-intensity daily activities. The purpose of this study was to perform a meta analysis on studies assessing the effects of ACL reconstruction on kinematics, kinetics and proprioception of knee during level walking.Methods This meta analysis was conducted according to the methodological guidelines outlined by the Cochrane Collaboration. An electronic search of the literature was performed and all trials published between January 1966 and July 2010 comparing gait and proprioception of a reconstructed-ACL group with an intact-ACL group were pooled for this review. Thirteen studies were included in the final meta analysis.Results There was no significant difference in step length, walking speed, maximum knee flexion angle during loading response, joint position sense and threshold to detect passive motion between the reconstructed-ACL group and the intact-ACL group (P >0.05). However, there was a significant difference in peak knee flexion angle, maximum angular knee flexion excursion during stance, peak knee flexion moment during walking and maximum external tibial rotation angle throughout the gait cycle between the reconstructed-ACL group and the intact-ACL group (P <0.05).Conclusions Step length, walking speed, maximum knee flexion angle during loading response, joint position sense and threshold to detect passive motion usually observed with ACL deficiency were restored after the ACL reconstruction and rehabilitation, but no significant improvements were observed for peak knee flexion angle, maximum angular knee flexion excursion

  13. Biomechanical risk factors of non-contact ACL injuries:A stochastic biomechanical modeling study

    Institute of Scientific and Technical Information of China (English)

    Cheng-Feng; Lin; Hui; Liu; Michael; T.Gros; Paul; Weinhold; William; E.Garrett; Bing; Yu

    2012-01-01

    <正>Background:Significant efforts have been made to identify modifiable risk factors of non-contact anterior cruciate ligament(ACL) injuries in male and female athletes.However,current literature on the risk factors for ACL injury are purely descriptive.An understanding of biomechanical relationship between risk and risk factors of the non-contact ACL injury is necessary to develop effective prevention programs. Purpose:To compare lower extremity kinematics and kinetics between trials with and without non-contact ACL injuries and to determine if any difference exists between male and female trials with non-contact ACL injuries regarding the lower extremity motion patterns. Methods:In this computer simulation study,a stochastic biomechanical model was used to estimate the ACL loading at the time of peak posterior ground reaction force(GRF) during landing of the stop-jump task.Monte Carlo simulations were performed to simulate the ACL injuries with repeated random samples of independent variables.The distributions of independent variables were determined from in vivo laboratory data of 40 male and 40 female recreational athletes. Results:In the simulated injured trials,both male and female athletes had significantly smaller knee flexion angles,greater normalized peak posterior and vertical GRF.greater knee valgus moment,greater patella tendon force,greater quadriceps force,greater knee extension moment. and greater proximal tibia anterior shear force in comparison to the simulated uninjured trials.No significant difference was found between genders in any of the selected biomechanical variables in the trials with simulated non-contact ACL injuries. Conclusion:Small knee flexion angle,large posterior GRF.and large knee valgus moment are risk factors of non-contact ACL injury determined by a stochastic biomechanical model with a cause-and-effect relationship.

  14. Clinical applications of biomechanics cinematography.

    Science.gov (United States)

    Woodle, A S

    1986-10-01

    Biomechanics cinematography is the analysis of movement of living organisms through the use of cameras, image projection systems, electronic digitizers, and computers. This article is a comparison of cinematographic systems and details practical uses of the modality in research and education. PMID:2946390

  15. Biomechanical analysis technique choreographic movements (for example, "grand battman jete"

    Directory of Open Access Journals (Sweden)

    Batieieva N.P.

    2015-04-01

    Full Text Available Purpose : biomechanical analysis of the execution of choreographic movement "grand battman jete". Material : the study involved students (n = 7 of the department of classical choreography faculty of choreography. Results : biomechanical analysis of choreographic movement "grand battman jete" (classic exercise, obtained kinematic characteristics (path, velocity, acceleration, force of the center of mass (CM bio parts of the body artist (foot, shin, thigh. Built bio kinematic model (phase. The energy characteristics - mechanical work and kinetic energy units legs when performing choreographic movement "grand battman jete". Conclusions : It was found that the ability of an athlete and coach-choreographer analyze the biomechanics of movement has a positive effect on the improvement of choreographic training of qualified athletes in gymnastics (sport, art, figure skating and dance sports.

  16. Biomechanics of Kuzushi-Tsukuri and Interaction in Competition

    CERN Document Server

    Sacripanti, Attilio

    2010-01-01

    In this paper it is performed the comparative biomechanical analysis of the Kuzushi (Unbalance) -Tsukuri (the entry and proper fitting of Tori's body into the position taken just before throwing) phases of Judo Throwing techniques. The whole effective movement is without separation, as already stated by old Japanese biomechanical studies (1972 -1978), only one skilled connected action, but the biomechanical analysis is able to separate the whole in didactic steps called Action Invariants. The first important finding singled out is the existence of two classes of Action Invariants the first the General one' connected to the whole body motion is specific of shortening distance in the Kuzushi Tsukuri Phase. The second one, the Specific Action Invariants is connected to the superior and inferior kinetic chains motion and right positioning connected both to Kuzushi and Tsukuri phases. Some interesting findings derive from this analysis: among throwing techniques, couple techniques could be independent from Kuzushi...

  17. Cluster Decline and Resilience

    DEFF Research Database (Denmark)

    Østergaard, Christian Richter; Park, Eun Kyung

    Most studies on regional clusters focus on identifying factors and processes that make clusters grow. However, sometimes technologies and market conditions suddenly shift, and clusters decline. This paper analyses the process of decline of the wireless communication cluster in Denmark, 1963...... in new resources to the cluster but being quick to withdraw in times of crisis....

  18. Reversing insect pollinator decline

    OpenAIRE

    Potts, Simon; Wentworth, Jonathan

    2013-01-01

    Pollination by insects enables the reproduction of flowering plants and is critical to UK agriculture.1 Insect pollinators have declined globally, with implications for food security and wild habitats. This POSTnote summarises the causes for the recent trends, gaps in knowledge and possible strategies for reversing pollinator decline.

  19. Effect of BDNF Val66Met on memory decline and hippocampal atrophy in prodromal Alzheimer's disease: a preliminary study.

    Directory of Open Access Journals (Sweden)

    Yen Ying Lim

    Full Text Available OBJECTIVE: Cross-sectional genetic association studies have reported equivocal results on the relationship between the brain-derived neurotrophic factor (BDNF Val66Met and risk of Alzheimer's disease (AD. As AD is a neurodegenerative disease, genetic influences may become clearer from prospective study. We aimed to determine whether BDNF Val66Met polymorphism influences changes in memory performance, hippocampal volume, and Aβ accumulation in adults with amnestic mild cognitive impairment (aMCI and high Aβ. METHODS: Thirty-four adults with aMCI were recruited from the Australian, Imaging, Biomarkers and Lifestyle (AIBL Study. Participants underwent PiB-PET and structural MRI neuroimaging, neuropsychological assessments and BDNF genotyping at baseline, 18 month, and 36 month assessments. RESULTS: In individuals with aMCI and high Aβ, Met carriers showed significant and large decline in episodic memory (d = 0.90, p = .020 and hippocampal volume (d = 0.98, p = .035. BDNF Val66Met was unrelated to the rate of Aβ accumulation (d = -0.35, p = .401. CONCLUSIONS: Although preliminary due to the small sample size, results of this study suggest that high Aβ levels and Met carriage may be useful prognostic markers of accelerated decline in episodic memory, and reductions in hippocampal volume in individuals in the prodromal or MCI stage of AD.

  20. Biomechanical ToolKit: Open-source framework to visualize and process biomechanical data.

    Science.gov (United States)

    Barre, Arnaud; Armand, Stéphane

    2014-04-01

    C3D file format is widely used in the biomechanical field by companies and laboratories to store motion capture systems data. However, few software packages can visualize and modify the integrality of the data in the C3D file. Our objective was to develop an open-source and multi-platform framework to read, write, modify and visualize data from any motion analysis systems using standard (C3D) and proprietary file formats (used by many companies producing motion capture systems). The Biomechanical ToolKit (BTK) was developed to provide cost-effective and efficient tools for the biomechanical community to easily deal with motion analysis data. A large panel of operations is available to read, modify and process data through C++ API, bindings for high-level languages (Matlab, Octave, and Python), and standalone application (Mokka). All these tools are open-source and cross-platform and run on all major operating systems (Windows, Linux, MacOS X). PMID:24548899

  1. Relationship between Biomechanical Characteristics of Spinal Manipulation and Neural Responses in an Animal Model: Effect of Linear Control of Thrust Displacement versus Force, Thrust Amplitude, Thrust Duration, and Thrust Rate

    Directory of Open Access Journals (Sweden)

    William R. Reed

    2013-01-01

    Full Text Available High velocity low amplitude spinal manipulation (HVLA-SM is used frequently to treat musculoskeletal complaints. Little is known about the intervention’s biomechanical characteristics that determine its clinical benefit. Using an animal preparation, we determined how neural activity from lumbar muscle spindles during a lumbar HVLA-SM is affected by the type of thrust control and by the thrust's amplitude, duration, and rate. A mechanical device was used to apply a linear increase in thrust displacement or force and to control thrust duration. Under displacement control, neural responses during the HVLA-SM increased in a fashion graded with thrust amplitude. Under force control neural responses were similar regardless of the thrust amplitude. Decreasing thrust durations at all thrust amplitudes except the smallest thrust displacement had an overall significant effect on increasing muscle spindle activity during the HVLA-SMs. Under force control, spindle responses specifically and significantly increased between thrust durations of 75 and 150 ms suggesting the presence of a threshold value. Thrust velocities greater than 20–30 mm/s and thrust rates greater than 300 N/s tended to maximize the spindle responses. This study provides a basis for considering biomechanical characteristics of an HVLA-SM that should be measured and reported in clinical efficacy studies to help define effective clinical dosages.

  2. Relationship between Biomechanical Characteristics of Spinal Manipulation and Neural Responses in an Animal Model: Effect of Linear Control of Thrust Displacement versus Force, Thrust Amplitude, Thrust Duration, and Thrust Rate.

    Science.gov (United States)

    Reed, William R; Cao, Dong-Yuan; Long, Cynthia R; Kawchuk, Gregory N; Pickar, Joel G

    2013-01-01

    High velocity low amplitude spinal manipulation (HVLA-SM) is used frequently to treat musculoskeletal complaints. Little is known about the intervention's biomechanical characteristics that determine its clinical benefit. Using an animal preparation, we determined how neural activity from lumbar muscle spindles during a lumbar HVLA-SM is affected by the type of thrust control and by the thrust's amplitude, duration, and rate. A mechanical device was used to apply a linear increase in thrust displacement or force and to control thrust duration. Under displacement control, neural responses during the HVLA-SM increased in a fashion graded with thrust amplitude. Under force control neural responses were similar regardless of the thrust amplitude. Decreasing thrust durations at all thrust amplitudes except the smallest thrust displacement had an overall significant effect on increasing muscle spindle activity during the HVLA-SMs. Under force control, spindle responses specifically and significantly increased between thrust durations of 75 and 150 ms suggesting the presence of a threshold value. Thrust velocities greater than 20-30 mm/s and thrust rates greater than 300 N/s tended to maximize the spindle responses. This study provides a basis for considering biomechanical characteristics of an HVLA-SM that should be measured and reported in clinical efficacy studies to help define effective clinical dosages.

  3. Changes in multi-segment foot biomechanics with a heat-mouldable semi-custom foot orthotic device

    OpenAIRE

    Ferber Reed; Benson Brittany

    2011-01-01

    Abstract Background Semi-custom foot orthoses (SCO) are thought to be a cost-effective alternative to custom-made devices. However, previous biomechanical research involving either custom or SCO has only focused on rearfoot biomechanics. The purpose of this study was therefore to determine changes in multi-segment foot biomechanics during shod walking with and without an SCO. We chose to investigate an SCO device that incorporates a heat-moulding process, to further understand if the moulding...

  4. Using Clinical Gait Case Studies to Enhance Learning in Biomechanics

    Science.gov (United States)

    Chester, Victoria

    2011-01-01

    Clinical case studies facilitate the development of clinical reasoning strategies through knowledge and integration of the basic sciences. Case studies have been shown to be more effective in developing problem-solving abilities than the traditional lecture format. To enhance the learning experiences of students in biomechanics, clinical case…

  5. Non-linear viscoelastic finite element analysis of the effect of the length of glass fiber posts on the biomechanical behaviour of directly restored incisors and surrounding alveolar bone.

    Science.gov (United States)

    Ferrari, Marco; Sorrentino, Roberto; Zarone, Fernando; Apicella, Davide; Aversa, Raffaella; Apicella, Antonio

    2008-07-01

    The study aimed at estimating the effect of insertion length of posts with composite restorations on stress and strain distributions in central incisors and surrounding bone. The typical, average geometries were generated in a FEA environment. Dentin was considered as an elastic orthotropic material, and periodontal ligament was coupled with nonlinear viscoelastic mechanical properties. The model was then validated with experimental data on displacement of incisors from published literature. Three post lengths were investigated in this study: root insertion of 5, 7, and 9 mm. For control, a sound incisor model was generated. Then, a tearing load of 50 N was applied to both sound tooth and simulation models. Post restorations did not seem to affect the strain distribution in bone when compared to the control. All simulated post restorations affected incisor biomechanics and reduced the root's deforming capability, while the composite crowns underwent a higher degree of deformation than the sound crown. No differences could be noticed in incisor stress and strain. As for the influence of post length, it was not shown to affect the biomechanics of restored teeth. PMID:18833761

  6. Biomechanical properties of acellular sciatic nerves treated with a modified chemical method

    Institute of Scientific and Technical Information of China (English)

    Xinlong Ma; Zhao Yang; Xiaolei Sun; Jianxiong Ma; Xiulan Li; Zhenzhen Yuan; Yang Zhang; Honggang Guo

    2011-01-01

    Nerve grafts are able to adapt to surrounding biomechanical environments if the nerve graft itself exhibits appropriate biomechanical properties (load, elastic modulus, etc.). The present study was designed to determine the differences in biomechanical properties between fresh and chemically acellularized sciatic nerve grafts. Two different chemical methods were used to establish acellular nerve grafts. The nerve was chemically extracted in the Sondell method with a combination of Triton X-100 (nonionic detergent) and sodium deoxycholate (anionic detergent), and in the modified method with a combination of Triton X-200 (anionic detergent), sulfobetaine-10 (SB-10, amphoteric detergents), and sulfobetaine-16 (SB-16, amphoteric detergents). Following acellularization, hematoxylin-eosin staining and scanning electron microscopy demonstrated that the effect of acellularization via the modified method was similar to the traditional Sondell method. However, effects of demyelination and nerve fiber tube integrity were superior to the traditional Sondell method. Biomechanical testing showed that peripheral nerve graft treated using the chemical method resulted in decreased biomechanical properties (ultimate load, ultimate stress, ultimate strain, and mechanical work to fracture) compared with fresh nerves, but the differences had no statistical significance (P > 0.05). These results demonstrated no significant effect on biomechanical properties of nerves treated using the chemical method. In conclusion, nerve grafts treated via the modified method removed Schwann cells, preserved neural structures, and ensured biomechanical properties of the nerve graft, which could be more appropriate for implantation studies.

  7. Effect of tiotropium on lung function decline in early-stage of chronic obstructive pulmonary disease patients: propensity score-matched analysis of real-world data

    Directory of Open Access Journals (Sweden)

    Lee HY

    2015-10-01

    Full Text Available Ha Youn Lee,1,2 Sun Mi Choi,1,2 Jinwoo Lee,1,2 Young Sik Park,1,2 Chang-Hoon Lee,1,2 Deog Kyeom Kim,2,3 Sang-Min Lee,1,2 Ho Il Yoon,2,4 Jae-Joon Yim,1,2 Young Whan Kim,1,2 Sung Koo Han,1,2 Chul-Gyu Yoo1,2 1Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea; 2Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; 3Department of Internal Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul, Republic of Korea; 4Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea Background: Tiotropium failed to slow the annual rate of forced expiratory volume in 1 second (FEV1 decline in chronic obstructive pulmonary disease (COPD patients with <70% predicted FEV1. However, the rate of FEV1 decline is known to be faster at early stages, which suggests that the effects of tiotropium may be more prominent in early-stage of COPD patients. The aim of this study was to test the hypothesis that tiotropium modifies the rate of FEV1 decline in COPD patients with an FEV1≥70%.Methods: We retrospectively reviewed the records of COPD patients diagnosed between January 1, 2004, and July 31, 2012, at Seoul National University Hospital, Seoul National University Bundang Hospital, and Seoul Metropolitan Government-Seoul National University Boramae Medical Center. The inclusion criteria were as follows: age ≥40 years, postbronchodilator (BD FEV1≥70% of predicted and FEV1/FVC (forced vital capacity <0.70, and spirometry more than two times at certain times of the year. Conversely, the exclusion criteria were as follows: asthma, lung cancer, pulmonary tuberculosis, pulmonary resection, or long-term use of a short-acting muscarinic antagonist. The annual lung function decline in patients using tiotropium was compared with that in patients not

  8. Sport and Exercise Biomechanics (Bios Instant Notes)

    OpenAIRE

    Paul Grimshaw; Adrian Lees; Neil Fowler; Adrian Burden

    2007-01-01

    DESCRIPTION Instant Notes on Sport and Exercise Biomechanics provides a broad overview of the fundamental concepts in exercise and sport biomechanics. PURPOSE The book aims to provide instant notes on essential information about biomechanics, and is designed to help undergraduate students to grasp the corresponding subjects in physical effort rapidly and easily. AUDIENCE The book provides a useful resource for undergraduate and graduate students as a fundamental reference book. For the resear...

  9. Effect of IP3R3 and NPY on age-related declines in olfactory stem cell proliferation.

    Science.gov (United States)

    Jia, Cuihong; Hegg, Colleen C

    2015-02-01

    Losing the sense of smell because of aging compromises health and quality of life. In the mouse olfactory epithelium, aging reduces the capacity for tissue homeostasis and regeneration. The microvillous cell subtype that expresses both inositol trisphosphate receptor type 3 (IP3R3) and the neuroproliferative factor neuropeptide Y (NPY) is critical for regulation of homeostasis, yet its role in aging is undefined. We hypothesized that an age-related decline in IP3R3 expression and NPY signaling underlie age-related homeostatic changes and olfactory dysfunction. We found a decrease in IP3R3(+) and NPY(+) microvillous cell numbers and NPY protein and a reduced sensitivity to NPY-mediated proliferation over 24 months. However, in IP3R3-deficient mice, there was no further age-related reduction in cell numbers, proliferation, or olfactory function compared with wild type. The proliferative response was impaired in aged IP3R3-deficient mice when injury was caused by satratoxin G, which induces IP3R3-mediated NPY release, but not by bulbectomy, which does not evoke NPY release. These data identify IP3R3 and NPY signaling as targets for improving recovery following olfactotoxicant exposure.

  10. Unified Approach to the Biomechanics of Dental Implantology

    Science.gov (United States)

    Grenoble, D. E.; Knoell, A. C.

    1973-01-01

    The human need for safe and effective dental implants is well-recognized. Although many implant designs have been tested and are in use today, a large number have resulted in clinical failure. These failures appear to be due to biomechanical effects, as well as biocompatibility and surgical factors. A unified approach is proposed using multidisciplinary systems technology, for the study of the biomechanical interactions between dental implants and host tissues. The approach progresses from biomechanical modeling and analysis, supported by experimental investigations, through implant design development, clinical verification, and education of the dental practitioner. The result of the biomechanical modeling, analysis, and experimental phases would be the development of scientific design criteria for implants. Implant designs meeting these criteria would be generated, fabricated, and tested in animals. After design acceptance, these implants would be tested in humans, using efficient and safe surgical and restorative procedures. Finally, educational media and instructional courses would be developed for training dental practitioners in the use of the resulting implants.

  11. Effect of knee physiological anatomy environment on knee biomechanical properties%膝关节生理解剖环境对膝关节生物力学特性的影响

    Institute of Scientific and Technical Information of China (English)

    张美娟

    2012-01-01

    the biomechanics of the knee joint were selected, and for the articles in the same field, those published recently or in the authorized journals were selected. There were 163 articles after the initial survey. Then 25 articles related to biomechanics of the knee joint were selected to review.RESULTS AND CONCLUSION: The stability of the knee joint relies on the articular bone, and also depends on the constraints of the anterior and posterior cruciate ligament, the balance of internal and external collateral ligament and extensor mechanism, as well as the power balance of quadriceps and hamstrings, especially depends on the balancing and stabilizing effect of the internal and external collateral ligament. It indicates that the anatomical environment of the knee joint determines the complexity of the knee joint in the biomechanical properties of loading, action and stability. Therefore, understanding the physiological structure and anatomical characteristics of the knee joint is of benefits to study the biomechanical characteristics of the knee joint, and that is important to study the pain, injury and tissue engineering of the knee joint.

  12. Decline in tropospheric NO2 and the effects of the 2008-09 economic crisis observed by OMI over Europe

    Science.gov (United States)

    Castellanos, P.; Boersma, F. F.

    2011-12-01

    We present a trend analysis of tropospheric NO2 for the time period of 2004-2010. Necessary for monitoring pollution abatement strategies, NO2 trends analyses are often based on surface networks, which suffer from high NO2 biases and spatial representativity issues inherent to the standard monitoring method (thermal reduction of NO2 followed by reaction with ozone and chemiluminescence). Space based NO2 trends are unbiased and self-consistent, but over Europe they have not been as obvious as those observed over North America and East Asia. In this work we exploit the daily NO2 column observations from the Ozone Monitoring Instrument (OMI) in order to isolate long-term (timescales greater than one year) variability in NO2 over Europe without imposing a parametric fit to the data. In general, we find between 2005 and 2008, 1-5% per year declines in NO2 concentration in many polluted regions (e.g. Germany, Netherlands, Belgium, Italy, Spain), but also 1-5% per year increases over the English Channel and the southern North Sea (a major shipping channel), as well as the United Kingdom, northern France and Eastern Europe. In 2009, NO2 almost exclusively decreased over Europe at a rate of 5-10% per year, coinciding with the abrupt decrease in industrial production and construction prompted by the global economic crisis. By 2010, in many areas the NO2 rate of change returned to pre-2009 levels suggesting economic recovery. We employ a simple fitting model to separate the forcing by meteorological variability, which can influence apparent NO2 trends, from that of NOx emissions. We calculate 1-3% per year NOx emissions reduction rates over most of Europe and an additional 15-30% per year decrease in NOx emissions during the economic crisis time period.

  13. Spatial and temporal variation in population dynamics of Andean frogs: Effects of forest disturbance and evidence for declines

    Directory of Open Access Journals (Sweden)

    Esther M. Cole

    2014-08-01

    Full Text Available Biodiversity loss is a global phenomenon that can result in the collapse of food webs and critical ecosystem services. Amphibian population decline over the last century is a notable case of species loss because amphibians survived the last four major extinction events in global history, their current rate of extinction is unprecedented, and their rate of extinction is greater than that for most other taxonomic groups. Despite the severity of this conservation problem and its relevance to the study of global biodiversity loss, major knowledge gaps remain for many of the most threatened species and regions in the world. Rigorous estimates of population parameters are lacking for many amphibian species in the Neotropics. The goal of our study was to determine how the demography of seven species of the genus Pristimantis varied over time and space in two cloud forests in the Ecuadorian Andes. We completed a long term capture–mark–recapture study to estimate abundance, survival, and population growth rates in two cloud forests in the Ecuadorian Andes; from 2002 to 2009 at Yanayacu in the Eastern Cordillera and from 2002 to 2003 at Cashca Totoras in the Western Cordillera. Our results showed seasonal and annual variation in population parameters by species and sex. P. bicantus experienced significant reductions in abundance over the course of our study. Abundance, apparent survival, and population growth rates were lower in disturbed than in primary or mature secondary forest. The results of our study raise concerns for the population status of understudied amphibian groups and provide insights into the population dynamics of Neotropical amphibians.

  14. Substantial effects of apolipoprotein E ε4 on memory decline in very old age: longitudinal findings from a population-based sample.

    Science.gov (United States)

    Praetorius, Marcus; Thorvaldsson, Valgeir; Hassing, Linda B; Johansson, Boo

    2013-12-01

    We examined associations between the apolipoprotein E (APOE) ε4 allele and levels of performance and rates of change in cognition in late life taking incident dementia into account. The sample consisted of 482 nondemented individuals, aged 80 years and older at baseline, drawn from the OCTO twin study. A battery of 10 cognitive tests was administered at 5 occasions with measurements intervals of 2 years. We fitted hierarchical linear models with time specified as time to death and controlled for baseline age, sex, education, stroke, cardiovascular disease, hypertension, diabetes, and incident dementia. The ε4 allele was significantly associated with lower levels of performance or steeper rate of decline in all 7 memory tests. Largest effect sizes were found in tests of delayed recall and recognition memory. The effects of the APOE ε4 allele were, however, reduced to a nonsignificant level in all tests except 1 after accounting for incident dementia. The findings support the notion that the APOE ε4 allele is associated with substantial memory decline in very old age, but as expected, the effect is largely related to incident dementia.

  15. Biomechanics research in ski jumping, 1991-2006.

    Science.gov (United States)

    Schwameder, Hermann

    2008-01-01

    In this paper, I review biomechanics research in ski jumping with a specific focus on publications presented between 1991 and 2006 on performance enhancement, limiting factors of the take-off, specific training and conditioning, aerodynamics, and safety. The first section presents a brief description of ski jumping phases (in-run, take-off, early flight, stable flight, and landing) regarding the biomechanical and functional fundamentals. The most important and frequently used biomechanical methods in ski jumping (kinematics, ground reaction force analyses, muscle activation patterns, aerodynamics) are summarized in the second section. The third section focuses on ski jumping articles and research findings published after the establishment of the V-technique in 1991, as the introduction of this technique has had a major influence on performance enhancement, ski jumping regulations, and the construction of hill profiles. The final section proposes topics for future research in the biomechanics of ski jumping, including: take-off and early flight and the relative roles of vertical velocity and forward somersaulting angular momentum; optimal jumping patterns utilizing the capabilities of individual athletes; development of kinematic and kinetic feedback systems for hill jumps; comparisons of simulated and hill jumps; effect of equipment modifications on performance and safety enhancement.

  16. Pathobiology of obesity and osteoarthritis: integrating biomechanics and inflammation

    Directory of Open Access Journals (Sweden)

    Rita I. Issa

    2012-05-01

    Full Text Available Obesity is a significant risk factor for developing osteoarthritis in weight-bearing and non-weight-bearing joints. Although the pathogenesis of obesity-associated osteoarthritis is not completely understood, recent studies indicate that pro-inflammatory metabolic factors contribute to an increase in osteoarthritis risk. Adipose tissue, and in particular infrapatellar fat, is a local source of pro-inflammatory mediators that are increased with obesity and have been shown to increase cartilage degradation in cell and tissue culture models. One adipokine in particular, leptin, may be a critical mediator of obesity-associated osteoarthritis via synergistic actions with other inflammatory cytokines. Biomechanical factors may also increase the risk of osteoarthritis by activating cellular inflammation and promoting oxidative stress. However, some types of biomechanical stimulation, such as physiologic cyclic loading, inhibit inflammation and protect against cartilage degradation. A high percentage of obese individuals with knee osteoarthritis are sedentary, suggesting that a lack of physical activity may increase the susceptibility to inflammation. A more comprehensive approach to understanding how obesity alters daily biomechanical exposures within joint tissues may provide new insight into the protective and damaging effects of biomechanical factors on inflammation in osteoarthritis.

  17. LUMBAR SPINAL STENOSIS. A REVIEW OF BIOMECHANICAL STUDIES

    Institute of Scientific and Technical Information of China (English)

    戴力扬; 徐印坎

    1998-01-01

    ObjectS. To investigate the biomechanical aspects of etiology, pathology, clinical manifestation, diagnosis and surgical treatment of the lumbar spinal stenosis. Methods. A series of biomechanical methods, such as three-dimensional finite element models, threedimensional kinematic measurement, cadeveric evaluation, and imaging assessment was applied to correlate lumbar biomechanics and lumber spinal stenosls. Surgery of lumber spinal stenosis has been improved. Results.The stresses significantly concentrate on the posterolateral part of the annulus fibrcsms of disc, the posterior surface of vertebral body, the pedlcle, the interarticularis and the beet joints. This trend is intensified by disc degeneration and lumber backward extension. Posterior elcxnent resection has a definite effect upon the biomechanical behavior of lumbar vertebrae. The improved operations proved satisfactory. Conclusion. Stress concentration in the lumber vertebrae is of importance to the etiology of degenerative lumbar spinal stenosls, and disc degeneratkm is the initial key of this process. Than these will be aggravatnd by backward extension. Functloval radiography and myelography are of assistance to the diagnosis of the lumhar spinal stenosls. For the surgcal treatment of the lumber spinal stenosis, destruction of the posterior element should be avoid as far as possible based upon the thorough decmnpression. Maintaining the lumbar spine in flexion by fusion after decorapression has been proved a useftd method. When developmental spinal stenoals is combined with disc herniation, discectoray through laminotomy is recommend for decompression.

  18. Effects of strontium malonate (NB S101) on the compositional, structural and biomechanical properties of calcified tissues in rats and dogs

    DEFF Research Database (Denmark)

    Raffalt, Anders Christer

    with postmenopausal osteoporosis. Strontium malonate (SrM) is currently being developed as a novel pharmaceutical for the treatment and prevention of osteoporosis. SrM potentially provides considerable advantages over SrR with respect to Sr content, bioavailability and ease of administration. SrM was tested in three...... were examined for treatment-related changes in concentrations of Sr, Ca, Mg and P using inductively coupled mass spectrometry (ICP-MS). Bone mineral density (BMD) was determined using dual energy X-ray absorptiometry (DEXA), and the biomechanical properties of the bones were assessed using bending...... cross-flow nebuliser. Rh was found to be a suitable internal standard for all four analytes. Reliable estimates of the measurement uncertainties were achieved by pooling calibration data obtained on different days. Treatment with SrM resulted in a dose-dependent increase in Sr contents in all analysed...

  19. Is America in Decline?

    Science.gov (United States)

    Prowse, Michael

    1992-01-01

    Rather than decline, the issues are increased equality among industrialized nations, increased U.S. social inequality, and social implications of the new economy. The best way to tackle growing social inequality is by reshaping education to give workers the skills needed for this new economy. (JOW)

  20. Age-related wayfinding differences in real large-scale environments: detrimental motor control effects during spatial learning are mediated by executive decline?

    Directory of Open Access Journals (Sweden)

    Mathieu Taillade

    Full Text Available The aim of this study was to evaluate motor control activity (active vs. passive condition with regards to wayfinding and spatial learning difficulties in large-scale spaces for older adults. We compared virtual reality (VR-based wayfinding and spatial memory (survey and route knowledge performances between 30 younger and 30 older adults. A significant effect of age was obtained on the wayfinding performances but not on the spatial memory performances. Specifically, the active condition deteriorated the survey measure in all of the participants and increased the age-related differences in the wayfinding performances. Importantly, the age-related differences in the wayfinding performances, after an active condition, were further mediated by the executive measures. All of the results relative to a detrimental effect of motor activity are discussed in terms of a dual task effect as well as executive decline associated with aging.

  1. Fruit biomechanics based on anatomy: a review

    Science.gov (United States)

    Li, Zhiguo; Yang, Hongling; Li, Pingping; Liu, Jizhan; Wang, Jizhang; Xu, Yunfeng

    2013-01-01

    Fruit biomechanics is needed for quality determination, multiscale modelling and engineering design of fruit processes and equipments. However, these determined fruit biomechanics data often have obvious differences for the same fruit or tissue. In order to investigate it, the fruit biomechanics based on anatomy was reviewed in this paper. First, the anatomical characteristics of fruit biomaterials were described at the macroscopic `tissue' level and microscopic `cellular' level. Subsequently, the factors affecting fruit biomechanics based on anatomy and the relationships between fruit biomechanics, texture and mechanical damage were summarised according to the published literature. Fruit biomechanics is mainly affected by size, number and arrangement of cells, quantity and volume of intracellular spaces, structure, thickness, chemical composition and permeability of cell walls, and pectin degradation level and turgor pressure within cells based on microanatomy. Four test methods and partial determined results of fruit biomechanics were listed and reviewed. The determined mechanical properties data of fruit are only approximate values by using the existing four test methods, owing to the fruit biomaterials being non-homogeneous and living. Lastly, further aspects for research on fruit biomechanics were proposed for the future.

  2. Biomechanical properties of four dermal substitutes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guo-an; NING Fang-gang; ZHAO Nan-ming

    2007-01-01

    @@ Many kinds of cell-free dermal substitutes have been developed during the past several years, however,their biomechanical properties, including hysteresis,stress relaxation, creep, and non-linear stress-strain, are still unknown. In this study, we tested these biomechanical characteristics of four dermal substitutes,and compared them with those of fresh human skin (FHS).

  3. Applied Biomechanics in an Instructional Setting

    Science.gov (United States)

    Hudson, Jackie L.

    2006-01-01

    Biomechanics is the science of how people move better, meaning more skillfully and more safely. This article places more emphasis on skill rather than safety, though there are many parallels between them. It shares a few features of the author's paradigm of applied biomechanics and discusses an integrated approach toward a middle school football…

  4. Biomechanics of Posterior Dynamic Stabilization Systems

    Directory of Open Access Journals (Sweden)

    D. U. Erbulut

    2013-01-01

    Full Text Available Spinal rigid instrumentations have been used to fuse and stabilize spinal segments as a surgical treatment for various spinal disorders to date. This technology provides immediate stability after surgery until the natural fusion mass develops. At present, rigid fixation is the current gold standard in surgical treatment of chronic back pain spinal disorders. However, such systems have several drawbacks such as higher mechanical stress on the adjacent segment, leading to long-term degenerative changes and hypermobility that often necessitate additional fusion surgery. Dynamic stabilization systems have been suggested to address adjacent segment degeneration, which is considered to be a fusion-associated phenomenon. Dynamic stabilization systems are designed to preserve segmental stability, to keep the treated segment mobile, and to reduce or eliminate degenerative effects on adjacent segments. This paper aimed to describe the biomechanical aspect of dynamic stabilization systems as an alternative treatment to fusion for certain patients.

  5. Decline in sediment contamination by persistent toxic substances from the outfall of wastewater treatment plant: Effectiveness of legislative actions in Korea.

    Science.gov (United States)

    Jin, Xiangzi; Lee, Hyun-Kyung; Badejo, Abimbola C; Lee, Sang-Yoon; Shen, Aihua; Lee, Sunggyu; Jeong, Yunsun; Choi, Minkyu; Moon, Hyo-Bang

    2016-06-01

    Legacy and new persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) were measured in sediments near a wastewater treatment plant (WWTP) outfall in a semi-enclosed bay, to investigate the current contamination and temporal changes in these contaminants associated with regulation activities in Korea. The concentrations of most of the POPs showed clear decreasing trends with an increase in the distance from the WWTP outfall, indicating that the WWTP discharges greatly contributed to the sediment contamination by POPs. Highly significant correlations were found for most of the POPs, indicating a common source for sediment contamination. Significant declines were found in the concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (DL-PCBs), polybrominated diphenyl ethers (PBDEs), and PAHs in the sediments collected between 2005 and 2013. This result suggested that legislative actions (regulation of the PCDD/Fs in flue gas, total pollution load management, and whole effluent toxicity for WWTP discharges) and change of fuels, were likely to be effective at reducing the POP and PAH levels in sediments during the past several years. The different compositional profiles of the PCDD/Fs and PAHs between 2005 and 2013 implied changes in and/or additional sources of these contaminants. Despite a decline in the PCDD/Fs over time, the present levels of PCDD/Fs in the sediment exceeded some of the sediment quality guidelines suggested by the National Oceanic and Atmospheric Administration. PMID:27031806

  6. A draft de novo genome assembly for the northern bobwhite (Colinus virginianus reveals evidence for a rapid decline in effective population size beginning in the Late Pleistocene.

    Directory of Open Access Journals (Sweden)

    Yvette A Halley

    Full Text Available Wild populations of northern bobwhites (Colinus virginianus; hereafter bobwhite have declined across nearly all of their U.S. range, and despite their importance as an experimental wildlife model for ecotoxicology studies, no bobwhite draft genome assembly currently exists. Herein, we present a bobwhite draft de novo genome assembly with annotation, comparative analyses including genome-wide analyses of divergence with the chicken (Gallus gallus and zebra finch (Taeniopygia guttata genomes, and coalescent modeling to reconstruct the demographic history of the bobwhite for comparison to other birds currently in decline (i.e., scarlet macaw; Ara macao. More than 90% of the assembled bobwhite genome was captured within 14,000 unique genes and proteins. Bobwhite analyses of divergence with the chicken and zebra finch genomes revealed many extremely conserved gene sequences, and evidence for lineage-specific divergence of noncoding regions. Coalescent models for reconstructing the demographic history of the bobwhite and the scarlet macaw provided evidence for population bottlenecks which were temporally coincident with human colonization of the New World, the late Pleistocene collapse of the megafauna, and the last glacial maximum. Demographic trends predicted for the bobwhite and the scarlet macaw also were concordant with how opposing natural selection strategies (i.e., skewness in the r-/K-selection continuum would be expected to shape genome diversity and the effective population sizes in these species, which is directly relevant to future conservation efforts.

  7. Effect of corneal biomechanical parameters in astigmatic keratotomy%角膜生物力学特性对散光性角膜切开术影响

    Institute of Scientific and Technical Information of China (English)

    邹湖涌; 王勤美; 俞阿勇; 郑志利; 芦群

    2012-01-01

    目的 探讨屈光性晶状体置换联合散光性角膜切开术术后角膜生物力学特性的改变及其对手术效果的影响.方法 收集角膜散光≥1.50D的患者,在屈光性晶状体置换术时联合行散光性角膜切开术.术前,术后1周、1、3、6个月用眼反应分析仪(Ocular response analyzer,Reichert,Depew,NY)测量角膜阻力因子(corneal resistance factor,CRF)、角膜滞后性(corneal hysteresis,CH)、Goldmann眼压(Goldmann correlated intraocular pressure,IOP);用角膜地形图仪(Pentacam ver.1.11;Oculus,Germany)观察角膜散光的变化.采用重复测量数据方差分析及Pearson相关分析进行统计分析.结果 共23例(32只眼).CRF、CH术后1周、1个月均低于术前水平(P<0.05),术后3个月、6个月与术前比较差异均无统计学意义(P>0.05).IOP术后各时间点与术前比较差异均无统计学意义(P>0.05).散光矢量分解后术后J0的变化与CRF、CH负相关(P<0.05),与IOP无相关(P>0.05).J45的变化与CRF、CH、IOP无相关(P>0.05).结论 屈光性晶状体置换术联合散光性角膜切开术不会引起角膜生物力学特性的长期改变,CRF、CH对散光性角膜切开术手术效果产生一定的影响.%Objective To study the changes of corneal biomechanical parameters and the correlations between surgical induced corneal astigmatism and corneal biomechanical parameters in Astigmatic Keratotomy (AK).Methods Patients with corneal astigmatism ≥1.50D underwent AK during refractive intraocular lens exchange.Corneal resistance factor (CRF),Corneal hysteresis (CH) and Goldmann-correlated intraocular pressure (IOP) measurements were obtained with the Ocular Response Analyzer (ORA,Reichert.,Depew,NY) before and 1 week,1 month,3 months and 6 months after surgery.Corneal astigmatism was also measured with Scheimpflug imaging (Pentacam ver.1.11; Oculus,Germany).Results Thirty-two eyes were included in this study.Both CRF and CH decreased briefly at 1 week and

  8. Integrative Role Of Cinematography In Biomechanics Research

    Science.gov (United States)

    Zernicke, Ronald F.; Gregor, Robert J.

    1982-02-01

    Cinematography is an integral element in the interdisciplinary biomechanics research conducted in the Department of Kinesiology at the University of California, Los Angeles. For either an isolated recording of a movement phenomenon or as a recording component which is synchronized with additional transducers and recording equipment, high speed motion picture film has been effectively incorporated into resr'arch projects ranging from two and three dimensional analyses of human movements, locomotor mechanics of cursorial mammals and primates, to the structural responses and dynamic geometries of skeletal muscles, tendons, and ligaments. The basic equipment used in these studies includes three, 16 mm high speed, pin-registered cameras which have the capacity for electronic phase-locking. Crystal oscillators provide the generator pulses to synchronize the timing lights of the cameras and the analog-to-digital recording equipment. A rear-projection system with a sonic digitizer permits quantification of film coordinates which are stored on computer disks. The capacity for synchronizing the high speed films with additional recording equipment provides an effective means of obtaining not only position-time data from film, but also electromyographic, force platform, tendon force transducer, and strain gauge recordings from tissues or moving organisms. During the past few years, biomechanics research which comprised human studies has used both planar and three-dimensional cinematographic techniques. The studies included planar analyses which range from the gait characteristics of lower extremity child amputees to the running kinematics and kinetics of highly skilled sprinters and long-distance runners. The dynamics of race cycling and kinetics of gymnastic maneuvers were studied with cinematography and either a multi-dimensional force platform or a bicycle pedal with strain gauges to determine the time histories of the applied forces. The three-dimensional technique

  9. Impact of climate change effecting Decline on Migration Birds of Bhadalwadi Lake Indapur Taluka M.S India

    OpenAIRE

    U.S .Gantaloo; Sangeeta B Dongare

    2016-01-01

    Environmental changes are now a day’s happening regularly day to day increase in temperature ,Scarcity of rainfall ,Drying of lakes have strong implication on Biodiversity .) .Global warming has set in motion and is affecting the timing of migration of birds .Birds are reliable indicator of environment change for centuries and their arrival indicate start of winter and departure summer in study area .There are many example of the effect of climate change on birds from all around t...

  10. Development of a biomechanical energy harvester

    Directory of Open Access Journals (Sweden)

    Donelan J Maxwell

    2009-06-01

    Full Text Available Abstract Background Biomechanical energy harvesting–generating electricity from people during daily activities–is a promising alternative to batteries for powering increasingly sophisticated portable devices. We recently developed a wearable knee-mounted energy harvesting device that generated electricity during human walking. In this methods-focused paper, we explain the physiological principles that guided our design process and present a detailed description of our device design with an emphasis on new analyses. Methods Effectively harvesting energy from walking requires a small lightweight device that efficiently converts intermittent, bi-directional, low speed and high torque mechanical power to electricity, and selectively engages power generation to assist muscles in performing negative mechanical work. To achieve this, our device used a one-way clutch to transmit only knee extension motions, a spur gear transmission to amplify the angular speed, a brushless DC rotary magnetic generator to convert the mechanical power into electrical power, a control system to determine when to open and close the power generation circuit based on measurements of knee angle, and a customized orthopaedic knee brace to distribute the device reaction torque over a large leg surface area. Results The device selectively engaged power generation towards the end of swing extension, assisting knee flexor muscles by producing substantial flexion torque (6.4 Nm, and efficiently converted the input mechanical power into electricity (54.6%. Consequently, six subjects walking at 1.5 m/s generated 4.8 ± 0.8 W of electrical power with only a 5.0 ± 21 W increase in metabolic cost. Conclusion Biomechanical energy harvesting is capable of generating substantial amounts of electrical power from walking with little additional user effort making future versions of this technology particularly promising for charging portable medical devices.

  11. Biomechanics of sprint running. A review.

    Science.gov (United States)

    Mero, A; Komi, P V; Gregor, R J

    1992-06-01

    Understanding of biomechanical factors in sprint running is useful because of their critical value to performance. Some variables measured in distance running are also important in sprint running. Significant factors include: reaction time, technique, electromyographic (EMG) activity, force production, neural factors and muscle structure. Although various methodologies have been used, results are clear and conclusions can be made. The reaction time of good athletes is short, but it does not correlate with performance levels. Sprint technique has been well analysed during acceleration, constant velocity and deceleration of the velocity curve. At the beginning of the sprint run, it is important to produce great force/power and generate high velocity in the block and acceleration phases. During the constant-speed phase, the events immediately before and during the braking phase are important in increasing explosive force/power and efficiency of movement in the propulsion phase. There are no research results available regarding force production in the sprint-deceleration phase. The EMG activity pattern of the main sprint muscles is described in the literature, but there is a need for research with highly skilled sprinters to better understand the simultaneous operation of many muscles. Skeletal muscle fibre characteristics are related to the selection of talent and the training-induced effects in sprint running. Efficient sprint running requires an optimal combination between the examined biomechanical variables and external factors such as footwear, ground and air resistance. Further research work is needed especially in the area of nervous system, muscles and force and power production during sprint running. Combining these with the measurements of sprinting economy and efficiency more knowledge can be achieved in the near future.

  12. Impact of climate change effecting Decline on Migration Birds of Bhadalwadi Lake Indapur Taluka M.S India

    Directory of Open Access Journals (Sweden)

    U.S .Gantaloo

    2016-08-01

    Full Text Available Environmental changes are now a day’s happening regularly day to day increase in temperature ,Scarcity of rainfall ,Drying of lakes have strong implication on Biodiversity . .Global warming has set in motion and is affecting the timing of migration of birds .Birds are reliable indicator of environment change for centuries and their arrival indicate start of winter and departure summer in study area .There are many example of the effect of climate change on birds from all around the world which taken together provide compelling evidence that climate change is already affecting birds in diverse ways. The study was carried out for two years considering the changes occurring in climate parameters like Air Temperature, Rainfall were taken into facts .Keen observation with the help camera photography were taken to study. The effect on migrating Birds which measure international status on wet lands and lakes. Hence in the present study the data on biodiversity ,migratory birds have been collected to understand How climate change supported the dwelling of avian fauna in this area . This paper opens a review on migration of birds on the eve of 14th&15th May of world Bird migratory day.

  13. Building a better hormone therapy?: How understanding the rapid effects of sex steroid hormones could lead to new therapeutics for age-related memory decline

    OpenAIRE

    Frick, Karyn M.

    2012-01-01

    A wealth of data collected in recent decades has demonstrated that ovarian sex-steroid hormones, particularly 17β-estradiol (E2), are important trophic factors that regulate the function of cognitive regions of the brain such as the hippocampus. The loss of hormone cycling at menopause is associated with cognitive decline and dementia in women, and the onset of memory decline in animal models. However, hormone therapy is not currently recommended to prevent or treat cognitive decline, in part...

  14. The early emergence and puzzling decline of relational reasoning: Effects of knowledge and search on inferring abstract concepts.

    Science.gov (United States)

    Walker, Caren M; Bridgers, Sophie; Gopnik, Alison

    2016-11-01

    We explore the developmental trajectory and underlying mechanisms of abstract relational reasoning. We describe a surprising developmental pattern: Younger learners are better than older ones at inferring abstract causal relations. Walker and Gopnik (2014) demonstrated that toddlers are able to infer that an effect was caused by a relation between two objects (whether they are the same or different), rather than by individual kinds of objects. While these findings are consistent with evidence that infants recognize same-different relations, they contrast with a large literature suggesting that older children tend to have difficulty inferring these relations. Why might this be? In Experiment 1a, we demonstrate that while younger children (18-30-month-olds) have no difficulty learning these relational concepts, older children (36-48-month-olds) fail to draw this abstract inference. Experiment 1b replicates the finding with 18-30-month-olds using a more demanding intervention task. Experiment 2 tests whether this difference in performance might be because older children have developed the general hypothesis that individual kinds of objects are causal - the high initial probability of this alternative hypothesis might override the data that favors the relational hypothesis. Providing additional information falsifying the alternative hypothesis improves older children's performance. Finally, Experiment 3 demonstrates that prompting for explanations during learning also improves performance, even without any additional information. These findings are discussed in light of recent computational and algorithmic theories of learning. PMID:27472036

  15. Biomechanical performance of new cardiovascular needles.

    Science.gov (United States)

    Thacker, J G; Ferguson, R E; Rodeheaver, G T; Edlich, R F

    2001-01-01

    Cardiovascular needles are now being manufactured from new stainless steel alloys containing high concentrations of nickel, Surgalloy and Ethalloy. The purpose of this study was to compare the biomechanical performance of a cardiovascular needle made of Surgalloy with a comparably sized needle made of Ethalloy. The parameters of biomechanical performance included sharpness, maintenance of sharpness, resistance to bending, and ductility. Because the biomechanical performance of these needles was remarkably similar, cardiovascular needles made of either the Surgalloy or Ethalloy alloys are recommended for cardiovascular surgery. PMID:11495105

  16. Biomechanical energetic analysis of technique during learning the longswing on the high bar.

    Science.gov (United States)

    Williams, Genevieve Kate Roscoe; Irwin, Gareth; Kerwin, David George; Newell, Karl Maxim

    2015-01-01

    Biomechanical energetic analysis of technique can be performed to identify limits or constraints to performance outcome at the level of joint work, and to assess the mechanical efficiency of techniques. The aim of this study was to investigate the biomechanical energetic processes during learning the longswing on the high bar. Twelve male, novice participants took part in a training study. Kinematic and kinetics data were collected during swing attempts in eight weekly testing sessions. Inverse dynamics analysis was performed from known zero forces at the toes. Joint work, total energy, and bar energy were calculated. Biomechanical constraints to action, that is, limits to novice performance, were identified as "total work" and "shoulder work". The most biomechanically efficient technique was associated with an onset of the hip functional phase and joint work that occurred between 10-45° before the bottom of the swing. The learning of gross motor skills is realised through the establishment of a set of techniques with task specific biomechanical constraints. Knowledge of the biomechanical constraints to action associated with more effective and efficient techniques will be useful for both assessing learning and establishing effective learning interventions. PMID:25535648

  17. Beneficial effects of multisensory and cognitive stimulation on age-related cognitive decline in long-term-care institutions

    Directory of Open Access Journals (Sweden)

    Oliveira TCG

    2014-02-01

    Full Text Available Thaís Cristina Galdino De Oliveira,1 Fernanda Cabral Soares,1 Liliane Dias E Dias De Macedo,1 Domingos Luiz Wanderley Picanço Diniz,1 Natáli Valim Oliver Bento-Torres,1,2 Cristovam Wanderley Picanço-Diniz1 1Laboratory of Investigations in Neurodgeneration and Infection, Biological Sciences Institute, University Hospital João de Barros Barreto, 2College of Physical Therapy and Occupational Therapy, Federal University of Pará, Belém, Brazil Abstract: The aim of the present report was to evaluate the effectiveness and impact of multisensory and cognitive stimulation on improving cognition in elderly persons living in long-term-care institutions (institutionalized [I] or in communities with their families (noninstitutionalized [NI]. We compared neuropsychological performance using language and Mini-Mental State Examination (MMSE test scores before and after 24 and 48 stimulation sessions. The two groups were matched by age and years of schooling. Small groups of ten or fewer volunteers underwent the stimulation program, twice a week, over 6 months (48 sessions in total. Sessions were based on language and memory exercises, as well as visual, olfactory, auditory, and ludic stimulation, including music, singing, and dance. Both groups were assessed at the beginning (before stimulation, in the middle (after 24 sessions, and at the end (after 48 sessions of the stimulation program. Although the NI group showed higher performance in all tasks in all time windows compared with I subjects, both groups improved their performance after stimulation. In addition, the improvement was significantly higher in the I group than the NI group. Language tests seem to be more efficient than the MMSE to detect early changes in cognitive status. The results suggest the impoverished environment of long-term-care institutions may contribute to lower cognitive scores before stimulation and the higher improvement rate of this group after stimulation. In conclusion

  18. [Biomechanics of the ankle joint].

    Science.gov (United States)

    Zwipp, H

    1989-03-01

    According to Fick, the tree-dimensional patterns of foot motion are best characterized as jawlike movement. Anatomically and biomechanically, this process represents conjoined, synchronous motion within the three mobile segments of the hindfoot: the ankle joint, the posterior subtalar joint, and the anterior subtalar joint. Foot kinematics can be described more completely if the anterior subtalar joint is defined not only as the talocalcaneal navicular joint, but as including the calcaneocuboid joint, thus representing the transverse joint of the tarsus, i.e., the Chopart joint. The axes of these three joints can be defined precisely. In some parts they represent a screwlike motion, clockwise or counter-clockwise, around the central ligamentous structures (fibulotibial ligament, talocalcaneal interosseous ligament, bifurcate ligament). The individual anatomy and structure of these ligaments provide variations in the degree and direction of foot motion. A precise knowledge of foot kinematics is important in surgical ligament and joint reconstruction and in selective foot arthrodeses.

  19. Biomechanics of knife stab attacks.

    Science.gov (United States)

    Chadwick, E K; Nicol, A C; Lane, J V; Gray, T G

    1999-10-25

    Equipment, materials and methods for the measurement of the biomechanical parameters governing knife stab attacks have been developed and data have been presented that are relevant to the improvement of standards for the testing of stab-resistant materials. A six-camera Vicon motion analysis system was used to measure velocity, and derive energy and momentum during the approach phase of the attack and a specially developed force-measuring knife was used to measure three-dimensional forces and torque during the impact phase. The body segments associated with the knife were modelled as a series of rigid segments: trunk, upper arm, forearm and hand. The velocities of these segments, together with knowledge of the mass distribution from biomechanical tables, allowed the calculation of the individual segment energy and momentum values. The instrumented knife measured four components of load: axial force (along the length of the blade), cutting force (parallel to the breadth of the blade), lateral force (across the blade) and torque (twisting action) using foil strain gauges. Twenty volunteers were asked to stab a target with near maximal effort. Three styles of stab were used: a short thrust forward, a horizontal style sweep around the body and an overhand stab. These styles were chosen based on reported incidents, providing more realistic data than had previously existed. The 95th percentile values for axial force and energy were 1885 N and 69 J, respectively. The ability of current test methods to reproduce the mechanical parameters measured in human stab attacks has been assessed. It was found that current test methods could reproduce the range of energy and force values measured in the human stab attacks, although the simulation was not accurate in some respects. Non-axial force and torque values were also found to be significant in the human tests, but these are not reproduced in the standard mechanical tests.

  20. Forward lunge knee biomechanics before and after partial meniscectomy

    DEFF Research Database (Denmark)

    Hall, Michelle; Nielsen, Jonas Høberg; Holsgaard-Larsen, Anders;

    2015-01-01

    BACKGROUND: Patients following meniscectomy are at increased risk of developing knee osteoarthritis in the tibiofemoral compartment and at the patellofemoral joint. As osteoarthritis is widely considered a mechanical disease, it is important to understand the potential effect of arthroscopic...... partial meniscectomy (APM) on knee joint mechanics. The purpose of this study was to evaluate changes in knee joint biomechanics during a forward lunge in patients with a suspected degenerative meniscal tear from before to three months after APM. METHODS: Twenty-two patients (35-55years old......) with a suspected degenerative medial meniscal tear participated in this study. Three dimensional knee biomechanics were assessed on the injured and contralateral leg before and three months after APM. The visual analogue scale was used to assess knee pain and the Knee Injury Osteoarthritis Outcome Score was used...

  1. Musculoskeletal demands on flamenco dancers: a clinical and biomechanical study.

    Science.gov (United States)

    Bejjani, F J; Halpern, N; Pio, A; Dominguez, R; Voloshin, A; Frankel, V H

    1988-04-01

    The flamenco dancer acts on the floor like a drummer. The percussive footwork and vibration patterns created during dancing impose unusual demands on the musculoskeletal system. This study investigated the clinical and biomechanical aspects of this task. Using the electrodynogram and skin-mounted accelerometers, foot pressures as well as hip and knee vibrations were recorded in 10 female dancers after a thorough clinical evaluation. A health questionnaire was also distributed to 29 dancers. Foot pressures and acceleration data reveal the percussive nature of the dance. Some clinical findings, like calluses, are related to pressure distribution. Urogenital disorders, as well as back and neck pain, may be related to the vibrations generated by the flamenco dance form. The hip joint seems to absorb most of the impacts. "Vibration-pressure" diagrams are suggested as a useful tool for evaluating a dancer's biomechanical behavior, as well as the effect of floors and footwear on this behavior. PMID:3366430

  2. Fertility decline in Paraguay.

    Science.gov (United States)

    Ishida, Kanako; Stupp, Paul; Melian, Mercedes

    2009-09-01

    Recent reproductive health surveys show that the fertility rate in Paraguay decreased precipitously from 4.3 lifetime births per woman in 1995-98 to 2.9 births in 2001-04. In this study, we establish data consistency between the 1998 and 2004 surveys by comparing a series of cohort-specific period rates and use the Bongaarts framework of proximate determinants of fertility to demonstrate that an increase in the contraceptive prevalence rate (CPR) between 1998 and 2004 fully accounts for the fertility decline. Decomposition of rates shows that changes in group-specific CPRs explain a greater proportion of the change in the overall CPR than do changes in population composition by educational attainment, urban residence, region, and language spoken at home. Finally, we show that younger cohorts of women in 2004 reported ideal completed fertility desires of less than 2.9 births, suggesting that the fertility rate is likely to continue to decrease.

  3. Mobility decline in old age

    DEFF Research Database (Denmark)

    Rantakokko, Merja; Mänty, Minna Regina; Rantanen, Taina

    2013-01-01

    Mobility is important for community independence. With increasing age, underlying pathologies, genetic vulnerabilities, physiological and sensory impairments, and environmental barriers increase the risk for mobility decline. Understanding how mobility declines is paramount to finding ways to pro...... to promote mobility in old age.......Mobility is important for community independence. With increasing age, underlying pathologies, genetic vulnerabilities, physiological and sensory impairments, and environmental barriers increase the risk for mobility decline. Understanding how mobility declines is paramount to finding ways...

  4. Decline in breast cancer mortality

    DEFF Research Database (Denmark)

    Njor, Sisse Helle; Schwartz, Walter; Blichert-Toft, Mogens;

    2015-01-01

    OBJECTIVES: When estimating the decline in breast cancer mortality attributable to screening, the challenge is to provide valid comparison groups and to distinguish the screening effect from other effects. In Funen, Denmark, multidisciplinary breast cancer management teams started before screening...... was introduced; both activities came later in the rest of Denmark. Because Denmark had national protocols for breast cancer treatment, but hardly any opportunistic screening, Funen formed a "natural experiment", providing valid comparison groups and enabling the separation of the effect of screening from other...... factors. METHODS: Using Poisson regression we compared the observed breast cancer mortality rate in Funen after implementation of screening with the expected rate without screening. The latter was estimated from breast cancer mortality in the rest of Denmark controlled for historical differences between...

  5. Understanding a migratory species in a changing world: climatic effects and demographic declines in the western monarch revealed by four decades of intensive monitoring.

    Science.gov (United States)

    Espeset, Anne E; Harrison, Joshua G; Shapiro, Arthur M; Nice, Chris C; Thorne, James H; Waetjen, David P; Fordyce, James A; Forister, Matthew L

    2016-07-01

    Migratory animals pose unique challenges for conservation biologists, and we have much to learn about how migratory species respond to drivers of global change. Research has cast doubt on the stability of the eastern monarch butterfly (Danaus plexippus) population in North America, but the western monarchs have not been as intensively examined. Using a Bayesian hierarchical model, sightings of western monarchs over approximately 40 years were investigated using summer flight records from ten sites along an elevational transect in Northern California. Multiple weather variables were examined, including local and regional temperature and precipitation. Population trends from the ten focal sites and a subset of western overwintering sites were compared to summer and overwintering data from the eastern migration. Records showed western overwintering grounds and western breeding grounds had negative trends over time, with declines concentrated early in the breeding season, which were potentially more severe than in the eastern population. Temporal variation in the western monarch also appears to be largely independent of (uncorrelated with) the dynamics in the east. For our focal sites, warmer temperatures had positive effects during winter and spring, and precipitation had a positive effect during spring. These climatic associations add to our understanding of biotic-abiotic interactions in a migratory butterfly, but shifting climatic conditions do not explain the overall, long-term, negative population trajectory observed in our data. PMID:27000943

  6. Effect of recombinant human platelet-derived growth factor-BB-coated sutures on Achilles tendon healing in a rat model: A histological and biomechanical study

    Science.gov (United States)

    Cummings, Stephen H; Grande, Daniel A; Hee, Christopher K; Kestler, Hans K; Roden, Colleen M; Shah, Neil V; Razzano, Pasquale; Dines, David M; Chahine, Nadeen O

    2012-01-01

    Purpose: Repairing tendon injuries with recombinant human platelet-derived growth factor-BB has potential for improving surgical outcomes. Augmentation of sutures, a critical component of surgical tendon repair, by coating with growth factors may provide a clinically useful therapeutic device for improving tendon repair. Therefore, the purpose of this study was to (a) coat Vicryl sutures with a defined dose of recombinant human platelet-derived growth factor-BB without additional coating excipients (e.g. gelatin), (b) quantify the recombinant human platelet-derived growth factor-BB released from the suture, and (c) use the recombinant human platelet-derived growth factor-BB-coated sutures to enhance tendon repair in a rat Achilles tendon transection model. Methods: Vicryl sutures were coated with 0, 0.3, 1.0, and 10.0 mg/mL concentrations of recombinant human platelet-derived growth factor-BB using a dip-coating process. In vitro release was quantified by an enzyme-linked immunosorbent assay. Acutely transected rat Achilles tendons were repaired using one of the four suture groups (n = 12 per group). Four weeks following repair, the tensile biomechanical and histological (i.e. collagen organization and angiogenesis) properties were determined. Results: A dose-dependent bolus release of recombinant human platelet-derived growth factor-BB occurred within the first hour in vitro, followed by a gradual release over 48 h. There was a significant increase in ultimate tensile strength (p < 0.01) in the two highest recombinant human platelet-derived growth factor-BB dose groups (1.9 ± 0.5 and 2.1 ± 0.5 MPa) relative to controls (1.0 ± 0.2 MPa). The modulus significantly increased (p = 0.031) with the highest recombinant human platelet-derived growth factor-BB dose group (7.2 ± 3.8 MPa) relative to all other groups (control: 3.5 ± 0.9 MPa). No significant differences were identified for the maximum load or stiffness. The histological collagen and angiogenesis scores

  7. Biomechanical properties of peripheral nerve after acellular treatment

    Institute of Scientific and Technical Information of China (English)

    MA Xin-long; SUN Xiao-lei; YANG Zhao; LI Xiu-lan; MA Jian-xiong; ZHANG Yang; YUAN Zhen-zhen

    2011-01-01

    Background Peripheral nerve injury causes a high rate of disability and a huge economic burden,and is currently one of the serious health problems in the world.The use of nerve grafts plays a vital role in repairing nerve defects.Acellular nerve grafts have been widely used in many experimental models as a peripheral nerve substitute.The purpose of this study was to test the biomechanical properties of acellular nerve grafts.Methods Thirty-four fresh sciatic nerves were obtained from 17 adult male Wistar rats (age of 3 months) and randomly assigned to 3 groups:normal control group,nerve segments underwent no treatment and were put in phosphate buffered saline (pH 7.4) and stored at 4℃ until further use; physical method group,nerve segments were frozen at -196℃ and then thawed at 37℃; and chemical method group,nerve segments were chemically extracted with the detergents Triton X-200,sulfobetaine-10 (SB-10) and sulfobetaine-16 (SB-16).After the acellularization process was completed,the structural changes of in the sciatic nerves in each group were observed by hematoxylin-eosin staining and field emission scanning electron microscopy,then biomechanical properties were tested using a mechanical apparatus (Endura TEC ELF 3200,Bose,Boston,USA).Results Hematoxylin-eosin staining and field emission scanning electron microscopy demonstrated that the effects of acellularization,demyelination,and integrity of nerve fiber tube of the chemical method were better than that of the physical method.Biomechanical testing showed that peripheral nerve grafts treated with the chemical method resulted in some decreased biomechanical properties (ultimate load,ultimate stress,ultimate strain,and mechanical work to fracture) compared with normal control nerves,but the differences were not statistically significant (P >0.05).Conclusion Nerve treated with the chemical method may be more appropriate for use in implantation than nerve treated with the physical method.

  8. Dynamic biomechanics of the human head in lateral impacts.

    Science.gov (United States)

    Zhang, Jiangyue; Yoganandan, Narayan; Pintar, Frank A

    2009-10-01

    The biomechanical responses of human head (translational head CG accelerations, rotational head accelerations, and HIC) under lateral impact to the parietal-temporal region were investigated in the current study. Free drop tests were conducted at impact velocities ranging from 2.44 to 7.70 m/s with a 40 durometer, a 90 durometer flat padding, and a 90 durometer cylinder. Specimens were isolated from PMHS subjects at the level of occipital condyles, and the intracranial substance was replaced with brain simulant (Sylgard 527). Three tri-axial accelerometers were instrumented at the anterior, posterior, and vertex of the specimen, and a pyramid nine accelerometer package (pNAP) was used at the contra-lateral site. Biomechanical responses were computed by transforming accelerations measured at each location to the head CG. The results indicated significant "hoop effect" from skull deformation. Translational head CG accelerations were accurately measured by transforming the pNAP, the vertex accelerations, or the average of anterior/posterior acceleration to the CG. The material stiffness and structural rigidity of the padding changed the biomechanical responses of the head with stiffer padding resulting in higher head accelerations. At the skull fracture, HIC values were more than 2-3x higher than the frontal skull fracture threshold (HIC=1000), emphasizing the differences between frontal and lateral impact. Rotational head accelerations up to 42.1 krad/s(2) were observed before skull fracture, indicating possible severe brain injury without skull fracture in lateral head impact. These data will help to establish injury criteria and threshold in lateral impacts for improved automotive protection and help clinicians understand the biomechanics of lateral head impact from improved diagnosis.

  9. Drivers and moderators of business decline

    Directory of Open Access Journals (Sweden)

    Marius Pretorius

    2010-12-01

    Full Text Available Purpose: Reports of business failure elicit various reactions, while research in this domain often appears to be limited by a lack of access to information about failure and by the negativity that surrounds it. Those who have experienced failure do not readily talk about it, or they disappear from the radar screen of researchers. Yet failure is preceded by decline which, when focused on strategically, can reduce eventual failures if early action is taken. The main purpose of this study is to develop a conceptual framework or typology of the drivers and moderators of business decline. Design/methodology/approach: After applying the "grounded theory" approach to the academic literature on decline and failure, a conceptual framework for the variables that drive and moderate business decline is proposed. Findings: The study proposes that decline has three core drivers, three peripheral drivers and four moderators. The core drivers identified are: resource munificence; leadership as origin; and causality (strategic versus operational origin of decline. The three peripheral drivers are: unique preconditions; continuous decisions impact; and extremes dichotomy. The study describes four moderators of the drivers: life cycle stage; stakeholder perspective; quantitative versus qualitative nature of signs and causes; and finally the age and size effects. Research limitations/implications: The proposed conceptual framework is based on literature only, although it has found support during discussions with practitioners. It is proposed to readers of this journal for scrutiny and validation. Practical implications: Strategists need to understand what drives decline in order to act timeously; practitioners who have an insight into the moderators with their impacts could make better decisions in response to decline in organisations and possibly avoid business failure. Originality/Value: Understanding business decline is still a huge theoretical challenge, which

  10. Biomechanical Properties of Bone and Biomechanics of Age - Related Fractures - Review

    Directory of Open Access Journals (Sweden)

    Rezzan Günaydın

    2007-06-01

    Full Text Available From a biomechanical viewpoint, fractures are due to a structural failure of the bone. This failure occurs when the forces applied to the bone exceed its load – bearing capacity. The load – bearing capacity of a bone depends on the geometry (its size, shape and distribution of bone mass, and the material properties of a bone as well as the direction and magnitude of applied load. Bone fragility can be defined by biomechanical parameters such as strength, brittleness and work to failure. Strategies to reduce fracture risk must be based on a sound understanding of the cellular, molecular and biomechanical mechanisms that underlie the increased risk of fractures while aging. In this review biomechanics of bone and the etiology of age – related fractures from a biomechanical viewpoint have been discussed in the view of current literature. (From the World of Osteoporosis 2007;13:44-8

  11. Effects of Hospital-Based Physical Therapy on Hospital Discharge Outcomes among Hospitalized Older Adults with Community-Acquired Pneumonia and Declining Physical Function

    OpenAIRE

    Kim, Sun Jung; Lee, Joo Hun; Han, Boram; Lam, Julia; Bukowy, Elizabeth; Rao, Avinash; Vulcano, Jordan; Andreeva, Anelia; Bertelson, Heather; Shin, Hyun Phil; Yoo, Ji Won

    2015-01-01

    To examine whether hospital-based physical therapy is associated with functional changes and early hospital readmission among hospitalized older adults with community-acquired pneumonia and declining physical function. Study design was a retrospective observation study. Participants were community-dwelling older adults admitted to medicine floor for community-acquired pneumonia (n = 1,058). Their physical function using Katz activities of daily living (ADL) Index declined between hospital adm...

  12. SPORT AND EXERCISE BIOMECHANICS (BIOS INSTANT NOTES

    Directory of Open Access Journals (Sweden)

    Paul Grimshaw

    2007-06-01

    Full Text Available DESCRIPTION Instant Notes on Sport and Exercise Biomechanics provides a broad overview of the fundamental concepts in exercise and sport biomechanics. PURPOSE The book aims to provide instant notes on essential information about biomechanics, and is designed to help undergraduate students to grasp the corresponding subjects in physical effort rapidly and easily. AUDIENCE The book provides a useful resource for undergraduate and graduate students as a fundamental reference book. For the researcher and lecturer it would be a starting point to plan and prepare more detailed experimental designs or lecture and/or laboratory classes in the field of exercise and sport biomechanics. It would also be interest to anyone who wonders the concepts like momentum possessed, whole body angular momentum, opposite parallel forces, superman position, parabolic flight path, joint/normal reaction force, etc. FEATURES This textbook is divided into following sections from A to F: kinematics of motion, kinetics of linear motion, kinetics of angular motion, special topics, applications and measurement techniques, respectively. In sub-sections the kinematics of motion are reviewed in detail, outlining the physics of motion. Furthermore, the discussions of mechanical characteristics of motion, the mechanisms of injury, and the analysis of the sport technique provide a source of valuable information for both students and lecturers in appropriate fields. ASSESSMENT This book is an important reading for biomechanics students, teachers and even researchers as well as anyone interested in understanding motion.

  13. Biomechanics and physiology in active manual wheelchair propulsion

    NARCIS (Netherlands)

    van der Woude, L H; Veeger, DirkJan (H. E. J.); Dallmeijer, A J; Janssen, T W; Rozendaal, L A

    2001-01-01

    Manual wheelchair propulsion in daily life and sports is increasingly being studied. Initially, an engineering and physiological perspective was taken. More recently a concomitant biomechanics interest is seen. Themes of biomechanical and physiological studies today are performance enhancing aspects

  14. A survey on stochastic multi-scale modeling in biomechanics: computational challenges

    CERN Document Server

    Favino, Marco; Pivkin, Igor

    2016-01-01

    During the last decade, multi-scale models in mechanics, bio-mechanics and life sciences have gained increasing attention. Using multi-scale approaches, effects on different time and length scales, such as, e.g., cellular and organ scale, can be coupled and their interaction can be studied. Clearly, this requires the development of new mathematical models and numerical methods for multi-scale problems, in order to provide reliable and efficient tools for the investigation of multi-scale effects. Here, we give an overview on existing numerical approaches for multi-scale simulations in bio-mechanics with particular emphasis on stochastic effects.

  15. Problems Associated with Declining National Oil Production

    Science.gov (United States)

    Jackson, J. S.

    2009-12-01

    Forecasts of peak oil production have focussed on the global impacts of declining production. Meanwhile, national oil production has declined in 20 countries, leading to local problems that receive little comment outside of the effected regions. Two problems deserve wider recognition: declining state revenues and fuel substitution. Most oil producing countries with large reserves adopted licensing practices that provide significant revenues to the host governments such that oil revenues generate from 40 to 80 percent of total government funds. Typically these governments allocate a fraction of this revenue to their state oil companies, utilizing the remainder for other activities. As oil revenues decline with falling production, host governments face a dilemma: either to increase state oil company budgets in order to stem the decline, or to starve the state oil company while maintaining other government programs. The declining oil revenues in these states can significantly reduce the government's ability to address important national issues. Mexico, Indonesia, and Yemen illustrate this situation in its early phases. Fuel substitution occurs whenever one fuel proves less expensive than another. The substitution of coal for wood in the eighteenth century and oil for coal in the twentieth century are classic examples. China and India appear to be at peak oil production, while their economies generate increasing demand for energy. Both countries are substituting coal and natural gas for oil with attendant environmental impacts. Coal-to-liquids projects are proposed in in both China, which will require significant water resources if they are executed. These examples suggest that forecasting the impact of peak oil at a regional level requires more than an assessment of proven-probable-possible reserves and a forecast of supply-demand scenarios. A range of government responses to declining oil income scenarios must also be considered, together with scenarios describing

  16. Modelling the learning of biomechanics and visual planning for decision-making of motor actions.

    Science.gov (United States)

    Cos, Ignasi; Khamassi, Mehdi; Girard, Benoît

    2013-11-01

    Recent experiments showed that the bio-mechanical ease and end-point stability associated to reaching movements are predicted prior to movement onset, and that these factors exert a significant influence on the choice of movement. As an extension of these results, here we investigate whether the knowledge about biomechanical costs and their influence on decision-making are the result of an adaptation process taking place during each experimental session or whether this knowledge was learned at an earlier stage of development. Specifically, we analysed both the pattern of decision-making and its fluctuations during each session, of several human subjects making free choices between two reaching movements that varied in path distance (target relative distance), biomechanical cost, aiming accuracy and stopping requirement. Our main result shows that the effect of biomechanics is well established at the start of the session, and that, consequently, the learning of biomechanical costs in decision-making occurred at an earlier stage of development. As a means to characterise the dynamics of this learning process, we also developed a model-based reinforcement learning model, which generates a possible account of how biomechanics may be incorporated into the motor plan to select between reaching movements. Results obtained in simulation showed that, after some pre-training corresponding to a motor babbling phase, the model can reproduce the subjects' overall movement preferences. Although preliminary, this supports that the knowledge about biomechanical costs may have been learned in this manner, and supports the hypothesis that the fluctuations observed in the subjects' behaviour may adapt in a similar fashion.

  17. 4th International Plant Biomechanics Conference Proceedings (Abstracts)

    Energy Technology Data Exchange (ETDEWEB)

    Frank W. Telewski; Lothar H. Koehler; Frank W. Ewers

    2003-07-20

    The 4th International Plant Biomechanics Conference facilitated an interdisciplinary exchange between scientists, engineers, and educators addressing the major questions encountered in the field of Plant Biomechanics. Subjects covered by the conference include: Evolution; Ecology; Mechanoreception; Cell Walls; Genetic Modification; Applied Biomechanics of Whole Plants, Plant Products, Fibers & Composites; Fluid Dynamics; Wood & Trees; Fracture Mechanics; Xylem Pressure & Water Transport; Modeling; and Introducing Plant Biomechanics in Secondary School Education.

  18. Biomechanical Analysis of the Swim-Start: A Review

    OpenAIRE

    Julien Vantorre, Didier Chollet, Ludovic Seifert

    2014-01-01

    This review updates the swim-start state of the art from a biomechanical standpoint. We review the contribution of the swim-start to overall swimming performance, the effects of various swim-start strategies, and skill effects across the range of swim-start strategies identified in the literature. The main objective is to determine the techniques to focus on in swimming training in the contemporary context of the sport. The phases leading to key temporal events of the swim-start, like water e...

  19. Sixth Computational Biomechanics for Medicine Workshop

    CERN Document Server

    Nielsen, Poul MF; Miller, Karol; Computational Biomechanics for Medicine : Deformation and Flow

    2012-01-01

    One of the greatest challenges for mechanical engineers is to extend the success of computational mechanics to fields outside traditional engineering, in particular to biology, biomedical sciences, and medicine. This book is an opportunity for computational biomechanics specialists to present and exchange opinions on the opportunities of applying their techniques to computer-integrated medicine. Computational Biomechanics for Medicine: Deformation and Flow collects the papers from the Sixth Computational Biomechanics for Medicine Workshop held in Toronto in conjunction with the Medical Image Computing and Computer Assisted Intervention conference. The topics covered include: medical image analysis, image-guided surgery, surgical simulation, surgical intervention planning, disease prognosis and diagnostics, injury mechanism analysis, implant and prostheses design, and medical robotics.

  20. Multiscale modeling in biomechanics and mechanobiology

    CERN Document Server

    Hwang, Wonmuk; Kuhl, Ellen

    2015-01-01

    Presenting a state-of-the-art overview of theoretical and computational models that link characteristic biomechanical phenomena, this book provides guidelines and examples for creating multiscale models in representative systems and organisms. It develops the reader's understanding of and intuition for multiscale phenomena in biomechanics and mechanobiology, and introduces a mathematical framework and computational techniques paramount to creating predictive multiscale models.   Biomechanics involves the study of the interactions of physical forces with biological systems at all scales – including molecular, cellular, tissue and organ scales. The emerging field of mechanobiology focuses on the way that cells produce and respond to mechanical forces – bridging the science of mechanics with the disciplines of genetics and molecular biology. Linking disparate spatial and temporal scales using computational techniques is emerging as a key concept in investigating some of the complex problems underlying these...

  1. Afterword: The Management and Consequences of Decline.

    Science.gov (United States)

    Boyd, William Lowe

    1983-01-01

    Stresses the need for aggressive, farsighted management of decline and for more Federal and State aid to local school administrators to combat the negative effects of school closures and retrenchment, and to ensure that retrenched school systems still serve children effectively. (Author/MJL)

  2. Analysis of Biomechanical Factors in Bend Running

    Directory of Open Access Journals (Sweden)

    Bing Zhang

    2013-03-01

    Full Text Available Sprint running is the demonstration of comprehensive abilities of technology and tactics, under various conditions. However, whether it is just to allocate the tracks for short-distance athletes from different racetracks has been the hot topic. This study analyzes its forces, differences in different tracks and winding influences, in the aspects of sport biomechanics. The results indicate, many disadvantages exist in inner tracks, middle tracks are the best and outer ones are inferior to middle ones. Thus it provides references for training of short-distance items in biomechanics and psychology, etc.

  3. Protocol for Project FACT: A randomised controlled trial on the effect of a walking program and vitamin B supplementation on the rate of cognitive decline and psychosocial wellbeing in older adults with mild cognitive impairment

    NARCIS (Netherlands)

    Uffelen, J.G.Z. van; Hopman-Rock, M.; Chin A Paw, M.J.M.; Mechelen, W. van

    2005-01-01

    Background: the prevalence of individuals with cognitive decline is increasing since the number of elderly adults is growing considerably. The literature provides promising results on the beneficial effect of exercise and vitamin supplementation on cognitive function both in cognitively healthy as w

  4. Protocol for project FACT: a randomised controlled trial on the effect of a walking program and vitamin B supplementation on the rate of cognitive decline and psychosocial wellbeing in older adults with mild cognitive impairment [ISRCTN19227688

    NARCIS (Netherlands)

    Uffelen, van J.G.Z.; Hopman-Rock, M.; Chin A Paw, M.J.M.; Mechelen, van W.

    2005-01-01

    ABSTRACT: BACKGROUND: The prevalence of individuals with cognitive decline is increasing since the number of elderly adults is growing considerably. The literature provides promising results on the beneficial effect of exercise and vitamin supplementation on cognitive function both in cognitively he

  5. Biomechanical evaluation of wrist-driven flexor hinge orthosis in persons with spinal cord injury

    Directory of Open Access Journals (Sweden)

    Yeoun-Seung Kang, MD, PhD, CPO

    2013-11-01

    Full Text Available The wrist-driven flexor hinge orthosis (WDFHO is a device used to restore hand function in persons with tetraplegic spinal cord injury by furnishing three-point prehension. We assessed the effectiveness and biomechanical properties of the WDFHO in 24 persons with cervical 6 or 7 tetraplegia who have severely impaired hand function. This study introduces a mechanical operating model to assess the efficiency of the WDFHO. Experimental results showed that pinch force increased significantly (p < 0.001 after using the WDFHO and was found to positively correlate with the strength of wrist extensor muscles (r = 0.41, p < 0.001. However, when the strength of the wrist extensors acting on the WDFHO was greater, the reciprocal wrist and finger motion that generates three-point prehension was less effective (r = 0.79, p < 0.001. Reliable and valid biomechanical evaluation of the WDFHO could improve our understanding of its biomechanics.

  6. Mobility decline in old age

    OpenAIRE

    Rantakokko, Merja; Mänty, Minna; Rantanen, Taina

    2013-01-01

    Mobility is important for community independence. With increasing age, underlying pathologies, genetic vulnerabilities, physiological and sensory impairments, and environmental barriers increase the risk for mobility decline. Understanding how mobility declines is paramount to finding ways to promote mobility in old age.

  7. Biomechanical progress of fatigue effect on non-contact anterior cruciate ligament injury%疲劳因素影响膝关节前交叉韧带的非接触性损伤生物力学

    Institute of Scientific and Technical Information of China (English)

    刘海瑞; 伍勰; 吴瑛

    2014-01-01

    BACKGROUND:Anterior cruciate ligament injury can trigger knee instability, knee osteoarthritis which decreases human beings’ life quality. Exploration on non-contact anterior cruciate ligament injury mechanism can prevent the occurrence of anterior cruciate ligament injury. OBJECTIVE:To investigate the mechanism of fatigue effect on non-contact anterior cruciate ligament injury and to introduce the progression of fatigue effect on non-contact anterior cruciate ligament injury in jump-landing activities. METHODS:The author retrieved the PubMed database from 1988 to 2013 by computer. The key words were set as:ACL, landing, and fatigue. A total of 42 articles were included which related to biomechanics research on anterior cruciate ligament injury, fatigue landing and low-limb injury. RESULTS AND CONCLUSION:In jump-landing activities, knee valgus, moment, knee joint rotation and smal er knee flexion are main biomechanics underlying non-contact anterior cruciate ligament injury. In addition, fatigue effect is another critical factor for non-contact anterior cruciate ligament injury. However, the cause-effect between fatigue effect and anterior cruciate ligament injury is not clearly investigated and summarized, especial y on fatigue level, fatigue induction and movement control. Introduction of fatigue induction is crucial for better understanding how fatigue effect results in anterior cruciate ligament injury. Thus, the quantification of fatigue level, fatigue models and landing ways wil provide new ideas for exploring biomechanical mechanism underlying anterior cruciate ligament injury in fatigue state, as wel as provide more information on intervention design and injury rehabilitation.%背景:膝关节前交叉韧带的损伤会触发膝关节的其他损伤,如慢性膝关节不稳,骨关节炎等。梳理非接触性膝关节前交叉韧带损伤有助于掌握损伤机制,降低损伤发病率。  目的:对膝关节前交叉韧带非接触性

  8. Biomechanics of the press-fit phenomenon in dental implantology: an image-based finite element analysis

    OpenAIRE

    Frisardi Gianni; Barone Sandro; Razionale Armando V; Paoli Alessandro; Frisardi Flavio; Tullio Antonio; Lumbau Aurea; Chessa Giacomo

    2012-01-01

    Abstract Background A fundamental pre-requisite for the clinical success in dental implant surgery is the fast and stable implant osseointegration. The press-fit phenomenon occurring at implant insertion induces biomechanical effects in the bone tissues, which ensure implant primary stability. In the field of dental surgery, the understanding of the key factors governing the osseointegration process still remains of utmost importance. A thorough analysis of the biomechanics of dental implanto...

  9. Terminal decline in motor function.

    Science.gov (United States)

    Wilson, Robert S; Segawa, Eisuke; Buchman, Aron S; Boyle, Patricia A; Hizel, Loren P; Bennett, David A

    2012-12-01

    The study aim was to test the hypothesis that motor function undergoes accelerated decline proximate to death. As part of a longitudinal clinical-pathologic study, 124 older Roman Catholic nuns, priests, and monks completed at least 7 annual clinical evaluations, died, and underwent brain autopsy and uniform neuropathologic examination. Each evaluation included administration of 11 motor tests and 19 cognitive tests from which global measures of motor and cognitive function were derived. The global motor measure (baseline M = 0.82, SD = 0.21) declined a mean 0.024 unit per year (95% confidence interval [CI]: -0.032, -0.016) until a mean of 2.46 years (95% CI: -2.870, -2.108) before death when rate of decline increased nearly fivefold to -0.117 unit per year (95% CI: -0.140, -0.097). The global cognitive measure (baseline M = 0.07, SD = 0.45) declined a mean of 0.027-unit per year (95% CI: -0.041, -0.014) until a mean of 2.76 years (95% CI: -3.157, -2.372) before death when rate of decline increased more than 13-fold to -0.371 unit per year (95% CI: -0.443, -0.306). Onset of terminal motor decline was highly correlated with onset of terminal cognitive decline (r = .94, 95% CI: 0.81, 0.99), but rates of motor and cognitive change were not strongly correlated (preterminal r = .20, 95% CI: -0.05, 0.38; terminal r = .34, 95% CI: 0.03, 0.62). Higher level of plaques and tangles was associated with earlier onset of terminal decline in motor function, but no pathologic measures were associated with rate of preterminal or terminal motor decline. The results demonstrate that motor and cognitive functions both undergo a period of accelerated decline in the last few years of life. PMID:22612603

  10. Biomechanical characteristics of the eccentric Achilles tendon exercise

    DEFF Research Database (Denmark)

    Henriksen, Marius; Aaboe, Jens; Bliddal, Henning;

    2009-01-01

    into the biomechanics of the exercise may improve our understanding. METHODS: Sixteen healthy subjects performed one-legged full weight bearing ankle plantar and dorsiflexion exercises during which three-dimensional ground reaction forces (GRF), ankle joint kinematics and surface electromyography (EMG) of the lower leg...... that although the tendon loads are similar, the tendon is vibrated at higher frequencies during the eccentric phase than during the concentric phases. This study provides data that may explain the mechanisms behind the effectiveness of eccentric exercises used in the treatment of Achilles tendinopathies....

  11. 有氧运动配合雷洛昔芬对骨生物力学性能影响的研究%Aerobic Exercise Combined with Effects of Raloxifene on Bone Biomechanical Properties

    Institute of Scientific and Technical Information of China (English)

    谢江涛; 罗珊

    2014-01-01

    目的:通过对去势大鼠骨生物力学指标的检测,探讨有氧运动与雷洛昔芬联合作用对去势大鼠骨生物力学性能的影响。方法:将50只雌性SD大鼠随机分为5组:假手术组、模型组、有氧运动组、雷洛昔芬组、有氧运动+雷洛昔芬组。假手术组不去卵巢,其余各组去卵巢造模;有氧运动组、雷洛昔芬组、有氧运动+雷洛昔芬组分别在去卵巢的基础上进行有氧运动训练和(或)灌胃选择性雌激素受体调节剂雷洛昔芬。8周后比较各组大鼠股骨结构力学和材料力学指标的变化。结果:(1)与模型组相比,有氧运动组、雷洛昔芬组、有氧运动+雷洛昔芬组大鼠的各项指标都显著优于模型组(P<0.05),部分指标出现显著性差异(P<0.01)。(2)模型组各项指标都与假手术组有显著性差别(P<0.05)。结论:有氧运动配合雷洛昔芬治疗联合应用预防废用性骨质疏松比单独应用能获得更好的效果;并且更加安全易行。%Objective: ovariectomized rats bone biomechanical indicators detect, investigate the combined effects of aerobic exercise and raloxifene on ovariectomized rats bone biomechanical properties. Methods: 50 female SD rats were randomly divided into five groups: sham operation group, model group, aerobic exercise group, the raloxifene group, aerobic exercise + raloxifene group. Sham group only surgery but not ovariectomy, the rest of the group of ovariectomized modeling; aerobic exercise group, the raloxifene group aerobic exercise + raloxifene groups, respectively, based on ovariectomized aerobic exercise training and (or) orally selective estrogen receptor modulator raloxifene. After eight weeks, comparing changes in the rat femur structural mechanics and material mechanics index. Results: (1) Compared with model group, the aerobic exercise group, raloxifene group, the indicators of aerobic exercise + raloxifene rats

  12. A Biomechanical Analysis of the Karate Chop.

    Science.gov (United States)

    Cavanagh, Peter R.; Landa, Jean

    Although the sport of karate has been somewhat neglected by scientists, the following two isolated biomechanical studies exist in literature: (1) tracings of a karate chop in two planes were presented, but no data was given concerning the rates of movement of the limb segments, and (2) pre- and postimpact phenomena of five subjects were studied,…

  13. Biomechanics of Pediatric Manual Wheelchair Mobility.

    Science.gov (United States)

    Slavens, Brooke A; Schnorenberg, Alyssa J; Aurit, Christine M; Tarima, Sergey; Vogel, Lawrence C; Harris, Gerald F

    2015-01-01

    Currently, there is limited research of the biomechanics of pediatric manual wheelchair mobility. Specifically, the biomechanics of functional tasks and their relationship to joint pain and health is not well understood. To contribute to this knowledge gap, a quantitative rehabilitation approach was applied for characterizing upper extremity biomechanics of manual wheelchair mobility in children and adolescents during propulsion, starting, and stopping tasks. A Vicon motion analysis system captured movement, while a SmartWheel simultaneously collected three-dimensional forces and moments occurring at the handrim. A custom pediatric inverse dynamics model was used to evaluate three-dimensional upper extremity joint motions, forces, and moments of 14 children with spinal cord injury (SCI) during the functional tasks. Additionally, pain and health-related quality of life outcomes were assessed. This research found that joint demands are significantly different amongst functional tasks, with greatest demands placed on the shoulder during the starting task. Propulsion was significantly different from starting and stopping at all joints. We identified multiple stroke patterns used by the children, some of which are not standard in adults. One subject reported average daily pain, which was minimal. Lower than normal physical health and higher than normal mental health was found in this population. It can be concluded that functional tasks should be considered in addition to propulsion for rehabilitation and SCI treatment planning. This research provides wheelchair users and clinicians with a comprehensive, biomechanical, mobility assessment approach for wheelchair prescription, training, and long-term care of children with SCI. PMID:26442251

  14. Interdisciplinary Vertical Integration: The Future of Biomechanics

    Science.gov (United States)

    Gregor, Robert J.

    2008-01-01

    The field of biomechanics has grown rapidly in the past 30 years in both size and complexity. As a result, the term might mean different things to different people. This article addresses the issues facing the field in the form of challenges biomechanists face in the future. Because the field is so diverse, strength within the different areas of…

  15. Expose Mechanical Engineering Students to Biomechanics Topics

    Science.gov (United States)

    Shen, Hui

    2011-01-01

    To adapt the focus of engineering education to emerging new industries and technologies nationwide and in the local area, a biomechanics module has been developed and incorporated into a mechanical engineering technical elective course to expose mechanical engineering students at ONU (Ohio Northern University) to the biomedical engineering topics.…

  16. The biomechanical interaction between horse and rider

    NARCIS (Netherlands)

    Cocq, de P.

    2012-01-01

    The forces exerted by a rider on a horse have a direct influence on the mechanical load experienced by the horse and consequently on its motion pattern. The aim of this thesis is to explore the biomechanical interaction between rider, saddle and horse in order to get insight in the loading of the ho

  17. Ultrasonographic assessment of carpal tunnel biomechanics

    NARCIS (Netherlands)

    van Doesburg, M.H.M.

    2012-01-01

    In this thesis, we searched for a way to assess flexor tendon and median nerve biomechanics, as well as subsynovial connective tissue thickness (SSCT) in the carpal tunnel with ultrasound, and tried to see if these patterns would give a clue towards understanding the etiology of carpal tunnel syndro

  18. The Value of Biomechanical Research in Dance.

    Science.gov (United States)

    Ranney, D. A.

    Simple observation of dance movement, while very useful, can lead to misconceptions, about the physical realities of dance movement, that make learning difficult. This gap between reality and understanding can be reduced by the application of biomechanical techniques such as cinematography, electromyography, and force-plate analysis. Biomechanical…

  19. Effects of decline in renal function with age on the outcome of asymptomatic carotid plaque in healthy adults:a 5-year follow-up study

    Institute of Scientific and Technical Information of China (English)

    JIANG Shi-min; SUN Xue-feng; GU Hong-xia; CHEN Yun-shuang; XI Chun-sheng; QIAO Xi; CHEN Xiang-mei

    2012-01-01

    Background It has been long suggested that abnormal clinical factors in the body,such as dyslipidemia and diabetes.can affect the presence of atherosclerosis.However,few studies on the effect of factors within the normal range,such as the loss of renal function with age,on the prevalence of atherosclerosis are few know in healthy individuals.The aim of this study was to investigate risk factors affecting the presence of asymptomatic carotid plaques in a middle-aged and elderly healthy population.Methods In this regard,we prospectively evaluated 245 healthy individuals (98 males and 147 females) at baseline and after 5 years.Changes in the presence of carotid plaque between 2003 and 2008 were categorized into four groups,i.e.subjects without plaque at entry (n=165):Group 1 (without plaque on two occasions,n=129) and Group 2 (with nascent plaque at follow-up,n=36); subjects with plaque at entry (n=80); Group 3 (with plaque regression at follow-up,n=29) and Group 4 (with plaque on two occasions,n=51).Results Univariate analysis showed that the positive rate of carotid plaques in males was higher than that in females at the baseline,and that a significantly inverse correlation existed between the prevalence rate of plaque and aging.Logistic regression analysis of cross-sectional research showed that independent risk factors for the prevalence of atherosclerosis were male gender,lower estimated glomerular filtration rate (eGFR) and higher low-density lipoprotein cholesterol (LDL-C) at the baseline,and older age and lower eGFR were involved in the presence of carotid plaques at follow-up point.However,logistic regression analysis of the longitudinal data showed that older age,decreased eGFR and increased systolic blood pressure (SBP) independently predicted the presence of carotid plaques after 5 years in subjects without plaque at entry.In addition,in subjects with plaque at entry,age,changes in eGFR and the baseline levels of serum albumin (ALB) and serum total

  20. Periodontitis and Cognitive Decline in Alzheimer's Disease.

    Science.gov (United States)

    Ide, Mark; Harris, Marina; Stevens, Annette; Sussams, Rebecca; Hopkins, Viv; Culliford, David; Fuller, James; Ibbett, Paul; Raybould, Rachel; Thomas, Rhodri; Puenter, Ursula; Teeling, Jessica; Perry, V Hugh; Holmes, Clive

    2016-01-01

    Periodontitis is common in the elderly and may become more common in Alzheimer's disease because of a reduced ability to take care of oral hygiene as the disease progresses. Elevated antibodies to periodontal bacteria are associated with an increased systemic pro-inflammatory state. Elsewhere raised serum pro-inflammatory cytokines have been associated with an increased rate of cognitive decline in Alzheimer's disease. We hypothesized that periodontitis would be associated with increased dementia severity and a more rapid cognitive decline in Alzheimer's disease. We aimed to determine if periodontitis in Alzheimer's disease is associated with both increased dementia severity and cognitive decline, and an increased systemic pro inflammatory state. In a six month observational cohort study 60 community dwelling participants with mild to moderate Alzheimer's Disease were cognitively assessed and a blood sample taken for systemic inflammatory markers. Dental health was assessed by a dental hygienist, blind to cognitive outcomes. All assessments were repeated at six months. The presence of periodontitis at baseline was not related to baseline cognitive state but was associated with a six fold increase in the rate of cognitive decline as assessed by the ADAS-cog over a six month follow up period. Periodontitis at baseline was associated with a relative increase in the pro-inflammatory state over the six month follow up period. Our data showed that periodontitis is associated with an increase in cognitive decline in Alzheimer's Disease, independent to baseline cognitive state, which may be mediated through effects on systemic inflammation.

  1. Periodontitis and Cognitive Decline in Alzheimer's Disease.

    Directory of Open Access Journals (Sweden)

    Mark Ide

    Full Text Available Periodontitis is common in the elderly and may become more common in Alzheimer's disease because of a reduced ability to take care of oral hygiene as the disease progresses. Elevated antibodies to periodontal bacteria are associated with an increased systemic pro-inflammatory state. Elsewhere raised serum pro-inflammatory cytokines have been associated with an increased rate of cognitive decline in Alzheimer's disease. We hypothesized that periodontitis would be associated with increased dementia severity and a more rapid cognitive decline in Alzheimer's disease. We aimed to determine if periodontitis in Alzheimer's disease is associated with both increased dementia severity and cognitive decline, and an increased systemic pro inflammatory state. In a six month observational cohort study 60 community dwelling participants with mild to moderate Alzheimer's Disease were cognitively assessed and a blood sample taken for systemic inflammatory markers. Dental health was assessed by a dental hygienist, blind to cognitive outcomes. All assessments were repeated at six months. The presence of periodontitis at baseline was not related to baseline cognitive state but was associated with a six fold increase in the rate of cognitive decline as assessed by the ADAS-cog over a six month follow up period. Periodontitis at baseline was associated with a relative increase in the pro-inflammatory state over the six month follow up period. Our data showed that periodontitis is associated with an increase in cognitive decline in Alzheimer's Disease, independent to baseline cognitive state, which may be mediated through effects on systemic inflammation.

  2. Periodontitis and Cognitive Decline in Alzheimer's Disease.

    Science.gov (United States)

    Ide, Mark; Harris, Marina; Stevens, Annette; Sussams, Rebecca; Hopkins, Viv; Culliford, David; Fuller, James; Ibbett, Paul; Raybould, Rachel; Thomas, Rhodri; Puenter, Ursula; Teeling, Jessica; Perry, V Hugh; Holmes, Clive

    2016-01-01

    Periodontitis is common in the elderly and may become more common in Alzheimer's disease because of a reduced ability to take care of oral hygiene as the disease progresses. Elevated antibodies to periodontal bacteria are associated with an increased systemic pro-inflammatory state. Elsewhere raised serum pro-inflammatory cytokines have been associated with an increased rate of cognitive decline in Alzheimer's disease. We hypothesized that periodontitis would be associated with increased dementia severity and a more rapid cognitive decline in Alzheimer's disease. We aimed to determine if periodontitis in Alzheimer's disease is associated with both increased dementia severity and cognitive decline, and an increased systemic pro inflammatory state. In a six month observational cohort study 60 community dwelling participants with mild to moderate Alzheimer's Disease were cognitively assessed and a blood sample taken for systemic inflammatory markers. Dental health was assessed by a dental hygienist, blind to cognitive outcomes. All assessments were repeated at six months. The presence of periodontitis at baseline was not related to baseline cognitive state but was associated with a six fold increase in the rate of cognitive decline as assessed by the ADAS-cog over a six month follow up period. Periodontitis at baseline was associated with a relative increase in the pro-inflammatory state over the six month follow up period. Our data showed that periodontitis is associated with an increase in cognitive decline in Alzheimer's Disease, independent to baseline cognitive state, which may be mediated through effects on systemic inflammation. PMID:26963387

  3. The Decline of Direct Newspaper Competition.

    Science.gov (United States)

    Rosse, James N.

    1980-01-01

    Describes the decline of direct newspaper competition in terms of the loss of effective newspaper market segmentation. Examines the following influences on market segmentation: shift in advertising demand, advertiser preferences for differentiated audiences, shift in subscriber demand, growth of alternative media, increasing production costs, and…

  4. The biomechanics of the equine foot as it pertains to farriery.

    Science.gov (United States)

    Eliashar, Ehud

    2012-08-01

    Shoes were originally applied to horses' feet to protect against excessive wear. Over the years, countless types of shoes and farriery techniques have been developed not only as a therapeutic aid to treat lameness but also to maintain or enhance functionality. The past 3 decades have provided equine veterinarians and farriers with new information relating to limb biomechanics and the effects of various farriery methods. This article describes the principles of foot biomechanics and how they are affected by some of the more common farriery and shoeing techniques. PMID:22981190

  5. Hangman's fracture: a historical and biomechanical perspective.

    Science.gov (United States)

    Rayes, Mahmoud; Mittal, Monika; Rengachary, Setti S; Mittal, Sandeep

    2011-02-01

    The execution technique of hanging, introduced by the Angle, Saxon, and Jute Germanic tribes during their invasions of the Roman Empire and Britain in the 5th century, has remained largely unchanged over time. The earliest form of a gallows was a tree on which prisoners were hanged. Despite the introduction of several modifications such as a trap door, the main mechanism of death remained asphyxiation. This created the opportunity for attempted revival after the execution, and indeed several well-known cases of survival following judicial hanging have been reported. It was not until the introduction of the standard drop by Dr. Samuel Haughton in 1866, and the so-called long drop by William Marwood in 1872 that hanging became a standard, humane means to achieve instantaneous death. Hangmen, however, fearing knot slippage, started substituting the subaural knot for the traditional submental knot. Subaural knots were not as effective, and cases of decapitation were recorded. Standardization of the long drop was further propagated by John Berry, an executioner who used mathematical calculations to estimate the correct drop length for each individual to be hanged. A British committee on capital sentences, led by Lord Aberdare, studied the execution method, and advocated for the submental knot. However, it was not until Frederic Wood-Jones published his seminal work in 1913 that cervical fractures were identified as the main mechanism of death following hanging in which the long drop and a submental knot were used. Schneider introduced the term "hangman's fracture" in 1965, and reported on the biomechanics and other similarities of the cervical fractures seen following judicial hangings and those caused by motor vehicle accidents.

  6. Pharmacological Effect of EPF on Biomechanical Properties among Ovariectomized Rats%淫羊藿黄酮对去势大鼠骨生物力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    陈鹏; 刘文和; 颜林淋; 陈家玉; 胡伟文; 曹锡文; 李杨

    2014-01-01

    物力学性能的降低,使其维持在较高水平。%This study was aimed to explore pharmacological effects of epimedium pubescen flavonoid (EPF) on biomechanical properties among ovariectomized rats. Sixty female Sprague-Dawley (SD) rats (aged 2-month-old) were randomly divided into six groups (n = 10), which were the sham control group (Group A), the model group (GroupB), the standard group (Group C), the treated 1 group (Group D), the treated 2 group (Group E), and the treated 3 group (Group F). Except the sham control group (Group A), rats in other groups had been ovariectomized. All rats were given the same feedstuff. Meanwhile, Group C was given calcium 75 mg·kg-1 combined with VitD3 21 IU·kg-1 by gastrogavage every day for 4 months; Group D was given EPF 75 mg·kg-1; Group E was given EPF 150 mg·kg-1;Group F was given EPF 300 mg·kg-1. At the end of the 4th month, all rats were sacrificed. Bones, which included tibia, femur and humerus of both sides and all lumbar vertebra bodies, had been taken out. Measurement was made on the elastic modulus, maximum loading capability, maximum stress, potential energy of deformation, and structural rigidity of biomechanical properties of the fourth lumbar vertebra body (LV4); the maximum loading capability, bone break load, potential energy of deformation, structural rigidity of the structural dynamics properties of the femur com-pact bone; the elastic modulus, maximum stress, maximum inherent strain, bone break stress, and bone break strain of the mechanical properties of a material of the femur compact bone in the experimental rats. The results showed that compared with Group B, the elastic modulus, maximum loading capability, maximum stress, potential energy of deformation, and structural rigidity of LV4; the maximum loading capability, bone break load, potential energy of de-formation, structural rigidity of the structural dynamics properties of the femur compact bone; the elastic modulus, maximum stress

  7. Effects of Hospital-Based Physical Therapy on Hospital Discharge Outcomes among Hospitalized Older Adults with Community-Acquired Pneumonia and Declining Physical Function.

    Science.gov (United States)

    Kim, Sun Jung; Lee, Joo Hun; Han, Boram; Lam, Julia; Bukowy, Elizabeth; Rao, Avinash; Vulcano, Jordan; Andreeva, Anelia; Bertelson, Heather; Shin, Hyun Phil; Yoo, Ji Won

    2015-06-01

    To examine whether hospital-based physical therapy is associated with functional changes and early hospital readmission among hospitalized older adults with community-acquired pneumonia and declining physical function. Study design was a retrospective observation study. Participants were community-dwelling older adults admitted to medicine floor for community-acquired pneumonia (n = 1,058). Their physical function using Katz activities of daily living (ADL) Index declined between hospital admission and 48 hours since hospital admission (Katz ADL Index 6→5). The intervention group was those receiving physical therapy for ≥ 0.5 hour/day. Outcomes were Katz ADL Index at hospital discharge and all-cause 30-day hospital readmission rate. The intervention and control groups did not differ in the Katz ADL Index at hospital discharge (p = 0.11). All-cause 30-day hospital readmission rate was lower in the intervention than in control groups (OR = 0.65, p = 0.02). Hospital-based physical therapy has the benefits toward reducing 30-day hospital readmission rate of acutely ill older adults with community-acquired pneumonia and declining physical function. PMID:26029475

  8. A review of biomechanically informed breast image registration

    Science.gov (United States)

    Hipwell, John H.; Vavourakis, Vasileios; Han, Lianghao; Mertzanidou, Thomy; Eiben, Björn; Hawkes, David J.

    2016-01-01

    Breast radiology encompasses the full range of imaging modalities from routine imaging via x-ray mammography, magnetic resonance imaging and ultrasound (both two- and three-dimensional), to more recent technologies such as digital breast tomosynthesis, and dedicated breast imaging systems for positron emission mammography and ultrasound tomography. In addition new and experimental modalities, such as Photoacoustics, Near Infrared Spectroscopy and Electrical Impedance Tomography etc, are emerging. The breast is a highly deformable structure however, and this greatly complicates visual comparison of imaging modalities for the purposes of breast screening, cancer diagnosis (including image guided biopsy), tumour staging, treatment monitoring, surgical planning and simulation of the effects of surgery and wound healing etc. Due primarily to the challenges posed by these gross, non-rigid deformations, development of automated methods which enable registration, and hence fusion, of information within and across breast imaging modalities, and between the images and the physical space of the breast during interventions, remains an active research field which has yet to translate suitable methods into clinical practice. This review describes current research in the field of breast biomechanical modelling and identifies relevant publications where the resulting models have been incorporated into breast image registration and simulation algorithms. Despite these developments there remain a number of issues that limit clinical application of biomechanical modelling. These include the accuracy of constitutive modelling, implementation of representative boundary conditions, failure to meet clinically acceptable levels of computational cost, challenges associated with automating patient-specific model generation (i.e. robust image segmentation and mesh generation) and the complexity of applying biomechanical modelling methods in routine clinical practice.

  9. Biomechanics of the spine. Part I: Spinal stability

    Energy Technology Data Exchange (ETDEWEB)

    Izzo, Roberto, E-mail: roberto1766@interfree.it [Neuroradiology Department, “A. Cardarelli” Hospital, Napoli (Italy); Guarnieri, Gianluigi, E-mail: gianluigiguarnieri@hotmail.it [Neuroradiology Department, “A. Cardarelli” Hospital, Napoli (Italy); Guglielmi, Giuseppe, E-mail: g.gugliemi@unifg.it [Department of Radiology, University of Foggia, Foggia (Italy); Muto, Mario, E-mail: mutomar@tiscali.it [Neuroradiology Department, “A. Cardarelli” Hospital, Napoli (Italy)

    2013-01-15

    Biomechanics, the application of mechanical principles to living organisms, helps us to understand how all the bony and soft spinal components contribute individually and together to ensure spinal stability, and how traumas, tumours and degenerative disorders exert destabilizing effects. Spine stability is the basic requirement to protect nervous structures and prevent the early mechanical deterioration of spinal components. The literature reports a number of biomechanical and clinical definitions of spinal stability, but a consensus definition is lacking. Any vertebra in each spinal motion segment, the smallest functional unit of the spine, can perform various combinations of the main and coupled movements during which a number of bony and soft restraints maintain spine stability. Bones, disks and ligaments contribute by playing a structural role and by acting as transducers through their mechanoreceptors. Mechanoreceptors send proprioceptive impulses to the central nervous system which coordinates muscle tone, movement and reflexes. Damage to any spinal structure gives rise to some degree of instability. Instability is classically considered as a global increase in the movements associated with the occurrence of back and/or nerve root pain. The assessment of spinal instability remains a major challenge for diagnostic imaging experts. Knowledge of biomechanics is essential in view of the increasing involvement of radiologists and neuroradiologists in spinal interventional procedures and the ongoing development of new techniques and devices. Bioengineers and surgeons are currently focusing on mobile stabilization systems. These systems represent a new frontier in the treatment of painful degenerative spine and aim to neutralize noxious forces, restore the normal function of spinal segments and protect the adjacent segments. This review discusses the current concepts of spine stability.

  10. Effects of Cougar Predation and Nutrition on Mule Deer Population Declines in the IM Province of the Columbia Basin, Annual Report 2002-2003.

    Energy Technology Data Exchange (ETDEWEB)

    Wielgus, Robert; Shipley, Lisa; Myers, Woodrow

    2003-09-01

    Construction of the Grand Coulee and Chief Joseph dams has resulted in inundation and loss of 29,125 total habitat units for mule deer and irrigation agriculture in many parts the Intermountain Province (IM) of the Columbia Basin. Mule deer in the Shrub-Steppe are ranked high priority target species for mitigation and management and are declining in most portions of the sub basins of the IM. Reasons for the decline are unknown but believed to be related to habitat changes resulting from dams and irrigation agriculture. White-tailed deer are believed to be increasing throughout the basin because of habitat changes brought about by the dams and irrigation agriculture. Recent research (1997-2000) in the NE IM and adjacent Canadian portions of the Columbia Basin (conducted by this author and funded by the Columbia Basin Fish & Wildlife Compensation Program B.C.), suggest that the increasing white-tailed deer populations (because of dams and irrigation agriculture) are resulting in increased predation by cougars on mule deer (apparent competition or alternate prey hypothesis). The apparent competition hypothesis predicts that as alternate prey (white-tailed deer) densities increase, so do densities of predators, resulting in increased incidental predation on sympatric native prey (mule deer). Apparent competition can result in population declines and even extirpation of native prey in some cases. Such a phenomenon may account for declines of mule deer in the IM and throughout arid and semi-arid West where irrigation agriculture is practiced. We will test the apparent competition hypothesis by conducting a controlled, replicated 'press' experiment in at least 2 treatment and 2 control areas of the IM sub basins by reducing densities of white-tailed deer and observing any changes in cougar predation on mule deer. Deer densities will be monitored by WADFW personnel using annual aerial surveys and/or other trend indices. Predation rates and population growth rates

  11. Effects of Cougar Predation and Nutrition on Mule Deer Population Declines in the Intermountain Province of the Columbia Basin, 2001-2002 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Wielgus, Robert B.; Shipley, Lisa

    2002-07-01

    Construction of the Grand Coulee and Chief Joseph dams has resulted in inundation and loss of 29,125 total habitat units for mule deer and irrigation agriculture in many parts the Intermountain Province (IM) of the Columbia Basin. Mule deer in the Shrub-Steppe are ranked high priority target species for mitigation and management and are declining in most portions of the subbasins of the IM. Reasons for the decline are unknown but believed to be related to habitat changes resulting from dams and irrigation agriculture. White-tailed deer are not ranked as target species and are believed to be increasing throughout the basin because of habitat changes brought about by the dams and irrigation agriculture. Recent research (1997-2000) in the NE IM and adjacent Canadian portions of the Columbia Basin (conducted by this author and funded by the Columbia Basin Fish & Wildlife Compensation Program B.C.), suggest that the increasing white-tailed deer populations (because of dams and irrigation agriculture) are resulting in increased predation by cougars on mule deer (apparent competition or alternate prey hypothesis). The apparent competition hypothesis predicts that as alternate prey (white-tailed deer) densities increase, so do densities of predators, resulting in increased incidental predation on sympatric native prey (mule deer). Apparent competition can result in population declines and even extirpation of native prey in some cases. Such a phenomenon may account for declines of mule deer in the IM and throughout arid and semi-arid West where irrigation agriculture is practiced. We will test the apparent competition hypothesis by conducting a controlled, replicated ''press'' experiment in at least 2 treatment and 2 control areas of the IM subbasins by reducing densities of white-tailed deer and observing any changes in cougar predation on mule deer. Deer densities will be monitored by WADFW personnel using annual aerial surveys and/or other trend

  12. Role of Aquaporin 0 in lens biomechanics

    Energy Technology Data Exchange (ETDEWEB)

    Sindhu Kumari, S.; Gupta, Neha [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); Shiels, Alan [Washington University School of Medicine, St. Louis, MO (United States); FitzGerald, Paul G. [Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, CA (United States); Menon, Anil G. [University of Cincinnati College of Medicine, Cincinnati, OH (United States); Mathias, Richard T. [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); SUNY Eye Institute, NY (United States); Varadaraj, Kulandaiappan, E-mail: kulandaiappan.varadaraj@stonybrook.edu [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); SUNY Eye Institute, NY (United States)

    2015-07-10

    Maintenance of proper biomechanics of the eye lens is important for its structural integrity and for the process of accommodation to focus near and far objects. Several studies have shown that specialized cytoskeletal systems such as the beaded filament (BF) and spectrin-actin networks contribute to mammalian lens biomechanics; mutations or deletion in these proteins alters lens biomechanics. Aquaporin 0 (AQP0), which constitutes ∼45% of the total membrane proteins of lens fiber cells, has been shown to function as a water channel and a structural cell-to-cell adhesion (CTCA) protein. Our recent ex vivo study on AQP0 knockout (AQP0 KO) mouse lenses showed the CTCA function of AQP0 could be crucial for establishing the refractive index gradient. However, biomechanical studies on the role of AQP0 are lacking. The present investigation used wild type (WT), AQP5 KO (AQP5{sup −/−}), AQP0 KO (heterozygous KO: AQP0{sup +/−}; homozygous KO: AQP0{sup −/−}; all in C57BL/6J) and WT-FVB/N mouse lenses to learn more about the role of fiber cell AQPs in lens biomechanics. Electron microscopic images exhibited decreases in lens fiber cell compaction and increases in extracellular space due to deletion of even one allele of AQP0. Biomechanical assay revealed that loss of one or both alleles of AQP0 caused a significant reduction in the compressive load-bearing capacity of the lenses compared to WT lenses. Conversely, loss of AQP5 did not alter the lens load-bearing ability. Compressive load-bearing at the suture area of AQP0{sup +/−} lenses showed easy separation while WT lens suture remained intact. These data from KO mouse lenses in conjunction with previous studies on lens-specific BF proteins (CP49 and filensin) suggest that AQP0 and BF proteins could act co-operatively in establishing normal lens biomechanics. We hypothesize that AQP0, with its prolific expression at the fiber cell membrane, could provide anchorage for cytoskeletal structures like BFs and

  13. Effect of attending to a ball during a side-cut maneuver on lower extremity biomechanics in male and female athletes.

    Science.gov (United States)

    Fedie, Rebecca; Carlstedt, Kristen; Willson, John D; Kernozek, Thomas W

    2010-09-01

    Many sports associated with anterior cruciate ligament (ACL) injury require athletes attend to a ball during participation. We investigated effects of attending to a ball on lower extremity mechanics during a side-cut maneuver and if these effects are consistent for males and females. Sagittal and frontal plane hip and knee kinematics and joint moments were measured during side-cut maneuvers in 19 male and 19 female National Collegiate Athletic Association division III basketball players. Participants also experienced two side-cut conditions that required attention to a ball. Our results did not indicate that the effect of attention varies with gender. However, during side-cut conditions while attending to a ball, internal knee adductor moment was 20% greater (p = 0.03) and peak knee flexion angle was 4 degrees larger (p knee flexion (p knee abduction (p = 0.026) at initial contact during all side-cut conditions than males. Attention to a ball may affect lower extremity mechanics relevant to ACL injury. The validity of laboratory studies of lower extremity mechanics for sports that include attention to a ball may be increased if participants are required to attend to a ball during the task. PMID:21162362

  14. Longitudinal modeling in sports: young swimmers' performance and biomechanics profile.

    Science.gov (United States)

    Morais, Jorge E; Marques, Mário C; Marinho, Daniel A; Silva, António J; Barbosa, Tiago M

    2014-10-01

    New theories about dynamical systems highlight the multi-factorial interplay between determinant factors to achieve higher sports performances, including in swimming. Longitudinal research does provide useful information on the sportsmen's changes and how training help him to excel. These questions may be addressed in one single procedure such as latent growth modeling. The aim of the study was to model a latent growth curve of young swimmers' performance and biomechanics over a season. Fourteen boys (12.33 ± 0.65 years-old) and 16 girls (11.15 ± 0.55 years-old) were evaluated. Performance, stroke frequency, speed fluctuation, arm's propelling efficiency, active drag, active drag coefficient and power to overcome drag were collected in four different moments of the season. Latent growth curve modeling was computed to understand the longitudinal variation of performance (endogenous variables) over the season according to the biomechanics (exogenous variables). Latent growth curve modeling showed a high inter- and intra-subject variability in the performance growth. Gender had a significant effect at the baseline and during the performance growth. In each evaluation moment, different variables had a meaningful effect on performance (M1: Da, β = -0.62; M2: Da, β = -0.53; M3: η(p), β = 0.59; M4: SF, β = -0.57; all P performance over time. Different variables were the main responsible for the performance improvement. A gender gap, intra- and inter-subject variability was verified.

  15. Stability of the unlinked Latitude total elbow prosthesis: A biomechanical in vitro analysis.

    NARCIS (Netherlands)

    Wagener, M.L.; Vos, M.J. de; Hendriks, J.C.M.; Eygendaal, D.; Verdonschot, N.J.J.

    2013-01-01

    BACKGROUND: The purpose of this study is to assess the valgus and varus laxity of the unlinked version of the Latitude total elbow prosthesis and the effects of radial head preservation or replacement. METHODS: Biomechanical analysis of the valgus and varus laxity of the unlinked Latitude was perfor

  16. Stability of the unlinked Latitude total elbow prosthesis: A biomechanical in vitro analysis

    NARCIS (Netherlands)

    Wagener, Marc L.; Vos, de Maarten J.; Hendriks, Jan C.M.; Eygendaal, Denise; Verdonschot, Nico

    2013-01-01

    Background The purpose of this study is to assess the valgus and varus laxity of the unlinked version of the Latitude total elbow prosthesis and the effects of radial head preservation or replacement. Methods Biomechanical analysis of the valgus and varus laxity of the unlinked Latitude was perform

  17. Dehydroepiandrosterone and age-related cognitive decline

    OpenAIRE

    Sorwell, Krystina G.; Urbanski, Henryk F.

    2009-01-01

    In humans the circulating concentrations of dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS) decrease markedly during aging, and have been implicated in age-associated cognitive decline. This has led to the hypothesis that DHEA supplementation during aging may improve memory. In rodents, a cognitive anti-aging effect of DHEA and DHEAS has been observed but it is unclear whether this effect is mediated indirectly through conversion of these steroids to estradiol. Moreover, despite the de...

  18. Are cranial biomechanical simulation data linked to known diets in extant taxa? A method for applying diet-biomechanics linkage models to infer feeding capability of extinct species.

    Directory of Open Access Journals (Sweden)

    Zhijie Jack Tseng

    Full Text Available Performance of the masticatory system directly influences feeding and survival, so adaptive hypotheses often are proposed to explain craniodental evolution via functional morphology changes. However, the prevalence of "many-to-one" association of cranial forms and functions in vertebrates suggests a complex interplay of ecological and evolutionary histories, resulting in redundant morphology-diet linkages. Here we examine the link between cranial biomechanical properties for taxa with different dietary preferences in crown clade Carnivora, the most diverse clade of carnivorous mammals. We test whether hypercarnivores and generalists can be distinguished based on cranial mechanical simulation models, and how such diet-biomechanics linkages relate to morphology. Comparative finite element and geometric morphometrics analyses document that predicted bite force is positively allometric relative to skull strain energy; this is achieved in part by increased stiffness in larger skull models and shape changes that resist deformation and displacement. Size-standardized strain energy levels do not reflect feeding preferences; instead, caniform models have higher strain energy than feliform models. This caniform-feliform split is reinforced by a sensitivity analysis using published models for six additional taxa. Nevertheless, combined bite force-strain energy curves distinguish hypercarnivorous versus generalist feeders. These findings indicate that the link between cranial biomechanical properties and carnivoran feeding preference can be clearly defined and characterized, despite phylogenetic and allometric effects. Application of this diet-biomechanics linkage model to an analysis of an extinct stem carnivoramorphan and an outgroup creodont species provides biomechanical evidence for the evolution of taxa into distinct hypercarnivorous and generalist feeding styles prior to the appearance of crown carnivoran clades with similar feeding preferences.

  19. Are cranial biomechanical simulation data linked to known diets in extant taxa? A method for applying diet-biomechanics linkage models to infer feeding capability of extinct species.

    Science.gov (United States)

    Tseng, Zhijie Jack; Flynn, John J

    2015-01-01

    Performance of the masticatory system directly influences feeding and survival, so adaptive hypotheses often are proposed to explain craniodental evolution via functional morphology changes. However, the prevalence of "many-to-one" association of cranial forms and functions in vertebrates suggests a complex interplay of ecological and evolutionary histories, resulting in redundant morphology-diet linkages. Here we examine the link between cranial biomechanical properties for taxa with different dietary preferences in crown clade Carnivora, the most diverse clade of carnivorous mammals. We test whether hypercarnivores and generalists can be distinguished based on cranial mechanical simulation models, and how such diet-biomechanics linkages relate to morphology. Comparative finite element and geometric morphometrics analyses document that predicted bite force is positively allometric relative to skull strain energy; this is achieved in part by increased stiffness in larger skull models and shape changes that resist deformation and displacement. Size-standardized strain energy levels do not reflect feeding preferences; instead, caniform models have higher strain energy than feliform models. This caniform-feliform split is reinforced by a sensitivity analysis using published models for six additional taxa. Nevertheless, combined bite force-strain energy curves distinguish hypercarnivorous versus generalist feeders. These findings indicate that the link between cranial biomechanical properties and carnivoran feeding preference can be clearly defined and characterized, despite phylogenetic and allometric effects. Application of this diet-biomechanics linkage model to an analysis of an extinct stem carnivoramorphan and an outgroup creodont species provides biomechanical evidence for the evolution of taxa into distinct hypercarnivorous and generalist feeding styles prior to the appearance of crown carnivoran clades with similar feeding preferences. PMID:25923776

  20. Protocol for Project FACT: a randomised controlled trial on the effect of a walking program and vitamin B supplementation on the rate of cognitive decline and psychosocial wellbeing in older adults with mild cognitive impairment [ISRCTN19227688

    OpenAIRE

    Hopman-Rock Marijke; van Uffelen Jannique GZ; Chin A Paw Marijke JM; van Mechelen Willem

    2005-01-01

    Abstract Background the prevalence of individuals with cognitive decline is increasing since the number of elderly adults is growing considerably. The literature provides promising results on the beneficial effect of exercise and vitamin supplementation on cognitive function both in cognitively healthy as well as in the demented elderly. Methods/Design the design is a two-by-two factorial randomised controlled trial. The study population consists of independently living elderly, between 70 an...

  1. Protocol for Project FACT: A randomised controlled trial on the effect of a walking program and vitamin B supplementation on the rate of cognitive decline and psychosocial wellbeing in older adults with mild cognitive impairment

    OpenAIRE

    Uffelen, J.G.Z. van; Hopman-Rock, M.; Chin A Paw, M.J.M.; van Mechelen, W

    2005-01-01

    Background: the prevalence of individuals with cognitive decline is increasing since the number of elderly adults is growing considerably. The literature provides promising results on the beneficial effect of exercise and vitamin supplementation on cognitive function both in cognitively healthy as well as in the demented elderly. Methods/Design: the design is a two-by-two factorial randomised controlled trial. The study population consists of independently living elderly, between 70 and 80 ye...

  2. The Effect of Chang Run Tong on Biomechanical Colon Remodeling in STZ-Induced Type I Diabetic Rats - Is It Related to Advanced Glycation End Product Formation?

    DEFF Research Database (Denmark)

    Zhao, Jingbo; Gregersen, Hans

    2015-01-01

    effects. Meterials and METHODS: Morphometric properties, residual strains and stress-strain of the wall were studied in colonic segments obtained from diabetic (DM), CRT treated diabetic (T1, high dosage: 50g/kg; T2, low dosage: 25g/kg) and normal (Con) rats. Diabetes was induced by a single tail vein...... and the opening angle were measured from the digitized images of the segments in the no-load state and zero-stress state. The residual strain was computed from the morphometry data. Step-wise distension was done (from 0 to 20 cmH2O). Circumferential and longitudinal stresses and strains were computed from...... the length, diameter and pressure data and from the zero-stress state geometry. The expression of advanced glycation end products (AGE) and receptor of AGE (RAGE) were detected in different layers by using immunohistochemistry method and quantitatively analyzed by using imaging analysis software. Linear...

  3. Biomedical Imaging and Computational Modeling in Biomechanics

    CERN Document Server

    Iacoviello, Daniela

    2013-01-01

    This book collects the state-of-art and new trends in image analysis and biomechanics. It covers a wide field of scientific and cultural topics, ranging from remodeling of bone tissue under the mechanical stimulus up to optimizing the performance of sports equipment, through the patient-specific modeling in orthopedics, microtomography and its application in oral and implant research, computational modeling in the field of hip prostheses, image based model development and analysis of the human knee joint, kinematics of the hip joint, micro-scale analysis of compositional and mechanical properties of dentin, automated techniques for cervical cell image analysis, and iomedical imaging and computational modeling in cardiovascular disease.   The book will be of interest to researchers, Ph.D students, and graduate students with multidisciplinary interests related to image analysis and understanding, medical imaging, biomechanics, simulation and modeling, experimental analysis.

  4. Effects of two football stud configurations on biomechanical characteristics of single-leg landing and cutting movements on infilled synthetic turf.

    Science.gov (United States)

    Brock, Elizabeth; Zhang, Songning; Milner, Clare; Liu, Xuan; Brosnan, James T; Sorochan, John C

    2014-11-01

    Multiple playing surfaces and footwear used in American football warrant a better understanding of relationship between different combinations of turf and footwear. The purpose of this study was to examine effects of shoe and stud types on ground reaction force (GRF) and ankle and knee kinematics of a 180° cut and a single-leg 90° land-cut on synthetic turf. Fourteen recreational football players performed five trials of the 180° cut and 90° land-cut in three shoe conditions: non-studded running shoe, and football shoe with natural and synthetic turf studs. Variables were analyzed with a 3 × 2 (shoe × movement) repeated measures analysis of variance (p studs produced smaller peak medial GRFs compared to synthetic turf studs and non-studded shoe (p = 0.012). For land-cut, peak eversion velocity was reduced in running shoes compared to natural (p = 0.016) and synthetic (p = 0.002) turf studs. The 90° land-cut movement resulted in greater peak vertical GRF and loading rate compared to the 180° cut. Overall, increased GRFs in the 90° land-cut movement may increase the chance of injury. PMID:25301011

  5. The biomechanical effects of variation in the maximum forces exerted by trunk muscles on the joint forces and moments in the lumbar spine: a finite element analysis.

    Science.gov (United States)

    Kim, K; Lee, S K; Kim, Y H

    2010-10-01

    The weakening of trunk muscles is known to be related to a reduction of the stabilization function provided by the muscles to the lumbar spine; therefore, strengthening deep muscles might reduce the possibility of injury and pain in the lumbar spine. In this study, the effect of variation in maximum forces of trunk muscles on the joint forces and moments in the lumbar spine was investigated. Accordingly, a three-dimensional finite element model of the lumbar spine that included the trunk muscles was used in this study. The variation in maximum forces of specific muscle groups was then modelled, and joint compressive and shear forces, as well as resultant joint moments, which were presumed to be related to spinal stabilization from a mechanical viewpoint, were analysed. The increase in resultant joint moments occurred owing to decrease in maximum forces of the multifidus, interspinales, intertransversarii, rotatores, iliocostalis, longissimus, psoas, and quadratus lumborum. In addition, joint shear forces and resultant joint moments were reduced as the maximum forces of deep muscles were increased. These results from finite element analysis indicate that the variation in maximum forces exerted by trunk muscles could affect the joint forces and joint moments in the lumbar spine.

  6. Effects of two football stud configurations on biomechanical characteristics of single-leg landing and cutting movements on infilled synthetic turf.

    Science.gov (United States)

    Brock, Elizabeth; Zhang, Songning; Milner, Clare; Liu, Xuan; Brosnan, James T; Sorochan, John C

    2014-11-01

    Multiple playing surfaces and footwear used in American football warrant a better understanding of relationship between different combinations of turf and footwear. The purpose of this study was to examine effects of shoe and stud types on ground reaction force (GRF) and ankle and knee kinematics of a 180° cut and a single-leg 90° land-cut on synthetic turf. Fourteen recreational football players performed five trials of the 180° cut and 90° land-cut in three shoe conditions: non-studded running shoe, and football shoe with natural and synthetic turf studs. Variables were analyzed with a 3 × 2 (shoe × movement) repeated measures analysis of variance (p < 0.05). Peak vertical GRF (p < 0.001) and loading rate (p < 0.001) were greater during 90° land-cut than 180° cut. For 180° cut, natural turf studs produced smaller peak medial GRFs compared to synthetic turf studs and non-studded shoe (p = 0.012). For land-cut, peak eversion velocity was reduced in running shoes compared to natural (p = 0.016) and synthetic (p = 0.002) turf studs. The 90° land-cut movement resulted in greater peak vertical GRF and loading rate compared to the 180° cut. Overall, increased GRFs in the 90° land-cut movement may increase the chance of injury.

  7. Homogenization of biomechanical models for plant tissues

    OpenAIRE

    Piatnitski, Andrey; Ptashnyk, Mariya

    2015-01-01

    In this paper homogenization of a mathematical model for plant tissue biomechanics is presented. The microscopic model constitutes a strongly coupled system of reaction-diffusion-convection equations for chemical processes in plant cells, the equations of poroelasticity for elastic deformations of plant cell walls and middle lamella, and Stokes equations for fluid flow inside the cells. The chemical process in cells and the elastic properties of cell walls and middle lamella are coupled becau...

  8. Biomechanics of pediatric manual wheelchair mobility

    Directory of Open Access Journals (Sweden)

    Brooke A. Slavens

    2015-09-01

    Full Text Available Currently, there is limited research of the biomechanics of pediatric manual wheelchair mobility. Specifically, the biomechanics of functional tasks and their relationship to joint pain and health is not well understood. To contribute to this knowledge gap, a quantitative rehabilitation approach was applied for characterizing upper extremity biomechanics of manual wheelchair mobility in children and adolescents during propulsion, starting and stopping tasks. A Vicon motion analysis system captured movement, while a SmartWheel simultaneously collected three-dimensional forces and moments occurring at the hand-rim. A custom pediatric inverse dynamics model was used to evaluate three-dimensional upper extremity joint motions, forces and moments of 14 children with spinal cord injury (SCI during the functional tasks. Additionally, pain and health-related quality of life outcomes were assessed. This research found that joint demands are significantly different amongst functional tasks, with greatest demands placed on the shoulder during the starting task. Propulsion was significantly different from starting and stopping at all joints. We identified multiple stroke patterns used by the children, some of which are not standard in adults. One subject reported average daily pain, which was minimal. Lower than normal physical health and higher than normal mental health was found in this population. It can be concluded that functional tasks should be considered in addition to propulsion for rehabilitation and SCI treatment planning. This research provides wheelchair users and clinicians with a comprehensive, biomechanical, mobility assessment approach for wheelchair prescription, training, and long-term care of children with SCI.

  9. Analysis of Biomechanical Factors in Bend Running

    OpenAIRE

    Bing Zhang; Xinping You; Feng Li

    2013-01-01

    Sprint running is the demonstration of comprehensive abilities of technology and tactics, under various conditions. However, whether it is just to allocate the tracks for short-distance athletes from different racetracks has been the hot topic. This study analyzes its forces, differences in different tracks and winding influences, in the aspects of sport biomechanics. The results indicate, many disadvantages exist in inner tracks, middle tracks are the best and outer ones are inferior to midd...

  10. Effect of the rider position during rising trot on the horse׳s biomechanics (back and trunk kinematics and pressure under the saddle).

    Science.gov (United States)

    Martin, P; Cheze, L; Pourcelot, P; Desquilbet, L; Duray, L; Chateau, H

    2016-05-01

    Knowledge about the horse-saddle-rider interaction remains limited. The aim of this study was to compare the effect of the rider׳s position at rising trot on the pressure distribution, spine movements, stirrups forces and locomotion of the horse. The horse׳s back movements were measured using IMUs fixed at the levels of thoracic (T6, T12, T16) and lumbar (L2, L5) vertebrae, the pressure distribution using a pressure mat and stirrups forces using force sensors. The horse׳s and rider׳s approximated centres of mass (COM) were calculated using 2D reflective markers. To compare both trot phases (rider seated/rider standing), three horses were trotted at the rising trot by the same rider. Means±SD of each parameter for sitting and standing were compared using a Student׳s t test (p=0.05). Stirrups forces showed two peaks of equal magnitude in every stride cycle for left and right stirrups but increased during the standing phase. Simultaneously, the pressure for the whole mat significantly increased by +3.1kPa during the sitting phase with respect to standing phase. The T12-T16 and T16-L2 angular ranges of motion (ROM) were significantly reduced (-3.2° -1.2°) and the T6-T12 and L2-L5 ROM were significantly increased (+1.7° +0.7°) during sitting phase compared to standing phase. During rising trot, the sitting phase does not only increase the pressure on the horse׳s back but also reduces the back motion under the saddle compared to the standing phase. These results give new insights into the understanding of horse-rider interactions and equine back pain management. PMID:26947029

  11. Biomechanical exploration on dynamic modes of lifting.

    Science.gov (United States)

    Gagnon, M; Smyth, G

    1992-03-01

    Whatever the lifting method used, dynamic factors appear to have an effect on the safe realization of movement, and NIOSH guidelines recommend smooth lifting with no sudden acceleration effects. On the other hand, inertial forces may play an important role in the process of transfer of momentum to the load. The direction by which these inertial forces may affect the loadings on body structures and processes of energy transfers cannot be determined a priori. A biomechanical experiment was performed to examine if there were differences in the execution processes between a slow-continuous lift and an accelerated-continuous lift, and also between accelerated lifts either executed continuously or interrupted with a pause. The lifts were executed from a height of 15 cm to a height of 185 cm above the head and with two different loads (6.4 and 11.6 kg). Five experienced workers in manual materials handling were used as subjects. Films and force platforms recordings supplied the data; dynamic segmental analyses were performed to calculate net muscular moments at each joint; a planar single-muscle equivalent was used to estimate compression loadings at L5/S1; total mechanical work, joint work distribution, and energy transfers were determined from a kinetic approach based on the integration of joint power as a function of time. Analyses of variance with repeated measures were applied to the three treatments. The results showed that joint muscular moments, spinal loadings, mechanical work, and muscular utilization ratios were generally increased by the presence of acceleration without inducing benefits of improved energy transfers; therefore slower lifts with reduced acceleration may be safer when handling moderately heavy loads. The maximum values of kinematic and kinetic factors were generally not affected by the pause, but the occurrence of jerks in the movement (acceleration, ground forces, and muscular moments) suggests that the pause may not be indicated when

  12. Computational Biomechanics Theoretical Background and BiologicalBiomedical Problems

    CERN Document Server

    Tanaka, Masao; Nakamura, Masanori

    2012-01-01

    Rapid developments have taken place in biological/biomedical measurement and imaging technologies as well as in computer analysis and information technologies. The increase in data obtained with such technologies invites the reader into a virtual world that represents realistic biological tissue or organ structures in digital form and allows for simulation and what is called “in silico medicine.” This volume is the third in a textbook series and covers both the basics of continuum mechanics of biosolids and biofluids and the theoretical core of computational methods for continuum mechanics analyses. Several biomechanics problems are provided for better understanding of computational modeling and analysis. Topics include the mechanics of solid and fluid bodies, fundamental characteristics of biosolids and biofluids, computational methods in biomechanics analysis/simulation, practical problems in orthopedic biomechanics, dental biomechanics, ophthalmic biomechanics, cardiovascular biomechanics, hemodynamics...

  13. Biomechanical determinants of elite rowing technique and performance.

    Science.gov (United States)

    Buckeridge, E M; Bull, A M J; McGregor, A H

    2015-04-01

    In rowing, the parameters of injury, performance, and technique are all interrelated and in dynamic equilibrium. Whilst rowing requires extreme physical strength and endurance, a high level of skill and technique is essential to enable an effective transfer of power through the rowing sequence. This study aimed to determine discrete aspects of rowing technique, which strongly influence foot force production and asymmetries at the foot-stretchers, as these are biomechanical parameters often associated with performance and injury risk. Twenty elite female rowers performed an incremental rowing test on an instrumented rowing ergometer, which measured force at the handle and foot-stretchers, while three-dimensional kinematic recordings of the ankle, knee, hip, and lumbar-pelvic joints were made. Multiple regression analyses identified hip kinematics as a key predictor of foot force output (R(2)  = 0.48), whereas knee and lumbar-pelvic kinematics were the main determinants in optimizing the horizontal foot force component (R(2)  = .41). Bilateral asymmetries of the foot-stretchers were also seen to significantly influence lumbar-pelvic kinematics (R(2)  = 0.43) and pelvic twisting (R(2)  = 0.32) during the rowing stroke. These results provide biomechanical evidence toward aspects of technique that can be modified to optimize force output and performance, which can be of direct benefit to coaches and athletes. PMID:25039605

  14. Morphology and biomechanics of human heart

    Science.gov (United States)

    Chelnokova, Natalia O.; Golyadkina, Anastasiya A.; Kirillova, Irina V.; Polienko, Asel V.; Ivanov, Dmitry V.

    2016-03-01

    Object of study: A study of the biomechanical characteristics of the human heart ventricles was performed. 80 hearts were extracted during autopsy of 80 corpses of adults (40 women and 40 men) aged 31-70 years. The samples were investigated in compliance with the recommendations of the ethics committee. Methods: Tension and compression tests were performed with help of the uniaxial testing machine Instron 5944. Cardiometry was also performed. Results: In this work, techniques for human heart ventricle wall biomechanical properties estimation were developed. Regularities of age and gender variability in deformative and strength properties of the right and left ventricle walls were found. These properties were characterized by a smooth growth of myocardial tissue stiffness and resistivity at a relatively low strain against reduction in their strength and elasticity from 31-40 to 61-70 years. It was found that tissue of the left ventricle at 61-70 years had a lower stretchability and strength compared with tissues of the right ventricle and septum. These data expands understanding of the morphological organization of the heart ventricles, which is very important for the development of personalized medicine. Taking into account individual, age and gender differences of the heart ventricle tissue biomechanical characteristics allows to rationally choosing the type of patching materials during reconstructive operations on heart.

  15. Biomechanical analysis of sprinting: decathletes versus champions.

    Science.gov (United States)

    Kunz, H.; Kaufmann, D. A.

    1981-01-01

    The purpose of this study was to compare some biomechanical variables of decathletes and world class sprinters while running the 100 metre race. Sixteen Swiss national decathletes and three world class American sprinters were filmed by a 16 mm Locam (100 fps) camera at the 70 m mark of the race. The co-ordinates for a 26-point stick figure were digitised and then submitted to analysis by a computer programme which produced quantitative data for 12 biomechanical variables. The data indicated that world-class sprinters differed from decathletes in running the 100 m dash by having (1) an optimal combination of a larger stride length and higher stride frequency (2) a smaller thigh angle at contact which shortens the contact time (3) a larger stride landing angle (4) a greater average acceleration of the thigh angle was (5) a larger trunk angle which contributes to a larger trunk/thigh angle. Although other factors such as culture, training, physique and racial differences may influence differences in performance between American world-class sprinters and Swiss decathletes, these data do indicate that biomechanical variables may contribute to differences in 100 m dash performance. Images p177-a p177-b PMID:7272662

  16. Effect of High Heels on Biomechanics of a Walking Woman's Trunk and Lower Limbs%高跟鞋对行走中女性躯干、下肢的力学影响

    Institute of Scientific and Technical Information of China (English)

    刘华; 吴文华

    2011-01-01

    It is very useful for designing suitable high heels that we investigate the biomechanical characteristics of a woman' s trunk and lower limbs , who is walking with high heehs. This paper summarizes the common impairment caused by high-heels, including platypodia, toe deformity, sprain of ankle, gonarthritis,backache. The gait characters of walking women in high heels are with little stride, low step speed, long gait cycle, more fluctuant center of gravity, shorter phase of single-limb stance. The characters on mechanics shows that the pressure on pelma is not even, the stress at knee joint increases, the muscle power of lower limbs gets weak, and even the load on spine augments. Therefore woman walking in high heels for a long time causes a lot of adverse effects on trunk and lower limbs, that means a woman should wear high heels as few as possible in daily life.%通过探讨高跟鞋对行走中女性躯干、下肢的生物力学影响,可以为设计更符合人体运动功能的高跟鞋提供理论依据.通过总结本文得出高跟鞋对女性的常见损伤有扁平足、足趾畸形、踝关节扭伤、膝关节炎、腰背酸痛;穿高跟鞋行走的步态特征是步幅小、步速慢、周期长、重心起伏大、单支撑时相缩短;其力学特征有足底受力不均匀、踝关节受力减少、膝关节内压力增大、下肢肌肉肌力变小、脊柱负荷加大等.总之长期穿高跟鞋行走对女性躯干、下肢产生许多不利影响,因此建议女性平时尽量少穿高跟鞋.

  17. Migratory diversity predicts population declines in birds.

    Science.gov (United States)

    Gilroy, James J; Gill, Jennifer A; Butchart, Stuart H M; Jones, Victoria R; Franco, Aldina M A

    2016-03-01

    Declines in migratory species are a pressing concern worldwide, but the mechanisms underpinning these declines are not fully understood. We hypothesised that species with greater within-population variability in migratory movements and destinations, here termed 'migratory diversity', might be more resilient to environmental change. To test this, we related map-based metrics of migratory diversity to recent population trends for 340 European breeding birds. Species that occupy larger non-breeding ranges relative to breeding, a characteristic we term 'migratory dispersion', were less likely to be declining than those with more restricted non-breeding ranges. Species with partial migration strategies (i.e. overlapping breeding and non-breeding ranges) were also less likely to be declining than full migrants or full residents, an effect that was independent of migration distance. Recent rates of advancement in Europe-wide spring arrival date were greater for partial migrants than full migrants, suggesting that migratory diversity may also help facilitate species responses to climate change. PMID:26807694

  18. An introduction to biomechanics solids and fluids, analysis and design

    CERN Document Server

    Humphrey, Jay D

    2004-01-01

    Designed to meet the needs of undergraduate students, Introduction to Biomechanics takes the fresh approach of combining the viewpoints of both a well-respected teacher and a successful student. With an eye toward practicality without loss of depth of instruction, this book seeks to explain the fundamental concepts of biomechanics. With the accompanying web site providing models, sample problems, review questions and more, Introduction to Biomechanics provides students with the full range of instructional material for this complex and dynamic field.

  19. Biomechanics of the elbow joint in tennis players.

    OpenAIRE

    Eygendaal, D.; Rahussen, F.T.; Diercks, R.L.

    2007-01-01

    Elbow injuries constitute a sizeable percentage of tennis injuries. A basic understanding of biomechanics of tennis and analysis of forces, loads and motions of the elbow during tennis can will improve the understanding of the pathophysiology of these injuries. All different strokes in tennis have a different repetitive biomechanical nature which can result in tennis related injuries. In this article a biomechanically based evaluation of tennis strokes is presented. This overview includes all...

  20. 月球赤纬角变化的旱灾效应%The Effect of Lunar Apparent Declination on Drought Hazard

    Institute of Scientific and Technical Information of China (English)

    芮建勋

    2014-01-01

    行星对应区理论认为太阳系各星体及其格局对地球气候有影响。该理论较完整地解释了包括月球在内的太阳系各星体运行、格局对地球气候乃至旱涝灾害的影响规律。研究发现,月球对干旱的影响有地带性规律,月球回归赤纬偏北或偏南,均可造成华北或黄河流域的干旱。月球只能配合其他星体格局以触发干旱或洪涝灾害。据此判断,在2013-2017年期间,月球赤纬角进入最低值时期,预示着我国华北地区进入了连续几年将呈现大旱的状态。%The planetary corresponding area theory from the astronomical disasters point of view claims that those celestial bodies in the solar system can affect the Earth climates.The theory explains completely the affecting rules of the apparent positions and patterns of these major planets on many drought or rainstorm disasters on the Earth.Disaster impacts of different lunar right declinations are explored.It is found that the impact of the lunar motion has zonal rules on the Earth.Higher or lower of lunar regression of right declination would also bring drought disasters for the North China.The moon can only trigger the natural disasters together with the other planets.Dur-ing the period of 2013 to 2017,the right declination of the moon enters the lowest state.It means the North China will come into drought disaster period for several years.

  1. Analysis of FEV1 decline in relatively healthy heavy smokers

    DEFF Research Database (Denmark)

    Thomsen, Laura H.; Dirksen, Asger; Shaker, Saher B.;

    2014-01-01

    Progressive decline in lung function has been widely accepted as the hallmark of chronic obstructive pulmonary disease (COPD); however, recent evidence indicates that the rate of decline measured as decline in forced expiratory volume in one second (FEV1) is higher in mild to moderate COPD than...... analyzed data from 3,218 relatively healthy heavy smokers who participated in the Danish Lung Cancer Screening Trial. The influences of age, sex, height, body mass index, smoking, and severity of airflow limitation on FEV1 were analyzed in mixed effects models. In absolute terms those with the best lung...... function consistently showed the steepest decline, whereas in relative terms most fast decliners are found among those with low lung function. Measuring changes in relative terms implied statistically significant acceleration of decline with advancing age, smoking (pack-years) and severity of airflow...

  2. Recent microfluidic devices for studying gamete and embryo biomechanics.

    Science.gov (United States)

    Lai, David; Takayama, Shuichi; Smith, Gary D

    2015-06-25

    The technical challenges of biomechanic research such as single cell analysis at a high monetary cost, labor, and time for just a small number of measurements is a good match to the strengths of microfluidic devices. New scientific discoveries in the fertilization and embryo development process, of which biomechanics is a major subset of interest, is crucial to fuel the continual improvement of clinical practice in assisted reproduction. The following review will highlight some recent microfluidic devices tailored for gamete and embryo biomechanics where biomimicry arises as a major theme of microfluidic device design and function, and the application of fundamental biomechanic principles are used to improve outcomes of cryopreservation. PMID:25801423

  3. Lithuania: Fertility decline and its determinants

    Directory of Open Access Journals (Sweden)

    Aiva Jasilioniene

    2008-07-01

    Full Text Available Since the beginning of the 1990s, Lithuania has been undergoing significant transformations in family life and has experienced a precipitous decline in fertility. The determinants of the changes are diverse in character and are associated with socioeconomic transformations, economic difficulties faced by the post-Soviet society, inadequate social and family policies and changing value orientations and life styles. This article traces the fertility trends in Lithuania from the period and cohort perspective, providing adjusted TFR estimates that reveal the significance of the tempo effect on the recent decline in fertility. Furthermore, the main factors leading to the recently observed changes in family and fertility are identified and analysed. Finally, the characteristic features and necessary improvements of current Lithuanian family policy and its possible effects on individual behaviour and fertility trends are discussed.

  4. French Wines on the Decline?:

    DEFF Research Database (Denmark)

    Steiner, Bodo

    2004-01-01

    French wines, differentiated by geographic origin, served for many decades as a basis for the French success in the British wine market. However in the early 1990s, market share began to decline. This article explores the values that market participants placed on labelling information on French...

  5. Bibliography on Decline and Retrenchment.

    Science.gov (United States)

    National Center for Higher Education Management Systems, Boulder, CO.

    A bibliography on decline and retrenchment in higher education is presented that includes publications from the fields of higher education, the organization sciences, and public administration. The objective is to make available the reference tools that have been useful in conducting the National Center for Higher Education Management Systems'…

  6. Chinese culture and fertility decline.

    Science.gov (United States)

    Wu, C; Jia, S

    1992-01-01

    Coale has suggested that cultural factors exert a significant influence on fertility reduction; countries in the "Chinese cultural circle" would be the first to show fertility decline. In China, the view was that traditional Chinese culture contributed to increased population. This paper examines the nature of the relationship between Chinese culture and fertility. Attention was directed to a comparison of fertility rates of developing countries with strong Chinese cultural influence and of fertility within different regions of China. Discussion was followed by an explanation of the theoretical impact of Chinese culture on fertility and direct and indirect beliefs and practices that might either enhance or hinder fertility decline. Emigration to neighboring countries occurred after the Qing dynasty. Fertility after the 1950s declined markedly in Japan, Singapore, Hong Kong, South Korea, Taiwan, and mainland China: all countries within the Chinese cultural circle. Other countries within the Chinese circle which have higher fertility, yet lower fertility than other non-Chinese cultural countries, are Malaysia, Thailand, and Indonesia. Within China, regions with similar fertility patterns are identified as coastal regions, central plains, and mountainous and plateau regions. The Han ethnic group has lower fertility than that of ethnic minorities; regions with large Han populations have lower fertility. Overseas Chinese in East Asian countries also tend to have lower fertility than their host populations. Chinese culture consisted of the assimilation of other cultures over 5000 years. Fertility decline was dependent on the population's desire to limit reproduction, favorable social mechanisms, and availability of contraception: all factors related to economic development. Chinese culture affects fertility reduction by affecting reproductive views and social mechanisms directly, and indirectly through economics. Confucianism emphasizes collectivism, self

  7. The declining talent pool of government

    OpenAIRE

    Dewan, Torun; Myatt, David

    2008-01-01

    We consider a government for which success requires high performance by talented ministers. A leader provides incentives to her ministers by firing those who fail. However, the consequent turnover drains a finite talent pool of potential appointees. The severity of the optimal firing rule and ministerial performances decline over time: the lifetime of an effective government is limited. We relate this lifetime to various factors, including external shocks, the replenishment of the talent pool...

  8. Effects of lovastatin on bone mass and biomechanical property in tail-suspended rats%洛伐他汀对尾悬吊大鼠骨量及生物力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    何余庆; 郑杰; 赵嘉懿

    2012-01-01

    目的 通过尾悬吊法制作拟失重大鼠骨质疏松动物模型,观察洛伐他汀体内给药对尾悬吊大鼠骨量、微观结构、生物力学性能的作用潜能.方法 将24只10周龄雄性SD大鼠随机分成3组,每组各8只:正常对照组(G1组,8只,每日予蒸馏水灌胃)、尾悬吊组(G2组,将大鼠在悬吊笼中尾部悬吊,后肢离地,使躯干与地面成40°角,同时每日予每天蒸馏水灌胃)、尾悬吊加洛伐他汀组(G3组,在尾部悬吊基础上,每日予20mg/kg洛伐他汀灌胃);4周后处死所有大鼠,取大鼠右侧股骨用双能X线骨密度仪测量骨密度,并取胫骨近端进行骨组织形态计量学测定;同时取大鼠左侧股骨行生物力学检测.结果 G1组的右股骨各段骨密度和骨小梁相对体积、左股骨最大载荷量显著高于G2、G3组(均P<0.05),G1组的骨小梁分离度及骨吸收周长百分数、破骨细胞数、类骨质周长百分数显著低于G2、G3组(均P<0.05),且G2、G3组上述指标的差异均无统计学意义(均P >0.05).结论 尾悬吊4周可导致大鼠骨量丢失;洛伐他汀体内给药不能阻止尾悬吊大鼠股骨骨量丢失.%To investigate the effects of lovastatin on bone mass,microarchitecture and biomechanical property,and to observe the potential protective effect of lovastatin on unloading-induced osteoporosis.MethodsTwenty-four 10-week-old male Sprague-Dawley rats were randomized into three groups of eight animals each: G1, control group; G2, the tail-suspended group with vehicle; G3, the tail-suspended group and administered daily with 20 mg/kg of lovastatin by gavage. The experiment was lasted for four weeks, and all animals were sacrificed one day after the final lovastatin administration. The right femurs were harvested for the measurement of bone histomorphometry, and bone mineral density (BMD) measured by dual-energy X-ray absorptiometry.The left femurs were collected for biomechanical test.ResultsThe tBMD,pBMD and dBMD of

  9. Matrix Metalloproteinase 9 (MMP-9 Regulates Vein Wall Biomechanics in Murine Thrombus Resolution.

    Directory of Open Access Journals (Sweden)

    Khanh P Nguyen

    Full Text Available Deep venous thrombosis is a common vascular problem with long-term complications including post-thrombotic syndrome. Post-thrombotic syndrome consists of leg pain, swelling and ulceration that is related to incomplete or maladaptive resolution of the venous thrombus as well as loss of compliance of the vein wall. We examine the role of metalloproteinase-9 (MMP-9, a gene important in extracellular remodeling in other vascular diseases, in mediating thrombus resolution and biomechanical changes of the vein wall.The effects of targeted deletion of MMP-9 were studied in an in vivo murine model of thrombus resolution using the FVB strain of mice. MMP-9 expression and activity significantly increased on day 3 after DVT. The lack of MMP-9 impaired thrombus resolution by 27% and this phenotype was rescued by the transplantation of wildtype bone marrow cells. Using novel biomechanical techniques, we demonstrated that the lack of MMP-9 significantly decreased thrombus-induced loss of vein wall compliance. Biomechanical analysis of the contribution of individual structural components showed that MMP-9 affected the elasticity of the extracellular matrix and collagen-elastin fibers. Biochemical and histological analyses correlated with these biomechanical effects as thrombi of mice lacking MMP-9 had significantly fewer macrophages and collagen as compared to those of wildtype mice.MMP-9 mediates thrombus-induced loss of vein wall compliance by increasing stiffness of the extracellular matrix and collagen-elastin fibers during thrombus resolution. MMP-9 also mediates macrophage and collagen content of the resolving thrombus and bone-marrow derived MMP-9 plays a role in resolution of thrombus mass. These disparate effects of MMP-9 on various aspects of thrombus illustrate the complexity of individual protease function on biomechanical and morphometric aspects of thrombus resolution.

  10. Sports biomechanics in the research of the Department of Biomechanics of University School of Physical Education in Poznań. Part 1. Biomechanics of rowing: tests on rowing ergometers, reconstruction and synthesis.

    Science.gov (United States)

    Dworak, Lechosław B

    2010-01-01

    The purpose of this study is to reconstruct the early phase of scientific research conducted at the Department of Biomechanics of the University School of Physical Education in Poznan, particularly the work on biomechanics of rowing, conducted as part of the Ministerial Project PR 105, entitled "The effectiveness of training and competition as well as regeneration in sports". Three kinds of research have been described, carried out with the use of the rowing ergometers. The first was the research on neuromuscular coordination in the rowing cycle, the second was the research on kinematic and dynamic characteristics of rowing on the Universal Rowing Ergometer UEW - 1, while the last one concerned determination of maximum forces generated by functional muscle groups in two characteristic rowing positions within the closed biochain of the torso and the limbs.

  11. Biomechanical approaches to identify and quantify injury mechanisms and risk factors in women's artistic gymnastics.

    Science.gov (United States)

    Bradshaw, Elizabeth J; Hume, Patria A

    2012-09-01

    Targeted injury prevention strategies, based on biomechanical analyses, have the potential to help reduce the incidence and severity of gymnastics injuries. This review outlines the potential benefits of biomechanics research to contribute to injury prevention strategies for women's artistic gymnastics by identification of mechanisms of injury and quantification of the effects of injury risk factors. One hundred and twenty-three articles were retained for review after searching electronic databases using key words, including 'gymnastic', 'biomech*', and 'inj*', and delimiting by language and relevance to the paper aim. Impact load can be measured biomechanically by the use of instrumented equipment (e.g. beatboard), instrumentation on the gymnast (accelerometers), or by landings on force plates. We need further information on injury mechanisms and risk factors in gymnastics and practical methods of monitoring training loads. We have not yet shown, beyond a theoretical approach, how biomechanical analysis of gymnastics can help reduce injury risk through injury prevention interventions. Given the high magnitude of impact load, both acute and accumulative, coaches should monitor impact loads per training session, taking into consideration training quality and quantity such as the control of rotation and the height from which the landings are executed. PMID:23072044

  12. Numerical Reconstruction and Injury Biomechanism in a Car-Pedestrian Crash Accident

    Institute of Scientific and Technical Information of China (English)

    ZOU Dong-hua; LI Zheng-dong; SHAO Yu; FENG Hao; CHEN Jian-guo; LIU Ning-guo; HUANG Ping; CHEN Yi-jiu

    2012-01-01

    Objective To reconstruct a car-pedestrian crash accident using numerical simulation technology and explore the injury biomechanism as forensic evidence for injury identification.Methods An integration of multi-body dynamic,finite elcment (FE),and classical method was applied to a car-pedestrian crash accident.The location of the collision and the details of the traffic accident were determined by vehicle trace verification and autopsy.The accident reconstruction was performed by coupling the three-dimensional car behavior from PC-CRASH with a MADYMO dummy model.The collision FE models of head and leg,developed from CT scans of human remains,were loaded with calculated dummy collision parameters.The data of the impact biomechanical responses were extracted in terms of von Mises stress,relative displacement,strain and stress fringes.Results The accident reconstruction results were identical with the examined ones and the biomechanism of head and leg injuries,illustrated through the FE methods,were consistent with the classical injury theories.Conclusion The numerical simulation technology is proved to be effective in identifying traffic accidents and exploring of injury biomechanism.

  13. Evaluation of Corneal Topography and Biomechanical Parameters after Use of Systemic Isotretinoin in Acne Vulgaris

    Directory of Open Access Journals (Sweden)

    Yusuf Yildirim

    2014-01-01

    Full Text Available Purpose. We report the effect of isotretinoin on corneal topography, corneal thickness, and biomechanical parameters in patients with acne vulgaris. Method. Fifty-four eyes of 54 patients who received oral isotretinoin for treatment of acne vulgaris were evaluated. All patients underwent a corneal topographical evaluation with a Scheimpflug camera combined with Placido-disk (Sirius, ultrasonic pachymetry measurements, and corneal biomechanical evaluation with an ocular response analyzer at baseline, in the 1st, 3rd, and 6th months of treatment, and 6 months after isotretinoin discontinuation. Results. The thinnest corneal thickness measured with Sirius differed significantly in the 1st, 3rd, and 6th months compared with the baseline measurement; there was no significant change in ultrasonic central corneal thickness measurements and biomechanical parameters (corneal hysteresis and corneal resistance factor throughout the study. Average simulated keratometry and surface asymmetry index increased significantly only in the first month of treatment according to the baseline. All changes disappeared 6 months after the end of treatment. Conclusion. Basal tear secretion and corneal morphologic properties were significantly influenced during the systemic isotretinoin treatment and the changes were reversible after discontinuation. No statistical important biomechanical differences were found to be induced by isotretinoin.

  14. Evaluating the Association between Diabetes, Cognitive Decline and Dementia

    Directory of Open Access Journals (Sweden)

    Omorogieva Ojo

    2015-07-01

    Full Text Available The aim of this article is to review the association between diabetes mellitus, cognitive decline and dementia, including the effects of cognitive decline and dementia on self management of diabetes. This is a literature review of primary research articles. A number of contemporary research articles that met the inclusion criteria were selected for this review paper. These articles were selected using a number of search strategies and electronic databases, such as EBSCOhost Research and SwetsWise databases. The duration of diabetes, glycated haemoglobin levels and glycaemic fluctuations were associated with cognitive decline and dementia. Similarly, hypoglycaemia was significantly related to increased risk of developing cognitive decline and dementia. Furthermore, cognitive decline and dementia were associated with poorer diabetes management. There is evidence of the association between diabetes, cognitive decline and dementia including the shared pathogenesis between diabetes and Alzheimer’s disease. In addition, the self management of diabetes is affected by dementia and cognitive decline. It could be suggested that the association between diabetes and dementia is bidirectional with the potential to proceed to a vicious cycle. Further studies are needed in order to fully establish the relationship between diabetes, cognitive decline and dementia. Patients who have diabetes and dementia could benefit from structured education strategies, which should involve empowerment programmes and lifestyle changes. The detection of cognitive decline should highlight the need for education strategies.

  15. VASCULAR RISK FACTORS AND COGNITIVE DECLINE IN A POPULATION SAMPLE

    Science.gov (United States)

    Ganguli, Mary; Fu, Bo; Snitz, Beth E.; Unverzagt, Frederick W.; Loewenstein, David A.; Hughes, Tiffany F.; Chang, Chung-Chou H.

    2014-01-01

    We examined several vascular factors in relation to rates of decline in five cognitive domains in a population-based cohort. In an age-stratified random sample (N=1982) aged 65+ years, we assessed at baseline the cognitive domains of attention, executive function, memory, language, and visuospatial function, and also vascular, inflammatory, and metabolic indices. Random effects models generated slopes of cognitive decline over the next four years; linear models identified vascular factors associated with these slopes, adjusting for demographics, baseline cognition, and potential interactions. Several vascular risk factors (history of stroke, diabetes, central obesity, C-Reactive Protein), although associated with lower baseline cognitive performance, did not predict rate of subsequent decline. APOE*4 genotype was associated with accelerated decline in language, memory, and executive functions. Homocysteine elevation was associated with faster decline in executive function. Hypertension (history or systolic blood pressure >140 mm) was associated with slower decline in memory. Baseline alcohol consumption was associated with slower decline in attention, language, and memory. Different indices of vascular risk are associated with low performance and with rates of decline in different cognitive domains. Cardiovascular mechanisms explain at least some of the variance in cognitive decline. Selective survival may also play a role. PMID:24126216

  16. Lower limb biomechanics during running in individuals with achilles tendinopathy: a systematic review

    Directory of Open Access Journals (Sweden)

    Munteanu Shannon E

    2011-05-01

    Full Text Available Abstract Background Abnormal lower limb biomechanics is speculated to be a risk factor for Achilles tendinopathy. This study systematically reviewed the existing literature to identify, critique and summarise lower limb biomechanical factors associated with Achilles tendinopathy. Methods We searched electronic bibliographic databases (Medline, EMBASE, Current contents, CINAHL and SPORTDiscus in November 2010. All prospective cohort and case-control studies that evaluated biomechanical factors (temporospatial parameters, lower limb kinematics, dynamic plantar pressures, kinetics [ground reaction forces and joint moments] and muscle activity associated with mid-portion Achilles tendinopathy were included. Quality of included studies was evaluated using the Quality Index. The magnitude of differences (effect sizes between cases and controls was calculated using Cohen's d (with 95% CIs. Results Nine studies were identified; two were prospective and the remaining seven case-control study designs. The quality of 9 identified studies was varied, with Quality Index scores ranging from 4 to 15 out of 17. All studies analysed running biomechanics. Cases displayed increased eversion range of motion of the rearfoot (d = 0.92 and 0.67 in two studies, reduced maximum lower leg abduction (d = -1.16, reduced ankle joint dorsiflexion velocity (d = -0.62 and reduced knee flexion during gait (d = -0.90. Cases also demonstrated a number of differences in dynamic plantar pressures (primarily the distribution of the centre of force, ground reaction forces (large effects for timing variables and also showed reduced peak tibial external rotation moment (d = -1.29. Cases also displayed differences in the timing and amplitude of a number of lower limb muscles but many differences were equivocal. Conclusions There are differences in lower limb biomechanics between those with and without Achilles tendinopathy that may have implications for the prevention and management of

  17. Effectiveness and cost-effectiveness of a multidisciplinary intervention programme to prevent new falls and functional decline among elderly persons at risk: design of a replicated randomised controlled trial [ISRCTN64716113

    Directory of Open Access Journals (Sweden)

    Crebolder Harry FJM

    2005-01-01

    Full Text Available Abstract Background Falls are common among community-dwelling elderly people and can have a considerable impact on quality of life and healthcare costs. People who have sustained a fall are at greater risk of falling again. We replicated a British randomised controlled trial which demonstrated the effectiveness of a multidisciplinary intervention programme to prevent falls. The objective is to describe the design of a replication study evaluating a multidisciplinary intervention programme on recurrent falls and functional decline among elderly persons at risk. The study consists of an effect evaluation, an economic evaluation and a process evaluation. Methods/design The programme is aimed at community-dwelling elderly people aged 65 years or over who have visited an accident and emergency department (A&E department or a general practitioners' cooperative (GP cooperative because of a fall. The design involves a two-group randomised controlled trial. Participants are followed for twelve months after baseline. The intervention programme consists of a detailed medical and occupational therapy assessment with referral to relevant services if indicated. People in the control group receive usual care. The main outcome measures of the effect evaluation are number of falls and daily functioning. The economic evaluation will be performed from a societal perspective. A process evaluation will be carried out to evaluate the feasibility of the intervention programme.

  18. Biomechanics of male erectile function

    OpenAIRE

    Udelson, Daniel

    2007-01-01

    Two major branches of engineering mechanics are fluid mechanics and structural mechanics, with many practical problems involving the effect of the first on the second. An example is the design of an aircraft's wings to bend within reasonable limits without breaking under the action of lift forces exerted by the air flowing over them; another is the maintenance of the structural integrity of a dam designed to hold back a water reservoir which would exert very large forces on it. Similarly, flu...

  19. Cardiovascular Prevention of Cognitive Decline

    Directory of Open Access Journals (Sweden)

    Jean-Jacques Monsuez

    2011-01-01

    Full Text Available Midlife cardiovascular risk factors, including diabetes, hypertension, dyslipemia, and an unhealthy lifestyle, have been linked to subsequent incidence, delay of onset, and progression rate of Alzheimer disease and vascular dementia. Conversely, optimal treatment of cardiovascular risk factors prevents and slows down age-related cognitive disorders. The impact of antihypertensive therapy on cognitive outcome in patients with hypertension was assessed in large trials which demonstrated a reduction in progression of MRI white matter hyperintensities, in cognitive decline and in incidence of dementia. Large-scale database correlated statin use and reduction in the incidence of dementia, mainly in patients with documented atherosclerosis, but clinical trials failed to reach similar conclusions. Whether a multitargeted intervention would substantially improve protection, quality of life, and reduce medical cost expenditures in patients with lower risk profile has not been ascertained. This would require appropriately designed trials targeting large populations and focusing on cognitive decline as a primary outcome endpoint.

  20. Biomechanics, Exercise Physiology, and the 75th Anniversary of RQES

    Science.gov (United States)

    Hamill, Joseph; Haymes, Emily M.

    2005-01-01

    The purpose of this paper is to review the biomechanics and exercise physiology studies published in the Research Quarterly for Exercise and Sport (RQES) over the past 75 years. Studies in biomechanics, a relatively new subdiscipline that evolved from kinesiology, first appeared in the journal about 40 years ago. Exercise physiology studies have…

  1. The Undergraduate Biomechanics Experience at Iowa State University.

    Science.gov (United States)

    Francis, Peter R.

    This paper discusses the objectives of a program in biomechanics--the analysis of sports skills and movement--and the evolution of the biomechanics program at Iowa State University. The primary objective of such a course is to provide the student with the basic tools necessary for adequate analysis of human movement, with special emphasis upon…

  2. Factors Related to Students' Learning of Biomechanics Concepts

    Science.gov (United States)

    Hsieh, ChengTu; Smith, Jeremy D.; Bohne, Michael; Knudson, Duane

    2012-01-01

    The purpose of this study was to replicate and expand a previous study to identify the factors that affect students' learning of biomechanical concepts. Students were recruited from three universities (N = 149) located in the central and western regions of the United States. Data from 142 students completing the Biomechanics Concept Inventory…

  3. Correlates of recent declines of rodents in northern and southern Australia : habitat structure is critical

    OpenAIRE

    Lawes, Michael J.; Fisher, Diana O; Johnson, Chris N.; Blomberg, Simon P.; Anke S K Frank; Fritz, Susanne A.; Hamish McCallum; Jeremy VanDerWal; Brett N Abbott; Sarah Legge; Mike Letnic; Thomas, Colette R.; Nikki Thurgate; Alaric Fisher; Gordon, Iain J.

    2015-01-01

    Australia has experienced dramatic declines and extinctions of its native rodent species over the last 200 years, particularly in southern Australia. In the tropical savanna of northern Australia significant declines have occurred only in recent decades. The later onset of these declines suggests that the causes may differ from earlier declines in the south. We examine potential regional effects (northern versus southern Australia) on biological and ecological correlates of range decline in A...

  4. Biomechanical and neuromuscular characteristics of male athletes: implications for the development of anterior cruciate ligament injury prevention programs.

    Science.gov (United States)

    Sugimoto, Dai; Alentorn-Geli, Eduard; Mendiguchía, Jurdan; Samuelsson, Kristian; Karlsson, Jon; Myer, Gregory D

    2015-06-01

    Prevention of anterior cruciate ligament (ACL) injury is likely the most effective strategy to reduce undesired health consequences including reconstruction surgery, long-term rehabilitation, and pre-mature osteoarthritis occurrence. A thorough understanding of mechanisms and risk factors of ACL injury is crucial to develop effective prevention programs, especially for biomechanical and neuromuscular modifiable risk factors. Historically, the available evidence regarding ACL risk factors has mainly involved female athletes or has compared male and female athletes without an intra-group comparison for male athletes. Therefore, the principal purpose of this article was to review existing evidence regarding the investigation of biomechanical and neuromuscular characteristics that may imply aberrant knee kinematics and kinetics that would place the male athlete at risk of ACL injury. Biomechanical evidence related to knee kinematics and kinetics was reviewed by different planes (sagittal and frontal/coronal), tasks (single-leg landing and cutting), situation (anticipated and unanticipated), foot positioning, playing surface, and fatigued status. Neuromuscular evidence potentially related to ACL injury was reviewed. Recommendations for prevention programs for ACL injuries in male athletes were developed based on the synthesis of the biomechanical and neuromuscular characteristics. The recommendations suggest performing exercises with multi-plane biomechanical components including single-leg maneuvers in dynamic movements, reaction to and decision making in unexpected situations, appropriate foot positioning, and consideration of playing surface condition, as well as enhancing neuromuscular aspects such as fatigue, proprioception, muscle activation, and inter-joint coordination.

  5. Biomechanics aspects of technique of high jump

    OpenAIRE

    Adashevskiy V.M.; Iermakov S.S.; Marchenko A. A.

    2013-01-01

    The purpose of work consists in the theoretical ground of optimum biomechanics descriptions in high jumps. A mathematical model is developed for determination of influence on the height of jump: speed and corner of flight of centre-of-mass during pushing away, positions of centre-of-mass body of sportsman in the phases of pushing away and transition through a slat, forces of resistance of air environment, influences of moment of inertia of body. The basic technical run-time errors of sportsma...

  6. Sensitivity of tumor motion simulation accuracy to lung biomechanical modeling approaches and parameters

    International Nuclear Information System (INIS)

    Finite element analysis (FEA)-based biomechanical modeling can be used to predict lung respiratory motion. In this technique, elastic models and biomechanical parameters are two important factors that determine modeling accuracy. We systematically evaluated the effects of lung and lung tumor biomechanical modeling approaches and related parameters to improve the accuracy of motion simulation of lung tumor center of mass (TCM) displacements. Experiments were conducted with four-dimensional computed tomography (4D-CT). A Quasi-Newton FEA was performed to simulate lung and related tumor displacements between end-expiration (phase 50%) and other respiration phases (0%, 10%, 20%, 30%, and 40%). Both linear isotropic and non-linear hyperelastic materials, including the neo-Hookean compressible and uncoupled Mooney–Rivlin models, were used to create a finite element model (FEM) of lung and tumors. Lung surface displacement vector fields (SDVFs) were obtained by registering the 50% phase CT to other respiration phases, using the non-rigid demons registration algorithm. The obtained SDVFs were used as lung surface displacement boundary conditions in FEM. The sensitivity of TCM displacement to lung and tumor biomechanical parameters was assessed in eight patients for all three models. Patient-specific optimal parameters were estimated by minimizing the TCM motion simulation errors between phase 50% and phase 0%. The uncoupled Mooney–Rivlin material model showed the highest TCM motion simulation accuracy. The average TCM motion simulation absolute errors for the Mooney–Rivlin material model along left-right, anterior–posterior, and superior–inferior directions were 0.80 mm, 0.86 mm, and 1.51 mm, respectively. The proposed strategy provides a reliable method to estimate patient-specific biomechanical parameters in FEM for lung tumor motion simulation. (paper)

  7. On the prospect of patient-specific biomechanics without patient-specific properties of tissues.

    Science.gov (United States)

    Miller, Karol; Lu, Jia

    2013-11-01

    This paper presents main theses of two keynote lectures delivered at Euromech Colloquium "Advanced experimental approaches and inverse problems in tissue biomechanics" held in Saint Etienne in June 2012. We are witnessing an advent of patient-specific biomechanics that will bring in the future personalized treatments to sufferers all over the world. It is the current task of biomechanists to devise methods for clinically-relevant patient-specific modeling. One of the obstacles standing before the biomechanics community is the difficulty in obtaining patient-specific properties of tissues to be used in biomechanical models. We postulate that focusing on reformulating computational mechanics problems in such a way that the results are weakly sensitive to the variation in mechanical properties of simulated continua is more likely to bear fruit in near future. We consider two types of problems: (i) displacement-zero traction problems whose solutions in displacements are weakly sensitive to mechanical properties of the considered continuum; and (ii) problems that are approximately statically determinate and therefore their solutions in stresses are also weakly sensitive to mechanical properties of constituents. We demonstrate that the kinematically loaded biomechanical models of the first type are applicable in the field of image-guided surgery where the current, intraoperative configuration of a soft organ is of critical importance. We show that sac-like membranes, which are prototypes of many thin-walled biological organs, are approximately statically determinate and therefore useful solutions for wall stress can be obtained without the knowledge of the wall's properties. We demonstrate the clinical applicability and effectiveness of the proposed methods using examples from modeling neurosurgery and intracranial aneurysms. PMID:23491073

  8. Jet Methods in Time-Dependent Lagrangian Biomechanics

    CERN Document Server

    Ivancevic, Tijana T

    2009-01-01

    In this paper we propose the time-dependent generalization of an `ordinary' autonomous human biomechanics, in which total mechanical + biochemical energy is not conserved. We introduce a general framework for time-dependent biomechanics in terms of jet manifolds associated to the extended musculo-skeletal configuration manifold, called the configuration bundle. We start with an ordinary configuration manifold of human body motion, given as a set of its all active degrees of freedom (DOF) for a particular movement. This is a Riemannian manifold with a material metric tensor given by the total mass-inertia matrix of the human body segments. This is the base manifold for standard autonomous biomechanics. To make its time-dependent generalization, we need to extend it with a real time axis. By this extension, using techniques from fibre bundles, we defined the biomechanical configuration bundle. On the biomechanical bundle we define vector-fields, differential forms and affine connections, as well as the associat...

  9. Biomechanical factors associated with the development of tibiofemoral knee osteoarthritis

    DEFF Research Database (Denmark)

    van Tunen, Joyce A C; Dell'Isola, Andrea; Juhl, Carsten;

    2016-01-01

    INTRODUCTION: Altered biomechanics, increased joint loading and tissue damage, might be related in a vicious cycle within the development of knee osteoarthritis (KOA). We have defined biomechanical factors as joint-related factors that interact with the forces, moments and kinematics in and around...... a synovial joint. Although a number of studies and systematic reviews have been performed to assess the association of various factors with the development of KOA, a comprehensive overview focusing on biomechanical factors that are associated with the development of KOA is not available. The aim...... of this review is (1) to identify biomechanical factors that are associated with (the development of) KOA and (2) to identify the impact of other relevant risk factors on this association. METHODS AND ANALYSIS: Cohort, cross-sectional and case-control studies investigating the association of a biomechanical...

  10. Systematic evaluation of observational methods assessing biomechanical exposures at work

    DEFF Research Database (Denmark)

    Takala, Esa-Pekka; Irmeli, Pehkonen; Forsman, Mikael;

    2009-01-01

    University of Science and Technology, Trondheim, 9 University of Gothenburg and National Research Centre for the Working Environment, Copenhagen   The aim of this project was to identify and systematically evaluate observational methods to assess workload on the musculoskeletal system. Searches...... in the electronic databases and other sources identified 29 observational methods. The methods were evaluated for the aspects related to their reliability and usability for different purposes. The results of evaluation will be found in internet with a tool that helps the user to search for most suitable method...... by sorting the methods according to the several items evaluated.   Numerous methods have been developed to assess physical workload (biomechanical exposures) in order to identify hazards leading to musculoskeletal disorders, to monitor the effects of ergonomic changes, and for research. No indvidual method...

  11. Occupational biomechanics of athletes and dancers: a comparative approach.

    Science.gov (United States)

    Bejjani, F J

    1987-07-01

    Muscle strains represent more than a third of all injuries in both dancers and athletes. Although often overlooked, anatomic variations play an important role in the etiology of these injuries, as does strength imbalance between agonists and antagonists. The incidence of spondylolysis is unusually high in ballet dancers and certain athletic groups, such as gymnasts, javelin throwers, and weight-lifters. Mechanical factors play a major role and can be exacerbated by congenital abnormalities. Various permanent adaptive musculoskeletal changes have been described both in dancers and athletes, especially those that start at a very young age. Task-related adaptive changes can also be seen in isokinetic strength measurements of various muscle groups, such as the spine muscles of Flamenco dancers. Shoes and floor surfaces can be directly responsible in part or in whole for many sports and dance injuries. "Vibration-pressure" diagrams are suggested as an objective way to document their effect on biomechanical behavior. PMID:2886209

  12. Assessment of knowledge transfer in the context of biomechanics

    Science.gov (United States)

    Hutchison, Randolph E.

    The dynamic act of knowledge transfer, or the connection of a student's prior knowledge to features of a new problem, could be considered one of the primary goals of education. Yet studies highlight more instances of failure than success. This dissertation focuses on how knowledge transfer takes place during individual problem solving, in classroom settings and during group work. Through the lens of dynamic transfer, or how students connect prior knowledge to problem features, this qualitative study focuses on a methodology to assess transfer in the context of biomechanics. The first phase of this work investigates how a pedagogical technique based on situated cognition theory affects students' ability to transfer knowledge gained in a biomechanics class to later experiences both in and out of the classroom. A post-class focus group examined events the students remembered from the class, what they learned from them, and how they connected them to later relevant experiences inside and outside the classroom. These results were triangulated with conceptual gains evaluated through concept inventories and pre- and post- content tests. Based on these results, the next two phases of the project take a more in-depth look at dynamic knowledge transfer during independent problem-solving and group project interactions, respectively. By categorizing prior knowledge (Source Tools), problem features (Target Tools) and the connections between them, results from the second phase of this study showed that within individual problem solving, source tools were almost exclusively derived from "propagated sources," i.e. those based on an authoritative source. This differs from findings in the third phase of the project, in which a mixture of "propagated" sources and "fabricated" sources, i.e. those based on student experiences, were identified within the group project work. This methodology is effective at assessing knowledge transfer in the context of biomechanics through evidence of

  13. Reduction of Biomechanical and Welding Fume Exposures in Stud Welding.

    Science.gov (United States)

    Fethke, Nathan B; Peters, Thomas M; Leonard, Stephanie; Metwali, Mahmoud; Mudunkotuwa, Imali A

    2016-04-01

    The welding of shear stud connectors to structural steel in construction requires a prolonged stooped posture that exposes ironworkers to biomechanical and welding fume hazards. In this study, biomechanical and welding fume exposures during stud welding using conventional methods were compared to exposures associated with use of a prototype system that allowed participants to weld from an upright position. The effect of base material (i.e. bare structural beam versus galvanized decking) on welding fume concentration (particle number and mass), particle size distribution, and particle composition was also explored. Thirty participants completed a series of stud welding simulations in a local apprenticeship training facility. Use of the upright system was associated with substantial reductions in trunk inclination and the activity levels of several muscle groups. Inhalable mass concentrations of welding fume (averaged over ~18 min) when using conventional methods were high (18.2 mg m(-3) for bare beam; 65.7 mg m(-3) for through deck), with estimated mass concentrations of iron (7.8 mg m(-3) for bare beam; 15.8 mg m(-3) for through deck), zinc (0.2 mg m(-3) for bare beam; 15.8 mg m(-3) for through deck), and manganese (0.9 mg m(-3) for bare beam; 1.5 mg m(-3) for through deck) often exceeding the American Conference of Governmental Industrial Hygienists Threshold Limit Values (TLVs). Number and mass concentrations were substantially reduced when using the upright system, although the total inhalable mass concentration remained above the TLV when welding through decking. The average diameters of the welding fume particles for both bare beam (31±17 nm) through deck conditions (34±34 nm) and the chemical composition of the particles indicated the presence of metallic nanoparticles. Stud welding exposes ironworkers to potentially high levels of biomechanical loading (primarily to the low back) and welding fume. The upright system used in this study improved exposure

  14. The biomechanics of solids and fluids: the physics of life

    Science.gov (United States)

    Alexander, David E.

    2016-09-01

    Biomechanics borrows and extends engineering techniques to study the mechanical properties of organisms and their environments. Like physicists and engineers, biomechanics researchers tend to specialize on either fluids or solids (but some do both). For solid materials, the stress-strain curve reveals such useful information as various moduli, ultimate strength, extensibility, and work of fracture. Few biological materials are linearly elastic so modified elastic moduli are defined. Although biological materials tend to be less stiff than engineered materials, biomaterials tend to be tougher due to their anisotropy and high extensibility. Biological beams are usually hollow cylinders; particularly in plants, beams and columns tend to have high twist-to-bend ratios. Air and water are the dominant biological fluids. Fluids generate both viscous and pressure drag (normalized as drag coefficients) and the Reynolds number (Re) gives their relative importance. The no-slip conditions leads to velocity gradients (‘boundary layers’) on surfaces and parabolic flow profiles in tubes. Rather than rigidly resisting drag in external flows, many plants and sessile animals reconfigure to reduce drag as speed increases. Living in velocity gradients can be beneficial for attachment but challenging for capturing particulate food. Lift produced by airfoils and hydrofoils is used to produce thrust by all flying animals and many swimming ones, and is usually optimal at higher Re. At low Re, most swimmers use drag-based mechanisms. A few swimmers use jetting for rapid escape despite its energetic inefficiency. At low Re, suspension feeding depends on mechanisms other than direct sieving because thick boundary layers reduce effective porosity. Most biomaterials exhibit a combination of solid and fluid properties, i.e., viscoelasticity. Even rigid biomaterials exhibit creep over many days, whereas pliant biomaterials may exhibit creep over hours or minutes. Instead of rigid materials

  15. The biomechanics of solids and fluids: the physics of life

    Science.gov (United States)

    Alexander, David E.

    2016-09-01

    Biomechanics borrows and extends engineering techniques to study the mechanical properties of organisms and their environments. Like physicists and engineers, biomechanics researchers tend to specialize on either fluids or solids (but some do both). For solid materials, the stress–strain curve reveals such useful information as various moduli, ultimate strength, extensibility, and work of fracture. Few biological materials are linearly elastic so modified elastic moduli are defined. Although biological materials tend to be less stiff than engineered materials, biomaterials tend to be tougher due to their anisotropy and high extensibility. Biological beams are usually hollow cylinders; particularly in plants, beams and columns tend to have high twist-to-bend ratios. Air and water are the dominant biological fluids. Fluids generate both viscous and pressure drag (normalized as drag coefficients) and the Reynolds number (Re) gives their relative importance. The no-slip conditions leads to velocity gradients (‘boundary layers’) on surfaces and parabolic flow profiles in tubes. Rather than rigidly resisting drag in external flows, many plants and sessile animals reconfigure to reduce drag as speed increases. Living in velocity gradients can be beneficial for attachment but challenging for capturing particulate food. Lift produced by airfoils and hydrofoils is used to produce thrust by all flying animals and many swimming ones, and is usually optimal at higher Re. At low Re, most swimmers use drag-based mechanisms. A few swimmers use jetting for rapid escape despite its energetic inefficiency. At low Re, suspension feeding depends on mechanisms other than direct sieving because thick boundary layers reduce effective porosity. Most biomaterials exhibit a combination of solid and fluid properties, i.e., viscoelasticity. Even rigid biomaterials exhibit creep over many days, whereas pliant biomaterials may exhibit creep over hours or minutes. Instead of rigid materials

  16. 人工种植牙修复牙列缺损的疗效及生物力学研究%Clinical effect and biomechanical research of dental implant in the restoration of dentition defect

    Institute of Scientific and Technical Information of China (English)

    陈增芳

    2013-01-01

    Objective To observe the clinical effect of dental implant system in the dentition defect repair,and to explore biomechanical properties of instant axial and lateral load to dental implants.Methods Forty-two patients with dentition defect received 67 ITI Straumann dental implants,6 months after which the upper part of the plant was repaired.Three-dimensional finite element models were established to analyze stress changes for dental implants with different immediate loadings.Results Twelve months after planting,94.0% (63/67) dental implants were planted successfully,and the rest of the indicators are good.Both in axial and lateral loads,stress was concentrated in the neck of the implant,stress of middle and apical parts decrease gradually.In 10 °,20 ° and 30 ° lateral load,at the part of 1/3 neck stress dropped sharply,and with the lateral load inclination increase,the neck stress increased.Conclusion Dental implant is an excellent method for repairing defective dentition with satisfactory results.Dental implant is applicable,but dentists should pay attention to the anastomosis angle,to avoid dental implant and foundation piles subject to lateral forces,in order to guarantee satisfying success rate of dental implants.%目的 观察人工种植牙修复牙列缺损的临床效,探讨牙种植体轴向和侧向即刻负载时的生物力学性能.方法 42例牙列缺损患者,共植入ITI Straumann牙种植体67枚,6个月后行种植义齿修复.采用三维有限元法分析种植牙即刻负载时不同负载下种植体骨界面的应力及位移变化.结果 修复后12个月,种植成功率为94.0%(63/67),其余各项指标良好.种植体轴向及侧向负载时,应力均集中在颈部,中部和根尖区应力逐渐较小;10°、20°及30°侧向负载时,颈1/3处落差较大,且随着侧向负载倾斜度增加,颈部应力增大.侧向负载时种植体的即刻负载位移均明显大于轴向负载位移(P<0.05),且种植体的即刻负载

  17. 颈椎前路不同方式减压固定对颈椎稳定性影响的生物力学研究%Biomechanical effects of different anterior decompressions on the stability of cervical vertebra

    Institute of Scientific and Technical Information of China (English)

    刘世敬; 袁国栋; 余正红; 赵卫东; 梁栋柱; 钟世镇

    2009-01-01

    Objectives: To study biomechanical effects of different anterior decompression and fusion on the stability of cervical vertebrae. Methods: 18 cadaveric specimens of cervical spine were divided into three group randomly: ①anterior cervical discectomy and fusion (ACDF); ②anterior cervical hybrid decompression and fusion(combined with corpectomy and discectomy (ACHDF) ; ③anterior cervical corpectomy and fusion (ACCF); Specimens of every group endured the movements of flexion, extension, lateral bending, and axial rotation. The range of motion of all directions was recorded stereophotogrammetrieally niter flexion-extension fatigue loading of 2000 cycles on the specimens of 3 groups. Results: Anterior plate made all of specimens more stable. After flexion-extension fatigue loading of 1200 cycles, there were no changes of ROM between ACDF and ACHDF groups, however, ROM of ACCF group increased. After 2000 cycles, SPIROM and SPINZ of ACDF and ACHDF groups had no difference, however, that of ACCF group decreased. Conclusions: Three kinds of anterior decompression and fusion technique could restore the stability of cervical vertebrae. Under the fatigue loading, the stability and tolerance of ACDF and ACHDF groups are superior to that of ACCF group.%目的:研究颈椎前路多节段病变不同减压、融合固定方式对生物力学稳定性的影响.方法:18具新鲜人尸体颈椎标本,分别行前路椎间盘切除植骨融合(ACDF)、分节段混合减压植骨融合(ACHDF)及椎体次全切除植骨融合(ACCF)术,依次测定正常状态、减压植骨后、钢板固定后、疲劳2000次后的三维活动度,计算稳定潜能指数(SPI),测定疲劳2000次后尾端螺钉和椎体间的活动度.结果:3种方式减压、植骨、钢板固定后,稳定性均明显提高;届伸疲劳1200次后,ACDF、ACHDF组标准化的螺钉-椎体间活动度曲线无变化,而ACCF组曲线升高;疲劳2000次后,ACDF组三维运动SPIROM及SPINZ无变

  18. Effects of exogenous IGF-1 on bone mineral density and biomechanical properties of ovariectomized rats%IGF-1对去卵巢大鼠骨密度及骨力学强度的影响

    Institute of Scientific and Technical Information of China (English)

    赵荣兰; 刘新宇; 孙蓓; 梁东春; 郭刚; 张镜宇

    2008-01-01

    Objective To study the effects of exogenous IGF-1 on bone mineral density,bone turnover and bone biomechanical properties of ovariectomized (OVX) rats.Methods Sprague-Dawley rats were either ovariectomized (n=60) or sham operated (n=10).Three months after the operation,the existence of osteoporosis in OVX rats was confirmed by bone mineral densitometry.OVX rats were randomly separated into 5 groups,subjected to the treatment of PTH1-34,three different-dosage of IGF-1 or normal saline (NS) respectively.Sham rats,treated with NS,was established as sham control.Eight weeks alter the treatment,serum levels of Ca,P,steocalcin concentration and alkaline phosphatase (ALP) activity were assayed.The bone mineral density of lumbar spine and the mechanical strength of the femur were determined.The bone thick-ness of distal femur was determined by histological staining.Results IGF-1 did not improve the bone miner-81 density of lumbar spine in OVX rats,but significantly improved their mechanical strength.Serological test results showed that IGF-1 could lower serum calcium,phosphorus,calcium levels and ALP activity;histological staining showed that IGF-1 could significantly increase the femur bone thickness of OVX rats.Conclusion IGF-1 Can increase the mechanical strength of the femug in OVX rats through reconstructing bone architee-ture rather than increasing bone mineral density.%目的 研究外源性胰岛素样生长因子-1(IGF-1)对去卵巢(OVX)骨质疏松大鼠骨密度、骨转换率、骨力学强度等方面的影响.方法 对大鼠施行双侧卵巢摘除术,术后3个月以骨密度测定证实骨质疏松的存在后,随机分为5组,分别以生理盐水、甲状旁腺激素1-34及3种不同剂量IGF-1进行干预.同时设立生理盐水干预的假手术大鼠作为对照.8周后检测血清钙、磷、骨钙素水平及碱性磷酸酶活性;测定腰椎骨密度、股骨力学强度;组织学染色测定股骨远端骨皮质厚度.结果 IGF-1虽未提

  19. Biomechanical analysis of padding in child seats and head injury.

    Science.gov (United States)

    Kumaresan, Srirangam; Sances, Anthony; Carlin, Fred

    2002-01-01

    Head injury is a common finding for infants and young children involved in automobile accidents. Although the child restraint seats have increased the level of safety for the pediatric population, skull fracture and/or brain injury occur during the interaction between the child's head and interior of the car seats with no padding. The introduction of effective and sufficient padding may significantly reduce the head injury. The present study was designed to evaluate the biomechanical effects of padding in child seats to reduce the potential for head injury. A head drop test of a six-month old anthropomorphic dummy was conducted. The side of the dummy head impacted the interior wing of child car seats of relatively soft and stiff materials, and a rigid metal plate at velocities of 2.2, 4.5 and 6.7 m/s. In all tests, three types of padding environments were used (no padding, comfort foam, 16 to 19 mm polypropylene padding). All data were collected at 10 kHz and filtered. A total of 39 tests were conducted. The head injury criteria (HIC), and head acceleration, and head angular acceleration were obtained. The HIC was calculated over a 36 ms interval from the resultant tri-axial acceleration. The angular accelerations were derived from the angular velocity data. The head injury biomechanical parameters decreased with the addition of padding. The HIC, peak acceleration, and angular acceleration were reduced up to 91%, 80%, and 61% respectively. The present results emphasize the importance of energy absorbing padding to provide an improved safety environment in child car seats.

  20. Is human fecundity declining in Western countries?

    Science.gov (United States)

    te Velde, Egbert; Burdorf, Alex; Nieschlag, Eberhard; Eijkemans, René; Kremer, Jan A M; Roeleveld, Nel; Habbema, Dik

    2010-06-01

    Since Carlsen and co-workers reported in 1992 that sperm counts have decreased during the second half of the last century in Western societies, there has been widespread anxiety about the adverse effects of environmental pollutants on human fecundity. The Carlsen report was followed by several re-analyses of their data set and by many studies on time trends in sperm quality and on secular trends in fecundity. However, the results of these studies were diverse, complex, difficult to interpret and, therefore, less straightforward than the Carlsen report suggested. The claims that population fecundity is declining and that environmental pollutants are involved, can neither be confirmed nor rejected, in our opinion. However, it is of great importance to find out because the possible influence of widespread environmental pollution, which would adversely affect human reproduction, should be a matter of great concern triggering large-scale studies into its causes and possibilities for prevention. The fundamental reason we still do not know whether population fecundity is declining is the lack of an appropriate surveillance system. Is such a system possible? In our opinion, determining total sperm counts (as a measure of male reproductive health) in combination with time to pregnancy (as a measure of couple fecundity) in carefully selected populations is a feasible option for such a monitoring system. If we want to find out whether or not population fecundity will be declining within the following 20-30 years, we must start monitoring now. PMID:20395222

  1. Farmer's lung is now in decline.

    LENUS (Irish Health Repository)

    Arya, A

    2012-02-03

    Farmer\\'s lung incidence in Ireland was constant until 1996, even though hay making methods were revolutionised in late 1980\\'s. We undertook this study to find out the incidence of farmer\\'s lung in Ireland from 1982-2002 and its correlation with rainfall and the effect of changing farm practices. The primary cases of farmer\\'s lung were identified from Hospital in Patients Enquiry (HIPE) unit of the national Economic & Social Research Institute (ESRI) Dublin. Rainfall data were obtained from Met Eireann whereas population, hay production and silage production were obtained from the Central Statistics Office, Dublin. As the farming population is in decline, we used the annual working unit (AWU), which reflects the true population at risk. An AWU is the equivalent of 1800 hours per farm worker per year. The incidence rates were constant from 1982-1996, but from 1997-2002 a marked decline was observed. There was strong positive correlation with hay production (r = 0.81) and strong negative correlation with silage production (r = -0.82). This study indicates that the incidence of farmer\\'s lung is now in decline.

  2. Action mechanism for effects of tibial rotational alignment technique on patellofemoral joint biomechanics%胫骨假体旋转对线技术影响髌股关节生物力学的作用机制

    Institute of Scientific and Technical Information of China (English)

    刘锴

    2016-01-01

    BACKGROUND:At present, the placement of tibial anatomic landmarks has no gold standard during total knee arthroplasty. In order to achieve the most ideal rotation function of the tibial prosthesis, we should do the preparation before surgery, understand tibial rotational alignment to rationaly select and apply the prosthesis. OBJECTIVE:To investigate the effect of tibial rotational alignment technique on patelofemoral joint biomechanics and related mechanisms. METHODS:Ten pairs of human knee joint specimens were colected to prepare experimental platform. Specimens were fixed on the experiment frame, which was fixed on the material testing instrument for mechanics experiment. Weset different knee flexion angles, including 30°, 60°, 90° and 120°. Joint replacement was performed with the knee prosthesis. Samples were randomly assigned to two groups (n=5). Tibial nodule technology and ROM technology were used to identify rotationalalignment of the tibial prosthesis. The medial and lateral patelofemoral joint contact pressure peak and patelofemoral contact area at different knee angles, and the medial and lateral parts of patelofemoral contact area at deep knee angles were observed in both groups. RESULTS AND CONCLUSION:(1) During flexion angle from 30° to 60°, the peak contact pressure of medial patelofemoral joint increased, and decreased gradualy in both groups. At flexion angle of 90°, contact pressure reached the minimum value, then increased gradualy, and reached the maximum value at 120°. No significant difference in peak contact pressure of medial patelofemoral joint at different knee angles was detected between the two groups (alP> 0.05). (2) During flexion angle from 30° to 60°, peak contact pressure of lateral patelofemoral joint decreased constantly, and then gradualy increased. No significant difference in peak contact pressure of lateral patelofemoral joint at different knee angles was detectable between thetwo groups (alP> 0.05). (3) During

  3. Biomechanical Energy Harvester Design For Active Prostheses

    Directory of Open Access Journals (Sweden)

    Akın Oğuz Kaptı

    2012-06-01

    Full Text Available One of the factors restricting the functions of active prostheses is limited charge times and weights of the batteries. Therefore, some biomechanical energy harvesting studies are conducted for reducing the dependence on batteries and developing the systems that produce energy by utilizing one's own actions during daily living activities. In this study, as a new approach to meet energy needs of active-controlled lower limb prostheses, the design of a biomechanical energy harvester that produces electrical energy from the movements of the knee joint during gait were carried out. This harvester is composed of the generator, planetary gear system and one-way clutch that transmit just the knee extension. Low weight, low additional metabolic power consumption requirement and high electrical power generation are targeted in design process. The total reduction ratio of the transmission is 104, and the knee joint reaction torque applied by the system is 6 Nm. Average electrical powers that can be obtained are 17 W and 5,8 W for the swing extension phase and the entire cycle, respectively. These values seem to be sufficient for charging the battery units of many prostheses and similar medical systems, and portable electronic devices such as mobile phones, navigation devices and laptops.

  4. Integrated biomechanical and topographical surface characterization (IBTSC)

    Energy Technology Data Exchange (ETDEWEB)

    Löberg, Johanna, E-mail: Johanna.Loberg@dentsply.com [Dentsply Implants, Box 14, SE-431 21 Mölndal (Sweden); Mattisson, Ingela [Dentsply Implants, Box 14, SE-431 21 Mölndal (Sweden); Ahlberg, Elisabet [Department of Chemistry and Molecular Biology, University of Gothenburg, SE-41296 Gothenburg (Sweden)

    2014-01-30

    In an attempt to reduce the need for animal studies in dental implant applications, a new model has been developed which combines well-known surface characterization methods with theoretical biomechanical calculations. The model has been named integrated biomechanical and topographical surface characterization (IBTSC), and gives a comprehensive description of the surface topography and the ability of the surface to induce retention strength with bone. IBTSC comprises determination of 3D-surface roughness parameters by using 3D-scanning electron microscopy (3D-SEM) and atomic force microscopy (AFM), and calculation of the ability of different surface topographies to induce retention strength in bone by using the local model. Inherent in this integrated approach is the use of a length scale analysis, which makes it possible to separate different size levels of surface features. The IBTSC concept is tested on surfaces with different level of hierarchy, induced by mechanical as well as chemical treatment. Sequential treatment with oxalic and hydrofluoric acid results in precipitated nano-sized features that increase the surface roughness and the surface slope on the sub-micro and nano levels. This surface shows the highest calculated shear strength using the local model. The validity, robustness and applicability of the IBTSC concept are demonstrated and discussed.

  5. Integrative Structural Biomechanical Concepts of Ankylosing Spondylitis

    Directory of Open Access Journals (Sweden)

    Alfonse T. Masi

    2011-01-01

    Full Text Available Ankylosing spondylitis (AS is not fully explained by inflammatory processes. Clinical, epidemiological, genetic, and course of disease features indicate additional host-related risk processes and predispositions. Collectively, the pattern of predisposition to onset in adolescent and young adult ages, male preponderance, and widely varied severity of AS is unique among rheumatic diseases. However, this pattern could reflect biomechanical and structural differences between the sexes, naturally occurring musculoskeletal changes over life cycles, and a population polymorphism. During juvenile development, the body is more flexible and weaker than during adolescent maturation and young adulthood, when strengthening and stiffening considerably increase. During middle and later ages, the musculoskeletal system again weakens. The novel concept of an innate axial myofascial hypertonicity reflects basic mechanobiological principles in human function, tissue reactivity, and pathology. However, these processes have been little studied and require critical testing. The proposed physical mechanisms likely interact with recognized immunobiological pathways. The structural biomechanical processes and tissue reactions might possibly precede initiation of other AS-related pathways. Research in the combined structural mechanobiology and immunobiology processes promises to improve understanding of the initiation and perpetuation of AS than prevailing concepts. The combined processes might better explain characteristic enthesopathic and inflammatory processes in AS.

  6. Modeling the biomechanics of fetal movements.

    Science.gov (United States)

    Verbruggen, Stefaan W; Loo, Jessica H W; Hayat, Tayyib T A; Hajnal, Joseph V; Rutherford, Mary A; Phillips, Andrew T M; Nowlan, Niamh C

    2016-08-01

    Fetal movements in the uterus are a natural part of development and are known to play an important role in normal musculoskeletal development. However, very little is known about the biomechanical stimuli that arise during movements in utero, despite these stimuli being crucial to normal bone and joint formation. Therefore, the objective of this study was to create a series of computational steps by which the forces generated during a kick in utero could be predicted from clinically observed fetal movements using novel cine-MRI data of three fetuses, aged 20-22 weeks. A custom tracking software was designed to characterize the movements of joints in utero, and average uterus deflection of [Formula: see text] mm due to kicking was calculated. These observed displacements provided boundary conditions for a finite element model of the uterine environment, predicting an average reaction force of [Formula: see text] N generated by a kick against the uterine wall. Finally, these data were applied as inputs for a musculoskeletal model of a fetal kick, resulting in predicted maximum forces in the muscles surrounding the hip joint of approximately 8 N, while higher maximum forces of approximately 21 N were predicted for the muscles surrounding the knee joint. This study provides a novel insight into the closed mechanical environment of the uterus, with an innovative method allowing elucidation of the biomechanical interaction of the developing fetus with its surroundings. PMID:26534772

  7. Biomechanics of Counterweighted One-Legged Cycling.

    Science.gov (United States)

    Elmer, Steven J; McDaniel, John; Martin, James C

    2016-02-01

    One-legged cycling has served as a valuable research tool and as a training and rehabilitation modality. Biomechanics of one-legged cycling are unnatural because the individual must actively lift the leg during flexion, which can be difficult to coordinate and cause premature fatigue. We compared ankle, knee, and hip biomechanics between two-legged, one-legged, and counterweighted (11.64 kg) one-legged cycling. Ten cyclists performed two-legged (240 W), one-legged (120 W), and counterweighted one-legged (120 W) cycling (80 rpm). Pedal forces and limb kinematics were recorded to determine work during extension and flexion. During counterweighted one-legged cycling relative ankle dorsiflexion, knee flexion, and hip flexion work were less than one-legged but greater than two-legged cycling (all P one-legged cycling were greater than one-legged but less than two-legged cycling (all P one-legged cycling reduced but did not eliminate differences in joint flexion and extension actions between one- and two-legged cycling. Even with these differences, counterweighted one-legged cycling seemed to have advantages over one-legged cycling. These results, along with previous work highlighting physiological characteristics and training adaptations to counterweighted one-legged cycling, demonstrate that this exercise is a viable alternative to one-legged cycling.

  8. Integrated biomechanical and topographical surface characterization (IBTSC)

    Science.gov (United States)

    Löberg, Johanna; Mattisson, Ingela; Ahlberg, Elisabet

    2014-01-01

    In an attempt to reduce the need for animal studies in dental implant applications, a new model has been developed which combines well-known surface characterization methods with theoretical biomechanical calculations. The model has been named integrated biomechanical and topographical surface characterization (IBTSC), and gives a comprehensive description of the surface topography and the ability of the surface to induce retention strength with bone. IBTSC comprises determination of 3D-surface roughness parameters by using 3D-scanning electron microscopy (3D-SEM) and atomic force microscopy (AFM), and calculation of the ability of different surface topographies to induce retention strength in bone by using the local model. Inherent in this integrated approach is the use of a length scale analysis, which makes it possible to separate different size levels of surface features. The IBTSC concept is tested on surfaces with different level of hierarchy, induced by mechanical as well as chemical treatment. Sequential treatment with oxalic and hydrofluoric acid results in precipitated nano-sized features that increase the surface roughness and the surface slope on the sub-micro and nano levels. This surface shows the highest calculated shear strength using the local model. The validity, robustness and applicability of the IBTSC concept are demonstrated and discussed.

  9. Fibrin-genipin adhesive hydrogel for annulus fibrosus repair: performance evaluation with large animal organ culture, in situ biomechanics, and in vivo degradation tests

    OpenAIRE

    Likhitpanichkul, M.; Dreischarf, M; S Illien-Junger; BA Walter; T Nukaga; RG Long; Sakai, D; AC Hecht; JC Iatridis

    2014-01-01

    Annulus fibrosus (AF) defects from annular tears, herniation, and discectomy procedures are associated with painful conditions and accelerated intervertebral disc (IVD) degeneration. Currently, no effective treatments exist to repair AF damage, restore IVD biomechanics and promote tissue regeneration. An injectable fibrin-genipin adhesive hydrogel (Fib-Gen) was evaluated for its performance repairing large AF defects in a bovine caudal IVD model using ex vivo organ culture and biomechanical t...

  10. Longitudinal Decline in Lung Function Measurements among Saskatchewan Grain Workers

    Directory of Open Access Journals (Sweden)

    Punam Pahwa

    2003-01-01

    Full Text Available OBJECTIVE: To evaluate the relationship between the long term effects of grain dust and decline in lung function among grain elevator workers in Saskatchewan, studied over a 15-year period.

  11. The fertility decline in Kenya.

    Science.gov (United States)

    Robinson, W C; Harbison, S F

    1995-01-01

    In Sub-Saharan Africa Kenya is a prime example of a country experiencing a rapid decline in fertility and greater contraceptive prevalence. These changes have occurred since 1980 when fertility was high at 8.0 children per woman. In 1993 the total fertility rate (TFR) was 5.4, and the growth rate declined to about 2.0%. This transition is swifter than any country in contemporary Asia or historical Europe. The likely projection for Kenya is attainment of replacement level fertility during the 2020s and a leveling of population at about 100 million persons. Fertility has declined the most in urban areas and central and eastern regions. Bongaarts' proximate determinants (TFR, total marital fertility rate, total natural marital fertility rate, and total fecundity) are reduced to the proportion of currently married women using contraception, the proportion in lactational nonfecund status, and the proportion currently married. Actual fertility change is accounted for by total fertility change of 3.0 children. Lactational infecundability accounts for 0.5 potential births, and changes in marital fertility account for 1.0 reduced births per woman. About 70% of fertility reduction is accounted for by contraception and abortion. During 1977-78 80% of fertility control was due to lactational nonfecundity, 10% to nonmarriage, and 10% to contraception. In 1993 lactational nonfecundity accounted for 50% of the reduction, nonmarriage for 20%, and abortion about 30%. Future fertility is expected to be dependent on contraceptive prevalence. Kenya has experienced the Coale paradigm of preconditions necessary for demographic transition (willing, ready, and able). High fertility in Africa is not intractable. Creating the change in attitudes that leads to readiness is linked to education, health, and exposure to modernizing media and urban lifestyles. The public sector family planning program in Kenya has created the opportunity for access and availability of contraception. The key

  12. Declining Efficiency in the Economy

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen

    1995-01-01

    The paper discusses the concept of resource efficiency in the economy as a whole. This implies some unfoldings of the simple definition of efficiency as human satisfaction over throughput of resources. It is suggested, that the efficiency of the economic systems is declining in the countries...... with a high material standard of living. Examples are presented as are suggestions for how to improve the efficiency. These improvements, however, have a tendency to reduce the gross domestic product and hence are conflicting with the conventional political goals of growing GDP....

  13. Biomechanics of Forearm Rotation: Force and Efficiency of Pronator Teres

    Science.gov (United States)

    Ibáñez-Gimeno, Pere; Galtés, Ignasi; Jordana, Xavier; Malgosa, Assumpció; Manyosa, Joan

    2014-01-01

    Biomechanical models are useful to assess the effect of muscular forces on bone structure. Using skeletal remains, we analyze pronator teres rotational efficiency and its force components throughout the entire flexion-extension and pronation-supination ranges by means of a new biomechanical model and 3D imaging techniques, and we explore the relationship between these parameters and skeletal structure. The results show that maximal efficiency is the highest in full elbow flexion and is close to forearm neutral position for each elbow angle. The vertical component of pronator teres force is the highest among all components and is greater in pronation and elbow extension. The radial component becomes negative in pronation and reaches lower values as the elbow flexes. Both components could enhance radial curvature, especially in pronation. The model also enables to calculate efficiency and force components simulating changes in osteometric parameters. An increase of radial curvature improves efficiency and displaces the position where the radial component becomes negative towards the end of pronation. A more proximal location of pronator teres radial enthesis and a larger humeral medial epicondyle increase efficiency and displace the position where this component becomes negative towards forearm neutral position, which enhances radial curvature. Efficiency is also affected by medial epicondylar orientation and carrying angle. Moreover, reaching an object and bringing it close to the face in a close-to-neutral position improve efficiency and entail an equilibrium between the forces affecting the elbow joint stability. When the upper-limb skeleton is used in positions of low efficiency, implying unbalanced force components, it undergoes plastic changes, which improve these parameters. These findings are useful for studies on ergonomics and orthopaedics, and the model could also be applied to fossil primates in order to infer their locomotor form. Moreover, activity

  14. Biomechanics of forearm rotation: force and efficiency of pronator teres.

    Directory of Open Access Journals (Sweden)

    Pere Ibáñez-Gimeno

    Full Text Available Biomechanical models are useful to assess the effect of muscular forces on bone structure. Using skeletal remains, we analyze pronator teres rotational efficiency and its force components throughout the entire flexion-extension and pronation-supination ranges by means of a new biomechanical model and 3D imaging techniques, and we explore the relationship between these parameters and skeletal structure. The results show that maximal efficiency is the highest in full elbow flexion and is close to forearm neutral position for each elbow angle. The vertical component of pronator teres force is the highest among all components and is greater in pronation and elbow extension. The radial component becomes negative in pronation and reaches lower values as the elbow flexes. Both components could enhance radial curvature, especially in pronation. The model also enables to calculate efficiency and force components simulating changes in osteometric parameters. An increase of radial curvature improves efficiency and displaces the position where the radial component becomes negative towards the end of pronation. A more proximal location of pronator teres radial enthesis and a larger humeral medial epicondyle increase efficiency and displace the position where this component becomes negative towards forearm neutral position, which enhances radial curvature. Efficiency is also affected by medial epicondylar orientation and carrying angle. Moreover, reaching an object and bringing it close to the face in a close-to-neutral position improve efficiency and entail an equilibrium between the forces affecting the elbow joint stability. When the upper-limb skeleton is used in positions of low efficiency, implying unbalanced force components, it undergoes plastic changes, which improve these parameters. These findings are useful for studies on ergonomics and orthopaedics, and the model could also be applied to fossil primates in order to infer their locomotor form

  15. Morphological characteristics of the developing proximal femur: A biomechanical perspective

    Directory of Open Access Journals (Sweden)

    Đurić Marija

    2012-01-01

    Full Text Available Introduction. In contrast to a plethora of studies on the proximal femur in adults, its external and internal morphology in growing children has not been sufficiently analyzed. Objective. We analyzed changes in external and internal morphology of the proximal femur during growth and development to interpret the links between them and concepts of the human femoral biomechanics. Methods. We assessed external geometry, internal trabecular and cortical arrangement, and bone mineral density (BMD of the proximal femur in 29 children (age at death from 1 month to 14 years from archaeological context by using microscopic and radiographic methods. Results. The results showed that both the femoral neck width and length increased with age, with the femoral neck becoming more elongated, while the collo-diaphyseal angle decreased. A strong relationship between age and adjusted areal BMD was found, showing continuous increase during childhood. Parallel trabecular pattern at birth changed to mature three distinct trabecular groups (longitudinal – principal compressive, transversal – tensile and randomly scattered starting from the age of 8 months. In older children the superior and inferior aspects of the femoral neck differently changed with growth, with medial neck having thicker cortex and trabeculae. Conclusion. In the light of bone adaptation principle, the observed changes in external and internal morphology are governed by mechanical forces acting on the developing femur. Our findings on the development of trabecular pattern and cortical distribution are compatible with recent views on the femoral biomechanics which point out the predominance of compressive stresses in the femoral neck, adaptation to shear stresses, multiaxial loading perspective, prevalence of muscle effects over body weight, and existence of adaptational eccentricity. [Projekat Ministarstva nauke Republike Srbije, br. 45005

  16. Gas in stems: abundance and potential consequences for tree biomechanics.

    Science.gov (United States)

    Gartner, Barbara L; Moore, John R; Gardiner, Barry A

    2004-11-01

    Secondary xylem of woody plants has a large volumetric proportion of gas occupying spaces that would otherwise be filled with water. We examined whether these gas-filled voids have a mechanical role by either decreasing the fresh mass the tree must support (by replacing some of the water with gas) or by providing inexpensive filler to increase stem diameter (thereby increasing the second moment of area at the expense of the modulus of elasticity and modulus of rupture). Calculations from published data show that temperate softwood species (n = 26) average 18 and 50% gas by volume for sapwood and heartwood, respectively; temperate hardwood species (n = 31) average 26% gas by volume in both the sapwood and heartwood; and tropical species (n = 52) with mixed sapwood and heartwood have 18% gas by volume. In this paper, we develop equations to show how gas affects the mechanical behavior of tree stems, and describe model results to show how gas affects mechanical stability, based on mass and stem diameters for six 34-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees. For the same applied load, modeled stems in which the gas space was filled with water differed in their surface stresses by Trees with gas removed had higher modulus of rupture, but could withstand up to 14% lower maximum wind forces than trees in their native state, suggesting a biomechanical role for the gas if the model assumptions are valid. The gas content may, however, have evolved in response to pressures unrelated to biomechanics. We discuss some of its potential effects on sapwood physiology.

  17. Effect and Countermeasure of School-age Population Decline on Higher Education%适龄人口下降对高等教育的影响及应对措施

    Institute of Scientific and Technical Information of China (English)

    童乃诚

    2013-01-01

      我国人口出生率下降导致了高等教育适龄人口下降,适龄人口下降对高等教育的生源数量、办学效益、教育结构、队伍建设和教育质量等带来影响。要减少这些影响,高等教育必须未雨绸缪,提前应对。应对的措施应该是政府统筹与市场竞争机制相结合,保持适度的办学规模,改革人事制度,拓展高等教育功能,调整高校发展思路,拓展生源市场,同时采取保护性措施扶持高职教育、民办教育和师范教育。%  Chinese birth rate decline led to a decline in school -age population in higher education.The decline in the school -age population had influenced on the number of higher education students 、school effectiveness、educa-tional structure、team -building、 the quality of education,etc.In order to reduce the effects, higher education should be prepared in advance .Measures is that to combine government and market competition mechanism to maintain the modest size of the student body ; to reform the personnel system for expanding higher education func -tions; to adjust the university & college development ideas for expanding the student market ; to take protective measures to support vocational education 、 private education and teacher education at the same time .

  18. Changes in Corneal Biomechanical Properties after Long-Term Topical Prostaglandin Therapy.

    Directory of Open Access Journals (Sweden)

    Na Wu

    Full Text Available To compare corneal biomechanical properties, measured by a newly developed tonometer (Corneal Visualization Scheimpflug Technology, Corvis ST, in untreated primary open angle glaucoma (POAG patients, POAG patients with long-term topical prostaglandin analog (PGA therapy and in normal controls. Further is to investigate the potential effects of PGA on corneal biomechanics.In this case-control study, 35 consecutive medication naïve eyes with POAG, 34 POAG eyes with at least 2 years treatment by PGA and 19 normal eyes were included. Intraocular pressure (IOP, central corneal thickness (CCT and corneal biomechanical parameters, including deformation amplitude (DA, applanation time (AT1 and AT2, applanation length (AL1 and AL2, applanation velocity (AV1 and AV2, and peak distance and radius were measured using Corvis ST. Axial length and corneal curvature were measured with partial coherence interferometry (IOLMaster, Zeiss, Germany. General linear model analysis was performed to investigate the corneal biomechanical property changes among the normal controls, newly diagnosed POAG patients and POAG patients with long-term PGA treatment, and among the subgroups of different types of PGA treatment, including bimatoprost, latanoprost and travoprost. Furthermore, pairwise comparisons using Bonferroni correction for least squares means were employed.AT1 (p<0.0001, AV1 (p<0.0001, AT2 (p = 0.0001, AV2 (p<0.0001 and DA (p = 0.0004 in newly diagnosed glaucoma patients were significantly different from those in normal subjects and in patients underwent at least 2 years topical PGA therapy after adjusting for age and gender. After adjusting for age, gender, IOP, CCT, axial length and corneal curvature, a significant difference was detected for DA between glaucoma patients without PGA treatment and patients with long-term PGA therapy (p = 0.0387. Furthermore, there were no statistical significant differences in all of the corneal biomechanical parameters among

  19. 运动生物力学实验教学内容改革及效果分析%Sport Biomechanics Experimental Reform of Teaching Contents and Effect Analysis

    Institute of Scientific and Technical Information of China (English)

    张念坤; 黄志刚

    2012-01-01

    To enrich the Biomechanics experiments teaching content,to improve the utilization of laboratory instruments,to develop students creativity and to solve practical problems ability.The article adjusts and supplements the experiment contents of the motion picture for continuous shooting,image analysis system for use and operation,image analysis and three-dimensional force measurement.The results show that exercise technical analysis significantly increased undergraduate thesis topics,elective students be enhanced motor skills,follow-up courses to improve learning,social practice and empowerment,sport biomechanics teaching quality and teaching has improved significantly.%为丰富运动生物力学实验教学内容,提高实验仪器使用率,发挥学生的创造力和动手解决实际问题的能力,对连续动作图片的拍摄、影像解析系统的使用与操作、影像解析及三维测力实验内容进行了补充和调整。结果表明,运动技术分析方面的本科毕业论文选题明显增多,选课学生动作技能得到提升,后续课程学习效果改善,社会实践能力得到增强,运动生物力学教学质量和教学效果明显提高。

  20. Ovariectomy decreases biomechanical quality of skin via oxidative stress in rat

    OpenAIRE

    Çömelekoğlu, Ülkü; YALIN, Serap; BALLI, Ebru; Berköz, Mehmet

    2012-01-01

    To investigate the effect of ovariectomy on the skin using biomechanical, biochemical, and histological techniques in the ovariectomized rat model. Ovariectomy causes significant changes in the physical characteristics of the skin. Materials and methods: Twenty female Wistar albino rats were divided into 2 groups, with each group consisting of 10 rats: the control group and the ovariectomized group. The ovariectomized group underwent bilateral ovariectomy via ventral incision and the contr...

  1. Fibrillin: from microfibril assembly to biomechanical function.

    Science.gov (United States)

    Kielty, Cay M; Baldock, Clair; Lee, David; Rock, Matthew J; Ashworth, Jane L; Shuttleworth, C Adrian

    2002-02-28

    Fibrillins form the structural framework of a unique and essential class of extracellular microfibrils that endow dynamic connective tissues with long-range elasticity. Their biological importance is emphasized by the linkage of fibrillin mutations to Marfan syndrome and related connective tissue disorders, which are associated with severe cardiovascular, ocular and skeletal defects. These microfibrils have a complex ultrastructure and it has proved a major challenge both to define their structural organization and to relate it to their biological function. However, new approaches have at last begun to reveal important insights into their molecular assembly, structural organization and biomechanical properties. This paper describes the current understanding of the molecular assembly of fibrillin molecules, the alignment of fibrillin molecules within microfibrils and the unique elastomeric properties of microfibrils.

  2. Biomechanics/risk management (Working Group 2)

    DEFF Research Database (Denmark)

    Sanz, Mariano; Naert, Ignace; Gotfredsen, Klaus

    2009-01-01

    INTRODUCTION: The remit of this workgroup was to update the existing knowledge base in biomechanical factors, navigation systems and medications that may affect the outcome of implant therapy. MATERIAL AND METHODS: The literature was systematically searched and critically reviewed. Five manuscrip...... of anticoagulants on patients undergoing oral implant therapy?...... in the following papers, together with the group consensus statements, clinical implications and directions for future research: * To what extent do cantilevers affect survival and complications of implant supported restorations in partially dentate patients? * To what extent does the crown-implant ratio affect...... survival and complications of implant supported restorations? * A systematic review on the accuracy and the clinical outcome of computer-guided template based implant dentistry. * What is the impact of systemic bisphosphonates on patients undergoing oral implant therapy? * What is the impact...

  3. Biomechanical Remodeling of the Diabetic Gastrointestinal Tract

    DEFF Research Database (Denmark)

    Zhao, Jingbo; Liao, Donghua; Yang, Jian;

    2010-01-01

    in diabetes mellitus is complex in nature, multi-factorial (motor dysfunction, autonomic neuropathy, glycemic control, psychological factors, etc.) and is not well understood. Histologically, many studies have demonstrated prominent proliferation of different GI wall layers during diabetes. During the past......Gastrointestinal tract sensory-motor abnormalities are common in patients with diabetes mellitus with symptoms arising from the whole GI tract. Common complaints include dysphasia, early satiety, reflux, constipation, abdominal pain, nausea, vomiting, and diarrhea. The pathogenesis of GI symptoms...... several years, several studies demonstrated that experimental diabetes induces GI morphological and biomechanical remodeling. Following the development of diabetes, the GI wall becomes thicker and the stiffness of the GI wall increases in a time-dependent manner. It is well known that mechanosensitive...

  4. Pathogenesis of varicose veins - lessons from biomechanics.

    Science.gov (United States)

    Pfisterer, Larissa; König, Gerd; Hecker, Markus; Korff, Thomas

    2014-03-01

    The development of varicose veins or chronic venous insufficiency is preceded by and associated with the pathophysiological remodelling of the venous wall. Recent work suggests that an increase in venous filling pressure is sufficient to promote varicose remodelling of veins by augmenting wall stress and activating venous endothelial and smooth muscle cells. In line with this, known risk factors such as prolonged standing or an obesity-induced increase in venous filling pressure may contribute to varicosis. This review focuses on biomechanically mediated mechanisms such as an increase in wall stress caused by venous hypertension or alterations in blood flow, which may be involved in the onset of varicose vein development. Finally, possible therapeutic options to counteract or delay the progress of this venous disease are discussed.

  5. Biomechanical Analysis of T2 Exercise

    Science.gov (United States)

    DeWitt, John K.; Ploutz-Snyder, Lori; Everett, Meghan; Newby, Nathaniel; Scott-Pandorf, Melissa; Guilliams, Mark E.

    2010-01-01

    Crewmembers regularly perform treadmill exercise on the ISS. With the implementation of T2 on ISS, there is now the capacity to obtain ground reaction force (GRF) data GRF data combined with video motion data allows biomechanical analyses to occur that generate joint torque estimates from exercise conditions. Knowledge of how speed and load influence joint torque will provide quantitative information on which exercise prescriptions can be based. The objective is to determine the joint kinematics, ground reaction forces, and joint kinetics associated with treadmill exercise on the ISS. This study will: 1) Determine if specific exercise speed and harness load combinations are superior to others in exercise benefit; and 2) Aid in the design of exercise prescriptions that will be most beneficial in maintaining crewmember health.

  6. Biomechanics of knee joint — A review

    Science.gov (United States)

    Madeti, Bhaskar Kumar; Chalamalasetti, Srinivasa Rao; Bolla Pragada, S. K. Sundara siva rao

    2015-06-01

    The present paper is to know how the work is carried out in the field of biomechanics of knee. Various model formulations are discussed and further classified into mathematical model, two-dimensional model and three-dimensional model. Knee geometry is a crucial part of human body movement, in which how various views of knee is shown in different planes and how the forces act on tibia and femur are studied. It leads to know the forces acting on the knee joint. Experimental studies of knee geometry and forces acting on knee shown by various researchers have been discussed, and comparisons of results are made. In addition, static and dynamic analysis of knee has been also discussed respectively to some extent.

  7. Protocol for Project FACT: a randomised controlled trial on the effect of a walking program and vitamin B supplementation on the rate of cognitive decline and psychosocial wellbeing in older adults with mild cognitive impairment [ISRCTN19227688

    Directory of Open Access Journals (Sweden)

    Hopman-Rock Marijke

    2005-12-01

    Full Text Available Abstract Background the prevalence of individuals with cognitive decline is increasing since the number of elderly adults is growing considerably. The literature provides promising results on the beneficial effect of exercise and vitamin supplementation on cognitive function both in cognitively healthy as well as in the demented elderly. Methods/Design the design is a two-by-two factorial randomised controlled trial. The study population consists of independently living elderly, between 70 and 80 years old, with mild cognitive impairment (MCI. In the RCT the effect of two interventions, a walking program and vitamin supplementation, is examined. The walking program (WP is a group-based program aimed at improving cardiovascular endurance; frequency two lessons a week; lesson duration one hour; program duration one year. Non-walking groups receive a placebo activity program (PAP (i.e. low intensive non-aerobic group exercises, like stretching with the same frequency, lesson and program duration. Vitamin supplementation consists of a single daily vitamin supplement containing 50 mg B6, 5 mg folic acid and 0,4 mg B12 for one year. Subjects not receiving vitamin supplements are daily taking an identically looking placebo pill, also for a year. Participants are randomised to four groups 1 WP and vitamin supplements; 2 WP and placebo supplements; 3 PAP and vitamin supplements; 4 PAP and placebo supplements. Primary outcome measures are measures of cognitive function. Secondary outcomes include psychosocial wellbeing, physical activity, cardiovascular endurance and blood vitamin levels. Discussion no large intervention study has been conducted yet on the effect of physical activity and vitamin supplementation in a population-based sample of adults with MCI. The objective of the present article is to describe the design of a randomised controlled trial examining the effect of a walking program and vitamin B supplementation on the rate of cognitive

  8. Effects of exercise programs to prevent decline in health-related quality of life in highly deconditioned institutionalized elderly persons: a randomized controlled trial.

    NARCIS (Netherlands)

    Dechamps, A.A.; Diolez, P.; Thiaudiere, E.; Tulon, A.; Onifade, C.; Vuong, T.; Helmer, C.; Bourdel-Marchasson, I.

    2010-01-01

    BACKGROUND: Our objective was to assess the effects of targeted exercise programs on health-related quality of life compared with usual care based on the ability to perform activities of daily living (ADL) and the Neuropsychiatric Inventory scores in geriatric institutionalized persons. METHODS: A r

  9. Wheelchair propulsion biomechanics: implications for wheelchair sports.

    Science.gov (United States)

    Vanlandewijck, Y; Theisen, D; Daly, D

    2001-01-01

    The aim of this article is to provide the reader with a state-of-the-art review on biomechanics in hand rim wheelchair propulsion, with special attention to sport-specific implications. Biomechanical studies in wheelchair sports mainly aim at optimising sport performance or preventing sport injuries. The sports performance optimisation question has been approached from an ergonomic, as well as a skill proficiency perspective. Sports medical issues have been addressed in wheelchair sports mainly because of the extremely high prevalence of repetitive strain injuries such as shoulder impingement and carpal tunnel syndrome. Sports performance as well as sports medical reflections are made throughout the review. Insight in the underlying musculoskeletal mechanisms of hand rim wheelchair propulsion has been achieved through a combination of experimental data collection under realistic conditions, with a more fundamental mathematical modelling approach. Through a synchronised analysis of the movement pattern, force generation pattern and muscular activity pattern, insight has been gained in the hand rim wheelchair propulsion dynamics of people with a disability, varying in level of physical activity and functional potential. The limiting environment of a laboratory, however, has hampered the drawing of sound conclusions. Through mathematical modelling, simulation and optimisation (minimising injury and maximising performance), insight in the underlying musculoskeletal mechanisms during wheelchair propulsion is sought. The surplus value of inverse and forward dynamic simulation of hand rim stroke dynamics is addressed. Implications for hand rim wheelchair sports are discussed. Wheelchair racing, basketball and rugby were chosen because of the significance and differences in sport-specific movement dynamics. Conclusions can easily be transferred to other wheelchair sports where movement dynamics are fundamental. PMID:11347685

  10. Laryngeal biomechanics of the singing voice.

    Science.gov (United States)

    Koufman, J A; Radomski, T A; Joharji, G M; Russell, G B; Pillsbury, D C

    1996-12-01

    By transnasal fiberoptic laryngoscopy, patients with functional voice often demonstrate abnormal laryngeal biomechanics, commonly supraglottic contraction. Appropriately, such conditions are sometimes termed muscle tension dysphonias. Singers working at the limits of their voice may also transiently demonstrate comparable tension patterns. However, the biomechanics of normal singing, particularly for different singing styles, have not been previously well characterized. We used transnasal fiberoptic laryngoscopy to study 100 healthy singers to assess patterns of laryngeal tension during normal singing and to determine whether factors such as sex, occupation, and style of singing influence laryngeal muscle tension. Thirty-nine male and 61 female singers were studied; 48 were professional singers, and 52 were amateurs. Examinations of study subjects performing standardized and nonstandardized singing tasks were recorded on a laser disk and subsequently analyzed in a frame-by-frame fashion by a blinded otolaryngologist. Each vocal task was graded for muscle tension by previously established criteria, and objective muscle tension scores were computed. The muscle tension score was expressed as a percentage of frames for each task with one of the laryngeal muscle tension patterns shown. The lowest muscle tension scores were seen in female professional singers, and the highest muscle tension scores were seen in amateur female singers. Male singers (professional and amateur) had intermediate muscle tension scores. Classical singers had lower muscle tension scores than nonclassical singers, with the lowest muscle tension scores being seen in those singing choral music (41%), art song (47%), and opera (57%), and the highest being seen in those singing jazz/pop (65%), musical theater (74%), bluegrass/country and western (86%), and rock/gospel (94%). Analyzed also were the influences of vocal nodules, prior vocal training, number of performance and practice hours per week

  11. Biomechanical research in dance: a literature review.

    Science.gov (United States)

    Krasnow, Donna; Wilmerding, M Virginia; Stecyk, Shane; Wyon, Matthew; Koutedakis, Yiannis

    2011-03-01

    The authors reviewed the literature, published from 1970 through December 2009, on biomechanical research in dance. To identify articles, the authors used search engines, including PubMed and Web of Science, five previous review articles, the Dance Medicine and Science Bibliography, and reference lists of theses, dissertations, and articles being reviewed. Any dance research articles (English language) involving the use of electromyography, forceplates, motion analysis using photography, cinematography or videography, and/or physics analysis were included. A total of 89 papers, theses/dissertations, and abstracts were identified and reviewed, grouped by the movement concept or specialized movements being studied: alignment (n = 8), plié (8), relevé (8), passé (3), degagé (3), développé (7), rond de jambe (3), grand battement (4), arm movements (1), forward stepping (3), turns (6), elevation work (28), falls (1), and dance-specific motor strategies (6). Several recurring themes emerged from these studies: that elite dancers demonstrate different and superior motor strategies than novices or nondancers; that dancers perform differently when using a barre as opposed to without a barre, both in terms of muscle activation patterns and weight shift strategies; that while skilled dancers tend to be more consistent across multiple trials of a task, considerable variability is seen among participants, even when matched for background, years of training, body type, and other variables; and that dance teachers recommend methods of achieving movement skills that are inconsistent with optimal biomechanical function, as well as inconsistent with strategies employed by elite dancers. Measurement tools and the efficacy of study methodologies are also discussed. PMID:21442132

  12. Declining amphibian populations: a global phenomenon in conservation biology

    Directory of Open Access Journals (Sweden)

    Gardner, T.

    2001-01-01

    Full Text Available The majority of the recent reductions in the Earth's biodiversity can be attributed to direct human impacts on the environment. An increasing number of studies over the last decade have reported declines in amphibian populations in areas of pristine habitat. Such reports suggest the role of indirect factors and a global effect of human activities on natural systems. Declines in amphibian populations bear significant implications for the functioning of many terrestrial ecosystems, and may signify important implications for human welfare. A wide range of candidates have been proposed to explain amphibian population declines. However, it seems likely that the relevance of each factor is dependent upon the habitat type and species in question, and that complex synergistic effects between a number of environmental factors is of critical importance. Monitoring of amphibian populations to assess the extent and cause of declines is confounded by a number of ecological and methodological limitations.

  13. Biomechanical Comparison of Spinal Fusion Methods Using Interspinous Process Compressor and Pedicle Screw Fixation System Based on Finite Element Method

    Science.gov (United States)

    Choi, Jisoo; Kim, Sohee

    2016-01-01

    Objective To investigate the biomechanical effects of a newly proposed Interspinous Process Compressor (IPC) and compare with pedicle screw fixation at surgical and adjacent levels of lumbar spine. Methods A three dimensional finite element model of intact lumbar spine was constructed and two spinal fusion models using pedicle screw fixation system and a new type of interspinous devices, IPC, were developed. The biomechanical effects such as range of motion (ROM) and facet contact force were analyzed at surgical level (L3/4) and adjacent levels (L2/3, L4/5). In addition, the stress in adjacent intervertebral discs (D2, D4) was investigated. Results The entire results show biomechanical parameters such as ROM, facet contact force, and stress in adjacent intervertebral discs were similar between PLIF and IPC models in all motions based on the assumption that the implants were perfectly fused with the spine. Conclusion The newly proposed fusion device, IPC, had similar fusion effect at surgical level, and biomechanical effects at adjacent levels were also similar with those of pedicle screw fixation system. However, for clinical applications, real fusion effect between spinous process and hooks, duration of fusion, and influence on spinous process need to be investigated through clinical study. PMID:26962413

  14. Effects of high voltage electrical stimulation on the rate of pH decline, meat quality and color stability in chilled beef carcasses

    Institute of Scientific and Technical Information of China (English)

    Ehsan Gharib Mombeni; Manoochehr Gharib Mombeini; Lucas Chaves Figueiredo; Debora Testoni Dias

    2013-01-01

    Objective:To determine the effects of high voltage electrical stimulation (HVES, 800 Voltage) on rapid decreases in pH values and improvements in meat quality. Methods:A total of 50 beef carcasses were applied, divided into two groups, one as a control and another for HVES. Meat quality was evaluated based on M. longissimus dorsi by examining pH and temperature levels at 1, 2, 5, 10 and 24 h, while color stability was examined seven days after slaughter. Results:HVES decreased the pH values of the meat and accelerated rigor mortis (P Conclusion:the HVES had positive effects on meat quality and color stability, in contrast to undesirable consumer preferences.

  15. Investigating the effects of decline of participatiation of citizens in directing urban zones (A case study of zone number 3 in Shiraz city

    Directory of Open Access Journals (Sweden)

    Masoud Taghvaie

    2010-10-01

    Full Text Available Abstract   The present research aims to identify effective factors on the reduction of social cooperation with the purpose of attracting social cooperation in directing city zones (zone number 3 in Shiraz.The methodology of this research was based on documentary and survey methods. The statistical sample of this research contains people 18 years old and over who live in zone number 3 in Shiraz, of whom 385 individuals were chosen as the sample of this research using Cochran method. To collect data, a research made questionnaire (analysis of effective factors on social cooperation in directing city zones was utilized. The findings show that the effectiveness rate of cooperation, trust in executives and organizations, training, residency, education, motivation, and the role of the person in the family are preventing factors of social cooperation in directing the city zones (zone number 3 in Shiraz. Therefore, if responsible authorities are fond of removing the obstacles of social cooperation in directing the city zones (zone number 3 in Shiraz, they should think about above mentioned obstacles and decide on these items for their long term goals.      * Correspondent Author: 09133273643 Email:m.tahgvaei@ltr.ui.ac.ir

  16. Evaluating the Association between Diabetes, Cognitive Decline and Dementia

    OpenAIRE

    Omorogieva Ojo; Joanne Brooke

    2015-01-01

    The aim of this article is to review the association between diabetes mellitus, cognitive decline and dementia, including the effects of cognitive decline and dementia on self management of diabetes. This is a literature review of primary research articles. A number of contemporary research articles that met the inclusion criteria were selected for this review paper. These articles were selected using a number of search strategies and electronic databases, such as EBSCOhost Research and Swet...

  17. VASCULAR RISK FACTORS AND COGNITIVE DECLINE IN A POPULATION SAMPLE

    OpenAIRE

    Ganguli, Mary; Fu, Bo; Snitz, Beth E.; Unverzagt, Frederick W.; Loewenstein, David A; Hughes, Tiffany F.; Chang, Chung-Chou H.

    2014-01-01

    We examined several vascular factors in relation to rates of decline in five cognitive domains in a population-based cohort. In an age-stratified random sample (N=1982) aged 65+ years, we assessed at baseline the cognitive domains of attention, executive function, memory, language, and visuospatial function, and also vascular, inflammatory, and metabolic indices. Random effects models generated slopes of cognitive decline over the next four years; linear models identified vascular factors ass...

  18. Application of techniques of biomechanics in the status evaluation and pathology correction of locomotor system

    Directory of Open Access Journals (Sweden)

    Romakina N.A.

    2015-09-01

    Full Text Available The article deals with the problem of development and the modern state of biomechanics as a scientific and practical direction in medicine under the context of technological advance herein a specific attention is paid to the achievements of the Russian schools. It is shown a necessity of wide usage of instrumental biomechanical diagnostics of locomotive disorders for intrinsic substantiation of rehabilitation treatment tactics and monitoring of its medical efficiency particularly for persons with remote effects of surgical interventions such as osteosynthesis, spondylosynthesis, total joint replacements. Non-invasive technique, possibility of its multiple application and rather low cost make actual using of locomotion clinical analysis techniques for rehabilitation treatment of concerned patients of different age groups.

  19. Individual athletes’ biomechanical features of interaction with objects in art gymnastics

    Directory of Open Access Journals (Sweden)

    Adashevskiy V.M.

    2014-04-01

    Full Text Available Purpose: To design a biomechanical model of interaction of athlete with the subject, as well as the development of areas of its use in practice. Material : The study involved 10 students - athletes. Results : The presented computational schemes create direction of flight of different items (rope, hoop, ball, ribbon, clubs. The characteristics of the time of flight trajectories and with regard for the resistance force of the air environment. Shows the influence of initial parameters on departure flight time items. Graphic characteristics are presented trajectories of objects depending on the parameters of their departure. Conclusions : It is recommended to improve the judicial assessment and effective implementation gymnast exercises during the flight characteristics of the various items to consider trajectories of objects. Note that age, height and distance from the athletes at the end of the flight object defined biomechanical characteristics that can realize an athlete: absolute initial velocity of departure, departure angle, height of the center of mass manufacture items.

  20. On seed physiology, biomechanics and plant phenology in Eragrostis tef

    NARCIS (Netherlands)

    Delden, van S.H.

    2011-01-01

    • Key words: Teff (Eragrostis tef (Zuccagni) Trotter), germination, temperature, model, leaf appearance, phyllochron, development rate, lodging, biomechanics, safety factor, flowering, heading, day length, photoperiod. • Background Teff (Eragrostis tef (Zuccagni) Trotter) is a C4 annual g

  1. Soft Tissue Biomechanical Modeling for Computer Assisted Surgery

    CERN Document Server

    2012-01-01

      This volume focuses on the biomechanical modeling of biological tissues in the context of Computer Assisted Surgery (CAS). More specifically, deformable soft tissues are addressed since they are the subject of the most recent developments in this field. The pioneering works on this CAS topic date from the 1980's, with applications in orthopaedics and biomechanical models of bones. More recently, however, biomechanical models of soft tissues have been proposed since most of the human body is made of soft organs that can be deformed by the surgical gesture. Such models are much more complicated to handle since the tissues can be subject to large deformations (non-linear geometrical framework) as well as complex stress/strain relationships (non-linear mechanical framework). Part 1 of the volume presents biomechanical models that have been developed in a CAS context and used during surgery. This is particularly new since most of the soft tissues models already proposed concern Computer Assisted Planning, with ...

  2. Keratoconus: A biomechanical perspective on loss of corneal stiffness

    Directory of Open Access Journals (Sweden)

    Abhijit Sinha Roy

    2013-01-01

    Full Text Available Keratoconus (KC is progressive disease of corneal thinning, steepening and collagen degradation. Biomechanics of the cornea is maintained by the intricate collagen network, which is responsible for its unique shape and function. With the disruption of this collagen network, the cornea loses its shape and function, resulting in progressive visual degradation. While KC is essentially a stromal disease, there is evidence that the epithelium undergoes significant thinning similar to the stroma. Several topographical approaches have been developed to detect KC early. However, it is now hypothesized that biomechanical destabilization of the cornea may precede topographic evidence of KC. Biomechanics of KC has been investigated only to a limited extent due to lack of in vivo measurement techniques and/or devices. In this review, we focus on recent work performed to characterize the biomechanical characteristics of KC.

  3. Waves and high nutrient loads jointly decrease survival and separately affect morphological and biomechanical properties in the seagrass

    NARCIS (Netherlands)

    La Nafie, Y.A.; de los Santos, C.B.; Brun, F.G.; van Katwijk, M.M.; Bouma, T.J.

    2012-01-01

    In an 8-week aquarium experiment, we investigated the interactive effects of waves (present vs. absent) and water-column nutrient level (high vs. low) on the survival, growth, morphology, and biomechanics of the seagrass, Zostera noltii. Survival was reduced when plants were exposed to both waves an

  4. Design of a Passive Exoskeleton for the Upper Extremity through Co-simulation with a Biomechanical Human Arm Model

    DEFF Research Database (Denmark)

    Zhou, Lelai; Bai, Shaoping; Rasmussen, John

    2013-01-01

    , which allows designers to analyze and evaluate an exoskeleton for its functioning, effectively. A simulation platform is developed by integrating a biomechanical model of human body and the exoskeleton. With the proposed approach, two types of exoskeletons with gravity compensating capability...

  5. Iliotibial Band Syndrome in Runners: Biomechanical Implications and Exercise Interventions.

    Science.gov (United States)

    Baker, Robert L; Fredericson, Michael

    2016-02-01

    Iliotibial band syndrome (ITBS) has known biomechanical factors with an unclear explanation based on only strength and flexibility deficits. Neuromuscular coordination has emerged as a likely reason for kinematic faults guiding research toward motor control. This article discusses ITBS in relation to muscle performance factors, fascial considerations, epidemiology, functional anatomy, strength deficits, kinematics, iliotibial strain and strain rate, and biomechanical considerations. Evidence-based exercise approaches are reviewed for ITBS, including related methods used to train the posterior hip muscles.

  6. BIOMECHANICAL PRINCIPLES PHYSICAL REHABILITATION OF CHILDREN WITH CEREBRAL PALSY

    OpenAIRE

    S. D. Korshunov; K. V. Davletyarova; L. V. Kapilevich

    2016-01-01

    Aim. We studied the basic biomechanical principles of physical rehabilitation of children with cerebral palsy.Materials and methods. Methods of Motion Tracking and electromyography investigated the biomechanical characteristics of gait in children with cerebral palsy. It is shown that the main differences between dynamic stereotype walk pediatric patients is to delay moving forward center of gravity and the disorganization of the lower limb movements (especially knee) in the vertical plane. P...

  7. Iliotibial Band Syndrome in Runners: Biomechanical Implications and Exercise Interventions.

    Science.gov (United States)

    Baker, Robert L; Fredericson, Michael

    2016-02-01

    Iliotibial band syndrome (ITBS) has known biomechanical factors with an unclear explanation based on only strength and flexibility deficits. Neuromuscular coordination has emerged as a likely reason for kinematic faults guiding research toward motor control. This article discusses ITBS in relation to muscle performance factors, fascial considerations, epidemiology, functional anatomy, strength deficits, kinematics, iliotibial strain and strain rate, and biomechanical considerations. Evidence-based exercise approaches are reviewed for ITBS, including related methods used to train the posterior hip muscles. PMID:26616177

  8. Integrative biomechanics for tree ecology: beyond wood density and strength

    OpenAIRE

    Fournier, Mériem; Dlouhà, Jana; Jaouen, Gaëlle; Almeras, Tancrède

    2013-01-01

    International audience; Functional ecology has long considered the support function as important, but its biomechanical complexity is only just being elucidated. We show here that it can be described on the basis of four biomechanical traits, two safety traits against winds (SW) and self-buckling (SB), and two motricity traits involved in sustaining an upright position, tropic motion velocity (MV) and posture control (PC). All these traits are integrated at the tree scale, combining tree size...

  9. [Ozone decline and UV increase].

    Science.gov (United States)

    Winkler, P; Trepte, S

    2004-02-01

    The following results have been obtained from long-term observations on the ozone layer and UV at the Meteorological Observatory Hohenpeigenberg:The seasonally varying decline of the ozone layer determines the maximum exposure to UV. Since ozone decline shows the highest rates in the spring months the UV exposure has most strongly increased in this time of the year. This is especially important because in spring the human skin is not adapted to UV exposure. Weather changes from day to day can induce rapid ozone reductions in spring about -30% which in turn is followed by an increase in UV of about 40%. Clouds, especially the transparent cirrus clouds (high clouds consisting of ice particles) have increased in frequency during spring and fall while a decrease is observed in summer. This change in cloudiness reduces the daily UV dose in spring and fall while it is enhanced in summer. With increasing height above sea level UV rises by roughly 10% per 1000 m (rule of thumb). Snow reflects the UV-radiation by up to 80% enhancing the UV-doses at relevant conditions. Strong volcano eruptions destroy ozone in the stratosphere additionally during 1-2 years after the eruption. Therafter the ozone layer recovers. In April 1993, after the eruption of Mt. Pinatubo (1991), the UV burden was still 40% higher than average. Miniholes and streamers can appear unexpected on a short-time scale and cross over Central Europe within 1-2 days, thus enhancing UV irradiation. The human skin reacts to UV exposure depending on the type of skin. The campaign "Sonne(n) mit Verstand" of the Bavarian Ministries for Environment, for Health and for Education informs about the danger of UV radiation (see www.sonne-mit-ver-stand.de). The German Weather Service informs the public on present developments of the ozone layer and relevant topics byits ozone bulletin, which is also available via internet under (www.dwd.de/deFundE/Observator/MOHp/hp2/ozon/bulletin.htm). PMID:14770335

  10. Biomechanics of occlusion--implications for oral rehabilitation.

    Science.gov (United States)

    Peck, C C

    2016-03-01

    The dental occlusion is an important aspect of clinical dentistry; there are diverse functional demands ranging from highly precise tooth contacts to large crushing forces. Further, there are dogmatic, passionate and often diverging views on the relationship between the dental occlusion and various diseases and disorders including temporomandibular disorders, non-carious cervical lesions and tooth movement. This study provides an overview of the biomechanics of the masticatory system in the context of the dental occlusion's role in function. It explores the adaptation and precision of dental occlusion, its role in bite force, jaw movement, masticatory performance and its influence on the oro-facial musculoskeletal system. Biomechanics helps us better understand the structure and function of biological systems and consequently an understanding of the forces on, and displacements of, the dental occlusion. Biomechanics provides insight into the relationships between the dentition, jaws, temporomandibular joints, and muscles. Direct measurements of tooth contacts and forces are difficult, and biomechanical models have been developed to better understand the relationship between the occlusion and function. Importantly, biomechanical research will provide knowledge to help correct clinical misperceptions and inform better patient care. The masticatory system demonstrates a remarkable ability to adapt to a changing biomechanical environment and changes to the dental occlusion or other components of the musculoskeletal system tend to be well tolerated. PMID:26371622

  11. ARTIFICIAL INTELLIGENCE IN SPORTS BIOMECHANICS: NEW DAWN OR FALSE HOPE?

    Directory of Open Access Journals (Sweden)

    Roger Bartlett

    2006-12-01

    Full Text Available This article reviews developments in the use of Artificial Intelligence (AI in sports biomechanics over the last decade. It outlines possible uses of Expert Systems as diagnostic tools for evaluating faults in sports movements ('techniques' and presents some example knowledge rules for such an expert system. It then compares the analysis of sports techniques, in which Expert Systems have found little place to date, with gait analysis, in which they are routinely used. Consideration is then given to the use of Artificial Neural Networks (ANNs in sports biomechanics, focusing on Kohonen self-organizing maps, which have been the most widely used in technique analysis, and multi-layer networks, which have been far more widely used in biomechanics in general. Examples of the use of ANNs in sports biomechanics are presented for javelin and discus throwing, shot putting and football kicking. I also present an example of the use of Evolutionary Computation in movement optimization in the soccer throw in, which predicted an optimal technique close to that in the coaching literature. After briefly overviewing the use of AI in both sports science and biomechanics in general, the article concludes with some speculations about future uses of AI in sports biomechanics.

  12. A Biomechanical Approach to Assessing Hip Fracture Risk

    Science.gov (United States)

    Ellman, Rachel

    2009-01-01

    Bone loss in microgravity is well documented, but it is difficult to quantify how declines in bone mineral density (BMD) contribute to an astronaut's overall risk of fracture upon return. This study uses a biomechanical approach to assessing hip fracture risk, or Factor of Risk (Phi), which is defined as the ratio of applied load to bone strength. All long-duration NASA astronauts from Expeditions 1-18 were included in this study (n=25), while crewmembers who flew twice (n=2) were treated as separate subjects. Bone strength was estimated based on an empirical relationship between areal BMD at the hip, as measured by DXA, and failure load, as determined by mechanical testing of cadaver femora. Fall load during a sideways fall was calculated from a previously developed biomechanical model, which takes into account body weight, height, gender, and soft tissue thickness overlying the lateral aspect of the hip that serves to attenuate the impact force. While no statistical analyses have been performed yet, preliminary results show that males in this population have a higher FOR than females, with a post- flight Phi of 0.87 and 0.36, respectively. FOR increases 5.1% from preflight to postflight, while only one subject crossed the fracture "threshold" of Phi = 1, for a total of 2 subjects with a postflight Phi > 1. These results suggest that men may be at greater risk for hip fracture due largely in part to their relatively thin soft tissue padding as compared to women, since soft tissue thickness has the highest correlation (R(exp 2)= .53) with FOR of all subject-specific parameters. Future work will investigate changes in FOR during recovery to see if baseline risk levels are restored upon return to 1-g activity. While dual x-ray absorptiometry (DXA) is the most commonly used clinical measure of bone health, it fails to provide compartment-specific information that is useful in assessing changes to bone quality as a result of microgravity exposure. Peripheral

  13. Biomechanical effect of the iliac screw insertion depth on lumboiliac taxation construct%髂骨钉置入深度对腰椎-骨盆重建结构的生物力学影响

    Institute of Scientific and Technical Information of China (English)

    陈辉; 于滨生; 郑召民; 吕游; 张奎渤; 刘辉; 李佛保

    2008-01-01

    Objective To biomechanically compare the stability of the short and long iliae screw fixation constructs in lumboiliac reconstruction. Methods Seven adult human embalmed cadavers (L3- pelvis) were used. Using posterior spinal fixation system, L4-S1 pedicle screw fixation was performed. This was defined as intact state of the sacroiliac joint. After the intact test, total sacrum resection and L4-L5- pelvis reconstruction by pediele screw and iliac screw with different lengths were performed as follow: short screw group (as the length of exceeding 2 mm over ischial notch) and long screw group (as the length of exceeding 2 mm over anterior inferior iliac spine ). Using the 858 MTS material testing machine, biomechanical testing was performed under 800 N compression and 7 Nm torsion loading modes. At last, the axial pullout test of two iliac screws was executed. Construct stiffness in compression and torsion test, and maximum pullout force were analyzed. Results Insertion lengths of the short and long iliac screw were (70±2) mm and (138±4) mm respectively. The lumbopelvic reconstruction using short and long iliac screw, respectively restored 53.3%±13.6% and 57.6%±16.2% of the initial stiffness in compression testing, and respectively harvested 55.1%±11.9% and 62.5%±9.2% of the initial stiffness in torsion testing. No significant difference was detected between the two reconstructions (P>0.05), however, the compressive and torsional stiffness of the two techniques were markedly less than the intact condition (P0.05);但是,两者的轴向压缩及旋转刚度均显著低于完整状态组(P<0.05).髂骨长钉的最大拔出力显著高于髂骨短钉(P<0.05).结论 在生理载荷下,髂骨短钉的脊柱-骨盆重建结构可获得与髂骨长钉同等的力学稳定性;髂骨短钉的置入深度仅为长钉的一半,可降低置入的风险.但是,无论髂骨长钉或短钉的脊柱.骨盆重建装置均难以恢复局部的初始稳定性.

  14. Inter-assessor reliability of practice based biomechanical assessment of the foot and ankle

    Directory of Open Access Journals (Sweden)

    Jarvis Hannah L

    2012-06-01

    Full Text Available Abstract Background There is no consensus on which protocols should be used to assess foot and lower limb biomechanics in clinical practice. The reliability of many assessments has been questioned by previous research. The aim of this investigation was to (i identify (through consensus what biomechanical examinations are used in clinical practice and (ii evaluate the inter-assessor reliability of some of these examinations. Methods Part1: Using a modified Delphi technique 12 podiatrists derived consensus on the biomechanical examinations used in clinical practice. Part 2: Eleven podiatrists assessed 6 participants using a subset of the assessment protocol derived in Part 1. Examinations were compared between assessors. Results Clinicians choose to estimate rather than quantitatively measure foot position and motion. Poor inter-assessor reliability was recorded for all examinations. Intra-class correlation coefficient values (ICC for relaxed calcaneal stance position were less than 0.23 and were less than 0.14 for neutral calcaneal stance position. For the examination of ankle joint dorsiflexion, ICC values suggest moderate reliability (less than 0.61. The results of a random effects ANOVA highlight that participant (up to 5.7°, assessor (up to 5.8° and random (up to 5.7° error all contribute to the total error (up to 9.5° for relaxed calcaneal stance position, up to 10.7° for the examination of ankle joint dorsiflexion. Kappa Fleiss values for categorisation of first ray position and mobility were less than 0.05 and for limb length assessment less than 0.02, indicating slight agreement. Conclusion Static biomechanical assessment of the foot, leg and lower limb is an important protocol in clinical practice, but the key examinations used to make inferences about dynamic foot function and to determine orthotic prescription are unreliable.

  15. Biomechanical Properties of a Novel Biodegradable Magnesium-Based Interference Screw.

    Science.gov (United States)

    Ezechieli, Marco; Meyer, Hanna; Lucas, Arne; Helmecke, Patrick; Becher, Christoph; Calliess, Tilman; Windhagen, Henning; Ettinger, Max

    2016-06-27

    Magnesium-based interference screws may be an alternative in anterior/posterior cruciate ligament reconstruction. The well-known osteoconductive effects of biodegradable magnesium alloys may be useful. It was the purpose of this study to evaluate the biomechanical properties of a magnesium based interference screw and compare it to a standard implant. A MgYREZr-alloy interference screw and a standard implant (Milagro®; De Puy Mitek, Raynham, MA, USA) were used for graft fixation. Specimens were placed into a tensile loading fixation of a servohydraulic testing machine. Biomechanical analysis included pretensioning of the constructs at 20 N for 1 min following cyclic pretensioning of 20 cycles between 20 and 60 N. Biomechanical elongation was evaluated with cyclic loading of 1000 cycles between 50 and 200 N at 0.5 Hz. Maximum load to failure was 511.3±66.5 N for the Milagro® screw and 529.0±63.3 N for magnesium-based screw (ns, P=0.57). Elongations after preload, during cyclical loading and during failure load were not different between the groups (ns, P>0.05). Stiffness was 121.1±13.8 N/mm for the magnesium-based screw and 144.1±18.4 for the Milagro® screw (ns, P=0.32). MgYREZr alloy interference screws show comparable results in biomechanical testing to standard implants and may be an alternative for anterior cruciate reconstruction in the future. PMID:27433303

  16. Biomechanical properties of a novel biodegradable magnesium-based interference screw

    Directory of Open Access Journals (Sweden)

    Marco Ezechieli

    2016-06-01

    Full Text Available Magnesium-based interference screws may be an alternative in anterior/posterior cruciate ligament reconstruction. The well-known osteoconductive effects of biodegradable magnesium alloys may be useful. It was the purpose of this study to evaluate the biomechanical properties of a magnesium based interference screw and compare it to a standard implant. A MgYREZr-alloy interference screw and a standard implant (Milagro®; De Puy Mitek, Raynham, MA, USA were used for graft fixation. Specimens were placed into a tensile loading fixation of a servohydraulic testing machine. Biomechanical analysis included pretensioning of the constructs at 20 N for 1 min following cyclic pretensioning of 20 cycles between 20 and 60 N. Biomechanical elongation was evaluated with cyclic loading of 1000 cycles between 50 and 200 N at 0.5 Hz. Maximum load to failure was 511.3±66.5 N for the Milagro® screw and 529.0±63.3 N for magnesium-based screw (ns, P=0.57. Elongations after preload, during cyclical loading and during failure load were not different between the groups (ns, P>0.05. Stiffness was 121.1±13.8 N/mm for the magnesiumbased screw and 144.1±18.4 for the Milagro® screw (ns, P=0.32. MgYREZr alloy interference screws show comparable results in biomechanical testing to standard implants and may be an alternative for anterior cruciate reconstruction in the future.

  17. Biomechanical metrics of aesthetic perception in dance.

    Science.gov (United States)

    Bronner, Shaw; Shippen, James

    2015-12-01

    The brain may be tuned to evaluate aesthetic perception through perceptual chunking when we observe the grace of the dancer. We modelled biomechanical metrics to explain biological determinants of aesthetic perception in dance. Eighteen expert (EXP) and intermediate (INT) dancers performed développé arabesque in three conditions: (1) slow tempo, (2) slow tempo with relevé, and (3) fast tempo. To compare biomechanical metrics of kinematic data, we calculated intra-excursion variability, principal component analysis (PCA), and dimensionless jerk for the gesture limb. Observers, all trained dancers, viewed motion capture stick figures of the trials and ranked each for aesthetic (1) proficiency and (2) movement smoothness. Statistical analyses included group by condition repeated-measures ANOVA for metric data; Mann-Whitney U rank and Friedman's rank tests for nonparametric rank data; Spearman's rho correlations to compare aesthetic rankings and metrics; and linear regression to examine which metric best quantified observers' aesthetic rankings, p < 0.05. The goodness of fit of the proposed models was determined using Akaike information criteria. Aesthetic proficiency and smoothness rankings of the dance movements revealed differences between groups and condition, p < 0.0001. EXP dancers were rated more aesthetically proficient than INT dancers. The slow and fast conditions were judged more aesthetically proficient than slow with relevé (p < 0.0001). Of the metrics, PCA best captured the differences due to group and condition. PCA also provided the most parsimonious model to explain aesthetic proficiency and smoothness rankings. By permitting organization of large data sets into simpler groupings, PCA may mirror the phenomenon of chunking in which the brain combines sensory motor elements into integrated units of behaviour. In this representation, the chunk of information which is remembered, and to which the observer reacts, is the elemental mode shape of

  18. Biomechanical rupture risk assessment of abdominal aortic aneurysms based on a novel probabilistic rupture risk index.

    Science.gov (United States)

    Polzer, Stanislav; Gasser, T Christian

    2015-12-01

    A rupture risk assessment is critical to the clinical treatment of abdominal aortic aneurysm (AAA) patients. The biomechanical AAA rupture risk assessment quantitatively integrates many known AAA rupture risk factors but the variability of risk predictions due to model input uncertainties remains a challenging limitation. This study derives a probabilistic rupture risk index (PRRI). Specifically, the uncertainties in AAA wall thickness and wall strength were considered, and wall stress was predicted with a state-of-the-art deterministic biomechanical model. The discriminative power of PRRI was tested in a diameter-matched cohort of ruptured (n = 7) and intact (n = 7) AAAs and compared to alternative risk assessment methods. Computed PRRI at 1.5 mean arterial pressure was significantly (p = 0.041) higher in ruptured AAAs (20.21(s.d. 14.15%)) than in intact AAAs (3.71(s.d. 5.77)%). PRRI showed a high sensitivity and specificity (discriminative power of 0.837) to discriminate between ruptured and intact AAA cases. The underlying statistical representation of stochastic data of wall thickness, wall strength and peak wall stress had only negligible effects on PRRI computations. Uncertainties in AAA wall stress predictions, the wide range of reported wall strength and the stochastic nature of failure motivate a probabilistic rupture risk assessment. Advanced AAA biomechanical modelling paired with a probabilistic rupture index definition as known from engineering risk assessment seems to be superior to a purely deterministic approach. PMID:26631334

  19. Does student learning style affect performance on different formats of biomechanics examinations?

    Science.gov (United States)

    Hsieh, Chengtu; Mache, Melissa; Knudson, Duane

    2012-03-01

    Students' learning style preferences have been widely adapted into teaching and learning environments. The purpose of this study was to investigate the relationship between self-reported and assessed learning style preferences (visual, auditory, reading/writing, kinesthetic: VARK) on performance in different types of multiple-choice examinations (T1: text only format and T2: visual format) given in an introductory biomechanics class. Students who enrolled in three biomechanics classes at a state university were recruited to participate in the study. Ninety students (47 males and 43 females) completed a learning style survey and two types of examinations. Results showed that approximately half of the students were assessed and self-reported as kinesthetic for their preferred learning style. There was no significant difference in test performance between students who preferred visual and reading/writing learning styles (self-reported and assessed). These students demonstrated similar learning and comprehension of biomechanical concepts regardless of whether the test material was presented in their preferred sensory mode or not. Interestingly, female students' perceptions of their learning style preference may have a positive effect on the test results when the test is presented in their preferred format. PMID:22518949

  20. Biomechanical and structural parameters of tendons in rats subjected to swimming exercise.

    Science.gov (United States)

    Bezerra, M A; Santos de Lira, K D; Coutinho, M P G; de Mesquita, G N; Novaes, K A; da Silva, R T B; de Brito Nascimento, A K; Inácio Teixeira, M F H B; Moraes, S R A

    2013-12-01

    The aim of this study was to evaluate the effect of swimming exercise, without overloading, on the biomechanical parameters of the calcaneal tendon of rats. 27 male Wistar rats (70 days) were distributed randomly into 2 groups, Control Group (CG; n=15) with restricted movements inside the cage and Swimming Group (SG; n=12), subjected to exercise training in a tank with a water temperature of 30±1°C, for 1 h/day, 5 days/week for 8 weeks. All animals were kept in a reversed light/dark cycle of 12 h with access to food and water ad libitum. After that, they were anesthetized and had their calcaneus tendons collected from their left rear paws. The tendon was submitted to a mechanical test on a conventional test machine. From the stress vs. strain curve, the biomechanical data were analyzed. For the statistical analysis, the Student-T test was used (pexercise training, without overloading, was an important stimulus for improving the biomechanical parameters and structural properties of the calcaneal tendon. PMID:23740340

  1. Structural and biomechanical changes in the Achilles tendon after chronic treatment with statins.

    Science.gov (United States)

    de Oliveira, L P; Vieira, C P; Guerra, F D; Almeida, M S; Pimentel, E R

    2015-03-01

    Cases of tendinopathy and tendon ruptures have been reported as side effects associated with statin therapy. This work assessed possible changes in the structural and biomechanical properties of the tendons after chronic treatment with statins. Wistar rats were divided into the following groups: treated with atorvastatin (A-20 and A-80), simvastatin (S-20 and S-80) and the group that received no treatment (C). The doses of statins were calculated using allometric scaling, based on the doses of 80 mg/day and 20 mg/day recommended for humans. The morphological aspect of the tendons in A-20, S-20 and S-80 presented signals consistent with degeneration. Both the groups A-80 and S-80 showed a less pronounced metachromasia in the compression region of the tendons. Measurements of birefringence showed that A-20, A-80 and S-80 groups had a lower degree of organization of the collagen fibers. In all of the groups treated with statins, the thickness of the epitenon was thinner when compared to the C group. In the biomechanical tests the tendons of the groups A-20, A-80 and S-20 were less resistant to rupture. Therefore, statins affected the organization of the collagen fibers and decreased the biomechanical strength of the tendons, making them more predisposed to ruptures. PMID:25544391

  2. A study on the effect of the corneal biomechanical properties undergoing overnight orthokeratology%角膜塑形术治疗近视眼安全性的探讨

    Institute of Scientific and Technical Information of China (English)

    毛欣杰; 黄橙赤; 陈琳; 吕帆

    2010-01-01

    Objective To evaluate the changes of corneal biomechanical properties and corneal topography undergoing overnight orthokeratology treatment. Methods Thirty teenagers with low andmoderate myopia with age of 11.67±1.63,myopia(-2.56±0.86)D,were included and were fitted with Ortho-K CL. The corneal biomechanical properties,including corneal hysteresis (CH),corneal resistance factor(CRF),goldmann-correlated lOP(IOPg) and corneal-compensated intraocular pressure(IOPcc) were measured with ocular response analyzer(ORA).Corneal topography,central corneal thickness(CCT) and corneal endothelium density were measured with computerized corneal topography,optical coherence tomography(OCT) and non contact specular microscope respectively.The measurements were taken at pre-wear,1 day and 7,30,90,180 days after orthokeratology.Only data from the right eyes were analysed.Results All subjects were significantly reduced the myopia amount after 1 day of lens Wear.The corneal curvature flattening(F=38.837,P<0.01)became slightly down to stable after the first week.There were significant decrease in CH and CRF after the orthokeratology treatment within the first week,and CH and CRF reversed and thereafeter into the original level at 3-month and 6-month follow up.IOPg and IOPcc decreased and reached the lowwest level at 1-week visit and after then became down to stable.There were significant reduction in CCT after 1 week(F=4.739,P<0.05).There were no significant changes in corneal endothelium density during orthokeratology treatment for 6 months.Conclusions The amount of myopia reduction with orthokeratology occurred mostly within 1 week while the corneal biomechanical properties such as CH and CRF were decreased. However the corneal biomechanical properties are reversal to the original level thereafter and remain unchanged within the 6 months follow up visits.It proves that orthokeratology does not demage corneal microsturcture.The early sign of reduction may due to the temporal

  3. DESIGN AND BIOMECHANICAL EVALUATION OF A RODENT SPINAL FIXATION DEVICE

    Science.gov (United States)

    Shahrokni, Maryam; Zhu, Qingan; Liu, Jie; Tetzlaff, Wolfram; Oxland, Thomas R.

    2016-01-01

    Structured Abstract Study Design An in vitro and in vivo study in rats. Objectives To design a novel rat spinal fixation device and investigate its biomechanical effectiveness in stabilizing the spine up to eight weeks post injury. Methods A fixation device made of polyetheretherketone was designed to stabilize the spine via bilateral clamping pieces. The device effectiveness was assessed in a Sprague-Dawley rat model after it was applied to a spine with a fracture-dislocation injury produced at C5–C6. Animals were euthanized either immediately (n=6) or eight weeks (n=9) post-injury and the C3-T1 segment of the cervical spine was removed for biomechanical evaluation. Segments of intact spinal columns (C3-T1) (n=6) served as uninjured controls. In these tests, anterior-posterior shear forces were applied to the C3 vertebra to produce flexion and extension bending moments at the injury site (peak 12.8Nmm). The resultant two-dimensional motions at the injury site (i.e. C5–C6) were measured using digital imaging and reported as ranges of motion (ROM) or neutral zones (NZ). Results Flexion/extension ROMs (average ± S.D.) were 18.1 ± 3.3°, 19.9 ± 7.5°, and 1.5 ± 0.7°, respectively for the intact, injured/fixed, and injured/8-week groups, with the differences being highly significant for the injured/8-week group (p=0.0002). Flexion/extension NZs were 3.4 ± 2.8°, 5.0 ± 2.4°, and 0.7 ± 0.5°, respectively for the intact, injured/fixed, and injured/8-week groups, with the differences being significant for the injured/8-week group (p =0.04). Conclusion The device acutely stabilizes the spine and promotes fusion at the site of injury. PMID:22289899

  4. Shape memory alloys: metallurgy, biocompatibility, and biomechanics for neurosurgical applications.

    Science.gov (United States)

    Hoh, Daniel J; Hoh, Brian L; Amar, Arun P; Wang, Michael Y

    2009-05-01

    SHAPE MEMORY ALLOYS possess distinct dynamic properties with particular applications in neurosurgery. Because of their unique physical characteristics, these materials are finding increasing application where resiliency, conformation, and actuation are needed. Nitinol, the most frequently manufactured shape memory alloy, responds to thermal and mechanical stimuli with remarkable mechanical properties such as shape memory effect, super-elasticity, and high damping capacity. Nitinol has found particular use in the biomedical community because of its excellent fatigue resistance and biocompatibility, with special interest in neurosurgical applications. The properties of nitinol and its diffusionless phase transformations contribute to these unique mechanical capabilities. The features of nitinol, particularly its shape memory effect, super-elasticity, damping capacity, as well as its biocompatibility and biomechanics are discussed herein. Current and future applications of nitinol and other shape memory alloys in endovascular, spinal, and minimally invasive neurosurgery are introduced. An understanding of the metallurgic properties of nitinol provides a foundation for further exploration of its use in neurosurgical implant design.

  5. Comparative biomechanics: life's physical world (second edition)

    CERN Document Server

    Vogel, Steven

    2013-01-01

    Why do you switch from walking to running at a specific speed? Why do tall trees rarely blow over in high winds? And why does a spore ejected into air at seventy miles per hour travel only a fraction of an inch? Comparative Biomechanics is the first and only textbook that takes a comprehensive look at the mechanical aspects of life--covering animals and plants, structure and movement, and solids and fluids. An ideal entry point into the ways living creatures interact with their immediate physical world, this revised and updated edition examines how the forms and activities of animals and plants reflect the materials available to nature, considers rules for fluid flow and structural design, and explores how organisms contend with environmental forces. Drawing on physics and mechanical engineering, Steven Vogel looks at how animals swim and fly, modes of terrestrial locomotion, organism responses to winds and water currents, circulatory and suspension-feeding systems, and the relationship between size and mech...

  6. The biomechanics of throwing: simplified and cogent.

    Science.gov (United States)

    Weber, Alexander E; Kontaxis, Andreas; O'Brien, Stephen J; Bedi, Asheesh

    2014-06-01

    The majority of shoulder injuries occur due to repetitive overhead movements, with baseball pitching being the most common mechanism for overuse injury. Before studying the treatment of these shoulder injuries, it is paramount that the health professional have an understanding of the etiology of and the underlying mechanisms for shoulder pathology. The act of overhead throwing is an eloquent full-body motion that requires tremendous coordination from the time of force generation to follow-through. The shoulder complex is a crucial component of the upper body kinetic chain as it transmits force created in the lower body to the arm and hand to produce velocity and accuracy with ball release. The focus of this article is on the biomechanics of the throwing motion, with emphasis on the kinematics of the shoulder. The established phases of the throwing motion will be reviewed in a stepwise manner and the contributions of osseous and soft-tissue structures to the successful completion of each phase will be discussed. PMID:24787720

  7. Perioperative Cognitive Decline in the Aging Population

    Science.gov (United States)

    Terrando, Niccolò; Brzezinski, Marek; Degos, Vincent; Eriksson, Lars I.; Kramer, Joel H.; Leung, Jacqueline M.; Miller, Bruce L.; Seeley, William W.; Vacas, Susana; Weiner, Michael W.; Yaffe, Kristine; Young, William L.; Xie, Zhongcong; Maze, Mervyn

    2011-01-01

    Elderly patients who have an acute illness or who undergo surgery often experience cognitive decline. The pathophysiologic mechanisms that cause neurodegeneration resulting in cognitive decline, including protein deposition and neuroinflammation, also play a role in animal models of surgery-induced cognitive decline. With the aging of the population, surgical candidates of advanced age with underlying neurodegeneration are encountered more often, raising concerns that, in patients with this combination, cognitive function will precipitously decline postoperatively. This special article is based on a symposium that the University of California, San Francisco, convened to explore the contributions of surgery and anesthesia to the development of cognitive decline in the aged patient. A road map to further elucidate the mechanisms, diagnosis, risk factors, mitigation, and treatment of postoperative cognitive decline in the elderly is provided. PMID:21878601

  8. The cause of global amphibian declines: a developmental endocrinologist's perspective.

    Science.gov (United States)

    Hayes, T B; Falso, P; Gallipeau, S; Stice, M

    2010-03-15

    Greater than 70% of the world's amphibian species are in decline. We propose that there is probably not a single cause for global amphibian declines and present a three-tiered hierarchical approach that addresses interactions among and between ultimate and proximate factors that contribute to amphibian declines. There are two immediate (proximate) causes of amphibian declines: death and decreased recruitment (reproductive failure). Although much attention has focused on death, few studies have addressed factors that contribute to declines as a result of failed recruitment. Further, a great deal of attention has focused on the role of pathogens in inducing diseases that cause death, but we suggest that pathogen success is profoundly affected by four other ultimate factors: atmospheric change, environmental pollutants, habitat modification and invasive species. Environmental pollutants arise as likely important factors in amphibian declines because they have realized potential to affect recruitment. Further, many studies have documented immunosuppressive effects of pesticides, suggesting a role for environmental contaminants in increased pathogen virulence and disease rates. Increased attention to recruitment and ultimate factors that interact with pathogens is important in addressing this global crisis.

  9. The cause of global amphibian declines: a developmental endocrinologist's perspective.

    Science.gov (United States)

    Hayes, T B; Falso, P; Gallipeau, S; Stice, M

    2010-03-15

    Greater than 70% of the world's amphibian species are in decline. We propose that there is probably not a single cause for global amphibian declines and present a three-tiered hierarchical approach that addresses interactions among and between ultimate and proximate factors that contribute to amphibian declines. There are two immediate (proximate) causes of amphibian declines: death and decreased recruitment (reproductive failure). Although much attention has focused on death, few studies have addressed factors that contribute to declines as a result of failed recruitment. Further, a great deal of attention has focused on the role of pathogens in inducing diseases that cause death, but we suggest that pathogen success is profoundly affected by four other ultimate factors: atmospheric change, environmental pollutants, habitat modification and invasive species. Environmental pollutants arise as likely important factors in amphibian declines because they have realized potential to affect recruitment. Further, many studies have documented immunosuppressive effects of pesticides, suggesting a role for environmental contaminants in increased pathogen virulence and disease rates. Increased attention to recruitment and ultimate factors that interact with pathogens is important in addressing this global crisis. PMID:20190117

  10. Stress and decline with forest trees. Stress und Decline bei Waldbaeumen

    Energy Technology Data Exchange (ETDEWEB)

    Tesche, M. (Technische Univ. Dresden, Tharandt (Germany, F.R.). Abt. Forstwirtschaft)

    1991-03-01

    Stress and decline are two terms used in a different manner in connection with current forest damages. Using examples, it is demonstrated that effects of complex environmental stress do not only depend upon the genotypic reaction capability of plants and the intensity of stress, but also on the combination and constellation as well as the way of influence exerted by individual stressors; low stress intensities lasting for a limited time can result in an adaption stimulation for plants, which should be called eustress and complex stress situations do not necessarily lead to an intensification of the effect caused by individual stressors and thus not to distress. Investigations carried out during or immediately after the impact of stress (instant effects) are not sufficient for diagnosing defence or adaptation reactions. Effects of this kind (memory effects) can only be identified in long-term experiments. From the results one can conclude that the 'decline-spiral-model' by MANION (1981) simplifies things too much, because it does not consider the defence and adaptation potential of plants. (orig.).

  11. The corneoscleral shell of the eye: potentials of assessing biomechanical parameters in normal and pathological conditions

    Directory of Open Access Journals (Sweden)

    E. N. Iomdina

    2016-01-01

    Full Text Available The paper reviews modern methods of evaluating the biomechanical properties of the corneoscleral shell of the eye that can be used both in the studies of the pathogenesis of various ophthalmic pathologies and in clinical practice. The biomechanical parameters of the cornea and the sclera have been shown to be diagnostically significant in assessing the risk of complications and the effectiveness of keratorefractive interventions, in the diagnosis and the prognosis of keratoconus, progressive myopia, or glaucoma. In clinical practice, a special device, Ocular Response Analyzer (ORA, has been used on a large scale. The analyzer is used to assess two parameters that characterize viscoelastic properties of the cornea — corneal hysteresis (CH and corneal resistance factor (CRF. Reduced levels of CH and CRF have been noted after eximer laser surgery, especially that administered to patients who demonstrate a regression in the refraction effect or suffer from keratoconus. This fact justifies the use of these biomechanical parameters as additional diagnostic criteria in the evaluation of the state of the cornea. At the same time, ORA data are shown to reflect the biomechanical response to the impact of the air pulse not only from the cornea alone but also from the whole corneoscleral capsule. This is probably the cause of reduced CH in children with progressive myopia and a weakened supportive function of the sclera, as well as such reduction in glaucomatous adult patients. It is hypothesized that a low CH value is a result of remodeling of the connective tissue matrix of the corneoscleral shell of the eye and can be an independent factor testifying to a risk of glaucoma progression. Reduced CH in primary open-angle glaucoma occurs in parallel with the development of pathological structural changes of the optic disc, and deterioration of visual fields, which is an evidence of a specific character and sensitivity of this parameter. The

  12. 全膝关节置换后关节线变化对髌股关节生物力学的影响%Effects of joint line changes on biomechanics of patellofemoral joint after total knee arthroplasty

    Institute of Scientific and Technical Information of China (English)

    王韬

    2016-01-01

    背景:全膝关节置换翻修的主要原因除感染外,聚乙烯衬垫磨损以及假体松动也是最常见的原因,关节线高度对髌股关节生物力学的影响尚无定论。目的:观察全膝关节置换后关节线变化对髌股关节生物力学的影响。方法:建立全膝关节置换后膝关节三维有限元模型,计算膝关节屈曲度在0°,30°,60°和90°时不同关节线高度对股四头肌拉力、骸韧带拉力和髌股关节间作用力变化的影响。结果与结论:①膝关节屈曲0°时,关节线高度在-3-4.5 mm变化对股四头肌拉力、膑腱拉力和髌股关节间作用力没有太大影响。②在膝关节屈曲30°-90°时,关节线高度在3 mm以下对股四头肌拉力、膑腱拉力和髌股关节间作用力影响不大;关节线高度超过3 mm对股四头肌拉力、膑腱拉力和髌股关节间作用力的影响比较明显。③因此建议全膝关节置换术中关节线的高度最好控制在正负3 mm以内。%BACKGROUND:In addition to infection, the reasons for total knee arthroplasty revision are polyethylene liner wear and prosthesis loosening. The impact of joint line height on patelofemoral biomechanics was inconclusive. OBJECTIVE: To study the impact of joint line changes after total knee arthroplasty on patelofemoral joint biomechanics. METHODS: Three-dimensional finite element models were established after total knee arthroplasty. The impact of different joint line height on quadriceps tensile force, patela tendon tension, and patelofemoral joint forces was calculated at range of flexion of 0°, 30°, 60° and 90°. RESULTS AND CONCLUSION: (1) At knee flexion of 0°, the height of the joint line in-3 mm-4.5 mm did not have great impacts on quadriceps tensile force, patela tendon tension and patelofemoral joint forces. (2) At knee flexion of 30°-90°, the height of the joint line below 3 mm did not have great impacts on quadriceps tensile force, patela tendon

  13. Wheelchair Propulsion Biomechanics in Junior Basketball Players: A Method for the Evaluation of the Efficacy of a Specific Training Program

    Science.gov (United States)

    Bergamini, Elena; Morelli, Francesca; Marchetti, Flavia; Vannozzi, Giuseppe; Polidori, Lorenzo; Paradisi, Francesco; Traballesi, Marco; Cappozzo, Aurelio; Delussu, Anna Sofia

    2015-01-01

    As participation in wheelchair sports increases, the need of quantitative assessment of biomechanical performance indicators and of sports- and population-specific training protocols has become central. The present study focuses on junior wheelchair basketball and aims at (i) proposing a method to identify biomechanical performance indicators of wheelchair propulsion using an instrumented in-field test and (ii) developing a training program specific for the considered population and assessing its efficacy using the proposed method. Twelve athletes (10 M, 2 F, age = 17.1 ± 2.7 years, years of practice = 4.5 ± 1.8) equipped with wheelchair- and wrist-mounted inertial sensors performed a 20-metre sprint test. Biomechanical parameters related to propulsion timing, progression force, and coordination were estimated from the measured accelerations and used in a regression model where the time to complete the test was set as dependent variable. Force- and coordination-related parameters accounted for 80% of the dependent variable variance. Based on these results, a training program was designed and administered for three months to six of the athletes (the others acting as control group). The biomechanical indicators proved to be effective in providing additional information about the wheelchair propulsion technique with respect to the final test outcome and demonstrated the efficacy of the developed program. PMID:26543852

  14. A selection of biomechanical research problems: From modeling to experimentation

    Science.gov (United States)

    Abbasi, Cyrus Omid

    The research undertakings within this manuscript illustrate the importance of biomechanics in today's science. Without doubt, biomechanics can be utilized to obtain a better understanding of many unsolved mysteries involved in the field of medicine. Moreover, biomechanics can be used to develop better prosthetic or surgical devices as well. Chapter 2 represents a medical problem, which has not been solved for more than a century. With the use of fundamental principles of biomechanics', a better insight of this problem and its possible causes were obtained. Chapter 3 investigates the mechanical interaction between the human teeth and some processed food products during mastication, which is a routine but crucial daily activity of a human being. Chapter 4 looks at a problem within the field of surgery. In this chapter the stability and reliability of two different Suturing-Techniques are explored. Chapters 5 and 6 represent new patent designs as a result of the investigations made in Chapter 4. Chapter 7 studies the impact and load transfer patterns during the collision between a child's head and the ground. All of the above mentioned chapters show the significance of biomechanics in solving a range of different medical problems that involve physical and or mechanical characters.

  15. New Trends in Dental Biomechanics with Photonics Technologies

    Directory of Open Access Journals (Sweden)

    Lídia Carvalho

    2015-11-01

    Full Text Available Engineering techniques used to evaluate strain-stress fields, materials’ mechanical properties, and load transfer mechanisms, among others, are useful tools in the study of biomechanical applications. These engineering tools, as experimental and numerical ones, were imported to biomechanics, in particular in dental biomechanics, a few decades ago. Several experimental techniques have been used in dental biomechanics, like photoelasticity, ESPI (Electronic Speckle Pattern Interferometry, strain gages, and other kinds of transducers. However, these techniques have some limitations. For instance, photoelasticity and ESPI give the overall field pattern of the strain, showing the stress-strain concentration points. These methods cannot give an accurate measurement at all points. On the contrary, strain gages can be used to perform local measurements. However, as they use electrical resistances, their use is limited to perform in vivo measurements. Optical fiber sensors have already been used in dentistry, for diagnostic and therapeutic purposes, and in dental biomechanics studies. Lasers have also been used in clinical dentistry for a few decades. Other optical technologies, like optical coherence tomography (OCT, became suitable for dental practice and nowadays it is perhaps one that has had more development in dentristry, along with lasers.

  16. Biomechanical analysis of plate stabilization on cervical part of spine

    Directory of Open Access Journals (Sweden)

    M. Kiel

    2009-07-01

    Full Text Available Purpose: The main aim of the work was determination of biomechanical analysis of cervical spine – stabilizer system made of stainless steel (Cr-Ni-Mo and Ti-6Al-4V alloy.Design/methodology/approach: To define biomechanical characteristic of the system the finite elements method (FEM was applied. Geometric model of part of spine C5-C7 and stabilizer were discretized by SOLID95 element. Appropriate boundary conditions imitating phenomena in real system with appropriate accuracy were established.Findings: The result of biomechanical analysis was calculation of displacements and stresses in the vertebras and the stabilizer in a function of the applied loading: 50-300 N for the stabilizer made of stainless steel (Cr-Ni-Mo and Ti-6Al-4V alloy.Research limitations/implications: The result of biomechanical analysis for plate stabilizer obtained by FEM can be use to determine a construction features of the stabilizer, and to select mechanical properties of metallic biomaterial and estimation of stabilization quality. The calculation of displacements for part C5-C7 show that the proposed type of stabilizer enables correct stabilization used to clinical apply.Practical implications: The results of biomechanical analysis showed correct mechanical properties used to made the plate stabilizer.Originality/value: The obtained numerical results should be verified in “in vitro” tests.

  17. Physical Activity and Obesity: Biomechanical and Physiological Key Concepts

    Directory of Open Access Journals (Sweden)

    Julie Nantel

    2011-01-01

    Full Text Available Overweight (OW and obesity (OB are often associated with low levels of physical activity. Physical activity is recommended to reduce excess body weight, prevent body weight regain, and decrease the subsequent risks of developing metabolic and orthopedic conditions. However, the impact of OW and OB on motor function and daily living activities must be taken into account. OW and OB are associated with musculoskeletal structure changes, decreased mobility, modification of the gait pattern, and changes in the absolute and relative energy expenditures for a given activity. While changes in the gait pattern have been reported at the ankle, knee, and hip, modifications at the knee level might be the most challenging for articular integrity. This review of the literature combines concepts and aims to provide insights into the prescription of physical activity for this population. Topics covered include the repercussions of OW and OB on biomechanical and physiological responses associated with the musculoskeletal system and daily physical activity. Special attention is given to the effect of OW and OB in youth during postural (standing and various locomotor (walking, running, and cycling activities.

  18. Muscular activity and its relationship to biomechanics and human performance

    Science.gov (United States)

    Ariel, Gideon

    1994-01-01

    The purpose of this manuscript is to address the issue of muscular activity, human motion, fitness, and exercise. Human activity is reviewed from the historical perspective as well as from the basics of muscular contraction, nervous system controls, mechanics, and biomechanical considerations. In addition, attention has been given to some of the principles involved in developing muscular adaptations through strength development. Brief descriptions and findings from a few studies are included. These experiments were conducted in order to investigate muscular adaptation to various exercise regimens. Different theories of strength development were studied and correlated to daily human movements. All measurement tools used represent state of the art exercise equipment and movement analysis. The information presented here is only a small attempt to understand the effects of exercise and conditioning on Earth with the objective of leading to greater knowledge concerning human responses during spaceflight. What makes life from nonliving objects is movement which is generated and controlled by biochemical substances. In mammals. the controlled activators are skeletal muscles and this muscular action is an integral process composed of mechanical, chemical, and neurological processes resulting in voluntary and involuntary motions. The scope of this discussion is limited to voluntary motion.

  19. Experimental model for civilian ballistic brain injury biomechanics quantification.

    Science.gov (United States)

    Zhang, Jiangyue; Yoganandan, Narayan; Pintar, Frank A; Guan, Yabo; Gennarelli, Thomas A

    2007-01-01

    Biomechanical quantification of projectile penetration using experimental head models can enhance the understanding of civilian ballistic brain injury and advance treatment. Two of the most commonly used handgun projectiles (25-cal, 275 m/s and 9 mm, 395 m/s) were discharged to spherical head models with gelatin and Sylgard simulants. Four ballistic pressure transducers recorded temporal pressure distributions at 308kHz, and temporal cavity dynamics were captured at 20,000 frames/second (fps) using high-speed digital video images. Pressures ranged from 644.6 to -92.8 kPa. Entry pressures in gelatin models were higher than exit pressures, whereas in Sylgard models entry pressures were lower or equivalent to exit pressures. Gelatin responded with brittle-type failure, while Sylgard demonstrated a ductile pattern through formation of micro-bubbles along projectile path. Temporary cavities in Sylgard models were 1.5-2x larger than gelatin models. Pressures in Sylgard models were more sensitive to projectile velocity and diameter increase, indicating Sylgard was more rate sensitive than gelatin. Based on failure patterns and brain tissue rate-sensitive characteristics, Sylgard was found to be an appropriate simulant. Compared with spherical projectile data, full-metal jacket (FMJ) projectiles produced different temporary cavity and pressures, demonstrating shape effects. Models using Sylgard gel and FMJ projectiles are appropriate to enhance understanding and mechanisms of ballistic brain injury.

  20. Growth Cone Biomechanics in Peripheral and Central Nervous System Neurons

    Science.gov (United States)

    Urbach, Jeffrey; Koch, Daniel; Rosoff, Will; Geller, Herbert

    2012-02-01

    The growth cone, a highly motile structure at the tip of an axon, integrates information about the local environment and modulates outgrowth and guidance, but little is known about effects of external mechanical cues and internal mechanical forces on growth-cone mediated guidance. We have investigated neurite outgrowth, traction forces and cytoskeletal substrate coupling on soft elastic substrates for dorsal root ganglion (DRG) neurons (from the peripheral nervous system) and hippocampal neurons (from the central) to see how the mechanics of the microenvironment affect different populations. We find that the biomechanics of DRG neurons are dramatically different from hippocampal, with DRG neurons displaying relatively large, steady traction forces and maximal outgrowth and forces on substrates of intermediate stiffness, while hippocampal neurons display weak, intermittent forces and limited dependence of outgrowth and forces on substrate stiffness. DRG growth cones have slower rates of retrograde actin flow and higher density of localized paxillin (a protein associated with substrate adhesion complexes) compared to hippocampal neurons, suggesting that the difference in force generation is due to stronger adhesions and therefore stronger substrate coupling in DRG growth cones.

  1. Biomechanical evaluation of an expansive pedicle screw in calf vertebrae

    Institute of Scientific and Technical Information of China (English)

    雷伟; 吴子祥

    2005-01-01

    Objective: To obtain a comprehensive understanding of the effect of the improvement of fixation strength of a newly designed expansive pedicle screw through biomechanical analyses.Metheds: 100 (200 pedicles) fresh calf lumber vertebrae were used. A total of four instrumentation systems were tested including CDH (CD Horizon), USS (Universal Spine System pedicle screw), Tenor (Sofamor Denek) and expansive pedicle screw (EPS). Pullout and turning-back tests were performed to compare the holding strength of the expansive pedicle screw with conventional screws, i.e. USS, CDH and Tenor. Revision tests were performed to evaluate the mechanical properties of the expansive pedicle screw as a "rescue" revision screw. A fatigue simulation using perpendicular load up to 1 500 000 cycles was carried out.Results: The turning back torque (Tmax) and pull-out force (Fmax) of EPS were significantly greater than those of USS, Tenor and CDH screws (6.5 mm×40 mm). In revision tests, the Fmax of both kinds of EPS (6.5 mm×40 mm; 7.0 mm×40 mm) were greater than that of CDH, USS and Tenor screws significantly (P<0.05). No screws were broken or bent at the end of fatigue tests.Conclusions: EPS can significantly improve the bone purchase and the pull-out strength compared to USS, Tenor and CDH screws with similar dimensions before and after failure simulation. The fatigue characteristic of EPS is similar to that of CDH, USS and Tenor screws.

  2. Anthropometry and Biomechanics Facility Spring 2016 Internship

    Science.gov (United States)

    Boppana, Abhishektha

    2016-01-01

    The Anthropometry and Biomechanics Facility (ABF) at Johnson Space Center supports the Space Human Factors Engineering portfolio of the Human Research Program. ABF provides capability to verify the accommodation and comfort of crewmembers through anthropometry and biomechanics analyses. Anthropometric measurements are derived from three-dimensional (3D) whole body scan images. The scans are currently taken by a Human Solutions Vitus 3D Laser Scanning System. ABF has purchased a 3dMD photogrammetry scanner system to speed up the process of collecting 3D scans. The photogrammetry scanner system features a faster data collection time, as well as fewer holes in the scans. This internship was mainly focused on developing calibration, measurement, data acquisition, and analysis processes for the new system. In addition, I also participated in a project to validate the use of a pressure mat sensor on the shoulder during in-suit testing. My duties for the scanner validation project started with identifying and documenting a calibration process. The calibration process proved vital to using the system as the quality of the scans was directly related to the success of the calibration. In addition, the calibration process suggested by the system vendor required the user to hold a large calibration board at precise locations. To aid in this, I built a calibration stand which held a calibration board at constant positions throughout numerous calibration process. The calibration process was tested extensively until proven acceptable. The standardized process reduced calibration time from over 10 minutes to just below three minutes. As a result, the calibration process could be completed painlessly and precisely, and scan quality was constant between sessions. After standardizing the calibration process, I proceeded to modify the locations of the cameras in order to capture the full volume of a person. The scanning system needed to capture a full T-pose of a person in one scan

  3. Effect of ultraviolet A (UVA) plus riboflavin induced collagen cross-linking on biomechanical properties of the sclera in guinea pigs%紫外光-核黄素交联法对豚鼠巩膜生物力学特性的影响

    Institute of Scientific and Technical Information of China (English)

    吕雅平; 周浩; 夏文涛; 褚仁远; 周行涛; 戴锦晖

    2012-01-01

    目的 探索紫外光-核黄素交联法对巩膜织张力和强度的影响.方法 交联组和对照组皆选右眼为实验眼,交联组采用波长为(370±5)nm、辐射强度定为3.0 mW/cm2的紫外线和0.1%核黄素为光敏剂对豚鼠赤道部巩膜面进行胶原交联,对照组不进行交联处理.术后一个月取交联组交联区巩膜条带和对照组相应区域的巩膜条带,进行生物力学测试,并对眼球各组织进行HE染色光镜和透射电镜检测.结果 交联组巩膜的生物力学特性增强,赤道部交联组巩膜试件断裂时的极限应力增加了147%,弹性模量显著增加了193%,极限应变降低了21.9%;后极部交联组巩膜试件断裂时的极限应力增加了108%,弹性模量显著增加了191%,极限应变降低了40.42%.HE染色光镜检查结果显示形态学无病理改变,透射电镜结果显示交联组交联区的巩膜成纤维细胞增生活跃.结论 紫外光-核黄素交联法可以有效地提高巩膜的生物力学特性,增强巩膜组织的张力和强度,有望作为治疗高度病理性近视的一种方法.%Objective To study the effect of collagen cross-linking induced by riboflavin and ultraviolet A ( UVA ) on biomechanical properties of the sclera in guinea pigs. Methods The changes of biomechanical properties of the sclera induced by riboflavin and ultraviolet A ( UVA)-induced collagen crosslinking were examined in ten guinea pigs and compared with those of ten non-treated guinea pigs. Histological and ultrastructural changes of the sclera were examined to evaluate the side-effects. Results At one month after the UVA plus riboflavin treatment, the ultimate stress increased by 147% , elastic modulus increased by 193% , ultimate strain reduced by 21.9% in the equatorial sclera and significantly changed by 108% , 191% , 40.42% in the posterior sclera, respectively. Light microscopy showed no pathological alterations. Transmission electron microscopy showed active

  4. Retirement Age Declines Again in 1990s.

    Science.gov (United States)

    Gendell, Murray

    2001-01-01

    The average retirement age continued to decline in the 1990s after having leveled off during the preceding 10-15 years. The resumption of the decline is attributed largely to a rise in the labor force participation rate of older men and women between the mid-1980s and 2000. (Author/JOW)

  5. How China Survives a Global Economic Decline

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Dark clouds are looming over the global economy. The Euro zone may only manage a paltry 1.5 percent growth next year. Meanwhile in the United States, labor, residential and consumer markets have all experienced a decline in growth. With rising fuel prices, a growing debt burden and a negative savings rate, the United States also is poised for further decline in consumption.

  6. Forest declines: Some perspectives on linking processes and patterns

    International Nuclear Information System (INIS)

    The regional decline in vigor of some species of forest trees has become an important component in the ecological, aesthetic, and economic criteria by which the costs of anthropogenic pollution are weighed. Because declines are often complex and virtually never without significant natural environmental modifiers, determining the role of specific anthropogenic stresses in initiating or enhancing the rate and direction of change in forest condition represents a significant research challenge. Separation of primary mechanisms that point to principal causes from secondary responses that result from internal feedbacks and the milieu of modifying agents is a critical issue in diagnosing forest decline. Air pollutant stress may have its most significant effects on forest processes by accelerating or amplifying natural stresses. Studies of changes in forest metabolic processes have played an important role in evaluating the role of air pollution in four regional forest declines that are the focus of this paper. The decline of ponderosa pine in the San Bernardino Mountains of California, Norway spruce and silver fir in Europe, loblolly and shortleaf pine in the Southeastern United States, and red spruce in the Eastern Appalachian Mountains provide case studies in which physiological responses to air pollutants under field and laboratory conditions have provided important analytical tools for assessing likely causes. These tools are most effective when both mechanistic explanations and larger scale patterns of response are evaluated in an iterative feedback loop that examines plausible mechanisms and patterns of response at levels ranging from cell membranes to plant populations

  7. Problem-Based Learning in Biomechanics: Advantages, Challenges, and Implementation Strategies.

    Science.gov (United States)

    Clyne, Alisa Morss; Billiar, Kristen L

    2016-07-01

    Problem-based learning (PBL) has been shown to be effective in biomedical engineering education, particularly in motivating student learning, increasing knowledge retention, and developing problem solving, communication, and teamwork skills. However, PBL adoption remains limited by real challenges in effective implementation. In this paper, we review the literature on advantages and challenges of PBL and present our own experiences. We also provide practical guidelines for implementing PBL, including two examples of PBL modules from biomechanics courses at two different institutions. Overall, we conclude that the benefits for both professors and students support the use of PBL in biomedical engineering education. PMID:27210616

  8. Problem-Based Learning in Biomechanics: Advantages, Challenges, and Implementation Strategies.

    Science.gov (United States)

    Clyne, Alisa Morss; Billiar, Kristen L

    2016-07-01

    Problem-based learning (PBL) has been shown to be effective in biomedical engineering education, particularly in motivating student learning, increasing knowledge retention, and developing problem solving, communication, and teamwork skills. However, PBL adoption remains limited by real challenges in effective implementation. In this paper, we review the literature on advantages and challenges of PBL and present our own experiences. We also provide practical guidelines for implementing PBL, including two examples of PBL modules from biomechanics courses at two different institutions. Overall, we conclude that the benefits for both professors and students support the use of PBL in biomedical engineering education.

  9. The increasing importance of the biomechanics of impact trauma

    Indian Academy of Sciences (India)

    Murray Mackay

    2007-08-01

    The evolution of experimental biomechanics and crash injury research is summarized briefly to show that they both play a major role in mitigating traffic deaths and injuries. Historically, the subject has been based largely in western countries and thus focused on vehicle occupants, whereas some 80% of traffic casualties in the world are outside the vehicle as pedestrians, cyclists and motorcyclists. The subject is close to the regulatory process which controls vehicle design and is thus heavily influenced by government and industry, yet it is now in an expanding period because of new techniques to replicate the human frame’s response to impact forces. New knowledge is likely to emerge from addressing population variations and combining real world accident investigations with experimental biomechanics. The application of impact biomechanics to the vulnerable road users is of particular importance.

  10. Biomechanics of Wheat/Barley Straw and Corn Stover

    Energy Technology Data Exchange (ETDEWEB)

    Christopher T. Wright; Peter A. Pryfogle; Nathan A. Stevens; Eric D. Steffler; J. Richard Hess; Thomas H. Ulrich

    2005-03-01

    The lack of understanding of the mechanical characteristics of cellulosic feedstocks is a limiting factor in economically collecting and processing crop residues, primarily wheat and barley stems and corn stover. Several testing methods, including compression, tension, and bend have been investigated to increase our understanding of the biomechanical behavior of cellulosic feedstocks. Biomechanical data from these tests can provide required input to numerical models and help advance harvesting, handling, and processing techniques. In addition, integrating the models with the complete data set from this study can identify potential tools for manipulating the biomechanical properties of plant varieties in such a manner as to optimize their physical characteristics to produce higher value biomass and more energy efficient harvesting practices.

  11. The biomechanical and structural properties of CS2 fimbriae

    CERN Document Server

    Mortezaei, Narges; Zakrisson, Johan; Bullitt, Esther; Andersson, Magnus

    2015-01-01

    Enterotoxigenic Escherichia coli (ETEC) are a major cause of diarrhea worldwide, and infection of children in underdeveloped countries often leads to high mortality rates. Isolated ETEC express a plethora of colonization factors (fimbriae/pili), of which CFA/I and CFA/II that are assembled via the alternate chaperone pathway (ACP), are amongst the most common. Fimbriae are filamentous structures, whose shafts are primarily composed of helically arranged single pilin-protein subunits, with a unique biomechanical capability allowing them to unwind and rewind. A sustained ETEC infection, under adverse conditions of dynamic shear forces, is primarily attributed to this biomechanical feature of ETEC fimbriae. Recent understandings about the role of fimbriae as virulence factors are pointing to an evolutionary adaptation of their structural and biomechanical features. In this work, we investigated the biophysical properties of CS2 fimbriae from the CFA/II group. Homology modelling its major structural subunit CotA ...

  12. Computational biomechanics for medicine imaging, modeling and computing

    CERN Document Server

    Doyle, Barry; Wittek, Adam; Nielsen, Poul; Miller, Karol

    2016-01-01

    The Computational Biomechanics for Medicine titles provide an opportunity for specialists in computational biomechanics to present their latest methodologies and advancements. This volume comprises eighteen of the newest approaches and applications of computational biomechanics, from researchers in Australia, New Zealand, USA, UK, Switzerland, Scotland, France and Russia. Some of the interesting topics discussed are: tailored computational models; traumatic brain injury; soft-tissue mechanics; medical image analysis; and clinically-relevant simulations. One of the greatest challenges facing the computational engineering community is to extend the success of computational mechanics to fields outside traditional engineering, in particular to biology, the biomedical sciences, and medicine. We hope the research presented within this book series will contribute to overcoming this grand challenge.

  13. Computational biomechanics for medicine new approaches and new applications

    CERN Document Server

    Miller, Karol; Wittek, Adam; Nielsen, Poul

    2015-01-01

    The Computational Biomechanics for Medicine titles provide an opportunity for specialists in computational biomechanics to present their latest methodologiesand advancements. Thisvolumecomprises twelve of the newest approaches and applications of computational biomechanics, from researchers in Australia, New Zealand, USA, France, Spain and Switzerland. Some of the interesting topics discussed are:real-time simulations; growth and remodelling of soft tissues; inverse and meshless solutions; medical image analysis; and patient-specific solid mechanics simulations. One of the greatest challenges facing the computational engineering community is to extend the success of computational mechanics to fields outside traditional engineering, in particular to biology, the biomedical sciences, and medicine. We hope the research presented within this book series will contribute to overcoming this grand challenge.

  14. Biomechanics of Load Carriage--Historical Perspectives and Recent Insights.

    Science.gov (United States)

    Seay, Joseph F

    2015-11-01

    Loads carried by the warfighter have increased substantially throughout recorded history, with the typical U.S. ground soldier carrying external loads averaging 45 kg during operations in Afghanistan. Incidence of disability in the U.S. Army has also increased sixfold since the 1980s, predominantly driven by increases in musculoskeletal injuries, with load carriage implicated as a possible mechanism. This article will provide a brief overview of the biomechanics of load carriage and will provide some recent insights into how the stress of the loads carried by military personnel can affect the musculoskeletal system. Studies into the biomechanics of load carriage have documented motion-related differences such as increased step rate, decreased stride length, and more trunk lean with increases in pack-borne loads. However, there is a paucity of literature on the relationship between load carriage and biomechanical mechanisms of overuse injury. Findings of recent studies will be presented, which add mechanistic information to increased stresses on the lower extremity. This was particularly true at the knee, where in one study, peak knee extension moment increased 115% when carrying a 55 kg load (0.87 ± 0.16 Nm·kg⁻¹) vs. no external load (0.40 ± 0.13 Nm·kg⁻¹). Efforts to model injury mechanisms require continued biomechanical measurements in humans while carrying occupationally relevant loads to be validated. Specifically, imaging technologies (e.g., bone geometry scans) should be incorporated to produce higher fidelity model of the stresses and strains experienced by the load carrier. In addition to laboratory-based biomechanics, data are needed to further explore the mechanistic relationship between load magnitude and injury; to this end, wearable sensors should continue to be exploited to accurately quantify biomechanical stresses related to load carriage in the field.

  15. Antitumor effect of COOH-terminal polypeptide of human TERT is associated with the declined expression of hTERT and NF-κB p65 in HeLa cells.

    Science.gov (United States)

    Wu, Xian; Chen, Jiasheng; Cao, Ying; Xie, Baoping; Li, Hongwei; Zhou, Pingzheng; Qiu, Yuchang; Pang, Jianxin

    2015-12-01

    Human telomerase reverse transcriptase (hTERT) plays an important role in the development of tumors and has been investigated as a potent target for anticancer therapy. In the present study, we constructed a recombinant adenovirus, Ad-EGFP-C197 which was capable of expressing COOH‑terminal polypeptide of hTERT (amino acid 936-1,132, termed as C197 for the reason that it contains 197 amino acids). Infection of HeLa cells with Ad-EGFP-C197 suppressed the activity of telomerase, decreased the expression of hTERT and NF-κB p65, and induced rapid growth delay and apoptosis of HeLa cells in vitro. In nude mice xenografted with HeLa tumors, injection of Ad-EGFP-C197 into the tumor nodule significantly slowed tumor growth and promoted tumor cell apoptosis, as well as reduced the expression of NF-κB p65 in tumor tissues. In the present study, we suggest that the antitumor effect of C197 is associated with the declined expression of hTERT and NF-κB p65. Our results highlight the potential of C197 in tumor therapy.

  16. Biomechanically Excited SMD Model of a Walking Pedestrian

    DEFF Research Database (Denmark)

    Zhang, Mengshi; Georgakis, Christos T.; Chen, Jun

    2016-01-01

    of biomechanical forces, was used to model a pedestrian for application in vertical human-structure interaction (HSI). Tests were undertaken in a gait laboratory, where a three-dimensional motion-capture system was used to record a pedestrian's walking motions at various frequencies. The motion-capture system...... to be scattered and not closely related to walking frequency. A generalized extreme value distribution was fit to each of the amplitudes. Phases in the model for biomechanical forces were not related to pacing frequency, and a mean value of the phases is proposed....

  17. The modern biomechanics technology in practice of preparedness athletes.

    Directory of Open Access Journals (Sweden)

    Akhmetov R.F.

    2011-01-01

    Full Text Available The generalized information about directions of application of biomechanics technologies in modern sport is resulted. Some aspects of the use of biomechanics ergogenical tools of the moved delayed action in the system of preparation of athletes-jumpers are considered. Presents the possibility of using training complex «easy leading» for perfection of structure of motive actions of sportsmen, specialized in high jumps. The introduction of a vast arsenal of technical tools in practice the training process open new prospects associated with increased efficiency in the preparation of athletes.

  18. Biomechanics of the Gastrointestinal Tract in Health and Disease

    DEFF Research Database (Denmark)

    Zhao, Jingbo; Liao, Donghua; Gregersen, Hans

    2010-01-01

    The gastrointestinal (GI) tract is functionally subjected to dimensional changes. Hence, biomechanical properties such as the stress-strain relationships are of particularly importance. These properties vary along the normal GI tract and remodel in response to growth, aging and disease. The biome......The gastrointestinal (GI) tract is functionally subjected to dimensional changes. Hence, biomechanical properties such as the stress-strain relationships are of particularly importance. These properties vary along the normal GI tract and remodel in response to growth, aging and disease...

  19. Do Cells Contribute to Tendon and Ligament Biomechanics?

    Science.gov (United States)

    Hammer, Niels; Huster, Daniel; Fritsch, Sebastian; Hädrich, Carsten; Koch, Holger; Schmidt, Peter; Sichting, Freddy; Wagner, Martin Franz-Xaver; Boldt, Andreas

    2014-01-01

    Introduction Acellular scaffolds are increasingly used for the surgical repair of tendon injury and ligament tears. Despite this increased use, very little data exist directly comparing acellular scaffolds and their native counterparts. Such a comparison would help establish the effectiveness of the acellularization procedure of human tissues. Furthermore, such a comparison would help estimate the influence of cells in ligament and tendon stability and give insight into the effects of acellularization on collagen. Material and Methods Eighteen human iliotibial tract samples were obtained from nine body donors. Nine samples were acellularized with sodium dodecyl sulphate (SDS), while nine counterparts from the same donors remained in the native condition. The ends of all samples were plastinated to minimize material slippage. Their water content was adjusted to 69%, using the osmotic stress technique to exclude water content-related alterations of the mechanical properties. Uniaxial tensile testing was performed to obtain the elastic modulus, ultimate stress and maximum strain. The effectiveness of the acellularization procedure was histologically verified by means of a DNA assay. Results The histology samples showed a complete removal of the cells, an extensive, yet incomplete removal of the DNA content and alterations to the extracellular collagen. Tensile properties of the tract samples such as elastic modulus and ultimate stress were unaffected by acellularization with the exception of maximum strain. Discussion The data indicate that cells influence the mechanical properties of ligaments and tendons in vitro to a negligible extent. Moreover, acellularization with SDS alters material properties to a minor extent, indicating that this method provides a biomechanical match in ligament and tendon reconstruction. However, the given protocol insufficiently removes DNA. This may increase the potential for transplant rejection when acellular tract scaffolds are used in

  20. Do cells contribute to tendon and ligament biomechanics?

    Directory of Open Access Journals (Sweden)

    Niels Hammer

    Full Text Available Acellular scaffolds are increasingly used for the surgical repair of tendon injury and ligament tears. Despite this increased use, very little data exist directly comparing acellular scaffolds and their native counterparts. Such a comparison would help establish the effectiveness of the acellularization procedure of human tissues. Furthermore, such a comparison would help estimate the influence of cells in ligament and tendon stability and give insight into the effects of acellularization on collagen.Eighteen human iliotibial tract samples were obtained from nine body donors. Nine samples were acellularized with sodium dodecyl sulphate (SDS, while nine counterparts from the same donors remained in the native condition. The ends of all samples were plastinated to minimize material slippage. Their water content was adjusted to 69%, using the osmotic stress technique to exclude water content-related alterations of the mechanical properties. Uniaxial tensile testing was performed to obtain the elastic modulus, ultimate stress and maximum strain. The effectiveness of the acellularization procedure was histologically verified by means of a DNA assay.The histology samples showed a complete removal of the cells, an extensive, yet incomplete removal of the DNA content and alterations to the extracellular collagen. Tensile properties of the tract samples such as elastic modulus and ultimate stress were unaffected by acellularization with the exception of maximum strain.The data indicate that cells influence the mechanical properties of ligaments and tendons in vitro to a negligible extent. Moreover, acellularization with SDS alters material properties to a minor extent, indicating that this method provides a biomechanical match in ligament and tendon reconstruction. However, the given protocol insufficiently removes DNA. This may increase the potential for transplant rejection when acellular tract scaffolds are used in soft tissue repair. Further research