MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Computer Methods in Biomechanics and Biomedical Engineering' source. Sun, 21 Mar 2010 17:31:37 +0100 http://www.medworm.com/index.php?rid=3374540&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20229379%26dopt%3DAbstract In this study, the mechanobiological principles were implemented on a 3D finite element (FE) model of the proximal femur in order to predict changes in morphology over time in healthy and CP children. This model relies on the assumption that cyclic octahedral shear stress promotes growth and cyclic hydrostatic compressive stress inhibits growth. Growth was simulated over 16 iterations, representing approximately 5 months of growth. The FE model predicts an increase in the femoral anteversion and coxa valga for CP loading conditions when compared with healthy ones. Understanding the role of loading in skeletal morphogenesis may help prevent bone deformities and improve function in children with gait abnormalities. PMID: 20229379 [PubMed - as supplied by publisher] (Source: Computer Meth... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3374540 Fri, 12 Mar 2010 00:00:00 +0100 3374540 http://www.medworm.com/index.php?rid=3362827&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20221934%26dopt%3DAbstract Authors: Xu H, Hu JJ, Humphrey JD, Liu JC Structural features of elastic laminae within arteries can provide vital information for both the mechanobiology and the biomechanics of the wall. In this paper, we propose, test and illustrate a new computer-based scheme for automated analysis of regional distributions of elastic laminae thickness, inter-lamellar distances and fragmentation furcation points (FPs) from standard histological images. Our scheme eliminates potential artefacts produced by tissue cutting, automatically aligns tissue according to physiologic orientations and performs cross-sectional measurements along radial directions. A statistical randomised complete block design and F test were used to assess the potential (non)-uniformity of lamellar thicknesses and separations ... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3362827 Tue, 09 Mar 2010 00:00:00 +0100 3362827 http://www.medworm.com/index.php?rid=3337250&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20204910%26dopt%3DAbstract Authors: Peck CC, Wirianski A, Murray GM The human jaw's structure-function relationships are complex. A recent example of this complexity is the lateral pterygoid muscle which we now consider as a single unit made up of functional regions with activity in each dependent on the biomechanical demands of the task. We have also characterised the effects on the jaw motor system of pain or exercise, as examples of how the jaw motor system adapts. Synchronised jaw tracking and electromyographic acquisition systems were used to study the effects on jaw muscle activity of experimentally induced masseter muscle pain or resistance exercises during goal-directed tasks. With both interventions, subjects were able to perform the same movement with different muscle co-activation strategies. In futur... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3337250 Wed, 03 Mar 2010 00:00:00 +0100 3337250 http://www.medworm.com/index.php?rid=3337249&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20204911%26dopt%3DAbstract Authors: Farhat N, Mata V, Rosa D, Fayos J Knee injuries, especially those that affect the cruciate and lateral ligaments, are one of the most serious and frequent pathologies that affect the lower human extremity. Hence, the aim of this study is to develop a dynamic model for the lower extremity capable of estimating forces, forces in the cruciate and collateral ligaments and those normal to the articular cartilage, generated in the knee. The proposed model considers a four-bar mechanism in the knee, a spherical joint in the pelvis and a revolute one in the ankle. The four-bar mechanism is obtained by a synthesis process. The dynamic model includes the inertial properties of the femur, tibia, patella and the foot, the ground reaction force and the most important muscles in the knee. M... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3337249 Wed, 03 Mar 2010 00:00:00 +0100 3337249 http://www.medworm.com/index.php?rid=3285967&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20162473%26dopt%3DAbstract The objective of the current study was to benchmark models from three platforms (two FE and one MBD) using various probabilistic methods by predicting the influence of alignment variability and experimental parameters on TKR mechanics in simulated gait. Predicted kinematics envelopes were on average about 2.6 mm for tibial anterior-posterior translation, 2.9 degrees for tibial internal-external rotation and 1.9 MPa for tibial peak contact pressure for the various platforms and methods. Based on this good agreement with the MCST, the efficient probabilistic techniques may prove useful in the fast evaluation of new implant designs, including considerations of uncertainty, e.g. misalignment. PMID: 20162473 [PubMed - as supplied by publisher] (Source: Computer Methods in Biomechanics and B... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3285967 Mon, 15 Feb 2010 00:00:00 +0100 3285967 http://www.medworm.com/index.php?rid=3285966&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20162474%26dopt%3DAbstract Authors: Domire ZJ, Challis JH The maximum velocity of shortening of a muscle is an important parameter in musculoskeletal models. The most commonly used values are derived from animal studies; however, these values are well above the values that have been reported for human muscle. The purpose of this study was to examine the sensitivity of simulations of maximum vertical jumping performance to the parameters describing the force-velocity properties of muscle. Simulations performed with parameters derived from animal studies were similar to measured jump heights from previous experimental studies. While simulations performed with parameters derived from human muscle were much lower than previously measured jump heights. If current measurements of maximum shortening velocity in human m... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3285966 Mon, 15 Feb 2010 00:00:00 +0100 3285966 http://www.medworm.com/index.php?rid=3285965&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20162475%26dopt%3DAbstract Authors: Masson C, Baque P, Brunet C Mechanical properties of human pelvic bone tissue according morphological parameters were few studied in anterior-posterior compression tests and few data are available to correctly validate finite element pelvis models. In order to reduce this gap, 12 pelvic bones were removed from male and female embalmed cadavers and compressed. Anatomic angles were measured and bone's density was calculated after each test. Fractures observed during those tests were coherent with those observed in real life. Bone's density and percentage of mineralisation were not significantly different between the male and female groups. The retropubic angle was significantly larger in the female group (p < 0.05). Mean load necessary to obtain the collapse was significantly... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3285965 Mon, 15 Feb 2010 00:00:00 +0100 3285965 http://www.medworm.com/index.php?rid=3280269&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20155531%26dopt%3DAbstract In this study, high-resolution magnetic resonance imaging was performed in the transaxial, coronal and sagittal planes to provide comprehensive structural details of the bladder and surrounding systems. Detailed finite-element (FE) models that were specific to each participant were developed by rendering the images, and the process of bladder filling was simulated. The overall model of bladder deformation was compared with repeated images of the filled bladder that were obtained using computed tomography to validate the FE models. The relationship between the changes in the key dimensions of the bladder and the increase in bladder volume during the filling process was also investigated. The numerical results showed that the bladder dimensions increased linearly with its volume during the f... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3280269 Fri, 12 Feb 2010 00:00:00 +0100 3280269 http://www.medworm.com/index.php?rid=3263322&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20146128%26dopt%3DAbstract Authors: Bani Amer M This paper presents an adaptive neurofuzzy-based method for the determination of blood acidity (pH). The main advantage of this method in comparison with conventional ones used for blood pH measurements is that it is capable of estimating the blood pH without the need for a pH sensor, which in turn reduces the volume of blood sample required to conduct the chemical analysis. This method uses blood carbon dioxide partial pressure (pCO(2)) and bicarbonate ([image omitted] ) as input to a neurofuzzy approach to predict the value of blood pH. This method was validated using 60 test data points that had not been used during the training process. The obtained results showed that the pH values predicted using this method have good concordance with experimentally measured ... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3263322 Mon, 08 Feb 2010 00:00:00 +0100 3263322 http://www.medworm.com/index.php?rid=3263321&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20146129%26dopt%3DAbstract Authors: Cobos S, Ferre M, Angel Sanchez-Uran M, Ortego J, Aracil R This work focuses on obtaining realistic human hand models that are suitable for manipulation tasks. A 24 degrees of freedom (DoF) kinematic model of the human hand is defined. The model reasonably satisfies realism requirements in simulation and movement. To achieve realism, intra- and inter-finger constraints are obtained. The design of the hand model with 24 DoF is based upon a morphological, physiological and anatomical study of the human hand. The model is used to develop a gesture recognition procedure that uses principal components analysis (PCA) and discriminant functions. Two simplified hand descriptions (nine and six DoF) have been developed in accordance with the constraints obtained previously. The accuracy... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3263321 Mon, 08 Feb 2010 00:00:00 +0100 3263321 http://www.medworm.com/index.php?rid=3263320&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20146130%26dopt%3DAbstract Authors: Binderup AT, Arendt-Nielsen L, Madeleine P The aim of this study was to investigate and present a new mapping method to describe muscle pain sensitivity based on the assessment of pressure pain threshold (PPT) over the trapezius muscle. PPT data were recorded from 36 points in 20 healthy males using a standardised grid. Points were clustered using the K-means algorithm with a fixed initialisation procedure. The total number of clusters was determined on the basis of (1) R(2) evaluation of the clustering outcome compared against a desired 95% reduction in variance criterion and (2) the number of empty clusters. A minimum of three clusters were found which fulfilled the criteria. The proposed method enables the identification of a relation between the muscle subdivisions and pre... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3263320 Mon, 08 Feb 2010 00:00:00 +0100 3263320 http://www.medworm.com/index.php?rid=3263319&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20146131%26dopt%3DAbstract Authors: Martins P, Pena E, Calvo B, Doblare M, Mascarenhas T, Jorge RN, Ferreira A The mechanical properties of the vaginal tissue need to be characterised to perform accurate simulations of prolapse and other pelvic disorders that commonly affect women. This is also a fundamental step towards the improvement of therapeutic techniques such as surgery. Issues like the efficiency of using autologous tissue in pelvic reconstruction may be addressed. The goal of this study was to characterise the elastic behaviour of vaginal tissue. For this purpose, prolapsed vaginal tissue from eight different post-menopausal patients, excised during prolapse corrective surgery, was mechanically tested. The mechanical testing of vaginal tissue, consisting of uniaxial tension tests performed along the lo... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3263319 Mon, 08 Feb 2010 00:00:00 +0100 3263319 http://www.medworm.com/index.php?rid=3255425&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20140798%26dopt%3DAbstract We present herein an approach for prescribing lumped parameter outflow boundary conditions that accommodate transient phenomena. We have applied this method to compute haemodynamic quantities in different physiologically relevant cardiovascular models, including patient-specific examples, to study non-periodic flow phenomena often observed in normal subjects and in patients with acquired or congenital cardiovascular disease. The relevance of using boundary conditions that accommodate transient phenomena compared with boundary conditions that assume periodicity of the solution is discussed. PMID: 20140798 [PubMed - as supplied by publisher] (Source: Computer Methods in Biomechanics and Biomedical Engineering) Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3255425 Thu, 04 Feb 2010 00:00:00 +0100 3255425 http://www.medworm.com/index.php?rid=3213228&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20099169%26dopt%3DAbstract Authors: Rao GV, Rubod C, Brieu M, Bhatnagar N, Cosson M Pelvic prolapse affects one woman in three of all ages combined and is quite common for more than 60% of patients over 60 years of age. The treatment of this pathological problem is one of the biggest challenges to the gynaecologist today. The rate of surgical intervention failure is quite significant. The recurrence of prolapse could be related to inadequate surgical technique or the pathology or/and biomechanical deficiency of the soft tissues. The modelling and simulation of the behaviour of the pelvic cavity could be a major tool for specific evaluation of pelvic status. A first stage of this model is being developed and reported. The computer-aided design model of the organs of the pelvic floor is created using magnetic reso... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3213228 Fri, 22 Jan 2010 00:00:00 +0100 3213228 http://www.medworm.com/index.php?rid=3201200&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20094931%26dopt%3DAbstract Authors: Morrow DA, Haut Donahue T, Odegard GM, Kaufman KR Higher-order polynomial functions can be used as a constitutive model to represent the mechanical behaviour of biological materials. The goal of this study was to present a method for assessing the fit of a given constitutive three-dimensional material model. Goodness of fit was assessed using multiple parameters including the root mean square error and Hotelling's T(2)-test. Specifically, a polynomial model was used to characterise the stress-strain data, varying the number of model terms used (45 combinations of between 3 and 11 terms) and the manner of optimisation used to establish model coefficients (i.e. determining coefficients either by parameterisation of all data simultaneously or averaging coefficients obtained by pa... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3201200 Wed, 20 Jan 2010 00:00:00 +0100 3201200 http://www.medworm.com/index.php?rid=3179278&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20077238%26dopt%3DAbstract Authors: Fang G, Ji B, Liu XS, Guo XE Trabecular bone microdamage significantly influences the skeletal integrity and bone remodelling process. In this paper a novel constitutive model, called the virtual internal bond model (VIB), was adopted for simulating the damage behaviour of bone tissue. A unique 3D image analysis technique, named individual trabeculae segmentation, was used to analyse the effects of microarchitectures on the damage behaviours of trabecular bone. We demonstrated that the process of initiation and accumulation of microdamage in trabecular bone samples can be captured by the VIB-embedded finite-element method simulation without a separate fracture criterion. Our simulation results showed that the microdamage can occur at as early as about 0.2-0.4% apparent strain,... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3179278 Thu, 14 Jan 2010 00:00:00 +0100 3179278 http://www.medworm.com/index.php?rid=3179277&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20077239%26dopt%3DAbstract Authors: Wang S, Yang J In cranio-maxillofacial surgical simulation, many difficulties occur in building a realistic biomechanical model of soft tissue deformation, e.g. constitutive properties of the living tissues, geometry description, and kinematics of the facial soft tissues. This paper presents a nonlinear finite mixed-element model (NFM-EM) to enhance the tissue behaviour in the simulation. A novel geometric description method based on the mixed elements is first designed to allow the skin and the internal tissues (muscles and fat) to be discretised with different volumetric elements and assigned unique material properties. Moreover, it provides C(1)-continuity at the facial surface and leaves C(0)-continuity in the interior elements. In addition, this approach employs the Lagra... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3179277 Thu, 14 Jan 2010 00:00:00 +0100 3179277 http://www.medworm.com/index.php?rid=3179276&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20077240%26dopt%3DAbstract In this study, we use the cross-impact analysis to build a descriptively quantitative relationship between mutant adrenoleukodystrophy protein and classification of adrenoleukodystrophy with the amino-acid distribution probability, which is a quantitative measure sensitive to mutation. Then we determine the probability that the adrenoleukodystrophy can be classified under mutations with the help of a Bayesian equation. PMID: 20077240 [PubMed - as supplied by publisher] (Source: Computer Methods in Biomechanics and Biomedical Engineering) Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3179276 Thu, 14 Jan 2010 00:00:00 +0100 3179276 http://www.medworm.com/index.php?rid=3034145&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19937492%26dopt%3DAbstract Authors: Zander T, Krishnakanth P, Bergmann G, Rohlmann A Diurnal changes of intervertebral disc height are caused by high compressive loading during the day, which expulses fluid from the disc, and by osmotic pressure, which imbibes fluid into the disc at low loading. The aim of the present study was to determine the magnitude of diurnal changes in spine flexibility, intradiscal pressures and contact forces in the facet joints. A validated osseoligamentous finite element model of the lumbar spine was used to determine these quantities for morning and evening situations. Disc height varied by 10% for these two situations. Spine flexibility and facet joint forces were markedly higher in the evening than in the morning. Intradiscal pressures were higher in the morning than in the evening... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3034145 Thu, 19 Nov 2009 00:00:00 +0100 3034145 http://www.medworm.com/index.php?rid=3015891&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19927241%26dopt%3DAbstract In conclusion, the material factor did not significantly alter the stress magnitude, but volume was the key factor in reducing the stress shielding effect. PMID: 19927241 [PubMed - as supplied by publisher] (Source: Computer Methods in Biomechanics and Biomedical Engineering) Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3015891 Wed, 18 Nov 2009 00:00:00 +0100 3015891 http://www.medworm.com/index.php?rid=3015890&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19927242%26dopt%3DAbstract Authors: Vaziri A, Nayeb-Hashemi H, Akhavan-Tafti B A 3D finite element model of rib cage movement is developed and used to study the role of age-related costal cartilage and sternocostal joint calcification, as well as respiratory muscle weakness on the 'bucket-handle' movement of human rib. The volume displacement of the rib cage is related to changes in its circumference using an empirical equation presented by Agostoni et al. (1965, J Appl Physiol, 20:1179-1186). A systematic study is carried out to quantify the role of costal cartilage, sternocostal joint calcification and muscle weakness on the volume displacement of the rib cage. The results provide insight into some of the mechanisms underlying age-related changes in the respiratory system. PMID: 19927242 [PubMed - as suppl... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3015890 Wed, 18 Nov 2009 00:00:00 +0100 3015890 http://www.medworm.com/index.php?rid=3015889&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19927243%26dopt%3DAbstract Authors: Davidson PL, Wilson SJ, Wilson BD, Chalmers DJ The mechanical interactions during impact of a falling human body onto a non-rigid surface are complex. Mechanical properties of both the impacting body and the impacted surface contribute to risk of injury. Increased understanding of these properties should provide insight into the process and how to reduce injury risk. We assessed whether modelling energy flows in the body during impact can provide useful information. As input, we used data from gymnastic tumbling mats and from children performing an exercise involving freefall onto an outstretched arm. Even basic energy transfer principles provided information not discerned by the mechanical approach traditionally used. The model identified differences between surfaces in how e... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3015889 Wed, 18 Nov 2009 00:00:00 +0100 3015889 http://www.medworm.com/index.php?rid=3015888&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19927244%26dopt%3DAbstract Authors: Liao W, Chen H, Pan Z Functional magnetic resonance imaging (fMRI) data-processing methods in the time domain include correlation analysis and the general linear model, among others. Virtually, many fMRI processing strategies utilise temporal information and ignore or pay little attention to phase information, resulting in an unnecessary loss of efficiency. We proposed a novel method named Hilbert phase entropy imaging (HPEI) that used the discrete Hilbert transform of the magnitude time series to detect brain functional activation. The data from two simulation studies and two in vivo fMRI studies that both contained block-design and event-related experiments revealed that the HPEI method enabled the effective detection of brain functional activation and the distinction of dif... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3015888 Wed, 18 Nov 2009 00:00:00 +0100 3015888 http://www.medworm.com/index.php?rid=3015887&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19927245%26dopt%3DAbstract Conclusions: IABP can be described by a theoretical model. Our model representing the cardiovascular system is capable of showing the effects of different pathologies such as MI and we have shown that MI effects can be reduced using IABP in accordance with the modelling results. The mathematical model should serve as a useful tool to simulate and better understand cardiovascular operation in normal and pathological conditions. PMID: 19927245 [PubMed - as supplied by publisher] (Source: Computer Methods in Biomechanics and Biomedical Engineering) Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3015887 Wed, 18 Nov 2009 00:00:00 +0100 3015887 http://www.medworm.com/index.php?rid=2920632&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19844816%26dopt%3DAbstract Authors: Azevedo TC, Tavares JM, Vaz MA This work presents a volumetric approach to reconstruct and characterise 3D models of external anatomical structures from 2D images. Volumetric methods represent the final volume using a finite set of 3D geometric primitives, usually designed as voxels. Thus, from an image sequence acquired around the object to reconstruct, the images are calibrated and the 3D models of the referred object are built using different approaches of volumetric methods. The final goal is to analyse the accuracy of the obtained models when modifying some of the parameters of the considered volumetric methods, such as the type of voxel projection (rectangular or accurate), the way the consistency of the voxels is tested (only silhouettes or silhouettes and photo-consist... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920632 Mon, 19 Oct 2009 23:00:00 +0100 2920632 http://www.medworm.com/index.php?rid=2920631&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19844817%26dopt%3DAbstract Authors: Ciocca L, De Crescenzio F, Fantini M, Scotti R Ear defects in patients affected by Treacher Collins syndrome necessitate the replacement of the existing anatomic residuals of the ears with custom-made prostheses. This paper describes a multidisciplinary protocol involving both medicine and computer-aided design/computer-aided manufacturing for manufacturing ear prostheses. Using innovative prototyping technologies together with conventional silicone processing procedures, a step-by-step procedure is presented. The complete workflow includes laser scanning of the defective regions of a patient's face, the use of 3D anatomic models from an ear digital library and rapid prototyping of both substructures for bar anchoring and moulds for silicone processing. PMID: 19844817 [Pub... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920631 Mon, 19 Oct 2009 23:00:00 +0100 2920631 http://www.medworm.com/index.php?rid=2879886&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19816835%26dopt%3DAbstract This article describes the merits and demerits of various stent designs and details the specific reasons why a particular novel design is expected to be the most suitable implant during and after percutaneous aortic valve replacement. PMID: 19816835 [PubMed - as supplied by publisher] (Source: Computer Methods in Biomechanics and Biomedical Engineering) Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2879886 Wed, 07 Oct 2009 23:00:00 +0100 2879886 http://www.medworm.com/index.php?rid=2866161&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19802754%26dopt%3DAbstract Authors: Cerveri P, De Momi E, Marchente M, Baud-Bovy G, Scifo P, Barros RM, Ferrigno G In this paper, we propose a method to estimate the parameters of a double hinge model of the trapeziometacarpal joint (TMC) by MRI-based motion analysis. The model includes two non-orthogonal and non-intersecting rotation axes accounting for flexion-extension (F-E) and adduction-abduction (A-A). We evaluated the quality of the estimated model parameters in the prediction of the relative motion of the first metacarpal bone with respect to the trapezium. As a result, we obtained that: (a) the estimated location and orientation of the F-E and A-A axes were in agreement with previous in vitro studies, (b) the motion of the first metacarpal predicted by the 2 degrees of freedom (2DoF) model exhibits a ma... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2866161 Thu, 01 Oct 2009 23:00:00 +0100 2866161 http://www.medworm.com/index.php?rid=2866160&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19802755%26dopt%3DAbstract Authors: Senk M, Cheze L Optoelectronic tracking systems are rarely used in 3D studies examining shoulder movements including the scapula. Among the reasons is the important slippage of skin markers with respect to scapula. Methods using electromagnetic tracking devices are validated and frequently applied. Thus, the aim of this study was to develop a new method for in vivo optoelectronic scapular capture dealing with the accepted accuracy issues of validated methods. Eleven arm positions in three anatomical planes were examined using five subjects in static mode. The method was based on local optimisation, and recalculation procedures were made using a set of five scapular surface markers. The scapular rotations derived from the recalculation-based method yielded RMS errors comparable... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2866160 Thu, 01 Oct 2009 23:00:00 +0100 2866160 http://www.medworm.com/index.php?rid=2847431&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19787497%26dopt%3DAbstract Authors: Pal B, Gupta S, New AM Ceramic hip resurfacing may offer improved wear resistance compared to metallic components. The study is aimed at investigating the effects of stiffer ceramic components on the stress/strain-related failure mechanisms in the resurfaced femur, using three-dimensional finite element models of intact and resurfaced femurs with varying stem-bone interface conditions. Tensile stresses in the cement varied between 1 and 5 MPa. Postoperatively, 20-85% strain shielding was observed inside the resurfaced head. The variability in stem-bone interface condition strongly influenced the stresses and strains generated within the resurfaced femoral head. For full stem-bone contact, high tensile (151-158 MPa) stresses were generated at the cup-stem junction, indicating r... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2847431 Wed, 23 Sep 2009 23:00:00 +0100 2847431 http://www.medworm.com/index.php?rid=2847430&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19787498%26dopt%3DAbstract Authors: Huang R, Pan J The degradation of medical devices made of bioresorbable polymers such as fixation devices in orthopaedic surgeries and scaffolds for tissue engineering can take from months to years. The trial and error approach of device development is therefore problematic and mathematical modelling of the biodegradation can help to accelerate the device development. This paper presents an inverse scheme to obtain the material parameters in a biodegradation model developed by Pan and his co-workers from existing experimental data of bioresorbable devices. The parameters can then be used to predict the degradation rate of new devices made of the same polymer. Firstly, the previously developed model is briefly outlined. Secondly, a finite element scheme and a time integration a... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2847430 Sun, 20 Sep 2009 23:00:00 +0100 2847430 http://www.medworm.com/index.php?rid=2725450&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19697181%26dopt%3DAbstract Authors: Ghaffari A, Homaeinezhad MR, Atarod M, Akraminia M The aim of this study is to detect acute hypotensive episodes (AHE) and mean arterial pressure dropping regimes (MAPDRs) using electrocardiographic (ECG) signals and arterial blood pressure waveforms. To meet this end, the QRS complexes and end-systolic end-diastolic pulses are first extracted using two innovative modified Hilbert transform-based algorithms, namely ECGMHT and BPMHT. The resulting systolic and diastolic blood pressure pulses are then used to calculate the MAP trend. A new smoothing algorithm is developed, next based on piecewise polynomial fitting (PPF) to smooth the fast fluctuations observed in RR-tachogram and MAP trends. PPF algorithm operates by sequentially fitting N number of polynomials to the original ... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2725450 Wed, 19 Aug 2009 23:00:00 +0100 2725450 http://www.medworm.com/index.php?rid=2725449&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19697182%26dopt%3DAbstract Authors: Perez MA, Fornells P, Doblare M, Garcia-Aznar JM Subject-specific finite element models are an extensively used tool for the numerical analysis of the biomechanical behaviour of human bones. However, bone modelling is not an easy task due to the complex behaviour of bone tissue, involving non-homogeneous and anisotropic mechanical properties. Moreover, bone is a living tissue and therefore its microstructure and mechanical properties evolve with time in a known process called bone remodelling. This phenomenon has been widely studied, many being the numerical models that have been formulated to predict density distribution and its evolution in several bones. The aim of the present study is to assess the capability of a bone remodelling model to predict the bone density distribu... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2725449 Wed, 19 Aug 2009 23:00:00 +0100 2725449 http://www.medworm.com/index.php?rid=2721008&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19693717%26dopt%3DAbstract Authors: Andersen MS, Damsgaard M, Macwilliams B, Rasmussen J This paper introduces a general optimisation-based method for identification of biomechanically relevant parameters in kinematically determinate and over-determinate systems from a given motion. The method is designed to find a set of parameters that is constant over the time frame of interest as well as the time-varying system coordinates, and it is particularly relevant for biomechanical motion analysis where the system parameters can be difficult to accurately determine by direct measurements. Although the parameter identification problem results in a large-scale optimisation problem, we show that, due to a special structure in the linearised Karush-Kuhn-Tucker optimality conditions, the solution can be found very efficie... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2721008 Tue, 18 Aug 2009 23:00:00 +0100 2721008 http://www.medworm.com/index.php?rid=2682611&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19657797%26dopt%3DAbstract Authors: Molla MM, Paul MC, Roditi G Transition of additive and non-additive pulsatile flows through a simple 3D model of arterial stenosis is investigated by using a large eddy simulation (LES) technique. We find in both the pulsatile cases that the interaction of the two shear layers, one of which separates from the nose of the stenosis and the another one from its opposite wall, causes recirculation in the flow downstream of the stenosis where the nature of the transient flow becomes turbulent. The strength of this recirculation is found to be quite high from the non-additive pulsations when the flow Reynolds numbers, [image omitted] , for which both the pressure and shearing stresses take on an oscillating form at the post-stenotic region. Potential medical consequences of these re... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2682611 Mon, 03 Aug 2009 23:00:00 +0100 2682611 http://www.medworm.com/index.php?rid=2682610&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19657798%26dopt%3DAbstract In this study, a new approach is presented, in which landmarks are calculated after selection of the landmark region on a triangular model and in which the skull is automatically orientated in a standardised way. Two examiners each performed five analyses on three skull models. Landmark reproducibility was tested by calculating the standard deviation for each observer and the difference between the mean values of both observers. The variation can be limited to 0.1 mm for most landmarks. However, some landmarks perform less well and require further investigation. With the proposed reference system, a symmetrical orientation of the skulls is obtained. The presented methods contribute to standardisation in cephalometry and could therefore allow improved comparison of patient data. PMID: 1... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2682610 Mon, 03 Aug 2009 23:00:00 +0100 2682610 http://www.medworm.com/index.php?rid=2682609&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19657799%26dopt%3DAbstract Authors: Provatidis C, Vossou C, Koukoulis I, Balanika A, Baltas C, Lyritis G In this paper, two patient-specific finite element (FE) models of both an L1 vertebra with a normal T-score and a mildly wedging, osteoporotic one were created and analysed under usual action. Utilising commercial software packages for image processing and FE analysis (FEA) along with in house computer codes for a posteriori assignment of material properties, in vivo high-resolution spiral computed tomography of the entire vertebrae and FEA were combined. Using the vertebra with a normal T-score as baseline it was found that the maximum value of the von Mises stress in the osteoporotic vertebra was 60% higher but still far below bone strength, while the maximum value of von Mises strain in the same vertebra w... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2682609 Mon, 03 Aug 2009 23:00:00 +0100 2682609 http://www.medworm.com/index.php?rid=2682608&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19657800%26dopt%3DAbstract Authors: Park B, Han K Many methods developed for estimating the reliability of protein-protein interactions are based on the topology of protein-protein interaction networks. This paper describes a new reliability measure for protein-protein interactions, which does not rely on the topology of protein interaction networks, but expresses biological information on functional roles, sub-cellular localisations and protein classes as a scoring schema. The new measure is useful for filtering many spurious interactions, as well as for estimating the reliability of protein interaction data. In particular, the reliability measure can be used to search protein-protein interactions with the desired reliability in databases. The reliability-based search engine is available at http://yeast.hpid.or... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2682608 Mon, 03 Aug 2009 23:00:00 +0100 2682608 http://www.medworm.com/index.php?rid=2682607&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19657801%26dopt%3DAbstract Authors: Ma Z, Tavares JM, Jorge RN, Mascarenhas T This paper aims to make a review on the current segmentation algorithms used for medical images. Algorithms are classified according to their principal methodologies, namely the ones based on thresholds, the ones based on clustering techniques and the ones based on deformable models. The last type is focused on due to the intensive investigations into the deformable models that have been done in the last few decades. Typical algorithms of each type are discussed and the main ideas, application fields, advantages and disadvantages of each type are summarised. Experiments that apply these algorithms to segment the organs and tissues of the female pelvic cavity are presented to further illustrate their distinct characteristics. In the end... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2682607 Mon, 03 Aug 2009 23:00:00 +0100 2682607 http://www.medworm.com/index.php?rid=2682606&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19657802%26dopt%3DAbstract Authors: Koch TM, Reddy BD, Zilla P, Franz T This work was concerned with the numerical simulation of the behaviour of aortic valves whose material can be modelled as non-linear elastic anisotropic. Linear elastic models for the valve leaflets with parameters used in previous studies were compared with hyperelastic models, incorporating leaflet anisotropy with pronounced stiffness in the circumferential direction through a transverse isotropic model. The parameters for the hyperelastic models were obtained from fits to results of orthogonal uniaxial tensile tests on porcine aortic valve leaflets. The computational results indicated the significant impact of transverse isotropy and hyperelastic effects on leaflet mechanics; in particular, increased coaptation with peak values of stress ... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2682606 Mon, 03 Aug 2009 23:00:00 +0100 2682606 http://www.medworm.com/index.php?rid=2654446&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19639485%26dopt%3DAbstract Authors: Schmid H, Wang W, Hunter PJ, Nash MP A previous study investigated a number of invariant-based orthotropic and transversely isotropic constitutive equations for their suitability to fit three-dimensional simple shear mechanics data of passive myocardial tissue. The study was based on the assumption of a homogeneous deformation. Here, we extend the previous study by performing an inverse finite element material parameter estimation. This ensures a more realistic deformation state and material parameter estimates. The constitutive relations were compared on the basis of (i) 'goodness of fit': how well they fit a set of six shear deformation tests and (ii) 'variability': how well determined the material parameters are over the range of experiments. These criteria were utilised to... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2654446 Mon, 27 Jul 2009 23:00:00 +0100 2654446 http://www.medworm.com/index.php?rid=2654445&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19639486%26dopt%3DAbstract Authors: Johnston PR This paper presents an implementation of the finite volume method with the aim of studying subendocardial ischaemia during the ST segment. In this implementation, based on hexahedral finite volumes, each quadrilateral sub-face is split into two triangles to improve the accuracy of the numerical integration in complex geometries and when fibre rotation is included. The numerical method is validated against previously published solutions obtained from slab and cylindrical models of the left ventricle with subendocardial ischaemia and no fibre rotation. Epicardial potential distributions are then obtained for a half-ellipsoid model of the left ventricle. In this case it is shown that for isotropic cardiac tissue the degree of subendocardial ischaemia does not affect t... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2654445 Mon, 27 Jul 2009 23:00:00 +0100 2654445 http://www.medworm.com/index.php?rid=2654444&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19639487%26dopt%3DAbstract This article proposes a new vision of the permeability based on a concept of multi-scale medium corresponding to the scales already introduced in the SiNuPrOs model which has been developed for cortical bone. According to this model, several architectural levels are proposed and a mathematical development based on the homogenisation theory, which can be applied to each of these levels, allows a numerical computation of the permeability tensor coefficients. A comparative analysis of our simulations and some experimental results (already published) shows a good accordance with the literature. PMID: 19639487 [PubMed - as supplied by publisher] (Source: Computer Methods in Biomechanics and Biomedical Engineering) Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2654444 Mon, 27 Jul 2009 23:00:00 +0100 2654444 http://www.medworm.com/index.php?rid=2654443&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19639488%26dopt%3DAbstract Authors: Delfour MC, Garon A The notion of dose that comes from the biologists has been introduced by Delfour et al. (2005 SIAM J. Appl. Math. 65(3):858-881) in the context of coated stents to control restenosis. Assuming a stationary velocity profile of the blood flow in the lumen, it leads to a time-independent equation for the dose that considerably simplifies the analysis and the design problem. Under stable conditions the blood flow is pulsative, that is the velocity field can be assumed to be periodic. So it is necessary to justify the replacement of the periodic field by its time average over the pulsation period. In this paper, firstly we introduce the new unfolded dose and its equations without a priori constraint on the size of the period. So it can be used in biochemical pro... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2654443 Mon, 27 Jul 2009 23:00:00 +0100 2654443 http://www.medworm.com/index.php?rid=2611767&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19603305%26dopt%3DAbstract Authors: Balaguera MI, Briceno JC, Glazier JA An object-oriented modelling framework for the arterial wall is presented. The novelty of the framework is the possibility to generate customisable artery models, taking advantage of imaging technology. In our knowledge, this is the first object-oriented modelling framework for the arterial wall. Existing models do not allow close structural mapping with arterial microstructure as in the object-oriented framework. In the implemented model, passive behaviour of the arterial wall was considered and the tunica adventitia was the objective system. As verification, a model of an arterial segment was generated. In order to simulate its deformation, a matrix structural mechanics simulator was implemented. Two simulations were conducted, one for an... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2611767 Mon, 13 Jul 2009 23:00:00 +0100 2611767 http://www.medworm.com/index.php?rid=2611766&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19603306%26dopt%3DAbstract Authors: Horta-Rangel J, Rivera AL, Castano VM A common cause of human disability is related to the fracture of bones, complex structural materials whose properties vary with time. An analytical study (using ANSYS, a commercial finite element package) of bones under fracture conditions is presented, focusing on the frequency variation versus depth of crack, as well as on the evolution of strength in the fracture area. PMID: 19603306 [PubMed - as supplied by publisher] (Source: Computer Methods in Biomechanics and Biomedical Engineering) Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2611766 Mon, 13 Jul 2009 23:00:00 +0100 2611766 http://www.medworm.com/index.php?rid=2525857&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19360508%26dopt%3DAbstract Authors: Moxnes JF, Hausken K The forces during the kicking phase in Nordic diagonal stride skiing are described by differential equations and the results are compared with experiments. The difference between static and dynamic friction, interacting with characteristics of the skier such as weight, velocity and the kicking force's angle with the terrain, are essential for high-velocity diagonal striding. Analytical results for relationships between glide length, friction and kicking force are shown. Aerodynamic drag and gravity are accounted for. A propulsion force based on the Hill (1970) equation for muscle contraction velocity and activation is constructed. The model shows a feasible tool for studying the effects of ski stiffness, the kicking force and the amount of waxing during di... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2525857 Wed, 17 Jun 2009 23:00:00 +0100 2525857 http://www.medworm.com/index.php?rid=2525840&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19544114%26dopt%3DAbstract Authors: Lempereur M, Brochard S, Burdin V, Remy-Neris O The aim of this study is to determine the errors of scapular localisation due to skin relative to bone motion with an optoelectronic tracking system. We compared three-dimensional (3D) scapular positions obtained with skin markers to those obtained through palpation of three scapular anatomical landmarks. The scapular kinematics of nine subjects were collected. Static positions of the scapula were recorded with the right arm elevated at 0 degrees , 40 degrees , 80 degrees , 120 degrees and 160 degrees in the sagittal plane. Palpation and subsequent digitisation of anatomical landmarks on scapula and thorax were done at the same positions. Scapular 3D orientation was also computed during 10 repeated movements of arm elevation betw... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2525840 Wed, 17 Jun 2009 23:00:00 +0100 2525840 http://www.medworm.com/index.php?rid=2525854&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19396729%26dopt%3DAbstract Authors: Bischoff JE, Drexler ES, Slifka AJ, McCowan CN Determination of material parameters for soft tissue frequently involves regression of material parameters for nonlinear, anisotropic constitutive models against experimental data from heterogeneous tests. Here, parameter estimation based on membrane inflation is considered. A four parameter nonlinear, anisotropic hyperelastic strain energy function was used to model the material, in which the parameters are cast in terms of key response features. The experiment was simulated using finite element (FE) analysis in order to predict the experimental measurements of pressure versus profile strain. Material parameter regression was automated using inverse FE analysis; parameter values were updated by use of both local and global techni... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2525854 Sun, 31 May 2009 23:00:00 +0100 2525854 http://www.medworm.com/index.php?rid=2525844&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19488911%26dopt%3DAbstract Authors: Serres JL, Reynolds DB, Phillips CA, Rogers DB, Repperger DW Pneumatic muscle actuators (PMAs) offer significant advantages over more traditional actuators, which make them prime candidates in rehabilitation devices. A dynamic test station (DTS) is modified to demonstrate the use of a PMA for this application. The DTS includes two dynamic systems: a PMA and a DC servomotor. An overall transfer function was developed utilising characterisation data for the PMA and DC servomotor. A Tustin (bilinear) transform was performed on the overall transfer function to obtain a discrete time system. Model parameters were optimised and used to generate input voltage profiles that achieve isokinetic (constant velocity) task specifications. Percent root mean square error values (PRMSE) betwee... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2525844 Sun, 31 May 2009 23:00:00 +0100 2525844 http://www.medworm.com/index.php?rid=2525842&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19488912%26dopt%3DAbstract Authors: Dopico-Gonzalez C, New AM, Browne M In the present study, a probabilistic finite element tool was implemented to assess an uncemented total hip replacement including variability in bone-implant version angle. The Monte Carlo method was used with two different performance indicators: the bone maximum nodal von-Mises elastic strain and the bone volume (BV) percentage exceeding specified strain limits. Implant version, bone stiffness and load magnitude were the most sensitive parameters. The results were more consistent using percentage BV under specified limit strains as the performance indicator, even for a low number of simulations. The reliability of the computational tool was demonstrated through a comparison with previous studies, and the consistency of the results for all ... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2525842 Sun, 31 May 2009 23:00:00 +0100 2525842 http://www.medworm.com/index.php?rid=2525848&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19418316%26dopt%3DAbstract This study demonstrates conceptually how probabilistic studies might further provide a framework to explore relationships not just within but between multiple different activities, e.g. intra-operative passive laxity drawer loading and post-operative active gait. Two implants were compared using simulated ISO-gait and passive laxity loading, with factors including mal-positioning and soft-tissue constraint varied using Monte-Carlo analysis. The results illustrate that correlations between different activities can be quantified; this demonstration study suggests further research is justified (with detailed clinically representative models) to explore the relationship between passive and active mechanics for specific in vivo conditions. Probabilistics is a key enabling methodology for achiev... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2525848 Tue, 05 May 2009 23:00:00 +0100 2525848 http://www.medworm.com/index.php?rid=2525846&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19418317%26dopt%3DAbstract Authors: Ventura SR, Freitas DR, Tavares JM Speech production has always been a subject of interest both at the morphological and acoustic levels. This knowledge is useful for a better understanding of all the involved mechanisms and for the construction of articulatory models. Magnetic resonance imaging (MRI) is a powerful technique that allows the study of the whole vocal tract, with good soft tissue contrast and resolution, and permits the calculation of area functions towards a better understanding of this mechanism. Thus, our aim is to demonstrate the value and application of MRI in speech production study and its relationship with engineering, namely with biomedical engineering. After vocal tract contours extraction, data were processed for 3D reconstruction culminating in model ... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2525846 Mon, 04 May 2009 23:00:00 +0100 2525846 http://www.medworm.com/index.php?rid=2525850&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19412827%26dopt%3DAbstract Authors: El Ouaaid Z, Arjmand N, Shirazi-Adl A, Parnianpour M A novel optimisation algorithm is developed to predict coactivity of abdominal muscles while accounting for both trunk stability via the lowest buckling load (P(cr)) and tissue loading via the axial compression (F(c)). A nonlinear multi-joint kinematics-driven model of the spine along with the response surface methodology are used to establish empirical expressions for P(cr) and F(c) as functions of abdominal muscle coactivities and external load magnitude during lifting in upright standing posture. A two-component objective function involving F(c) and P(cr) is defined. Due to opposite demands, abdominal coactivities that simultaneously maximise P(cr) and minimise F(c) cannot exist. Optimal solutions are thus identified whil... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2525850 Thu, 30 Apr 2009 23:00:00 +0100 2525850 http://www.medworm.com/index.php?rid=2525853&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19408138%26dopt%3DAbstract Authors: Gonzalez RC, Alvarez D, Lopez AM, Alvarez JC It has been reported that spatio-temporal gait parameters can be estimated using an accelerometer to calculate the vertical displacement of the body's centre of gravity. This method has the potential to produce realistic ambulatory estimations of those parameters during unconstrained walking. In this work, we want to evaluate the crude estimations of mean step length so obtained, for their possible application in the construction of an ambulatory walking distance measurement device. Two methods have been tested with a set of volunteers in 20 m excursions. Experimental results show that estimations of walking distance can be obtained with sufficient accuracy and precision for most practical applications (errors of 3.66 +/- 6.24 and 0... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2525853 Wed, 29 Apr 2009 23:00:00 +0100 2525853 http://www.medworm.com/index.php?rid=2525852&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19408139%26dopt%3DAbstract Authors: Mendez JA, Torres S, Reboso JA, Reboso H This paper presents an efficient computer control technique for regulation of anesthesia in humans. The anesthetic used is propofol and the objective is to control the degree of hypnosis of the patient. The paper describes the basic hardware/software setup of the system and the closed-loop methodologies. The bispectral index (BIS) is considered as the feedback signal. The control methods proposed here are based in the use of proportional integral controllers with dead-time compensation to avoid undesirable oscillations in the BIS signal during the process. The compensation is based on the Smith predictor. To guarantee the applicability of the method to different patients, an adaptive module to tune the compensator is developed. Some rea... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2525852 Wed, 29 Apr 2009 23:00:00 +0100 2525852 http://www.medworm.com/index.php?rid=2525855&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19370459%26dopt%3DAbstract The objectives of this study were to develop an efficient probabilistic representation of knee ligamentous constraint using the advanced mean value (AMV) probabilistic approach, and to compare the AMV representation with the gold standard Monte Carlo (MC) approach. Specifically, the effects of inherent uncertainty in ligament stiffness, reference strain and attachment site locations on joint constraint were assessed. An explicit finite element model of the knee was evaluated under a series of anterior-posterior (AP) and internal-external (IE) loading at full extension and 90 degrees flexion. Distributions of AP and IE laxity were predicted using experimentally-based levels of ligament parameter variability. Importance factors identified the critical properties affecting the predicted bound... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2525855 Tue, 14 Apr 2009 23:00:00 +0100 2525855 http://www.medworm.com/index.php?rid=2525858&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19358056%26dopt%3DAbstract Authors: Rodrigues LB, Lopes DS, Folgado J, Fernandes PR, Pires EB, Las Casas EB, Faleiros RR The response of bovine bone to the presence of an implant is analysed with the aim of simulating bone remodelling in a developing model of a polymeric intramedullary interlocking nail for veterinary use. A 3-D finite element model of the femur diaphysis is built based on computed tomography images and using a CAD-based modelling pipeline. The bone remodelling process after the surgery is analysed and compared with the healthy bone. The remodelling law assumes that bone adapts to the mechanical environment. For the analyses a consistent set of loads is determined for the bovine walk cycle. The remodelling results reproduce the morphologic features of bone and provide evidence of the difference ... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2525858 Wed, 08 Apr 2009 23:00:00 +0100 2525858 http://www.medworm.com/index.php?rid=2525856&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19360509%26dopt%3DAbstract Authors: Zhang G, Kinsner W, Huang B This paper presents an electrocardiogram (ECG) data mining scheme based on the ECG frame classification realised by a dynamic time warping (DTW) matching technique, which has been used successfully in speech recognition. We use the DTW to classify ECG frames because ECG and speech signals have similar non-stationary characteristics. The DTW mapping function is obtained by searching the frame from its end to start. A threshold is setup for DTW matching residual either to classify an ECG frame or to add a new class. Classification and establishment of a template set are carried out simultaneously. A frame is classified into a category with a minimal residual and satisfying a threshold requirement. A classification residual of 1.33% is achieved by the ... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2525856 Wed, 08 Apr 2009 23:00:00 +0100 2525856 http://www.medworm.com/index.php?rid=2525859&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19358001%26dopt%3DAbstract Authors: Wong A, Dunk NM, Callaghan JP This paper presents a systematic approach to lumbar spine vertebrae tracking in fluoroscopic images using complex-valued wavelets. The proposed algorithm is designed specifically based on a set of performance criteria associated with the detection and tracking of feature points in lumbar spine vertebrae from fluoroscopic images. The algorithm handles contrast and illumination non-homogeneities and noise in fluoroscopic images through the use of local phase information obtained using complex-valued wavelets. The algorithm is capable of tracking feature points that undergo various geometric deformations caused during the fluoroscopic imaging process by defining a descriptor that is invariant to scale and rotation and robust to affine, projective and... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2525859 Tue, 07 Apr 2009 23:00:00 +0100 2525859 http://www.medworm.com/index.php?rid=2224476&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19242833%26dopt%3DAbstract Authors: Folgado J, Fernandes PR, Jacobs CR, Pellegrini VD This work presents a computational model for the concurrent study of bone remodelling and ingrowth around cementless femoral stems in total hip arthroplasty. It is assumed that biological fixation depends upon the magnitude of relative displacement at the bone-stem interface as well as an ongoing updating of interface conditions during the remodelling process. The remodelling model determines the distribution of bone density by producing the stiffest structure for a given set of biological conditions at the point of equilibrium in bone turnover. Changes in bone density and patterns of ingrowth are compared for different stem geometries, materials and lengths of surface coating. Patterns of bone ingrowth on the tapered stem were... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2224476 Sun, 01 Mar 2009 11:28:34 +0100 2224476 http://www.medworm.com/index.php?rid=2224474&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19242834%26dopt%3DAbstract Authors: Iorga LN, Shan B, Pelegri AA A finite element (FE) model is employed to investigate the dynamic response of soft tissues under external excitations, particularly corresponding to the case of harmonic motion imaging. A solid 3D mixed 'u-p' element S8P0 is implemented to capture the near-incompressibility inherent in soft tissues. Two important aspects in structural modelling of these tissues are studied; these are the influence of viscous damping on the dynamic response and, following FE-modelling, a developed state-space formulation that valuates the efficiency of several order reduction methods. It is illustrated that the order of the mathematical model can be significantly reduced, while preserving the accuracy of the observed system dynamics. Thus, the reduced-order state-s... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2224474 Sun, 01 Mar 2009 11:27:50 +0100 2224474 http://www.medworm.com/index.php?rid=2224478&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19242832%26dopt%3DAbstract Authors: Abi-Abdallah D, Drochon A, Robin V, Fokapu O Blood flow in a steady magnetic field has been of great interest over recent years. Many researchers have examined the effects of magnetic fields on velocity profiles and arterial pressure, and major studies have focused on steady or sinusoidal flows. In this paper, we present a solution for pulsed magnetohydrodynamic blood flow with a somewhat realistic physiological pressure wave obtained using a Windkessel lumped model. A pressure gradient is derived along a rigid vessel placed at the output of a compliant module which receives the ventricle outflow. Then, velocity profile and flow rate expressions are derived in the rigid vessel in the presence of a steady transverse magnetic field. As expected, results showed flow retardation a... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2224478 Wed, 25 Feb 2009 05:00:00 +0100 2224478 http://www.medworm.com/index.php?rid=2202606&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19225961%26dopt%3DAbstract In this study, we use a subject-specific computer simulation approach to estimate internal and external loading of the distal tibia during the impact phase for two runners when running in shoes with different midsole cushioning parameters. The results suggest that: (1) changes in tibial loading induced by footwear are not reflected by changes in ground reaction force (GRF) magnitudes; (2) the GRF loading rate is a better surrogate measure of tibial loading and stress fracture risk than the GRF magnitude; and (3) averaging results across groups may potentially mask differential responses to training interventions between individuals. PMID: 19225961 [PubMed - as supplied by publisher] (Source: Computer Methods in Biomechanics and Biomedical Engineering) Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2202606 Thu, 19 Feb 2009 05:00:00 +0100 2202606 http://www.medworm.com/index.php?rid=2196269&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19221921%26dopt%3DAbstract Authors: Trachet B, Swillens A, Van Loo D, Casteleyn C, De Paepe A, Loeys B, Segers P In this paper, the influence of the aortic dimensions of an investigated mouse on its resulting wall shear stress (WSS) was studied. A numerical model of a mouse aortic arch was created based on a micro-CT scan of a vascular corrosion cast of an 8-week-old wild type mouse. This model was then rescaled to obtain five models with aortic root diameters corresponding to five different stages in the mouse life cycle varying from late fetal (0.7 mm) to old adult (1.5 mm). Consistent with literature, WSS values much higher than those normally encountered in humans were found. WSS was found to decrease rapidly in early life stages and to reach a plateau in adulthood, thus supporting a mediating role for WSS i... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2196269 Tue, 17 Feb 2009 05:00:00 +0100 2196269 http://www.medworm.com/index.php?rid=2192436&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19219677%26dopt%3DAbstract Authors: Lamvohee JM, Mootanah R, Ingle P, Cheah K, Dowell JK The effects of femoral prosthetic heads of diameters 22 and 28 mm were investigated on the stability of reconstructed hemi-pelves with cement mantles of thicknesses 1-4 mm and different bone qualities. Materialise medical imaging package and I-Deas finite element (FE) software were used to create accurate geometry of a hemi-pelvis from CT-scan images. Our FE results show an increase in cement mantle stresses associated with the larger femoral head. When a 22 mm femoral head is used on acetabulae of diameters 56 mm and above, the probability of survivorship can be increased by creating a cement mantle of at least 1 mm thick. However, when a 28 mm femoral head is used, a cement mantle thickness of at least 4 mm is needed. Poor... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2192436 Sat, 14 Feb 2009 05:00:00 +0100 2192436 http://www.medworm.com/index.php?rid=2175182&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19199168%26dopt%3DAbstract The objective of this study was to see whether a mathematical model of fracture healing was able to mimic bone formation around an unloaded screw-shaped titanium implant as it is well-believed that both processes exhibit many biological similarities. This model describes the spatio-temporal evolution of cellular activities, ranging from mesenchymal stem cell migration, proliferation, differentiation to bone formation, which are initiated and regulated by the growth factors present at the peri-implant site. For the simulations, a finite volume code was used and adequate initial and boundary conditions were applied. Two sets of analyses have been performed, in which either initial and boundary condition or model parameter values were changed with respect to the fracture healing model paramet... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2175182 Mon, 09 Feb 2009 05:00:00 +0100 2175182 http://www.medworm.com/index.php?rid=2175181&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19199169%26dopt%3DAbstract Authors: Evans SL A number of researchers have studied the mechanical properties of skin and developed constitutive models to describe its behaviour. Typically, many of these studies have concentrated on the uniaxial tensile behaviour of the skin, on the grounds that it will wrinkle under in-plane compression and have minimal stiffness. However, although there is a substantial body of literature on wrinkling models, the practical implementation of such a model of skin in a finite element setting has not been widely addressed. This paper presents computational details of a wrinkling, hyperelastic membrane model and aspects of its implementation and areas requiring further research are discussed. The model is based on an Ogden constitutive model, which provides accurate results at modera... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2175181 Mon, 09 Feb 2009 05:00:00 +0100 2175181 http://www.medworm.com/index.php?rid=2138940&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19172428%26dopt%3DAbstract Authors: Judy MV, Ravichandran KS, Murugesan K Genetic algorithms (GA) are often well suited for optimisation problems involving several conflicting objectives. It is more suitable to model the protein structure prediction problem as a multi-objective optimisation problem since the potential energy functions used in the literature to evaluate the conformation of a protein are based on the calculations of two different interaction energies: local (bond atoms) and non-local (non-bond atoms) and experiments have shown that those types of interactions are in conflict, by using the potential energy function, Chemistry at Harvard Macromolecular Mechanics. In this paper, we have modified the immune inspired Pareto archived evolutionary strategy (I-PAES) algorithm and denoted it as MI-PAES. It... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2138940 Mon, 26 Jan 2009 05:00:00 +0100 2138940 http://www.medworm.com/index.php?rid=2048832&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19089785%26dopt%3DAbstract Authors: Restrepo JM, Choksi R, Hyman JM, Jiang Y We extend, reformulate and analyse a phenomenological model for bone remodelling. The original macrobiomechanical model (MBM), proposed by Hazelwood et al. [J Biomech 2001; 34:299-308], couples a population equation for the cellular activities of the basic multicellular units (BMUs) in the bone and a rate equation to account for microdamage and repair. We propose to account for bone failure under severe overstressing by incorporating a Paris-like power-law damage accumulation term. The extended model agrees with the Hazelwood et al. predictions when the bone is under-stressed, and allows for suitably loaded bones to fail, in agreement with other MBM and experimental data regarding damage by fatigue. We numerically solve the extended mod... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2048832 Wed, 17 Dec 2008 05:00:00 +0100 2048832 http://www.medworm.com/index.php?rid=2048834&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19089682%26dopt%3DAbstract This study investigated a number of invariant based orthotropic and transversely isotropic constitutive equations for their suitability to fit three-dimensional simple shear mechanics data of passive myocardial tissue. A number of orthotropic laws based on Green strain components and one microstructurally based law have previously been investigated to fit experimental measurements of stress-strain behaviour. Here we extend this investigation to include several recently proposed functional forms, i.e. invariant based orthotropic and transversely isotropic constitutive relations. These laws were compared on the basis of (i) 'goodness of fit': how well they fit a set of six shear deformation tests, (ii) 'variability': how well determined the material parameters are over the range of experimen... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2048834 Tue, 16 Dec 2008 05:00:00 +0100 2048834 http://www.medworm.com/index.php?rid=2048833&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19089683%26dopt%3DAbstract This study suggests that biodegradable bone scaffolds could be used to fill bone defects in revision knee arthroplasty, but scaffold size seems to be the limiting factor. PMID: 19089683 [PubMed - as supplied by publisher] (Source: Computer Methods in Biomechanics and Biomedical Engineering) Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2048833 Tue, 16 Dec 2008 05:00:00 +0100 2048833 http://www.medworm.com/index.php?rid=2008180&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18665475%26dopt%3DAbstract XXXIII Congress of the Societe de Biomécanique, Compiègne, France, 1-3 September 2008. Comput Methods Biomech Biomed Engin. 2008;11 Suppl 1:1-227 Authors: PMID: 18665475 [PubMed - in process] (Source: Computer Methods in Biomechanics and Biomedical Engineering) Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2008180 Wed, 03 Dec 2008 19:24:49 +0100 2008180 http://www.medworm.com/index.php?rid=1931437&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18979301%26dopt%3DAbstract Authors: Morris L PMID: 18979301 [PubMed - in process] (Source: Computer Methods in Biomechanics and Biomedical Engineering) Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1931437 Tue, 04 Nov 2008 20:26:27 +0100 1931437 http://www.medworm.com/index.php?rid=1931436&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18979302%26dopt%3DAbstract Authors: Neofytou P, Tsangaris S, Kyriakidis M The current study is focused on the numerical investigation of the flow field induced by the unsteady flow in the vicinity of an abdominal aortic aneurysm model. The computational fluid dynamics code used is based on the finite volume method, and it has already been used in various bioflow studies. For modelling the rheological behaviour of blood, the Quemada non-Newtonian model is employed, which is suitable for simulating the two-phase character of blood namely a suspension of blood cells in plasma. For examining its non-Newtonian effects a comparison with a corresponding Newtonian flow is carried out. Furthermore, the investigation is focused on the distribution of the flow-induced forces on the interior wall of the aneurysm and in orde... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1931436 Tue, 04 Nov 2008 20:26:22 +0100 1931436 http://www.medworm.com/index.php?rid=1931435&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18979303%26dopt%3DAbstract Authors: Loerakker S, Cox LG, van Heijst GJ, de Mol BA, van de Vosse FN Together with new developments in mechanical cardiac support, the analysis of vortex dynamics in the left ventricle has become an increasingly important topic in literature. The aim of this study was to develop a method to investigate the influence of a left ventricular assist device (LVAD) on vortex dynamics in a failing ventricle. An axisymmetric fluid dynamics model of the left ventricle was developed and coupled to a lumped parameter model of the complete circulation. Simulations were performed for healthy conditions and dilated cardiomyopathy (DCM). Vortex structures in these simulations were analysed by means of automated detection. Results show that the strength of the leading vortex ring is lower in a DCM v... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1931435 Tue, 04 Nov 2008 20:26:18 +0100 1931435 http://www.medworm.com/index.php?rid=1906939&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18949590%26dopt%3DAbstract Authors: Andersen MS, Damsgaard M, Rasmussen J In this paper, we introduce a new general method for kinematic analysis of rigid multi body systems subject to holonomic constraints. The method extends the standard analysis of kinematically determinate rigid multi body systems to the over-determinate case. This is accomplished by introducing a constrained optimisation problem with the objective function given as a function of the set of system equations that are allowed to be violated while the remaining equations define the feasible set. We show that exact velocity and acceleration analysis can also be performed by solving linear sets of equations, originating from differentiation of the Karush-Kuhn-Tucker optimality conditions. The method is applied to the analysis of an 18 degrees-of-... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1906939 Thu, 23 Oct 2008 04:00:00 +0100 1906939 http://www.medworm.com/index.php?rid=1906938&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18949651%26dopt%3DAbstract Authors: Abdoli-Eramaki M, Stevenson JM, Agnew MJ, Kamalzadeh A The purpose of this study was to validate a 3D dynamic virtual model for lifting tasks against a validated link segment model (LSM). A face validation study was conducted by collecting x, y, z coordinate data and using them in both virtual and LSM models. An upper body virtual model was needed to calculate the 3D torques about human joints for use in simulated lifting styles and to estimate the effect of external mechanical devices on human body. Firstly, the model had to be validated to be sure it provided accurate estimates of 3D moments in comparison to a previously validated LSM. Three synchronised Fastraktrade mark units with nine sensors were used to record data from one male subject who completed dynamic box lifting... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1906938 Thu, 23 Oct 2008 04:00:00 +0100 1906938 http://www.medworm.com/index.php?rid=1906937&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18949652%26dopt%3DAbstract Authors: Brazel E, Taylor D Bone defects create stress concentrations which can cause fracture under impact or cyclic loading. Defects are often repaired by filling them with a bone graft material; this will reduce the stress concentration, but not completely, because these materials have lower stiffness than bone. The fracture risk decreases over time as the graft material is replaced by living bone. Many new bone graft materials are being developed, using tissue engineering and other techniques, but currently there is no rational way to compare these materials and predict their effectiveness in repairing a given defect. This paper describes, for the first time, a theoretical model which can be used to predict failure by brittle fracture or fatigue, initiating at the defect. Prelimina... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1906937 Thu, 23 Oct 2008 04:00:00 +0100 1906937 http://www.medworm.com/index.php?rid=1906936&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18949653%26dopt%3DAbstract Authors: Feenstra PH, Taylor CA A simulation framework for drug-eluting stents (DES) is presented that simulates the two distinct operational phases of a DES: stent deployment is simulated first, a mechanical porohyperelastic/elasto-plastic/contact analysis. This analysis calculates the interstitial fluid velocity as the result of interstitial fluid pressure gradients and mechanical deformations of the vessel wall. The deformed geometry, interstitial fluid velocity field and porosity field are extracted and used as input for the drug release simulation: a reaction-advection-diffusion (RAD) transport analysis calculating the spatial and temporal drug distribution. The advantage of this approach is that the deformed geometry and interstitial fluid velocity field are not assumed a priori,... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1906936 Thu, 23 Oct 2008 04:00:00 +0100 1906936 http://www.medworm.com/index.php?rid=1877213&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18853290%26dopt%3DAbstract This study proposes an adaptation for the trapeziometacarpal joint. The definition of the segment coordinate system of both trapezium and first metacarpal is based on functional anatomy. The definition of the joint coordinate system (JCS) is guided by the two degrees of freedom of the joint, i.e. flexion-extension about a trapezium axis and abduction-adduction about a first metacarpal axis. The rotations obtained using three methods are compared on the same data: the fixed axes sequence proposed by Cooney et al., the mobile axes sequence proposed by the ISB and our alternative mobile axes sequence. The rotation amplitudes show a difference of 9 degrees in flexion-extension, 2 degrees in abduction-adduction and 13 degrees in internal-external rotation. This study emphasizes the importance o... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1877213 Mon, 13 Oct 2008 04:00:00 +0100 1877213 http://www.medworm.com/index.php?rid=1869248&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18846460%26dopt%3DAbstract Authors: Abolfathi N, Naik A, Sotudeh Chafi M, Karami G, Ziejewski M This paper proposes a micromechanics algorithm utilising the finite element method (FEM) for the analysis of heterogeneous matter. The characterisation procedure takes the material properties of the constituents, axons and extracellular matrix (ECM) as input data. The material properties of both the axons and the matrix are assumed to have linear viscoelastic behaviour with a perfect bonding between them. The results of the modelling have been validated with experimental data with material white input from brainstem by considering the morphology of brainstem in which most axons are oriented in longitudinal direction in the form of a uniaxial fibrous composite material. The method is then employed to examine the undula... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1869248 Fri, 10 Oct 2008 04:00:00 +0100 1869248 http://www.medworm.com/index.php?rid=1860627&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18839383%26dopt%3DAbstract Authors: Pahr DH, Zysset PK New ideas for the extraction of finite element (FE) models from high-resolution computed tomography datasets are presented. The multi-step approach starts with a 3D region-growing algorithm in order to extract the outer voxel based iso-surface. This information is used to compute a voxel model of the cortical shell. The next step provides triangulated surfaces of the outer bone contour. Three-dimensional deformable models using a gradient vector flow and a multi-level mesh resampling are used. These meshes are self-regularising and of high quality. A further step contains a new self correcting cortical shell thickness evaluation algorithm, which results in topological conform smooth inner and outer compact bone iso-surface meshes. Such iso-surfaces can be us... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1860627 Mon, 06 Oct 2008 04:00:00 +0100 1860627 http://www.medworm.com/index.php?rid=1845903&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18828027%26dopt%3DAbstract Authors: Gerschutz MJ, Phillips CA, Reynolds DB, Repperger DW High-force pneumatic muscle actuators (PMAs) are used for force assistance with minimal displacement applications. However, poor control due to dynamic nonlinearities has limited PMA applications. A simulated control system is developed consisting of: (1) a controller relating an input position angle to an output proportional pressure regulator voltage, (2) a phenomenological model of the PMA with an internal dynamic force loop (system time constant information), (3) a physical model of a human sit-to-stand task and (4) an external position angle feed-back loop. The results indicate that PMA assistance regarding the human sit-to-stand task is feasible within a specified PMA operational pressure range. PMID: 18828027 [Pub... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1845903 Tue, 30 Sep 2008 04:00:00 +0100 1845903 http://www.medworm.com/index.php?rid=1845902&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18828028%26dopt%3DAbstract Authors: Miller RH, Gillette JC, Derrick TR, Caldwell GE Muscle forces during locomotion are often predicted using static optimisation and SQP. SQP has been criticised for over-estimating force magnitudes and under-estimating co-contraction. These problems may be related to SQP's difficulty in locating the global minimum to complex optimisation problems. Algorithms designed to locate the global minimum may be useful in addressing these problems. Muscle forces for 18 flexors and extensors of the lower extremity were predicted for 10 subjects during the stance phase of running. Static optimisation using SQP and two random search (RS) algorithms (a genetic algorithm and simulated annealing) estimated muscle forces by minimising the sum of cubed muscle stresses. The RS algorithms predicted... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1845902 Tue, 30 Sep 2008 04:00:00 +0100 1845902 http://www.medworm.com/index.php?rid=1838652&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18821189%26dopt%3DAbstract Authors: Early M, Lally C, Prendergast PJ, Kelly DJ The success of stents to restore blood flow in atherosclerotic peripheral arteries is low relative to coronary arteries. It has been shown that joint flexion induces a mechanical environment that makes stent placement in these arteries highly incompatible, and damage and destruction of stents has been recorded. However, the effect of this environment on the stresses in the arteries is unknown. It is hypothesised that the stresses induced in arteries as a result of this mechanical environment could be sufficient to explain the relatively low success rates. To investigate this hypothesis, a finite element model of the stent-artery interaction was developed. Following stent expansion, bending was simulated by applying a displacement boun... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1838652 Sat, 27 Sep 2008 04:00:00 +0100 1838652 http://www.medworm.com/index.php?rid=1838651&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18821190%26dopt%3DAbstract Authors: Zoghi-Moghadam M, Sadegh AM Blunt and rotational head impacts due to vehicular collisions, falls and contact sports cause relative motion between the brain and skull. This increases the normal and shear stresses in the (skull/brain) interface region consisting of cerebrospinal fluid (CSF) and subarachnoid space (SAS) trabeculae. The relative motion between the brain and skull can explain many types of traumatic brain injuries (TBI) including acute subdural hematomas (ASDH) and subarachnoid hemorrhage (SAH) which is caused by the rupture of bridging veins that transverse from the deep brain tissue to the superficial meningeal coverings. The complicated geometry of the SAS trabeculae makes it impossible to model all the details of the region. Investigators have compromised this ... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1838651 Sat, 27 Sep 2008 04:00:00 +0100 1838651 http://www.medworm.com/index.php?rid=1838653&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18821096%26dopt%3DAbstract Authors: El-Rich M, Villemure I, Labelle H, Aubin CE Biomechanics of the isthmic spondylolysis was investigated by using a nonlinear 3D-finite element model (FEM). A personalised in vivo pediatric geometry of L5-S1 low-grade spondylolisthesis patient was used to develop a L5-pelvis motion segment model that took into consideration vertebrae, disc and ligaments. The stress distribution in the affected motion segment under axial force only, and for a combination of flexion and extension was evaluated. Predicted results showed that, under all loading conditions, stresses were much higher on the pedicle and in the dorsal wall of the pars interarticularis due to the abnormal geometry which is consistent with clinical observations. PMID: 18821096 [PubMed - as supplied by publisher] (Sour... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1838653 Fri, 26 Sep 2008 04:00:00 +0100 1838653 http://www.medworm.com/index.php?rid=1817784&cid=s_38096_169_f&fid=38096&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D18803059%26dopt%3DAbstract Authors: Buehler MJ, Ackbarow T Biological protein materials (BPMs), intriguing hierarchical structures formed by assembly of chemical building blocks, are crucial for critical functions of life. The structural details of BPMs are fascinating: They represent a combination of universally found motifs such as alpha-helices or beta-sheets with highly adapted protein structures such as cytoskeletal networks or spider silk nanocomposites. BPMs combine properties like strength and robustness, self-healing ability, adaptability, changeability, evolvability and others into multi-functional materials at a level unmatched in synthetic materials. The ability to achieve these properties depends critically on the particular traits of these materials, first and foremost their hierarchical architectu... Computer Methods in Biomechanics and Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=1817784 Fri, 19 Sep 2008 04:00:00 +0100 1817784