Abstract：
:The flow of cerebrospinal fluid (CSF) in a patient-specific model of the subarachnoid space in a Chiari I patient was investigated using numerical simulations. The pulsating CSF flow was modeled using a time-varying velocity pulse based on peak velocity measurements (diastole and systole) derived from a selection of patients with Chiari I malformation. The present study introduces the general definition of the Reynolds number to provide a measure of CSF flow instability to give an estimate of the possibility of turbulence occurring in CSF flow. This was motivated by the fact that the combination of pulsating flow and the geometric complexity of the spinal canal may result in local Reynolds numbers that are significantly higher than the commonly used global measure such that flow instabilities may develop into turbulent flow in these regions. The local Reynolds number was used in combination with derived statistics to characterize the flow. The results revealed the existence of both local unstable regions and local regions with velocity fluctuations similar in magnitude to what is observed in fully turbulent flows. The results also indicated that the fluctuations were not self-sustained turbulence, but rather flow instabilities that may develop into turbulence. The case considered was therefore believed to represent a CSF flow close to transition.
journal_name
J Biomechjournal_title
Journal of biomechanicsauthors
Helgeland A,Mardal KA,Haughton V,Reif BAdoi
10.1016/j.jbiomech.2013.12.023subject
Has Abstractpub_date
2014-03-21 00:00:00pages
1082-90issue
5eissn
0021-9290issn
1873-2380pii
S0021-9290(14)00002-5journal_volume
47pub_type
杂志文章abstract：:Poisson's ratio has not been experimentally measured earlier for meniscus in compression. It is however an important intrinsic material property needed in biomechanical analysis and computational models. In this study, equilibrium Poisson's ratio of bovine meniscus (n = 6) was determined experimentally by combining st...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2018.07.001
更新日期：2018-08-22 00:00:00
abstract：:The estimation of segment inertial parameters (SIPs) is an important source of error in inverse dynamic analysis. In most individual cases SIPs are derived from extrapolation of known SIPs of a certain population through regression equations (proportional models). Another well-known method is the use of mathematical a...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/0021-9290(95)00086-0
更新日期：1996-05-01 00:00:00
abstract：PURPOSE:Evidence concerning the alteration of knee function during landing suffers from a lack of consensus. This uncertainty can be attributed to methodological flaws, particularly in relation to the statistical analysis of variable human movement data. The aim of this study was to compare single-subject and group ana...
journal_title：Journal of biomechanics
pub_type： 临床试验,杂志文章
doi：10.1016/j.jbiomech.2012.05.046
更新日期：2012-08-09 00:00:00
abstract：:This communication extends the recently reported cell-specific finite element (FE) method in Slomka and Gefen (2010) in which geometrically realistic FE cell models are created from confocal microscopy scans for large deformation analyses. The cell-specific FE method is extended here in the following aspects: (i) we d...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2010.09.012
更新日期：2011-02-03 00:00:00
abstract：:The aims of this study were: 1. To study the transfer of energy between the high bar and the gymnast. 2. To develop criteria from the utilisation of high bar elasticity and the utilisation of muscle capacity to assess the effectiveness of a movement solution. 3. To study the influence of varying segment movement upon ...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/s0021-9290(98)00134-1
更新日期：1998-12-01 00:00:00
abstract：:Computational models have recently been developed to replicate experimental conditions present in the Stanmore knee wear simulator. These finite element (FE) models, which provide a virtual platform to evaluate total knee replacement (TKR) mechanics, were validated through comparisons with experimental data for a spec...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2005.07.029
更新日期：2006-01-01 00:00:00
abstract：:The purpose of the present study was to investigate the rotational kinematics pattern of the upper trunk and the pelvis and the complexity-variability of their movement, during the sprint butterfly stroke between male and female swimmers with long fins (18-26 cm) and without fins. Two pairs of 3D accelerometers and gy...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2016.01.004
更新日期：2016-02-08 00:00:00
abstract：:The aim of this study was to analyze changes in gait variability and symmetry in distance runners. Fourteen competitive athletes ran on an instrumented treadmill for 10,000 m at speeds equivalent to 103% of their season's best time. Spatiotemporal and ground reaction force data were recorded at 1500, 3000, 5000, 7500 ...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2018.08.008
更新日期：2018-10-05 00:00:00
abstract：:The study verifies the development of active axial stress in the wall of mouse aorta over a range of physiological loads when the smooth muscle cells are stimulated to contract. The results obtained show that the active axial stress is virtually independent of the magnitude of pressure, but depends predominately on th...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2012.05.025
更新日期：2012-07-26 00:00:00
abstract：BACKGROUND:Dilation and dissection of aneurysmal ascending aortic tissues occur preferentially at the outer curvature of the vessel. In this study we hypothesize that the density and contractile properties of the vascular smooth muscle cells (VSMCs) of the pig ascending aorta (AA) are heterogeneous and could explain th...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2010.04.018
更新日期：2010-08-26 00:00:00
abstract：:Human runners adjust the stiffness of their stance leg to accommodate surface stiffness during steady state running. This adjustment allows runners to maintain similar center of mass movement (e.g., ground contact time and stride frequency) regardless of surface stiffness. When runners encounter abrupt transitions in ...
journal_title：Journal of biomechanics
pub_type： 临床试验,杂志文章,随机对照试验
doi：10.1016/s0021-9290(99)00078-0
更新日期：1999-08-01 00:00:00
abstract：:The reference point indentation (RPI) method is a microindentation technique involving successive indentation cycles. We employed RPI to measure average stiffness (Ave US), indentation distance increase (IDI), total indentation distance (TID), average energy dissipated (Ave ED), and creep indentation distance (CID) of...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2013.04.003
更新日期：2013-06-21 00:00:00
abstract：:Side-cutting is commonly used to evaluate knee joint kinematics and kinetics in the context of anterior cruciate ligament injury risk. Many existing side-cutting studies fail to clearly define the orientation of the femoral frame and the knee axis, making comparisons between studies difficult. A femoral frame construc...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2012.05.017
更新日期：2012-07-26 00:00:00
abstract：:The feasibility of determining biphasic material properties using regression models was investigated. A transversely isotropic poroelastic finite element model of stress relaxation was developed and validated against known results. This model was then used to simulate load intensity for a wide range of material proper...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2013.05.028
更新日期：2013-07-26 00:00:00
abstract：:Numerical models commonly account for elastic inhomogeneity in cortical bone using power-law scaling relationships with various measures of tissue density, but limited experimental data exists for anatomic variation in elastic anisotropy. A recent study revealed anatomic variation in the magnitude and anisotropy of el...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2011.04.009
更新日期：2011-06-03 00:00:00
abstract：:Inguinal herniation represents a common condition requiring surgical intervention. Despite being regarded as a connective tissue disorder of uncertain cause, research has focused predominantly on biochemical changes in the key tissue layer, the transversalis fascia (TF) with little direct analysis of functional tissue...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2008.08.018
更新日期：2008-12-05 00:00:00
abstract：:Hind limb kinematics were recorded in five horses at walk and trot using an opto-electronic CODA-3 system. Simultaneously, in vivo strain in the completely tendinous peroneus tertius muscle was registered by implanted mercury-in-silastic strain gauges. The origin-insertion length patterns of the peroneus tertius were ...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/0021-9290(92)90284-8
更新日期：1992-11-01 00:00:00
abstract：:The aim of this study was to develop a model which describes the mechanical spinal response to small alternating pelvic stimulation induced by an active rotational movement of a normal chair. The rotary continuous passive motion (RCPM) of the seat about a vertical axis of only 0.6 degrees resulted in an increased in s...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/s0021-9290(99)00231-6
更新日期：2000-06-01 00:00:00
abstract：:The aim of this study was to test the hypothesis that running at fixed fractions of Froude (Nfr) and Strouhal (Str) dimensionless numbers combinations induce dynamic similarity between humans of different sizes. Nineteen subjects ran in three experimental conditions, (i) constant speed, (ii) similar speed (Nfr) and (i...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2014.10.012
更新日期：2014-12-18 00:00:00
abstract：:Many soft biological tissues possess a considerable surface stress, which plays a significant role in their biophysical functions, but most previous methods for characterizing their mechanical properties have neglected the effects of surface stress. In this work, we investigate the micropipette aspiration method to me...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2018.08.020
更新日期：2018-10-26 00:00:00
abstract：:Valgus moments on the knee joint during single-leg landing have been suggested as a risk factor for anterior cruciate ligament (ACL) injury. The purpose of this study was to test the influence of isolated valgus moment on ACL strain during single-leg landing. Physiologic levels of valgus moments from an in vivo study ...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2008.10.031
更新日期：2009-02-09 00:00:00
abstract：:The methods of evaluation of mechanical energy economy during human movement based on the calculation of three different values of work (Wwb, Ww, Wn), corresponding to three hypothetical types of energy exchange, are subject to criticism. Only the value of work, Wwb, calculated under the assumption of energy transfers...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/0021-9290(86)90006-0
更新日期：1986-01-01 00:00:00
abstract：:For the purpose of detecting early aberrations of gait in rheumatoid arthritis 17 women suffering from that disease were examined. They were all under 50 years of age and had an essentially normal range of motility in the hips, knees and ankles. Eleven healthy women walking at voluntary speed and 6 healthy women walki...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/0021-9290(88)90237-0
更新日期：1988-01-01 00:00:00
abstract：:In presence of aortic stenosis, a jet is produced downstream of the aortic valve annulus during systole. The vena contracta corresponds to the location where the cross-sectional area of the flow jet is minimal. The maximal transvalvular pressure gradient (TPG(max)) is the difference between the static pressure in the ...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2005.10.013
更新日期：2006-01-01 00:00:00
abstract：:Exposure following pelvic organ prolapse repair has been observationally associated with wrinkling of the implanted mesh. The purpose of this study was to quantify the impact of variable boundary conditions on the out-of-plane deformations of mesh subjected to tensile loading. Using photogrammetry and surface curvatur...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2015.02.061
更新日期：2015-06-25 00:00:00
abstract：:Foot mobility commonly contributes to injury via altered motion of the lower extremities. However, there is a lack of understanding of sensitive kinetic changes with flat foot. The purpose of this study was to investigate the threshold that best distinguishes between participants with and without flat foot. The kineti...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2015.11.004
更新日期：2016-01-04 00:00:00
abstract：:This paper investigated the factors that influence Hecht vault performance and assessed the level of model complexity required to give an adequate representation of vaulting. A five-segment planar simulation model with a visco-elastic shoulder joint and a torque generator at the shoulder joint was used to simulate the...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/j.jbiomech.2004.02.039
更新日期：2005-01-01 00:00:00
abstract：:The in situ longitudinal strain of canine and porcine aortas was investigated. Marks of black water-resistant ink were placed on the aortas and the axial lengths between the marks were measured in situ and in vitro. When the aortas were cut, the retraction was measured and described by the stretch ratio, which is defi...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/0021-9290(94)00091-h
更新日期：1995-05-01 00:00:00
abstract：:The relationship between patella alta and patellar subluxation may, in part, reflect the relationship between the height of the patella above the tibiofemoral joint line and the patellofemoral contact force. This study reports on the direct in vitro measurement of the patellofemoral contact force, and its point of app...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/0021-9290(94)90222-4
更新日期：1994-08-01 00:00:00
abstract：:A composite cushion acetabular cup for a total hip replacement has been designed and developed jointly by Leeds University and DePuy International. In order to assess the long-term performance of this novel design, two sets of simulator tests of more than 4 million cycles duration have been carried out with the cushio...
journal_title：Journal of biomechanics
pub_type： 杂志文章
doi：10.1016/s0021-9290(98)00034-7
更新日期：1998-04-01 00:00:00
