bluuebunny/crossref_metadata_2025_split huggingface dataset:
Age-Dependent Morphological Changes of the Human Carotid Bifurcation
Authors: Lieber Baruch B. , Wakhloo Ajay K. , Luft Andreas R. , Divani Afshin A. 
Published: December 2021

Abstract
The development, significance and function of the human carotid sinus is not yet well understood. The arterial wall within the carotid sinus is well enervated and it contains baroreceptive neural terminals. One hypothesis that was put forward is that the dilation, which may involve all vessels of the carotid bifurcation, exists to support pressure sensing1. Another hypothesis that is supported only by phenomenological observations assume that the function of the sinus is to protect the brain by slowing blood flow and reducing pulsatility2. Yet another hypothesis interprets the sinus as an ontogenetic or phylogenic residual3. More recently, carotid hemodynamics has been investigated using in vitro and computational models. Flow patterns in the carotid sinus were found to be complex and as such have been implicated in the hetrogenesis and subsequent development of atherosclerosis at this site. However, the development of this unique sinus morphology, the role of hemodynamics in such development, and the physiological implications created by this unique morphology have not been investigated. Understanding the hemodynamic and developmental forces that play a role in remodeling of the carotid bifurcation and development of the sinus is of both fundamental and clinical interest and can lead to better prognostication and therapy of carotid disease.
Therefore, we initiated a study of the morphological development of the human carotid bulb using different age groups under the hypothesis that sinus morphology reflects an adaptive change in response to alterations in cerebral blood supply during the developmental years of the brain. This adaptation attempts to reduce hydraulic losses in the carotid bifurcation through reduced flow disturbances and maintain high level of blood supply to the brain than consumes about 15% of cardiac output under basal conditions. In addition, it may protect the sinus wall from high shear stress and/or the brain from highly pulsatile blood flow conditions.
Initially, we analyzed the angle and sinus morphology of the carotid bifurcation in pediatric and adult patients using biplane digital subtraction angiograms to characterize changes that occur as the brain matures.
Measurement by PIV of Synoptic Strain Rate Downstream of a St. Jude Prosthetic Valve
Authors: Lourenco L. M. , Spellings K. J. 
Published: December 2021

Abstract
It is widely accepted that shear stresses in flowing blood affect the behavior of blood cells. Effects may range from the alteration of the surface properties of platelets to damage of cell walls. These effects result in the release of biochemical signals leading to platelet aggregation and thrombus formation. While numerous studies support these observations it is still unclear what the main shear mechanisms are. However, there is large support to the notion that turbulent shear stresses (Reynolds stresses) are the major contributor to the shear experienced by blood solids.
Time-Varying Effect of Ascorbate on the Compressive Modulus and Gag Content of Chondrocyte-Seeded Agarose Cultures
Authors: Mauck Robert L. , Soltz Michael A. , Gilbert Beth , Ateshian Gerard A. , Hung Clark T. , Raia Frank J. , Valhmu Wilmot B. 
Published: December 2021

Abstract
The generation of a cartilage substitute will require both the mechanical and biochemical properties of the substance to approach that of native tissue. Recent studies (Buschmann et al., 1992, 1995; Bader and Lee, 1997) have shown that agarose can provide a suitable environment for the production of a mechanically functional matrix. Over time cells seeded in this matrix alter the intrinsic mechanical properties of the matrix. Additionally, several studies have included such biochemical factors as vitamin C (ascorbate) to the culture medium. This biological effector has varied effects on chondrocyte matrix biosynthesis. Specifically, it has been shown to promote calcification in chick growth plate chondrocytes (Wu et al., 1989), while it increased both type II and type I procollagen mRNA in 5 day culture (Sandell and Daniel, 1988). Conversely, it has been shown in bovine culture that aggrecan mRNA levels rise steadily in monolayer culture without ascorbate. but rise quickly and then fall off in its presence (Hering et al., 1994). To assess the effect of ascorbate in our system, primary bovine articular chondrocytes seeded in agarose, we initiated a study to examine the effects of ascorbate on both the production of cartilage extracellular matrix and the development of mechanical properties over a 14 day culture period. Three groups were studied: agarose disks without cells (control) and cell-seeded agarose disks maintained in DMEM supplemented daily with and without 50 μg/ml of ascorbate. Glycosaminoglycan (GAG) and hydroxyproline contents of each disk were determined using standard colorimetric assays.
Fluid-Induced Shear Stress Stimulates Ca2+ Signaling in Human Tendon Epitenon Cells
Authors: Francke Eric , Elfervig Michelle K. , Sood Ajay , Brown Thomas D. , Bynum Donald K. , Banes Albert J. 
Published: December 2021

Abstract
Tendon cells reside in an environment rich in mechanical stimuli and respond to these stimuli with a variety of activities. Whole tendon, ex vivo, responds to cyclic stretch by increasing DNA and collagen synthesis (Banes et al., 1999). Cultured epitenon and internal cells from tendon respond synergistically to cyclic tensile strain and a growth factor (Banes et al., 1995). Tendon cells stimulated by plasma membrane indentation with a micropipet propagate intercellular calcium waves to neighboring cells via gap junctions (Kenamond et al., 1997). Tendon cells subjected to equibiaxial cyclic stretching signal with a transient rise in intracellular calcium (Kenamond et al., 1998). Recently, it has been shown that connective tissue cells are responsive to fluid-induced shear stress similar to cells of the vascular system. Moreover, Brown and coworkers have shown that apparati used to apply substrate tension to cultured cells have limitations that include a potentially confounding component of fluid-induced shear stress (Brown et al., 1998). Hence, there is a concern that a given cell response to substrate stretching may actually involve a response to shear stress or some combination of the two stimuli. We have designed a parallel plate, laminar flow apparatus that provides regulated fluid-induced shear stress and subjected tendon cells to shear stresses of 0, 5, 10, 15 and 20 dynes/cm2. This will enable us to make a direct comparison between fluid-induced shear stress and substrate deformation on tendon cell signaling and downstream gene responses.
Simulation of Surface Fatigue Crack Propagation in UHMWPE Tibial Components for Total Knee Replacement
Authors: Estupiñán Jaime A. , Bartel Donald L. , Wright Timothy M. 
Published: December 2021

Abstract
A simulation of surface fatigue damage to ultra-high molecular weight polyethylene (UHMWPE) components in total knee replacement is presented. Results of simulations of surface fatigue crack propagation were consistent with observed clinical damage. Extensions of these analyses to incorporate a more realistic description of the constitutive and fracture behavior of UHMWPE and three dimensional geometry are discussed.
The Relationship Between Hip Simulator Wear and Surface Morphology Characterized Using White Light Interferometry
Authors: Muhlstein C. L. , Kurtz S. M. , Chui C. , Rising M. , Edidin A. A. 
Published: December 2021

Abstract
A non-contact surface topography measurement system based on white light interferometry was used to quantify the surface morphology of the UHMWPE, PTFE, HDPE, and polyacetal liners before and after wear testing. We investigated the hypothesis that the wear rate of four polymeric materials in the hip simulator was related to quantitative metrics of the surface morphology (i.e., surface roughness). Nine common roughness parameters (PV, Ra, Rrms, Rsk, Rku, Rtm, Rz, R3z, and H) were evaluated in 28 acetabular liners. The surface morphology within a given material was reproducible from insert to insert. Statistical relationships were observed between the surface roughness of the acetabular liners and the volumetric wear rate (p &lt; 1 × 10−6). However, the power law relationships accounted for less than 50% of the variability in the data, based on r2.
Assessment of Orientation-Dependent Torsional Constraints Provided by a Contemporary Total Ankle Replacement
Authors: McIff Terence E. , Saltzman Charles L. , Brown Thomas D. 
Published: December 2021

Abstract
This paper describes torsional testing on the components of a unique total ankle design, to establish the range and conditions of torsional constraint. For this design, the torsional constraint was found to be dependent on the relative flexion and inversion angles between components. Dorsiflexion provides greater torsional stability than plantarflexion. The maximum torque values were recorded at 25 degrees of dorsiflexion with no relative inversion. Under these conditions, and with a weight bearing load of 1200 N, the ankle resisted 2200 N-mm at 5 degrees of rotation and 3300 N-mm at 15 degrees of rotation. Torsional stability decreased as the relative inversion or eversion of the components increased. When the components were inverted more than a few degrees, the initial rotational stiffness became negligible.
Simulation of Trabecular Bone Yield Using Nonlinear Finite Element Analysis
Authors: Niebur Glen L. , Hsia Andy C. , Chen Tony J. , Keaveny Tony M. 
Published: December 2021

Abstract
Knowledge of the failure properties of trabecular bone will lead to improved modeling of whole bone fracture and bone-prosthesis systems. Because trabecular bone is anisotropic, its yield properties are dependent on orientation. Defining a complete orthotropic yield criterion requires multiple material constants to be determined experimentally. As these constants can depend on both architecture and density, a large numbers of specimens would be needed to develop a complete criterion. This may not be feasible, especially for human bone, due to difficulties in obtaining suitable specimens.
The Effect of Loading Rate on the Load Sharing Between Passive and Active Subsystems of Spine: A Finite Element Analysis
Authors: Wang J. L. , Shirazi-Adl A. , Parnianpour M. , Engin A. E. 
Published: December 2021

Abstract
The effects of dynamic loading rate on the load sharing of passive and active subsytems of the spine were evaluated using a validated viscoelastic finite element (FE) model of a L2-L3 motion segment. Both the force controlled and hybrid force-rotation controlled simulations were performed to best simulate the in-vivo loading conditions. The stiffening response of motion segement at higher loading rate was predicted by both simulation strategies, while the interpretation of the hybrid simulations was much easier due to decoupling of the confounding interactions of load, posture and loading rate. The results collectively indicate that the loading rate markedly effects the distribution of stress/strain in the tissues and reduces the margin of safety of the spine. The results should be used in developing a better biomechanical basis for considering the role of trunk speed as a risk factor for low back disorders.
Biphasic Poroviscoelastic Model Simultaneously Predicts Axial Reaction Force and Lateral Displacement of Articular Cartilage During an Unconfined Compression-Stress Relaxation Experiment
Authors: DiSilvestro Mark R. , Zhu Qiliang , Wong Marcy , Jurvelin Jukka , Suh Jun-Kyo 
Published: December 2021

Abstract
Articular cartilage lining the articulating surfaces in diarthrodial joints is composed of an extracellular matrix and interstitial fluid. The complex mechanical behavior of this tissue has been successfully modeled by the linear biphasic poroviscoelastic (BPVE) model first introduced by Mak (1986). This model, a simple extension of the well-known biphasic theory first proposed by Mow et al. (1980), accounts for both fluid flow-dependent and fluid flow-independent viscoelastic mechanisms which contribute to the overall mechanical behavior exhibited by the tissue. Despite the success of the linear BPVE model for indentation (Suh and Bai, 1997), as well as that described for unconfined compression (Suh and DiSilvestro, 1997, 1998), the model’s ability to account for more than one measurable variable with a single parameter set has not been established. Therefore, the objective, of this study was to assess the ability of the linear BPVE model to account for both the axial reaction force and lateral deformation of a cylindrical plug of articular cartilage subjected to unconfined compression under a stress relaxation protocol.
Material Constants for Human Annulus Fibrosus Depend on Water Content and Reference Configuration
Authors: Klisch Stephen M. , Lotz Jeffrey C. 
Published: December 2021

Abstract
We apply a special theory of an incompressible mixture of an elastic solid and an inviscid fluid (Klisch and Lotz, 1998) to experimental data for healthy human annulus fibrosus tested in a stress-relaxation confined compression protocol. The material constants revealed no significant differences due to orientation (i.e., axial vs. radial, n = 16). The aggregate modulus and initial permeability constants were significantly different (n = 32) due to the choice of theory used to fit the data (i.e., that of Klisch and Lotz (1998) vs. that of Holmes and Mow (1990)) and were significantly correlated with initial water content.
The Effect of Trunk Velocity on Concentric and Eccentric Isokinetic Extension Strength of Healthy Men
Authors: Ng Joseph K.-F. , Chan William , Chung Keny , Hung Dino , Lun C. L. , Tang William , Parnianpour Mohamad 
Published: December 2021

Abstract
The dynamic contractile behavior of the muscle is commonly represented by the torque-velocity relation, which is an inverse hyperbolic relationship between muscular tension and the velocity of muscle action (shortening in concentric, static in isometric and lengthening in eccentric muscle actions). This relationship has been well established for extremity muscles but this study extended the range of trunk velocity (−60 to 60 °/sec) that had been used for trunk extensors in the past. The effect of velocity was significant on trunk extensor strength, while the expected plateau was not found within the speed considered.
Seat Failure in Rear Impacts
Authors: Friedman Keith , Gaston Fiona , Bish Jack , Sances Anthony 
Published: December 2021

Abstract
An analysis of rear end accidents involving 1377 driver and right front seat occupants was conducted examining the probability of seat performance failure as a function of crash severity and the injury severity as a function of both crash severity and seat performance. The results suggest that occupants with seat failures experience serious injury more frequently than without such failures for the same Delta-V. Intrusion into the area behind the occupant’s seat appears to be an important consideration in increasing the risk of injury.
Biomechanical Analysis of Padding
Authors: Sances Anthony , Herbst Brian , Forrest Stephen , Meyer Steven E. , Khadilkar Anil V. 
Published: December 2021

Abstract
Padding materials are routinely used to reduce the potential for head injury. The interior of vehicles has been identified as an area where injury can occur in the absence of padding. Head impacts with roof, pillars and support structures have been studied by Fan, Monk, and Friedman. Recent rulemaking by the National Highway Traffic Safety Administration has identified padding as a potential mechanism for reduction in head injury. Helmets utilize padding for energy management so as to reduce the potential for head injury. (Meyers, Becker). The occurrence of diffuse axonal injury with direct impacts and translational accelerations have been evaluated by Nishimoto. Mclean has suggested that brain injury does not occur without head impact.
Design of a Sports Knee Prosthesis
Authors: DiAngelo Denis J. , Evans Charles E. 
Published: December 2021

Abstract
Typical walking prostheses maintain stability during stance with a knee locking mechanism; i.e., a frictional device (mechanical brake) or free rotating knee joint (single pinned or multi-link system) held in a hyper-extended orientation (de Vries, 1995). Attempts to jog with a walking prosthesis are difficult and unsafe. A previous gait study of a “pogo-stick” A/K jogging prosthesis found that the device provided alternating periods of support and non-support between the amputated and non-amputated sides, but required greater energy expenditure from the intact limb and induced larger impact loads (DiAngelo et al., 1989). A computer modeling technique was used to design a multi-link above-knee (A/K) prosthesis that provided continuous, controlled knee flexion during weight bearing and free knee rotation during swing. Aspects of the design were improved energy expenditure, symmetrical gait, and reduced impact loading. Biomechanical data for the computation model was obtained from a gait study of an A/K amputee jogger. The objective of the study was to develop prosthetic knee that provided continuous knee flexion throughout weight bearing and free rotation during swing.
Through-Tool Coolant Drilling of Aluminium/SiC Metal Matrix Composite
Authors: Barnes S. , Pashby I. R. 
Published: December 2021

Abstract
Through-tool coolant has been applied to the drilling of a 2618 aluminium alloy reinforced with 18% silicon carbide (SiC) particles. Titanium nitride coated, K10, solid carbide drills were used to investigate the effect of the coolant application method on the performance of the drilling operation. Through holes were drilled in a 24 mm thick workpiece material without the application of any coolant, with the conventional application of coolant and with the coolant applied through-the tool. Cutting forces were measured during the drilling trials in addition to the wear on the drills, the extent of the entry and exit burrs produced on the workpiece and the quality of the holes produced. The results obtained provided strong evidence that the conventional application of coolant was having no beneficial effect on the cutting operation compared to dry drilling. However, there was very little evidence of an increase in drill wear which some workers suggest is associated with the formation of an abrasive slurry when using coolant with MMCs. Nevertheless, examination of the used drills in the scanning electron microscope confirmed abrasion as the primary wear mechanism. The results showed mat even at the low coolant pressures, through-tool cooling gave a significant improvement in tool wear, cutting forces, surface finish and the height of the burrs produced. Consequently, the recommendations from this work are that through-tool coolant can result in a marked improvement in performance when drilling MMCs and that conventional cooling has virtually no effect on the machinability of this material compared with dry drilling.
Nonlinear Modeling of 3D Open-Cell Foams
Authors: Wang Yu , Cuitiño Alberto M. 
Published: December 2021

Abstract
In this article, we present a hyperelastic model for light and compliant open cell foams with an explicit correlation between microstructure and macroscopic behavior. The model describes a large number of three dimensional structures with regular and irregular cells. The theory is based on the formulation of strain-energy function accounting for stretching which is the main deformation mechanism in this type of materials. Within the same framework, however, bending, shear and twisting energies can also be incorporated. The formulation incorporates nonlinear kinematics which traces the evolution of the structure during loading process and its effects on the constitutive behavior, including the cases where configurational transformations are present leading to non-convex strain-energy functions. Also nonlinear material effects at local or beam level are introduced to accommodate a wide range of different material behaviors. Since the micromechanical formulation presented here has explicit correlation with the foam structure, it preserves in the constitutive relation the symmetries or directional properties of the corresponding structures, including the cases of re-entrant foams which exhibit negative Poisson’s ratio effects. The model captures the central features exhibit by these materials. Predictions of the model for macroscopic uniaxial strain are presented in this article.
A New X-Actuator Design for Controlling Wing Bending and Twisting Modes
Authors: Ye R. , Ding J. H. , Tzou H. S. 
Published: December 2021

Abstract
Recent development of smart structures and structronic systems has demonstrated the technology in many engineering applications. Active structural control of aircraft wings or helicopter blades (e.g., shapes, flaps, leading and/or trailing edges) can significantly enhance the aerodynamic efficiency and flight maneuverability of high-performance airplanes and helicopters. This paper in to evaluate the dual bending and torsion vibration control effects of an X-actuator configuration reconfigured from a parallel configuration. Finite element (FE) formation of a new FE using the layerwise constant shear angle theory is reviewed and the derived governing equations are discussed. Bending and torsion control effects of plates are studied using the FE method and also demonstrated via laboratory experiments. FE and experimental results both suggest the X-actuator is effective to both bending and torsion control of plates.
Dynamic Modeling of an Innovative Piezoelectric Actuator for Minimally Invasive Surgery
Authors: Edinger Benjamin , Frecker Mary , Gardner John 
Published: December 2021

Abstract
A small piezoelectric inchworm actuator has been designed for use with a monolithic compliant end-effector in minimally invasive surgery procedures. A dynamic model of the inchworm actuator has been developed using SIMULINK. Utilizing the equations of motion for the inchworm actuator, the dynamic characteristics of the piezoelectric stack material, and the known compliance of the gripper, a force measurement model has been developed which extracts resisting force information from the piezoelectric signal. The focus of this paper is on the development of the dynamic model and the results of a simulation study that will be used to develop optimal driving signals for the inchworm actuator. Simulation results include the predicted displacement capabilities and settling time of the inchworm actuator over a range of driving frequencies.
Development of Piezoelectrically Actuated Elastodynamic Flapping Micro-Aerial Vehicles
Authors: Cox Adam , Monopoli Daniel J. , Goldfarb Michael , Garcia Ephrahim 
Published: December 2021

Abstract
A discussion of the principles involved in small-scale flight is presented here. In addition, several novel mechanisms have been developed in an attempt to mechanically emulate flapping flight on the meso-scale. Wings are being developed which will exploit particular material properties to emulate the dynamic characteristics of insect wings. The flapping mechanisms developed in this paper use piezoelectric unimorph actuators integrated with compliant, solid-state flexure based mechanisms. Four and five bar linkages are used to convert the linear unimorph output into a single degree-of-freedom rotational flapping motion. Due to their capacitive nature, piezoelectric actuators generally dissipate less power than traditional actuation methods such as electromagnetic motors. Piezoelectric actuators possess a high power density and are capable of high force output. They are frequently used to induce structural resonances, making them suitable for use in these devices. The dynamics of these systems rely on the mechanics of flexure mechanisms, the mechanical and electrical behavior of the piezoelectric elements, and the aerodynamic interaction of the wings and the air, resulting in a complex, nonlinear problem.