Kinda Khalaf | KUSTAR - Academia.edu (original) (raw)

Papers by Kinda Khalaf

2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015

Degenerative disc disease is one of the most common causes of low back pain instigating huge soci... more Degenerative disc disease is one of the most common causes of low back pain instigating huge socioeconomic costs and posing an immense burden on healthcare systems worldwide. New therapeutic approaches to damaged intervertebral discs are therefore of great interest. Platelet-Rich Plasma (PRP) has been proposed for the repair and regeneration of degenerated discs, but there remains a knowledge gap regarding its effectiveness and influence on disc material properties. The objective of this study was to investigate and quantify the material properties of intact, denatured, and PRP treated discs. A systematic methodology was established in the process, where ex-vivo experiments were conducted and material properties were extracted using an inverse finite element approach. The results showed that PRP is able to recover the mechanical properties of denatured discs, thereby providing a promising effective therapeutic modality.

2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015

A single-degree-of-freedom model is considered for flexible exercise bars based on the lumped-ele... more A single-degree-of-freedom model is considered for flexible exercise bars based on the lumped-element approach. By considering the side segment of a flexible bar as a cantilever beam with an equivalent mass at the free end, its free-vibration response, as well as the forced response under the excitation of the grip, are expressed parametrically. Experiments are performed on a particular flexible bar (FLEXI_BAR) in order to obtain numerical values for quantifying the model's parameters. The model is also computationally simulated to study the response of the flexible bar to various excitations. The results are imported into a multi-segment musculoskeletal software (AnyBody), where the effect of different initial hand positions on the lumbar disc and back muscle forces is investigated (including Longissimus, Iliocostalis, and Transversus) during up-down exercises. The results show that all intervertebral discs and muscles forces are more sensitive to the horizontal position of the bar as compared to its vertical position.

2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015

This paper aims to demonstrate the possibility of exploiting poly-L-lactic acid (PLLA) ultra-thin... more This paper aims to demonstrate the possibility of exploiting poly-L-lactic acid (PLLA) ultra-thin films as platforms for bio-hybrid actuation. Firstly, flat PLLA nanofilms at different concentrations (15 and 25 mg/ml in dichloromethane) were tested with contractile cardiomyocytes. The results obtained using motion vector analysis, a non-invasive method capable of estimating flow velocities on recorded videos, demonstrated that PLLA nanofilms were able to move under the contraction of muscle cells. Immunofluorescence images reflected good cell spreading, thus confirming that these films are promising matrices for bio-hybrid actuation. Subsequently, microgrooved PLLA nanofilms were fabricated, in order to drive muscle cell distribution on an anisotropic surface, thus optimizing the system's efficiency. After matrix characterization, in terms of AFM and SEM imaging, we investigated the viability and morphology of C2C12 skeletal muscle cells (a more controllable muscle cell type), 24 h after cell seeding as well as at the 7-day differentiation state.

Journal of biomechanics, Jan 6, 2015

It has been suggested that the central nervous system simplifies muscle control through basic uni... more It has been suggested that the central nervous system simplifies muscle control through basic units, called synergies. In this study, we have developed a novel target-matching protocol and used non-negative matrix factorization (NMF) technique to extract trunk muscle synergies and corresponding torque synergies. Isometric torque data at the L5/S1 level and electromyographic patterns of twelve abdominal and back muscles from twelve healthy participants (five females) were simultaneously recorded. Each participant performed a total number of 24 isometric target-matching tasks using 12 different angular directions and 2 levels of uniaxial and biaxial exertions. Within- and between-subject similarities were assessed by considering both the data of different pairs of participants, where the activation coefficients of one participant were used in the NMF analysis of another participant, and the Pearson's correlation coefficients (R) between muscle synergy vectors. The results showed t...

Journal of Applied Biomechanics

Frontiers in endocrinology, 2015

Type 2 diabetes mellitus (T2DM) is a global public health problem of epidemic proportions, with 6... more Type 2 diabetes mellitus (T2DM) is a global public health problem of epidemic proportions, with 60-70% of affected individuals suffering from associated neurovascular complications that act on multiple organ systems. The most common and clinically significant neuropathies of T2DM include uremic neuropathy, peripheral neuropathy, and cardiac autonomic neuropathy. These conditions seriously impact an individual's quality of life and significantly increase the risk of morbidity and mortality. Although advances in gene sequencing technologies have identified several genetic variants that may regulate the development and progression of T2DM, little is known about whether or not the variants are involved in disease progression and how these genetic variants are associated with diabetic neuropathy specifically. Significant missing heritability data and complex disease etiologies remain to be explained. This article is the first to provide a review of the genetic risk variants implicate...

Clinical Biomechanics, 2015

Comparison of the kinematic variability and dynamic stability of the trunk between healthy and lo... more Comparison of the kinematic variability and dynamic stability of the trunk between healthy and low back pain patient groups can contribute to gaining valuable information about the movement patterns and neuromotor strategies involved in various movement tasks. Fourteen chronic low back pain patients with mild symptoms and twelve healthy male volunteers performed repeated trunk flexion-extension movements in the sagittal plane at three different speeds: 20cycles/min, self-selected, and 40cycles/min. Mean standard deviations, coefficient of variation and variance ratio as variability measures; maximum finite-time Lyapunov exponents and maximum Floquet multipliers as stability measures were computed from trunk kinematics. Higher speed significantly reduced the kinematic variability, while it increased short-term Lyapunov exponents. Long-term Lyapunov exponents were higher at self-selected speed and lower in low back pain patients as compared to control volunteers. Floquet multipliers were larger at self-selected speed and during higher pace trunk movements. Our findings suggest that slower pace flexion-extension trunk movements are associated with more motor variation as well as local and orbital stability, implying less potential risk of injury for the trunk. Individuals with and without low back pain consistently recruited a closed-loop control strategy towards achieving trunk stability. Chronic low back pain patients exhibited more stable trunk movements over long-term periods, indicating probable temporary pain relief functional adaption strategies. These results may be used towards the development of more effective personalized rehabilitation strategies and quantitative spinal analysis tools for low back pain detection, diagnosis and treatment, as well as improvement of workspace and occupational settings.

Wound Medicine, 2015

Objectives: This study aims to increase understanding of the connection between oxidative stress ... more Objectives: This study aims to increase understanding of the connection between oxidative stress and inflammation in diabetes disease progression to provide a basis for investigating improved diagnostic possibilities, treatment and prevention of prediabetes.

Frontiers in Physiology, 2015

Background: Physiological interactions are abundant within, and between, body systems. These inte... more Background: Physiological interactions are abundant within, and between, body systems. These interactions may evolve into discrete states during pathophysiological processes resulting from common mechanisms. An association between arterial stenosis, identified by low ankle-brachial pressure index (ABPI) and cardiovascular disease (CVD) as been reported. Whether an association between vascular calcification-characterized by high ABPI and a different pathophysiology-is similarly associated with CVD, has not been established. The current study aims to investigate the association between ABPI, and cardiac rhythm, as an indicator of cardiovascular health and functionality, utilizing heart rate variability (HRV).

Clinical biochemistry, Jan 6, 2015

This study aims to increase understanding of the connection between oxidative stress and inflamma... more This study aims to increase understanding of the connection between oxidative stress and inflammation in diabetes disease progression to provide a basis for investigating improved diagnostic possibilities, treatment and prevention of prediabetes. Differences in the level of biochemical markers of oxidative stress (erythrocyte GSH/GSSG and urinary 8-isoprostane), inflammation (CRP, IL-6), endothelial dysfunction (plasma homocysteine, urinary 8-hydroxy-2-deoxy-guanosine) and coagulation/fibrinolysis (C5a, D-Dimer) were determined in prediabetes and control subjects. While no difference was found in the 8-isoprostane levels between the two groups, the erythrocyte GSH/GSSG ratio was significantly reduced in the prediabetes group compared to control, indicating increased oxidative stress in the prediabetic state. Both urinary 8-OHdG and surprisingly also plasma homocysteine were significantly elevated in the prediabetes group, indicating endothelial dysfunction. The inflammation markers ...

Technology and health care : official journal of the European Society for Engineering and Medicine, 2011

Healing rate of fractured bone differs from one patient to another which may lead to incorrect co... more Healing rate of fractured bone differs from one patient to another which may lead to incorrect consequent medical procedures. Thus, quantitative assessment of bone healing after fracture becomes important. In this paper, we present a mathematical model which describes the interaction of a pulsed mode ultrasound waves with a multilayered biological structure. The model is applied to estimate the bone callus thickness and degree of hardness. Different frequencies are utilized to obtain highest measurement sensitivity and accuracy of callus thickness and degree of hardness. It is found that a transducer operating at 1 MHz has the highest sensitivity to the different phases of callus hardening. On the other hand, a 3 MHz transducer yields the highest sensitivity to the thickness of the callus layer. Thus, using both frequencies might prove to be useful for full quantitative assessment of the bone healing process.

Biomedical sciences instrumentation, 1997

In investigating manual material handling (MMH) jobs, such as lifting, the quantification of the ... more In investigating manual material handling (MMH) jobs, such as lifting, the quantification of the various kinematic and kinetic parameters of the lift is an important step towards functional assessment and evaluation. Experimental data collection generates a large quantity of data for the different kinetic, kinematic, and electromyographic parameters over the various lifting cycles. In order to efficiently manage and interpret the data, it is important to use appropriate tools which would reduce the dimension of the original data set without sacrificing any important features. Furthermore, the generated parameters are often expressed as a function of the lifting cycle resulting in complex waveforms as the unit of analysis. Appropriate statistical analysis of these waveforms or motion profiles should reflect their vectorial constitution as a function of the lifting cycle rather than the usual method of using traditional descriptive statistics based on collapsing the data over the cycle.

Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2014

Osteoporosis is a progressive bone disease characterized by deterioration in the quantity and qua... more Osteoporosis is a progressive bone disease characterized by deterioration in the quantity and quality of bone, leading to inferior mechanical properties and an increased risk of fracture. Current assessment of osteoporosis is typically based on bone densitometry tools such as Quantitative Computed Tomography (QCT) and Dual Energy X-ray absorptiometry (DEXA). These assessment modalities mainly rely on estimating the bone mineral density (BMD). Hence present densitometry tools describe only the deterioration of the quantity of bone associated with the disease and not the affected morphology or microstructural changes, resulting in potential incomplete assessment, many undetected patients, and unexplained fractures. In this study, an in-silico parametric model of vertebral trabecular bone incorporating both material and microstructural parameters was developed towards the accurate assessment of osteoporosis and the consequent risk of bone fracture. The model confirms that the mechanical properties such as strength and stiffness of vertebral trabecular tissue are highly influenced by material properties as well as morphology characteristics such as connectivity, which reflects the quality of connected inter-trabecular parts. The FE cellular solid model presented here provides a holistic approach that incorporates both material and microstructural elements associated with the degenerative process, and hence has the potential to provide clinical practitioners and researchers with more accurate assessment method for the degenerative changes leading to inferior mechanical properties and increased fracture risk associated with age and/or disease such as Osteoporosis.

Frontiers in Bioengineering and Biotechnology, 2015

The risk of low back pain resulted from cyclic loadings is greater than that resulted from prolon... more The risk of low back pain resulted from cyclic loadings is greater than that resulted from prolonged static postures. Disk degeneration results in degradation of disk solid structures and decrease of water contents, which is caused by activation of matrix digestive enzymes.The mechanical responses resulted from internal solid-fluid interactions of degenerative disks to cyclic loadings are not well studied yet. The fluid-solid interactions in disks can be evaluated by mathematical models, especially the poroelastic finite element (FE) models. We developed a robust disk poroelastic FE model to analyze the effect of degeneration on solidfluid interactions within disk subjected to cyclic loadings at different loading frequencies. A backward analysis combined with in vitro experiments was used to find the elastic modulus and hydraulic permeability of intact and enzyme-induced degenerated porcine disks. The results showed that the averaged peak-to-peak disk deformations during the in vitro cyclic tests were well fitted with limited FE simulations and a quadratic response surface regression for both disk groups. The results showed that higher loading frequency increased the intradiscal pressure, decreased the total fluid loss, and slightly increased the maximum axial stress within solid matrix. Enzyme-induced degeneration decreased the intradiscal pressure and total fluid loss, and barely changed the maximum axial stress within solid matrix. The increase of intradiscal pressure and total fluid loss with loading frequency was less sensitive after the frequency elevated to 0.1 Hz for the enzyme-induced degenerated disk. Based on this study, it is found that enzyme-induced degeneration decreases energy attenuation capability of disk, but less change the strength of disk. (2015) Effect of degeneration on fluid-solid interaction within intervertebral disk under cyclic loading -a meta-model analysis of finite element simulations. Front. Bioeng. Biotechnol. 3:4.

Engineering Solid Mechanics, 2015

2014 8th Conference of the European Study Group on Cardiovascular Oscillations (ESGCO), 2014

Early identification of cardiac autonomic neuropathy (CAN) leads to better treatment outcomes. He... more Early identification of cardiac autonomic neuropathy (CAN) leads to better treatment outcomes. Heart rate variability (HRV) analysis allows identification of CAN but is sensitive to the length of recording and the presence of artifacts and ectopics, requiring preprocessing and consideration of length of recording. RR intervals from 10second and 5-minute ECG recordings from patients with no CAN, early CAN and definite CAN were preprocessed using adaptive filtering with the controlling parameter c set at 0.2, 0.5 and 0.8, and time and frequency domain HRV analysis applied. Early CAN and definite CAN required different setting of c with respect to the length of recording. The 5-minute recording with c=0.2 provided the best results using RMSSD for normal versus eCAN (p=0.0007) and for eCAN versus dCAN (0.019). Clinically, this has potential use in general practice for screening patients at risk, newly diagnosed with diabetes, or for follow-up during the course of diabetes.

ABSTRACT Thesis (M.S.)--Ohio State University, 1991. Includes bibliographical references. Advisor... more ABSTRACT Thesis (M.S.)--Ohio State University, 1991. Includes bibliographical references. Advisor: N. Berme, Dept. of Mechanical Engineering.

2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015

Degenerative disc disease is one of the most common causes of low back pain instigating huge soci... more Degenerative disc disease is one of the most common causes of low back pain instigating huge socioeconomic costs and posing an immense burden on healthcare systems worldwide. New therapeutic approaches to damaged intervertebral discs are therefore of great interest. Platelet-Rich Plasma (PRP) has been proposed for the repair and regeneration of degenerated discs, but there remains a knowledge gap regarding its effectiveness and influence on disc material properties. The objective of this study was to investigate and quantify the material properties of intact, denatured, and PRP treated discs. A systematic methodology was established in the process, where ex-vivo experiments were conducted and material properties were extracted using an inverse finite element approach. The results showed that PRP is able to recover the mechanical properties of denatured discs, thereby providing a promising effective therapeutic modality.

2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015

A single-degree-of-freedom model is considered for flexible exercise bars based on the lumped-ele... more A single-degree-of-freedom model is considered for flexible exercise bars based on the lumped-element approach. By considering the side segment of a flexible bar as a cantilever beam with an equivalent mass at the free end, its free-vibration response, as well as the forced response under the excitation of the grip, are expressed parametrically. Experiments are performed on a particular flexible bar (FLEXI_BAR) in order to obtain numerical values for quantifying the model's parameters. The model is also computationally simulated to study the response of the flexible bar to various excitations. The results are imported into a multi-segment musculoskeletal software (AnyBody), where the effect of different initial hand positions on the lumbar disc and back muscle forces is investigated (including Longissimus, Iliocostalis, and Transversus) during up-down exercises. The results show that all intervertebral discs and muscles forces are more sensitive to the horizontal position of the bar as compared to its vertical position.

2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015

This paper aims to demonstrate the possibility of exploiting poly-L-lactic acid (PLLA) ultra-thin... more This paper aims to demonstrate the possibility of exploiting poly-L-lactic acid (PLLA) ultra-thin films as platforms for bio-hybrid actuation. Firstly, flat PLLA nanofilms at different concentrations (15 and 25 mg/ml in dichloromethane) were tested with contractile cardiomyocytes. The results obtained using motion vector analysis, a non-invasive method capable of estimating flow velocities on recorded videos, demonstrated that PLLA nanofilms were able to move under the contraction of muscle cells. Immunofluorescence images reflected good cell spreading, thus confirming that these films are promising matrices for bio-hybrid actuation. Subsequently, microgrooved PLLA nanofilms were fabricated, in order to drive muscle cell distribution on an anisotropic surface, thus optimizing the system's efficiency. After matrix characterization, in terms of AFM and SEM imaging, we investigated the viability and morphology of C2C12 skeletal muscle cells (a more controllable muscle cell type), 24 h after cell seeding as well as at the 7-day differentiation state.

Journal of biomechanics, Jan 6, 2015

It has been suggested that the central nervous system simplifies muscle control through basic uni... more It has been suggested that the central nervous system simplifies muscle control through basic units, called synergies. In this study, we have developed a novel target-matching protocol and used non-negative matrix factorization (NMF) technique to extract trunk muscle synergies and corresponding torque synergies. Isometric torque data at the L5/S1 level and electromyographic patterns of twelve abdominal and back muscles from twelve healthy participants (five females) were simultaneously recorded. Each participant performed a total number of 24 isometric target-matching tasks using 12 different angular directions and 2 levels of uniaxial and biaxial exertions. Within- and between-subject similarities were assessed by considering both the data of different pairs of participants, where the activation coefficients of one participant were used in the NMF analysis of another participant, and the Pearson's correlation coefficients (R) between muscle synergy vectors. The results showed t...

Journal of Applied Biomechanics

Frontiers in endocrinology, 2015

Type 2 diabetes mellitus (T2DM) is a global public health problem of epidemic proportions, with 6... more Type 2 diabetes mellitus (T2DM) is a global public health problem of epidemic proportions, with 60-70% of affected individuals suffering from associated neurovascular complications that act on multiple organ systems. The most common and clinically significant neuropathies of T2DM include uremic neuropathy, peripheral neuropathy, and cardiac autonomic neuropathy. These conditions seriously impact an individual's quality of life and significantly increase the risk of morbidity and mortality. Although advances in gene sequencing technologies have identified several genetic variants that may regulate the development and progression of T2DM, little is known about whether or not the variants are involved in disease progression and how these genetic variants are associated with diabetic neuropathy specifically. Significant missing heritability data and complex disease etiologies remain to be explained. This article is the first to provide a review of the genetic risk variants implicate...

Clinical Biomechanics, 2015

Comparison of the kinematic variability and dynamic stability of the trunk between healthy and lo... more Comparison of the kinematic variability and dynamic stability of the trunk between healthy and low back pain patient groups can contribute to gaining valuable information about the movement patterns and neuromotor strategies involved in various movement tasks. Fourteen chronic low back pain patients with mild symptoms and twelve healthy male volunteers performed repeated trunk flexion-extension movements in the sagittal plane at three different speeds: 20cycles/min, self-selected, and 40cycles/min. Mean standard deviations, coefficient of variation and variance ratio as variability measures; maximum finite-time Lyapunov exponents and maximum Floquet multipliers as stability measures were computed from trunk kinematics. Higher speed significantly reduced the kinematic variability, while it increased short-term Lyapunov exponents. Long-term Lyapunov exponents were higher at self-selected speed and lower in low back pain patients as compared to control volunteers. Floquet multipliers were larger at self-selected speed and during higher pace trunk movements. Our findings suggest that slower pace flexion-extension trunk movements are associated with more motor variation as well as local and orbital stability, implying less potential risk of injury for the trunk. Individuals with and without low back pain consistently recruited a closed-loop control strategy towards achieving trunk stability. Chronic low back pain patients exhibited more stable trunk movements over long-term periods, indicating probable temporary pain relief functional adaption strategies. These results may be used towards the development of more effective personalized rehabilitation strategies and quantitative spinal analysis tools for low back pain detection, diagnosis and treatment, as well as improvement of workspace and occupational settings.

Wound Medicine, 2015

Objectives: This study aims to increase understanding of the connection between oxidative stress ... more Objectives: This study aims to increase understanding of the connection between oxidative stress and inflammation in diabetes disease progression to provide a basis for investigating improved diagnostic possibilities, treatment and prevention of prediabetes.

Frontiers in Physiology, 2015

Background: Physiological interactions are abundant within, and between, body systems. These inte... more Background: Physiological interactions are abundant within, and between, body systems. These interactions may evolve into discrete states during pathophysiological processes resulting from common mechanisms. An association between arterial stenosis, identified by low ankle-brachial pressure index (ABPI) and cardiovascular disease (CVD) as been reported. Whether an association between vascular calcification-characterized by high ABPI and a different pathophysiology-is similarly associated with CVD, has not been established. The current study aims to investigate the association between ABPI, and cardiac rhythm, as an indicator of cardiovascular health and functionality, utilizing heart rate variability (HRV).

Clinical biochemistry, Jan 6, 2015

This study aims to increase understanding of the connection between oxidative stress and inflamma... more This study aims to increase understanding of the connection between oxidative stress and inflammation in diabetes disease progression to provide a basis for investigating improved diagnostic possibilities, treatment and prevention of prediabetes. Differences in the level of biochemical markers of oxidative stress (erythrocyte GSH/GSSG and urinary 8-isoprostane), inflammation (CRP, IL-6), endothelial dysfunction (plasma homocysteine, urinary 8-hydroxy-2-deoxy-guanosine) and coagulation/fibrinolysis (C5a, D-Dimer) were determined in prediabetes and control subjects. While no difference was found in the 8-isoprostane levels between the two groups, the erythrocyte GSH/GSSG ratio was significantly reduced in the prediabetes group compared to control, indicating increased oxidative stress in the prediabetic state. Both urinary 8-OHdG and surprisingly also plasma homocysteine were significantly elevated in the prediabetes group, indicating endothelial dysfunction. The inflammation markers ...

Technology and health care : official journal of the European Society for Engineering and Medicine, 2011

Healing rate of fractured bone differs from one patient to another which may lead to incorrect co... more Healing rate of fractured bone differs from one patient to another which may lead to incorrect consequent medical procedures. Thus, quantitative assessment of bone healing after fracture becomes important. In this paper, we present a mathematical model which describes the interaction of a pulsed mode ultrasound waves with a multilayered biological structure. The model is applied to estimate the bone callus thickness and degree of hardness. Different frequencies are utilized to obtain highest measurement sensitivity and accuracy of callus thickness and degree of hardness. It is found that a transducer operating at 1 MHz has the highest sensitivity to the different phases of callus hardening. On the other hand, a 3 MHz transducer yields the highest sensitivity to the thickness of the callus layer. Thus, using both frequencies might prove to be useful for full quantitative assessment of the bone healing process.

Biomedical sciences instrumentation, 1997

In investigating manual material handling (MMH) jobs, such as lifting, the quantification of the ... more In investigating manual material handling (MMH) jobs, such as lifting, the quantification of the various kinematic and kinetic parameters of the lift is an important step towards functional assessment and evaluation. Experimental data collection generates a large quantity of data for the different kinetic, kinematic, and electromyographic parameters over the various lifting cycles. In order to efficiently manage and interpret the data, it is important to use appropriate tools which would reduce the dimension of the original data set without sacrificing any important features. Furthermore, the generated parameters are often expressed as a function of the lifting cycle resulting in complex waveforms as the unit of analysis. Appropriate statistical analysis of these waveforms or motion profiles should reflect their vectorial constitution as a function of the lifting cycle rather than the usual method of using traditional descriptive statistics based on collapsing the data over the cycle.

Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2014

Osteoporosis is a progressive bone disease characterized by deterioration in the quantity and qua... more Osteoporosis is a progressive bone disease characterized by deterioration in the quantity and quality of bone, leading to inferior mechanical properties and an increased risk of fracture. Current assessment of osteoporosis is typically based on bone densitometry tools such as Quantitative Computed Tomography (QCT) and Dual Energy X-ray absorptiometry (DEXA). These assessment modalities mainly rely on estimating the bone mineral density (BMD). Hence present densitometry tools describe only the deterioration of the quantity of bone associated with the disease and not the affected morphology or microstructural changes, resulting in potential incomplete assessment, many undetected patients, and unexplained fractures. In this study, an in-silico parametric model of vertebral trabecular bone incorporating both material and microstructural parameters was developed towards the accurate assessment of osteoporosis and the consequent risk of bone fracture. The model confirms that the mechanical properties such as strength and stiffness of vertebral trabecular tissue are highly influenced by material properties as well as morphology characteristics such as connectivity, which reflects the quality of connected inter-trabecular parts. The FE cellular solid model presented here provides a holistic approach that incorporates both material and microstructural elements associated with the degenerative process, and hence has the potential to provide clinical practitioners and researchers with more accurate assessment method for the degenerative changes leading to inferior mechanical properties and increased fracture risk associated with age and/or disease such as Osteoporosis.

Frontiers in Bioengineering and Biotechnology, 2015

The risk of low back pain resulted from cyclic loadings is greater than that resulted from prolon... more The risk of low back pain resulted from cyclic loadings is greater than that resulted from prolonged static postures. Disk degeneration results in degradation of disk solid structures and decrease of water contents, which is caused by activation of matrix digestive enzymes.The mechanical responses resulted from internal solid-fluid interactions of degenerative disks to cyclic loadings are not well studied yet. The fluid-solid interactions in disks can be evaluated by mathematical models, especially the poroelastic finite element (FE) models. We developed a robust disk poroelastic FE model to analyze the effect of degeneration on solidfluid interactions within disk subjected to cyclic loadings at different loading frequencies. A backward analysis combined with in vitro experiments was used to find the elastic modulus and hydraulic permeability of intact and enzyme-induced degenerated porcine disks. The results showed that the averaged peak-to-peak disk deformations during the in vitro cyclic tests were well fitted with limited FE simulations and a quadratic response surface regression for both disk groups. The results showed that higher loading frequency increased the intradiscal pressure, decreased the total fluid loss, and slightly increased the maximum axial stress within solid matrix. Enzyme-induced degeneration decreased the intradiscal pressure and total fluid loss, and barely changed the maximum axial stress within solid matrix. The increase of intradiscal pressure and total fluid loss with loading frequency was less sensitive after the frequency elevated to 0.1 Hz for the enzyme-induced degenerated disk. Based on this study, it is found that enzyme-induced degeneration decreases energy attenuation capability of disk, but less change the strength of disk. (2015) Effect of degeneration on fluid-solid interaction within intervertebral disk under cyclic loading -a meta-model analysis of finite element simulations. Front. Bioeng. Biotechnol. 3:4.

Engineering Solid Mechanics, 2015

2014 8th Conference of the European Study Group on Cardiovascular Oscillations (ESGCO), 2014

Early identification of cardiac autonomic neuropathy (CAN) leads to better treatment outcomes. He... more Early identification of cardiac autonomic neuropathy (CAN) leads to better treatment outcomes. Heart rate variability (HRV) analysis allows identification of CAN but is sensitive to the length of recording and the presence of artifacts and ectopics, requiring preprocessing and consideration of length of recording. RR intervals from 10second and 5-minute ECG recordings from patients with no CAN, early CAN and definite CAN were preprocessed using adaptive filtering with the controlling parameter c set at 0.2, 0.5 and 0.8, and time and frequency domain HRV analysis applied. Early CAN and definite CAN required different setting of c with respect to the length of recording. The 5-minute recording with c=0.2 provided the best results using RMSSD for normal versus eCAN (p=0.0007) and for eCAN versus dCAN (0.019). Clinically, this has potential use in general practice for screening patients at risk, newly diagnosed with diabetes, or for follow-up during the course of diabetes.

ABSTRACT Thesis (M.S.)--Ohio State University, 1991. Includes bibliographical references. Advisor... more ABSTRACT Thesis (M.S.)--Ohio State University, 1991. Includes bibliographical references. Advisor: N. Berme, Dept. of Mechanical Engineering.