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Articles 271 - 296 of 296

Full-Text Articles in Biomedical Engineering and Bioengineering

Alterations In Multiple Measures Of White Matter Integrity In Normal Women At High Risk For Alzheimer's Disease, Brian T. Gold, David K. Powell, Anders H. Andersen, Charles D. Smith Oct 2010

Alterations In Multiple Measures Of White Matter Integrity In Normal Women At High Risk For Alzheimer's Disease, Brian T. Gold, David K. Powell, Anders H. Andersen, Charles D. Smith

Neuroscience Faculty Publications

There is evidence that disruption of white matter (WM) microstructure is an early event in the course of Alzheimer's disease (AD). However, the neurobiological bases of WM microstructural declines in presymptomatic AD are unknown. In the present study we address this issue using a multimodal imaging approach to the study of presymptomatic AD. Participants were 37 high-risk (both family history of dementia and one or more APOE4 alleles) women and 20 low-risk (neither family history nor APOE4) women. Groups were matched for age, education, neuropsychological performance, and vascular factors that could affect white matter. Whole-brain analyses of diffusion tensor imaging …

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Correlating The Magnitude And Spatial Gradient Of Alternans, Stuart Traxel Jan 2010

Correlating The Magnitude And Spatial Gradient Of Alternans, Stuart Traxel

University of Kentucky Master's Theses

Electrical restitution has been shown to inaccurately predict the occurrence of alternans of action potential duration. A new method using the spatial gradient of alternans (SGA) is proposed to predict alternans and cardiac electrical stability. A simulated 1-D strand of tissue was used to compare indexes computed from restitution methods and the SGA method to changes in the amplitude of alternans using different electro-physiological alterations. The SGA method correlated better with changes in the amplitude of alternans than restitution methods for a decrease in the transient outward current (Ito) and conduction velocity. Restitution methods correlated better with changes …

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Multiwall Carbon Nanotubes Alter The Thermal Profile And Antibiotic Elution Of Orthopaedic Bone Cement, Alison Carroll Tickle Jan 2010

Multiwall Carbon Nanotubes Alter The Thermal Profile And Antibiotic Elution Of Orthopaedic Bone Cement, Alison Carroll Tickle

University of Kentucky Master's Theses

Multiwall carbon nanotubes (MWNTs) have extraordinary mechanical and thermal transport properties. They significantly improve the static and dynamic mechanical properties of acrylic orthopaedic bone cement when added to the dry cement polymer powder. Understanding the role MWNTs play on bone cement polymerization temperatures will lead to improved mechanical integrity of the cement-bone interface in joint arthroplasties. It was determined through thermal testing that MWNTs increased the polymerization time of the methylmethacrylate by 45-460% and decreased the peak exothermic temperature of bone cement with and without antibiotics. The flow of heat produced during polymerizing cement was reduced 25-85% with the addition …

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Distraction Osteogenesis In An Organ Culture Model, Bradley R. Heil Jan 2010

Distraction Osteogenesis In An Organ Culture Model, Bradley R. Heil

University of Kentucky Master's Theses

Distraction osteogenesis (DO) is a surgical procedure in which applied strain stimulates new bone growth; however, the underlying mechanisms by which bone cells respond to load are still uncertain. An organ culture model of DO was developed and validated by using linear distraction on the femoral shafts of 5 day old Wistar rats. Two loading regimes were utilized: distracting the bones for 2 hrs on day 1 (GRP I); distracting the bones for 2 hrs on days 1, 3, and 5 (GRP II). After 1 week in culture, the bones were compared to unloaded contralateral controls and assessed for changes. …

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Synthesis And Characterization Of Magnetic Hydrogel Nanocomposites For Cancer Therapy Applications, Samantha Ann Meenach Jan 2010

Synthesis And Characterization Of Magnetic Hydrogel Nanocomposites For Cancer Therapy Applications, Samantha Ann Meenach

University of Kentucky Doctoral Dissertations

Currently, cancer is the second leading cause of death in the United States. Conventional cancer treatment includes chemotherapy, radiation, and surgical resection, but unfortunately, all of these methods have significant drawbacks. Hyperthermia, the heating of cancerous tissues to between 41 and 45°C, has been shown to improve the efficacy of cancer therapy when used in conjunction with irradiation and/or chemotherapy. In this work, a novel method for remotely administering heat is presented. This method involves heating of tumor tissue using hydrogel nanocomposites containing magnetic nanoparticles which can be remotely heated upon exposure to an external alternating magnetic field (AMF). The …

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Igf-I Releasing Plga Scaffolds For Growth Plate Regeneration, Sharath Kumar Chinnakavanam Sundararaj Jan 2010

Igf-I Releasing Plga Scaffolds For Growth Plate Regeneration, Sharath Kumar Chinnakavanam Sundararaj

University of Kentucky Master's Theses

Growth plate is a highly organized cartilaginous tissue found at the end of long bones and is responsible for longitudinal growth of the bones. Growth plate fracture leads to retarded growth and unequal limb length, which might have a lifelong effect on a person’s physical stature. This research is a tissue engineering approach for the treatment of growth plate injury. Insulin-like growth factor I (IGF-I), which can stimulate cartilage formation, was encapsulated within PLGA microspheres that were then used to form porous scaffolds. The release profile of the IGF-I from the PLGA scaffold showed a biphasic release pattern. In vitro …

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Understanding The Development Of Infant Feeding: A Spectral Analysis Approach, Pooja Vijaygopal Jan 2009

Understanding The Development Of Infant Feeding: A Spectral Analysis Approach, Pooja Vijaygopal

University of Kentucky Master's Theses

Feeding problems in preterm neonates stem from complications of early delivery. Attainment of independent feeding is a prerequisite for Neonatal Intensive Care Unit (NICU) discharges. Some quantitative studies of infant feeding involve excessive amounts of time for data processing. Multivariate spectral analysis was used to minimize time for investigation of variability in these rhythms. Auto and Cross-spectral parameters of the rhythms were correlated with Gestational Age (GA), Postmenstrual Age (PMA), Birthweight (BW), Days of Life (DOL), and Time Since First Nipple feeding (TSFN). Auto-spectral analysis showed 25.55% increase in Bandwidth of suck (bw-su) for a 2-week increase in GA (DOL …

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Effects Of Calcium Changes On Hysteresis In Restitution Of Action Potential Duration, Kathleen Marie Guzman Jan 2009

Effects Of Calcium Changes On Hysteresis In Restitution Of Action Potential Duration, Kathleen Marie Guzman

University of Kentucky Master's Theses

Sudden cardiac death (SCD) is a leading cause of fatalities. Several methods have been developed to predict instability in myocytes which could lead to SCD. The focus of this study was on altering memory in myocytes, i.e. hysteresis in restitution of action potential duration (APD), by differing levels of calcium. Determination of alteration was implemented by using a diastolic interval (DI) control program that implements a sinusoidal change in DI. Plotting APD versus previous DI, i.e. restitution, produces a hysteresis loop. From these hysteresis loops, five parameters were used to determine measures of memory: area, thickness, overall tilt, max delay …

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Regeneration Of Damaged Growth Plate Using Igf-I Plasmid-Releasing Porous Plga Scaffolds, Nirmal Ravi Jan 2009

Regeneration Of Damaged Growth Plate Using Igf-I Plasmid-Releasing Porous Plga Scaffolds, Nirmal Ravi

University of Kentucky Doctoral Dissertations

Growth plate injuries account for 15-30% of long bone fractures in children. About 10% of these result in significant growth disturbances due to formation of a boney bar. If not treated correctly, this can lead to life-lasting consequences of limb length inequalities and angular deformities. Current treatments for growth plate injuries include removal of boney bar and insertion of fat, silicone, bone cement, etc.. This treatment y is inadequate, leaving almost half of these patients with continued deformities. This dissertation reports characterization of a DNA–containing porous poly(lactic-co-glycolic acid) (PLGA) scaffold system, chondrogenesis using insulin-like growth factor I (IGF-I) plasmid-releasing scaffolds …

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Aging And Sleep Stage Effects On Entropy Of Electroencephalogram Signals, Swetha Vennelaganti Jan 2008

Aging And Sleep Stage Effects On Entropy Of Electroencephalogram Signals, Swetha Vennelaganti

University of Kentucky Master's Theses

The aging brain is characterized by alteration in synaptic contacts, which leads to decline of motor and cognitive functions. These changes are reflected in the age related shifts in power spectrum of electroencephalogram (EEG) signals in both wakefulness and sleep. Various non-linear measures have been used to obtain more insights from EEG analysis compared to the conventional spectral analysis. In our study we used Sample Entropy to quantify regularity of the EEG signal. Because elderly subjects arouse from sleep more often than younger subjects, we hypothesized that Entropy of EEG signals from elderly subjects would be higher than that from …

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Functional Dissociation In Frontal And Striatal Areas For Processing Of Positive And Negative Reward Information, Xun Liu, David K. Powell, Hongbin Wang, Brian T. Gold, Christine R. Corbly, Jane E. Joseph Apr 2007

Functional Dissociation In Frontal And Striatal Areas For Processing Of Positive And Negative Reward Information, Xun Liu, David K. Powell, Hongbin Wang, Brian T. Gold, Christine R. Corbly, Jane E. Joseph

Neuroscience Faculty Publications

Reward-seeking behavior depends critically on processing of positive and negative information at various stages such as reward anticipation, outcome monitoring, and choice evaluation. Behavioral and neuropsychological evidence suggests that processing of positive (e.g., gain) and negative (e.g., loss) reward information may be dissociable and individually disrupted. However, it remains uncertain whether different stages of reward processing share certain neural circuitry in frontal and striatal areas, and whether distinct but interactive systems in these areas are recruited for positive and negative reward processing. To explore these issues, we used a monetary decision-making task to investigate the roles of frontal and striatal …

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Dissociation Of Automatic And Strategic Lexical-Semantics: Functional Magnetic Resonance Imaging Evidence For Differing Roles Of Multiple Frontotemporal Regions, Brian T. Gold, David A. Balota, Sara J. Jones, David K. Powell, Charles D. Smith, Anders H. Andersen Jun 2006

Dissociation Of Automatic And Strategic Lexical-Semantics: Functional Magnetic Resonance Imaging Evidence For Differing Roles Of Multiple Frontotemporal Regions, Brian T. Gold, David A. Balota, Sara J. Jones, David K. Powell, Charles D. Smith, Anders H. Andersen

Neuroscience Faculty Publications

Behavioral research has demonstrated three major components of the lexical-semantic processing system: automatic activation of semantic representations, strategic retrieval of semantic representations, and inhibition of competitors. However, these component processes are inherently conflated in explicit lexical-semantic decision tasks typically used in functional magnetic resonance imaging (fMRI) research. Here, we combine the logic of behavioral priming studies and the neurophysiological phenomenon of fMRI priming to dissociate the neural bases of automatic and strategic lexical-semantic processes across a series of three studies. A single lexical decision task was used in all studies, with stimulus onset asynchrony or linguistic relationship between prime and …

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Method And Device For Removal Of Cryoprotectant From Cryopreserved Biological Cells And Tissues, Dayong Gao, Xiangdong Cui Mar 2005

Method And Device For Removal Of Cryoprotectant From Cryopreserved Biological Cells And Tissues, Dayong Gao, Xiangdong Cui

Biomedical Engineering Faculty Patents

Novel methods and devices for removing cryoprotectant from cryoprotectant-containing liquids, and from cells residing therein, are disclosed. In one aspect, the method comprises passing the cryoprotectant-containing liquid through at least one semipermeable hollow fiber membrane contained in a hollow module in a first direction, while passing a liquid which is substantially free of cryoprotectant through the hollow module in a second direction to remove cryoprotectant across a diffusion gradient. In another aspect, a device is described for removing cryoprotectant from a liquid, comprising a hollow module with at least one semipermeable hollow fiber membrane therein for accomplishing such counter-current diffusion …

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Loss Of Sympathetic Control Of Cardiovascular Function Following Spinal Cord Injury, Charles Everett Hogancamp Ii Jan 2004

Loss Of Sympathetic Control Of Cardiovascular Function Following Spinal Cord Injury, Charles Everett Hogancamp Ii

University of Kentucky Master's Theses

Cardiovascular control in the human is significantly impaired after spinal cord injury(SCI) having a direct effect on the sympathetic nervous system (SNS) causing an inability toregulate vasoconstriction below the level of the lesion. The effects of SCI on the two majorcomponents of blood pressure regulation, control of plasma volume and neural control of theheart and peripheral vasculature are poorly understood. In particular, no index to diagnosedisorders to autonomic control of the heart and vasculature has been developed. The presentstudy primarily utilized noninvasively acquired, easily accessible variables that may havepromise as indicators of autonomic activity for assessing the level of autonomic …

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Implant Pre-Treated For Reducing The Generation Of Wear Particulates, David A. Pienkowski, Kwon-Yong Lee Mar 1999

Implant Pre-Treated For Reducing The Generation Of Wear Particulates, David A. Pienkowski, Kwon-Yong Lee

Biomedical Engineering Faculty Patents

A method is provided for reducing the amount of wear particulates generated by a total joint orthopaedic implant. The implant consists of two matched articulating components wherein at least one of the components is made of polymer or other material with similar physical properties. The method includes the steps of placing the total joint orthopaedic implant in a fluid bath and articulating the implant in the fluid bath for at least 1,000 cycles. The articulation may be performed in three stages. In the first, the implant is articulated under a load of substantially 0.1-500 Newtons with sliding speeds of substantially …

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Method For Improving Consolidation Of Powder Resin, David A. Pienkowski, Eric A. Grulke, Robert J. Jacob Sep 1998

Method For Improving Consolidation Of Powder Resin, David A. Pienkowski, Eric A. Grulke, Robert J. Jacob

Biomedical Engineering Faculty Patents

A method for improving consolidation of powder resin is provided. The method broadly includes the steps of: (1) sorting particles of the powder resin according to their diameter; (2) combining the sorted particles having a first diameter D1 with the sorted particles having a second diameter D2 so as to form a particle mixture; (3) applying a vibration to the particle mixture; (4) heating the particle mixture; and (5) delivering the particle mixture through a nozzle or into a mold. The particle diameters D1 and D2 are chosen so that once combined there is optimal close packing of the three-dimensional …

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Multidirectional Ecg Coherent Optimal Timing Of Defibrillation Shocks, Abhijit R. Patwardhan, Fabio M. Leonelli Apr 1998

Multidirectional Ecg Coherent Optimal Timing Of Defibrillation Shocks, Abhijit R. Patwardhan, Fabio M. Leonelli

Biomedical Engineering Faculty Patents

A method for of delivering a defibrillation shock to a heart at an optimal time to stop ventricular fibrillation which involves obtaining an electrocardiogram of a heart in at least two directions, determining a time-coherency of the electrocardiogram based upon each of the at least two directions, and computing a tracking function from the time-coherency. An optimal time to apply a defibrillation shock to the heart is determined by locating a local maximum on the tracking function. The method utilizes spacia characteristics of the ventricular fibrillation. The method can be incorporated into implantable cardioverter defibrillators utilizing existing hardware technology.

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Method For Reducing The Generation Of Wear Particulates From An Implant, David A. Pienkowski, Kwon-Yong Lee Jan 1998

Method For Reducing The Generation Of Wear Particulates From An Implant, David A. Pienkowski, Kwon-Yong Lee

Biomedical Engineering Faculty Patents

A method is provided for reducing the amount of wear particulates generated by a total joint orthopaedic implant. The implant consists of two matched articulating components wherein at least one of the components is made of polymer or other material with similar physical properties. The method includes the steps of placing the total joint orthopaedic implant in a fluid bath and articulating the implant in the fluid bath for at least 1,000 cycles. The articulation may be performed in three stages. In the first, the implant is articulated under a load of substantially 0.1-500 Newtons with sliding speeds of substantially …

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Implant Having Reduced Generation Of Wear Particulates, David A. Pienkowski Dec 1997

Implant Having Reduced Generation Of Wear Particulates, David A. Pienkowski

Biomedical Engineering Faculty Patents

A method is provided for reducing the amount of wear particulates generated by a total joint orthopaedic implant. The implant consists of two matched articulating components. The method includes the steps of placing the total joint orthopaedic implant in a fluid bath and articulating the implant in the fluid bath for at least 1,000 cycles. The articulation may be performed in three stages. In the first, the implant is articulated under a load of substantially 0.1-500 Newtons with sliding speeds of substantially 0.01-0.5 meters per second. During a second stage the articulation takes place under a load of substantially 200-2,500 …

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Method For Reducing The Generation Of Wear Particulates From An Implant, David A. Pienkowski May 1996

Method For Reducing The Generation Of Wear Particulates From An Implant, David A. Pienkowski

Biomedical Engineering Faculty Patents

A method is provided for reducing the amount of wear particulates generated by a total joint orthopaedic implant. The implant consists of two matched articulating components. The method includes the steps of placing the total joint orthopaedic implant in a fluid bath and articulating the implant in the fluid bath for at least 1,000 cycles. The articulation may be performed in three stages. In the first, the implant is articulated under a load of substantially 0.1-500 Newtons with sliding speeds of substantially 0.01-0.5 meters per second. During a second stage the articulation takes place under a load of substantially 200-2,500 …

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Development Of A Biologically Based Aerobic Composting Simulation Model, Dennis P. Stombaugh, Sue E. Nokes Jan 1996

Development Of A Biologically Based Aerobic Composting Simulation Model, Dennis P. Stombaugh, Sue E. Nokes

Biosystems and Agricultural Engineering Faculty Publications

A relatively simple dynamic model based on microbial process kinetics has been developed for aerobic composting. Differential equations describing microbial, substrate, and oxygen concentrations, as well as moisture and temperature profiles have been derived as a function of vessel size and aeration rate. Microbial biomass growth was described using Monod growth kinetics as a function of degradable substrate concentration, oxygen concentration, moisture content, and compost temperature. Facility and fan operating costs have been included to permit economic optimization of the process. Predicted results demonstrated the ability of the model to quantify and describe the influence of multiple interacting factors (temperature, …

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Process For Converting Serial Image To The Sterolithography Apparatus (Sla) Slice File With Automatic Base And Support Generation, Charles F. Knapp, P. L. Charles Fischer, Samuel V. Duplessis Sep 1995

Process For Converting Serial Image To The Sterolithography Apparatus (Sla) Slice File With Automatic Base And Support Generation, Charles F. Knapp, P. L. Charles Fischer, Samuel V. Duplessis

Biomedical Engineering Faculty Patents

Method and apparatus for converting a series of serial section images of an object into a three-dimensional model. The method includes acquiring and storing the series of serial section images, converting, zooming, and interpolating serial section images. The method further includes discriminating the series of serial section images to form a binary image, which is then compressed, and filtered. Further, support data for floating or cantilevered portions of the object and base data are generated, the filtered binary image is translated to produce a plurality of vectors representing pixels of the object, and a three-dimensional model of the object is …

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Dynamic Childbirth Simulator For Teaching Maternity Patient Care, Charles F. Knapp, George S. Eades Jul 1974

Dynamic Childbirth Simulator For Teaching Maternity Patient Care, Charles F. Knapp, George S. Eades

Biomedical Engineering Faculty Patents

A programmable patient simulator for teaching maternity patient care includes a life size manikin with a pelvis, vaginal canal, uterus, placenta, umbilical cord, and a fetal doll from which heart sounds are emitted. A programmable electro-pneumatic system controls the simulated uterine contractions, position of the uterus, rupture of membranes, expulsion of fetal doll, and fetal heart rate during labor and delivery sequence. The invention described herein was made in the course of work under a grant or award from the Department of Health, Education and Welfare.

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Dynamic Childbirth Simulator For Teaching Maternity Patient Care, Charles F. Knapp, George S. Eades Jul 1974

Dynamic Childbirth Simulator For Teaching Maternity Patient Care, Charles F. Knapp, George S. Eades

Biomedical Engineering Faculty Patents

A programmable patient simulator for teaching maternity patient care includes a life size manikin with a pelvis, vaginal canal, uterus, placenta, umbilical cord, and a fetal doll from which heart sounds are emitted. A programmable electro-pneumatic system controls the simulated uterine contractions, position of the uterus, rupture of membranes, expulsion of fetal doll, and fetal heart rate during labor and delivery sequence. The invention described herein was made in the course of work under a grant or award from the Department of Health, Education and Welfare.

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Dynamic Childbirth Simulator For Teaching Maternity Patient Care, Charles F. Knapp, George S. Eades Jul 1974

Dynamic Childbirth Simulator For Teaching Maternity Patient Care, Charles F. Knapp, George S. Eades

Biomedical Engineering Faculty Patents

A programmable patient simulator for teaching maternity patient care includes a life size manikin with a pelvis, vaginal canal, uterus, placenta, umbilical cord, and a fetal doll from which heart sounds are emitted. A programmable electro-pneumatic system controls the simulated uterine contractions, position of the uterus, rupture of membranes, expulsion of fetal doll, and fetal heart rate during labor and delivery sequence. The invention described herein was made in the course of work under a grant or award from the Department of Health, Education and Welfare.

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Dynamic Childbirth Simulator For Teaching Maternity Patient Care, Charles F. Knapp, George S. Eades Mar 1974

Dynamic Childbirth Simulator For Teaching Maternity Patient Care, Charles F. Knapp, George S. Eades

Biomedical Engineering Faculty Patents

A programmable patient simulator for teaching maternity patient care includes a life size manikin with a pelvis, vaginal canal, uterus, placenta, umbilical cord, and a fetal doll from which heart sounds are emitted. A programmable electro-pneumatic system controls the simulated uterine contractions, position of the uterus, rupture of membranes, expulsion of fetal doll, and fetal heart rate during labor and delivery sequence.

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