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Structure-function study of N-isopropylacrylamide copolymers with enzyme degradable GAPGLF and GAPGLL side chains

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With an increased demand for more enzyme-sensitive, bioresorbable and more biodegradable polymers, various studies of copolymers have been developed. Polymers are widely used in various applications of biomedical engineering such as in tissue engineering, drug delivery and wound healing. Depending

With an increased demand for more enzyme-sensitive, bioresorbable and more biodegradable polymers, various studies of copolymers have been developed. Polymers are widely used in various applications of biomedical engineering such as in tissue engineering, drug delivery and wound healing. Depending on the conditions in which polymers are used, they are modified to accommodate a specific need. For instance, polymers used in drug delivery are more efficient if they are biodegradable. This ensures that the delivery system does not remain in the body after releasing the drug. It is therefore crucial that the polymer used in the drug system possess biodegradable properties. Such modification can be done in different ways including the use of peptides to make copolymers that will degrade in the presence of enzymes. In this work, we studied the effect of a polypeptide GAPGLL on the polymer NIPAAm and compare with the previously studied Poly(NIPAAm-co-GAPGLF). Both copolymers Poly(NIPAAm-co-GAPGLL) were first synthesized from Poly(NIPAAm-co-NASI) through nucleophilic substitution by the two peptides. The synthesis of these copolymers was confirmed by 1H NMR spectra and through cloud point measurement, the corresponding LCST was determined. Both copolymers were degraded by collagenase enzyme at 25 ° C and their 1H NMR spectra confirmed this process. Both copolymers were cleaved by collagenase, leading to an increase in solubility which yielded a higher LCST compared to before enzyme degradation. Future studies will focus on evaluating other peptides and also using other techniques such as Differential Scanning Microcalorimetry (DSC) to better observe the LCST behavior. Moreover, enzyme kinetics studies is also crucial to evaluate how fast the enzyme degrades each of the copolymers.

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2018-05

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Dynamic Changes in Heart Rate and Cerebral Blood Flow During Acute Vagal Nerve Stimulation

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Vagal Nerve Stimulation (VNS) has been shown to be a promising therapeutic technique in treating many neurological diseases, including epilepsy, stroke, traumatic brain injury, and migraine headache. The mechanisms by which VNS acts, however, are not fully understood but may

Vagal Nerve Stimulation (VNS) has been shown to be a promising therapeutic technique in treating many neurological diseases, including epilepsy, stroke, traumatic brain injury, and migraine headache. The mechanisms by which VNS acts, however, are not fully understood but may involve changes in cerebral blood flow. The vagus nerve plays a significant role in the regulation of heart rate and cerebral blood flow that are altered during VNS. Here, we examined the effects of acute vagal nerve stimulation on both heart rate and cerebral blood flow. Laser Speckle Contrast Analysis (LASCA) was used to analyze the cerebral blood flow of male Long\u2014Evans rats. Results showed two distinct patterns of responses whereby animals either experienced a mild or severe decrease in heart rate during VNS. Further, animals that displayed mild heart rate decreases showed an increase in cerebral blood flow that persisted beyond VNS. Animals that displayed severe decreases showed a transient decrease in cerebral blood flow followed by an increase that was greater than that observed in mild animals but progressively decreased after VNS. The results suggest two distinct patterns of changes in both heart rate and cerebral blood flow that may be related to the intensity of VNS.

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2018-05

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Image Analysis for Registration, Segmentation, and Intensity Measurement of 2-Photon Microscope Images using MATLAB

Description

Traumatic brain injury (TBI) is a major concern in public health due to its prevalence and effect. Every year, about 1.7 million TBIs are reported [7]. According to the According to the Centers for Disease Control and Prevention (CDC), 5.5%

Traumatic brain injury (TBI) is a major concern in public health due to its prevalence and effect. Every year, about 1.7 million TBIs are reported [7]. According to the According to the Centers for Disease Control and Prevention (CDC), 5.5% of all emergency department visits, hospitalizations, and deaths from 2002 to 2006 are due to TBI [8]. The brain's natural defense, the Blood Brain Barrier (BBB), prevents the entry of most substances into the brain through the blood stream, including medicines administered to treat TBI [11]. TBI may cause the breakdown of the BBB, and may result in increased permeability, providing an opportunity for NPs to enter the brain [3,4]. Dr. Stabenfeldt's lab has previously established that intravenously injected nanoparticles (NP) will accumulate near the injury site after focal brain injury [4]. The current project focuses on confirmation of the accumulation or extravasation of NPs after brain injury using 2-photon microscopy. Specifically, the project used controlled cortical impact injury induced mice models that were intravenously injected with 40nm NPs post-injury. The MATLAB code seeks to analyze the brain images through registration, segmentation, and intensity measurement and evaluate if fluorescent NPs will accumulate in the extravascular tissue of injured mice models. The code was developed with 2D bicubic interpolation, subpixel image registration, drawn dimension segmentation and fixed dimension segmentation, and dynamic image analysis. A statistical difference was found between the extravascular tissue of injured and uninjured mouse models. This statistical difference proves that the NPs do extravasate through the permeable cranial blood vessels in injured cranial tissue.

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2018-05

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Optical Feedback Mechanism for Detecting Cerebrospinal Fluid Leaks During Spinal Surgery

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For my honors thesis, I developed a proof of concept alpha prototype of a biomedical device for detection of cerebrospinal fluid leaks during spinal surgery. Cerebrospinal fluid leaks are a consequence of tears in the dura mater of the spinal

For my honors thesis, I developed a proof of concept alpha prototype of a biomedical device for detection of cerebrospinal fluid leaks during spinal surgery. Cerebrospinal fluid leaks are a consequence of tears in the dura mater of the spinal cord and can result in potentially life-threatening conditions and are overall a large burden not only on the patient but upon the clinical teams managing the patient postoperatively. What I created was an optical sensor that I programmed to be sensitive to detecting green wavelength light. The device would ideally be attached to surgical drain tubing and used in conjunction with fluorescein (a green fluorescent dye) infused lumbar punctures into the spinal canal of patients. As the dye circulates through the spinal cord, any tears in the dura mater would cause the fluorescein to leak out with cerebrospinal fluid into the incision site. This fluid may then be collected by the surgical drain where the sensor may detect the fluorescein, triggering a buzzer response that would notify the patient or the surgeons of an ongoing leak that requires repair. The time I spent on my thesis involved sensor validation to ensure it could differentiate between colors, testing the sensor's color sensitivity by performing a fluorescein aliquot, and running proof of concept testing that could show the sensor can detect fluorescein drain tubing and provide an adequate response. The sensor was able to differentiate between varying concentrations of fluorescein in solution and provided exceptional results in its proof-of-concept testing. Next steps will be to re-run the sensor validation study with different dyes as well as consolidating the device's electrical hardware onto a single circuit board as development of beta and gamma prototypes move forward.

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2018-05

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Can Startle Elicit Sequential Movements in Highly Trained Individuals?

Description

Most daily living tasks consist of pairing a series of sequential movements, e.g., reaching to a cup, grabbing the cup, lifting and returning the cup to your mouth. The process by which we control and mediate the smooth progression of

Most daily living tasks consist of pairing a series of sequential movements, e.g., reaching to a cup, grabbing the cup, lifting and returning the cup to your mouth. The process by which we control and mediate the smooth progression of these tasks is not well understood. One method which we can use to further evaluate these motions is known as Startle Evoked Movements (SEM). SEM is an established technique to probe the motor learning and planning processes by detecting muscle activation of the sternocleidomastoid muscles of the neck prior to 120ms after a startling stimulus is presented. If activation of these muscles was detected following a stimulus in the 120ms window, the movement is classified as Startle+ whereas if no sternocleidomastoid activation is detected after a stimulus in the allotted time the movement is considered Startle-. For a movement to be considered SEM, the activation of movements for Startle+ trials must be faster than the activation of Startle- trials. The objective of this study was to evaluate the effect that expertise has on sequential movements as well as determining if startle can distinguish when the consolidation of actions, known as chunking, has occurred. We hypothesized that SEM could distinguish words that were solidified or chunked. Specifically, SEM would be present when expert typists were asked to type a common word but not during uncommon letter combinations. The results from this study indicated that the only word that was susceptible to SEM, where Startle+ trials were initiated faster than Startle-, was an uncommon task "HET" while the common words "AND" and "THE" were not. Additionally, the evaluation of the differences between each keystroke for common and uncommon words showed that Startle was unable to distinguish differences in motor chunking between Startle+ and Startle- trials. Explanations into why these results were observed could be related to hand dominance in expert typists. No proper research has been conducted to evaluate the susceptibility of the non-dominant hand's fingers to SEM, and the results of future studies into this as well as the results from this study can impact our understanding of sequential movements.

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2018-05

Biomedical Engineering Workforce Competencies for 21st Century Healthcare Technology Product Development Teams: A BME Student Cohort Perspective

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The importance of efficient design and development teams in in 21st century is evident after the compressive literate review was performed to digest various aspects of benefits and foundation of teamwork. Although teamwork may have variety of applications in many

The importance of efficient design and development teams in in 21st century is evident after the compressive literate review was performed to digest various aspects of benefits and foundation of teamwork. Although teamwork may have variety of applications in many different industries, the new emerging biomedical engineering is growing significantly using principles of teamwork. Studying attributes and mechanism of creating successful biomedical engineering teams may even contribute more to the fast paste growth of this industry. In comprehensive literate review performed, general importance of teamwork was studied. Also specific hard and soft attributes which may contribute to teamwork was studied. Currently, there are number of general assessment tools which assists managements in industry and academia to systematically bring qualified people together to flourish their talents and skills as members of a biomedical engineering teams. These assessment tools, although are useful, but are not comprehensive, incorporating literature review attributes, and also doesn't not contain student perspective who have experience as being part of a design and development team. Although there are many scientific researches and papers designated to this matter, but there is no study which purposefully studies development of an assessment tool which is designated to biomedical engineering workforce and is constructed of both literature, current assessment tools, and also student perspective. It is hypothesized that a more comprehensive composite assessment tool that incorporate both soft and hard team attributes from a combined professional and student perspective could be implemented in the development of successful Biomedical Engineering Design and Development teams and subsequently used in 21st century workforce.

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2017-05

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Analyzing rat sciatic nerve fibers under various electrical stimuli

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Abstract Modern imaging techniques for sciatic nerves often use imaging techniques that can clearly find myelinated axons (Group A and Group B and analyze their properties, but have trouble with the more numerous Remak Fibers (Group C). In this paper,

Abstract Modern imaging techniques for sciatic nerves often use imaging techniques that can clearly find myelinated axons (Group A and Group B and analyze their properties, but have trouble with the more numerous Remak Fibers (Group C). In this paper, Group A and B fibers are analyzed while also analyzing Remak fibers using osmium tetroxide staining and imaging with the help of transmission electron microscopy. Using this method, nerves had various electrical stimuli attached to them and were analyzed as such. They were analyzed with a cuff electrode attached, a stimulator attached, and both, with images taken at the center of the nerve and the ends of them. The number and area taken by the Remak fibers were analyzed, along with the g-ratios of the Group A and B fibers. These were analyzed to help deduce the overall health of the fibers along with vacuolization, and mitochondria available. While some important information was gained from this evaluation, further testing has to be done to improve the myelin detection system, along with analyzing the proper and necessary Remak fibers and the role they play. The research tries to thoroughly look at the necessary material and find a way to use it as a guide to further experimentation with electrical stimuli, and notes the differences found within and without various groups, various points of observation, and various stimuli as a whole. Nevertheless, this research allows a strong look into the benefits of transmission electron microscopy and the ability to assess electrical stimulation from these points.

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2018-05

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The Ethics of Brain-Computer Interfaces

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The development of computational systems known as brain-computer interfaces (BCIs) offers the possibility of allowing individuals disabled by neurological disorders such as Amyotrophic Lateral Sclerosis (ALS) and ischemic stroke the ability to perform relatively complex tasks such as communicating with

The development of computational systems known as brain-computer interfaces (BCIs) offers the possibility of allowing individuals disabled by neurological disorders such as Amyotrophic Lateral Sclerosis (ALS) and ischemic stroke the ability to perform relatively complex tasks such as communicating with others and walking. BCIs are closed-loop systems that record physiological signals from the brain and translate those signals into commands that control an external device such as a wheelchair or a robotic exoskeleton. Despite the potential for BCIs to vastly improve the lives of almost one billion people, one question arises: Just because we can use brain-computer interfaces, should we? The human brain is an embodiment of the mind, which is largely seen to determine a person's identity, so a number of ethical and philosophical concerns emerge over current and future uses of BCIs. These concerns include privacy, informed consent, autonomy, identity, enhancement, and justice. In this thesis, I focus on three of these issues: privacy, informed consent, and autonomy. The ultimate purpose of brain-computer interfaces is to provide patients with a greater degree of autonomy; thus, many of the ethical issues associated with BCIs are intertwined with autonomy. Currently, brain-computer interfaces exist mainly in the domain of medicine and medical research, but recently companies have started commercializing BCIs and providing them at affordable prices. These consumer-grade BCIs are primarily for non-medical purposes, and so they are beyond the scope of medicine. As BCIs become more widespread in the near future, it is crucial for interdisciplinary teams of ethicists, philosophers, engineers, and physicians to collaborate to address these ethical concerns now before BCIs become more commonplace.

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2016-05

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The Role of Precision Grip Aperture in Hardness Differentiation of Cube-Like Objects

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Determining the characteristics of an object during a grasping task requires a combination of mechanoreceptors in the muscles and fingertips. The width of a person's finger aperture during the grasp may affect the accuracy of how that person determines hardness,

Determining the characteristics of an object during a grasping task requires a combination of mechanoreceptors in the muscles and fingertips. The width of a person's finger aperture during the grasp may affect the accuracy of how that person determines hardness, as well. These experiments aim to investigate how an individual perceives hardness amongst a gradient of varying hardness levels. The trend in the responses is assumed to follow a general psychometric function. This will provide information about subjects' abilities to differentiate between two largely different objects, and their tendencies towards guess-chances upon the presentation of two similar objects. After obtaining this data, it is then important to additionally test varying finger apertures in an object-grasping task. This will allow an insight into the effect of aperture on the obtained psychometric function, thus ultimately providing information about tactile and haptic feedback for further application in neuroprosthetic devices. Three separate experiments were performed in order to test the effect of finger aperture on object hardness differentiation. The first experiment tested a one-finger pressing motion among a hardness gradient of ballistic gelatin cubes. Subjects were asked to compare the hardness of one cube to another, which produced the S-curve that accurately portrayed the psychometric function. The second experiment utilized the Phantom haptic device in a similar setup, using the precision grip grasping motion, instead. This showed a more linear curve; the percentage reported harder increased as the hardness of the second presented cube increased, which was attributed to both the experimental setup limitations and the scale of the general hardness gradient. The third experiment then progressed to test the effect of three finger apertures in the same experimental setup. By providing three separate testing scenarios in the precision grip task, the experiment demonstrated that the level of finger aperture has no significant effect on an individual's ability to perceive hardness.

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2015-05

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Startle can evoke individuated movements of the fingers; implications for neural control

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Startle-evoked-movement (SEM), the involuntary release of a planned movement via a startling stimulus, has gained significant attention recently for its ability to probe motor planning as well as enhance movement of the upper extremity following stroke. We recently showed that

Startle-evoked-movement (SEM), the involuntary release of a planned movement via a startling stimulus, has gained significant attention recently for its ability to probe motor planning as well as enhance movement of the upper extremity following stroke. We recently showed that hand movements are susceptible to SEM. Interestingly, only coordinated movements of the hand (grasp) but not individuated movements of the finger (finger abduction) were susceptible. It was suggested that this resulted from different neural mechanisms involved in each task; however it is possible this was the result of task familiarity. The objective of this study was to evaluate a more familiar individuated finger movement, typing, to determine if this task was susceptible to SEM. We hypothesized that typing movements will be susceptible to SEM in all fingers. These results indicate that individuated movements of the fingers are susceptible to SEM when the task involves a more familiar task, since the electromyogram (EMG) latency is faster in SCM+ trials compared to SCM- trials. However, the middle finger does not show a difference in terms of the keystroke voltage signal, suggesting the middle finger is less susceptible to SEM. Given that SEM is thought to be mediated by the brainstem, specifically the reticulospinal tract, this suggest that the brainstem may play a role in movements of the distal limb when those movements are very familiar, and the independence of each finger might also have a significant on the effect of SEM. Further research includes understanding SEM in fingers in the stroke population. The implications of this research can impact the way upper extremity rehabilitation is delivered.

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2016-12