Engineering Commons^™

A Fractal Art Approach To The Three-Body Problem, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

This preliminary study explores a new search strategy for identifying relatively stable vs. unstable solutions to the planar three-body problem in astrophysics, starting from the perspective of computer-generated art. Here classical Newtonian accelerations, speeds, and positions of all three bodies in a fixed plane are calculated. All three bodies are stationary at time zero, and the fate of the system is classified as reflecting either a bound stable orbit, a likely collision, or the ejection of one body. The initial position of one of the three bodies is varied in the image plane, and the outcome coded as one of …

Quantification Of Intervertebral Disc Strain From High-Resolution Ultrasound Imaging During Dynamic Loading, Diya Sakhrani

Discovery Undergraduate Interdisciplinary Research Internship

High-resolution ultrasound imaging employs high-frequency sound waves that can be used to noninvasively visualize the structures within the body, facilitating medical diagnosis without the need for open surgery. The widespread utilization of ultrasound is attributed to its affordability, non-invasive characteristics, and use of non-ionizing radiation. Nevertheless, ultrasound is prone to artifacts originating from the surrounding environment, gas-liquid interfaces, or dense tissue. These artifacts are common in ultrasound images and can cause dropout, noise, and degraded resolution. In this study we analyzed intervertebral disc (IVD) strain during two axial compression testing cycles of bovine intervertebral discs with a 2-dimensional direct deformation …

Characterizing Intervertebral Disc Strain Under Dynamic Loading Conditions Using Ultrasound Texture Analysis, Radhika Kulkarni

Discovery Undergraduate Interdisciplinary Research Internship

Herniated discs in the spine are a significant patient burden, with potential links to lower back and leg discomfort and a considerable impact on daily life. These discs, located between spinal vertebrae, are comprised of the annulus fibrosus (AF) and the nucleus pulposus (NP). Herniations happen when the NP protrudes through a full-thickness annular tear, possibly compressing spinal nerves. The mechanical factors underlying herniated discs are poorly understood, necessitating research into these mechanisms and accessible diagnostic techniques. Our study employs high-resolution ultrasound and texture correlation to quantify strain patterns in intervertebral discs during dynamic loading.

A motion segment from the …

Scanning Electron Microscopy Analysis Of Murine Renal, Aortic, And Cardiac Tissue, Sarah E. Grev, Luke E. Schepers, Jennifer Anderson, Craig J. Goergen

Discovery Undergraduate Interdisciplinary Research Internship

Scanning electron microscopy (SEM) is a tool that provides detailed insight into objects invisible to the human eye. As the name suggests, an electron beam is used to create an image down to the nanometer scale. The beam focuses on the surface of a sample using lenses in the electron column. In this project, we use SEM to study three types of murine tissue. First, we examine the glomerulus, found in the kidney, that is primarily responsible for filtering blood. Following a left renal vein (LRV) stenosis, SEM is used to observe changes to the glomeruli. Differences in the left …

Methods To Study Activity Dependent Protein Synthesis In Autism Spectrum Disorder, Megan Webb, Karin F K Ejendal, Tamara L. Kinzer-Ursem

Discovery Undergraduate Interdisciplinary Research Internship

It is estimated by the World Health Organization that 1 in 100 children have autism spectrum disorder (ASD), a condition characterized by neurological differences that may impact a person’s learning or behavior. Clinically, ASD symptoms are alleviated with behavioral or pharmacological therapies, however, not all patients respond to these interventions. Deep brain stimulation (DBS) is a promising treatment of Parkinson’s disease that could also be effective in treating ASD. SynGAP1 is a protein involved in neuronal action that is crucial for regulating synaptic plasticity. Mutations in the SYNGAP1 gene causing haploinsufficiency can result in the manifestation of ASD symptoms. This …

Designing A Self-Regulating And Portable Heating Device For A Microfluidic Based Biosensor, Riya Mahajan

Discovery Undergraduate Interdisciplinary Research Internship

Paper-based biosensors are powerful microfluidic analytical devices that are potentially useful for a wide range of applications, ranging from medical diagnostics to agricultural and environmental monitoring. Molecular diagnostics have limitations because they need to send samples back to a centralized laboratory, which increases the cost and turnaround time of the test. This project aims to create a simple-to-use, low-cost, and portable heating system that would facilitate the creation of a field-deployable paper-based analytical device that can incubate the sample at elevated temperatures for conducting isothermal molecular assays. Our design aims to miniaturize a commercial water bath and will be fabricated …

Deep Learning Approach To Improved Image Quality For Medical Diagnostics, Olivia Loesch, Katie Leyba, Halyley Chan, Craig Goergen

Discovery Undergraduate Interdisciplinary Research Internship

The United Nation’s health-related Sustainable Development Goals are difficult to achieve in low- and middle-income countries due to workforce shortages and inadequate health surveillance systems. However, with the growth of artificial intelligence (AI) and computer algorithms, it is possible to apply AI to healthcare technologies to improve progress towards these UN standards. This project aims at using and improving computer algorithms and deep learning to aid in the extraction of important structural and functional information from murine carotid artery ultrasound and photoacoustic images. First, we created a large database of simulated photoacoustic images to optimize the algorithms. These images were …

Model Based Analysis Of The Accuracy And Precision Of Auscultatory Blood Pressure Measurements In Patients With Atrial Fibrillation, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

Accurate measurement of blood pressure in the presence of atrial fibrillation remains an open problem. The present study combines the techniques of stochastic mathematical modeling with physiological models of the systemic circulation, cuff, and arm (1) to explore mechanisms underlying both the lack of accuracy and the lack of precision in cuff-based arterial pressure measurements during atrial fibrillation and (2) to develop strategies to correct for errors. Both the cardiovascular system and the measurement technique are described using mathematics, including both numerical techniques and analytical probability theory. Preliminary results with numerical models suggested that, despite variability, average systolic pressures tend …

Ex Vivo Electrochemical Measurement Of Glutamate Release During Spinal Cord Injury, James K. Nolan, Tran N. H. Nguyen, Mara Fattah, Jessica C. Page, Riyi Shi, Hyowon Lee

Weldon School of Biomedical Engineering Faculty Publications

Excessive glutamate release following traumatic spinal cord injury (SCI) has been associated with exacerbating the extent of SCI. However, the mechanism behind sustained high levels of extracellular glutamate is unclear. Spinal cord segments mounted in a sucrose double gap recording chamber are an established model for traumatic spinal cord injury. We have developed a method to record, with micro-scale printed glutamate biosensors, glutamate release from ex vivo rat spinal cord segments following injury. This protocol would work equally well for similar glutamate biosensors.

Hypothesis Paper: Mechanism For Primary Blast Induced Traumatic Brain Injury With Minimal Head Motion, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

Transit of the human skull by blast waves produces diffuse brain injury. The exact mechanisms are unknown. This paper describes plausible mechanisms in which steep intracranial pressure gradients, demonstrated in prior computational models of blast-skull interaction, produce subsequent deformation and motion of the whole brain within the skull, without obvious movement of the head. Equations of motion are derived to describe the acceleration, velocity, and relative position of both the skull and the brain in response to known extracranial and intracranial pressures both during and several hundred milliseconds after blast wave passage. A finite element model is solved to visualize …

A Simple Mathematical Model For The Nonlinear Compliance Of Arteries, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

No abstract provided.

Brain Motion, Deformation, And Potential Injury During Soccer Heading, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

This paper addresses the problem of what is happening physically inside the skull during head-ball contact. Mathematical models based upon Newton’s laws of motion and numerical methods are used to create animations of brain motion and deformation inside the skull.

Initially a 1 cm gap filled with cerebrospinal fluid (CSF) separates the brain from the rigid skull in adults and older children. Whole head acceleration induces a pulse of artificial gravity within the skull. Because brain density differs slightly from that of CSF, the brain accelerates and strikes the inner aspect of the skull, undergoing viscoelastic deformation, ranging from 1 …

New Fractals For Computer Generated Art Created By Iteration Of Polynomial Functions Of A Complex Variable, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

Novel fractal forms can be created by iteration of higher order polynomials of the complex variable, z, with both positive and negative exponents, followed by optional integer power transformation, k zz . Such functions lead to an expanded universe of fascinating fractal patterns that can be incorporated into computer generated art.

Generalized Fractals For Computer Generated Art: Preliminary Results, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

This paper explores new types of fractals created by iteration of the functions xn+1 = f1(xn, yn) and yn+1 = f2(xn, yn) in a general plane, rather than in the complex plane. Iteration of such functions generates orbits with novel fractal patterns. Especially interesting are N-th order polynomials, raised to a positive or negative integer power, p.

Such functions create novel fractal patterns, including budding, spiked, striped, dragon head, and bat-like forms. The present faculty working paper shows how to create a rich variety of complex and fascinating fractals using this generalized approach, which is accessible to students with high …

An Automated Workflow For Quantifying Rna Transcripts In Individual Cells In Large Data-Sets, Matthew C. Pharris, Tzu-Ching Wu, Xinping Chen, Xu Wang, David M. Umulis, Vikki M. Weake, Tamara L. Kinzer-Ursem

Weldon School of Biomedical Engineering Faculty Publications

Advanced molecular probing techniques such as single molecule fluorescence in situ hybridization (smFISH) or RNAscope can be used to assess the quantity and spatial location of mRNA transcripts within cells. Quantifying mRNA expression in large image sets usually involves automated counting of fluorescent spots. Though conventional spot counting algorithms may suffice, they often lack high-throughput capacity and accuracy in cases of crowded signal or excessive noise. Automatic identification of cells and processing of many images is still a challenge. We have developed a method to perform automatic cell boundary identification while providing quantitative data about mRNA transcript levels across many …

Biomechanics Of Snoring And Sleep Apnea, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

To understand the mechanisms of snoring and sleep apnea a first-principles biomechanical analysis was done for airflow through branched parallel channels, separated by a freely movable soft palate, and converging to a common channel at the base of the tongue in a “Y-shaped” configuration. Branches of the Y describe slit-like passages on the nasal and oral sides of the soft palate, when the palate is pushed by backward movement of the tongue to form a wedge between the tongue surface and the posterior pharyngeal wall. The common channel of the Y describes the oropharyngeal passage between the base of the …

Valveless Pumping: The Reflected Pulse Wave Hypothesis, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

No abstract provided.

Meta-Analysis Of Studies On Cpr: A Better Route To New Practice Guidelines, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

Quantitative synthesis of research results multiple small clinical trials using the statistical techniques of meta-analysis yields conclusions in excellent agreement with large randomized “mega-trails”. The present paper introduces a simple yet powerful method of meta-analysis for combining results of any published studies of a proposed treatment compared with a suitable control. These may include pre-clinical or clinical models generating either continuous or dichotomous data.

Local Probability Based Transformations And Diagonal Projection: A New Support Vector Machine-Like Method For Classification Of Feature Vectors, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

No abstract provided.

Increased Risk Of Children For Subtle Closed Head Injury From Soccer Heading, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

No abstract provided.

Development Of A Mathematical Model To Estimate Intra-Tumor Oxygen Concentrations Through Multi-Parametric Imaging, Chung-Wein Lee, Keith Stantz, Phd

School of Health Sciences Faculty Publications

Background

Tumor hypoxia is involved in every stage of solid tumor development: formation, progression, metastasis, and apoptosis. Two types of hypoxia exist in tumors—chronic hypoxia and acute hypoxia. Recent studies indicate that the regional hypoxia kinetics is closely linked to metastasis and therapeutic responses, but regional hypoxia kinetics is hard to measure. We propose a novel approach to determine the local pO2 by fusing the parameters obtained from in vivo functional imaging through the use of a modified multivariate Krogh model.

Methods

To test our idea and its potential to translate into an in vivo setting through the use of …

A Potential New Technique To Estimate The Origins Of Focal Atrial Tachycardias From 12-Lead Electrocardiograms, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Background: This brief report presents a potential new technique for locating the sites of origin of focal atrial tachycardias from standard 12-lead electrocardiograms. Methods: Estimated P wave vector coordinates are derived from leads I, aVF, V1 and V2, and mapped to a three dimensional coordinate system in space. A simple graphical method is used to find the back projection of the P wave vector onto the surface of atrial muscle to estimate the most likely site of origin of the tachycardia. Results: Graphical back projection correctly identified foci of atrial tachycardias in 19 of 19 cases described in the most …

Β-Aminopropionitrile-Induced Reduction In Enzymatic Crosslinking Causes In Vitro Changes In Collagen Morphology And Molecular Composition, Silvia P. Canelón, Joseph M. Wallace

Weldon School of Biomedical Engineering Graduate Student Publications

Type I collagen morphology can be characterized using fibril D-spacing, a metric which describes the periodicity of repeating bands of gap and overlap regions of collagen molecules arranged into collagen fibrils. This fibrillar structure is stabilized by enzymatic crosslinks initiated by lysyl oxidase (LOX), a step which can be disrupted using β-aminopropionitrile (BAPN). Murine in vivo studies have confirmed effects of BAPN on collagen nanostructure and the objective of this study was to evaluate the mechanism of these effects in vitro by measuring D-spacing, evaluating the ratio of mature to immature crosslinks, and quantifying gene expression of type I collagen …

Biomechanics Of Retinal Venous Pulsations As Indicators Of Intracranial Pressure, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

The origin of retinal venous pulsations remains an open problem in physiology and medicine; so too, their exact relationship to intracranial pressure. This study takes a mathematical modeling approach to explore details of blood flow through the eye to reveal the mechanism of pulsations. The intravaginal, intraneural, and intraocular segments of the retinal arteries and veins are modeled as connected resistive-capacitive segments. The analysis incorporates two critical mechanical properties of these small blood vessels, not heretofore studied, which become significant under conditions of negative transmural pressures: (1) dramatically reduced compliance during flattening and (2) cross-sectional shape change as internal volume …

Optimizing Strategies For Population-Based Chlamydia Infection Screening Among Young Women: An Age-Structured System Dynamics Approach Infectious Disease Epidemiology, Yu Teng, Nan Kong, Wanzhu Tu

Weldon School of Biomedical Engineering Faculty Publications

Background

Chlamydia infection (CT) is one of the most commonly reported sexually transmitted diseases. It is often referred to as a “silent” disease with the majority of infected people having no symptoms. Without early detection, it can progress to serious reproductive and other health problems. Economical identification of asymptomatically infected is a key public health challenge. Increasing evidence suggests that CT infection risk varies over the range of adolescence. Hence, age-dependent screening strategies with more frequent testing for certain age groups of higher risk may be cost-saving in controlling the disease.

Methods

We study the optimization of age-dependent screening strategies …

The Origin Of Korotkoff Sounds And The Accuracy Of Auscultatory Blood Pressure Measurements, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

This study explores the hypothesis that the sharper, high frequency Korotkoff sounds come from resonant motion of the arterial wall, which begins after the artery transitions from a buckled state to an expanding state. The motion of one mass, two nonlinear springs, and one damper, driven by transmural pressure under the cuff, are used to model and compute the Korotkoff sounds according to principles of classical Newtonian physics. The natural resonance of this spring-mass-damper system provides a concise, yet rigorous, explanation for the origin of Korotkoff sounds. Fundamentally, wall stretching in expansion requires more force than wall bending in buckling. …

Ontogenetic Scaling Patterns And Functional Anatomy Of The Pelvic Limb Musculature In Emus (Dromaius Novaehollandiae), Luis P. Lamas, Russell P. Main, John R. Hutchinson

Department of Basic Medical Sciences Faculty Publications

Emus (Dromaius novaehollandiae) are exclusively terrestrial, bipedal and cursorial ratites with some similar biomechanical characteristics to humans. Their growth rates are impressive, as their body mass increases eighty-fold from hatching to adulthood whilst maintaining the same mode of locomotion throughout life. These ontogenetic characteristics stimulate biomechanical questions about the strategies that allow emus to cope with their rapid growth and locomotion, which can be partly addressed via scaling (allometric) analysis of morphology. In this study we have collected pelvic limb anatomical data (muscle architecture, tendon length, tendon mass and bone lengths) and calculated muscle physiological cross sectional area …

Noninvasive Measurement Of Cardiac Stroke Volume Using Pulse Wave Velocity And Aortic Dimensions: A Simulation Study, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Background: Concerns about the cost-effectiveness of invasive hemodynamic monitoring in critically ill patients using pulmonary artery catheters motivate a renewed search for effective noninvasive methods to measure stroke volume. This paper explores a new approach based on noninvasively measured pulse wave velocity, pulse contour, and ultrasonically determined aortic cross sectional area. Methods: The Bramwell-Hill equation relating pulse wave velocity to aortic compliance is applied. At the time point on the noninvasively measured pulse contour, denoted th, when pulse amplitude has fallen midway between systolic and diastolic values, the portion of stroke volume remaining in the aorta, and in turn the …

A Compact Theory Of Magnetic Nerve Stimulation: Predicting How To Aim, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Background: A compact theory that predicts quantitatively when and where magnetic neurostimulation will occur is needed as a guide to therapy, ideally providing a single equation that defines the target volume of tissue excited by single or dual coils. Methods: A first-principles analysis of magnetic stimulation incorporating a simplified description of electromagnetic fields and a simplified cable theory of the axon yields a mathematical synthesis predicting how to aim. Results: Nerve stimulation produced by a single circular coil having one or more closely packed turns occurs in donut shaped volume of tissue beneath the coil. Axons spanning several millimeters are …

Choosing Inclusion Criteria That Minimize The Time And Cost Of Clinical Trials, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

AIM: To present statistical tools to model and optimize the cost of a randomized clinical trial as a function of the stringency of patient inclusion criteria. METHODS: We consider a two treatment, dichotomous outcome trial that includes a proportion of patients who are strong responders to the tested intervention. Patients are screened for inclusion using an arbitrary number of test results that are combined into an aggregate suitability score. The screening score is regarded as a diagnostic test for the responsive phenotype, having a specific cutoff value for inclusion and a particular sensitivity and specificity. The cutoff is a measure …