Biomedical Engineering and Bioengineering Commons^™

Automatic Exposure Control And Estimation Of Effective System Noise In Diffuse Fluorescence Tomography, Dax L. Kepshire, Hamid Dehghani, Frederic Leblond, Brian W. Pogue

Dartmouth Scholarship

A diffuse fluorescence tomography system, based upon time-correlated single photon counting, is presented with an automated algorithm to allow dynamic range variation through exposure control. This automated exposure control allows the upper and lower detection levels of fluorophore to be extended by an order of magnitude beyond the previously published performance and benefits in a slight decrease in system effective noise. The effective noise level is used as a metric to characterize the system performance, integrating both model-mismatch and calibration bias errors into a single parameter. This effective error is near 7% of the reconstructed fluorescent yield value, when imaging …

Development Of The Mask Scentometer, A Comparison Of Ambient Odor Assessment Methods, And Their Application In Ground Truthing Atmospheric Dispersion Models, Christopher G. Henry

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

This dissertation is organized as four stand-alone papers. Paper No. 1 describes the development of the Mask Scentometer and reports dilution ratios measured during use by twelve different people. Dilution ratios at the Mask Scentometer’s five dilution-to-threshold (D/T) settings were found to be 0.35, 1, 2, 4.5 and 18. In Paper No.’s 2 and 4, ambient odor assessment methods were compared in both controlled laboratory conditions and in the field. Laboratory analysis of ambient air samples using dynamic triangular forced-choice olfactometry (DTFCO) did not correlate well with any of the ambient odor assessment methods. Average intensity-predicted D/T was roughly five …

Responses To “Comment On ‘Response To Plevin: Implications For Life Cycle Emissions Regulations’” And “Assessing Corn Ethanol: Relevance And Responsibility”, Adam Liska, Kenneth Cassman

Adam Liska Papers

This letter responds to two issues concerning the greenhouse gas (GHG) emissions intensity of corn-ethanol that were raised in discussions of our response (Liska and Cassman 2009) to Plevin’s article (2009), which critiques our original research (Liska et al. 2009) published in the Journal of Industrial Ecology. ... The suggestion by Anex and Lifset (2009) that corn-ethanol does not reduce GHG emissions by 47% compared to gasoline, but instead by “somewhere between” 35 to 40%, is unsubstantiated.

Extraction And Characterization Of Natural Cellulose Fibers From Common Milkweed Stems, Narendra Reddy, Yiqi Yang

Biological Systems Engineering: Papers and Publications

Natural cellulose fibers with cellulose content, strength, and elongation higher than that of milkweed floss and between that of cotton and linen have been obtained from the stems of common milkweed plants. Although milkweed floss is a unique natural cellulose fiber with low density, the short length and low elongation make milkweed floss unsuitable as a textile fiber. The possibility of using the stems of milkweed plant as a source for natural cellulose fibers was explored in this research. Natural cellulose fibers extracted from milkweed stems have been characterized for their composition, structure, and properties. Fibers obtained from milkweed stems …

On Coupling A Lumped Parameter Heart Model And A Three-Dimensional Finite Element Aorta Model, H. J. Kim, Irene E. Vignon-Clementel, C. A. Figueroa, John F. Ladisa, K. E. Jansen, Jeffrey A. Feinstein, Charles A. Taylor

Biomedical Engineering Faculty Research and Publications

Aortic flow and pressure result from the interactions between the heart and arterial system. In this work, we considered these interactions by utilizing a lumped parameter heart model as an inflow boundary condition for three-dimensional finite element simulations of aortic blood flow and vessel wall dynamics. The ventricular pressure–volume behavior of the lumped parameter heart model is approximated using a time varying elastance function scaled from a normalized elastance function. When the aortic valve is open, the coupled multidomain method is used to strongly couple the lumped parameter heart model and three-dimensional arterial models and compute ventricular volume, ventricular pressure, …

Comparison Of Cumulative Planimetry Versus Manual Dissection To Assess Experimental Infarct Size In Isolated Hearts, Matthias L. Riess, Samhita S. Rhodes, David F. Stowe, Mohammed Aldakkak, Amadou K.S. Camara

Biomedical Engineering Faculty Research and Publications

Introduction

Infarct size (IS) is an important variable to estimate cardiac ischemia/reperfusion injury in animal models. Triphenyltetrazolium chloride (TTC) stains viable cells red while leaving infarcted cells unstained. To quantify IS, infarcted and non-infarcted tissue is often manually dissected and weighed (IS-DW). An alternative is to measure infarcted areas by cumulative planimetry (IS-CP).

Methods

We prospectively compared these two methods in 141 Langendorff-prepared guinea pig hearts (1.44 ± 0.02 g) that were part of different studies on mechanisms of cardioprotection. Hearts were perfused with Krebs–Ringer's and subjected to 30 min global ischemia after various cardioprotective treatments. Two hours after reperfusion …

Exploiting Multiple Sensory Modalities In Brain-Machine Interfaces, Aaron J. Suminski, Dennis C. Tkach, Nicholas G. Hatsopoulos

Biomedical Engineering Faculty Research and Publications

Recent improvements in cortically-controlled brain-machine interfaces (BMIs) have raised hopes that such technologies may improve the quality of life of severely motor-disabled patients. However, current generation BMIs do not perform up to their potential due to the neglect of the full range of sensory feedback in their strategies for training and control. Here we confirm that neurons in the primary motor cortex (MI) encode sensory information and demonstrate a significant heterogeneity in their responses with respect to the type of sensory modality available to the subject about a reaching task. We further show using mutual information and directional tuning analyses …

Characterisation And Mechanical Testing Of Hydrothermally Treated Ha/Zro2 Composites, D. J. Curran, T. J. Fleming, G. Kawachi, C. Ohtsuki, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Hydrothermal treatment is traditionally employed to improve the sinterability of powder compacts by reducing porosity and increasing apparent density. The effect of hydrothermal treatment on green powder compacts has been assessed in order to better understand how treatment may affect the sinter ability of the bodies. Laboratory synthesized nano sized hydroxyapatite (HA) and a commercial zirconia (ZrO₂) powder have been ball milled together to create composite mixtures containing 0-5 wt% ZrO₂ loadings. Disc shaped bodies have been formed using uniaxial and subsequent isostatic pressure. The resultant coherent samples were subjected to hydrothermal treatment at either 120 or …

Fabrication Of Spherical Cao-Sro-Zno-Sio2 Particles By Sol-Gel Processing, Ill Yong Kim, Mark R. Towler, Anthony Wren, Chikara Ohtsuki

Chemical and Biochemical Engineering Faculty Research & Creative Works

This study was concerned with the fabrication of ceramic CaO-SrO-ZnO-SiO₂ spherical particles, which are novel candidates for the glass phase in glass polyalkenoate cements (GPCs). GPCs made from these glasses have potential as bone cements because, unlike conventional GPCs, they do not contain aluminum ions, which inhibit the calcification of hydroxyapatite in the body. The glass phase of GPCs require a controllable glass morphology and particle size distribution. Sol-gel processing can potentially be used to fabricate homogenous ceramic particles with controlled morphology. However, a thorough study on preparation conditions of spherical CaO-SrO-ZnO-SiO₂ particles by sol-gel processing has, to …

Analysis Of Γ-Irradiated Synthetic Bone Grafts By ²⁹Si Mas-Nmr Spectroscopy, Calorimetry And Xrd, D. Boyd, S. Murphy, Mark R. Towler, A. W. Wren, S. Hayakawa

Chemical and Biochemical Engineering Faculty Research & Creative Works

Ca-Sr-Zn-Si glasses have demonstrated excellent biocompatibility both in vitro using the MTT assay with L929 mouse fibroblast cells, and in vivo using healthy and ovariectomized female Wistar rats. However, the biological evaluation of the materials was performed on glass granules that were autoclaved, rather than γ-irradiated; the sterilisation procedure required prior to implantation of these materials in the human body. Given the fact that when a glass is exposed to ionizing radiation changes in its physical properties can take place, it is imperative to determine whether the structure of such glasses will be altered as a result of exposure to …

Compliance Calibration For Fracture Testing Of Anisotropic Biological Materials, J. A. Creel, S. M. Stover, R. B. Martin, D. P. Fyhrie, S. J. Hazelwood, J. C. Gibeling

Biomedical Engineering

The compliance technique has been used to monitor crack length during fracture and fatigue testing of materials. Difficulties arise when this technique is applied to anisotropic biological materials such as bone. In this tutorial, two different methods of analyzing compliance calibration data are described: the standard ASTM method and a new approach developed by the authors specifically for anisotropic materials. An example is given showing how data from equine cortical bone can be analyzed. In this example, calibration tests were conducted on thirty-six three point bend specimens machined from the middiaphysis of six pairs of equine third metacarpal bones. Cracks …

Material Properties Are Related To Stress Fracture Callus And Porosity Of Cortical Bone Tissue At Affected And Unaffected Sites, Rachel C. Entwistle,, Sara C. Sammons, Robert F. Bigley, Scott J. Hazelwood, David P. Fyhrie, Jeffery C. Gibeling, Susan M. Stover

Biomedical Engineering

Stress fractures are overuse injuries of bone that affect elite athletes and military recruits. One response of cortical bone to stress fracture is to lay down periosteal callus. The objectives of this study were to determine if material properties are different among bones with different stages of stress fracture callus, at both a callus site and at a distal site. Cortical specimens were mechanically tested to determine their stress–strain response. Material property differences were examined using nonparametric and regression analyses. At the callus site, material properties were low during the earliest stages of callus, higher with increasing callus maturity, but …

A Biomechanical Comparison Of Locked Plate Fixation With Percutaneous Insertion Capability Versus The Angled Blade Plate In A Subtrochanteric Fracture Gap Model, Brett D. Crist, Afshin Khalafi, Scott J. Hazelwood, Mark A. Lee

Biomedical Engineering

Objectives: The angled blade plate has been the historical standard in fixed-angle extramedullary subtrochanteric femur fracture fixation, but it requires an extensile lateral approach to the femur. Little formal evaluation exists for specifically designed percutaneous extramedullary implants. The purpose of this study was to compare 3 locked plating constructs, all with percutaneous insertion capability, with the standard 95-degree angled blade plate to determine whether specifically designed fixed-angle extramedullary implants for subtrochanteric femur fractures were biomechanically comparable to the angled blade plate.

Methods: Forty composite adult femurs were divided into 4 equal groups. The constructs evaluated included a 95-degree angled blade …

The Uqam Mummy – The Use Of Non-Destructive Imaging To Reconstruct An Ancient Osteobiography And To Document Modern Malfeasance, Andrew J. Nelson, Andrew D. Wade, R. Hibbert, B. Macdonald, M. Donaldson, R. Chatelain, N. Nguyen, V. Lywood, G. Gibson, M. Trumpour, S. N. Friedman, P. V. Granton, J. Morgan, David W. Holdsworth, I. A. Cunningham

Anthropology Presentations

An Egyptian mummy and her coffin dating to the 26th Dynasty were donated to the École de Beaux Arts in Montreal in 1927. This mummy has been in the collection of the Université du Québec à Montréal since 1967. Inscriptions on the elaborate coffin identify the individual as Hetep-Bastet. In 1969, the mummy was attacked by a protester, who caused extensive damage. The mummy was scanned once over a decade ago. However, computed tomography (CT) technology has advanced a great deal since that time, and some conclusions reached were somewhat suspect (e.g. that she suffered from a large dental abscess …

Statistical Hypothesis Testing For Postreconstructed And Postregistered Medical Images, Eugene Demidenko

Dartmouth Scholarship

Postreconstructed and postregistered medical images are typically treated as the raw data, implicitly assuming that those operations are error free. We question this assumption and explore how the precision of reconstruction and affine registration can be assessed by the image covariance matrix and confidence interval, called the confidence eigenimage, using a statistical model-based approach. Various hypotheses may be tested after image reconstruction and registration using classical statistical hypothesis testing vehicles: Is there a statistically significant difference between images? Does the intensity at a specific location or area of interest belong to the “normal” range? Is there a tumor? Does the …

Splenic Trauma As An Adverse Effect Of Torso-Protecting Side Airbags: Biomechanical And Case Evidence, Jason John Hallman, Karen J. Brasel, Narayan Yoganandan, Frank A. Pintar

Biomedical Engineering Faculty Research and Publications

Injury mechanisms from frontal airbags, first identified in anecdotal reports, are now well documented for pediatric, small female, and out-of-position occupants. In contrast, torso side airbags have not yet been consistently associated with specific injury risks in field assessments. To determine possible torso side airbag-related injuries, the present study identified crashes involving side airbags from reports within the CIREN, NASS, and SCI databases. Injury patterns were compared to patterns from lateral crashes in absence of side airbag. Splenic trauma (AIS 3+) was found present in five cases of torso side airbag deployment at lower impact severity (as measured by velocity …

Modulation Of Mitochondrial Bioenergetics In The Isolated Guinea Pig Beating Heart By Potassium And Lidocaine Cardioplegia: Implications For Cardioprotection, Mohammed Aldakkak, David F. Stowe, Edward J. Lesnefsky, James S. Heisner, Qun Chen, Amadou K.S. Camara

Biomedical Engineering Faculty Research and Publications

Mitochondria are damaged by cardiac ischemia/reperfusion (I/R) injury but can contribute to cardioprotection. We tested if hyperkalemic cardioplegia (CP) and lidocaine (LID) differently modulate mitochondrial (m) bioenergetics and protect hearts against I/R injury. Guinea pig hearts (n = 71) were perfused with Krebs Ringer's solution before perfusion for 1 minute just before ischemia with either CP (16 mM K+) or LID (1 mM) or Krebs Ringer's (control, 4 mM K+). The 1-minute perfusion period assured treatment during ischemia but not on reperfusion. Cardiac function, NADH, FAD, m[Ca2+], and superoxide (reactive oxygen species) were assessed at baseline, during the 1-minute perfusion, …

The Effect Of Glass Synthesis Route On Mechanical And Physical Properties Of Resultant Glass Ionomer Cements, A. Wren, O. M. Clarkin, F. R. Laffir, C. Ohtsuki, I. Y. Kim, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Glass ionomer cements (GICs) have potential orthopaedic applications. Solgel processing is reported as having advantages over the traditional melt-quench route for synthesizing the glass phase of GICs, including far lower processing temperatures and higher levels of glass purity and homogeneity. This work investigates a novel glass formulation, BT 101 (0.48 SiO₂-0.36 ZnO-0.12 CaO-0.04 SrO) produced by both the melt-quench and the solgel route. The glass phase was characterized by X-ray diffraction (XRD) to determine whether the material was amorphous and differential thermal analysis (DTA) to measure the glass transition temperature (T_g). Particle size analysis (PSA) was …

Flexor Reflex Decreases During Sympathetic Stimulation In Chronic Human Spinal Cord Injury, Mark Kevin Garrison, Brian D. Schmit

Biomedical Engineering Faculty Research and Publications

A better understanding of autonomic influence on motor reflex pathways in spinal cord injury is important to the clinical management of autonomic dysreflexia and spasticity in spinal cord injured patients. The purpose of this study was to examine the modulation of flexor reflex windup during episodes of induced sympathetic activity in chronic human spinal cord injury (SCI). We simultaneously measured peripheral vascular conductance and the windup of the flexor reflex in response to conditioning stimuli of electrocutaneous stimulation to the opposite leg and bladder percussion. Flexor reflexes were quantified using torque measurements of the response to a noxious electrical stimulus …

Towards Supervised Autonomous Task Completion Using An In Vivo Surgical Robot, Jason J. Dumpert

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Laparoscopy is a minimally invasive alternative to traditional abdominal surgery. Unlike traditional surgery, a laparoscopic procedure can be completed using small incisions. The use of these small incision results in reduced pain to the patient, shorter recovery times, and less trauma to skin, muscle and other tissues. However, these benefits to the patient are offset by the increased difficulty to the surgeon performing the procedure. These difficulties include reduced dexterity, reduced perception, and longer procedure times. The use of small in vivo robotic devices in minimally invasive surgery is one possible solution to these problems. The movement of these devices …

Accelerometer Based Measurement For The Mapping Of Neck Surface Vibrations During Vocalized Speech, Mark Nolan, Brian Madden, Edward Burke

Conference Papers

This paper presents a detailed study of the vibrations on the surface of the neck during a vocalization of predefined fundamental frequency and intensity. This study was carried out as part of a wider investigation into the use of laryngeal vibrations as a channel of communication. Another potential application of this study is in identifying a suitable location for a hands-free electro-larynx for laryngectomees.

An analog accelerometer, with dimensions 5x5x1.6mm and of mass 80mg, was used to perform the measurements. It was connected to a 12-bit analog-to-digital converter via single strands of insulated wire with a diameter of 100μm. The …

A Modification To The Group Delay And Simulated Annealing Technique For Characterization Of Peripheral Nerve Fiber Size Distributions For Non-Deterministic Sampled Data, Robert B. Szlavik

Biomedical Engineering

The ability to determine the characteristics of peripheral nerve fiber size distributions would provide additional information to clinicians for the diagnosis of specific pathologies of the peripheral nervous system. Investigation of these conditions, using electro-diagnostic techniques, is advantageous in the sense that such techniques tend to be minimally invasive yet provide valuable diagnostic information. One of the principal electro-diagnostic tools available to the clinician is the nerve conduction velocity test. While the peripheral nerve conduction velocity test can provide useful information to the clinician regarding the viability of the nerve under study, it is a single parameter test that yields …

Post-Yield Relaxation Behavior Of Bovine Cancellous Bone, Travis A. Burgers, Roderic S. Lakes, Sylvana Garcia-Rodriguez, Geoffrey R. Piller, Heidi-Lynn Ploeg

Mechanical Engineering Faculty Publications

Relaxation studies were conducted on specimens of bovine cancellous bone at post-yield strains. Stress and strain were measured for 1000 s and the relaxation modulus was determined. Fifteen cylindrical, cancellous bone specimens were removed from one bovine femur in the anterior–posterior direction. The relaxation modulus was found to be a function of strain. Therefore cancellous bone is non-linearly viscoelastic/viscoplastic in the plastic region. A power law regression was fit to the relaxation modulus data. The multiplicative constant was found to be statistically related through a power law relationship to both strain (p < 0.0005) and apparent density (p < 0.0005) while the power coefficient was found to be related through a power law relationship, E(t, ε)= A(ε)t-n(ε), to strain (p < 0.0005), but not apparent density.

Methods For Calculating Coronary Perfusion Pressure During Cpr, Michael P. Otlewski, Leslie A. Geddes, Michael Pargett, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Coronary perfusion pressure (CPP) is a major indicator of the effectiveness of cardiopulmonary resuscitation in human and animal research studies; however methods for calculating CPP differ among research groups. Here we compare the 6 published methods for calculating CPP using the same data set of aortic (Ao) and right atrial (RA) blood pressures. CPP was computed using each of the 6 calculation methods in an anesthetized pig model, instrumented with catheters with Cobe pressure transducers. Aortic and right atrial pressures were recorded continuously during electrically induced ventricular fibrillation and standard CPR. CPP calculated from the same raw data set by …

Effects Of Non-Equilibrium Plasma On Eukaryotic Cells (Final Report: Grant Fa9550-06-1-0004), Mounir Laroussi, Fred C. Dobbs, Old Dominion University

Electrical & Computer Engineering Faculty Publications

This document is our final report describing the research activities carried out under AFOSR Grant FA9550-06-1-0004. First, descriptions of our cold plasma generation systems are presented. Two systems, developed with past and present AFOSR support, are available in our laboratory. The first is a pulsed device capable of emitting a cold plasma plume in room air. The second is an air plasma generator the core of which is a dielectric barrier discharge excited by a high AC voltage. Following these brief descriptions we first present the effects of an atmospheric pressure air plasma on four different types of eukaryotic microalgae. …

The Tromped, A Means Of Prophylaxis For Flight Related Deep Vein Thrombosis, Carolyn Collins

Doctoral

The process of blood flow in the leg, against gravity and towards the heart is instigated by compression of the veins in the foot. Contraction of the calf muscles results in an ejection volume (EV) of blood towards the heart, completing the process. Research studies have shown an association between flight travel and deep vein thrombosis (DVT). Stasis of blood flow can lead to the development of thrombus formation. Deep Vein Thrombosis occurs in situations where people are immobile for long periods of time, whether this is a result of ill health or travel on land or in the air. …

Comparison Of Failure Mechanisms For Cements Used In Skeletal Luting Applications, O. Clarkin, D. Boyd, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Glass Polyalkenoate Cements (GPCs) based on strontium calcium zinc silicate (Sr-Ca-Zn-SiO₂) glasses and low molecular weight poly (acrylic acid) (PAA) have been shown to exhibit suitable compressive strength (65 MPa) and flexural strength (14 MPa) for orthopaedic luting applications. In this study, two such GPC formulations, alongside two commercial cements (Simplex ® P and Hydroset™) were examined. Fracture toughness and tensile bond strength to sintered hydroxyapatite and a biomedical titanium alloy were examined. Fracture toughness of the commercial Poly(methyl methacrylate) cement, Simplex® P, (3.02 MPa m^1/2) was superior to that of the novel GPC (0.36 MPa …

Discriminating Pulmonary Hypertension Caused By Monocrotaline Toxicity From Chronic Hypoxia By Near-Infrared Spectroscopy And Multivariate Methods Of Analysis, Simon Duri, Robert C. Molthen, Chieu D. Tran

Biomedical Engineering Faculty Research and Publications

A new method has been developed for the determination of tissue pathology caused by chronic hypoxia and monocrotaline toxicity. The method is based on the use of near-infrared (NIR) spectrophotometry to measure spectra of lung tissue from normal chronic hypoxia (CH) and monocrotaline (MCT) models of pulmonary hypertension (PH), followed by analysis using multivariate methods, that is, principal component analysis (PCA) and partial least squares (PLS). Synergistic use of NIR with the PCA/PLS method makes it possible, for the first time, not only to divide different lung tissue samples into their respective groups (normal, CH, and MCT) but also to …

Video-Rate Near Infrared Tomography To Image Pulsatile Absorption Properties In Thick Tissue, Zhiqiu Li, Venkataramanan Krishnaswamy, Scott C. Davis, Subhadra Srinivasan, Keith D. Paulsen, Brian W. Pogue

Dartmouth Scholarship

A high frame-rate near-infrared (NIR) tomography system was created to allow transmission imaging of thick tissues with spectral encoding for parallel source implementation. The design was created to maximize tissue penetration through up to 10 cm of tissue, allowing eventual use in human imaging. Eight temperature-controlled laser diodes (LD) are used in parallel with 1.5 nm shifts in their lasing wavelengths. Simultaneous detection is achieved with eight high-resolution, CCD-based spectrometers that were synchronized to detect the intensities and decode their source locations from the spectrum. Static and dynamic imaging is demonstrated through a 64 mm tissue-equivalent phantom, with acquisition rates …

Comparison Of An Experimental Bone Cement With A Commercial Control, Hydroset™, O. M. Clarkin, D. Boyd, S. Madigan, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Glass polyalkenoate cements based on strontium calcium zinc silicate glasses (Zn-GPCs) and high molecular weight polyacrylic acids (PAA) (MW; 52,000-210,000) have been shown to exhibit mechanical properties and in vitro bioactivity suitable for arthroplasty applications. Unfortunately, these formulations exhibit working times and setting times which are too short for invasive surgical applications such as bone void filling and fracture fixation. In this study, Zn-GPCs were formulated using a low molecular weight PAA (MW; 12,700) and a modifying agent, trisodium citrate dihydrate (TSC), with the aim of improving the rheological properties of Zn-GPCs. These novel formulations were then compared with commercial …