Biomedical Engineering and Bioengineering Commons^™

Origins Of Scale Invariance In Vocalization Sequences And Speech, Fatemeh Khatami, Markus Wöhr, Heather L. Read, Monty A. Escabí

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To communicate effectively animals need to detect temporal vocalization cues that vary over several orders of magnitude in their amplitude and frequency content. This large range of temporal cues is evident in the power-law scale-invariant relationship between the power of temporal fluctuations in sounds and the sound modulation frequency (f). Though various forms of scale invariance have been described for natural sounds, the origins and implications of scale invariant phenomenon remain unknown. Using animal vocalization sequences, including continuous human speech, and a stochastic model of temporal amplitude fluctuations we demonstrate that temporal acoustic edges are the primary acoustic cue accounting …

Underwater Sound Transmission Through Arrays Of Disk Cavities In A Soft Elastic Medium., David C. Calvo, Abel L. Thangawng, Christopher N. Layman, Riccardo Casalini, Shadi F. Othman

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Scattering from a cavity in a soft elastic medium, such as silicone rubber, resembles scattering from an underwater bubble in that low-frequency monopole resonance is obtainable in both cases. Arrays of cavities can therefore be used to reduce underwater sound transmission using thin layers and low void fractions. This article examines the role of cavity shape by microfabricating arrays of disk-shaped air cavities into single and multiple layers of polydimethylsiloxane. Comparison is made with the case of equivalent volume cylinders which approximate spheres. Measurements of ultrasonic underwater sound transmission are compared with finite element modeling predictions. The disks provide a …

Noninvasive Assessment Of Cardiac Abnormalities In Experimental Autoimmune Myocarditis By Magnetic Resonance Microscopy Imaging In The Mouse., Chandirasegaran Massilamany, Vahid Khalilzad-Sharghi, Arunakumar Gangaplara, David Steffen, Shadi F. Othman, Jay Reddy

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Myocarditis is an inflammation of the myocardium, but only -10% of those affected show clinical manifestations of the disease. To study the immune events of myocardial injuries, various mouse models of myocarditis have been widely used. This study involved experimental autoimmune myocarditis (EAM) induced with cardiac myosin heavy chain (Myhc)-α 334-352 in A/J mice; the affected animals develop lymphocytic myocarditis but with no apparent clinical signs. In this model, the utility of magnetic resonance microscopy (MRM) as a non-invasive modality to determine the cardiac structural and functional changes in animals immunized with Myhc-α 334-352 is shown. EAM and healthy mice …

Near-Infrared Optical Imaging For Monitoring The Regeneration Of Osteogenic Tissue-Engineered Constructs., Elizabeth A. Cowles, Joy L. Kovar, Evan T. Curtis, Huihui Xu, Shadi F. Othman

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Millions of cases of bone injury or loss due to trauma, osteoporosis, and cancer occur in the United States each year. Because bone is limited in its ability to regenerate, alternative therapy approaches are needed. Bone tissue engineering has the potential to correct musculoskeletal disorders through the development of cell-based substitutes for osteogenic tissue replacement. Multiple medical imaging techniques such as magnetic resonance microscopy (MRM) were investigated recently; these techniques are able to provide useful information on the anatomical and structural changes of developing bone. However, there is a need for noninvasive approaches to evaluate biochemical constituents and consequent compositional …

Magnetic Resonance Elastography Methodology For The Evaluation Of Tissue Engineered Construct Growth., Evan Curtis, Simeng Zhang, Vahid Khalilzad-Sharghi, Thomas Boulet, Shadi F. Othman

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Traditional mechanical testing often results in the destruction of the sample, and in the case of long term tissue engineered construct studies, the use of destructive assessment is not acceptable. A proposed alternative is the use of an imaging process called magnetic resonance elastography. Elastography is a nondestructive method for determining the engineered outcome by measuring local mechanical property values (i.e., complex shear modulus), which are essential markers for identifying the structure and functionality of a tissue. As a noninvasive means for evaluation, the monitoring of engineered constructs with imaging modalities such as magnetic resonance imaging (MRI) has seen increasing …

Curcumin-Loaded Magnetic Nanoparticles For Breast Cancer Therapeutics And Imaging Applications., Murali M. Yallapu, Shadi F. Othman, Evan Curtis, Nichole A. Bauer, Neeraj Chauhan, Deepak Kumar, Meena Jaggi, Subhash C. Chauhan

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BACKGROUND: The next generation magnetic nanoparticles (MNPs) with theranostic applications have attracted significant attention and will greatly improve nanomedicine in cancer therapeutics. Such novel MNP formulations must have ultra-low particle size, high inherent magnetic properties, effective imaging, drug targeting, and drug delivery properties. To achieve these characteristic properties, a curcumin-loaded MNP (MNP-CUR) formulation was developed.

METHODS: MNPs were prepared by chemical precipitation method and loaded with curcumin (CUR) using diffusion method. The physicochemical properties of MNP-CUR were characterized using dynamic light scattering, transmission electron microscopy, and spectroscopy. The internalization of MNP-CUR was achieved after 6 hours incubation with MDA-MB-231 breast …

Rapid Cell Extraction In Aqueous Two-Phase Microdroplet Systems, Kalpana Vijayakumar, Shelly Gulati, Andrew J. De Mello, Joshua B. Edel

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Distinguishing specific cells is an essential technique in cell research and clinical diagnostics. We report a novel method to passively isolate and extract cells in a microfluidic device. We utilise a droplet-based microfluidic system to generate an aqueous two phase system in which aqueous droplets consist of two phases in the form of a double emulsion. Specifically, we generate PEG droplets that completely encapsulate DEX droplets within a microfluidic channel. Target cells can be introduced directly into the droplets and driven to partition to the more favourable phase, whilst still being contained within the aqueous droplet. Human T lymphoma cells, …

High-Resolution/High-Contrast Mri Of Human Articular Cartilage Lesions., Shadi F. Othman, Jun Li, Osama Abdullah, Jessy J. Moinnes, Richard L. Magin, Carol Muehleman

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BACKGROUND: Magnetic resonance microscopy (MRM) is an important experimental tool in the identification of early cartilage lesions.

METHODS: Normal and degenerated cartilage samples were imaged at 11.74 T using a standard spin echo sequence. Quantitative MR measurements for T1, T2, and ADC were obtained and mapping for T2 and ADC was performed. The bi-exponential model for T2 relaxation was also explored. Histology was carried out for comparison with MR images.

RESULTS: MR images of cartilage samples displaying early stages of degeneration were positively correlated to their histological appearance in 23-microm high-resolution images and also with much shorter imaging times at …