bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for Plasticity in White‐Matter Tracts of Patients with Chronic Broca's Aphasia Undergoing Intense Intonation‐based Speech Therapy
Authors: Schlaug Gottfried , Marchina Sarah , Norton Andrea
Published: July 2009

Recovery from aphasia can be achieved through recruitment of either perilesional brain regions in the affected hemisphere or homologous language regions in the nonlesional hemisphere. For patients with large left‐hemisphere lesions, recovery through the right hemisphere may be the only possible path. The right‐hemisphere regions most likely to play a role in this recovery process are the superior temporal lobe (important for auditory feedback control), premotor regions/posterior inferior frontal gyrus (important for planning and sequencing of motor actions and for auditory‐motor mapping), and the primary motor cortex (important for execution of vocal motor actions). These regions are connected reciprocally via a major fiber tract called the arcuate fasciculus (AF), however, this tract is not as well developed in the right hemisphere as it is in the dominant left. We tested whether an intonation‐based speech therapy (i.e., melodic intonation therapy [MIT]), which is typically administered in an intense fashion with 75–80 daily therapy sessions, would lead to changes in white‐matter tracts, particularly the AF. Using diffusion tensor imaging (DTI), we found a significant increase in the number of AF fibers and AF volume comparing post‐ with pretreatment assessments in six patients that could not be attributed to scan‐to‐scan variability. This suggests that intense, long‐term MIT leads to remodeling of the right AF and may provide an explanation for the sustained therapy effects that were seen in these six patients.
Musicians—Same or Different?
Authors: Tervaniemi Mari
Published: July 2009

In the neuroscience of music, musicians have traditionally been treated as a unified group, as if the demands set by their musical activities would be more or less equal in terms of perceptual, cognitive, and motor functions. However, obviously, their musical preferences differentiate them to a higher degree, for instance, in terms of the instrument they choose and the music genre they are mostly engaged with as well as their practicing style. This diversity in musicians’ profiles has been recently taken into account in several empirical endeavors. The present contribution will review the evidence available about the various neurocognitive profiles these different kinds of musicians display.
Is Beat Induction Innate or Learned?
Authors: Honing Henkjan , Ladinig Olivia , Háden Gábor P. , Winkler István
Published: July 2009

Meter is considered an important structuring mechanism in the perception and experience of rhythm in music. Combining behavioral and electrophysiological measures, in the present study we investigate whether meter is more likely a learned phenomenon, possibly a result of musical expertise, or whether sensitivity to meter is also active in adult nonmusicians and newborn infants. The results provide evidence that meter induction is active in adult nonmusicians and that beat induction is already functional right after birth.
Exceptional Preservation of Memory for Tunes and Lyrics
Authors: Vanstone Ashley D. , Cuddy Lola L. , Duffin Jacalyn M. , Alexander Elizabeth
Published: July 2009

Four elderly persons with neurologic impairments of differing etiology and differing cognitive profiles presented unexpected patterns of memory for tunes and song lyrics. Impairments included profound deafness, right‐hemisphere stroke, and dementia of the Alzheimer's type. Patterns for the impaired individuals differed according to the disorder, but each person had some scores within the range for 90 healthy seniors. We suggest implications for models of brain organization for musical memory.
Effects of Musical Training on Key and Harmony Perception
Authors: Corrigall Kathleen A. , Trainor Laurel J.
Published: July 2009

Even adults with no formal music lessons have implicit musical knowledge acquired through exposure to the music of their culture. Two of these abilities are knowledge of key membership (which notes belong in a key) and harmony (chord progressions). Studies to date suggest that perception of harmony emerges around 5–6 years of age. Using simple tasks, we found that formal music training influences key and harmony perception in 3‐ to 6‐year‐olds, and that even nonmusicians as young as 3 years have some knowledge of key membership and harmony.
The Subjective Experience of Music in Autism Spectrum Disorder
Authors: Allen Rory , Hill Elisabeth , Heaton Pamela
Published: July 2009

Semi‐structured interviews were conducted with 12 high‐functioning adults on the autism spectrum in order to examine the nature of their personal experiences of music. The analysis showed that most participants exploit music for a wide range of purposes in the cognitive, emotional and social domains, but the autism spectrum disorder (ASD) group's descriptions of mood states reflected a greater reliance on internally focused (arousal) rather than externally focused (emotive) language, when compared with studies of typically developing individuals.
Neural Correlates Underlying Musical Semantic Memory
Authors: Groussard M. , Viader F. , Landeau B. , Desgranges B. , Eustache F. , Platel H.
Published: July 2009

Numerous functional imaging studies have examined the neural basis of semantic memory mainly using verbal and visuospatial materials. Musical material also allows an original way to explore semantic memory processes. We used PET imaging to determine the neural substrates that underlie musical semantic memory using different tasks and stimuli. The results of three PET studies revealed a greater involvement of the anterior part of the temporal lobe. Concerning clinical observations and our neuroimaging data, the musical lexicon (and most widely musical semantic memory) appears to be sustained by a temporo‐prefrontal cerebral network involving right and left cerebral regions.
Overlap of Musical and Linguistic Syntax Processing: Intracranial ERP Evidence
Authors: Sammler D. , Koelsch S. , Ball T. , Brandt A. , Elger C. E. , Friederici A. D. , Grigutsch M. , Huppertz H.‐J. , Knösche T. R. , Wellmer J. , Widman G. , Schulze‐Bonhage A.
Published: July 2009

The present study investigated the co‐localization of musical and linguistic syntax processing in the human brain. EEGs were recorded from subdural electrodes placed on the left and right perisylvian cortex. The neural generators of the early potentials elicited by syntactic errors in music and language were localized by means of distributed source modeling and compared within subjects. The combined results indicated a partial overlap of the sources within the bilateral superior temporal gyrus, and, to a lesser extent, in the left inferior frontal gyrus, qualifying these areas as shared anatomic substrates of early syntactic error detection in music and language.
Load‐dependent Brain Activity Related to Acoustic Short‐term Memory for Pitch
Authors: Grimault Stephan , Lefebvre Christine , Vachon François , Peretz Isabelle , Zatorre Robert , Robitaille Nicolas , Jolicœur Pierre
Published: July 2009

Acoustic short‐term memory (ASTM) refers to the temporary retention of acoustic information. In the present study, we investigated the neural correlates of ASTM for pitch using magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI). Both MEG and fMRI analyses revealed brain activations that varied with memory load in the vicinity of secondary auditory cortex (Brodmann's area, BA22) and superior parietal cortex (BA5/7), while analyses specific to MEG data revealed load‐related activations in the frontal cortex (BA9/10).
Electrophysiological Correlates of Aesthetic Music Processing
Authors: Müller Mira , Höfel Lea , Brattico Elvira , Jacobsen Thomas
Published: July 2009

We analyzed the processes of making aesthetic judgments of music, focusing on the differences between music experts and laypersons. Sixteen students of musicology and 16 control subjects (also students) judged the aesthetic value as well as the harmonic correctness of chord sequences. Event‐related potential (ERP) data indicate differences between experts and laypersons in making aesthetic judgments at three different processing stages. Additionally, effects of expertise on ERP components that have previously been proven to be sensitive to musical training were replicated. The study thus provides insights into the effects of musical expertise on neural correlates of aesthetic music processing.
Estimating the Time to Reach a Target Frequency in Singing
Authors: Hutchins Sean , Campbell David
Published: July 2009

The ability to match pitches quickly and accurately is essential for proficient singing. We describe a new technique for estimating the time to reach a target frequency that uses adaptive optimal‐kernel (AOK) time‐frequency representations, designed to optimize the time‐frequency tradeoff at each time point. We show in two experiments that this measure is more sensitive to tonal priming effects than an onset latency measurement. This analysis is applied to the vocal productions of untrained singers to reveal effects of tonality and pitch height.
Home Telemedicine: Encryption is Not Enough
Authors: Salajegheh M. , Molina A. , Fu K.
Published: July 2009

Implantable medical devices and home monitors make use of wireless radio communication for both therapeutic functions and remote monitoring of patients' vital signs. While our past work showed that lack of cryptographic protection results in disclosure of private medical data and manipulation of therapies (Halperin et al., IEEE S&P, 2008) our present work shows that even using encryption is insufficient to protect the confidentiality of patient telemetry. Our experiment analyzes the security of data traffic patterns of two sets of real medical telemetry: a corpus from PhysioNet (an online biomedical research database) and a network trace of a live disaster drill using Harvard's CodeBlue medical sensor network (Chen et al., DCOSS, 2008). Our work shows that even if a wireless medical device uses encryption, patient data can leak to unauthorized parties who need not be near the patient. Our measurements show that data packet timing information and headers distinguish the types of medical and monitoring devices even if traditional cryptographic mechanisms are used. Furthermore, the highly repetitive nature of medical data, such as ECG or respiration signals, leads to additional privacy vulnerabilities that cannot be easily mitigated by means of encryption without significant modification. Data compression technology further exposes encrypted telemetry to cryptanalysis. The information leakage of telemetry could facilitate unauthorized tracking of a patient because an ECG is known to uniquely identify a person in a predetermined group (Biel et al., IEEE I&M, 2002). Moreover, our study shows that data packet padding, encryption, authentication, and other common defenses against security threats require significant energy, storage, and computation that impose on the already scarce battery and space resources. Two of our experiments show how to automatically recover data from encrypted telemetry using Bayesian classifiers. In one experiment, we encrypted an ECG signal. By observing only the length of the digitally encrypted data, we were able to reconstruct sufficient information about the original ECG data that we determined the patient's heart rate. Using similar techniques, we recovered a leaked respiration signal that visually matches the original signal. Our findings show the weakness of using common cryptographic techniques on highly periodic and often compressed medical telemetry. Our work further discusses techniques to mitigate these security and privacy risks in wireless medical telemetry systems. However, all known techniques require extra energy, computation, and bandwidth from the medical device. The lesson learned is that encryption is not enough to protect the privacy of medical telemetry, and that reasonable assurance for security and privacy will require an energy budget. Future design of medical devices will have to make difficult tradeoffs between battery life versus security and privacy. This work was supported by NSF grants CNS-0627529, CNS-0716386, and CNS-0831244.
Diamagnetic Effects of Blood in a Magnetically Levitated Blood Pump
Authors: Gomez A. D. , Day S. W.
Published: July 2009

Magnetic bearings are becoming increasingly popular in ventricular assist devices. In most cases, blood fills a portion of the gap between the magnetic actuators and rotor. Understanding the effects of the operating fluid on magnetic suspension is necessary, particularly when the device geometry features a relatively large gap (typically defined as greater than 150 um and as large as 2 mm in some pumps). A large gap reduces cell damage and allows unrestricted flow, it but increases the distance and amount of material through which magnetic fields must pass. These net effects of the operating fluid on the magnetic suspension can be characterized in terms of a contribution to the overall damping and stiffness of the system. This contribution may be caused by traditional tribological properties (density and viscosity) as well as the magnetic properties of the medium. This research isolates the effects of fluid diamagnetism on a magnetically levitated blood pump. Experimental transient and frequency responses of the system operating at 3000 to 6000 rpm are presented while pumping different liquid media: Blood, water, and fluids with similar densities and viscosities to each, but different magnetic susceptibilities. In order to calculate the stiffness and damping coefficients, a mathematical model of the system is iteratively updated to match experimental transient response. The resulting coefficients are validated in the frequency domain by means of simulations, which agree with experimental frequency response data. The relationship between diamagnetism, damping and stiffness coefficients of the test fluids with known magnetic susceptibility is also used to obtain a quantitative estimate of the magnetic susceptibility of blood.
Pre-Clinical Evaluation of Direct Current Ablation for the Treatment of Benign Prostatic Hyperplasia
Authors: Fruland B. , Holtz M. , Sundquist S. , Nelson T. , Kroll A. , Anderson K. , Larson T.
Published: July 2009

Benign Prostatic Hyperplasia (BPH) is a non-cancerous growth of the prostate gland affecting about 50% of the men over age 50. As men age, the prostate continues to grow leading to increased prostate volume, which may cause lower urinary tract symptoms (LUTS). These symptoms can include the inability to completely empty the bladder, urine retention, and a profound sensation of urgency. Direct Current (DC) ablation may be applied to treat these symptoms as a minimally-invasive alternative to surgery, medication, or thermal ablation, by causing tissue necrosis within the lateral lobes of the prostate. The objective of this study was to evaluate the effects of DC ablation in canine prostates by investigating how the resulting necrosis would change the macrostructure of the prostate for the potential treatment of symptomatic BPH. DC ablation is achieved by passing direct current through two electrodes in tissue, causing the formation of hydrogen ions at the anode and hydroxyl ions at the cathode. These ions diffuse through the tissue causing a pH of ∼1 at the anode, and ∼13 at the cathode. The extreme anti-physiological pH regions cause cellular necrosis and form in a predictable manner that is directly proportional to the charge delivered. The controlled shape and size of the lesions allow for predictable necrotic zones and enable treatment optimization. Treatment was performed on 6 acute and 8 chronic canine subject by performing a laparotomy and inserting electrodes through the prostate capsule. Acute subjects were sacrificed before recovery, while chronic subjects were sacrificed after 1, 3, 20, 40, and 60 days to investigate the healing cascade of the prostate after treatment. The chronic subjects were monitored for changes in urination or defecation patterns. Urine and blood samples were collected to evaluate the subjects' health throughout the study. Both macro-visual and pathological analyses were done to evaluate tissue response all acute and chronic subjects. Cellular necrosis within the prostate was significant and exhibited a dose response within the range of 0.07 to 0.10 cm3/coulomb for each electrode pair. The does response is defined as the ratio of necrotic tissue created, to charge delivered. Necrotic prostate cells resulted in voids with minimal scar tissue and a visible reduction in prostate mass. The treatment followed tissue planes constraining necrotic zones to the region between the prostate capsule and prostatic urethra. Both normal and hyperplastic tissues were treated and exhibited necrosis. No necrosis was observed outside the prostate. DC ablation has been demonstrated to create well-defined, predictable, and repeatable regions of cellular necrosis and structural changes in canine prostates. This technology may offer promise for the treatment of symptomatic BPH with an appropriately designed delivery system. Other potential applications include other benign and malignant tumors within the body.
Comparison of Video Laryngoscopy Technologies
Authors: Chiesa C. , Miljkovic N. , Schulte N. , Callahan J. B. , Miller D. J. , Boedeker B. H.
Published: July 2009

Indirect laryngoscopy allows practitioners to “see around the corner” of a patient's airway during intubation. Inadequate airway management is a major contributor to patient injury, morbidity and mortality. The purpose of the present study was to evaluate the video quality of commercially available video laryngoscopy systems. A team of four investigators at the University of Nebraska at Omaha and the Peter Kiewit Institute performed intubation simulations using a number of video laryngoscopy systems. Testing was done with a Laerdal Difficult Airway Manikin (Laerdal Medical Corp., Wappingers Falls, NY) in a setting that simulated difficult airways, adverse lighting conditions and various system configurations (e.g., maximizing screen contrast, minimizing screen brightness, maximizing screen color hue, etc.). Systems included the STORZ C-MACTM (KARL STORZ Endoscopy, Tuttlingen, Germany), a prototype developed by STORZ (a McIntosh #3 video blade with USB connectivity to an ultra mobile PC; “UMPC”) and a GlideScope® Portable GUL (Verathon Inc., Bothell, WA). Equipment was evaluated based on investigator's perceptions of the color (“C”), clarity (“L”) and brightness (“B”) of the image onscreen for each of the systems. Perceptions were given one of three possible ratings: High=3, Moderate=2 or Low=1. Statistics were performed using a two-tailed Wilcoxon Rank Sum test for independent samples. A summary of the results of the testing are shown below (shown as “Mean±Standard Deviation”):

• C-MAC–L=2.13±0.99, C=1.75±0.89, B=2.5±0.93, Total=6.38±2.5

• GlideScope®–L=2.38±0.92, C=1.38±0.52, B=2.38±0.92, Total=6.13±1.96

• UMPC–L=1.88±0.83, C=1.75±1.04, B=1.88±0.83, Total=5.5±2.2

Testing showed that there were no significant differences between image clarity, color, brightness or overall score of any of the tested systems (α=0.05). Since there were no significant differences in video quality between the three systems, the choice of system falls to user preference, which can vary from person to person, and qualitative analysis of features that are outside the scope of this study. Investigators plan to evaluate additional video laryngoscopy solutions in an effort to create a platform-agnostic video laryngoscopy suite. Funding by KARL STORZ Endoscopy. Investigators were blinded to funding source until after testing was completed. The authors wish to thank Dr. W. Bosseau Murray for his insightful comments.
A Muscle Energy Converter for Powering Implantable Cardiac Assist Devices
Authors: Trumble D. R. , Norris M. , Peters G.
Published: July 2009

Harnessing skeletal muscle for circulatory support would improve on current blood pump technologies by eliminating infection-prone drivelines and expensive transcutaneous transmission systems. Here we describe an implantable muscle energy converter (MEC) designed to transmit the contractile energy of the latissimus doris muscle in hydraulic form. The MEC weighs just 290 grams and comprises a metallic bellows actuated by a rotary arm fixed to the humeral insertion of the muscle via a looped artificial tendon. The housing is anchored to the ribcage using a perforated mounting ring (83 mm diameter). Lessons learned through six design iterations have produced a pump with excellent durability, energy transfer efficiency, anatomic fit, and tissue interface characteristics. This report describes recent improvements in MEC design and summarizes results from in silico, in vitro, and in vivo testing. The components most subject to wear in this device are the stainless-steel bellows, spring-loaded lip seals, and load-bearing surfaces (bearings, cams and shafts). Roller bearings supporting the camshaft and cam follower were replaced with needle bearings for better stress distribution and longer cycle life. Camshaft bearings were improved still further by changing to a full-complement configuration to lower stress concentration and reduce lateral (off-axis) shaft movement that could reduce lipseal life. Bellows cycle life was estimated using ANSYS V11 finite element analysis (FEA) software with a mesh size of 0.002”. In this simulation a pressure of 22 psi was applied to the internal surface of the bellows and compression length was set to the longest possible stroke (0.177”). All load-bearing surfaces were analyzed for fatigue stress and cycle life under these same loading conditions following closed form equations. Results show that the overall durability of the MEC device can be expected to exceed 450 million cycles, resulting in a minimum working life of 14.5 years given a 1 Hz cycle rate. Lipseal durability was tested empirically in a 37°C saline bath using a cycling apparatus designed specifically for that purpose. After 55 days (12.3 million cycles) the test was stopped and the unit disassembled and inspected. The shaft and seals showed evidence of contamination buildup in front of the lip seal but not behind it, indicating that the seal had functioned properly throughout the test period. Importantly, implant studies in 30–35 Kg dogs (n=7) confirm excellent anatomic fit, patient comfort, and device functionality to one month. These results suggest that muscle-powered cardiac assist devices are feasible and that efforts to further develop this technology are warranted.
The Design of a Cell-Phone Based Balance-Training Device
Authors: Kim J. H. , Sienko K. H.
Published: July 2009

Postural imbalance can result from various vestibular (central and peripheral), neurological, orthopedic, and vascular disorders, as well as sensory conflicts, head injuries, infections, medications, and aging. Balance rehabilitation has been shown to improve the quality of life of individuals with balance disorders by facilitating the development of compensatory strategies which mitigate dizziness, improve balance, and increase the ability to perform activities of daily living. The goal of this work is to design a cell phone based balance training device that can be used in the home to assist a patient with therapist-assigned balance exercises or in an environment where access to balance therapy is limited (i.e., rural regions in the developing world). The prototype comprises an iPhone (iPhone SDK, Apple), an auxiliary pager motor (Samsung GH31-00154C), and an audio amplifier (Analog Devices SSM2301). Body motion is detected by on-board tri-axial accelerometers, and a tilt estimate is computed using a low-pass filter. The phone's native pager motor and an auxiliary pager motor are used to provide real-time vibrotactile cues of body tilt along a single axis. The phone is worn on the small of the back to provide anterior-posterior vibrotactile trunk tilt feedback during stance, and worn near the right hip to provide medial-lateral vibrotactile trunk tilt feedback during gait. Auditory files direct the user through a series of standard balance rehabilitation exercises. A summary of the user's performance is displayed on the phone's screen following completion of the exercise.
Application of Magnetoelastic Thick Films for Wireless, In Vivo Monitoring of Pressure at Abdominal Aortic Aneurysm
Authors: Tan E. , Pereles B. , Ong K.
Published: July 2009

According to the National Center for Health Statistics, cardiovascular diseases remain the number one killer in the United States. Among the various types of cardiovascular diseases, the aortic aneurysm is ranked number nine. The abdominal aortic aneurysm (AAA), in particular, is an abnormal, localized dilation of the abdominal aorta wall caused by weakened or diseased aorta walls. One of the treatments for this disease is using an endovascular surgery at which an endovascular graft is delivered to the aneurysm site through the femoral arteries. The deployment of the endovascular graft will exclude blood flow to the aneurysm, thus preventing further expansion of the aneurysm sac. Although this technique is preferred over open surgeries due to its minimal invasiveness, an event known as the endoleak, where the endovascular graft fails to retain the blood and leads to leakage to the aneurysm sac, may occur. Here, we are developing a novel pressure monitoring system to remotely and continuously measure the pressure in the aneurysm sac. The main component of the system is a pressure-sensitive material, made of a magnetoelastic, magnetically soft film attached or coated on the endovascular graft. When under an AC magnetic field (excitation field), the magnetoelastic film generates a secondary magnetic field. Due to its magnetoelastic property, the amplitude of the secondary field varies with applied stresses, allowing remote pressure monitoring. To eliminate noises from the excitation field, the generated secondary field is measured at twice the excitation frequency to obtain the 2nd-order harmonic field, which is used for tracking the pressure variations. A scaled-up prototype of the pressure monitoring system was constructed and examined to demonstrate the feasibility of this technology. A commercial magnetoelastic thick film, Metglas 2826MB from Metglas, Inc., was attached on a polycarbonate substrate and covered by a thin polycarbonate protective layer. The substrate was then embedded in a plastic tube with flowing liquid to represent the condition of an aorta. Liquid pressure in the tube was altered during the experiment by restricting or relaxing the flow channel. In this study, a 10mm×40mm file (Film A) and a 5mm×40mm film (Film B) were fabricated and tested. The amplitude of the 2nd-order harmonic field produced by the films was inversely proportional to the fluid pressure. It was also shown that films with different sizes exhibited different signal sensitivity with the smaller film (Film B) exhibited greater sensitivity. This experiment indicates that feasibility of the pressure monitoring technology.
Targeting Colon Cancer Cells Using PEGylated Liposomes Modified With a Fibronectin-Mimetic Peptide
Authors: Garg A. , Tisdale A. W. , Kokkoli E.
Published: July 2009

The ability to target cancer cells using an appropriate drug delivery system can significantly reduce the associated side effects from cancer therapies and can help in improving overall quality of life post cancer survival. Integrin α5β1 is expressed on several types of cancer cells, including colon cancer, and plays an important role in tumor growth and metastasis. Thus, the ability to target the integrin α5β1 using an appropriate drug delivery nano-vector can signficantly help in inhibiting tumor growth and reducing tumor metastasis. In this study we have designed functionalized stealth liposomes (liposomes covered with polyethylene glycol (PEG)) that specifically target the integrin α5β1. The PEG provides a steric barrier allowing the liposomes to circulate in the blood for longer duration and the functionalizing moiety, the PR_b peptide specifically recognizes and binds to integrin α5β1 expressing cells. PR_b is a novel peptide sequence, designed in our lab, that mimics the cell adhesion domain of fibronectin, and includes four building blocks, RGDSP (the primary recognition site for α5β1), PHSRN (the synergy site for α5β1), a (SG)5 linker, and a KSS spacer. In this study, we demonstrate that by optimizing the amount of PEG and PR_b on the liposomal interface we can engineer nano-vectors that bind to CT26.WT, HCT116, and RKO colon cancer cells in a specific manner and are internalized through α5β1-mediated endocytosis. Stealth liposomes functionalized with an RGD containing peptide bind to colon cancer cells and internalize, but they have much lesser efficiency than PR_b-targeted stealth liposomes, and more importantly they are not as specific since many integrins bind to RGD. PR_b-targeted stealth liposomes are as cytotoxic as free 5-Fluorouracil (5-FU) and exert the highest cytotoxicity on CT26.WT cells compared to RGD-targeted stealth liposomes and non-targeted stealth liposomes. In order to further increase the efficacy of the system we have designed peptide-functionalized stealth liposomes that are pH-sensitive and exhibit triggered release under mild acidic conditions present in endocytotic vesicles. The proposed targeted delivery system has the great potential to deliver a therapeutic load directly to colon cancer cells, in an efficient and specific manner.
Development of the Stiffenable Exoskeleton Device for a Colonoscopy
Authors: Choi JungHun , Sturges R. H.
Published: July 2009

Colonoscopy provides a minimally invasive tool for examining and treating the colon without surgery, but current colonoscope designs still cause a degree of pain and mechanical trauma to the colon wall. The most common colonoscopes are long tubes inserted through the rectum with fiber optic lights, cameras, and biopsy tools on the distal end. The stiffness required to support these tools makes it difficult for the scopes to navigate the twisted path of the colon without causing mechanical trauma inside the colon wall or distorting its shape. The shaft of the colonoscope often causes looping (alpha, reverse alpha, or n), and it is very difficult to advance the distal tip of the colonoscope with looping. In order to avoid looping and minimize mechanical trauma, the author expanded on a design by Zehel et al., who proposed surrounding a flexible colonoscope with an external exoskeleton structure with controllable stiffness. The stiffenable exoskeleton device is comprised of rigid, articulating tubular units, which are stiffened or relaxed by four control cables. The stiffened or relaxed exoskeleton device guides navigation and provides stability for the colonoscope when it protrudes beyond the exoskeleton device for examination and procedures. This research determined the design requirements of such an exoskeleton device and tested requirements of such an exoskeleton device and tested its behavior in a colonoscopy training model. Moreover, the stiffenable exoskeleton device can be operated in purely a mechanical way, which is safe as a class II medical device, and no additional modification of the colonoscope is needed to use the stiffenable exoskeleton device. Colonoscopy training model is used to test the stiffenable exoskeleton device. First, the endoscopist inserted the colonoscope into the colonoscopy training model up to the end of the stiffenable exoskeleton device along the shaft of the colonoscope to the distal tip of the colonoscope, and then locked the stiffenable exoskeleton device and advanced the shaft of the colonoscope to examine the colon. When the distal tip reached the cecum, he or she unlocked the stiffenable exoskeleton device, retracted the shaft of the colonoscope and the stiffenable exoskeleton device, and checked for polyps or other colon disease. Also, the endoscopist can insert the stiffenable exoskeleton device and a colonoscope alternatively by stiffening and releasing the exoskeleton device. In that way, endoscopist can advance the colonoscope and the exoskeleton structure inch-by-inch without causing mechanical trauma in the rectum and the sigmoid colon. The endoscopist tested the stiffenable exoskeleton device using the colonoscopy training model and fulfilled its objectives. Several other diagnostic procedures involving the stomach, esophagus and the nose could also benefit due to the improvements provided by the stiffenable exoskeleton technology.
Recumbent Exercise Bicycle for Low-Impact Rehabilitation of Obese Individuals
Authors: Newman K. , Gibson K. , Zeller H. , Carter S. , Joyce B.
Published: July 2009

It is often difficult for persons who are extremely overweight to find exercise systems that are accessible and safe to use. Seating is required to handle heavier loads of up to 500 lbs. and provide safe access to the exercise unit. Additionally, the exercise should not cause additional pain or possible damage if the person needs to suddenly stop. A multidisciplinary team of undergraduate engineers participated in a training course to interview a non-technical customer to determine design requirements and then underwent a rigorous design process to implement the best solution. Mechanical analysis was performed to determine the best solution for the concept, materials, and resistance. An exercise machine with a rotating chair was selected as the best solution. The chair rotates 90 degrees so that the user can sit down without having to step onto the machine. Once the user sits, the chair can then rotate 90 degrees until the chair is in the exercise position; in either position the chair locks into position for stability. This particular concept uses a bicyle exercise. This exercise minimizes impact on the knees, which is a safety issue for patients with knee problems. A sitting position for this exercise eliminates the stability issue raised with a standing exercise, where there is worry of falling. This exercise is beneficial for cardiovascular exercise. Resistance is implemented using a magnet. Fluid resistance and fly-wheel resistance would create too much momentum which was not desired by the customer. Electrical analysis was performed to determine the best method to sense heart rate, speed, and computer interface. Wired handles were selected to monitor the heart rate. These are hand held and are much easier to use than a chest strap. An optical sensor was used to sense speed. It was placed near the center of the wheel and rotations were indicated by a tab to break the connection in the sensor. This method was selected over a Hall effect sensor because it is a much simpler sensing method that does not require an addition magnetic component that is not too accurate a low speeds. The computer interface was a Motorola HC12s since it had the necessary I/O interfaces and was low cost. A custom interface was created with seven segment displays to show the heart rate and time of exercise. The system was then developed, tested, and delivered to the customer for use. This project was supported by Grant No. 0607883 from the National Science Foundation.
Wireless Recharging of Implanted Batteries via Ultrasound
Authors: Radziemski L. , Denison A. , Dunn F.
Published: July 2009

In order to expand the applications for implanted rechargeable batteries, and to reduce the frequency of battery replacement procedures, we are investigating a recharging technique complimentary to and improving on the current RF recharging technique. Although the first applications deal with batteries that could be implanted in human bodies to power neurostimulators, sensors, and drug pumps, non-medical applications may exist. Using a transmitter-receiver arrangement, we have recharged batteries wirelessly using ultrasound at several frequencies between 0.75 and 3.0 MHz. Rechargeable implantable batteries of 35, 200 and 600 mA-hr were charged at rates of up to 0.75 C, where C is the charging rate (charging current/maximum battery charging current). Typically the intervening medium was one centimeter of a tissue mimicking liquid (TML), however some in vitro experiments have also been performed. Charging was accomplished at distances of up to 20 centimeters in water, and even through millimeters of plastic and centimeters of aluminum. Temperature measurements were made on both transmitting and receiving transducers, and in the TML. As expected there were significant increases in temperature at the higher charging currents. Experimentally we determined that the “overall efficiency” of the charging process, viz. E=(Ibatt*Vbatt)/(net electrical power)input, was closely correlated with the observed heating. That is, the lower the efficiency, the higher the input electrical power required, the more transducer heat was produced and conducted into and through the medium. The critical issues were the coupling of the transmitter and receiver to the medium, and the efficiency of conversion of the receiver output to charging power by the charging circuitry. These depend on the mechanical and electrical impedances, and we improved the efficiency considerable by appropriate impedance matching. Active and passive methods of cooling the transducers and intervening medium have been constructed and successfully tested. With our system, recharging times will be limited not by heating considerations, but only by the optimum rate at which a given battery can accept charge.
High-Density Transcranial Direct Current Stimulation (HD-tDCS): Hardware Interface
Authors: Diaz J. , Bansal V. , Datta A. , Patel J. , Bikson M.
Published: July 2009

Transcranial Direct Current Stimulation (tDCS) is a non-invasive procedure where a weak electrical current (260 μA to 2 mA) is applied across the scalp to modulate brain function. tDCS has been applied for therapeutic purposes (e.g., addiction, depression, mood and sleep disorders) as well as cognitive performance enhancement (e.g., memory consolidation, motor learning, language recall). Despite safety and cost advantages, the developments of tDCS therapies have been restricted by spatial targeting concerns using existing two-channel systems. We have developed novel technology for High-Density tDCS (HD-tDCS) that improves spatial focality. Our hardware interface integrates a multichannel stimulating guide with existing two channel tDCS stimulators, and can be configured to target specific brain regions using computational models of current flow and multichannel array accessories. The hardware interface provides real time stimulation quality and safety feedback, and is designed to be MRI and TMS compatible. An electrical “tickle” feature enables skin pre-conditioning to minimize sensation. The full system includes the hardware interface, cable assemblies, head gear, tDCS electrodes, tDCS gel, and electrode adaptors. The head gear allows fixing the electrode adaptors over cortical targets using conventional EEG electrode coordinates. The electrode adaptors “fin” design, tDCS gel composition, and electrode shape are optimized to reduce sensation during direct current stimulation with 2 mA for up to 22 minutes. A five electrode system (4×1-C1), for implementing optimally focal “4×1 ring configuration” protocols, and an 8 electrode system (4×4-S1), that can be configured for “4×4 cortical strip stimulation”, are available. The entire system is robust, intuitive, and ultimately adaptable for home use. Our HD-tDCS system allows non-invasive, safe, and targeted modulation of selected cortical structures for electrotherapies that are individualized as well as optimized for a range of therapeutic applications.
High-Density Transcranial DC Stimulation (HD-tDCS): Targeting Software
Authors: Datta A. , Bansal V. , Diaz J. , Patel J. , Oliveira L. , Reato D. , Bikson M.
Published: July 2009

Transcranial Direct Current Stimulation (tDCS) is a non-invasive procedure where a weak electrical current (260 μA to 2 mA) is applied across the scalp to modulate brain function. tDCS has been applied for therapeutic purposes (e.g., addiction, depression, mood and sleep disorders) as well as cognitive performance enhancement (e.g., memory consolidation, motor learning, language recall). Despite safety and cost advantages, the developments of tDCS therapies have been restricted by spatial targeting concerns using existing two-channel systems. We have developed novel technology for High-Density tDCS (HD-tDCS) that improves spatial focality. To determine optimal stimulation electrode configurations, based on application specific constraints, we developed a HD-tDCS targeting software. High resolution (gyri/sulci precise) MRI derived finite element (FE) human head models are generated by segmenting grey matter, white matter, CSF, skull, muscle, fatty tissue, eyes, blood vessels, scalp, etc. The models comprised >10 million elements with >15 million degrees of freedom. The induced cortical electric field/current density values are calculated; activation of either radially and tangentially oriented neuronal structures are considered. Our HD-tDCS hardware (4×1-C1, 4×4-S1) currently supports the ‘4×1-Ring’ and the ‘4×4-Strip’ electrode configurations. The peak cortical electric field was matched to ‘conventional’ large rectangular-pad tDCS stimulation; however, the spatial focality was significantly enhanced by 4×1 configuration. Using patient specific head models, our software interface allows simple and rapid screening of stimulation electrode configurations. After selecting a target region, clinicians can customize the electrode configuration to balance: 1) cortical surface and brain depth stimulation focality; 2) total applied current/voltage; and 3) electrode/scalp current density. Our HD-tDCS system allows non-invasive, safe, and targeted modulation of selected cortical structures for electrotherapies that are individualized as well as optimized for a range of therapeutic applications.
Novel Photoinitiated Nitric Oxide Releasing Compounds for More Biocompatible Coatings on Blood and Tissue Contacting Medical Devices
Authors: Burgess B. M. , Gierke G. E. , Frost M. C.
Published: July 2009

Biomedical devices that contact blood and tissue universally inspire a host response that often compromises the function of the device (i.e., intravascular sensors become coated with thrombi, artificial vascular grafts become coated with thrombi, artificial vascular grafts become occluded with thrombus formation and neointimal hyperplasia). Nitric oxide (NO) has been shown to be a potent inhibitor of platelet adhesion and activation and has been implicated in mediating the inflammatory response and promoting would healing. We are currently developing NO-releasing compounds based on S-nitrosothiols derived from substituted aromatic compounds that utilize light as an external on/off trigger capable of releasing precisely controlled surface fluxes of NO. The level of NO generated is dependent on the wavelength and intensity of light shown on the compounds. Data will be presented that show the synthesis and NO-release properties of three novel compounds, S-nitroso-2-methoxybenzene, S-nitroso-3-methoxybenzene and S-nitroso-2-chlorobenzene. Ultimately, these compounds will be tethered to the surface of polymer fillers that will then be blended into hydrophobic polymers and used as coatings on biomedical devices. A model system that will be used to demonstrate the utility of this approach will be a multi-element fiber optic sensors that will contain sensing elements capable of measuring blood gases and NO-releasing fibers that locally generate enough NO to inhibit clot formation on the sensor surface, thus allowing the sensor to function reliably in vivo.
Development of a Pedal Powered Wheelchair
Authors: Dix R. , Pal R. , Brown D. A. , Makhous M.
Published: July 2009

A first student project to put pedals on a wheelchair for exercise and propulsion was unsuccessful. The need remained and in June of 2005 the “Eureka” event occurred. Seeing a five-year-old on her training-wheel-equipped bicycle suggested that a fifth wheel could be added in the center between the wheelchair's two large rear wheels, and a mast supported by the fifth wheel's axle could extend forward to support a front axle and pedal set. A chain drive completed the propulsion system. There are no pedal-powered wheelchairs currently on the market. Around 2001 a product (EZChair) without retractable pedals was on the market but withdrawn. A team at the University of Buffalo invented and patented a pedal-powered wheelchair in 1993 (US Patent 5,242,179), but it was not commercialized. Also, a Japanese company designed and built a series of fifth-wheel wheelchair designs. Between 2006 and late 2008 we built many prototypes incorporating geometries that permitted retracting the pedal. For compactness a “Pedalong” with three telescoping tubes was built but it proved impossible to secure tightly. In the next design twin telescoping tubes passing above and to the rear of the rear axle provided the desired extension. A clamp at the front of the outer tube provided tightness of the assembly. In the Northwestern research program (see below), there was some success, but awkwardness in operation prevented commercialization. In October 2008 a major design change from a fifth wheel in the center to a powering of the two standard rear wheels was begun. This required a new chain path geometry and addition of a differential to the drive train. With the new design user control, arm-powering and braking through the rear wheels is retained, and chair stability is improved. Twelve individuals with chronic post-stroke hemiplegia (>6 months post-stroke event) participated in a study to examine the metabolic energy expended when participants performed a 6-minute walk test, a 6 minute leg-propelled wheelchair trial (using the Pedalong), and a 6 minute arm-propelled wheelchair trial. VO2, VCO2, and distance traveled were measured using a portable metablic cart system and wheel-based distance measurement system. The Pedalong and walking trials showed equivalent oxygen consumption levels, but manual pushing was, on average, significantly less. All three modes (walking, leg-propelled and arm-propelled) resulting in similar distances traveled within the 6 minute period. The leg-propelled trials generated the greatest amount of VCO2 during expiration compared with the other modes. This means that more of the available oxygen is being utilized (metabolized) during the leg-propelled mode and so, a greater number of calories were being burned during this 6-minute test.