bluuebunny/crossref_metadata_2025 huggingface dataset:
Risk factors for morbidities in laparoscopic appendectomy for acute appendicitis of paediatric patients
Authors: Chung Patrick Ho‐Yu , Chan Kwong‐Leung , Tam Paul Kwong‐Hang
Published: July 2009

Aim:  Laparoscopic appendectomy has been the treatment of choice for acute appendicitis in children for many years. The aim of the present study was to analyze factors that are associated with morbidities of this operation and make recommendations to the management protocol.

Methods:  This is a single‐centre study and the study period lasted from January 2002 to June 2007. The medical records of all paediatric patients undergoing emergency laparoscopic appendectomy were reviewed retrospectively. Demographic data, symptoms on presentation, operative findings, duration of operation and antibiotics used were noted. The outcome measures included conversion rate, early and late complication rates as well as duration of total hospital stay. Statistical analysis was done by SPSS version 15.0.

Results:  A total of 61 emergency laparoscopic appendectomies were carried out during the study period. About two‐thirds of the patients were male. Thirty‐nine patients were aged 13–18 years. The most common presenting symptoms were lower abdominal pain (83.6%) and fever (95.1%). The overall complication rate was 32.8%. After statistical analysis, late presentation (onset of symptoms for more than 3 days) and appendicitis with perforation were found to be risk factors for perioperative morbidities.

Conclusion:  Late presentation and perforated appendicitis were associated with high complication rates in emergency laparoscopic appendectomy. Parents of the patients should be informed about this before operation. The possibility of using alternative management in these situations can be considered.
Quantifying the heart of darkness with GHALO – a multibillion particle simulation of a galactic halo
Authors: Stadel J. , Potter D. , Moore B. , Diemand J. , Madau P. , Zemp M. , Kuhlen M. , Quilis V.
Published: July 2009

We perform a series of simulations of a Galactic mass dark matter halo at different resolutions: our largest uses over 3 billion particles and has a mass resolution of 1000 M⊙. We quantify the structural properties of the inner dark matter distribution and study how they depend on numerical resolution. We can measure the density profile to a distance of 120 pc (0.05 per cent of Rvir), where the logarithmic slope is −0.8 and −1.4 at (0.5 per cent of Rvir). We propose a new two-parameter fitting function that has a linearly varying logarithmic density gradient over the resolved radii which fits the GHALO and VL2 density profiles extremely well. Convergence in the halo shape is achieved at roughly three times the convergence radius for the density profile at which point the halo becomes more spherical due to numerical resolution. The six-dimensional phase-space profile is dominated by the presence of the substructures and does not follow a power law, except in the central few kpc which is devoid of substructure even at this resolution. The quantity, ρ/σ3, which is often used as a proxy for the six-dimensional phase-space density should be used with caution.
A Forward Modeling Approach for Interpreting Impeller Flow Logs
Authors: Parker Alison H. , West L. Jared , Odling Noelle E. , Bown Richard T.
Published: July 2009

A rigorous and practical approach for interpretation of impeller flow log data to determine vertical variations in hydraulic conductivity is presented and applied to two well logs from a Chalk aquifer in England. Impeller flow logging involves measuring vertical flow speed in a pumped well and using changes in flow with depth to infer the locations and magnitudes of inflows into the well. However, the measured flow logs are typically noisy, which leads to spurious hydraulic conductivity values where simplistic interpretation approaches are applied. In this study, a new method for interpretation is presented, which first defines a series of physical models for hydraulic conductivity variation with depth and then fits the models to the data, using a regression technique. Some of the models will be rejected as they are physically unrealistic. The best model is then selected from the remaining models using a maximum likelihood approach. This balances model complexity against fit, for example, using Akaike's Information Criterion.
The “Three‐Step Test” and the Wider Public Interest: Towards a More Inclusive Interpretation
Authors: Wright Robin
Published: July 2009

Intellectual property law aims to protect the public interest in two often‐contradictory ways: by granting exclusive rights to encourage creativity and by limiting those rights in certain situations for socially beneficial purposes. The Three‐Step Test in international intellectual property treaties aims to ensure that limitations and exceptions to intellectual property rights do not inappropriately encroach upon the interests of rights holders. This article examines the interpretation of the Three‐Step Test as included in the Agreement on Trade‐Related Aspects of Intellectual Property Rights for copyright and patents by two World Trade Organization dispute‐resolution panels and by other commentators. It looks at how these interpretations have dealt with the public policy motivations underlying limitations and exceptions to exclusive rights, and considers the ways in which the public policy intentions that underlie decisions by national legislators to adopt the limitations and exceptions to intellectual property rights can be considered in each step of the test. The conclusion reached is that the Three‐Step Test contains the potential to allow both aspects of the public interest to be considered as part of an inclusive interpretation.
Shifting Authority: Teachers’ Role in the Bureaucratization of School Discipline in Postwar Los Angeles
Authors: Kafka Judith
Published: July 2009

In November of 1956, the Los Angeles City Board of Education held a regular evening meeting devoted entirely to the topic of school discipline. The session began with brief comments from the district superintendent, Ellis Jarvis, who urged those in attendance not to take the issue too seriously Discipline was “an inherent part of education,” he reminded them, and thus was always “a problem of all schools; all schools in this city, in every city, in every community.” Moreover, he joked, “Denunciation of the young is a necessary part of the hygiene of older people, and greatly assists in the circulation of their blood.” The rest of the meeting's speakers, however, almost all of whom were Los Angeles teachers, did not share Jarvis’ lighthearted perspective. Representing several local teacher organizations, clubs, and associations, as well as two Board-appointed committees charged with investigating discipline in the city's schools, they portrayed a district in crisis, overrun by misbehaving youth, and urged the Board to take action to address the problem.
Melodic Contour Identification and Music Perception by Cochlear Implant Users
Authors: Galvin John J. , Fu Qian‐Jie , Shannon Robert V.
Published: July 2009

Research and outcomes with cochlear implants (CIs) have revealed a dichotomy in the cues necessary for speech and music recognition. CI devices typically transmit 16–22 spectral channels, each modulated slowly in time. This coarse representation provides enough information to support speech understanding in quiet and rhythmic perception in music, but not enough to support speech understanding in noise or melody recognition. Melody recognition requires some capacity for complex pitch perception, which in turn depends strongly on access to spectral fine structure cues. Thus, temporal envelope cues are adequate for speech perception under optimal listening conditions, while spectral fine structure cues are needed for music perception. In this paper, we present recent experiments that directly measure CI users’ melodic pitch perception using a melodic contour identification (MCI) task. While normal‐hearing (NH) listeners’ performance was consistently high across experiments, MCI performance was highly variable across CI users. CI users’ MCI performance was significantly affected by instrument timbre, as well as by the presence of a competing instrument. In general, CI users had great difficulty extracting melodic pitch from complex stimuli. However, musically experienced CI users often performed as well as NH listeners, and MCI training in less‐experienced subjects greatly improved performance. With fixed constraints on spectral resolution, such as occurs with hearing loss or an auditory prosthesis, training and experience can provide considerable improvements in music perception and appreciation.
The Role of Auditory and Premotor Cortex in Sensorimotor Transformations
Authors: Chen Joyce L. , Penhune Virginia B. , Zatorre Robert J.
Published: July 2009

This review first summarizes three functional magnetic resonance imaging studies conducted to elucidate the neural basis for interactions between the auditory and motor systems in the context of musical rhythm perception and production. The second part of the paper discusses these findings in the context of a proposed model for auditory–motor interactions that engage the posterior aspects of the superior temporal gyrus, and the ventral and dorsal premotor cortex. In the last section, we present outstanding issues that encompass topics, such as the role of auditory versus parietal cortex in sensorimotor integration, sensorimotor integration as an emergent property, the role of mirror neurons, and clinical applications.
Top‐Down Control of Rhythm Perception Modulates Early Auditory Responses
Authors: Iversen John R. , Repp Bruno H. , Patel Aniruddh D.
Published: July 2009

Our perceptions are shaped by both extrinsic stimuli and intrinsic interpretation. The perceptual experience of a simple rhythm, for example, depends upon its metrical interpretation (where one hears the beat). Such interpretation can be altered at will, providing a model to study the interaction of endogenous and exogenous influences in the cognitive organization of perception. Using magnetoencephalography (MEG), we measured brain responses evoked by a repeating, rhythmically ambiguous phrase (two tones followed by a rest). In separate trials listeners were instructed to impose different metrical organizations on the rhythm by mentally placing the downbeat on either the first or the second tone. Since the stimulus was invariant, differences in brain activity between the two conditions should relate to endogenous metrical interpretation. Metrical interpretation influenced early evoked neural responses to tones, specifically in the upper beta range (20–30 Hz). Beta response was stronger (by 64% on average) when a tone was imagined to be the beat, compared to when it was not. A second experiment established that the beta increase closely resembles that due to physical accents, and thus may represent the genesis of a subjective accent. The results demonstrate endogenous modulation of early auditory responses, and suggest a unique role for the beta band in linking of endogenous and exogenous processing. Given the suggested role of beta in motor processing and long‐range intracortical coordination, it is hypothesized that the motor system influences metrical interpretation of sound, even in the absence of overt movement.
Broca's Area in Language, Action, and Music
Authors: Fadiga Luciano , Craighero Laila , D’Ausilio Alessandro
Published: July 2009

The work of Paul Broca has been of pivotal importance in the localization of some higher cognitive brain functions. He first reported that lesions to the caudal part of the inferior frontal gyrus were associated with expressive deficits. Although most of his claims are still true today, the emergence of novel techniques as well as the use of comparative analyses prompts modern research for a revision of the role played by Broca's area. Here we review current research showing that the inferior frontal gyrus and the ventral premotor cortex are activated for tasks other than language production. Specifically, a growing number of studies report the involvement of these two regions in language comprehension, action execution and observation, and music execution and listening. Recently, the critical involvement of the same areas in representing abstract hierarchical structures has also been demonstrated. Indeed, language, action, and music share a common syntactic‐like structure. We propose that these areas are tuned to detect and represent complex hierarchical dependencies, regardless of modality and use. We speculate that this capacity evolved from motor and premotor functions associated with action execution and understanding, such as those characterizing the mirror‐neuron system.
“With Concord of Sweet Sounds…”
Authors: Heaton Pamela , Allen Rory
Published: July 2009

Questions about music's evolution and functions have long excited interest among scholars. More recent theoretical accounts have stressed the importance of music's social origins and functions. Autism and Williams syndrome, neurodevelopmental disorders supposedly characterized by contrasting social and musical phenotypes, have been invoked as evidence for these. However, empirical data on social skills and deficits in autism and Williams syndrome do not support the notion of contrasting social phenotypes: research findings suggest that the social deficits characteristic of both disorders may increase rather than reduce the importance of music. Current data do not allow for a direct comparison of musical phenotypes in autism and Williams syndrome, although it is noted that deficits in music cognition have been observed in Williams syndrome, but not in autism. In considering broader questions about musical understanding in neurodevelopmental disorders, we conclude that intellectual impairment is likely to result in qualitative differences between handicapped and typical listeners, but this does not appear to limit the extent to which individuals can derive benefits from the experience of listening to music.
Auditory‐Somatosensory Integration and Cortical Plasticity in Musical Training
Authors: Pantev Christo , Lappe Claudia , Herholz Sibylle C. , Trainor Laurel
Published: July 2009

Learning to play a musical instrument requires complex multimodal skills involving simultaneous perception of several sensory modalities: auditory, visual, and somatosensory as well as the motor system. Musical training thus provides an adequate neuroscientific model to study multimodal integration and plasticity in musical training. The aim of this study was to investigate the impact of short‐term uni‐ and multimodal musical training on auditory‐somatosensory integration and plasticity. Two groups of nonmusicians were musically trained. The first group (sensorimotor‐auditory group, SA) learned to play a musical sequence on the piano, whereas the second one (auditory group, A) actively listened to and made judgments about the correctness of the music. The training‐induced cortical plasticity effect was assessed by recording musically elicited mismatch negativity (MMN) from magnetoencephalographic (MEG) measurements before and after training. The SA group showed significant enlargement of MMN after training compared to the A group, reflecting greater enhancement of musical representations in auditory cortex after sensorimotor‐auditory training compared to mere auditory training. This study demonstrates that the sensorimotor and auditory systems integrate and that this multimodal training causes cortical reorganizational changes in the auditory cortex over and above the changes introduced by auditory training alone.
Understanding the Benefits of Musical Training
Authors: Trainor Laurel J. , Shahin Antoine J. , Roberts Larry E.
Published: July 2009

A number of studies suggest that musical training has benefits for other cognitive domains, such as language and mathematics, and studies of children and adults indicate structural as well as functional differences between the brains of musicians and nonmusicians. The induced gamma‐band response has been associated with attentional, expectation, memory retrieval, and integration of top‐down, bottom‐up, and multisensory processes. Here we report data indicating that the induced gamma‐band response to musical sounds is larger in adult musicians than in nonmusicians and that it develops in children after 1 year of musical training beginning at age 41/2 years, but not in children of this age who are not engaged in musical lessons. We conclude that musical training affects oscillatory networks in the brain associated with executive functions, and that superior executive functioning could enhance learning and performance in many cognitive domains.
Amusia and Cognitive Deficits after Stroke
Authors: Särkämö Teppo , Tervaniemi Mari , Soinila Seppo , Autti Taina , Silvennoinen Heli M. , Laine Matti , Hietanen Marja
Published: July 2009

We studied the relationship between musical and cognitive deficits by testing middle cerebral arterial (MCA) stroke patients (n= 53) with a shortened version of the Montreal Battery of Evaluation of Amusia (MBEA) and an extensive neuropsychological test battery. Results showed that amusic patients (n= 32) had more severe cognitive deficits, especially in working memory and executive functioning, than did non‐amusic patients (n= 21), and the severity of amusia also correlated with attention deficits. These findings thus suggest that domain‐general attention, executive, and working memory processes are associated with amusia after stroke.
Integrated Preattentive Processing of Vowel and Pitch
Authors: Lidji Pascale , Jolicœur Pierre , Moreau Patricia , Kolinsky Régine , Peretz Isabelle
Published: July 2009

This study examines the additivity of the Mismatch Negativity (MMN) as an index of the early interactions between vowels and pitch when sung. Event‐related potentials (ERPs) were recorded while participants were presented with sung vowels. Sixteen percent of stimuli deviated in pitch only, in vowel only, or in both pitch and vowel. All three kinds of deviants elicited an MMN of similar amplitude. The MMNs to vowel and pitch deviants did not show significant additivity. This suggests that vowel and pitch are processed by shared neural substrates at the preattentive level.
A Protocol for Cross‐Cultural Research on the Acquisition of Singing
Authors: Cohen Annabel J. , Armstrong Vickie L. , Lannan Marsha S. , Coady Jenna D.
Published: July 2009

As part of a major collaborative research initiative, Advancing Interdisciplinary Research in Singing (AIRS), we developed a protocol for obtaining audiovisual information reflecting aspects of the ability to sing. We also developed a digital library prototype, the Children's International Media Exchange for Singing (CHIMES), to index and store the data for access through the Internet by researchers worldwide. The protocol was piloted at five monthly intervals with 20 individuals (children 3, 5, and 7 years of age and adults differing in vocal training level), validating its feasibility in Western culture and producing rich data amenable to numerous levels and kinds of analysis.
Reducing Linguistic Information Enhances Singing Proficiency in Occasional Singers
Authors: Berkowska Magdalena , Dalla Bella Simone
Published: July 2009

In this study we examined the effect of reducing linguistic information on singing proficiency in occasional singers. Thirty‐nine occasional singers were asked to sing from memory and to imitate three familiar melodies with lyrics and on the syllable /la/. Performances were analyzed with an acoustically based method yielding objective measures of pitch and temporal accuracy. Results obtained in production and imitation tasks revealed increased accuracy (e.g., fewer pitch interval errors and contour errors) when occasional singers produced melodies on a syllable as compared to singing with lyrics. This effect may be the result of reduced memory load and/or motor entrainment.
Therapeutic Role of Music Listening in Stroke Rehabilitation
Authors: Forsblom Anita , Laitinen Sari , Särkämö Teppo , Tervaniemi Mari
Published: July 2009

We performed two parallel interview studies of stroke patients (n= 20) and professional nurses (n= 5) to gain more insight into the therapeutic role of music listening in stroke rehabilitation. Results suggest that music listening can be used to relax, improve mood, and provide both physical and mental activation during the early stages of recovery from stroke. Thus, music listening could provide a useful clinical tool in stroke rehabilitation.
Beta and Gamma Rhythms in Human Auditory Cortex during Musical Beat Processing
Authors: Fujioka Takako , Trainor Laurel J. , Large Edward W. , Ross Bernhard
Published: July 2009

We examined β‐ (∼20 Hz) and γ‐ (∼40 Hz) band activity in auditory cortices by means of magnetoencephalography (MEG) during passive listening to a regular musical beat with occasional omission of single tones. The β activity decreased after each tone, followed by an increase, thus forming a periodic modulation synchronized with the stimulus. The β decrease was absent after omissions. In contrast, γ‐band activity showed a peak after tone and omission, suggesting underlying endogenous anticipatory processes. We propose that auditory β and γ oscillations have different roles in musical beat encoding and auditory–motor interaction.
Chills As an Indicator of Individual Emotional Peaks
Authors: Grewe Oliver , Kopiez Reinhard , Altenmüller Eckart
Published: July 2009

Chills (goose bumps) have been repeatedly associated with positive emotional peaks. Chills seem to be related to distinct musical structures and the reward system in the brain. A new approach that uses chills as indicators of individual emotional peaks is discussed. Chill reactions of 95 participants in response to seven music pieces were recorded. Subjective intensity as well as physiological arousal (skin conductance response, heart rate) revealed peaks during chill episodes. This review suggests that chills are a reliable indicator of individual emotional peaks, combining reports of subjective feelings with physiological arousal.
Motor/Autonomic Stress Responses in a Competitive Piano Performance
Authors: Yoshie Michiko , Kudo Kazutoshi , Ohtsuki Tatsuyuki
Published: July 2009

The present study examined the effects of psychological stress on performance quality, autonomic responses, and upper extremity muscle activity in skilled pianists through comparisons between stressful (competition) and nonstressful (rehearsal) conditions. We observed increased levels of subjective anxiety, autonomic arousal, and electromyographic activity in the competition condition, which could contribute to the impairment of performance quality. The results provide important practical implications for enhancing performance quality as well as preventing playing‐related musculoskeletal disorders in musicians.
Long‐term Effects of Auditory Training in Severely or Profoundly Deaf Children
Authors: Rochette Françoise , Bigand Emmanuel
Published: July 2009

Despite new technological advances in the rehabilitation of audition in profoundly deaf children, auditory training remains a fundamental part of their education. Consequently, it is necessary to learn what kind of stimuli, what kind of auditory tasks, and what kind of learning procedures generate faster and more long‐lasting benefits. The present study evaluates a training program that includes numerous nonlinguistic stimuli that tap into several means of cognitive processing. The program is based on an implicit learning procedure and was tested with six severely or profoundly deaf children. The first results demonstrate an improvement in nonlinguistic performances on both accuracy and processing times. These results were evident immediately after the auditory training, and most of the effects remains stable 6 months later. Moreover, the children show a better discrimination of linguistic sounds. These results open the possibility of new approaches in speech therapy.
A New Approach to Rhythm Cueing of Cognitive Functions
Authors: Bernardi Nicolò F. , Aggujaro Silvia , Caimmi Marco , Molteni Franco , Maravita Angelo , Luzzatti Claudio
Published: July 2009

Although positive effects of rhythm cueing on motor control in neurologic disorders are known, no studies have yet focused on patients suffering from impaired programming of complex actions. One patient suffering from ideomotor apraxia (a potentially ideal experimental paradigm to test the effect of rhythm on high‐level motor control) underwent two rehabilitation training sets differing only for the presence or absence of rhythm cueing. Both sets of training increased the patient's proficiency, but rhythm cueing was significantly more effective, during the training as well as during the post‐training uncued test. Ideomotor apraxia represents an effective model to test the effects of rhythm on high‐level motor control.
The Birth of Musical Emotion
Authors: Dellacherie Delphine , Pfeuty Micha , Hasboun Dominique , Lefèvre Julien , Hugueville Laurent , Schwartz Denis P. , Baulac Michel , Adam Claude , Samson Séverine
Published: July 2009

Intracranial electroencephalography was recorded in an epileptic patient when he was listening to dissonant and consonant chords and to minor and major chords. Changes in dissonance induced event‐related potentials (ERPs) in the auditory areas from 200 ms onward, in the orbito‐frontal cortex (500–1000 ms), and later in the amygdala and anterior cingulate gyrus (1200–1400 ms), suggesting the sequential involvement of these brain structures in implicit emotional judgment of musical dissonance. Changes in musical mode induced ERPs only in the orbito‐frontal cortex (500–1000 ms), emphasizing the implication of this frontal region in emotional judgment of pleasant music.
Carney complex and lentiginosis
Authors: Horvath Anelia , Stratakis Constantine A.
Published: July 2009

Initially described as the ‘complex of myxomas, spotty skin pigmentation and endocrine overactivity,’ Carney complex (CNC) is known as an autosomal dominant multiple neoplasia syndrome involving skin and cardiac myxomas, pigmented skin lesions and endocrine tumors. Pigmented cutaneous manifestations in CNC are important diagnostically because they can be used for the early detection of the disease and, thus, the prevention of life‐threatening complications of CNC related to heart myxomas and endocrine abnormalities. Specific for the disease skin lesions are present in more than half of the CNC patients. A major challenge is to distinguish pigmented skin lesions associated with CNC from other skin pathology, and thus accurately estimate the risk of cancer in affected patients; curiously, patients with CNC do not appear to have predisposition to skin cancers whereas this is not the case with other genetic syndromes associated with melanotic and other cutaneous lesions. In this paper, we review the current knowledge on cutaneous pathology associated with CNC and the most recent data on the molecular basis of the disease.
Aerodynamic Performance of Blade Tip End-Plates Designed for Low-Noise Operation in Axial Flow Fans
Authors: Corsini Alessandro , Rispoli Franco , Sheard A. G.
Published: July 2009

This study assesses the effectiveness of modified blade-tip configurations in achieving passive noise control in industrial fans. The concepts developed here, which are based on the addition of end-plates at the fan-blade tip, are shown to have a beneficial effect on the fan aeroacoustic signature as a result of the changes they induce in tip-leakage-flow behavior. The aerodynamic merits of the proposed blade-tip concepts are investigated by experimental and computational studies in a fully ducted configuration. The flow mechanisms in the blade-tip region are correlated with the specific end-plate design features, and their role in the creation of overall acoustic emissions is clarified. The tip-leakage flows of the fans are analyzed in terms of vortex structure, chordwise leakage flow, and loading distribution. Rotor losses are also investigated. The modifications to blade-tip geometry are found to have marked effects on the multiple vortex behaviors of leakage flow as a result of changes in the near-wall fluid flow paths on both blade surfaces. The improvements in rotor efficiency are assessed and correlated with the control of tip-leakage flows produced by the modified tip end-plates.
A New System for Monitoring Gait Training in Infants With Down Syndrome
Authors: Portnoy Sigal , Gefen Amit , Ohana Assaf , Yizhar Ziva
Published: July 2009

Infants with Down syndrome show an altered pattern of motor development at early childhood. Treadmill-walking training can be used to promote the earlier attainment of motor milestones in infants with locomotion deficiencies but quantitative data on their motor development are limited to gait laboratory studies. Our purpose was to develop, validate, and test a low-cost portable system for detecting infant steps on a treadmill while training. The system includes five infrared distance sensors, which were placed on a motorized treadmill to record the location of the feet of the infant during walking and thus measure his/her step length and cadence. The system was validated using synthetic objects, with a healthy 13-month-old infant. Pilot studies were then conducted in additional five infants with Down syndrome (aged 11–28 months) to determine step length (17.5–22.3 cm) and cadence (0.33–2.16 steps/s) at baseline, as well as at follow-ups 1 month and 3 months after the first trial. Measurements were repeatable per session and agreed with values reported in the literature. These pilot studies indicate the potential utility of the present system in quantitative monitoring of the process of acquisition of initial gait in infants with Down syndrome at the care facility where routine therapy is given.
The Therapress 1600i: Accelerating Knee Rehabilitation
Authors: Geronimo A. , Holyoak M. , Oliver M. , Scherm E. , Paliwal M.
Published: July 2009

Objective: To design a ‘smart’ leg press machine that improves upon current rehabilitative practices for degenerative knee disorders such as osteoarthritis as well as injury induced knee pathologies. As its design entails, the machine provides rehabilitative assistance through strength training of upper leg muscles, with focus on the vastus medialis and vastus lateralis of the quadriceps group. The Therapress is designed to further improve the rate and quality of joint rehabilitation. The TP1600i is unique to current physical therapy practices because it incorporates three documented and proven strategies to combat quadriceps weakness: strength training, electrotherapy, and biofeedback [1,2]. The machine is designed to aid the user in regaining lost quadriceps strength, a condition indicative of poor knee health [3]. The machine incorporates a novel package of biofeedback, automated continuous variable resistance, and progress assessment, while maintaining subject specificity. The Therapress system utilizes a LabVIEW interface, which acquires and processes physiological signals recorded from the subject, as well as serves as a controller for output. These signals include surface electromyography (EMG) of the quadriceps, reaction forces at the foot (an indirect measurement of exercise resistance), and knee range of motion (ROM). Additionally, the subject is outfitted with stimulatory electrodes which function to characterize muscle recruitment using the Central Activation Ratio (CAR), as well as to therapeutically excite the muscle and induce accelerated hypertrophy [4]. Automated continuous variable resistance is achieved through a resistive hydraulic cylinder, which utilizes a servo motor to change the orifice size of partially overlapping valves during and between exercise sets. The resistance is adjusted based on user input of exertion and pain levels into the LabVIEW interface. The footplate of the machine houses four force sensing units to measure the resistance offered by the cylinder. A biofeedback arm attached to the system provides the subject with real-time data of their performance, including integrated EMG activity, ROM, and force production. Inclusion of biofeedback in quadriceps exercise regimens has been shown to increase strength gain [2]. The design allows the user to be in control of the exercise intensity at all times, while the machine works to maximize the efficacy of the protocol. The TP1600i is designed as a cost effective and time efficient alternative for the rehabilitation of debilitating knee disorders in a physical therapy protocol, and its ease of operation may qualify it for home use as well.
Real-Time, In Vivo Measurement of Contact Pressures at a Knee Arthroplasty
Authors: Pereles B. , Tan E. , Ong K.
Published: July 2009

There is a need to measure contact pressures at the femoral component and tibia plate of a knee arthroplasty implant to determine the wear and tear of the polyethylene (PE) insert of the implant. Today, most pressure monitoring systems for knee arthroplasty implants are either limited to in vitro or intraoperative use, or cannot measure contact pressures at the polyethylene surface. Here, we are developing a wireless passive sensor system for measuring the contact pressure at the knee arthroplasty in vivo. The sensor system is made of a pressure-sensitive magnetic layer embedded under the top surface of a PE insert used for mapping the contact pressures with the femoral components. The pressure-sensing layer consists of a grid of pressure and stress sensitive magnetoelastic thin strips that alter their magnetic properties with applied force. Measurements are taken at pressure points located at the crossings of the grid. The magnetization of each sensing strip is remotely measured by using an AC magnetic field to excite the material to generate higher-frequency fields, which are then detected through external detection coils. The responses of these sensing strips are fed into an algorithm to determine the pressure loadings at all pressure points, which allows for real-time, in vivo determination of pressure profiles on the PE insert. By using an array of magnetoelastic sensing strips, we have demonstrated the remote detection of pressure across a surface. The 2nd order harmonic amplitude of a 30 mm×1.5mm magnetoelastic strip decreased linearly with increasing pressure. For this sensing strip, the rate of decrease was about 0.1 (normalized to unstressed signal level) per 200 kPa. An algorithm was also developed to determine the pressures at all pressure points from the responses of the sensing strips. Experimental results have shown that the algorithm can accurately map the pressure profile of a 3×3 sensing strip array. Further works include developing a fabrication process for safely embedding the sensing strips into a PE insert, and modifying the algorithm for a larger sensing strip array.
Aiming a Surgical Laser With an Active Cannula
Authors: Rucker D. C. , Croom J. M. , Webster R. J.
Published: July 2009

An active cannula is a surgical device capable of dynamically changing its curved shape in response to rotation and translation of the several precurved, concentric, superelastic tubes from which it is made. As the tubes move with respect to one another in response to input motion at their bases (outside the patient), they elastically interact, causing one another to bend. This bending can be harnessed to direct the cannula through winding trajectories within the human body. An active cannula has the potential to perform a wide range of surgical tasks, and it is especially well suited for guiding and aiming an optical fiber (e.g. BeamPath from OmniGuide, Inc.) for laser ablation. Controlling the trajectory of the laser requires control of the shape of the active cannula, and in particular the position and orientation of its tip. Prior work has shown that beam mechanics can be used to describe the shape of the cannula, given the translations and axial angles of each tube base. Here, in order to aim the laser, we invert this relationship (obtaining the “inverse kinematic”), solving for the translations and axial angles of each tube, given a desired position and orientation of the cannula tip. Experimental evaluation of inverse kinematics was carried out using a prototype consisting of three tubes. The outermost tube is straight and rigid (stainless steel), with an outer diameter (OD) of 2.4 mm. The 1.8 mm OD middle tube is superelastic Nitinol, with a preshaped circular tip. The 1.4 mm OD innermost tube is Nitinol and is not precurved, representing the straight trajectory of a laser emanating from the tip of the cannula. We assessed the accuracy of the inverse kinematics by computing the necessary tube translations and rotations needed to direct the beam of the “laser” to sequential locations along a desired trajectory consisting of two line segments that meet at a corner. These inputs were then applied at tube bases to direct the laser to thirty points along the trajectory on a flat surface 100 mm away the cannula base. The position of the tip of the simulated laser was measured using an optical tracker (Micron Tracker H3-60, Claron, Inc.). Mean error between desired and actual positions was 3.1 mm (maximum 5.5 mm). This experiment demonstrates proof of concept for laser guidance, and establishes the accuracy of the inverse kinematic model. We note that these results are applicable to guidance of a wide range of medical devices in addition to lasers. Relevant references, as well as images of our prototype and experimental data described here can be found in an online version of this abstract at http://research.vuse.vanderbilt.edu/MEDLab/. This work was supported by NSF grant #0651803, and NIH grant #1R44CA134169-01A1.
Vibrotactile Balance Rehabilitation Gait Assist Device
Authors: Vichare V. V. , Lee B. C. , Carender W. , Sienko K. H.
Published: July 2009

Visual, vibrotactile, and auditory cues have proven successful in numerous applications to supplement or in some cases completely replace missing sensory information. Sensory substitution using vibrotactile stimulation has been effective in improving postural stability during stationary tasks and tasks involving perturbed stance. The challenge increases, however, when designing a wearable device that provides meaningful information during a dynamic task such as walking. Techniques that directly apply the feedback strategies effective in stance (trunk tilt) to walking have largely proven ineffective (excluding heel-to-toe walking, which is essentially a series of standing balance tasks). We have demonstrated a device for correcting vestibulopathic gait using a novel feedback methodology that was co-developed with physical therapists specializing in balance rehabilitation. The device supplies vibrotactile cues based on factors during walking that are considered important by physical therapists, including gait velocity, stride length, and gaze. The device consists of three independent units, each consisting of an inertial measurement unit (IMU), vibrotactile display, and microprocessor. Head tilt (which approximates eye gaze), trunk tilt, stride length, and velocity are estimated by the IMUs and displayed to the patient in the form of vibrotactile cues on the head, trunk, and tibia, respectively. Algorithms were developed to estimate stride length and gait velocity in real time from measured heel-strike and toe-off events. Feedback of the head pitch angle is provided continuously to the subject, while gait velocity and stride length feedback are provided during heel strike events only. Preliminary results demonstrate that healthy subjects can interpret this feedback to correct their head pitch and adjust their stride length and gait velocity.
A Novel Combination Therapy for Post-Operative Arrhythmias
Authors: Richardson E. S. , Whitson B. A. , Iaizzo P. A.
Published: July 2009

Atrial fibrillation (AF) is a common heart rhythm disorder, effecting about 20% of cardiac surgical patients. While often benign, it leads to a prolonged hospital stay, and potentially to malignant arrhythimas. Many anti-arrhythmic drugs have been used to both prevent and treat post-operative AF and other post-operative arrhythmias; however, they have potentially harmful side-effects (e.g., hypotension, pulmonary fibrosis). Cardioversion is often the therapy of last resort to restore a perfusable rhythm. We propose a novel, innovative concept that allows for local pharmacological and electrical therapy of the heart. We have shown in animal models that such delivery increases the efficacy of the therapy and reduces side effects. Several variations of the device have been conceived and prototypes are currently being developed. The simplest version is a multi-port infusion catheter incorporated into a temporary pacing lead. Placement of the device would be trivial for surgeons, who routinely place temporary pacing leads prior to closing the chest. Removal of the device post-operatively would be equally simple. More complex iterations include an expandable wick to maintain the infused drug in a desired location. Designs may also include epicardial defibrillation capabilities, which would lower the energy required for defibrillation. To demonstrate proof of principle, cadaver and animal investigations were performed. In a fresh cadaver, a sternotomy and pericardiotomy was performed. A catheter was placed in the pericardium, and an infusion of radio-opaque contrast was administered under fluoroscopy. The majority of the contrast collected near the pulmonary veins, which are often the origin of atrial arrhythmias. To evaluate the efficacy of drugs administered into the pericardium as compared with drugs administered through the conventional route (intravenously), animal studies in swine were performed. Results demonstrated that pericardially administered metoprolol had a greater and more lasting effect on heart rate than when given intravenously. Additionally, during pericardial delivery myocardial contractility was better preserved. Only trace amounts of metoprolol were found in the circulation. Thus pericardial delivery may enhance certain therapeutic effects of drugs while limiting side effects. Currently, studies are underway to evaluate the efficacy other pharmacologic agents delivered into the pericardium. Should our animal studies continue to show promising results, we anticipate moving into clinical trials. Development and refinement of prototype delivery devices will also continue as we pursue this promising new therapy for post-operative arrhythmias.
Cell Motion in a Two-Stream Microfluidic Channel
Authors: Hanna J. , Darr T. B. , Hubel A. , Mata C. , Longmire E. K. , McKenna D. H.
Published: July 2009

Microfluidic channels have been proposed as a method for removal of cryoprotective agents from cell suspensions [Fleming, Longmire, and Hubel, J. Biomech. Eng. 129, 703 (2007)]. The device tested consists of a rectangular cross section channel of 500 μm depth, 25 mm width, and 160 mm length, through which a cell suspension and wash stream flow in parallel. Cryoprotective agents diffuse from the cell stream to the wash stream and the wash stream is discarded. The washed cell stream is then ready for use. This device must be capable of removing 95% of the dimethyl sulfoxide (DMSO) from the cell stream with minimal cell losses. Our previous studies have demonstrated our ability to remove DMSO [Mata, Longmire, McKenna, Glass, and Hubel, Microfluid. Nanofluid. 5, 529 (2008)]. The next phase of the investigation involves characterizing the influence of flow conditions on cell motion through the device. To that end, Jurkat cells (lymphoblasts) in a 10% DMSO solution were flowed through the microfluidic channel in parallel with a wash stream composed of phosphate buffered saline solution (PBS). Average cell stream velocities were varied from 0.94 to 8.5 mm/s (Re 1.7 to 6.0). Cell viability at the outlet was high, indicating that cells are not damaged during their passage through the device. Gravitational settling caused an accumulation of cells near the bottom of the channel, where flow velocities are low. Cell settling leads results in an initial transient period for cell motion through the device. For the initial portion of cells flowing through the device, cells tend to accumulate in the device until a critical device population time is reached. Cell recovery (number of cells out of the device divided by the number of cells input to the device) is high (90–100%) after the device has been fully populated. For a single stage device with average cell stream velocities of ⩾6 mm/s, cell recovery was 90–100%. As more stages are added to the device, the population time for the device increases. Gravitational settling of cells also leads to a time-varying cell concentration from the input syringe to the inlet of the channel, as well as cell losses due to cells remaining in the horizontally-oriented syringe. Reorienting the syringes to a vertical position eliminates these losses. Cell motion within the channel can be modulated by the flow conditions used. For sufficiently high Reynolds numbers, the Segre-Silberberg effect [Segre and Silberberg, J. Fluid Mech. 14, 115 (1962)] can be used to move cells from the low velocity region of the cell stream to a higher velocity region thereby reducing the transient portion of processing the cells and improving overall recovery of cells through the device.
Stimuli-Responsive Triblock Polymers for Multipulse Drug Delivery
Authors: Gaumet M. , Xi J. , Barriet D. , Siegel R. A.
Published: July 2009

Temperature and pH-sensitive ABC triblock polymers were prepared to form hydrogel membranes capable of changing their structure in response to environmental stimuli, allowing drug release, from a micro implantable device, in short and repetitive pulses. We have previously investigated the capacity of hydrogels to sustain open loop oscillatory behavior, with application in rhythmic hormone release. This novel oscillator is mediated by feedback instability between swelling/shrinking of the hydrogel and an enzyme reaction, whose product modifies pH in the hydrogel. The objective of this work was to prepare and characterize triblock polymer-based hydrogels, to overcome limitations of conventional hydrogels. Our strategy involves reversible arrangement of A and C thermosensitive domains within a strong network, whereas B block is also pH-sensitive. The triblock was mainly based on the use of NIPAAm (N, isopropylacrylamide) and AA (acrylic acid) monomers. Polymers were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization. Polymers molecular weight (Mn) and polydispersity index (PDI) were determined by matrix-assisted laser desorption ionization/mass spectrometry (MALDI). Monomers conversion was assessed by NMR and copolymers composition by NMR and pH-titration. Temperature and pH responsiveness was studied by turbidity and light scattering experiments. ABC triblock presented Mn close to 40,000 Da and was nearly monodisperse (PDI<1.1). The monomers conversion was 92%, 97% and 39% for A, B and C blocks, respectively. The opposing effects of hydrophobicity and ionization on the aggregation behavior of the diblock have been highlighted through the turbidity and light scattering data. AB diblock cloud points were 32, 34, 35.5 and 37°C for 3, 5, 10 and 20% of AA, respectively. Micelles or aggegrates were observed depending on pH and temperature. ABC triblock polymers with controlled architecture and Mn distribution were synthesized and fully characterized. The results suggest that these block polymers are promising materials for stimul-responsive hydrogel membranes applied to medical devices. Work supported by the Swiss National Fund for Scientific Research and an NSF-funded MRSEC (DMR#0819885) at the University of Minnesota.