Biomedical Engineering

This work concerns a deterministic and stochastic model describing the transmission of typhoid fever infection in human host community, where the vaccination of susceptible births and immigrants as well as screening and treatment of carriers and infected individuals are considered in the model build -up. The well-posedness and computation of the basic reproduction number 𝑅𝑅 𝑡𝑦𝑝𝑝 of the deterministic model are obtained and analysed. The deterministic model is further transformed into a stochastic model, where the drift and diffusion parts of the model are obtained, and the existence and uniqueness of the stochastic model are discussed. Numerical simulations involving the model parameters of 𝑅𝑅 𝑡𝑦𝑝𝑝 showed that vaccination of susceptible births and influx of immigrants as well as screening and treatment of carriers and infected humans are effective in bringing the threshold 𝑅𝑅 𝑡𝑦𝑝𝑝 (𝑅𝑅 𝑡𝑦𝑝𝑝 ≈ 0.7944) below 1, and the results of other simulations suggest more health policies are to be implemented, as low 𝑅𝑅 𝑡𝑦𝑝𝑝 may not be guaranteed because vaccination wanes over time. In addition, the numerical simulations of the stochastic model equations describing the sub -population of human individuals in the total human host community are carried out using the computational software MATLAB.

The Ca 2 + signaling system in an established immortalized rat parotid acinar cell line, Par-C5, was examined using the Ca 2 + -sensitive fluorescent indicator fura-2 and by measuring inositol 1,4,5-trisphosphate (IP 3 ) formation. Agonist-induced increase in intracellular Ca 2 + ([Ca 2 + ] i ) by mobilization of intracellular stores and influx across the cell membrane was stimulated by acetylcholine (ACh) and ATP, whereas noradrenaline-(NA)-induced a small [Ca 2 + ] i increase mediated primarily by release from intracellular Ca 2 + stores. [Ca 2 + ] i increase by ACh and ATP was meditated through the phosphoinositide signal pathway since both agonists significantly increased 1,4,5-IP 3 formation and Ca 2 + mobilization was abolished by the phospholipase C inhibitor U73122. In Ca 2 + -free medium, ACh or ATP discharged the IP 3 -sensitive Ca 2 + store and essentially abolished subsequent [Ca 2 + ] i response to thapsigargin (TG). Exposure to ionomycin and monensin after TG induced a further mobilization of Ca 2 + , suggesting IP 3 -insensitive stores are present. Furthermore, depletion of IP 3 -sensitive Ca 2 + stores by TG, ACh and ATP enhanced plasmalemmal Ca 2 + -entry pathways. Exposure to tumor necrosis factor-a (TNF-a), a cytokine associated with lymphocyte invasion of salivary epithelial cells in autoimmune disorders, significantly reduced ACh-stimulated Ca 2 + mobilization. TNF-a inhibitory effect on Ca 2 + mobilization was not directly due to an interaction on muscarinic receptors since ACh-induced 1,4,5-IP 3 formation was not altered. These results in the Par-C5 cell line indicate 1) [Ca 2 + ] i is regulated by muscarinic and P2Y-nucleotide receptors and partly by a 1 -adrenergic receptors; 2) IP 3 -sensitive and -insensitive Ca 2 + stores exist; 3) Ca 2 + influx activated by ACh, ATP or TG is mediated by the store-operated Ca 2 + entry pathway; and 4) muscarinic agonist-stimulated Ca 2 + mobilization is altered by the cytokine TNF-a.

In this paper, wristband electrodes for hand-to-hand bioimpedance measurements are investigated. The proposed electrodes consist of a stretchable conductive knitted fabric. Different implementations have been developed and compared with Ag/AgCl commercial electrodes. Hand-to-hand measurements at 50 kHz on forty healthy subjects have been carried out and the Passing–Bablok regression method has been exploited to compare the proposed textile electrodes with commercial ones. It is demonstrated that the proposed designs guarantee reliable measurements and easy and comfortable use, thus representing an excellent solution for the development of a wearable bioimpedance measurement system.

Due to current technology scaling trends, digital designs are becoming strongly susceptible to space radiation effects. These effects can cause unwanted single event upsets (SEUs) in any state element. This paper presents a new system level model of SEUs propagation through processors as a Continuous-Time Markov Chain (CTMC). Moreover, probabilistic formal techniques (such as probabilistic model checking) are utilized to exhaustively estimate the impact of SEUs on the system behavior. The proposed CTMC model was analyzed for different SEU injection scenarios and different bit-flip rates. Results demonstrate that the proposed approach can provide an accurate estimation of different reliability metrics, such as Mean Time to Failure (MTTF), Mean Time to Recover (MTTR), and the probability of failure for each SEU injection scenario in the system's subcomponents. Furthermore, the proposed probabilistic system-level analysis was utilized to investigate the optimal selfrepair rate required in the system to obtain the desired level of reliability. Results demonstrate that in comparison with existing simulation techniques for fault impact evaluation, the presented approach can provide consistent results while being orders of magnitude faster in terms of CPU time. Index Terms-Single event upsets (SEUs), system-level analysis, probabilistic model checking (PMC), PRISM model checker, continuous-time Markov chain (CTMC), mean time to failure (MTTF), mean time to recover (MTTR).

Worldwide children’s walking disabilities that are caused main ly by cerebral palsy display multiple conditions of both permanent and non-developing motor dysfunction that in turn upsets posture, mobility, or muscle tone in general. In order to estimate the influence of instrumented gait analysis on the walking ability in cerebral palsied children the Dynaport Mini mod, based on a tri-axial accelerometer was employed. A Dynaport Minimod was used for collecting the spatial and temporal gait data. An evaluation of the gait data carried out via online services application for 80 children with cerebral palsies from April 1, 2018 to October 30, 2019. The Dynaport Minimod is capable of capturing most of the spatiotemporal gait parameters which indicate that this technique is quite cooperative and objective in the detection of gait changes and the evaluation of consequences, respectively. The most useful practice for the managing of children with cerebral palsy is a gait analysis system in...

As a potential alternative to currently available skin substitutes and wound dressings, we explored the use of bioactive scaffolds made of plant-derived proteins. We hypothesized that 'green' materials, derived from renewable and biodegradable natural sources, may confer bioactive properties to enhance wound healing and tissue regeneration. We optimized and characterized fibrous scaffolds electrospun from soy protein isolate (SPI) with addition of 0.05% poly(ethylene oxide) (PEO) dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol, and from corn zein dissolved in glacial acetic acid. Fibrous mats electrospun from either of these plant proteins remained intact without further cross-linking, possessing a skin-like pliability. Soy-derived scaffolds supported the adhesion and proliferation of cultured primary human dermal fibroblasts. Using targeted PCR arrays and qPCR validation, we found similar gene expression profiles of fibroblasts cultured for 2 and 24 h on SPI substrates and on collagen type I at both time points. On both substrates there was a pronounced time-dependent upregulation of several genes related to ECM deposition remodelling, including MMP-10, MMP-1, collagen VII, integrin-a2 and laminin-b3, indicating that both plant-and animal-derived materials induce similar responses from the cells after initial adhesion, degrading substrate proteins and depositing extracellular matrix in a 'normal' remodelling process. These results suggest that 'green' proteins, such as soy and zein, are promising as a platform for organotypic skin equivalent culture, as well as implantable scaffolds for skin regeneration. Future studies will determine specific mechanisms of their interaction with skin cells and their efficacy in wound-healing applications.

The actin-myosin system, responsible for muscle contraction, is also the force-generating element in dynamic nanodevices operating with surface-immobilized motor proteins. These devices require materials that are amenable to micro-and nano-fabrication, but also preserve the bioactivity of molecular motors. The complexity of the protein-surface systems is greatly amplified by those of the polymer-fluid interface; and of the structure and function of molecular motors, making the study of these interactions critical to the success of molecular motor-based nanodevices. We measured the density of the adsorbed motor protein (heavy meromyosin, HMM) using quartz crystal microbalance; and motor bioactivity with ATPase assay, on a set of model surfaces, i.e., nitrocellulose, polystyrene, poly(methyl methacrylate), and poly(butyl methacrylate), poly(tert-butyl methacrylate). A higher hydrophobicity of the adsorbing material translates in a higher total number of HMM molecules per unit area, but also in a lower uptake of water, and a lower ratio of active per total HMM molecules per unit area. We also measured the motility characteristics of actin filaments on the model surfaces, i.e., velocity, smoothness and deflection of movement, determined via in vitro motility assays. The filament velocities were found to be controlled by the relative number of active HMM per total motors, rather than their absolute surface density. The study allowed the formulation of the general engineering principles for the selection of polymeric materials for the manufacturing of dynamic nanodevices using protein molecular motors.

Micro-contact printing, μCP, is a well-established soft-lithography technique for printing biomolecules. μCP uses stamps made of Poly(dimethylsiloxane), PDMS, made by replicating a microstructured silicon master fabricated by semiconductor manufacturing processes. One of the problems of the μCP is the difficult control of the printing process, which, because of the high compressibility of PDMS, is very sensitive to minute changes in the applied pressure. This over-sensitive response leads to frequent and/or uncontrollable collapse of the stamps with high aspect ratios, thus decreasing the printing accuracy and reproducibility. Here we present a straightforward methodology of designing and fabricating PDMS structures with an architecture which uses the collapse of the stamp to reduce, rather than enlarge the variability of the printing. The PDMS stamp, organized as an array of pyramidal micro-posts, whose ceiling collapses when pressed on a flat surface, replicates the structure of t...

In this work, we present an evolutive trabecular model for bone remodeling based on a boundary detection algorithm accounting for both biology and applied mechanical forces, known to be an important factor in bone evolution. A finite element (FE) numerical model using the Abaqus/Standard ® software was used with a UMAT subroutine to solve the governing coupled mechanical-biological non-linear differential equations of the bone evolution model. The simulations present cell activation on a simplified trabeculae configuration organization with trabecular thickness of 200 µm. For this activation process, the results confirm that the trabeculae are mainly oriented in the active direction of the principal mechanical stresses and according to the principal applied mechanical load directions. The trabeculae surface activation is clearly identified and can provide understanding of the different bone cell activations in more complex geometries and load conditions.

Given the current emphasis on accurate computational fluid dynamics (CFD) modeling of cardiovascular flows, which incorporates realistic blood vessel geometries and cardiac waveforms, it is necessary to revisit the conventional wisdom regarding the influences of non-Newtonian effects. In this study, patient-specific reconstructed 3D geometries, whole blood viscosity data, and venous pulses postdialysis access surgery are used as the basis for the hemodynamic simulations of renal failure patients with native fistula access. Rheological analysis of the viscometry data initially suggested that the correct choice of constitutive relations to capture the non-Newtonian behavior of blood is important because the end-stage renal disease (ESRD) patient cohort under observation experience drastic variations in hematocrit (Hct) levels and whole blood viscosity throughout the hemodialysis treatment. For this purpose, various constitutive relations have been tested and implemented in CFD practic...

Novel minimum-contact vital signs monitoring techniques like textile or capacitive electrocardiogram (ECG) provide new opportunities for health monitoring. These techniques are sensitive to artifacts and require handling of unstable signal quality. Spatio-temporal blind source separation (BSS) is capable of processing suchlike multichannel signals. However, BSS's permutation indeterminacy requires the selection of the cardiac signal (i.e., the component resembling the electric cardiac activity) after its separation from artifacts. This study evaluates different concepts for solving permutation indeterminacy. Methods: Novel automated component selection routines based on heartbeat detections are compared with standard concepts, as using higher order moments or frequencydomain features, for solving permutation indeterminacy in spatio-temporal BSS. BSS was applied to a textile and a capacitive ECG dataset of healthy subjects performing a motion protocol, and to the MIT-BIH Arrhythmia Database. The performance of the subsequent component selection was evaluated by means of the heartbeat detection accuracy (ACC) using an automatically selected single component. Results: The proposed heartbeat-detection-based selection routines significantly outperformed the standard selectors based on Skewness, Kurtosis, and frequency-domain features, especially for datasets containing motion artifacts. For arrhythmia data, beat analysis by sparse coding outperformed simple periodicity tests of the detected heartbeats. Conclusion: Component selection routines based on heartbeat detections are capable of reliably selecting cardiac signals after spatio-temporal BSS in case of severe motion artifacts and arrhythmia. Significance: The availability of robust cardiac component selectors for solving permutation indeterminacy facilitates the usage of spatiotemporal BSS to extract cardiac signals in artifact-sensitive minimum-contact vital signs monitoring techniques.

Over the last few years, the contactless acquisition of cardiovascular parameters using cameras has gained immense attention. The technique provides an optical means to acquire cardiovascular information in a very convenient way. This review provides an overview on the technique's background and current realizations. Besides giving detailed information on the most widespread application of the technique, namely the contactless acquisition of heart rate, we outline further concepts and we critically discuss the current state.

In the last decade, a novel optical measuring technique called camera-based photoplethysmography (cbPPG) has gained a lot of attention. The technique permits the remote extraction of cardio-respiratory signals using conventional video cameras . Similar to the classical photoplethysmography (PPG), the signals are mainly modulated by blood volume changes in the cutaneous microvasculature . However, cbPPG has the benefit of allowing a spatial assessment of the microcirculatory perfusion which provides a new diagnostic value . For a broad and convenient application of cbPPG, a region of interest (ROI) has to be detected and tracked automatically at suitable skin regions in the video recordings. The efficiency of ROI selection eventually determines the quality and validity of the extracted

Over the last few years, the contactless acquisition of cardiovascular parameters using cameras has gained immense attention. The technique provides an optical means to acquire cardiovascular information in a very convenient way. This review provides an overview on the technique’s background and current realizations. Besides giving detailed information on the most widespread application of the technique, namely the contactless acquisition of heart rate, we outline further concepts and we critically discuss the current state.

Novel minimum-contact vital signs monitoring techniques like textile or capacitive electrocardiogram (ECG) provide new opportunities for health monitoring. These techniques are sensitive to artifacts and require handling of unstable signal quality. Spatio-temporal Blind Source Separation (BSS) is capable of processing suchlike multichannel signals. However, BSS's permutation indeterminacy requires the selection of the cardiac signal (i.e. the component resembling the electric cardiac activity) after its separation from artifacts. This study evaluates different concepts for solving permutation indeterminacy. Novel automated component selection routines based on heartbeat detections are compared with standard concepts, as using higher order moments or frequency-domain features, for solving permutation indeterminacy in spatio-temporal BSS. BSS was applied to a textile and a capacitive ECG dataset of healthy subjects performing a motion protocol, and to the MIT-BIH Arrhythmia Databa...

Camera-based photoplethysmography (cbPPG) is a measurement technique which enables remote vital sign monitoring by using cameras. To obtain valid plethysmograms, proper regions of interest (ROIs) have to be selected in the video data. Most automated selection methods rely on specific spatial or temporal features limiting a broader application. In this work, we present a new method which overcomes those drawbacks and, therefore, allows cbPPG to be applied in an intraoperative environment. We recorded 41 patients during surgery using an RGB and a near-infrared (NIR) camera. A Bayesian skin classifier was employed to detect suitable regions, and a level set segmentation approach to define and track ROIs based on spatial homogeneity. The results show stable and homogeneously illuminated ROIs. We further evaluated their quality with regards to extracted cbPPG signals. The green channel provided the best results where heart rates could be correctly estimated in 95.6% of cases. The NIR cha...

Blind source separation (BSS) aims at separating useful signal content from distortions. In the contactless acquisition of vital signs by means of the camera-based photoplethysmogram (cbPPG), BSS has evolved the most widely used approach to extract the cardiac pulse. Despite its frequent application, there is no consensus about the optimal usage of BSS and its general benefit. This contribution investigates the performance of BSS to enhance the cardiac pulse from cbPPGs in dependency to varying input data characteristics. The BSS input conditions are controlled by an automated spatial preselection routine of regions of interest. Input data of different characteristics (wavelength, dominant frequency, and signal quality) from 18 postoperative cardiovascular patients are processed with standard BSS techniques, namely principal component analysis (PCA) and independent component analysis (ICA). The effect of BSS is assessed by the spectral signal-tonoise ratio (SNR) of the cardiac pulse. The preselection of cbPPGs, appears beneficial providing higher SNR compared to standard cbPPGs. Both, PCA and ICA yielded better outcomes by using monochrome inputs (green wavelength) instead of inputs of different wavelengths. PCA outperforms ICA for more homogeneous input signals. Moreover, for high input SNR, the application of ICA using standard contrast is likely to decrease the SNR.

The fetal ECG derived from abdominal leads is an interesting alternative to standard fetal heart monitoring methods. Due to the temporal and spectral overlap of maternal and fetal signals, the usage of abdominal leads requires elaborated signal processing routines. In this work a modular combination of processing techniques is presented. The core of the evaluated scheme consists of two maternal ECG estimation techniques, namely the Extended Kalman Smoother (EKS) and Template Adaption (TA). Different method combinations are compared using the Computing in Cardiology Challenge 2013's scoring system. The obtained results prove that the proposed methods produce reliable fetal heart rate estimates. For training Set-A we obtained scores of 9.90/2.98 (Event 4/5) for TA, 196/6.78 for EKS and 15.7/3.25 combined versions of each method. For Set-B the best scores (18.1/4.38) were produced by TA in combination with statistical postprocessing.

The fetal ECG derived from abdominal leads provides an alternative to standard means of fetal monitoring. Furthermore, it permits long-term and ambulant recordings, which expands the range diagnostic possibilities for evaluating the fetal health state. However, due to the temporal and spectral overlap of maternal and fetal signals, the usage of abdominal leads imposes the need for elaborated signal processing routines. In this work a modular combination of processing techniques is presented. Its core consists of two maternal ECG estimation techniques, namely the extended Kalman smoother (EKS) and template adaption (TA) in combination with an innovative detection algorithm. Our detection method employs principles of evolutionary computing to detect fetal peaks by considering the periodicity and morphological characteristics of the fetal signal. In a postprocessing phase, single channel detections are combined by means of kernel density estimation and heart rate correction. The described methodology was presented during the Computing in Cardiology Challenge 2013. The entry was the winner of the closed-source events with average scores for events 4/5 with 15.1/3.32 (TA) and 69.5/4.58 (EKS) on training set-A and 20.4/4.57 (TA) and 219/7.69 (EKS) on test set-B, respectively. Using our own clinical data (24 subjects each 20 min recordings) and statistical measures beyond the Challenge's scoring system, we further validated the proposed method. For our clinical data we obtained an average detection rate of 82.8% (TA) and 83.4% (EKS). The achieved results show that the proposed methods are able produce reliable fetal heart rate estimates from a restricted number of abdominal leads.

This paper deals with output feedback control of phytoplanktonic algae growth models in the chemostat. The considered class of model is of variable yield type, meaning that the ratio between the environmental nutrient absorption rate and the cells' growth rate varies, which is different from classical bioprocesses assumptions. On the basis of weak qualitative hypotheses on the analytical expressions of the involved biological phenomena (which guarantee robustness of the procedure towards modelling uncertainties) we propose a nonlinear controller and prove its ability to globally stabilize such processes. Finally, we illustrate our approach with numerical simulations and show its benefits for biological laboratory experiments, especially for ensuring persistence of the culture facing classical experimental problems.

Microalgae are often seen as a potential biofuel producer. In order to predict achievable productivities in the so called raceway culturing system, the dynamics of photosynthesis has to be taken into account. In particular, the dynamical effect of inhibition by an excess of light (photoinhibition) must be represented. We propose a model considering both photosynthesis and growth dynamics. This model involves three different time scales. We study the response of this model to fluctuating light with different frequencies by slow/fast approximations. Therefore, we identify three different regimes for which a simplified expression for the model can be derived. These expressions give a hint on productivity improvement which can be expected by stimulating photosynthesis with a faster hydrodynamics.

A metasurface combined with a transceiver coil to improve the radio frequency magnetic field for 1.5T magnetic resonance imaging applications is presented. The novel transceiver provides localized enhancement in magnetic flux density when compared to a transceiver coil alone by incorporating an electrically small metasurface using an interdigital capacitance approach.

The development of metasurface structures has provided new methods of designing electromagnetic devices and materials with unique features. This thesis reports new approaches of metasurface structure, which have been designed to improve the local performance of a radio frequency (RF) magnetic field and SNR of MRI images acquired on a 1.5T MRI scanner. In this context, comprehensive investigations of different metasurafce structures combined with RF coils, have been evaluated and compared against the standard coil performance. In order to determine the best options which are able to improve the RF magnetic field and SNR in terms of their strength and more penetration depth inside the dielectric phantom, different metasurface approaches have been investigated. This framework was applied in different metasurafce structures, which include a high impedance surface (HIS) and capacitive impedance surface (CIS), which has been applied as a reflective or a transmission surface. A novel design of a HIS is miniaturized using distributed interdigital capacitors. The HIS with an electrically small unit cell λ /92 was positioned between a RF transmit-receive (TR) coil and an RF shield. The magnitude of the magnetic flux density from an RF coil when coupled to a dielectric phantom load (mimicking a biological sample) was estimated using numerical simulation and corroborated with SNR measurements on a MRI scanner. The results show that, the RF magnetic flux profile can be increased by using the miniaturised HIS, however, the measured SNR showed a limited improvement. For this reason, a new structure has been developed, which is a reflective capacitive impedance surface (RCIS)combined with a radio frequency loop coil. The proposed RCIS structure is based on a miniaturized surface unit cell using an interdigital capacitance approach. Full field simulations employing an interdigital frequency selective surface show a high improvement in magnetic flux density inside a homogeneous dielectric phantom as compared to a loop coil alone. This improvement has been for the first 20 mm inside the phantom. Since MRI applications require more penetration depth, a new method of using the CIS is developed as a transmission capacitive impedance surface combined with a radio frequency loop coil. Full field simulations employing an interdigital frequency selective surface show a significant improvement of 160% and 210% in normalised A.

Phage display is a commonly utilized in vivo approach in selecting peptides specific to solid inorganic materials. In this process, traditionally, high affinity peptides are recovered by a chemical elution method, which involves contacting the phage library with the desired inorganic, washing the weak binders, and eluting the tight binders under harsh buffer conditions. This process may result in incomplete removal of all strong binders, separation of the phage from the display protein, or may modify the material surface. To overcome these potential limitations, we developed a physical elution technique based on ultrasonication. Here, we report two optimized ultrasonication protocols by which we selected peptides specific to natural mineral mica. We first performed a 30-s physical elution after the chemical elution step and increased the efficiency of screening strong binders by about 100%. Encouraged by the results, we applied physical elutiononly protocol where we obtained 45% of the selected sequences as strong binders. The approach has a far shorter total elution time, i.e., seconds compared to hours in traditional chemical elution. The novel physical elution approach using ultrasonication reported herein can be a highly efficient alternate step in the screening of solid material specific peptides.

Adapting molecular biology to materials science we developed peptide-based protocols for the assembly and formation of hybrid materials and systems. In this approach of generating molecular scale biomimetic materials, peptides are designed, synthesized, genetically tailored and, finally, utilized as potential molecular linkers in self-assembly, ordered organization, and fabrication of inorganics for specific technological applications. The potential areas range from molecular and nanoscale functional materials to medical fields, e.g., from diagnosis to biosensors. Here, we describe a selection of inorganic binding polypeptides via directed evolution, post-selection modifications through genetic engineering, and utility in practical applications. The selection of the inorganic binders is accomplished through combinatorial biology based peptide libraries. The diversity of applications is highlighted in three case studies. First, the molecular and nanoscale recognition of the polypeptide is presented via nanosize gold particle immobilization onto a molecular template by gold binding polypeptide. Second, we present that the alkaline phosphatase fused with multiple repeats of gold binding polypeptide can still be enzymatically active when it is immobilized onto a solid substrate. Finally, we present silica biosynthesis in aqueous environment using engineered quartz-binding peptides.

Background: The rapid growth of mobile technology has given rise to the development of mobile health programmes aimed at treating and preventing a wide range of health conditions. However, evidence on the use of mHealth in high disease burdened settings such as SSA is not clear. We systematically mapped evidence on mHealth for disease diagnosis and treatment support by health workers in SSA. Methods: We conducted a scoping review study guided by the Arksey and O’Malley’s framework, Levac et al recommendations, and Joanna Briggs Institute guidelines. We thoroughly searched the following databases: MEDLINE and CINAHL with full-text via EBSCOhost; PubMed; Science Direct and Google Scholar for relevant articles from inception to July 2019. Two independent reviewers screened abstracts and full-text articles using the eligibility criteria as reference. This study employed the mixed methods appraisal tool version 2018 to assess the methodological quality of the included studies. Results: O...

Cardiac MRI in neonates holds promise as a tool that can provide detailed functional information in this vulnerable group. However, their small size, rapid heart rate, and inability to breath-hold, pose particular challenges that require prolonged high-contrast and high-SNR methods. Balanced-steady state free precession (SSFP) offers high SNR efficiency and excellent contrast, but is vulnerable to off-resonance effects that cause banding artifacts. This is particularly problematic in the bloodpool, where off-resonance flow artifacts severely degrade image quality. Methods: In this article, we explore active frequency stabilization, combined with image-based shimming, to achieve prolonged SSFP imaging free of banding artifacts. The method was tested using 2D multislice SSFP cine acquisitions on 18 preterm infants, and the functional measures derived were validated against phase-contrast flow assessment. Results: Significant drifts in the resonant frequency (165 6 23Hz) were observed during 10-min SSFP examinations. However, full short-axis stacks free of banding artifacts were achieved in 16 subjects with stabilization; the cardiac output obtained revealed a mean difference of 9.0 6 8.5% compared to phase-contrast flow measurements. Conclusion: Active frequency stabilization has enabled the use of prolonged SSFP acquisitions for neonatal cardiac imaging at 3T. The findings presented could have broader implications for other applications using prolong SSFP acquisitions.

Despite continuous research, communication approaches based on brain-computer interfaces (BCIs) are not yet an efficient and reliable means that severely disabled patients can rely on. To date, most motor imagery (MI)-based BCI systems use conventional spectral analysis methods to extract discriminative features and classify the associated electroencephalogram (EEG)-based sensorimotor rhythms (SMR) dynamics that results in relatively low performance. In this study, we investigated the feasibility of using recurrence quantification analysis (RQA) and complex network theory graph-based feature extraction methods as a novel way to improve MI-BCIs performance. Rooted in chaos theory, these features explore the nonlinear dynamics underlying the MI neural responses as a new informative dimension in classifying MI. Method: EEG time series recorded from six healthy participants performing MI-Rest tasks were projected into multidimensional phase space trajectories in order to construct the corresponding recurrence plots (RPs). Eight nonlinear graph-based RQA features were extracted from the RPs then compared to the classical spectral features through a 5-fold nested cross-validation procedure for parameter optimization using a linear support vector machine (SVM) classifier. Results: Nonlinear graph-based RQA features were able to improve the average performance of MI-BCI by 5.8% as compared to the classical features. Significance: These findings suggest that RQA and complex network analysis could represent new informative dimensions for nonlinear characteristics of EEG signals in order to enhance the MI-BCI performance.

Objectives: Radiofrequency Ablation is an investigational treatment option for RCC. The aim of our study was to test the ablation algorithms of four different RF systems in a standardized ex vivo perfused porcine kidney model. Materials and methods: A multitine monopolar dry electrode (impedance-based system), a multitine monopolar dry electrode (temperature-based system), a single monopolar wet electrode (impedance-based system) and a single monopolar dry, internally-cooled electrode (impedance-based system) were selected. RF energy was applied at different treatment parameters (power with and without control, tissue temperature, saline enhancement) for 1, 3, 5 and 9 minutes in healthy perfused ex vivo porcine tissue. Each treatment parameter was repeated 5 times. Maximum vertical, long-axis and short-axis diameters of the macroscopic lesion were measured and lesion volumes/ shapes were calculated. Results: Lesion volumes increased significantly with the pre-selected tissue temperature and saline enhancement. Saline enhancement created larger, but irregular shaped lesions. The impedance-based system created lesion volumes that were predictable by treatment time and generator power. Lesions were unpredictable when uncontrolled generator power was applied. The created lesion shape was dependent on the selected electrode configuration. Conclusions: The currently available monopolar RFA systems offer different specific technical features to control tissue ablation. Detailed knowledge of the specific characteristics of each RF system is necessary to provide a higher chance of successful clinical outcome by complete and reliable ablation.

The wear performance of a polyurethane compliant layer (CL) material formed into an acetabular component and implanted into a sheep model of cemented total hip arthroplasty was assessed at 6, 12, 24, and 48 months. Four (11%) of 36 acetabular components debonded from the cement and one component was slightly loose at the cement-bone interface. There was no macroscopic evidence of fracture, wear, or deformation of the CL material on the articular surface of the acetabular components. Small numbers of polymeric wear particles was found in the hip synovial tissues of 10 sheep, most commonly in the early time groups, and were likely associated with initial wear of surface asperities. The wear performance of the CL was unchanged during a 48-month implantation period.

Research into Brain-Computer Music Interfacing (BCMI) involves three major challenges: the extraction of meaningful control information from signals emanating from the brain, the design of generative music techniques that respond to such information and the definition of ways in which such technology can effectively improve the lives of people with special needs and address therapeutic needs. This chapter discussed the first two challenges, in particularly the music technology side of BCMI research, which has been largely overlooked by colleagues working in this field. After a brief historical account of the field, the author reviews the pioneering research into BCMI that has been developed at Plymouth University's Interdisciplinary Centre for Computer Music Research (ICCMR) within the last decade or so. The chapter introduces examples illustrating ICCMR's developments and glances at current work informed by cognitive experiments.

Brain-Computer Music Interface (BCMI) is a new research area that is emerging at the cross roads of neurobiology, engineering sciences and music. This research involves three major challenging problems: the extraction of meaningful control information from signals emanating directly from the brain, the design of generative music techniques that respond to such information, and the training of subjects to use the system. We have implemented a proof-of-concept BCMI system that is able to use electroencephalogram information to generate music online. Ongoing research informed by a better understanding of brain activity associated with music cognition, and the development of new tools and techniques for implementing braincontrolled generative music systems offer a bright future for the development of BCMI.

Ventricular arrhythmias after myocardial infarction (MI) originate from discrete areas within the MI border zone (BZ), identified during functional electrophysiology tests. Accurate sampling of arrhythmogenic sites for ex vivo study remains challenging, yet is critical to identify their tissue, cellular and molecular signature. In this study, we developed, validated, and applied a targeted sampling methodology based on individualized 3D prints of the human-sized pig heart. To this end, 3D anatomical models of the left ventricle were created from magnetic resonance imaging and fused with biplane fluoroscopy. Regions of interest for sampling were annotated on the anatomical models, from which we created a unique 3D printed cast with custom slits identifying the annotated regions for sampling. The methodology was validated by retrieving ablation lesions created at predefined locations on the anatomical model. We applied the methodology to sample arrhythmia-vulnerable regions after MI during adrenergic stimulation. A novel pipeline of imaging was developed to create a 3D highresolution map of each sample, highlighting the complex interplay of cellular organization, and altered innervation in the BZ.

Objectives. To stress the importance of the way intraforaminal synovial cyst, a very rare condition, causes a peculiar position of the nerve root in the foramen and to describe the required surgical approach. Summary of Background Data. Intraforaminal synovial cyst is a highly unusual finding. The existence of this rare entity raises the problem of differential diagnosis with other space-occupying lesions of the neural foramen, such as herniated disc, neurinoma, neurofibroma, and metastatic lesions Methods and Results. A 64-year-old woman suffered a right L4 radiculopathy with motor deficit. Computed tomography showed a space-occupying lesion in the L4 -L5 foramen isodense with the disc. Magnetic resonance images showed a right intraforaminal cystic lesion at the L4 -L5 level with no enhancement after intravenous infusion of gadolinium. A 3-cm cystic lesion, which appeared to arise from the L4 -L5 facet joint without direct communication, was excised from the L4 -L5 foramen. In contrast with intraforaminal disc herniation, downward displacement of the L4 nerve root was observed. Two months after surgery, the patient was pain-free and neurologic examination revealed no motor deficit. Conclusions. An unusual intraforaminal presentation of a lumbar synovial cyst demonstrates the importance of considering this entity and of adapting the surgical technique to avoid injury to the nerve root.

This chapter introduces a motorized camera system designed for monitoring and evaluating the tests of the Short Physical Performance Battery (SPPB). This system targets physical performance assessment for older patients undergoing cancer treatment. The device is self-contained, incorporating a small computer, three cameras, and two motors. The core algorithms utilize three object recognition techniques: template matching, Haar cascades, and Channel and Spatial Reliability Tracking. To facilitate user interaction, graphical user interfaces (GUIs) are developed on the small computer, enabling test execution and camera adjustments via cell phone and its hotspot. The system delivers precise results, with gait speed tests showing a range of 0.041-1.92 m/s and average speed and distance accuracies exceeding 95%. The standing balance and 5 times sit-stand (5TSS) tests achieve average time accuracies exceeding 97%. This novel camera-based device holds promise in enhancing evaluation of lower body extremity fitness for elderly people receiving cancer health care, offering a reliable and efficient solution for monitoring their progress and well-being.

We evaluated nutrition in chronic renal failure (CRF) in Nigeria by comparing 74 patients with CRF and 48 normal controls (C). Creatinine clearance (Ccr, Cockroit-Gault formula) was 14238 m h i n in CRF and 93523 ml/min in C. Gender (%Female: CRF 30%, C 29%), age (CRF 41220 y, C 4259 y), and total serum (8.) cholesterol (CRF 1972108 mg/dL, C 174231 fmg/dL) did not differ between CRF and C. The CRF group had lower (p c 0.0001) body mass index (BMI, 221-5 Vs. 2523 kg/M2, with 24% of the CRF patients and 2% of the C patients having BMI < 20 kg/M2j, hematocrit (27?8% Vs. 3624%), HDL cholesterol (58535 Vs. 93223 mg/dL), and s. albumin (3.220.9 Vs. 4.020.4 g/dL, with 43% of the CRF patients and none of the C patients having s. albumin < 2.9 g/dL), and higher (at p 5 0.02) s. urea nitrogen ( 9 4 t 4 6 Vs. 16218 mg/dL) and s. creatinine (8.525.8 Vs. 0.720.2 mg/dL) than the C group. Compared to CRF patients with s. albumin > 2.9 g/dL, those with s. albumin < 2.9 g/dL had lower (at p 5 0.0002) BMI (21 ?4 Vs. 2423 kg/M2) and higher (at p = 0.03) s. triglyceride (2132168 Vs. 133289 mg/dL), while Ccr, gender, age, hematocrit, total and HDL s. cholesterol, 5. urea nitrogen and creatinine, and degree of proteinuria did not differ between the two CRF groups. Severe hypoalbuminemia is seen in approximately 40% of the Nigerian patients with advanced CRF, who also exhibit weight deficit and a serum lipid profile pattern promoting atherosclerosis. Attention to nutrition prior to dialysis is of paramount importance in the management of CRF patients in developing countries.

Objective: To determine frequencies of various acute complications in patients undergoing hemodialysis. Study Design: Descriptive cross-sectional study. Place and Duration of Study: Department of Nephrology Military Hospital (MH) Rawalpindi, from Jan 2016 till Mar 2016. Material and Methods: A total of 150 patients who underwent haemodialysis at MH were enrolled in the study after informed consent on justification of inclusion and exclusion criteria. The patients were evaluated for the frequency of various intra-dialytic complications and data were analysed using SPSS version 19. Results: Out of the 150 enrolled patients, males were 125 (83.33%) and females were 25 (16.67%). A total of 2520 haemodialysis session were performed. Hypotension was the most frequently observed complication during 318 (12.62%) dialysis sessions, followed by hypertension in 208 (8.25%) and fever in 193 (7.66%) sessions. Other complications were muscle cramps in 116 (4.60%), shivering in 94 (3.73%), headach...

We present results of simulations performed as part of the development of a gamma-ray detector module comprising a nonpixellated scintillator and pixellated photodiode detector. The simulations have been carried out to determine the effect of surface treatment and dimensions of the scintillator on the ability to determine the two-dimensional position of interaction. A set of 32 different combinations of surface treatments have been considered for each crystal size. Scintillator dimensions considered have been 25 25 ( 3-6 mm 3 ). For scintillator thicknesses at the low end of this range, an average accuracy of 0.5-0.6 mm is achievable for many different surface treatments. At the higher end of the thickness range, 6 mm, the average accuracy reduces to around 0.7 mm and is more dependent on the surface treatment.

Silicon microdosimetry is a promising technology for heavy ion therapy (HIT) quality assurance, because of its sub-mm spatial resolution and capability to determine radiation effects at a cellular level in a mixed radiation field. A drawback of silicon is not being tissue-equivalent, thus the need to convert the detector response obtained in silicon to tissue. This paper presents a method for converting silicon microdosimetric spectra to tissue for a therapeutic 12 C beam, based on Monte Carlo simulations. The energy deposition spectra in a 10 μm sized silicon cylindrical sensitive volume (SV) were found to be equivalent to those measured in a tissue SV, with the same shape, but with dimensions scaled by a factor κ equal to 0.57 and 0.54 for muscle and water, respectively. A low energy correction factor was determined to account for the enhanced response in silicon at low energy depositions, produced by electrons. The concept of the mean path length (l Path ) to calculate the lineal energy was introduced as an alternative to the mean chord length (l) because it was found that adopting Cauchy's formula for the (l) was not appropriate for the radiation field typical of HIT as it is very directional (l Path ) can be determined based on the peak of the lineal energy distribution produced by the incident carbon beam. Furthermore it was demonstrated that the thickness of the SV along the direction of the incident 12 C ion beam can be adopted as (l Path ). The tissue equivalence conversion method and (l Path ) were adopted to determine the RBE 10 , calculated using a modified microdosimetric kinetic model, applied to the microdosimetric spectra resulting from the simulation study. Comparison of the RBE 10 along the Bragg peak to experimental TEPC measurements at HIMAC, NIRS, showed good agreement. Such agreement demonstrates the validity of the developed tissue equivalence correction factors and of the determination of (l Path ).