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James Hope, Frederique Vanholsbeeck, A J McDaid
In neural interfaces for peripheral nerve a trade-off exists between the level of invasiveness and the selectivity of neural recordings. In this study, we implement electrical impedance tomography (EIT) in a nerve cuff with the aim to investigate the achievable level of selectivity.
 Approach: Established modelling approaches in neural-EIT are expanded on to be used, for the first time, on myelinated fibres which are abundant in mammalian peripheral nerves and transmit motor commands. The model is then used to evaluate the viability of using EIT with a nerve cuff to record neural activity in peripheral nerves...
March 16, 2018: Physiological Measurement
Barry James McDermott, Emily Porter, Marggie Jones, Brian McGinley, Martin O'Halloran
OBJECTIVE: The theoretical basis, experimental implementation, and proof of concept of a novel Electrical Impedance Tomography (EIT) imaging technique, called Symmetry Difference EIT, is described. This technique is applicable in situations where there is inherent symmetry in the region being imaged. METHODS: The sample scenario of the human head is used to describe the technique. The head is largely symmetrical across the sagittal plane. A unilateral lesion such as a haemorrhage or region of ischaemia distorts that symmetry...
March 13, 2018: Physiological Measurement
Tingting Zhang, Rihui Li, Thomas Potter, Jin Keun Seo, Guanglin Li, Yingchun Zhang
Electrical properties of human tissues are usually linked with structure of thin insulating membranes and thereby reflect physiological function of the tissues or organs. It is clinically important to characterize electrical properties of tissues in vivo. Electrical impedance tomography (EIT) is a recently developed medical imaging technique which has been exploited to characterize electrical properties (conductivity and permittivity) of human tissues by injecting currents and measuring the resulting voltages at boundary electrodes...
March 8, 2018: International Journal for Numerical Methods in Biomedical Engineering
Louiza Sophocleous, Inez Frerichs, Martijn Miedema, Merja Kallio, Thalia Papadouri, Christina Karaoli, Tobias Becher, David G Tingay, Anton van Kaam, Richard H Bayford, Andreas Daniel Waldmann
OBJECTIVE: Critically ill neonates and infants might particularly benefit from continuous chest electrical impedance tomography (EIT) monitoring at the bedside. In this study a textile 32-electrode interface for neonatal EIT examination has been developed and tested to validate its clinical performance. The objectives were to assess ease of use in a clinical setting, stability of contact impedance at the electrode-skin interface and possible adverse effects. APPROACH: Thirty preterm infants (gestational age: 30...
March 8, 2018: Physiological Measurement
Anna Witkowska-Wrobel, Kirill Aristovich, Mayo Faulkner, James Avery, David Holder
Imaging ictal and interictal activity with Electrical Impedance Tomography (EIT) using intracranial electrode mats has been demonstrated in animal models of epilepsy. In human epilepsy subjects undergoing presurgical evaluation, depth electrodes are often preferred. The purpose of this work was to evaluate the feasibility of using EIT to localise epileptogenic areas with intracranial electrodes in humans. The accuracy of localisation of the ictal onset zone was evaluated in computer simulations using 9M element FEM models derived from three subjects...
February 27, 2018: NeuroImage
Constantinos Makrides, Ming Li, Eite Tiesinga, Svetlana Kotochigova
Ergodic quantum systems are often quite alike, whereas nonergodic, fractal systems are unique and display characteristic properties. We explore one of these fractal systems, weakly bound dysprosium lanthanide molecules, in an external magnetic field. As recently shown, colliding ultracold magnetic dysprosium atoms display a soft chaotic behavior with a small degree of disorder. We broaden this classification by investigating the generalized inverse participation ratio and fractal dimensions for large sets of molecular wave functions...
February 2018: Science Advances
Gregory Reychler, Valeska Uribe Rodriguez, Cheryl Elizabeth Hickmann, Bertrand Tombal, Pierre-François Laterre, Axel Feyaerts, Jean Roeseler
INTRODUCTION: Impairment of global and regional pulmonary ventilations is a well-known consequence of general anesthesia. Positive expiratory pressure (PEP) or incentive spirometry (IS) is commonly prescribed, albeit their efficacy is poorly demonstrated. The aim of this study was to assess the effects of PEP and IS on lung ventilation and recruitment in patients after surgery involving anesthesia using electrical impedance tomography (EIT). METHOD: Ten male subjects (age = 61...
February 27, 2018: Physiotherapy Theory and Practice
Barbara Resnick, Ann Kolanowski, Kimberly Van Haitsma, Elizabeth Galik, Marie Boltz, Jeanette Ellis, Liza Behrens, Nina M Flanagan, Karen J Eshraghi, Shijun Zhu
Behavioral and psychological symptoms of dementia (BPSD) include aggression, agitation, resistiveness to care, depression, anxiety, apathy, and hallucinations. BPSD are common in nursing home residents and can be ameliorated using person-centered approaches. Despite regulatory requirements, less than 2% of nursing homes consistently implement person-centered behavioral approaches. In a National Institute of Nursing Research-funded research protocol, we are implementing a pragmatic cluster randomized clinical trial designed to enable staff in nursing homes to reduce BPSD using behavioral approaches while optimizing function, preventing adverse events, and improving quality of life of residents...
February 27, 2018: Research in Nursing & Health
Kristyna Buzkova, Martin Muller, Ales Rara, Karel Roubik, Tomas Tyll
BACKGROUND AND AIMS: During laparoscopic surgery, a capnoperitoneum is created to optimize the operating space for surgeons. One effect of this is abdominal pressure which alters the physiological thoraco-abdominal configuration and pushes the diaphragm and lungs cranially. Since the lung image acquired by electrical impedance tomography (EIT) depends on the conditions within the thorax and abdomen, it is crucial to know the diaphragm position to determine the effect of diaphragm shift on EIT thorax image...
February 21, 2018: Biomedical Papers of the Medical Faculty of the University Palacký, Olomouc, Czechoslovakia
Mayo Faulkner, Sana Hannan, Kirill Y Aristovich, James Avery, David S Holder
<i>Objective</i>. Electrical Impedance Tomography (EIT) can image impedance changes associated with evoked physiological activity in the cerebral cortex using an array of epicortical electrodes. An impedance change is observed as the externally applied current, normally confined to the extracellular space is admitted into the conducting intracellular space during neuronal depolarisation. The response is largest at DC and decreases at higher frequencies due to capacitative transfer of current across the membrane...
February 16, 2018: Physiological Measurement
Lu Zhao
Based on electromagnetically induced transparency (EIT), we investigate an all-optical grating structure to realize polarization-dependent multiple beam splitting in the Raman-Nath limit. To optimize the grating performance, higher excited state [e.g., nS 1/2 (n ≥ 6)] of ultracold 87 Rb atoms is employed to construct a five-level Ξ-Λ system sharing one common populated ground state. A principal advantage of our proposed scheme is that the σ ± components of a linearly polarized weak probe field can be decoupled and thus be independently diffracted with high efficiency in both one and two dimensions by exploiting different quasi-standing waves as the two strong coupling fields in the Ξ and Λ configurations...
February 15, 2018: Scientific Reports
Zhanqi Zhao, Wei Wang, Zuojing Zhang, Meiying Xu, Inez Frerichs, Jing-Xiang Wu, Knut Moeller
The aim of the study was to explore the feasibility of titrating tidal volume (VT) and positive end-expiratory pressure (PEEP) during one-lung ventilation (OLV) based on ventilation distribution and oxygenation. Approach: Twenty four consecutive patients requiring intubation with a double-lumen tube and subsequent OLV for thoracic surgical procedures were examined prospectively in lateral posture. Electrical impedance tomography (EIT), blood gases, respiratory mechanics were successfully measured in 21 patients at various combinations of VT (4 ml/kg, 6 ml/kg, 8 ml/kg body weight) and PEEP (0 cmH2O, 4 cmH2O, 8 cmH2O) during OLV...
February 12, 2018: Physiological Measurement
Beatriz Lobo, Cecilia Hermosa, Ana Abella, Federico Gordo
Continuous assessment of respiratory status is one of the cornerstones of modern intensive care unit (ICU) monitoring systems. Electrical impedance tomography (EIT), although with some constraints, may play the lead as a new diagnostic and guiding tool for an adequate optimization of mechanical ventilation in critically ill patients. EIT may assist in defining mechanical ventilation settings, assess distribution of tidal volume and of end-expiratory lung volume (EELV) and contribute to titrate positive end-expiratory pressure (PEEP)/tidal volume combinations...
January 2018: Annals of Translational Medicine
Jakob Orschulik, Nadine Hochhausen, Michael Czaplik, Daniel Teichmann, Steffen Leonhardt, Marian Walter
Bioimpedance measurements are used in many biomedical applications, such as Bioimpedance Spectroscopy (BIS) or Electrical Impedance Tomography (EIT). While BIS measures and analyzes the impedance in a frequency range at constant electrode positions, EIT aims to reconstruct images of the conductivity distribution from multiple measurements at different electrode positions. Our aim is to add spatial information to BIS measurements by using electrode positions focus measurements on desired regions of interest...
February 6, 2018: Physiological Measurement
Thomas Dowrick, David S Holder
Objective The most commonly used EIT paradigm (Time Division Multiplexing) limits the temporal resolution of impedance images due to the need to switch between injection electrodes. Advances have previously been made using Frequency Division Multiplexing (FDM) to increase temporal resolution, but in cases where a fixed range of frequencies is available, such as imaging fast neural activity, an upper limit is placed on the total number of simultaneous injections. The use of Phase Division Multiplexing (PDM) where multiple out of phase signals can be injected at each frequency is investigated to increase temporal resolution...
February 6, 2018: Physiological Measurement
Chuong Ngo, Falk Dippel, Klaus Tenbrock, Steffen Leonhardt, Sylvia Lehmann
BACKGROUND: Electrical impedance tomography (EIT) provides information on global and regional ventilation during tidal breathing and mechanical ventilation. During forced expiration maneuvers, the linearity of EIT and spirometric data has been documented in healthy persons. The present study investigates the potential diagnostic use of EIT in pediatric patients with asthma. METHODS: EIT and spirometry were performed in 58 children with asthma (average age ± SD: 11...
February 6, 2018: Pediatric Pulmonology
Muhammad Amin, Rashid Ramzan, Omar Siddiqui
We report a novel guided-wave resonator that supports multiple bands of electromagnetically induced transparency (EIT). The platform for the spatial and spectral interference is obtained by a microstrip transmission line loaded with proximity-coupled open-circuited stubs. We show experimentally that with two microstrip open stubs, a complete destructive interference takes place leading to a single EIT band with near-unity transmission efficiency. More interestingly, the addition of a third stub results in a supplementary EIT band with a Q-factor of 147 and an effective group refractive index of 530...
February 5, 2018: Scientific Reports
Zhiwei Guo, Haitao Jiang, Yunhui Li, Hong Chen, G S Agarwal
Near-field coupling is a fundamental physical effect, which plays an important role in the establishment of classical analog of electromagnetically induced transparency (EIT). However, in a normal environment the coupling length between the bright and dark artificial atoms is very short and far less than one wavelength, owing to the exponentially decaying property of near fields. In this work, we report the realization of a long range EIT, by using a hyperbolic metamaterial (HMM) which can convert the near fields into high-k propagating waves to overcome the problem of weak coupling at long distance...
January 22, 2018: Optics Express
D Ziemkiewicz, K Słowik, S Zielińska-Raczyńska
We analytically examine propagation of surface plasmon polaritons (SPPs) at a thin metallic film between a glass substrate and an electromagnetically induced transparency (EIT) medium. High precision and high resolution in the frequency domain provided by EIT paves the way toward plasmonic group velocities' reduction, even by up to four orders of magnitude, and corresponding lifetime enhancement of SPPs up to microseconds.
February 1, 2018: Optics Letters
Hongjun Zhang, Ximei Li, Dong Sun, Huijing Li, Hui Sun
We investigate theoretically an enhancement of four-wave mixing (FWM) process in phase-dependent double electromagnetically induced transparency (EIT) six-level atomic media. It is shown, owing to the multiphoton destructive interference, that the conversion efficiency of FWM can be enhanced by manipulating the relative phase of the applied fields in this ultraslow propagation regime. Moreover, we also find that the conversion efficiency is amplified with the presence of the microwave field in comparison with the previous six-level scheme [Phys...
January 20, 2018: Applied Optics
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