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Seyyed Hossein Asadpour, Hamid Reza Hamedi, Mahmoud Jafari
This paper hints at the Goos-Hänchen shift properties of a cavity containing an ensemble of atoms using a four-level atomic system involving a Rydberg state. By means of the stationary phase theory and density matrix formalism in quantum optics, we study theoretically the Goos-Hänchen shifts in both reflected and transmitted light beams. It is realized that as a result of the interaction between Rydberg and excited states in such a four-level atom-light coupling scheme the maximum positive and negative Goos-Hänchen shifts can be obtained in reflected and transmitted light beams owning to the effect of the Rydberg electromagnetically induced transparency (EIT) or Rydberg electromagnetically induced absorption...
May 20, 2018: Applied Optics
Gang Wang, Yu-Sheng Wang, Emily Kay Huang, Weilun Hung, Kai-Lin Chao, Ping-Yeh Wu, Yi-Hsin Chen, Ite A Yu
We present high-contrast electromagnetically-induced-transparency (EIT) spectra in a heated vapor cell of single isotope 87 Rb atoms. The EIT spectrum has both high resonant transmission up to 67% and narrow linewidth of 1.1 MHz. We get rid of the possible amplification resulted from the effects of amplification without population inversion and four-wave mixing. Therefore, this high transmitted light is not artificial. The theoretical prediction of the probe transmission agrees well with the data and the experimental parameters can be derived reasonably from the model...
May 21, 2018: Scientific Reports
Mangesh Bhattarai, Vineet Bharti, Vasant Natarajan
We demonstrate a technique for continuous tuning of the Hanle effect from electromagnetically induced transparency (EIT) to electromagnetically induced absorption (EIA) by changing the polarization ellipticity of a control beam. In contrast to previous work in this field, we use spatially separated probe and control beams. The experiments are done using magnetic sublevels of the Fg  = 4 → Fe  = 5 closed hyperfine transition in the 852 nm D2 line of 133 Cs. The atoms are contained in a room temperature vapor cell with anti-relaxation (paraffin) coating on the walls...
May 14, 2018: Scientific Reports
Arnab Lahiri, Pranab K Mondal
Spatiotemporal thermal response and characteristics of net entropy production rate of a gold nanosphere (radius: 50-200 nm), subjected to a short-pulse, femtosecond laser is reported. In order to correctly illustrate the temperature history of laser-metal interaction(s) at picoseconds transient with a comprehensive single temperature definition in macroscale and to further understand how the thermophysical response of the single-phase lag (SPL) and dual-phase lag (DPL) frameworks (with various lag-ratios') differs, governing energy equations derived from these benchmark non-Fourier frameworks are numerically solved and thermodynamic assessment under both the classical irreversible thermodynamics (CIT) as well as extended irreversible thermodynamics (EIT) frameworks is subsequently carried out...
April 2018: Physical Review. E
Mayo Faulkner, Sana Hannan, Kirill Aristovich, James Avery, David Holder
Electrical Impedance Tomography (EIT) is an emerging technique which has been used to image evoked activity during whisker displacement in the cortex of an anaesthetised rat with a spatiotemporal resolution of 200 μm and 2 ms. The aim of this work was to extend EIT to image not only from the cortex but also from deeper structures active in somatosensory processing, specifically the ventral posterolateral (VPL) nucleus of the thalamus. The direct response in the cortex and VPL following 2 Hz forepaw stimulation were quantified using a 57-channel epicortical electrode array and a 16-channel depth electrode...
May 9, 2018: NeuroImage
Jennifer L Mueller, Peter A Muller, Michelle Mellenthin, Rashmi Murthy, Michael Capps, Melody Alsaker, Robin Deterding, Scott D Sagel, Emily DeBoer
OBJECTIVE: Electrical impedance tomography (EIT) has been shown as a viable non-invasive, bedside imaging modality to monitor lung function.This paper introduces a method for identifying regions of air trapping from EIT data collected during tidal breathing and breath-holding maneuvers. APPROACH: Ventilation-perfusion index maps are computed from dynamic EIT images. These maps are then used to identify regions of air trapping in the area of the lung as regions that are poorly ventilated but well perfused throughout the breathing and cardiac cycles...
May 4, 2018: Physiological Measurement
Peng-Yuan Wang, Tao Jin, Fan-Yi Meng, Yue-Long Lyu, Daniel Erni, Qun Wu, Lei Zhu
This paper introduces the concept of electromagnetically induced transparency (EIT) into the permittivity extraction of an anisotropic material-nematic liquid crystal (NLC). A novel two-step strategy is presented to extract the complex permittivity of the NLC at the THz band, which evaluates the relative permittivity tensor from the resonant frequencies and then determines the loss tangent from the quality factor Q of the EIT sensor. The proposed method features high accuracy due to the sharp resonance of the EIT sensor and also high robustness to the thickness of the NLC layer because only amplitude rather than phase information of the transmission coefficients is required...
April 30, 2018: Optics Express
Tingting Ding, Yuanlin Zheng, Xianfeng Chen
Configurable narrow bandwidth filters are indispensable components in optical communication networks. Here, we present an easily-integrated compact tunable filtering based on polarization-coupling process in a thin periodically poled lithium niobate (PPLN) in a reflective geometry via the transverse electro-optic (EO) effect. The structure, composed of an in-line polarizer and a thinned PPLN chip, forms a phase-shift Solc-type filter with similar mechanism to defected Bragg gratings. The filtering effect can be dynamically switched on and off by a transverse electric filed...
April 30, 2018: Optics Express
Michael A Manfredi, Susannah J Clark, Shawn Medford, Steven J Staffa, Peter Ngo, Thomas E Hamilton, C Jason Smithers, Russell W Jennings
BACKGROUND AND AIM: Refractory esophageal strictures are rare conditions in pediatrics, and are often due to anastomotic, congenital, or caustic strictures. Traditional treatment options include serial dilation and surgical stricture resection; endoscopic intralesional steroid injections, mitomycin C, and externally removable stents combined with dilation have had variable success rates. Although not as widely used, endoscopic electrocautery incisional therapy (EIT) has been reported as an alternative treatment for refractory strictures in a small number of adult series...
April 23, 2018: Journal of Pediatric Gastroenterology and Nutrition
Ethan K Murphy, Xiaotian Wu, Ryan J Halter
OBJECTIVE: Prostate cancer is a significant problem affecting 1 in 7 men. Unfortunately, the diagnostic gold-standard of ultrasound-guided biopsy misses 10-30% of all cancers. The objective of this study was to develop an Electrical Impedance Tomography (EIT) approach that has the potential to image the entire prostate using multiple impedance measurements recorded between electrodes integrated onto an end-fired transrectal ultrasound (TRUS) device and a biopsy probe (BP). APPROACH: Simulations and sensitivity analyses were used to investigate the best combination of electrodes, and measured tank experiments were used to evaluate a fused-data transrectal EIT (fd-TREIT) and BP approach...
April 18, 2018: Physiological Measurement
Thibault Vogt, Christian Gross, T F Gallagher, Wenhui Li
We demonstrate electromagnetically induced transparency (EIT) in a four-level cascade-like system, where the two upper levels are Rydberg states coupled by a microwave field. A two-photon transition consisting of an off-resonant microwave field and an off-resonant optical field forms an effective coupling field to induce transparency of the probe light. We characterize the Rabi frequency of the effective coupling field, as well as the EIT microwave spectra. The results show that microwave-assisted EIT allows us to efficiently access Rydberg states with relatively high orbital angular momentum ℓ=3, which is promising for the study of exotic Rydberg molecular states...
April 15, 2018: Optics Letters
Appaji Rayi, Stephanie Thompson, David Gloss, Konark Malhotra
OBJECTIVE: To explore the evidence of reporting bias among completed epilepsy intervention trials (EITs) and compliance of applicable EITs to Food and Drug Administration Amendments Act (FDAAA). METHODS: We included consecutive EITs registered as completed on from 2008 to 2015. Descriptive data was collected including study type, study phase, funding source, primary completion date, and result reporting date. Time to result reporting was analyzed using Kaplan-Meier estimates for two time periods (2008-2011 and 2012-2015)...
March 30, 2018: Epilepsy Research
Peter A Muller, Jennifer L Mueller, Michelle Mellenthin, Rashmi Murthy, Michael Capps, Brandie Wagner, Melody Alsaker, Robin Deterding, Scott D Sagel, Jordana Hoppe
Lung function monitoring by spiromety plays a critical role in the clinical care of pediatric cystic fibrosis (CF) patients, but many young children are unable to perform spirometry, and the outputs are often normal even in the presence of lung disease. Measures derived from electrical impedance tomography (EIT) images were studied for their utility as potential surrogates for spirometry in CF patients and to assess response to intravenous antibiotic treatment for acute pulmonary exacerbations (PEx) in a subset of patients...
March 22, 2018: Physiological Measurement
Yuan Luo, Parinaz Abiri, Shell Zhang, Chih-Chiang Chang, Amir H Kaboodrangi, Rongsong Li, Ashish K Sahib, Alex Bui, Rajesh Kumar, Mary Woo, Zhaoping Li, René R Sevag Packard, Yu-Chong Tai, Tzung K Hsiai
Introduction: Obesity is associated with an increased risk of nonalcoholic fatty liver disease (NAFLD). While Magnetic Resonance Imaging (MRI) is a non-invasive gold standard to detect fatty liver, we demonstrate a low-cost and portable electrical impedance tomography (EIT) approach with circumferential abdominal electrodes for liver conductivity measurements. Methods and Results: A finite element model (FEM) was established to simulate decremental liver conductivity in response to incremental liver lipid content...
2018: Theranostics
J Hope, F Vanholsbeeck, A McDaid
OBJECTIVE: 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...
April 26, 2018: Physiological Measurement
Barry 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...
April 26, 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 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
L Sophocleous, I Frerichs, M Miedema, M Kallio, T Papadouri, C Karaoli, T Becher, D G Tingay, A H van Kaam, R Bayford, A D 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...
April 26, 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...
June 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
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