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phase coherence

Nicolas Libert, Anatole Harrois, Jacques Duranteau
In case of haemorrhage, a combination of low volume fluid resuscitation and permissive hypotension is used to avoid the adverse effects of early aggressive fluid resuscitation. During this phase, occult microvascular hypoperfusion can possibly develop over time. After controlling the bleeding, it is expected that optimization of macrocirculation will result in an improvement in microcirculation. However, this is the case only without alterations in microcirculation regulation. Haemodynamic coherence must be maintained to expect the restoration of microcirculation through systemic haemodynamic-driven resuscitation...
December 2016: Best Practice & Research. Clinical Anaesthesiology
Spoorti Krishna Reddy Mandadi, Aniruddha Agarwal, Kanika Aggarwal, Bruttendu Moharana, Ramandeep Singh, Aman Sharma, Reema Bansal, Mangat R Dogra, Vishali Gupta
PURPOSE: To analyze and describe the imaging characteristics of tubercular serpiginous-like choroiditis using optical coherence tomography angiography (OCTA) and to compare these findings with multimodal imaging. METHODS: In this prospective cross-sectional study, multimodal imaging was performed in subjects with tubercular serpiginous-like choroiditis using OCTA (Optovue RTVue XR Avanti), enhanced-depth imaging OCT (Heidelberg Spectralis), fundus autofluorescence, fluorescein angiography, and indocyanine green angiography...
December 7, 2016: Retina
Miguel Angel Ribot, Cyril Botteron, Pierre-André Farine
The use of the reflected Global Navigation Satellite Systems' (GNSS) signals in Earth observation applications, referred to as GNSS reflectometry (GNSS-R), has been already studied for more than two decades. However, the estimation precision that can be achieved by GNSS-R sensors in some particular scenarios is still not fully understood yet. In an effort to partially fill this gap, in this paper, we compute the Cramér-Rao bound (CRB) for the specific case of static ground-based GNSS-R receivers and scenarios where the coherent component of the reflected signal is dominant...
December 5, 2016: Sensors
Cheng Jin, Kyung-Han Hong, C D Lin
We numerically demonstrate the generation of intense, low-divergence soft X-ray isolated attosecond pulses in a gas-filled hollow waveguide using synthesized few-cycle two-color laser waveforms. The waveform is a superposition of a fundamental and its second harmonic optimized such that highest harmonic yields are emitted from each atom. We then optimize the gas pressure and the length and radius of the waveguide such that bright coherent high-order harmonics with angular divergence smaller than 1 mrad are generated, for photon energy from the extreme ultraviolet to soft X-rays...
December 8, 2016: Scientific Reports
Thomas R Hedges, Marisa Gobuty, Richard A Manfready, Natalie Erlich-Malona, Caitlin Monaco, Carlos E Mendoza-Santiesteban
The objective of this study was to describe the changes in the retinal ganglion cell complex (GCC) relative to the retinal nerve fibre layer (RNFL) over time in Leber hereditary optic neuropathy (LHON) patients. Average RNFL and GCC thickness was measured in seven patients in the early acute (123, 68.4 μm), late acute (113.5, 57.4 μm), and chronic (72.7, 50.8 μm) phases. Patients showed thinning of the GCC with RNFL swelling in the early acute phase. GCC thinning became severe within weeks and persisted...
June 2016: Neuro-ophthalmology
Mengqi Xing, Reza Tadayonnejad, Annmarie MacNamara, Olusola Ajilore, Julia DiGangi, K Luan Phan, Alex Leow, Heide Klumpp
BACKGROUND: Functional magnetic resonance imaging (fMRI) resting-state studies show generalized social anxiety disorder (gSAD) is associated with disturbances in networks involved in emotion regulation, emotion processing, and perceptual functions, suggesting a network framework is integral to elucidating the pathophysiology of gSAD. However, fMRI does not measure the fast dynamic interconnections of functional networks. Therefore, we examined whole-brain functional connectomics with electroencephalogram (EEG) during resting-state...
2017: NeuroImage: Clinical
Manuel Alegre, Patricio Molero, Miguel Valencia, Guillermo Mayner, Felipe Ortuño, Julio Artieda
The symptoms of schizophrenia might be mediated by a cortical network disconnection which may disrupt the cortical oscillatory activity. Steady-state responses are an easy and consistent way to explore cortical oscillatory activity. A chirp-modulated tone (increasing the frequency of the modulation in a linear manner) allows a fast measure of the steady-state response to different modulation rates. With this approach, we studied the auditory steady-state responses in two groups of patients with schizophrenia (drug-naive and treated with atypical antipsychotic drugs), in order to assess the differences in their responses with respect to healthy subjects, and study any potential effect of medication...
November 26, 2016: Psychiatry Research
Mohamed S Seghilani, Mikhael Myara, Mohamed Sellahi, Luc Legratiet, Isabelle Sagnes, Grégoire Beaudoin, Philippe Lalanne, Arnaud Garnache
The generation of a coherent state, supporting a large photon number, with controlled orbital-angular-momentum L = ħl (of charge l per photon) presents both fundamental and technological challenges: we demonstrate a surface-emitting laser, based on III-V semiconductor technology with an integrated metasurface, generating vortex-like coherent state in the Laguerre-Gauss basis. We use a first order phase perturbation to lift orbital degeneracy of wavefunctions, by introducing a weak anisotropy called here "orbital birefringence", based on a dielectric metasurface...
December 5, 2016: Scientific Reports
Jayakrishnan Nair, Arndt-Lukas Klaassen, Jordan Poirot, Alexei Vyssotski, Björn Rasch, Gregor Rainer
The basal forebrain (BF) is an important regulator of cortical excitability and responsivity to sensory stimuli, and plays a major role in wake-sleep regulation. While the impact of BF on cortical EEG or LFP signals has been extensively documented, surprisingly little is known about LFP activity within BF. Based on bilateral recordings from rats in their home cage, we describe endogenous LFP oscillations in the BF during quiet wakefulness, rapid eye movement (REM) and slow wave sleep (SWS) states. Using coherence and Granger causality methods, we characterize directional influences between BF and visual cortex (VC) during each of these states...
November 29, 2016: Journal of Physiology, Paris
Michael Förster, Timo Paschen, Michael Krüger, Christoph Lemell, Georg Wachter, Florian Libisch, Thomas Madlener, Joachim Burgdörfer, Peter Hommelhoff
We demonstrate coherent control of multiphoton and above-threshold photoemission from a single solid-state nanoemitter driven by a fundamental and a weak second harmonic laser pulse. Depending on the relative phase of the two pulses, electron emission is modulated with a contrast of the oscillating current signal of up to 94%. Electron spectra reveal that all observed photon orders are affected simultaneously and similarly. We confirm that photoemission takes place within 10 fs. Accompanying simulations indicate that the current modulation with its large contrast results from two interfering quantum pathways leading to electron emission...
November 18, 2016: Physical Review Letters
Jiangkun Liu, Weixing Cai, Ruola Ning
Grating-based differential phase contrast (DPC) imaging enables the use of a hospital-grade X-ray tube, but compromises the image quality due to insufficiently coherent illumination. In this research, a bench-top DPC cone beam CT (DPC-CBCT) was systematically evaluated and compared with the traditional attenuation-based CBCT in terms of contrast to noise ratio, noise property, and contrast resolution through phantom studies. In order to evaluate DPC-CBCT for soft tissue imaging, breast specimen and small animal studies were carried out...
November 30, 2016: Journal of X-ray Science and Technology
J Chen, W X Ding, D L Brower, D Finkenthal, C Muscatello, D Taussig, R Boivin
Motivated by the need to measure fast equilibrium temporal dynamics, non-axisymmetric structures, and core magnetic fluctuations (coherent and broadband), a three-chord Faraday-effect polarimeter-interferometer system with fast time response and high phase resolution has recently been installed on the DIII-D tokamak. A novel detection scheme utilizing two probe beams and two detectors for each chord results in reduced phase noise and increased time response [δb ∼ 1G with up to 3 MHz bandwidth]. First measurement results were obtained during the recent DIII-D experimental campaign...
November 2016: Review of Scientific Instruments
H Qu, T Zhang, X Han, H M Xiang, F Wen, K N Geng, Y M Wang, D F Kong, J Q Cai, C B Huang, Y Gao, X Gao, S Zhang
A new multi-channel poloidal correlation reflectometry is developed at Experimental Advanced Superconducting Tokamak. Eight dielectric resonator oscillators with frequencies of 12.5 GHz, 13.5 GHz, 14.5 GHz, 15 GHz, 15.5 GHz, 16 GHz, 17 GHz, and 18 GHz are used as sources. Signals from the sources are up-converted to V band using active quadruplers and then coupled together. The output waves are launched by one single antenna after passing through a 20 dB directional coupler which can provide the reference signal...
November 2016: Review of Scientific Instruments
Xiang Gao, Shinbuhm Lee, John Nichols, Tricia L Meyer, Thomas Z Ward, Matthew F Chisholm, Ho Nyung Lee
Direct observations using scanning transmission electron microscopy unveil an intriguing interfacial bi-layer that enables epitaxial growth of a strain-free, monoclinic, bronze-phase VO2(B) thin film on a perovskite SrTiO3 (STO) substrate. We observe an ultrathin (2-3 unit cells) interlayer best described as highly strained VO2(B) nanodomains combined with an extra (Ti,V)O2 layer on the TiO2 terminated STO (001) surface. By forming a fully coherent interface with the STO substrate and a semi-coherent interface with the strain-free epitaxial VO2(B) film above, the interfacial bi-layer enables the epitaxial connection of the two materials despite their large symmetry and lattice mismatch...
December 2, 2016: Scientific Reports
Yanlong Yang, Shaohui Yan, Xianghua Yu, Manman Li, Baoli Yao
We propose a non-paraxial hollow accelerating beam, which is formed by incoherently superposing two well-designed coherent accelerating beams. Very interestingly, this incoherent superposition does not hamper the acceleration dynamics pertaining to the coherent ones, but results in a hollow intensity pattern in the cross section transverse to the circular accelerating trajectory. By a simple optimization, this hollow cross section pattern can be effectively extended to an angle close to 90°. The magnitude and the phase of the angular spectrum of the beam are given followed by a suggested scheme to generate the beam in practice...
November 28, 2016: Optics Express
V E Lobanov, G V Lihachev, N G Pavlov, A V Cherenkov, T J Kippenberg, M L Gorodetsky
Dissipative Kerr solitons have paved the way to broadband and fully coherent optical frequency combs in microresonators. Here, we demonstrate numerically that slow frequency tuning of the pump laser in conjunction with phase or amplitude modulation corresponding to the free spectral range of the microresonator, provides reliable convergence of an initially excited chaotic comb state to a single dissipative Kerr soliton (DKS) state. The efficiency of this approach depends on both frequency tuning speed and modulation depth...
November 28, 2016: Optics Express
Dongfang Li, Jing Feng, Domenico Pacifici
We compare the intensity modulation of passive light transmission and active fluorescence emission in planar plasmonic interferometers consisting of a nano-scale hole flanked by circular grooves etched in a silver film. Discrete fast Fourier transform applied to plasmonic interferograms - i.e., optical interferograms obtained by varying the propagation phase of surface plasmon polaritons (SPPs) - reveals higher-order interference effects that can be enhanced by optimizing in-plane SPP scattering and reflection...
November 28, 2016: Optics Express
Sambit B Pal, Mark M Lam, K Dieckmann
We report on a transfer-lock laser frequency stabilization that utilizes a frequency comb (FC) and a radio frequency counter referenced to a GPS frequency standard to compensate for the frequency drifts of two lasers, which are locked to a single passive Fabry-Perot resonator (FPR). The method requires only one optical phase lock with the FC and allows transfer locking of lasers at wavelengths beyond the usable range of the FC. To attain a large frequency tuning range for the lasers, we implement optical serrodyning...
December 1, 2016: Optics Letters
Zhen Qu, Ivan B Djordjevic, Mark A Neifeld
We theoretically investigate and experimentally demonstrate a RF-assisted four-state continuous-variable quantum key distribution (CV-QKD) system. Classical coherent detection is implemented with a simple digital phase noise cancelation scheme. In the proposed system, there is no need for frequency and phase locking between the quantum signals and the local oscillator laser. Moreover, in principle, there is no residual phase noise, and a mean excess noise of 0.0115 (in shot-noise units) can be acquired experimentally...
December 1, 2016: Optics Letters
Ayse Oner, Z Burcin Gonen, Neslihan Sinim, Mustafa Cetin, Yusuf Ozkul
BACKGROUND: This prospective clinical case series aimed to investigate the safety of subretinal adipose tissue-derived mesenchymal stem cell (ADMSC) implantation in advanced stage retinitis pigmentosa (RP). METHODS: This study included 11 patients with end-stage RP who received subretinal implantation of ADMSCs. All patients had a total visual field defect and five of them only had light perception. The best corrected visual acuity (BCVA) in the study was 20/2000...
December 1, 2016: Stem Cell Research & Therapy
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