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phase coherence

Zhibin Luo, Jicheng Ding, Lin Zhao, Mouyan Wu
Tracking error estimation is of great importance in global navigation satellite system (GNSS) receivers. Any inaccurate estimation for tracking error will decrease the signal tracking ability of signal tracking loops and the accuracies of position fixing, velocity determination, and timing. Tracking error estimation can be done by traditional discriminator, or Kalman filter-based pre-filter. The pre-filter can be divided into two categories: coherent and non-coherent. This paper focuses on the performance improvements of non-coherent pre-filter...
November 18, 2017: Sensors
Qian Wang, Liang Li
A periodic sound, such as a pure tone, evokes both transient onset field-potential responses and sustained frequency-following responses (FFRs) in the auditory midbrain, the inferior colliculus (IC). It is not clear whether the two types of responses are based on the same or different neural substrates. Although it has been assumed that FFRs are based on phase locking to the periodic sound, the evidence showing the direct relationship between the FFR amplitude and the phase-locking strength is still lacking...
November 7, 2017: Hearing Research
Gen Long, Shuigang Xu, Xiangbin Cai, Zefei Wu, Tianyi Han, Jiangxiazi Lin, Chun Cheng, Yuan Cai, Xinran Wang, Ning Wang
Atomically-thin black phosphorus (BP) field effect transistors show strong-weak localization transition, which is tunable through gate voltages. Hopping transports through charge impurity-induced localized states are observed at low carrier density regime. Variable-range hopping model is applied to simulate scattering behaviors of charge carriers. In the high carrier concentration regime, a negative magnetoresistance indicates weak localization effects. The extracted phase coherence length is power-law temperature-dependent (~T<sup>-0...
November 20, 2017: Nanotechnology
Youssef Korani, Hassan Sabzyan
The effects of the orientation, wavelength and carrier-envelope phase of laser pulses on the spin fluctuation in HeH(2+) and LiH(3+) molecular ions in their bound electronic states, during their interactions with linearly polarized intense laser pulses, were investigated by solving numerically the time-dependent Dirac equation with the Foldy-Wouthuysen transformation. The results of this study showed that an increase in the wavelength of the laser pulse at a fixed intensity reduces the lifetime of the coherent spin states and increases the sensitivity of the spin vector to the applied laser field in both HeH(2+) and LiH(3+) species...
November 15, 2017: Physical Chemistry Chemical Physics: PCCP
Fei Yao, Dechao Li, Haodi Liu, Libin Fu, Xiaoguang Wang
Majorana stars are visual representation for a quantum pure state. For some states, the corresponding majorana stars are located on one curve on the Block sphere. However, it is lack of exact curve equations for them. To find the exact equations, we consider a superposition of two bosonic coherent states with an arbitrary relative phase. We analytically give the curve equation and find that the curve always goes through the North pole on the Block sphere. Furthermore, for the superpositions of SU(1,1) coherent states, we find the same curve equation...
November 14, 2017: Scientific Reports
X N Feng, L F Wei
Quantum coherence is one of the old but always important concepts in quantum mechanics, and now it has been regarded as a necessary resource for quantum information processing and quantum metrology. However, the question of how to quantify the quantum coherence has just been paid the attention recently (see, e.g., Baumgratz et al. PRL, 113. 140401 (2014)). In this paper we verify that the well-known quantum Fisher information (QFI) can be utilized to quantify the quantum coherence, as it satisfies the monotonicity under the typical incoherent operations and the convexity under the mixing of the quantum states...
November 14, 2017: Scientific Reports
Taek Jeong, Jumi Park, Han Seb Moon
In quantum memory based on an atomic medium, we may have a question about whether all information on the stored light is preserved. In particular, the phase coherence between the stored and retrieval light pulses is very interesting, because it can indicate the relationship between the coherence time and storage time of the light. In this paper, we investigate the phase coherence time of light stored in a warm atomic vapor, by examining the beat-note interference between the retrieval light pulse and a reference light beam optically delayed using an optical fiber...
November 14, 2017: Scientific Reports
Zhuolin Liu, Kazuhiro Kurokawa, Furu Zhang, John J Lee, Donald T Miller
Ganglion cells (GCs) are fundamental to retinal neural circuitry, processing photoreceptor signals for transmission to the brain via their axons. However, much remains unknown about their role in vision and their vulnerability to disease leading to blindness. A major bottleneck has been our inability to observe GCs and their degeneration in the living human eye. Despite two decades of development of optical technologies to image cells in the living human retina, GCs remain elusive due to their high optical translucency...
November 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
Katarzyna Michalska-Małecka, Anna Heinke Knudsen
PURPOSE: To present optical coherence tomography angiography (OCTA) features in patients with diabetic retinopathy (DR) at the baseline and in response to treatment with anti-VEGF intravitreal injections. To investigate the role of OCTA in management of patients with DR. METHODS: Retrospective case series showing primary outcomes of 3 patients with DR and diabetic macular edema. Patients were injected intravitreally a loading phase of 3 monthly 2.0 mg aflibercept, followed by 2 injections bimonthly (5 injections in total)...
November 2017: Medicine (Baltimore)
G Kramer, A M M Van der Stouwe, N M Maurits, M A J Tijssen, J W J Elting
OBJECTIVE: To distinguish tremor subtypes using wavelet coherence analysis (WCA). WCA enables to detect variations in coherence and phase difference between two signals over time and might be especially useful in distinguishing functional from organic tremor. METHODS: In this pilot study, polymyography recordings were studied retrospectively of 26 Parkinsonian (PT), 26 functional (FT), 26 essential (ET), and 20 enhanced physiological (EPT) tremor patients. Per patient one segment of 20 s in duration, in which tremor was present continuously in the same posture, was selected...
October 14, 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
B Voloh, T Womelsdorf
Population-level theta and beta band activity in anterior cingulate and prefrontal cortices (ACC/PFC) are prominent signatures of self-controlled, adaptive behaviors. But how these rhythmic activities are linked to cell-type specific activity has remained unclear. Here, we suggest such a cell-to-systems level linkage. We found that the rate of burst spiking events is enhanced particularly during attention states and that attention-specific burst spikes have a unique temporal relationship to local theta and beta band population-level activities...
November 9, 2017: Cerebral Cortex
Gaoxuan Wang, Serge Reboul, Jean-Bernard Choquel, Eric Fertein, Weidong Chen
Lock-in amplification (LIA) is an effective approach for recovery of weak signal buried in noise. Determination of the input signal amplitude in a classical dual-phase LIA is based on incoherent detection which leads to a biased estimation at low signal-to-noise ratio. This article presents, for the first time to our knowledge, a new architecture of LIA involving phase estimation with a linear-circular regression for coherent detection. The proposed phase delay estimate, between the input signal and a reference, is defined as the maximum-likelihood of a set of observations distributed according to a von Mises distribution...
November 14, 2017: Sensors
Li-Chi Kao, Bo-Jia Huang, Yu-En Jeng, Kai-Teng Tu, Shang-Jui Chiu, Ching-Shun Ku, Kuang-Yao Lo
Zn dots are potential solutions for metal contacts in future nanodevices. The metastable states that exist at the interface between Zn quantum dots and oxide-free Si(111) surfaces can suppress the development of the complete relaxation and increase the size of Zn dots. In this work, the actual heat consumption of the structural evolution of Zn dots resulting from extrinsic thermal effect was analyzed. Zn dots were coherently grown on oxide-free Si(111) through magnetron RF sputtering. A compensative optical method combined with reflective second harmonic generation (RSHG) and synchrotron X-ray diffraction (XRD) was developed to statistically analyze the thermal effect on the Zn dot system...
November 14, 2017: Nanotechnology
Yusuke Nagai, Chen Shao-Chieh, Kotaro Kajikawa
A random laser of a photonic crystal fiber (PCF) with holes filled with laser dye-doped nematic liquid crystal (NLC) is reported. When the excitation polarization was along the PCF axis, the measured laser threshold was 80  μJ/mm(2) per pulse, which is much lower than the previously reported random laser of PCF filled with laser dye-doped organic solvent. This low threshold is due to the high refractive index of the NLC, which produces a greater scattering efficiency. In contrast, when the excitation polarization is perpendicular to the PCF axis, the threshold was much higher or the laser oscillation was absent...
November 10, 2017: Applied Optics
Niar Gusnaniar, Henny C van der Mei, Wenwen Qu, Titik Nuryastuti, Johanna M M Hooymans, Jelmer Sjollema, Henk J Busscher
Bacterial adhesion is a main problem in many biomedical, domestic, natural and industrial environments and forms the onset of the formation of a biofilm, in which adhering bacteria grow into a multi-layered film while embedding themselves in a matrix of extracellular polymeric substances. It is usually assumed that bacterial adhesion occurs from air or by convective-diffusion from a liquid suspension, but often bacteria adhere by transmission from a bacterially contaminated donor to a receiver surface. Therewith bacterial transmission is mechanistically different from adhesion, as it involves bacterial detachment from a donor surface followed by adhesion to a receiver one...
November 5, 2017: Advances in Colloid and Interface Science
Raj K Maturi, Adam R Glassman, Danni Liu, Roy W Beck, Abdhish R Bhavsar, Neil M Bressler, Lee M Jampol, Michele Melia, Omar S Punjabi, Hani Salehi-Had, Jennifer K Sun
Importance: Some eyes have persistent diabetic macular edema (DME) following anti-vascular endothelial growth factor (anti-VEGF) therapy for DME. Subsequently adding intravitreous corticosteroids to the treatment regimen might result in better outcomes than continued anti-VEGF therapy alone. Objective: To compare continued intravitreous ranibizumab alone with ranibizumab plus intravitreous dexamethasone implant in eyes with persistent DME. Design, Setting, and Participants: Phase 2 multicenter randomized clinical trial conducted at 40 US sites in 129 eyes from 116 adults with diabetes between February 2014 and December 2016...
November 11, 2017: JAMA Ophthalmology
Hamid Farrokhi, Thazhe Madam Rohith, Jeeranan Boonruangkan, Seunghwoi Han, Hyunwoong Kim, Seung-Woo Kim, Young-Jin Kim
High coherence of lasers is desirable in high-speed, high-resolution, and wide-field imaging. However, it also causes unavoidable background speckle noise thus degrades the image quality in traditional microscopy and more significantly in interferometric quantitative phase imaging (QPI). QPI utilizes optical interference for high-precision measurement of the optical properties where the speckle can severely distort the information. To overcome this, we demonstrated a light source system having a wide tunability in the spatial coherence over 43% by controlling the illumination angle, scatterer's size, and the rotational speed of an electroactive-polymer rotational micro-optic diffuser...
November 10, 2017: Scientific Reports
Fengzi Ling, Shuai Li, Xinli Song, Yanmei Wang, Jinyou Long, Bing Zhang
The butterfly vibration during the hydrogen tunneling process in electronically excited o-fluorophenol has been visualized in real time by femtosecond time-resolved ion yield spectroscopy coupled with time-resolved photoelectron imaging technique. A coherent superposition of out-of-plane C-F butterfly motions is prepared in the first excited electronic state (S1). As the C-F bond vibrates with respect to the aromatic ring, the nuclear geometry varies periodically, leading to the corresponding variation in the photoionization channel...
November 10, 2017: Scientific Reports
Shikhar Uttam, Yang Liu
Quantitative phase imaging (QPI) modality has been widely adopted in a variety of applications ranging from identifying photomask defects in lithography to characterizing cell structure and tissue morphology in cancer. Traditional QPI utilizes the electromagnetic phase of transmitted light to measure, with nanometer scale sensitivity, alterations in the optical thickness of a sample of interest. In our work, the QPI paradigm is generalized to study depth-resolved properties of phase objects with slowly varying refractive index without a strong interface by utilizing the Fourier phase associated with Fourier-domain optical coherence tomography (FD-OCT)...
November 7, 2017: Methods: a Companion to Methods in Enzymology
Gufei Zhang, Tomas Samuely, Hongchu Du, Zheng Xu, Liwang Liu, Oleksandr Onufriienko, Paul W May, Johan Vanacken, Pavol Szabó, Jozef Kačmarčík, Haifeng Yuan, Peter Samuely, Rafal E Dunin-Borkowski, Johan Hofkens, Victor V Moshchalkov
In the presence of disorder, superconductivity exhibits short-range characteristics linked to localized Cooper pairs which are responsible for anomalous phase transitions and the emergence of quantum states such as the bosonic insulating state. Complementary to well-studied homogeneously disordered superconductors, superconductor-normal hybrid arrays provide tunable realizations of the degree of granular disorder for studying anomalous quantum phase transitions. Here, we investigate the superconductor-bosonic dirty metal transition in disordered nanodiamond arrays as a function of the dispersion of intergrain spacing, which ranges from angstroms to micrometers...
November 13, 2017: ACS Nano
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