Read by QxMD icon Read

phase coherence

Yang Liu, Shoufeng Tong, Shuai Chang, Yansong Song, Yan Dong, Xin Zhao, Zhe An, Fuwan Yu
Optical phase-locked loops are an effective detection method in high-speed and long-distance laser communication. Although this method can detect weak signal light and maintain a small bit error rate, it is difficult to perform because identifying the phase difference between the signal light and the local oscillator accurately has always been a technical challenge. Thus, a series of studies is conducted to address this issue. First, a delayed exclusive or gate (XOR) phase detector with multi-level loop compound control is proposed...
May 10, 2018: Applied Optics
Mikael Sjodahl, Eynas Amer
The two techniques of lateral shear interferometry and speckle deflectometry are analyzed in a common optical system for their ability to measure phase gradient fields of a thin phase object. The optical system is designed to introduce a shear in the frequency domain of a telecentric imaging system that gives a sensitivity of both techniques in proportion to the defocus introduced. In this implementation, both techniques successfully measure the horizontal component of the phase gradient field. The response of both techniques scales linearly with the defocus distance, and the precision is comparative, with a random error in the order of a few rad/mm...
May 10, 2018: Applied Optics
Nicolas C M Marty, Sylvain Grangeon, Erik Elkaïm, Christophe Tournassat, Clémence Fauchet, Francis Claret
Amongst all cement phases, hydrated calcium aluminate (AFm) plays a major role in the retention of anionic species. Molybdenum (Mo), whose 93 Mo isotope is considered a major steel activation product, will be released mainly under the form of MoO4 2- in a radioactive waste repository. Understanding its fate is of primary importance in a safety analysis of such disposal. This necessitates models that can both predict quantitatively the sorption of Mo by AFm and determine the nature of the sorption process (i...
May 21, 2018: Scientific Reports
Jayanth S Ajay, Ksenia G Komarova, Francoise Remacle, R D Levine
Isotopic fractionation in the photodissociation of N2 could explain the considerable variation in the 14 N/15 N ratio in different regions of our galaxy. We previously proposed that such an isotope effect is due to coupling of photoexcited bound valence and Rydberg electronic states in the frequency range where there is strong state mixing. We here identify features of the role of the mass in the dynamics through a time-dependent quantum-mechanical simulation. The photoexcitation of N2 is by an ultrashort pulse so that the process has a sharply defined origin in time and so that we can monitor the isolated molecule dynamics in time...
May 21, 2018: Proceedings of the National Academy of Sciences of the United States of America
Abel Swaan, Christophe K Mannaerts, Matthijs Jv Scheltema, Jakko A Nieuwenhuijzen, C Dilara Savci-Heijink, Jean Jmch de la Rosette, R Jeroen A van Moorselaar, Ton G van Leeuwen, Theo M de Reijke, Daniel Martijn de Bruin
BACKGROUND: Focal therapy for prostate cancer has been proposed as an alternative treatment to whole-gland therapies in selected men to diminish side effects in localized prostate cancer. As nowadays imaging cannot offer complete prostate cancer disease characterization, multicore systematic biopsies are recommended (transrectal or transperineal). Optical imaging techniques such as confocal laser endomicroscopy and optical coherence tomography allow in vivo, high-resolution imaging. Moreover, they can provide real-time visualization and analysis of tissue and have the potential to offer additive diagnostic information...
May 21, 2018: JMIR Research Protocols
Alva Tang, Ayelet Lahat, Michael J Crowley, Jia Wu, Louis A Schmidt
Although the neural correlates of social exclusion have been well-documented, most studies have examined single age groups. No studies have directly compared specific age-related differences in social exclusion across children, adolescents, and adults using event-related oscillatory electroencephalogram (EEG) dynamics. The authors examined event-related theta EEG power and phase coherence in fair play and social exclusion conditions during the Cyberball task in 166 participants: 42 children (ages 10-12), 56 adolescents (ages 14-17), and 68 adults (ages 18-28)...
May 21, 2018: Emotion
Shuping Guo, Kaishuai Yang, Zhi Zeng, Yongsheng Zhang
Doping and alloying are important methodologies to improve the thermoelectric performance of FeNbSb based materials. To fully understand the influence of point defects on the thermoelectric properties, we have used density functional calculations in combination with the cluster expansion and Monte Carlo methods to examine the defect distribution behaviors in the mesoscopic FeNb1-xVxSb and FeNb1-xTixSb systems. We find that V and Ti exhibit different distribution behaviors in FeNbSb at low temperature: forming the FeNbSb-FeVSb phase separations in the FeNb1-xVxSb system but two thermodynamically stable phases in FeNb1-xTixSb...
May 21, 2018: Physical Chemistry Chemical Physics: PCCP
Blake S Porter, Robert Schmidt, David K Bilkey
Effective navigation relies on knowledge of one's environment. A challenge to effective navigation is accounting for the time and energy costs of routes. Irregular terrain in ecological environments poses a difficult navigational problem as organisms ought to avoid effortful slopes to minimize travel costs. Route planning and navigation have previously been shown to involve hippocampal place cells and their ability to encode and store information about an organism's environment. However, little is known about how place cells may encode the slope of space and associated energy costs as experiments are traditionally carried out in flat, horizontal environments...
May 21, 2018: Hippocampus
Lucie Nadeau, Vanessa Lecompte, Janique Johnson-Lafleur, Annie Pontbriand, Cécile Rousseau
Background: This article examines the association between immigration, poverty and family environment, and the emotional and behavioral problems reported by youth and their family receiving mental health (MH) services within a collaborative care model in a multiethnic neighborhood. Method: Participants in this study were 140 parent-child dyads that are part of an ongoing longitudinal project looking at the association between individual, familial, social and organizational factors, and outcomes of youth receiving MH services in local health and social service organizations in the Montreal area...
May 2018: Child and Adolescent Mental Health
D Bellocq, F De Bats, M Rabilloud, L Kodjikian
PURPOSE: To assess the value of a monthly injection of Lucentis® until stable visual acuity (VA) is obtained for three consecutive months without exudation in patients with neovascular age macular degeneration (AMD). METHODS: Prospective, single-center, non-controlled trial including naïve AMD patients with neovascularization. An assessment of VA and a spectral domain optical coherence tomography (SD-OCT) were performed at baseline and every month. Monthly injections of Lucentis® were performed over three months...
May 17, 2018: Journal Français D'ophtalmologie
Nicole Proulx, Ali-Akbar Samadani, Tom Chau
Event-related potentials (ERPs) have previously been used to confirm the existence of the fast optical signal (FOS) but validation methods have mainly been limited to exploring the temporal correspondence of FOS peaks to those of ERPs. The purpose of this study was to systematically quantify the relationship between FOS and ERP responses to a visual oddball task in both time and frequency domains. Near-infrared spectroscopy (NIRS) and electroencephalography (EEG) sensors were co-located over the prefrontal cortex while participants performed a visual oddball task...
May 16, 2018: NeuroImage
Ilia Kaminker, Songi Han
Dynamic nuclear polarization (DNP) takes center stage in nuclear magnetic resonance (NMR) as a tool to amplify its signal by orders of magnitude through the transfer of polarization from electron to nuclear spins. In contrast to modern NMR and electron paramagnetic resonance (EPR) that extensively rely on pulses for spin manipulation in the time domain, the current mainstream DNP technology exclusively relies on monochromatic continuous wave (CW) irradiation. This study introduces arbitrary phase shaped pulses that constitute a train of coherent chirp pulses in the time domain at 200 GHz (7 Tesla) to dramatically enhance the saturation bandwidth and DNP performance compared to CW DNP, yielding up to 500-fold in NMR signal enhancements...
May 18, 2018: Journal of Physical Chemistry Letters
Nian-Ke Chen, Xian-Bin Li, Junhyeok Bang, Xue-Peng Wang, Dong Han, Damien West, Shengbai Zhang, Hong-Bo Sun
Time-dependent density-functional theory molecular dynamics reveals an unexpected effect of optical excitation in the experimentally observed rhombohedral-to-cubic transition of GeTe. The excitation induces coherent forces along [001], which may be attributed to the unique energy landscape of Peierls-distorted solids. The forces drive the A_{1g} optical phonon mode in which Ge and Te move out of phase. Upon damping of the A_{1g} mode, phase transition takes place, which involves no atomic diffusion, defect formation, or the nucleation and growth of the cubic phase...
May 4, 2018: Physical Review Letters
Jared Rovny, Robert L Blum, Sean E Barrett
A discrete time crystal (DTC) is a robust phase of driven systems that breaks the discrete time translation symmetry of the driving Hamiltonian. Recent experiments have observed DTC signatures in two distinct systems. Here we show nuclear magnetic resonance observations of DTC signatures in a third, strikingly different system: an ordered spatial crystal. We use a novel DTC echo experiment to probe the coherence of the driven system. Finally, we show that interactions during the pulse of the DTC sequence contribute to the decay of the signal, complicating attempts to measure the intrinsic lifetime of the DTC...
May 4, 2018: Physical Review Letters
Fei Xue, A H MacDonald
We study the phase diagram of a model quantum spin Hall system as a function of band inversion and band-coupling strength, demonstrating that when band hybridization is weak, an interaction-induced nematic insulator state emerges over a wide range of band inversion. This property is a consequence of the long-range Coulomb interaction, which favors interband phase coherence that is weakly dependent on momentum and therefore frustrated by the single-particle Hamiltonian at the band inversion point. For weak band hybridization, interactions convert the continuous gap closing topological phase transition at inversion into a pair of continuous phase transitions bounding a state with broken time-reversal and rotational symmetries...
May 4, 2018: Physical Review Letters
Luca Giannessi, Enrico Allaria, Kevin C Prince, Carlo Callegari, Giuseppe Sansone, Kiyoshi Ueda, Toru Morishita, Chien Nan Liu, Alexei N Grum-Grzhimailo, Elena V Gryzlova, Nicolas Douguet, Klaus Bartschat
The seeded Free-Electron Laser (FEL) FERMI is the first source of short-wavelength light possessing the full coherence of optical lasers, together with the extreme power available from FELs. FERMI provides longitudinally coherent radiation in the Extreme Ultraviolet and soft x-ray spectral regions, and therefore opens up wide new fields of investigation in physics. We first propose experiments exploiting this property to provide coherent control of the photoionization of neon and helium, carry out numerical calculations to find optimum experimental parameters, and then describe how these experiments may be realized...
May 17, 2018: Scientific Reports
Giovanni Batignani, Giuseppe Fumero, Ajay Ram Srimath Kandada, Giulio Cerullo, Marina Gandini, Carino Ferrante, Annamaria Petrozza, Tullio Scopigno
Electronic properties and lattice vibrations are expected to be strongly correlated in metal-halide perovskites, due to the soft fluctuating nature of their crystal lattice. Thus, unveiling electron-phonon coupling dynamics upon ultrafast photoexcitation is necessary for understanding the optoelectronic behavior of the semiconductor. Here, we use impulsive vibrational spectroscopy to reveal vibrational modes of methylammonium lead-bromide perovskite under electronically resonant and non-resonant conditions...
May 17, 2018: Nature Communications
Björn Herrmann, Ingrid S Johnsrude
The ability to detect regularities in sound (i.e., recurring structure) is critical for effective perception, enabling, for example, change detection and prediction. Two seemingly unconnected lines of research concern the neural operations involved in processing regularities: one investigates how neural activity synchronizes with temporal regularities (e.g., frequency modulation; FM) in sounds, whereas the other focuses on increases in sustained activity during stimulation with repeating tone-frequency patterns...
May 17, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
John A Wells, Christine R Gonzales, Brian B Berger, Victor H Gonzalez, Brian D Sippy, Gabriela Burian
BACKGROUND AND OBJECTIVE: This phase 1 study evaluated the safety and tolerability of single intravitreous injections (IVIs) of ICON-1 (Iconic Therapeutics, South San Francisco, CA) in patients with neovascular age-related macular degeneration (nAMD). ICON-1 is a modified factor VIIa protein linked with the Fc portion of a human immunoglobulin G1. The molecule binds tissue factor overexpressed on choroidal neovascularization (CNV) in AMD. PATIENTS AND METHODS: Open-label, interventional, dose-escalation trial in 18 patients with CNV due to AMD, with six patients per dose cohort...
May 1, 2018: Ophthalmic Surgery, Lasers & Imaging Retina
Hsi-Hsun Chen, Yu-Zi Lin, Yuan Luo
Quantitative phase imaging has been investigated to retrieve optical phase information of an object, and applied to biological microscopy and related medical studies. In recent examples, differential phase contrast (DPC) microscopy can recover phase image of thin sample under multi-axis intensity measurements in wide field scheme. Unlike conventional DPC, based on theoretical approach under partially coherent condition, we propose a new method to achieve isotropic differential phase contrast (iDPC) with high accuracy and stability for phase recovery in simple and high-speed fashion...
May 16, 2018: Journal of Biophotonics
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"