Read by QxMD icon Read

phase coherence

Thomas Burwick, Alexandros Bouras
The communication-through-coherence (CTC) hypothesis states that a sending group of neurons will have a particularly strong effect on a receiving group if both groups oscillate in a phase-locked ("coherent") manner (Fries, 2005, 2015). Here, we consider a situation with two visual stimuli, one in the focus of attention and the other distracting, resulting in two sites of excitation at an early cortical area that project to a common site in a next area. Taking a modeler's perspective, we confirm the workings of a mechanism that was proposed by Bosman et al...
October 20, 2016: Neural Computation
M Garg, M Zhan, T T Luu, H Lakhotia, T Klostermann, A Guggenmos, E Goulielmakis
The frequency of electric currents associated with charge carriers moving in the electronic bands of solids determines the speed limit of electronics and thereby that of information and signal processing. The use of light fields to drive electrons promises access to vastly higher frequencies than conventionally used, as electric currents can be induced and manipulated on timescales faster than that of the quantum dephasing of charge carriers in solids. This forms the basis of terahertz (10(12) hertz) electronics in artificial superlattices, and has enabled light-based switches and sampling of currents extending in frequency up to a few hundred terahertz...
October 19, 2016: Nature
Dierck Hillmann, Hendrik Spahr, Carola Hain, Helge Sudkamp, Gesa Franke, Clara Pfäffle, Christian Winter, Gereon Hüttmann
Certain topics in research and advancements in medical diagnostics may benefit from improved temporal and spatial resolution during non-invasive optical imaging of living tissue. However, so far no imaging technique can generate entirely diffraction-limited tomographic volumes with a single data acquisition, if the target moves or changes rapidly, such as the human retina. Additionally, the presence of aberrations may represent further difficulties. We show that a simple interferometric setup-based on parallelized optical coherence tomography-acquires volumetric data with 10 billion voxels per second, exceeding previous imaging speeds by an order of magnitude...
October 20, 2016: Scientific Reports
Liat Helpman, Marie-France Marin, Santiago Papini, Xi Zhu, Gregory M Sullivan, Franklin Schneier, Mariana Neria, Erel Shvil, Maria Josefa Malaga Aragon, John C Markowitz, Martin A Lindquist, Tor Wager, Mohammad Milad, Yuval Neria
BACKGROUND: Neurobiological models of posttraumatic stress disorder (PTSD) implicate fear processing impairments in the maintenance of the disorder. Specific deficits in extinction recall, the retention of learned extinction, have been demonstrated. While deficient extinction recall, and the associated activation pattern of prefrontal and hippocampal regions, distinguishes individuals with PTSD from controls, research has not yet examined changes following treatment. We examined the behavioral and neural correlates of extinction recall before and after cognitive behavioral treatment of PTSD...
2016: NeuroImage: Clinical
Ivan Kozyryev, Louis Baum, Kyle Matsuda, John M Doyle
An experimentally feasible strategy for direct laser cooling of polyatomic molecules with six or more atoms is presented. Our approach relies on the attachment of a metal atom to a complex molecule, where it acts as an active photon cycling site. We describe a laser cooling scheme for alkaline earth monoalkoxide free radicals taking advantageof the phase space compression of a cryogenic buffer-gas beam. Possible applications are presented including laser cooling of chiral molecules and slowing of molecular beams using coherent photon processes...
October 19, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Veysi Öner, Asker Bulut
PURPOSE: Recent studies have found a choroidal thickening in amblyopic eyes and suggested that there might be a relationship between the choroid and amblyopia. The present study aimed to evaluate the effect of a six-month treatment of amblyopia on choroidal thickness in anisometropic hyperopic amblyopic children. METHODS: Thirty-two anisometropic hyperopic children with unilateral amblyopia were included in this prospective study. Subfoveal choroidal thickness was measured as the distance between the retinal pigment epithelium and the chorioscleral edge, by using spectral domain enhanced depth imaging optical coherence tomography...
October 18, 2016: Clinical & Experimental Optometry: Journal of the Australian Optometrical Association
Jinsoo Uh, M Ayaz Khan, Chiaho Hua
This study aimed to develop a practical and accurate 4-dimensional (4D) magnetic resonance imaging (MRI) method using a non-navigator, image-based internal respiratory surrogate derived by dimensionality reduction (DR). The use of DR has been previously suggested but not implemented for reconstructing 4D MRI, despite its practical advantages. We compared multiple image-acquisition schemes and refined a retrospective-sorting process to optimally implement a DR-derived surrogate. The comparison included an unconventional scheme that acquires paired slices alternately to mitigate the internal surrogate's dependency on a specific slice location...
November 7, 2016: Physics in Medicine and Biology
Yuantao Xie, Clément Le Priol, Jean J Heremans
Low-temperature quantum phase coherence lengths were experimentally measured in mesoscopic circular arenas fabricated on InGaAs quantum wells. The arenas are connected to wide sample regions by short side-wires, to investigate the effects of geometry in comparison to intrinsic materials properties on quantum decoherence. Universal conductance fluctuations were used to quantify the phase coherence lengths as a function of temperature and geometry. The experimental data show a dependence of phase coherence lengths on side-wire length and width-to-length ratio, which is accounted for by the competing effects of decoherence by coupling to the classical environment and Nyquist decoherence in ergodic wires...
October 18, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Nariyuki Saito, Nobuhisa Ishii, Teruto Kanai, Shuntaro Watanabe, Jiro Itatani
Long-wavelength lasers have great potential to become a new-generation drive laser for tabletop coherent light sources in the soft X-ray region. Because of the significantly low conversion efficiency from a long-wavelength light field to high-order harmonics, their pulse characterization has been carried out by measuring the carrier-envelope phase and/or spatial dependences of high harmonic spectra. However, these photon detection schemes, in general, have difficulty in obtaining information on the spectral phases, which is crucial to determine the temporal structures of high-order harmonics...
October 18, 2016: Scientific Reports
Yuandong Li, Woo June Choi, Wan Qin, Utku Baran, Lauren M Habenicht, Ruikang K Wang
BACKGROUND: Arteriogenesis describes the active growth of the pre-existing collateral arterioles, which is a crucial tissue-saving process in occlusive vascular diseases. NEW METHOD: We propose to use optical coherence tomography (OCT)-based microangiography (OMAG) to monitor arteriogenesis following artery transection in mouse ear and focal stroke in mouse brain. RESULTS: Our longitudinal mouse ear study shows that the growth phase of arteriogenesis, indicated by changes in collateral vessel diameter and velocity, occurs between 12-24hours after vessel occlusion...
October 14, 2016: Journal of Neuroscience Methods
Nikita Khodakovskiy, Mikhail Kalashnikov, Emilien Gontier, Franck Falcoz, Pierre-Mary Paul
Recompressed pulses from Ti:sapphire chirped-pulse lasers are accompanied by a slowly decaying post-pulse pedestal that is coherent with the main pulse. The pedestal typically consists of numerous pulses with temporal separation in the picosecond range. The source of this artifact lies in the Ti:sapphire active medium itself, both in the Kerr-lens mode-locked oscillator and in subsequent amplifiers. In the presence of substantial self-phase modulation, after recompression the post-pedestal generates a mirror-symmetric pre-pulse pedestal...
October 1, 2016: Optics Letters
Kai Song, Shuming Bai, Qiang Shi
Recent experimental and theoretical studies have revealed that quantum coherence plays an important role in the excitation energy transfer in photosynthetic light harvesting complexes. Inspired by the recent single molecule two-color double-pump experiment, we investigate theoretically the effect of pulse shaping on observing coherent energy transfer in the single bacterial light harvesting 2 (LH2) complex. It is found that, quantum coherent energy transfer can be observed when the time delay and phase difference between the two laser pulses are controlled independently...
October 17, 2016: Journal of Physical Chemistry. B
L Kilanski, A Reszka, M Górska, V Domukhovski, A Podgórni, B J Kowalski, W Dobrowolski, I V Fedorchenko, A N Aronov, S F Marenkin
We present the studies of structural, transport and magnetotransport properties of [Formula: see text]Cd x GeAs2 crystals with the chemical content changing from 0 to 1. The structural studies indicate that this alloy exists as a composite two-phase material in almost the entire range of average chemical compositions. The two phase nature of our samples does have a significant influence on the carrier transport and magnetotransport of the composite alloy. The change of the conductivity type is observed at room temperature, from p-type for [Formula: see text] to n-type for x  >  0...
October 17, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Aaron C Johnston-Peck, Igor Levin, Andrew A Herzing, Leonid A Bendersky
A pristine Li-rich layered electrode material with composition Li1.2Mn0.55Ni0.15Co0.1O2 was characterized by X-ray diffraction, transmission electron microscopy, and scanning transmission electron microscopy to determine whether it is a coherent mixture of monoclinic C2/m Li2MO3 and trigonal [Formula: see text] LiMO2 phases or a solid solution of the monoclinic phase. Contradictory results have been previously reported which can be attributed to the complexity and structural similarity of the monoclinic and trigonal phases...
September 2016: Materials Characterization
Randolph F Helfrich, Robert T Knight
The prefrontal cortex (PFC) provides the structural basis for numerous higher cognitive functions. However, it is still largely unknown which mechanisms provide the functional basis for flexible cognitive control of goal-directed behavior. Here, we review recent findings that suggest that the functional architecture of cognition is profoundly rhythmic and propose that the PFC serves as a conductor to orchestrate task-relevant large-scale networks. We highlight several studies that demonstrated that oscillatory dynamics, such as phase resetting, cross-frequency coupling (CFC), and entrainment, support PFC-dependent recruitment of task-relevant regions into coherent functional networks...
October 12, 2016: Trends in Cognitive Sciences
Alice E Liddell, Steven Allan, Ken Goss
OBJECTIVES: Compassion-focused therapy (CFT) has shown promising results for a range of clinical presentations. This study explored the therapeutic competencies required to deliver CFT and organized these into a coherent framework. DESIGN: The Delphi method was used to explore and refine competencies for delivering CFT in three rounds of data collection. METHODS: The first round involved interviews with 12 experts in CFT. Data were analysed using template analysis to generate a draft competency framework...
October 15, 2016: Psychology and Psychotherapy
Douglas McLelland, Rufin VanRullen
Several theories have been advanced to explain how cross-frequency coupling, the interaction of neuronal oscillations at different frequencies, could enable item multiplexing in neural systems. The communication-through-coherence theory proposes that phase-matching of gamma oscillations between areas enables selective processing of a single item at a time, and a later refinement of the theory includes a theta-frequency oscillation that provides a periodic reset of the system. Alternatively, the theta-gamma neural code theory proposes that a sequence of items is processed, one per gamma cycle, and that this sequence is repeated or updated across theta cycles...
October 2016: PLoS Computational Biology
K M Ratheesh, L K Seah, V M Murukeshan
The automatic calibration in Fourier-domain optical coherence tomography (FD-OCT) systems allows for high resolution imaging with precise depth ranging functionality in many complex imaging scenarios, such as microsurgery. However, the accuracy and speed of the existing automatic schemes are limited due to the functional approximations and iterative operations used in their procedures. In this paper, we present a new real-time automatic calibration scheme for swept source-based optical coherence tomography (SS-OCT) systems...
October 14, 2016: Physics in Medicine and Biology
C Wan, M Scala, G W Morley, Atm A Rahman, H Ulbricht, J Bateman, P F Barker, S Bose, M S Kim
We propose an interferometric scheme based on an untrapped nano-object subjected to gravity. The motion of the center of mass (c.m.) of the free object is coupled to its internal spin system magnetically, and a free flight scheme is developed based on coherent spin control. The wave packet of the test object, under a spin-dependent force, may then be delocalized to a macroscopic scale. A gravity induced dynamical phase (accrued solely on the spin state, and measured through a Ramsey scheme) is used to reveal the above spatially delocalized superposition of the spin-nano-object composite system that arises during our scheme...
September 30, 2016: Physical Review Letters
Michinobu Nagao, Yuzo Yamasaki, Takeshi Kamitani, Satoshi Kawanami, Masatoshi Kondo, Hiromichi Sonoda, Taisuke Fujioka, Hiroshi Honda
The purpose of this study is to analyze the geometrical characteristics of aortic root and left ventricular (LV) function in aortic stenosis (AS) using 256-slice coronary-computed tomography angiography (CCTA). Retrospective ECG-gated 256-slice CCTA data from 32 patients with tricuspid AS scheduled for aortic valve replacement, and 11 controls were analyzed. Aortic root geometry was measured using multiplanar reconstruction CT images. CCTA data set was transformed into 100 phases/cycle using motion coherence image processing...
October 13, 2016: Heart and Vessels
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"