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Pulse transit time

S Longhi
Parity-time (PT) symmetry is one of the most important accomplishments in optics over the past decade. Here the concept of PT mode-locking (ML) of a laser is introduced, in which active phase-locking of cavity axial modes is realized by asymmetric mode coupling in a complex time crystal. PT ML shows a transition from single- to double-pulse emission as the PT symmetry breaking point is crossed. The transition can show a turbulent behavior, depending on a dimensionless modulation parameter that plays the same role as the Reynolds number in hydrodynamic flows...
October 1, 2016: Optics Letters
Rainer Engelken, Farzad Farkhooi, David Hansel, Carl van Vreeswijk, Fred Wolf
Neuronal activity in the central nervous system varies strongly in time and across neuronal populations. It is a longstanding proposal that such fluctuations generically arise from chaotic network dynamics. Various theoretical studies predict that the rich dynamics of rate models operating in the chaotic regime can subserve circuit computation and learning. Neurons in the brain, however, communicate via spikes and it is a theoretical challenge to obtain similar rate fluctuations in networks of spiking neuron models...
2016: F1000Research
Oleksandr Kyriienko, Anders S Sørensen
We propose a microwave frequency single-photon transistor which can operate under continuous wave probing and represents an efficient single microwave photon detector. It can be realized using an impedance matched system of a three level artificial ladder-type atom coupled to two microwave cavities connected to input-output waveguides. Using a classical drive on the upper transition, we find parameter space where a single photon control pulse incident on one of the cavities can be fully absorbed into hybridized excited states...
September 30, 2016: Physical Review Letters
Pedro Franco Navarro, David J Benson, Vitali F Nesterenko
The shock waves generated by a plate impact are numerically investigated in Al-W laminates with different mesostructures. The main characteristic time scales (and the corresponding spatial scales) related to the formation of the stationary shock are identified: the duration (width) of the leading front, the time (distance) from the impact required to establish a stationary profile, and the shock front width, identified as a time span (distance) from the initial state to the final quasiequilibrium state. It is demonstrated that the width of the leading front and the maximum strain rates are determined by the dispersive and the nonlinear parameters of the laminate and not by the dissipation, as is the case for uniform solids...
September 2016: Physical Review. E
Yongfeng Guo, Kerry Flegel, Jayashree Kumar, Daniel J McKay, Laura A Buttitta
During development cell proliferation and differentiation must be tightly coordinated to ensure proper tissue morphogenesis. Because steroid hormones are central regulators of developmental timing, understanding the links between steroid hormone signaling and cell proliferation is crucial to understanding the molecular basis of morphogenesis. Here we examined the mechanism by which the steroid hormone ecdysone regulates the cell cycle in Drosophila We find that a cell cycle arrest induced by ecdysone in Drosophila cell culture is analogous to a G2 cell cycle arrest observed in the early pupa wing...
October 13, 2016: Biology Open
Sezin Unal, Ebru Ergenekon, Selma Aktas, Serdar Beken, Nilgun Altuntas, Ebru Kazanci, Ferit Kulali, Ibrahim M Hirfanoglu, Esra Onal, Canan Turkyilmaz, Esin Koc, Yildiz Atalay
BACKGROUND: Perfusion index (PI) is becoming a part of clinical practice in neonatology to monitor peripheral perfusion noninvasively. Hemodynamic and respiratory changes occur in newborns during the transition period after birth in which peripheral perfusion may be affected. Tachypnea is a frequent symptom during this period. While some tachypneic newborns get well in less than 6 h and diagnosed as "delayed transition", others get admitted to intensive care unit which transient tachypnea of newborn (TTN) being the most common diagnosis among them...
October 7, 2016: BMC Pediatrics
Christian Burger, Nora G Kling, Robert Siemering, Ali S Alnaser, Boris Bergues, Abdallah M Azzeer, Robert Moshammer, Regina de Vivie-Riedle, Matthias Kübel, Matthias F Kling
The migration of hydrogen atoms resulting in the isomerization of hydrocarbons is an important process which can occur on ultrafast timescales. Here, we visualize the light-induced hydrogen migration of acetylene to vinylidene in an ionic state using two synchronized 4 fs intense laser pulses. The first pulse induces hydrogen migration, and the second is used for monitoring transient structural changes via Coulomb explosion imaging. Varying the time delay between the pulses reveals the migration dynamics with a time constant of 54 ± 4 fs as observed in the H(+) + H(+) + CC(+) channel...
September 15, 2016: Faraday Discussions
Fabian Brunner, Laura Martínez-Sarti, Sarah Keller, Antonio Pertegás, Alessandro Prescimone, Edwin C Constable, Henk J Bolink, Catherine E Housecroft
A series of heteroleptic [Cu(N^N)(P^P)][PF6] complexes is described in which P^P = bis(2-(diphenylphosphino)phenyl)ether (POP) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos) and N^N = 4,4'-diphenyl-6,6'-dimethyl-2,2'-bipyridine substituted in the 4-position of the phenyl groups with atom X (N^N = 1 has X = F, 2 has X = Cl, 3 has X = Br, 4 has X = I; the benchmark N^N ligand with X = H is 5). These complexes have been characterized by multinuclear NMR spectroscopy, mass spectrometry, elemental analyses and cyclic voltammetry; representative single crystal structures are also reported...
September 27, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
David A Hirsh, Aaron J Rossini, Lyndon Emsley, Robert W Schurko
In this work, we show how to obtain efficient dynamic nuclear polarization (DNP) enhanced (35)Cl solid-state NMR (SSNMR) spectra at 9.4 T and demonstrate how they can be used to characterize the molecular-level structure of hydrochloride salts of active pharmaceutical ingredients (APIs) in both bulk and low wt% API dosage forms. (35)Cl SSNMR central-transition powder patterns of chloride ions are typically tens to hundreds of kHz in breadth, and most cannot be excited uniformly with high-power rectangular pulses or acquired under conditions of magic-angle spinning (MAS)...
September 21, 2016: Physical Chemistry Chemical Physics: PCCP
Jian Lu, Yaqing Zhang, Harold Y Hwang, Benjamin K Ofori-Okai, Sharly Fleischer, Keith A Nelson
Ultrafast 2D spectroscopy uses correlated multiple light-matter interactions for retrieving dynamic features that may otherwise be hidden under the linear spectrum; its extension to the terahertz regime of the electromagnetic spectrum, where a rich variety of material degrees of freedom reside, remains an experimental challenge. We report a demonstration of ultrafast 2D terahertz spectroscopy of gas-phase molecular rotors at room temperature. Using time-delayed terahertz pulse pairs, we observe photon echoes and other nonlinear signals resulting from molecular dipole orientation induced by multiple terahertz field-dipole interactions...
October 4, 2016: Proceedings of the National Academy of Sciences of the United States of America
Leigh Mickelson-Young, Emily Wear, Patrick Mulvaney, Tae-Jin Lee, Eric S Szymanski, George Allen, Linda Hanley-Bowdoin, William Thompson
The duration of the DNA synthesis stage (S phase) of the cell cycle is fundamental in our understanding of cell cycle kinetics, cell proliferation, and DNA replication timing programs. Most S-phase duration estimates that exist for plants are based on indirect measurements. We present a method for directly estimating S-phase duration by pulse-labeling root tips or actively dividing suspension cells with the halogenated thymidine analog 5-ethynl-2'-deoxyuridine (EdU) and analyzing the time course of replication with bivariate flow cytometry...
October 3, 2016: Journal of Experimental Botany
I Dierickx, S Van Hooland, K Tomsin, D Vanercke, W Cools, H Fransen, W Gyselaers
INTRODUCTION: Studying the venous compartment may add valuable information on background mechanisms and (patho)physiology of the cardiovascular system in normal pregnancies and pregnancies complicated by preeclampsia. Every component of the venous pulse wave is reflecting a specific stage of the cardiac cycle in the right atrium, and can be recognized in the neck veins, the hepatic and the renal veins. Previous studies have demonstrated the repeatability and reproducibility of venous Doppler sonography and venous pulse transit time in renal interlobar and hepatic veins...
August 2016: Journal of Maternal-fetal & Neonatal Medicine
Jun Nishida, Chang Yan, Michael D Fayer
Polarization-selective angle-resolved infrared pump-probe spectroscopy was developed and used to study the orientational dynamics of a planar alkylsiloxane monolayer functionalized with a rhenium metal carbonyl headgroup on an SiO2 surface. The technique, together with a time-averaged infrared linear dichroism measurement, characterized picosecond orientational relaxation of the headgroup occurring at the monolayer-air interface by employing several sets of incident angles of the infrared pulses relative to the sample surface...
October 12, 2016: Journal of the American Chemical Society
V N Gridnev
We study theoretically the light-induced magnetization switching in a binary ferrimagnet of the type [Formula: see text], randomly occupied by two different species of magnetic ions. The localized spins are coupled with spins of itinerant electrons via s-d exchange interaction. Model parameters are chosen so that to achieve similarity between magnetic characteristics of the model and those of ferrimagnetic rare-earth-transition metal GdFeCo alloys. The switching is triggered by heating of the itinerant electrons by a laser pulse...
September 26, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Qin Cui, Jinglong Lan, Zhi Lin, Bin Xu, Huiying Xu, Zhiping Cai, Xiaodong Xu, Jian Zhang, Jun Xu
We report on high-performance infrared lasers at 0.94 μm based on quasi-three-level transition of F<sub>3/2</sub>4→I<sub>9/2</sub>4 in Nd:LuYAG mixed crystal, for the first time to our knowledge. The maximum output power was achieved to 5.64 W with slope efficiency of approximately 52.5% at 946 nm. The simultaneous dual-wavelength laser at 939 and 946 nm is also obtained with maximum output power of 3.61 W and slope efficiency of 34.8% by introducing a glass etalon into the cavity...
September 10, 2016: Applied Optics
Delfino Reyes, Marco Camacho, Miguel Camacho, Miguel Mayorga, Duncan Weathers, Greg Salamo, Zhiming Wang, Arup Neogi
The synthesis of fluorescent carbon dots-like nanostructures (CNDs) obtained through the laser ablation of a carbon solid target in liquid environment is reported. The ablation process was induced in acetone with laser pulses of 1064, 532, and 355 nm under different irradiation times. Close-spherical amorphous CNDs with sizes between 5 and 20 nm, whose abundance strongly depends on the ablation parameters were investigated using electron microscopy and was confirmed using absorption and emission spectroscopies...
December 2016: Nanoscale Research Letters
Nahid Talebi
Interference patterns are not only a defining characteristic of waves, but also have several applications; characterization of coherent processes and holography. Spatial holography with electron waves, has paved the way towards space-resolved characterization of magnetic domains and electrostatic potentials with angstrom spatial resolution. Another impetus in electron microscopy has been introduced by ultrafast electron microscopy which uses pulses of sub-picosecond durations for probing a laser induced excitation of the sample...
2016: Scientific Reports
Ilka Siebels, Stefan Dröse
The charge translocation by purified reconstituted mitochondrial complex I from the obligate aerobic yeast Yarrowia lipolytica was investigated after adsorption of proteoliposomes to solid-supported membranes. In presence of n-decylubiquinone (DBQ), pulses of NADH provided by rapid solution exchange induced charge transfer reflecting steady-state pumping activity of the reconstituted enzyme. The signal amplitude increased with time, indicating 'deactive→active' transition of the Yarrowia complex I. Furthermore, an increase of the membrane-conductivity after addition of 5-(N-ethyl-N-isopropyl)amiloride (EIPA) was detected which questiones the use of EIPA as an inhibitor of the Na(+)/H(+)-antiporter-like subunits of complex I...
October 14, 2016: Biochemical and Biophysical Research Communications
Leonid Bolotov, Yuta Saito, Tetsuya Tada, Junji Tominaga
Chalcogenide superlattice (SL) phase-change memory materials are leading candidates for non-volatile, energy-efficient electric memory where the electric conductance switching is caused by the atom repositioning in the constituent layers. Here, we study the time evolution of the electric conductance in [(GeTe)2/(Sb2Te3)1]4 SLs upon the application of an external pulsed electric field by analysing the structural and electrical responses of the SL films with scanning probe microscopy (SPM) and scanning probe lithography (SPL)...
2016: Scientific Reports
Grzegorz Styczynski, Adam Rdzanek, Arkadiusz Pietrasik, Janusz Kochman, Zenon Huczek, Piotr Sobieraj, Zbigniew Gaciong, Cezary Szmigielski
BACKGROUND: Aortic pulse-wave velocity (PWV) is a measure of aortic stiffness that has a prognostic role in various diseases and in the general population. A number of methods are used to measure PWV, including Doppler ultrasound. Although echocardiography has been used for PWV measurement, to the authors' knowledge, it has never been tested against an invasive reference method at the same time point. Therefore, the aim of this study was to compare prospectively an echocardiographic PWV measurement, called echo-PWV, with an invasive study...
September 7, 2016: Journal of the American Society of Echocardiography
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