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K Nagaya, D Iablonskyi, N V Golubev, K Matsunami, H Fukuzawa, K Motomura, T Nishiyama, T Sakai, T Tachibana, S Mondal, S Wada, K C Prince, C Callegari, C Miron, N Saito, M Yabashi, Ph V Demekhin, L S Cederbaum, A I Kuleff, M Yao, K Ueda
In high-intensity laser light, matter can be ionized by direct multiphoton absorption even at photon energies below the ionization threshold. However on tuning the laser to the lowest resonant transition, the system becomes multiply excited, and more efficient, indirect ionization pathways become operative. These mechanisms are known as interatomic Coulombic decay (ICD), where one of the species de-excites to its ground state, transferring its energy to ionize another excited species. Here we show that on tuning to a higher resonant transition, a previously unknown type of interatomic Coulombic decay, intra-Rydberg ICD occurs...
December 5, 2016: Nature Communications
Klaus Reinhardt, Hans Georg Breunig, Karsten König
The decay time of the fluorescence of excited molecules, called fluorescence lifetime, can provide information about the cuticle composition additionally to widely used spectral characteristics. We compared autofluorescence lifetimes of different cuticle regions in the copulatory organ of females of the bedbug, Cimex lectularius. After two-photon excitation at 720 nm, regions recently characterised as being rich in resilin showed a longer bimodal distribution of the mean autofluorescence lifetime τm (tau-m) at 0...
November 29, 2016: Arthropod Structure & Development
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
Xi-Lin Wang, Luo-Kan Chen, W Li, H-L Huang, C Liu, C Chen, Y-H Luo, Z-E Su, D Wu, Z-D Li, H Lu, Y Hu, X Jiang, C-Z Peng, L Li, N-L Liu, Yu-Ao Chen, Chao-Yang Lu, Jian-Wei Pan
We report the first experimental demonstration of quantum entanglement among ten spatially separated single photons. A near-optimal entangled photon-pair source was developed with simultaneously a source brightness of ∼12  MHz/W, a collection efficiency of ∼70%, and an indistinguishability of ∼91% between independent photons, which was used for a step-by-step engineering of multiphoton entanglement. Under a pump power of 0.57 W, the ten-photon count rate was increased by about 2 orders of magnitude compared to previous experiments, while maintaining a state fidelity sufficiently high for proving the genuine ten-particle entanglement...
November 18, 2016: Physical Review Letters
Chen Zhang, Wei Li, Yi Hu, Tao Yang, Ge Jin, Xiao Jiang
In this paper, we demonstrate a coincidence counting system with 48 input channels which is aimed to count all coincidence events, up to 531 441 kinds, in a multiphoton experiment. Using the dynamic delay adjusting inside the Field Programmable Gate Array, the alignment of photon signals of 48 channels is achieved. After the alignment, clock phase shifting is used to sample signal pulses. Logic constraints are used to stabilize the pulse width. The coincidence counting data stored in a 1G bit external random access memory will be sent to the computer to analyze the amount of 2-, 3-, 4-, 5-, and 6-fold coincidence events...
November 2016: Review of Scientific Instruments
Chao Zhang, Yun-Feng Huang, Cheng-Jie Zhang, Jian Wang, Bi-Heng Liu, Chuan-Feng Li, Guang-Can Guo
High-quality entangled photon pairs generated via spontaneous parametric down-conversion have made great contributions to the modern quantum information science and the fundamental tests of quantum mechanics. However, the quality of the entangled states decreases sharply when moving from biphoton to multiphoton experiments, mainly due to the lack of interactions between photons. Here, for the first time, we generate a four-photon Greenberger-Horne-Zeilinger state with a fidelity of 98%, which is even comparable to the best fidelity of biphoton entangled states...
November 28, 2016: Optics Express
L T Bang, H Y Wu, Y Zhao, E G Kim, N Kim
Multilayer images of living cells are typically obtained using confocal or multiphoton microscopy. However, limitations on the distance between consecutive scan layers hinder high-resolution three-dimensional reconstruction, and scattering strongly degrades images of living cell components. Consequently, when overlapping information from different layers is focused on a specific point in the camera, this causes uncertainty in the depiction of the cell components. We propose a method that combines the Fresnel incoherent correlation holography and a depth-of-focus reduction algorithm to enhance the depth information of three-dimensional cell images...
December 1, 2016: Journal of Microscopy
Nicolás González Bardeci, Juan Francisco Angiolini, María Cecilia De Rossi, Luciana Bruno, Valeria Levi
Fluorescence fluctuation-based methods are non-invasive microscopy tools especially suited for the study of dynamical aspects of biological processes. These methods examine spontaneous intensity fluctuations produced by fluorescent molecules moving through the small, femtoliter-sized observation volume defined in confocal and multiphoton microscopes. The quantitative analysis of the intensity trace provides information on the processes producing the fluctuations that include diffusion, binding interactions, chemical reactions and photophysical phenomena...
November 28, 2016: IUBMB Life
Mihaela Balu, Hideharu Mikami, Jue Hou, Eric O Potma, Bruce J Tromberg
We present a multiphoton microscope designed for mesoscale imaging of human skin. The system is based on two-photon excited fluorescence and second-harmonic generation, and images areas of ~0.8x0.8 mm(2) at speeds of 0.8 fps (800x800 pixels; 12 frame averages) for high signal-to-noise ratio, with lateral and axial resolutions of 0.5µm and 3.3µm, respectively. The main novelty of this instrument is the design of the scan head, which includes a fast galvanometric scanner, optimized relay optics, a beam expander and high NA objective lens...
November 1, 2016: Biomedical Optics Express
E Leung, A Xue, Y Wang, P Rougerie, V P Sharma, R Eddy, D Cox, J Condeelis
During metastasis to distant sites, tumor cells migrate to blood vessels. In vivo, breast tumor cells utilize a specialized mode of migration known as streaming, where a linear assembly of tumor cells migrate directionally towards blood vessels on fibronectin-collagen I-containing extracellular matrix (ECM) fibers in response to chemotactic signals. We have successfully reconstructed tumor cell streaming in vitro by co-plating tumors cells, macrophages and endothelial cells on 2.5 μm thick ECM-coated micro-patterned substrates...
November 28, 2016: Oncogene
Tony Kelly, Heinz Beck
OBJECTIVE: The maturation of adult-born granule cells and their functional integration into the network is thought to play a key role in the proper functioning of the dentate gyrus. In temporal lobe epilepsy, adult-born granule cells in the dentate gyrus develop abnormally and possess a hilar basal dendrite (HBD). Although morphological studies have shown that these HBDs have synapses, little is known about the functional properties of these HBDs or the intrinsic and network properties of the granule cells that possess these aberrant dendrites...
November 26, 2016: Epilepsia
Wyatt G Merrill, F Fleming Crim, Amanda S Case
We investigate the Ã-band photodissociation of CHBrCl2 at 215, 225, 235, 245, 255, and 265 nm. Following C-Br bond cleavage, resonance enhanced multiphoton ionization and time of flight mass spectrometry provide selective detection of the two product channels, from which we quantify the relative quantum yield of Br/Br* production. Velocity-map imaging of the photofragments allows us to determine the energy partitioning as a function of the photolysis energy for different exit channels. The anisotropy present in the imaging data suggests that absorption to the (3)Q0(+)(A') state is important throughout the entire region we study, though competition with other excited states is evident...
November 25, 2016: Physical Chemistry Chemical Physics: PCCP
John Heslar, Shih-I Chu
Recently, the study of near- and below- threshold regime harmonics as a potential source of intense coherent vacuum-ultraviolet radiation has received considerable attention. However, the dynamical origin of these lower harmonics, particularly for the molecular systems, is less understood and largely unexplored. Here we perform the first fully ab initio and high precision 3D quantum study of the below- and near-threshold harmonic generation of molecules in an intense 800-nm near-infrared (NIR) laser field. Combining with a synchrosqueezing transform of the quantum time-frequency spectrum and an extended semiclassical analysis, we explore in-depth the roles of various quantum trajectories, including short- and long trajectories, multiphoton trajectories, resonance-enhanced trajectories, and multiple rescattering trajectories of the below- and near- threshold harmonic generation processes...
November 24, 2016: Scientific Reports
C Fink, H A Haenssle
BACKGROUND: While the excisional biopsy and histological examination of suspicious lesions remains the current gold standard for diagnosing cutaneous melanoma (CM), there is a demand for more objective and non-invasive examination methods that may support clinicians in their decision when to biopsy or not. METHODS: This review is based on publications and guidelines retrieved by a selective search in PubMed and MEDLINE and focused on non-invasive diagnostic strategies for detecting melanoma...
November 22, 2016: Skin Research and Technology
Shukei Sugita, Takeo Matsumoto
Elastin and collagen fibers play important roles in the mechanical properties of aortic media. Because knowledge of local fiber structures is required for detailed analysis of blood vessel wall mechanics, we investigated 3D microstructures of elastin and collagen fibers in thoracic aortas and monitored changes during pressurization. Using multiphoton microscopy, autofluorescence images from elastin and second harmonic generation signals from collagen were acquired in media from rabbit thoracic aortas that were stretched biaxially to restore physiological dimensions...
November 22, 2016: Biomechanics and Modeling in Mechanobiology
Hossein Z Jooya, Kamran Reihani, Shih-I Chu
We propose a graph-theoretical formalism to study generic circuit quantum electrodynamics systems consisting of a two level qubit coupled with a single-mode resonator in arbitrary coupling strength regimes beyond rotating-wave approximation. We define colored-weighted graphs, and introduce different products between them to investigate the dynamics of superconducting qubits in transverse, longitudinal, and bidirectional coupling schemes. The intuitive and predictive picture provided by this method, and the simplicity of the mathematical construction, are demonstrated with some numerical studies of the multiphoton resonance processes and quantum interference phenomena for the superconducting qubit systems driven by intense ac fields...
November 21, 2016: Scientific Reports
Ann L B Seynhaeve, Timo L M Ten Hagen
Real-time evaluation of vascular effects in an animal skinfold window model by intravital microscopy (IVM) provides a powerful tool to improve insight into vascular development and vascular therapy. The potential of IVM to examine processes in tissues (e.g., tumors, inflammatory sites), in a noninvasive way, enables determination of the kinetics of processes under study at any given time point. The introduction of sensitive digital cameras, confocal and multiphoton microscopy, and powerful imaging software greatly improved the quality of the images acquired...
2016: Methods in Molecular Biology
Thomas Yang Sun, Ann M Haberman, Valentina Greco
Conventional, static analyses have historically been the bedrock and tool of choice for the study of skin cancers. Over the past several years, in vivo imaging of tumors using multiphoton microscopy has emerged as a powerful preclinical tool for revealing detailed cellular behaviors from the earliest moments of tumor development to the final steps of metastasis. Multiphoton microscopy allows for deep tissue penetration with relatively minor phototoxicity, rendering it an effective tool for the long-term observation of tumor evolution...
November 12, 2016: Journal of Investigative Dermatology
Denis Gagnon, François Fillion-Gourdeau, Joey Dumont, Catherine Lefebvre, Steve MacLean
Photo-induced transition probabilities in graphene are studied theoretically from the viewpoint of Floquet theory. Conduction band populations are computed for a strongly, periodically driven graphene sheet under linear, circular, and elliptic polarization. Features of the momentum spectrum of excited quasi-particles can be directly related to the avoided crossing of the Floquet quasi-energy levels. In particular, the impact of the ellipticity and the strength of the laser excitation on the avoided crossing structure-and on the resulting transition probabilities-is studied...
November 15, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Germano Piccirillo, Brigida Bochicchio, Antonietta Pepe, Katja Schenke-Layland, Svenja Hinderer
: Actinic Keratosis' (AKs) are small skin lesions that are related to a prolonged sun-damage, which can develop into invasive squamous cell carcinoma (SCC) when left untreated. Effective, specific and well tolerable therapies to cure AKs are still of great interest. Diclofenac (DCF) is the current gold standard for the local treatment of AKs in terms of costs, effectiveness, side effects and tolerability. In this work, an electrospun polylactic acid (PLA) scaffold loaded with a synthetic DCF prodrug was developed and characterized...
November 2, 2016: Acta Biomaterialia
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