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Renaud Schuck, Mary Ann Go, Stefania Garasto, Stephanie Reynolds, Pier Luigi Dragotti, Simon Schultz
OBJECTIVE: Multi-photon laser scanning microscopy provides a powerful tool for monitoring the spatiotemporal dynamics of neural circuit activity. It is, however, intrinsically a point scanning technique. Standard raster scanning enables imaging at subcellular resolution; however, acquisition rates are limited by the size of the field of view to be scanned. Recently developed scanning strategies such as Travelling Salesman Scanning (TSS) have been developed to maximize cellular sampling rate by scanning only select regions in the field of view corresponding to locations of interest such as somata...
November 13, 2017: Journal of Neural Engineering
Ying-Qiu He, Dong Ding, Feng-Li Yan, Ting Gao
We describe a method to detect twin-beam multiphoton entanglement based on a beam splitter and weak nonlinearities. For the twin-beam four-photon entanglement, we explore a symmetry detector. It works not only for collecting two-pair entangled states directly from the spontaneous parametric down-conversion process, but also for generating them by cascading these symmetry detectors. Surprisingly, by calculating the iterative coefficient and the success probability we show that with a few iterations the desired two-pair can be obtained from a class of four-photon entangled states...
November 10, 2017: Scientific Reports
Ching-Chi Shen, Tsung-Ting Tsai, Jun-Yi Wu, Jr-Wei Ho, Yi-Wei Chen, Po-Yuan Cheng
In this paper, we give a full account of our previous work [C. C. Shen et al., J. Chem. Phys. 141, 171103 (2014)] on the study of an ultrafast photoionization-induced proton transfer (PT) reaction in the phenol-ammonia (PhOH-NH3) complex using ultrafast time-resolved ion photofragmentation spectroscopy implemented by the photoionization-photofragmentation pump-probe detection scheme. Neutral PhOH-NH3 complexes prepared in a free jet are photoionized by femtosecond 1 + 1 resonance-enhanced multiphoton ionization via the S1 state...
October 28, 2017: Journal of Chemical Physics
Nicolas C Pégard, Alan R Mardinly, Ian Antón Oldenburg, Savitha Sridharan, Laura Waller, Hillel Adesnik
Optical methods capable of manipulating neural activity with cellular resolution and millisecond precision in three dimensions will accelerate the pace of neuroscience research. Existing approaches for targeting individual neurons, however, fall short of these requirements. Here we present a new multiphoton photo-excitation method, termed three-dimensional scanless holographic optogenetics with temporal focusing (3D-SHOT), which allows precise, simultaneous photo-activation of arbitrary sets of neurons anywhere within the addressable volume of a microscope...
October 31, 2017: Nature Communications
Oliver J Muensterer, Sibylle Waldron, Yoon Jung Boo, Claudius Ries, Lisa Sehls, Frank Simon, Larissa Seidmann, Jérôme Birkenstock, Jan Gödeke
BACKGROUND: The prognosis of solid pediatric tumors strongly correlates with accurate staging and complete local control. Currently, surgeons rely on macroscopic cues and intraoperative cryosection to determine resection borders. Multiphoton Microscopy (MPM) is a real time technique that allows imaging of tissue without time-consuming tissue processing. PURPOSE: This pilot study evaluates the diagnostic potential of MPM in pediatric solid tumors compared to routine histopathology...
October 30, 2017: International Journal of Surgery
Karl J Lewis, Dorra Frikha-Benayed, Joyce Louie, Samuel Stephen, David C Spray, Mia M Thi, Zeynep Seref-Ferlengez, Robert J Majeska, Sheldon Weinbaum, Mitchell B Schaffler
Osteocytes are considered to be the major mechanosensory cells of bone, but how osteocytes in vivo process, perceive, and respond to mechanical loading remains poorly understood. Intracellular calcium (Ca(2+)) signaling resulting from mechanical stimulation has been widely studied in osteocytes in vitro and in bone explants, but has yet to be examined in vivo. This is achieved herein by using a three-point bending device which is capable of delivering well-defined mechanical loads to metatarsal bones of living mice while simultaneously monitoring the intracellular Ca(2+) responses of individual osteocytes by using a genetically encoded fluorescent Ca(2+) indicator...
October 31, 2017: Proceedings of the National Academy of Sciences of the United States of America
K Ono, G Giavaras, T Tanamoto, T Ohguro, X Hu, F Nori
We study hole spin resonance in a p-channel silicon metal-oxide-semiconductor field-effect transistor. In the subthreshold region, the measured source-drain current reveals a double dot in the channel. The observed spin resonance spectra agree with a model of strongly coupled two-spin states in the presence of a spin-orbit-induced anticrossing. Detailed spectroscopy at the anticrossing shows a suppressed spin resonance signal due to spin-orbit-induced quantum state mixing. This suppression is also observed for multiphoton spin resonances...
October 13, 2017: Physical Review Letters
Tomás Ramos, Juan José García-Ripoll
In this work we develop an experimental procedure to interrogate the single- and multiphoton scattering matrices of an unknown quantum system interacting with propagating photons. Our proposal requires coherent state laser or microwave inputs and homodyne detection at the scatterer's output, and provides simultaneous information about multiple-elastic and inelastic-segments of the scattering matrix. The method is resilient to detector noise and its errors can be made arbitrarily small by combining experiments at various laser powers...
October 13, 2017: Physical Review Letters
Md Mehboob Alam, Ramprasad Misra, Kenneth Ruud
Channel interference plays a crucial role in understanding the physics behind multiphoton absorption processes. In this work, we study the role of channel interference and solvent effects on the two-photon absorption in aryl-substituted boron dipyrromethene (BODIPY) dyes, a class of intramolecular charge-transfer (ICT) molecules. For this purpose, we consider fourteen dyes of this class with various donor/acceptor substitutions at the para position of the phenyl ring and with or without methyl (-CH3) substitution on the BODIPY moiety...
November 8, 2017: Physical Chemistry Chemical Physics: PCCP
Maximilian J Waldner, Timo Rath, Sebastian Schürmann, Christian Bojarski, Raja Atreya
In recent years, various technological developments markedly improved imaging of mucosal inflammation in patients with inflammatory bowel diseases. Although technological developments such as high-definition-, chromo-, and autofluorescence-endoscopy led to a more precise and detailed assessment of mucosal inflammation during wide-field endoscopy, probe-based and stationary confocal laser microscopy enabled in vivo real-time microscopic imaging of mucosal surfaces within the gastrointestinal tract. Through the use of fluorochromes with specificity against a defined molecular target combined with endoscopic techniques that allow ultrastructural resolution, molecular imaging enables in vivo visualization of single molecules or receptors during endoscopy...
2017: Frontiers in Immunology
Barbara Lynch, Christelle Bonod-Bidaud, Guillaume Ducourthial, Jean-Sébastien Affagard, Stéphane Bancelin, Sotiris Psilodimitrakopoulos, Florence Ruggiero, Jean-Marc Allain, Marie-Claire Schanne-Klein
Skin aging is a complex process that strongly affects the mechanical behavior of skin. This study aims at deciphering the relationship between age-related changes in dermis mechanical behavior and the underlying changes in dermis microstructure. To that end, we use multiphoton microscopy to monitor the reorganization of dermal collagen during mechanical traction assays in ex vivo skin from young and old mice. The simultaneous variations of a full set of mechanical and microstructural parameters are analyzed in the framework of a multiscale mechanical interpretation...
October 23, 2017: Scientific Reports
Jenelle L Wallace, Martin Wienisch, Venkatesh N Murthy
New neurons appear only in a few regions of the adult mammalian brain and become integrated into existing circuits. Little is known about the functional development of individual neurons in vivo. We examined the functional life history of adult-born granule cells (abGCs) in the olfactory bulb using multiphoton imaging in awake and anesthetized mice. We found that abGCs can become responsive to odorants soon after they arrive in the olfactory bulb. Tracking identified abGCs over weeks revealed that the robust and broadly tuned responses of most newly arrived abGCs gradually become more selective over a period of ∼3 weeks, but a small fraction achieves broader tuning with maturation...
November 15, 2017: Neuron
Manabu Kanno, Nobuyoshi Inada, Hirohiko Kono
We theoretically explore the effects of optical ellipticity on single-active-electron multiphoton excitation in atoms and (nearly) spherical molecules irradiated by intense polarized laser fields. This work was motivated by the experimental and theoretical studies of Hertel et al. [Phys. Rev. Lett. 102, 023003 (2009) and Phys. Rev. A 79, 053414 (2009)], who reported pronounced changes in the near-infrared-induced ion yields of xenon and C60 as a function of ellipticity (in particular, yield reduction for circular polarization) at low light intensities and derived a perturbative cross section formula to describe such polarization effects by assuming that the excited-state energies and radial transition electric dipole moments of the system are independent of the azimuthal quantum number l...
October 21, 2017: Journal of Chemical Physics
Martin Lehr, Benjamin Foerster, Mathias Schmitt, Katja Krüger, Carsten Sönnichsen, Gerd Schönhense, Hans-Joachim Elmers
Electron emission by femtosecond laser pulses from individual Au nanorods is studied with a time-of-flight momentum resolving photoemission electron microscope (ToF k-PEEM). The Au nanorods adhere to a transparent indium-tin oxide substrate, allowing for illumination from the rear side at normal incidence. Localized plasmon polaritons are resonantly excited at 800 nm with 100 fs long pulses. The momentum distribution of emitted electrons reveals two distinct emission mechanisms: a coherent multiphoton photoemission process from the optically heated electron gas leads to an isotropic emission distribution...
October 26, 2017: Nano Letters
Shaun Pacheco, Chengliang Wang, Monica K Chawla, Minhkhoi Nguyen, Brend K Baggett, Urs Utzinger, Carol A Barnes, Rongguang Liang
Confocal fluorescence microscopy is often used in brain imaging experiments, however conventional confocal microscopes are limited in their field of view, working distance, and speed for high resolution imaging. We report here the development of a novel high resolution, high speed, long working distance, and large field of view confocal fluorescence microscope (H(2)L(2)-CFM) with the capability of multi-region and multifocal imaging. To demonstrate the concept, a 0.5 numerical aperture (NA) confocal fluorescence microscope is prototyped with a 3 mm × 3 mm field of view and 12 mm working distance, an array of 9 beams is scanned over the field of view in 9 different regions to speed up the acquisition time by a factor of 9...
October 17, 2017: Scientific Reports
Babak Amirsolaimani, Benjamin Cromey, N Peyghambarian, Khanh Kieu
We present the design, construction, and characterization of a multiphoton microscope that uses reflective elements for beam shaping and steering. This compact all reflective design removes the adverse effects of dispersion on laser pulse broadening as well as chromatic aberration in the focusing of broadband and multicolored laser sources. The design of this system is discussed in detail, including aberrations analysis via ray-tracing simulation and opto-mechanical design. The resolution of this mirror based all-reflective microscope is characterized using fluorescent microbeads...
September 18, 2017: Optics Express
Shilin Hu, Jing Chen, Xiaolei Hao, Weidong Li, Li Guo, Shensheng Han
Using solution of the full three-dimensional time-dependent Schrödinger equation (TDSE) in prolate spheroidal coordinates, we investigate the orientation dependence of ionization of H2+ in near-infrared laser fields. It is found that, the ionization probability decreases as a function of the alignment angle in tunneling ionization regime, while it ascends with the increase of orientation angle in multiphoton ionization regime for the internuclear distance R=2 a.u. Furthermore, the result obtained by the length gauge strong-field approximation theory is in qualitative agreement with that calculated by the TDSE but the radiation gauge strong-field approximation and molecular ADK theories fail to reproduce the TDSE result...
September 18, 2017: Optics Express
Fangzhou Cheng, Lori A Birder, F Aura Kullmann, Jack Hornsby, Paul N Watton, Simon Watkins, Mark Thompson, Anne M Robertson
In this work, we re-evaluated long-standing conjectures as to the source of the exceptionally large compliance of the bladder wall. Whereas these conjectures were based on indirect measures of loading mechanisms, in this work we take advantage of advances in bioimaging to directly assess collagen fibers and wall architecture during biaxial loading. A custom biaxial mechanical testing system compatible with multiphoton microscopy was used to directly measure the layer-dependent collagen fiber recruitment in bladder tissue from 9 male Fischer rats (4 adult and 5 aged)...
October 16, 2017: Biomechanics and Modeling in Mechanobiology
Genevieve Vigil, Yide Zhang, Aamir Khan, Scott Howard
Here we recount the standard two-level model that describes saturated excitation (SAX) in multiphoton microscopy (MPM), a new technique for super-resolution fluorescence microscopy in scattering tissue, which requires no special chemistry and only simple modifications to a commercial MPM microscope. We use the model to study conditions required for improvements in MPM SAX resolution and experimental implementation strategies. Simulation results find zeros, or nodes, in the frequency response, which generate highly irregular point-spread functions (PSFs), such as rings and ripples, that contain spatial frequency content >3× larger than allowed by diffraction...
July 1, 2017: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Marco Pensalfini, Eric Haertel, Raoul Hopf, Mateusz Wietecha, Sabine Werner, Edoardo Mazza
A multiscale mechanics approach to the characterization of murine excisional wounds subjected to uniaxial tensile loading is presented. Local strain analysis at a physiological level of tension uncovers the presence of two distinct regions within the wound: i) a very compliant peripheral cushion and ii) a core area undergoing modest deformation. Microstructural visualizations of stretched wound specimens show negligible engagement of the collagen located in the center of a 7-day old wound; fibers remain coiled despite the applied tension, confirming the existence of a mechanically isolated wound core...
October 12, 2017: Acta Biomaterialia
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