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two photon

Rosanna P Sammons, Claudia Clopath, Samuel J Barnes
Persistent synapses are thought to underpin the storage of sensory experience, yet little is known about their structural plasticity in vivo. We investigated how persistent presynaptic structures respond to the loss of primary sensory input. Using in vivo two-photon (2P) imaging, we measured fluctuations in the size of excitatory axonal boutons in L2/3 of adult mouse visual cortex after monocular enucleation. The average size of boutons did not change after deprivation, but the range of bouton sizes was reduced...
January 16, 2018: Cell Reports
Xinran Dong, Haifeng Du, Zhi Luo, Ji'an Duan
A highly sensitive strain sensor based on a novel fiber in line Mach-Zehnder interferometer (MZI) was demonstrated experimentally. The MZI was realized by splicing a section of photonic crystal fiber (PCF) with the same length of thin core fiber (TCF) between two single mode fibers (SMFs). The fringe visibility of MZI can reach as high as 20 dB in air. In particular, the strain sensitivity of -1.95 pm/με was achieved within a range from 0 to 4000 με. Furthermore, the strain properties of different length of MZI was investigated...
January 18, 2018: Sensors
Jonathan C Taylor, Nicholas Vennart, Ian Negus, Robin Holmes, Oliver Bandmann, Christine Lo, John Fenner
The Alderson striatal phantom is frequently used to assess I-FP-CIT (Ioflupane) image quality and to test semi-quantification software. However, its design is associated with a number of limitations, in particular: unrealistic image appearances and inflexibility. A new physical phantom approach is proposed on the basis of subresolution phantom technology. The design incorporates thin slabs of attenuating material generated through additive manufacturing, and paper sheets with radioactive ink patterns printed on their surface, created with a conventional inkjet printer...
January 17, 2018: Nuclear Medicine Communications
Wei Zhu, Sang-Hyun Pyo, Pengrui Wang, Shangting You, Claire Yu, Jeffrey Alido, Justin Liu, Yew Leong, Shaochen Chen
Polycarbonates are widely used in food packages, drink bottles, and various healthcare products such as dental sealants and tooth coatings. However, bisphenol A (BPA) and phosgene used in the production of commercial polycarbonates poses major concerns to public health safety. Here, we report a green pathway to prepare BPA-free polycarbonates (BFPs) by thermal ring opening polymerization and photopolymerization. Polycarbonates prepared from two cyclic carbonates in different mole ratios demonstrated tunable mechanical stiffness, excellent thermal stability, and high optical transparency...
January 18, 2018: ACS Applied Materials & Interfaces
Jonas G Croissant, Jeffrey I Zink, Laurence Raehm, Jean-Olivier Durand
Coherent two-photon-excited (TPE) therapy in the near-infrared (NIR) provides safer cancer treatments than current therapies lacking spatial and temporal selectivities because it is characterized by a 3D spatial resolution of 1 µm3 and very low scattering. In this review, the principle of TPE and its significance in combination with organosilica nanoparticles (NPs) are introduced and then studies involving the design of pioneering TPE-NIR organosilica nanomaterials are discussed for bioimaging, drug delivery, and photodynamic therapy...
January 18, 2018: Advanced Healthcare Materials
Mustafa Mohammad Rafiei, Hossein Tavakoli-Anbaran
Exposure buildup factors are very important for the calculation of radiation shielding and also applied radiation. We must distinguish the monoenergetic and continuous energy spectrum gamma source in order to calculate the exposure buildup factors. In this study, the exposure buildup factors for two x-ray continuous energy spectra (bremsstrahlung) with 5 and 10 MeV endpoint energies were calculated up to depths of 10 mfp of water. It was observed that there is a large difference between the obtained exposure buildup factors due to the monoenergetic and continuous energy spectrum gamma sources...
January 18, 2018: Journal of Radiological Protection: Official Journal of the Society for Radiological Protection
Andrey Yu Sosorev, Dmitry Yu Godovsky, Dmitry Yu Paraschuk
The modeling of organic solar cells (OSCs) can provide a roadmap for their further improvement. Many OSC models have been proposed in recent years; however, the impact of the key intermediates from photons to electricity-hot charge-transfer (CT) states-on the OSC efficiency is highly ambiguous. In this study, we suggest an analytical kinetic model for OSC that considers a two-step charge generation via hot CT states. This hot kinetic model allowed us to evaluate the impact of different material parameters on the OSC performance: the driving force for charge separation, optical bandgap, charge mobility, geminate recombination rate, thermalization rate, average electron-hole separation distance in the CT state, dielectric permittivity, reorganization energy and charge delocalization...
January 18, 2018: Physical Chemistry Chemical Physics: PCCP
Xiuqi Kong, Baoli Dong, Xuezhen Song, Chao Wang, Nan Zhang, Weiying Lin
Controlled release systems with capabilities for direct and real-time monitoring of the release and dynamics of drugs in living systems are of great value for cancer chemotherapy. Herein, we describe a novel dual turn-on fluorescence signal-based controlled release system (CDox), in which the chemotherapy drug doxorubicin (Dox) and the fluorescent dye (CH) are conjugated by a hydrazone moiety, a pH-responsive cleavable linker. CDox itself shows nearly no fluorescence as the fluorescence of CH and Dox is essentially quenched by the C=N isomerization and N-N free rotation...
2018: Theranostics
Qiufang Liu, Yuyi Qian, Panli Li, Sihang Zhang, Jianjun Liu, Xiaoguang Sun, Michael Fulham, Dagan Feng, Gang Huang, Wei Lu, Shaoli Song
Purpose: Transcatheter hepatic artery embolization therapy is a minimally invasive alternative for treating inoperable liver cancer but recurrence is frequent. Multifunctional agents, however, offer an opportunity for tumor eradication. In this study, we were aim to synthesized poly (lactic-co-glycolic acid) (PLGA) microspheres encapsulating hollow CuS nanoparticles (HCuSNPs) and paclitaxel (PTX) that were then labeled with radioiodine-131 (131I) to produce 131I-HCuSNPs-MS-PTX. This compound combines the multi-theranostic properties of chemotherapy, radiotherapy and photothermal therapy...
2018: Theranostics
Shigeo Asahi, Kazuki Kusaki, Yukihiro Harada, Takashi Kita
Development of high-efficiency solar cells is one of the attractive challenges in renewable energy technologies. Photon up-conversion can reduce the transmission loss and is one of the promising concepts which improve conversion efficiency. Here we present an analysis of the conversion efficiency, which can be increased by up-conversion in a single-junction solar cell with a hetero-interface that boosts the output voltage. We confirm that an increase in the quasi-Fermi gap and substantial photocurrent generation result in a high conversion efficiency...
January 17, 2018: Scientific Reports
Drew Mitchell, Samuel Fahrenholtz, Christopher MacLellan, Dhiego Bastos, Ganesh Rao, Sujit Prabhu, Jeffrey Weinberg, John Hazle, Jason Stafford, David Fuentes
We evaluated a physics-based model for planning for magnetic resonance-guided laser interstitial thermal therapy for focal brain lesions. Linear superposition of analytical point source solutions to the steady-state Pennes bioheat transfer equation simulates laser-induced heating in brain tissue. The line integral of the photon attenuation from the laser source enables computation of the laser interaction with heterogeneous tissue. Magnetic resonance thermometry data sets (n = 31) were used to calibrate and retrospectively validate the model's thermal ablation prediction accuracy, which was quantified by the Dice similarity coefficient (DSC) between model-predicted and measured ablation regions (T > 57°C)...
January 17, 2018: International Journal of Hyperthermia
Christopher L Buckley, Taro Toyoizumi
During active behaviours like running, swimming, whisking or sniffing, motor actions shape sensory input and sensory percepts guide future motor commands. Ongoing cycles of sensory and motor processing constitute a closed-loop feedback system which is central to motor control and, it has been argued, for perceptual processes. This closed-loop feedback is mediated by brainwide neural circuits but how the presence of feedback signals impacts on the dynamics and function of neurons is not well understood. Here we present a simple theory suggesting that closed-loop feedback between the brain/body/environment can modulate neural gain and, consequently, change endogenous neural fluctuations and responses to sensory input...
January 17, 2018: PLoS Computational Biology
Andreas Norrman, Kasimir Blomstedt, Tero Setälä, Ari T Friberg
We derive two general complementarity relations for the distinguishability and visibility of genuine vector-light quantum fields in double-pinhole photon interference involving polarization modulation. The established framework reveals an intrinsic aspect of wave-particle duality of the photon, not previously reported, thus providing deeper insights into foundational quantum interference physics.
July 28, 2017: Physical Review Letters
Lana Descheemaeker, Vincent Ginis, Sophie Viaene, Philippe Tassin
The enhancement of optical forces has enabled a variety of technological applications that rely on the optical control of small objects and devices. Unfortunately, optical forces are still too small for the convenient actuation of integrated switches and waveguide couplers. Here we show how the optical gradient force can be enhanced by an order of magnitude by making use of gauge materials inside two evanescently coupled waveguides. To this end, the gauge materials inside the cores should emulate imaginary vector potentials for photons pointing perpendicularly to the waveguide plane...
September 29, 2017: Physical Review Letters
M Westig, B Kubala, O Parlavecchio, Y Mukharsky, C Altimiras, P Joyez, D Vion, P Roche, D Esteve, M Hofheinz, M Trif, P Simon, J Ankerhold, F Portier
We show that a properly dc-biased Josephson junction in series with two microwave resonators of different frequencies emits photon pairs in the resonators. By measuring auto- and intercorrelations of the power leaking out of the resonators, we demonstrate two-mode amplitude squeezing below the classical limit. This nonclassical microwave light emission is found to be in quantitative agreement with our theoretical predictions, up to an emission rate of 2 billion photon pairs per second.
September 29, 2017: Physical Review Letters
E Agudelo, J Sperling, L S Costanzo, M Bellini, A Zavatta, W Vogel
We derive and implement a general method to characterize the nonclassicality in compound discrete- and continuous-variable systems. For this purpose, we introduce the operational notion of conditional hybrid nonclassicality which relates to the ability to produce a nonclassical continuous-variable state by projecting onto a general superposition of discrete-variable subsystem. We discuss the importance of this form of quantumness in connection with interfaces for quantum communication. To verify the conditional hybrid nonclassicality, a matrix version of a nonclassicality quasiprobability is derived and its sampling approach is formulated...
September 22, 2017: Physical Review Letters
Hashem Zoubi, Klemens Hammerer
We show that strong nonlinearities at the few photon level can be achieved in optomechanical nanoscale waveguides. We consider the propagation of photons in cm-scale one-dimensional nanophotonic structures where stimulated Brillouin scattering (SBS) is strongly enhanced by radiation pressure coupling. We introduce a configuration that allows slowing down photons by several orders of magnitude via SBS from sound waves using two pump fields. Slowly propagating photons can then experience strong nonlinear interactions through virtual off-resonant exchange of dispersionless phonons...
September 22, 2017: Physical Review Letters
Mark M Wilde, Marco Tomamichel, Seth Lloyd, Mario Berta
Quantum hypothesis testing is one of the most basic tasks in quantum information theory and has fundamental links with quantum communication and estimation theory. In this paper, we establish a formula that characterizes the decay rate of the minimal type-II error probability in a quantum hypothesis test of two Gaussian states given a fixed constraint on the type-I error probability. This formula is a direct function of the mean vectors and covariance matrices of the quantum Gaussian states in question. We give an application to quantum illumination, which is the task of determining whether there is a low-reflectivity object embedded in a target region with a bright thermal-noise bath...
September 22, 2017: Physical Review Letters
Sebastian Maehrlein, Alexander Paarmann, Martin Wolf, Tobias Kampfrath
In stimulated Raman scattering, two incident optical waves induce a force oscillating at the difference of the two light frequencies. This process has enabled important applications such as the excitation and coherent control of phonons and magnons by femtosecond laser pulses. Here, we experimentally and theoretically demonstrate the so far neglected up-conversion counterpart of this process: THz sum-frequency excitation of a Raman-active phonon mode, which is tantamount to two-photon absorption by an optical transition between two adjacent vibrational levels...
September 22, 2017: Physical Review Letters
Alexandre Specht, Bastien Goegan, Firat Terzi, Frédéric Bolze, Sidney Cambridge
We report herein the synthesis and the photolytic properties of EANBP and PEG7-DEACM caged 9-aminodoxycycline. 9-Aminodoxycycline is a tetracycline analogue able to activate transcription via the inducible TetOn transgene expression system and can be regioselectively coupled by carbamoylation to two-photon sensitive photoremovable protecting groups. The EANBP caged 9-aminodoxycycline showed complex photochemical reactions but did release 10% of 9-aminodoxycycline. However, the PEG7-DEACM-9-aminodoxycycline exhibited excellent photolysis efficiency at 405 nm with a quantitative release of 9-aminodoxycycline and a 0...
January 17, 2018: Chembiochem: a European Journal of Chemical Biology
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