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Hana D'Souza, Annette Karmiloff-Smith
Recent technological advances allow us to measure how the infant brain functions in ways that were not possible just a decade ago. Although methodological advances are exciting, we must also consider how theories guide research: what we look for and how we explain what we find. Indeed, the ways in which research findings are interpreted affects the design of policies, educational practices, and interventions. Thus, the theoretical approaches adopted by scientists have a real impact on the lives of children with neurodevelopmental disorders (NDDs) and their families, as well as on the wider community...
December 1, 2016: Wiley Interdisciplinary Reviews. Cognitive Science
Venkata N K B Adusumalli, Heramba V S R M Koppisetti, Sagar Ganguli, Shyam Sarkar, Venkataramanan Mahalingam
NaYF4 is a superior host matrix to study the luminescence properties of lanthanide (Ln(3+) ) ions. Ln(3+) ions in hexagonal-phase NaYF4 (β-phase) nanocrystals (NCs) exhibit strong luminescence via an upconversion process compared to cubic NaYF4 (α-phase) NCs. However, in Ce(3+) /Ln(3+) -doped NaYF4 NCs (Ln=Tm, Tb, Sm, Dy) the α-phase NaYF4 NCs shows strong luminescence compared to their counterpart β-phase NCs despite the latter being much larger in size. This is attributed to comparatively large overlap between Ce(3+) ions emission band with excited energy levels of those Ln(3+) ions in α-phase compared to β-phase NCs...
December 1, 2016: Chemistry: a European Journal
Joran Deschamps, Andreas Rowald, Jonas Ries
Single-molecule localization microscopy (SMLM) relies on the switching of fluorescent molecules between a fluorescent and a dark state to achieve super resolution. This process is inherently dependent on the intensity distribution of the laser light used for both activation from the dark state and excitation of the bright state. Typically, laser light is coupled directly or via a single-mode fiber into the microscope, which leads to a Gaussian intensity profile in total internal reflection (TIR) or epi illumination...
November 28, 2016: Optics Express
Zizhuo Liu, Koray Aydin
Graphene is a monolayer plasmonic material that has been widely studied in the area of plasmonics and nanophotonics. Combining graphene with traditional plasmonic structures provides new opportunities and challenges. One particular application for nanostructured metals is enhanced optical transmission. However, extraordinary transmission (EOT) is known to have a frequency-selective performance due to size and periodicity of the nanohole arrays. Here, we propose to use a continuous graphene layer to enhance transmission through gold nanoslit arrays at mid-infrared (mid-IR) wavelengths...
November 28, 2016: Optics Express
Weijie Mai, Xiaokang Song, Ping Jiang, Wenzhong Wang, Li Yu, Jiasen Zhang
Plasmon-based fluorescence modulation has led to important advances in various fields and has paved the way toward promising scientific research aimed at enabling new applications. However, the modulation of fluorescence properties based on both localized surface plasmon (LSP) and cavity modes of propagating surface plasmon polaritons (SPPs) are rarely reported. Here, we raster scanned a hybrid nanowire (HNW) with quantum dots (QDs) adsorbed onto a Ag nanowire (NW) and obtained two-photon fluorescence (TPF) maps of the intensity and decay rate...
November 28, 2016: Optics Express
Wu-Chao Zhai, Tie-Zhu Qiao, Dong-Jin Cai, Wen-Jie Wang, Jing-Dong Chen, Zhi-Hui Chen, Shao-Ding Liu
Third-harmonic generation with metallic or dielectric nanoparticles often suffer from, respectively, small modal volumes and weak near-field enhancements. This study propose and demonstrate that a metallic/dielectric hybrid nanostructure composed of a silver double rectangular nanoring and a silicon square nanoplate can be used to overcome these obstacles for enhanced third-harmonic generation. It is shown that the nonradiative anapole mode of the Si plate can be used as a localized source to excite the dark subradiant octupole mode of the Ag ring, and the mode hybridization leads to the formation of an antibonding and a bonding subradiant collective mode, thereby forming anticrossing double Fano resonances...
November 28, 2016: Optics Express
Michele Scaravilli, Giuseppe Castaldi, Andrea Cusano, Vincenzo Galdi
In this paper, we investigate the possibility to excite Bloch surface waves (BSWs) on the tip of single-mode optical fibers. Within this framework, after exploring an idealized, proof-of-principle grating-coupling-based scheme for on-tip excitation of BSWs, we focus on an alternative configuration that is more robust with respect to fabrication-related non-idealities. Subsequently, with a view towards label-free chemical and biological sensing, we present a specific design aimed at enhancing the sensitivity (in terms of wavelength shift) of the arising resonance with respect to changes in the refractive properties of the surrounding environment...
November 28, 2016: Optics Express
Ilya P Radko, Mads Boll, Niels M Israelsen, Nicole Raatz, Jan Meijer, Fedor Jelezko, Ulrik L Andersen, Alexander Huck
It is generally accepted that nitrogen-vacancy (NV) defects in bulk diamond are bright sources of luminescence. However, the exact value of their internal quantum efficiency (IQE) has not been measured so far. Here we use an implementation of Drexhage's scheme to quantify the IQE of shallow-implanted NV defects in a single-crystal bulk diamond. Using a spherical metallic mirror with a large radius of curvature compared to the optical spot size, we perform calibrated modifications of the local density of states around NV defects and observe the change of their total decay rate, which is further used for IQE quantification...
November 28, 2016: Optics Express
Di Liu, Le Yu, Xiao Xiong, Lei Yang, Yan Li, Ming Li, Hai-Ou Li, Gang Cao, Ming Xiao, Bin Xiang, Chang-Jun Min, Guang-Can Guo, Xi-Feng Ren, Guo-Ping Guo
Monolayer transition-metal dichalcogenides (TMDs) have grown as fantastic building blocks for optoelectronic applications, owing to their direct band gap, transparency, and mechanical flexibility. Since the luminescence of monolayer TMDs suffers from low light absorption and emission, surface plasmons, which confine light at subwavelength and enhance the local electric field, are utilized to boost both excitation and emission fields of TMDs, enabling strong light-matter interaction at the nano-scale. Meanwhile, radially-polarized beams (RPBs) as new and attractive excitation source have found many applications in surface plasmon polaritons, optical tweezer and so on...
November 28, 2016: Optics Express
Alexander Jesacher, Stefan Bernet, Monika Ritsch-Marte
Using the color selectivity of a spatial light modulator (SLM) for both, tailoring the excitation beam at one wavelength, and multiplexing the image at the red-shifted fluorescence wavelength, it is possible to parallelize confocal microscopy, i.e. to simultaneously detect an axial stack (z-stack) of a sample. For this purpose, two diffractive patterns, one steering the excitation light, and the other manipulating the emission light, are combined within the same area of the SLM, which acts as a pure phase modulator...
November 28, 2016: Optics Express
V E Lobanov, G V Lihachev, N G Pavlov, A V Cherenkov, T J Kippenberg, M L Gorodetsky
Dissipative Kerr solitons have paved the way to broadband and fully coherent optical frequency combs in microresonators. Here, we demonstrate numerically that slow frequency tuning of the pump laser in conjunction with phase or amplitude modulation corresponding to the free spectral range of the microresonator, provides reliable convergence of an initially excited chaotic comb state to a single dissipative Kerr soliton (DKS) state. The efficiency of this approach depends on both frequency tuning speed and modulation depth...
November 28, 2016: Optics Express
Mathias Perrin
We derive a quasi-normal mode theory for three-dimensional scatterers, taking care to remove an hypothesis of weakly dispersive materials implicitely used in previous works. In our approach, the normalized modes remain unchanged, but the analytic expansion coefficients onto the set of QNM are modified. In particular, we take into account in a simple way the non-orthogonality of the modes, and we set up a rigourous frame, to treat the case where several QNMs are excited. Eventally, the complex concept of PML integration, previously introduced, becomes unnecessary, even to compute the QNM mode volume...
November 28, 2016: Optics Express
Fabio Baronio, Shihua Chen, Miguel Onorato, Stefano Trillo, Stefan Wabnitz, Yuji Kodama
We introduce spatiotemporal optical dark X solitary waves of the (2+1)D hyperbolic nonlinear Schrödinger equation (NLSE), which rules wave propagation in a self-focusing and normally dispersive medium. These analytical solutions are derived by exploiting the connection between the NLSE and a well-known equation of hydrodynamics, namely the type II Kadomtsev-Petviashvili (KP-II) equation. As a result, families of shallow water X soliton solutions of the KP-II equation are mapped into optical dark X solitary wave solutions of the NLSE...
December 1, 2016: Optics Letters
Alberto Sottile, Eugenio Damiano, Mauro Tonelli
We report on, to the best of our knowledge, the first growth, spectroscopy, and laser operation of monocrystalline Ba(Y<sub>0.8</sub>Lu<sub>0.2</sub>)<sub>2</sub>F<sub>8</sub> doped with 1.25 at.% of Pr<sup>3+</sup> ions (Pr:BYLF). We studied the spectroscopic properties of this material, particularly in comparison with its isomorph Pr<sup>3+</sup>: BaY<sub>2</sub>F<sub>8</sub> (Pr:BYF). Under diode-pumped excitation, we achieved continuous-wave laser operation in the orange, red, and deep red regions in the three possible crystal orientations...
December 1, 2016: Optics Letters
Xiaolei Zhao, Lin Zhu, Cai Yuan, Jianquan Yao
A grating-coupled double-layer graphene hybrid system is proposed to investigate the plasmon-induced transparency effect at far-infrared frequencies. Based on the guided mode resonance principle, a diffractive grating is used to couple the normally incident waves and excite the plasmonic resonances on two graphene films separated by a spacer, thereby avoiding the need for patterning graphene. It is found that the origin of the observed transparency window transforms from Autler-Townes splitting to electromagnetically induced transparency with the increase of the separation distance between the two graphene films...
December 1, 2016: Optics Letters
I A Kolmychek, A N Shaimanov, A V Baryshev, T V Murzina
We present an experimental study of optical second harmonic generation (SHG) from arrays of nanostructures exhibiting collective plasmon resonances in the visible spectral range. Gold nanoparticles with the lateral diameter of 100 nm are packed in a square lattice with the period of 400 nm and are covered by a 90 nm thick iron garnet layer. We show an enhancement of SHG in the spectral vicinity of the lattice surface plasmon resonance. It is demonstrated that application of the external DC magnetic field results in a spectral shift of the SHG maximum up to 5 nm, accompanied by a pronounced phase modulation of the second harmonic wave...
December 1, 2016: Optics Letters
Pauline Roy, Fredérique Rau, Julien Ochala, Julien Messéant, Bodvael Fraysse, Jeanne Lainé, Onnik Agbulut, Gillian Butler-Browne, Denis Furling, Arnaud Ferry
BACKGROUND: The greater susceptibility to contraction-induced skeletal muscle injury (fragility) is an important dystrophic feature and tool for testing preclinic dystrophin-based therapies for Duchenne muscular dystrophy. However, how these therapies reduce the muscle fragility is not clear. METHODS: To address this question, we first determined the event(s) of the excitation-contraction cycle which is/are altered following lengthening (eccentric) contractions in the mdx muscle...
July 20, 2016: Skeletal Muscle
Manuel Arias-Calderón, Gonzalo Almarza, Alexis Díaz-Vegas, Ariel Contreras-Ferrat, Denisse Valladares, Mariana Casas, Héctor Toledo, Enrique Jaimovich, Sonja Buvinic
BACKGROUND: Electrical activity regulates the expression of skeletal muscle genes by a process known as "excitation-transcription" (E-T) coupling. We have demonstrated that release of adenosine 5'-triphosphate (ATP) during depolarization activates membrane P2X/P2Y receptors, being the fundamental mediators between electrical stimulation, slow intracellular calcium transients, and gene expression. We propose that this signaling pathway would require the proper coordination between the voltage sensor (dihydropyridine receptor, DHPR), pannexin 1 channels (Panx1, ATP release conduit), nucleotide receptors, and other signaling molecules...
April 11, 2016: Skeletal Muscle
Xiaofei Cong, Jonathan Doering, Davi A G Mazala, Eva R Chin, Robert W Grange, Honglin Jiang
BACKGROUND: The SH3 and cysteine-rich domain 3 (Stac3) gene is specifically expressed in the skeletal muscle. Stac3 knockout mice die perinatally. In this study, we determined the potential role of Stac3 in postnatal skeletal muscle growth, fiber composition, and contraction by generating conditional Stac3 knockout mice. METHODS: We disrupted the Stac3 gene in 4-week-old male mice using the Flp-FRT and tamoxifen-inducible Cre-loxP systems. RESULTS: RT-qPCR and western blotting analyses of the limb muscles of target mice indicated that nearly all Stac3 mRNA and more than 70 % of STAC3 protein were deleted 4 weeks after tamoxifen injection...
April 11, 2016: Skeletal Muscle
Thor A Wagner
More than 30 million people are infected with HIV, and HIV remains the fifth leading cause of disability-adjusted life years worldwide. Antiretroviral therapy (ART) dramatically decreases mortality rate, but there are side effects, long-term toxicities, expenses, stigmas, and inconveniences associated with chronic treatment, and HIV-infected individuals on ART have an increased risk of malignancies, cardiovascular disease, neurologic disease, and shortened life expectancy. Therefore, a cure for HIV remains an important goal...
December 2016: AIDS Patient Care and STDs
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