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Results 351 - 400 of 2550
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Eilenberger Falk - - 2012
We show experimentally that the recently proposed iterative shadowgraphic method can be applied to in-line digital holography, provided a suitable regularization step is introduced. We show that the method correctly solves the "twin-image" problem using just two samples of the intensity field scattered by a phase object. Field retrieval accuracy ...
Yi Xiaoke - - 2012
A new technique to realize an array of multiple true-time-delay elements, which can be independently and continuously tuned, is reported. It is based on a WDM parallel signal processing approach in conjunction with a diffraction-based Fourier-domain optical signal processor. Programmable linear optical phase transfer functions are realized to obtain different ...
Yao Junjie J Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, - - 2012
Recent developments of optical-resolution photoacoustic microscopy (OR-PAM) have improved its spatial resolution and imaging speed. However, the penetration depth of OR-PAM is still limited to ~1 mm in tissue, owing to the strong tissue scattering. Here, we have developed double-illumination PAM (DI-PAM), which illuminates the sample from both top and ...
Balsells José María Garrido - - 2012
In this paper, the performance of the variable weight multiple pulse-position modulation (MPPM) coding technique in an atmospheric optical communication environment under gamma-gamma optical scintillation is analyzed, proposing a closed-form expression for the average bit error rate (BER). This study is based on a hyperexponential fitting of the conditional BER ...
Shimizu-Hirota Ryoko - - 2012
Macrophages play critical roles in events ranging from host defense to obesity and cancer, where they infiltrate affected tissues and orchestrate immune responses in tandem with the remodeling of the extracellular matrix (ECM). Despite the dual roles played by macrophages in inflammation, the functions of macrophage-derived proteinases are typically relegated ...
Saleh Khaldoun - - 2012
Nonlinear phenomena occurring in an optical fiber ring resonator featuring ultrahigh Q factor are experimentally studied. The laser is locked onto the resonator, and the optical power induced in the resonator is controlled. The onset of the first stimulated Brillouin scattering wave occurs at an optical input power as low ...
Feiyue Mao - - 2012
The aerosol lidar ratio is a key parameter for the retrieval of aerosol optical properties from elastic lidar, which changes largely for aerosols with different chemical and physical properties. We proposed a method for retrieving the aerosol lidar ratio profile by combining simultaneous ground- and space-based elastic lidars. The method ...
Ding W - - 2012
We report frequency conversion experiments in silicon-on-insulator (SOI) directional couplers. We demonstrate that the evanescent coupling between two subwavelength SOI waveguides is strongly dispersive and significantly modifies modulational instability (MI) spectra through the coupling induced group velocity dispersion (GVD). As the separation between two 380-nm-wide silicon photonic wires decreases, the ...
Gerhard Christoph - - 2012
In this Letter, we report on the near-surface modification of fused silica by applying a hydrogenous atmospheric pressure plasma jet at ambient temperature. A significant decrease in UV-transmission due to this plasma treatment was observed. By the use of secondary ion mass spectroscopy, the composition of the plasma-modified glass surface ...
Trowbridge Jennifer J - - 2012
Epigenetic mechanisms regulating leukemia stem cells (LSCs) are an attractive target for therapy of blood cancers. Here, we report that conditional knockout of the DNA methyltransferase Dnmt1 blocked development of leukemia, and haploinsufficiency of Dnmt1 was sufficient to delay progression of leukemogenesis and impair LSC self-renewal without altering normal hematopoiesis. ...
Dumas Delphine - - 2012
Design of miniature and light cameras requires an optical design breakthrough to achieve good optical performance. Solutions inspired by animals' eyes are the most promising. The curvature of the retina offers several advantages, such as uniform intensity and no field curvature, but this feature is not used. The work presented ...
Sun Quan - - 2012
We report on experimental study of the shrinkage of photopolymerized micro/nanostructures fabricated by femtosecond direct laser writing in organic-inorganic resists. Blueshift of the stop-band positions of fabricated photonic crystals during the drying process, which follows the development and rinsing stages, indicates that the drying process plays an important role in ...
de Leon Jose - - 2012
Pharmacokinetic and pharmacodynamic drug interactions (DIs) can occur between antiepileptics (AEDs) and second-generation antipsychotics (SGAPs). Some AED and SGAP pharmacodynamic mechanisms are poorly understood. AED-SGAP combinations are used for treating comorbid illnesses or increasing efficacy, particularly in bipolar disorder. This article provides a comprehensive review of the interactions between antiepileptics ...
Weiss S Benjamin - - 2012
We demonstrate a method for single-detector coherent sensing and automated coalignment of group delays in a coherently combined laser array, enabling robust coherent combining of broadband sources despite initial path mismatches exceeding the laser coherence length. The method is based on Fourier-domain filtering of the coherently combined laser beam to ...
ZieliƄska Joanna A - - 2012
We present a theoretical and experimental study of the ultranarrow bandwidth Faraday anomalous dispersion optical filter operating at the rubidium D<sub>1</sub> line (795 nm). This atomic line gives better performance than other lines for key figures of merit, e.g., simultaneously 71% transmission, 445 MHz bandwidth, and 1.2 GHz equivalent-noise bandwidth.
Luo Zhang - - 2012
In this Letter, we suggest an on-chip integrated isolator based on an add-drop filter with unidirectional Raman-induced gain (or loss). For the steady state, complete one-way propagation for monochromatic signals is realized in the bus waveguide. For transient transmission, the burr is suppressed. And the power consumption is reduced by ...
Bahramipanah Mohsen - - 2012
In this numerical study, we present and demonstrate a compact, electrical plasmonic beam-steering device composed of anisotropic material. The splitting angle can be modulated by the external electric or magnetic field. The physical principle of this phenomenon is evaluated from the phase of surface plasmon polaritons and Fabry-Perot (F-P) resonance ...
Huang Min - - 2012
By micro-Raman spectroscopy, we show that the structured surfaces of highly oriented pyrolytic graphite and diamond induced by 800 nm, 125 fs or 532 nm, 30 ps laser pulses are capped by thin amorphous carbon layers. Based on the results, we propose that for multiphoton ablation the thin amorphous layer ...
Hohenau Andreas - - 2012
We launch surface plasmons from one end of a silver nanowire by asymmetric illumination with white light and use plasmon-to-light scattering at the nanowire ends to probe spectroscopically the plasmonic Fabry-Perot wire modes. The spectral positions of the maxima and minima in the scattered intensity from both nanowire ends are ...
Noordegraaf D - - 2012
We demonstrate efficient multimode (MM) to single-mode (SM) conversion in a 19-port photonic lantern with a 50 μm core MM delivery fiber. The photonic lantern can be used within the field of astrophotonics for coupling MM starlight to an ensemble of SM fibers in order to perform fiber-Bragg-grating-based spectral filtering. ...
Lu Tsan-Wen - - 2012
We theoretically propose and investigate a TM-polarized one-dimensional photonic crystal nanocavity with a horizontal SiO<sub>2</sub> slot on a suspended silicon nanobeam via the three-dimensional finite-element method. The ultrahigh quality factor and ultrasmall effective mode volume of 1.5×10<sup>7</sup> and 0.176 half-wavelength cubic of the horizontally SiO<sub>2</sub>-slotted nanocavity show strong possibilities for ...
Wei D - - 2012
Two-wave mixing in nematic liquid crystals doped with dyes and chiral agents is studied. The photo-induced spatial modulation of the chiral structure, together with the diffusion anisotropy of the mixture, determine a relatively fast response time, a spatial resolution of 1 μm, and a maximum gain for circularly polarized interacting beams. ...
Wang Yu Y Department of Pathology, University of Washington School of Medicine, Seattle, WA 98104, - - 2012
Phosphorylated α-synuclein (PS-129), a protein implicated in the pathogenesis of Parkinson's disease (PD), was identified by mass spectrometry in human cerebrospinal fluid (CSF). A highly sensitive and specific assay was established and used to measure PS-129 together with total α-synuclein in the CSF of patients with PD, other parkinsonian disorders ...
Uppu Ravitej - - 2012
We measure intensity statistics and identify statistical regimes and crossovers in random lasers based on nonresonant feedback. A single parameter extracted from an α-stable Levy fit is used to characterize the intensity distributions in all regimes. Measurements made over a range of scattering strengths, excitation energies, and sample sizes enable ...
Li Chunhui - - 2012
We report on a quantitative elastography technique achieved by combining phase-sensitive optical coherence tomography (PhS-OCT) with the surface acoustic wave (SAW) method. Different from traditional optical coherence elastography, the elastography is achieved by impulse-stimulated SAW, rather than by shear waves. PhS-OCT serves not only as a detector to measure SAW ...
Fan Weiwei W Center for Molecular and Mitochondrial Medicine and Genetics, University of California at Irvine, 92697, - - 2012
The role of mitochondrial DNA (mtDNA) mutations and mtDNA recombination in cancer cell proliferation and developmental biology remains controversial. While analyzing the mtDNAs of several mouse L cell lines, we discovered that every cell line harbored multiple mtDNA mutants. These included four missense mutations, two frameshift mutations, and one tRNA ...
Youngstrom Isaac A IA Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, - - 2012
Because many different sensory modalities contribute to spatial learning in rodents, it has been difficult to determine whether spatial navigation can be guided solely by visual cues. Rodents moving within physical environments with visual cues engage a variety of nonvisual sensory systems that cannot be easily inhibited without lesioning brain ...
Lamrini Samir - - 2012
We report on the high-energy laser operation of an Ho:YAG oscillator resonantly pumped by a GaSb-based laser diode stack at 1.9 μm. The output energy was extracted from a compact plano-concave acousto-optically Q-switched resonator optimized for low repetition rates. Operating at 100 Hz, pulse energies exceeding 30 mJ at a ...
Kim Shin Ae - - 2012
We propose an intrinsic optical method for in vivo neural recording using optic fiber-based surface plasmon resonance (SPR) phenomena. The fiber-based SPR method is electrical artifact free, labeling free, and feasible for a portable system compared with conventional in vivo neural recording systems. We simultaneously detected SPR signals and electrical ...
Wang Pengfei - - 2012
In this Letter, the fabrication and characterization of a microsphere resonator from the semiconductor germanium is demonstrated. Whispering gallery modes are excited in a 46 μm diameter germanium microsphere resonator using evanescent coupling from a tapered silica optical fiber with a waist diameter of 2 μm. Resonances with Q factors ...
Athyros Vasilios G - - 2012
A recent study suggested that patients with chronic kidney disease (CKD) with a glomerular filtration rate (GFR) < 45 ml/min/1.73 m(2) are more likely to present with acute myocardial infarction (AMI) than with stable exertion angina. Thus, the degree of renal impairment seems to be related to the presentation of ...
Choy Jennifer T - - 2012
We demonstrate waveguide-coupled titanium dioxide (TiO<sub>2</sub>) racetrack resonators with loaded quality factors of 2.2×10<sup>4</sup> for the visible wavelengths. The structures were fabricated in sputtered TiO<sub>2</sub> thin films on oxidized silicon substrates using standard top-down nanofabrication techniques, and passively probed in transmission measurements using a tunable red laser.
Chen Zhenhua - - 2012
We demonstrate the fractional second-harmonic (SH) Talbot effect in a hexagonally poled LiTaO<sub>3</sub> crystal. We carefully record the SH Talbot images at 1/2, 1/3, and 1/4 Talbot lengths, which are well matched with the simulated images by using the modified Rayleigh-Sommerfeld diffraction formula. A simplified model with a hexagonal array ...
Solntsev Alexander S - - 2012
We suggest an application of pump-degenerate four-wave mixing process in tapered waveguides for generation of ultrashort pulses with central frequency tunable over the material transparency range. Our method can produce strongly compressed frequency-converted pulses in presence of group-velocity mismatch and group-velocity dispersion. Additionally, the proposed technique does not require pulse ...
Strasser Samantha Dale - - 2012
Quantification of intracellular nanoscale macromolecular density distribution is a fundamental aspect to understanding cellular processes. We report a near-field penetrating optical microscopy (NPOM) technique to directly probe the internal nanoscale macromolecular density of biological cells through quantification of intracellular refractive index (RI). NPOM inserts a tapered optical fiber probe to ...
Fülöp J A - - 2012
Recent theoretical calculations predicted an order-of-magnitude increase in the efficiency of terahertz pulse generation by optical rectification in lithium niobate when 500 fs long pump pulses are used, rather than the commonly used ∼100  fs pulses. Even by using longer than optimal pump pulses of 1.3 ps duration, 2.5× higher THz ...
North Thibault - - 2012
We demonstrate the operation of a fiber ring laser using a 19.5 cm segment of As<sub>2</sub>S<sub>3</sub> chalcogenide fiber. The laser is passively mode-locked via nonlinear polarization rotation and provides two different operation regimes of picosecond and noiselike pulses. This ring configuration also enables an accurate measurement of the chromatic dispersion ...
Beck David B DB Howard Hughes Medical Institute, Department of Biochemistry, New York University School of Medicine, New York, 10016, - - 2012
Histone post-translational modifications impact many aspects of chromatin and nuclear function. Histone H4 Lys 20 methylation (H4K20me) has been implicated in regulating diverse processes ranging from the DNA damage response, mitotic condensation, and DNA replication to gene regulation. PR-Set7/Set8/KMT5a is the sole enzyme that catalyzes monomethylation of H4K20 (H4K20me1). It ...
Randoux Stéphane - - 2012
We present an experiment in which the intracavity broadened spectrum of a Raman fiber laser is sliced by using a narrow-bandwidth optical filter. High-contrast fast fluctuations of the Stokes power are observed at the output of the optical filter. The statistics of the power fluctuations strongly change with the central ...
Yue Yang - - 2012
We propose and experimentally demonstrate ultrawideband monocycle pulse generation using nondegenerate two-photon absorption in a silicon waveguide. The free-carrier absorption induced pulse tail at the rising edge of inverted probe pulse is largely compensated by the overlapped pump pulse and results in a symmetric negative monocycle pulse. A 143 ps Gaussian ...
Heins A M - - 2012
In the past, laser-induced breakdown spectroscopy (LIBS) signals have been reported to have a stability independent of the pulse length in solids. In this Letter, we perform the first stability study of femtosecond LIBS in gases (to our best knowledge) and show a significant improvement in signal stability over those ...
Gorthi Sai Siva - - 2012
This letter introduces a fluidics-based focus-stack collecting microscope. A microfluidic device transports cells through the focal plane of a microscope, resulting in an efficient method to collect focus stacks of large collections of single cells. Images from the focus stacks are used to reconstruct the quantitative phase of cells with ...
Neumann Frank R - - 2012
Chromatin in the interphase nucleus moves in a constrained random walk. Despite extensive study, the molecular causes of such movement and its impact on DNA-based reactions are unclear. Using high-precision live fluorescence microscopy in budding yeast, we quantified the movement of tagged chromosomal loci to which transcriptional activators or nucleosome ...
Eckerle Michael - - 2012
A diode-pumped actively Q-switched and actively mode-locked Tm<sup>3+</sup>-doped double-clad silicate fiber laser is reported providing up to 5 W of average output power at ~60 kHz Q-switch envelope repetition rate and ∼8  μJ subpulses with up to 2.4 kW peak power. Using this source as a pump laser for supercontinuum generation ...
Park Hyunkyu - - 2012
A highly disordered GaN nanostructure was grown by using hydride vapor phase epitaxy on an Si(100) substrate, and its diffuse reflectivity was measured in the 200-1200 nm spectral range by using an integrating sphere. A modified multiple-scattering-based model successfully explained the spectral distribution of diffuse reflectivity of this highly disordered ...
Deleidi Michela M Harvard Medical School, Boston, MA 02115, - - 2012
Here, we synthesize research behind the emerging hypothesis that inflammation--which can result, for example, from viral infections--can initiate and propagate chronic neuronal dysfunction, an event that precedes the clinical onset of many neurodegenerative diseases. Therapeutic approaches that target immunological pathways in the prodromal phase of diseases might decrease the incidence ...
Kim Jongki - - 2012
Highly efficient Bessel-like beam generation was achieved based on a new all-fiber method that implements Fourier transformation of a micro annular aperture along a concatenated composite optical fiber. The beam showed unique characteristics of tilted washboard optical potential in the transverse plane and sustained a nondiffracting length over 400 μm ...
Marchev Georgi - - 2012
A 21.4 mm long noncritically cut CdSiP<sub>2</sub> crystal, pumped by 8 ns pulses at 1064 nm in a double-pass configuration for pump, signal, and idler, generated 523 μJ, 5.8 ns idler pulses at 6.125 μm. The average power of 52.3 mW at the repetition rate of 100 Hz is the ...
Eichler H-G - - 2012
Traditional drug licensing approaches are based on binary decisions. At the moment of licensing, an experimental therapy is presumptively transformed into a fully vetted, safe, efficacious therapy. By contrast, adaptive licensing (AL) approaches are based on stepwise learning under conditions of acknowledged uncertainty, with iterative phases of data gathering and ...
Popov K I - - 2012
We investigate the role of a spatially inhomogenous nonresonant background medium on several Raman-based imaging modalities. In particular, we consider a small resonant bead submerged in a spatially heterogeneous nonresonant χ<sup>(3)</sup> background. Using detailed 3D electrodynamic simulations, we compare coherent anti-Stokes Raman scattering (CARS), frequency-modulated CARS, amplitude-modulated stimulated Raman scattering ...
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