wavelength (Total 86261 Papers Found)

  • Stan Schein, R. Desimone,
  • The Journal of neuroscience : the official journal of the Society for Neuroscience
  • 1990
Spectral properties of 129 cells in the V4 area of 5 macaque monkeys were studied quantitatively with narrow-band and broad-band colored lights. The large majority of cells exhibited some degree of wavelength sensitivity within their receptive fields. The half-bandwidth of the primary peak in the spectral-response curve was less than 50 nm for 72% of the cells; the mean half-bandwidth of these cells, 27 nm, is similar to that found for color-opponent ganglion cells and cells in the parvocellular ...
In the past few years, there has been growing interest in wide area \All Optical Networks" with wavelength division multiplexing (WDM), using wavelength routing. Due to the huge band-width inherent in optical ber, and the use of WDM to match user and network bandwidths, the wavelength routing architecture is an attractive candidate for future backbone transport networks. A virtual topology over a WDM WAN consists of clear channels between nodes called light-paths, with traac carried from source ...
Digital cameras have become popular and many people are choosing to take their pictures with digital cameras instead of film cameras. When a digital image is recorded, the camera needs to perform a significant amount of processing to provide the user a viewable image. This processing includes white balance adjustment, gamma correction, compression and more (reference “Color Image Processing Pipeline in Digital Still Cameras” in this issue). A very important part of this image processing chai ...
It is commonly assumed that quantum field theory arises by applying ordinary quantum mechanics to the low energy effective degrees of freedom of a more fundamental theory defined at ultra-high-energy/short-wavelength scales. We shall argue here that, even for free quantum fields, there are holistic aspects of quantum field theory that cannot be properly understood in this manner. Specifically, the “subtractions” needed to define nonlinear polynomial functions of a free quantum field in curve ...
The intrinsic fluorescence of aquatic organic matter emitted at 350 nm when excited at 280 nm correlates widely with water quality parameters such as biochemical oxygen demand. Hence, in sewage-impacted rivers and groundwater, it might be expected that fluorescence at these wavelengths will also correlate with the microbial water quality. In this paper we use a portable fluorimeter to assess the relationship between fluorescence intensity at this wavelength pair and Escherichia coli enumeration ...
Advantages of the acousto-optic tunable filter (AOTF), namely its ability for fast scanning and multiple-wavelength diffraction, were exploited to develop a novel, all solid-state, nonmoving parts spectrofluorometer. This instrument is based on the use of two AOTFs: one for excitation and the other for emission. The first AOTF was used to specifically diffract white incident light into a specific wavelength(s) for excitation. Depending on the needs, the second AOTF (i.e., the emission AOTF) can ...
We experimentally demonstrate an all-optical exclusive-OR (XOR) gate with optical feedback using a highly Ge-doped nonlinear fiber. The XOR is achieved based on cross-polarization rotation in nonlinear fiber, while the optical feedback employs a terahertz optical asymmetric demultiplexer (TOAD). The TOAD simultaneously cleans up the XOR output and converts the wavelength of the feedback signal to allow proper feedback operation. The performance of the all-optical XOR gate with optical feedback i ...
When reliability is a major concern in optical WDM networks, Shared Path Protection (SPP) schemes offer the potentially appealing feature of requiring fewer network resources than their counterpart Dedicated Path Protection (DPP) schemes. However, while sharing increases resource utilization, it reduces end-to-end reliability of connection demands. Moreover, the evaluation of connection demand reliability is easy with DPP: it depends only on the components used to route the connection demand. It ...
Online monitoring of the contamination condition of power transmission line is important to prevent insulation from flashover. The conventional online monitoring methods are easily disturbed by the strong electromagnetic interference around the high voltage line. In this letter, Bragg wavelength of polyimide coated fiber Bragg grating (FBG) is found to be slightly restrained by the salt deposited on the polyimide surface. Based on the effect, a special designed FBG sensor is proposed for detecti ...
We introduce the use of quantum dot (QD) nanoparticles for near-surface velocimetry and provide preliminary data to demonstrate its feasibility. Evanescent wave illumination is used to image the motion of water-soluble (CdSe)ZnS QDs with a core size of 6 nm within a region of order 100 nm of a surface . Results are presented for the two in-plane components of the velocity field. With the recent surge of interest in microfluidics and nanofluidics research, various fundamental and practical issues ...
Liquid crystal ‘blue phases’ are highly fluid self-assembled three-dimensional cubic defect structures that exist over narrow temperature ranges in highly chiral liquid crystals. The characteristic period of these defects is of the order of the wavelength of visible light, and they give rise to vivid specular reflections that are controllable with external fields. Blue phases may be considered as examples of tuneable photonic crystals with many potential applications. The disadvantage of the ...
The diffuse attenuation coefficient K<sub>d</sub>(λ) was first expressed in terms of the inherent optical properties (IOPs) of water according to well-established empirical bio-optical models. Boltzmann simulated annealing was then used to find the best sets of IOPs to fit K<sub>d</sub>(λ) spectra to the reference spectra Kd0(λ) that define the Jerlov water types. Absorption a(λ) and scattering b(λ) coefficients were thus obtained for all Jerlov water types over the ...
Understanding the complexity of the cellular environment will benefit from the ability to unambiguously resolve multiple cellular components, simultaneously and with nanometer-scale spatial resolution. Multicolor super-resolution fluorescence microscopy techniques have been developed to achieve this goal, yet challenges remain in terms of the number of targets that can be simultaneously imaged and the crosstalk between color channels. Herein, we demonstrate multicolor stochastic optical reconstr ...
The influence of light of varying wavelength on growth and ochratoxin A biosynthesis of Aspergillus carbonarius, A. niger, A. steynii and on Penicillium nordicum and P. verrucosum was analysed. For comparison the influence of light on various other food relevant fungi, including citrinin producers, was also tested. Generally the Aspergilli seem to be more resistant to light treatment than the Penicillia. Interestingly wavelengths from both sides of the spectrum, e. g. red (long wavelength, 627 n ...
The choice of an optimal wavelength for soft x-ray holography is discussed, based on a description of scattering by biological structures within an aqueous environment. We conclude that wavelengths slightly longer than the 43.7-A carbon K-edge provide a good trade off between minimizing the necessary source power and the dose absorbed by the sample and maximizing the penetrability of the x-rays through wet samples. This differs from the previous notion that wavelengths within the water window (b ...
Spectral sensitivity measurements from the retina of the Mexican salamander Ambystoma mexicanum (the 'axolotl') were used to provide evidence for and to characterize an amphibian ultraviolet-sensitive photoreception mechanism. Electroretinograms (transretinal voltage responses) were recorded from open eye cup preparations to analyze the spectral sensitivity of the retina. Both dark-adapted and white light-adapted preparations exhibited a peak in sensitivity between 360-370 nm. Under selective ch ...
  • T. D. Hall,
  • PLANS 2004. Position Location and Navigation Symposium (IEEE Cat. No.04CH37556)
  • 2004
We have previously demonstrated that carrier phase measurements of the ubiquitous AM broadcast signals can be used for instantaneous radiolocation. The positioning accuracy, however, depends on how well the signal propagation characteristics can be modeled. In this paper, the signal propagation issues relevant to radiolocation are reviewed and empirical data on phase perturbation are presented. An AM radiolocation system, though not nearly as susceptible as GPS to tropospheric, ionospheric, and ...
This paper discusses the requirements and motivations for setting-up and utilizing two different optical fiber test-beds both of a Telecom Operator as well as the UEssex/JANET Aurora field fiber testbed for optical metro networks research within the EU ICT MAINS project. Using both test-beds the MAINS project aims to evaluate its proposed mesh-ring topologies which feature innovative sub-wavelength switching nodes. Different research and technology attributes are considered for evaluation over t ...
A new structure single-channel wavelength-selective switch based on fiber grating and fiber loop mirror is presented and the simulation explains the characteristics of the experimental results. A new multichannel configurable wavelength-selective switch is proposed and analyzed; this kind of switch can be used as routing or demultiplexer in dense wavelength-division multiplexing networking. ...
A two-dimensional Heisenberg model with random antiferromagnetic nearest-neighbor exchange is studied using quantum Monte Carlo techniques. As the strength of the randomness is increased, the system undergoes a transition from an antiferromagnetically ordered ground state to a gapless disordered state. The finite-size scaling of the staggered structure factor and susceptibility is consistent with a dynamic exponent z = 2. PACS numbers: 75.10.Nr, 75.10.Jm, 75.40.Cx, 75.40.Mg Typeset using REVTEX ...
As quad-play (data, voice, video and mobile communications) and high-performance computing (HPC) traffic are proliferating and converging on to public (Internet), private, enterprise or service providers’ IP networking infrastructure, there is need for new generation of networking infrastructure and relevant management of the enhanced infrastructure. This new generation network will include converged architectures of IP and Optical networking (IP–Optical). Optical networks are not to be anym ...
Two-dimensional photosensitive supramolecular assemblies based on an azobenzene derivative and bi-pyridine are built up and investigated using scanning tunneling microscopy (STM). In order to probe the photo-induced self-assembled behavior of these two molecules, irradiation experiments with different wavelengths are designed and performed. Our STM results show that the constructed H-bonded networks can be reversibly regulated under irradiation with UV light and visible light. ...
Optical coherence tomography (OCT) is a new technology for noninvasive cross-sectional imaging of tissue structure in biological system by directing a focused beam of light at the tissue to be image [Bouma et al., 1995; Jiang et al., 2005; Ryu et al., 2005]. The technique measures the optical pulse time delay and intensity of backscattered light using interferometry with broadband light sources or with frequency swept lasers. It is analogous to ultrasound imaging or radar, except that it uses li ...
Computational and spectroscopic techniques have been combined to probe local protein structure. Experimental resonance Raman spectra were obtained for small fragments of the 29 amino acid glucose regulating protein glucagon. The Raman spectra for these fragments were also simulated computationally and were used to aid in the interpretation of the experimental spectra. Glucagon was then probed with experimental resonance Raman at a wavelength of 224 nm. Both the experimental and computational dat ...
  • Daojun Xue, Yang Qin, Chee Kheong Siew,
  • 2005 13th IEEE International Conference on Networks Jointly held with the 2005 IEEE 7th Malaysia International Conf on Communic
  • 2005
We consider the scheduling problem in a new optical transport network called time-domain wavelength interleaved networks (TWIN). Due to the innovative architecture of TWIN, four issues are essential in the designing of scheduling schemes: there are no transmitting/receiving conflicts; propagation delays are observed; throughput is maximized; queueing delay and delay variance are kept as small as possible. We formulate the scheduling problem into an integer linear programming (ILP) problem and pr ...
In this work, we report our recent progress on monolithic integration of magneto-optical oxide thin films and nonreciprocal photonic devices on silicon. We demonstrate strong Faraday rotation of - 6000 deg/cm at 1550 nm wavelength in silicon integrated Ce<sub>1.5</sub>Y<sub>1.5</sub>Fe<sub>5</sub>O<sub>12</sub> films, which exceeds the Faraday rotation of epitaxial CeiY<sub>2</sub>Fe<sub>5</sub>Oi<sub>2</sub> thi ...
Recently, there has been a great deal of interest in using the photoisomerization of azobenzene compounds to control specific biological targets in vivo. These azo compounds can be used as research tools or, in principle, could act as optically controlled drugs. Such "photopharmaceuticals" offer the prospect of targeted drug action and an unprecedented degree of temporal control. A key feature of azo compounds designed to photoswitch in vivo is the wavelength of light required to cause the photo ...
The article is devoted to tunable band-pass filters based on microstrip transmission lines and to phase-shift keying devices based on such types of filters. This paper gives a comprehensive description of the structure and the calculation methods for tunable band-pass filters based on the microstrip transmission lines. These filters are expected to have quite a compact dimensions and good physical implementation for the pass band of 2%–10% within decimeter wavelength range. ...
We present the dispersion characteristics of 18 liquids and one resin, which are widely used as media for liquid lenses in adaptive and tunable optics and for index matching in spectrochemical analysis. These are measured by using a refractometer operating at six different wavelengths. We provide a short description of the measurement setup and present a detailed uncertainty analysis of the measurement system to provide a measure of the reliability of the data. We conclude with a catalog of refr ...
Photonic crystal (PhC) components in InP-based materials are of practical importance not only for their unique properties but also for integration with conventional optoelectronic components on InP substrate. PhC waveguides have been investigated extensively for their unique waveguiding and dispersive properties. One such interesting property is the mode-gap which results in a transmission mini-stop band (MSB) [1] and has been investigated for applications such as coarse wavelength selection [2] ...
To the editor: I read the interesting study by Weaver et al1 and the accompanying editorial by Wilcox and Richards2 on noninvasive carbon monoxide (CO) detection in the February 2013 issue of RESPIRATORY CARE. I agree wholeheartedly with those authors that CO poisoning is an important public health concern, confounded by nonspecific symptoms that challenge diagnosticians. My experience with noninvasive measurement of carboxyhemoglobin by pulse oximetry (SpCO) with the RAD-57 (Masimo, Irvine, Cal ...
A general expression for the optical heterodyne signal power from a finite-sized radiation source is derived that is formally valid for an arbitrary degree of coherence of the source. The signal power is given explicitly in terms of those variables that describe the source of radiation (e.g., total radiated power, brightness distribution, and source size). Finite-sized incoherent and coherent sources are examined in detail, and analytic expressions are derived for various geometries of experimen ...
IN two papers published in the Proceedings of the Amsterdam Academy (vol. xvii., 445, 1914; vol. xviii., 398, 1915) an experimental investigation concerning Fresnel's convection-coefficient for light of various colours was described. The main object of my repetition of Fizeau's experiment, in the improved form introduced by Michelson, was to decide between the expressions for the convection-coefficient given by Fresnel and by Lorentz. As a review of the papers mentioned has appeared in NATURE (v ...
Orthogonal frequency division multiplexing (OFDM) is a prominent technique for providing high Quality of service (QOS) to the users by mitigating the fading of signals and also for providing high data rates in multimedia services. Single carrier FDMA (SC-FDMA) system has similar performance and the same overall complexity as that of OFDM. But Peak to average power ratio (PAPR) is a technical challenge which reduces the efficiency of RF power amplifiers. In this paper, we describe the Localized F ...
Hybridization of 20 mer probe oligonucleotides to complementary, surface-immobilized target oligonucleotides was visualized on a single-molecule basis by fluorescence microscopy. Coincident determination of the positions of both the target and the probe oligonucleotides using dual-wavelength fluorescence labeling allowed for highly reliable discrimination of specifically bound probe molecules from those being physisorbed. The figures of merit of the assay are characterized by the low probability ...
The effects of acoustic modes in the penstock on the self-excited oscillation in hydraulic power system were studied by assuming a finite sound velocity in the penstock. The flow in the draft tube is considered to be incompressible assuming that the length of the draft tube is smaller than the wavelength of the oscillation. It was found that various acoustic modes in the penstock can become unstable (amplified) by the diffuser effect of the draft tube or the effect of swirl flow from the runner. ...
BACKGROUND AND OBJECTIVE Though devices for hair growth based on low levels of light have shown encouraging results, further improvements of their efficacy is impeded by a lack of knowledge on the exact molecular targets that mediate physiological response in skin and hair follicle. The aim of this study was to investigate the expression of selected light-sensitive receptors in the human hair follicle and to study the impact of UV-free blue light on hair growth ex vivo. MATERIAL AND METHODS Th ...
NIR polymethine cyanine dyes exhibit long wavelengths that cannot be detected by the naked eye, whereas normal biological tissues fluoresce in the visible region of the electromagnetic spectrum. Using FLARE (Fluorescence-Assisted Resection and Exploration) imaging technology, both visible and NIR light can now be superimposed and visualized simultaneously. This technology has increased research in the field of biological contrast imaging agents. Polymethine cyanine dyes have shown specificity fo ...
  • B. Villeneuve, H. B. Kim, Margaret Cyr, Daniel Gariepy,
  • 1997 Digest of the IEEE/LEOS Summer Topical Meeting: Vertical-Cavity Lasers/Technologies for a Global Information Infrastructure/WDM Components Technology/Advanced Semiconductor Lasers and Application
  • 1997
With the 100/200 GHz channel spacing of current commercial DWDM systems, severe restrictions are imposed on transmitter wavelengths in order to meet crosstalk specifications and ensure reliable operation of the system in all conditions of its 25 years lifetime. While very stable in the short-term, free-running DFB laser transmitters are expected to exhibit long-term wavelength drifts exceeding these requirements, leading to a need for practical wavelength monitoring and control. In this paper we ...
We report a novel splicing-based pressure-assisted melt-filling technique for creating metallic nanowires in hollow channels in microstructured silica fibers. Wires with diameters as small as 120 nm (typical aspect ration 50:1) could be realized at a filling pressure of 300 bar. As an example we investigate a conventional single-mode step-index fiber with a parallel gold nanowire (wire diameter 510 nm) running next to the core. Optical transmission spectra show dips at wavelengths where guided s ...
Wide area networks, based on wavelength division multiplexed (WDM) optical networks, have limitations resulting from signal quality degradations, as the signals propagates along the fiber network. To overcome this problem, the notion of 3R regeneration has been investigated recently. At selected nodes in the WDM network, 3R regeneration facilities are included to reshape, reamplify and retime the signals. Scheduled traffic model (STM) has been proposed recently to take advantage of situations wh ...