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Intense pulsed light

Tanya Moutray, Jennifer R Evans, Noemi Lois, David J Armstrong, Tunde Peto, Augusto Azuara-Blanco
BACKGROUND: Diabetic retinopathy (DR) is a chronic progressive disease of the retinal microvasculature associated with prolonged hyperglycaemia. Proliferative DR (PDR) is a sight-threatening complication of DR and is characterised by the development of abnormal new vessels in the retina, optic nerve head or anterior segment of the eye. Argon laser photocoagulation has been the gold standard for the treatment of PDR for many years, using regimens evaluated by the Early Treatment of Diabetic Retinopathy Study (ETDRS)...
March 15, 2018: Cochrane Database of Systematic Reviews
K R P Kafka, S Papernov, S G Demos
Laser conditioning was investigated as a function of the temporal shape and duration of 351 nm nanosecond pulses for fused-silica substrates polished via magnetorheological finishing. The aim is to advance our understanding of the dynamics involved to enable improved control of the interaction of laser light with the material to optimize laser conditioning. Gaussian pulses that are temporally truncated at the intensity peak are observed to enhance laser conditioning, in comparison to a Gaussian pulse shape...
March 15, 2018: Optics Letters
Oz Habiby, Omri Nahor, Alvaro Israel, Alexander Liberzon, Alexander Golberg
Marine macroalgae are a potential feedstock for biorefineries that can reduce dependence on fossil fuels and contribute to bioeconomy. New knowledge and technologies for efficient conversion of solar energy into macroalgae biomass are needed to increase biomass yields and energy conversion efficiency. In this work, we show that the green macroalgae from Ulva sp. can grow under the pulsed light in a photobioreactor with higher exergy conversion efficiency in comparison to cultivation under constant light with the same intensity...
March 14, 2018: Biotechnology and Bioengineering
Mohammad Reza Monazzam, Esmaeil Shoja, Seyed Abolfazl Zakerian, Abbas Rahimi Foroushani, Mohsen Shoja, Masoumeh Gharaee, Amin Asgari
PURPOSE: This study aimed to investigate the effect of whole-body vibration and ambient lighting, as well as their combined effect on human discomfort, heart rate, and reaction time in laboratory conditions. METHODS: 44 men were recruited with an average age of 25.4 ± 1.9 years. Each participant was subjected to 12 experimental steps, each step lasting five minutes for four different vibration accelerations in X, Y, and Z axes at a fixed frequency; three different lighting intensities of 50, 500, and 1000 lx were also considered...
March 12, 2018: International Archives of Occupational and Environmental Health
Yaser Khorrami, Vahid Ahmadi, Mohammad Razaghi, Narottam Das
In this paper, we numerically analyze nonlinear asymmetric switching using a semiconductor optical amplifier (SOA) phase-shifter-based Mach-Zehnder interferometer (MZI), for the first time, to the best of our knowledge. The self-phase modulation (SPM) effect and nonlinear phase shift in each MZI arm are investigated for different input pulse intensities and linear gains in both picosecond and femtosecond regimes. The input light signal is split unequally over the two arms, where SOAs are placed and act as nonlinear phase shifters in each arm...
March 1, 2018: Applied Optics
Daniel J Heath, James A Grant-Jacob, Robert W Eason, Ben Mills
Digital micromirror devices (DMDs) show great promise for use as intensity spatial light modulators. When used in conjunction with pulsed lasers of a timescale below the DMD pixel switching time, DMDs are generally only used as binary intensity masks (i.e., "on" or "off" intensity for each mask pixel). In this work, we show that by exploiting the numerical aperture of an optical system during the design of binary masks, near-continuous intensity control can be accessed, whilst still maintaining high-precision laser-machining resolution...
March 10, 2018: Applied Optics
Xue-Ling Mei, Li Wang
Intense pulsed light (IPL) is effective for the treatment of lentigines, telangiectasia, and generalized erythema, but is less effective in the removal of skin wrinkles. Fractional laser is effective on skin wrinkles and textural irregularities, but can induce postinflammatory hyperpigmentation (PIH), especially in Asians. This study evaluated the safety and efficacy of ablative fractional laser (AFL) in combination with IPL in the treatment of photoaging skin in Asians.This study included 28 Chinese women with Fitzpatrick skin type III and IV...
January 2018: Medicine (Baltimore)
Mei-Ling Chen, Zhi-Wen Gao, Xue-Min Chen, Shu-Chao Pang, Yi Zhang
Magnetic graphene-based hybrids are being increasing recognized as an effective nanotheranostic agent in biomedicine. Conventional technologies for their synthesis have drawbacks not only from a synthetic standpoint, mainly requiring high temperatures and multi-step processes, but also from a biological perspective, chemical precursors or surfactants involved in the chemical process are toxic to cells. Herein, we report a novel approach for one-step fabricating magnetic graphene hybrid nanocomposites based on laser irradiation of an Fe target in GO-PEG aqueous solution at room temperature without using any other chemical reagent...
May 15, 2018: Talanta
Catarina C V Oliveira, Filipe Figueiredo, Florbela Soares, Wilson Pinto, Maria Teresa Dinis
The present study reveals the first characterization of the plasma melatonin rhythms of the meagre (Argyrosomus regius) under aquaculture conditions. Melatonin levels were monitored during a 24 h cycle under a photoperiod of 16 L:8D and under constant darkness (DD), respectively to characterize the daily rhythm of this indoleamine and to test its endogenous origin. Besides, to identify which light intensities are perceived as night or day by this species, the degree of inhibition of nocturnal melatonin production caused by increasing intensities of light was tested (3...
March 2, 2018: Fish Physiology and Biochemistry
A R Jones, M D Aspinall, M J Joyce
A detector system for the characterization of radiation fields of both fast neutrons and γ rays is described comprising of a gated photomultiplier tube (PMT), an EJ299-33 solid organic scintillator detector, and an external trigger circuit. The objective of this development was to conceive a means by which the PMT in such a system can be actuated remotely during the high-intensity bursts of pulsed γ-ray contamination that can arise during active interrogation procedures. The system is used to detect neutrons and γ rays using established pulse-shape discrimination (PSD) techniques...
February 2018: Review of Scientific Instruments
Abdullah Alharbi, Andrey E Boguslavskiy, Dane Austin, Nicholas Thiré, D Wood, P Hawkins, Felicity McGrath, A S Johnson, I Lopez-Quintas, Bruno Schmidt, Francois Légaré, J P Marangos, Anh-Thu Le, Ravi Bhardwaj
Structural isomers, molecules having the same chemical formula but with atoms bonded in different order, are hard to identify using conventional spectroscopy and mass spectrometry. They exhibit virtually indistinguishable mass spectra when ionized by electrons. Laser mass spectrometry based on photoionization of the isomers has emerged as a promising alternative but requires shaped ultrafast laser pulses. Here we use transform limited femtosecond pulses to distinguish the isomers using two methods. First, we probe doubly charged parent ions with circularly polarized light...
February 28, 2018: Scientific Reports
Moniruzzaman Shaikh, Amit D Lad, Gabriele Birindelli, Kevin Pepitone, Jagannath Jha, Deep Sarkar, Sheroy Tata, Gourab Chatterjee, Indranuj Dey, Kamalesh Jana, Prashant K Singh, Vladimir T Tikhonchuk, P P Rajeev, G Ravindra Kumar
We report the lifetime of intense-laser (2×10^{19}  W/cm^{2}) generated relativistic electron pulses in solids by measuring the time evolution of their Cherenkov emission. Using a picosecond resolution optical Kerr gating technique, we demonstrate that the electrons remain relativistic as long as 50 picoseconds-more than 1000 times longer than the incident light pulse. Numerical simulations of the propagation of relativistic electrons and the emitted Cherenkov radiation with Monte Carlo geant4 package reproduce the striking experimental findings...
February 9, 2018: Physical Review Letters
Daniel D Hickstein, Grace C Kerber, David R Carlson, Lin Chang, Daron Westly, Kartik Srinivasan, Abijith Kowligy, John E Bowers, Scott A Diddams, Scott B Papp
Supercontinuum generation (SCG) in integrated photonic waveguides is a versatile source of broadband light, and the generated spectrum is largely determined by the phase-matching conditions. Here we show that quasi-phase-matching via periodic modulations of the waveguide structure provides a useful mechanism to control the evolution of ultrafast pulses during supercontinuum generation. We experimentally demonstrate a quasi-phase-matched supercontinuum to the TE_{20} and TE_{00} waveguide modes, which enhances the intensity of the SCG in specific spectral regions by as much as 20 dB...
February 2, 2018: Physical Review Letters
Ming Ren, Bo Song, Tianxin Zhuang, Shujing Yang
Light emitted from partial discharges (PDs) in SF6 gas is investigated in the view point of insulation status diagnostics. Light intensity and integral spectrum of PD are proved to have significant correlations with PD activities and the involved dielectric interfaces. Based on synchronous light pulse detections in ultraviolet (UV), visible (VIS) and near-infrared (NIR) regions, the multispectral stochastic PD diagnosis is realized with more information beyond the conventional PD detections. The optical PD detection is also compared with ultra-high frequency (UHF) PD detection and acoustic emission (AE) PD detection in term of linearity, sensitivity and statistical property...
February 20, 2018: ISA Transactions
Tobias Kampfrath, R Kramer Campen, Martin Wolf, Mohsen Sajadi
The dielectric response of liquids in the terahertz (THz) and sub-THz frequency range arise from low-energy collective molecular motions, which are often strongly influenced by intermolecular interactions. To shed light on the microscopic origin of the THz dielectric response of the simplest alcohol, methanol, we resonantly excite this liquid with an intense THz electric-field pulse and monitor the relaxation of the induced optical birefringence. We find a unipolar THz Kerr-effect signal which, in contrast to aprotic polar liquids, shows a weak coupling between the THz electric field and the permanent molecular dipole moment...
February 23, 2018: Journal of Physical Chemistry Letters
Huihui Gan, Baishuang Yue, Yan Wang, Zhong Lu
OBJECTIVE: To evaluate the efficacy and safety of narrow-band intense pulsed light (DPL) in treating facial telangiectasia. METHOD: Thirty patients with facial telangiectasia underwent five sessions of treatment with DPL (500 nm~600 nm) at 4-week interval. The erythema index (EI), temperature, transepidermal water loss (TEWL), and lightness of the skin (L) were measured before each treatment session and at each follow-up. RESULT: Thirty cases completed treatment and follow-ups...
February 20, 2018: Journal of Cosmetic and Laser Therapy: Official Publication of the European Society for Laser Dermatology
Renyun Zhang, Magnus Hummelgård, Viviane Forsberg, Henrik Andersson, Magnus Engholm, Thomas Öhlund, Martin Olsen, Jonas Örtegren, Håkan Olin
MoS2 has been studied intensively during recent years as a semiconducting material in several fields, including optoelectronics, for applications such as solar cells and phototransistors. The photoresponse mechanisms of MoS2 have been discussed but are not fully understood, especially the phenomenon in which the photocurrent slowly increases. Here, we report on a study of the photoresponse flash-light-processed MoS2 films of different thicknesses and areas. The photoresponse of such films under different light intensities and bias voltages was measured, showing significant current changes with a quick response followed by a slow one upon exposure to pulsed light...
February 19, 2018: Scientific Reports
Sebastian Burhenn, Jan Kratzer, Milan Svoboda, Felix David Klute, Antje Michels, Damir Veza, Joachim Franzke
A new method for arsenic detection by optical emission spectrometry (OES) is presented. Arsine (AsH3) is generated from liquid solutions by means of hydride generation (HG) and introduced into a capillary dielectric barrier discharge (DBD) where it is atomized and excited. A great challenge in OES is the reduction of the recorded background signal because it negatively affects the limit of detection (LOD). In conventional DBD-OES methods the signal intensity of the line of interest, in this case arsenic, is integrated over a long timescale...
February 19, 2018: Analytical Chemistry
Arwa M Hassan, Nashwa N Elfar, Omnia M Rizk, Nahed Y Eissa
BACKGROUND: Recent reports suggest that melasma may have a vascular component. Vascular targeting lasers and light treatment can be a therapeutic option that will provide benefits to the patients. OBJECTIVES: To compare the efficacy and tolerability of pulsed dye laser (PDL) and intense pulsed light in treatment of melasma. PATIENTS AND METHODS: Twenty-eight Egyptian female patients with melasma were treated with PDL on the right hemiface (Group A) and with the intense pulsed light on the left hemiface (Group B)...
February 23, 2018: Journal of Dermatological Treatment
Cecilia Nordqvist, Sebastien Fracheboud, Yan Guex-Crosier
No abstract text is available yet for this article.
February 16, 2018: Klinische Monatsblätter Für Augenheilkunde
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