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Intensed pulsed laser

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https://www.readbyqxmd.com/read/28340403/micro-and-macrovascular-function-in-children-with-sickle-cell-anaemia-and-sickle-cell-haemoglobin-c-disease
#1
Berenike Möckesch, Keyne Charlot, Stéphane Jumet, Marc Romana, Lydia Divialle-Doumdo, Marie-Dominique Hardy-Dessources, Marie Petras, Benoît Tressieres, Vanessa Tarer, Olivier Hue, Maryse Etienne-Julan, Philippe Connes, Sophie Antoine-Jonville
It is unclear whether vascular function is affected similarly in children with sickle cell anaemia (SS) and children with sickle haemoglobin C (SC) disease. Therefore, we compared micro and macrovascular functions in healthy (AA) children, children with SS and SC disease, and assessed their association with physical activity. Participants (24 SS, 22 SC and 16 AA), were compared in terms of 1) thermal hyperaemic response (finger pad warming to 42°C) measured by Laser Doppler techniques, 2) arterial stiffness determined by pulse wave velocity, 3) daily energy expenditure related to moderate and intense physical activities estimated by questionnaire and 4) fitness level, evaluated by the six-minute walk test...
February 4, 2017: Blood Cells, Molecules & Diseases
https://www.readbyqxmd.com/read/28339255/quantum-quenching-of-radiation-losses-in-short-laser-pulses
#2
C N Harvey, A Gonoskov, A Ilderton, M Marklund
Accelerated charges radiate, and therefore must lose energy. The impact of this energy loss on particle motion, called radiation reaction, becomes significant in intense-laser matter interactions, where it can reduce collision energies, hinder particle acceleration schemes, and is seemingly unavoidable. Here we show that this common belief breaks down in short laser pulses, and that energy losses and radiation reaction can be controlled and effectively switched off by appropriate tuning of the pulse length...
March 10, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28338214/light-therapies-for-acne-abridged-cochrane-systematic-review-including-grade-assessments
#3
REVIEW
J Barbaric, R Abbott, P Posadzki, M Car, L H Gunn, A M Layton, A Majeed, J Car
We undertook a Cochrane review of randomized controlled trials (RCTs) evaluating the effects of light-based interventions for acne vulgaris. We searched the Cochrane Skin Specialised Register, CENTRAL, MEDLINE, Embase, LILACS, ISI Web of Science, and grey literature sources (September 2015). We used the Grading of Recommendations Assessment, Development and Evaluation Working Group approach to assess the quality of evidence (QE). We included 71 RCTs (4211 participants, median sample size 31). Results from a single study (n = 266, low QE) showed little or no difference in effectiveness on participants' assessment of improvement between 20% aminolevulinic acid (ALA) photodynamic therapy (PDT), activated by blue light, versus vehicle plus blue light, whereas another study (n = 180) of a comparison of ALA-PDT (red light) concentrations showed 20% ALA-PDT was no more effective than 15%, but better than 10% and 5% ALA-PDT...
March 24, 2017: British Journal of Dermatology
https://www.readbyqxmd.com/read/28338010/brilliant-petawatt-gamma-ray-pulse-generation-in-quantum-electrodynamic-laser-plasma-interaction
#4
H X Chang, B Qiao, T W Huang, Z Xu, C T Zhou, Y Q Gu, X Q Yan, M Zepf, X T He
We show a new resonance acceleration scheme for generating ultradense relativistic electron bunches in helical motions and hence emitting brilliant vortical γ-ray pulses in the quantum electrodynamic (QED) regime of circularly-polarized (CP) laser-plasma interactions. Here the combined effects of the radiation reaction recoil force and the self-generated magnetic fields result in not only trapping of a great amount of electrons in laser-produced plasma channel, but also significant broadening of the resonance bandwidth between laser frequency and that of electron betatron oscillation in the channel, which eventually leads to formation of the ultradense electron bunch under resonant helical motion in CP laser fields...
March 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28317370/two-dimensional-ch3nh3pbi3-perovskite-nanosheets-for-ultrafast-pulsed-fiber-lasers
#5
Pengfei Li, Yao Chen, Tieshan Yang, Ziyu Wang, Han Lin, Yanhua Xu, Lei Li, Haoran Mu, Bannur Nanjunda Shivananju, Yupeng Zhang, Qinglin Zhang, Anlian Pan, Shaojuan Li, Dingyuan Tang, Baohua Jia, Han Zhang, Qiaoliang Bao
Even though the nonlinear optical effects of solution processed organic-inorganic perovskite films have been studied, the nonlinear optical properties in two-dimensional (2D) perovskites, especially their applications for ultrafast photonics, are largely unexplored. In comparison to bulk perovskite films, 2D perovskite nanosheets with small thicknesses of a few unit cells are more suitable for investigating the intrinsic nonlinear optical properties because bulk recombination of photocarriers and the nonlinear scattering are relatively small...
March 29, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28315815/self-assembled-photoadditives-in-polyester-films-allow-stop-and-go-chemical-release
#6
Ting Cheng, Richard O'Rorke, Raphael Francois Ortiz, Tay Yee Yan, Eva Hemmer, Fiorenzo Vetrone, Robert S Marks, Terry W J Steele
Near-infrared (NIR) triggered chemical delivery allows on-demand release with the advantage of external tissue stimulation. Bioresorbable polyester poly-l-lactic acid (PLLA) was compounded with photoadditives of neat zinc oxide (ZnO) nanoparticles and 980→365nm LiYF4:Tm(3+), Yb(3+) upconverting nanoparticles (UCNP). Subsequently, neat ZnO and UCNP blended PLLA films of sub-50μm thickness were knife casted with a hydrophobic small molecule drug mimic, fluorescein diacetate. The PLLA films displayed a 500 times increase in fluorescein diacetate release from the 50mW NIR irradiated PLLA/photoadditive film compared to non-irradiated PLLA control films...
March 16, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28297990/laser-pulse-compression-using-magnetized-plasmas
#7
Yuan Shi, Hong Qin, Nathaniel J Fisch
Proposals to reach the next generation of laser intensities through Raman or Brillouin backscattering have centered on optical frequencies. Higher frequencies are beyond the range of such methods mainly due to the wave damping that accompanies the higher-density plasmas necessary for compressing higher frequency lasers. However, we find that an external magnetic field transverse to the direction of laser propagation can reduce the required plasma density. Using parametric interactions in magnetized plasmas to mediate pulse compression, both reduces the wave damping and alleviates instabilities, thereby enabling higher frequency or lower intensity pumps to produce pulses at higher intensities and longer durations...
February 2017: Physical Review. E
https://www.readbyqxmd.com/read/28297954/seeded-qed-cascades-in-counterpropagating-laser-pulses
#8
T Grismayer, M Vranic, J L Martins, R A Fonseca, L O Silva
The growth rates of seeded QED cascades in counterpropagating lasers are calculated with first-principles two- and three-dimensional QED-PIC (particle-in-cell) simulations. The dependence of the growth rate on the laser polarization and intensity is compared with analytical models that support the findings of the simulations. The models provide insight regarding the qualitative trend of the cascade growth when the intensity of the laser field is varied. A discussion about the cascade's threshold is included, based on the analytical and numerical results...
February 2017: Physical Review. E
https://www.readbyqxmd.com/read/28288450/laser-treatment-of-tattoos-basic-principles
#9
Wolfgang Bäumler
Tattooing has become very popular worldwide during the past decades, and millions of people have one or many tattoos at different anatomical sites. The color of tattoos is mainly black, followed by red, green, blue, and other colors. A part of the tattooed people regret tattooing or have permanent problems with tattoos and therefore seek for tattoo removal. Tattoos consist of solid pigment particles in the skin. Thus, tattoo removal requires fragmentation of these permanently incorporated particles. The gold standard of tattoo removal is laser therapy...
2017: Current Problems in Dermatology
https://www.readbyqxmd.com/read/28282208/subcycle-extreme-nonlinearities-in-gap-induced-by-an-ultrastrong-terahertz-field
#10
Carlo Vicario, Mostafa Shalaby, Christoph P Hauri
We report on the experimental observation of extreme laser spectral broadening and a change in optical transmission in gallium phosphite induced by 25  MV/cm terahertz (THz) single-cycle internal field. Such intense THz radiation leads to twofold transient modifications of the optical properties in the electro-optical crystal. First, the electric field provokes extensive cross-phase modulation via the χ^{(2)} and χ^{(3)} nonlinearities on a copropagating 50 fs near infrared laser pulse which turns into 500% spectral broadening...
February 24, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28281679/three-electron-beams-from-a-laser-plasma-wakefield-accelerator-and-the-energy-apportioning-question
#11
X Yang, E Brunetti, D Reboredo Gil, G H Welsh, F Y Li, S Cipiccia, B Ersfeld, D W Grant, P A Grant, M R Islam, M P Tooley, G Vieux, S M Wiggins, Z M Sheng, D A Jaroszynski
Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lower-energy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5-10% of the initial laser energy...
March 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28279642/low-intensity-400%C3%A2-mw-cm-2-500%C3%A2-khz-pulsed-transcranial-ultrasound-preconditioning-may-mitigate-focal-cerebral-ischemia-in-rats
#12
Hangdao Li, Junfeng Sun, Daqu Zhang, Daryl Omire-Mayor, Peter A Lewin, Shanbao Tong
BACKGROUND: Preconditioning methods, which could increase tolerance of brain to subsequent ischemic injuries with a small dose of non-injury stimuli, have gained attention. Capitalizing on noninvasiveness and safety of ultrasound modality, the pulsed transcranial ultrasound stimulation (pTUS) approach may provide a novel treatment for patients with high risk of stroke. OBJECTIVE: This study's goal was to investigate whether the risk of stroke could be minimized or eliminated by prior exposure to low-intensity, pulsed transcranial ultrasound stimulation (pTUS)...
February 27, 2017: Brain Stimulation
https://www.readbyqxmd.com/read/28273922/the-role-of-super-atom-molecular-orbitals-in-doped-fullerenes-in-a-femtosecond-intense-laser-field
#13
Hui Xiong, Benoit Mignolet, Li Fang, Timur Osipov, Thomas J A Wolf, Emily Sistrunk, Markus Gühr, Francoise Remacle, Nora Berrah
The interaction of gas phase endohedral fullerene Ho3N@C80 with intense (0.1-5 × 10(14) W/cm(2)), short (30 fs), 800 nm laser pulses was investigated. The power law dependence of Ho3N@C80(q+), q = 1-2, was found to be different from that of C60. Time-dependent density functional theory computations revealed different light-induced ionization mechanisms. Unlike in C60, in doped fullerenes, the breaking of the cage spherical symmetry makes super atomic molecular orbital (SAMO) states optically active...
December 2017: Scientific Reports
https://www.readbyqxmd.com/read/28272897/magnetic-switching-in-granular-fept-layers-promoted-by-near-field-laser-enhancement
#14
Patrick W Granitzka, Emmanuelle Jal, Loïc Le Guyader, Matteo Savoini, Daniel J Higley, Tianmin Liu, Zhao Chen, Tyler Chase, Hendrik Ohldag, Georgi L Dakovski, William F Schlotter, Sebastian Carron, Matthias C Hoffman, Alexander X Gray, Padraic Shafer, Elke Arenholz, Olav Hellwig, Virat Mehta, Yukiko K Takahashi, Jian Wang, Eric E Fullerton, Joachim Stöhr, Alexander H Reid, Hermann A Dürr
Light-matter interaction at the nanoscale in magnetic materials is a topic of intense research in view of potential applications in next-generation high-density magnetic recording. Laser-assisted switching provides a pathway for overcoming the material constraints of high-anisotropy and high-packing density media, though much about the dynamics of the switching process remains unexplored. We use ultrafast small-angle X-ray scattering at an X-ray free-electron laser to probe the magnetic switching dynamics of FePt nanoparticles embedded in a carbon matrix following excitation by an optical femtosecond laser pulse...
March 17, 2017: Nano Letters
https://www.readbyqxmd.com/read/28272471/dynamics-of-laser-driven-proton-acceleration-exhibited-by-measured-laser-absorptivity-and-reflectivity
#15
J H Bin, K Allinger, K Khrennikov, S Karsch, P R Bolton, J Schreiber
Proton acceleration from nanometer thin foils with intense laser pulses is investigated experimentally. We analyzed the laser absorptivity by parallel monitoring of laser transmissivity and reflectivity with different laser intensities when moving the targets along the laser axis. A direct correlation between laser absorptivity and maximum proton energy is observed. Experimental results are interpreted in analytical estimation, exhibiting a coexistence of plasma expansion and light-sail form of radiation pressure acceleration (RPA-LS) mechanisms during the entire proton acceleration process based on the measured laser absorptivity and reflectivity...
March 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28272022/quantum-mechanical-interpretation-of-the-ultrafast-all-optical-spin-switching
#16
Mitsuko Murakami, Zach Babyak, Michael Giocolo, Guo-Ping Zhang
The all optical spin switching induced by an intense ($\sim$ TW/cm$^2$), near-infrared (775 nm), ultrashort ($\sim100$ fs) circularly-polarized laser pulse is studied based on the spin-orbit coupled Heisenberg model. We find that the spin magnetic moment undergoes an oscillation in time during the interaction with a driving laser pulse, which can be explained as a classical counterpart of the Rabi oscillation associated with a spin-orbit coupling. The optimal spin reversal is achieved by adjusting the pulse duration to one half the Rabi oscillation period...
March 8, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28271882/rate-tunable-stepwise-two-photon-gated-photoresponsive-systems-employing-a-synergetic-interaction-between-transient-biradical-units
#17
Katsuya Mutoh, Yoichi Kobayashi, Takuya Yamane, Takahiro Ikezawa, Jiro Abe
The cooperative interaction between photons and molecules, recently termed as the "photosynergetic" effect, is crucial to develop advanced photofunctional materials beyond a one-photon reaction of a single chromophore. The two-photon absorption is one of the attractive processes for the efficient utilization of photons. Especially, the nonlinear response of the two-photon absorption process is of interest not only to realize temporal and spatial control of reactions but also to develop the rewritable optical memory media and smart optical devices responding to the intensity of light...
March 17, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28271006/vcsel-based-swept-source-for-low-cost-optical-coherence-tomography
#18
Sucbei Moon, Eun Seo Choi
We present a novel wavelength-swept laser source for optical coherence tomography (OCT) which is based on the conventional laser diode technology of the vertical-cavity surface-emitting laser (VCSEL). In our self-heating sweep VCSEL (SS-VCSEL), a VCSEL device is simply driven by ramped pulses of currents in direct intensity modulation. The intrinsic property of VCSEL produces a frequency-swept output through the self-heating effect. By the injected current, the temperature of the active region is gradually increased in this effect...
February 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28267751/cost-effectiveness-of-adjunct-non-pharmacological-interventions-for-osteoarthritis-of-the-knee
#19
Beth Woods, Andrea Manca, Helen Weatherly, Pedro Saramago, Eleftherios Sideris, Christina Giannopoulou, Stephen Rice, Mark Corbett, Andrew Vickers, Matthew Bowes, Hugh MacPherson, Mark Sculpher
BACKGROUND: There is limited information on the costs and benefits of alternative adjunct non-pharmacological treatments for knee osteoarthritis and little guidance on which should be prioritised for commissioning within the NHS. This study estimates the costs and benefits of acupuncture, braces, heat treatment, insoles, interferential therapy, laser/light therapy, manual therapy, neuromuscular electrical stimulation, pulsed electrical stimulation, pulsed electromagnetic fields, static magnets and transcutaneous electrical nerve Stimulation (TENS), based on all relevant data, to facilitate a more complete assessment of value...
2017: PloS One
https://www.readbyqxmd.com/read/28266540/amplitude-concentration-in-a-phase-modulated-spectrum-due-to-femtosecond-filamentation
#20
J V Thompson, P A Zhokhov, M M Springer, A J Traverso, V V Yakovlev, A M Zheltikov, A V Sokolov, M O Scully
We present a method by which the spectral intensity of an ultrafast laser pulse can be accumulated at selected frequencies by a controllable amount. Using a 4-f pulse shaper we modulate the phase of the frequency components of a femtosecond laser. By inducing femtosecond filamentation with the modulated pulse, we can concentrate the spectral amplitude of the pulse at various frequencies. The phase mask applied by the pulse shaper determines the frequencies for which accumulation occurs, as well as the intensity of the spectral concentration...
March 7, 2017: Scientific Reports
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