Science.gov

Sample records for fast light particles

  1. Fast Light-Sheet Scanner

    NASA Technical Reports Server (NTRS)

    Hunter, William W., Jr.; Humphreys, William M., Jr.; Bartram, Scott M.

    1995-01-01

    Optomechanical apparatus maintains sheet of pulsed laser light perpendicular to reference axis while causing sheet of light to translate in oscillatory fashion along reference axis. Produces illumination for laser velocimeter in which submicrometer particles entrained in flow illuminated and imaged in parallel planes displaced from each other in rapid succession. Selected frequency of oscillation range upward from tens of hertz. Rotating window continuously shifts sheet of light laterally while maintaining sheet parallel to same plane.

  2. Silicon Timing Response to Particles and Light

    SciTech Connect

    Ronzhin, Anatoly; Spiropulu, Maria

    2015-01-01

    It is observed growing interest to fast timing detectors in high energy physics, related, for example, with collider luminosity increase (LHC) [1]. The options of CMS [2] calorimeter upgrade based on silicon detectors renewed interest to the timing study of this type of detectors. The article is devoted to study of silicon timing response to particles and light.

  3. Slow and Fast Light in Coupled Microresonators

    NASA Technical Reports Server (NTRS)

    Chang, Hongrok; Smith, David D.; Fuller, Kirk A.; Dimmock, John O.; Gregory, Don A.; Frazier, Donald O.

    2005-01-01

    We predict the propagation of slow and fast light in two co-resonant coupled optical resonators. In coupled resonators, slow light can propagate without attenuation by a cancellation of absorption as a result of mode splitting and destructive interference, whereas transparent fast light propagation can be achieved by the assistance of gain and splitting of the intracavity resonances, which consequently change the dispersion from normal to anomalous. The effective steady-state response of coupled-resonators is derived using the temporal coupled-mode formalism, and the absorptive and dispersive responses are described. Specifically, the occurrence of slow light via coupled-resonator-induced transparency and gain-assisted fast light are discussed.

  4. Slow and fast light switching in ruby

    NASA Astrophysics Data System (ADS)

    Rajan, Rajitha P.; Riesen, Hans

    2015-05-01

    Studies about light propagation have been undertaken for more than a century. It is now well established that any material that has normal or anomalous dispersion generates slow or fast light. In this paper, we demonstrate an experimental technique to rapidly switch between slow and fast light in ruby. The experiment utilizes transient holeburning to create drastic variation in refractive index of ruby to produce slow as well as fast light. Transient hole-burning involves the depletion of the ground state leading to a highly populated excited state by single frequency laser excitation. This leads to a hole in the absorption spectrum when readout by a laser. We observed a delay of 29 ns and advancement of -11 ns in an external magnetic field of B║c = 12 mT corresponding to a group velocity of c/961 and negative group velocity of -c/365 respectively.

  5. Slow and fast light in semiconductors

    NASA Astrophysics Data System (ADS)

    Sedgwick, Forrest Grant

    Slow and fast light are the propagation of optical signals at group velocities below and above the speed of light in a given medium. There has been great interest in the use of nonlinear optics to engineer slow and fast light dispersion for applications in optical communications and radio-frequency or microwave photonics. Early results in this field were primarily confined to dilute atomic systems. While these results were impressive, they had two major barriers to practical application. First, the wavelengths were not compatible with fiber optic telecommunications. More importantly, the bandwidth obtainable in these experiments was inherently low; 100 kHz or less. Within the last five years slow and fast light effects have been observed and engineered in a much wider variety of systems. In this work, we detail our efforts to realize slow and fast light in semiconductor systems. There are three primary advantages of semiconductor systems: fiber-compatible wavelengths, larger bandwidth, and simplification of integration with other optical components. In this work we will explore three different types of physical mechanisms for implementing slow and fast light. The first is electromagnetically induced transparency (EIT). In transporting this process to semiconductors, we initially turn our attention to quantum dots or "artificial atoms". We present simulations of a quantum dot EIT-based device within the context of an optical communications link and we derive results which are generally applicable to a broad class of slow light devices. We then present experimental results realizing EIT in quantum wells by using long-lived electron spin coherence. The second mechanism we will explore is coherent population oscillations (CPO), also known as carrier density pulsations (CDP). We examine for the first time how both slow and fast light may be achieved in a quantum well semiconductor optical amplifier (SOA) while operating in the gain regime. Again, we simulate the device

  6. Metallic nano-particles for trapping light.

    PubMed

    Tang, Yongan; Vlahovic, Branislav

    2013-02-07

    We study metallic nano-particles for light trapping by investigating the optical absorption efficiency of the hydrogenated amorphous silicon thin film with and without metallic nano-particles on its top. The size and shape of these nano-particles are investigated as to their roles of light trapping: scattering light to the absorption medium and converting light to surface plasmons. The optical absorption enhancement in the red light region (e.g., 650nm) due to the light trapping of the metallic nano-particles is observed when a layer of metallic nano-particle array has certain structures. The investigation of the light with incident angles shows the importance of the coupling efficiency of light to surface plasmons in the metallic nano-particle light trapping. PACS: 73.20.Mf, 42.25.s, 88.40.hj.

  7. Fast Particle Resonant Modes on MST*

    NASA Astrophysics Data System (ADS)

    Koliner, J. J.; Forest, C. B.; Sarff, J. S.; Anderson, J. K.; Lin, L.; Ding, W. X.; Brower, D. L.; Spong, D. A.

    2011-10-01

    The interaction between fast particles and Alfvén eigenmodes (AE's) is an important process critical to magnetically confined fusion plasmas. An effort is in progress to understand AE's through theory and experiment on MST, a reversed-field pinch. Coupling of energetic particle dynamics to one or more continuum modes can introduce undamped AE's. This coupling can drive modes unstable, a condition pertinent to NBI on MST and fusion alpha particles in future RFP devices. Computational studies for MST have predicted toroidal AE's with frequencies in the 200-300 kHz range and global structure. Alfvén-wave-frequency modes have been observed with up to 1 MW of NBI. Toroidal and poloidal arrays of magnetic loops are utilized to find edge amplitudes, frequencies and mode numbers. Frequencies are in the 60-150 kHz range with n=4 and n=5, m=1. The strongest coherent activity scales inversely with density, as expected for AE's, but does not scale with magnetic field strength. Additional experiments to investigate resonance conditions and beam energy scaling have been performed. An FIR interferometer-polarimeter has been used to find internal structure of the detected modes through correlation analysis. *Supported by USDoE and NSF.

  8. Any Light Particle Search (ALPS)

    NASA Astrophysics Data System (ADS)

    Spector, Aaron; Any Light Particle Search (ALPS) Collaboration

    2016-03-01

    High power laser fields enabled by technologies developed for ground-based gravitational-wave observatories open up new opportunities for fundamental physics studies. One of these options is the search for axions and axion-like particles in a pure laboratory experiment. The axion is a solution to the strong CP-problem and a potential dark matter candidate. The axion has also been proposed as an additional channel to cool stars as well as a potential explanation for the TeV transparency problem. The German-US ALPS collaboration is setting up a light-shining-through-walls (LSW) experiment at DESY. LSW experiments are based on the simple idea that a high power laser field traversing a static magnetic field will transform partly into a relativistic axion field. This axion field will travel through an opaque wall into a second static magnetic field region where it turns partly back into an electromagnetic wave field with the same frequency as the laser. The ALPS collaboration is working towards a large scale LSW experiment at DESY in Hamburg, Germany. I will report on the status of the ALPS experiment. This work is supported by the Deutsche Forschungsgemeinschaft, PRISMA, the Helmholtz Association, the National Science Foundation and the Heising-Simons Foundation.

  9. Fast optical switch having reduced light loss

    NASA Technical Reports Server (NTRS)

    Nelson, Bruce N. (Inventor); Cooper, Ronald F. (Inventor)

    1992-01-01

    An electrically controlled optical switch uses an electro-optic crystal of the type having at least one set of fast and slow optical axes. The crystal exhibits electric field induced birefringence such that a plane of polarization oriented along a first direction of a light beam passing through the crystal may be switched to a plane of polarization oriented along a second direction. A beam splitting polarizer means is disposed at one end of the crystal and directs a light beam passing through the crystal whose plane of polarization is oriented along the first direction differently from a light beam having a plane of polarization oriented along the second direction. The electro-optic crystal may be chosen from the crystal classes 43m, 42m, and 23. In a preferred embodiment, the electro-optic crystal is a bismuth germanium oxide crystal or a bismuth silicon oxide crystal. In another embodiment of the invention, polarization control optics are provided which transmit substantially all of the incident light to the electro-optic crystal, substantially reducing the insertion loss of the switch.

  10. Fast Scintillating Paddles for DarkLight

    NASA Astrophysics Data System (ADS)

    Palumbo, Daniel

    2017-01-01

    The DarkLight experiment proposes to search for a dark photon in the 10-100 MeV mass range via its production in fixed-target electron-proton collisions. The experimental design is driven by the desire to detect the complete final state including the recoiling proton, while also sustaining a very high luminosity in order to search for this rare process. Although the final design of the DarkLight experiment calls for fully streamed detector readout, initial studies will rely on traditional, triggered approaches. In order to facilitate precision measurements at high rate, a fast, thin, finely-segmented trigger detector based on plastic scintillating paddles and custom amplifiers was developed. I will discuss this design and its performance in recent DarkLight beam studies, as well as the work we have done to develop detectors using individual scintillating fibers. The DarkLight project is supported by DOE grant DE-FG02-94ER40818.

  11. Refractive index fiber sensor based on Brillouin fast light

    NASA Astrophysics Data System (ADS)

    Chen, Jiali; Gan, Jiulin; Zhang, Zhishen; Yang, Tong; Deng, Huaqiu; Yang, Zhongmin

    2014-01-01

    A new type of refractive index fiber sensor was invented by combining the evanescent-field scattering sensing mechanism with the Brillouin fast light scheme. Superluminal light was realized using Brillouin lasing oscillation in a fiber ring cavity. The refractive index of the solution around the microfiber within the cavity is related to the group velocity of the fast light. This fast light refractive index sensor offers an alternative for high-accuracy sensing applications.

  12. Fast Radio Bursts from Extragalactic Light Sails

    NASA Astrophysics Data System (ADS)

    Lingam, Manasvi; Loeb, Abraham

    2017-03-01

    We examine the possibility that fast radio bursts (FRBs) originate from the activity of extragalactic civilizations. Our analysis shows that beams used for powering large light sails could yield parameters that are consistent with FRBs. The characteristic diameter of the beam emitter is estimated through a combination of energetic and engineering constraints, and both approaches intriguingly yield a similar result that is on the scale of a large rocky planet. Moreover, the optimal frequency for powering the light sail is shown to be similar to the detected FRB frequencies. These “coincidences” lend some credence to the possibility that FRBs might be artificial in origin. Other relevant quantities, such as the characteristic mass of the light sail, and the angular velocity of the beam, are also derived. By using the FRB occurrence rate, we infer upper bounds on the rate of FRBs from extragalactic civilizations in a typical galaxy. The possibility of detecting fainter signals is briefly discussed, and the wait time for an exceptionally bright FRB event in the Milky Way is estimated.

  13. Polarization of fast particle beams by collisional pumping

    DOEpatents

    Stearns, J. Warren; Kaplan, Selig N.; Pyle, Robert V.; Anderson, L. Wilmer; Ruby, Lawrence; Schlachter, Alfred S.

    1988-01-01

    Method and apparatus for highly polarizing a fast beam of particles by collisional pumping, including generating a fast beam of particles, and also generating a thick electron-spin-polarized medium positioned as a target for the beam. The target is made sufficiently thick to allow the beam to interact with the medium to produce collisional pumping whereby the beam becomes highly polarized.

  14. Polarization of fast particle beams by collisional pumping

    DOEpatents

    Stearns, J.W.; Kaplan, S.N.; Pyle, R.V.; Anderson, L.W.; Schlachter, A.S.; Ruby, L.

    1984-10-19

    The invention relates to method and apparatus for polarizing a fast beam of particles by collisional pumping, including generating a fast beam of particles, and generating a thick electron-spin-polarized medium positioned as a target for said beam, said medium being sufficiently thick to allow said beam to interact with said medium to produce collisional pumping whereby said particle beam becomes highly polarized.

  15. Light as a Fundamental Particle

    ERIC Educational Resources Information Center

    Weinberg, Steven

    1975-01-01

    Presents two arguments concerning the role of the photon. One states that the photon is just another particle distinguished by a particular value of charge, spin, mass, lifetime, and interaction properties. The second states that the photon plays a fundamental role with a deep relation to ultimate formulas of physics. (GS)

  16. Are There Faster Than Light Particles?

    ERIC Educational Resources Information Center

    Kreisler, Michael N.

    1969-01-01

    Based upon recent relativistic theory, the researcher describes the search for tachyons, particles having velocities greater than that of a light. The properties of these particles are speculated upon. The author delineates the difficulties anticipated in their detection and the assumptions underlying their methodology. (RR)

  17. Light Obscuration Particle Counter Fuel Contamination Limits

    DTIC Science & Technology

    2015-10-08

    The 3 UNCLASSIFIED Energy Institute (EI) has published guidance documents and test methods relating to fuel quality measurement using... Energy (11) have conducted laboratory and field evaluations of particle counter technologies for fuel contamination monitoring. Testing has concluded...AND USE OF LIQUID FUELS Charleston, South Carolina USA 4-8 October 2015 LIGHT OBSCURATION PARTICLE COUNTER FUEL CONTAMINATION LIMITS Joel

  18. Fast Particle Methods for Multiscale Phenomena Simulations

    NASA Technical Reports Server (NTRS)

    Koumoutsakos, P.; Wray, A.; Shariff, K.; Pohorille, Andrew

    2000-01-01

    We are developing particle methods oriented at improving computational modeling capabilities of multiscale physical phenomena in : (i) high Reynolds number unsteady vortical flows, (ii) particle laden and interfacial flows, (iii)molecular dynamics studies of nanoscale droplets and studies of the structure, functions, and evolution of the earliest living cell. The unifying computational approach involves particle methods implemented in parallel computer architectures. The inherent adaptivity, robustness and efficiency of particle methods makes them a multidisciplinary computational tool capable of bridging the gap of micro-scale and continuum flow simulations. Using efficient tree data structures, multipole expansion algorithms, and improved particle-grid interpolation, particle methods allow for simulations using millions of computational elements, making possible the resolution of a wide range of length and time scales of these important physical phenomena.The current challenges in these simulations are in : [i] the proper formulation of particle methods in the molecular and continuous level for the discretization of the governing equations [ii] the resolution of the wide range of time and length scales governing the phenomena under investigation. [iii] the minimization of numerical artifacts that may interfere with the physics of the systems under consideration. [iv] the parallelization of processes such as tree traversal and grid-particle interpolations We are conducting simulations using vortex methods, molecular dynamics and smooth particle hydrodynamics, exploiting their unifying concepts such as : the solution of the N-body problem in parallel computers, highly accurate particle-particle and grid-particle interpolations, parallel FFT's and the formulation of processes such as diffusion in the context of particle methods. This approach enables us to transcend among seemingly unrelated areas of research.

  19. Phase measurement of fast light pulse in electromagnetically induced absorption.

    PubMed

    Lee, Yoon-Seok; Lee, Hee Jung; Moon, Han Seb

    2013-09-23

    We report the phase measurement of a fast light pulse in electromagnetically induced absorption (EIA) of the 5S₁/₂ (F = 2)-5P₃/₂ (F' = 3) transition of ⁸⁷Rb atoms. Using a beat-note interferometer method, a stable measurement without phase dithering of the phase of the probe pulse before and after it has passed through the EIA medium was achieved. Comparing the phases of the light pulse in air and that of the fast light pulse though the EIA medium, the phase of the fast light pulse at EIA resonance was not shifted and maintained to be the same as that of the free-space light pulse. The classical fidelity of the fast light pulse according to the advancement of the group velocity by adjusting the atomic density was estimated to be more than 97%.

  20. Nuclear diagnostic for fast alpha particles

    DOEpatents

    Grisham, L.R.; Post, D.E. Jr.; Dawson, J.M.

    1983-11-23

    This invention relates generally to high energy confined plasmas and more particularly is directed to measuring the velocity distribution of confined energetic alpha particles resulting from deuterium-tritium fusion reactions in a confined energetic plasma.

  1. Industrial Particle Size Measurement Using Light Scattering

    NASA Astrophysics Data System (ADS)

    Muly, E. C.; Frock, H. N.

    1980-12-01

    The precise knowledge of particle size and particle size distribution is fundamental to the control of a wide variety of industrial processes. Processing steps as diverse as crystallization, grinding, emulsification, and atomization, produce particles in the size range .1 to 1000 micrometers in diameter. While the object of some processes may be the production of particles of specified sizes, e.g., abrasives and glass beads, other processes may require particle size control for process efficiency, e.g., crystallization, and still others for control of final product quality, e.g., minerals, cement, and ceramics. In many processes more than one of these reasons may be important. A line of instruments has been developed using light scattering to measure various parameters of particulate distributions. These instruments employ laser illumination of a flowing stream of particles, producing Fraunhofer diffraction patterns which are processed both optically and electronically with unique, proprietary techniques. Various parameters of the particle size distribution are measured. The measurement is both rapid and precise. This paper will cover the importance of particle size measurements in various processes, different types of measurement methods, and the application of light scattering technology to size determinations in wet slurries and dry powders. A number of specific applications will be discussed encompassing minerals grinding, Portland cement, and rolling mill emulsions. Some references will be made to energy savings through automation.

  2. Mechanism of light-particle emission

    SciTech Connect

    Nagamiya, S.

    1982-02-01

    A general overview of the field of high-energy nuclear collisions studied from light particle spectra, pions, kaons, lambdas, protons, deuterons, and light composite fragments is given. Specifically, the basic reaction mechanism that determines the main features of particle emission such as the energy and angular distributions, the multiplicity, the production rate, the projectile and target mass dependences, the beam-energy dependences, etc. are discussed. Very general features of high-energy nuclear collisions are described. The major question is what characterizes these collisions. Proton emission is discussed since the proton is the dominant particle emitted at a large angle. The mechanism of composite-fragment formation is discussed. Also pion production and strange particle production are considered.

  3. Nuclear diagnostic for fast alpha particles

    DOEpatents

    Grisham, Larry R.; Post Jr., Douglass E.; Dawson, John M.

    1986-06-03

    Measurement of the velocity distribution of confined energetic alpha particles resulting from deuterium-tritium fusion reactions in a magnetically contained plasma is provided. The fusion plasma is seeded with energetic boron neutrals for producing, by means of the reaction .sup.10 B (.alpha.,n) .sup.13 N reaction, radioactive nitrogen nuclei which are then collected by a probe. The radioactivity of the probe is then measured by conventional techniques in determining the energy distribution of the alpha particles in the plasma. In a preferred embodiment, diborane gas (B.sub.2 H.sub.6) is the source of the boron neutrals to produce .sup.13 N which decays almost exclusively by positron emission with a convenient half-life of 10 minutes.

  4. Nuclear diagnostic for fast alpha particles

    DOEpatents

    Grisham, Larry R.; Post, Jr., Douglass E.; Dawson, John M.

    1986-01-01

    Measurement of the velocity distribution of confined energetic alpha particles resulting from deuterium-tritium fusion reactions in a magnetically contained plasma is provided. The fusion plasma is seeded with energetic boron neutrals for producing, by means of the reaction .sup.10 B (.alpha.,n) .sup.13 N reaction, radioactive nitrogen nuclei which are then collected by a probe. The radioactivity of the probe is then measured by conventional techniques in determining the energy distribution of the alpha particles in the plasma. In a preferred embodiment, diborane gas (B.sub.2 H.sub.6) is the source of the boron neutrals to produce .sup.13 N which decays almost exclusively by positron emission with a convenient half-life of 10 minutes.

  5. Particles That Travel Faster than Light?

    ERIC Educational Resources Information Center

    Newton, Roger G.

    1970-01-01

    A discussion of the possible existence of tachyons, particles that travel faster than light, and their theoretical properties. Suggests that if tachyons were found, the consequences for relativity theory, quantum mechanics and the concept of casuality would be far-reaching. Concludes that the final answer rests with the experimentalist.…

  6. Chirp-enhanced fast light in semiconductor optical amplifiers.

    PubMed

    Sedgwick, F G; Pesala, Bala; Uskov, Alexander V; Chang-Hasnain, C J

    2007-12-24

    We present a novel scheme to increase the THz-bandwidth fast light effect in semiconductor optical amplifiers and increase the number of advanced pulses. By introducing a linear chirp to the input pulses before the SOA and recompressing at the output with an opposite chirp, the advance-bandwidth product reached 3.5 at room temperature, 1.55 microm wavelength. This is the largest number reported, to the best of our knowledge, for a semiconductor slow/fast light device.

  7. Storage and retrieval of light pulses in a fast-light medium via active Raman gain

    NASA Astrophysics Data System (ADS)

    Xu, Datang; Bai, Zhengyang; Huang, Guoxiang

    2016-12-01

    We propose a scheme to realize the storage and retrieval of light pulses in a fast-light medium via a mechanism of active Raman gain (ARG). The system under consideration is a four-level atomic gas interacting with three (pump, signal, and control) laser fields. We show that a stable propagation of signal light pulses with superluminal velocity (i.e., fast-light pulses) is possible in such a system through the ARG contributed by the pump field and the quantum interference effect induced by the control field. We further show that a robust storage and retrieval of light pulses in such a fast-light medium can be implemented by switching on and off the pump and the control fields simultaneously. The results reported here may have potential applications for light information processing and transmission using fast-light media.

  8. Simple, fast, bright, and stable light sources.

    PubMed

    Tordera, Daniel; Meier, Sebastian; Lenes, Martijn; Costa, Rubén D; Ortí, Enrique; Sarfert, Wiebke; Bolink, Henk J

    2012-02-14

    In this work we show that solution-processed light-emitting electrochemical cells (LECs) based on only an ionic iridium complex and a small amount of ionic liquid exhibit exceptionally good performances when applying a pulsed current: sub-second turn-on times and almost constant high luminances (>600 cd m(-2) ) and power efficiencies over the first 600 h. This demonstrates the potential of LECs for applications in solid-state signage and lighting.

  9. Fast photon detection for particle identification with COMPASS RICH-1

    NASA Astrophysics Data System (ADS)

    Abbon, P.; Alekseev, M.; Angerer, H.; Apollonio, M.; Birsa, R.; Bordalo, P.; Bradamante, F.; Bressan, A.; Busso, L.; Chiosso, M.; Ciliberti, P.; Colantoni, M. L.; Costa, S.; Dalla Torre, S.; Dafni, T.; Delagnes, E.; Deschamps, H.; Diaz, V.; Dibiase, N.; Duic, V.; Eyrich, W.; Faso, D.; Ferrero, A.; Finger, M.; Finger, M., Jr.; Fischer, H.; Gerassimov, S.; Giorgi, M.; Gobbo, B.; Hagemann, R.; von Harrach, D.; Heinsius, F. H.; Horikawa, S.; Joosten, R.; Ketzer, B.; Königsmann, K.; Kolosov, V. N.; Konorov, I.; Kramer, D.; Kunne, F.; Lehmann, A.; Levorato, S.; Maggiora, A.; Magnon, A.; Mann, A.; Martin, A.; Menon, G.; Mutter, A.; Nähle, O.; Nerling, F.; Neyret, D.; Pagano, P.; Panebianco, S.; Panzieri, D.; Paul, S.; Pesaro, G.; Polak, J.; Rebourgeard, P.; Robinet, F.; Rocco, E.; Schiavon, P.; Schill, C.; Schröder, W.; Silva, L.; Slunecka, M.; Sozzi, F.; Steiger, L.; Sulc, M.; Svec, M.; Tessarotto, F.; Teufel, A.; Wollny, H.

    2007-10-01

    Particle identification (PID) at high rates is an important challenge for many current and future high-energy physics experiments. The upgrade of the COMPASS RICH-1 detector requires a new technique for Cherenkov photon detection at count rates of several 106 per channel in the central detector region, and a read-out system allowing for trigger rates of up to 100 kHz. To cope with these requirements, the photon detectors in the central region have been replaced with the detection system described in this paper. In the peripheral regions, the existing multi-wire proportional chambers with CsI photocathode are now read out via a new system employing APV pre-amplifiers and flash ADC chips. The new detection system consists of multi-anode photomultiplier tubes (MAPMT) and fast read-out electronics based on the MAD4 discriminator and the F1-TDC chip. The RICH-1 is in operation in its upgraded version for the 2006 CERN SPS run. We present the photon detection design, constructive aspects and the first Cherenkov light in the detector.

  10. Fast Solar Polarimeter: First Light Results

    NASA Astrophysics Data System (ADS)

    Krishnappa, N.; Feller, A.; Iglesia, F. A.; Solanki, S.

    2013-12-01

    Accurate measurements of magnetic fields on the Sun are crucial to understand various physical processes that take place in the solar atmosphere such as solar eruptions, coronal heating, solar wind acceleration, etc. The Fast Solar Polarimeter (FSP) is a new instrument that is being developed to probe magnetic fields on the Sun. One of the main goals of this polarimeter is to carry out high precision spectropolarimetric observations with spatial resolution close to the telescope diffraction limit. The polarimeter is based on pnCCD technology with split frame transfer and simultaneous multi-channel readout, resulting in frame rate upto 1 kHz. The FSP prototype instrument uses a small format pnCCD of 264x264 pixels which has been developed by PNSensor and by the semiconductor lab of the Max Planck Society. The polarization modulator is based on two ferro-electric liquid crystals (FLCs) interlaced between two static retarders. The first solar observations have been carried out with this prototype during May-June, 2013 at German Vacuum Tower Telescope (VTT) on Tenerife, Canary Islands, Spain. Here we present the instrument performance assessments and the first results on the magnetic field measurements. Further, we briefly discuss about the next phase of FSP which will be a dual beam system with 1k x 1k CCDs.

  11. Lagrangian statistics of light particles in turbulence

    NASA Astrophysics Data System (ADS)

    Mercado, Julián Martínez; Prakash, Vivek N.; Tagawa, Yoshiyuki; Sun, Chao; Lohse, Detlef; (International CollaborationTurbulence Research)

    2012-05-01

    We study the Lagrangian velocity and acceleration statistics of light particles (micro-bubbles in water) in homogeneous isotropic turbulence. Micro-bubbles with a diameter db = 340 μm and Stokes number from 0.02 to 0.09 are dispersed in a turbulent water tunnel operated at Taylor-Reynolds numbers (Reλ) ranging from 160 to 265. We reconstruct the bubble trajectories by employing three-dimensional particle tracking velocimetry. It is found that the probability density functions (PDFs) of the micro-bubble acceleration show a highly non-Gaussian behavior with flatness values in the range 23 to 30. The acceleration flatness values show an increasing trend with Reλ, consistent with previous experiments [G. Voth, A. La Porta, A. M. Crawford, J. Alexander, and E. Bodenschatz, "Measurement of particle accelerations in fully developed turbulence," J. Fluid Mech. 469, 121 (2002)], 10.1017/S0022112002001842 and numerics [T. Ishihara, Y. Kaneda, M. Yokokawa, K. Itakura, and A. Uno, "Small-scale statistics in highresolution direct numerical simulation of turbulence: Reynolds number dependence of one-point velocity gradient statistics," J. Fluid Mech. 592, 335 (2007)], 10.1017/S0022112007008531. These acceleration PDFs show a higher intermittency compared to tracers [S. Ayyalasomayajula, Z. Warhaft, and L. R. Collins, "Modeling inertial particle acceleration statistics in isotropic turbulence," Phys. Fluids. 20, 095104 (2008)], 10.1063/1.2976174 and heavy particles [S. Ayyalasomayajula, A. Gylfason, L. R. Collins, E. Bodenschatz, and Z. Warhaft, "Lagrangian measurements of inertial particle accelerations in grid generated wind tunnel turbulence," Phys. Rev. Lett. 97, 144507 (2006)], 10.1103/PhysRevLett.97.144507 in wind tunnel experiments. In addition, the micro-bubble acceleration autocorrelation function decorrelates slower with increasing Reλ. We also compare our results with experiments in von Kármán flows and point-particle direct numerical simulations with periodic

  12. Teaching conservation laws, symmetries and elementary particles with fast feedback

    NASA Astrophysics Data System (ADS)

    van den Berg, Ed; Hoekzema, Dick

    2006-01-01

    Lessons about elementary particles at the secondary school level can degenerate into listing a zoo of particles and reactions, resulting in disorganized and rather meaningless knowledge. A more powerful way is to focus on conservation laws, symmetries and reaction diagrams. The conservation laws and symmetries provide generalizing power that enables the students to predict whether or not certain reactions are possible and to derive new reactions from given ones by applying the symmetries. In this article we first present simplified Feynman diagrams and three symmetry operations. Then we discuss the fast feedback teaching method and present two lessons and a worksheet for teaching symmetries and reactions using this fast feedback. The method was developed and piloted during the last two school years in Dutch secondary schools.

  13. Outdoor ultrafine particle concentrations in front of fast food restaurants.

    PubMed

    Vert, Cristina; Meliefste, Kees; Hoek, Gerard

    2016-01-01

    Ultrafine particles (UFPs) have been associated with negative effects on human health. Emissions from motor vehicles are the principal source of UFPs in urban air. A study in Vancouver suggested that UFP concentrations were related to density of fast food restaurants near the monitoring sites. A previous monitoring campaign could not separate the contribution of restaurants from road traffic. The main goal of this study has been the quantification of fast food restaurants' contribution to outdoor UFP concentrations. A portable particle number counter (DiscMini) has been used to carry out mobile monitoring in a largely pedestrianized area in the city center of Utrecht. A fixed route passing 17 fast food restaurants was followed on 8 days. UFP concentrations in front of the restaurants were 1.61 times higher than in a nearby square without any local sources used as control area and 1.22 times higher compared with all measurements conducted in between the restaurants. Adjustment for other sources such as passing mopeds, smokers or candles did not explain the increase. In conclusion, fast food restaurants result in significant increases in outdoor UFP concentrations in front of the restaurant.

  14. Note on the field of a fast, charged particle

    SciTech Connect

    Lippmann, B.A.

    1984-08-01

    As the velocity of a charged particle increases, its electric flux lines become more and more concentrated about the transverse plane. This picture is sometimes construed to mean that the electric field is zero in front of a very fast particle. For many purposes, this is a valid approximation, but we must remember that it is still an approximation. No matter what the velocity of the particle, the field ahead of it never is zero. This becomes apparent if the field component along the direction of motion is integrated over the transverse plane. Here, Gauss' Theorem constrains the longitudinal field component to be finite, and the approximation that sets it equal to zero breaks down.

  15. Double-resonant fast particle-wave interaction

    NASA Astrophysics Data System (ADS)

    Schneller, M.; Lauber, Ph.; Brüdgam, M.; Pinches, S. D.; Günter, S.

    2012-10-01

    In future fusion devices fast particles must be well confined in order to transfer their energy to the background plasma. Magnetohydrodynamic instabilities like toroidal Alfvén eigenmodes or core-localized modes such as beta-induced Alfvén eigenmodes and reversed shear Alfvén eigenmodes, both driven by fast particles, can lead to significant losses. This is observed in many ASDEX Upgrade discharges. This study applies the drift-kinetic HAGIS code with the aim of understanding the underlying resonance mechanisms, especially in the presence of multiple modes with different frequencies. Of particular interest is the resonant interaction of particles simultaneously with two different modes, referred to as ‘double-resonance’. Various mode overlapping scenarios with different q profiles are considered. It is found that, depending on the radial mode distance, double-resonance is able to enhance growth rates as well as mode amplitudes significantly. Surprisingly, no radial mode overlap is necessary for this effect. Quite the contrary is found: small radial mode distances can lead to strong nonlinear mode stabilization of a linearly dominant mode.

  16. Fast imaging of live organisms with sculpted light sheets

    NASA Astrophysics Data System (ADS)

    Chmielewski, Aleksander K.; Kyrsting, Anders; Mahou, Pierre; Wayland, Matthew T.; Muresan, Leila; Evers, Jan Felix; Kaminski, Clemens F.

    2015-04-01

    Light-sheet microscopy is an increasingly popular technique in the life sciences due to its fast 3D imaging capability of fluorescent samples with low photo toxicity compared to confocal methods. In this work we present a new, fast, flexible and simple to implement method to optimize the illumination light-sheet to the requirement at hand. A telescope composed of two electrically tuneable lenses enables us to define thickness and position of the light-sheet independently but accurately within milliseconds, and therefore optimize image quality of the features of interest interactively. We demonstrated the practical benefit of this technique by 1) assembling large field of views from tiled single exposure each with individually optimized illumination settings; 2) sculpting the light-sheet to trace complex sample shapes within single exposures. This technique proved compatible with confocal line scanning detection, further improving image contrast and resolution. Finally, we determined the effect of light-sheet optimization in the context of scattering tissue, devising procedures for balancing image quality, field of view and acquisition speed.

  17. Fast imaging of live organisms with sculpted light sheets

    PubMed Central

    Chmielewski, Aleksander K.; Kyrsting, Anders; Mahou, Pierre; Wayland, Matthew T.; Muresan, Leila; Evers, Jan Felix; Kaminski, Clemens F.

    2015-01-01

    Light-sheet microscopy is an increasingly popular technique in the life sciences due to its fast 3D imaging capability of fluorescent samples with low photo toxicity compared to confocal methods. In this work we present a new, fast, flexible and simple to implement method to optimize the illumination light-sheet to the requirement at hand. A telescope composed of two electrically tuneable lenses enables us to define thickness and position of the light-sheet independently but accurately within milliseconds, and therefore optimize image quality of the features of interest interactively. We demonstrated the practical benefit of this technique by 1) assembling large field of views from tiled single exposure each with individually optimized illumination settings; 2) sculpting the light-sheet to trace complex sample shapes within single exposures. This technique proved compatible with confocal line scanning detection, further improving image contrast and resolution. Finally, we determined the effect of light-sheet optimization in the context of scattering tissue, devising procedures for balancing image quality, field of view and acquisition speed. PMID:25893952

  18. Fast Bayesian inference of optical trap stiffness and particle diffusion

    PubMed Central

    Bera, Sudipta; Paul, Shuvojit; Singh, Rajesh; Ghosh, Dipanjan; Kundu, Avijit; Banerjee, Ayan; Adhikari, R.

    2017-01-01

    Bayesian inference provides a principled way of estimating the parameters of a stochastic process that is observed discretely in time. The overdamped Brownian motion of a particle confined in an optical trap is generally modelled by the Ornstein-Uhlenbeck process and can be observed directly in experiment. Here we present Bayesian methods for inferring the parameters of this process, the trap stiffness and the particle diffusion coefficient, that use exact likelihoods and sufficient statistics to arrive at simple expressions for the maximum a posteriori estimates. This obviates the need for Monte Carlo sampling and yields methods that are both fast and accurate. We apply these to experimental data and demonstrate their advantage over commonly used non-Bayesian fitting methods. PMID:28139705

  19. Fast Bayesian inference of optical trap stiffness and particle diffusion

    NASA Astrophysics Data System (ADS)

    Bera, Sudipta; Paul, Shuvojit; Singh, Rajesh; Ghosh, Dipanjan; Kundu, Avijit; Banerjee, Ayan; Adhikari, R.

    2017-01-01

    Bayesian inference provides a principled way of estimating the parameters of a stochastic process that is observed discretely in time. The overdamped Brownian motion of a particle confined in an optical trap is generally modelled by the Ornstein-Uhlenbeck process and can be observed directly in experiment. Here we present Bayesian methods for inferring the parameters of this process, the trap stiffness and the particle diffusion coefficient, that use exact likelihoods and sufficient statistics to arrive at simple expressions for the maximum a posteriori estimates. This obviates the need for Monte Carlo sampling and yields methods that are both fast and accurate. We apply these to experimental data and demonstrate their advantage over commonly used non-Bayesian fitting methods.

  20. Light scattering from nonspherical airborne particles: Experimental and theoretical comparisons

    NASA Astrophysics Data System (ADS)

    Hirst, Edwin; Kaye, Paul H.; Guppy, John R.

    1994-10-01

    Spatial intensity distribution of laser light scattered by airborne hazardous particles such as asbestos fiber is studied to classify particles shape and size. Theoretical treatment is based on Rayleigh-Gans formalism. Theoretical and experimental data are in good agreement.

  1. Performance of single mechanoluminescent particle as ubiquitous light source.

    PubMed

    Terasaki, Nao; Xu, Chao-Nan

    2014-08-01

    In this study, we have investigated mechanoluminescent (ML) performance of single ML particle as ubiquitous light source. When using high-speed CCD camera with image intensifier and microscopic equipment, mechanoluminescence from single particle was observed. As to the quantitative ML evaluation of the single ML particle was carried out using photomultiplier, and successfully estimated the performance of the single ML particle as an intensity controllable light source in nW order.

  2. White dwarfs constraints on dark sector models with light particles

    SciTech Connect

    Ubaldi, Lorenzo

    2014-06-24

    The white dwarf luminosity function is well understood in terms of standard model physics and leaves little room for exotic cooling mechanisms related to the possible existence of new weakly interacting light particles. This puts significant constraints on the parameter space of models that contain a massive dark photon and light dark sector particles.

  3. Slow and fast light propagation in nonlinear Kerr media.

    NASA Astrophysics Data System (ADS)

    Yang, Qiguang; Ma, Seongmin; Wang, Huitian; Jung, S. S.

    2005-04-01

    Sub- and superluminal propagation of light pulse in Kerr materials has been investigated. Group velocities as slow as much less than 1 millimeter per second to as fast as negative several hundreds meters per second can be easily obtained in Kerr medium, which possesses large nonlinear refractive index and long relaxation time, such as Cr doped Alexandrite, Ruby, and GdAlO3. The physical mechanism is the strong highly dispersive coupling between different frequency components of the pulse. The new mechanism of slowing down pulses as well as producing superluminal pulses enlarges the very specific materials to all kinds of nonlinear optical materials.

  4. Fast frame scanning camera system for light-sheet microscopy.

    PubMed

    Wu, Di; Zhou, Xing; Yao, Baoli; Li, Runze; Yang, Yanlong; Peng, Tong; Lei, Ming; Dan, Dan; Ye, Tong

    2015-10-10

    In the interest of improving the temporal resolution for light-sheet microscopy, we designed a fast frame scanning camera system that incorporated a galvanometer scanning mirror into the imaging path of a home-built light-sheet microscope. This system transformed a temporal image sequence to a spatial one so that multiple images could be acquired during one exposure period. The improvement factor of the frame rate was dependent on the number of sub-images that could be tiled on the sensor without overlapping each other and was therefore a trade-off with the image size. As a demonstration, we achieved 960 frames/s (fps) on a CCD camera that was originally capable of recording images at only 30 fps (full frame). This allowed us to observe millisecond or sub-millisecond events with ordinary CCD cameras.

  5. An application of fast response Polarized Light Microscopy

    NASA Astrophysics Data System (ADS)

    Kantha, Deependra; van Winkle, David

    2007-03-01

    A fast response polarized light microscope was designed based on the algorithm by Shribak et. al (Applied Optics, vol. 42, 3009-3017). A pulsed laser beam was passed through two Pockels cells aligned at different angles with respect to optical axis. The retardance of the Pockels cell was controlled by external switches and power supplies. The electronics circuit in the system allows change of the retardance of the Pockels cell each millisecond for four milliseconds. In four milliseconds, four images of a birefringent sample, formed by different states of polarized light are recorded. The images are added appropriately to calculate retardence amplitude and phase by using codes written in imageJ software. The microscope was used to show the retardance and phase of a rabbit muscle fiber. Recordings were also taken of the contraction of Vorticella convallaria but the changes were too fast to yield retardance images. This type of microscope can be used to study different kinds of biological functions that change on a timescale slower than four milliseconds but faster than two seconds.

  6. Effects of dust particle internal structure on light scattering

    NASA Astrophysics Data System (ADS)

    Kemppinen, O.; Nousiainen, T.; Jeong, G. Y.

    2015-10-01

    There is a large variety of internal structures inside atmospheric dust particles, making them inherently inhomogeneous. Such structures may have a large effect on ground-level and atmospheric radiation. So far, dust particle internal structures and their effect on the light scattering properties have proved to be hard to quantify, in part due to challenges in obtaining information about these structures. Recently, internal structures of individual dust particles were revealed through focused ion beam milling and analyzed. Here, we perform a sensitivity study to evaluate the optical impacts of some of the typical internal structures revealed. To obtain suitable model particles, the first step is to generate inhomogeneous particles with varying internal structures by using an algorithm that is based on three-dimensional Voronoi tessellation. The parameters for the particle generation are obtained from studies of real-world Asian dust particles. The second step is to generate homogeneous versions of the generated particles by using an effective-medium approximation, for comparison. Third, light scattering by both versions of these particles is simulated with discrete dipole approximation code. This allows us to see how different internal structures affect light scattering, and how important it is to account for these structures explicitly. Further, this allows us to estimate the potential inaccuracies caused by using only homogeneous model particles for atmospheric studies and remote-sensing measurements. The results show that the effects vary greatly between different kinds of internal structures and single-scattering quantity considered, but for most structure types the effects are overall notable. Most significantly, hematite inclusions in particles impact light scattering heavily. Furthermore, internal pores and hematite-rich coating both affect some form of light scattering noticeably. Based on this work, it seems that it is exceedingly important that the

  7. Effects of dust particle internal structure on light scattering

    NASA Astrophysics Data System (ADS)

    Kemppinen, O.; Nousiainen, T.; Jeong, G. Y.

    2015-07-01

    There is a large variety of internal structures inside atmospheric dust particles, making them inherently inhomogeneous. Such structures may have a large effect on ground-level and atmospheric radiation. So far, dust particle internal structures and their effect on the light scattering properties have proved to be hard to quantify, in part due to challenges in obtaining information about these structures. Recently, internal structures of individual dust particles were revealed through focused ion beam milling and analyzed. Here, we perform a sensitivity study to evaluate the optical impacts of some of the typical internal structures revealed. To obtain suitable model particles, the first step is to generate inhomogeneous particles with varying internal structures by using an algorithm that is based on three-dimensional Voronoi tessellation. The parameters for the particle generation are obtained from studies of real-world Asian dust particles. The second step is to generate homogeneous versions of the generated particles by using an effective-medium approximation, for comparison. Third, light scattering by both versions of these particles is simulated with discrete-dipole approximation code. This allows us to see how different internal structures affect light scattering, and how important it is to account for these structures explicitly. Further, this allows us to estimate the potential inaccuracies caused by using only homogeneous model particles for atmospheric studies and remote sensing measurements. The results show that the effects vary greatly between different kinds of internal structures and single-scattering quantity considered, but for most structure types the effects are overall notable. Most significantly, hematite inclusions in particles impact light scattering heavily. Furthermore, internal pores and hematite-rich coating both affect some form of light scattering noticeably. Based on this work, it seems that it is exceedingly important that the

  8. Open LED Illuminator: A Simple and Inexpensive LED Illuminator for Fast Multicolor Particle Tracking in Neurons

    PubMed Central

    Bosse, Jens B.; Tanneti, Nikhila S.; Hogue, Ian B.; Enquist, Lynn W.

    2015-01-01

    Dual-color live cell fluorescence microscopy of fast intracellular trafficking processes, such as axonal transport, requires rapid switching of illumination channels. Typical broad-spectrum sources necessitate the use of mechanical filter switching, which introduces delays between acquisition of different fluorescence channels, impeding the interpretation and quantification of highly dynamic processes. Light Emitting Diodes (LEDs), however, allow modulation of excitation light in microseconds. Here we provide a step-by-step protocol to enable any scientist to build a research-grade LED illuminator for live cell microscopy, even without prior experience with electronics or optics. We quantify and compare components, discuss our design considerations, and demonstrate the performance of our LED illuminator by imaging axonal transport of herpes virus particles with high temporal resolution. PMID:26600461

  9. Diffraction of entangled particles by light gratings

    SciTech Connect

    Sancho, Pedro

    2015-04-15

    We analyze the diffraction regime of the Kapitza–Dirac effect for particles entangled in momentum. The detection patterns show two-particle interferences. In the single-mode case we identify a discontinuity in the set of joint detection probabilities, associated with the disconnected character of the space of non-separable states. For Gaussian multi-mode states we derive the diffraction patterns, providing an example of the dependence of the light–matter interaction on entanglement. When the particles are identical, we can explore the relation between exchange and entanglement effects. We find a complementary behavior between overlapping and Schmidt’s number. In particular, symmetric entanglement can cancel the exchange effects. - Highlights: • Kapitza–Dirac diffraction of entangled particles shows multiparticle interference. • There is a discontinuity in the set of joint detection patterns of entangled states. • We find a complementary behavior between overlapping and Schmidt’s number. • Symmetric entanglement can cancel the exchange effects.

  10. Spectrophotometry of Thin Films of Light-Absorbing Particles.

    PubMed

    Binks, Bernard P; Fletcher, Paul D I; Johnson, Andrew J; Marinopoulos, Ioannis; Crowther, Jonathan M; Thompson, Michael A

    2017-04-06

    Thin films of dispersions of light-absorbing solid particles or emulsions containing a light-absorbing solute all have a nonuniform distribution of light-absorbing species throughout the sample volume. This results in nonuniform light absorption over the illuminated area, which causes the optical absorbance, as measured using a conventional specular UV-vis spectrophotometer, to deviate from the Beer-Lambert relationship. We have developed a theoretical model to account for the absorbance properties of such films, which are shown to depend on the size and volume fraction of the light-absorbing particles plus other sample variables. We have compared model predictions with measured spectra for samples consisting of emulsions containing a dissolved light-absorbing solute. Using no adjustable parameters, the model successfully predicts the behavior of nonuniform, light-absorbing emulsion films with varying values of droplet size, volume fraction, and other parameters.

  11. Light Absorbing Particle (LAP) Measurements in the Lower Stratosphere

    NASA Technical Reports Server (NTRS)

    Baumgardner, D.; Raga, G. B.; Anderson, B.; Diskin, G.; Sachse, G.; Kok, G.

    2003-01-01

    This viewgraph presentation covers the capabilities and design of the Single Particle Soot Photometer (SP-2), and reviews its role on the Sage III Ozone Loss Validation Experiment (SOLVE II) field campaign during 2003. On SOLVE II the SP-2 was carried into the Arctic onboard a DC-8 aircraft, in order to determine the size distribution of light-absorbing and non light-absorbing particles in the stratosphere. Graphs and tables relate some of the results from SOLVE II.

  12. Three-dimensional light trap for reflective particles

    DOEpatents

    Neal, D.R.

    1999-08-17

    A system is disclosed for containing either a reflective particle or a particle having an index of refraction lower than that of the surrounding media in a three-dimensional light cage. A light beam from a single source illuminates an optics system and generates a set of at least three discrete focused beams that emanate from a single exit aperture and focus on to a focal plane located close to the particle. The set of focal spots defines a ring that surrounds the particle. The set of focused beams creates a ``light cage`` and circumscribes a zone of no light within which the particle lies. The surrounding beams apply constraining forces (created by radiation pressure) to the particle, thereby containing it in a three-dimensional force field trap. A diffractive element, such as an aperture multiplexed lens, or either a Dammann grating or phase element in combination with a focusing lens, may be used to generate the beams. A zoom lens may be used to adjust the size of the light cage, permitting particles of various sizes to be captured and contained. 10 figs.

  13. Three-dimensional light trap for reflective particles

    DOEpatents

    Neal, Daniel R.

    1999-01-01

    A system for containing either a reflective particle or a particle having an index of refraction lower than that of the surrounding media in a three-dimensional light cage. A light beam from a single source illuminates an optics system and generates a set of at least three discrete focussed beams that emanate from a single exit aperture and focus on to a focal plane located close to the particle. The set of focal spots defines a ring that surrounds the particle. The set of focussed beams creates a "light cage" and circumscribes a zone of no light within which the particle lies. The surrounding beams apply constraining forces (created by radiation pressure) to the particle, thereby containing it in a three-dimensional force field trap. A diffractive element, such as an aperture multiplexed lens, or either a Dammann grating or phase element in combination with a focusing lens, may be used to generate the beams. A zoom lens may be used to adjust the size of the light cage, permitting particles of various sizes to be captured and contained.

  14. Fast and accurate line scanner based on white light interferometry

    NASA Astrophysics Data System (ADS)

    Lambelet, Patrick; Moosburger, Rudolf

    2013-04-01

    White-light interferometry is a highly accurate technology for 3D measurements. The principle is widely utilized in surface metrology instruments but rarely adopted for in-line inspection systems. The main challenges for rolling out inspection systems based on white-light interferometry to the production floor are its sensitivity to environmental vibrations and relatively long measurement times: a large quantity of data needs to be acquired and processed in order to obtain a single topographic measurement. Heliotis developed a smart-pixel CMOS camera (lock-in camera) which is specially suited for white-light interferometry. The demodulation of the interference signal is treated at the level of the pixel which typically reduces the acquisition data by one orders of magnitude. Along with the high bandwidth of the dedicated lock-in camera, vertical scan-speeds of more than 40mm/s are reachable. The high scan speed allows for the realization of inspection systems that are rugged against external vibrations as present on the production floor. For many industrial applications such as the inspection of wafer-bumps, surface of mechanical parts and solar-panel, large areas need to be measured. In this case either the instrument or the sample are displaced laterally and several measurements are stitched together. The cycle time of such a system is mostly limited by the stepping time for multiple lateral displacements. A line-scanner based on white light interferometry would eliminate most of the stepping time while maintaining robustness and accuracy. A. Olszak proposed a simple geometry to realize such a lateral scanning interferometer. We demonstrate that such inclined interferometers can benefit significantly from the fast in-pixel demodulation capabilities of the lock-in camera. One drawback of an inclined observation perspective is that its application is limited to objects with scattering surfaces. We therefore propose an alternate geometry where the incident light is

  15. Faster-than-Light Particles: A Review of Tachyon Characteristics.

    DTIC Science & Technology

    1980-10-01

    A-DlAO9(4 529 RAND CORP SANTA MNtICA CA F/6 20/S FASTER-THAN-LIBI4T PARTICLES: A REVIEW OF TACHYON CHARACTERISTIC--ETCWU) OCT B0 E A PUSCHER F49620...77-C-0023 UNCLASSIFIED RAI0IN-1530-AF N. I nmui ininmuuuI LEVEL A RAND NOTE FASTER-THAN-LIGHT PARTICLES: A REVIEW OF ) ( TACHYON CHARACTERISTICS Edward...RECIPIENT’S CATALOG NUMBER 4TIT LE ( d Subtitle) TYPE OF REPORT & PERIOD COVERED ( Faster-than-Light Particles: A Review of /Interim -i Tachyon

  16. Nonlinear alfvénic fast particle transport and losses

    NASA Astrophysics Data System (ADS)

    Schneller, M.; Lauber, Ph; García-Muñoz, M.; Brüdgam, M.; Günter, S.

    2012-12-01

    Magnetohydrodynamic instabilities like Toroidal Alfvén Eigenmodes or core-localized modes such as Beta Induced Alfvén Eigenmodes and Reversed Shear Alfvén Eigenmodes driven by fast particles can lead to significant redistribution and losses in fusion devices. This is observed in many ASDEX Upgrade discharges. The present work aims to understand the underlying resonance mechanisms, especially in the presence of multiple modes with different frequencies. Resonant mode coupling mechanisms are investigated using the drift kinetic HAGIS code [Pinches 1998]. Simulations were performed for different plasma equilibria, in particular for different q profiles, employing the availability of improved experimental data. A study was carried out, investigating double-resonant mode coupling with respect to various overlapping scenarios. It was found that, depending on the radial mode distance, double-resonance is able to enhance growth rates as well as mode amplitudes significantly. Small radial mode distances, however can also lead to strong nonlinear mode stabilization of a linear dominant mode. With the extended version of HAGIS, losses were simulated and directly compared with experimental loss measurements. The losses' phase space distribution as well as their ejection signal is consistent with experimental data. Furthermore, it allowed to characterize them as prompt, resonant or stochastic. It was found that especially in multiple mode scenarios (with different mode frequencies), abundant incoherent losses occur in the lower energy range, due to a broad phase-space stochastization. The incoherent higher energetic losses are "prompt", i.e. their initial energy is too large for confined orbits.

  17. Light Scattering by Inhomogeneous Composite Particles.

    NASA Astrophysics Data System (ADS)

    Srivastava, Vandana

    The scattering characteristics of various composites is calculated using the effective medium approximations. There are several effective medium theories that can be applied, each leading to a different result. Experimentally, a set of scattering data for well defined composite spheres is obtained. The effective medium approximations are tested against the experimental results. The Bruggeman (1935) mixing rule and Maxwell Garnett (1904) theory, with proper inclusion and matrix model, lead to good agreement with the measurements. A generalized theory has also been derived (Chylek and Srivastava, 1983) which gives an iterative scheme for calculating the effective refractive index for composite medium. The Chylek-Srivastava iterative rule that takes into account all the electric and magnetic interactions for the absorbing component also leads to a good agreement with the measurements. This generalized theory can be applied to composites that contain a highly absorbing component with particle sizes comparable to the wavelength of incident radiation. Application of the Chylek-Srivastava iterative method to carbon-snow composites leads to calculated snow albedos that are in very good agreement with the measured albedos, eliminating the discrepancies that have existed for many years between calculated and measured albedos. Therefore, small amounts of absorbing impurities like carbon can significantly alter the scattering characteristics of composite particles. Carbon content of snow is also measured at different sites categorized as urban, rural, or remote, depending upon their location and elevation. The content varies according to the location of the site and the time of snow collection. However, ice from Camp Century, Greenland, that is several thousand years old contains the same order of graphitic carbon as does the remote polar surface snow at present. Backscattering of water-ice composites like hailstones depends upon the liquid water content and the topological

  18. Coherent Light induced in Optical Fiber by a Charged Particle

    NASA Astrophysics Data System (ADS)

    Artru, Xavier; Ray, Cédric

    2016-07-01

    Coherent light production in an optical fiber by a charged particle (named PIGL, for particle-induced guided, light) is reviewed. From the microscopic point of view, light is emitted by transient electric dipoles induced in the fiber medium by the Coulomb field of the particle. The phenomenon can also considered as the capture of virtual photons of the particle field by the fiber. Two types of captures are distinguished. Type-I takes place in a uniform part of the fiber; then the photon keeps its longitudinal momentum pz . Type-II takes place near an end or in a non-uniform part of the fiber; then pz is not conserved. Type-I PIGL is not affected by background lights external to the fiber. At grazing incidence it becomes nearly monochromatic. Its circular polarization depends on the angular momentum of the particle about the fiber and on the relative velocity between the particle and the guided wave. A general formula for the yield of Type-II radiation, based on the reciprocity theorem, is proposed. This radiation can be assisted by metallic objects stuck to the fiber, via plasmon excitation. A periodic structure leads to a guided Smith-Purcell radiation. Applications of PIGL in beam diagnostics are considered.

  19. Particle Shape Characterization of Lunar Regolith using Reflected Light Microscopy

    NASA Astrophysics Data System (ADS)

    McCarty, C. B.; Garcia, G. C.; Rickman, D.

    2014-12-01

    Automated identification of particles in lunar thin sections is necessary for practical measurement of particle shape, void characterization, and quantitative characterization of sediment fabric. This may be done using image analysis, but several aspects of the lunar regolith make such automations difficult. For example, many of the particles are shattered; others are aggregates of smaller particles. Sieve sizes of the particles span 5 orders of magnitude. The physical thickness of a thin section, at a nominal 30 microns, is large compared to the size of many of the particles. Image acquisition modes, such as SEM and reflected light, while superior to transmitted light, still have significant ambiguity as to the volume being sampled. It is also desirable to have a technique that is inexpensive, not resource intensive, and analytically robust. To this end, we have developed an image acquisition and processing protocol that identifies and delineates resolvable particles on the front surface of a lunar thin section using a petrographic microscope in reflected light. For a polished thin section, a grid is defined covering the entire thin section. The grid defines discrete images taken with 20% overlap, minimizing the number of particles that intersect image boundaries. In reflected light mode, two images are acquired at each grid location, with a closed aperture diaphragm. One image, A, is focused precisely on the front surface of the thin section. The second image, B, is made after the stage is brought toward the objective lens just slightly. A bright fringe line, analogous to a Becke line, appears inside all transparent particles at the front surface of the section in the second image. The added light in the bright line corresponds to a deficit around the particles. Particle identification is done using ImageJ and uses multiple steps. A hybrid 5x5 median filter is used to make images Af and Bf. This primarily removes very small particles just below the front surface

  20. SMARTIES: User-friendly codes for fast and accurate calculations of light scattering by spheroids

    NASA Astrophysics Data System (ADS)

    Somerville, W. R. C.; Auguié, B.; Le Ru, E. C.

    2016-05-01

    We provide a detailed user guide for SMARTIES, a suite of MATLAB codes for the calculation of the optical properties of oblate and prolate spheroidal particles, with comparable capabilities and ease-of-use as Mie theory for spheres. SMARTIES is a MATLAB implementation of an improved T-matrix algorithm for the theoretical modelling of electromagnetic scattering by particles of spheroidal shape. The theory behind the improvements in numerical accuracy and convergence is briefly summarized, with reference to the original publications. Instructions of use, and a detailed description of the code structure, its range of applicability, as well as guidelines for further developments by advanced users are discussed in separate sections of this user guide. The code may be useful to researchers seeking a fast, accurate and reliable tool to simulate the near-field and far-field optical properties of elongated particles, but will also appeal to other developers of light-scattering software seeking a reliable benchmark for non-spherical particles with a challenging aspect ratio and/or refractive index contrast.

  1. QUANTUM CONTROL OF LIGHT: From Slow Light and FAST CARS to Nuclear γ-ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Scully, Marlan

    2007-06-01

    In recent work we have demonstrated strong coherent backward wave oscillation using forward propagating fields only. This surprising result is achieved by applying laser fields to an ultra-dispersive medium with proper chosen detunings to excite a molecular vibrational coherence that corresponds to a backward propagating wave [PRL, 97, 113001 (2006)]. The physics then has much in common with propagation of ultra-slow light. Applications of coherent scattering and remote sensing to the detection of bio and chemical pathogens (e.g., anthrax) via Coherent Anti-Raman Scattering together with Femtosecond Adaptive Spectroscopic Techniques (FAST CARS [Opt. Comm., 244, 423 (2005)]) will be discussed. Furthermore, the interplay between quantum optics (Dicke super and sub-radiant states) and nuclear physics (forward scattering of γ radiation) provides interesting problems and insights into the quantum control of scattered light [PRL, 96, 010501 (2005)].

  2. Particle-in-cell simulations of particle energization from low Mach number fast mode shocks

    NASA Astrophysics Data System (ADS)

    Park, Jaehong; Workman, Jared C.; Blackman, Eric G.; Ren, Chuang; Siller, Robert

    2012-06-01

    Astrophysical shocks are often studied in the high Mach number limit but weakly compressive fast shocks can occur in magnetic reconnection outflows and are considered to be a site of particle energization in solar flares. Here we study the microphysics of such perpendicular, low Mach number collisionless shocks using two-dimensional particle-in-cell simulations with a reduced ion/electron mass ratio and employ a moving wall boundary method for initial generation of the shock. This moving wall method allows for more control of the shock speed, smaller simulation box sizes, and longer simulation times than the commonly used fixed wall, reflection method of shock formation. Our results, which are independent of the shock formation method, reveal the prevalence shock drift acceleration (SDA) of both electron and ions in a purely perpendicular shock with Alfvén Mach number MA=6.8 and ratio of thermal to magnetic pressure β=8. We determine the respective minimum energies required for electrons and ions to incur SDA. We derive a theoretical electron distribution via SDA that compares to the simulation results. We also show that a modified two-stream instability due to the incoming and reflecting ions in the shock transition region acts as the mechanism to generate collisionless plasma turbulence that sustains the shock.

  3. Light scattering by subwavelength Cu2O particles.

    PubMed

    Ullah, Kaleem; Liu, Xuefeng; Yadav, N P; Habib, Muhammad; Song, Li; García-Cámara, Braulio

    2017-03-01

    Novel metamaterials with new capabilities to manipulate light may be used by considering basic building blocks with new optical properties. This is the case with resonant magneto-dielectric particles. In this work, the resonant response of a high-dielectric Cu2O subwavelength particle is analyzed, both analytically and experimentally. The emergence of electric and magnetic resonances and their interferential effects, producing directional behaviors, can be used in a new generation of metamaterials, as well as new integrated optical devices.

  4. Light scattering by subwavelength Cu2O particles

    NASA Astrophysics Data System (ADS)

    Ullah, Kaleem; Liu, Xuefeng; Yadav, N. P.; Habib, Muhammad; Song, Li; García-Cámara, Braulio

    2017-03-01

    Novel metamaterials with new capabilities to manipulate light may be used by considering basic building blocks with new optical properties. This is the case with resonant magneto-dielectric particles. In this work, the resonant response of a high-dielectric Cu2O subwavelength particle is analyzed, both analytically and experimentally. The emergence of electric and magnetic resonances and their interferential effects, producing directional behaviors, can be used in a new generation of metamaterials, as well as new integrated optical devices.

  5. Morphologic tomography of nonspherical particles using multispectral diffusing light measurements

    PubMed Central

    Hajihashemi, Mohammad Reza; Li, Xiaoqi; Jiang, Huabei

    2011-01-01

    A series of phantom experiments are conducted to demonstrate the ability of a T-matrix–based inverse algorithm for tomographic recovery of morphologic characteristics of nonspherical particles embedded in heterogeneous turbid media. Diffusely scattered light at several wavelengths along the boundary of the phantom are collected and analyzed to allow for simultaneous extraction of the size, concentration, and aspect ratio of the spheroidal particles. PMID:22112119

  6. Exact simulation of polarized light reflectance by particle deposits

    NASA Astrophysics Data System (ADS)

    Ramezan Pour, B.; Mackowski, D. W.

    2015-12-01

    The use of polarimetric light reflection measurements as a means of identifying the physical and chemical characteristics of particulate materials obviously relies on an accurate model of predicting the effects of particle size, shape, concentration, and refractive index on polarized reflection. The research examines two methods for prediction of reflection from plane parallel layers of wavelength—sized particles. The first method is based on an exact superposition solution to Maxwell's time harmonic wave equations for a deposit of spherical particles that are exposed to a plane incident wave. We use a FORTRAN-90 implementation of this solution (the Multiple Sphere T Matrix (MSTM) code), coupled with parallel computational platforms, to directly simulate the reflection from particle layers. The second method examined is based upon the vector radiative transport equation (RTE). Mie theory is used in our RTE model to predict the extinction coefficient, albedo, and scattering phase function of the particles, and the solution of the RTE is obtained from adding—doubling method applied to a plane—parallel configuration. Our results show that the MSTM and RTE predictions of the Mueller matrix elements converge when particle volume fraction in the particle layer decreases below around five percent. At higher volume fractions the RTE can yield results that, depending on the particle size and refractive index, significantly depart from the exact predictions. The particle regimes which lead to dependent scattering effects, and the application of methods to correct the vector RTE for particle interaction, will be discussed.

  7. Measurements of Light Absorbing Particles on Tropical South American Glaciers

    NASA Astrophysics Data System (ADS)

    Schmitt, C. G.; All, J.; Schwarz, J. P.; Arnott, W. P.; Warthon, J.; Andrade, M.; Celestian, A. J.; Hoffmann, D.; Cole, R. J.; Lapham, E.; Horodyskyj, U. N.; Froyd, K. D.; Liao, J.

    2014-12-01

    Glaciers in the tropical Andes have been losing mass rapidly in recent decades. In addition to the documented increase in temperature, increases in light absorbing particulates deposited on glaciers could be contributing to the observed glacier loss. Here we present results of measurements of light absorbing particles from glaciers in Peru and Bolivia. Samples have been collected by American Climber Science Program volunteers and scientists at altitudes up to 6770 meters. Collected snow samples were melted and filtered in the field. A new inexpensive technique, the Light Absorption Heating Method (LAHM) has been developed for analysis of light absorbing particles collected on filters. Results from LAHM analysis are calibrated using filters with known amounts of fullerene soot, a common industrial surrogate for black carbon (BC). For snow samples collected at the same field location LAHM analysis and measurements from the Single Particle Soot Photometer (SP2) instrument are well correlated (r2 = 0.92). Co-located SP2 and LAHM filter analysis suggest that BC could be the dominant absorbing component of the light absorbing particles in some areas.

  8. Fast neutral particle measurements in LHD and CHS

    SciTech Connect

    Ozaki, T.; Okamura, S.; Zanza, V.

    1996-12-31

    The development of high energy neutral particle measurement system for ion temperature measurements and high energy particle confinement analysis in Large Helical Device is described here. For NBIs, 180 keV hydrogen beams will be used in Phase 1 of LHD experiment schedule and 360 keV deuterium beams will be used in Phase 2. In ICRF heating experiment, the hydrogen and helium-3 will be used as minorities. It is important to observe the pitch angle distribution to investigate the confinement of high energy particles. For this purpose the neutral particle analyzer should have a wide observation energy range above the maximum energy of NBI and an ability to separate the particle species of hydrogen, deuterium and He-3. In Compact Helical System (CHS), the electrostatic neutral particle analyzer is used. They have compared the spectrum obtained from the measurement by a passive method in CHS with that from the calculation by PROCTR code.

  9. Gyrokinetic particle simulation of fast-electron driven beta-induced Aflvén eigenmode

    NASA Astrophysics Data System (ADS)

    Cheng, Junyi; Zhang, Wenlu; Lin, Zhihong; Holod, Ihor; Li, Ding; Chen, Yang; Cao, Jintao

    2016-05-01

    The fast-electron driven beta-induced Alfvén eigenmode (e-BAE) in toroidal plasmas is investigated for the first time using global gyrokinetic particle simulations, where the fast electron is described by the drift kinetic equation. The simulation shows that the e-BAE propagates in the fast electron diamagnetic direction and its polarization is close to an ideal MHD mode. The phase space structure shows that only the fast electron processional resonance is responsible for the e-BAE excitations while fast-ion driven BAE can be excited through all the channels, including transit, bounce, and processional resonance.

  10. Integrated ultrasonic particle positioning and low excitation light fluorescence imaging

    SciTech Connect

    Bernassau, A. L.; Al-Rawhani, M.; Beeley, J.; Cumming, D. R. S.

    2013-12-09

    A compact hybrid system has been developed to position and detect fluorescent micro-particles by combining a Single Photon Avalanche Diode (SPAD) imager with an acoustic manipulator. The detector comprises a SPAD array, light-emitting diode (LED), lenses, and optical filters. The acoustic device is formed of multiple transducers surrounding an octagonal cavity. By stimulating pairs of transducers simultaneously, an acoustic landscape is created causing fluorescent micro-particles to agglomerate into lines. The fluorescent pattern is excited by a low power LED and detected by the SPAD imager. Our technique combines particle manipulation and visualization in a compact, low power, portable setup.

  11. MCNPX Monte Carlo simulations of particle transport in SiC semiconductor detectors of fast neutrons

    NASA Astrophysics Data System (ADS)

    Sedlačková, K.; Zat'ko, B.; Šagátová, A.; Pavlovič, M.; Nečas, V.; Stacho, M.

    2014-05-01

    The aim of this paper was to investigate particle transport properties of a fast neutron detector based on silicon carbide. MCNPX (Monte Carlo N-Particle eXtended) code was used in our study because it allows seamless particle transport, thus not only interacting neutrons can be inspected but also secondary particles can be banked for subsequent transport. Modelling of the fast-neutron response of a SiC detector was carried out for fast neutrons produced by 239Pu-Be source with the mean energy of about 4.3 MeV. Using the MCNPX code, the following quantities have been calculated: secondary particle flux densities, reaction rates of elastic/inelastic scattering and other nuclear reactions, distribution of residual ions, deposited energy and energy distribution of pulses. The values of reaction rates calculated for different types of reactions and resulting energy deposition values showed that the incident neutrons transfer part of the carried energy predominantly via elastic scattering on silicon and carbon atoms. Other fast-neutron induced reactions include inelastic scattering and nuclear reactions followed by production of α-particles and protons. Silicon and carbon recoil atoms, α-particles and protons are charged particles which contribute to the detector response. It was demonstrated that although the bare SiC material can register fast neutrons directly, its detection efficiency can be enlarged if it is covered by an appropriate conversion layer. Comparison of the simulation results with experimental data was successfully accomplished.

  12. Teaching Conservation Laws, Symmetries and Elementary Particles with Fast Feedback

    ERIC Educational Resources Information Center

    van den Berg, Ed; Hoekzema, Dick

    2006-01-01

    Lessons about elementary particles at the secondary school level can degenerate into listing a zoo of particles and reactions, resulting in disorganized and rather meaningless knowledge. A more powerful way is to focus on conservation laws, symmetries and reaction diagrams. The conservation laws and symmetries provide generalizing power that…

  13. An experimental study of light scattering by large, irregular particles

    NASA Technical Reports Server (NTRS)

    Mcguire, Audrey F.; Hapke, Bruce W.

    1995-01-01

    The intensity and polarization of light scattered by a variety of types of artificial partices large compared to the wavelength were measured as a function of phase angle. Shape, surface roughness, absorption coefficient, and internal scattering coefficient were varied systematically and their effects studied. Scattering by clear, smooth-surfaced spheres is in quantitative agreement with the predictions of the geometrical optics (ray theory) approximation to physical optics (Mie theory). The phase functions of almost all of the particles measured have both forward and backward scattering lobes. A two-parameter, double Henyey-Greenstein function generally provides reasonably good descriptions of the data, while keeping the number of free parameters to the minimum necessary. On a double Henyey- Greenstein parameter plot all of the particles fall into an L-shaped area of restricted size in which the location is characteristic of the particle type. Formalisms based on the equivalent slab model are also given for estimating the scattering efficiency of a large, irregular particle. For most dielectric particles the transmitted, forward scattered light is partially negatively polarized. It is this component that is respopnsible for the well-known maximum in the polarization curves of planetary regoliths at phase angles around 100 deg. For phase angles between about 30 deg and 70 deg the internally scattered light is found to be randomly polarized in the particles studied here, so that the only contribution to the second component of the Stokes vector is by Fresnel reflection from the particle surface. If this empirical result is general, measurement of the second Stokes vector of the light scattered from a regolith at these angles may provide a method of remotely measuring the mean refractive index.

  14. Computation of scattering matrix elements of large and complex shaped absorbing particles with multilevel fast multipole algorithm

    NASA Astrophysics Data System (ADS)

    Wu, Yueqian; Yang, Minglin; Sheng, Xinqing; Ren, Kuan Fang

    2015-05-01

    Light scattering properties of absorbing particles, such as the mineral dusts, attract a wide attention due to its importance in geophysical and environment researches. Due to the absorbing effect, light scattering properties of particles with absorption differ from those without absorption. Simple shaped absorbing particles such as spheres and spheroids have been well studied with different methods but little work on large complex shaped particles has been reported. In this paper, the surface Integral Equation (SIE) with Multilevel Fast Multipole Algorithm (MLFMA) is applied to study scattering properties of large non-spherical absorbing particles. SIEs are carefully discretized with piecewise linear basis functions on triangle patches to model whole surface of the particle, hence computation resource needs increase much more slowly with the particle size parameter than the volume discretized methods. To improve further its capability, MLFMA is well parallelized with Message Passing Interface (MPI) on distributed memory computer platform. Without loss of generality, we choose the computation of scattering matrix elements of absorbing dust particles as an example. The comparison of the scattering matrix elements computed by our method and the discrete dipole approximation method (DDA) for an ellipsoid dust particle shows that the precision of our method is very good. The scattering matrix elements of large ellipsoid dusts with different aspect ratios and size parameters are computed. To show the capability of the presented algorithm for complex shaped particles, scattering by asymmetry Chebyshev particle with size parameter larger than 600 of complex refractive index m = 1.555 + 0.004 i and different orientations are studied.

  15. Towards Fast, Scalable Hard Particle Monte Carlo Simulations on GPUs

    NASA Astrophysics Data System (ADS)

    Anderson, Joshua A.; Irrgang, M. Eric; Glaser, Jens; Harper, Eric S.; Engel, Michael; Glotzer, Sharon C.

    2014-03-01

    Parallel algorithms for Monte Carlo simulations of thermodynamic ensembles of particles have received little attention because of the inherent serial nature of the statistical sampling. We discuss the implementation of Monte Carlo for arbitrary hard shapes in HOOMD-blue, a GPU-accelerated particle simulation tool, to enable million particle simulations in a field where thousands is the norm. In this talk, we discuss our progress on basic parallel algorithms, optimizations that maximize GPU performance, and communication patterns for scaling to multiple GPUs. Research applications include colloidal assembly and other uses in materials design, biological aggregation, and operations research.

  16. The impact of dust particle morphological details on light scattering

    NASA Astrophysics Data System (ADS)

    Kemppinen, Osku; Nousiainen, Timo; Lindqvist, Hannakaisa; Jeong, Gi Young

    2016-04-01

    We investigate the impact of dust particle surface roughness and internal structure on light scattering. Starting from digital representation of realistically shaped dust particles, we vary the particle morphology, and perform light scattering simulations to both the original and the modified particles. By mapping the changes in morphology to the changes in scattering, we will get information of how strongly and in which way a particular change affects scattering. All investigations have been done with complex, irregular particle shapes. For surface roughness studies we have kept the particle total volume virtually constant during the roughening process, and the roughness element size small enough to keep the overall shape relatively unchanged. For internal structure studies, the size and the external shape are kept constant. These safety measures help ensure that the effects seen are in fact due to the feature studied. The work is notable for model development, because some models can not include surface roughness, for example. In that case, the people who use such models have to adjust for the fact that the results are inaccurate, and by knowing how surface roughness typically changes the scattering results, the adjustment can be made. As a corollary, if it is shown that a particular feature does not change scattering results in any noticeable way, the model developers can confidently ignore or simplify it.

  17. LIGHT SCATTERING: Fast path-integration technique in simulation of light propagation through highly scattering objects

    NASA Astrophysics Data System (ADS)

    Voronov, Aleksandr V.; Tret'yakov, Evgeniy V.; Shuvalov, Vladimir V.

    2004-06-01

    Based on the path-integration technique and the Metropolis method, the original calculation scheme is developed for solving the problem of light propagation through highly scattering objects. The elimination of calculations of 'unnecessary' realisations and the phenomenological description of processes of multiple small-angle scattering provided a drastic increase (by nine and more orders of magnitude) in the calculation rate, retaining the specific features of the problem (consideration of spatial inhomogeneities, boundary conditions, etc.). The scheme allows one to verify other fast calculation algorithms and to obtain information required to reconstruct the internal structure of highly scattering objects (of size ~1000 scattered lengths and more) by the method of diffusion optical tomography.

  18. Cherenkov light imaging in astro-particle physics

    NASA Astrophysics Data System (ADS)

    Mirzoyan, Razmik

    2014-12-01

    Cherenkov light emission plays a key role in contemporary science; it is widely used in high energy, nuclear, and numerous astro-particle physics experiments. Most astro-particle physics experiments are based on the detection of light, and a vast majority of them on the measurement of Cherenkov light. Cherenkov light emission is measured in gases (used in air-Cherenkov technique), in water (for example, neutrino experiments BAIKAL, Super-Kamiokande, NESTOR, ANTARES, future KM3NeT; cosmic and γ-ray experiments Milagro, HAWC, AUGER) and in ice (IceCube). In this report our goal is not limited to simply listing the multitude of experiments that are based on using Cherenkov emission, but we will clarify the reasons making this emission so important and so frequently used. For completeness we will first give a short historical overview on the discovery and evolution of Cherenkov emission and then we will dwell on its main features and numerous applications in astro-particle physics experiments.

  19. Models of filter-based particle light absorption measurements

    NASA Astrophysics Data System (ADS)

    Hamasha, Khadeejeh M.

    Light absorption by aerosol is very important in the visible, near UN, and near I.R region of the electromagnetic spectrum. Aerosol particles in the atmosphere have a great influence on the flux of solar energy, and also impact health in a negative sense when they are breathed into lungs. Aerosol absorption measurements are usually performed by filter-based methods that are derived from the change in light transmission through a filter where particles have been deposited. These methods suffer from interference between light-absorbing and light-scattering aerosol components. The Aethalometer is the most commonly used filter-based instrument for aerosol light absorption measurement. This dissertation describes new understanding of aerosol light absorption obtained by the filter method. The theory uses a multiple scattering model for the combination of filter and particle optics. The theory is evaluated using Aethalometer data from laboratory and ambient measurements in comparison with photoacoustic measurements of aerosol light absorption. Two models were developed to calculate aerosol light absorption coefficients from the Aethalometer data, and were compared to the in-situ aerosol light absorption coefficients. The first is an approximate model and the second is a "full" model. In the approximate model two extreme cases of aerosol optics were used to develop a model-based calibration scheme for the 7-wavelength Aethalometer. These cases include those of very strong scattering aerosols (Ammonium sulfate sample) and very absorbing aerosols (kerosene soot sample). The exponential behavior of light absorption in the strong multiple scattering limit is shown to be the square root of the total absorption optical depth rather than linear with optical depth as is commonly assumed with Beer's law. 2-stream radiative transfer theory was used to develop the full model to calculate the aerosol light absorption coefficients from the Aethalometer data. This comprehensive model

  20. Nonequilibrium Decays of Light Particles and Primordial Nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Dolgov, A. D.; Kirilova, D. P.

    Possible modifications of the standard big-bang nucleosynthesis scenario, which would loosen the bound on the number of neutrino flavors, are examined. A concrete model with light ((mx=O(MeV)) quasistable particles (τx 1 s) decaying into ν bar {ν } is considered. If the decay products do not thermalize they shift the frozen neutron-to-proton ratio and respectively the abundance of the light element produced primordially. The direction of this shift depends on the parameters of the model. Correspondingly for the particular choice of these parameters the restrictions on the number of neutrino flavors may be considerably weakened.

  1. Development of a Bioaerosol single particle detector (BIO IN) for the Fast Ice Nucleus CHamber FINCH

    NASA Astrophysics Data System (ADS)

    Bundke, U.; Reimann, B.; Nillius, B.; Jaenicke, R.; Bingemer, H.

    2010-02-01

    In this work we present the setup and first tests of our new BIO IN detector. This detector was constructed to classify atmospheric ice nuclei (IN) for their biological content. It is designed to be coupled to the Fast Ice Nucleus CHamber FINCH. If one particle acts as an ice nucleus, it will be at least partly covered with ice at the end of the development section of the FINCH chamber. The device combines an auto-fluorescence detector and a circular depolarization detector for simultaneous detection of biological material and discrimination between water droplets, ice crystals and non activated large aerosol particles. The excitation of biological material with UV light and analysis of auto-fluorescence is a common principle used for flow cytometry, fluorescence microscopy, spectroscopy and imaging. The detection of auto-fluorescence of airborne single particles demands some more experimental effort. However, expensive commercial sensors are available for special purposes, e.g. size distribution measurements. But these sensors will not fit the specifications needed for the FINCH IN counter (e.g. high sample flow of up 10 LPM). The newly developed -low cost- BIO IN sensor uses a single high-power UV LED for the electronic excitation instead of much more expensive UV lasers. Other key advantages of the new sensor are the low weight, compact size, and the little effect on the aerosol sample, which allows it to be coupled with other instruments for further analysis. The instrument will be flown on one of the first missions of the new German research aircraft "HALO" (High Altitude and LOng range).

  2. Module for dielectric surfaces modification by fast neutral particles beams

    NASA Astrophysics Data System (ADS)

    Barchenko, V. T.; Lisenkov, A. A.; Babinov, N. A.

    2014-11-01

    In this paper, we describe the module for dielectric and wide-gap semiconductor surfaces modification by fast neutral beam. The module can be used for cleaning, etching or assisting of films deposition. The surface proceeding by neutral beam can prevent an accumulation of surface charge without using current compensation by inserting electrons to the beam or RF power supply. The module beside cathode and anode contains an electrode with floating potential. Insertion of the additional electrode causes electron retention in an electrostatic trap resulting the reducing of the module operating pressure. Moreover, the electrode with floating potential allows increasing the current efficient of the module. An important feature of the module is that neutralization of the ions extracted from the plasma occurs in the cathode potential well. Thereby ions that have not neutralized cannot leave nearcathode region and there are no fast ions in the output beam. Module does not contain sources of the magnetic fields or elements heated by external sources. Module operates with free cooling. Thus, the module does not need water cooling and can be freely moved in the vacuum chamber.

  3. Detection of fast flying nanoparticles by light scattering over a large volume

    NASA Astrophysics Data System (ADS)

    Pettazzi, F.; Bäumer, S.; van der Donck, J.; Deutz, A.

    2015-06-01

    is a well-known detection method which is applied in many different scientific and technology domains including atmospheric physics, environmental control, and biology. It allows contactless and remote detection of sub-micron size particles. However, methods for detecting a single fast moving particle smaller than 100 nm are lacking. In the present work we report a preliminary design study of an inline large area detector for nanoparticles larger than 50 nm which move with velocities up to 100 m/s. The detector design is based on light scattering using commercially available components. The presented design takes into account all challenges connected to the inline implementation of the scattering technique in the system: the need for the detector to have a large field of view to cover a volume with a footprint commensurate to an area of 100mm x 100mm, the necessity to sense nanoparticles transported at high velocity, and the requirement of large capture rate with a false detection as low as one false positive per week. The impact of all these stringent requirements on the expected sensitivity and performances of the device is analyzed by mean of a dedicated performance model.

  4. Detecting light long-lived particle produced by cosmic ray

    NASA Astrophysics Data System (ADS)

    Yin, Peng-Fei; Zhu, Shou-Hua

    2010-03-01

    We investigate the possibility of detecting light long-lived particle (LLP) produced by high energy cosmic ray colliding with atmosphere. The LLP may penetrate the atmosphere and decay into a pair of muons near/in the neutrino telescope. Such muons can be treated as the detectable signal for neutrino telescope. This study is motivated by recent cosmic electron/positron observations which suggest the existence of O(TeV) dark matter and new light O(GeV) particle. It indicates that dark sector may be complicated, and there may exist more than one light particles, for example, the dark gauge boson A‧ and associated dark Higgs boson h‧. In this work, we discuss the scenario with A‧ heavier than h‧ and h‧ is treated as LLP. Based on our numerical estimation, we find that the large volume neutrino telescope IceCube has the capacity to observe several tens of di-muon events per year for favorable parameters if the decay length of LLP can be comparable with the depth of atmosphere. The challenge here is how to suppress the muon backgrounds induced by cosmic rays and atmospheric neutrinos.

  5. Experimental detection of transverse particle movement with structured light

    PubMed Central

    Rosales-Guzmán, Carmelo; Hermosa, Nathaniel; Belmonte, Aniceto; Torres, Juan P.

    2013-01-01

    One procedure widely used to detect the velocity of a moving object is by using the Doppler effect. This is the perceived change in frequency of a wave caused by the relative motion between the emitter and the detector, or between the detector and a reflecting target. The relative movement, in turn, generates a time-varying phase which translates into the detected frequency shift. The classical longitudinal Doppler effect is sensitive only to the velocity of the target along the line-of-sight between the emitter and the detector (longitudinal velocity), since any transverse velocity generates no frequency shift. This makes the transverse velocity undetectable in the classical scheme. Although there exists a relativistic transverse Doppler effect, it gives values that are too small for the typical velocities involved in most laser remote sensing applications. Here we experimentally demonstrate a novel way to detect transverse velocities. The key concept is the use of structured light beams. These beams are unique in the sense that their phases can be engineered such that each point in its transverse plane has an associated phase value. When a particle moves across the beam, the reflected light will carry information about the particle's movement through the variation of the phase of the light that reaches the detector, producing a frequency shift associated with the movement of the particle in the transverse plane. PMID:24085150

  6. Light organization of small particles by multiple scattering

    NASA Astrophysics Data System (ADS)

    Hang, Zhi Hong

    Optical manipulation is of broad interest in physics, chemistry, and biology. In the literature, most of the studies are focused on the optical trapping on a single object. In this thesis, we investigated the light-induced interaction of a collection of particles. The light-induced interaction between small particles was studied by a hierarchy of methods including the dipole theory, the multiple scattering and Maxwell stress tensor formalism, and the finite-difference-time-domain method. We showed that the multiple scattering between small particles could induce a binding mechanism to stabilize optically organized structures, but at the same time induced an intrinsic unbinding mechanism. The stability of optically organized structure was studied and a concept of "optical density" was introduced to gauge the destabilizing effect. We found that light-induced forces could bind dielectric spheres into extended structures through two mechanisms, each with its own length scale which could be adjusted by the configuration of the external light source. By manipulating the commensurability of the two length scales, these two mechanisms cooperated to bind a large number of spheres. When the two length scales became incommensurate for some particular incident angle, the competition between the two mechanisms led to modulated structures and other complex phenomena such as re-entrant stability. We searched for the possibility for stabilizing larger clusters. For this purpose, we found that circularly polarized light bound dielectric spheres into large-scale two-dimensional hexagonal lattice and multiple scattering also induced a rotation of optically bound structures. We searched for configurations that could induce optical trapping by field enhancement. Enhanced transmission on perforated metallic film system was studied. Surface modes bound on multi perforated perfect metal plate system were analytical solved and related to different high transmittance modes. Near

  7. Three-dimensional microscopic light field particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Truscott, Tadd T.; Belden, Jesse; Ni, Rui; Pendlebury, Jonathon; McEwen, Bryce

    2017-03-01

    A microscopic particle image velocimetry (μ {PIV}) technique is developed based on light field microscopy and is applied to flow through a microchannel containing a backward-facing step. The only hardware difference from a conventional μPIV setup is the placement of a microlens array at the intermediate image plane of the microscope. The method combines this optical hardware alteration with post-capture computation to enable 3D reconstruction of particle fields. From these particle fields, we measure three-component velocity fields, but find that accurate velocity measurements are limited to the two in-plane components at discrete depths through the volume (i.e., 2C-3D). Results are compared with a computational fluid dynamics simulation.

  8. A point particle model of lightly bound skyrmions

    NASA Astrophysics Data System (ADS)

    Gillard, Mike; Harland, Derek; Kirk, Elliot; Maybee, Ben; Speight, Martin

    2017-04-01

    A simple model of the dynamics of lightly bound skyrmions is developed in which skyrmions are replaced by point particles, each carrying an internal orientation. The model accounts well for the static energy minimizers of baryon number 1 ≤ B ≤ 8 obtained by numerical simulation of the full field theory. For 9 ≤ B ≤ 23, a large number of static solutions of the point particle model are found, all closely resembling size B subsets of a face centred cubic lattice, with the particle orientations dictated by a simple colouring rule. Rigid body quantization of these solutions is performed, and the spin and isospin of the corresponding ground states extracted. As part of the quantization scheme, an algorithm to compute the symmetry group of an oriented point cloud, and to determine its corresponding Finkelstein-Rubinstein constraints, is devised.

  9. Online submicron particle sizing by dynamic light scattering using autodilution

    NASA Technical Reports Server (NTRS)

    Nicoli, David F.; Elings, V. B.

    1989-01-01

    Efficient production of a wide range of commercial products based on submicron colloidal dispersions would benefit from instrumentation for online particle sizing, permitting real time monitoring and control of the particle size distribution. Recent advances in the technology of dynamic light scattering (DLS), especially improvements in algorithms for inversion of the intensity autocorrelation function, have made it ideally suited to the measurement of simple particle size distributions in the difficult submicron region. Crucial to the success of an online DSL based instrument is a simple mechanism for automatically sampling and diluting the starting concentrated sample suspension, yielding a final concentration which is optimal for the light scattering measurement. A proprietary method and apparatus was developed for performing this function, designed to be used with a DLS based particle sizing instrument. A PC/AT computer is used as a smart controller for the valves in the sampler diluter, as well as an input-output communicator, video display and data storage device. Quantitative results are presented for a latex suspension and an oil-in-water emulsion.

  10. Fast white-light interferometry with Hilbert transform evaluation

    NASA Astrophysics Data System (ADS)

    Pavliček, Pavel; Mikeska, Erik

    2016-12-01

    White-light interferometry is an established method for the measurement of the shape of objects. Unlike to the classical interferometry, white-light interferometry can measure the shape of objects with rough surface. A major disadvantage of white-light interferometry is the low scanning speed and thus the long measurement time. This disadvantage can be overcome by a strong undersampling and Hilbert transform evaluation. We propose a system that measures the shape of objects with rough surface with the scanning speed of more than 100 μm/s with the standard frame rate of 25 fps. The measurement uncertainty is comparable with that obtained with standard design.

  11. Resonant Alfven wave instabilities driven by streaming fast particles

    SciTech Connect

    Zachary, A.

    1987-05-08

    A plasma simulation code is used to study the resonant interactions between streaming ions and Alfven waves. The medium which supports the Alfven waves is treated as a single, one-dimensional, ideal MHD fluid, while the ions are treated as kinetic particles. The code is used to study three ion distributions: a cold beam; a monoenergetic shell; and a drifting distribution with a power-law dependence on momentum. These distributions represent: the field-aligned beams upstream of the earth's bow shock; the diffuse ions upstream of the bow shock; and the cosmic ray distribution function near a supernova remnant shock. 92 refs., 31 figs., 12 tabs.

  12. Fast excitation of geodesic acoustic mode by energetic particle beams

    SciTech Connect

    Cao, Jintao; Qiu, Zhiyong; Zonca, Fulvio

    2015-12-15

    A new mechanism for geodesic acoustic mode (GAM) excitation by a not fully slowed down energetic particle (EP) beam is analyzed to explain experimental observations in Large Helical Device. It is shown that the positive velocity space gradient near the lower-energy end of the EP distribution function can strongly drive the GAM unstable. The new features of this EP-induced GAM (EGAM) are: (1) no instability threshold in the pitch angle; (2) the EGAM frequency can be higher than the local GAM frequency; and (3) the instability growth rate is much larger than that driven by a fully slowed down EP beam.

  13. Stellar cooling bounds on new light particles: plasma mixing effects

    NASA Astrophysics Data System (ADS)

    Hardy, Edward; Lasenby, Robert

    2017-02-01

    Strong constraints on the coupling of new light particles to the Standard Model (SM) arise from their production in the hot cores of stars, and the effects of this on stellar cooling. For new light particles which have an effective in-medium mixing with the photon, plasma effects can result in parametrically different production rates to those obtained from a naive calculation. Taking these previously-neglected contributions into account, we make updated estimates for the stellar cooling bounds on light scalars and vectors with a variety of SM couplings. In particular, we improve the bounds on light ( m ≲ keV) scalars coupling to electrons or nucleons by up to 3 orders of magnitude in the coupling squared, significantly revise the supernova cooling bounds on dark photon couplings, and qualitatively change the mass dependence of stellar bounds on new vectors. Scalars with mass ≲ 2 keV that couple through the Higgs portal are constrained to mixing angle sin θ ≲ 3 × 10-10, which gives the dominant bound for scalar masses above ˜ 0 .2eV.

  14. Measurement of energetic-particle-driven core magnetic fluctuations and induced fast-ion transport

    NASA Astrophysics Data System (ADS)

    Lin, L.; Ding, W. X.; Brower, D. L.; Koliner, J. J.; Eilerman, S.; Reusch, J. A.; Anderson, J. K.; Nornberg, M. D.; Sarff, J. S.; Waksman, J.; Liu, D.

    2013-03-01

    Internal fluctuations arising from energetic-particle-driven instabilities, including both density and radial magnetic field, are measured in a reversed-field-pinch plasma. The fluctuations peak near the core where fast ions reside and shift outward along the major radius as the instability transits from the n = 5 to n = 4 mode. During this transition, strong nonlinear three-wave interaction among multiple modes accompanied by enhanced fast-ion transport is observed.

  15. Fast scalable visualization techniques for interactive billion-particle walkthrough

    NASA Astrophysics Data System (ADS)

    Liu, Xinlian

    This research develops a comprehensive framework for interactive walkthrough involving one billion particles in an immersive virtual environment to enable interrogative visualization of large atomistic simulation data. As a mixture of scientific and engineering approaches, the framework is based on four key techniques: adaptive data compression based on space-filling curves, octree-based visibility and occlusion culling, predictive caching based on machine learning, and scalable data reduction based on parallel and distributed processing. In terms of parallel rendering, this system combines functional parallelism, data parallelism, and temporal parallelism to improve interactivity. The visualization framework will be applicable not only to material simulation, but also to computational biology, applied mathematics, mechanical engineering, and nanotechnology, etc.

  16. Tunable temporal gap based on simultaneous fast and slow light in electro-optic photonic crystals.

    PubMed

    Li, Guangzhen; Chen, Yuping; Jiang, Haowei; Liu, Yi'an; Liu, Xiao; Chen, Xianfeng

    2015-07-13

    We demonstrated a tunable temporal gap based on simultaneous fast and slow light in electro-optic photonic crystals. The light experiences an anomalous dispersion near the transmission center and a normal dispersion away from the center, where it can be accelerated and slowed down, respectively. We also obtained the switch between fast and slow light by adjusting the external electric filed. The observed largest temporal gap is 541 ps, which is crucial in practical event operation inside the gap. The results offer a new solution for temporal cloak.

  17. Ionization of multielectron atoms by fast charged particles.

    NASA Technical Reports Server (NTRS)

    Omidvar, K.; Kyle, H. L.; Sullivan, E. C.

    1972-01-01

    Using plane waves to describe the incident and scattered particles, and screened hydrogenic and Coulomb functions to describe the atomic electrons before and after ejections, we have calculated the differential and total ionization cross sections of 11 atoms and one ion by electron impact, and ionization of helium by proton impact. The effective charges of the screened hydrogenic functions are fixed by the Hartree-Fock calculations. Calculations have been carried out for the atomic s, p, and d electrons. For low atomic numbers, we find reasonable agreement with the experimental data. For intermediate atomic numbers, we expect our results to overestimate the actual cross sections, since our choice of a unit charge for the Coulomb function of the ejected electrons will overestimate the atomic dipole potential strength, and in turn the high-energy cross sections. The advantage of the method presented here is that the ionization amplitude is given in analytic form. This may allow further analysis on this amplitude, and facilitates extension of the numerical integration for the cross section to high impact energies.

  18. Light absorption properties of laboratory generated tar ball particles

    NASA Astrophysics Data System (ADS)

    Hoffer, A.; Tóth, A.; Nyirő-Kósa, I.; Pósfai, M.; Gelencsér, A.

    2015-06-01

    Tar balls (TBs) are a specific particle type which is abundant in the global troposphere, in particular in biomass smoke plumes. These particles belong to the family of atmospheric brown carbon (BrC) which can absorb light in the visible range of the solar spectrum. Albeit TBs are typically present as individual particles in biomass smoke plumes, their absorption properties have been only indirectly inferred from field observations or calculations based on their electron energy-loss spectra. This is because in biomass smoke TBs coexist with various other particle types (e.g. organic particles with inorganic inclusions and soot, the latter is emitted mainly during flaming conditions) from which they cannot be physically separated; thus, a direct experimental determination of their absorption properties is not feasible. Very recently we have demonstrated that TBs can be generated in the laboratory from droplets of wood tar that resemble atmospheric TBs in all of their observed properties. As a follow-up study we have installed on-line instruments to our laboratory set-up generating pure TB particles to measure the absorption and scattering, as well as size distribution of the particles. In addition, samples were collected for transmission electron microscopy (TEM) and total carbon (TC) analysis. The effects of experimental parameters were also studied. The mass absorption coefficients of the laboratory generated TBs were found to be in the range of 0.8-3.0 m2 g-1 at 550 nm, with absorption Ångström exponents (AAE) between 2.7 and 3.4 (average 2.9) in the wavelength range 467-652 nm. The refractive index of TBs as derived from Mie calculations was about 1.84-0.21i at 550 nm. In the brown carbon continuum these values fall closer to those of soot than to other light-absorbing species such as humic-like substances (HULIS). Considering the abundance of TBs in biomass smoke and the global magnitude of biomass burning emissions, these findings may have substantial

  19. Light absorption properties of laboratory-generated tar ball particles

    NASA Astrophysics Data System (ADS)

    Hoffer, A.; Tóth, A.; Nyirő-Kósa, I.; Pósfai, M.; Gelencsér, A.

    2016-01-01

    Tar balls (TBs) are a specific particle type that is abundant in the global troposphere, in particular in biomass smoke plumes. These particles belong to the family of atmospheric brown carbon (BrC), which can absorb light in the visible range of the solar spectrum. Albeit TBs are typically present as individual particles in biomass smoke plumes, their absorption properties have been only indirectly inferred from field observations or calculations based on their electron energy-loss spectra. This is because in biomass smoke TBs coexist with various other particle types (e.g., organic particles with inorganic inclusions and soot, the latter emitted mainly during flaming conditions) from which they cannot be physically separated; thus, a direct experimental determination of their absorption properties is not feasible. Very recently we have demonstrated that TBs can be generated in the laboratory from droplets of wood tar that resemble atmospheric TBs in all of their observed properties. As a follow-up study, we have installed on-line instruments to our laboratory set-up, which generate pure TB particles to measure the absorption and scattering, as well as the size distribution of the particles. In addition, samples were collected for transmission electron microscopy (TEM) and total carbon (TC) analysis. The effects of experimental parameters were also studied. The mass absorption coefficients of the laboratory-generated TBs were found to be in the range of 0.8-3.0 m2 g-1 at 550 nm, with absorption Ångström exponents (AAE) between 2.7 and 3.4 (average 2.9) in the wavelength range 467-652 nm. The refractive index of TBs as derived from Mie calculations was about 1.84 - 0.21i at 550 nm. In the brown carbon continuum, these values fall closer to those of soot than to other light-absorbing species such as humic-like substances (HULIS). Considering the abundance of TBs in biomass smoke and the global magnitude of biomass burning emissions, these findings may have

  20. Fast mapping algorithm of lighting spectrum and GPS coordinates for a large area

    NASA Astrophysics Data System (ADS)

    Lin, Chih-Wei; Hsu, Ke-Fang; Hwang, Jung-Min

    2016-09-01

    In this study, we propose a fast rebuild technology for evaluating light quality in large areas. Outdoor light quality, which is measured by illuminance uniformity and the color rendering index, is difficult to conform after improvement. We develop an algorithm for a lighting quality mapping system and coordinates using a micro spectrometer and GPS tracker integrated with a quadcopter or unmanned aerial vehicle. After cruising at a constant altitude, lighting quality data is transmitted and immediately mapped to evaluate the light quality in a large area.

  1. Energetic-particle-driven instabilities and induced fast-ion transport in a reversed field pinch

    SciTech Connect

    Lin, L.; Brower, D. L.; Ding, W. X.; Anderson, J. K.; Capecchi, W.; Eilerman, S.; Forest, C. B.; Koliner, J. J.; Nornberg, M. D.; Reusch, J.; Sarff, J. S.; Liu, D.

    2014-05-15

    Multiple bursty energetic-particle (EP) driven modes with fishbone-like structure are observed during 1 MW tangential neutral-beam injection in a reversed field pinch (RFP) device. The distinguishing features of the RFP, including large magnetic shear (tending to add stability) and weak toroidal magnetic field (leading to stronger drive), provide a complementary environment to tokamak and stellarator configurations for exploring basic understanding of EP instabilities. Detailed measurements of the EP mode characteristics and temporal-spatial dynamics reveal their influence on fast ion transport. Density fluctuations exhibit a dynamically evolving, inboard-outboard asymmetric spatial structure that peaks in the core where fast ions reside. The measured mode frequencies are close to the computed shear Alfvén frequency, a feature consistent with continuum modes destabilized by strong drive. The frequency pattern of the dominant mode depends on the fast-ion species. Multiple frequencies occur with deuterium fast ions compared to single frequency for hydrogen fast ions. Furthermore, as the safety factor (q) decreases, the toroidal mode number of the dominant EP mode transits from n=5 to n=6 while retaining the same poloidal mode number m=1. The transition occurs when the m=1, n=5 wave-particle resonance condition cannot be satisfied as the fast-ion safety factor (q{sub fi}) decreases. The fast-ion temporal dynamics, measured by a neutral particle analyzer, resemble a classical predator-prey relaxation oscillation. It contains a slow-growth phase arising from the beam fueling followed by a rapid drop when the EP modes peak, indicating that the fluctuation-induced transport maintains a stiff fast-ion density profile. The inferred transport rate is strongly enhanced with the onset of multiple EP modes.

  2. Energetic-particle-driven instabilities and induced fast-ion transport in a reversed field pincha)

    NASA Astrophysics Data System (ADS)

    Lin, L.; Anderson, J. K.; Brower, D. L.; Capecchi, W.; Ding, W. X.; Eilerman, S.; Forest, C. B.; Koliner, J. J.; Liu, D.; Nornberg, M. D.; Reusch, J.; Sarff, J. S.

    2014-05-01

    Multiple bursty energetic-particle (EP) driven modes with fishbone-like structure are observed during 1 MW tangential neutral-beam injection in a reversed field pinch (RFP) device. The distinguishing features of the RFP, including large magnetic shear (tending to add stability) and weak toroidal magnetic field (leading to stronger drive), provide a complementary environment to tokamak and stellarator configurations for exploring basic understanding of EP instabilities. Detailed measurements of the EP mode characteristics and temporal-spatial dynamics reveal their influence on fast ion transport. Density fluctuations exhibit a dynamically evolving, inboard-outboard asymmetric spatial structure that peaks in the core where fast ions reside. The measured mode frequencies are close to the computed shear Alfvén frequency, a feature consistent with continuum modes destabilized by strong drive. The frequency pattern of the dominant mode depends on the fast-ion species. Multiple frequencies occur with deuterium fast ions compared to single frequency for hydrogen fast ions. Furthermore, as the safety factor (q) decreases, the toroidal mode number of the dominant EP mode transits from n =5 to n =6 while retaining the same poloidal mode number m =1. The transition occurs when the m =1, n =5 wave-particle resonance condition cannot be satisfied as the fast-ion safety factor (qfi) decreases. The fast-ion temporal dynamics, measured by a neutral particle analyzer, resemble a classical predator-prey relaxation oscillation. It contains a slow-growth phase arising from the beam fueling followed by a rapid drop when the EP modes peak, indicating that the fluctuation-induced transport maintains a stiff fast-ion density profile. The inferred transport rate is strongly enhanced with the onset of multiple EP modes.

  3. Significant Attenuation of Lightly Damped Resonances Using Particle Dampers

    NASA Technical Reports Server (NTRS)

    Smith, Andrew; LaVerde, Bruce; Hunt, Ron; Knight, Joseph Brent

    2015-01-01

    When equipment designs must perform in a broad band vibration environment it can be difficult to avoid resonances that affect life and performance. This is especially true when an organization seeks to employ an asset from a heritage design in a new, more demanding vibration environment. Particle dampers may be used to provide significant attenuation of lightly damped resonances to assist with such a deployment of assets by including only a very minor set of modifications. This solution may be easier to implement than more traditional attenuation schemes. Furthermore, the cost in additional weight to the equipment can be very small. Complexity may also be kept to a minimum, because the particle dampers do not require tuning. Attenuating the vibratory response with particle dampers may therefore be simpler (in a set it and forget it kind of way) than tuned mass dampers. The paper will illustrate the use of an "equivalent resonance test jig" that can assist designers in verifying the potential resonance attenuation that may be available to them during the early trade stages of the design. An approach is suggested for transforming observed attenuation in the jig to estimated performance in the actual service design. KEY WORDS: Particle Damper, Performance in Vibration Environment, Damping, Resonance, Attenuation, Mitigation of Vibration Response, Response Estimate, Response Verification.

  4. Light scattering by lunar-like particle size distributions

    NASA Technical Reports Server (NTRS)

    Goguen, Jay D.

    1991-01-01

    A fundamental input to models of light scattering from planetary regoliths is the mean phase function of the regolith particles. Using the known size distribution for typical lunar soils, the mean phase function and mean linear polarization for a regolith volume element of spherical particles of any composition were calculated from Mie theory. The two contour plots given here summarize the changes in the mean phase function and linear polarization with changes in the real part of the complex index of refraction, n - ik, for k equals 0.01, the visible wavelength 0.55 micrometers, and the particle size distribution of the typical mature lunar soil 72141. A second figure is a similar index-phase surface, except with k equals 0.1. The index-phase surfaces from this survey are a first order description of scattering by lunar-like regoliths of spherical particles of arbitrary composition. They form the basis of functions that span a large range of parameter-space.

  5. Lamb shift contribution of very light charged particles

    SciTech Connect

    Glueck, M.; Rakshit, S.; Reya, E.

    2007-11-01

    The leading-order vacuum polarization contribution of very light millicharged fermions and scalar (spin-0) particles with charge {epsilon}e and mass {mu} to the Lamb shift of the hydrogen atom is shown to imply universal, i.e. {mu}-independent, upper bounds on {epsilon}: {epsilon} < or approx. 10{sup -4} for {mu} < or approx. 1 keV in the case of fermions, and for scalars this bound is increased by a factor of 2. This is in contrast to expectations based on the commonly used approximation to the Uehling potential relevant only for conventionally large fermion (and scalar) masses.

  6. Fast and reliable techniques for using Racah's algebra in many-particle physics

    NASA Astrophysics Data System (ADS)

    Fritzsche, S.; Fricke, B.; Gaigalas, G.; Jacob, T.; Tomaselli, M.

    2002-08-01

    During recent years, the RACAH program has been found to be a fast and reliable alternative for simplifying typical expressions from the theory of angular momenta. Here, we review the recent developments for this package and illustrate how it can be applied to the study of many-particle systems.

  7. Fast transport in phase space due to nonlinear wave-particle interaction in the radiation belts.

    NASA Astrophysics Data System (ADS)

    Artemyev, Anton; Vasiliev, Alexii; Mourenas, Didier; Agapitov, Oleksiy; Krasnoselskikh, Vladimir; Boscher, Daniel; Rolland, Guy

    2014-05-01

    We present an analytical, simplified formulation accounting for the fast transport of particles in phase space, in the presence of nonlinear wave-particle resonant interactions in an inhomogeneous magnetic field representative of the radiation belts. We show that the general approach for the description of the evolution of the particle velocity distribution based on the Fokker-Plank equation can be modified to consider the process of nonlinear wave-particle interaction, including particle trapping. Such a modification consists in one additional operator describing fast particle jumps in phase space. The proposed approach is illustrated by considering the acceleration of relativistic electrons by strongly oblique whistler waves. We determine the typical variation of electron phase-density due to nonlinear wave-particle interaction and compare this variation with pitch-angle/energy diffusion due to quasi-linear electron scattering. We show that relation between nonlinear and quasi-linear effects is controlled by the distribution of wave-amplitudes. When this distribution has a heavy tail, nonlinear effects can become dominant in the formation of the electron energy distribution.

  8. Nonthermal nuclear reactions induced by fast α particles in the solar core

    NASA Astrophysics Data System (ADS)

    Voronchev, Victor T.

    2015-02-01

    Nonthermal nuclear effects triggered in the solar carbon-nitrogen-oxygen (CNO) cycle by fast α particles—products of the p p chain reactions—are examined. The main attention is paid to 8.674-MeV α particles generated in the 7Li(p ,α ) α reaction. Nonthermal characteristics of these α particles and their influence on some nuclear processes are determined. It is found that the α -particle effective temperature is at a level of 1.1 MeV and exceeds the solar core temperature by 3 orders of magnitude. These fast particles are able to significantly enhance some endoergic (α ,p ) reactions neglected in standard solar model calculations. In particular, they can substantially affect the balance of the p +17O⇄α +14N reactions due to an appreciable increase of the reverse reaction rate. It is shown that in the region R =0.08 -0.25 R⊙ the reverse α +14N reaction can block the forward p +17O reaction, thus preventing closing of the CNO-II cycle, and increase the 17O abundance by a factor of 2-155 depending on R . This indicates that the fast α particles produced in the p p cycle can distort running of the CNO cycle, making it essentially different in the inner and outer core regions.

  9. Particle sizing by weighted measurements of scattered light

    NASA Technical Reports Server (NTRS)

    Buchele, Donald R.

    1988-01-01

    A description is given of a measurement method, applicable to a poly-dispersion of particles, in which the intensity of scattered light at any angle is weighted by a factor proportional to that angle. Determination is then made of four angles at which the weighted intensity is four fractions of the maximum intensity. These yield four characteristic diameters, i.e., the diameters of the volume/area mean (D sub 32 the Sauter mean) and the volume/diameter mean (D sub 31); the diameters at cumulative volume fractions of 0.5 (D sub v0.5 the volume median) and 0.75 (D sub v0.75). They also yield the volume dispersion of diameters. Mie scattering computations show that an average diameter less than three micrometers cannot be accurately measured. The results are relatively insensitive to extraneous background light and to the nature of the diameter distribution. Also described is an experimental method of verifying the conclusions by using two microscopic slides coated with polystyrene microspheres to simulate the particles and the background.

  10. Energetic-Particle-Driven Instabilities and Their Effect on Fast Ions in a Reversed Field Pinch

    NASA Astrophysics Data System (ADS)

    Lin, L.; Ding, W. X.; Brower, D. L.; Koliner, J. J.; Eilerman, S.; Reusch, J.; Anderson, J. K.; Almagri, A. F.; Chapman, B. E.; Nornberg, M. D.; Sarff, J. S.; Waksman, J.; Liu, D.

    2012-10-01

    During 1 MW tangential neutral-beam injection (NBI) into the MST reversed field pinch, multiple, bursty instabilities (n=5, 4 and -1) are detected by various fluctuation diagnostics. The spatial structure of associated density fluctuations peaks near the core where fast ions reside. Significant bicoherence among them is measured, indicating nonlinear three-wave coupling. These instabilities are also observed by a laser-based Faraday-rotation diagnostic, containing critical information on the internal magnetic field fluctuations. A tangential-view high-energy neutral particle analyzer (NPA) is used to study the fast-ion population. The measured NPA signal decreases by 15% following NBI-driven instabilities, indicating fluctuation-induced fast-ion transport. The NBI also reduces the amplitude of the innermost-resonant tearing mode by up to 65%. This mode-suppression is lessened following the NBI-driven bursts, consistent with fast ion loss/redistribution weakening the suppression effect.

  11. Characterization of Mixed Polypeptide Colloidal Particles by Light Scattering

    NASA Astrophysics Data System (ADS)

    Shuman, Hannah E.; Gaeckle, Grace K.; Gavin, John; Holland, Nolan B.; Streletzky, Kiril A.

    2014-03-01

    Temperature-dependent polymer surfactants have been developed by connecting three elastin-like polypeptide (ELP) chains to a charged protein domain (foldon), forming a three-armed star polymer. At low temperatures the polymer is soluble, while at higher temperatures it forms micelles. The behavior of mixtures of the three-armed star ELP (E20-Foldon) and H40-Linear ELP chains was analyzed under different salt and protein concentrations and various foldon to linear ELP ratio using Depolarized Dynamic Light Scattering. It was expected that under certain conditions the pure E20-Foldon would form spherical micelles, which upon adding the linear ELP would change in size and possibly shape. The pure E20-Foldon indeed formed largely spherical micelles with Rh of 10-20nm in solutions with 15-100mM salt and protein concentration between 10 μM and 100 μM. For the mixtures of 50 μM E20-Foldon and varying concentrations of H40-Linear in 25mM of salt, it was discovered that low and high H40-Linear concentration (4 μM and 50 μM) had only one transition. For the mixtures with of 10 and 25 μM of H40-Linear the two distinct transition temperatures were observed by spectrophotometry. The first transition corresponded to significantly elongated diffusive particles of apparent Rh of 30-50nm, while the second transition corresponded to slightly anisotropic diffusive particles with apparent Rh of about 20nm. At all H40-Linear concentrations studied, diffusive particles were seen above the second transition. Their radius and ability to depolarize light increased with the increase of H40-Linear concentration.

  12. Light Particle Solution to the Cosmic Lithium Problem.

    PubMed

    Goudelis, Andreas; Pospelov, Maxim; Pradler, Josef

    2016-05-27

    We point out that the cosmological abundance of ^{7}Li can be reduced down to observed values if during its formation, big bang nucleosynthesis is modified by the presence of light electrically neutral particles X that have substantial interactions with nucleons. We find that the lithium problem can be solved without affecting the precisely measured abundances of deuterium and helium if the following conditions are satisfied: the mass (energy) and lifetimes of such particles are bounded by 1.6  MeV≤m_{X}(E_{X})≤20  MeV and few100s≲τ_{X}≲10^{4}  s, and the abundance times the absorption cross section by either deuterium or ^{7}Be are comparable to the Hubble rate, n_{X}σ_{abs}v∼H, at the time of ^{7}Be formation. We include X-initiated reactions into the primordial nucleosynthesis framework, observe that it leads to a substantial reduction of the freeze-out abundances of ^{7}Li+^{7}Be, and find specific model realizations of this scenario. Concentrating on the axionlike-particle case, X=a, we show that all these conditions can be satisfied if the coupling to d quarks is in the range of f_{d}^{-1}∼TeV^{-1}, which can be probed at intensity frontier experiments.

  13. Study of wave-particle interaction between fast Magnetosonic and energetic electrons based on numerical simulation

    NASA Astrophysics Data System (ADS)

    Fu, S.

    2015-12-01

    There are many energetic electrons in the radiation belt of Earth. When the geomagnetic activity becomes stronger, the energy flux of energetic electrons will increase to more than ten times in the outer radiation belt, therefore it is very important to study how the energetic electrons generate and the lifetime of energetic electrons for space weather research. The acceleration of electrons in radiation belt is mainly depending on wave-particle interaction: the whistler mode chorus is the main driver for local acceleration mechanism, which could accelerate and loss energetic electrons; the geomagnetic pulsation ULF wave will cause energetic electron inward radial diffusion which will charge the electrons; recently observation results show us that the fast magnetosonic waves may also accelerate energetic electrons. For the reason that we try to study the wave-particle interaction between fast Magnetosonic and energetic electrons based on numerical simulation, in which the most important past is at the storm time the combination of highly warped Earth magnetic field and fast magnetosonic wave field will be applied for the electromagnetic environment of moving test particles. The energy, pitch angle and cross diffusion coefficients will be calculated respectively in this simulation to study how the electrons receive energy from fast magnetosonic wave. The diffusion coefficients within different dipole Earth magnetic field and non-dipole storm magnetic field are compared, while dynamics of electrons at selected initial energys are shown in our study.

  14. Analysis of Alfven Eigenmodes destabilization by fast particles in Large Helical Device

    NASA Astrophysics Data System (ADS)

    Varela, Jacobo; Spong, Donald; Garcia, Luis

    2016-10-01

    Fast particle populations in nuclear fusion experiments can destabilize Alfven Eigenmodes through inverse Landau damping and couplings with gap modes in the shear Alfven continua. We use the reduced MHD equations to describe the linear evolution of the poloidal flux and the toroidal component of the vorticity in a full 3D system, coupled with equations of density and parallel velocity moments for the energetic particles. We add the Landau damping and resonant destabilization effects by a closure relation. We apply this model to study the Alfven modes stability in Large Helical Device (LHD) equilibria for inward configurations, performing a parametric analysis along a range of realistic values of fast particle β (βfp), ratios of thermal/Alfven velocities (Vth/Vao), magnetic Lundquist numbers (S) and dominant toroidal (n) modes families. The n = 1 and n =2 toroidal families show the largest growth rates for parameters closer to a real LHD scenario (S = 5E6, βfp = 0.02 and Vth/Vao = 0.5), particularly the modes n/m = 1/2 and 2/4 located the inner and middle plasma (ρ = 0.25 - 0.5 with ρ the normalized minor radius). The n = 3 and n = 4 toroidal families are weakly perturbed by fast particles.

  15. [Particle Size and Number Density Online Analysis for Particle Suspension with Polarization-Differentiation Elastic Light Scattering Spectroscopy].

    PubMed

    Chen, Wei-kang; Fang, Hui

    2016-03-01

    The basic principle of polarization-differentiation elastic light scattering spectroscopy based techniques is that under the linear polarized light incidence, the singlely scattered light from the superficial biological tissue and diffusively scattered light from the deep tissue can be separated according to the difference of polarization characteristics. The novel point of the paper is to apply this method to the detection of particle suspension and, to realize the simultaneous measurement of its particle size and number density in its natural status. We design and build a coaxial cage optical system, and measure the backscatter signal at a specified angle from a polystyrene microsphere suspension. By controlling the polarization direction of incident light with a linear polarizer and adjusting the polarization direction of collected light with another linear polarizer, we obtain the parallel polarized elastic light scattering spectrum and cross polarized elastic light scattering spectrum. The difference between the two is the differential polarized elastic light scattering spectrum which include only the single scattering information of the particles. We thus compare this spectrum to the Mie scattering calculation and extract the particle size. We then also analyze the cross polarized elastic light scattering spectrum by applying the particle size already extracted. The analysis is based on the approximate expressions taking account of light diffusing, from which we are able to obtain the number density of the particle suspension. We compare our experimental outcomes with the manufacturer-provided values and further analyze the influence of the particle diameter standard deviation on the number density extraction, by which we finally verify the experimental method. The potential applications of the method include the on-line particle quality monitoring for particle manufacture as well as the fat and protein density detection of milk products.

  16. Energetic-particle-driven instabilities and induced fast-ion transport in a reversed field pinch

    NASA Astrophysics Data System (ADS)

    Lin, Liang

    2013-10-01

    Multiple bursty energetic-particle (EP) modes with fishbone-like structures are observed during 1 MW tangential neutral-beam injection into MST reversed field pinch (RFP) plasmas. The distinguishing features of the RFP, including large magnetic shear (tending to add stability) and weak toroidal magnetic field (leading to large fast ion beta and stronger drive), provide a complementary environment to tokamak and stellarator configurations for exploring basic understanding of these instabilities. Detailed measurements of the EP mode characteristics and temporal-spatial dynamics reveal their influence on fast ion transport and interaction with global tearing modes. Internal magnetic field fluctuations associated with the EP modes are directly observed for the first time by Faraday-effect polarimetry (frequency ~ 90 kHz and amplitude ~ 2 G). Simultaneously measured density fluctuations exhibit a dynamically evolving and asymmetric spatial structure that peaks near the core where fast ions reside and shifts outward as the instability evolves. Furthermore, the EP mode frequencies appear at ~k∥VA , consistent with continuum modes destabilized by strong drive. The fast-ion temporal dynamics, measured by a neutral particle analyzer, resemble a classical predator-prey relaxation oscillation. It contains a slow-growing phase arising from the beam fueling followed by a rapid drop (~ 15 %) when the EP modes peak, indicating the fluctuation-induced transport maintains a stiff fast-ion density profile. The inferred transport rate is strongly enhanced (× 2) with the onset of multiple nonlinearly-interacting EP modes. The fast ions also impact global tearing modes, reducing their amplitudes by up to 65%. This mode reduction is lessened following the EP-bursts, further evidence for fast ion redistribution that weakens the suppression mechanism. Possible tearing mode suppression mechanisms will be discussed. Work supported by US DoE.

  17. Variational principle for scattering of light by dielectric particles

    NASA Technical Reports Server (NTRS)

    Yung, Y. L.

    1978-01-01

    Consideration is given to the work of Purcell and Pennypacker (1973) where a dielectric particle is taken to be an aggregate of N polarizable elements mounted on a cubic lattice. The simultaneous equations which result from the scattering problem are presented. This theory has been discussed in the case of nonspherical and inhomogeneous objects whose dimensions are smaller than or comparable to the wavelength of incident light. A more precise numerical treatment is derived for further progress. The variational principle is invoked and the practical limit for the current version of the scheme is a dipole array on the order of 10,000 atoms. Limits to the scattering parameter due to the phase difference between neighboring atoms are discussed.

  18. The linac coherent light source single particle imaging road map

    PubMed Central

    Aquila, A.; Barty, A.; Bostedt, C.; Boutet, S.; Carini, G.; dePonte, D.; Drell, P.; Doniach, S.; Downing, K. H.; Earnest, T.; Elmlund, H.; Elser, V.; Gühr, M.; Hajdu, J.; Hastings, J.; Hau-Riege, S. P.; Huang, Z.; Lattman, E. E.; Maia, F. R. N. C.; Marchesini, S.; Ourmazd, A.; Pellegrini, C.; Santra, R.; Schlichting, I.; Schroer, C.; Spence, J. C. H.; Vartanyants, I. A.; Wakatsuki, S.; Weis, W. I.; Williams, G. J.

    2015-01-01

    Intense femtosecond x-ray pulses from free-electron laser sources allow the imaging of individual particles in a single shot. Early experiments at the Linac Coherent Light Source (LCLS) have led to rapid progress in the field and, so far, coherent diffractive images have been recorded from biological specimens, aerosols, and quantum systems with a few-tens-of-nanometers resolution. In March 2014, LCLS held a workshop to discuss the scientific and technical challenges for reaching the ultimate goal of atomic resolution with single-shot coherent diffractive imaging. This paper summarizes the workshop findings and presents the roadmap toward reaching atomic resolution, 3D imaging at free-electron laser sources. PMID:26798801

  19. The linac coherent light source single particle imaging road map

    DOE PAGES

    Aquila, A.; Barty, A.; Bostedt, C.; ...

    2015-07-01

    Intense femtosecond x-ray pulses from free-electron laser sources allow the imaging of individual particles in a single shot. Early experiments at the Linac Coherent Light Source (LCLS) have led to rapid progress in the field and, so far, coherent diffractive images have been recorded from biological specimens, aerosols, and quantum systems with a few-tens-of-nanometers resolution. In March 2014, LCLS held a workshop to discuss the scientific and technical challenges for reaching the ultimate goal of atomic resolution with single-shot coherent diffractive imaging. This paper summarizes the workshop findings and presents the roadmap toward reaching atomic resolution, 3D imaging at free-electronmore » laser sources.« less

  20. The linac coherent light source single particle imaging road map

    SciTech Connect

    Aquila, A.; Barty, A.; Bostedt, C.; Boutet, S.; Carini, G.; dePonte, D.; Drell, P.; Doniach, S.; Downing, K. H.; Earnest, T.; Elmlund, H.; Elser, V.; Gühr, M.; Hajdu, J.; Hastings, J.; Hau-Riege, S. P.; Huang, Z.; Lattman, E. E.; Maia, F. R.N.C.; Marchesini, S.; Ourmazd, A.; Pellegrini, C.; Schlichting, I.; Schroer, C.; Spence, J. C. H.; Vartanyants, I. A.; Wakatsuki, S.; Weis, W. I.; Williams, G. J.

    2015-07-01

    Intense femtosecond x-ray pulses from free-electron laser sources allow the imaging of individual particles in a single shot. Early experiments at the Linac Coherent Light Source (LCLS) have led to rapid progress in the field and, so far, coherent diffractive images have been recorded from biological specimens, aerosols, and quantum systems with a few-tens-of-nanometers resolution. In March 2014, LCLS held a workshop to discuss the scientific and technical challenges for reaching the ultimate goal of atomic resolution with single-shot coherent diffractive imaging. This paper summarizes the workshop findings and presents the roadmap toward reaching atomic resolution, 3D imaging at free-electron laser sources.

  1. Performance of Advanced Light Source particle beam diagnostics

    SciTech Connect

    Hinkson, J.

    1993-05-01

    The Advanced Light Source (ALS), a third-generation synchrotron radiation facility, is complete. The particle beam diagnostics have been installed and tested. The beam injection systems have been running for two years. We have performance data on beam position monitors, beam intensity monitors, scintillators, beam collimators, a 50 {Omega} Faraday cup, and broad-band striplines and kickers used in the linac, transport lines, and the booster synchrotron. The single-turn monitoring capability of the booster beam position monitoring system has been particularly useful for studying beam dynamics. Beam diagnostics for the storage ring are being commissioned. In this paper we describe each instrument, show its performance, and outline how the instruments are controlled and their output data displayed.

  2. Impacts of fast meteoroids and the separation of dust particles from the surface of the Moon

    NASA Astrophysics Data System (ADS)

    Popel, S. I.; Golub', A. P.; Lisin, E. A.; Izvekova, Yu. N.; Atamaniuk, B.; Dol'nikov, G. G.; Zakharov, A. V.; Zelenyi, L. M.

    2016-05-01

    The possibility of the separation of dust particles owing to impacts of micrometeoroids on the surface of the Moon has been discussed. It has been shown that this effect is significant and should be taken into account when determining the number of particles rising over the surface of the Moon at the formation of a plasma-dust system. The average number of regolith particles leaving the surface of the Moon owing to the impacts of fast meteoroids has been determined for various altitudes over the Moon. The size distribution function of particles leaving the surface of the Moon because of impacts of meteoroids has been determined. It has been shown that impacts of meteoroids constitute an important source of dust microparticles in the plasma-dust system over the surface of the Moon.

  3. Report of the Workshop on Light Particle-Induced Reactions

    NASA Astrophysics Data System (ADS)

    The study meeting on light particle (mass number = 3 - 11) induced reaction was held for three days from 5-7 Dec. 1991 at the Research Center for Nuclear Physics, Osaka University. This book records the reports based on the lectures presented at the meeting. In the new facility of the RCNP, the experiment on the nuclear reaction using 400 MeV polarized protons and 200 MeV polarized deuterons is about to begin. When the acceleration of polarized He-3 beam which is being developed becomes feasible, by combining it with the high resolution spectrometer GRAND RAIDEN, it is expected that the unique, high accuracy research using the polarized He-3 having intermediate energy (540 MeV) becomes possible. At this time, by focusing attention to what new physics is developed by the nuclear reaction induced by the composite particles having the intermediate energy of mass number 3 - 11, this study meeting was planned and held. As the result, 29 lectures collected were to cover wide fields, and active discussion was carried out.

  4. ReaDDyMM: Fast Interacting Particle Reaction-Diffusion Simulations Using Graphical Processing Units

    PubMed Central

    Biedermann, Johann; Ullrich, Alexander; Schöneberg, Johannes; Noé, Frank

    2015-01-01

    ReaDDy is a modular particle simulation package combining off-lattice reaction kinetics with arbitrary particle interaction forces. Here we present a graphical processing unit implementation of ReaDDy that employs the fast multiplatform molecular dynamics package OpenMM. A speedup of up to two orders of magnitude is demonstrated, giving us access to timescales of multiple seconds on single graphical processing units. This opens up the possibility of simulating cellular signal transduction events while resolving all protein copies. PMID:25650912

  5. Fast Particle Effects on the Internal Kink, Fishbone and Alfven Modes

    SciTech Connect

    N.N. Gorelenkov; S. Bernabei; C.Z. Cheng; G.Y. Fu; K. Hill; S. Kaye; G.J. Kramer; Y. Kusama; K. Shinohara; R. Nazikian; T. Ozeki; W. Park

    2000-11-15

    The issues of linear stability of low frequency perturbative and nonperturbative modes in advanced tokamak regimes are addressed based on recent developments in theory, computational methods, and progress in experiments. Perturbative codes NOVA and ORBIT are used to calculate the effects of TAEs on fast particle population in spherical tokamak NSTX. Nonperturbative analysis of chirping frequency modes in experiments on TFTR and JT-60U is presented using the kinetic code HINST, which identified such modes as a separate branch of Alfven modes - resonance TAE (R-TAE). Internal kink mode stability in the presence of fast particles is studied using the NOVA code and hybrid kinetic-MHD nonlinear code M3D.

  6. Fast superposition T-matrix solution for clusters with arbitrarily-shaped constituent particles

    NASA Astrophysics Data System (ADS)

    Markkanen, Johannes; Yuffa, Alex J.

    2017-03-01

    A fast superposition T-matrix solution is formulated for electromagnetic scattering by a collection of arbitrarily-shaped inhomogeneous particles. The T-matrices for individual constituents are computed by expanding the Green's dyadic in the spherical vector wave functions and formulating a volume integral equation, where the equivalent electric current is the unknown and the spherical vector wave functions are treated as excitations. Furthermore, the volume integral equation and the superposition T-matrix are accelerated by the precorrected-FFT algorithm and the fast multipole algorithm, respectively. The approach allows for an efficient scattering analysis of the clusters and aggregates consisting of a large number of arbitrarily-shaped inhomogeneous particles.

  7. Landau Damping of Transverse Waves in the Exosphere by Fast Particle Fluxes

    NASA Technical Reports Server (NTRS)

    Tidman, D. A.; Jaggi, R. K.

    1962-01-01

    We have investigated the Landau damping of transverse waves propagating in the thermal exospheric plasma, by fast particle fluxes which also exist in these regions. The most intense non-thermal fluxes so far detected are those of the auroral producing electrons and protons measured by McIlwain. We find that these fluxes may considerably damp the propagation of whistler modes through some regions. The damping of hydromagnetic waves in the exosphere by this mechanism is negligible.

  8. Nonlinear interaction of fast particles with Alfven waves in toroidal plasmas

    SciTech Connect

    Candy, J.; Borba, D.; Huysmans, G.T.A.; Kerner, W.; Berk, H.L.

    1996-12-17

    A numerical algorithm to study the nonlinear, resonant interaction of fast particles with Alfven waves in tokamak geometry has been developed. The scope of the formalism is wide enough to describe the nonlinear evolution of fishbone modes, toroidicity-induced Alfven eigenmodes and ellipticity-induced Alfven eigenmodes, driven by both passing and trapped fast ions. When the instability is sufficiently weak, it is known that the wave-particle trapping nonlinearity will lead to mode saturation before wave-wave nonlinearities are appreciable. The spectrum of linear modes can thus be calculated using a magnetohydrodynamic normal-mode code, then nonlinearly evolved in time in an efficient way according to a two-time-scale Lagrangian dynamical wave model. The fast particle kinetic equation, including the effect of orbit nonlinearity arising from the mode perturbation, is simultaneously solved of the deviation, {delta}f = f {minus} f{sub 0}, from an initial analytic distribution f{sub 0}. High statistical resolution allows linear growth rates, frequency shifts, resonance broadening effects, and nonlinear saturation to be calculated quickly and precisely. The results have been applied to an ITER instability scenario. Results show that weakly-damped core-localized modes alone cause negligible alpha transport in ITER-like plasmas--even with growth rates one order of magnitude higher than expected values. However, the possibility of significant transport in reactor-type plasmas due to weakly unstable global modes remains an open question.

  9. Fast Pyrolysis of Wood for Biofuels: Spatiotemporally Resolved Diffuse Reflectance In situ Spectroscopy of Particles.

    PubMed

    Paulsen, Alex D; Hough, Blake R; Williams, C Luke; Teixeira, Andrew R; Schwartz, Daniel T; Pfaendtner, Jim; Dauenhauer, Paul J

    2014-02-20

    Fast pyrolysis of woody biomass is a promising process capable of producing renewable transportation fuels to replace gasoline, diesel, and chemicals currently derived from nonrenewable sources. However, biomass pyrolysis is not yet economically viable and requires significant optimization before it can contribute to the existing oil-based transportation system. One method of optimization uses detailed kinetic models for predicting the products of biomass fast pyrolysis, which serve as the basis for the design of pyrolysis reactors capable of producing the highest value products. The goal of this work is to improve upon current pyrolysis models, usually derived from experiments with low heating rates and temperatures, by developing models that account for both transport and pyrolysis decomposition kinetics at high heating rates and high temperatures (>400 °C). A new experimental technique is proposed herein: spatiotemporally resolved diffuse reflectance in situ spectroscopy of particles (STR-DRiSP), which is capable of measuring biomass composition during fast pyrolysis with high spatial (10 μm) and temporal (1 ms) resolution. Compositional data were compared with a comprehensive 2D single-particle model, which incorporated a multistep, semiglobal reaction mechanism, prescribed particle shrinkage, and thermophysical properties that varied with temperature, composition, and orientation. The STR-DRiSP technique can be used to determine the transport-limited kinetic parameters of biomass decomposition for a wide variety of biomass feedstocks.

  10. Gyrokinetic Particle Simulation of Fast Electron Driven Beta-induced Alfven Eigenmodes

    NASA Astrophysics Data System (ADS)

    Zhang, Wenlu; Cheng, Junyi; Lin, Zhihong

    2016-10-01

    The fast electron driven beta induced Alfven eigenmode (e-BAE) has been routinely observed in HL-2A tokamak. We study e-BAE for the first time using global gyrokinetic GTC simulation, where the fast electrons are described by the drift kinetic model. Frequency chirping is observed in nonlinear simulations in the absence of sources and sinks, which provide a new nonlinear paradigm beyond the standard ``bump-on-tail'' model. For weakly driven case, nonlinear frequency is observed to be in phase with particle flux, and nonlinear mode structure is almost the same as linear stage. In the strongly driven case, BAAE is also unstable and co-exists with BAE after the BAE saturation. Analysis of nonlinear wave-particle interactions shows that the frequency chirping is induced by the nonlinear evolution of the coherent structures in the fast electron phase space, where the dynamics of the coherent structure is controlled by the formation and destruction of phrase space islands in the canonical variables. Zonal fields are found to affect wave-particle resonance in the nonlinear e-BAE simulations.

  11. A fast multispectral light synthesiser based on LEDs and a diffraction grating

    PubMed Central

    Belušič, Gregor; Ilić, Marko; Meglič, Andrej; Pirih, Primož

    2016-01-01

    Optical experiments often require fast-switching light sources with adjustable bandwidths and intensities. We constructed a wavelength combiner based on a reflective planar diffraction grating and light emitting diodes with emission peaks from 350 to 630 nm that were positioned at the angles corresponding to the first diffraction order of the reversed beam. The combined output beam was launched into a fibre. The spacing between 22 equally wide spectral bands was about 15 nm. The time resolution of the pulse-width modulation drivers was 1 ms. The source was validated with a fast intracellular measurement of the spectral sensitivity of blowfly photoreceptors. In hyperspectral imaging of Xenopus skin circulation, the wavelength resolution was adequate to resolve haemoglobin absorption spectra. The device contains no moving parts, has low stray light and is intrinsically capable of multi-band output. Possible applications include visual physiology, biomedical optics, microscopy and spectroscopy. PMID:27558155

  12. A fast multispectral light synthesiser based on LEDs and a diffraction grating

    NASA Astrophysics Data System (ADS)

    Belušič, Gregor; Ilić, Marko; Meglič, Andrej; Pirih, Primož

    2016-08-01

    Optical experiments often require fast-switching light sources with adjustable bandwidths and intensities. We constructed a wavelength combiner based on a reflective planar diffraction grating and light emitting diodes with emission peaks from 350 to 630 nm that were positioned at the angles corresponding to the first diffraction order of the reversed beam. The combined output beam was launched into a fibre. The spacing between 22 equally wide spectral bands was about 15 nm. The time resolution of the pulse-width modulation drivers was 1 ms. The source was validated with a fast intracellular measurement of the spectral sensitivity of blowfly photoreceptors. In hyperspectral imaging of Xenopus skin circulation, the wavelength resolution was adequate to resolve haemoglobin absorption spectra. The device contains no moving parts, has low stray light and is intrinsically capable of multi-band output. Possible applications include visual physiology, biomedical optics, microscopy and spectroscopy.

  13. Analysis and Implementation of Particle-to-Particle (P2P) Graphics Processor Unit (GPU) Kernel for Black-Box Adaptive Fast Multipole Method

    DTIC Science & Technology

    2015-06-01

    ARL-TR-7315 ● JUNE 2015 US Army Research Laboratory Analysis and Implementation of Particle-to- Particle (P2P) Graphics Processor ...Particle-to- Particle (P2P) Graphics Processor Unit (GPU) Kernel for Black-Box Adaptive Fast Multipole Method by Richard H Haney and Dale Shires...reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information

  14. Determination of the refractive index of microparticles by utilizing light dispersion properties of the particle and an immersion liquid.

    PubMed

    Niskanen, I; Räty, J; Peiponen, K E

    2013-10-15

    The knowledge of the refractive index of a particle is important in sensing and imaging applications, e.g., in biology, medicine and process industry. The refractive index of tiny solid particles such as microsize particles can be determined by the so-called liquid immersion technique. This study deals with three different types of interrogation methods to get the refractive index of a particle in a liquid matrix. These methods utilize thermo-optical properties and wavelength-dependent refractive index of the particle and the immersion liquids, as well as, the classical method using a set of in advance prepared set of immersion liquids with different refractive indices. The emphasis is on a method to get especially the wavelength-dependent refractive index of microparticles and exploiting different wavelength-dependences of immersion liquid and a solid particle because identification of a particle is more reliable if the refractive index of the particle is known at several wavelengths. In this study glycerol-water mixtures served as immersion liquids to obtain the refractive index of CaF2 at several discrete wavelengths in the spectral range 200-500 nm. The idea is to find the maximum value of light transmission of suspension by scanning the wavelength of a commercial spectrophotometer. The light dispersion-based method is suggested as a relatively easy, economic and fast method to determine the refractive index of a particle by a spectrophotometer at several wavelengths of light. The accuracy of the detection of the refractive index is suggested to be better than ± 0.005 refractive index units.

  15. Particle sizing by measurement of forward-scattered light at two angles

    NASA Technical Reports Server (NTRS)

    Buchele, D. R.

    1983-01-01

    Fundamental and practical limitations to particle sizing by measurement of forward scattered light are presented. Methods to minimize the limitations are described. Two types of instruments are compared.

  16. A fast sorting algorithm for a hypersonic rarefied flow particle simulation on the connection machine

    NASA Technical Reports Server (NTRS)

    Dagum, Leonardo

    1989-01-01

    The data parallel implementation of a particle simulation for hypersonic rarefied flow described by Dagum associates a single parallel data element with each particle in the simulation. The simulated space is divided into discrete regions called cells containing a variable and constantly changing number of particles. The implementation requires a global sort of the parallel data elements so as to arrange them in an order that allows immediate access to the information associated with cells in the simulation. Described here is a very fast algorithm for performing the necessary ranking of the parallel data elements. The performance of the new algorithm is compared with that of the microcoded instruction for ranking on the Connection Machine.

  17. Photonic-chip-based tunable slow and fast light via stimulated Brillouin scattering.

    PubMed

    Pant, Ravi; Byrnes, Adam; Poulton, Christopher G; Li, Enbang; Choi, Duk-Yong; Madden, Steve; Luther-Davies, Barry; Eggleton, Benjamin J

    2012-03-01

    We report the first (to our knowledge) demonstration of photonic chip based tunable slow and fast light via stimulated Brillouin scattering. Slow, fast, and negative group velocities were observed in a 7 cm long chalcogenide (As(2)S(3)) rib waveguide with a group index change ranging from ~-44 to +130, which results in a maximum delay of ~23 ns at a relatively low gain of ~23 dB. Demonstration of large tunable delays in a chip scale device opens up applications such as frequency sensing and true-time delay for a phased array antenna, where integration and delays ~10 ns are highly desirable.

  18. An Optically Stabilized Fast-Switching Light Emitting Diode as a Light Source for Functional Neuroimaging

    PubMed Central

    Wagenaar, Daniel A.

    2012-01-01

    Neuroscience research increasingly relies on optical methods for evoking neuronal activity as well as for measuring it, making bright and stable light sources critical building blocks of modern experimental setups. This paper presents a method to control the brightness of a high-power light emitting diode (LED) light source to an unprecedented level of stability. By continuously monitoring the actual light output of the LED with a photodiode and feeding the result back to the LED's driver by way of a proportional-integral controller, drift was reduced to as little as 0.007% per hour over a 12-h period, and short-term fluctuations to 0.005% root-mean-square over 10 seconds. The LED can be switched on and off completely within 100 s, a feature that is crucial when visual stimuli and light for optical recording need to be interleaved to obtain artifact-free recordings. The utility of the system is demonstrated by recording visual responses in the central nervous system of the medicinal leech Hirudo verbana using voltage-sensitive dyes. PMID:22238663

  19. An optically stabilized fast-switching light emitting diode as a light source for functional neuroimaging.

    PubMed

    Wagenaar, Daniel A

    2012-01-01

    Neuroscience research increasingly relies on optical methods for evoking neuronal activity as well as for measuring it, making bright and stable light sources critical building blocks of modern experimental setups. This paper presents a method to control the brightness of a high-power light emitting diode (LED) light source to an unprecedented level of stability. By continuously monitoring the actual light output of the LED with a photodiode and feeding the result back to the LED's driver by way of a proportional-integral controller, drift was reduced to as little as 0.007% per hour over a 12-h period, and short-term fluctuations to 0.005% root-mean-square over 10 seconds. The LED can be switched on and off completely within 100 μs, a feature that is crucial when visual stimuli and light for optical recording need to be interleaved to obtain artifact-free recordings. The utility of the system is demonstrated by recording visual responses in the central nervous system of the medicinal leech Hirudo verbana using voltage-sensitive dyes.

  20. Fast optical recording of light-flash evoked neural activation in amphibian retina

    NASA Astrophysics Data System (ADS)

    Yao, Xin-Cheng; George, John S.

    2005-08-01

    Imaging of fast intrinsic optical responses closely associated with neural activation promises important technical advantages over traditional single and multi-channel electrophysiological techniques for dynamic measurements of visual processing and early detection of eye diseases. We have developed a fast, no-moving-parts optical coherence tomography (OCT), system based on an electro-optic phase modulator, and used it to record dynamic near infrared (NIR) light scattering changes in frog retina activated by a visible light-flash. We also employed transmitted light for highly sensitive measurement and imaging of neural activation, and to optimize illumination and optical configuration. Using a photodiode detector, we routinely measured dynamic NIR transmitted optical responses in single passes. When the whole retina was illuminated by a visible light-flash, a positive peak was typically observed in transmitted light measurements. CCD image sequences disclosed larger fractional responses, in some cases exceeding 0.5% in individual pixels, and showed evidence of multiple response components with both negative- and positive-going signals with different timescales and complex but consistent spatial organization. The fast negative-going signals are highly correlated with the a-wave of the electrophysiological signals, and may reflect the activation of photoreceptors. The fast positive-going responses are related to the b-wave of the electrophysiological signals, and may result from the activation of ON bipolar cells. Slow optical responses may signal metabolic changes of retinal tissue. Our experimental results and theoretical analysis suggest that the optical responses may result from dynamic volume changes associated with neural activation, corresponding to ion and water flow across the cell membrane.

  1. Particle-in-cell Simulations Of Particle Energization From Low Mach Number Fast Mode Shocks

    NASA Astrophysics Data System (ADS)

    Ren, Chuang; Blackman, E.; Park, J.; Siller, R.; Workman, J.

    2012-05-01

    Collisionless perpendicular mangetosonic shocks relevant for termination shocks during solar flares are studied using two-dimensional particle-in-cell simulations with a reduced ion/electron mass ratio and a moving wall boundary condition. Compared to the reflection boundary condition, the moving wall method can control the shock speed and allows for smaller box sizes and longer simulation times in the study of shocks. In a purely perpendicular shock with the Alfven Mach number of 6.8 and plasma beta of 8. Electron and ion acceleration via shock drift acceleration (SDA) is observed. The modified two-stream instability due to the incoming and reflecting ions in the shock transition region is identified to be a possible turbulent dissipation mechanism. We determine the respective minimum energies required for electrons and ions to incur SDA. We derive a theoretical electron distribution via SDA that compares favorably to the simulation results. This work was supported by DOE under Grant DE-FG02-06ER54879 and Cooperate Agreement No. DE-FC52-08NA28302, by NSF under Grant PHY-0903797, and by NSFC under Grant No. 11129503. The research used resources of NERSC. We also thank the OSIRIS consortium for the use of OSIRIS.

  2. Fast food restaurant lighting and music can reduce calorie intake and increase satisfaction.

    PubMed

    Wansink, Brian; van Ittersum, Koert

    2012-08-01

    Recent research shows that environmental cues such as lighting and music strongly bias the eating behavior of diners in laboratory situations. This study examines whether changing the atmosphere of a fast food restaurant would change how much patrons ate. The results indicated that softening the lighting and music led people to eat less, to rate the food as more enjoyable, and to spend just as much. In contrast to hypothesized U-shaped curves (people who spend longer eat more), this suggests a more relaxed environment increases satisfaction and decreases consumption.

  3. Compact, highly sensitive optical gyros and sensors with fast-light

    NASA Astrophysics Data System (ADS)

    Christensen, Caleb A.; Zavriyev, Anton; Cummings, Malcolm; Beal, A. C.; Lucas, Mark; Lagasse, Michael

    2015-09-01

    Fast-light phenomena can enhance the sensitivity of an optical gyroscope of a given size by several orders of magnitude, and could be applied to other optical sensors as well. MagiQ Technologies has been developing a compact fiber-based fast light Inertial Measurement Unit (IMU) using Stimulated Brillouin Scattering in optical fibers with commercially mature technologies. We will report on our findings, including repeatable fast-light effects in the lab, numerical analysis of noise and stability given realistic optical specs, and methods for optimizing efficiency, size, and reliability with current technologies. The technology could benefit inertial navigation units, gyrocompasses, and stabilization techniques, and could allow high grade IMUs in spacecraft, unmanned aerial vehicles or sensors, where the current size and weight of precision gyros are prohibitive. By using photonic integrated circuits and telecom-grade components along with specialty fibers, we also believe that our design is appropriate for development without further advances in the state of the art of components.

  4. A fast model for spreading of neutral particles injected locally into hot plasma

    SciTech Connect

    Tokar, M. Z.

    2014-08-15

    A fast model for calculation of non-stationary 3-D profiles of the density for neutral particles locally released into a hot plasma is elaborated. The approach reduces non-stationary three-dimensional transport equations to a set of one-dimensional ones describing the time evolution of the radial profiles for several parameters characterizing adequately the three-dimensional structure. The method is applied to model the spreading process of carbon atoms released by laser desorption in an experimental device and the local injection of working gas into a fusion reactor. The associated heat loads onto the first wall are assessed.

  5. Depolarization of light backscattered by randomly oriented nonspherical particles.

    PubMed

    Mishchenko, M I; Hovenier, J W

    1995-06-15

    We derive theoretically and validate numerically general relationships for the elements of the backscattering matrix and for the linear, delta(L), and circular, delta(C), backscattering depolarization ratios for nonspherical particles in random orientation. For the practically important case of randomly oriented particles with a plane of symmetry or particles and their mirror particles occurring in equal numbers and in random orientation, delta(C) = 2delta(L)/(1 - delta(L)). Extensive T-matrix computations for randomly oriented spheroids demonstrate that, although both delta(L) and delta(C) are indicators of particle nonsphericity, they cannot be considered a universal measure of the departure of particle shape from that of a sphere and have no simple dependence on particle size and refractive index.

  6. Fast Three-Dimensional Single-Particle Tracking in Natural Brain Tissue

    PubMed Central

    Sokoll, Stefan; Prokazov, Yury; Hanses, Magnus; Biermann, Barbara; Tönnies, Klaus; Heine, Martin

    2015-01-01

    Observation of molecular dynamics is often biased by the optical very heterogeneous environment of cells and complex tissue. Here, we have designed an algorithm that facilitates molecular dynamic analyses within brain slices. We adjust fast astigmatism-based three-dimensional single-particle tracking techniques to depth-dependent optical aberrations induced by the refractive index mismatch so that they are applicable to complex samples. In contrast to existing techniques, our online calibration method determines the aberration directly from the acquired two-dimensional image stream by exploiting the inherent particle movement and the redundancy introduced by the astigmatism. The method improves the positioning by reducing the systematic errors introduced by the aberrations, and allows correct derivation of the cellular morphology and molecular diffusion parameters in three dimensions independently of the imaging depth. No additional experimental effort for the user is required. Our method will be useful for many imaging configurations, which allow imaging in deep cellular structures. PMID:26445447

  7. Plasma flow and fast particles in a hypervelocity accelerator - A color presentation. [micrometeoroid simulation

    NASA Technical Reports Server (NTRS)

    Igenbergs, E. B.; Cour-Palais, B.; Fisher, E.; Stehle, O.

    1975-01-01

    A new concept for particle acceleration for micrometeoroid simulation was developed at NASA Marshall Space Flight Center, using a high-density self-luminescent fast plasma flow to accelerate glass beads (with a diameter up to 1.0 mm) to velocities between 15-20 km/sec. After a short introduction to the operation of the hypervelocity range, the eight-converter-camera unit used for the photographs of the plasma flow and the accelerated particles is described. These photographs are obtained with an eight-segment reflecting pyramidal beam splitter. Wratten filters were mounted between the beam splitter and the converter tubes of the cameras. The photographs, which were recorded on black and white film, were used to make the matrices for the dye-color process, which produced the prints shown.

  8. The effect of fast and regeneration in light versus dark on regulation in the hydra-algal symbiosis

    NASA Technical Reports Server (NTRS)

    Bossert, P.; Slobodkin, L. B.

    1983-01-01

    Green hydra are able to regenerate tentacles after fast durations which cause brown, i.e., asymbiotic, hydra to fail completely, but the presence of endosymbiotic algae does not always enhance regeneration in fasted hydra. Green hydra whose nutritional state falls below some threshold, exhibit a light induced inhibition of regeneration. That is, hydra, fasted in the light, then randomly assigned to light or dark after decapitation, regenerate better in the dark. This effect of light does not appear to be present either in brown hydra or in normally green hydra from which the algae were removed. In a large strain of Chlorohydra viridissima, after fasts of intermediate duration (10 and 15 days), this light induced inhibition of regeneration is associated with an increase in the number of algae per gastric cell in regenerating hydra relative to non-regenerating controls.

  9. Thermodynamic correction of particle concentrations measured by underwing probes on fast flying aircraft

    NASA Astrophysics Data System (ADS)

    Weigel, R.; Spichtinger, P.; Mahnke, C.; Klingebiel, M.; Afchine, A.; Petzold, A.; Krämer, M.; Costa, A.; Molleker, S.; Jurkat, T.; Minikin, A.; Borrmann, S.

    2015-12-01

    Particle concentration measurements with underwing probes on aircraft are impacted by air compression upstream of the instrument body as a function of flight velocity. In particular for fast-flying aircraft the necessity arises to account for compression of the air sample volume. Hence, a correction procedure is needed to invert measured particle number concentrations to ambient conditions that is commonly applicable for different instruments to gain comparable results. In the compression region where the detection of particles occurs (i.e. under factual measurement conditions), pressure and temperature of the air sample are increased compared to ambient (undisturbed) conditions in certain distance away from the aircraft. Conventional procedures for scaling the measured number densities to ambient conditions presume that the particle penetration speed through the instruments' detection area equals the aircraft speed (True Air Speed, TAS). However, particle imaging instruments equipped with pitot-tubes measuring the Probe Air Speed (PAS) of each underwing probe reveal PAS values systematically below those of the TAS. We conclude that the deviation between PAS and TAS is mainly caused by the compression of the probed air sample. From measurements during two missions in 2014 with the German Gulfstream G-550 (HALO - High Altitude LOng range) research aircraft we develop a procedure to correct the measured particle concentration to ambient conditions using a thermodynamic approach. With the provided equation the corresponding concentration correction factor ξ is applicable to the high frequency measurements of each underwing probe which is equipped with its own air speed sensor (e.g. a pitot-tube). ξ-values of 1 to 0.85 are calculated for air speeds (i.e. TAS) between 60 and 260 m s-1. From HALO data it is found that ξ does not significantly vary between the different deployed instruments. Thus, for the current HALO underwing probe configuration a parameterisation of

  10. A fast method for optical simulation of flood maps of light-sharing detector modules

    NASA Astrophysics Data System (ADS)

    Shi, Han; Du, Dong; Xu, JianFeng; Moses, William W.; Peng, Qiyu

    2015-12-01

    Optical simulation of the detector module level is highly desired for Position Emission Tomography (PET) system design. Commonly used simulation toolkits such as GATE are not efficient in the optical simulation of detector modules with complicated light-sharing configurations, where a vast amount of photons need to be tracked. We present a fast approach based on a simplified specular reflectance model and a structured light-tracking algorithm to speed up the photon tracking in detector modules constructed with polished finish and specular reflector materials. We simulated conventional block detector designs with different slotted light guide patterns using the new approach and compared the outcomes with those from GATE simulations. While the two approaches generated comparable flood maps, the new approach was more than 200-600 times faster. The new approach has also been validated by constructing a prototype detector and comparing the simulated flood map with the experimental flood map. The experimental flood map has nearly uniformly distributed spots similar to those in the simulated flood map. In conclusion, the new approach provides a fast and reliable simulation tool for assisting in the development of light-sharing-based detector modules with a polished surface finish and using specular reflector materials.

  11. A fast method for optical simulation of flood maps of light-sharing detector modules

    PubMed Central

    Shi, Han; Du, Dong; Xu, JianFeng; Moses, William W.; Peng, Qiyu

    2016-01-01

    Optical simulation of the detector module level is highly desired for Position Emission Tomography (PET) system design. Commonly used simulation toolkits such as GATE are not efficient in the optical simulation of detector modules with complicated light-sharing configurations, where a vast amount of photons need to be tracked. We present a fast approach based on a simplified specular reflectance model and a structured light-tracking algorithm to speed up the photon tracking in detector modules constructed with polished finish and specular reflector materials. We simulated conventional block detector designs with different slotted light guide patterns using the new approach and compared the outcomes with those from GATE simulations. While the two approaches generated comparable flood maps, the new approach was more than 200–600 times faster. The new approach has also been validated by constructing a prototype detector and comparing the simulated flood map with the experimental flood map. The experimental flood map has nearly uniformly distributed spots similar to those in the simulated flood map. In conclusion, the new approach provides a fast and reliable simulation tool for assisting in the development of light-sharing-based detector modules with a polished surface finish and using specular reflector materials. PMID:27660376

  12. Active and fast particle driven Alfvén eigenmodes in Alcator C-Moda)

    NASA Astrophysics Data System (ADS)

    Snipes, J. A.; Basse, N.; Boswell, C.; Edlund, E.; Fasoli, A.; Gorelenkov, N. N.; Granetz, R. S.; Lin, L.; Lin, Y.; Parker, R.; Porkolab, M.; Sears, J.; Sharapov, S.; Tang, V.; Wukitch, S.

    2005-05-01

    Alfvén eigenmodes (AEs) are studied to assess their stability in high density reactor relevant regimes where Ti≈Te and as a diagnostic tool. Stable AEs are excited with active magnetohydrodynamics antennas in the range of the expected AE frequency. Toroidal Alfvén eigenmode (TAE) damping rates between 0.5%<γ/ω<4.5% have been observed in diverted and limited Ohmic plasmas. Unstable AEs are excited with a fast ion tail driven by H minority ion cyclotron radio frequency (ICRF) heating with electron densities in the range of n¯e=0.5-2×1020m-3. Energetic particle modes or TAEs have been observed to decrease in frequency and mode number with time up to a large sawtooth collapse, indicating the role fast particles play in stabilizing sawteeth. In the current rise phase, unstable modes with frequencies that increase rapidly with time are observed with magnetic pick-up coils at the wall and phase contrast imaging density fluctuation measurements in the core. Modeling of these modes constrains the calculated safety factor profile to be very flat or with slightly reversed shear. AEs are found to be more stable for an inboard than for central or outboard ICRF resonances in qualitative agreement with modeling.

  13. Stimulated Light Emission and Inelastic Scattering by a Classical Linear System of Rotating Particles

    SciTech Connect

    Asenjo-Garcia, Ana; Manjavacas, Alejandro; Garcia de Abajo, F. Javier

    2011-05-27

    The rotational dynamics of particles subject to external illumination is found to produce light amplification and inelastic scattering at high rotation velocities. Light emission at frequencies shifted with respect to the incident light by twice the rotation frequency dominates over elastic scattering within a wide range of light and rotation frequencies. Remarkably, net amplification of the incident light is produced in this classical linear system via stimulated emission. Large optically induced acceleration rates are predicted in vacuum accompanied by moderate heating of the particle, thus supporting the possibility of observing these effects under extreme rotation conditions.

  14. Thermodynamic correction of particle concentrations measured by underwing probes on fast-flying aircraft

    NASA Astrophysics Data System (ADS)

    Weigel, Ralf; Spichtinger, Peter; Mahnke, Christoph; Klingebiel, Marcus; Afchine, Armin; Petzold, Andreas; Krämer, Martina; Costa, Anja; Molleker, Sergej; Reutter, Philipp; Szakáll, Miklós; Port, Max; Grulich, Lucas; Jurkat, Tina; Minikin, Andreas; Borrmann, Stephan

    2016-10-01

    Particle concentration measurements with underwing probes on aircraft are impacted by air compression upstream of the instrument body as a function of flight velocity. In particular, for fast-flying aircraft the necessity arises to account for compression of the air sample volume. Hence, a correction procedure is needed to invert measured particle number concentrations to ambient conditions that is commonly applicable to different instruments to gain comparable results. In the compression region where the detection of particles occurs (i.e. under factual measurement conditions), pressure and temperature of the air sample are increased compared to ambient (undisturbed) conditions in certain distance away from the aircraft. Conventional procedures for scaling the measured number densities to ambient conditions presume that the air volume probed per time interval is determined by the aircraft speed (true air speed, TAS). However, particle imaging instruments equipped with pitot tubes measuring the probe air speed (PAS) of each underwing probe reveal PAS values systematically below those of the TAS. We conclude that the deviation between PAS and TAS is mainly caused by the compression of the probed air sample. From measurements during two missions in 2014 with the German Gulfstream G-550 (HALO - High Altitude LOng range) research aircraft we develop a procedure to correct the measured particle concentration to ambient conditions using a thermodynamic approach. With the provided equation, the corresponding concentration correction factor ξ is applicable to the high-frequency measurements of the underwing probes, each of which is equipped with its own air speed sensor (e.g. a pitot tube). ξ values of 1 to 0.85 are calculated for air speeds (i.e. TAS) between 60 and 250 m s-1. For different instruments at individual wing position the calculated ξ values exhibit strong consistency, which allows for a parameterisation of ξ as a function of TAS for the current HALO

  15. Particle and field characteristics of broadband electrons observed by the FAST satellite during a geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Nakajima, A.; Shiokawa, K.; Seki, K.; Strangeway, R. J.; McFadden, J. P.; Carlson, C. W.

    2007-06-01

    Broadband electrons (BBEs) are remarkable flux enhancements (>1013 eV cm-2 s-1) of precipitating electrons over a broad energy range (0.03-30 keV) near the equatorward edge of the auroral oval during geomagnetic storms. We show characteristics of particles (energy spectra and pitch angle distribution) and fields (electric field, magnetic field, and wave spectra) during a BBE event observed by the Fast Auroral SnapshoT (FAST) satellite. The BBEs were observed at an altitude of ˜2000 km at 59°-61° invariant latitudes (ILATs) and 21 h magnetic local time (MLT). The event was observed at ˜7 min after the onset of a substorm during the main phase of the Bastille Day geomagnetic storm (minimum Dst = -301 nT) on 15 July 2000. The precipitation region of the BBEs corresponded to a localized intensification of auroral emission, lasting ˜14 min, observed by the Polar UVI images at 50°-60° geomagnetic latitudes (MLATs) and 20-21 MLTs. These results suggest that rapid particle acceleration was occurring in the inner magnetosphere associated with a storm-time substorm. The pitch angle distribution of BBEs was isotropic except for a loss cone feature around the field-aligned upward direction at a higher energy range above ˜1 keV, while field-aligned electron fluxes were larger than the perpendicular fluxes below ˜1 keV. These results imply that a higher energy part of the BBEs originated from higher altitudes in the inner magnetosphere and that a lower energy part was accelerated parallel to the local magnetic field at lower altitudes near the satellite. Intense fluctuations of electric and magnetic fields were observed during this BBE event. From these results, we discuss possible acceleration of the lower energy part of BBEs through wave-particle interaction.

  16. Design and analysis of particles detecting system based on near forward light scattering

    NASA Astrophysics Data System (ADS)

    Cui, Xiao-Jun; Li, Xiao; Yu, Jia-Xin

    2016-01-01

    A novel design based on near forward light scattering detection system to measure size and concentration distribution of particles in liquids is reported. According to theory of Mie scattering, the influence of relative refractive index, particles size and wavelength on the detection results are discussed. A green optical fiber laser with 532nm was used as the excited light source. As a key part in the detection system, the focusing system using a lens structure to confine light sensitive area with Gauss distribution less than 80 μm2. The lateral size of the sample cell is limited to 100μm. In order to measure the particles in non-overlapping state and improve the accuracy and repeatability, a novel structure in the sample cell was used and particle velocity through the sample cell was controlled by high precision stepper motor control system of micro circulation pump. Particle light scattering signal acquisition was completed by the poly lens combination system, according to the receiving angle relative to the measured particle, which can adjust the light scattering direction to obtain better particles light scattering signal. Photoelectric signal conversion, amplification and acquisition are all the devices with high precision. The measurement results showed that the measurement system was accurate and stable when the particles size in the range of 0.5-5μm.

  17. Thermo-Mechanical Analysis of Coated Particle Fuel Experiencing a Fast Control Rod Ejection Transient

    SciTech Connect

    Ortensi, J.; Brian Boer; Abderrafi M. Ougouag

    2010-10-01

    A rapid increase of the temperature and the mechanical stress is expected in TRISO coated particle fuel that experiences a fast Total Control Rod Ejection (CRE) transient event. During this event the reactor power in the pebble bed core increases significantly for a short time interval. The power is deposited instantly and locally in the fuel kernel. This could result in a rapid increase of the pressure in the buffer layer of the coated fuel particle and, consequently, in an increase of the coating stresses. These stresses determine the mechanical failure probability of the coatings, which serve as the containment of radioactive fission products in the Pebble Bed Reactor (PBR). A new calculation procedure has been implemented at the Idaho National Laboratory (INL), which analyzes the transient fuel performance behavior of TRISO fuel particles in PBRs. This early capability can easily be extended to prismatic designs, given the availability of neutronic and thermal-fluid solvers. The full-core coupled neutronic and thermal-fluid analysis has been modeled with CYNOD-THERMIX. The temperature fields for the fuel kernel and the particle coatings, as well as the gas pressures in the buffer layer, are calculated with the THETRIS module explicitly during the transient calculation. Results from this module are part of the feedback loop within the neutronic-thermal fluid iterations performed for each time step. The temperature and internal pressure values for each pebble type in each region of the core are then input to the PArticle STress Analysis (PASTA) code, which determines the particle coating stresses and the fraction of failed particles. This paper presents an investigation of a Total Control Rod Ejection (TCRE) incident in the 400 MWth Pebble Bed Modular reactor design using the above described calculation procedure. The transient corresponds to a reactivity insertion of $3 (~2000 pcm) reaching 35 times the nominal power in 0.5 seconds. For each position in the core

  18. Sensitivity Analysis of Reprocessing Cooling Times on Light Water Reactor and Sodium Fast Reactor Fuel Cycles

    SciTech Connect

    R. M. Ferrer; S. Bays; M. Pope

    2008-04-01

    The purpose of this study is to quantify the effects of variations of the Light Water Reactor (LWR) Spent Nuclear Fuel (SNF) and fast reactor reprocessing cooling time on a Sodium Fast Reactor (SFR) assuming a single-tier fuel cycle scenario. The results from this study show the effects of different cooling times on the SFR’s transuranic (TRU) conversion ratio (CR) and transuranic fuel enrichment. Also, the decay heat, gamma heat and neutron emission of the SFR’s fresh fuel charge were evaluated. A 1000 MWth commercial-scale SFR design was selected as the baseline in this study. Both metal and oxide CR=0.50 SFR designs are investigated.

  19. Collimated light reflection and transmission of a surface partially covered by large and tenuous particles.

    PubMed

    Vázquez-Estrada, Omar; García-Valenzuela, Augusto

    2016-11-01

    We derive simple approximate expressions for the reflectivity and transmissivity of light from disordered monolayers of tenuous particles of dimensions larger than the wavelength and supported by a flat interface. The expressions derived can be used for different particle shapes and for moderate angles of incidence. We then investigate the effects of particle shape and orientation on reflectivity and transmissivity spectra of a monolayer of tenuous particles containing an optical chromophore in a solution in their interior. We also simulate the effects of a particle's shape and orientation on the angle dependence of the optical reflectivity and transmissivity. In our examples, we consider disordered monolayers of particles analogous to some biological cells.

  20. Fast detection of alpha particles in DAM-ADC nuclear track detectors

    NASA Astrophysics Data System (ADS)

    Rammah, Y. S.; Ashraf, O.; Abdalla, A. M.; Eisa, M.; Ashry, A. H.; Tsuruta, T.

    2015-02-01

    Fast detection of alpha particles in DAM-ADC nuclear track detectors using a new chemical etchant was investigated. 252Cf and 241Am sources were used for irradiating samples of DAM-ADC SSNTDs with fission fragments and alpha particles in air at normal temperature and pressure. A series of experimental chemical etching are carried out using new etching solution (8 ml of 10 N NaOH+ 1 ml CH3OH) at 60 °C to detect alpha particle in short time in DAM-ADC detectors. Suitable analyzing software has been used to analyze experimental data. From fission and alpha track diameters, the value of bulk etching rate is equal to 8.52 μm/h. Both of the sensitivity and etching efficiency were found to vary with the amount of methanol in the etching solution and etching time. The DAM-ADC detectors represent the best efficiency applicable in detectors in the entire range of alpha energies (from 1 to 5 MeV). The activation energies of this etchant have been calculated; track activation energy, ET, has been found to be lower than the bulk activation energy, EB, for the DAM-ADC nuclear track detectors. These results are in more agreement with the previous work.

  1. Spinor Slow-Light and Dirac Particles with Variable Mass

    SciTech Connect

    Unanyan, R. G.; Otterbach, J.; Fleischhauer, M.; Ruseckas, J.; Kudriasov, V.; Juzeliunas, G.

    2010-10-22

    We consider the interaction of two weak probe fields of light with an atomic ensemble coherently driven by two pairs of standing wave laser fields in a tripod-type linkage scheme. The system is shown to exhibit a Dirac-like spectrum for light-matter quasiparticles with multiple dark states, termed spinor slow-light polaritons. They posses an 'effective speed of light' given by the group velocity of slow light, and can be made massive by inducing a small two-photon detuning. Control of the two-photon detuning can be used to locally vary the mass including a sign flip. Particularly, this allows the implementation of the random-mass Dirac model for which localized zero-energy (midgap) states exist with unusual long-range correlations.

  2. Fast, Large-Area, Wide-Bandgap UV Photodetector for Cherenkov Light Detection

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Wrbanek, Susan Y.

    2013-01-01

    Due to limited resources available for power and space for payloads, miniaturizing and integrating instrumentation is a high priority for addressing the challenges of manned and unmanned deep space missions to high Earth orbit (HEO), near Earth objects (NEOs), Lunar and Martian orbits and surfaces, and outer planetary systems, as well as improvements to high-altitude aircraft safety. New, robust, and compact detectors allow future instrumentation packages more options in satisfying specific mission goals. A solid-state ultraviolet (UV) detector was developed with a theoretical fast response time and large detection area intended for application to Cherenkov detectors. The detector is based on the wide-bandgap semiconductor zinc oxide (ZnO), which in a bridge circuit can detect small, fast pulses of UV light like those required for Cherenkov detectors. The goal is to replace the role of photomultiplier tubes in Cherenkov detectors with these solid-state devices, saving on size, weight, and required power. For improving detection geometry, a spherical detector to measure high atomic number and energy (HZE) ions from any direction has been patented as part of a larger space radiation detector system. The detector will require the development of solid-state UV photodetectors fast enough (2 ns response time or better) to detect the shockwave of Cherenkov light emitted as the ions pass through a quartz, sapphire, or acrylic ball. The detector must be small enough to fit in the detector system structure, but have an active area large enough to capture enough Cherenkov light from the sphere. The detector is fabricated on bulk single-crystal undoped ZnO. Inter - digitated finger electrodes and contact pads are patterned via photolithography, and formed by sputtered metal of silver, platinum, or other high-conductivity metal.

  3. Mathieu beams as versatile light moulds for 3D micro particle assemblies.

    PubMed

    Alpmann, C; Bowman, R; Woerdemann, M; Padgett, M; Denz, C

    2010-12-06

    We present tailoring of three dimensional light fields which act as light moulds for elaborate particle micro structures of variable shapes. Stereo microscopy is used for visualization of the 3D particle assemblies. The powerful method is demonstrated for the class of propagation invariant beams, where we introduce the use of Mathieu beams as light moulds with non-rotationally-symmetric structure. They offer multifarious field distributions and facilitate the creation of versatile particle structures. This general technique may find its application in micro fluidics, chemistry, biology, and medicine, to create highly efficient mixing tools, for hierarchical supramolecular organization or in 3D tissue engineering.

  4. Can a particle interacting with a scalar field reach the speed of light\\?

    NASA Astrophysics Data System (ADS)

    Vollick, Dan N.

    1995-09-01

    The motion of a particle interacting with a scalar field is examined. It is shown that the effective mass of the particle is a linear function of the scalar field and that the particle reaches the speed of light when its effective mass goes to zero if scalar field radiation is neglected. The equation of motion for the particle including radiation reaction has the same form as the Lorentz-Dirac equation. The radiation emitted diverges as the particle approaches the speed of light and prevents the particle from becoming luminal. The energy-momentum tensor for the particle and field is calculated and it is shown that there exists an interaction energy-momentum tensor which allows for violations of the weak energy condition.

  5. Improved light extraction with nano-particles offering directional radiation diagrams

    SciTech Connect

    Jouanin, A.; Hugonin, J. P.; Besbes, M.; Lalanne, P.

    2014-01-13

    We propose a unique approach for light extraction, using engineered nano-particles to efficiently decouple the light guided in transverse-magnetic guided modes into free-space radiation modes that leak out normally to the thin-film stacks. The underlying mechanism takes advantage of a small electric field variation at the nano-particle scale and induces a “polarization conversion,” which renders the induced dipole moment perpendicular to the polarization of the incident light. Our analysis is supported by 2D fully vectorial computational results. Potential applications for light emitting or photovoltaic devices are outlined.

  6. Fast electron energy deposition in a magnetized plasma: Kinetic theory and particle-in-cell simulation

    SciTech Connect

    Robiche, J.; Rax, J.-M.; Bonnaud, G.; Gremillet, L.

    2010-03-15

    The collisional dynamics of a relativistic electron jet in a magnetized plasma are investigated within the framework of kinetic theory. The relativistic Fokker-Planck equation describing slowing down, pitch angle scattering, and cyclotron rotation is derived and solved. Based on the solution of this Fokker-Planck equation, an analytical formula for the root mean square spot size transverse to the magnetic field is derived and this result predicts a reduction in radial transport. Some comparisons with particle-in-cell simulation are made and confirm striking agreement between the theory and the simulation. For fast electron with 1 MeV typical kinetic energy interacting with a solid density hydrogen plasma, the energy deposition density in the transverse direction increases by a factor 2 for magnetic field of the order of 1 T. Along the magnetic field, the energy deposition profile is unaltered compared with the field-free case.

  7. Particle-In-Cell modeling of Fast Ignition experiments on the Titan Laser

    NASA Astrophysics Data System (ADS)

    Link, Anthony; Akli, K. U.; Beg, F.; Chen, C. D.; Davies, J. R.; Freeman, R. R.; Kemp, G. E.; Li, K.; McLean, H. S.; Morace, A.; Patel, P. K.; Schumacher, D. W.; Sorokovikova, A. V.; Stephens, R.; Streeter, M. J. V.; Wertepny, D.; Westhover, B.

    2012-10-01

    We report on particle-in-cell-modeling (PIC) of fast ignition experiments conducted on the Titan laser. The Titan laser was used to irradiate multilayer planar targets at intensities greater than 10^20 Wcm-2 to diagnose the laser to electron coupling, electron beam divergence, and energy spectrum of the hot electrons at relativistic intensities. Hot electron beam properties were inferred through buried fluors, escaping electrons and bremsstrahlung measurements. The PIC simulations of the experiment were conducted in two stages: a high resolution laser plasma interaction (LPI) simulation using measured on shot laser parameters but with a subscale target; and a lower resolution transport simulation containing the full scale multilayer target. The transport simulation utilized the electron source based on the output of the LPI simulation and included necessary models to simulate the experimental diagnostics. Comparison of the predicted electron source properties and the experimental data will be presented.

  8. Inverse problem for multiple scattering of fast charged particles in a mesoscopic medium

    SciTech Connect

    Ramm, A.G. C-3 Division, Los Alamos National Laboratory, Los Alamos, New Mexcio 87545 ); Berman, G.P. Kirensky Institute of Physics, Research Educational Center for Nonlinear Processes, The Krasnoyarsk Technical University, 660036 Krasnoyarsk Theoretical Department, The Krasnoyarsk State University, 660036 Krasnoyarsk )

    1995-01-15

    We consider an inverse problem of multiple scattering for fast charged particles propagating in an inhomogeneous medium. The scattering processes are described by the diffusion-type equation in the small-angle approximation. It is shown that by using the scattering data given on some small interval, it is possible to recover the spatial dependence of the density of the medium. This inverse problem is ill posed in the sense that small noise in the data may lead to large perturbations in [epsilon]([ital z]) if no [ital a] priori assumptions are made about [epsilon]([ital z]). This is clear from our presentation, since an analytic continuation of [epsilon]([ital z]) is involved. One hopes that the proposed method can be applied to thin foils and to mesoscopic systems.

  9. The Interior Analysis and 3-D Reconstruction of Internally-Mixed Light-Absorbing Atmospheric Particles

    NASA Astrophysics Data System (ADS)

    Conny, J. M.; Collins, S. M.; Anderson, I.; Herzing, A.

    2010-12-01

    Carbon-containing atmospheric particles may either absorb solar or outgoing long-wave radiation or scatter solar radiation, and thus, affect Earth’s radiative balance in multiple ways. Light-absorbing carbon that is common in urban air particles such as industrial coke dust, road dust, and diesel soot, often exists in the same particle with other phases that contain, for example, aluminum, calcium, iron, and sulfur. While the optical properties of atmospheric particles in general depend on overall particle size and shape, the inhomogeneity of chemical phases within internally-mixed particles may also greatly affect particle optical properties. In this study, a series of microscopic approaches were used to identify individual light-absorbing coarse-mode particles and to assess their interior structure and composition. Particle samples were collected in 2004 from one of the U.S. EPA’s Los Angeles Particulate Matter Supersites, and were likely affected substantially by road dust and construction dust. First, bright-field and dark-field light microscopy and computer-controlled scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDX) were used to distinguish predominantly light-absorbing carbonaceous particles from other particle types such as mineral dust, sea salt, and brake wear. Second, high-resolution SEM-EDX elemental mapping of individual carbonaceous particles was used to select particles with additional elemental phases that exhibited spatial inhomogeneity. Third, focused ion-beam SEM (FIB-SEM) with EDX was used to slice through selected particles to expose interior surfaces and to determine the spatial distribution of element phases throughout the particles. Fourth, study of the interior phases of a particle was augmented by the transmission electron microscopy (TEM) of a thin section of the particle prepared by FIB-SEM. Here, electron energy loss spectroscopy with TEM was used to study chemical bonding in the carbonaceous phase

  10. Reversible Fano resonance by transition from fast light to slow light in a coupled-resonator-induced transparency structure.

    PubMed

    Zhang, Yundong; Zhang, Xuenan; Wang, Ying; Zhu, Ruidong; Gai, Yulong; Liu, Xiaoqi; Yuan, Ping

    2013-04-08

    We theoretically propose and experimentally perform a novel dispersion tuning scheme to realize a tunable Fano resonance in a coupled-resonator-induced transparency (CRIT) structure coupled Mach-Zehnder interferometer. We reveal that the profile of the Fano resonance in the resonator coupled Mach-Zehnder interferometers (RCMZI) is determined not only by the phase shift difference between the two arms of the RCMZI but also by the dispersion (group delay) of the CRIT structure. Furthermore, it is theoretically predicted and experimentally demonstrated that the slope and the asymmetry parameter (q) describing the Fano resonance spectral line shape of the RCMZI experience a sign reversal when the dispersion of the CRIT structure is tuned from abnormal dispersion (fast light) to normal dispersion (slow light). These theoretical and experimental results indicate that the reversible Fano resonance which holds significant implications for some attractive device applications such as highly sensitive biochemical sensors, ultrafast optical switches and routers can be realized by the dispersion tuning scheme in the RCMZI.

  11. Roto-Translational Effects on Deflection of Light and Particle by Moving Kerr Black Hole

    NASA Astrophysics Data System (ADS)

    He, G.; Lin, W.

    2014-02-01

    Velocity effects in first-order Schwarzschild deflection of light and particles have been explored in the previous literature. In this paper, we investigate the roto-translational-motion induced deflection by one moving Kerr black hole with an arbitrary, but constant speed. It is shown that the coupling between the effects of the rotation and the translational motion always exists for both light and particles. The contribution of the roto-translational deflection to the total bending angle is discussed in detail. This ratio takes upper limit for light and it decreases monotonically with increasing translational velocity for a massive particle. For a given translational velocity of black hole, this ratio increases with the particle's velocity. In addition, the post-Newtonian dynamics of the photon and particle is also presented.

  12. SPED light sheet microscopy: fast mapping of biological system structure and function

    PubMed Central

    Tomer, Raju; Lovett-Barron, Matthew; Kauvar, Isaac; Andalman, Aaron; Burns, Vanessa M.; Sankaran, Sethuraman; Grosenick, Logan; Broxton, Michael; Yang, Samuel; Deisseroth, Karl

    2016-01-01

    The goal of understanding living nervous systems has driven interest in high-speed and large field-of-view volumetric imaging at cellular resolution. Light-sheet microscopy approaches have emerged for cellular-resolution functional brain imaging in small organisms such as larval zebrafish, but remain fundamentally limited in speed. Here we have developed SPED light sheet microscopy, which combines large volumetric field-of-view via an extended depth of field with the optical sectioning of light sheet microscopy, thereby eliminating the need to physically scan detection objectives for volumetric imaging. SPED enables scanning of thousands of volumes-per-second, limited only by camera acquisition rate, through the harnessing of optical mechanisms that normally result in unwanted spherical aberrations. We demonstrate capabilities of SPED microscopy by performing fast sub-cellular resolution imaging of CLARITY mouse brains and cellular-resolution volumetric Ca2+ imaging of entire zebrafish nervous systems. Together, SPED light sheet methods enable high-speed cellular-resolution volumetric mapping of biological system structure and function. PMID:26687363

  13. A fast fusion scheme for infrared and visible light images in NSCT domain

    NASA Astrophysics Data System (ADS)

    Zhao, Chunhui; Guo, Yunting; Wang, Yulei

    2015-09-01

    Fusion of infrared and visible light images is an effective way to obtain a simultaneous visualization of details of background provided by visible light image and hiding target information provided by infrared image, which is more suitable for browsing and further processing. Two crucial components for infrared and visual light image fusion are improving its fusion performance as well as reducing its computational burden. In this paper, a novel fusion algorithm named pixel information estimation is proposed, which determines the weights by evaluating the information of pixel and is well applied in visible light and infrared image fusion with better fusion quality and lower time-consumption. Besides, a fast realization of non-subsampled contourlet transform is also proposed in this paper to improve the computational efficiency. To verify the advantage of the proposed method, this paper compares it with several popular ones in six evaluation metrics over four different image groups. Experimental results show that the proposed algorithm gets a more effective result with much less time consuming and performs well in both subjective evaluation and objective indicators.

  14. Multiple particle production processes in the light'' of quantum optics

    SciTech Connect

    Friedlander, E.M.

    1990-09-01

    Ever since the observation that high-energy nuclear active'' cosmic-ray particles create bunches of penetrating particles upon hitting targets, a controversy has raged about whether these secondaries are created in a single act'' or whether many hadrons are just the result of an intra-nuclear cascade, yielding one meson in every step. I cannot escape the impression that: the latter kind of model appeals naturally as a consequence of an innate bio-morphism in our way of thinking and that in one guise or another it has tenaciously survived to this day, also for hadron-hadron collisions, via multi-peripheral models to the modern parton shower approach. Indeed, from the very beginning of theoretical consideration of multiparticle production, the possibility of many particles arising from a single hot'' system has been explored, with many fruitful results, not the least of which are the s{sup 1/4} dependence of the mean produced particle multiplicity and the thermal'' shape of the P{sub T} spectra. An important consequence of the thermodynamical-hydrodynamical models is that particle emission is treated in analogy to black-body radiation, implying for the secondaries a set of specific Quantum-Statistical properties, very similar to those observed in quantum optics. From here on I shall try to review a number of implications and applications of this QS analogy in the study of multiplicity distributions of the produced secondaries. I will touch only in passing another very important topic of this class, the Bose-Einstein two-particle correlations.

  15. Light diffraction by a particle on an optically smooth surface.

    PubMed

    Johnson, B R

    1997-01-01

    The differential cross section for radiation scattered by a particle that is large compared to the wavelength, and resting on an optically smooth surface, is characterized by an intense, narrow peak in the direction of the reflected beam. This peak is shown to be due mainly to Fraunhofer diffraction by the overlapping projections of the particle and its image on a plane perpendicular to the reflected beam. Results calculated with this simple diffraction theory are compared with accurate results calculated by the multipole expansion method. Simple analytic formulas are derived that characterize the width and height of the central diffraction peak.

  16. Transparency and tunable slow and fast light in a nonlinear optomechanical cavity

    NASA Astrophysics Data System (ADS)

    Li, Ling; Nie, Wenjie; Chen, Aixi

    2016-10-01

    We investigate theoretically the optical response of the output field and the tunable slow and fast light in a nonlinear optomechanical cavity with a degenerate optical parametric amplifier (OPA) and a higher order excited atomic ensemble. Studies show that the higher-order-excitation atom which is similar to the degenerate OPA that acts as a nonlinear medium, induces an additional dip in absorption spectrum of the probe field. The coherence of the mechanical oscillator leads to split the peak in absorption in the probe field spectrum so that the phenomenon of optomechanically induced transparency (OMIT) is generated from the output probe field. In particular, the presence of nonlinearities with the degenerate OPA and the higher order excited atoms can affect significantly the width of the transparency windows, providing an additional flexibility for controlling optical properties. Furthermore, in the presence of the degenerate OPA, the optical-response properties for the probe field become phase-sensitive so that a tunable switch from slow to fast light can be realized.

  17. Transparency and tunable slow and fast light in a nonlinear optomechanical cavity

    PubMed Central

    Li, Ling; Nie, Wenjie; Chen, Aixi

    2016-01-01

    We investigate theoretically the optical response of the output field and the tunable slow and fast light in a nonlinear optomechanical cavity with a degenerate optical parametric amplifier (OPA) and a higher order excited atomic ensemble. Studies show that the higher-order-excitation atom which is similar to the degenerate OPA that acts as a nonlinear medium, induces an additional dip in absorption spectrum of the probe field. The coherence of the mechanical oscillator leads to split the peak in absorption in the probe field spectrum so that the phenomenon of optomechanically induced transparency (OMIT) is generated from the output probe field. In particular, the presence of nonlinearities with the degenerate OPA and the higher order excited atoms can affect significantly the width of the transparency windows, providing an additional flexibility for controlling optical properties. Furthermore, in the presence of the degenerate OPA, the optical-response properties for the probe field become phase-sensitive so that a tunable switch from slow to fast light can be realized. PMID:27725763

  18. Unperceivable noise to active light touch effects on fast postural sway.

    PubMed

    Kimura, Tetsuya; Kouzaki, Motoki; Masani, Kei; Moritani, Toshio

    2012-01-06

    Human postural sway during quiet standing is reduced when a fingertip lightly touches a stable surface. The tactile feedback information from the fingertip has been considered responsible for this effect of light touch. Studies have shown that a noise-like minute stimulation to the sensory system can improve the system's weak signal detection. In the present study, we investigated whether a noise-like unperceivable vibration on the fingertip enhances its tactile sensation and facilitates the effect of light touch during quiet standing. Thirteen volunteers maintained quiet standing while lightly touching a touch surface with the index fingertip. Based on each subject's vibrotactile threshold (VT), a noise-like vibration was applied to the touch surface at amplitudes under (0.5VT) or at VT (1.0VT), in addition to the normal light touch condition (no vibration, 0VT). The results showed that the mean velocities of the foot center of pressure (CoP) in both the anteroposterior (AP) and mediolateral (ML) directions were significantly reduced at 0.5VT compared to 0VT and 1.0VT (P<0.05), while there was no significant difference between 1.0VT and 0VT (P>0.05). Frequency analysis of CoP revealed that the power of high-frequency fluctuation (1-10Hz) was significantly reduced at 0.5VT (P<0.05), whereas no significant change was observed in that of low-frequency sway (below 1Hz) (P>0.05). These results indicate that an unperceivable noise-like vibration can facilitate the effect of light touch on postural stability, by further reducing fast postural sway.

  19. Shapes of internally mixed hygroscopic aerosol particles after deliquescence, and their effect on light scattering

    NASA Astrophysics Data System (ADS)

    Adachi, Kouji; Freney, Evelyn J.; Buseck, Peter R.

    2011-07-01

    Hygroscopic aerosol particles change the magnitude of light scattering through condensation and evaporation of water vapor. We collected aerosol particles from two megacities and observed the particle shapes at various values of relative humidity (RH) using an environmental cell within a transmission electron microscope. Many Mexico City samples had sulfate particles that were embedded within weakly hygroscopic organic aerosol, whereas the Los Angeles samples mainly consisted of externally mixed sulfate particles. For the Mexico City samples, when the RH was increased in the microscope, only the sulfate parts deliquesced, but the entire particle did not become spherical, i.e., particles containing deliquescent phases do not necessarily become spherical upon deliquescence. This result conflicts with the assumption used in many models, i.e., that deliquesced particles become spherical. Using a discrete-dipole approximation to calculate light scattering of simulated particles that resemble the observed ones, we show that, for particles >1.0 μm, the spherical-shape assumption used in Mie theory underestimates the light scattering by ˜50%, with the exact value depending on the sizes and relative volumes of the constituent phases.

  20. Intensity and polarization of light scattered by size distributions of randomly oriented nonspherical particles

    NASA Technical Reports Server (NTRS)

    Mishchenko, M. I.; Travis, L. D.

    1993-01-01

    Calculations of light scattering by small particles are important in many diverse fields of science and engineering. In many cases of practical interest, scattering particles are nonspherical and are distributed over sizes and orientations. However, accurate light scattering computations for ensembles of nonspherical particles are difficult and time-consuming, and the literature in which such calculations are reported is rather scarce. In this paper, the T-matrix approach, as extended recently to randomly oriented particles, is used to calculate rigorously light scattering by size distributions of randomly oriented axially symmetric particles. To model the variation of particle sizes in real ensembles, we use a power law distribution typical of some terrestrial aerosols. Contour plots of intensity and degree of linear polarization for polydisperse prolate and oblate spheroids of different aspect ratios and effective equivalent-sphere size parameters from 0 to 10 are calculated and compared with calculations for equivalent spheres. The angular scattering behavior of nonspherical polydispersions is found to be greatly different from that of spheres, while the scattering properties of oblate and prolate spheroids of the same aspect ratio are similar. With increasing particle size, both intensity and polarization become more shape-dependent. In general, nonspherical particles are stronger side scatterers and weaker backscatterers than equivalent spheres. With increasing aspect ratio of nonspherical particles polarization tends to be predominantly positive. Possible effects of particle nonsphericity on optical remote sensing of atmospheric aerosols are discussed.

  1. Laboratory Evaluation of Light Obscuration Particle Counters used to Establish use Limits for Aviation Fuel

    DTIC Science & Technology

    2015-12-01

    Establish use Limits for Aviation Fuel December 2015 UNCLASSIFIED UNCLASSIFIED Joel Schmitigal 27480 Standard Form 298 (Rev. 8-98) Prescribed by ANSI-Std...To) 4. TITLE AND SUBTITLE Laboratory Evaluation of Light Obscuration Particle Counters used to Establish use Limits for Aviation Fuel 5a. CONTRACT...laboratory evaluations of automatic light obscuration particle counters to develop limits for aviation fuel cleanliness. The laboratory evaluations

  2. An Analytical Approach for Fast Recovery of the LSI Properties in Magnetic Particle Imaging

    PubMed Central

    Jabbari Asl, Hamed

    2016-01-01

    Linearity and shift invariance (LSI) characteristics of magnetic particle imaging (MPI) are important properties for quantitative medical diagnosis applications. The MPI image equations have been theoretically shown to exhibit LSI; however, in practice, the necessary filtering action removes the first harmonic information, which destroys the LSI characteristics. This lost information can be constant in the x-space reconstruction method. Available recovery algorithms, which are based on signal matching of multiple partial field of views (pFOVs), require much processing time and a priori information at the start of imaging. In this paper, a fast analytical recovery algorithm is proposed to restore the LSI properties of the x-space MPI images, representable as an image of discrete concentrations of magnetic material. The method utilizes the one-dimensional (1D) x-space imaging kernel and properties of the image and lost image equations. The approach does not require overlapping of pFOVs, and its complexity depends only on a small-sized system of linear equations; therefore, it can reduce the processing time. Moreover, the algorithm only needs a priori information which can be obtained at one imaging process. Considering different particle distributions, several simulations are conducted, and results of 1D and 2D imaging demonstrate the effectiveness of the proposed approach. PMID:27847513

  3. Visible light photon counters (VLPCs) for high rate tracking medical imaging and particle astrophysics

    SciTech Connect

    Atac, M.

    1998-02-01

    This paper is on the operation principles of the Visible Light Photon Counters (VLPCs), application to high luminosity-high multiplicity tracking for High Energy Charged Particle Physics, and application to Medical Imaging and Particle Astrophysics. The VLPCs as Solid State Photomultipliers (SSPMS) with high quantum efficiency can detect down to single photons very efficiently with excellent time resolution and high avalanche gains.

  4. A simple and tunable switch between slow- and fast-light in two signal modes with an optomechanical system

    NASA Astrophysics Data System (ADS)

    Ma, Peng-Cheng; Yan, Lei-Lei; Chen, Gui-Bin; Li, Xiao-Wei; Zhan, You-Bang

    2016-12-01

    The control of slow and fast light propagation is a challenging task. Here, we theoretically study the dynamics of a driven optomechanical cavity coupled to a charged nanomechanical resonator (NR) via Coulomb interaction. We find that the tunable switch between slow- and fast-light for two signal modes can be observed from the output field by adjusting the laser-cavity detuning in this system. Moreover, the frequencies of two signal light can be tuned by Coulomb coupling strength. In comparison with previous schemes, the clear advantage of our scheme is that we can simply switch from fast- to slow-light in two signal modes by only adjusting the laser-cavity deturning from Δ ={ω1} to Δ =-{ω1} . The proposal may have potential application in optical router and quantum optomechanical memory.

  5. Photoelectric charging of dust particles: Effect of spontaneous and light induced field emission of electrons

    SciTech Connect

    Sodha, M. S.; Dixit, A.

    2009-09-07

    The authors have analyzed the charging of dust particles in a plasma, taking into account the electron/ion currents to the particles, electron/ion generation and recombination, electric field emission, photoelectric emission and photoelectric field emission of electrons under the influence of light irradiation; the irradiance has been assumed to be at a level, which lets the particles retain the negative sign of the charge. Numerical results and discussion conclude the papers.

  6. Application of the combinative particle size reduction technology H 42 to produce fast dissolving glibenclamide tablets.

    PubMed

    Salazar, Jaime; Müller, Rainer H; Möschwitzer, Jan P

    2013-07-16

    Standard particle size reduction techniques such as high pressure homogenization or wet bead milling are frequently used in the production of nanosuspensions. The need for micronized starting material and long process times are their evident disadvantages. Combinative particle size reduction technologies have been developed to overcome the drawbacks of the standard techniques. The H 42 combinative technology consists of a drug pre-treatment by means of spray-drying followed by standard high pressure homogenization. In the present paper, spray-drying process parameters influencing the diminution effectiveness, such as drug and surfactant concentration, were systematically analyzed. Subsequently, the untreated and pre-treated drug powders were homogenized for 20 cycles at 1500 bar. For untreated, micronized glibenclamide, the particle size analysis revealed a mean particle size of 772 nm and volume-based size distribution values of 2.686 μm (d50%) and 14.423 μm (d90%). The use of pre-treated material (10:1 glibenclamide/docusate sodium salt ratio spray-dried as ethanolic solution) resulted in a mean particle size of 236 nm and volume-based size distribution values of 0.131 μm (d50%) and 0.285 μm (d90%). These results were markedly improved compared to the standard process. The nanosuspensions were further transferred into tablet formulations. Wet granulation, freeze-drying and spray-drying were investigated as downstream methods to produce dry intermediates. Regarding the dissolution rate, the rank order of the downstream processes was as follows: Spray-drying>freeze-drying>wet granulation. The best drug release (90% within 10 min) was obtained for tablets produced with spray-dried nanosuspension containing 2% mannitol as matrix former. In comparison, the tablets processed with micronized glibenclamide showed a drug release of only 26% after 10 min. The H 42 combinative technology could be successfully applied in the production of small drug nanocrystals. A

  7. Development of Spectral and Atomic Models for Diagnosing Energetic Particle Characteristics in Fast Ignition Experiments

    SciTech Connect

    MacFarlane, Joseph J

    2009-08-07

    This Final Report summarizes work performed under DOE STTR Phase II Grant No. DE-FG02-05ER86258 during the project period from August 2006 to August 2009. The project, “Development of Spectral and Atomic Models for Diagnosing Energetic Particle Characteristics in Fast Ignition Experiments,” was led by Prism Computational Sciences (Madison, WI), and involved collaboration with subcontractors University of Nevada-Reno and Voss Scientific (Albuquerque, NM). In this project, we have: Developed and implemented a multi-dimensional, multi-frequency radiation transport model in the LSP hybrid fluid-PIC (particle-in-cell) code [1,2]. Updated the LSP code to support the use of accurate equation-of-state (EOS) tables generated by Prism’s PROPACEOS [3] code to compute more accurate temperatures in high energy density physics (HEDP) plasmas. Updated LSP to support the use of Prism’s multi-frequency opacity tables. Generated equation of state and opacity data for LSP simulations for several materials being used in plasma jet experimental studies. Developed and implemented parallel processing techniques for the radiation physics algorithms in LSP. Benchmarked the new radiation transport and radiation physics algorithms in LSP and compared simulation results with analytic solutions and results from numerical radiation-hydrodynamics calculations. Performed simulations using Prism radiation physics codes to address issues related to radiative cooling and ionization dynamics in plasma jet experiments. Performed simulations to study the effects of radiation transport and radiation losses due to electrode contaminants in plasma jet experiments. Updated the LSP code to generate output using NetCDF to provide a better, more flexible interface to SPECT3D [4] in order to post-process LSP output. Updated the SPECT3D code to better support the post-processing of large-scale 2-D and 3-D datasets generated by simulation codes such as LSP. Updated atomic physics modeling to provide for

  8. Slow and fast light using nonlinear processes in semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Pesala, Bala Subrahmanyam

    Ability to control the velocity of light is usually referred to as slow or fast light depending on whether the group velocity of light is reduced or increased. The slowing of light as it passes through the glass to 2/3rd its original value is a well known phenomenon. This slowing down happens due to the interaction of light with the electrons in the medium. As a general principle, stronger the interaction, larger is the reduction in velocity. Recently, a fascinating field has emerged with the objective of not only slowing down the velocity of light but also speeding it up as it goes through the medium by enhancing light-matter interaction. This unprecedented control opens up several exciting applications in various scientific disciplines ranging from nonlinear science, RF photonics to all-optical networks. Initial experiments succeeded in reducing the velocity of light more than a million times to a very impressive 17 m/s. This speed reduction is extremely useful to enhance various nonlinear processes. For RF photonic applications including phased array antennas and tunable filters, control of phase velocity of light is required while control of group velocity serves various functionalities including packet synchronization and contention resolution in an optical buffer. Within the last 10 years, several material systems have been proposed and investigated for this purpose. Schemes based on semiconductor systems for achieving slow and fast light has the advantage of extremely high speed and electrical control. In addition, they are compact, operate at room temperature and can be easily integrated with other optical subsystems. In this work, we propose to use nonlinear processes in semiconductor optical amplifiers (SOAs) for the purpose of controlling the velocity of light. The versatility of the physical processes present in SOAs enables the control of optical signals ranging from 1GHz to larger than 1000 GHz (1 THz). First, we experimentally demonstrate both

  9. Interferometric apparatus and method for detection and characterization of particles using light scattered therefrom

    DOEpatents

    Johnston, Roger G.

    1988-01-01

    Interferometric apparatus and method for detection and characterization of particles using light scattered therefrom. Differential phase measurements on scattered light from particles are possible using the two-frequency Zeeman effect laser which emits two frequencies of radiation 250 kHz apart. Excellent discrimination and reproducibility for various pure pollen and bacterial samples in suspension have been observed with a single polarization element. Additionally, a 250 kHz beat frequency was recorded from an individual particle traversing the focused output from the laser in a flow cytometer.

  10. Apparatus and method for detection and characterization of particles using light scattered therefrom

    DOEpatents

    Johnston, R.G.

    1987-03-23

    Apparatus and method for detection and characterization of particles using light scattered therefrom. Differential phase measurements on scattered light from particles are possible using the two-frequency Zeeman effect laser which emits two frequencies of radiation 250 kHz apart. Excellent discrimination and reproducibility for various pure pollen and bacterial samples in suspension have been observed with a single polarization element. Additionally, a 250 kHz beat frequency was recorded from an individual particle traversing the focused output from the laser in a flow cytometer. 13 figs.

  11. Investigation of light scattering as a technique for detecting discrete soot particles in a luminous flame

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The practicability of using a classical light-scattering technique, involving comparison of angular scattering intensity patterns with theoretically determined Mie and Rayleight patterns, to detect discrete soot particles (diameter less than 50 nm) in premixed propane/air and propane/oxygen-helium flames is considered. The experimental apparatus employed in this investigation included a laser light source, a flat-flame burner, specially coated optics, a cooled photomultiplier detector, and a lock-in voltmeter readout. Although large, agglomerated soot particles were detected and sized, it was not possible to detect small, discrete particles. The limiting factor appears to be background scattering by the system's optics.

  12. Influence of fast and slow alkali myosin light chain isoforms on the kinetics of stretch-induced force transients of fast-twitch type IIA fibres of rat.

    PubMed

    Andruchov, Oleg; Galler, Stefan

    2008-03-01

    This study contributes to understand the physiological role of slow myosin light chain isoforms in fast-twitch type IIA fibres of skeletal muscle. These isoforms are often attached to the myosin necks of rat type IIA fibres, whereby the slow alkali myosin light chain isoform MLC1s is much more frequent and abundant than the slow regulatory myosin light chain isoform MLC2s. In the present study, single-skinned rat type IIA fibres were maximally Ca(2+) activated and subjected to stepwise stretches for causing a perturbation of myosin head pulling cycles. From the time course of the resulting force transients, myosin head kinetics was deduced. Fibres containing MLC1s exhibited slower kinetics independently of the presence or absence of MLC2s. At the maximal MLC1s concentration of about 75%, the slowing was about 40%. The slowing effect of MLC1s is possibly due to differences in the myosin heavy chain binding sites of the fast and slow alkali MLC isoforms, which changes the rigidity of the myosin neck. Compared with the impact of myosin heavy chain isoforms in various fast-twitch fibre types, the influence of MLC1s on myosin head kinetics of type IIA fibres is much smaller. In conclusion, the physiological role of fast and slow MLC isoforms in type IIA fibres is a fine-tuning of the myosin head kinetics.

  13. Investigation of Very Fast Light Detectors: Silicon Photomultiplier and Micro PMT for a Cosmic Ray Array

    NASA Astrophysics Data System (ADS)

    Cervantes, Omar; Reyes, Liliana; Hooks, Tyler; Perez, Luis; Ritt, Stefan

    2016-03-01

    To construct a cosmic detector array using 4 scintillation detectors, we investigated 2 recent light sensor technologies from Hamamatsu, as possible readout detectors. First, we investigated several homemade versions of the multipixel photon counter (MPPC) light sensors. These detectors were either biased with internal or external high voltage power supplies. We made extensive measurements to confirm for the coincidence of the MPPC devices. Each sensor is coupled to a wavelength shifting fiber (WSF) that is embedded along a plastic scintillator sheet (30cmx60cmx1/4''). Using energetic cosmic rays, we evaluated several of these homemade detector modules placed above one another in a light proof enclosure. Next, we assembled 2 miniaturized micro photomultiplier (micro PMT), a device recently marketed by Hamamatsu. These sensors showed very fast response times. With 3 WSF embedded in scintillator sheets, we performed coincidence experiments. The detector waveforms were captured using the 5GS/sec domino ring sampler, the DRS4 and our workflow using the CERN PAW package and data analysis results would be presented. Title V Grant.

  14. Ultraviolet Light Enhances the Bovine Serum Albumin Fixation for Acid Fast Bacilli Stain

    PubMed Central

    Lai, Pei-Yin; Lee, Shih-Yi; Chou, Yu-Ching; Fu, Yung-Chieh; Wu, Chen-Cheng; Chiueh, Tzong-Shi

    2014-01-01

    The use of a liquid culture system such as MGIT broth has greatly improved the sensitivity of isolating mycobacteria in clinical laboratories. Microscopic visualization of acid fast bacilli (AFB) in the culture positive MGIT broth remains the first routine step for rapidly indicating the presence of mycobacteria. We modified an ultraviolet (UV) light fixation process to increase AFB cells adherence to the slide. The retained haze proportion of a 1-cm circle marked area on the smear slide was quantified after the staining procedure indicating the adherence degree of AFB cells. More AFB cells were preserved on the slide after exposure to UV light of either germicidal lamp or UV crosslinker in a time-dependent manner. We demonstrated both the bovine serum albumin (BSA) in MGIT media and UV light exposure were required for enhancing fixation of AFB cells. While applying to AFB stains for 302 AFB positive MGIT broths in clinics, more AFB cells were retained and observed on smear slides prepared by the modified fixation procedure rather than by the conventional method. The modified fixation procedure was thus recommended for improving the sensitivity of microscopic diagnosis of AFB cells in culture positive MGIT broth. PMID:24586725

  15. Fast evolving pair-instability supernova models: evolution, explosion, light curves

    NASA Astrophysics Data System (ADS)

    Kozyreva, Alexandra; Gilmer, Matthew; Hirschi, Raphael; Fröhlich, Carla; Blinnikov, Sergey; Wollaeger, Ryan T.; Noebauer, Ulrich M.; van Rossum, Daniel R.; Heger, Alexander; Even, Wesley P.; Waldman, Roni; Tolstov, Alexey; Chatzopoulos, Emmanouil; Sorokina, Elena

    2017-01-01

    With an increasing number of superluminous supernovae (SLSNe) discovered, the question of their origin remains open and causes heated debates in the supernova community. Currently, there are three proposed mechanisms for SLSNe: (1) pair-instability supernovae (PISNe), (2) magnetar-driven supernovae and (3) models in which the supernova ejecta interacts with a circumstellar material ejected before the explosion. Based on current observations of SLSNe, the PISN origin has been disfavoured for a number of reasons. Many PISN models provide overly broad light curves and too reddened spectra, because of massive ejecta and a high amount of nickel. In the current study, we re-examine PISN properties using progenitor models computed with the GENEC code. We calculate supernova explosions with FLASH and light-curve evolution with the radiation hydrodynamics code STELLA. We find that high-mass models (200 and 250 M⊙) at relatively high metallicity (Z = 0.001) do not retain hydrogen in the outer layers and produce relatively fast evolving PISNe Type I and might be suitable to explain some SLSNe. We also investigate uncertainties in light-curve modelling due to codes, opacities, the nickel-bubble effect and progenitor structure and composition.

  16. Single-particle evanescent light scattering simulations for total internal reflection microscopy

    NASA Astrophysics Data System (ADS)

    Helden, Laurent; Eremina, Elena; Riefler, Norbert; Hertlein, Christopher; Bechinger, Clemens; Eremin, Yuri; Wriedt, Thomas

    2006-10-01

    We simulate and measure light scattering of a micrometer-sized spherical particle suspended in solution close to a glass substrate. The model, based on the discrete sources method, is developed to describe the experimental situation of total internal reflection microscopy experiments; i.e., the particle is illuminated by an evanescent light field originating from the glass-solvent interface. In contrast to the well-established assumption of a simple exponential decay of the scattering intensity with distance, we demonstrate significant deviations for a certain range of penetration depths and polarization states of the incident light.

  17. Single-particle evanescent light scattering simulations for total internal reflection microscopy.

    PubMed

    Helden, Laurent; Eremina, Elena; Riefler, Norbert; Hertlein, Christopher; Bechinger, Clemens; Eremin, Yuri; Wriedt, Thomas

    2006-10-01

    We simulate and measure light scattering of a micrometer-sized spherical particle suspended in solution close to a glass substrate. The model, based on the discrete sources method, is developed to describe the experimental situation of total internal reflection microscopy experiments; i.e., the particle is illuminated by an evanescent light field originating from the glass-solvent interface. In contrast to the well-established assumption of a simple exponential decay of the scattering intensity with distance, we demonstrate significant deviations for a certain range of penetration depths and polarization states of the incident light.

  18. Light-Absorbing Carbonaceous Particles: Chemical Composition and Its Implications for Direct Climate Forcing

    NASA Astrophysics Data System (ADS)

    Hemming, B. L.; Henze, D. K.; Akhtar, F.; Pinder, R. W.; Loughlin, D. H.

    2012-12-01

    Carbonaceous particles are understood to play a substantial role in direct climate forcing, but current estimates of this effect depend on very simple assumptions concerning the light absorbing properties of the materials from these particles are formed. The practice, to date is to classify all black (graphitic, combustion-derived) carbon as having a single mass absorption coefficient, with all other carbon consider only slightly- or completely non-absorbing. The substantial literature produced by the combustion sciences, biomass energy, and paper processing research communities suggest that particle carbon comprises a wide array of light-absorbing compounds having distinct light-absorbing properties of varying degrees of extinction efficiency. These materials accumulate in the particle phase, and are emitted at all stages of solid fuel pyrolysis and combustion. Filter-based measurements of carbonaceous PM collected from various solid fuel combustion sources show substantial variability in solar wavelength-dependent light absorption, with Angstrom Exponents ranging from as high as 12, down to 1. In this presentation, the fuel and combustion variables determining the degree of light absorption by carbonaceous particle components will be discussed, followed by a presentation of the results of a study applying the adjoint of the GEOS-Chem chemical transport model to an estimation of the sensitivity of direct forcing by carbonaceous particles to variation in burning phase-specific AE values.

  19. Small angle light scattering characterization of single micrometric particles in microfluidic flows

    NASA Astrophysics Data System (ADS)

    Dannhauser, David; Romeo, Giovanni; Causa, Filippo; Netti, Paolo A.

    2013-04-01

    A CCD-camera based small angle light scattering (SALS) apparatus has been used to characterize single micrometric particles flowing in a micro-channel. The measured scattering vector spans the range 2x10-2 - 6:8x101μm-1. The incident laser light is collimated to a spot of about 50 μm in diameter at the sample position with a divergence lower than 0.045 rad. Such small collimated laser beam opens the possibility to perform on-line SALS of micron-sized particles flowing in micro-channels. By properly designing the micro-channel and using a viscoelastic liquid as suspending medium we are able to realize a precise 3D focusing of the target particles. The forward scattering emitted from the particle is collected by a lens with high numerical aperture. At the focal point of that lens a homemade beam stop is blocking the incident light. Finally, a second lens maps the scattered light on the CCD sensor, allowing to obtain far field images on short distances. Measurements with mono-disperse polystyrene particles, both in quiescent and in-flow conditions have been realized. Experiments in-flow allow to measure the single particle scattering. Results are validated by comparison with calculations based on the Lorenz-Mie theory. The quality of the measured intensity profiles confirms the possibility to use our apparatus in real multiplex applications, with particles down to 1 μm in radius.

  20. Monte Carlo simulation of light reflection from cosmetic powder particles near the human skin surface.

    PubMed

    Okamoto, Takashi; Kumagawa, Tatsuya; Motoda, Masafumi; Igarashi, Takanori; Nakao, Keisuke

    2013-06-01

    The reflection and scattering properties of light incident on human skin covered with powder particles have been investigated. A three-layer skin structure with a pigmented area is modeled, and the propagation of light in the skin's layers and in a layer of particles near the skin's surface is simulated using the Monte Carlo method. Assuming that only single scattering of light occurs in the powder layer, the simulation results show that the reflection spectra of light from the skin change with the size of powder particles. The color difference between normal and discolored skin is found to decrease considerably when powder particles with a diameter of approximately 0.25 μm are present near the skin's surface. The effects of the medium surrounding the particles, and the influence of the distribution of particle size (polydispersity), are also examined. It is shown that a surrounding medium with a refractive index close to that of the skin substantially suppresses the extreme spectral changes caused by the powder particles covering the skin surface.

  1. Comparison of the Light Charged Particles on Scatter Radiation Dose in Thyroid Hadron Therapy

    PubMed Central

    Azizi, M; Mowlavi, AA

    2014-01-01

    Background: Hadron therapy is a novel technique of cancer radiation therapy which employs charged particles beams, 1H and light ions in particular. Due to their physical and radiobiological properties, they allow one to obtain a more conformal treatment, sparing better the healthy tissues located in proximity of the tumor and allowing a higher control of the disease. Objective: As it is well known, these light particles can interact with nuclei in the tissue, and produce the different secondary particles such as neutron and photon. These particles can damage specially the critical organs behind of thyroid gland. Methods: In this research, we simulated neck geometry by MCNPX code and calculated the light particles dose at distance of 2.14 cm in thyroid gland, for different particles beam: 1H, 2H, 3He, and 4He. Thyroid treatment is important because the spine and vertebrae is situated right behind to the thyroid gland on the posterior side. Results: The results show that 2H has the most total flux for photon and neutron, 1.944E-3 and 1.7666E-2, respectively. Whereas 1H and 3He have best conditions, 8.88609E-4 and 1.35431E-3 for photon, 4.90506E-4 and 4.34057E-3 for neutron, respectively. The same calculation has obtained for energy depositions for these particles. Conclusion: In this research, we investigated that which of these light particles can deliver the maximum dose to the normal tissues and the minimum dose to the tumor. By comparing these results for the mentioned light particles, we find out 1H and 3He is the best therapy choices for thyroid glands whereas 2H is the worst. PMID:25505774

  2. Laser Light Scattering with Multiple Scattering Suppression Used to Measure Particle Sizes

    NASA Technical Reports Server (NTRS)

    Meyer, William V.; Tin, Padetha; Lock, James A.; Cannell, David S.; Smart, Anthony E.; Taylor, Thomas W.

    1999-01-01

    Laser light scattering is the technique of choice for noninvasively sizing particles in a fluid. The members of the Advanced Technology Development (ATD) project in laser light scattering at the NASA Lewis Research Center have invented, tested, and recently enhanced a simple and elegant way to extend the concentration range of this standard laboratory particle-sizing technique by several orders of magnitude. With this technique, particles from 3 nm to 3 mm can be measured in a solution. Recently, laser light scattering evolved to successfully size particles in both clear solutions and concentrated milky-white solutions. The enhanced technique uses the property of light that causes it to form tall interference patterns at right angles to the scattering plane (perpendicular to the laser beam) when it is scattered from a narrow laser beam. Such multiple-scattered light forms a broad fuzzy halo around the focused beam, which, in turn, forms short interference patterns. By placing two fiber optics on top of each other and perpendicular to the laser beam (see the drawing), and then cross-correlating the signals they produce, only the tall interference patterns formed by singly scattered light are detected. To restate this, unless the two fiber optics see the same interference pattern, the scattered light is not incorporated into the signal. With this technique, only singly scattered light is seen (multiple-scattered light is rejected) because only singly scattered light has an interference pattern tall enough to span both of the fiber-optic pickups. This technique is simple to use, easy to align, and works at any angle. Placing a vertical slit in front of the signal collection fibers enhanced this approach. The slit serves as an optical mask, and it significantly shortens the time needed to collect good data by selectively masking out much of the unwanted light before cross-correlation is applied.

  3. Fast X-ray imaging at beamline I13L at Diamond Light Source

    NASA Astrophysics Data System (ADS)

    De Fanis, A.; Pešić, Z. D.; Wagner, U.; Rau, C.

    2013-03-01

    The imaging branch of the dual-branch beamline I13L at Diamond Light Source has been operational since April 2012. This branch is dedicated to hard X-ray imaging (in-line phase contrast radiography and tomography, and full-field microscopy), with energies in the ranges 6-30keV. At present we aim to achieve spatial resolution of the order of 1 μm over a field of view of l-20mm2. This branch aims to excel at imaging experiment of fast dynamic processes, where it is of interest to have short exposure times and high frame rates. To accommodate for this, we prepared for the beamline to operate with "pink" beam to provide higher flux, an efficient detection system, and rapid data acquisition, transfer, and saving to storage. This contributed paper describes the present situation and illustrate the author's goal for the mid-future.

  4. Energy-efficient constellations design and fast decoding for space-collaborative MIMO visible light communications

    NASA Astrophysics Data System (ADS)

    Zhu, Yi-Jun; Liang, Wang-Feng; Wang, Chao; Wang, Wen-Ya

    2017-01-01

    In this paper, space-collaborative constellations (SCCs) for indoor multiple-input multiple-output (MIMO) visible light communication (VLC) systems are considered. Compared with traditional VLC MIMO techniques, such as repetition coding (RC), spatial modulation (SM) and spatial multiplexing (SMP), SCC achieves the minimum average optical power for a fixed minimum Euclidean distance. We have presented a unified SCC structure for 2×2 MIMO VLC systems and extended it to larger MIMO VLC systems with more transceivers. Specifically for 2×2 MIMO VLC, a fast decoding algorithm is developed with decoding complexity almost linear in terms of the square root of the cardinality of SCC, and the expressions of symbol error rate of SCC are presented. In addition, bit mappings similar to Gray mapping are proposed for SCC. Computer simulations are performed to verify the fast decoding algorithm and the performance of SCC, and the results demonstrate that the performance of SCC is better than those of RC, SM and SMP for indoor channels in general.

  5. Heterogeneous Combustion Particles with Distinctive Light-Absorbing and Light-Scattering Phases as Mimics of Internally-Mixed Ambient Atmospheric Particles

    NASA Astrophysics Data System (ADS)

    Conny, J. M.; Ma, X.; Gunn, L. R.

    2011-12-01

    Particles with heterogeneously-distributed light-absorbing and light-scattering phases were generated from incomplete combustion or thermal decomposition to mimic real atmospheric particles with distinctive optical properties. Individual particles and particle populations were characterized microscopically. The purpose was to examine how optical property measurements of internally-mixed ambient air particles might vary based on the properties of laboratory-generated particles produced under controlled conditions. The project is an initial stage in producing reference samples for calibrating instrumentation for monitoring climatically-important atmospheric aerosols. Binary-phase particles containing black carbon (BC) and a metal or a metal oxide phase were generated from the thermal decomposition or partial combustion of liquid fuels at a variety of temperatures from 600 °C to 1100 °C. Fuels included mixtures of toluene or isooctane and iron pentacarbonyl or titanium tetrachloride. Scanning electron microscopy with energy-dispersive x-ray spectroscopy revealed that burning the fuels at different temperatures resulted in distinctive differences in morphology and carbon vs. metal/metal oxide composition. Particles from toluene/Fe(CO)5 thermal decomposition exhibited aggregated morphologies that were classified as dendritic, soot-like, globular, or composited (dendritic-globular). Particles from isooctane/TiCl4 combustion were typically spherical with surface adducts or aggregates. Diameters of the BC/TiO2 particles averaged 0.68 μm to 0.70 μm. Regardless of combustion temperature, the most abundant particles in each BC/TiO2 sample had an aspect ratio of 1.2. However, for the 600 °C and 900 °C samples the distribution of aspect ratios was skewed toward much larger ratios suggesting significant chainlike aggregation. Carbon and titanium compositions (wt.) for the 600 °C sample were 12 % and 53 %, respectively. In contrast, the composition trended in the opposite

  6. LOAC (Light Optical Particle Counter): a new small aerosol counter with particle characterization capabilities for surface and airborne measurements

    NASA Astrophysics Data System (ADS)

    Renard, Jean-Baptiste; Berthet, Gwenael; Jégou, Fabrice; Jeannot, Matthieu; Jourdain, Line; Dulac, François; Mallet, Marc; Dupont, Jean-Charles; Thaury, Claire; Tonnelier, Thierry; Verdier, Nicolas; Charpentier, Patrick

    2013-04-01

    The determination of the size distribution of tropospheric and stratospheric aerosols with conventional optical counters is difficult when different natures of particles are present (droplets, soot, mineral dust, secondary organic or mineral particles...). Also, a light and cheap aerosol counter that can be used at ground, onboard drones or launched under all kinds of atmospheric balloons can be very useful during specific events as volcanic plumes, desert dust transport or local pollution episodes. These goals can be achieved thanks to a new generation of aerosol counter, called LOAC (Light Optical Aerosol Counter). The instrument was developed in the frame of a cooperation between French scientific laboratories (CNRS), the Environnement-SA and MeteoModem companies and the French Space Agency (CNES). LOAC is a small optical particle counter/sizer of ~250 grams, having a low electrical power consumption. The measurements are conducted at two scattering angles. The first one, at 12°, is used to determine the aerosol particle concentrations in 19 size classes within a diameter range of 0.3-100 micrometerers. At such an angle close to forward scattering, the signal is much more intense and the measurements are the least sensitive to the particle nature. The second angle is at 60°, where the scattered light is strongly dependent on the particle refractive index and thus on the nature of the aerosols. The ratio of the measurements at the two angles is used to discriminate between the different types of particles dominating the nature of the aerosol particles in the different size classes. The sensor particularly discriminates wet or liquid particles, soil dust and soot. Since 2011, we have operated LOAC in various environments (Arctic, Mediterranean, urban and peri-urban…) under different kinds of balloons including zero pressure stratospheric, tethered, drifting tropospheric, and meteorological sounding balloons. For the last case, the total weight of the gondola

  7. B decays into light scalar particles and glueball

    NASA Astrophysics Data System (ADS)

    Minkowski, P.; Ochs, W.

    2005-01-01

    The recent observations of f 0(980) in charmless B decays motivate further studies of scalar particle and glueball production in these processes. Amplitudes for charmless two-body B decays involving the members of the scalar nonet are presented based on the symmetries of the dominant penguin contribution. Different scenarios for the lightest scalar nonet are investigated in view of the presently available data. We describe the evidence from B decays for f 0(1500) with a flavor octet like mixing and the hints towards the members of the qbar{q} nonet of lowest mass. There is further support for the hypothesis of a broad 0 + + glueball acting as coherent background especially in Bto Koverline K K. The estimated B decay rates into gluonic mesons represent a sizable fraction of the theoretically derived decay rate for {bto sg}.

  8. Integral light-scattering and absorption characteristics of large, nonspherical particles

    NASA Astrophysics Data System (ADS)

    Kokhanovsky, Alexander A.; Macke, Andreas

    1997-11-01

    We obtain and analyze simple analytical formulas for asymmetry parameters and absorption cross sections of large, nonspherical particles. The formulas are based on the asymptotic properties of these characteristics at strong and weak absorption of radiation inside particles. The absorption cross section depends on parameter , which determines the value of the light-absorption cross section for weakly absorbing particles. It is larger for nonspherical scatterers. The asymmetry parameter depends on two parameters. The first is the asymmetry parameter g0 of a nonspherical, transparent particle with the same shape as an absorbing one. The second parameter, , determines the strength of the influence of light absorption on the value of the asymmetry parameter. Parameter is larger for nonspherical particles. One can find these three parameters ( , g0 , and ) using a ray-tracing code (RTC) for nonabsorbing and weakly absorbing particles. The RTC can then be used to check the accuracy of the equations at any absorption for hexagonal cylinders and spheroids. It is found that the error of computing the absorption cross section and 1 -g (g is the asymmetry parameter) is less than 20% at the refractive index of particles n = 1.333. Values for asymmetry parameters of large, nonabsorbing, spheroidal particles with different aspect ratios are tabulated for the first time to our knowledge. They do not depend on the size of particles and can serve as an independent check of the accuracy of T-matrix codes for large parameters.

  9. Trapped fast particle destabilization of internal kink mode for the locally flattened q-profile with an inflection point

    NASA Astrophysics Data System (ADS)

    Wang, Xian-Qu; Zhang, Rui-Bin; Meng, Guo

    2016-07-01

    The destabilization of ideal internal kink modes by trapped fast particles in tokamak plasmas with a "shoulder"-like equilibrium current is investigated. It is found that energetic particle branch of the mode is unstable with the driving of fast-particle precession drifts and corresponds to a precessional fishbone. The mode with a low stability threshold is also more easily excited than the conventional precessional fishbone. This is different from earlier studies for the same equilibrium in which the magnetohydrodynamic (MHD) branch of the mode is stable. Furthermore, the stability and characteristic frequency of the mode are analyzed by solving the dispersion relation and comparing with the conventional fishbone. The results suggest that an equilibrium with a locally flattened q-profile, may be modified by localized current drive (or bootstrap current, etc.), is prone to the onset of the precessional fishbone branch of the mode.

  10. Exocytosis of Alphaherpesvirus Virions, Light Particles, and Glycoproteins Uses Constitutive Secretory Mechanisms

    PubMed Central

    Hogue, Ian B.; Scherer, Julian

    2016-01-01

    ABSTRACT Many molecular and cell biological details of the alphaherpesvirus assembly and egress pathway remain unclear. Recently we developed a live-cell fluorescence microscopy assay of pseudorabies virus (PRV) exocytosis, based on total internal reflection fluorescence (TIRF) microscopy and a virus-encoded pH-sensitive fluorescent probe. Here, we use this assay to distinguish three classes of viral exocytosis in a nonpolarized cell type: (i) trafficking of viral glycoproteins to the plasma membrane, (ii) exocytosis of viral light particles, and (iii) exocytosis of virions. We find that viral glycoproteins traffic to the cell surface in association with constitutive secretory Rab GTPases and exhibit free diffusion into the plasma membrane after exocytosis. Similarly, both virions and light particles use these same constitutive secretory mechanisms for egress from infected cells. Furthermore, we show that viral light particles are distinct from cellular exosomes. Together, these observations shed light on viral glycoprotein trafficking steps that precede virus particle assembly and reinforce the idea that virions and light particles share a biogenesis and trafficking pathway. PMID:27273828

  11. On the scattered light by dilute aqueous dispersions of nanogel particles.

    PubMed

    Callejas-Fernández, J; Ramos, J; Forcada, J; Moncho-Jordá, A

    2015-07-15

    This work deals with the scattered light by nanoparticles formed by a temperature sensitive polymer networks, namely nanogel particles. The scattered light is measured as a function of the scattering angle at temperatures below and above the volume phase transition temperature (VPTT) of nanogel particles. Our experimental results indicate that nanogel particles have a core-shell structure, formed by a uniform highly cross-linked core surrounded by a fuzzy shell where the polymer density decays to zero gradually for swollen configurations and sharply for shrunken states. The theoretical fitting of the experimental curves shows that the scattered light at low angle obeys a decreasing power law with the scattering vector, q(-α). The value of exponent α provides information about the radial dependence of the polymer density at the external shell of the particles for swollen nanogels, and about the degree of roughness of the surface for the case of shrunken nanogels. On the one hand, at low temperatures (below the VPPT), the nanogel particle is in the swollen state and the light scattering data show that its shell structure follows a fractal behaviour, with a polymer density that decays as r(α-3), where r is the distance to the particle centre. On the other hand, above the VPPT the results indicate that nanogel collapses into a core of uniform polymer density and a rough shell, with a fractal surface dimension of 2.5.

  12. Physicochemical and Light Scattering Studies on Ribosome Particles

    PubMed Central

    Scafati, Anna Reale; Stornaiuolo, Maria Rosaria; Novaro, Patrizia

    1971-01-01

    The light scattering technique has been used to measure the molecular weight of Escherichia coli ribosomes. The 30S, 50S, and 70S components have been isolated and purified. The refractive index increment dn/dc was found to have the same value, (0.20 ±0.01) cm3/g, for the three species. The molecular weights are (1.0 ±0.1)·106, (1.7 ±0.1)·106, and (2.9 ±0.3)·106 daltons respectively. Some information about the dimensions in solution (radius of gyration) and the interaction constant (second virial coefficient) have been obtained, and their significance is discussed. PMID:4931397

  13. Preface: Electromagnetic and Light Scattering by Nonspherical Particles XIV

    NASA Technical Reports Server (NTRS)

    Dubovik, Oleg; Labonnete, Laurent; Litvinov, Pavel; Parol, Frederic; Mischenko, Michael

    2014-01-01

    The 14th Electromagnetic and Light Scattering Conference (ELS-XIV) was held at the Universit de Lille 1, Villeneuve d'Ascq, France on 17-21 June 2013. The conference was attended by 200 scientists from 26 countries. The scientific program included one plenary lecture, 12 invited reviews, 100 contributed oral talks, and 86 poster presentations. The program, the abstracts, and the slides of the oral presentations are available at the conference web site http:www-loa.univ-lille1.frELS-XIV. To highlight one of the traditional ELS themes, the ELS-XIV featured a special session on Remote sensing of aerosols and clouds using polarimetric observations. This session was sponsored and co-organized by the French space agency CNES and attracted representatives from nearly all research teams word-wide involved in the development and active use of space-borne, in situ, and ground-based polarimetric observations.

  14. Laboratory measurements of light scattering properties of a carbonaceous interstellar dust analogue (soot particles)

    NASA Astrophysics Data System (ADS)

    Gogoi, Ankur; Choudhury, Amarjyoti; Ahmed, Gazi A.; Kashyap Boruah, Goutam

    2012-07-01

    Dust particles are present everywhere in the solar system, cometary comae and tail, interstellar dust clouds, asteroidal atmospheres and aerosols of other planetary atmospheres. The in situ sampling of the cometary dust composition conducted by CIDA (Cometary and Interstellar Dust Analyzer) and observed interstellar extinction and polarization revealed the presence of amorphous carbon, graphite, silicate, graphite, carbonates, metal oxide grains, ice particles and nanodiamonds in the interstellar medium. These particles act as the heterogeneous media to scatter solar or steller light. Observations and simulations of the light scattered by dust particles in cometary comae, interplanetary space and planetary regolith (or analogous terrestrial dust aggregates) is necessary to deduce the physical properties of their constituent particles and may lead to a better understanding of the formation of solar system. Notably the measurement of the volume scattering function (VSF) and degree of linear polarization (DLP) can be used to estimate parameters like size, porosity and roughness of the dust particles. In this contribution we report the design and fabrication of a laser based laboratory light scattering instrument that uses an array of 16 static Si photodetectors and can be operated at three different incident wavelengths (543.5 nm, 594.5 nm and 632.8 nm). The accuracy and the reliability of the setup were verified by conducting light scattering measurements on spherical water droplets and comparing the results with theoretical Mie calculations. The results of the measurements of the VSF and DLP of carbonaceous soot particles (agglomerates) that were sprayed in front of the laser beam by using an aerosol sprayer are presented. The experimental results were further analyzed by comparing with theoretically generated T-matrix and DDA (Discrete Dipole Approximation) plots with estimated parameters to yield more fruitful conclusions. Significant variations of the light

  15. Advanced laser particle accelerator development at LANL: from fast ignition to radiation oncology

    SciTech Connect

    Flippo, Kirk A; Gaillard, Sandrine A; Offermann, D T; Cobble, J A; Schmitt, M J; Gautier, D C; Kwan, T J T; Montgomery, D S; Kluge, Thomas; Bussmann, Micheal; Bartal, T; Beg, F N; Gall, B; Geissel, M; Korgan, G; Kovaleski, S; Lockard, T; Malekos, S; Schollmeier, M; Sentoku, Y; Cowan, T E

    2010-01-01

    Laser-plasma accelerated ion and electron beam sources are an emerging field with vast prospects, and promise many superior applications in a variety of fields such as hadron cancer therapy, compact radioisotope generation, table-top nuclear physics, laboratory astrophysics, nuclear forensics, waste transmutation, SN M detection, and inertial fusion energy. LANL is engaged in several projects seeking to develop compact high current and high energy ion and electron sources. We are especially interested in two specific applications: ion fast ignition/capsule perturbation and radiation oncology in conjunction with our partners at the ForschungsZentrum Dresden-Rossendorf (FZD). Laser-to-beam conversion efficiencies of over 10% are needed for practical applications, and we have already shown inherent etliciencies of >5% from flat foils, on Trident using only a 5th of the intensity and energy of the Nova Petawatt. With clever target designs, like structured curved cone targets, we have also been able to achieve major ion energy gains, leading to the highest energy laser-accelerated proton beams in the world. These new target designs promise to help usher in the next generation of particle sources realizing the potential of laser-accelerated beams.

  16. Deflections of Fast Coronal Mass Ejections and the Properties of Associated Solar Energetic Particle Events

    NASA Technical Reports Server (NTRS)

    Kahler, S. W.; Akiyama, S.; Gopalswamy, N.

    2012-01-01

    The onset times and peak intensities of solar energetic particle (SEP) events at Earth have long been thought to be influenced by the open magnetic fields of coronal holes (CHs). The original idea was that a CH lying between the solar SEP source region and the magnetic footpoint of the 1 AU observer would result in a delay in onset and/or a decrease in the peak intensity of that SEP event. Recently, Gopalswamy et al. showed that CHs near coronal mass ejection (CME) source regions can deflect fast CMEs from their expected trajectories in space, explaining the appearance of driverless shocks at 1 AU from CMEs ejected near solar central meridian (CM). This suggests that SEP events originating in CME-driven shocks may show variations attributable to CH deflections of the CME trajectories. Here, we use a CH magnetic force parameter to examine possible effects of CHs on the timing and intensities of 41 observed gradual E approx 20 MeV SEP events with CME source regions within 20 deg. of CM. We find no systematic CH effects on SEP event intensity profiles. Furthermore, we find no correlation between the CME leading-edge measured position angles and SEP event properties, suggesting that the widths of CME-driven shock sources of the SEPs are much larger than the CMEs. Independently of the SEP event properties, we do find evidence for significant CME deflections by CH fields in these events

  17. DEFLECTIONS OF FAST CORONAL MASS EJECTIONS AND THE PROPERTIES OF ASSOCIATED SOLAR ENERGETIC PARTICLE EVENTS

    SciTech Connect

    Kahler, S. W.; Akiyama, S.; Gopalswamy, N.

    2012-08-01

    The onset times and peak intensities of solar energetic particle (SEP) events at Earth have long been thought to be influenced by the open magnetic fields of coronal holes (CHs). The original idea was that a CH lying between the solar SEP source region and the magnetic footpoint of the 1 AU observer would result in a delay in onset and/or a decrease in the peak intensity of that SEP event. Recently, Gopalswamy et al. showed that CHs near coronal mass ejection (CME) source regions can deflect fast CMEs from their expected trajectories in space, explaining the appearance of driverless shocks at 1 AU from CMEs ejected near solar central meridian (CM). This suggests that SEP events originating in CME-driven shocks may show variations attributable to CH deflections of the CME trajectories. Here, we use a CH magnetic force parameter to examine possible effects of CHs on the timing and intensities of 41 observed gradual E {approx} 20 MeV SEP events with CME source regions within 20 Degree-Sign of CM. We find no systematic CH effects on SEP event intensity profiles. Furthermore, we find no correlation between the CME leading-edge measured position angles and SEP event properties, suggesting that the widths of CME-driven shock sources of the SEPs are much larger than the CMEs. Independently of the SEP event properties, we do find evidence for significant CME deflections by CH fields in these events.

  18. Advanced Laser Particle Accelerator Development at LANL: From Fast Ignition to Radiation Oncology

    SciTech Connect

    Flippo, K. A.; Offermann, D. T.; Cobble, J. A.; Schmitt, M. J.; Gautier, D. C.; Kwan, T. J.; Montgomery, D. S.; Gaillard, S. A.; Kluge, T.; Bussmann, M.; Cowan, T. E.; Bartal, T.; Beg, F. N.; Gall, B.; Kovaleski, S.; Geissel, M.; Schollmeier, M.; Korgan, G.; Malekos, S.; Lockard, T.

    2010-11-04

    Laser-plasma accelerated ion and electron beam sources are an emerging field with vast prospects, and promise many superior applications in a variety of fields such as hadron cancer therapy, compact radioisotope generation, table-top nuclear physics, laboratory astrophysics, nuclear forensics, waste transmutation, Special Nuclear Material (SNM) detection, and inertial fusion energy. LANL is engaged in several projects seeking to develop compact high-current and high-energy ion and electron sources. We are especially interested in two specific applications: ion fast ignition/capsule perturbation and radiation oncology. Laser-to-beam conversion efficiencies of over 10% are needed for practical applications, and we have already shown inherent efficiencies of >5% from flat foils, on Trident using only a 5th of the intensity and energy of the Nova Petawatt laser. With clever target designs, like structured curved cone targets, we have also been able to achieve major ion energy gains, leading to the highest energy laser-accelerated proton beams in the world [3]. These new target designs promise to help usher in the next generation of particle sources realizing the potential of laser-accelerated beams.

  19. Single Molecule Experiments Challenge the Strict Wave-Particle Dualism of Light

    PubMed Central

    Greulich, Karl Otto

    2010-01-01

    Single molecule techniques improve our understanding of the photon and light. If the single photon double slit experiment is performed at the “single photon limit” of a multi-atom light source, faint light pulses with more than one photon hamper the interpretation. Single molecules, quantum dots or defect centres in crystals should be used as light source. “Single photon detectors” do not meet their promise—only “photon number resolving single photon detectors” do so. Particularly, the accumulation time argument, the only safe basis for the postulate of a strictly particle like photon, has so far not yet been verified. PMID:20162017

  20. Single molecule experiments challenge the strict wave-particle dualism of light.

    PubMed

    Greulich, Karl Otto

    2010-01-21

    Single molecule techniques improve our understanding of the photon and light. If the single photon double slit experiment is performed at the "single photon limit" of a multi-atom light source, faint light pulses with more than one photon hamper the interpretation. Single molecules, quantum dots or defect centres in crystals should be used as light source. "Single photon detectors" do not meet their promise-only "photon number resolving single photon detectors" do so. Particularly, the accumulation time argument, the only safe basis for the postulate of a strictly particle like photon, has so far not yet been verified.

  1. High-fidelity, broadband stimulated-Brillouin-scattering-based slow light using fast noise modulation.

    PubMed

    Zhu, Yunhui; Lee, Myungjun; Neifeld, Mark A; Gauthier, Daniel J

    2011-01-17

    We demonstrate a 5-GHz-broadband tunable slow-light device based on stimulated Brillouin scattering in a standard highly-nonlinear optical fiber pumped by a noise-current-modulated laser beam. The noisemodulation waveform uses an optimized pseudo-random distribution of the laser drive voltage to obtain an optimal flat-topped gain profile, which minimizes the pulse distortion and maximizes pulse delay for a given pump power. In comparison with a previous slow-modulation method, eye-diagram and signal-to-noise ratio (SNR) analysis show that this broadband slow-light technique significantly increases the fidelity of a delayed data sequence, while maintaining the delay performance. A fractional delay of 0.81 with a SNR of 5.2 is achieved at the pump power of 350 mW using a 2-km-long highly nonlinear fiber with the fast noise-modulation method, demonstrating a 50% increase in eye-opening and a 36% increase in SNR in the comparison.

  2. Regulatory light chain phosphorylation increases eccentric contraction-induced injury in skinned fast-twitch fibers.

    PubMed

    Childers, Martin K; McDonald, Kerry S

    2004-02-01

    During contraction, activation of Ca(2+)/calmodulin-dependent myosin light chain kinase (MLCK) results in phosphorylation of myosin's regulatory light chain (RLC), which potentiates force and increases speed of force development over a wide range of [Ca(2+)]. We tested the hypothesis that RLC phosphorylation by MLCK mediates the extent of eccentric contraction-induced injury as measured by force deficit in skinned fast-twitch skeletal muscle fibers. Results indicated that RLC phosphorylation in single skinned rat psoas fibers significantly increased Ca(2+) sensitivity of isometric force; isometric force from 50 +/- 16 to 59 +/- 18 kN/m(2) during maximal Ca(2+) activation; peak absolute power output from 38 +/- 15 to 48 +/- 14 nW during maximal Ca(2+) activation; and the magnitude of contraction-induced force deficit during maximal (pCa 4.5) activation from 26 +/- 9.8 to 35 +/- 9.6%. We conclude that RLC phosphorylation increases force deficits following eccentric contractions, perhaps by increasing the number of force-generating cross-bridges.

  3. Independent-particle models for light negative atomic ions

    NASA Technical Reports Server (NTRS)

    Ganas, P. S.; Talman, J. D.; Green, A. E. S.

    1980-01-01

    For the purposes of astrophysical, aeronomical, and laboratory application, a precise independent-particle model for electrons in negative atomic ions of the second and third period is discussed. The optimum-potential model (OPM) of Talman et al. (1979) is first used to generate numerical potentials for eight of these ions. Results for total energies and electron affinities are found to be very close to Hartree-Fock solutions. However, the OPM and HF electron affinities both depart significantly from experimental affinities. For this reason, two analytic potentials are developed whose inner energy levels are very close to the OPM and HF levels but whose last electron eigenvalues are adjusted precisely with the magnitudes of experimental affinities. These models are: (1) a four-parameter analytic characterization of the OPM potential and (2) a two-parameter potential model of the Green, Sellin, Zachor type. The system O(-) or e-O, which is important in upper atmospheric physics is examined in some detail.

  4. Light flash phenomena induced by HzE particles

    NASA Technical Reports Server (NTRS)

    Mcnulty, P. J.; Pease, V. P.

    1980-01-01

    Astronauts and Apollo and Skylab missions have reported observing a variety of visual phenomena when their eyes are closed and adapted to darkness. These phenomena have been collectively labelled as light flashes. Visual phenomena which are similar in appearance to those observed in space have been demonstrated at the number of accelerator facilities by expressing the eyes of human subjects to beams of various types of radiation. In some laboratory experiments Cerenkov radiation was found to be the basis for the flashes observed while in other experiments Cerenkov radiation could apparently be ruled out. Experiments that differentiate between Cerenkov radiation and other possible mechanisms for inducing visual phenomena was then compared. The phenomena obtained in the presence and absence of Cerenkov radiation were designed and conducted. A new mechanism proposed to explain the visual phenomena observed by Skylab astronauts as they passed through the South Atlantic Anomaly, namely nuclear interactions in and near the sensitive layer of the retina, is covered. Also some studies to search for similar transient effects of space radiation on sensors and microcomputer memories are described.

  5. Dual-wavelength light scattering for selective detection of volcanic ash particles

    NASA Astrophysics Data System (ADS)

    Jurányi, Z.; Burtscher, H.; Loepfe, M.; Nenkov, M.; Weingartner, E.

    2015-08-01

    A new method is presented in this paper which analyses the scattered light of individual aerosol particles simultaneously at two different wavelengths in order to retrieve information on the particle type. We show that dust-like particles, such as volcanic ash, can be unambiguously discriminated from water droplets on a single particle level. As a future application of this method, the detection of volcanic ash particles should be possible in a humid atmosphere in the presence of cloud droplets. We show an example, how the characteristic behaviour of pure water's refractive index can be used to separate water droplets and dust-like particles which are commonly found in the micrometer size-range in the ambient air. The low real part of the water's refractive index around 2700-2800 nm results in low scattered light intensities compared to e.g. the visible wavelength range and this feature can be used for the particle identification. The two-wavelength measurement setup was theoretically and experimentally tested and studied. Theoretical calculations were done using Mie theory. Comparing the ratio of the scattered light at the two wavelengths (R value) for water droplets and different dust types (basalt, andesite, African mineral dust, sand, volcanic ash, pumice) showed at least 9 times higher values (on average 70 times) for water droplets than for the dust types at any diameter within the particle size range of 2-20 μm. The envisaged measurement setup was built up into a laboratory prototype and was tested with different types of aerosols. We generated aerosols from the following powders simulating dust-like particles: cement dust, ISO 12103-1 A1 Ultrafine Test Dust and Ash from the 2012 eruption of the Etna volcano. Our measurements verified the theoretical considerations, the median experimental R value is 8-21 times higher for water than for the "dust" particles.

  6. Controlling dispersion forces between small particles with artificially created random light fields.

    PubMed

    Brügger, Georges; Froufe-Pérez, Luis S; Scheffold, Frank; José Sáenz, Juan

    2015-06-22

    Appropriate combinations of laser beams can be used to trap and manipulate small particles with optical tweezers as well as to induce significant optical binding forces between particles. These interaction forces are usually strongly anisotropic depending on the interference landscape of the external fields. This is in contrast with the familiar isotropic, translationally invariant, van der Waals and, in general, Casimir-Lifshitz interactions between neutral bodies arising from random electromagnetic waves generated by equilibrium quantum and thermal fluctuations. Here we show, both theoretically and experimentally, that dispersion forces between small colloidal particles can also be induced and controlled using artificially created fluctuating light fields. Using optical tweezers as a gauge, we present experimental evidence for the predicted isotropic attractive interactions between dielectric microspheres induced by laser-generated, random light fields. These light-induced interactions open a path towards the control of translationally invariant interactions with tuneable strength and range in colloidal systems.

  7. Controlling dispersion forces between small particles with artificially created random light fields

    PubMed Central

    Brügger, Georges; Froufe-Pérez, Luis S.; Scheffold, Frank; José Sáenz, Juan

    2015-01-01

    Appropriate combinations of laser beams can be used to trap and manipulate small particles with optical tweezers as well as to induce significant optical binding forces between particles. These interaction forces are usually strongly anisotropic depending on the interference landscape of the external fields. This is in contrast with the familiar isotropic, translationally invariant, van der Waals and, in general, Casimir–Lifshitz interactions between neutral bodies arising from random electromagnetic waves generated by equilibrium quantum and thermal fluctuations. Here we show, both theoretically and experimentally, that dispersion forces between small colloidal particles can also be induced and controlled using artificially created fluctuating light fields. Using optical tweezers as a gauge, we present experimental evidence for the predicted isotropic attractive interactions between dielectric microspheres induced by laser-generated, random light fields. These light-induced interactions open a path towards the control of translationally invariant interactions with tuneable strength and range in colloidal systems. PMID:26096622

  8. Light charged particles emitted in fission reactions induced by protons on 208Pb

    NASA Astrophysics Data System (ADS)

    Rodríguez-Sánchez, J. L.; Benlliure, J.; Paradela, C.; Ayyad, Y.; Casarejos, E.; Alvarez-Pol, H.; Audouin, L.; Bélier, G.; Boutoux, G.; Chatillon, A.; Cortina-Gil, D.; Gorbinet, T.; Heinz, A.; Kelić-Heil, A.; Laurent, B.; Martin, J.-F.; Pellereau, E.; Pietras, B.; Ramos, D.; Rodríguez-Tajes, C.; Rossi, D. M.; Simon, H.; Taïeb, J.; Vargas, J.; Voss, B.

    2016-09-01

    Light charged particles emitted in proton-induced fission reactions on 208Pb have been measured at different kinetic energies: 370 A ,500 A , and 650 A MeV. The experiment was performed by the SOFIA Collaboration at the GSI facilities in Darmstadt (Germany). The inverse kinematics technique was combined with a setup especially designed to measure light charged particles in coincidence with fission fragments. This measurement allowed us, for the first time, to obtain correlations between the light charged particles emitted during the fission process and the charge distributions of the fission fragments. These correlations were compared with different model calculations to assess the ground-to-saddle dynamics. The results confirm that transient and dissipative effects are required for an accurate description of the fission observables.

  9. Amplified light scattering and emission of silver and silver core-silica shell particles.

    PubMed

    Siiman, Olavi; Jitianu, Andrei; Bele, Marjan; Grom, Patricia; Matijević, Egon

    2007-05-01

    Side versus forward light scattergrams, and fluorescence (488 nm excitation) intensity versus particle count histograms were gathered for bare, R6G-coated, and silica-R6G-coated silver particles of 150-200 nm diameter, one-by-one by flow cytometry. Fluorescence emission intensity of the composite particles monotonically increased and then reached a plateau with greater R6G concentrations, as measured by flow cytometry. Fluorescence amplification factors of up to 3.5x10(3) were estimated by reference to measurements on core-shell particles with silica instead of silver cores. Huge surface enhanced Raman scattering (SERS) intensities, at least 10(14)-fold greater than normal Raman scattering intensities, were observed with 633 nm excitation for molecules such as rhodamine 6G (R6G) on the same single particles of silver. Although routine transmission (TEM) and scanning (SEM) electron microscopies showed gross structures of the bare and coated particles, high-resolution field emission scanning electron microscopy (FE-SEM), revealed Brownian roughness describing quantum size and larger structures on the surface of primary colloidal silver particles. These silver particles were further characterized by extinction spectra and zeta potentials. Structural and light scattering observations that are reported herein were used to tentatively propose a new hierarchical model for the mechanism of SERS.

  10. Static light scattering by aqueous solutions of rodlike fd-virus particles

    NASA Astrophysics Data System (ADS)

    Hagenbüchle, M.; Weyerich, B.; Deggelmann, M.; Graf, C.; Krause, R.; Maier, E. E.; Schulz, S. F.; Klein, R.; Weber, R.

    1990-11-01

    Static light scattering measurements are reported on aqueous solutions of rodlike fd-virus (length L = 880 nm, molecular weight 16.4 × 10 6 g/mol) below and above the overlap concentration c∗ = 1 particle/length 3. In solutions of very low ionic strength a liquidlike structure with a significant first intensity maximum of the elastically scattered light is observed due to the electrostatic interaction of the charged rods. The scattering vector of the first static structure factor maximum scales with concentration as c1/3 below c∗ and as c1/2 above. In comparison to results of spherical particle solutions the influence of particle anisotropy is evaluated. It is claimed that the c1/2-dependence is a general feature of solutions of rodlike particles above c∗. The experimental results in the crossover region around c∗ are confirmed by Monte Carlo simulations, based on a model potential describing a screened Coulomb interaction between rods.

  11. Accurate optical simulation of nano-particle based internal scattering layers for light outcoupling from organic light emitting diodes

    NASA Astrophysics Data System (ADS)

    Egel, Amos; Gomard, Guillaume; Kettlitz, Siegfried W.; Lemmer, Uli

    2017-02-01

    We present a numerical strategy for the accurate simulation of light extraction from organic light emitting diodes (OLEDs) comprising an internal nano-particle based scattering layer. On the one hand, the light emission and propagation through the OLED thin film system (including the scattering layer) is treated by means of rigorous wave optics calculations using the T-matrix formalism. On the other hand, the propagation through the substrate is modeled in a ray optics approach. The results from the wave optics calculations enter in terms of the initial substrate radiation pattern and the bidirectional reflectivity distribution of the OLED stack with scattering layer. In order to correct for the truncation error due to a finite number of particles in the simulations, we extrapolate the results to infinitely extended scattering layers. As an application example, we estimate the optimal particle filling fraction for an internal scattering layer in a realistic OLED geometry. The presented treatment is designed to emerge from electromagnetic theory with as few additional assumptions as possible. It could thus serve as a baseline to validate faster but approximate simulation approaches.

  12. Fast single-image dehazing method for visible-light systems

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Guo, Bao Long; Li, Da Jian; Jia, Wei

    2013-09-01

    Optical imaging systems are often degraded by scattering due to atmospheric particles such as haze, fog, and mist. According to the physical model of atmospheric scattering, two major factors that affect the effect of fog removal are discussed. By using joint probability density definition and the proposed joint mean shift filtering algorithm, discontinuity preserving smoothing and image segmentation are addressed in the sequel to refine the atmospheric veil and estimate the atmospheric light, which overcomes the inherent limitations of the state-of-the-art methods. Simulation results on a variety of outdoor foggy images demonstrate that the proposed method achieves short computation time and good restoration for visibility and color fidelity. An embedded vision enhanced system based on a DSP is designed and runs the proposed algorithm at 15 fps for a color frame of 720×576 pixels.

  13. Asymmetric transport of light in linearly arrayed metallic nano-particles

    NASA Astrophysics Data System (ADS)

    Horchani, R.

    2016-02-01

    A strong asymmetric light transport in a linear chain of spherical and equidistantly spaced silver metal nano-particles (MNPs) located near a substrate is reported. The contrast ratio of the proposed structure is above 0.95. We have studied the propagation of light in the array with respect to the metal and the size of the last nano-particle of the chain and the nature of the substrate. It is shown also that the presence of a copper or gold substrate enhance the guiding properties of the array. This structure opens the possibility to design various optical devices such as broadband antennae and optical diodes.

  14. Asymmetric transport of light in linearly arrayed metallic nano-particles

    NASA Astrophysics Data System (ADS)

    Aroua, W.; Horchani, R.; AbdelMalek, F.; Haxha, S.; Kamli, Ali A.

    2016-09-01

    A strong asymmetric light transport in a linear chain of spherical and equidistantly spaced silver metal nano-particles (MNPs) located near a substrate is reported. The contrast ratio of the proposed structure is above 0.95. We have studied the propagation of light in the array with respect to the metal and the size of the last nano-particle of the chain and the nature of the substrate. It is shown also that the presence of a copper or gold substrate enhance the guiding properties of the array. This structure opens the possibility to design various optical devices such as broadband antennae and optical diodes.

  15. New scheme of the Discrete Sources Method for light scattering analysis of a particle breaking interface

    NASA Astrophysics Data System (ADS)

    Eremin, Yuri; Wriedt, Thomas

    2014-12-01

    The Discrete Sources Method (DSM) has been modified to analyze polarized light scattering by an axial symmetric penetrable nanoparticle partially embedded into a substrate. The new numerical scheme of the DSM enables to consider scattering from such substrate defects as flat particles, mounds, pits and voids. A detailed description of the numerical scheme is provided. The developed computer model has been employed to investigate scattering from a shallow particle and pit. Simulation results corresponding to the Differential Scattering Cross-Section and the integral response for P/S polarized light are presented.

  16. Light scattering by irregular particles much larger than the wavelength with wavelength-scale surface roughness.

    PubMed

    Grynko, Yevgen; Shkuratov, Yuriy; Förstner, Jens

    2016-08-01

    We simulate light scattering by random irregular particles that have dimensions much larger than the wavelength of incident light at the size parameter of X=200 using the discontinuous Galerkin time domain method. A comparison of the DGTD solution for smoothly faceted particles with that obtained with a geometric optics model shows good agreement for the scattering angle curves of intensity and polarization. If a wavelength-scale surface roughness is introduced, diffuse scattering at rough interface results in smooth and featureless curves for all scattering matrix elements which is consistent with the laboratory measurements of real samples.

  17. Light concentration in the near-field of dielectric spheroidal particles with mesoscopic sizes.

    PubMed

    Mendes, Manuel J; Tobías, Ignacio; Martí, Antonio; Luque, Antonio

    2011-08-15

    This paper presents a numerical study of the light focusing properties of dielectric spheroids with sizes comparable to the illuminating wavelength. An analytical separation-of-variables method is used to determine the electric field distribution inside and in the near-field outside the particles. An optimization algorithm was implemented in the method to determine the particles' physical parameters that maximize the forward scattered light in the near-field region. It is found that such scatterers can exhibit pronounced electric intensity enhancement (above 100 times the incident intensity) in their close vicinity, or along wide focal regions extending to 10 times the wavelength. The results reveal the potential of wavelength-sized spheroids to manipulate light beyond the limitations of macroscopic geometrical optics. This can be of interest for several applications, such as light management in photovoltaics.

  18. A Description of the Full Particle Orbit Following SPIRAL Code for Simulating Fast-ion Experiments in Tokamaks

    SciTech Connect

    Kramer, G.J.; Budny, R.V.; Bortolon, A.; Fredrickson, E.D.; Fu, G.Y.; Heidbrink, W.W.; Nazikian, R.; Valeo, E.; Van Zeeland, M.A.

    2012-07-27

    The numerical methods used in the full particle-orbit following SPIRAL code are described and a number of physics studies performed with the code are presented to illustrate its capabilities. The SPIRAL code is a test-particle code and is a powerful numerical tool to interpret and plan fast-ion experiments in Tokamaks. Gyro-orbit effects are important for fast ions in low-field machines such as NSTX and to a lesser extent in DIII-D. A number of physics studies are interlaced between the description of the code to illustrate its capabilities. Results on heat loads generated by a localized error-field on the DIII-D wall are compared to measurements. The enhanced Triton losses caused by the same localized error-field are calculated and compared to measured neutron signals. MHD activity such as tearing modes and Toroidicity-induced Alfven Eigenmodes (TAEs) have a profound effect on the fast-ion content of Tokamak plasmas and SPIRAL can calculate the effects of MHD activity on the confined and lost fast-ion population as illustrated for a burst of TAE activity in NSTX. The interaction between Ion Cyclotron Range of Frequency (ICRF) heating and fast ions depends solely on the gyro-motion of the fast ions and is captured exactly in the SPIRAL code. A calculation of ICRF absorption on beam ions in ITER is presented. The effects of high harmonic fast wave heating on the beam-ion slowing-down distribution in NSTX is also studied.

  19. Advanced Fuel Cycle Economic Analysis of Symbiotic Light-Water Reactor and Fast Burner Reactor Systems

    SciTech Connect

    D. E. Shropshire

    2009-01-01

    The Advanced Fuel Cycle Economic Analysis of Symbiotic Light-Water Reactor and Fast Burner Reactor Systems, prepared to support the U.S. Advanced Fuel Cycle Initiative (AFCI) systems analysis, provides a technology-oriented baseline system cost comparison between the open fuel cycle and closed fuel cycle systems. The intent is to understand their overall cost trends, cost sensitivities, and trade-offs. This analysis also improves the AFCI Program’s understanding of the cost drivers that will determine nuclear power’s cost competitiveness vis-a-vis other baseload generation systems. The common reactor-related costs consist of capital, operating, and decontamination and decommissioning costs. Fuel cycle costs include front-end (pre-irradiation) and back-end (post-iradiation) costs, as well as costs specifically associated with fuel recycling. This analysis reveals that there are large cost uncertainties associated with all the fuel cycle strategies, and that overall systems (reactor plus fuel cycle) using a closed fuel cycle are about 10% more expensive in terms of electricity generation cost than open cycle systems. The study concludes that further U.S. and joint international-based design studies are needed to reduce the cost uncertainties with respect to fast reactor, fuel separation and fabrication, and waste disposition. The results of this work can help provide insight to the cost-related factors and conditions needed to keep nuclear energy (including closed fuel cycles) economically competitive in the U.S. and worldwide. These results may be updated over time based on new cost information, revised assumptions, and feedback received from additional reviews.

  20. On the errors in measuring the particle density by the light absorption method

    SciTech Connect

    Ochkin, V. N.

    2015-04-15

    The accuracy of absorption measurements of the density of particles in a given quantum state as a function of the light absorption coefficient is analyzed. Errors caused by the finite accuracy in measuring the intensity of the light passing through a medium in the presence of different types of noise in the recorded signal are considered. Optimal values of the absorption coefficient and the factors capable of multiplying errors when deviating from these values are determined.

  1. Evaluation of Additives to Eliminate Free Water from Aviation Fuel Light Obscuration Particle Counts

    DTIC Science & Technology

    2015-11-01

    5000 DISTRIBUTION A. Approved for public release: distribution unlimited. Evaluation of Additives to Eliminate Free Water from Aviation Fuel Light...April 2015 4. TITLE AND SUBTITLE Evaluation of Additives to Eliminate Free Water from Aviation Fuel Light Obscuration Particle Counts 5a. CONTRACT...13. SUPPLEMENTARY NOTES 14. ABSTRACT This technical report details the evaluation fuel additives used to eliminate the effects of free water

  2. 3D real-time visualization of blood flow in cerebral aneurysms by light field particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Carlsohn, Matthias F.; Kemmling, André; Petersen, Arne; Wietzke, Lennart

    2016-04-01

    Cerebral aneurysms require endovascular treatment to eliminate potentially lethal hemorrhagic rupture by hemostasis of blood flow within the aneurysm. Devices (e.g. coils and flow diverters) promote homeostasis, however, measurement of blood flow within an aneurysm or cerebral vessel before and after device placement on a microscopic level has not been possible so far. This would allow better individualized treatment planning and improve manufacture design of devices. For experimental analysis, direct measurement of real-time microscopic cerebrovascular flow in micro-structures may be an alternative to computed flow simulations. An application of microscopic aneurysm flow measurement on a regular basis to empirically assess a high number of different anatomic shapes and the corresponding effect of different devices would require a fast and reliable method at low cost with high throughout assessment. Transparent three dimensional 3D models of brain vessels and aneurysms may be used for microscopic flow measurements by particle image velocimetry (PIV), however, up to now the size of structures has set the limits for conventional 3D-imaging camera set-ups. On line flow assessment requires additional computational power to cope with the processing large amounts of data generated by sequences of multi-view stereo images, e.g. generated by a light field camera capturing the 3D information by plenoptic imaging of complex flow processes. Recently, a fast and low cost workflow for producing patient specific three dimensional models of cerebral arteries has been established by stereo-lithographic (SLA) 3D printing. These 3D arterial models are transparent an exhibit a replication precision within a submillimeter range required for accurate flow measurements under physiological conditions. We therefore test the feasibility of microscopic flow measurements by PIV analysis using a plenoptic camera system capturing light field image sequences. Averaging across a sequence of

  3. Angle-Resolved Second-Harmonic Light Scattering from Colloidal Particles

    SciTech Connect

    Yang, N.; Angerer, W. E.; Yodh, A. G.

    2001-09-03

    We report angle-resolved second-harmonic generation (SHG) measurements from suspensions of centrosymmetric micron-size polystyrene spheres with surface-adsorbed dye (malachite green). The second-harmonic scattering profiles differ qualitatively from linear light scattering profiles of the same particles. We investigated these radiation patterns using several polarization configurations and particle diameters. We introduce a simple Rayleigh-Gans-Debye model to account for the SHG scattering anisotropy. The model compares favorably with our experimental data. Our measurements suggest scattering anisotropy may be used to isolate particle nonlinear optics from other bulk nonlinear optical effects in suspension.

  4. Data report of hypervelocity micro-particle impact light flash data and MOS impact detector output

    NASA Astrophysics Data System (ADS)

    Serna, Patrick J.

    1995-06-01

    A series of hypervelocity impact tests were conducted at the Max-Plank Institut fur Kernphysik, Heidelberg, Germany using the Institut's 2 MV Van De Graaff micro-particle accelerator. The purpose of this experimental effort was to collect impact flash data resulting from hypervelocity impact events. The results of these test experiments are to be correlated with actual waveforms obtained from on-orbit systems. Furthermore, these experimental results will supplement ongoing theoretical predictions being conducted within the Phillips Laboratory by the Space Kinetic Impact/Debris Branch (pLJWSCD). This report only describes the instrumentation configuration and presents data collected from light flash measurements and a MOS micro-particle impact detector. An analysis of the acquired light flash data is contained in a separate report authored by Allahdadi, Medina, Serna, and Long. Iron particles in the mass range of 1 x 10(exp -15) to 8 x 10(exp -18) kg were accelerated to velocities between 7 and 38 km/sec. Three targets were used for these impact test: spacecraft optical lens, spacecraft optical sunshade, and MOS spacecraft micro-particle impact detector. The hypervelocity particle impacted the lens and micro-particle impact detector targets normal to the target surface. The sunshade was impacted at a 25 degree angle measured from the particle direction of flight.

  5. Fresnel reflectance in refractive index estimation of light scattering solid particles in immersion liquid

    NASA Astrophysics Data System (ADS)

    Räty, J.; Niskanen, I.; Peiponen, K.-E.

    2010-06-01

    The refractive index of homogenous particle population can be determined by the so-called immersion liquid method. The idea is to find a known liquid whose refractive index matches the index of the particles. We report on a method that simultaneously obtains the refractive index of particles and that of the immersion liquid. It is based on a system using internal light reflection and Fresnel's theory. The method includes a series of straightforward reflection measurements and a fitting procedure. The validity of the method was tested with CaF2 particles. The method has applications within scientific studies of microparticles and nanoparticles or micro-organism in suspensions. It can be also be utilized in industry for the detection of the refractive index of products involving particles for the purpose of improvement of product quality.

  6. Significant role of deformation in probing postsaddle nuclear dissipation with light particle emission

    SciTech Connect

    Ye, W.

    2010-05-15

    Using a one-dimensional Langevin model, we study the effects of deformation on the multiplicities of postsaddle neutrons, protons, alpha particles, and giant dipole resonance (GDR) gamma rays of a heavy fissioning system {sup 240}Cf as probes of postsaddle nuclear dissipation (beta). It is shown that postsaddle dissipation effects on these light particles have a significant deformation dependence. Furthermore, we find that the role of deformation depends on the type of the particle. It reduces the sensitive influence of beta on protons, alpha particles, and GDR gamma rays substantially, whereas it enhances the sensitivity of neutrons to beta. The results suggest that to accurately extract the postsaddle friction strength by comparing measured prescission particle multiplicities of heavy nuclei with calculations based on statistical models or stochastic equations like Langevin equations, it is important to take into account the deformation effects. The influence of model dimensionality is discussed.

  7. Monte Carlo simulation of light scattering from size distributed homogenous and coated spherical particles

    NASA Astrophysics Data System (ADS)

    Gogoi, Ankur

    Light scattering is a subject of intensive research at the present time in diverse fields of research namely, physics, astronomy, meteorology, biology, nanotechnology, etc. Observation and theoretical calculation of the absorption and scattering properties of particles, whose size ranges from micrometer to nanometer, are not only essential to deduce their physical properties but also capable of giving useful information for better understanding of radiation transfer through a medium containing such scatterer. In addition to such experimental and theoretical studies on light scattering by particulate matter several other groups have been extensively using Monte Carlo (MC) method to simulate light (photon) propagation in scattering media. Importantly such methods of simulating light scattering properties of artificial particles are proving to be a very useful tool in verifying the experimental observations with real samples as well as providing new clues to improve the accuracy of the existing theoretical models. In this contribution we report a MC method developed by implementing Mie theory to simulate the light scattering pattern from size distributed homogenous and coated spherical particles in single scattering regime. The computer program was written in ANSI C-language. The accuracy, efficiency and reliability of the MC method were validated by comparing the results generated by using the MC method with other benchmark theoretical results and experimental results with standard samples. Notably the MC method reported here is found to be stable even for very large spherical particles (size parameters > 1000) with large values of real (= 10) and imaginary part (= 10) of the refractive index. The promising field of application of the reported MC method will be in simulating the light (or electromagnetic) scattering properties of different types of planetary and interplanetary dust particles.

  8. Effects of porous films on the light reflectivity of pigmentary titanium dioxide particles

    NASA Astrophysics Data System (ADS)

    Liang, Yong; Qiao, Bing; Wang, Tig-Jie; Gao, Han; Yu, Keyi

    2016-11-01

    The light reflectivity of the film-coated titanium dioxide particles (TiO2) as a function of the film refractive index was derived and calculated using a plane film model. For the refractive index in the range of 1.00-2.15, the lower the film refractive index is, the higher is the light reflectivity of the film. It is inferred that the lower apparent refractive index of the porous film resulted in the higher reflectivity of light, i.e., the higher hiding power of the titanium dioxide particles. A dense film coating on TiO2 particles with different types of oxides, i.e., SiO2, Al2O3, MgO, ZnO, ZrO2, TiO2, corresponding to different refractive indices of the film from 1.46 to 2.50, was achieved, and the effects of refractive index on the hiding power from the model prediction were confirmed. Porous film coating of TiO2 particles was achieved by adding the organic template agent triethanolamine (TEA). The hiding power of the coated TiO2 particles was increased from 88.3 to 90.8 by adding the TEA template to the film coating (5-20 wt%). In other words, the amount of titanium dioxide needed was reduced by approximately 10% without a change in the hiding power. It is concluded that the film structure coated on TiO2 particle surface affects the light reflectivity significantly, namely, the porous film exhibits excellent performance for pigmentary titanium dioxide particles with high hiding power.

  9. Manipulation of Micro Scale Particles in Optical Traps Using Programmable Spatial Light Modulation

    NASA Technical Reports Server (NTRS)

    Seibel, Robin E.; Decker, Arthur J. (Technical Monitor)

    2003-01-01

    1064 nm light, from an Nd:YAG laser, was polarized and incident upon a programmable parallel aligned liquid crystal spatial light modulator (PAL-SLM), where it was phase modulated according to the program controlling the PAL-SLM. Light reflected from the PAL-SLM was injected into a microscope and focused. At the focus, multiple optical traps were formed in which 9.975 m spheres were captured. The traps and the spheres were moved by changing the program of the PAL-SLM. The motion of ordered groups of micro particles was clearly demonstrated.

  10. Design of a fast electron beam scanning system for compact synchrotron light sources

    NASA Astrophysics Data System (ADS)

    Moser, H. O.; Lehr, H.

    1989-07-01

    The design of an electron beam scanning system for compact storage ring synchrotron light sources is described. The main features are a scan frequency of 100 Hz and an angular amplitude of ±5 mrad. Different configurations of scan dipoles permit confining the scan to one cell using four dipoles or to repeat the scan periodically along the whole circumference by means of two scan dipoles per cell. Combinations of these basic configurations are possible. The location of the nodes of the pivoting electron beam can be optimized with respect to the maximum scan angle by slightly unbalancing the field strength in different scan dipoles. The scan dipoles are H-shaped magnets made from laminated iron. Their gap width is 68 mm. They are powered by fast transistor-bridge supplies which are controlled by freely programmable function generators capable of realizing a triangular current waveform with a deviation of less than 0.1% except for a 1% neighborhood of the apex. Estimates of the influence of the scanning on both quantum and Coulomb lifetime indicate acceptable lifetime reductions provided the minimum distance between distorted closed orbit and aperture exceeds about six standard deviations of the spatial electron distribution.

  11. Fast separation of triterpenoids by supercritical fluid chromatography/evaporative light scattering detector.

    PubMed

    Lesellier, E; Destandau, E; Grigoras, C; Fougère, L; Elfakir, C

    2012-12-14

    The screening of plant material, the chemical composition, the abundance and the biological activity of triterpenoids are of a major economical importance. The classical analytical methods, such as TLC, GC, and HPLC are either little resolutive, or require derivatization steps, or fail in sensitivity. The supercritical fluid chromatography/evaporative light scattering detector (SFC/ELSD) coupling provides high resolution, fast analysis and higher responses for the analysis of triterpenoids. After the initial screening of seven stationary phases to select the well suited one, analytical conditions (modifier percentage, from 10 to 3%; backpressure (from 12 to 18 MPa) and temperature (from 15 to 25 °C) were studied to improve the separation, and ELSD detection of a standard mixture composed of 8 triterpenoids (oleanolic acid, erythrodiol, β-amyrin, ursolic acid, uvaol, betulinic acid, betulin, lupeol). Applied to apple pomace extracts, this method allows the separation of about 15 triterpenoid compounds, in less than 20 min, with isocratic conditions. Moreover, the ELSD response is dramatically higher than the one provided by UV detection, and avoids derivatization steps. An attempt to identify some compounds was done by collecting chromatographic peaks and further analyzing them with mass spectrometry. Complete identification or molecular formula could be proposed for 11 compounds. However, due to the presence of position and orientation isomers the absolute identification remains difficult, despite some retention rules deduced from the standard analysis.

  12. Irregular spin angular momentum transfer from light to small birefringent particles

    SciTech Connect

    Rothmayer, M.; Tierney, D.; Schmitzer, H.; Frins, E.; Dultz, W.

    2009-10-15

    The transfer of spin angular momentum from photons to small particles is a key experiment of quantum physics. The particles rotate clockwise or counterclockwise depending on the polarization of the light beam which holds them in an optical trap. We show that even perfectly disk shaped particles will in general not rotate with a constant angular speed. The particles will periodically accelerate and decelerate their rotational motion due to a varying spin angular momentum transfer from the light. Using the Poincare sphere we derive the equation of motion of a birefringent plate and verify the results by measuring the time dependent rotation of small crystals of Hg(I) iodide and 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) in the trap of polarized optical tweezers. For small ellipticities of the polarized light in the tweezers the plate stops in a fixed orientation relative to the axes of the light ellipse. We discuss the origin of this halt and propose an application of small birefringent plates as self-adjusting optical retarders in micro-optics.

  13. Adaptive Fraunhofer diffraction particle sizing instrument using a spatial light modulator.

    PubMed

    Hirleman, E D; Dellenback, P A

    1989-11-15

    Integration of a magnetooptic spatial light modulator into a Fraunhofer diffraction particle sizing instrument is proposed and demonstrated theoretically and experimentally. The concept gives the instrument the ability to reconfigure a detector array on-line and thereby adapt to the measurement context.

  14. Light Scattering by Gaussian Particles: A Solution with Finite-Difference Time Domain Technique

    NASA Technical Reports Server (NTRS)

    Sun, W.; Nousiainen, T.; Fu, Q.; Loeb, N. G.; Videen, G.; Muinonen, K.

    2003-01-01

    The understanding of single-scattering properties of complex ice crystals has significance in atmospheric radiative transfer and remote-sensing applications. In this work, light scattering by irregularly shaped Gaussian ice crystals is studied with the finite-difference time-domain (FDTD) technique. For given sample particle shapes and size parameters in the resonance region, the scattering phase matrices and asymmetry factors are calculated. It is found that the deformation of the particle surface can significantly smooth the scattering phase functions and slightly reduce the asymmetry factors. The polarization properties of irregular ice crystals are also significantly different from those of spherical cloud particles. These FDTD results could provide a reference for approximate light-scattering models developed for irregular particle shapes and can have potential applications in developing a much simpler practical light scattering model for ice clouds angular-distribution models and for remote sensing of ice clouds and aerosols using polarized light. (copyright) 2003 Elsevier Science Ltd. All rights reserved.

  15. Depolarized light scattering from prolate anisotropic particles: The influence of the particle shape on the field autocorrelation function.

    PubMed

    Passow, Christopher; ten Hagen, Borge; Löwen, Hartmut; Wagner, Joachim

    2015-07-28

    We provide a theoretical analysis for the intermediate scattering function typically measured in depolarized dynamic light scattering experiments. We calculate the field autocorrelation function g1(VH)(Q,t) in dependence on the wave vector Q and the time t explicitly in a vertical-horizontal scattering geometry for differently shaped solids of revolution. The shape of prolate cylinders, spherocylinders, spindles, and double cones with variable aspect ratio is expanded in rotational invariants flm(r). By Fourier transform of these expansion coefficients, a formal multipole expansion of the scattering function is obtained, which is used to calculate the weighting coefficients appearing in the depolarized scattering function. In addition to translational and rotational diffusion, especially the translational-rotational coupling of shape-anisotropic objects is considered. From the short-time behavior of the intermediate scattering function, the first cumulants Γ(Q) are calculated. In a depolarized scattering experiment, they deviate from the simple proportionality to Q(2). The coefficients flm(Q) strongly depend on the geometry and aspect ratio of the particles. The time dependence, in addition, is governed by the translational and rotational diffusion tensors, which are calculated by means of bead models for differently shaped particles in dependence on their aspect ratio. Therefore, our analysis shows how details of the particle shape--beyond their aspect ratio--can be determined by a precise scattering experiment. This is of high relevance in understanding smart materials which involve suspensions of anisotropic colloidal particles.

  16. Light-scattering study of the effect of salt and polyelectrolyte on magnetic latex particles

    SciTech Connect

    Sohn, D.; Russo, P.S.

    1993-12-31

    Dynamic and static light scattering methods have been used to study the interaction between magnetic latex and polyelectrolytes (polystyrene sulfonate sodium salt, NaPSS) in solution. The light scattering signal from magnetic latex particles was far stronger than that of the polyelectrolyte, especially during depolarized measurements where the polyelectrolyte was essentially invisible. Rotational and translational diffusion of the magnetic latex is investigated as a function of the NaPSS concentration and added salt (NaCl). The diffusion coefficient of magnetic latex decreases abruptly with increasing salt concentration when NaPSS is absent, but it recovers upon addition of NaPSS to the system. Static light scattering results also give evidence of particle aggregation at high salt.

  17. The Classical Theory of Light Colors: a Paradigm for Description of Particle Interactions

    NASA Astrophysics Data System (ADS)

    Mazilu, Nicolae; Agop, Maricel; Gatu, Irina; Iacob, Dan Dezideriu; Butuc, Irina; Ghizdovat, Vlad

    2016-06-01

    The color is an interaction property: of the interaction of light with matter. Classically speaking it is therefore akin to the forces. But while forces engendered the mechanical view of the world, the colors generated the optical view. One of the modern concepts of interaction between the fundamental particles of matter - the quantum chromodynamics - aims to fill the gap between mechanics and optics, in a specific description of strong interactions. We show here that this modern description of the particle interactions has ties with both the classical and quantum theories of light, regardless of the connection between forces and colors. In a word, the light is a universal model in the description of matter. The description involves classical Yang-Mills fields related to color.

  18. Measurements of light-absorbing particles on the glaciers in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Schmitt, C. G.; All, J. D.; Schwarz, J. P.; Arnott, W. P.; Cole, R. J.; Lapham, E.; Celestian, A.

    2015-02-01

    Glaciers in the tropical Andes have been rapidly losing mass since the 1970s. In addition to the documented increase in temperature, increases in light-absorbing particles deposited on glaciers could be contributing to the observed glacier loss. Here we report on measurements of light-absorbing particles sampled from glaciers during three surveys in the Cordillera Blanca Mountains in Peru. During three research expeditions in the dry seasons (May-August) of 2011, 2012 and 2013, 240 snow samples were collected from 15 mountain peaks over altitudes ranging from 4800 to nearly 6800 m. Several mountains were sampled each of the 3 years and some mountains were sampled multiple times during the same year. Collected snow samples were melted and filtered in the field then later analyzed using the Light Absorption Heating Method (LAHM), a new technique that measures the ability of particles on filters to absorb visible light. LAHM results have been calibrated using filters with known amounts of fullerene soot, a common industrial surrogate for black carbon (BC). As sample filters often contain dust in addition to BC, results are presented in terms of effective black carbon (eBC). During the 2013 survey, snow samples were collected and kept frozen for analysis with a Single Particle Soot Photometer (SP2). Calculated eBC mass from the LAHM analysis and the SP2 refractory black carbon (rBC) results were well correlated (r2 = 0.92). These results indicate that a substantial portion of the light-absorbing particles in the more polluted regions were likely BC. The 3 years of data show that glaciers in the Cordillera Blanca Mountains close to human population centers have substantially higher levels of eBC (as high as 70 ng g-1) than remote glaciers (as low as 2.0 ng g-1 eBC), indicating that population centers can influence local glaciers by sourcing BC.

  19. Effects of fast halogen and plasma arc curing lights on the surface hardness of orthodontic adhesives for lingual retainers.

    PubMed

    Uşümez, Serdar; Büyükyilmaz, Tamer; Karaman, Ali Ihya

    2003-06-01

    The aims of this study were to (1) identify the optimum cure times of 2 different lingual retainer adhesives with a conventional halogen, a fast halogen, and a plasma arc light by measuring Vickers surface hardness, and (2) determine whether different lights produce similar surface hardness values for the same adhesive resin material. The investigated plasma arc curing unit was the PowerPac (American Dental Technologies, Corpus Christi, Tex), and the fast halogen unit was the Optilux 501 (Kerr, Orange, Calif). A conventional curing unit, the Ortholux XT (3M Dental Products, St. Paul, Minn) was used as the control. Two orthodontic lingual retainer adhesives were used: Transbond Lingual Retainer (3M Unitek, Monrovia, Calif) and Light Cure Retainer (Reliance Orthodontic Products, Itasca, Ill). Concise (3M Dental Products) and diluted Concise were used as controls. Transbond Lingual Retainer was polymerized by the PowerPac light in 6 seconds, by the Optilux in 10 seconds, and by the conventional halogen light in 20 seconds. The minimum curing times for Light Cure Retainer adhesive were 15 seconds for PowerPac, 10 seconds for Optilux, and 40 seconds for conventional halogen. Surface hardness values for each resin did not differ significantly with different curing units. However, different adhesives demonstrated significantly different surface hardness values. Final Vickers surface hardness values (averaged across curing units) of Transbond Lingual Retainer, Concise, diluted Concise, and Light Cure Retainer were 62.8, 52.4, 46.0, and 40.4, respectively. Plasma arc or fast halogen units polymerize resin composite adhesive in much shorter times than do conventional curing units, without a significant loss in surface hardness. Therefore, these units are suggested for clinical use to save chairside time.

  20. Dynamic light scattering: A fast and reliable method to analyze bacterial growth during the lag phase.

    PubMed

    Vargas, Susana; Millán-Chiu, Blanca E; Arvizu-Medrano, Sofía M; Loske, Achim M; Rodríguez, Rogelio

    2017-04-09

    A comparison between plate counting (PC) and dynamic light scattering (DLS) is reported. PC is the standard technique to determine bacterial population as a function of time; however, this method has drawbacks, such as the cumbersome preparation and handling of samples, as well as the long time required to obtain results. Alternative methods based on optical density are faster, but do not distinguish viable from non-viable cells. These inconveniences are overcome by using DLS. Two different bacteria strains were considered: Escherichia coli and Staphylococcus aureus. DLS was performed at two different illuminating conditions: continuous and intermittent. By the increment of particle size as a function of time, it was possible to observe cell division and the formation of aggregates containing very few bacteria. The scattered intensity profiles showed the lag phase and the transition to the exponential phase of growth, providing a quantity proportional to viable bacteria concentration. The results revealed a clear and linear correlation in both lag and exponential phase, between the Log10(colony-forming units/mL) from PC and the Log10 of the scattered intensity Is from DLS. These correlations provide a good support to use DLS as an alternative technique to determine bacterial population.

  1. Contribution of fine particle sulfates to light scattering in St. Louis summer aerosol

    SciTech Connect

    Vossler, T.L.; Macias, E.S.

    1986-12-01

    The contribution of fine particle (NH/sub 4/)/sub 2/SO/sub 4/ to total light scattering was calculated from measured sulfur size distributions and estimates of water that might be associated with this deliquescent species. The most common type of sulfur size distribution observed had a major sulfur mass peak between 0.5 and 1.0 ..mu..m in diameter and was associated with the highest levels of b/sub scat/. A less common type with no peak above 0.5 ..mu..m was associated only with low values of b/sub scat/. On average, (NH/sub 4/)SO/sub 4/ plus associated water contributed 68% of the total light scattering due to particles during the summer of 1984. The measured light scattering coefficient, b/sub scat/, and (NH/sub 4/)/sub 2/SO/sub 4/ plus associated water were extremely well correlated. b/sub scat/ and total fine particle mass were not as well correlated, because the correlation between b/sub scat/ and non-sulfate fine mass was poor. The average calculated light scattering efficiency of (NH/sub 4/)/sub 2/SO/sub 4/ plus water was 4.2 m/sup 2//g. The higher values were associated with sulfur size distributions with a major peak above 0.5 ..mu..m.

  2. Atmospheric fate of oil matter adsorbed on sea salt particles under UV light

    NASA Astrophysics Data System (ADS)

    Vaitilingom, M.; Avij, P.; Huang, H.; Valsaraj, K. T.

    2014-12-01

    The presence of liquid petroleum hydrocarbons at the sea water surface is an important source of marine pollution. An oil spill in sea-water will most likely occur due to an involuntary accident from tankers, offshore platforms, etc. However, a large amount of oil is also deliberately spilled in sea-water during the clean-out process of tank vessels (e.g. for the Mediterranean Sea, 490,000 tons/yr). Moreover, the pollution caused by an oil spill does not only affect the aquatic environment but also is of concern for the atmospheric environment. A portion of the oil matter present at the sea-water surface is transported into the atmosphere viaevaporation and adsorption at the surface of sea spray particles. Few studies are related to the presence of oil matter in airborne particles resulting from their adsorption on sea salt aerosols. We observed that the non-volatile oil matter was adsorbed at the surface of sea-salt crystals (av. size of 1.1 μm). Due to their small size, these particles can have a significant residence time in the atmosphere. The hydrocarbon matter adsorbed at the surface of these particles can also be transformed by catalyzers present in the atmosphere (i.e. UV, OH, O3, ...). In this work, we focused on the photo-oxidation rates of the C16 to C30alkanes present in these particles. We utilized a bubble column reactor, which produced an abundance of small sized bubbles. These bubbles generated droplets upon bursting at the air-salt water interface. These droplets were then further dried up and lifted to the top of the column where they were collected as particles. These particles were incubated in a controlled reactor in either dark conditions or under UV-visible light. The difference of alkane content analyzed by GC-MS between the particles exposed to UV or the particles not exposed to UV indicated that up to 20% in mass was lost after 20 min of light exposure. The degradation kinetics varied for each range of alkanes (C16-20, C21-25, C26

  3. Cylindrical particle manipulation and negative spinning using a nonparaxial Hermite-Gaussian light-sheet beam

    NASA Astrophysics Data System (ADS)

    Mitri, F. G.

    2016-10-01

    Based on the angular spectrum decomposition method (ASDM), a nonparaxial solution for the Hermite-Gaussian (HG m ) light-sheet beam of any order m is derived. The beam-shape coefficients (BSCs) are expressed in a compact form and computed using the standard Simpson’s rule for numerical integration. Subsequently, the analysis is extended to evaluate the longitudinal and transverse radiation forces as well as the spin torque on an absorptive dielectric cylindrical particle in 2D without any restriction to a specific range of frequencies. The dynamics of the cylindrical particle are also examined based on Newton’s second law of motion. The numerical results show that a Rayleigh or Mie cylindrical particle can be trapped, pulled or propelled in the optical field depending on its initial position in the cross-sectional plane of the HG m light-sheet. Moreover, negative or positive axial spin torques can arise depending on the choice of the non-dimensional size parameter ka (where k is the wavenumber and a is the radius of the cylinder) and the location of the absorptive cylinder in the beam. This means that the HG m light-sheet beam can induce clockwise or anti-clockwise rotations depending on its shift from the center of the cylinder. In addition, individual vortex behavior can arise in the cross-sectional plane of wave propagation. The present analysis presents an analytical model to predict the optical radiation forces and torque induced by a HG m light-sheet beam on an absorptive cylinder for applications in optical light-sheet tweezers, optical micro-machines, particle manipulation and opto-fluidics to name a few areas of research.

  4. Fast and efficient loading of a Rb magneto-optical trap using light-induced atomic desorption

    SciTech Connect

    Atutov, S.N.; Calabrese, R.; Guidi, V.; Mai, B.; Rudavets, A.G.; Scansani, E.; Tomassetti, L.; Biancalana, V.; Burchianti, A.; Marinelli, C.; Mariotti, E.; Moi, L.; Veronesi, S.

    2003-05-01

    We have obtained fast loading of a rubidium magneto-optical trap and very high collection efficiency by capturing the atoms desorbed by a light flash from a polydimethylsiloxane film deposited on the internal surface of a cell. The atoms are trapped with an effective loading time of about 65 ms at a loading rate greater than 2x10{sup 8} atoms per second. This rate is larger than the values reported in literature and is obtained by preserving a long lifetime of the trapped atoms. This lifetime exceeds the filling time by nearly two orders of magnitude. Trap loading by light-induced desorption from siloxane compounds can be very effectively applied to store and trap a large number of atoms in the case of very weak atomic flux or extremely low vapor density. It can be also effectively used for fast production of ultracold atoms.

  5. Light scattering by randomly irregular dielectric particles larger than the wavelength.

    PubMed

    Grynko, Yevgen; Shkuratov, Yuriy; Förstner, Jens

    2013-12-01

    We present results of simulation of light scattering by randomly irregular particles that have dimensions larger than the wavelength of incident light. We apply the discontinuous Galerkin time domain method and compare the accurate solution with that obtained using an approximate geometric-optics model. A qualitative agreement is observed for scattering angle curves of intensity at the size parameter of X=60, whereas angular dependence of polarization appears to be more sensitive to the wave effects and requires larger sizes for application of geometrical optics.

  6. Particle and light fragment emission in peripheral heavy ion collisions at Fermi energies

    SciTech Connect

    Piantelli, S.; Maurenzig, P. R.; Olmi, A.; Bardelli, L.; Bartoli, A.; Bini, M.; Casini, G.; Coppi, C.; Mangiarotti, A.; Pasquali, G.; Poggi, G.; Stefanini, A. A.; Taccetti, N.; Vanzi, E.

    2006-09-15

    A systematic investigation of the average multiplicities of light charged particles and intermediate mass fragments emitted in peripheral and semiperipheral collisions is presented as a function of the beam energy, violence of the collision, and mass of the system. The data have been collected with the FIASCO setup in the reactions {sup 93}Nb+{sup 93}Nb at (17,23,30,38)A MeV and {sup 116}Sn+{sup 116}Sn at (30,38)A MeV. The midvelocity emission has been separated from the emission of the projectile-like fragment. This last component appears to be compatible with an evaporation from an equilibrated source at normal density, as described by the statistical code GEMINI at the appropriate excitation energy. On the contrary, the midvelocity emission presents remarkable differences in both the dependence of the multiplicities on the energy deposited in the midvelocity region and the isotopic composition of the emitted light charged particles.

  7. Phase transition observations and discrimination of small cloud particles by light polarization in expansion chamber experiments

    NASA Astrophysics Data System (ADS)

    Nichman, Leonid; Fuchs, Claudia; Järvinen, Emma; Ignatius, Karoliina; Florian Höppel, Niko; Dias, Antonio; Heinritzi, Martin; Simon, Mario; Tröstl, Jasmin; Wagner, Andrea Christine; Wagner, Robert; Williamson, Christina; Yan, Chao; Connolly, Paul James; Dorsey, James Robert; Duplissy, Jonathan; Ehrhart, Sebastian; Frege, Carla; Gordon, Hamish; Hoyle, Christopher Robert; Bjerring Kristensen, Thomas; Steiner, Gerhard; McPherson Donahue, Neil; Flagan, Richard; Gallagher, Martin William; Kirkby, Jasper; Möhler, Ottmar; Saathoff, Harald; Schnaiter, Martin; Stratmann, Frank; Tomé, António

    2016-03-01

    Cloud microphysical processes involving the ice phase in tropospheric clouds are among the major uncertainties in cloud formation, weather, and general circulation models. The detection of aerosol particles, liquid droplets, and ice crystals, especially in the small cloud particle-size range below 50 μm, remains challenging in mixed phase, often unstable environments. The Cloud Aerosol Spectrometer with Polarization (CASPOL) is an airborne instrument that has the ability to detect such small cloud particles and measure the variability in polarization state of their backscattered light. Here we operate the versatile Cosmics Leaving OUtdoor Droplets (CLOUD) chamber facility at the European Organization for Nuclear Research (CERN) to produce controlled mixed phase and other clouds by adiabatic expansions in an ultraclean environment, and use the CASPOL to discriminate between different aerosols, water, and ice particles. In this paper, optical property measurements of mixed-phase clouds and viscous secondary organic aerosol (SOA) are presented. We report observations of significant liquid-viscous SOA particle polarization transitions under dry conditions using CASPOL. Cluster analysis techniques were subsequently used to classify different types of particles according to their polarization ratios during phase transition. A classification map is presented for water droplets, organic aerosol (e.g., SOA and oxalic acid), crystalline substances such as ammonium sulfate, and volcanic ash. Finally, we discuss the benefits and limitations of this classification approach for atmospherically relevant concentrations and mixtures with respect to the CLOUD 8-9 campaigns and its potential contribution to tropical troposphere layer analysis.

  8. An investigation into particle shape effects on the light scattering properties of mineral dust aerosol

    NASA Astrophysics Data System (ADS)

    Meland, Brian Steven

    Mineral dust aerosol plays an important role in determining the physical and chemical equilibrium of the atmosphere. The radiative balance of the Earth's atmosphere can be affected by mineral dust through both direct and indirect means. Mineral dust can directly scatter or absorb incoming visible solar radiation and outgoing terrestrial IR radiation. Dust particles can also serve as cloud condensation nuclei, thereby increasing albedo, or provide sites for heterogeneous reactions with trace gas species, which are indirect effects. Unfortunately, many of these processes are poorly understood due to incomplete knowledge of the physical and chemical characteristics of the particles including dust concentration and global distribution, as well as aerosol composition, mixing state, and size and shape distributions. Much of the information about mineral dust aerosol loading and spatial distribution is obtained from remote sensing measurements which often rely on measuring the scattering or absorption of light from these particles and are thus subject to errors arising from an incomplete understanding of the scattering processes. The light scattering properties of several key mineral components of atmospheric dust have been measured at three different wavelengths in the visible. In addition, measurements of the scattering were performed for several authentic mineral dust aerosols, including Saharan sand, diatomaceous earth, Iowa loess soil, and palagonite. These samples include particles that are highly irregular in shape. Using known optical constants along with measured size distributions, simulations of the light scattering process were performed using both Mie and T-Matrix theories. Particle shapes were approximated as a distribution of spheroids for the T-Matrix calculations. It was found that the theoretical model simulations differed markedly from experimental measurements of the light scattering, particularly near the mid-range and near backscattering angles. In

  9. PARTICLE-HOLE NATURE OF THE LIGHT HIGH-SPIN TOROIDAL ISOMERS

    SciTech Connect

    Staszczak, A.; Wong, Cheuk-Yin

    2015-01-01

    Nuclei under non-collective rotation with a large angular momentum above some threshold can assume a toroidal shape. In our previous work, we showed by using cranked Skyrme Hartree Fock approach that even even, N = Z, high-K, toroidal isomeric states may have general occurrences for light nuclei with 28 < A < 52. We present here some additional results and systematics on the particle-hole nature of these high-spin toroidal isomers.

  10. Advances in Thermal Spray Deposition of Billets for Particle Reinforced Light Metals

    NASA Astrophysics Data System (ADS)

    Wenzelburger, Martin; Zimmermann, Christian; Gadow, Rainer

    2007-04-01

    Forming of light-metals in semi-solid state offers some advantages like low process temperatures, improved mould durability, good flow behavior and fine, globular microstructure of the final material. By the introduction of ceramic particles, increased elastic modulus and yield strength as well as wear resistance and creep behavior can be obtained. By semi-solid forging or semi-solid casting, particle reinforced metals (PRM) can be produced with improved matrix microstructure and beneficial forming process parameters compared to conventional MMC manufacturing techniques. The production of this kind of light metal matrix composites requires the supply of dense semi-finished parts with well defined volume fractions of homogeneously distributed particulate reinforcement. A manufacturing method for cylindrical light metal billets is described that applies thermal spraying as a build-up process for simultaneous deposition of matrix and reinforcement phase with cored wires as spraying material. Thermal spraying leads to small grain sizes and prevents dendrite formation. However, long process cycle times lead to billet heating and recrystallization of the matrix microstructure. In order to preserve small grain sizes that enable semi-solid forming, the thermal spraying process was analyzed by in-flight particle analysis and thermography. As a consequence, the deposition process was optimized by adaptation of the thermal spraying parameters and by application of additional cooling, leading to lower billet temperatures and finer PRM billet microstructure.

  11. Advances in Thermal Spray Deposition of Billets for Particle Reinforced Light Metals

    SciTech Connect

    Wenzelburger, Martin; Zimmermann, Christian; Gadow, Rainer

    2007-04-07

    Forming of light-metals in semi-solid state offers some advantages like low process temperatures, improved mould durability, good flow behavior and fine, globular microstructure of the final material. By the introduction of ceramic particles, increased elastic modulus and yield strength as well as wear resistance and creep behavior can be obtained. By semi-solid forging or semi-solid casting, particle reinforced metals (PRM) can be produced with improved matrix microstructure and beneficial forming process parameters compared to conventional MMC manufacturing techniques. The production of this kind of light metal matrix composites requires the supply of dense semi-finished parts with well defined volume fractions of homogeneously distributed particulate reinforcement. A manufacturing method for cylindrical light metal billets is described that applies thermal spraying as a build-up process for simultaneous deposition of matrix and reinforcement phase with cored wires as spraying material. Thermal spraying leads to small grain sizes and prevents dendrite formation. However, long process cycle times lead to billet heating and recrystallization of the matrix microstructure. In order to preserve small grain sizes that enable semi-solid forming, the thermal spraying process was analyzed by in-flight particle analysis and thermography. As a consequence, the deposition process was optimized by adaptation of the thermal spraying parameters and by application of additional cooling, leading to lower billet temperatures and finer PRM billet microstructure.

  12. Light-particle-complex-fragment coincidence cross sections from intermediate energy nucleus-nucleus collisions

    SciTech Connect

    Hasselquist, B.E.; Crawley, G.M.; Jacak, B.V.; Koenig, Z.M.; Westfall, G.D.; Yurkon, J.E.; Tickle, R.S.; Dufour, J.P.; Symons, T.J.M.

    1985-07-01

    Light-particle (Zlight-particle spectra were intermediate rapidity fragments (3light-particle spectra triggered by projectilelike fragments. A single moving source parametrization is employed throughout to extract the relevant trends in the inclusive and coincidence data. The coincidence spectra are compared with a model based on the moving source model but incorporating momentum conservation to account for kinematical biases. Little difference between inclusive and complex-fragment-triggered coincidence cross sections is observed, indicating that all the fragments have a common source.

  13. Metal Optics Based nanoLEDs: In Search of a Fast, Efficient, Nanoscale Light Emitter

    NASA Astrophysics Data System (ADS)

    Eggleston, Michael Scott

    Since the invention of the laser, stimulated emission has been the de facto king of optical communication. Lasers can be directly modulated at rates as high as 50GHz, much faster than a typical solid state light-emitting diode (LED) that is limited by spontaneous emission to <1GHz. Unfortunately, lasers have a severe scaling problem; they require large cavities operated at high power to achieve efficient lasing. A properly designed LED can be made arbitrarily small and still operate with high-efficiency. On-chip interconnects is an area that is in desperate need of a high-speed, low-power optical emitter that can enable on-chip links to replace current high-loss metal wires. In this work, I will show that by utilizing proper antenna design, a nanoLED can be created that is faster than a laser while still operating at >50% efficiency. I start by formulating an optical antenna circuit model whose elements are based completely off of antenna geometry. This allows for intuitive antenna design and suggests that rate enhancements up to ~3,000x are possible while keeping antenna efficiency >50%. Such a massive speed-up in spontaneous emission would enable an LED that can be directly modulated at 100's of GHz, much faster than any laser. I then use the circuit model to design an arch-dipole antenna, a dipole antenna with an inductive arch across the feedgap. I experimentally demonstrate a free-standing arch-dipole based nanoLED with rate enhancement of 115x and 66% antenna efficiency. Because the emitter is InGaAsP, a common III-V material, I experimentally show that this device can be easily and efficiently coupled into an InP waveguide. Experimental coupling efficiencies up to 70% are demonstrated and directional antennas are employed that offer front to back emission ratios of 3:1. Finally, I show that a nanoLED can still have high quantum yield by using a transition metal dichalcogenide, WSe2, as the emitter material. By coupling a monolayer of WSe2 to a cavity

  14. The Fast-Evolving phy-2 Gene Modulates Sexual Development in Response to Light in the Model Fungus Neurospora crassa

    PubMed Central

    Wang, Zheng; Li, Ning; Li, Jigang; Dunlap, Jay C.; Trail, Frances

    2016-01-01

    ABSTRACT Rapid responses to changes in incident light are critical to the guidance of behavior and development in most species. Phytochrome light receptors in particular play key roles in bacterial physiology and plant development, but their functions and regulation are less well understood in fungi. Nevertheless, genome-wide expression measurements provide key information that can guide experiments that reveal how genes respond to environmental signals and clarify their role in development. We performed functional genomic and phenotypic analyses of the two phytochromes in Neurospora crassa, a fungal model adapted to a postfire environment that experiences dramatically variable light conditions. Expression of phy-1 and phy-2 was low in early sexual development and in the case of phy-2 increased in late sexual development. Under light stimulation, strains with the phytochromes deleted exhibited increased expression of sexual development-related genes. Moreover, under red light, the phy-2 knockout strain commenced sexual development early. In the evolution of phytochromes within ascomycetes, at least two duplications have occurred, and the faster-evolving phy-2 gene has frequently been lost. Additionally, the three key cysteine sites that are critical for bacterial and plant phytochrome function are not conserved within fungal phy-2 homologs. Through the action of phytochromes, transitions between asexual and sexual reproduction are modulated by light level and light quality, presumably as an adaptation for fast asexual growth and initiation of sexual reproduction of N. crassa in exposed postfire ecosystems. PMID:26956589

  15. A computer controlled television detector for light, X-rays and particles

    NASA Technical Reports Server (NTRS)

    Kalata, K.

    1981-01-01

    A versatile, high resolution, software configurable, two-dimensional intensified vidicon quantum detector system has been developed for multiple research applications. A thin phosphor convertor allows the detection of X-rays below 20 keV and non-relativistic particles in addition to visible light, and a thicker scintillator can be used to detect X-rays up to 100 keV and relativistic particles. Faceplates may be changed to allow any active area from 1 to 40 mm square, and active areas up to 200 mm square are possible. The image is integrated in a digital memory on any software specified array size up to 4000 x 4000. The array size is selected to match the spatial resolution, which ranges from 10 to 100 microns depending on the operating mode, the active area, and the photon or particle energy. All scan and data acquisition parameters are under software control to allow optimal data collection for each application.

  16. Plasmonic particles set into fast orbital motion by an optical vortex beam.

    PubMed

    Lehmuskero, Anni; Li, Yanming; Johansson, Peter; Käll, Mikael

    2014-02-24

    We optically trap plasmonic gold particles in two dimensions and set them into circular motion around the optical axis using a helically phased vortex laser beam. The orbiting frequency of the particles reaches 86 Hz, which corresponds to a particle velocity of the order 1 mm per second, for an incident laser power of a few tens of milliwatts. The experimentally determined orbiting frequencies are found to be well in line with the notion that the beam carries an orbital angular momentum of ħl per photon.

  17. Manipulation of small particles at solid liquid interface: light driven diffusioosmosis

    PubMed Central

    Feldmann, David; Maduar, Salim R.; Santer, Mark; Lomadze, Nino; Vinogradova, Olga I.; Santer, Svetlana

    2016-01-01

    The strong adhesion of sub-micron sized particles to surfaces is a nuisance, both for removing contaminating colloids from surfaces and for conscious manipulation of particles to create and test novel micro/nano-scale assemblies. The obvious idea of using detergents to ease these processes suffers from a lack of control: the action of any conventional surface-modifying agent is immediate and global. With photosensitive azobenzene containing surfactants we overcome these limitations. Such photo-soaps contain optical switches (azobenzene molecules), which upon illumination with light of appropriate wavelength undergo reversible trans-cis photo-isomerization resulting in a subsequent change of the physico-chemical molecular properties. In this work we show that when a spatial gradient in the composition of trans- and cis- isomers is created near a solid-liquid interface, a substantial hydrodynamic flow can be initiated, the spatial extent of which can be set, e.g., by the shape of a laser spot. We propose the concept of light induced diffusioosmosis driving the flow, which can remove, gather or pattern a particle assembly at a solid-liquid interface. In other words, in addition to providing a soap we implement selectivity: particles are mobilized and moved at the time of illumination, and only across the illuminated area. PMID:27808170

  18. Manipulation of small particles at solid liquid interface: light driven diffusioosmosis

    NASA Astrophysics Data System (ADS)

    Feldmann, David; Maduar, Salim R.; Santer, Mark; Lomadze, Nino; Vinogradova, Olga I.; Santer, Svetlana

    2016-11-01

    The strong adhesion of sub-micron sized particles to surfaces is a nuisance, both for removing contaminating colloids from surfaces and for conscious manipulation of particles to create and test novel micro/nano-scale assemblies. The obvious idea of using detergents to ease these processes suffers from a lack of control: the action of any conventional surface-modifying agent is immediate and global. With photosensitive azobenzene containing surfactants we overcome these limitations. Such photo-soaps contain optical switches (azobenzene molecules), which upon illumination with light of appropriate wavelength undergo reversible trans-cis photo-isomerization resulting in a subsequent change of the physico-chemical molecular properties. In this work we show that when a spatial gradient in the composition of trans- and cis- isomers is created near a solid-liquid interface, a substantial hydrodynamic flow can be initiated, the spatial extent of which can be set, e.g., by the shape of a laser spot. We propose the concept of light induced diffusioosmosis driving the flow, which can remove, gather or pattern a particle assembly at a solid-liquid interface. In other words, in addition to providing a soap we implement selectivity: particles are mobilized and moved at the time of illumination, and only across the illuminated area.

  19. Manipulation of small particles at solid liquid interface: light driven diffusioosmosis.

    PubMed

    Feldmann, David; Maduar, Salim R; Santer, Mark; Lomadze, Nino; Vinogradova, Olga I; Santer, Svetlana

    2016-11-03

    The strong adhesion of sub-micron sized particles to surfaces is a nuisance, both for removing contaminating colloids from surfaces and for conscious manipulation of particles to create and test novel micro/nano-scale assemblies. The obvious idea of using detergents to ease these processes suffers from a lack of control: the action of any conventional surface-modifying agent is immediate and global. With photosensitive azobenzene containing surfactants we overcome these limitations. Such photo-soaps contain optical switches (azobenzene molecules), which upon illumination with light of appropriate wavelength undergo reversible trans-cis photo-isomerization resulting in a subsequent change of the physico-chemical molecular properties. In this work we show that when a spatial gradient in the composition of trans- and cis- isomers is created near a solid-liquid interface, a substantial hydrodynamic flow can be initiated, the spatial extent of which can be set, e.g., by the shape of a laser spot. We propose the concept of light induced diffusioosmosis driving the flow, which can remove, gather or pattern a particle assembly at a solid-liquid interface. In other words, in addition to providing a soap we implement selectivity: particles are mobilized and moved at the time of illumination, and only across the illuminated area.

  20. [Light scattering extinction properties of atmospheric particle and pollution characteristics in hazy weather in Hangzhou].

    PubMed

    Xu, Chang; Ye, Hui; Shen, Jian-Dong; Sun, Hong-Liang; Hong, Sheng-Mao; Jiao, Li; Huang, Kan

    2014-12-01

    In order to evaluate the influence of particle scattering on visibility, light scattering coefficient, particle concentrations and meteorological factor were simultaneously monitored from July 2011 to June 2012 in Hangzhou. Daily scattering coefficients ranged from 108.4 to 1 098.1 Mm(-1), with an annual average concentration of 428.6 Mm(-1) ± 200.2 Mm(-1). Seasonal variation of scattering coefficients was significant, with the highest concentrations observed in autumn and winter and the lowest in summer. It was found there were two peaks for the average diurnal variations of the scattering coefficient, which could be observed at 08:00 and 21:00. The scattering efficiencies of PM2.5 and PM10 were 7.6 m2 x g(-1) and 4.4 m2 x g(-1), respectively. The particle scattering was about 90.2 percent of the total light extinction. The scattering coefficients were 684.4 Mm(-1) ± 218.1 Mm(-1) and 1 095.4 Mm(-1) ± 397.7 Mm(-1) in hazy and heavy hazy days, respectively, which were 2.6 and 4.2 times as high as in non-hazy weather, indicating that particle scattering is the main factor for visibility degradation and the occurrence of hazy weather in Hangzhou.

  1. Determination of single particle mass spectral signatures from light-duty vehicle emissions.

    PubMed

    Sodeman, David A; Toner, Stephen M; Prather, Kimberly A

    2005-06-15

    In this study, 28 light-duty gasoline vehicles (LDV) were operated on a chassis dynamometer at the California Air Resources Board Haagen-Smit Facility in El Monte, CA. The mass spectra of individual particles emitted from these vehicles were measured using aerosol time-of-flight mass spectrometry (ATOFMS). A primary goal of this study involves determining representative size-resolved single particle mass spectral signatures that can be used in future ambient particulate matter source apportionment studies. Different cycles were used to simulate urban driving conditions including the federal testing procedure (FTP), unified cycle (UC), and the correction cycle (CC). The vehicles were selected to span a range of catalytic converter (three-way, oxidation, and no catalysts) and engine technologies (vehicles models from 1953 to 2003). Exhaust particles were sampled directly from a dilution and residence chamber system using particle sizing instruments and an ATOFMS equipped with an aerodynamic lens (UF-ATOFMS) analyzing particles between 50 and 300 nm. On the basis of chemical composition, 10 unique chemical types describe the majority of the particles with distinct size and temporal characteristics. In the ultrafine size range (between 50 and 100 nm), three elemental carbon (EC) particle types dominated, all showing distinct EC signatures combined with Ca, phosphate, sulfate, and a lower abundance of organic carbon (OC). The relative fraction of EC particle types decreased as particle size increased with OC particles becoming more prevalent above 100 nm. Depending on the vehicle and cycle, several distinct OC particle types produced distinct ion patterns, including substituted aromatic compounds and polycyclic aromatic hydrocarbons (PAH), coupled with other chemical species including ammonium, EC, nitrate, sulfate, phosphate, V, and Ca. The most likely source of the Ca and phosphate in the particles is attributed to the lubricating oil. Significant variability was

  2. A fast and explicit algorithm for simulating the dynamics of small dust grains with smoothed particle hydrodynamics

    NASA Astrophysics Data System (ADS)

    Price, Daniel J.; Laibe, Guillaume

    2015-07-01

    We describe a simple method for simulating the dynamics of small grains in a dusty gas, relevant to micron-sized grains in the interstellar medium and grains of centimetre size and smaller in protoplanetary discs. The method involves solving one extra diffusion equation for the dust fraction in addition to the usual equations of hydrodynamics. This `diffusion approximation for dust' is valid when the dust stopping time is smaller than the computational timestep. We present a numerical implementation using smoothed particle hydrodynamics that is conservative, accurate and fast. It does not require any implicit timestepping and can be straightforwardly ported into existing 3D codes.

  3. Edge-effect contribution to the extinction of light by dielectric disks and cylindrical particles.

    PubMed

    Bi, Lei; Yang, Ping; Kattawar, George W

    2010-08-20

    The extinction efficiency factor associated with the scattering of a plane electromagnetic wave impinging on a basal face of a dielectric disk or a cylindrical particle is investigated by employing the physical-geometric optics hybrid (PGOH) method and the discrete-dipole approximation (DDA) method. It is found that the derived extinction efficiency factor from the PGOH is a function of the thickness of the disk, or the length of the cylinder, and the refractive index, but is independent of the diameter and shape of the cross section of the basal face of the particle. Furthermore, the oscillations of the extinction efficiency factor versus the thickness or length of the particle do not diminish if the particle is not absorptive. The values of the extinction efficiency factor simulated from the DDA method are quite different from those computed from the PGOH, although the size parameter of the particle is in the commonly recognized geometric optics regime. To explain the difference, the concept of the edge effect associated with the tunneling rays in the semiclassical scattering theory is generalized from the case of spherical particles to that of nonspherical particles based on the localization principle. Accordingly, the edge-effect contribution can be distinguished and removed from the extinction cross section calculation by the DDA method. The remaining part of the extinction cross section, associated with the interference between the transmitted rays and incident rays, agrees well with the results computed from the PGOH, and the agreement illustrates the presence of the edge effect in the case of nonspherical particles with surfaces that have no curvature along the incident direction. It is found that the asymptotic extinction efficiency factor may not necessarily converge to 2, but it depends on the specific physical processes of the interference between diffracted and transmitted light and of the edge effect.

  4. Light induced changes in Raman scattering of carotenoid molecules in Photosystem I particles

    NASA Astrophysics Data System (ADS)

    Andreeva, Atanaska; Abarova, Silviya; Stoitchkova, Katerina; Velitchkova, Maya

    2007-03-01

    The photosynthetic antenna systems are able to regulate the light energy harvesting under different light conditions by dynamic changes in their protein structure protecting the reaction center complexes. The changes modulate the electronic structure of the main antenna pigments (chlorophylls and carotenoids) and distort the characteristic planar structure of carotenoids, allowing their forbidden out of plane vibrations. Electronic absorption and low-temperature resonance Raman spectroscopy were used to study the changes in composition and spectral properties of the major carotenoids in spinach Photosystem I particles due to high light treatment. The duration of the applied intensity of the white light (1800 μE m -2 s -1) was 30, 60 and 120 minutes. We used Raman scattering in an attempt to recognize the type and conformation of photobleached carotenoid molecules. The resonance Raman spectra were measured at 488 and 514.5 nm, coinciding with the absorption maximum positions of the carotenoids neoxanthin and lutein, correspondingly. The results revealed nearly a full photobleaching of the long wavelength lutein molecules, whereas the bleaching of neoxantin molecules is negligible. The involvement of these changes in the photoprotection and photoinactivation of the Photosystem I particles was discussed.

  5. Pharmaceutical feasibility of sub-visible particle analysis in parenterals with reduced volume light obscuration methods.

    PubMed

    Hawe, Andrea; Schaubhut, Frank; Geidobler, Raimund; Wiggenhorn, Michael; Friess, Wolfgang; Rast, Markus; de Muynck, Christian; Winter, Gerhard

    2013-11-01

    The draft for a new United States Pharmacopoeia (USP) monograph {787} "Sub-visible Particulate Matter in Therapeutic Protein Injections" describes the analysis of sub-visible particles by light obscuration at much lower sample volumes as so far required by the European Pharmacopoeia (Ph. Eur.) and the USP for parenterals in general. Our aim was to show the feasibility of minimizing the sample expenditure required for light obscuration similar to the new USP settings for standards and pharmaceutically relevant samples (both proteins and small molecules), without compromising the data quality. The light obscuration method was downscaled from >20 ml volume as so far specified in Ph. Eur./USP to 1 ml total sample volume. Comparable results for the particle concentration in all tested size classes were obtained with both methods for polystyrene standards, stressed BSA solutions, recombinant human IgG1 formulations, and pantoprazol i.v. solution. An additional advantage of the low volume method is the possibility to detect vial-to-vial variations, which are leveled out when pooling several vials to achieve sufficient volume for the Ph. Eur./USP method. This is in particular important for biotech products where not only the general quality aspect, but also aggregate formation of the drug substance is monitored by light obscuration.

  6. Fast computation of radiation pressure force exerted by multiple laser beams on red blood cell-like particles

    NASA Astrophysics Data System (ADS)

    Gou, Ming-Jiang; Yang, Ming-Lin; Sheng, Xin-Qing

    2016-10-01

    Mature red blood cells (RBC) do not contain huge complex nuclei and organelles, makes them can be approximately regarded as homogeneous medium particles. To compute the radiation pressure force (RPF) exerted by multiple laser beams on this kind of arbitrary shaped homogenous nano-particles, a fast electromagnetic optics method is demonstrated. In general, based on the Maxwell's equations, the matrix equation formed by the method of moment (MOM) has many right hand sides (RHS's) corresponding to the different laser beams. In order to accelerate computing the matrix equation, the algorithm conducts low-rank decomposition on the excitation matrix consisting of all RHS's to figure out the so-called skeleton laser beams by interpolative decomposition (ID). After the solutions corresponding to the skeletons are obtained, the desired responses can be reconstructed efficiently. Some numerical results are performed to validate the developed method.

  7. Indoor anti-occlusion visible light positioning systems based on particle filtering

    NASA Astrophysics Data System (ADS)

    Jiang, Meng; Huang, Zhitong; Li, Jianfeng; Zhang, Ruqi; Ji, Yuefeng

    2015-04-01

    As one of the most popular categories of mobile services, a rapid growth of indoor location-based services has been witnessed over the past decades. Indoor positioning methods based on Wi-Fi, radio-frequency identification or Bluetooth are widely commercialized; however, they have disadvantages such as low accuracy or high cost. An emerging method using visible light is under research recently. The existed visible light positioning (VLP) schemes using carrier allocation, time allocation and multiple receivers all have limitations. This paper presents a novel mechanism using particle filtering in VLP system. By this method no additional devices are needed and the occlusion problem in visible light would be alleviated which will effectively enhance the flexibility for indoor positioning.

  8. Charactrisation of particle assemblies by 3D cross correlation light scattering and diffusing wave spectroscopy

    NASA Astrophysics Data System (ADS)

    Scheffold, Frank

    2014-08-01

    To characterize the structural and dynamic properties of soft materials and small particles, information on the relevant mesoscopic length scales is required. Such information is often obtained from traditional static and dynamic light scattering (SLS/DLS) experiments in the single scattering regime. In many dense systems, however, these powerful techniques frequently fail due to strong multiple scattering of light. Here I will discuss some experimental innovations that have emerged over the last decade. New methods such as 3D static and dynamic light scattering (3D LS) as well as diffusing wave spectroscopy (DWS) can cover a much extended range of experimental parameters ranging from dilute polymer solutions, colloidal suspensions to extremely opaque viscoelastic emulsions.

  9. Lidar remote sensing of laser-induced incandescence on light absorbing particles in the atmosphere.

    PubMed

    Miffre, Alain; Anselmo, Christophe; Geffroy, Sylvain; Fréjafon, Emeric; Rairoux, Patrick

    2015-02-09

    Carbon aerosol is now recognized as a major uncertainty on climate change and public health, and specific instruments are required to address the time and space evolution of this aerosol, which efficiently absorbs light. In this paper, we report an experiment, based on coupling lidar remote sensing with Laser-Induced-Incandescence (LII), which allows, in agreement with Planck's law, to retrieve the vertical profile of very low thermal radiation emitted by light-absorbing particles in an urban atmosphere over several hundred meters altitude. Accordingly, we set the LII-lidar formalism and equation and addressed the main features of LII-lidar in the atmosphere by numerically simulating the LII-lidar signal. We believe atmospheric LII-lidar to be a promising tool for radiative transfer, especially when combined with elastic backscattering lidar, as it may then allow a remote partitioning between strong/less light absorbing carbon aerosols.

  10. Beam-splitting code for light scattering by ice crystal particles within geometric-optics approximation

    NASA Astrophysics Data System (ADS)

    Konoshonkin, Alexander V.; Kustova, Natalia V.; Borovoi, Anatoli G.

    2015-10-01

    The open-source beam-splitting code is described which implements the geometric-optics approximation to light scattering by convex faceted particles. This code is written in C++ as a library which can be easy applied to a particular light scattering problem. The code uses only standard components, that makes it to be a cross-platform solution and provides its compatibility to popular Integrated Development Environments (IDE's). The included example of solving the light scattering by a randomly oriented ice crystal is written using Qt 5.1, consequently it is a cross-platform solution, too. Both physical and computational aspects of the beam-splitting algorithm are discussed. Computational speed of the beam-splitting code is obviously higher compared to the conventional ray-tracing codes. A comparison of the phase matrix as computed by our code with the ray-tracing code by A. Macke shows excellent agreement.

  11. Characterization and ontogenetic expression analysis of the myosin light chains from the fast white muscle of mandarin fish Siniperca chuatsi.

    PubMed

    Chu, W Y; Chen, J; Zhou, R X; Zhao, F L; Meng, T; Chen, D X; Nong, X X; Liu, Z; Lu, S Q; Zhang, J S

    2011-04-01

    Three full-length complementary DNA (cDNA) clones were isolated encoding the skeletal myosin light chain 1 (MLC1; 1237 bp), myosin light chain 2 (MLC2; 1206 bp) and myosin light chain 3 (MLC3; 1079 bp) from the fast white muscle cDNA library of mandarin fish Siniperca chuatsi. The sequence analysis indicated that MLC1 and MLC3 were not produced from differentially spliced messenger RNAs (mRNA) as reported in birds and rodents but were encoded by different genes. The MLC2 encodes 170 amino acids, which include four EF-hand (helix-loop-helix) structures. The primary structures of the Ca(2+)-binding domain were well conserved among the MLC2s of seven other fish species. The ontogenetic expression analysis by real-time PCR showed that the three light-chain mRNAs were first detected in the gastrula stage, and their expression increased from the tail bud stage to the larval stage. All three MLC mRNAs showed longitudinal expression variation in the fast white muscle of S. chuatsi, especially MLC1 which was highly expressed at the posterior area. Taken together, the study provides a better understanding about the MLC gene structure and their expression pattern in muscle development of S. chuatsi.

  12. Light Emission Intensities of Luminescent Y2O3:Eu and Gd2O3:Eu Particles of Various Sizes

    PubMed Central

    Adam, Jens; Metzger, Wilhelm; Koch, Marcus; Rogin, Peter; Coenen, Toon; Atchison, Jennifer S.; König, Peter

    2017-01-01

    There is great technological interest in elucidating the effect of particle size on the luminescence efficiency of doped rare earth oxides. This study demonstrates unambiguously that there is a size effect and that it is not dependent on the calcination temperature. The Y2O3:Eu and Gd2O3:Eu particles used in this study were synthesized using wet chemistry to produce particles ranging in size between 7 nm and 326 nm and a commercially available phosphor. These particles were characterized using three excitation methods: UV light at 250 nm wavelength, electron beam at 10 kV, and X-rays generated at 100 kV. Regardless of the excitation source, it was found that with increasing particle diameter there is an increase in emitted light. Furthermore, dense particles emit more light than porous particles. These results can be explained by considering the larger surface area to volume ratio of the smallest particles and increased internal surface area of the pores found in the large particles. For the small particles, the additional surface area hosts adsorbates that lead to non-radiative recombination, and in the porous particles, the pore walls can quench fluorescence. This trend is valid across calcination temperatures and is evident when comparing particles from the same calcination temperature. PMID:28336860

  13. Plasma produced by impacts of fast dust particles on a thin film

    NASA Technical Reports Server (NTRS)

    Auer, Siegfried

    1994-01-01

    The thin-film impact plasma detector was pioneered by Berg for detecting small cosmic dust particles and measuring their approximate velocities in a time-of-flight configuration. While Berg's device was highly successful in establishing the flux of interplanetary dust, the accuracy of measuring the velocities of individual particles was a moderate 18 percent in magnitude and 27 degrees in angle. A much greater accuracy of less than or equal to 1 percent in determining the velocity components appears desirable in order to associate a particle with its parent body. In order to meet that need, research was initiated to determine if a thin-film detector can be designed to provide such accurate velocity measurements. Previous laboratory investigations of the impact plasma uncovered two difficulties: (1) solid or liquid spray is ejected from a primary impact crater and strikes neighboring walls where it produces secondary impact craters and plasma clouds; as a result, both quantity and time of detection of the plasma can vary significantly with the experiment configuration. Particles from an accelerator rarely have speeds v greater than or equal to 10-15 km/s, while cosmic dust particles typically impact at v = 10-72 km/s. The purpose of the tests discussed in this paper was to resolve the two difficulties mentioned. That is, the experiment configuration was designed to reduce the contribution of plasma from secondary impacts. In addition, most particles with v less than or equal to 25 km/s and all particles with v less than or equal to 10 km/s were eliminated from the beam.

  14. UV Attenuation Near Coral Reefs in the Florida Keys: Light Absorption by CDOM and Particles

    NASA Astrophysics Data System (ADS)

    Shank, G. C.; Zepp, R. G.; Bartels, E.

    2005-12-01

    We have investigated the roles of chromophoric dissolved organic matter (CDOM) and suspended particles in the attenuation of UV radiation in the middle and lower regions of the Florida Keys. Extended exposure to UV radiation, along with elevated sea surface temperatures, impairs physiological processes in corals and contributes to bleaching episodes. Corals in the Florida Keys experience large variations in UV exposure due to several factors including tidal exchange and fluctuating meteorological conditions. CDOM derived from mangroves and seagrass beds is the primary attenuator of UV radiation near coral reefs in our study area. CDOM accounts for more than 90 percent of the absorption of UVB irradiance (305 nm) throughout the region. However, we have determined using the quantitative filter technique that up to 25 percent of the downwelling UVA irradiance at 380 nm may be directly absorbed by suspended particles. Resuspension from within or near the reef structure appears to be the primary particle source as phytoplankton pigments typically comprise less than 20 percent of the particle UV absorption capacity near reef sampling sites. Our research also has implications for remote sensing applications as light absorbed by particles must be considered when modeling optical data from satellites. Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.

  15. Fast Simulation of Membrane Filtration by Combining Particle Retention Mechanisms and Network Models

    NASA Astrophysics Data System (ADS)

    Krupp, Armin; Griffiths, Ian; Please, Colin

    2016-11-01

    Porous membranes are used for their particle retention capabilities in a wide range of industrial filtration processes. The underlying mechanisms for particle retention are complex and often change during the filtration process, making it hard to predict the change in permeability of the membrane during the process. Recently, stochastic network models have been shown to predict the change in permeability based on retention mechanisms, but remain computationally intensive. We show that the averaged behaviour of such a stochastic network model can efficiently be computed using a simple partial differential equation. Moreover, we also show that the geometric structure of the underlying membrane and particle-size distribution can be represented in our model, making it suitable for modelling particle retention in interconnected membranes as well. We conclude by demonstrating the particular application to microfluidic filtration, where the model can be used to efficiently compute a probability density for flux measurements based on the geometry of the pores and particles. A. U. K. is grateful for funding from Pall Corporation and the Mathematical Institute, University of Oxford. I.M.G. gratefully acknowledges support from the Royal Society through a University Research Fellowship.

  16. Performance of a fast digital integrator in on-field magnetic measurements for particle accelerators.

    PubMed

    Arpaia, P; Bottura, L; Fiscarelli, L; Walckiers, L

    2012-02-01

    The fast digital integrator has been conceived to face most demanding magnet test requirements with a resolution of 10 ppm, a signal-to-noise ratio of 105 dB at 20 kHz, a time resolution of 50 ns, an offset of 10 ppm, and on-line processing. In this paper, the on-field achievements of the fast digital integrator are assessed by a specific measurement campaign at the European Organization for Nuclear Research (CERN). At first, the architecture and the metrological specifications of the instrument are reported. Then, the recent on-field achievements of (i) ±10 ppm of uncertainty in the measurement of the main field for superconducting magnets characterization, (ii) ±0.02 % of field uncertainty in quality assessment of small-aperture permanent magnets, and (iii) ±0.15 % of drift, in an excitation current measurement of 600 s under cryogenic conditions, are presented and discussed.

  17. Calculation of energy relaxation rates of fast particles by phonons in crystals

    NASA Astrophysics Data System (ADS)

    Prange, Micah; Campbell, Luke; Wu, Dangxin; Kerisit, Sebastien

    2015-03-01

    We present ab initio calculations of the temperature-dependent exchange of energy between a classical charged point-particle and the phonons of a crystalline material. The phonons, which are computed using density functional perturbation theory (DFPT) methods, interact with the moving particle via the Coulomb interaction between the density induced in the material by phonon excitation and the charge of the classical particle. Energy relaxation rates are computed using time-dependent perturbation theory. The method, which is applicable wherever DFPT is, is illustrated with results for several important scintillators whose performance is affected by electron thermalization. We discuss the influence of the form assumed for quasiparticle dispersion on theoretical estimates of electron cooling rates. This research was supported by the National Nuclear Security Administration, Office of DNN R&D, of the DOE. PNNL is operated by Battelle Memorial Institute under Contract DE-AC0576RL01830.

  18. Theoretical study of the light pressure force acting on a spherical dielectric particle of an arbitrary size in the interference field of two plane monochromatic electromagnetic waves

    SciTech Connect

    Guzatov, D V; Gaida, L S; Afanas'ev, Anatolii A

    2008-12-31

    The light pressure force acting on a spherical dielectric particle in the interference field of two plane monochromatic electromagnetic waves is studied in detail for different particle radii and angles of incidence of waves. (light pressure)

  19. Construction of a fast ionization chamber for high-rate particle identification

    NASA Astrophysics Data System (ADS)

    Chae, K. Y.; Ahn, S.; Bardayan, D. W.; Chipps, K. A.; Manning, B.; Pain, S. D.; Peters, W. A.; Schmitt, K. T.; Smith, M. S.; Strauss, S. Y.

    2014-07-01

    A new gas-filled ionization chamber for high count rate particle identification has been constructed and commissioned at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). To enhance the response time of the ionization chamber, a design utilizing a tilted entrance window and tilted electrodes was adopted, which is modified from an original design by Kimura et al. [1]. A maximum counting rate of 700 , 000 particles per second has been achieved. The detector has been used for several radioactive beam measurements performed at the HRIBF.

  20. Mixing states of light-absorbing particles measured using a transmission electron microscope and a single-particle soot photometer in Tokyo, Japan

    NASA Astrophysics Data System (ADS)

    Adachi, Kouji; Moteki, Nobuhiro; Kondo, Yutaka; Igarashi, Yasuhito

    2016-08-01

    Light-absorbing atmospheric aerosols such as carbonaceous particles influence the climate through absorbing sunlight. The mixing states of these aerosol particles affect their optical properties. This study examines the changes in the mixing states and abundance of strongly light absorbing carbonaceous particles by using transmission electron microscopy (TEM) and single-particle soot photometer (SP2), as well as of iron oxide particles, in Tokyo, Japan. TEM and SP2 use fundamentally different detection techniques for the same light-absorbing particles. TEM allows characterization of the morphological, chemical, and structural features of individual particles, whereas SP2 optically measures the number, size, and mixing states of black carbon (BC). A comparison of the results obtained using these two techniques indicates that the peaks of high soot (nanosphere soot (ns-soot)) concentration periods agree with those of the BC concentrations determined by SP2 and that the high Fe-bearing particle fraction periods measured by TEM agree with that of high number concentrations of iron oxide particles measured using SP2 during the first half of the observation campaign. The results also show that the changes in the ns-soot/BC mixing states primarily correlate with the air mass sources, wind speed, precipitation, and photochemical processes. Nano-sized, aggregated, iron oxide particles mixed with other particles were commonly observed by using TEM during the high iron oxide particle periods. We conclude that although further quantitative comparison between TEM and SP2 data will be needed, the morphologically and optically defined ns-soot and BC, respectively, are essentially the same substance and that their mixing states are generally consistent across the techniques.

  1. Selective photobleaching of chlorophylls and carotenoids in photosystem I particles under high-light treatment.

    PubMed

    Andreeva, Atanaska; Abarova, Silvia; Stoitchkova, Katerina; Picorel, Rafael; Velitchkova, Maya

    2007-01-01

    Photosystem I particles (PSI-200) isolated from spinach leaves were studied by means of absorbance, 77K fluorescence and resonance Raman (RR) spectroscopy. The aim was to obtain better insight into the changes of the pigment spectral properties in those particles during prolonged exposure to high-light intensities and to reveal the involvement of these pigments in the photoprotection of the PSI. During prolonged exposure to high-light intensities of spinach PSI particles, a loss of a significant amount of photosynthetic pigments was observed. It was shown that various pigments exhibited different susceptibility to photodamage. In addition to bleaching of chlorophyll a (Chl a), bleaching of carotenoids was also clearly observed. RR technique allowed us to recognize the type and conformation of photobleached carotenoid molecules. Raman data revealed a nearly full photobleaching of the long-wavelength lutein molecules. The observed similar bleaching rate of the lutein molecules and the most-red shifted long-wavelength Chl a, located in the antenna membrane protein Lhca4, suggested that these molecules are located closely. Our results showed that the photobleached antenna pigments and especially luteins and the most long-wavelength absorbing chlorophylls are involved in photoprotection of PSI core complex.

  2. The LS-CODAG experiment for light scattering measurements by dust particles and their aggregates

    NASA Astrophysics Data System (ADS)

    Levasseur-Regourd, A. C.; Cabane, M.; Chassefière, E.; Haudebourg, V.; Worms, J. C.

    1999-01-01

    Light scattering measurements are needed to provide links between the currently available observations of scattering by dust in the solar system, and the still unknown properties of the clouds of dust particles and aggregates. The fragility, the fluffiness, and the size of the aggregates make it almos impossible to obtain realistic measurements through computational models or classical laboratory measurements. In order to measure the scattering by dust particles and their aggregates, we have conceived the Light Scattering (LS) experiment for the COsmic Dust AGgregation (CODAG) module. This small and compact instrument has been developed to operate under microgravity conditions, jointly with the CODAG Sounding Rocket experiment (Blum et al., 1998), during ESA rocket flights. The purpose of the experiment is to determine accurately the intensity and the polarization phase functions of the particles that are dispersed in a low pressure chamber, and to document the temporal evolution of their scattering properties, while an aggregation process representative of the solar system formation is starting and spreading out. The instrumental principle relies on simultaneous measurements, performed on a large number of phase angles, from back to forward scattering, of the two polarized components of the scattered intensity.

  3. Light propagation in moderately dense particle systems: a reexamination of the Kubelka-Munk theory.

    PubMed

    Latimer, P; Noh, S J

    1987-02-01

    A numerical method (NM) is developed to characterize radiative transfer in a moderately dense particle population, i.e., a suspension of concentration of <1-10% by volume. It assumes that the particles scatter in accord with the Mie equations, that the propagation of light over short distances is in accord with the exponential transmission law, and that the light flows in many (thirty-six) directions. For representative systems, predictions of the Kubelka-Munk theory (KMT) are compared with those of the NM; partial agreement is found. While this theory can be a useful tool, radiative transport in representative samples is found not to obey strictly either the assumptions for writing the basic differential equations of the KMT or those for solving them. The movement of diffuse light through an attenuating system is found to often collimate it, not to make it more diffuse as expected. This effect causes errors in absolute KMT predictions. New transport equations, like Schuster's, with four parameters instead of two are written and solved to obtain some new KMT equations. Their predictions are compared with those of the NM.

  4. An introduction to light extinction spectrometry as a diagnostic for dust particle characterisation in dusty plasmas

    NASA Astrophysics Data System (ADS)

    Barbosa, S.; Onofri, F. R. A.; Couëdel, L.; Wozniak, M.; Montet, C.; Pelcé, C.; Arnas, C.; Boufendi, L.; Kovacevic, E.; Berndt, J.; Grisolia, C.

    2016-08-01

    In this article, a detailed introduction of the light extinction spectrometry (LES) diagnostics is given. LES allows the direct in situ measurement of the particle size distribution and absolute concentration of dust clouds levitating in plasmas. Using a relatively simple and compact experimental set-up, the dust cloud parameters can be recovered with a good accuracy making minimum assumptions on their physical properties. Special emphases are given to the inversion procedure of light extinction spectra and all the required particle shape, refractive index and light extinction models. The parameter range and the limitations of LES are discussed. Two measurements in low-pressure gas discharges are presented: (i) in a direct-current (DC) glow discharge in which nanoparticles are growing from the sputtering of a tungsten cathode and (ii) in an argon-silane radio-frequency discharge. They demonstrate the capabilities of the LES technique to characterise, in situ and in real-time, the growth dynamics of nanoparticles in the size range 5-100 nm and volume concentrations in the range from a few ppb to a few ppm.

  5. Investigation of unburned carbon particles in fly ash by means of laser light scattering

    NASA Astrophysics Data System (ADS)

    Iannone, R. Q.; Morlacchi, R.; Calabria, R.; Massoli, P.

    2011-02-01

    A new optical method to determine the percentage of unburned carbon particles in fly ash from combustion of pulverized coal has been developed. The technique exploits the different properties of particles of ash and coal in the elastic scattering of polarized light. The polarization measurements were performed using a linearly polarized laser source and a receiving system able to simultaneously detect the scattered radiation polarized in parallel and orthogonal planes, under the scattering angle of 60°. The parallel and perpendicular components of the scattered light intensities are measured in order to determine the polarization ratio. The operation of the system was tested under various conditions using monodisperse glass spheres. The performance of the novel device was assessed in several sets of measurements with samples of fly ash produced from coal fired power plants. A correlation between the relative content of coal and ashes and the polarization ratio of scattered light was demonstrated. The resulting polarization ratio showed values ranging from 1.25 to 0.94 for a carbon content of 1.17 wt% and 16.3 wt%, respectively. The uncertainty on the measured percentage of unburned carbon was about 1%. The proposed device represents an attractive tool for monitoring real-time burnout and combustion efficiency.

  6. Ultra-fast RAFT polymerisation of poly(ethylene glycol) acrylate in aqueous media under mild visible light radiation at 25 degrees C.

    PubMed

    Shi, Yi; Gao, Huan; Lu, Lican; Cai, Yuanli

    2009-03-21

    Mild visible light was sufficient to activate RAFT polymerisation of poly(ethylene glycol) methyl ether acrylate in 50 wt% water at 25 degrees C, leading to an ultra-fast and well-controlled living RAFT polymerisation with more than 80% monomer conversion; this is the first example of an ultra-fast RAFT polymerisation under such environmentally friendly mild aqueous conditions.

  7. Fast-Particle-Driven Alfvénic Modes in a Reversed Field Pinch

    NASA Astrophysics Data System (ADS)

    Koliner, J. J.; Forest, C. B.; Sarff, J. S.; Anderson, J. K.; Liu, D.; Nornberg, M. D.; Waksman, J.; Lin, L.; Brower, D. L.; Ding, W. X.; Spong, D. A.

    2012-09-01

    Alfvénic modes are observed due to neutral beam injection for the first time in a reversed field pinch plasma. Modeling of the beam deposition and slowing down shows that the velocity and radial localization are high. This allows instability drive from inverse Landau damping of a bump-on-tail in the parallel distribution function or from free energy in the fast ion density gradient. Mode switching from a lower frequency toroidal mode number n=5 mode that scales with beam injection velocity to a higher frequency n=4 mode with Alfvénic scaling is observed.

  8. Webinar Presentation: Black Carbon and Other Light-absorbing Particles in Snow in Central North America and North China

    EPA Pesticide Factsheets

    This presentation, Black Carbon and Other Light-absorbing Particles in Snow in Central North America and North China, was given at the STAR Black Carbon 2016 Webinar Series: Accounting for Impact, Emissions, and Uncertainty held on Nov. 7, 2016.

  9. Fast high-contrast imaging of animal development with scanned light sheet-based structured illumination microscopy

    PubMed Central

    Keller, Philipp J.; Schmidt, Annette D.; Santella, Anthony; Khairy, Khaled; Bao, Zhirong; Wittbrodt, Joachim; Stelzer, Ernst H.K.

    2015-01-01

    Recording light microscopic images of large, non-transparent specimens, such as developing multi-cellular organisms, is complicated by decreased contrast due to light scattering. Early zebrafish development can be captured by standard light sheet microscopy; however, new imaging strategies are required to obtain high-quality data of late development or of less transparent organisms. We combined Digital Scanned Laser Light Sheet Fluorescence Microscopy (DSLM) with incoherent structured illumination microscopy and created structured illumination patterns with continuously adjustable frequencies (DSLM-SI). Our method discriminates the specimen-related scattered background from signal fluorescence, thereby removing out-of-focus light and optimizing the contrast of in-focus structures. DSLM-SI provides rapid control of the illumination pattern, exceptional imaging quality and high imaging speeds. We performed long-term imaging of zebrafish development for 58 hours and fast multiple-view imaging of early Drosophila development. We reconstructed cell positions over time from the Drosophila DSLM-SI data and created a Fly Digital Embryo. PMID:20601950

  10. Particle and power balance in a helicon operating with light gases [experiment

    NASA Astrophysics Data System (ADS)

    Bengtson, Roger D.; Gibson, J. N.; Jacobson, V. T.; Chang-Diaz, F. R.; Squire, J. P.; McCaskill, G. E.; McCoy, J. E.; Petro, A. J.; Winter, D. S.; Jamison, H. M.; Bering, E. A.; Glover, T. W.

    2001-10-01

    Measurements of input power, particle flow, radiation, electron density profiles, plasma flow, and electron temperature profiles over a range of input power, magnetic field, and neutral flow were used to do a power and particle balance during operation with light gases H, D, and He in the VASIMR experiment at the Advanced Space Propulsion Laboratory. In addition, an axial pressure scan provided important information about the importance of charge exchange collisions. The pressure in the helicon increases about a factor of 4 when the helicon is turned on. We make the assumption that electron temperature is constant along the axis of the helicon. Several important observations can be made: 1) The electron density increases with power, 2) Plasma flow is important in determining plasma conditions, 3) Radiation losses are large, and 4) charge exchange processes are important.

  11. Revisiting alpha decay-based near-light-speed particle propulsion.

    PubMed

    Zhang, Wenwu; Liu, Zhen; Yang, Yang; Du, Shiyu

    2016-08-01

    Interplanet and interstellar travels require long-term propulsion of spacecrafts, whereas the conventional schemes of propulsion are limited by the velocity of the ejected mass. In this study, alpha particles released by nuclear decay are considered as a potential solution for long-time acceleration. The principle of near-light-speed particle propulsion (NcPP) was elucidated and the stopping and range of ions in matter (SRIM) was used to predict theoretical accelerations. The results show that NcPP by means of alpha decay is feasible for long-term spacecraft propulsion and posture adjustment in space. A practical NcPP sail can achieve a speed >150km/s and reach the brink of the solar system faster than a mass equivalent solar sail. Finally, to significantly improve the NcPP sail, the hypothesis of stimulated acceleration of nuclear decay (SAND) was proposed, which may shorten the travel time to Mars to within 20 days.

  12. Modeling of laser light scattering in a medium with spherical particles

    NASA Astrophysics Data System (ADS)

    Larionova, Nadezhda L.; Maksimova, Irina L.

    2001-05-01

    Laser light radiation scattered by the system of spheres with various parameters was theoretically investigated by using of the Mie theory of electromagnetic scattering by a single sphere. The calculations were performed for systems of particles whose coordinates were specifically realized in random fashion according to the specified probabilities defined by the approximation of hard spheres. The parameters of model are the same as in the eye lense biotissue and were carried out by using of medical data about internal structure of men lens and some animals. In general the studied model presents the system of homogeneous spherical particles which are randomly distributed in the layer of thickness. We study the optical properties such as scattering effective cross-section and function of correlation in different models.

  13. SU-E-T-334: Track Structure Simulations of Charged Particles at Low and Intermediate Energies: Cross Sections Needs for Light and Heavy Ions

    SciTech Connect

    Dingfelder, M

    2014-06-01

    Purpose/Methods: Monte Carlo (MC) track structure simulations follow the primary as well as all produced secondary particles in an event-by-event manner, from starting or ejection energy down to total stopping. They provide useful information on physics and chemistry of the biological response to radiation. They depend on reliable interaction cross sections and transport models of the considered radiation quality with biologically relevant materials. Most transport models focus on sufficiently fast and bare (i.e., fully ionized) ions and cross sections calculated within the (relativistic) first Born or Bethe approximations. These theories consider the projectile as a point particle and rely on proton cross sections and simple charge-scaling methods; they neglect the atomic nature of the ion and break down at low and intermediate ion energies. Heavier ions are used in particle therapy and slow to intermediate and low energies in the biologically interesting Bragg peak. Lighter and slower fragment ions, including alpha particles, protons, and neutrons are also produced in nuclear and break up reactions of charged particles. Secondary neutrons also produce recoil protons and ions, mainly in the intermediate energy range. Results/Conclusion: This work reviews existing models for track structure simulations and cross section calculations for light and heavy ions focusing on the low and intermediate energy range. It also presents new and updated aspects on cross section calculations and simulation techniques for ions and discusses the need for new models, calculations, and experimental data.

  14. Slow and Fast Light in Room Temperature Solids: Fundamentals and Applications

    NASA Astrophysics Data System (ADS)

    Boyd, Robert W.

    2004-03-01

    In recent years there has been great interest in techniques that can lead to a modification of the propagation velocity of light pulses through optical materials. Interest stems both from the intrinsic interest in the ability to control the velocity of light over large ranges and from the potential for applications such as controllable delay lines, optical data storage devices, optical memories, and devices for quantum information. Matthew Bigelow, Nick Lepeshkin, and I have recently developed a new method for achieving ultra-slow light propagation in room temperature solids. Our method makes use of an effect known as coherent population oscillations. In particular, we apply pump and probe fields to a ruby crystal, and the population of ground-state chromium ions is induced to oscillate coherently at the resulting beat frequency. These oscillations lead to a decreased absorption of the probe beam, and consequently (by the Kramers-Kronig relations) to a steep variation of the refractive index. In our laboratory studies of this effect, we observed reduced light velocities with light speeds as low as 57 m/s. We have also studied light propagation in the reverse saturable absorber alexandrite. In this case, the sign of the effect is inverted, leading to superluminal (but causal) light propagation.

  15. Smectic A Filled Birefringent Elements and Fast Switching Twisted Dual Frequency Nematic Cells Used for Digital Light Deflection

    NASA Technical Reports Server (NTRS)

    Pishnyak, Oleg; Golovin, Andrii; Kreminskia, Liubov; Pouch, John J.; Miranda, Felix A.; Winker, Bruce K.; Lavrentovich, Oleg D.

    2006-01-01

    We describe the application of smectic A (SmA) liquid crystals for beam deflection. SmA materials can be used in digital beam deflectors (DBDs) as fillers for passive birefringent prisms. SmA prisms have high birefringence and can be constructed in a variety of shapes, including single prisms and prismatic blazed gratings of different angles and profiles. We address the challenges of uniform alignment of SmA, such as elimination of focal conic domains. Fast rotation of the incident light polarization in DBDs is achieved by an electrically switched 90 twisted nematic (TN) cell.

  16. Polarimetric Studies of Solar Light Scattered by Interplanetary Dust Particles and the Eye-Sat Project

    NASA Astrophysics Data System (ADS)

    Levasseur-Regourd, A. C.; Lasue, J.

    2014-12-01

    Studying intensity and linear polarization of the solar light scattered by interplanetary dust is of interest for various reasons. This so-called zodiacal light constitutes a faint polarized glow that constitutes a changing foreground for observations of faint extended astronomical sources. Besides, analysis of its polarization provides information on properties of the dust particles, such as spatial density, morphology and complex refractive index. Previous observations, mostly from the Earth and with a resolution in the 10° range, have been used to infer that the local polarization at 90° phase angle increases with increasing solar distance. Numerical simulations suggest that, in the inner solar system, interplanetary dust particles consist of a mixture of absorbing and less absorbing materials, and that radial changes originate in a decrease of organic materials with decreasing solar distance under alteration or evaporation processes. To improve the quality of data on zodiacal light polarimetry, Eye-Sat nanosat is being developed in the context of the JANUS CNES cubesats program for students. The project is now in phase C-D, for a piggy-back launch in 2016. Eye-Sat triple cubesat is anticipated to demonstrate the feasibility of a series of new on-board technologies. Moreover, during its one-year mission, zodiacal light intensity and polarization are to be measured, for the first time with a spatial resolution of about 1° over a wide portion of the sky and in four different wavelengths (visible to near-IR), leading to a better assessment of interplanetary dust properties. Finally, a significant fraction of the interplanetary dust is estimated to come from comets, the most pristine objects to be found in the inner solar system. While similarities have indeed been noticed between polarimetric properties of interplanetary and cometary dust particles, the latter being currently extensively documented by the Rosetta mission to comet 67P

  17. Optical knobs from slow- to fast-light with gain in low-dimensional semiconductor heterostructures

    NASA Astrophysics Data System (ADS)

    Han, Dingan; Zeng, Yaguang; Bai, Yanfeng

    2011-09-01

    The light pulse propagation through semiconductor quantum-well heterostructures under realistic experimental conditions is studied analytically with the Schrödinger equations. It is shown that slow light and superluminal propagation with gain can be observed by varying the relative phase and the strength of the applied fields. Such investigation may open up the possibility to control the light propagation and may lead to potential applications such as high-fidelity optical delay lines, optical buffers and optical communication in quantum wells solid materials.

  18. Large dynamic light-matter entanglement from driving neither too fast nor too slow

    NASA Astrophysics Data System (ADS)

    Acevedo, O. L.; Quiroga, L.; Rodríguez, F. J.; Johnson, N. F.

    2015-09-01

    A significant problem facing next-generation quantum technologies is how to generate and manipulate macroscopic entanglement in light and matter systems. Here we report a regime of dynamical light-matter behavior in which a giant, system-wide entanglement is generated by varying the light-matter coupling at intermediate velocities. This enhancement is far larger, broader ranged, and more experimentally accessible than that occurring near the quantum phase transition of the same model under adiabatic conditions. By appropriate choices of the coupling within this intermediate regime, the enhanced entanglement can be made to spread system-wide or to reside in each subsystem separately.

  19. Volcanic Particle Aggregation: A Fast Algorithm for the Smoluchowski Coagulation Equation

    NASA Astrophysics Data System (ADS)

    Rossi, E.; Bagheri, G.; Bonadonna, C.

    2014-12-01

    Particle aggregation is a key process that significantly affects dispersal and sedimentation of volcanic ash, with obvious implications for the associated hazards. Most theoretical studies of particle aggregation have been based on the Smoluchowski Coagulation Equation (SCE), which describes the expected time evolution of the total grain-size distribution under the hypothesis that particles can collide and stick together following specific mathematical relations (kernels). Nonetheless, the practical application of the SCE to real erupting scenarios is made extremely difficult - if not even impossible - by the large number of Ordinary Differential Equations (ODE) which have to be solved to study the typical sizes of volcanic ash (1 micron to 1 mm). We propose an algorithm to approximate the discrete solutions of the SCE, which can describe the time evolution of the total grain-size distribution of the erupted material with an increased computational efficiency. This algorithm has been applied to observed volcanic eruptions (i.e., Eyjafjallajokull 2010, Sakurajima 2013 and Mt. Saint Helens 1980) to see if the commonly used kernels can explain field data and to study how aggregation processes can modify the tephra dispersal on the ground. Different scenarios of sticking efficiencies and aggregate porosity have been used to test the sensitiveness of the SCE to these parameters. Constraints on these parameters come from field observations and laboratory experiments.

  20. The EB Factory Project. I. A Fast, Neural-net-based, General Purpose Light Curve Classifier Optimized for Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Paegert, Martin; Stassun, Keivan G.; Burger, Dan M.

    2014-08-01

    We describe a new neural-net-based light curve classifier and provide it with documentation as a ready-to-use tool for the community. While optimized for identification and classification of eclipsing binary stars, the classifier is general purpose, and has been developed for speed in the context of upcoming massive surveys such as the Large Synoptic Survey Telescope. A challenge for classifiers in the context of neural-net training and massive data sets is to minimize the number of parameters required to describe each light curve. We show that a simple and fast geometric representation that encodes the overall light curve shape, together with a chi-square parameter to capture higher-order morphology information results in efficient yet robust light curve classification, especially for eclipsing binaries. Testing the classifier on the ASAS light curve database, we achieve a retrieval rate of 98% and a false-positive rate of 2% for eclipsing binaries. We achieve similarly high retrieval rates for most other periodic variable-star classes, including RR Lyrae, Mira, and delta Scuti. However, the classifier currently has difficulty discriminating between different sub-classes of eclipsing binaries, and suffers a relatively low (~60%) retrieval rate for multi-mode delta Cepheid stars. We find that it is imperative to train the classifier's neural network with exemplars that include the full range of light curve quality to which the classifier will be expected to perform; the classifier performs well on noisy light curves only when trained with noisy exemplars. The classifier source code, ancillary programs, a trained neural net, and a guide for use, are provided.

  1. The EB factory project. I. A fast, neural-net-based, general purpose light curve classifier optimized for eclipsing binaries

    SciTech Connect

    Paegert, Martin; Stassun, Keivan G.; Burger, Dan M.

    2014-08-01

    We describe a new neural-net-based light curve classifier and provide it with documentation as a ready-to-use tool for the community. While optimized for identification and classification of eclipsing binary stars, the classifier is general purpose, and has been developed for speed in the context of upcoming massive surveys such as the Large Synoptic Survey Telescope. A challenge for classifiers in the context of neural-net training and massive data sets is to minimize the number of parameters required to describe each light curve. We show that a simple and fast geometric representation that encodes the overall light curve shape, together with a chi-square parameter to capture higher-order morphology information results in efficient yet robust light curve classification, especially for eclipsing binaries. Testing the classifier on the ASAS light curve database, we achieve a retrieval rate of 98% and a false-positive rate of 2% for eclipsing binaries. We achieve similarly high retrieval rates for most other periodic variable-star classes, including RR Lyrae, Mira, and delta Scuti. However, the classifier currently has difficulty discriminating between different sub-classes of eclipsing binaries, and suffers a relatively low (∼60%) retrieval rate for multi-mode delta Cepheid stars. We find that it is imperative to train the classifier's neural network with exemplars that include the full range of light curve quality to which the classifier will be expected to perform; the classifier performs well on noisy light curves only when trained with noisy exemplars. The classifier source code, ancillary programs, a trained neural net, and a guide for use, are provided.

  2. Particle-In-Cell Simulations of Particle Energization from Low Mach Number Fast Mode Shocks Using the Moving Wall Boundary Condition

    NASA Astrophysics Data System (ADS)

    Workman, Jared C.; Park, J.; Blackman, E.; Ren, C.; Siller, R.

    2012-05-01

    Astrophysical shocks are often studied in the high Mach number limit but weakly compressive fast shocks can occur in magnetic reconnection outflows and are considered to be a site of particle energization in solar flares. Here we study the microphysics of such perpendicular, low Mach number collisionless shocks using two-dimensional particle-in-cell (PIC) simulations with a reduced ion/electron mass ratio and employ a moving wall boundary method for initial generation the shock. This moving wall method allows for more control of the shock speed, smaller simulation box sizes, and longer simulation times than the commonly used fixed wall, reflection method of shock formation. Our results, which are independent of the shock formation method, reveal the prevalence shock drift acceleration (SDA) of both electron and ions in a purely perpendicular shock with Alfven Mach number MA = 6.8 and ratio of thermal to magnetic pressure β = 8. We determine the respective minimum energies required for electrons and ions to incur SDA. We derive an theoretical electron distribution via SDA that compares favorably to the simulation results. We also show that a modified two-stream instability due to the incoming and reflecting ions in the shock transition region acts as the mechanism to generate collisionless plasma turbulence that sustains the shock.

  3. Saharan Dust: Particle Size Distributions and Light Absorption From Measurements During PRIDE and AEROCE

    NASA Astrophysics Data System (ADS)

    Savoie, D. L.; Maring, H. B.

    2001-12-01

    During July 2000, the Office of Naval Reseach and NASA co-sponsored the Puerto Rican Dust Experiment (PRIDE) to assess the physical and optical properties of Saharan dust over the western Atlantic. Numerous aerosol characterization instruments were deployed on Isla Cabras (18.21 N, 65.60 W) in the Roosevelt Roads Naval Station at the eastern end of Puerto Rico. As part of AEROCE (Atmosphere/Ocean Chemistry Experiment), we had previously made similar measurements over the eastern Atlantic at Izana, Tenerife, Canary Islands (28.30 N, 16.48 W). Instrumentation included a TSI APS33 aerodynamic particle sizer, a Ruprecht and Patashnick Tapered Element Oscillating Microbalance (TEOM), and a Radiance Research particle soot absorption photometer (PSAP). At the same locations, daily, high-volume, bulk aerosol samples were collected and analyzed for mineral dust, sea-salt, nitrate, sulfate, and ammonium and for aerosol light absorption (every 10 nm from 300 to 1100 nm via total diffuse reflectance measurements). With the concurrent aerosol chemistry, variations in the in-situ aerosol physical and optical properties can be linked to variations in the concentrations of particles from specific sources. High concentrations of Saharan dust were present at Izana during the last half of July 1995. The APS data at Izana are almost exclusively from dust as there is no sea-salt at this free troposphere site. We used the measured particle size distributions for high dust periods from this campaign to establish an average dust size distribution. Because of the nearly zero correlation between sea-salt and dust, the APS size distributions during PRIDE could be reasonably well resolved between these two components. In contrast to the situation at Izana, there were virtually no particles larger than 10 um geometric diameter at Puerto Rico. Progressively lesser fractions of particles were lost between the eastern and western Atlantic as the particle size decreased. With the natural

  4. Electrically tunable fast light at THz bandwidth using cascaded semiconductor optical amplifiers.

    PubMed

    Pesala, Bala; Sedgwick, Forrest; Uskov, Alexander V; Chang-Hasnain, Connie

    2007-11-26

    Ultra fast non-linear processes are used to achieve an advance of 2 ps for a 600 fs pulse propagating through two SOAs in series. This corresponding 3.3-pulse advance is tuned continuously by changing the current applied to the devices. We propose an experimental scheme that uses a single SOA in a loop to emulate the propagation of pulse through multiple cascaded SOAs.

  5. High rate particle tracking and ultra-fast timing with a thin hybrid silicon pixel detector

    NASA Astrophysics Data System (ADS)

    Fiorini, M.; Aglieri Rinella, G.; Carassiti, V.; Ceccucci, A.; Cortina Gil, E.; Cotta Ramusino, A.; Dellacasa, G.; Garbolino, S.; Jarron, P.; Kaplon, J.; Kluge, A.; Marchetto, F.; Mapelli, A.; Martin, E.; Mazza, G.; Morel, M.; Noy, M.; Nuessle, G.; Perktold, L.; Petagna, P.; Petrucci, F.; Poltorak, K.; Riedler, P.; Rivetti, A.; Statera, M.; Velghe, B.

    2013-08-01

    The Gigatracker (GTK) is a hybrid silicon pixel detector designed for the NA62 experiment at CERN. The beam spectrometer, made of three GTK stations, has to sustain high and non-uniform particle rate (∼ 1 GHz in total) and measure momentum and angles of each beam track with a combined time resolution of 150 ps. In order to reduce multiple scattering and hadronic interactions of beam particles, the material budget of a single GTK station has been fixed to 0.5% X0. The expected fluence for 100 days of running is 2 ×1014 1 MeV neq /cm2, comparable to the one foreseen in the inner trackers of LHC detectors during 10 years of operation. To comply with these requirements, an efficient and very low-mass (< 0.15 %X0) cooling system is being constructed, using a novel microchannel cooling silicon plate. Two complementary read-out architectures have been produced as small-scale prototypes: one is based on a Time-over-Threshold circuit followed by a TDC shared by a group of pixels, while the other makes use of a constant-fraction discriminator followed by an on-pixel TDC. The read-out ASICs are produced in 130 nm IBM CMOS technology and will be thinned down to 100 μm or less. An overview of the Gigatracker detector system will be presented. Experimental results from laboratory and beam tests of prototype bump-bonded assemblies will be described as well. These results show a time resolution of about 170 ps for single hits from minimum ionizing particles, using 200 μm thick silicon sensors.

  6. FAST WAVELET-BASED SINGLE-PARTICLE RECONSTRUCTION IN CRYO-EM.

    PubMed

    Vonesch, Cédric; Wang, Lanhui; Shkolnisky, Yoel; Singer, Amit

    2011-06-09

    This paper presents a novel algorithm for the 3D tomographic inversion problem that arises in single-particle electron cryo-microscopy (Cryo-EM). It is based on two key components: 1) a variational formulation that promotes sparsity in the wavelet domain and 2) the Toeplitz structure of the combined projection/back-projection operator. The first idea has proven to be very effective for the recovery of piecewise-smooth signals, which is confirmed by our numerical experiments. The second idea allows for a computationally efficient implementation of the reconstruction procedure, using only one circulant convolution per iteration.

  7. Deflections of Fast Coronal Mass Ejections and the Properties of Associated Solar Energetic Particle Events (POSTPRINT)

    DTIC Science & Technology

    2012-09-20

    CMEs) – Sun: flares – Sun: particle emission Online-only material : color figures 1. INTRODUCTION 1.1. SEP Events and Coronal Holes Despite their...Gui et al. 2011; Liu et al. 2010; Byrne et al. 2010; Lugaz et al. 2011) show that these CME deflections must happen within several R, where the shock...et al. 2011), STEREO/SECCHI (Kilpua et al. 2009; Byrne et al. 2010; Shen et al. 2011; Zuccarello et al. 2012), and SMEI (Kahler & Webb 2010

  8. A fast, self-recovering superconducting strip particle detector made with granular tungsten

    NASA Astrophysics Data System (ADS)

    Gabutti, A.; Gray, K. E.; Pugh, G. M.; Tiberio, R.

    1992-02-01

    The ability of detectors to automatically recover (self-recovery) in a short period of time after sensing a particle is a very valuable advantage for their use as microvertex detectors at high energy particle colliders. Using a superconducting strip detector made of granular tungsten, we have observed such behavior with pulse amplitudes of few 100 μV and recovery times fo 10-50 ns. A 1.8 μm wide thin film was used to detect the superconducting-to-normal transitions induced by the absorption of 55Fe, 6 keV X-rays. For high bias currents the detector did not self-recover and a constant efficiency estimated to ˜65% was found, but with good indications that such a rate would persist in the self-recovery mode at lower bias currents. The threshold between self-recovering and propagating hotspots is discussed within the thermal propagation model, developed previously for normal regions which bridge the width of the strip. These results also confirm the potential applications of superconducting strips for high resolution X-rays detectors.

  9. ITER Plasma at Ion Cyclotron Frequency Domain: The Fusion Alpha Particles Diagnostics Based on the Stimulated Raman Scattering of Fast Magnetosonic Wave off High Harmonic Ion Bernstein Modes

    NASA Astrophysics Data System (ADS)

    Stefan, V. Alexander

    2014-10-01

    A novel method for alpha particle diagnostics is proposed. The theory of stimulated Raman scattering, SRS, of the fast wave and ion Bernstein mode, IBM, turbulence in multi-ion species plasmas, (Stefan University Press, La Jolla, CA, 2008). is utilized for the diagnostics of fast ions, (4)He (+2), in ITER plasmas. Nonlinear Landau damping of the IBM on fast ions near the plasma edge leads to the space-time changes in the turbulence level, (inverse alpha particle channeling). The space-time monitoring of the IBM turbulence via the SRS techniques may prove efficient for the real time study of the fast ion velocity distribution function, spatial distribution, and transport. Supported by Nikola Tesla Labs., La Jolla, CA 92037.

  10. Modeling Filamentous Cyanobacteria Reveals the Advantages of Long and Fast Trichomes for Optimizing Light Exposure

    PubMed Central

    Tamulonis, Carlos; Postma, Marten; Kaandorp, Jaap

    2011-01-01

    Cyanobacteria form a very large and diverse phylum of prokaryotes that perform oxygenic photosynthesis. Many species of cyanobacteria live colonially in long trichomes of hundreds to thousands of cells. Of the filamentous species, many are also motile, gliding along their long axis, and display photomovement, by which a trichome modulates its gliding according to the incident light. The latter has been found to play an important role in guiding the trichomes to optimal lighting conditions, which can either inhibit the cells if the incident light is too weak, or damage the cells if too strong. We have developed a computational model for gliding filamentous photophobic cyanobacteria that allows us to perform simulations on the scale of a Petri dish using over 105 individual trichomes. Using the model, we quantify the effectiveness of one commonly observed photomovement strategy—photophobic responses—in distributing large populations of trichomes optimally over a light field. The model predicts that the typical observed length and gliding speeds of filamentous cyanobacteria are optimal for the photophobic strategy. Therefore, our results suggest that not just photomovement but also the trichome shape itself improves the ability of the cyanobacteria to optimize their light exposure. PMID:21789215

  11. Weathering of a carbon nanotube/epoxy nanocomposite under UV light and in water bath: impact on abraded particles

    NASA Astrophysics Data System (ADS)

    Schlagenhauf, Lukas; Kianfar, Bahareh; Buerki-Thurnherr, Tina; Kuo, Yu-Ying; Wichser, Adrian; Nüesch, Frank; Wick, Peter; Wang, Jing

    2015-11-01

    Weathering processes can influence the surface properties of composites with incorporated nanoparticles. These changes may affect the release behavior of nanoparticles when an abrasion process is applied. Therefore, the influence of two different weathering processes, immersion in water and exposure to UV light, on the properties of abraded particles from a carbon nanotube (CNT)/epoxy nanocomposite was investigated. The investigation included the measurement of the weathering impact on the surface chemistry of the exposed samples, the particle size of abraded particles, the quantity of exposed CNTs in the respirable part of the abraded particles, and the toxicity of abraded particles, measured by in vitro toxicity tests using the THP-1 monocyte-derived macrophages. The results showed that weathering by immersion in water had no influence on the properties of abraded particles. The exposure to UV light caused a degradation of the epoxy on the surface, followed by delamination of an approx. 2.5 μm thick layer. An increased quantity of exposed CNTs in abraded particles was not found; on the contrary, longer UV exposure times decreased the released fraction of CNTs from 0.6% to 0.4%. The toxicity tests revealed that abraded particles from the nanocomposites did not induce additional acute cytotoxic effects compared to particles from the neat epoxy.Weathering processes can influence the surface properties of composites with incorporated nanoparticles. These changes may affect the release behavior of nanoparticles when an abrasion process is applied. Therefore, the influence of two different weathering processes, immersion in water and exposure to UV light, on the properties of abraded particles from a carbon nanotube (CNT)/epoxy nanocomposite was investigated. The investigation included the measurement of the weathering impact on the surface chemistry of the exposed samples, the particle size of abraded particles, the quantity of exposed CNTs in the respirable part of

  12. THE CRAB NEBULA SUPER-FLARE IN 2011 APRIL: EXTREMELY FAST PARTICLE ACCELERATION AND GAMMA-RAY EMISSION

    SciTech Connect

    Striani, E.; Tavani, M.; Cardillo, M; Piano, G.; Donnarumma, I.; Vittorini, V.; Trois, A.; Costa, E.; Argan, A.; De Paris, G.; Bulgarelli, A.; Pittori, C.; Verrecchia, F.; Weisskopf, M.; Tennant, A.; Barbiellini, G.; Caraveo, P.; Chen, A. W.

    2011-11-01

    We report on the extremely intense and fast gamma-ray flare above 100 MeV detected by AGILE from the Crab Nebula in mid-April 2011. This event is the fourth of a sequence of reported major gamma-ray flares produced by the Crab Nebula in the period 2007/mid-2011. These events are attributed to strong radiative and plasma instabilities in the inner Crab Nebula, and their properties are crucial for theoretical studies of fast and efficient particle acceleration up to 10{sup 15} eV. Here we study the very rapid flux and spectral evolution of the event that on 2011 April 16 reached the record-high peak flux of F = (26 {+-} 5) x 10{sup -6} photons cm{sup -2} s{sup -1} with a rise-time timescale that we determine to be in the range 6-10 hr. The peak flaring gamma-ray spectrum reaches a distinct maximum near 500 MeV with no substantial emission above 1 GeV. The very rapid rise time and overall evolution of the Crab Nebula flare strongly constrain the acceleration mechanisms and challenge MHD models. We briefly discuss the theoretical implications of our observations.

  13. Feasibility of the preparation of silica monoliths for gas chromatography: fast separation of light hydrocarbons.

    PubMed

    Azzouz, Imadeddine; Essoussi, Anouar; Fleury, Joachim; Haudebourg, Raphael; Thiebaut, Didier; Vial, Jerome

    2015-02-27

    The preparation conditions of silica monoliths for gas chromatography were investigated. Silica-based monolithic capillary columns based on sol-gel process were tested in the course of high-speed gas chromatographic separations of light hydrocarbons mixture (C1-C4). The impact of modifying the amount of porogen and/or catalyst on the monolith properties were studied. At the best precursor/catalyst/porogen ratio evaluated, a column efficiency of about 6500 theoretical plates per meter was reached with a very good resolution (4.3) for very light compounds (C1-C2). The test mixture was baseline separated on a 70cm column. To our knowledge for the first time a silica-based monolithic capillary column was able to separate light hydrocarbons from methane to n-butane at room temperature with a back pressure in the range of gas chromatography facilities (under 4.1bar).

  14. Use of fast scopes to enable Thomson scattering measurement in presence of fluctuating plasma light.

    SciTech Connect

    McLean, H; Moller, J; Hill, D

    2004-04-19

    The addition of inexpensive high-speed oscilloscopes has enabled higher Te Thomson scattering measurements on the SSPX spheromak. Along with signal correlation techniques, the scopes allow new analyses based on the shape of the scattered laser pulse to discriminate against fluctuating background plasma light that often make gated-integrator measurements unreliable. A 1.4 J Nd:YAG laser at 1064 nm is the scattering source. Spatial locations are coupled by viewing optics and fibers to 4-wavelength-channel filter polychrometers. Ratios between the channels determine Te while summations of the channels determine density. Typically, the channel that provides scattered signal at higher Te is contaminated by fluctuating background light. Individual channels are correlated with either a modeled representation of the laser pulse or a noise-free stray light signal to extract channel amplitudes.

  15. Fast single image haze removal via local atmospheric light veil estimation

    PubMed Central

    Sun, Wei; Wang, Hao; Sun, Changhao; Guo, Baolong; Jia, Wenyan; Sun, Mingui

    2015-01-01

    In this study, a novel single-image based dehazing framework is proposed to remove haze artifacts from images through local atmospheric light estimation. We use a novel strategy based on a physical model where the extreme intensity of each RGB pixel is used to define an initial atmospheric veil (local atmospheric light veil). Across bilateral filter is applied to each veil to achieve both local smoothness and edge preservation. A transmission map and a reflection component of each RGB channel are constructed from the physical atmospheric scattering model. The proposed approach avoids adverse effects caused by the error in estimating the global atmospheric light. Experimental results on outdoor hazy images demonstrate that the proposed method produces image output with satisfactory visual quality and color fidelity. Our comparative study demonstrates a higher performance of our method over several state-of-the-art methods. PMID:26744548

  16. Ultrahigh enhancement in absolute and relative rotation sensing using fast and slow light

    SciTech Connect

    Shahriar, M. S.; Pati, G. S.; Tripathi, R.; Gopal, V.; Messall, M.; Salit, K.

    2007-05-15

    We describe a resonator-based optical gyroscope whose sensitivity for measuring absolute rotation is enhanced via use of the anomalous dispersion characteristic of superluminal light propagation. The enhancement is given by the inverse of the group index, saturating to a bound determined by the group velocity dispersion. We also show how the offsetting effect of the concomitant broadening of the resonator linewidth may be circumvented by using an active cavity. For realistic conditions, the enhancement factor is as high as 10{sup 6}. We also show how normal dispersion used for slow light can enhance relative rotation sensing in a specially designed Sagnac interferometer, with the enhancement given by the slowing factor.

  17. New exclusion limits on scalar and pseudoscalar axionlike particles from light shining through a wall

    NASA Astrophysics Data System (ADS)

    Ballou, R.; Deferne, G.; Finger, M.; Finger, M.; Flekova, L.; Hosek, J.; Kunc, S.; Macuchova, K.; Meissner, K. A.; Pugnat, P.; Schott, M.; Siemko, A.; Slunecka, M.; Sulc, M.; Weinsheimer, C.; Zicha, J.; Osqar Collaboration

    2015-11-01

    Physics beyond the Standard Model predicts the possible existence of new particles that can be searched at the low-energy frontier in the sub-eV range. The OSQAR photon regeneration experiment looks for "light shining through a wall" from the quantum oscillation of optical photons into "weakly interacting sub-eV particles," such as axion or axionlike particles (ALPs) in a 9 T transverse magnetic field over a length of 2 ×14.3 m . In 2014, this experiment was run with an outstanding sensitivity, using an 18.5 W continuous wave laser emitting in the green at the single wavelength of 532 nm. No regenerated photons have been detected after the wall, pushing the limits for the existence of axions and ALPs down to an unprecedented level for such type of laboratory experiment. The diphoton couplings of possible pseudoscalar and scalar ALPs can be constrained in the nearly massless limit to be less than 3.5 ×10-8 GeV-1 and 3.2 ×10-8 GeV-1 , respectively, at 95% confidence level.

  18. Photocatalytic bactericidal action of fluorescent light in a titanium dioxide particle mixture: an in vitro study.

    PubMed

    Koseki, Hironobu; Shiraishi, Koutaro; Asahara, Tomohiko; Tsurumoto, Toshiyuki; Shindo, Hiroyuki; Baba, Koumei; Taoda, Hiroshi; Terasaki, Nao

    2009-06-01

    Traditional titanium dioxide (TiO(2)) has photocatalytic bactericidal properties only under ultraviolet (UV) irradiation, which restricts its use in clinical treatment regimens. In this study, we evaluated the photocatalytic bactericidal effects of an aqueous system of TiO(2) particles irradiated by fluorescent light (FL) on Staphylococcus aureus. A TiO(2) particle mixture containing 19 ppm (0.019 mg/mL) of TiO(2) was prepared. A bacterial solution of 1 x 10(5) CFU/mL was added one drop at a time to the TiO(2) mixture. The resulting product was then irradiated with FL. The bacterial survival rate decreased steadily in the TiO(2) mixture group, reaching 76.7% after 30 min of FL irradiation and 10.9% after 60 min. After 60 to 180 min, the bacterial survival ratio of the TiO(2) mixture group was significantly lower than that of the control group (P < 0.05). The present study indicates that treating the surfaces of surgical devices and the surgical field with a TiO(2) particle mixture can create a nearly sterile environment that can be maintained throughout surgery, even at low luminous intensities.

  19. Single and double ionization of helium by the impact of fast charged particles

    NASA Astrophysics Data System (ADS)

    Jones, S.; Madison, D. H.; Macek, Joseph H.

    2005-12-01

    A survey of the recent literature shows that paradoxes abound in electron- and ion-impact ionization of helium. For example, Schulz et al. [M. Schulz, R. Moshammer, D. Fischer, H. Kollmus, D.H. Madison, S. Jones, J. Ullrich, Nature 422 (2003) 48] found that first-Born and three-body distorted-wave (3DW) theories reproduced their data for single ionization of helium by very fast fully stripped carbon ions in the scattering plane, but not outside the scattering plane. For much slower impacting carbon ions, however, Madison et al. [D.H. Madison, D. Fischer, M. Foster, M. Schulz, R. Moshammer, S. Jones, J. Ullrich, Phys. Rev. Lett. 91 (2003) 253201] found good agreement between 3DW theory and experiment, even outside the scattering plane. This creates a dilemma, since distorted-wave perturbation theories are generally thought to improve with increasing, not decreasing, projectile speed! In this contribution, we will address these and other issues, and suggest possible ways of proceeding.

  20. A fast, scalable method for the parallel evaluation of distance-limited pairwise particle interactions.

    PubMed

    Shaw, David E

    2005-10-01

    Classical molecular dynamics simulations of biological macromolecules in explicitly modeled solvent typically require the evaluation of interactions between all pairs of atoms separated by no more than some distance R, with more distant interactions handled using some less expensive method. Performing such simulations for periods on the order of a millisecond is likely to require the use of massive parallelism. The extent to which such simulations can be efficiently parallelized, however, has historically been limited by the time required for interprocessor communication. This article introduces a new method for the parallel evaluation of distance-limited pairwise particle interactions that significantly reduces the amount of data transferred between processors by comparison with traditional methods. Specifically, the amount of data transferred into and out of a given processor scales as O(R(3/2)p(-1/2)), where p is the number of processors, and with constant factors that should yield a substantial performance advantage in practice.

  1. An initial measurement of a fast neutral spectrum for ion cyclotron range of frequency heated plasma using two-channel compact neutral particle analyzers in KSTAR

    NASA Astrophysics Data System (ADS)

    Kim, S. H.; Wang, S. J.; Park, M.; Kim, S. K.

    2013-11-01

    The accurate measurement of fast neutral particles from high energy ion tails is very important since it is a measure of ion cyclotron range of frequency (ICRF) or neutral beam (NB) ion heating. In KSTAR, fast neutral measurements have been carried out using a compact neutral particle analyzer based on the silicon photo diode since 2010. As a result, the fast neutral spectrum was observed consistent with the ion temperature, diamagnetic energy, and neutron flux in 2011. However, there was fast neutral count beyond the injected neutral beam energy in NB-only heating. Since it is difficult to expect the count unless the temperature is high enough to diffuse the fast ions beyond the beam energy it was required to identify what it is. During the 2012 campaign, the two-channel diode detectors with and without a particle stopper were used to distinguish fast neutral counts and other counts by a hard X-ray or neutrons. As a result, it was confirmed that the high energy component beyond the beam energy originated from a hard X-ray or neutrons. Finally, it was observed that faster neutrals are generated by ICRF heating and enhanced by electron cyclotron heating compared to NB-only heating.

  2. An initial measurement of a fast neutral spectrum for ion cyclotron range of frequency heated plasma using two-channel compact neutral particle analyzers in KSTAR

    SciTech Connect

    Kim, S. H.; Park, M.; Kim, S. K.; Wang, S. J.

    2013-11-15

    The accurate measurement of fast neutral particles from high energy ion tails is very important since it is a measure of ion cyclotron range of frequency (ICRF) or neutral beam (NB) ion heating. In KSTAR, fast neutral measurements have been carried out using a compact neutral particle analyzer based on the silicon photo diode since 2010. As a result, the fast neutral spectrum was observed consistent with the ion temperature, diamagnetic energy, and neutron flux in 2011. However, there was fast neutral count beyond the injected neutral beam energy in NB-only heating. Since it is difficult to expect the count unless the temperature is high enough to diffuse the fast ions beyond the beam energy it was required to identify what it is. During the 2012 campaign, the two-channel diode detectors with and without a particle stopper were used to distinguish fast neutral counts and other counts by a hard X-ray or neutrons. As a result, it was confirmed that the high energy component beyond the beam energy originated from a hard X-ray or neutrons. Finally, it was observed that faster neutrals are generated by ICRF heating and enhanced by electron cyclotron heating compared to NB-only heating.

  3. Optimizing and extending light-sculpting microscopy for fast functional imaging in neuroscience

    PubMed Central

    Rupprecht, Peter; Prevedel, Robert; Groessl, Florian; Haubensak, Wulf E.; Vaziri, Alipasha

    2015-01-01

    A number of questions in system biology such as understanding how dynamics of neuronal networks are related to brain function require the ability to capture the functional dynamics of large cellular populations at high speed. Recently, this has driven the development of a number of parallel and high speed imaging techniques such as light-sculpting microscopy, which has been used to capture neuronal dynamics at the whole brain and single cell level in small model organisms. However, the broader applicability of light-sculpting microcopy is limited by the size of volumes for which high speed imaging can be obtained and scattering in brain tissue. Here, we present strategies for optimizing the present tradeoffs in light-sculpting microscopy. Various scanning modalities in light-sculpting microscopy are theoretically and experimentally evaluated, and strategies to maximize the obtainable volume speeds, and depth penetration in brain tissue using different laser systems are provided. Design-choices, important parameters and their trade-offs are experimentally demonstrated by performing calcium-imaging in acute mouse-brain slices. We further show that synchronization of line-scanning techniques with rolling-shutter read-out of the camera can reduce scattering effects and enhance image contrast at depth. PMID:25780729

  4. Optically active biological particle distinguishing apparatus

    DOEpatents

    Salzman, Gary C.; Kupperman, Robert H.

    1989-01-01

    The disclosure is directed to organic particle sorting and identification. High frequency pulses of circularly polarized light, alternating between left and right, intersect a fast moving stream of organic particles. Circular intensity differential scattering and linear intensity differential scattering are monitored to uniquely identify a variety of organic particles.

  5. Controlling slow and fast light and dynamic pulse-splitting with tunable optical gain in a whispering-gallery-mode microcavity

    NASA Astrophysics Data System (ADS)

    Asano, M.; Özdemir, Ş. K.; Chen, W.; Ikuta, R.; Yang, L.; Imoto, N.; Yamamoto, T.

    2016-05-01

    We report controllable manipulation of slow and fast light in a whispering-gallery-mode microtoroid resonator fabricated from Erbium (Er3+) doped silica. We observe continuous transition of the coupling between the fiber-taper waveguide and the microresonator from undercoupling to critical coupling and then to overcoupling regimes by increasing the pump power even though the spatial distance between the resonator and the waveguide was kept fixed. This, in turn, enables switching from fast to slow light and vice versa just by increasing the optical gain. An enhancement of delay of two-fold over the passive silica resonator (no optical gain) was observed in the slow light regime. Moreover, we show dynamic pulse splitting and its control in slow/fast light systems using optical gain.

  6. Fast phase unwrapping algorithm based on region partition for structured light vision measurement

    NASA Astrophysics Data System (ADS)

    Lu, Jun; Su, Hang

    2014-04-01

    Phase unwrapping is a key problem of phase-shifting profilometry vision measurement for complex object surface shapes. The simple path-following phase unwrapping algorithm is fast but has serious unwrapping error for complex shapes. The Goldstein+flood phase unwrapping algorithm can handle some complex shape object measurement; however, it is time consuming. We propose a fast phase unwrapping algorithm based on region partition according to a quality map of wrapped phase. In this algorithm, wrapped phase image is divided into several regions using partition thresholds, which are determined according to histogram of quality value. Each region is unwrapped by using a simple path-following phase algorithm and several groups with different priorities are generated. These groups are merged according to their priorities from high to low order and a final absolute phase is obtained. The proposed method is applied to wrapped phase images of three objects with and without noise. Experiments show that the proposed method is much faster, more accurate, and robust to noise than the Goldstein+flood algorithm in unwrapping complex phase image.

  7. Probing effects of polymer adsorption in colloidal particle suspensions by light scattering as relevant for the aquatic environment: An overview.

    PubMed

    Tiraferri, Alberto; Borkovec, Michal

    2015-12-01

    Modification of particle surfaces by adsorption of polymers is a process that governs particle behavior in aqueous environmental systems. The present article briefly reviews the current understanding of the adsorption mechanisms and the properties of the resulting layers, and it discusses two environmentally relevant cases of particle modification by polymers. In particular, the discussion focuses on the usefulness of methods based on light scattering to probe such adsorbed layers together with the resulting properties of the particle suspensions, and it highlights advantages and disadvantages of these techniques. Measurement of the electrophoretic mobility allows to follow the development of the adsorption layer and to characterize the charge of the modified particles. At saturation, the surface charge is governed by the charge of the adsorbed film. Dynamic light scattering provides information on the film thickness and on the behavior of the modified suspensions. The charge and the structure of the adsorbed layer influence the stability of the particles, as well as the applicability of the classical theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO). This fundamental knowledge is presented in the light of environmental systems and its significance for applied systems is underlined. In particular, the article discusses two examples of environmental processes involving adsorption of polymers, namely, the modification of particles by natural adsorption of humic substances and the tailoring of surface properties of iron-based particles used to remediate contaminated aquifers.

  8. Fast synthesis of high-quality reduced graphene oxide at room temperature under light exposure

    NASA Astrophysics Data System (ADS)

    Some, Surajit; Kim, Sungjin; Samanta, Khokan; Kim, Youngmin; Yoon, Yeoheung; Park, Younghun; Lee, Sae Mi; Lee, Keunsik; Lee, Hyoyoung

    2014-09-01

    An approach of presenting new reducing reagents, sodium-benzophenone (Na-B) or Na-B in the presence of the hydrazine (Na-B-H) system under light exposure could produce rGOs with/without N-doping at room temperature in both the solution phase and on a solid substrate. Benzophenone activated those solutions acting as a photosensitizer under light. It was assumed that the newly generated radical anions with electrons from Na-B under light can reduce GO to rGO sheets (rGONa-B1). In addition, the Na-B-H system can allow a higher degree of reduction with the doping of nitrogen atoms by the introduction of hydrazine to produce radical anions and electrons with a sodium hydrazide complex, which helps decrease the sheet resistance of the as-made rGONa-B-H2. The excellent properties (very low oxygen content (C/O ~16.2), and low sheet resistance (~130 Ω square-1)) of the rGOs were confirmed by XPS, XRD, IR, Raman spectroscopy, TGA, wettability, and sheet resistance measurements. High-quality rGO films on flexible substrates could be prepared by directly immersing the GO films in these solutions for several minutes.An approach of presenting new reducing reagents, sodium-benzophenone (Na-B) or Na-B in the presence of the hydrazine (Na-B-H) system under light exposure could produce rGOs with/without N-doping at room temperature in both the solution phase and on a solid substrate. Benzophenone activated those solutions acting as a photosensitizer under light. It was assumed that the newly generated radical anions with electrons from Na-B under light can reduce GO to rGO sheets (rGONa-B1). In addition, the Na-B-H system can allow a higher degree of reduction with the doping of nitrogen atoms by the introduction of hydrazine to produce radical anions and electrons with a sodium hydrazide complex, which helps decrease the sheet resistance of the as-made rGONa-B-H2. The excellent properties (very low oxygen content (C/O ~16.2), and low sheet resistance (~130 Ω square-1)) of the r

  9. Cross sections for inelastic collisions of fast charged particles with atoms and molecules

    SciTech Connect

    Inokuti, Mitio

    1985-01-01

    A large volume of data of these cross sections are required for solving problems of radiological physics and dosimetry, as well as for detailed analysis of the earliest stage of radiation actions on matter (including the biological cell and substances constituting it). Current experimental data of the cross sections are far from being complete or even satisfactory for tentative applications. One practical approach to the cross-section determination is to test experimental data with general criteria. For example, the Bethe theory indicates a close connection between photoabsorption and energy absorption by glancing collisions. Development and use of these data constraints, first put forth by Platzman, can now be demonstrated in many examples. More recent studies concern the determination of the analytic expression most suitable for fitting the data on the oscillator-strength distribution or the energy distribution of secondary electrons from ionizing collisions of charged particles. There are three areas to which major efforts should be directed. First, methods of absolute cross-section measurements both for electron and ionic collisions must be thoroughly reviewed so that sources of systematic errors may be identified and corrected. Second, efforts should be devoted to the understanding of the data systematics, viz., the trends of cross sections for a series of molecules. Finally, electron and ionic collisions with molecules in condensed phases will be an important topic of study for years to come; initial reports on efforts toward this direction are encouraging. 46 refs.

  10. Sulfonated graphene oxide-ZnO-Ag photocatalyst for fast photodegradation and disinfection under visible light.

    PubMed

    Gao, Peng; Ng, Kokseng; Sun, Darren Delai

    2013-11-15

    Synthesis of efficient visible-light-driven photocatalyst is urgent but challenging for environmental remediation. In this work, for the first time, the hierarchical plasmonic sulfonated graphene oxide-ZnO-Ag (SGO-ZnO-Ag) composites were prepared through nanocrystal-seed-directed hydrothermal method combining with polyol-reduction process. The results indicated that SGO-ZnO-Ag exhibited much faster rate in photodegradation of Rhodamine B (RhB) and disinfection of Escherichia coli (E. coli), than ZnO, SGO-ZnO and ZnO-Ag. SGO-ZnO-Ag totally degraded RhB dye and kill 99% of E. coli within 20 min under visible light irradiation. The outstanding performances of SGO-ZnO-Ag were attributed to the synergetic merits of SGO sheets, ZnO nanorod arrays and Ag nanoparticles. Firstly, the light absorption ability of SGO-ZnO-Ag composite in the visible region was enhanced due to the surface plasmon resonance of Ag. In addition, the hierarchical structure of SGO-ZnO-Ag composite improved the incident light scattering and reflection. Furthermore, SGO sheets facilitated charge transfer and reduce electron-hole recombination rate. Finally, the tentative mechanism was proposed and verified by the photoluminescence (PL) measurement as well as the theoretical finite-difference time-domain (FDTD) simulation. In view of above, this work paves the way for preparation of multi-component plasmonic composites and highlights the potential applications of SGO-ZnO-Ag in photocatalytic wastewater treatment field.

  11. Fast synthesis of high-quality reduced graphene oxide at room temperature under light exposure.

    PubMed

    Some, Surajit; Kim, Sungjin; Samanta, Khokan; Kim, Youngmin; Yoon, Yeoheung; Park, Younghun; Lee, Sae Mi; Lee, Keunsik; Lee, Hyoyoung

    2014-10-07

    An approach of presenting new reducing reagents, sodium-benzophenone (Na-B) or Na-B in the presence of the hydrazine (Na-B-H) system under light exposure could produce rGOs with/without N-doping at room temperature in both the solution phase and on a solid substrate. Benzophenone activated those solutions acting as a photosensitizer under light. It was assumed that the newly generated radical anions with electrons from Na-B under light can reduce GO to rGO sheets (rGONa-B1). In addition, the Na-B-H system can allow a higher degree of reduction with the doping of nitrogen atoms by the introduction of hydrazine to produce radical anions and electrons with a sodium hydrazide complex, which helps decrease the sheet resistance of the as-made rGONa-B-H2. The excellent properties (very low oxygen content (C/O ∼16.2), and low sheet resistance (∼130 Ω square(-1))) of the rGOs were confirmed by XPS, XRD, IR, Raman spectroscopy, TGA, wettability, and sheet resistance measurements. High-quality rGO films on flexible substrates could be prepared by directly immersing the GO films in these solutions for several minutes.

  12. Ultra-fast annealing to reduce the residual stress in ultra-thin chips using flash light

    NASA Astrophysics Data System (ADS)

    Jeon, Eun-Beom; Park, Junhong; Kim, Hak-Sung

    2014-04-01

    The continuing trend of miniaturization in electronic equipment includes demands for thinner and smaller semiconductor devices with higher performance. To ensure the reliability of electronic devices and to enable high-throughput packaging processes, the mechanical properties of ultra-thin chips need to be accurately understood. One important consideration is the residual stress generated during wafer thinning due to the shear force between the grinding wheel and polish pad; this stress can degrade the fracture strength of ultra-thin devices. To reduce this residual stress, we developed a flash light irradiation annealing technique, including optimization of the irradiation conditions of flash light energy, pulse number and pulse duration. The distributions of residual stresses within ultra-thin flash memory chips before and after the annealing were measured using Raman spectroscopy, and their fracture strength was measured using a ball-on-ring test. Also, transmission electron microscopy (TEM) analysis and beam transfer function tests were performed to investigate the changes in mechanical properties and changes to the silicon lattice effected by the annealing. The ultra-fast flash light annealing was found to reduce the residual stress of ultra-thin chips by 50%, thereby improving their fracture strength by 20% compared to unannealed chips.

  13. Fast and direct quantification of underivatized muscone by ultra performance liquid chromatography coupled with evaporative light scattering detection.

    PubMed

    Jin, Cheng; Yan, Chunxia; Luo, Yun; Li, Baocai; He, Jing; Xiao, Xiaohe

    2013-06-01

    A new reversed phase ultra performance liquid chromatography coupled with evaporative light scattering detection is developed for the fast and direct quantification of underivatized muscone in precious herbal medicine musk. Separation of muscone was achieved on a Waters Acquity BEH C18 (50 × 2.1 mm id, 1.7 μm) column. The runtime was as short as 5 min. The mode of evaporative light scattering detection was set at Impact On. The influence of evaporative light scattering detection condition on sensitivity was investigated. The optimized condition was: drift tube temperature at 30°C, gas flow rate 4.2 L/min. The method was validated with respect to the precision, sensitivity, accuracy, linearity, stability, and robustness were measured in this paper. The calibration curves showed good linear regression (r = 0.9914) within the test range. The recovery rate was 98.6%. The limit of detection for muscone was 2.0 ng. The validated method was rapid, simple, reproducible, and convenient for the quantification of muscone in musk and the related products.

  14. Synechococcus elongatus UTEX 2973, a fast growing cyanobacterial chassis for biosynthesis using light and CO₂.

    PubMed

    Yu, Jingjie; Liberton, Michelle; Cliften, Paul F; Head, Richard D; Jacobs, Jon M; Smith, Richard D; Koppenaal, David W; Brand, Jerry J; Pakrasi, Himadri B

    2015-01-30

    Photosynthetic microbes are of emerging interest as production organisms in biotechnology because they can grow autotrophically using sunlight, an abundant energy source, and CO₂, a greenhouse gas. Important traits for such microbes are fast growth and amenability to genetic manipulation. Here we describe Synechococcus elongatus UTEX 2973, a unicellular cyanobacterium capable of rapid autotrophic growth, comparable to heterotrophic industrial hosts such as yeast. Synechococcus UTEX 2973 can be readily transformed for facile generation of desired knockout and knock-in mutations. Genome sequencing coupled with global proteomics studies revealed that Synechococcus UTEX 2973 is a close relative of the widely studied cyanobacterium Synechococcus elongatus PCC 7942, an organism that grows more than two times slower. A small number of nucleotide changes are the only significant differences between the genomes of these two cyanobacterial strains. Thus, our study has unraveled genetic determinants necessary for rapid growth of cyanobacterial strains of significant industrial potential.

  15. Synechococcus elongatus UTEX 2973, a fast growing cyanobacterial chassis for biosynthesis using light and CO2

    DOE PAGES

    Yu, Jingjie; Liberton, Michelle; Cliften, Paul F.; ...

    2015-01-30

    Photosynthetic microbes are of emerging interest as production organisms in biotechnology because they can grow autotrophically using sunlight, an abundant energy source, and CO2, a greenhouse gas. Important traits for such microbes are fast growth and amenability to genetic manipulation. Here we describe Synechococcus elongatus UTEX 2973, a unicellular cyanobacterium capable of rapid autotrophic growth, comparable to heterotrophic industrial hosts such as yeast. Synechococcus 2973 can be readily transformed for facile generation of desired knockout and knock-in mutations. Genome sequencing coupled with global proteomics studies revealed that Synechococcus 2973 is a close relative of the widely studied cyanobacterium Synechococcus elongatusmore » PCC 7942, an organism that grows more than two times slower. A small number of nucleotide changes are the only significant differences between the genomes of these two cyanobacterial strains. Thus, our study has unraveled genetic determinants necessary for rapid growth of cyanobacterial strains of significant industrial potential.« less

  16. Synechococcus elongatus UTEX 2973, a fast growing cyanobacterial chassis for biosynthesis using light and CO2

    SciTech Connect

    Yu, Jingjie; Liberton, Michelle; Cliften, Paul F.; Head, Richard D.; Jacobs, Jon M.; Smith, Richard D.; Koppenaal, David W.; Brand, Jerry J.; Pakrasi, Himadri B.

    2015-01-30

    Photosynthetic microbes are of emerging interest as production organisms in biotechnology because they can grow autotrophically using sunlight, an abundant energy source, and CO2, a greenhouse gas. Important traits for such microbes are fast growth and amenability to genetic manipulation. Here we describe Synechococcus elongatus UTEX 2973, a unicellular cyanobacterium capable of rapid autotrophic growth, comparable to heterotrophic industrial hosts such as yeast. Synechococcus 2973 can be readily transformed for facile generation of desired knockout and knock-in mutations. Genome sequencing coupled with global proteomics studies revealed that Synechococcus 2973 is a close relative of the widely studied cyanobacterium Synechococcus elongatus PCC 7942, an organism that grows more than two times slower. A small number of nucleotide changes are the only significant differences between the genomes of these two cyanobacterial strains. Thus, our study has unraveled genetic determinants necessary for rapid growth of cyanobacterial strains of significant industrial potential.

  17. Weathering of a carbon nanotube/epoxy nanocomposite under UV light and in water bath: impact on abraded particles.

    PubMed

    Schlagenhauf, Lukas; Kianfar, Bahareh; Buerki-Thurnherr, Tina; Kuo, Yu-Ying; Wichser, Adrian; Nüesch, Frank; Wick, Peter; Wang, Jing

    2015-11-28

    Weathering processes can influence the surface properties of composites with incorporated nanoparticles. These changes may affect the release behavior of nanoparticles when an abrasion process is applied. Therefore, the influence of two different weathering processes, immersion in water and exposure to UV light, on the properties of abraded particles from a carbon nanotube (CNT)/epoxy nanocomposite was investigated. The investigation included the measurement of the weathering impact on the surface chemistry of the exposed samples, the particle size of abraded particles, the quantity of exposed CNTs in the respirable part of the abraded particles, and the toxicity of abraded particles, measured by in vitro toxicity tests using the THP-1 monocyte-derived macrophages. The results showed that weathering by immersion in water had no influence on the properties of abraded particles. The exposure to UV light caused a degradation of the epoxy on the surface, followed by delamination of an approx. 2.5 μm thick layer. An increased quantity of exposed CNTs in abraded particles was not found; on the contrary, longer UV exposure times decreased the released fraction of CNTs from 0.6% to 0.4%. The toxicity tests revealed that abraded particles from the nanocomposites did not induce additional acute cytotoxic effects compared to particles from the neat epoxy.

  18. Spectral Light Absorption and Scattering by Aerosol Particles in Central Amazonia

    NASA Astrophysics Data System (ADS)

    Artaxo, P.; Holanda, B. A.; Ferreira De Brito, J.; Carbone, S.; Barbosa, H. M.; Rizzo, L. V.; Cirino, G. G.; Andreae, M. O.; Saturno, J.; Pöhlker, C.; Martin, S. T.; Holben, B. N.; Schafer, J.

    2015-12-01

    As part of the GoAmazon2014/5, a detailed characterization of spectral light absorption and light scattering was performed at four research sites located in the central Amazon forest at different distances upwind and downwind of Manaus. The sites ATTO (T0a) and Embrapa (T0e) are located upwind of Manaus where it is possible to observe very pristine atmospheric conditions in wet season. The site Tiwa (T2) is being operated under the direct influence of the Manaus plume at 5 km downwind of Manaus and, finally, the Manacapuru (T3) site is located at about 60 km downwind of Manaus. The spectral dependence of light absorption and light scattering were measured using Aethalometers (7-wavelengths) and Nephelometers (3-wavelengths), respectively. By calculating the Absorption Angstrom Exponent (AAE), it was possible to get information about the source of the aerosol whereas the Scattering Angstrom Exponent (SAE) gives information about its size distribution. Sunphotometers from the AERONET network were set up at T3 and T0e sites to measure column Aerosol Optical Depth (AOD). For all the stations, much higher absorption and scattering coefficients were observed during the dry season in comparison to the wet season, as a result of the larger concentration of BC and OC present in the biomass burning events. Additionally, we also observed Manaus plume pollution that alters the BC signal. There is also an increase of the AAE during the dry season due to the larger amount of aerosols from biomass burning compared with urban pollution. High values of AAE are also observed during the wet season, attributed to the presence of long-range transport of aerosols from Africa. The SAE for all the sites are lower during the wet season, with the dominance of large biological particles, and increases during the dry season as a consequence of fine particles emitted from both biomass and fossil fuel burning. The AOD at T0e and T3 (Jan-Jun/2014) showed very similar values ranging from 0.05 to

  19. Temperature control of light transmission using mixed system of silica hollow particles with nanoparticle shell and organic components.

    PubMed

    Fujiwara, Masahiro; Shiokawa, Kumi; Monobe, Hirosato; Shimizu, Yo

    2015-01-21

    We reported before that a silica hollow particle whose shell consists of silica nanoparticle (SHP-NP) has a high light reflection ability to prevent light transmission through the particle, which is caused from the intensive light diffusion by the hollow structure and the nanoparticle of the shell. Since the difference in the refractive indices between silica and air is responsible for the strong light reflection, the mixing of the particle with organic components having refractive indices close to that of silica such as tetradecane produced transparent mixtures by suppression of the light reflection. The transparency of the mixtures thus prepared could be controlled by temperature variation. For example, the mixture of the particle SHP-NP with tetradecane was transparent at 20 °C and opaque at 70 °C, while the mixture with n-hexyl cyclohexane was opaque at 20 °C and transparent at 70 °C. As the refractive indices of organic components changed with temperature more than 10 times wider than that of silica, the temperature alternation produced a significant change in the difference of the refractive indices between them to achieve complete control of the transparency of the mixtures. This simple control of the light transmission that can automatically regulate sunlight into the room with temperature alteration is expected to be suitable for smart glass technology for energy conservation.

  20. Dynamics of nuclear single-particle structure in covariant theory of particle-vibration coupling: From light to superheavy nuclei

    SciTech Connect

    Litvinova, E. V.; Afanasjev, A. V.

    2011-07-15

    The impact of particle-vibration coupling and polarization effects due to deformation and time-odd mean fields on single-particle spectra is studied systematically in doubly magic nuclei from low-mass {sup 56}Ni up to superheavy ones. Particle-vibration coupling is treated fully self-consistently within the framework of the relativistic particle-vibration coupling model. Polarization effects due to deformation and time-odd mean field induced by odd particle are computed within covariant density functional theory. It has been found that among these contributions the coupling to vibrations makes a major impact on the single-particle structure. The impact of particle-vibration coupling and polarization effects on calculated single-particle spectra, the size of the shell gaps, the spin-orbit splittings and the energy splittings in pseudospin doublets is discussed in detail; these physical observables are compared with experiment. Particle-vibration coupling has to be taken into account when model calculations are compared with experiment since this coupling is responsible for observed fragmentation of experimental levels; experimental spectroscopic factors are reasonably well described in model calculations.

  1. Slow and fast light propagation in a defect slab doped with polaritonic materials and nanoparticles

    NASA Astrophysics Data System (ADS)

    Solookinejad, Gh; Jabbari, M.; Panahi, M.; Ahmadi Sangachin, E.

    2016-12-01

    In this paper, the group velocity of transmitted and reflected pulses through a defect dielectric medium doped with polaritonic materials and nanoparticles is explored by using the density matrix equations and transform matrix method. It is demonstrated that the group velocity of transmitted and reflected lights can be manipulated by adjusting the system’s parameters. The effect of the dipole-dipole interaction is also discussed on behaviors of transmitted and reflected pulses through the slab. Our proposed model may be opened up the possibility of new storage and switching devices based on polaritonic material nanoparticles in future commercial systems.

  2. Very fast light-induced degradation of a-Si:H/c-Si(100) interfaces

    NASA Astrophysics Data System (ADS)

    de Wolf, Stefaan; Demaurex, Bénédicte; Descoeudres, Antoine; Ballif, Christophe

    2011-06-01

    Light-induced degradation (LID) of crystalline silicon (c-Si) surfaces passivated with hydrogenated amorphous silicon (a-Si:H) is investigated. The initial passivation decays on polished c-Si(100) surfaces on a time scale much faster than usually associated with bulk a-Si:H LID. This phenomenon is absent for the a-Si:H/c-Si(111) interface. We attribute these differences to the allowed reconstructions on the respective surfaces. This may point to a link between the presence of so-called “fast” states and (internal) surface reconstruction in bulk a-Si:H.

  3. Light Induced Degradation of Eight Commonly Used Pesticides Adsorbed on Atmospheric Particles: Kinetics and Product Study

    NASA Astrophysics Data System (ADS)

    Socorro, J.; Durand, A.; Gligorovski, S.; Wortham, H.; Quivet, E.

    2014-12-01

    Pesticides are widely used all over the world whether in agricultural production or in non-agricultural settings. They may pose a potential human health effects and environmental risks due to their physico-chemical properties and their extensive use which is growing every year. Pesticides are found in the atmosphere removed from the target area by volatilization or wind erosion, and carried over long distances. These compounds are partitioned between the gaseous and particulate atmospheric phases. The increasingly used pesticides are semi-volatile compounds which are usually adsorbed on the surface of the atmospheric particles. These pesticides may undergo chemical and photo-chemical transformation. New compounds may then be formed that could be more hazardous than the primary pesticides. The atmospheric fate and lifetime of adsorbed pesticides on particles are controlled by the these (photo)chemical processes. However, there is a lack of kinetic data regarding the pesticides in the particle phase. This current work focuses on the photolytic degradation of commonly used pesticides in particulate phase. It aims at estimating the photolytic rates and thus the lifetimes of pesticides adsorbed on silica particles as a proxy of atmospheric particles. The following eight commonly used pesticides, cyprodinil, deltamethrin, difenoconazole, fipronil, oxadiazon, pendimethalin, permethrin, tetraconazole, were chosen because of their physico-chemical properties. The photolysis rates of tetraconazole and permethrin were extremely slow ≤ 1.2 · 10-6 s-1. The photolysis rates for the other pesticides were determined in the range of: (5.9 ± 0.3) · 10-6 < k < (1.7 ± 0.1) · 10-4 s-1 from slowest to the fastest: pendimethalin < cyprodinil < deltamethrin < difenoconazole < oxadiazon < fipronil. Finally, the identification of the surface products upon light irradiation was performed, using GC-(QqQ)-MS/MS and LC-(Q-IMS-ToF)-MS/MS. The potentially formed gas-phase products during

  4. Collection efficiency of α-pinene secondary organic aerosol particles explored via light-scattering single-particle aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Shipley Robinson, Ellis; Onasch, Timothy B.; Worsnop, Douglas; Donahue, Neil M.

    2017-03-01

    We investigated the collection efficiency and effective ionization efficiency for secondary organic aerosol (SOA) particles made from α-pinene + O3 using the single-particle capabilities of the aerosol mass spectrometer (AMS). The mean count-based collection efficiency (CEp) for SOA across these experiments is 0.30 (±0.04 SD), ranging from 0.25 to 0.40. The mean mass-based collection efficiency (CEm) is 0.49 (±0.07 SD). This sub-unit collection efficiency and delayed vaporization is attributable to particle bounce in the vaporization region. Using the coupled optical and chemical detection of the light-scattering single-particle (LSSP) module of the AMS, we provide clear evidence that delayed vaporization is somewhat of a misnomer for these particles: SOA particles measured as a part of the AMS mass distribution do not vaporize at a slow rate; rather, they flash-vaporize, albeit often not on the initial impact with the vaporizer but instead upon a subsequent impact with a hot surface in the vaporization region. We also find that the effective ionization efficiency (defined as ions per particle, IPP) decreases with delayed arrival time. CEp is not a function of particle size (for the mobility diameter range investigated, 170-460 nm), but we did see a decrease in CEp with thermodenuder temperature, implying that oxidation state and/or volatility can affect CEp for SOA. By measuring the mean ions per particle produced for monodisperse particles as a function of signal delay time, we can separately determine CEp and CEm and thus more accurately measure the relative ionization efficiency (compared to ammonium nitrate) of different particle types.

  5. Profiler - A Fast and Versatile New Program for Decomposing Galaxy Light Profiles

    NASA Astrophysics Data System (ADS)

    Ciambur, Bogdan C.

    2016-12-01

    I introduce Profiler, a user-friendly program designed to analyse the radial surface brightness profiles of galaxies. With an intuitive graphical user interface, Profiler can accurately model galaxies of a broad range of morphological types, with various parametric functions routinely employed in the field (Sérsic, core-Sérsic, exponential, Gaussian, Moffat, and Ferrers). In addition to these, Profiler can employ the broken exponential model for disc truncations or anti-truncations, and two special cases of the edge-on disc model: along the disc's major or minor axis. The convolution of (circular or elliptical) models with the point spread function is performed in 2D, and offers a choice between Gaussian, Moffat or a user-provided profile for the point spread function. Profiler is optimised to work with galaxy light profiles obtained from isophotal measurements, which allow for radial gradients in the geometric parameters of the isophotes, and are thus often better at capturing the total light than 2D image-fitting programs. Additionally, the 1D approach is generally less computationally expensive and more stable. I demonstrate Profiler's features by decomposing three case-study galaxies: the cored elliptical galaxy NGC 3348, the nucleated dwarf Seyfert I galaxy Pox 52, and NGC 2549, a double-barred galaxy with an edge-on, truncated disc.

  6. Modeling of light absorbing particles in atmosphere, snow and ice in the Arctic

    NASA Astrophysics Data System (ADS)

    Sobhani, N.; Kulkarni, S.; Carmichael, G. R.

    2015-12-01

    Long-range transport of atmospheric particles from mid-latitude sources to the Arctic is the main contributor to the Arctic aerosol loadings and deposition. Black Carbon (BC), Brown Carbon (BrC) and dust are considered of great climatic importance and are the main absorbers of sunlight in the atmosphere. Furthermore, wet and dry deposition of light absorbing particles (LAPs) on snow and ice cause reduction of snow and ice albedo. LAPs have significant radiative forcing and effect on snow albedo. There are high uncertainties in estimating radiative forcing of LAPs. We studied the potential effect of LAPs from different emission source regions and sectors on snow albedo in the Arctic. The transport pathway of LAPs to the Arctic is studies for different high pollution episodes. In this study a modeling framework including Weather Research and Forecasting Model (WRF) and the University of Iowa's Sulfur Transport and dEpostion model(STEM) is used to predict the transport of LAPs from different geographical sources and sectors (i.e. transportation, residential, industry, biomass burning and power) to the Arctic. For assessing the effect of LAP deposition on snow single-layer simulator of the SNow, Ice, and Aerosol Radiation (SNICAR-Online) model was used to derive snow albedo values for snow albedo reduction causes by BC deposition. To evaluate the simulated values we compared the BC concentration in snow with observed values from previous studies including Doherty et al. 2010.

  7. Thermally induced light-driven microfluidics using a MOEMS-based laser scanner for particle manipulation

    NASA Astrophysics Data System (ADS)

    Kremer, Matthias P.; Tortschanoff, Andreas

    2014-03-01

    One key challenge in the field of microfluidics and lab-on-a-chip experiments for biological or chemical applications is the remote manipulation of fluids, droplets and particles. These can be volume elements of reactants, particles coated with markers, cells or many others. Light-driven microfluidics is one way of accomplishing this challenge. In our work, we manipulated micrometre sized polystyrene beads in a microfluidic environment by inducing thermal flows. Therefore, the beads were held statically in an unstructured microfluidic chamber, containing a dyed watery solution. Inside this chamber, the beads were moved along arbitrary trajectories on a micrometre scale. The experiments were performed, using a MOEMS (micro-opto-electro-mechanical-systems)-based laser scanner with a variable focal length. This scanner system is integrated in a compact device, which is flexibly applicable to various microscope setups. The device utilizes a novel approach for varying the focal length, using an electrically tunable lens. A quasi statically driven MOEMS mirror is used for beam steering. The combination of a tunable lens and a dual axis micromirror makes the device very compact and robust and is capable of positioning the laser focus at any arbitrary location within a three dimensional working space. Hence, the developed device constitutes a valuable extension to manually executed microfluidic lab-on-chip experiments.

  8. Fast and exact method for computing a stack of images at various focuses from a four-dimensional light field

    NASA Astrophysics Data System (ADS)

    Mhabary, Ziv; Levi, Ofer; Small, Eran; Stern, Adrian

    2016-07-01

    This paper presents an efficient method for computing a stack of images digitally focused at various lengths from a four-dimensional light field (LF). The main contribution of this work is a fast and algebraically exact method that does not require interpolation in the frequency or spatial domains as alternative methods do. The proposed imaging operator combines two-dimensional (2-D) fast Fourier transform with 2-D fractional Fourier transform and has computational complexity of O(N log N), where N is the number of pixels in the LF tesseract of dimension N=nx×ny×nu×nv. The whole method consists of unitary vector-based operations; therefore, parallel implementation is easy and can contribute additional speed up. While current state of the art methods suffer from inherent tradeoff between the reconstruction quality and computational complexity, the proposed method benefits of both low-computational complexity and high-reconstruction quality. We also offer a solution for refocusing at distances that are not included in the reconstructed images stack. For such a case, we provide a modified version of our method, which is also algebraically exact and has lower computational complexity than other exact methods.

  9. Design and expected performance of a fast neutron attenuation probe for light element density measurements

    DOE PAGES

    Sweany, M.; Marleau, P.

    2016-07-08

    In this paper, we present the design and expected performance of a proof-of-concept 32 channel material identification system. Our system is based on the energy-dependent attenuation of fast neutrons for four elements: hydrogen, carbon, nitrogen and oxygen. We describe a new approach to obtaining a broad range of neutron energies to probe a sample, as well as our technique for reconstructing the molar densities within a sample. The system's performance as a function of time-of-flight energy resolution is explored using a Geant4-based Monte Carlo. Our results indicate that, with the expected detector response of our system, we will be ablemore » to determine the molar density of all four elements to within a 20–30% accuracy in a two hour scan time. In many cases this error is systematically low, thus the ratio between elements is more accurate. This degree of accuracy is enough to distinguish, for example, a sample of water from a sample of pure hydrogen peroxide: the ratio of oxygen to hydrogen is reconstructed to within 8±0.5% of the true value. Lastly, with future algorithm development that accounts for backgrounds caused by scattering within the sample itself, the accuracy of molar densities, not ratios, may improve to the 5–10% level for a two hour scan time.« less

  10. Design and expected performance of a fast neutron attenuation probe for light element density measurements

    NASA Astrophysics Data System (ADS)

    Sweany, M.; Marleau, P.

    2016-10-01

    We present the design and expected performance of a proof-of-concept 32 channel material identification system. Our system is based on the energy-dependent attenuation of fast neutrons for four elements: hydrogen, carbon, nitrogen and oxygen. We describe a new approach to obtaining a broad range of neutron energies to probe a sample, as well as our technique for reconstructing the molar densities within a sample. The system's performance as a function of time-of-flight energy resolution is explored using a Geant4-based Monte Carlo. Our results indicate that, with the expected detector response of our system, we will be able to determine the molar density of all four elements to within a 20-30% accuracy in a two hour scan time. In many cases this error is systematically low, thus the ratio between elements is more accurate. This degree of accuracy is enough to distinguish, for example, a sample of water from a sample of pure hydrogen peroxide: the ratio of oxygen to hydrogen is reconstructed to within 8±0.5% of the true value. Finally, with future algorithm development that accounts for backgrounds caused by scattering within the sample itself, the accuracy of molar densities, not ratios, may improve to the 5-10% level for a two hour scan time.

  11. [Anxiety in patients undergoing fast-track knee arthroplasty in the light of recent literature].

    PubMed

    Ziętek, Paweł; Ziętek, Joanna; Szczypiór, Karina

    2014-01-01

    The rapid progress in knee implants technology and operational techniques go together with more and more modem medical programs, designed to optimize the patients' care and shorten their stay in hospital. However, this does not guarantee any elimination ofperioperative stress in patients. Anxiety is a negative emotional state arising from stressful circumstances accompanied by activation of the autonomous nervous system. Anxiety causes negative physiological changes, including wound healing, resistance to anesthetic induction, it is associated with an increased perioperative pain and prolong recovery period. The purpose of this work is to present the current state of knowledge on the preoperative anxiety and discuss its impact on pain and other parameters in patients undergoing fast-track arthroplasty of big joints. The work also shows selected issues of anxiety pathomechanism, and actual methods reducing preoperative anxiety in hospitalized patients. The common prevalence of anxiety in patients undergoing surgery induces the attempt to routinely identify patients with higher anxiety, which may be a predictive factor of worse results after TKA. Undertaking widely understood psychological support in these patients before and after the operation could be a favorable element, which would influence thefinal result of the treatment of patients after big joints arthroplasties.

  12. Design and expected performance of a fast neutron attenuation probe for light element density measurements

    SciTech Connect

    Sweany, M.; Marleau, P.

    2016-07-08

    In this paper, we present the design and expected performance of a proof-of-concept 32 channel material identification system. Our system is based on the energy-dependent attenuation of fast neutrons for four elements: hydrogen, carbon, nitrogen and oxygen. We describe a new approach to obtaining a broad range of neutron energies to probe a sample, as well as our technique for reconstructing the molar densities within a sample. The system's performance as a function of time-of-flight energy resolution is explored using a Geant4-based Monte Carlo. Our results indicate that, with the expected detector response of our system, we will be able to determine the molar density of all four elements to within a 20–30% accuracy in a two hour scan time. In many cases this error is systematically low, thus the ratio between elements is more accurate. This degree of accuracy is enough to distinguish, for example, a sample of water from a sample of pure hydrogen peroxide: the ratio of oxygen to hydrogen is reconstructed to within 8±0.5% of the true value. Lastly, with future algorithm development that accounts for backgrounds caused by scattering within the sample itself, the accuracy of molar densities, not ratios, may improve to the 5–10% level for a two hour scan time.

  13. Dual-wavelength light-scattering technique for selective detection of volcanic ash particles in the presence of water droplets

    NASA Astrophysics Data System (ADS)

    Jurányi, Z.; Burtscher, H.; Loepfe, M.; Nenkov, M.; Weingartner, E.

    2015-12-01

    A new method is presented in this paper which analyses the scattered light of individual aerosol particles simultaneously at two different wavelengths in order to retrieve information on the particle type. We show that dust-like particles, such as volcanic ash, can be unambiguously discriminated from water droplets on a single-particle level. As a future application of this method, the detection of volcanic ash particles should be possible in a humid atmosphere in the presence of cloud droplets. The characteristic behaviour of pure water's refractive index can be used to separate water droplets and dust-like particles which are commonly found in the micrometre size range in the ambient air. The low real part of the water's refractive index around 2700-2800 nm results in low scattered light intensities compared to e.g. the visible wavelength range, and this feature can be used for the desired particle identification. The two-wavelength measurement set-up was theoretically and experimentally tested and studied. Theoretical calculations were done using Mie theory. Comparing the ratio of the scattered light at the two wavelengths (visible-to-IR (infrared), R value) for water droplets and different dust types (basalt, andesite, African mineral dust, sand, volcanic ash, pumice) showed at least 9-times-higher values (on average 70 times) for water droplets than for the dust types at any diameter within the particle size range of 2-20 μm. The envisaged measurement set-up was built up into a laboratory prototype and was tested with different types of aerosols. We generated aerosols from the following powders, simulating dust-like particles: cement dust, ISO 12103-1 A1 Ultrafine Test Dust and ash from the 2012 eruption of the Etna volcano. Our measurements verified the theoretical considerations; the median experimental R value is 8-21 times higher for water than for the "dust" particles.

  14. A recursive regularization algorithm for estimating the particle size distribution from multiangle dynamic light scattering measurements

    NASA Astrophysics Data System (ADS)

    Li, Lei; Yang, Kecheng; Li, Wei; Wang, Wanyan; Guo, Wenping; Xia, Min

    2016-07-01

    Conventional regularization methods have been widely used for estimating particle size distribution (PSD) in single-angle dynamic light scattering, but they could not be used directly in multiangle dynamic light scattering (MDLS) measurements for lack of accurate angular weighting coefficients, which greatly affects the PSD determination and none of the regularization methods perform well for both unimodal and multimodal distributions. In this paper, we propose a recursive regularization method-Recursion Nonnegative Tikhonov-Phillips-Twomey (RNNT-PT) algorithm for estimating the weighting coefficients and PSD from MDLS data. This is a self-adaptive algorithm which distinguishes characteristics of PSDs and chooses the optimal inversion method from Nonnegative Tikhonov (NNT) and Nonnegative Phillips-Twomey (NNPT) regularization algorithm efficiently and automatically. In simulations, the proposed algorithm was able to estimate the PSDs more accurately than the classical regularization methods and performed stably against random noise and adaptable to both unimodal and multimodal distributions. Furthermore, we found that the six-angle analysis in the 30-130° range is an optimal angle set for both unimodal and multimodal PSDs.

  15. Visible light photocatalytic activity of BiVO4 particles with different morphologies

    NASA Astrophysics Data System (ADS)

    Lin, Xue; Yu, Lili; Yan, Lina; Li, Hongji; Yan, Yongsheng; Liu, Chunbo; Zhai, Hongju

    2014-06-01

    Bismuth vanadate (BiVO4) particles with different morphologies were synthesized by a one-step hydrothermal process and their optical and photocatalytic properties were investigated. Their crystal structure and microstructures were characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). XRD patterns demonstrate that the as-prepared samples are monoclinic cell. FESEM shows that BiVO4 crystals can be fabricated in different morphologies by simply manipulating the reaction parameters of hydrothermal process. The UV-visible diffuse reflectance spectra (UV-vis DRS) reveal that the band gaps of BiVO4 photocatalysts are about 2.07-2.21 eV. The as-prepared BiVO4 photocatalysts exhibit higher photocatalytic activities in the degradation of rhodamine B (Rh B) under visible light irradiation (λ > 420 nm) compared with traditional N-doped TiO2 (N-TiO2). Furthermore, wheat like BiVO4 sample reveals the highest photocatalytic activity. Up to 100% Rh B is decolorized after visible light irradiation for 180 min. The reason for the difference in the photocatalytic activities for BiVO4 samples obtained at different conditions were systematically studied based on their shape, size and the variation of local structure.

  16. Contribution of fine-particle sulfates to light scattering in St. Louis

    SciTech Connect

    Vossler, R.L.

    1985-01-01

    The extent to which sulfates produce visibility reduction in the St. Louis area was examined. The contribution of fine aerosol sulfates to total light scattering was calculated from measured sulfur size distributions and Mie theory of light scattering. The aerosol was collected during both a summer and a winter season. Short sampling intervals (10 minutes to 3 hours) permitted observation of the fine structure of the sulfur size distribution and concentration, and involved only small changes in meteorology. Size separation was accomplished with an 8-stage low pressure impactor, which yielded size fractions in the range of 4 ..mu..m greater than or equal to d greater than or equal to 0.05 ..mu..m. Elemental sulfur was measured by flash volatilization and flame photometric detection. All fine sulfur was assumed to be in the form of (NH/sub 4/)/sub 2/SO/sub 4/. Water which might be associated with this deliquescent aerosol was estimated. The measured light scattering coefficient and (NH/sub 4/)/sub 2/SO/sub 4/ were extremely well correlated (r = 0.97) in the summer, but not as well correlated (r = 0.63) in the winter. Conversely, the light scattering coefficient and non-sulfate fine mass were well correlated (r = 0.85) in the winter, but poorly correlated (r = 0.24) in the summer. The light scattering efficiency of (NH/sub 4/)/sub 2/SO/sub 4/ plus associated water calculated from Mie theory and size distributions was 4.2 m/sup 2//g for the summer aerosol, but only 2.0 m/sup 2//g for the dry winter (NH/sub 4/)/sub 2/SO/sub 4/. Two basic types of sulfur size distributions were observed. The most common type observed during the summer had a major sulfur mass peak between 0.5 ..mu..m and 1.0 ..mu..m in diameter. The combination of large sulfate particles and high sulfate loadings led to the dominance of sulfates in visibility reduction during the summer.

  17. In situ measurements of particulate number density and size distribution from an aircraft. [using light scattering particle counter

    NASA Technical Reports Server (NTRS)

    Briehl, D.

    1974-01-01

    Two different commercial particulate measuring instruments were flown aboard the NASA Convair 990. A condensation nuclei monitor was utilized to measure particles larger than approximately 0.003 micron in diameter. A specially designed pressurization system was used with this monitor at cabin altitude pressure. A near-forward light scattering counter was used to measure the number and size distribution particles in the size range from 0.5 to 5 microns and greater in diameter. Considerable variation in number density was encountered for both classes of particles at the test altitudes ranging from 5 to 12 km. Presence of clouds could be detected by the light scattering instrument because large numbers of particles would then be registered by the instrument, especially in the size range above 5.0 microns in diameter.

  18. Causes of variability in light absorption by particles in snow at sites in Idaho and Utah

    NASA Astrophysics Data System (ADS)

    Doherty, Sarah J.; Hegg, Dean A.; Johnson, James E.; Quinn, Patricia K.; Schwarz, Joshua P.; Dang, Cheng; Warren, Stephen G.

    2016-05-01

    A characterization of black carbon (BC) and other light-absorbing particles in snow is presented for three mountain valley sites in Idaho in early 2014 and for one site near Vernal, Utah, in early 2013 and 2014. The focus of the study was on constraining the magnitude and drivers of variations in particulate absorbers in midlatitude U.S. seasonal snow. Mass mixing ratios of BC in newly fallen snow were similar at all three Idaho sites, with a median of 4.7 ± 4.2 ng BC per gram of snow. The median total light-absorbing particulate mixing ratios in new snow, expressed as an equivalent mixing ratio of BC, was 18 ± 23 ng g-1. At the Utah site, which is near sources of both fossil fuel and dust, the mixing ratios of BC varied from 7 to 45 ng g-1 across seven new snowfall samples, and the BC-equivalent mixing ratios varied from 9 to 1500 ng g-1. At all sites, dry deposition and in-snow processes increase the mixing ratio of BC by up to an order of magnitude and increase the mixing ratio of all light-absorbing particulates by up to 2 orders of magnitude, highlighting the importance of capturing these processes for accurately representing snow albedo in climate models. Spatial variability at a range of scales is found to be considerably smaller than the temporal variations at a given site, with implications for the representativeness of field samples used in observation/model comparisons.

  19. PREFACE: 1st Conference on Light and Particle Beams in Materials Science 2013 (LPBMS2013)

    NASA Astrophysics Data System (ADS)

    Kumai, Reiji; Murakami, Youichi

    2014-04-01

    From 29-31 August 2013, the 1st International Conference on Light and Particle Beams in Materials Science, LPBMS 2013, took place in the Tsukuba International Congress Center in the city of Tsukuba, Japan. The conference was a continuation of the international series Synchrotron Radiation in Materials Science (SRMS), which started in 1994. The last one, SRMS-7, was held in Oxford UK 11-14 July 2010, where the International Advisory Committee (IAC) recommended the conference be enlarged to incorporate Materials Research from Neutron, Muon, and Slow Positron Sources, as well as the science emerging from Synchrotron Light Sources. The conference brought together contributions from academics and industrial researchers with a diverse background and experience from the physics, chemistry and engineering communities. The topics covered in the LPBMS2013 include strongly correlated electron systems, magnetism and magnetic materials, soft matter, interface and surface defects, catalysts, biomaterials, and ceramics. In the 3-day scientific program, the conference consisted of 9 plenary talks, 33 invited talks, 20 oral presentations, and 126 poster presentations. We are pleased to publish the proceedings of the LPBMS2013 in this volume of Journal of Physics: Conference Series. This volume contains 58 papers representing the work that was presented and discussed at the conference. We hope that this volume will promote further development of this interdisciplinary materials research emerging from synchrotron light, neutron, muon, and slow positron sciences. Finally, we would like to thank the International Advisory Committee (Chair: Professor G N Greaves), sponsors, all the participants and contributors for making possible this international meeting of researchers. Reiji Kumai & Youichi Murakami Conference photograph Details of the program and organizing committees are available in the pdf

  20. Fast mapping of terahertz bursting thresholds and characteristics at synchrotron light sources

    NASA Astrophysics Data System (ADS)

    Brosi, Miriam; Steinmann, Johannes L.; Blomley, Edmund; Bründermann, Erik; Caselle, Michele; Hiller, Nicole; Kehrer, Benjamin; Mathis, Yves-Laurent; Nasse, Michael J.; Rota, Lorenzo; Schedler, Manuel; Schönfeldt, Patrik; Schuh, Marcel; Schwarz, Markus; Weber, Marc; Müller, Anke-Susanne

    2016-11-01

    Dedicated optics with extremely short electron bunches enable synchrotron light sources to generate intense coherent THz radiation. The high degree of spatial compression in this so-called low-αc optics entails a complex longitudinal dynamics of the electron bunches, which can be probed studying the fluctuations in the emitted terahertz radiation caused by the microbunching instability ("bursting"). This article presents a "quasi-instantaneous" method for measuring the bursting characteristics by simultaneously collecting and evaluating the information from all bunches in a multibunch fill, reducing the measurement time from hours to seconds. This speed-up allows systematic studies of the bursting characteristics for various accelerator settings within a single fill of the machine, enabling a comprehensive comparison of the measured bursting thresholds with theoretical predictions by the bunched-beam theory. This paper introduces the method and presents first results obtained at the ANKA synchrotron radiation facility.

  1. Solid polystyrene and deuterated polystyrene light output response to fast neutrons.

    PubMed

    Simpson, R; Danly, C; Glebov, V Yu; Hurlbut, C; Merrill, F E; Volegov, P L; Wilde, C

    2016-04-01

    The Neutron Imaging System has proven to be an important diagnostic in studying DT implosion characteristics at the National Ignition Facility. The current system depends on a polystyrene scintillating fiber array, which detects fusion neutrons born in the DT hotspot as well as neutrons that have scattered to lower energies in the surrounding cold fuel. Increasing neutron yields at NIF, as well as a desire to resolve three-dimensional information about the fuel assembly, have provided the impetus to build and install two additional next-generation neutron imaging systems. We are currently investigating a novel neutron imaging system that will utilize a deuterated polystyrene (CD) fiber array instead of standard hydrogen-based polystyrene (CH). Studies of deuterated xylene or deuterated benzene liquid scintillator show an improvement in imaging resolution by a factor of two [L. Disdier et al., Rev. Sci. Instrum. 75, 2134 (2004)], but also a reduction in light output [V. Bildstein et al., Nucl. Instrum. Methods Phys. Res., Sect. A 729, 188 (2013); M. I. Ojaruega, Ph.D. thesis, University of Michigan, 2009; M. T. Febbraro, Ph.D. thesis, University of Michigan, 2014] as compared to standard plastic. Tests of the relative light output of deuterated polystyrene and standard polystyrene were completed using 14 MeV fusion neutrons generated through implosions of deuterium-tritium filled capsules at the OMEGA laser facility. In addition, we collected data of the relative response of these two scintillators to a wide energy range of neutrons (1-800 MeV) at the Weapons Neutrons Research Facility. Results of these measurements are presented.

  2. Solid polystyrene and deuterated polystyrene light output response to fast neutrons

    NASA Astrophysics Data System (ADS)

    Simpson, R.; Danly, C.; Glebov, V. Yu.; Hurlbut, C.; Merrill, F. E.; Volegov, P. L.; Wilde, C.

    2016-04-01

    The Neutron Imaging System has proven to be an important diagnostic in studying DT implosion characteristics at the National Ignition Facility. The current system depends on a polystyrene scintillating fiber array, which detects fusion neutrons born in the DT hotspot as well as neutrons that have scattered to lower energies in the surrounding cold fuel. Increasing neutron yields at NIF, as well as a desire to resolve three-dimensional information about the fuel assembly, have provided the impetus to build and install two additional next-generation neutron imaging systems. We are currently investigating a novel neutron imaging system that will utilize a deuterated polystyrene (CD) fiber array instead of standard hydrogen-based polystyrene (CH). Studies of deuterated xylene or deuterated benzene liquid scintillator show an improvement in imaging resolution by a factor of two [L. Disdier et al., Rev. Sci. Instrum. 75, 2134 (2004)], but also a reduction in light output [V. Bildstein et al., Nucl. Instrum. Methods Phys. Res., Sect. A 729, 188 (2013); M. I. Ojaruega, Ph.D. thesis, University of Michigan, 2009; M. T. Febbraro, Ph.D. thesis, University of Michigan, 2014] as compared to standard plastic. Tests of the relative light output of deuterated polystyrene and standard polystyrene were completed using 14 MeV fusion neutrons generated through implosions of deuterium-tritium filled capsules at the OMEGA laser facility. In addition, we collected data of the relative response of these two scintillators to a wide energy range of neutrons (1-800 MeV) at the Weapons Neutrons Research Facility. Results of these measurements are presented.

  3. Fluorescence imaging of microbe-containing particles shot from a two-stage Light-gas gun into an aerogel

    NASA Astrophysics Data System (ADS)

    Kawaguchi, Yuko; Sugino, Tomohiro; Tabata, Makoto; Okudaira, Kyoko; Imai, Eichi; Yano, Hajime; Hasegawa, Sunao; Hashimoto, Hirofumi; Yabuta, Hikaru; Kobayashi, Kensei; Kawai, Hideyuki; Mita, Hajime; Yokobori, Shin-ichi; Yamagishi, Akihiko

    2014-02-01

    We have proposed an experiment (the Tanpopo mission) to capture microbes on the Japan Experimental Module of the International Space Station. An ultra low-density silica aerogel will be exposed to space for more than 1 year. After retrieving the aerogel, particle tracks and particles found in it will be visualized by fluorescence microscopy after staining it with a DNA-specific fluorescence dye. In preparation for this study, we simulated particle trapping in an aerogel so that methods could be developed to visualize the particles and their tracks. During the Tanpopo mission, particles that have an orbital velocity of ~8 km/s are expected to collide with the aerogel. To simulate these collisions, we shot Deinococcus radiodurans-containing Lucentite particles into the aerogel from a two-stage light-gas gun (acceleration 4.2 km/s). The shapes of the captured particles, and their tracks and entrance holes were recorded with a microscope/camera system for further analysis. The size distribution of the captured particles was smaller than the original distribution, suggesting that the particles had fragmented. We were able to distinguish between microbial DNA and inorganic compounds after staining the aerogel with the DNA-specific fluorescence dye SYBR green I as the fluorescence of the stained DNA and the autofluorescence of the inorganic particles decay at different rates. The developed methods are suitable to determine if microbes exist at the International Space Station altitude.

  4. Towards nano-optical tweezers with graphene plasmons: Numerical investigation of trapping 10-nm particles with mid-infrared light

    PubMed Central

    Zhang, Jianfa; Liu, Wenbin; Zhu, Zhihong; Yuan, Xiaodong; Qin, Shiqiao

    2016-01-01

    Graphene plasmons are rapidly emerging as a versatile platform for manipulating light at the deep subwavelength scale. Here we show numerically that strong optical near-field forces can be generated under the illumination of mid-IR light when dielectric nanoparticles are located in the vicinity of a nanostructured graphene film. These near-field forces are attributed to the excitation of the graphene’s plasmonic mode. The optical forces can generate an efficient optical trapping potential for a 10-nm-diameter dielectric particle when the light intensity is only about about 4.4 mW/μm2 and provide possibilities for a new type of plasmonic nano-tweezers. Graphene plasmonic tweezers can be potentially exploited for optical manipulation of nanometric biomolecules and particles. Moreover, the optical trapping/tweezing can be combined with biosensing and provide a versatile platform for studing biology and chemistry with mid-IR light. PMID:27905527

  5. Towards nano-optical tweezers with graphene plasmons: Numerical investigation of trapping 10-nm particles with mid-infrared light

    NASA Astrophysics Data System (ADS)

    Zhang, Jianfa; Liu, Wenbin; Zhu, Zhihong; Yuan, Xiaodong; Qin, Shiqiao

    2016-12-01

    Graphene plasmons are rapidly emerging as a versatile platform for manipulating light at the deep subwavelength scale. Here we show numerically that strong optical near-field forces can be generated under the illumination of mid-IR light when dielectric nanoparticles are located in the vicinity of a nanostructured graphene film. These near-field forces are attributed to the excitation of the graphene’s plasmonic mode. The optical forces can generate an efficient optical trapping potential for a 10-nm-diameter dielectric particle when the light intensity is only about about 4.4 mW/μm2 and provide possibilities for a new type of plasmonic nano-tweezers. Graphene plasmonic tweezers can be potentially exploited for optical manipulation of nanometric biomolecules and particles. Moreover, the optical trapping/tweezing can be combined with biosensing and provide a versatile platform for studing biology and chemistry with mid-IR light.

  6. Fast fabrication of copper nanowire transparent electrodes by a high intensity pulsed light sintering technique in air.

    PubMed

    Ding, Su; Jiu, Jinting; Tian, Yanhong; Sugahara, Tohru; Nagao, Shijo; Suganuma, Katsuaki

    2015-12-14

    Copper nanowire transparent electrodes have received increasing interest due to the low price and nearly equal electrical conductivity compared with other TEs based on silver nanowires and indium tin oxide (ITO). However, a post-treatment at high temperature in an inert atmosphere or a vacuum environment was necessary to improve the conductivity of Cu NW TEs due to the easy oxidation of copper in air atmosphere, which greatly cancelled out the low price advantage of Cu NWs. Here, a high intensity pulsed light technique was introduced to sinter and simultaneously deoxygenate these Cu NWs into a highly conductive network at room temperature in air. The strong light absorption capacity of Cu NWs enabled the welding of the nanowires at contact spots, as well as the removal of the thin layer of residual organic compounds, oxides and hydroxide of copper even in air. The Cu NW TE with a sheet resistance of 22.9 Ohm sq(-1) and a transparency of 81.8% at 550 nm has been successfully fabricated within only 6 milliseconds exposure treatment, which is superior to other films treated at high temperature in a hydrogen atmosphere. The HIPL process was simple, convenient and fast to fabricate easily oxidized Cu NW TEs in large scale in an air atmosphere, which will largely extend the application of cheap Cu NW TEs.

  7. Cross-Platform Graphical User Interface with fast 3-D Rendering for Particle-in-Cell Simulations

    NASA Astrophysics Data System (ADS)

    Bruhwiler, David; Luetkemeyer, Kelly; Cary, John

    1999-11-01

    The Graphical User Interface (GUI) for XOOPIC (X11-based Object-Oriented Particle-in-Cell) is being ported to Qt, a cross-platform C++ windowing toolkit, thus permitting the code to run on PC's running both Windows 95/98/NT and Linux, as well as all commercial Unix platforms. All 3-D graphics will be handled through OpenGL, the cross-platform standard for fast 3-D rendering. The use of object-oriented design (OOD) techniques keeps the GUI/physics interface clean, and minimizes the impact of GUI development on the physics code. OOD also improves the maintainability and extensibility of large scientific simulation codes, while allowing for cross-platform portability and ready interchange of individual algorithms or entire physics kernels. Planned new GUI features include interactive modifications of the simulation parameters, including generation of a slowly-varying mesh and automatic updating of a corresponding input file. Improved modeling of high-power microwave tubes is one of the primary applications being targeted by this project.

  8. Separation of peptides on superficially porous particle based macrocyclic glycopeptide liquid chromatography stationary phases: consideration of fast separations.

    PubMed

    Wimalasinghe, Rasangi M; Breitbach, Zachary S; Lee, Jauh T; Armstrong, Daniel W

    2017-03-01

    Macrocyclic glycopeptide based liquid chromatography stationary phases are known for their highly selective peptide separations. Fast and ultrafast (t R < 1 min) high-efficiency separations were achieved with superficially porous particle (SPP)-based stationary phases. Separations of pharmaceutically important classes of peptides such as enkephalins and bradykinins have been achieved in less than 5 min in isocratic elution modes. Selectivity for peptides structurally similar to one another was increased with use of teicoplanin-based stationary phases compared with commercial C18 stationary phases. Ultrafast isocratic separations of structurally related peptides were achieved with teicoplanin- and vancomycin-based short SPP columns. Acidic mobile phases produced better separations. Ammonium formate was the optimal mobile phase buffer additive. Use of an appropriate combination of a macrocyclic glycopeptide stationary phase and a mobile phase permits faster and more electrospray ionization mass spectrometry compatible isocratic separations than previous gradient approaches. The tryptic peptide separation characteristics of the teicoplanin stationary phase are demonstrated. Additionally, compared with commercial C18 stationary phases, teicoplanin showed tryptic peptide separations with different selectivities. Graphical Abstract Ultrafast separation of enkephalin peptide epimers.

  9. A fast, ultra-low and frequency-scalable power consumption, 10-bit SAR ADC for particle physics detectors

    NASA Astrophysics Data System (ADS)

    Firlej, M.; Fiutowski, T.; Idzik, M.; Kulis, S.; Moron, J.; Swientek, K.

    2015-11-01

    The design and measurements results of a fast 10-bit SAR ADC with ultra-low and scalable with frequency power consumption, developed for readout systems for detectors at future particle physics colliders (ILC, CLIC, LHC Upgrade), are described. A prototype ASIC was designed and fabricated in 130 nm CMOS technology and a wide spectrum of static (INLlesssim0.5 LSB, DNLlesssim0.5 LSB) and dynamic (SINAD ~58 dB, ENOB~9.3) measurements was performed to study and quantify the ADC performance. The ADC works in wide 10 kS/s - 40 MS/s sampling frequency range, covering more than three orders of magnitude. In most of the range the power consumption scales linearly with sampling rate with a factor of about 22 μW/MS/s. A dynamic and asynchronous internal logic makes the ADC very well suited not only for commonly used synchronous sampling but also for applications with asynchronous sampling and/or the ones requiring power cycling, like the experiments at future linear collider (ILC/CLIC). The ADC layout is drawn with a small pitch of 146 μm to facilitate multi-channel integration. The obtained figure of Merit is in range 32-37 fJ/conversion for sampling frequencies 10-40 MS/s, placing the ADC among the best State of the Art designs with similar technology and specifications.

  10. Particle simulations of mode conversion between slow mode and fast mode in lower hybrid range of frequencies

    SciTech Connect

    Jia, Guozhang; Xiang, Nong; Huang, Yueheng; Wang, Xueyi; Lin, Yu

    2016-01-15

    The propagation and mode conversion of lower hybrid waves in an inhomogeneous plasma are investigated by using the nonlinear δf algorithm in a two-dimensional particle-in-cell simulation code based on the gyrokinetic electron and fully kinetic ion (GeFi) scheme [Lin et al., Plasma Phys. Controlled Fusion 47, 657 (2005)]. The characteristics of the simulated waves, such as wavelength, frequency, phase, and group velocities, agree well with the linear theoretical analysis. It is shown that a significant reflection component emerges in the conversion process between the slow mode and the fast mode when the scale length of the density variation is comparable to the local wavelength. The dependences of the reflection coefficient on the scale length of the density variation are compared with the results based on the linear full wave model for cold plasmas. It is indicated that the mode conversion for the waves with a frequency of 2.45 GHz (ω ∼ 3ω{sub LH}, where ω{sub LH} represents the lower hybrid resonance) and within Tokamak relevant amplitudes can be well described in the linear scheme. As the frequency decreases, the modification due to the nonlinear term becomes important. For the low-frequency waves (ω ∼ 1.3ω{sub LH}), the generations of the high harmonic modes and sidebands through nonlinear mode-mode coupling provide new power channels and thus could reduce the reflection significantly.

  11. Particle simulations of mode conversion between slow mode and fast mode in lower hybrid range of frequencies

    NASA Astrophysics Data System (ADS)

    Jia, Guozhang; Xiang, Nong; Wang, Xueyi; Huang, Yueheng; Lin, Yu

    2016-01-01

    The propagation and mode conversion of lower hybrid waves in an inhomogeneous plasma are investigated by using the nonlinear δf algorithm in a two-dimensional particle-in-cell simulation code based on the gyrokinetic electron and fully kinetic ion (GeFi) scheme [Lin et al., Plasma Phys. Controlled Fusion 47, 657 (2005)]. The characteristics of the simulated waves, such as wavelength, frequency, phase, and group velocities, agree well with the linear theoretical analysis. It is shown that a significant reflection component emerges in the conversion process between the slow mode and the fast mode when the scale length of the density variation is comparable to the local wavelength. The dependences of the reflection coefficient on the scale length of the density variation are compared with the results based on the linear full wave model for cold plasmas. It is indicated that the mode conversion for the waves with a frequency of 2.45 GHz (ω ˜ 3ωLH, where ωLH represents the lower hybrid resonance) and within Tokamak relevant amplitudes can be well described in the linear scheme. As the frequency decreases, the modification due to the nonlinear term becomes important. For the low-frequency waves (ω ˜ 1.3ωLH), the generations of the high harmonic modes and sidebands through nonlinear mode-mode coupling provide new power channels and thus could reduce the reflection significantly.

  12. Fast chiral separation of drugs using columns packed with sub-2 microm particles and ultra-high pressure.

    PubMed

    Guillarme, Davy; Bonvin, Gregoire; Badoud, Flavia; Schappler, Julie; Rudaz, Serge; Veuthey, Jean-Luc

    2010-03-01

    The use of columns packed with sub-2 microm particles in liquid chromatography with very high pressure conditions (known as UHPLC) was investigated for the fast enantioseparation of drugs. Two different procedures were evaluated and compared using amphetamine derivatives and beta-blockers as model compounds. In one case, cyclodextrins (CD) were directly added to the mobile phase and chiral separations were carried out in less than 5 min. However, this strategy suffered from several drawbacks linked to column lifetime and low chromatographic efficiencies. In the other case, the analysis of enantiomers was carried out after a derivatization procedure using two different reagents, 2,3,4-tri-O-acetyl-alpha-D-arabinopyranosyl isothiocyanate (AITC) and N-alpha-(2,4-dinitro-5-fluorophenyl)-L-alaninamide (Marfey's reagent). Separation of several amphetamine derivatives contained within the same sample was achieved in 2-5 min with high efficiency and selectivity. The proposed approach was also successfully applied to the enantiomeric purity determination of (+)-(S)-amphetamine and (+)-(S)-methamphetamine. Similar results were obtained with beta-blockers, and the separation of 10 enantiomers was carried out in less than 3 min, whereas the individual separation of several beta-blocker enantiomers was performed in 1 min or less.

  13. LIGHT PRESSURE: Theoretical study of the light pressure force acting on a spherical dielectric particle of an arbitrary size in the interference field of two plane monochromatic electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Guzatov, D. V.; Gaida, L. S.; Afanas'ev, Anatolii A.

    2008-12-01

    The light pressure force acting on a spherical dielectric particle in the interference field of two plane monochromatic electromagnetic waves is studied in detail for different particle radii and angles of incidence of waves.

  14. A novel method for fast imaging of brain function, non-invasively, with light

    NASA Astrophysics Data System (ADS)

    Chance, Britton; Anday, Endla; Nioka, Shoko; Zhou, Shuoming; Hong, Long; Worden, Katherine; Li, C.; Murray, T.; Ovetsky, Y.; Pidikiti, D.; Thomas, R.

    1998-05-01

    Imaging of the human body by any non-invasive technique has been an appropriate goal of physics and medicine, and great success has been obtained with both Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) in brain imaging. Non-imaging responses to functional activation using near infrared spectroscopy of brain (fNIR) obtained in 1993 (Chance, et al. [1]) and in 1994 (Tamura, et al. [2]) are now complemented with images of pre-frontal and parietal stimulation in adults and pre-term neonates in this communication (see also [3]). Prior studies used continuous [4], pulsed [3] or modulated [5] light. The amplitude and phase cancellation of optical patterns as demonstrated for single source detector pairs affords remarkable sensitivity of small object detection in model systems [6]. The methods have now been elaborated with multiple source detector combinations (nine sources, four detectors). Using simple back projection algorithms it is now possible to image sensorimotor and cognitive activation of adult and pre- and full-term neonate human brain function in times < 30 sec and with two dimensional resolutions of < 1 cm in two dimensional displays. The method can be used in evaluation of adult and neonatal cerebral dysfunction in a simple, portable and affordable method that does not require immobilization, as contrasted to MRI and PET.

  15. Fast and efficient synthesis of microporous polymer nanomembranes via light-induced click reaction

    PubMed Central

    An, Qi; Hassan, Youssef; Yan, Xiaotong; Krolla-Sidenstein, Peter; Mohammed, Tawheed; Lang, Mathias; Bräse, Stefan

    2017-01-01

    Conjugated microporous polymers (CMPs) are materials of low density and high intrinsic porosity. This is due to the use of rigid building blocks consisting only of lightweight elements. These materials are usually stable up to temperatures of 400 °C and are chemically inert, since the networks are highly crosslinked via strong covalent bonds, making them ideal candidates for demanding applications in hostile environments. However, the high stability and chemical inertness pose problems in the processing of the CMP materials and their integration in functional devices. Especially the application of these materials for membrane separation has been limited due to their insoluble nature when synthesized as bulk material. To make full use of the beneficial properties of CMPs for membrane applications, their synthesis and functionalization on surfaces become increasingly important. In this respect, we recently introduced the solid liquid interfacial layer-by-layer (LbL) synthesis of CMP-nanomembranes via Cu catalyzed azide–alkyne cycloaddition (CuAAC). However, this process featured very long reaction times and limited scalability. Herein we present the synthesis of surface grown CMP thin films and nanomembranes via light induced thiol–yne click reaction. Using this reaction, we could greatly enhance the CMP nanomembrane synthesis and further broaden the variability of the LbL approach.

  16. A comparison between mammalian and avian fast skeletal muscle alkali myosin light chain genes: regulatory implications.

    PubMed Central

    Daubas, P; Robert, B; Garner, I; Buckingham, M

    1985-01-01

    A single locus in the mouse, rat and chicken encodes both alkali myosin light chains, MLC1F and MLC3F. This gene has two distinct promoters and gives rise to two different primary transcripts, which are processed by alternative and different modes of splicing to form MLC1F and MLC3F mRNAs. The MLC1F/MLC3F gene is very similar between mouse, rat and chicken, in terms of its overall structure, the length and location of the introns, and the splice site consensus sequences. Nucleotide sequences of coding regions are very conserved but 3' and 5' non coding regions of the mRNAs have diverged. In the MLC1F promoter regions, several blocks of nucleotides are highly conserved (more than 70% homology), especially a sequence of about 70 nucleotides, located between positions -80 and -150 relative to the Cap site. Conserved blocks of homology are also found in the MLC3F promoter regions, although the common sequences are shorter. The presence of such highly conserved nucleotide sequences in the 5' flanking regions suggests that these sequences are functionally important in initiation of transcription and regulation of expression of this complex gene. Primer extension experiments indicate multiple cap sites for MLC3F mRNA. Images PMID:4022770

  17. High-throughput spatial light modulation two-photon microscopy for fast functional imaging

    PubMed Central

    Pozzi, Paolo; Gandolfi, Daniela; Tognolina, Marialuisa; Chirico, Giuseppe; Mapelli, Jonathan; D’Angelo, Egidio

    2015-01-01

    Abstract. The optical monitoring of multiple single neuron activities requires high-throughput parallel acquisition of signals at millisecond temporal resolution. To this aim, holographic two-photon microscopy (2PM) based on spatial light modulators (SLMs) has been developed in combination with standard laser scanning microscopes. This requires complex coordinate transformations for the generation of holographic patterns illuminating the points of interest. We present a simpler and fully digital setup (SLM-2PM) which collects three-dimensional two-photon images by only exploiting the SLM. This configuration leads to an accurate placement of laser beamlets over small focal volumes, eliminating mechanically moving parts and making the system stable over long acquisition times. Fluorescence signals are diffraction limited and are acquired through a pixelated detector, setting the actual limit to the acquisition rate. High-resolution structural images were acquired by raster-scanning the sample with a regular grid of excitation focal volumes. These images allowed the selection of the structures to be further investigated through an interactive operator-guided selection process. Functional signals were collected by illuminating all the preselected points with a single hologram. This process is exemplified for high-speed (up to 1 kHz) two-photon calcium imaging on acute cerebellar slices. PMID:26157984

  18. An inverse light scattering technique for morphological characterization of irregular particles based on the Gaussian-random-sphere model.

    PubMed

    Hajihashemi, M Reza; Jiang, Huabei

    2012-06-01

    The Gaussian-random-sphere model is employed for morphological characterization of nonspherical, irregular particles using an inverse light scattering technique. The synthetic measurement data consist of reduced scattering spectra caused by an aggregate of irregular particles randomly oriented in turbid media and are generated using the discrete dipole approximation. The proposed method simultaneously retrieves the concentration and shape parameters of particles using the data collected at multiple wavelengths. The performance of the inverse algorithm is tested using noise-corrupted data, in which up to 50% noise may be added to the observed scattering spectra.

  19. Search for light neutral scalar and pseudoscalar particles in pFe interactions at 70 GeV

    NASA Astrophysics Data System (ADS)

    Anikeev, V. B.; Bamburov, N. S.; Bozhko, N. I.

    A search has been performed for weakly interacting neutral light scalar and pseudoscalar particles in a proton beam dump experiment. No positive signal is observed. Limits on the mass and lifetime of these particles are set in the frame of the Standard Model and its minimal supersymmetric extension. The Higgs particle of the SU(2L) x U(1) Standard Model is excluded for masses in the range 1 MeV less than m less than 80 MeV at 95 percent CL. Limits on the Peccei Quinn like axions are also derived.

  20. Dynamics of statistically confident particle sizes and concentrations in blood plasma obtained by the dynamic light scattering method

    NASA Astrophysics Data System (ADS)

    Chaikov, Leonid L.; Kirichenko, Marina N.; Krivokhizha, Svetlana V.; Zaritskiy, Alexander R.

    2015-05-01

    The work is devoted to the study of sizes and concentrations of proteins, and their aggregates in blood plasma samples, using static and dynamic light scattering methods. A new approach is proposed based on multiple repetition of measurements of intensity size distribution and on counting the number of registrations of different sizes, which made it possible to obtain statistically confident particle sizes and concentrations in the blood plasma. It was revealed that statistically confident particle sizes in the blood plasma were stable during 30 h of observations, whereas the concentrations of particles of different sizes varied as a result of redistribution of material between them owing to the protein degradation processes.

  1. Dynamics of statistically confident particle sizes and concentrations in blood plasma obtained by the dynamic light scattering method.

    PubMed

    Chaikov, Leonid L; Kirichenko, Marina N; Krivokhizha, Svetlana V; Zaritskiy, Alexander R

    2015-05-01

    The work is devoted to the study of sizes and concentrations of proteins, and their aggregates in blood plasma samples, using static and dynamic light scattering methods. A new approach is proposed based on multiple repetition of measurements of intensity size distribution and on counting the number of registrations of different sizes, which made it possible to obtain statistically confident particle sizes and concentrations in the blood plasma. It was revealed that statistically confident particle sizes in the blood plasma were stable during 30 h of observations, whereas the concentrations of particles of different sizes varied as a result of redistribution of material between them owing to the protein degradation processes.

  2. Fast and effective inactivation of Bacillus atrophaeus endospores using light-activated derivatives of vitamin B2.

    PubMed

    Eichner, Anja; Gollmer, Anita; Späth, Andreas; Bäumler, Wolfgang; Regensburger, Johannes; König, Burkhard; Maisch, Tim

    2015-02-01

    Highly resistant endospores may cause severe problems in medicine as well as in the food and packaging industries. We found that bacterial endospores can be inactivated quickly with reactive oxygen species (ROS) that were generated by a new generation of flavin photosensitizers. Flavins like the natural compound vitamin B2 are already known to produce ROS but they show a poor antimicrobial photodynamic killing efficacy due to the lack of positive charges. Therefore we synthesized new flavin photosensitizers that have one (FLASH-01a) or eight (FLASH-07a) positive charges and can hence attach to the negatively charged surface of endospores. In this study we used standardized Bacillus atrophaeus endospores (ATCC 9372) as a biological surrogate model for a proof-of-concept study of photodynamic inactivation experiments using FLASH-01a and FLASH-07a. After incubation of spores with different flavin concentrations, the flavin derivatives were excited with blue light at a light dose of 70 J cm(-2). The inactivation of spores was investigated either in suspension or after attachment to polyethylene terephthalate (PET) surfaces. Incubation of spores suspended in Millipore water with 4 mM FLASH-01a for 10 seconds and irradiation with blue light for 10 seconds caused a biologically relevant decrease of spore survival of 3.5 log10 orders. Using FLASH-07a under the same conditions we achieved a decrease of 4.4 log10 orders. Immobilized spores on PET surfaces were efficiently killed with 7.0 log10 orders using 8 mM FLASH-07a. The total treatment time (incubation + irradiation) was as short as 20 seconds. The results of this study show evidence that endospores can be fastly and effectively inactivated with new generations of flavin photosensitizers that may be useful for industrial or medical applications in the future.

  3. Light induced heterogeneous ozone processing on the pesticides adsorbed on silica particles

    NASA Astrophysics Data System (ADS)

    Socorro, J.; Désert, M.; Quivet, E.; Gligorovski, S.; Wortham, H.

    2013-12-01

    In France, in 2010, the sales of pesticides reached 1.8 billion euros for 61 900 tons of active ingredients, positioning France as a first European consumer of pesticides, as reported by the European Crop Protection Association. About 19 million hectares of crops are sprayed annually with pesticides, i.e., 35% of the total surface area of France. This corresponds to an average pesticide dose of 3.2 kg ha-1. The consumption of herbicide and fungicide is favoured in comparison to the use of insecticides in France and the other European countries, as well. The partitioning of pesticides between the gas and particulate phases influences the atmospheric fate of these compounds such as their photo-chemical degradation. There is much uncertainty concerning the behavior of the pesticides in the atmosphere. Especially, there is a gap of knowledge concerning the degradation of the pesticides induced by heterogeneous reactions in absence and especially in presence of solar light. Considering that most of the pesticides currently used are semi-volatile, it is of crucial importance to investigate the heterogeneous reactivity of particulate pesticides with light and with atmospheric oxidants such as ozone and OH radical. The aim of the present work is to evaluate the light induced heterogeneous ozonation of suspended pesticide particles. 8 pesticides (cyprodinil, deltamethrin, difenoconazole, fipronil, oxadiazon, pendimethalin, permethrin and tetraconazole) were chosen for their physico-chemical properties and their concentration levels in the PACA (Région Provence-Alpes-Côte d'Azur) region, France. Silica particles with well-known properties were chosen as model particles of atmospheric relevance. Kinetic rate constants were determined to allow estimate the atmospheric lifetimes relating to ozone. The rate constants were determined as follows: k = (6.6 × 0.2) 10-19, (7.2 × 0.3) 10-19, (5.1 × 0.5) 10-19, (3.9 × 0.3) 10-19 [cm3 molecules-1 s-1] for Cyprodinil

  4. An efficient visible-light photocatalyst prepared by modifying AgBr particles with a small amount of activated carbon

    SciTech Connect

    Wang, Desong Zhao, Mangmang; Luo, Qingzhi; Yin, Rong; An, Jing; Li, Xueyan

    2016-04-15

    Highlights: • An efficient visible-light photocatalyst was prepared by modifying AgBr particles. • A small amount of activated carbon was used to modify AgBr particles. • The modified AgBr exhibited improved visible-light photocatalytic performances. - Abstract: An efficient visible-light photocatalyst was successfully prepared by modifying AgBr particles with a small amount of activated carbon (AC) via a simple chemical precipitation approach. The AC/AgBr composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, UV–vis diffuse reflection spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy. The photocatalytic performances of the AC/AgBr composite were investigated by evaluating photodegradation of methyl orange (MO) and phenol under visible light irradiation, and the effects of the AC content in the composite, concentrations of AC/AgBr composite and MO, carrier scavengers on MO photodegradation rate were systematically investigated. The results indicated that the modification of AC can hardly change the crystalline and crystal size of AgBr particles, while significantly improve their specific surface areas, visible-light absorption and separation efficiency of photogenerated electron–hole pairs. Compared with pure AgBr, the AC/AgBr composite exhibited drastically enhanced visible-light photocatalytic activity and stability. The photogenerated electrons and holes, hydroxyl radicals are responsible to the photodegradation of organic pollutants, and the photogenerated holes are the main active species. On the basis of the results and the properties of AC and AgBr, the visible-light photocatalytic mechanism of the AC/AgBr composite was discussed.

  5. A Study of the Jacobi Shape Transition in Light, Fast Rotating Nuclei with the EUROBALL IV, HECTOR and EUCLIDES Arrays

    SciTech Connect

    Maj, A.; Kmiecik, M.; Brekiesz, M.; Grebosz, J.; Meczynski, W.; Styczen, J.; Zieblinski, M.; Zuber, K.; Bracco, A.; Camera, F.; Benzoni, G.; Million, B.; Blasi, N.; Brambilla, S.; Leoni, S.; Pignanelli, M.; Wieland, O.; Airoldi, A.; Herskind, B.; Bednarczyk, P.

    2004-02-27

    The high-energy and discrete {gamma}-ray spectra, as well as the charged particle angular distribution have been measured in the reaction 105 MeV 18O+28Si using the EUROBALL IV, HECTOR and EUCLIDES arrays in order to investigate the predicted Jacobi shape transition in light nuclei. A comparison of the GDR line shape data with the predictions of the thermal shape fluctuation model, based on the most recent rotating liquid drop LSD calculations, shows evidence for such Jacobi shape transition in hot, rapidly rotating 46Ti. The found narrow low-energy component in the GDR line shape is interpreted as the consequence both of the elongated shape and of the Coriolis effect.

  6. A Study of the Jacobi Shape Transition in Light, Fast Rotating Nuclei with the EUROBALL IV, HECTOR and EUCLIDES Arrays

    NASA Astrophysics Data System (ADS)

    Maj, A.; Kmiecik, M.; Brekiesz, M.; Grebosz, J.; Meczyński, W.; Styczeń, J.; Ziebliński, M.; Zuber, K.; Bracco, A.; Camera, F.; Benzoni, G.; Million, B.; Blasi, N.; Brambilla, S.; Leoni, S.; Pignanelli, M.; Wieland, O.; Airoldi, A.; Herskind, B.; Bednarczyk, P.; Curien, D.; Farnea, E.; de Angelis, G.; Napoli, D. R.; Nyberg, J.; Kicińska-Habior, M.; Petrache, C. M.; Petrache, D.; Dubray, N.; Dudek, J.; Pomorski, K.

    2004-02-01

    The high-energy and discrete γ-ray spectra, as well as the charged particle angular distribution have been measured in the reaction 105 MeV 18O+28Si using the EUROBALL IV, HECTOR and EUCLIDES arrays in order to investigate the predicted Jacobi shape transition in light nuclei. A comparison of the GDR line shape data with the predictions of the thermal shape fluctuation model, based on the most recent rotating liquid drop LSD calculations, shows evidence for such Jacobi shape transition in hot, rapidly rotating 46Ti. The found narrow low-energy component in the GDR line shape is interpreted as the consequence both of the elongated shape and of the Coriolis effect.

  7. Evaluation of observable phase space by fast ion loss detector by calculating particle orbits in consideration of plasma facing components and three dimensional magnetic field.

    PubMed

    Shinohara, Kouji; Kim, Junghee; Kim, Jun Young; Rhee, Tongnyeol

    2016-11-01

    The orbits of lost ions can be calculated from the information obtained by a fast ion loss detector (FILD). The orbits suggest a source of the lost fast ions in a phase space. However, it is not obvious whether an observable set of orbits, or phase space, of a FILD appropriately covers the region of interest to be investigated since the observable phase space can be affected by plasma facing components (PFCs) and a magnetic configuration. A tool has been developed to evaluate the observable phase space of FILD diagnostic by calculating particle orbits by taking the PFCs and 3D magnetic field into account.

  8. Effect of particle size on the photocatalytic activity of BiNbO4 under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Adhikari, S. P.; Lachgar, A.

    2016-10-01

    Numerous attempts have focused on developing more efficient visible-light active photocatalysts. Bismuth niobate (BiNbO4) was reported as a potential candidate for photocatalytic water splitting and for the degradation of organic molecule under visible-light irradiation because of its small band gap and appropriate band positions. Here, three BiNbO4 samples with different, uniform particle sizes were synthesized. The effect of BiNbO4 particle size on its photocatalytic activity was studied by using the reduction of 4-nitroaniline as model reaction. Results show that the photocatalytic degradation of 4-nitroaniline varies systematically with the change in particle size and surface areas. To better understand the correlation between structure, composition, morphology, and optical properties, the catalysts were characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), Powder X-ray diffraction (PXRD), Brunauer-Emmett-Teller (BET) surface area, UV-vis diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL).

  9. Non-universal bound states of two identical heavy fermions and one light particle

    NASA Astrophysics Data System (ADS)

    Safavi, Arghavan; Rittenhouse, Seth; Blume, Dorte; Sadeghpour, Hossein

    2013-05-01

    We study a system of two identical heavy fermions of mass M and light particle of mass m. The interspecies interaction is modeled using a short-range two-body potential with positive s-wave scattering length. We impose a short-range boundary condition on the logarithmic derivative of the hyperradial wavefunction and show that, in the regime where Efimov states are absent, a non-universal three-body state ``cuts through'' the universal three-body states previously described by Kartavtsev and Malykh [O. I. Kartavtsev and A. V. Malykh, J. Phys. B 40, 1429 (2007)]. We study the effect of the non-universal state on the behavior of the universal states and use a simple quantum defect theory, utilizing hyperspherical coordinates, to explain the existence of the non-universal state. An empirical two-state model is employed to quantify the coupling of the non-universal state to the universal states. This work was supported by NSF through a grant for the Institute for Theoretical Atomic, Molecular and Optical Physics at Harvard University and Smithsonian Astrophysical Observatory and through grant PHY-1205443.

  10. Light-absorbing particles in snow and ice: Measurement and modeling of climatic and hydrological impact

    NASA Astrophysics Data System (ADS)

    Qian, Yun; Yasunari, Teppei J.; Doherty, Sarah J.; Flanner, Mark G.; Lau, William K. M.; Ming, Jing; Wang, Hailong; Wang, Mo; Warren, Stephen G.; Zhang, Rudong

    2015-01-01

    Light absorbing particles (LAP, e.g., black carbon, brown carbon, and dust) influence water and energy budgets of the atmosphere and snowpack in multiple ways. In addition to their effects associated with atmospheric heating by absorption of solar radiation and interactions with clouds, LAP in snow on land and ice can reduce the surface reflectance (a.k.a., surface darkening), which is likely to accelerate the snow aging process and further reduces snow albedo and increases the speed of snowpack melt. LAP in snow and ice (LAPSI) has been identified as one of major forcings affecting climate change, e.g. in the fourth and fifth assessment reports of IPCC. However, the uncertainty level in quantifying this effect remains very high. In this review paper, we document various technical methods of measuring LAPSI and review the progress made in measuring the LAPSI in Arctic, Tibetan Plateau and other mid-latitude regions. We also report the progress in modeling the mass concentrations, albedo reduction, radiative forcing, and climatic and hydrological impact of LAPSI at global and regional scales. Finally we identify some research needs for reducing the uncertainties in the impact of LAPSI on global and regional climate and the hydrological cycle.

  11. Light-absorbing Particles in Snow and Ice: Measurement and Modeling of Climatic and Hydrological Impact

    SciTech Connect

    Qian, Yun; Yasunari, Teppei J.; Doherty, Sarah J.; Flanner, M. G.; Lau, William K.; Ming, J.; Wang, Hailong; Wang, Mo; Warren, Stephen G.; Zhang, Rudong

    2015-01-01

    Light absorbing particles (LAP, e.g., black carbon, brown carbon, and dust) influence water and energy budgets of the atmosphere and snowpack in multiple ways. In addition to their effects associated with atmospheric heating by absorption of solar radiation and interactions with clouds, LAP in snow on land and ice can reduce the surface reflectance (a.k.a., surface darkening), which is likely to accelerate the snow aging process and further reduces snow albedo and increases the speed of snowpack melt. LAP in snow and ice (LAPSI) has been identified as one of major forcings affecting climate change, e.g. in the fourth and fifth assessment reports of IPCC. However, the uncertainty level in quantifying this effect remains very high. In this review paper, we document various technical methods of measuring LAPSI and review the progress made in measuring the LAPSI in Arctic, Tibetan Plateau and other mid-latitude regions. We also report the progress in modeling the mass concentrations, albedo reduction, radiative forcing, andclimatic and hydrological impact of LAPSI at global and regional scales. Finally we identify some research needs for reducing the uncertainties in the impact of LAPSI on global and regional climate and the hydrological cycle.

  12. Particle emission in the light heavy-ion fusion reactions: 14N, 16,18O+ 12C

    NASA Astrophysics Data System (ADS)

    Carlin Filho, N.; Coimbra, M. M.; Acquadro, J. C.; Liguori Neto, R.; Szanto, E. M.; Farrelly-Pessoa, E.; Szanto de Toledo, A.

    1985-01-01

    From the energy spectra of light particles produced in light-heavy-ion-induced reactions, level densities of the final nuclei as well as the critical angular momenta for fusion may be obtained. The 14N, 16,18O+ 12C reactions were investigated in the energy range 30 MeVlight particles (p,d,t,3He,α) emitted in the process were obtained. Fits of the magnitude and shape of the spectra by means of statistical model calculations were used to extract final nuclei level densities. The shape of the spectra and the ratio σ(α)/σ(p) are shown to be sensitive to the fusion critical angular momentum (Jcr), offering an alternative method for the total fusion cross-section determination.

  13. Very high pressure liquid chromatography using fully porous particles: quantitative analysis of fast gradient separations without post-run times.

    PubMed

    Stankovich, Joseph J; Gritti, Fabrice; Stevenson, Paul G; Beaver, Lois Ann; Guiochon, Georges

    2014-01-10

    Using a column packed with fully porous particles, four methods for controlling the flow rates at which gradient elution runs are conducted in very high pressure liquid chromatography (VHPLC) were tested to determine whether reproducible thermal conditions could be achieved, such that subsequent analyses would proceed at nearly the same initial temperature. In VHPLC high flow rates are achieved, producing fast analyses but requiring high inlet pressures. The combination of high flow rates and high inlet pressures generates local heat, leading to temperature changes in the column. Usually in this case a post-run time is input into the analytical method to allow the return of the column temperature to its initial state. An alternative strategy involves operating the column without a post-run equilibration period and maintaining constant temperature variations for subsequent analysis after conducting one or a few separations to bring the column to a reproducible starting temperature. A liquid chromatography instrument equipped with a pressure controller was used to perform constant pressure and constant flow rate VHPLC separations. Six replicate gradient separations of a nine component mixture consisting of acetophenone, propiophenone, butyrophenone, valerophenone, hexanophenone, heptanophenone, octanophenone, benzophenone, and acetanilide dissolved in water/acetonitrile (65:35, v/v) were performed under various experimental conditions: constant flow rate, two sets of constant pressure, and constant pressure operation with a programmed flow rate. The relative standard deviations of the response factors for all the analytes are lower than 5% across the methods. Programming the flow rate to maintain a fairly constant pressure instead of using instrument controlled constant pressure improves the reproducibility of the retention times by a factor of 5, when plotting the chromatograms in time.

  14. Unsteady Fast Random Particle Mesh method for efficient prediction of tonal and broadband noises of a centrifugal fan unit

    NASA Astrophysics Data System (ADS)

    Heo, Seung; Cheong, Cheolung; Kim, Taehoon

    2015-09-01

    In this study, efficient numerical method is proposed for predicting tonal and broadband noises of a centrifugal fan unit. The proposed method is based on Hybrid Computational Aero-Acoustic (H-CAA) techniques combined with Unsteady Fast Random Particle Mesh (U-FRPM) method. The U-FRPM method is developed by extending the FRPM method proposed by Ewert et al. and is utilized to synthesize turbulence flow field from unsteady RANS solutions. The H-CAA technique combined with U-FRPM method is applied to predict broadband as well as tonal noises of a centrifugal fan unit in a household refrigerator. Firstly, unsteady flow field driven by a rotating fan is computed by solving the RANS equations with Computational Fluid Dynamic (CFD) techniques. Main source regions around the rotating fan are identified by examining the computed flow fields. Then, turbulence flow fields in the main source regions are synthesized by applying the U-FRPM method. The acoustic analogy is applied to model acoustic sources in the main source regions. Finally, the centrifugal fan noise is predicted by feeding the modeled acoustic sources into an acoustic solver based on the Boundary Element Method (BEM). The sound spectral levels predicted using the current numerical method show good agreements with the measured spectra at the Blade Pass Frequencies (BPFs) as well as in the high frequency range. On the more, the present method enables quantitative assessment of relative contributions of identified source regions to the sound field by comparing predicted sound pressure spectrum due to modeled sources.

  15. Design of a fast multileaf collimator for radiobiological optimized IMRT with scanned beams of photons, electrons, and light ions.

    PubMed

    Svensson, Roger; Larsson, Susanne; Gudowska, Irena; Holmberg, Rickard; Brahme, Anders

    2007-03-01

    Intensity modulated radiation therapy is rapidly becoming the treatment of choice for most tumors with respect to minimizing damage to the normal tissues and maximizing tumor control. Today, intensity modulated beams are most commonly delivered using segmental multileaf collimation, although an increasing number of radiation therapy departments are employing dynamic multileaf collimation. The irradiation time using dynamic multileaf collimation depends strongly on the nature of the desired dose distribution, and it is difficult to reduce this time to less than the sum of the irradiation times for all individual peak heights using dynamic leaf collimation [Svensson et al., Phys. Med. Biol. 39, 37-61 (1994)]. Therefore, the intensity modulation will considerably increase the total treatment time. A more cost-effective procedure for rapid intensity modulation is using narrow scanned photon, electron, and light ion beams in combination with fast multileaf collimator penumbra trimming. With this approach, the irradiation time is largely independent of the complexity of the desired intensity distribution and, in the case of photon beams, may even be shorter than with uniform beams. The intensity modulation is achieved primarily by scanning of a narrow elementary photon pencil beam generated by directing a narrow well focused high energy electron beam onto a thin bremsstrahlung target. In the present study, the design of a fast low-weight multileaf collimator that is capable of further sharpening the penumbra at the edge of the elementary scanned beam has been simulated, in order to minimize the dose or radiation response of healthy tissues. In the case of photon beams, such a multileaf collimator can be placed relatively close to the bremsstrahlung target to minimize its size. It can also be flat and thin, i.e., only 15-25 mm thick in the direction of the beam with edges made of tungsten or preferably osmium to optimize the sharpening of the penumbra. The low height of

  16. Design of a fast multileaf collimator for radiobiological optimized IMRT with scanned beams of photons, electrons, and light ions

    SciTech Connect

    Svensson, Roger; Larsson, Susanne; Gudowska, Irena; Holmberg, Rickard; Brahme, Anders

    2007-03-15

    Intensity modulated radiation therapy is rapidly becoming the treatment of choice for most tumors with respect to minimizing damage to the normal tissues and maximizing tumor control. Today, intensity modulated beams are most commonly delivered using segmental multileaf collimation, although an increasing number of radiation therapy departments are employing dynamic multileaf collimation. The irradiation time using dynamic multileaf collimation depends strongly on the nature of the desired dose distribution, and it is difficult to reduce this time to less than the sum of the irradiation times for all individual peak heights using dynamic leaf collimation [Svensson et al., Phys. Med. Biol. 39, 37-61 (1994)]. Therefore, the intensity modulation will considerably increase the total treatment time. A more cost-effective procedure for rapid intensity modulation is using narrow scanned photon, electron, and light ion beams in combination with fast multileaf collimator penumbra trimming. With this approach, the irradiation time is largely independent of the complexity of the desired intensity distribution and, in the case of photon beams, may even be shorter than with uniform beams. The intensity modulation is achieved primarily by scanning of a narrow elementary photon pencil beam generated by directing a narrow well focused high energy electron beam onto a thin bremsstrahlung target. In the present study, the design of a fast low-weight multileaf collimator that is capable of further sharpening the penumbra at the edge of the elementary scanned beam has been simulated, in order to minimize the dose or radiation response of healthy tissues. In the case of photon beams, such a multileaf collimator can be placed relatively close to the bremsstrahlung target to minimize its size. It can also be flat and thin, i.e., only 15-25 mm thick in the direction of the beam with edges made of tungsten or preferably osmium to optimize the sharpening of the penumbra. The low height of

  17. Fast cyclic electron transport around photosystem I in leaves under far-red light: a proton-uncoupled pathway?

    PubMed

    Laisk, Agu; Talts, Eero; Oja, Vello; Eichelmann, Hillar; Peterson, Richard B

    2010-02-01

    Fast cyclic electron transport (CET) around photosystem I (PS I) was observed in sunflower (Helianthus annuus L.) leaves under intense far-red light (FRL) of up to 200 mumol quanta m(-2) s(-1). The electron transport rate (ETR) through PS I was found from the FRL-dark transmittance change at 810 and 950 nm, which was deconvoluted into redox states and pool sizes of P700, plastocyanin (PC) and cytochrome f (Cyt f). PC and P700 were in redox equilibrium with K(e) = 35 (ΔE(m) = 90 mV). PS II ETR was based on O(2) evolution. CET [(PS I ETR) - (PS II ETR)] increased to 50-70 mumol e(-) m(-2) s(-1) when linear electron transport (LET) under FRL was limited to 5 mumol e(-) m(-2) s(-1) in a gas phase containing 20-40 mumol CO(2) mol(-1) and 20 mumol O(2) mol(-1). Under these conditions, pulse-saturated fluorescence yield F(m) was non-photochemically quenched; however, F(m) was similarly quenched when LET was driven by low green or white light, which energetically precluded the possibility for active CET. We suggest that under FRL, CET is rather not coupled to transmembrane proton translocation than the CET-coupled protons are short-circuited via proton channels regulated to open at high ΔpH. A kinetic analysis of CET electron donors and acceptors suggests the CET pathway is that of the reversed Q-cycle: Fd -> (FNR) -> Cyt c(n) -> Cyt b(h) -> Cyt b(l) -> Rieske FeS -> Cyt f -> PC -> P700 ->-> Fd. CET is activated when PQH(2) oxidation is opposed by high ΔpH, and ferredoxin (Fd) is reduced due to low availability of e(-) acceptors. The physiological significance of CET may be photoprotective, as CET may be regarded as a mechanism of energy dissipation under stress conditions.

  18. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Threshold for gas breakdown initiated by an interaction of laser light with aerosol particles

    NASA Astrophysics Data System (ADS)

    Borets-Pervak, I. Yu; Vorob'ev, V. S.

    1993-03-01

    A model constructed previously for plasma production through the laser heating, evaporation, and ionization of a microscopic surface defect is refined in an effort to determine the breakdown conditions in an aerosol. Simple analytic expressions are derived for the threshold laser intensity as a function of the wavelength of the laser light, the dimensions and material of the aerosol particles, the shape of the laser pulse, and the evaporated volume of the particle. The results are compared with experiments on the laser breakdown of air caused by beams from CO2 and Nd lasers in the presence of an aerosol consisting of carbon particles 0.1-25 μm in radius. The results are also compared with the predictions of the explosion model.

  19. Photosensitized destruction of Chlorella vulgaris by Methylene Blue or Nuclear Fast Red combined with hydrogen peroxide under visible light irradiation.

    PubMed

    McCullagh, Cathy; Robertson, Peter K J

    2006-04-01

    A considerable number of investigations have started to elucidate the essential roles biological agents play in the biodeterioration of stone. Chemical biocides are becoming increasingly banned because of the environmental and health hazards associated with these toxic substances. The present study reports the photodynamic effect of Methylene Blue (MB) and Nuclear Fast Red (NFR) in the presence of hydrogen peroxide (H2O2) on the destruction of the algae Chlorella vulgaris (C. vulgaris) under irradiation with visible light. Illumination of C. vulgaris in the presence of MB or NFR combined with H2O2 results in the decomposition of both the algal species and the photosensitizer. The photodynamic effect was investigated under aerobic and anaerobic conditions. Differences in mechanism type are reported and are dependent on both the presence and the absence of oxygen. The behavior of each photosensitizer leads to a Type II mechanism and a Type I/Type II combination for MB and NFR, respectively, being concluded. This novel combination could be effective for the remediation of biofilm-colonized stone surfaces.

  20. Influence of surface roughness on the elastic-light scattering patterns of micron-sized aerosol particles

    NASA Astrophysics Data System (ADS)

    Auger, J.-C.; Fernandes, G. E.; Aptowicz, K. B.; Pan, Y.-L.; Chang, R. K.

    2010-04-01

    The relation between the surface roughness of aerosol particles and the appearance of island-like features in their angle-resolved elastic-light scattering patterns is investigated both experimentally and with numerical simulation. Elastic scattering patterns of polystyrene spheres, Bacillus subtilis spores and cells, and NaCl crystals are measured and statistical properties of the island-like intensity features in their patterns are presented. The island-like features for each class of particle are found to be similar; however, principal-component analysis applied to extracted features is able to differentiate between some of the particle classes. Numerically calculated scattering patterns of Chebyshev particles and aggregates of spheres are analyzed and show qualitative agreement with experimental results.

  1. Fasting and postprandial remnant-like particle cholesterol concentrations in obese participants are associated with plasma triglycerides, insulin resistance, and body fat distribution.

    PubMed

    van Hees, Anneke M J; Saris, Wim H M; Dallinga-Thie, Geesje M; Hul, Gabby B; Martinez, J Alfredo; Oppert, Jean-Michel; Stich, Vladimir; Astrup, Arne; Arner, Peter; Sørensen, Thorkild I A; Blaak, Ellen E

    2008-12-01

    Elevated plasma concentrations of remnant-like particle cholesterol (RLP-C) are atherogenic. However, factors that determine RLP-C are not fully understood. This study evaluates which factors affect RLP-C in the fasting and postprandial state, using multiple regression analyses in a large cohort of lean and obese participants. All participants (n = 740) underwent a test meal challenge containing 95 energy % (en%) fat (energy content 50% of predicted daily resting metabolic rate). Fasting and postprandial concentrations of circulating metabolites were measured over a 3-h period. Obese participants (n = 613) also participated in a 10-wk weight loss program (-2510 kJ/d), being randomized to either a low-fat or a high-fat diet (20-25 vs. 40-45en% fat). Postprandial RLP-C was associated with fasting RLP-C, waist:hip ratio (WHR), HOMA(IR) (homeostasis model assessment index for insulin resistance) (P < 0.001), and age, independently of BMI and gender [adjusted R(2) (adj. R(2)) = 0.70). These factors were also related to fasting RLP-C (P < 0.010), along with gender and physical activity (adj. R(2) = 0.23). The dietary intervention resulted in significantly lower fasting RLP-C concentrations, independently mediated by weight loss, improvements in HOMA(IR), and the fat content of the prescribed diet. However, after inclusion of plasma triglyceride (TG), HDL-cholesterol, and FFA concentrations in the models, HOMA(IR) and WHR no longer significantly predicted fasting RLP-C, although WHR remained a predictor of postprandial RLP-C (P = 0.002). Plasma TG was strongly associated with both fasting and postprandial RLP-C (P < 0.001). In conclusion, plasma RLP-C concentrations are mainly associated with plasma TG concentrations. Interestingly, the high-fat diet was more effective at decreasing fasting RLP-C concentrations in obese participants than the low-fat diet.

  2. Spectral shape of a signal in light-induced diffusive pulling (pushing) of particles into a light beam

    SciTech Connect

    Parkhomenko, A I; Shalagin, A M

    2015-02-28

    We study theoretically how the dependences of transport collision frequencies ν{sub i}, collision broadening γ and collision shift Δ of the levels on the velocity v of resonant particles influence lightinduced diffusive pulling (pushing) (LDP) effects in the framework of a generalised model of strong collisions in the case of velocitydependent collision rates (so-called kangaroo model). It is found that allowance for the dependences ν{sub i}(v), γ(v) and Δ(v) does not change the spectral shape of an LDP signal. In particular, in the case of low-intensity radiation, the spectral dependence of the LDP signal coincides with the absorption line shape. It is shown that the magnitude of the LDP effect is proportional to the difference between the diffusion coefficients of particles in the excited and ground states. It is found that the spectral anomalies previously predicted in the LDP effect [Gel'mukhanov F.Kh. JETP Lett., 55, 214 (1992)] for an idealised model of the Lorentz gas (the limiting case of heavy buffer particles), which arise due to the dependences ν{sub i}(v), γ(v) and Δ(v), are typical only for this gas. At a realistic ratio of the masses of absorbing and buffer particles, spectral anomalies do not occur in the LDP effect. (nonlinear optical phenomena)

  3. Spectral shape of a signal in light-induced diffusive pulling (pushing) of particles into a light beam

    NASA Astrophysics Data System (ADS)

    Parkhomenko, A. I.; Shalagin, A. M.

    2015-02-01

    We study theoretically how the dependences of transport collision frequencies νi, collision broadening γ and collision shift Δ of the levels on the velocity v of resonant particles influence lightinduced diffusive pulling (pushing) (LDP) effects in the framework of a generalised model of strong collisions in the case of velocitydependent collision rates (so-called kangaroo model). It is found that allowance for the dependences νi(v), γ(v) and Δ(v) does not change the spectral shape of an LDP signal. In particular, in the case of low-intensity radiation, the spectral dependence of the LDP signal coincides with the absorption line shape. It is shown that the magnitude of the LDP effect is proportional to the difference between the diffusion coefficients of particles in the excited and ground states. It is found that the spectral anomalies previously predicted in the LDP effect [Gel'mukhanov F.Kh. JETP Lett., 55, 214 (1992)] for an idealised model of the Lorentz gas (the limiting case of heavy buffer particles), which arise due to the dependences νi(v), γ(v) and Δ(v), are typical only for this gas. At a realistic ratio of the masses of absorbing and buffer particles, spectral anomalies do not occur in the LDP effect.

  4. LIGHT MICROSCOPY DETECTION OF NANOSCALE PARTICLE INTERNALIZATION BY HUMAN LUNG CELLS

    EPA Science Inventory

    RATIONALE. Ultrafine particulate matter (PM) is reported to be more strongly correlated with adverse health effects relative to larger particle size fractions. These epidemiological findings are supported by toxicological studies suggesting that particle size is inversely associa...

  5. Monte Carlo simulations of light scattering by composite particles in a planetary surface

    NASA Technical Reports Server (NTRS)

    Hillier, J.; Buratti, B.

    2001-01-01

    Composite particles containing internal scatterers have been proposed as an explanation for the fact that most photometric studies of planetary surfaces based on Hapke's bidirectional reflectance model have found the planetary particles to exhibit moderately backscattering phase functions.

  6. Finite-Difference Time Domain Solution of Light Scattering and Absorption by Particles in an Absorbing Medium

    NASA Technical Reports Server (NTRS)

    Sun, W.; Loeb, N. G.; Fu, Q.

    2002-01-01

    The three-dimensional (3-D) finite-difference time-domain (FDTD) technique has been extended to simulate light scattering and absorption by nonspherical particles embedded in an absorbing dielectric medium. A uniaxial perfectly matched layer (UPML) absorbing boundary condition is used to truncate the computational domain. When computing the single-scattering properties of a particle in an absorbing dielectric medium, we derive the single-scattering properties including scattering phase functions, extinction, and absorption efficiencies using a volume integration of the internal field. A Mie solution for light scattering and absorption by spherical particles in an absorbing medium is used to examine the accuracy of the 3-D UPML FDTD code. It is found that the errors in the extinction and absorption efficiencies from the 3-D UPML FDTD are less than similar to 2%. The errors in the scattering phase functions are typically less than similar to 5%. The errors in the asymmetry factors are less than similar to 0.l%. For light scattering by particles in free space, the accuracy of the 3-D UPML FDTD scheme is similar to a previous model.

  7. Verification and Validation of Gyrokinetic Particle Simulation of Fast Electron Driven Beta-induced Alfvén Eigenmodes on HL-2A Tokamak

    NASA Astrophysics Data System (ADS)

    Cheng, Junyi; Chen, Yang; Zhang, Wenlu; Lin, Zhihong; Chen, Wei; Yu, Limin; Ding, Xuantong

    2015-11-01

    A verification and validation study is carried out for a sequence of fast electron driven beta-induced Alfven eigenmodes in HL-2A tokamak plasma. The fast electron driven beta induced Alfvén eigenmode (e-BAE) in toroidal plasmas is investigated for the first time using global gyrokinetic particle simulations, where the fast electrons are described by the drift kinetic model. The phase space structure shows that only the processional resonance is responsible for the e-BAE excitations while fast-ion driven BAE can be excited through all the channels such as transit, drift-bounce, and processional resonance. For weakly nonlinear driven case, frequency is observed to be in phase with the particle energy flux, and mode structure is almost the same as linear stage . While in the strongly driven nonlinear case, BAAE is excited after the BAE mode saturated. The simulation of e-BAE with the HL-2A tokamak parameters is taken. Three modes n/m = 1/2 , 2/5 ,1/3 in HL-2A can be excited in our simulations.

  8. Search for lightly ionizing particles using CDMS-II data and fabrication of CDMS detectors with improved homogeneity in properties

    SciTech Connect

    Prasad, Kunj Bihari

    2013-12-01

    Fundamental particles are always observed to carry charges which are integral multiples of one-third charge of electron, e/3. While this is a well established experimental fact, the theoretical understanding for the charge quantization phenomenon is lacking. On the other hand, there exist numerous theoretical models that naturally allow for existence of particles with fractional electromagnetic charge. These particles, if existing, hint towards existence of physics beyond the standard model. Multiple high energy, optical, cosmological and astrophysical considerations restrict the allowable mass-charge parameter space for these fractional charges. Still, a huge unexplored region remains. The Cryogenic Dark Matter Search (CDMS-II), located at Soudan mines in northern Minnesota, employs germanium and silicon crystals to perform direct searches for a leading candidate to dark matter called Weakly Interacting Massive Particles (WIMPs). Alternately, the low detection threshold allows search for fractional electromagnetic-charged particles, or Lightly Ionizing Particles (LIPs), moving at relativistic speed. Background rejection is obtained by requiring that the magnitude and location of energy deposited in each detector be consistent with corresponding \\signatures" resulting from the passage of a fractionally charged particle. In this dissertation, the CDMS-II data is analyzed to search for LIPs, with an expected background of 0.078 0.078 events. No candidate events are observed, allowing exclusion of new parameter space for charges between e/6 and e/200.

  9. Supramolecularly self-organized nanomaterials: A voyage from inorganic particles to organic light-harvesting materials

    NASA Astrophysics Data System (ADS)

    Varotto, Alessandro

    In 2009 the U.S. National Science Foundation announced the realignment of the Chemistry Divisions introducing the new interdisciplinary program of "Macromolecular, Supramolecular and Nanochemistry." This statement officially recognizes a field of studies that has already seen the publication of many thousands of works in the past 20 years. Nanotechnology and supramolecular chemistry can be found in the most diverse disciplines, from biology to engineering, to physics. Furthermore, many technologies rely on nanoscale dimensions for more than one component. Nanomaterials and technologies are on the market with a range of applications from composite materials, to electronics, to medicine, to sensing and more. This thesis will introduce a variety of studies and applications of supramolecular chemistry to form nanoscale photonic materials from soft matter. We will first illustrate a method to synthesize metallic nanoparticles using plasmids DNA as a mold. The circular DNA functions as a sacrificial template to shape the particles into narrowly monodispersed nanodiscs. Secondly, we will describe the synthesis of a highly fluorinated porphyrin derivative and how the fluorines improve the formation of ultra thin films when the porphyrin is blended with fullerene C60. Finally, we will show how to increase the short-circuit current in a solar cell built with an internal parallel tandem light harvesting design. A blend of phthalocyanines, each with a decreasing optical band gap, is supramolecularly self-organized with pyridyl-C60 within thin films. The different band gaps of the single phthalocyanines capture a wider segment of the solar spectrum increasing the overall efficiency of the device. In conclusion, we have presented a number of studies for the preparation of inorganic and organic nanomaterials and their application in supramolecularly organized photonic devices.

  10. Slow light performance enhancement of Bragg slot photonic crystal waveguide with particle swarm optimization algorithm

    NASA Astrophysics Data System (ADS)

    Abedi, Kambiz; Mirjalili, Seyed Mohammad

    2015-03-01

    Recently, majority of current research in the field of designing Phonic Crystal Waveguides (PCW) focus in extracting the relations between output slow light properties of PCW and structural parameters through a huge number of tedious non-systematic simulations in order to introduce better designs. This paper proposes a novel systematic approach which can be considered as a shortcut to alleviate the difficulties and human involvements in designing PCWs. In the proposed method, the problem of PCW design is first formulated as an optimization problem. Then, an optimizer is employed in order to automatically find the optimum design for the formulated PCWs. Meanwhile, different constraints are also considered during optimization with the purpose of applying physical limitations to the final optimum structure. As a case study, the structure of a Bragg-like Corrugation Slotted PCWs (BCSPCW) is optimized by using the proposed method. One of the most computationally powerful techniques in Computational Intelligence (CI) called Particle Swarm Optimization (PSO) is employed as an optimizer to automatically find the optimum structure for BCSPCW. The optimization process is done by considering five constraints to guarantee the feasibility of the final optimized structures and avoid band mixing. Numerical results demonstrate that the proposed method is able to find an optimum structure for BCSPCW with 172% and 100% substantial improvements in the bandwidth and Normalized Delay-Bandwidth Product (NDBP) respectively compared to the best current structure in the literature. Moreover, there is a time domain analysis at the end of the paper which verifies the performance of the optimized structure and proves that this structure has low distortion and attenuation simultaneously.

  11. Feasibility studies for light scattering experiments to determine the velocity relaxation of small particles in a fluid

    NASA Technical Reports Server (NTRS)

    Acquista, C.; Narducci, L. M.

    1980-01-01

    An approach for measuring the non-Markoffian component in the relaxation mechanism of a Brownian particle is proposed which combines desirable features of both the shock wave experiment and conventional light scattering experiments. It is suggested that the radiation pressure generated by a C.W. laser be used to guide an individual spherical particle to terminal velocity. At an appropriate time, the beam intensity is suddenly lowered to a value at which the radiation pressure is negligible, and the ensuing velocity relaxation is measured directly.

  12. Integral indicatrix of light scattering from {open_quotes}soft{close_quotes} spherical particles in the region of small angles

    SciTech Connect

    Lopatin, V.N.; Shapovalov, K.A.

    1995-05-01

    The integral indicatrix of light scattering from a {open_quotes}soft{close_quotes} spherical particle is studied as a function of the phase shift. It is shown analytically in the WKB approximation and numerically on the basis of the Mie theory and the WKB approximation that the dependence of the integral indicatrix on the phase shift is similar to that for the factor of light scattering efficiency. Asymptotic expressions for the integral indicatrix are obtained for large diffraction parameters in the limiting cases of small and large phase shifts in the region of small angles. 8 refs., 3 figs.

  13. Constraining the Physical Properties of Meteor Stream Particles by Light Curve Shapes Using the Virtual Meteor Observatory

    NASA Technical Reports Server (NTRS)

    Koschny, D.; Gritsevich, M.; Barentsen, G.

    2011-01-01

    Different authors have produced models for the physical properties of meteoroids based on the shape of a meteor's light curve, typically from short observing campaigns. We here analyze the height profiles and light curves of approx.200 double-station meteors from the Leonids and Perseids using data from the Virtual Meteor Observatory, to demonstrate that with this web-based meteor database it is possible to analyze very large datasets from different authors in a consistent way. We compute the average heights for begin point, maximum luminosity, and end heights for Perseids and Leonids. We also compute the skew of the light curve, usually called the F-parameter. The results compare well with other author's data. We display the average light curve in a novel way to assess the light curve shape in addition to using the F-parameter. While the Perseids show a peaked light curve, the average Leonid light curve has a more flat peak. This indicates that the particle distribution of Leonid meteors can be described by a Gaussian distribution; the Perseids can be described with a power law. The skew for Leonids is smaller than for Perseids, indicating that the Leonids are more fragile than the Perseids.

  14. Portable sample preparation and analysis system for micron and sub-micron particle characterization using light scattering and absorption spectroscopy

    DOEpatents

    Stark, Peter C.; Zurek, Eduardo; Wheat, Jeffrey V.; Dunbar, John M.; Olivares, Jose A.; Garcia-Rubio, Luis H.; Ward, Michael D.

    2011-07-26

    There is provided a method and device for remote sampling, preparation and optical interrogation of a sample using light scattering and light absorption methods. The portable device is a filtration-based device that removes interfering background particle material from the sample matrix by segregating or filtering the chosen analyte from the sample solution or matrix while allowing the interfering background particles to be pumped out of the device. The segregated analyte is then suspended in a diluent for analysis. The device is capable of calculating an initial concentration of the analyte, as well as diluting the analyte such that reliable optical measurements can be made. Suitable analytes include cells, microorganisms, bioparticles, pathogens and diseases. Sample matrixes include biological fluids such as blood and urine, as well as environmental samples including waste water.

  15. An influence of long-lasting and gradual magnetic flux transport on fate of magnetotail fast plasma flows: An energetic particle injection substorm event study

    NASA Astrophysics Data System (ADS)

    Nowada, Motoharu; Fu, Suiyan; Parks, George K.; Pulkkinen, Tuija I.; Pu, Zuyin

    2014-10-01

    Based on multi-satellite and ground observations, we investigated an influence of long-lasting and gradual enhancements of magnetic flux transport rate on the magnetotail fast flow duration. On March 10th, 2009, THEMIS-B, which was located in the central plasma sheet of middle distant magnetotail (XGSM ~-25.8 RE), observed the fast flows with the velocity exceeding 300 km/s, lasting over 3 h for intense southward Interplanetary Magnetic Field (IMF) period. During long-lasting fast flows, AL index variations were very extensive and their recovery was much slow. Pi 2 waves were observed at the ground observatories around the THEMIS's footpoints and at low-/mid-latitudes. The aspect for these AL variations suggests Steady Magnetospheric Convection (SMC), but clear substorm signatures were also observed. Further magnetic dipolarization was detected by THEMIS-A at XGSM ~-8.2 RE and its nearby THEMIS-E. Only THEMIS-A observed the associated energetic electron flux enhancements. Therefore, the fast flows occurred during substorm with energetic particle injections at “imitative” SMC, which would be driven by prolonged intense southward IMF. The cumulative transport rates of magnetic and Poynting fluxes consecutively and gradually enhanced. On the other hand, THEMIS-C detected much shorter fast flows with the duration of 37 min at XGSM ~-18.1 RE and weak/gradual substorm-associated dipolarization. However, the cumulative magnetic flux transport rate was enhanced only during the fast flow interval and was saturated after the fast flows. From different magnetic transport rate profiles at THEMIS-B and THEMIS-C, the realms of dipolar-configured field lines expanded to near THEMIS-C's position responsible for long-lasting fast flow-associated consecutive and gradual magnetic flux pileup. Because the resultant “high-speed flow braking” region was retreated into a few RE tailward direction, long-lasting fast flows were almost stemmed. These results suggest that the

  16. Radiation Force Caused by Scattering, Absorption, and Emission of Light by Nonspherical Particles

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael I.; Hansen, James E. (Technical Monitor)

    2001-01-01

    General formulas for computing the radiation force exerted on arbitrarily oriented and arbitrarily shaped nonspherical particles due to scattering, absorption, and emission of electromagnetic radiation are derived. For randomly oriented particles with a plane of symmetry, the formula for the average radiation force caused by the particle response to external illumination reduces to the standard Debye formula derived from the Lorenz-Mie theory, whereas the average radiation force caused by emission vanishes.

  17. Influence of particle size and concentration on the diffuse backscattering of polarized light from tissue phantoms and biological cell suspensions

    SciTech Connect

    Hielscher, A.H.; Mourant, J.R.; Bigio, I.J.

    1997-01-01

    We present experimental results that show the spatial variations of the diffuse-backscattered intensity when linearly polarized light is incident upon highly scattering media. Experiments on polystyrene-sphere and Intralipid suspensions demonstrate that the radial and azimuthal variations of the observed pattern depend on the concentration, and anisotropy factor {ital g} of the particles that constitute the scattering medium. Measurements performed on biological-cell suspensions show the potential of this method for cell characterization. {copyright} 1997 Optical Society of America

  18. Visible light-induced photocatalytic reaction of gold-modified titanium(IV) oxide particles: action spectrum analysis.

    PubMed

    Kowalska, Ewa; Abe, Ryu; Ohtani, Bunsho

    2009-01-08

    Action spectrum analyses showed that visible light-induced oxidation of 2-propanol by aerated gold-modified titanium(IV) oxide (titania) suspensions is initiated by excitation of gold surface plasmon, and polychromatic irradiation experiments revealed that the photocatalytic reaction rate depends strongly on properties of titania, such as particle size, surface area and crystalline form (anatase or rutile) and on properties of gold deposits, such as size and shape.

  19. Light scattering by tenuous particles - A generalization of the Rayleigh-Gans-Rocard approach

    NASA Technical Reports Server (NTRS)

    Acquista, C.

    1976-01-01

    We consider scattering by arbitrarily shaped particles that satisfy two conditions: (1) that the polarizability of the particle relative to the ambient medium be small compared to 1 and (2) that the phase shift introduced by the particle be less than 2. We solve the integro-differential equation proposed by Shifrin by using the method of successive iterations and then applying a Fourier transform. For the second iteration, results are presented that accurately describe scattering by a broad class of particles. The phase function and other elements of the scattering matrix are shown to be in excellent agreement with Mie theory for spherical scatterers.

  20. Fast-cycling superconducting synchrotrons and possible path to the future of US experimental high-energy particle physics

    SciTech Connect

    Piekarz, Henryk; /Fermilab

    2008-02-01

    The authors outline primary physics motivation, present proposed new arrangement for Fermilab accelerator complex, and then discuss possible long-range application of fast-cycling superconducting synchrotrons at Fermilab.

  1. Ruling out the light weakly interacting massive particle explanation of the Galactic 511 keV line

    NASA Astrophysics Data System (ADS)

    Wilkinson, Ryan J.; Vincent, Aaron C.; BÅ`hm, Céline; McCabe, Christopher

    2016-11-01

    Over the past few decades, an anomalous 511 keV gamma-ray line has been observed from the center of the Milky Way. Dark matter (DM) in the form of light (≲10 MeV ) weakly interacting massive particles (WIMPs) annihilating into electron-positron pairs has been one of the leading hypotheses of the observed emission. Given the small required cross section, ⟨σ v ⟩˜1 0-30 cm3 s-1 , a further coupling to lighter particles is required to produce the correct relic density. Here, we derive constraints from the Planck satellite on light WIMPs that were in equilibrium with either the neutrino or electron sector in the early universe. For the neutrino sector, we obtain a lower bound on the WIMP mass of 4 MeV for a real scalar and 10 MeV for a Dirac fermion DM particle, at 95% C.L. For the electron sector, we find even stronger bounds of 7 and 11 MeV, respectively. Using these results, we show that, in the absence of additional ingredients such as dark radiation, the light thermally produced WIMP explanation of the 511 keV excess is strongly disfavored by the latest cosmological data. This suggests an unknown astrophysical or more exotic DM source of the signal.

  2. Coherent reflection of light from a turbid suspension of particles in an internal-reflection configuration: Theory versus experiment.

    PubMed

    García-Valenzuela, Augusto; Barrera, Rubén; Sánchez-Pérez, Celia; Reyes-Coronado, Alejandro; Méndez, Eugenio

    2005-09-05

    We compare a recently developed coherent-scattering model for the reflectance of light from a turbid colloidal suspension of particles with experimental measurements. The experimental data were obtained in an internal reflection configuration around the critical angle using a glass prism in contact with a monodisperse colloidal suspension of latex particles, and a polydisperse suspension of TiO2 particles. First, we review the coherent scattering model and extend it to the case of polydisperse suspensions in an internal reflection configuration. The experimental data is then compared with results of the coherent scattering model and results obtained assuming that the colloidal system can be treated as a homogeneous medium with an effective index of refraction. We find that the experimental results are not compatible with the effective medium model. On the other hand, good fits to the experimental curves can be obtained with the coherent scattering model.

  3. Light-charged-particle emission in the spontaneous fission of /sup 250/Cf, /sup 256/Fm, and /sup 257/Fm

    SciTech Connect

    Wild, J.F.; Baisden, P.A.; Dougan, R.J.; Hulet, E.K.; Lougheed, R.W.; Landrum, J.H.

    1985-08-01

    We have measured the energy spectra for the emission of long-range ..cap alpha.. particles from the spontaneous fission of /sup 250/Cf, /sup 256/Fm, and /sup 257/Fm, and for tritons and protons from the spontaneous fission of /sup 250/Cf and /sup 256/Fm. We have determined ..cap alpha.., triton, and proton emission probabilities and estimated total light-particle emission probabilities for these nuclides. We compare these and known emission probabilities for five other spontaneously fissioning nuclides with the deformation energy available at scission and show that there is a possible correlation that is consistent with a one-body dissipation mechanism for transferring release energy to particle clusters.

  4. Graphene-enhanced visible-light photocatalysis of large-sized CdS particles for wastewater treatment

    NASA Astrophysics Data System (ADS)

    Lü, Wei; Chen, Jie; Wu, Yao; Duan, Lianfeng; Yang, Yue; Ge, Xin

    2014-03-01

    The hybrid composites of graphene decorated by large-sized CdS particles (G/M-CdS) were prepared by a one-pot solvothermal route in which the reduction of graphite oxide into graphene was accompanied by the generation of microsized CdS particles. The structure and composition of the obtained nanocomposites were studied by means of X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The CdS particles with the average sizes of approximately 640 nm were formed on graphene sheets. The as-prepared composite was used as adsorbent to remove dye from wastewater using the organic dye Rhodamine B as the adsorbate. The G/M-CdS composite reveals a high photodegradation rate under visible light irradiation. Our results demonstrate that the G/M-CdS is very promising for removing organic dyes from wastewater.

  5. Graphene-enhanced visible-light photocatalysis of large-sized CdS particles for wastewater treatment.

    PubMed

    Lü, Wei; Chen, Jie; Wu, Yao; Duan, Lianfeng; Yang, Yue; Ge, Xin

    2014-03-26

    The hybrid composites of graphene decorated by large-sized CdS particles (G/M-CdS) were prepared by a one-pot solvothermal route in which the reduction of graphite oxide into graphene was accompanied by the generation of microsized CdS particles. The structure and composition of the obtained nanocomposites were studied by means of X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The CdS particles with the average sizes of approximately 640 nm were formed on graphene sheets. The as-prepared composite was used as adsorbent to remove dye from wastewater using the organic dye Rhodamine B as the adsorbate. The G/M-CdS composite reveals a high photodegradation rate under visible light irradiation. Our results demonstrate that the G/M-CdS is very promising for removing organic dyes from wastewater.

  6. Graphene-enhanced visible-light photocatalysis of large-sized CdS particles for wastewater treatment

    PubMed Central

    2014-01-01

    The hybrid composites of graphene decorated by large-sized CdS particles (G/M-CdS) were prepared by a one-pot solvothermal route in which the reduction of graphite oxide into graphene was accompanied by the generation of microsized CdS particles. The structure and composition of the obtained nanocomposites were studied by means of X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The CdS particles with the average sizes of approximately 640 nm were formed on graphene sheets. The as-prepared composite was used as adsorbent to remove dye from wastewater using the organic dye Rhodamine B as the adsorbate. The G/M-CdS composite reveals a high photodegradation rate under visible light irradiation. Our results demonstrate that the G/M-CdS is very promising for removing organic dyes from wastewater. PMID:24666436

  7. Remobilizing surfactant retarded fluid particle interfaces. I. Stress-free conditions at the interfaces of micellar solutions of surfactants with fast sorption kinetics

    NASA Astrophysics Data System (ADS)

    Stebe, Kathleen J.; Lin, Shi-Yow; Maldarelli, Charles

    1991-01-01

    Surfactant molecules adsorb onto the interfaces of moving fluid particles and are convected to regions in which the surface flow converges. Accumulation of surfactant in these regions creates interfacial tension gradients that retard the surface flow. In this study it is argued theoretically and demonstrated experimentally that fluid movement on the surface of a drop or bubble can remain unhindered in the presence of a single adsorbed surfactant if, relative to the convective rate of transport of adsorbed surfactant along the surface, desorption is fast, and the bulk concentration is high enough so that diffusion away from the particle is fast. For this circumstance, a uniform surface concentration of surfactant is maintained, and no gradients in surface tension arise to retard the surface velocity. The fluid particle flow behaves as it would in the absence of surfactant save that it has a reduced, uniform surface tension. The remobilization of surfactant-laden interfaces of fluid particles is demonstrated experimentally in a three-phase periodic slug flow in a capillary tube in which a train of alternating air and aqueous slugs ride on an annular wetting film of fluorocarbon oil. Surfactant, dissolved in the aqueous slug phase, adsorbs onto and retards the aqueous-oil interface. The hydrodynamics of this flow is such that small changes in the mobility of this interface create large shear rates in the oil layer. This significantly increases the pressure drop required to drive the slug train at constant velocity. Three surface adsorbers are used to demonstrate surface remobilization: The polyethoxy, nonionic surfactants Triton X-100 and Brij-35, which have fast desorption kinetics and do not retard the surface flow at high concentrations and, as a counter example, the desorption hindered protein bovine serum albumin, which is shown to be unable to remobilize an interface even at high concentration.

  8. Elements and polycyclic aromatic hydrocarbons in exhaust particles emitted by light-duty vehicles.

    PubMed

    Alves, Célia A; Barbosa, Cátia; Rocha, Sónia; Calvo, Ana; Nunes, Teresa; Cerqueira, Mário; Pio, Casimiro; Karanasiou, Angeliki; Querol, Xavier

    2015-08-01

    The main purpose of this work was to evaluate the chemical composition of particulate matter (PM) emitted by eight different light-duty vehicles. Exhaust samples from petrol and diesel cars (Euro 3 to Euro 5) were collected in a chassis dynamometer facility. To simulate the real-world driving conditions, three ARTEMIS cycles were followed: road, to simulate a fluid traffic flow and urban with hot and cold starts, to simulate driving conditions in cities. Samples were analysed for the water-soluble ions, for the elemental composition and for polycyclic aromatic hydrocarbons (PAHs), respectively, by ion chromatography, inductively coupled plasma atomic emission spectroscopy (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS) and gas chromatography-mass spectrometry (GC-MS). Nitrate and phosphate were the major water-soluble ions in the exhaust particles emitted from diesel and petrol vehicles, respectively. The amount of material emitted is affected by the vehicle age. For vehicles ≥Euro 4, most elements were below the detection limits. Sodium, with emission factors in the ranges 23.5-62.4 and 78.2-227μg km(-1), for petrol and diesel Euro 3 vehicles, respectively, was the major element. The emission factors of metallic elements indicated that diesel vehicles release three to five times more than petrol automobiles. Element emissions under urban cycles are higher than those found for on-road driving, being three or four times higher, for petrol vehicles, and two or three times, for diesel vehicles. The difference between cycles is mainly due to the high emissions for the urban cycle with hot start-up. As registered for elements, most of the PAH emissions for vehicles ≥Euro 4 were also below the detection limits. Regardless of the vehicle models or driving cycles, the two- to four-ring PAHs were always dominant. Naphthalene, with emission factors up to 925 μg km(-1), was always the most abundant PAH. The relative cancer risk associated with

  9. Fast Magnetic Reconnection and Particle Acceleration in Relativistic Low-density Electron-Positron Plasmas without Guide Field

    NASA Astrophysics Data System (ADS)

    Bessho, Naoki; Bhattacharjee, A.

    2012-05-01

    Magnetic reconnection and particle acceleration in relativistic Harris sheets in low-density electron-positron plasmas with no guide field have been studied by means of two-dimensional particle-in-cell simulations. Reconnection rates are of the order of one when the background density in a Harris sheet is of the order of 1% of the density in the current sheet, which is consistent with previous results in the non-relativistic regime. It has been demonstrated that the increase of the Lorentz factors of accelerated particles significantly enhances the collisionless resistivity needed to sustain a large reconnection electric field. It is shown analytically and numerically that the energy spectrum of accelerated particles near the X-line is the product of a power law and an exponential function of energy, γ-1/4exp (- aγ1/2), where γ is the Lorentz factor and a is a constant. However, in the low-density regime, while the most energetic particles are produced near X-lines, many more particles are energized within magnetic islands. Particles are energized in contracting islands by multiple reflection, but the mechanism is different from Fermi acceleration in magnetic islands for magnetized particles in the presence of a guide field. In magnetic islands, strong core fields are generated and plasma beta values are reduced. As a consequence, the fire-hose instability condition is not satisfied in most of the island region, and island contraction and particle acceleration can continue. In island coalescence, reconnection between two islands can accelerate some particles, however, many particles are decelerated and cooled, which is contrary to what has been discussed in the literature on particle acceleration due to reconnection in non-relativistic hydrogen plasmas.

  10. Fast drying of biocompatible polymer films loaded with poorly water-soluble drug nano-particles via low temperature forced convection.

    PubMed

    Susarla, Ramana; Sievens-Figueroa, Lucas; Bhakay, Anagha; Shen, Yueyang; Jerez-Rozo, Jackeline I; Engen, William; Khusid, Boris; Bilgili, Ecevit; Romañach, Rodolfo J; Morris, Kenneth R; Michniak-Kohn, Bozena; Davé, Rajesh N

    2013-10-15

    Fast drying of nano-drug particle laden strip-films formed using water-soluble biocompatible polymers via forced convection is investigated in order to form films having uniform drug distribution and fast dissolution. Films were produced by casting and drying a mixture of poorly water soluble griseofulvin (GF) nanosuspensions produced via media milling with aqueous hydroxypropyl methylcellulose (HPMC E15LV) solutions containing glycerin as a plasticizer. The effects of convective drying parameters, temperature and air velocity, and film-precursor viscosity on film properties were investigated. Two major drying regimes, a constant rate period as a function of the drying conditions, followed by a single slower falling rate period, were observed. Films dried in an hour or less without any irreversible aggregation of GF nanoparticles with low residual water content. Near-infrared chemical imaging (NIR-CI) and the content uniformity analysis indicated a better drug particle distribution when higher viscosity film-precursors were used. Powder X-ray diffraction showed that the GF in the films retained crystallinity and the polymorphic form. USP IV dissolution tests showed immediate release (~20 min) of GF. Overall, the films fabricated from polymer-based suspensions at higher viscosity dried at different conditions exhibited similar mechanical properties, improved drug content uniformity, and achieved fast drug dissolution.

  11. Entrainment of mouse peripheral circadian clocks to <24 h feeding/fasting cycles under 24 h light/dark conditions

    PubMed Central

    Hamaguchi, Yutaro; Tahara, Yu; Kuroda, Hiroaki; Haraguchi, Atsushi; Shibata, Shigenobu

    2015-01-01

    The circadian clock system in peripheral tissues can endogenously oscillate and is entrained by the light-dark and fasting-feeding cycles in mammals. Although the system’s range of entrainment to light-dark cycles with a non-24 h (<24 h) interval has been studied, the range of entrainment to fasting-feeding cycles with shorter periods (<24 h) has not been investigated in peripheral molecular clocks. In the present study, we measured this range by monitoring the mouse peripheral PER2::LUCIFERASE rhythm in vivo at different periods under each feeding cycle (Tau (T) = 15–24 h) under normal light-dark conditions. Peripheral clocks could be entrained to the feeding cycle with T = 22–24 h, but not to that with T = 15–21 h. Under the feeding cycle with T = 15–18 h, the peripheral clocks oscillated at near the 24-h period, suggesting that they were entrained to the light-dark cycle. Thus, for the first time, we demonstrated the range of entrainment to the non-24 h feeding cycle, and that the circadian range (T = 22–24 h) of feeding stimulus is necessary for peripheral molecular clock entrainment under light-dark cycles. PMID:26395309

  12. Entrainment of mouse peripheral circadian clocks to <24 h feeding/fasting cycles under 24 h light/dark conditions.

    PubMed

    Hamaguchi, Yutaro; Tahara, Yu; Kuroda, Hiroaki; Haraguchi, Atsushi; Shibata, Shigenobu

    2015-09-23

    The circadian clock system in peripheral tissues can endogenously oscillate and is entrained by the light-dark and fasting-feeding cycles in mammals. Although the system's range of entrainment to light-dark cycles with a non-24 h (<24 h) interval has been studied, the range of entrainment to fasting-feeding cycles with shorter periods (<24 h) has not been investigated in peripheral molecular clocks. In the present study, we measured this range by monitoring the mouse peripheral PER2::LUCIFERASE rhythm in vivo at different periods under each feeding cycle (Tau (T) = 15-24 h) under normal light-dark conditions. Peripheral clocks could be entrained to the feeding cycle with T = 22-24 h, but not to that with T = 15-21 h. Under the feeding cycle with T = 15-18 h, the peripheral clocks oscillated at near the 24-h period, suggesting that they were entrained to the light-dark cycle. Thus, for the first time, we demonstrated the range of entrainment to the non-24 h feeding cycle, and that the circadian range (T = 22-24 h) of feeding stimulus is necessary for peripheral molecular clock entrainment under light-dark cycles.

  13. Type I polar stratospheric cloud particles - Concentration, shape, size, light extinction

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Ferry, G. V.; Snetsinger, K. G.; Goodman, J.; Hamill, P.; Livingston, J. M.; Mccormick, M. P.

    1990-01-01

    Results from the flight on January 24, 1989 of the Airborne Arctic Stratospheric Experiment during which the ER-2 aircraft transitioned from unsaturated to ice saturated air at 20 km altitude are presented. Aerosol particles were sampled by wire impactors and examined for number density as a function of particle size by taking photomicrographs in a scanning electron microscope and visually sizing and counting the particles. Differences in the chemical, physical and optical properties of stratospheric aerosol between ice-saturated and nonsaturated air are described.

  14. Arctic climate response to forcing from light-absorbing particles in snow and sea ice in CESM

    NASA Astrophysics Data System (ADS)

    Goldenson, N.; Doherty, S. J.; Bitz, C. M.; Holland, M. M.; Light, B.; Conley, A. J.

    2012-02-01

    The presence of light-absorbing aerosol particles deposited on arctic snow and sea ice influences the surface albedo, causing greater shortwave absorption, warming, and loss of snow and sea ice, lowering the albedo further. The Community Earth System Model version 1 (CESM1) now includes the radiative effects of light-absorbing particles in snow on land and sea ice and in sea ice itself. We investigate the model response to the deposition of black carbon and dust to both snow and sea ice. For these purposes we employ a slab ocean version of CESM1, using the Community Atmosphere Model version 4 (CAM4), run to equilibrium for year 2000 levels of CO2 and fixed aerosol deposition. We construct experiments with and without aerosol deposition, with dust or black carbon deposition alone, and with varying quantities of black carbon and dust to approximate year 1850 and 2000 deposition fluxes. The year 2000 deposition fluxes of both dust and black carbon cause 1-2 °C of surface warming over large areas of the Arctic Ocean and sub-Arctic seas in autumn and winter and in patches of Northern land in every season. Atmospheric circulation changes are a key component of the surface-warming pattern. Arctic sea ice thins by on average about 30 cm. Simulations with year 1850 aerosol deposition are not substantially different from those with year 2000 deposition, given constant levels of CO2. The climatic impact of particulate impurities deposited over land exceeds that of particles deposited over sea ice. Even the surface warming over the sea ice and sea ice thinning depends more upon light-absorbing particles deposited over land. For CO2 doubled relative to year 2000 levels, the climate impact of particulate impurities in snow and sea ice is substantially lower than for the year 2000 equilibrium simulation.

  15. Arctic climate response to forcing from light-absorbing particles in snow and sea ice in CESM

    NASA Astrophysics Data System (ADS)

    Goldenson, N.; Doherty, S. J.; Bitz, C. M.; Holland, M. M.; Light, B.; Conley, A. J.

    2012-09-01

    The presence of light-absorbing aerosol particles deposited on arctic snow and sea ice influences the surface albedo, causing greater shortwave absorption, warming, and loss of snow and sea ice, lowering the albedo further. The Community Earth System Model version 1 (CESM1) now includes the radiative effects of light-absorbing particles in snow on land and sea ice and in sea ice itself. We investigate the model response to the deposition of black carbon and dust to both snow and sea ice. For these purposes we employ a slab ocean version of CESM1, using the Community Atmosphere Model version 4 (CAM4), run to equilibrium for year 2000 levels of CO2 and fixed aerosol deposition. We construct experiments with and without aerosol deposition, with dust or black carbon deposition alone, and with varying quantities of black carbon and dust to approximate year 1850 and 2000 deposition fluxes. The year 2000 deposition fluxes of both dust and black carbon cause 1-2 °C of surface warming over large areas of the Arctic Ocean and sub-Arctic seas in autumn and winter and in patches of Northern land in every season. Atmospheric circulation changes are a key component of the surface-warming pattern. Arctic sea ice thins by on average about 30 cm. Simulations with year 1850 aerosol deposition are not substantially different from those with year 2000 deposition, given constant levels of CO2. The climatic impact of particulate impurities deposited over land exceeds that of particles deposited over sea ice. Even the surface warming over the sea ice and sea ice thinning depends more upon light-absorbing particles deposited over land. For CO2 doubled relative to year 2000 levels, the climate impact of particulate impurities in snow and sea ice is substantially lower than for the year 2000 equilibrium simulation.

  16. A reliable light scattering computing for black carbon-containing particles: Hybrid discrete dipole approximation (h-DDA)

    NASA Astrophysics Data System (ADS)

    Moteki, N.

    2015-12-01

    Black carbon (BC) is a light-absorbing carbonaceous aerosol emitted from combustions of fossil fuels and biomasses and is estimated as the second most important contributor to positive climate forcing after the carbon dioxide. In the atmosphere, the fractal aggregate of BC-spherules may be mixed with non-absorbing (or weakly absorbing) compounds that forms morphologically complex "BC-containing particle". A reliable scattering code for BC-containing particles is necessary for predicting mass absorption efficiency of BC and designing/evaluating optical techniques for estimating microphysical properties (i.e., size distribution, mixing state, shape, refractive index) of BC-containing particles. The computational methods that derived from the volume-integral form of the Maxwell equation, such as discrete dipole approximation (DDA), are method of choice for morphologically complex object like BC-containing particles. In ordinary DDA, the entire particle volume is approximated as a collection of tiny cubical dipoles (with side length d) placed on a 3D cubic lattice. For several model BC-containing particles, the comparisons with numerically exact T-matrix method reveals that the ordinary DDA suffered from persistent positive systematic error (up to +30%) in absorption even under d <<λ. The cause of this DDA error is identified to be the shape error in BC-spherules. To eliminate the shape error in BC-spherules, we propose a new DDA methodology which may be called hybrid DDA (h-DDA): each primary BC sphere is assumed as a spherical dipole, while remaining particle volume of coating material is approximated by a collection of tiny cubical dipoles on a 3D cubic lattice. Positive absorption bias up to +30% in ordinary DDA is suppressed to within 3% in h-DDA. In h-DDA code, an efficient FFT-based algorithm for solving the matrix equation has been implemented, by utilizing the multilevel block-Toeplitz property of the submatrix corresponding to inter-dipole interaction within

  17. Reduction in biomass burning aerosol light absorption upon humidification: Roles of inorganically-induced hygroscopicity, particle collapse, and photoacoustic heat and mass transfer

    SciTech Connect

    lewis, Kristen A.; Arnott, W. P.; Moosmuller, H.; Chakrabarti, Raj; Carrico, Christian M.; Kreidenweis, Sonia M.; Day, Derek E.; Malm, William C.; Laskin, Alexander; Jimenez, Jose L.; Ulbrich, Ingrid M.; Huffman, John A.; Onasch, Timothy B.; Trimborn, Achim; Liu, Li; Mishchenko, M.

    2009-11-27

    Smoke particle emissions from the combustion of biomass fuels typical for the western and southeastern United States were studied and compared under high humidity and ambient conditions in the laboratory. The fuels used are Montana ponderosa pine (Pinus ponderosa), southern California chamise (Adenostoma fasciculatum), and Florida saw palmetto (Serenoa repens). Information on the non-refractory chemical composition of biomass burning aerosol from each fuel was obtained with an aerosol mass spectrometer and through estimation of the black carbon concentration from light absorption measurements at 870 nm. Changes in the optical and physical particle properties under high humidity conditions were observed for hygroscopic smoke particles containing substantial inorganic mass fractions that were emitted from combustion of chamise and palmetto fuels. Light scattering cross sections increased under high humidity for these particles, consistent with the hygroscopic growth measured for 100 nm particles in HTDMA measurements. Photoacoustic measurements of aerosol light absorption coefficients reveal a 20% reduction with increasing relative humidity, contrary to the expectation of light absorption enhancement by the liquid coating taken up by hygroscopic particles. This reduction is hypothesized to arise from two mechanisms: 1. Shielding of inner monomers after particle consolidation or collapse with water uptake; 2. The contribution of mass transfer through evaporation and condensation at high relative humidity to the usual heat transfer pathway for energy release by laser heated particles in the photoacoustic measurement of aerosol light absorption. The mass transfer contribution is used to evaluate the fraction of aerosol surface covered with liquid water solution as a function of RH.

  18. Three dimensional indoor positioning based on visible light with Gaussian mixture sigma-point particle filter technique

    NASA Astrophysics Data System (ADS)

    Gu, Wenjun; Zhang, Weizhi; Wang, Jin; Amini Kashani, M. R.; Kavehrad, Mohsen

    2015-01-01

    Over the past decade, location based services (LBS) have found their wide applications in indoor environments, such as large shopping malls, hospitals, warehouses, airports, etc. Current technologies provide wide choices of available solutions, which include Radio-frequency identification (RFID), Ultra wideband (UWB), wireless local area network (WLAN) and Bluetooth. With the rapid development of light-emitting-diodes (LED) technology, visible light communications (VLC) also bring a practical approach to LBS. As visible light has a better immunity against multipath effect than radio waves, higher positioning accuracy is achieved. LEDs are utilized both for illumination and positioning purpose to realize relatively lower infrastructure cost. In this paper, an indoor positioning system using VLC is proposed, with LEDs as transmitters and photo diodes as receivers. The algorithm for estimation is based on received-signalstrength (RSS) information collected from photo diodes and trilateration technique. By appropriately making use of the characteristics of receiver movements and the property of trilateration, estimation on three-dimensional (3-D) coordinates is attained. Filtering technique is applied to enable tracking capability of the algorithm, and a higher accuracy is reached compare to raw estimates. Gaussian mixture Sigma-point particle filter (GM-SPPF) is proposed for this 3-D system, which introduces the notion of Gaussian Mixture Model (GMM). The number of particles in the filter is reduced by approximating the probability distribution with Gaussian components.

  19. Validity of Particle-Counting Method Using Laser-Light Scattering for Detecting Platelet Aggregation in Diabetic Patients

    NASA Astrophysics Data System (ADS)

    Nakadate, Hiromichi; Sekizuka, Eiichi; Minamitani, Haruyuki

    We aimed to study the validity of a new analytical approach that reflected the phase from platelet activation to the formation of small platelet aggregates. We hoped that this new approach would enable us to use the particle-counting method with laser-light scattering to measure platelet aggregation in healthy controls and in diabetic patients without complications. We measured agonist-induced platelet aggregation for 10 min. Agonist was added to the platelet-rich plasma 1 min after measurement started. We compared the total scattered light intensity from small aggregates over a 10-min period (established analytical approach) and that over a 2-min period from 1 to 3 min after measurement started (new analytical approach). Consequently platelet aggregation in diabetics with HbA1c ≥ 6.5% was significantly greater than in healthy controls by both analytical approaches. However, platelet aggregation in diabetics with HbA1c < 6.5%, i.e. patients in the early stages of diabetes, was significantly greater than in healthy controls only by the new analytical approach, not by the established analytical approach. These results suggest that platelet aggregation as detected by the particle-counting method using laser-light scattering could be applied in clinical examinations by our new analytical approach.

  20. Aerosol particle absorption spectroscopy by photothermal modulation of Mie scattered light

    SciTech Connect

    Campillo, A.J.; Dodge, C.J.; Lin, H.B.

    1981-09-15

    Absorption spectroscopy of suspended submicron-sized aqueous ammonium-sulfate aerosol droplets has been performed by employing a CO/sub 2/ laser to photothermally modulate visible Mie scattered light. (AIP)

  1. Manipulation and spectroscopy of a single particle by use of white-light optical tweezers

    NASA Astrophysics Data System (ADS)

    Li, Peng; Shi, Kebin; Liu, Zhiwen

    2005-01-01

    We demonstrate, for the first time to our knowledge, three-dimensional (3D) trapping and manipulation of microscopic objects by use of supercontinuum white light generated from photonic crystal fibers. Furthermore, we show that the supercontinuum white-light optical tweezers used have the unique capability to perform optical scattering spectroscopy of a single 3D trapped object over a broad wavelength range. These novel tweezers can potentially open a promising avenue toward simultaneous manipulation and characterization of microscopic objects.

  2. Revisiting the ultra-high dose rate effect: implications for charged particle radiotherapy using protons and light ions

    PubMed Central

    Wilson, P; Jones, B; Yokoi, T; Hill, M; Vojnovic, B

    2012-01-01

    Objective To reinvestigate ultra-high dose rate radiation (UHDRR) radiobiology and consider potential implications for hadrontherapy. Methods A literature search of cellular UHDRR exposures was performed. Standard oxygen diffusion equations were used to estimate the time taken to replace UHDRR-related oxygen depletion. Dose rates from conventional and novel methods of hadrontherapy accelerators were considered, including spot scanning beam delivery, which intensifies dose rate. Results The literature findings were that, for X-ray and electron dose rates of around 109 Gy s–1, 5–10 Gy depletes cellular oxygen, significantly changing the radiosensitivity of cells already in low oxygen tension (around 3 mmHg or 0.4 kPa). The time taken to reverse the oxygen depletion of such cells is estimated to be over 20–30 s at distances of over 100 μm from a tumour blood vessel. In this time window, tumours have a higher hypoxic fraction (capable of reducing tumour control), so the next application of radiation within the same fraction should be at a time that exceeds these estimates in the case of scanned beams or with ultra-fast laser-generated particles. Conclusion This study has potential implications for particle therapy, including laser-generated particles, where dose rate is greatly increased. Conventional accelerators probably do not achieve the critical UHDRR conditions. However, specific UHDRR oxygen depletion experiments using proton and ion beams are indicated. PMID:22496068

  3. Study of translational and rotational dynamics of birefringent colloidal particles by depolarized light scattering in the far- and near-field regimes.

    PubMed

    Escobedo-Sánchez, Manuel A; De la Cruz-Burelo, Hugo A; Arauz-Lara, José L; Haro-Pérez, Catalina; Rojas-Ochoa, Luis F

    2015-07-28

    We characterize the translational and rotational dynamics of birefringent spherical colloidal particles by depolarized light scattering in the far- and near-field regimes. For this purpose, we use depolarized dynamic light scattering and propose an extension of dynamic heterodyne near-field light scattering that takes into account the polarization state of the light. Such a combination of methods allows to access colloidal dynamics in an extended q-range and permits to evaluate different modes of particles motion in suspension. Furthermore, we obtain a good agreement between results from the far- and near-field approaches thus validating our proposal and opening the possibility to investigate simultaneously the subtle interplay between translational and rotational motions of anisotropic colloidal particles in length-scales from the order of the particle size to several interparticle distances.

  4. Chaotic motion of light particles in an unsteady three-dimensional vortex: experiments and simulation.

    PubMed

    Vanyó, József; Vincze, Miklós; Jánosi, Imre M; Tél, Tamás

    2014-07-01

    We study the chaotic motion of a small rigid sphere, lighter than the fluid in a three-dimensional vortex of finite height. Based on the results of Eulerian and Lagrangian measurements, a sequence of models is set up. The time-independent model is a generalization of the Burgers vortex. In this case, there are two types of attractors for the particle: a fixed point on the vortex axis and a limit cycle around the vortex axis. Time dependence might combine these regular attractors into a single chaotic attractor, however its robustness is much weaker than what the experiments suggest. To construct an aperiodically time-dependent advection dynamics in a simple way, Gaussian noise is added to the particle velocity in the numerical simulation. With an appropriate choice of the noise properties, mimicking the effect of local turbulence, a reasonable agreement with the experimentally observed particle statistics is found.

  5. Isospin effects on light charged particles as probes of nuclear dissipation

    SciTech Connect

    Ye, W.

    2009-07-15

    The multiplicities of postsaddle protons and {alpha} particles of the heavy systems {sup 234}Cf, {sup 240}Cf, {sup 246}Cf, and {sup 240}U as functions of the postsaddle dissipation strength are calculated in the framework of a dynamical Langevin model coupled with a statistical decay model. It is found that with increasing isospin of the Cf system, the sensitivity of the postsaddle proton and {alpha}-particle multiplicity to the dissipation strength decreases substantially, and it disappears for the {sup 240}U system. We suggest that on the experimental side, to accurately probe the postsaddle dissipation strength by measuring the prescission proton and {alpha}-particle multiplicity, it is best to populate heavy compound systems with low isospin.

  6. Light

    NASA Astrophysics Data System (ADS)

    Vernon, C. G.

    2016-09-01

    Preface; 1. Historical; 2. Waves and wave-motion; 3. The behaviour of ripples; 4. The behaviour of light; 5. Refraction through glass blocks and prisms; 6. The imprinting of curvatures; 7. Simple mathematical treatment; 8. More advanced mathematical treatment; 9. The velocity of light; 10. The spectrum and colour; 11. Geometrical optics; 12. The eye and optical instruments; 13. Sources of light; 14. Interference, diffraction and polarisation; 15. Suggestions for class experiments; Index.

  7. Reducing light-scattering losses in nanocolloids by increasing average inter-particle distance

    NASA Astrophysics Data System (ADS)

    García-Valenzuela, Augusto; Márquez-Islas, Roberto; Barrera, Rubén G.

    2017-01-01

    First, we present a brief review of the theory of the complex effective refractive index of a disordered suspension of nanoparticles that take into account the effects of scattering by the particles. We present numerical examples of the dependence of the scattering losses in nanocolloids with the concentration of non-absorbing and weakly absorbing nanoparticles. Then, we explore a way to reduce scattering losses in colloidal suspensions of non-absorbing nanoparticles. Finally, we provide some physical insight into the dependence of scattering losses with the particle concentration.

  8. Visible light-driven photocatalytic H{sub 2}-generation activity of CuS/ZnS composite particles

    SciTech Connect

    Xiao, Liang; Chen, Hua; Huang, Jianhua

    2015-04-15

    Highlights: • Preparation of CuS/ZnS composite photocatalyst by cation-exchange reaction. • Visible light photocatalytic activity for H{sub 2} evolution without cocatalyst. • The H{sub 2}-evolution rate from water splitting depends on the CuS content. • The highest rate of H{sub 2} evolution is obtained with CuS (0.5 mol%)/ZnS composite. - Abstract: CuS/ZnS composite particles with diameter of 200–400 nm were successfully prepared by a simple cation-exchange reaction using ZnS spheres as a precursor. CuS nanoparticles with a few nanometers in diameter were observed on the surface of composite particles. The synthesized CuS/ZnS composite particles showed photocatalytic property effective for H{sub 2} evolution from an aqueous Na{sub 2}S and Na{sub 2}SO{sub 3} solution under visible light irradiation without any cocatalysts. The rate of H{sub 2} generation was found to be strongly dependent on the CuS content. The highest rate of H{sub 2} evolution reached 695.7 μmol h{sup −1} g{sup −1}, which was almost 7 times as high as that of the mechanical mixture of CuS and ZnS. The enhancement in the photocatalytic activity of CuS/ZnS composite particles is supposed to be due to the direct interfacial charge transfer of the CuS/ZnS heterojunction.

  9. White light emission from transparent SiO2 glass prepared from nanometer-sized silica particles

    NASA Astrophysics Data System (ADS)

    Uchino, Takashi; Yamada, Tomoko

    2004-08-01

    We report that nanometer-sized silicon-dioxide particles are sintered to optical transparency at temperatures even below 1000°C, forming nonporous bulk silica glass. The resultant silica glass exhibits visible emission, which appears white to the naked eye, in the wavelength range from ˜400to˜700nm at room temperature under ultraviolet excitation. The observed emission is quite stable after prolonged exposure to the atmosphere and shows no appreciable light-induced degradation. The present photoluminescence characteristics are found to be basically different from those reported previously for silica nanoparticles and silica-based porous materials.

  10. Production of medical isotopes from a thorium target irradiated by light charged particles up to 70 MeV

    NASA Astrophysics Data System (ADS)

    Duchemin, C.; Guertin, A.; Haddad, F.; Michel, N.; Métivier, V.

    2015-02-01

    The irradiation of a thorium target by light charged particles (protons and deuterons) leads to the production of several isotopes of medical interest. Direct nuclear reaction allows the production of Protactinium-230 which decays to Uranium-230 the mother nucleus of Thorium-226, a promising isotope for alpha radionuclide therapy. The fission of Thorium-232 produces fragments of interest like Molybdenum-99, Iodine-131 and Cadmium-115g. We focus our study on the production of these isotopes, performing new cross section measurements and calculating production yields. Our new sets of data are compared with the literature and the last version of the TALYS code.

  11. Production of medical isotopes from a thorium target irradiated by light charged particles up to 70 MeV.

    PubMed

    Duchemin, C; Guertin, A; Haddad, F; Michel, N; Métivier, V

    2015-02-07

    The irradiation of a thorium target by light charged particles (protons and deuterons) leads to the production of several isotopes of medical interest. Direct nuclear reaction allows the production of Protactinium-230 which decays to Uranium-230 the mother nucleus of Thorium-226, a promising isotope for alpha radionuclide therapy. The fission of Thorium-232 produces fragments of interest like Molybdenum-99, Iodine-131 and Cadmium-115g. We focus our study on the production of these isotopes, performing new cross section measurements and calculating production yields. Our new sets of data are compared with the literature and the last version of the TALYS code.

  12. Phenomenological study of exclusive binary light particle production from antiproton-proton annihilation at FAIR/PANDA

    NASA Astrophysics Data System (ADS)

    Ying, Wang

    2016-08-01

    Exclusive binary annihilation reactions induced by antiprotons of momentum from 1.5 to 15 GeV/c can be extensively investigated at FAIR/PANDA [1]. We are especially interested in the channel of charged pion pairs. Whereas this very probable channel constitutes the major background for other processes of interest in the PANDA experiment, it carries unique physical information on the quark content of proton, allowing to test different models (quark counting rules, statistical models,..). To study the binary reactions of light meson formation, we are developing an effective Lagrangian model based on Feynman diagrams which takes into account the virtuality of the exchanged particles. Regge factors [2] and form factors are introduced with parameters which may be adjusted on the existing data. We present preliminary results of our formalism for different reactions of light meson production leading to reliable predictions of cross sections, energy and angular dependencies in the PANDA kinematical range.

  13. Light scattering by dust particles (PROGRA2 experiment): size and structure effects for transparent and absorbing materials

    NASA Astrophysics Data System (ADS)

    Hadamcik, E.; Renard, J.-B.; Lasue, J.; Levasseur-Regourd, A. C.

    2007-08-01

    1- Introduction Cometary and possibly interplanetary dust particles seem to be mainly made of agglomerates of submicron and micron-sized grains. These particles are among the most primitive in our solar system. Regoliths on asteroidal and planetary surfaces seem to be loose materials produced by impinging meteorites on the surface of small bodies. Comparing their physical properties is thus fundamental to understand their evolution. To interpret remote observations of solar light scattered by dust particles and regoliths, it is necessary to use numerical and experimental simulations [1,2,3]. 2- PROGRA2 experiment PROGRA2 instruments are polarimeters; the light sources are two randomly polarized lasers (632.8 nm and 543.5 nm). Levitating particles (in microgravity or lifted by an air-draught) are studied by imaging polarimetry. Details on the instruments can be found in [4,5]. 3- Samples Two kinds of samples are studied: compact particles in the (1-400) micrometer size range and fluffy aggregates in the same size range, made from submicron and micronsized grains. The materials are transparent silica and absorbing carbon. Some deposited particles are huge agglomerates of micron-sized grains produced by random ballistic deposition of single grains [6,7] or produced by evaporation of mixtures in alcohol of fluffy aggregates of submicron-sized grains. Two samples are made of silica spheres coated by a carbonaceous black compound. Cometary analogues are mixtures of silica and amorphous carbon or Mg-Fe silicates mixed with amorphous carbon. 4- Results Phase curves and their main parameters (negative polarization at small phase angles and maximum polarization, Pmax, at 90-100° phase angle) for the different materials will be compared and related to the physical properties. For example, it is well known by numerical simulations and/or by experiments that the maximum polarization decreases when the size (submicrometer range) of the grains increases [2,8,9]. An inverse rule

  14. Light dark matter candidates in intense laser pulses I: paraphotons and fermionic minicharged particles

    NASA Astrophysics Data System (ADS)

    Villalba-Chávez, S.; Müller, C.

    2015-06-01

    Polarimetric experiments driven by the strong field of a circularly polarized laser wave can become a powerful tool to limit the parameter space of not yet detected hidden-photons and minicharged particles associated with extra U(1) gauge symmetries. We show how the absorption and dispersion of probe electromagnetic waves in the vacuum polarized by such a background are modified due to the coupling between the visible U(1)-gauge sector and these hypothetical degrees of freedom. The results of this analysis reveal that the regime close to the two-photon reaction threshold can be a sensititive probe of these hidden particles. Parameters of modern laser systems are used to estimate the projected sensitivities on the corresponding coupling constants in regions where experiments driven by dipole magnets are less constricted. The role played by a paraphoton field is analyzed via a comparison with a model in which the existence of minicharges is assumed only. For both scenarios is found that the most stringent exclusion limit occurs at the lowest threshold mass; this one being determined by a certain combination of the field frequencies and dictated by energy momentum balance of the photo-production of a pair of minicharged particles. The dependencies of the observables on the laser attributes as well as on the unknown particle parameters are also analyzed.

  15. UV ATTENUATION NEAR CORAL REEFS IN THE FLORIDA KEYS: LIGHT ABSORPTION BY CDOM AND PARTICLES

    EPA Science Inventory

    We have investigated the roles of chromophoric dissolved organic matter (CDOM) and suspended particles in the attenuation of UV radiation in the middle and lower regions of the Florida Keys. Extended exposure to UV radiation, along with elevated sea surface temperatures, impairs...

  16. Engineering imaging: using particle image velocimetry to see physiology in a new light.

    PubMed

    Fouras, Andreas; Dusting, Jonathan; Sheridan, John; Kawahashi, Masaaki; Hirahara, Hiroyuki; Hourigan, Kerry

    2009-02-01

    1. Despite the array of sophisticated imaging techniques available for biological applications, none of the standard biomedical techniques adequately provides the capability to measure motion and flow. Those techniques currently in use are particularly lacking in spatial and temporal resolution. 2. Herein, we introduce the technique of particle image velocimetry. This technique is a well-established tool in engineering research and industry. Particle image velocimetry is continuing to develop and has an increasing number of variants. 3. Three case studies are presented: (i) the use of microparticle image velocimetry to study flow generated by high-frequency oscillatory ventilation in a human airway model; (ii) the use of stereoparticle image velocimetry to study stirred cell and tissue culture devices; and (iii) a three-dimensional X-ray particle image velocimetry technique used to measure flow in an in vitro vascular flow model. 4. The case studies highlight the vast potential of applying the engineering technique of particle image velocimetry and its many variants to current research problems in physiology.

  17. Dynamic light scattering arising from flowing Brownian particles: analytical model in optical coherence tomography conditions.

    PubMed

    Popov, Ivan; Weatherbee, Andrew S; Vitkin, I Alex

    2014-12-01

    The statistical model of scattered by flowing Brownian particles coherent radiation is suggested. The model includes the random Doppler shifts caused by particle Brownian motion and the speckle fluctuations caused primarily by the flow motion of particles. Analytical expressions are obtained for the correlation function, power spectrum, and spectral width of scattered radiation in the imaging geometry typically used in optical coherence tomography (OCT). It is shown that the spectral density has the Voigt shape, a well-known spectral profile from atomic and molecular spectroscopy. The approach enables the choice of the experimental regimes for the measurement of Brownian particle motion parameters even in the presence of flow. These regimes are characterized by the dominant contribution of Brownian motion in the spectral width of the flow-caused Doppler shift component. Further, the new formalism suggests that prior attempts to extract transverse flow velocity are only valid at near-perpendicular geometry. The impact of the small scattering volume contributing to the OCT signal is also discussed.

  18. Measurement of the light absorbing properties of diesel exhaust particles using a three-wavelength photoacoustic spectrometer

    NASA Astrophysics Data System (ADS)

    Guo, Xuesong; Nakayama, Tomoki; Yamada, Hiroyuki; Inomata, Satoshi; Tonokura, Kenichi; Matsumi, Yutaka

    2014-09-01

    Diesel-exhaust particles (DEP) are one of the main anthropogenic sources of black carbon (BC) and organic matter (OM). Understanding the optical properties of DEP, including the enhancement of light absorption by BC due to coating and light absorption by OM, is important for evaluating the climate impact of DEP. In this study, a three-wavelength photoacoustic soot spectrometer (405, 532, and 781 nm) was used to investigate the wavelength-dependent optical properties of DEP emitted from a diesel engine vehicle running on a chassis dynamometer in transient driving mode (JE-05) and at a constant speed (either idling or driving at 70 km/h). Optical properties were measured after passing the diluted exhaust through a heater, set at 20, 47, or 300 °C (transient driving mode) or between 20 and 400 °C (constant driving mode). The OM accounted for, on average, ∼40 and ∼35% of the total mass concentration of DEP during the transient and constant driving modes, respectively. In transient driving mode, enhancements of scattering coefficients at 20 and 47 °C, and of the mass concentration of organics, were observed during the high-speed driving period (∼80 km/h) corresponding to driving on a highway. No difference was observed in the absorption coefficients between heated and unheated particles at 781 nm for either the transient (including the high-speed driving period) or constant driving modes. These results indicate a lack of enhancement due to the lensing effect, possibly because the BC was mainly mixed externally with the OM or because it was located at the edges of particles under these experimental conditions. Contributions to total light absorption at 405 nm by the OM were estimated by comparing the wavelength dependence of the absorption coefficients with and without heating. A significant contribution by light-absorbing OM (20 ± 7%) to total light absorption at 405 nm was observed during the high-speed driving period of the JE-05 mode, while the

  19. Particle distribution and dynamics in a complex fluid suspension studied by an image-analysis light-scattering technique

    NASA Astrophysics Data System (ADS)

    Algarni, Saad; Kashuri, H.; Iannacchione, Germano

    2011-03-01

    A relatively unique approach is described to analyze the scattered laser light from a complex fluid suspension for both static and dynamic behavior. Recent development of speckle analysis using CCD recorded direct imaging of the scattered coherent light has opened many new avenues for the application of static and dynamic light scattering experiments. The straightforward nature of this approach is somewhat offset by the constraints of the CCD chip size and placement to probe wide (or narrow) ranges of the wave vector. An alternative, and greatly simplified variation of this technique, is to convert the scattered light into diffuse scattering using a translucent screen placed at a desired location down beam then imaging the resulting pattern on the screen. A thru-beam stop and axis scales can be easily placed on the screen and recorded to improve the image quality and later analysis. One of many possible applications is the study of the particle (7nm diam aerosil SiO2 spheres) distribution and dynamics due to Brownian motion as well as sedimentation in a complex fluid (glycerol).

  20. Analysis of the method of generalized separation of variables in the problem of light scattering by small axisymmetric particles

    NASA Astrophysics Data System (ADS)

    Farafonov, V. G.; Ustimov, V. I.

    2017-02-01

    In the problem of light scattering by small axisymmetric particles, we have constructed the Rayleigh approximation in which the polarizability of particles is determined by the generalized separation of variables method (GSVM). In this case, electric-field strengths are gradients of scalar potentials, which are represented as expansions in term of eigenfunctions of the Laplace operator in the spherical coordinate system. By virtue of the fact that the separation of variables in the boundary conditions is incomplete, the initial problem is reduced to infinite systems of linear algebraic equations (ISLAEs) with respect to unknown expansion coefficients. We have examined the asymptotic behavior of ISLAE elements at large values of indices. It has been shown that the necessary condition of the solvability of the ISLAE coincides with the condition of correct application of the extended boundary conditions method (EBCM). We have performed numerical calculations for Chebyshev particles with one maximum (also known as Pascal's snails or limaçons of Pascal). The obtained numerical results for the asymptotics of ISLAE elements and for the matrix support theoretical inferences. We have shown that the scattering and absorption cross sections of examined particles can be calculated in a wide range of variation of parameters with an error of about 1-2% using the spheroidal model. This model is also applicable in the case in which the solvability condition of the ISLAE for nonconvex particles is violated; in this case, the SVM should be considered as an approximate method, which frequently ensures obtaining results with an error less than 0.1-0.5%.

  1. Development of perturbation Monte Carlo methods for polarized light transport in a discrete particle scattering model.

    PubMed

    Nguyen, Jennifer; Hayakawa, Carole K; Mourant, Judith R; Venugopalan, Vasan; Spanier, Jerome

    2016-05-01

    We present a polarization-sensitive, transport-rigorous perturbation Monte Carlo (pMC) method to model the impact of optical property changes on reflectance measurements within a discrete particle scattering model. The model consists of three log-normally distributed populations of Mie scatterers that approximate biologically relevant cervical tissue properties. Our method provides reflectance estimates for perturbations across wavelength and/or scattering model parameters. We test our pMC model performance by perturbing across number densities and mean particle radii, and compare pMC reflectance estimates with those obtained from conventional Monte Carlo simulations. These tests allow us to explore different factors that control pMC performance and to evaluate the gains in computational efficiency that our pMC method provides.

  2. Development of perturbation Monte Carlo methods for polarized light transport in a discrete particle scattering model

    PubMed Central

    Nguyen, Jennifer; Hayakawa, Carole K.; Mourant, Judith R.; Venugopalan, Vasan; Spanier, Jerome

    2016-01-01

    We present a polarization-sensitive, transport-rigorous perturbation Monte Carlo (pMC) method to model the impact of optical property changes on reflectance measurements within a discrete particle scattering model. The model consists of three log-normally distributed populations of Mie scatterers that approximate biologically relevant cervical tissue properties. Our method provides reflectance estimates for perturbations across wavelength and/or scattering model parameters. We test our pMC model performance by perturbing across number densities and mean particle radii, and compare pMC reflectance estimates with those obtained from conventional Monte Carlo simulations. These tests allow us to explore different factors that control pMC performance and to evaluate the gains in computational efficiency that our pMC method provides. PMID:27231642

  3. Light scattering by nonspherical particles - A refinement to the coupled-dipole method

    NASA Technical Reports Server (NTRS)

    Dungey, Clifton E.; Bohren, Craig F.

    1991-01-01

    In the coupled-dipole method, an arbitrary particle is modeled as an array of N polarizable subunits, each of which gives rise to only electric dipole radiation. The Clausius-Mosotti relation is widely used to calculate the polarizability of the subunits that correspond to the dielectric function of the particle that the array represents. The Clausius-Mosotti relation is replaced here with an exact expression for the electric dipole polarizability, and improvement is found in extinction calculations for spheres as compared with Mie theory. Near a Froehlich frequency the coupled-dipole method yields extinction cross sections for spheres and spheroids that compare favorably with the continuous distribution of ellipsoids method and measured values.

  4. Role of Minerogenic Particles in Light Scattering in Lakes and a River in Central New York

    DTIC Science & Technology

    2007-09-10

    calibration protocol. Corrections for differences in the ten samples for both elemental and morphometric pure-water absorption and attenuation due to tem...PA’>, (6) Morphometric characterization of particles by SAX is based on a "rotating chord" algorithm, which pro- where N,,, is the number of...to characterize individual minerogenic par- nous versus autochthonous) is essential information ticles both compositionally and morphometrically for

  5. Nuclear Thermal Propulsion engine based on Particle Bed Reactor using light water steam as a propellant

    SciTech Connect

    Powell, J.R.; Ludewig, H.; Maise, G.

    1993-06-01

    In this paper the possibility of configuring a water cooled Nuclear Thermal Propulsion (NTP) rocket, based on a Particle Bed Reactor (PBR) is investigated. This rocket will be used to operate on water obtained from near earth objects. The conclusions reached in this paper indicate that it is possible to configure a PBR based NTP rocket to operate on water and meet the mission requirements envisioned for it. No insurmountable technology issues have been identified.

  6. Light Scattering by Marine Particles: Modeling with Non-Spherical Shapes

    DTIC Science & Technology

    2011-04-15

    absorbing pigment ? A principal result of the study (detailed in Appendix 3) is that the extinction, absorption, and scattering efficiencies, and the...sediment transport [1], to the estimation of the energy available for photosynthesis [2] and the effi- ciency with which photosynthetic organisms can uti...terms of their chemical and physical properties, such as size, pigment composition, refrac- tive index, etc. [5—7]. In most studies the particles

  7. Confinement and dynamics of neutral beam injected fast ions in the MST Reversed Field Pinch

    NASA Astrophysics Data System (ADS)

    Liu, D.; Almagri, F.; Anderson, J. K.; den Hartog, D. J.; Nornberg, M. D.; Sarff, J. S.; Waksman, J.; Fiksel, G.; Deichuli, P.; Davydenko, V. I.; Ivanov, A. A.; Polosatkin, S. V.; Stupishin, N.; Andre, R.; McCune, D.

    2010-11-01

    The new 1MW neutral beam injector (97% H, 3% D) on MST provides a good test-bed for study of fast ions in the RFP. Analysis of the D-D fusion neutron flux decay at beam turn-off reveals that the confinement time of the fast ions is at least 10 ms, ten-fold larger than the thermal conferment times for particles and energy in standard stochastic plasmas. Also, the fast ion confinement increases with magnetic field strength. Dependence of fast ion confinement on plasma parameters, beam energy, and injection direction will be characterized and compared with TRANSP simulations. In addition, an advanced neutral particle analyzer and a prototype of fast ion charge exchange spectroscopy are under construction to measure neutralized fast ions and induced Doppler-shifted Hα light, respectively, thereby resolving fast ion density and energy distribution. Initial measurements of fast-ion dynamics during magnetic reconnection events will be presented.

  8. A fast Eulerian multiphase flow model for volcanic ash plumes: turbulence, heat transfer and particle non-equilibrium dynamics.

    NASA Astrophysics Data System (ADS)

    Cerminara, Matteo; Esposti Ongaro, Tomaso; Carlo Berselli, Luigi

    2014-05-01

    We have developed a compressible multiphase flow model to simulate the three-dimensional dynamics of turbulent volcanic ash plumes. The model describes the eruptive mixture as a polydisperse fluid, composed of different types of gases and particles, treated as interpenetrating Eulerian phases. Solid phases represent the discrete ash classes into which the total granulometric spectrum is discretized, and can differ by size and density. The model is designed to quickly and accurately resolve important physical phenomena in the dynamics of volcanic ash plumes. In particular, it can simulate turbulent mixing (driving atmospheric entrainment and controlling the heat transfer), thermal expansion (controlling the plume buoyancy), the interaction between solid particles and volcanic gas (including kinetic non-equilibrium effects) and the effects of compressibility (over-pressured eruptions and infrasonic measurements). The model is based on the turbulent dispersed multiphase flow theory for dilute flows (volume concentration <0.001, implying that averaged inter-particle distance is larger than 10 diameters) where particle collisions are neglected. Moreover, in order to speed up the code without losing accuracy, we make the hypothesis of fine particles (Stokes number <0.2 , i.e., volcanic ash particles finer then a millimeter), so that we are able to consider non-equilibrium effects only at the first order. We adopt LES formalism (which is preferable in transient regimes) for compressible flows to model the non-linear coupling between turbulent scales and the effect of sub-grid turbulence on the large-scale dynamics. A three-dimensional numerical code has been developed basing on the OpenFOAM computational framework, a CFD open source parallel software package. Numerical benchmarks demonstrate that the model is able to capture important non-equilibrium phenomena in gas-particle mixtures, such as particle clustering and ejection from large-eddy turbulent structures, as well

  9. The Orbiting Wide-Angle Light Collectors (OWL) Mission for Charged-Particle Astronomy

    NASA Technical Reports Server (NTRS)

    Mitchell, John; Krizmanic, J. F.; Stecker, F. W.; Streitmatter, R. E.

    2009-01-01

    The space-based OWL mission is designed to perform high-statistics measurements of ultra-high-energy cosmic rays (UHECR) using the Earth's atmosphere as a vast particle calorimeter, furthering the field of charged-particle astronomy. OWL has been developed in formal NASA instrument and mission studies and is comprised of two large telescopes separated by approx.600 km in 1000 km, near-equatorial orbits to stereoscopically image the near-UV air fluorescence emitted by UHECR-induced particle cascades. The High Resolution Fly's Eye (HiRes) Collaboration, and subsequently the Pierre Auger Observatory, recently reported confirmation of the expected Greisen-Zatsepin-Kuzmin (GZK) suppression of the UHECR flux above a few times 10(exp 19) eV. This observation is consistent with the majority of UHECR originating in astrophysical objects and reduces the need to invoke exotic physical processes. Particles observed above the GZK threshold energy must have come from sources within about 100 Mpc from the Earth. The small particle deflection angles expected at UHECR energies, with standard assumptions of extragalactic magnetic fields, are on the order of 1 degree. Thus by observing particles above the GZK threshold with sufficient exposure, there is the potential of identifying and characterizing individual UHECR sources. Auger has reported significant anisotropy in the arrival directions of UHECR at energies above about 6 10(exp 19) eV observed in the South, and a correlation to AGN in the 12th VCV catalog, suggesting that the sources of UHECR are traced by the distribution of luminous matter in the Universe. However, with similar statistics and the same event selection criteria, HiRes observations in the North are consistent with isotropy. Extended observations by Auger-South, by Telescope Array in the North, and possibly by the proposed Auger-North, will further these investigations. However, much greater exposures will be required to fully identify individual sources and

  10. Note: Light output enhanced fast response and low afterglow {sup 6}Li glass scintillator as potential down-scattered neutron diagnostics for inertial confinement fusion

    SciTech Connect

    Arikawa, Yasunobu; Yamanoi, Kohei; Nagai, Takahiro; Watanabe, Kozue; Kouno, Masahiro; Sakai, Kohei; Nakazato, Tomoharu; Shimizu, Toshihiko; Cadatal, Marilou Raduban; Estacio, Elmer Surat; Sarukura, Nobuhiko; Nakai, Mitsuo; Norimatsu, Takayoshi; Azechi, Hiroshi; Murata, Takahiro; Fujino, Shigeru; Yoshida, Hideki; Izumi, Nobuhiko; Satoh, Nakahiro; Kan, Hirofumi

    2010-10-15

    The characteristics of an APLF80+3Ce scintillator are presented. Its sufficiently fast decay profile, low afterglow, and an improved light output compared to the recently developed APLF80+3Pr, were experimentally demonstrated. This scintillator material holds promise for applications in neutron imaging diagnostics at the energy regions of 0.27 MeV of DD fusion down-scattered neutron peak at the world's largest inertial confinement fusion facilities such as the National Ignition Facility and the Laser Megajoule.

  11. Comparative analysis of four-wave mixing of optical pulses in slow- and fast-light regimes of a silicon photonic crystal waveguide.

    PubMed

    Lavdas, Spyros; Panoiu, Nicolae C

    2015-09-15

    We present an in-depth study of four-wave mixing (FWM) of optical pulses in silicon photonic crystal waveguides. Our analysis is based on a rigorous model that includes all relevant linear and nonlinear optical effects and their dependence on the group velocity, as well as the influence of free carriers on pulse dynamics. In particular, we reveal key differences between FWM in the slow- and fast-light regimes and how they are related to the physical parameters of the pulses and waveguide. Finally, we illustrate how these results can be used to design waveguides with optimized FWM conversion efficiency.

  12. Enhanced light absorption by mixed source black and brown carbon particles in UK winter

    PubMed Central

    Liu, Shang; Aiken, Allison C.; Gorkowski, Kyle; Dubey, Manvendra K.; Cappa, Christopher D.; Williams, Leah R.; Herndon, Scott C.; Massoli, Paola; Fortner, Edward C.; Chhabra, Puneet S.; Brooks, William A.; Onasch, Timothy B.; Jayne, John T.; Worsnop, Douglas R.; China, Swarup; Sharma, Noopur; Mazzoleni, Claudio; Xu, Lu; Ng, Nga L.; Liu, Dantong; Allan, James D.; Lee, James D.; Fleming, Zoë L.; Mohr, Claudia; Zotter, Peter; Szidat, Sönke; Prévôt, André S. H.

    2015-01-01

    Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC's light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ∼1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC's warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. We conclude that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models. PMID:26419204

  13. Enhanced light absorption by mixed source black and brown carbon particles in UK winter.

    PubMed

    Liu, Shang; Aiken, Allison C; Gorkowski, Kyle; Dubey, Manvendra K; Cappa, Christopher D; Williams, Leah R; Herndon, Scott C; Massoli, Paola; Fortner, Edward C; Chhabra, Puneet S; Brooks, William A; Onasch, Timothy B; Jayne, John T; Worsnop, Douglas R; China, Swarup; Sharma, Noopur; Mazzoleni, Claudio; Xu, Lu; Ng, Nga L; Liu, Dantong; Allan, James D; Lee, James D; Fleming, Zoë L; Mohr, Claudia; Zotter, Peter; Szidat, Sönke; Prévôt, André S H

    2015-09-30

    Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC's light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ∼1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC's warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. We conclude that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models.

  14. The use of visible light and metal oxide nano particles for pathogen inactivation

    NASA Astrophysics Data System (ADS)

    Lubart, R.; Lipovski, A.; Gedanken, A.

    2012-09-01

    Since the effectiveness of antibiotic treatment is decreasing due to the development of resistant strains, alternative approaches for destroying microorganisms are needed. In this review we summarize new technologies that might be effective for pathogen inactivation. In the past we found that intense blue light could be used for bacterial eradication. The phototoxic effect correlated with the amount of reactive oxygen species (ROS) generated by the bacteria due to illumination. Recently it has been shown that the effect of light can be enhanced by introducing metal oxide nanoparticles (nps) to the bacteria prior to irradiation. This led us to suggest combining nanoparticles with visible light irradiation for pathogen eradication. We have shown that combination of illumination with the nanoparticles (ZnO or TiO2) resulted in a marked increase in the reduction of bacterial viability to a mean reduction of 80-90% for both nanoaprticles. As a matter of fact metal oxide nps alone can be used for bacteria destruction. The advantage of our approach is the use of lower concentrations of nps, combined with reduced light intensity that is less toxic to the host tissue. To further avoid the toxicity of metal oxides nps on healthy tissue it is possible to coat their surfaces with various substrates including ceramics and polymers. Recently Zinc oxide nanoparticles have been synthesized and deposited on the surface of cotton fabrics using ultrasound irradiation. Thus in the future we will try to treat infected wounds with transparent bandages coated with ZnO that will be applied to the wounds prior to irradiation.

  15. Fast valve

    DOEpatents

    Van Dyke, W.J.

    1992-04-07

    A fast valve is disclosed that can close on the order of 7 milliseconds. It is closed by the force of a compressed air spring with the moving parts of the valve designed to be of very light weight and the valve gate being of wedge shaped with O-ring sealed faces to provide sealing contact without metal to metal contact. The combination of the O-ring seal and an air cushion create a soft final movement of the valve closure to prevent the fast air acting valve from having a harsh closing. 4 figs.

  16. Fast valve

    DOEpatents

    Van Dyke, William J.

    1992-01-01

    A fast valve is disclosed that can close on the order of 7 milliseconds. It is closed by the force of a compressed air spring with the moving parts of the valve designed to be of very light weight and the valve gate being of wedge shaped with O-ring sealed faces to provide sealing contact without metal to metal contact. The combination of the O-ring seal and an air cushion create a soft final movement of the valve closure to prevent the fast air acting valve from having a harsh closing.

  17. Kinetic energy deficit in the symmetric fission of /sup 259/Md. [Light particle emission in /sup 256/Fm fission

    SciTech Connect

    Hulet, E.K.; Wild, J.F.; Lougheed, R.W.; Baisden, P.A.; Dougan, R.J.; Mustafa, M.G.

    1980-10-01

    The fragment energies of about 725 coincidence events have now been observed in the spontaneous fission (SF) decay of 105-min /sup 259/Md since its discovery in 1977. The fission of /sup 259/Md is characterized by a symmetric mass distribution, similar to those of /sup 258/Fm and /sup 259/Fm, but with a broad total kinetic energy (anti TKE) distribution which peaks at about 195 MeV, in contrast to those of /sup 258/Fm and /sup 259/Fm, for which the anti TKE is about 240 MeV. This kinetic energy deficit, approx. 40 MeV, has been postulated to be due to the emission of hydrogen-like particles by /sup 259/Md at the scission point in a large fraction of the fissions, leaving the residual fissioning nucleus with 100 protons. The residual nucleus would then be able to divide into two ultrastable tin-like fission fragments, but with less kinetic energy than that observed in the SF of /sup 258/Fm and /sup 259/Fm, because of binding-energy losses and a reduction in the Coulomb repulsion of the major fragments. To test this hypothesis, counter-telescope experiments aimed at detecting and identifying these light particles were performed. In 439 SF events 3 + 3 protons of the appropriate energy were observed, too few to account for the kinetic energy deficit in the fission of /sup 259/Md. There seems to be no explanation for this problem within the framework of current fission theory. These results are discussed along with preliminary measurements of light-particle emission in the SF of /sup 256/Fm. 5 figures.

  18. Fast HPLC for quality control of Harpagophytum procumbens by using a monolithic silica column: method transfer from conventional particle-based silica column.

    PubMed

    Schmidt, Alexander H

    2005-05-06

    The applicability of a monolithic C18-bonded silica column for the rapid HPLC separation of ingredients in medicinal plants and their phytopharmaceutical preparations has been evaluated in the author's laboratory. In this presentation, an existing method for the determination of the iridoid glycoside harpagoside in Harpagophytum procumbens (Devil's Claw) was successfully transferred from a conventional particle-based C18 silica column to a monolithic silica column. The very high porosity of the stationary phase allows chromatography with a much lower backpressure than on conventional columns. Therefore, the flow rate could be easily increased from 0.8 mL/min (particle-based column) to 5 mL/min (monolithic column) and the run-time reduced from 30 to 5 min (that is a reduction about 85% !), without losing any chromatographic resolution of the compound of interest. The amount of harpagoside was measured with the original method on a conventional particle-based silica column and on the adapted method on a monolithic silica column. The statistical mean t-test showed no significant differences of the variances and the means indicating that the fast HPLC method is an acceptable alternative. The shorter analysis time makes the method very valuable for commercial quality control of Harpagophytum extracts and its pharmaceutical preparations.

  19. Ultra-fast alterations in mRNA levels uncover multiple players in light stress acclimation in plants.

    PubMed

    Suzuki, Nobuhiro; Devireddy, Amith R; Inupakutika, Madhuri A; Baxter, Aaron; Miller, Gad; Song, Luhua; Shulaev, Elena; Azad, Rajeev K; Shulaev, Vladimir; Mittler, Ron

    2015-11-01

    The acclimation of plants to changes in light intensity requires rapid responses at several different levels. These include biochemical and biophysical responses as well as alterations in the steady-state level of different transcripts and proteins. Recent studies utilizing promoter::reporter constructs suggested that transcriptional responses to changes in light intensity could occur within seconds, rates for which changes in mRNA expression are not routinely measured or functionally studied. To identify and characterize rapid changes in the steady-state level of different transcripts in response to light stress we performed RNA sequencing analysis of Arabidopsis thaliana plants subjected to light stress. Here we report that mRNA accumulation of 731 transcripts occurs as early as 20-60 sec following light stress application, and that at least five of these early response transcripts play an important biological role in the acclimation of plants to light stress. More than 20% of transcripts accumulating in plants within 20-60 sec of initiation of light stress are H2 O2 - and ABA-response transcripts, and the accumulation of several of these transcripts is inhibited by transcriptional inhibitors. In accordance with the association of rapid response transcripts with H2 O2 and ABA signaling, a mutant impaired in ABA sensing (abi-1) was found to be more tolerant to light stress, and the response of several of the rapid response transcripts was altered in mutants impaired in reactive oxygen metabolism. Our findings reveal that transcriptome reprogramming in plants could occur within seconds of initiation of abiotic stress and that this response could invoke known as well as unknown proteins and pathways.

  20. Fast and high-fidelity optical initialization of spin state of an electron in a semiconductor quantum dot using light-hole-trion states

    NASA Astrophysics Data System (ADS)

    Kumar, Parvendra; Nakajima, Takashi

    2016-07-01

    We theoretically show that under the Faraday geometry fast and high-fidelity optical initialization of electron spin (ES) state in a semiconductor quantum dot (SQD) can be realized by utilizing the light-hole (LH)-trion states. Initialization is completed within the time scale of ten nanoseconds with high fidelity, and the initialization laser pulse can be linearly, right-circularly, or left-circularly polarized. Moreover, we demonstrate that the time required for initialization can be further shortened down to a few hundreds of picoseconds if we introduce a pillar-microcavity to promote the relaxation of a LH-trion state towards the desired ES state through the Purcell effect. We also clarify the role of heavy-hole and light-hole mixing induced transitions on the fidelity of ES state initialization.