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Sample records for spot size pulsed

  1. Damage threshold from large retinal spot size repetitive-pulse laser exposures.

    Science.gov (United States)

    Lund, Brian J; Lund, David J; Edsall, Peter R

    2014-10-01

    The retinal damage thresholds for large spot size, multiple-pulse exposures to a Q-switched, frequency doubled Nd:YAG laser (532 nm wavelength, 7 ns pulses) have been measured for 100 μm and 500 μm retinal irradiance diameters. The ED50, expressed as energy per pulse, varies only weakly with the number of pulses, n, for these extended spot sizes. The previously reported threshold for a multiple-pulse exposure for a 900 μm retinal spot size also shows the same weak dependence on the number of pulses. The multiple-pulse ED50 for an extended spot-size exposure does not follow the n dependence exhibited by small spot size exposures produced by a collimated beam. Curves derived by using probability-summation models provide a better fit to the data.

  2. Spot size and pulse number dependence of femtosecond laser ablation thresholds of silicon and stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Armbruster, Oskar; Naghilou, Aida [University of Vienna, Department of Physical Chemistry, Währinger Straße 42, A-1090 Vienna (Austria); Kitzler, Markus [TU Wien, Photonics Institute, Gusshausstraße 27-29, A-1040 Vienna (Austria); Kautek, Wolfgang, E-mail: wolfgang.kautek@univie.ac.at [University of Vienna, Department of Physical Chemistry, Währinger Straße 42, A-1090 Vienna (Austria)

    2017-02-28

    Highlights: • Influence of laser spot size and pulse number on the ablation of solids. • An extended defect model describes the dependence of the threshold fluence on the basis of high and low density defects. • Successfully applied to silicon and stainless steel. - Abstract: Laser spot size and pulse number are two major parameters influencing the ablation of solids. The extended defect model describes the dependence of the threshold fluence on the basis of high and low density defects. This model was successfully applied to silicon and stainless steel. It is demonstrated that heat accumulation cannot describe the experimental results.

  3. Retinal response of Macaca mulatta to picosecond laser pulses of varying energy and spot size.

    Science.gov (United States)

    Roach, William P; Cain, Clarence P; Narayan, Drew G; Noojin, Gary D; Boppart, Stephen A; Birngruber, Reginald; Fujimoto, James G; Toth, Cynthia A

    2004-01-01

    We investigate the relationship between the laser beam at the retina (spot size) and the extent of retinal injury from single ultrashort laser pulses. From previous studies it is believed that the retinal effect of single 3-ps laser pulses should vary in extent and location, depending on the occurrence of laser-induced breakdown (LIB) at the site of laser delivery. Single 3-ps pulses of 580-nm laser energy are delivered over a range of spot sizes to the retina of Macaca mulatta. The retinal response is captured sequentially with optical coherence tomography (OCT). The in vivo OCT images and the extent of pathology on final microscopic sections of the laser site are compared. With delivery of a laser pulse with peak irradiance greater than that required for LIB, OCT and light micrographs demonstrate inner retinal injury with many intraretinal and/or vitreous hemorrhages. In contrast, broad outer retinal injury with minimal to no choriocapillaris effect is seen after delivery of laser pulses to a larger retinal area (60 to 300 microm diam) when peak irradiance is less than that required for LIB. The broader lesions extend into the inner retina when higher energy delivery produces intraretinal injury. Microscopic examination of stained fixed tissues provide better resolution of retinal morphology than OCT. OCT provides less resolution but could be guided over an in vivo, visible retinal lesion for repeated sampling over time during the evolution of the lesion formation. For 3-ps visible wavelength laser pulses, varying the spot size and laser energy directly affects the extent of retinal injury. This again is believed to be partly due to the onset of LIB, as seen in previous studies. Spot-size dependence should be considered when comparing studies of retinal effects or when pursuing a specific retinal effect from ultrashort laser pulses. Copyright 2004 Society of Photo-Optical Instrumentation Engineers.

  4. Real-time spot size camera for pulsed high-energy radiographic machines

    International Nuclear Information System (INIS)

    Watson, S.A.

    1993-01-01

    The focal spot size of an x-ray source is a critical parameter which degrades resolution in a flash radiograph. For best results, a small round focal spot is required. Therefore, a fast and accurate measurement of the spot size is highly desirable to facilitate machine tuning. This paper describes two systems developed for Los Alamos National Laboratory's Pulsed High-Energy Radiographic Machine Emitting X-rays (PHERMEX) facility. The first uses a CCD camera combined with high-brightness floors, while the second utilizes phosphor storage screens. Other techniques typically record only the line spread function on radiographic film, while systems in this paper measure the more general two-dimensional point-spread function and associated modulation transfer function in real time for shot-to-shot comparison

  5. The influence of the laser spot size and the pulse number on laser-induced backside wet etching

    International Nuclear Information System (INIS)

    Boehme, R.; Zimmer, K.

    2005-01-01

    The laser-induced backside wet etching (LIBWE) of transparent solids at the interface to absorbing liquid is a new promising method for laser microstructuring. The influence of the laser spot size and the applied pulse number to the etch rate were investigated in detail for fused silica and two different liquids. Additional to the significant rise of the etch rate with increasing spot size considerable incubation effects have been observed at low laser fluences and pulse numbers. Based on the bubble formation during LIBWE processing, a relation between the bubble collapse time and the etch rate was ascertained. This relation fits the etch rate dependence on the spot size well. It is assumed that the deposition of decomposition products from the bubble accounts for the spot size influence the etch rate

  6. Simulation of eye-tracker latency, spot size, and ablation pulse depth on the correction of higher order wavefront aberrations with scanning spot laser systems.

    Science.gov (United States)

    Bueeler, Michael; Mrochen, Michael

    2005-01-01

    The aim of this theoretical work was to investigate the robustness of scanning spot laser treatments with different laser spot diameters and peak ablation depths in case of incomplete compensation of eye movements due to eye-tracker latency. Scanning spot corrections of 3rd to 5th Zernike order wavefront errors were numerically simulated. Measured eye-movement data were used to calculate the positioning error of each laser shot assuming eye-tracker latencies of 0, 5, 30, and 100 ms, and for the case of no eye tracking. The single spot ablation depth ranged from 0.25 to 1.0 microm and the spot diameter from 250 to 1000 microm. The quality of the ablation was rated by the postoperative surface variance and the Strehl intensity ratio, which was calculated after a low-pass filter was applied to simulate epithelial surface smoothing. Treatments performed with nearly ideal eye tracking (latency approximately 0) provide the best results with a small laser spot (0.25 mm) and a small ablation depth (250 microm). However, combinations of a large spot diameter (1000 microm) and a small ablation depth per pulse (0.25 microm) yield the better results for latencies above a certain threshold to be determined specifically. Treatments performed with tracker latencies in the order of 100 ms yield similar results as treatments done completely without eye-movement compensation. CONCWSIONS: Reduction of spot diameter was shown to make the correction more susceptible to eye movement induced error. A smaller spot size is only beneficial when eye movement is neutralized with a tracking system with a latency <5 ms.

  7. Porcine skin visible lesion thresholds for near-infrared lasers including modeling at two pulse durations and spot sizes.

    Science.gov (United States)

    Cain, C P; Polhamus, G D; Roach, W P; Stolarski, D J; Schuster, K J; Stockton, K L; Rockwell, B A; Chen, Bo; Welch, A J

    2006-01-01

    With the advent of such systems as the airborne laser and advanced tactical laser, high-energy lasers that use 1315-nm wavelengths in the near-infrared band will soon present a new laser safety challenge to armed forces and civilian populations. Experiments in nonhuman primates using this wavelength have demonstrated a range of ocular injuries, including corneal, lenticular, and retinal lesions as a function of pulse duration. American National Standards Institute (ANSI) laser safety standards have traditionally been based on experimental data, and there is scant data for this wavelength. We are reporting minimum visible lesion (MVL) threshold measurements using a porcine skin model for two different pulse durations and spot sizes for this wavelength. We also compare our measurements to results from our model based on the heat transfer equation and rate process equation, together with actual temperature measurements on the skin surface using a high-speed infrared camera. Our MVL-ED50 thresholds for long pulses (350 micros) at 24-h postexposure are measured to be 99 and 83 J cm(-2) for spot sizes of 0.7 and 1.3 mm diam, respectively. Q-switched laser pulses of 50 ns have a lower threshold of 11 J cm(-2) for a 5-mm-diam top-hat laser pulse.

  8. Long-term clinical evaluation of a 800-nm long-pulsed diode laser with a large spot size and vacuum-assisted suction for hair removal.

    Science.gov (United States)

    Ibrahimi, Omar A; Kilmer, Suzanne L

    2012-06-01

    The long-pulsed diode (800-810-nm) laser is one of the most commonly used and effective lasers for hair removal. Limitations of currently available devices include a small treatment spot size, treatment-associated pain, and the need for skin cooling. To evaluate the long-term hair reduction capabilities of a long-pulsed diode laser with a large spot size and vacuum assisted suction. Thirty-five subjects were enrolled in a prospective, self-controlled, single-center study of axillary hair removal. The study consisted of three treatments using a long-pulsed diode laser with a large spot size and vacuum-assisted suction at 4- to 6-week intervals with follow-up visits 6 and 15 months after the last treatment. Hair clearance was quantified using macro hair-count photographs taken at baseline and at 6- and 15-month follow-up visits. Changes in hair thickness and color, levels of treatment-associated pain, and adverse events were additional study endpoints. There was statistically significant hair clearance at the 6 (54%) and 15-month (42%) follow-up visits. Remaining hairs were thinner and lighter at the 15-month follow-up visit, and the majority of subjects reported feeling up to mild to moderate pain during treatment without the use of pretreatment anesthesia or skin cooling. A long-pulsed diode laser with a large spot size and vacuum-assisted suction is safe and effective for long-term hair removal. This is the largest prospective study to evaluate long-term hair removal and the first to quantify decreases in hair thickness and darkness with treatment. © 2012 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

  9. Efficacy and Safety of Hair Removal with a Long-Pulsed Diode Laser Depending on the Spot Size: A Randomized, Evaluators-Blinded, Left-Right Study.

    Science.gov (United States)

    Jo, Seong Jin; Kim, Jin Yong; Ban, Juhee; Lee, Youngjoo; Kwon, Ohsang; Koh, Wooseok

    2015-10-01

    The efficacy of the long-pulsed diode laser (LPDL) in hair removal is determined with various physical parameters. Recently, LPDLs with a larger spot size are commercially available; however, the independent effect of spot size on hair removal has not been studied. This study aimed to compare the efficacy of the LPDL in hair removal depending on the spot size. A randomized, evaluators-blind, intrapatient comparison (left vs. right) trial was designed. Ten healthy Korean women received three hair removal treatment sessions on both armpits with the 805-nm LPDL and followed for 3 months. A 10×10 mm handpiece (D1) or a 10×30 mm handpiece (D3) was randomly assigned to the right or left axilla. The fluence, pulse duration, and epidermal cooling temperature were identical for both armpits. Hair clearance was quantified with high-resolution photos taken at each visit. Postprocedural pain was quantified on a visual analogue scale. Adverse events were evaluated by physical examination and the patients' self-report. The mean hair clearance at 3 months after three treatment sessions was 38.7% and 50.1% on the armpits treated with D1 and D3, respectively (p=0.028). Procedural pain was significantly greater in the side treated with D3 (p=0.009). Serious adverse events were not observed. Given that the pulse duration, fluence, and epidermal cooling were identical, the 805-nm LPDL at the three times larger spot size showed an efficacy improvement of 29.5% in axillary hair removal without serious adverse events.

  10. In Vivo Investigation of the Safety and Efficacy of Pulsed Dye Laser with Two Spot Sizes in Port-Wine Stain Treatment: A Prospective Side-by-Side Comparison.

    Science.gov (United States)

    Yu, Wenxin; Ying, Hanru; Chen, Yijie; Qiu, Yajing; Chen, Hui; Jin, Yunbo; Yang, Xi; Wang, Tianyou; Ma, Gang; Lin, Xiaoxi

    2017-09-01

    Pulsed dye laser (PDL) with 7 and 10 mm spot sizes is widely used on a regular basis for the treatment of port-wine stain (PWS). No studies have reported on the differences in efficacy outcomes resulting from the use of different laser spot sizes in the treatment of PWS by PDL. Thus, an in vivo investigation into the differences in safety and efficacy of treatment between two spot sizes (7 vs. 10 mm) of PWS by PDL was conducted. A total of 35 PWS patients underwent three treatment sessions by using a 595 nm wavelength PDL (Vbeam ® , Candela Corp) with two laser settings: (1) 7 mm spot size, radiant exposure of 12 J/cm 2 and (2) 10 mm spot size, radiant exposure of 10 J/cm 2 . Cryogen spray cooling and 1.5 msec pulse duration were applied. Therapeutic outcomes were evaluated by visual and chromametric evaluation 3 months after the final treatment. Average blanching rates were 34.03% and 36.51% at sites treated by PDL with 7 and 10 mm laser spot sizes, respectively (p spot sizes were similar. PDL with a 10 mm laser spot size is more efficacious with lower radiant exposure than PDL with a 7 mm spot size; it can also reduce the treatment time.

  11. Crack imaging by pulsed laser spot thermography

    International Nuclear Information System (INIS)

    Li, T; Almond, D P; Rees, D A S; Weekes, B

    2010-01-01

    A surface crack close to a spot heated by a laser beam impedes lateral heat flow and produces alterations to the shape of the thermal image of the spot that can be monitored by thermography. A full 3D simulation has been developed to simulate heat flow from a laser heated spot in the proximity of a crack. The modelling provided an understanding of the ways that different parameters affect the thermal images of laser heated spots. It also assisted in the development of an efficient image processing strategy for extracting the scanned cracks. Experimental results show that scanning pulsed laser spot thermography has considerable potential as a remote, non-contact crack imaging technique.

  12. Dynamically variable spot size laser system

    Science.gov (United States)

    Gradl, Paul R. (Inventor); Hurst, John F. (Inventor); Middleton, James R. (Inventor)

    2012-01-01

    A Dynamically Variable Spot Size (DVSS) laser system for bonding metal components includes an elongated housing containing a light entry aperture coupled to a laser beam transmission cable and a light exit aperture. A plurality of lenses contained within the housing focus a laser beam from the light entry aperture through the light exit aperture. The lenses may be dynamically adjusted to vary the spot size of the laser. A plurality of interoperable safety devices, including a manually depressible interlock switch, an internal proximity sensor, a remotely operated potentiometer, a remotely activated toggle and a power supply interlock, prevent activation of the laser and DVSS laser system if each safety device does not provide a closed circuit. The remotely operated potentiometer also provides continuous variability in laser energy output.

  13. Evaluation of actual vs expected photodynamic therapy spot size.

    Science.gov (United States)

    Ranchod, Tushar M; Brucker, Alexander J; Liu, Chengcheng; Cukras, Catherine A; Hopkins, Tim B; Ying, Gui-Shuang

    2009-05-01

    To determine the accuracy of the photodynamic therapy (PDT) laser spot size on the retina as generated by 2 Food and Drug Administration (FDA)-approved lasers. Prospective observational case series. Fundus photographs were taken of 1 eye of each of 10 subjects with the WinStation 4000 fundus photography system (OIS; Ophthalmic Imaging Systems, Sacramento, California, USA); disc size was calculated using OIS software. Slit-lamp photographs were taken of the PDT laser spot focused on the retina adjacent to the optic disc, using various spot sizes in combination with 3 different contact lenses and 2 different lasers. Spot size at the retina was determined by measuring the ratio of disc diameter to spot diameter in Adobe Photoshop (San Jose, California, USA) and applying this ratio to the OIS disc measurements. Spot size at the retina averaged 87% of expected spot size for the Coherent Opal laser (Coherent Inc, Santa Clara, California, USA) and 104% of expected spot size for the Zeiss Visulas laser (Carl Zeiss Meditec Inc, Dublin, California, USA)(P = .002). Multivariate analysis demonstrated that percentage of expected spot size decreased with larger spot diameter (P = .01 for Coherent laser; P = .02 for Zeiss laser). PDT spot size at the retina appears to be consistently smaller than expected for the Coherent laser while the spot size was consistently within 10% of expected size for the Zeiss laser. The deviation from expected size increased with larger spot size using the Coherent laser.

  14. Statistical analysis of the sizes and velocities of laser hot spots of smoothed beams

    International Nuclear Information System (INIS)

    Garnier, J.; Videau, L.

    2001-01-01

    This paper presents a precise description of the characteristics of the hot spots of a partially coherent laser pulse. The average values of the sizes and velocities of the hot spots are computed, as well as the corresponding probability density functions. Applications to the speckle patterns generated by optical smoothing techniques for uniform irradiation in plasma physics are discussed

  15. Morphological changes in ultrafast laser ablation plumes with varying spot size.

    Science.gov (United States)

    Harilal, S S; Diwakar, P K; Polek, M P; Phillips, M C

    2015-06-15

    We investigated the role of spot size on plume morphology during ultrafast laser ablation of metal targets. Our results show that the spatial features of fs LA plumes are strongly dependent on the focal spot size. Two-dimensional self-emission images showed that the shape of the ultrafast laser ablation plumes changes from spherical to cylindrical with an increasing spot size from 100 to 600 μm. The changes in plume morphology and internal structures are related to ion emission dynamics from the plasma, where broader angular ion distribution and faster ions are noticed for the smallest spot size used. The present results clearly show that the morphological changes in the plume with spot size are independent of laser pulse width.

  16. Effect of laser spot size on fusion neutron yield in laser–deuterium cluster interactions

    International Nuclear Information System (INIS)

    Chen Guanglong; Lu Haiyang; Wang Cheng; Liu Jiansheng; Li Ruxin; Ni Guoquan; Xu Zhizhan

    2008-01-01

    The effect of the laser spot size on the neutron yield of table-top nuclear fusion from explosions of a femtosecond intense laser pulse heated deuterium clusters is investigated by using a simplified model, in which the cluster size distribution and the energy attenuation of the laser as it propagates through the cluster jet are taken into account. It has been found that there exists a proper laser spot size for the maximum fusion neutron yield for a given laser pulse and a specific deuterium gas cluster jet. The proper spot size, which is dependent on the laser parameters and the cluster jet parameters, has been calculated and compared with the available experimental data. A reasonable agreement between the calculated results and the published experimental results is found

  17. Spot size dependence of laser accelerated protons in thin multi-ion foils

    International Nuclear Information System (INIS)

    Liu, Tung-Chang; Shao, Xi; Liu, Chuan-Sheng; Eliasson, Bengt; Wang, Jyhpyng; Chen, Shih-Hung

    2014-01-01

    We present a numerical study of the effect of the laser spot size of a circularly polarized laser beam on the energy of quasi-monoenergetic protons in laser proton acceleration using a thin carbon-hydrogen foil. The used proton acceleration scheme is a combination of laser radiation pressure and shielded Coulomb repulsion due to the carbon ions. We observe that the spot size plays a crucial role in determining the net charge of the electron-shielded carbon ion foil and consequently the efficiency of proton acceleration. Using a laser pulse with fixed input energy and pulse length impinging on a carbon-hydrogen foil, a laser beam with smaller spot sizes can generate higher energy but fewer quasi-monoenergetic protons. We studied the scaling of the proton energy with respect to the laser spot size and obtained an optimal spot size for maximum proton energy flux. Using the optimal spot size, we can generate an 80 MeV quasi-monoenergetic proton beam containing more than 10 8 protons using a laser beam with power 250 TW and energy 10 J and a target of thickness 0.15 wavelength and 49 critical density made of 90% carbon and 10% hydrogen

  18. Time Resolved X-Ray Spot Size Diagnostic

    CERN Document Server

    Richardson, Roger; Falabella, Steven; Guethlein, Gary; Raymond, Brett; Weir, John

    2005-01-01

    A diagnostic was developed for the determination of temporal history of an X-ray spot. A pair of thin (0.5 mm) slits image the x-ray spot to a fast scintillator which is coupled to a fast detector, thus sampling a slice of the X-Ray spot. Two other scintillator/detectors are used to determine the position of the spot and total forward dose. The slit signal is normalized to the dose and the resulting signal is analyzed to get the spot size. The position information is used to compensate for small changes due to spot motion and misalignment. The time resolution of the diagnostic is about 1 ns and measures spots from 0.5 mm to over 3 mm. The theory and equations used to calculate spot size and position are presented, as well as data. The calculations assume a symmetric, Gaussian spot. The spot data is generated by the ETA II accelerator, a 2kA, 5.5 MeV, 60ns electron beam focused on a Tantalum target. The spot generated is typically about 1 mm FWHM. Comparisons are made to an X-ray pinhole camera which images th...

  19. SU-E-T-510: Interplay Between Spots Sizes, Spot / Line Spacing and Motion in Spot Scanning Proton Therapy

    International Nuclear Information System (INIS)

    Lee, TK

    2015-01-01

    Purpose In proton beam configuration for spot scanning proton therapy (SSPT), one can define the spacing between spots and lines of scanning as a ratio of given spot size. If the spacing increases, the number of spots decreases which can potentially decrease scan time, and so can whole treatment time, and vice versa. However, if the spacing is too large, the uniformity of scanned field decreases. Also, the field uniformity can be affected by motion during SSPT beam delivery. In the present study, the interplay between spot/ line spacing and motion is investigated. Methods We used four Gaussian-shape spot sizes with 0.5cm, 1.0cm, 1.5cm, and 2.0cm FWHM, three spot/line spacing that creates uniform field profile which are 1/3*FWHM, σ/3*FWHM and 2/3*FWHM, and three random motion amplitudes within, +/−0.3mm, +/−0.5mm, and +/−1.0mm. We planned with 2Gy uniform single layer of 10×10cm2 and 20×20cm2 fields. Then, mean dose within 80% area of given field size, contrubuting MU per each spot assuming 1cGy/MU calibration for all spot sizes, number of spots and uniformity were calculated. Results The plans with spot/line spacing equal to or smaller than 2/3*FWHM without motion create ∼100% uniformity. However, it was found that the uniformity decreases with increased spacing, and it is more pronounced with smaller spot sizes, but is not affected by scanned field sizes. Conclusion It was found that the motion during proton beam delivery can alter the dose uniformity and the amount of alteration changes with spot size which changes with energy and spot/line spacing. Currently, robust evaluation in TPS (e.g. Eclipse system) performs range uncertainty evaluation using isocenter shift and CT calibration error. Based on presented study, it is recommended to add interplay effect evaluation to robust evaluation process. For future study, the additional interplay between the energy layers and motion is expected to present volumetric effect

  20. Holes generation in glass using large spot femtosecond laser pulses

    Science.gov (United States)

    Berg, Yuval; Kotler, Zvi; Shacham-Diamand, Yosi

    2018-03-01

    We demonstrate high-throughput, symmetrical, holes generation in fused silica glass using a large spot size, femtosecond IR-laser irradiation which modifies the glass properties and yields an enhanced chemical etching rate. The process relies on a balanced interplay between the nonlinear Kerr effect and multiphoton absorption in the glass which translates into symmetrical glass modification and increased etching rate. The use of a large laser spot size makes it possible to process thick glasses at high speeds over a large area. We have demonstrated such fabricated holes with an aspect ratio of 1:10 in a 1 mm thick glass samples.

  1. On the relationships between electron spot size, focal spot size, and virtual source position in Monte Carlo simulations

    International Nuclear Information System (INIS)

    Sterpin, E.; Chen, Y.; Lu, W.; Mackie, T. R.; Olivera, G. H.; Vynckier, S.

    2011-01-01

    Purpose: Every year, new radiotherapy techniques including stereotactic radiosurgery using linear accelerators give rise to new applications of Monte Carlo (MC) modeling. Accurate modeling requires knowing the size of the electron spot, one of the few parameters to tune in MC models. The resolution of integrated megavoltage imaging systems, such as the tomotherapy system, strongly depends on the photon spot size which is closely related to the electron spot. The aim of this article is to clarify the relationship between the electron spot size and the photon spot size (i.e., the focal spot size) for typical incident electron beam energies and target thicknesses. Methods: Three electron energies (3, 5.5, and 18 MeV), four electron spot sizes (FWHM=0, 0.5, 1, and 1.5 mm), and two tungsten target thicknesses (0.15 and 1 cm) were considered. The formation of the photon beam within the target was analyzed through electron energy deposition with depth, as well as photon production at several phase-space planes placed perpendicular to the beam axis, where only photons recorded for the first time were accounted for. Photon production was considered for ''newborn'' photons intersecting a 45x45 cm 2 plane at the isocenter (85 cm from source). Finally, virtual source position and ''effective'' focal spot size were computed by backprojecting all the photons from the bottom of the target intersecting a 45x45 cm 2 plane. The virtual source position and focal spot size were estimated at the plane position where the latter is minimal. Results: In the relevant case of considering only photons intersecting the 45x45 cm 2 plane, the results unambiguously showed that the effective photon spot is created within the first 0.25 mm of the target and that electron and focal spots may be assumed to be equal within 3-4%. Conclusions: In a good approximation photon spot size equals electron spot size for high energy X-ray treatments delivered by linear accelerators.

  2. SpotCaliper: fast wavelet-based spot detection with accurate size estimation.

    Science.gov (United States)

    Püspöki, Zsuzsanna; Sage, Daniel; Ward, John Paul; Unser, Michael

    2016-04-15

    SpotCaliper is a novel wavelet-based image-analysis software providing a fast automatic detection scheme for circular patterns (spots), combined with the precise estimation of their size. It is implemented as an ImageJ plugin with a friendly user interface. The user is allowed to edit the results by modifying the measurements (in a semi-automated way), extract data for further analysis. The fine tuning of the detections includes the possibility of adjusting or removing the original detections, as well as adding further spots. The main advantage of the software is its ability to capture the size of spots in a fast and accurate way. http://bigwww.epfl.ch/algorithms/spotcaliper/ zsuzsanna.puspoki@epfl.ch Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  3. The effect of laser unit on photodynamic therapy spot size.

    Science.gov (United States)

    Ansari-Shahrezaei, Siamak; Binder, Susanne; Stur, Michael

    2011-01-01

    To determine the effect of the laser unit on photodynamic therapy (PDT) spot size. A calibrated Gullstrand-type model eye was used for this study. The axial length of the model eye was set to different values ranging from 22.2 to 27.0 mm, and the actual spot size from the laser console was recorded for treating a spot of 4 mm in the center of the artificial fundus using two different laser units (Coherent Opal laser; Coherent Inc, Santa Clara, California, USA and Zeiss Visulas laser; Carl Zeiss Meditec Inc, Dublin, California, USA) and two indirect contact laser lenses (Volk PDT laser lens and Volk Area Centralis lens; Volk Optical Inc, Mentor, Ohio, USA). From myopia to hyperopia, the total deviation from the intended spot size was -22.5% to -7.5% (Opal laser and PDT laser lens), and -17.5% to +2.5% (Visulas laser and PDT laser lens), -12.5% to +7.5% (Opal laser and Area Centralis lens), and -7.5% to +10% (Visulas laser and Area Centralis lens). The used laser unit has a significant effect on PDT spot size in this model. These findings may be important for optimizing PDT of choroidal neovascular lesions.

  4. Newborn screening blood spot analysis in the UK: influence of spot size, punch location and haematocrit.

    Science.gov (United States)

    Lawson, A J; Bernstone, L; Hall, S K

    2016-03-01

    In dried blood spot analysis, punch location and variations in applied sample volume and haematocrit can produce different measured concentrations of analytes. We investigated the magnitude of these effects in newborn screening in the UK. Heparinized blood spiked with thyroid stimulating hormone (TSH), phenylalanine, tyrosine, leucine, methionine, octanoyl carnitine (C8), and immunoreactive trypsinogen (IRT) was spotted onto filter paper: (i) at a constant haematocrit of 50% at various volumes, and (ii) at a range of haematocrits using a constant volume. Subpunches (3.2 mm) of the dried blood spots were then analysed. Compared with a central punch from a 50 µL blood spot with 50% haematocrit, 10 µL spots can have significantly lower measured concentrations of all analytes, with decreases of 15% or more observed for leucine, methionine, phenylalanine, and tyrosine. Punching at the edge of a spot can increase measured concentrations up to 35%. Higher haematocrit decreased measured TSH and C8 yet increased amino acids and IRT by 15% compared with 50% haematocrit. Lower haematocrits had the opposite effect, but only with higher concentrations of some analytes. Differences in blood spot size, haematocrit and punch location substantially affect measured concentrations for analytes used in the UK newborn screening programme, and this could affect false positive and negative rates. To minimize analytical bias, these variables should be controlled or adjusted for where possible. © The Author(s) 2015.

  5. Assessment of Nugget Size of Spot Weld using Neutron Radiography

    Directory of Open Access Journals (Sweden)

    Triyono

    2011-08-01

    Full Text Available Resistance spot welding (RSW has been widely used for many years in the fabrication of car body structures, mainly due to the cost and time considerations. The weld quality as well as the nugget size is an issue in various manufacturing and processes due to the strong link between the weld quality and safety. It has led to the development of various destructive and non-destructive tests for spot welding such as peel testing, ultrasonic inspections, digital shearography, and infrared thermography. However, such methods cannot show spot weld nugget visually and the results are very operator’s skill dependent. The present work proposes a method to visualize the nugget size of spot welds using neutron radiography. Water, oil and various concentrations of gadolinium oxide-alcohol mixture were evaluated as a contrast media to obtain the best quality of radiography. Results show that mixture of 5 g gadolinium oxide (Gd2O3 in 25 ml alcohol produces the best contrast. It provides the possibility to visualize the shape and size of the nugget spot weld. Furthermore, it can discriminate between nugget and corona bond. The result of neutron radiography evaluation shows reasonable agreement with that of destructive test.

  6. Measurements of plasma mirror reflectivity and focal spot quality for tens of picosecond laser pulses

    Science.gov (United States)

    Forestier-Colleoni, Pierre; Williams, Jackson; Scott, Graeme; Mariscal, Dereck. A.; McGuffey, Christopher; Beg, Farhat N.; Chen, Hui; Neely, David; Ma, Tammy

    2017-10-01

    The Advanced Radiographic Capability (ARC) laser at the NIF (LLNL) is high-energy ( 4 kJ) with a pulse length of 30ps, and is capable of focusing to an intensity of 1018W/cm2 with a 100 μm focal spot. The ARC laser is at an intensity which can be used to produce proton beams. However, for applications such as radiography and warm dense matter creation, a higher laser intensity may be desired to generate more energetic proton beams. One possibility to increase the intensity is to decrease the focused spot size by employing a smaller f-number optic. But it is difficult to implement such an optic or to bring the final focusing parabola closer to the target within the complicated NIF chamber geometry. A proposal is to use ellipsoidal plasma mirrors (PM) for fast focusing of the ARC laser light, thereby increasing the peak intensity. There is uncertainty, however, in the survivability and reflectivity of PM at such long pulse durations. Here, we show experimental results from the Titan laser to study the reflectivity of flat PM as a function of laser pulse length. A calorimeter was used to measure the PM reflectivity. We also observed degradation of the far and near field energy distribution of the laser after the reflection by the PM for pulse-lengths beyond 10ps. Contract DE-AC52-07NA27344. Funded by the LLNL LDRD program: tracking code 17-ERD-039.

  7. First Beam Test of Nanometer Spot Size Monitor Using Laser Interferometry

    CERN Document Server

    Walz, D

    2003-01-01

    The nanometer spot size monitor based on the laser interferometry (Laser-Compton Spot Size Monitor) has been tested in FFTB beam line at SLAC. A low emittance beam of 46 GeV electrons, provided by the two-mile linear accelerator, was focused into nanometer spot in the FFTB line, and its transverse dimensions were precisely measured by the spot size monitor.

  8. First Beam Test of Nanometer Spot Size Monitor Using Laser Interferometry

    International Nuclear Information System (INIS)

    Walz, Dieter R

    2003-01-01

    The nanometer spot size monitor based on the laser interferometry (Laser-Compton Spot Size Monitor) has been tested in FFTB beam line at SLAC. A low emittance beam of 46 GeV electrons, provided by the two-mile linear accelerator, was focused into nanometer spot in the FFTB line, and its transverse dimensions were precisely measured by the spot size monitor

  9. Tuning temperature and size of hot spots and hot-spot arrays.

    Science.gov (United States)

    Saïdi, Elika; Babinet, Nicolas; Lalouat, Loïc; Lesueur, Jérôme; Aigouy, Lionel; Volz, Sébastian; Labéguerie-Egéa, Jessica; Mortier, Michel

    2011-01-17

    By using scanning thermal microscopy, it is shown that nanoscale constrictions in metallic microwires deposited on an oxidized silicon substrate can be tuned in terms of temperature and confinement size. High-resolution temperature maps indeed show that submicrometer hot spots and hot-spot arrays are obtained when the SiO(2) layer thickness decreases below 100 nm. When the SiO(2) thickness becomes larger, heat is less confined in the vicinity of the constrictions and laterally spreads all along the microwire. These results are in good agreement with numerical simulations, which provide dependences between silica-layer thickness and nanodot shape and temperature. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Using the ultra-long pulse width pulsed dye laser and elliptical spot to treat resistant nasal telangiectasia.

    Science.gov (United States)

    Madan, Vishal; Ferguson, Janice

    2010-01-01

    Thick linear telangiectasia on the ala nasi and nasolabial crease can be resistant to treatment with the potassium-titanyl-phosphate (KTP) laser and the traditional round spot on a pulsed dye laser (PDL). We evaluated the efficacy of a 3 mm x 10 mm elliptical spot using the ultra-long pulse width on a Candela Vbeam(R) PDL for treatment of PDL- and KTP laser-resistant nasal telangiectasia. Nasal telangiectasia resistant to PDL (12 patients) and KTP laser (12 patients) in 18 patients were treated with a 3 mm x 10 mm elliptical spot on the ultra-long pulse pulsed dye laser (ULPDL) utilising long pulse width [595 nm, 40 ms, double pulse, 30:20 dynamic cooling device (DCD)]. Six patients had previously received treatment with both PDL and KTP laser prior to ULPDL (40 treatments, range1-4, mean 2.2). Complete clearance was seen in ten patients, and eight patients displayed more than 80% improvement after ULPDL treatment. Self-limiting purpura occurred with round spot PDL and erythema with KTP laser and ULPDL. Subtle linear furrows along the treatment sites were seen in three patients treated with the KTP laser. ULPDL treatment delivered using a 3 mm x 10 mm elliptical spot was non-purpuric and highly effective in the treatment of nasal telangiectasia resistant to KTP laser and PDL.

  11. Effect of ambient humidity on the rate at which blood spots dry and the size of the spot produced.

    Science.gov (United States)

    Denniff, Philip; Woodford, Lynsey; Spooner, Neil

    2013-08-01

    For shipping and storage, dried blood spot (DBS) samples must be sufficiently dry to protect the integrity of the sample. When the blood is spotted the humidity has the potential to affect the size of the spot created and the speed at which it dries. The area of DBS produced on three types of substrates were not affected by the humidity under which they were generated. DBS samples reached a steady moisture content 150 min after spotting and 90 min for humidities less than 60% relative humidity. All packaging materials examined provided some degree of protection from external extreme conditions. However, none of the packaging examined provided a total moisture barrier to extreme environmental conditions. Humidity was shown not to affect the spot area and DBS samples were ready for shipping and storage 2 h after spotting. The packing solutions examined all provided good protection from external high humidity conditions.

  12. X-ray tube focal spot sizes: comprehensive studies of their measurement and effect of measured size in angiography

    International Nuclear Information System (INIS)

    Doi, K.; Loo, L.N.; Chan, H.P.

    1982-01-01

    Thirty-two focal spot sizes of four x-ray tubes were measured by the pinhole, star pattern, slit, and root-mean-square (RMS) methods under various exposure conditions. The modulation transfer functions (MTFs) and line spread functions (LSFs) were also determined. The star pattern focal spot sizes agreed with the effective sizes calculated from the frequencies at the first minimum of the MTF within 0.04 mm for large focal spots and within 0.01 mm for small focal spots. The focal spot size determined by the slit method was approximately equal to the width of the LSF at the cutoff level of 0.15 +/- 0.06 of the peak value. The RMS method provided the best correlation between the measured focal spot sizes and the corresponding image distributions of blood vessels. The pinhole and slit methods tended to overestimate the focal spot size, but the star pattern method tended to underestimate it. For approximately 90% of the focal spots, the average of the star and slit (or pinhole) focal spot sizes agreed with the RMS focal spot size within +/- 0.1 mm

  13. Effects of spot size and spot spacing on lateral penumbra reduction when using a dynamic collimation system for spot scanning proton therapy

    International Nuclear Information System (INIS)

    Hyer, Daniel E; Hill, Patrick M; Wang, Dongxu; Smith, Blake R; Flynn, Ryan T

    2014-01-01

    The purpose of this work was to investigate the reduction in lateral dose penumbra that can be achieved when using a dynamic collimation system (DCS) for spot scanning proton therapy as a function of two beam parameters: spot size and spot spacing. This is an important investigation as both values impact the achievable dose distribution and a wide range of values currently exist depending on delivery hardware. Treatment plans were created both with and without the DCS for in-air spot sizes (σ air ) of 3, 5, 7, and 9 mm as well as spot spacing intervals of 2, 4, 6 and 8 mm. Compared to un-collimated treatment plans, the plans created with the DCS yielded a reduction in the mean dose to normal tissue surrounding the target of 26.2–40.6% for spot sizes of 3–9 mm, respectively. Increasing the spot spacing resulted in a decrease in the time penalty associated with using the DCS that was approximately proportional to the reduction in the number of rows in the raster delivery pattern. We conclude that dose distributions achievable when using the DCS are comparable to those only attainable with much smaller initial spot sizes, suggesting that the goal of improving high dose conformity may be achieved by either utilizing a DCS or by improving beam line optics. (note)

  14. Motion Interplay as a Function of Patient Parameters and Spot Size in Spot Scanning Proton Therapy for Lung Cancer

    Science.gov (United States)

    Grassberger, Clemens; Dowdell, Stephen; Lomax, Antony; Sharp, Greg; Shackleford, James; Choi, Noah; Willers, Henning; Paganetti, Harald

    2013-01-01

    Purpose Quantify the impact of respiratory motion on the treatment of lung tumors with spot scanning proton therapy. Methods and Materials 4D Monte Carlo simulations were used to assess the interplay effect, which results from relative motion of the tumor and the proton beam, on the dose distribution in the patient. Ten patients with varying tumor sizes (2.6-82.3cc) and motion amplitudes (3-30mm) were included in the study. We investigated the impact of the spot size, which varies between proton facilities, and studied single fractions and conventionally fractionated treatments. The following metrics were used in the analysis: minimum/maximum/mean dose, target dose homogeneity and 2-year local control rate (2y-LC). Results Respiratory motion reduces the target dose homogeneity, with the largest effects observed for the highest motion amplitudes. Smaller spot sizes (σ≈3mm) are inherently more sensitive to motion, decreasing target dose homogeneity on average by a factor ~2.8 compared to a larger spot size (σ≈13mm). Using a smaller spot size to treat a tumor with 30mm motion amplitude reduces the minimum dose to 44.7% of the prescribed dose, decreasing modeled 2y-LC from 87.0% to 2.7%, assuming a single fraction. Conventional fractionation partly mitigates this reduction, yielding a 2y-LC of 71.6%. For the large spot size, conventional fractionation increases target dose homogeneity and prevents a deterioration of 2y-LC for all patients. No correlation with tumor volume is observed. The effect on the normal lung dose distribution is minimal: observed changes in mean lung dose and lung V20 are interplay using a large spot size and conventional fractionation. For treatments employing smaller spot sizes and/or in the delivery of single fractions, interplay effects can lead to significant deterioration of the dose distribution and lower 2y-LC. PMID:23462423

  15. Stabilization of electron beam spot size by self bias potential

    International Nuclear Information System (INIS)

    Kwan, T.J.T.; Moir, D.C.; Snell, C.M.; Kang, M.

    1998-01-01

    In high resolution flash x-ray imaging technology the electric field developed between the electron beam and the converter target is large enough to draw ions from the target surface. The ions provide fractional neutralization and cause the electron beam to focus radially inward, and the focal point subsequently moves upstream due to the expansion of the ion column. A self-bias target concept is proposed and verified via computer simulation that the electron charge deposited on the target can generate an electric potential, which can effectively limit the ion motion and thereby stabilize the growth of the spot size. A target chamber using the self bias target concept was designed and tested in the Integrated Test Stand (ITS). The authors have obtained good agreement between computer simulation and experiment

  16. The Influence of spot size on the expansion dynamics of nanosecond-laser-produced copper plasmas in atmosphere

    International Nuclear Information System (INIS)

    Li, Xingwen; Wei, Wenfu; Wu, Jian; Jia, Shenli; Qiu, Aici

    2013-01-01

    Laser produced copper plasmas of different spot sizes in air were investigated using fast photography and optical emission spectroscopy (OES). The laser energy was 33 mJ. There were dramatic changes in the plasma plume expansion into the ambient air when spot sizes changed from ∼0.1 mm to ∼0.6 mm. A stream-like structure and a hemispherical structure were, respectively, observed. It appeared that the same spot size resulted in similar expansion dynamics no matter whether the target was located in the front of or behind the focal point, although laser-induced air breakdown sometimes occurred in the latter case. Plasma plume front positions agree well with the classic blast wave model for the large spot-size cases, while an unexpected stagnation of ∼80 ns occurred after the laser pulse ends for the small spot size cases. This stagnation can be understood in terms of the evolution of enhanced plasma shielding effects near the plasma front. Axial distributions of plasma components by OES revealed a good confinement effect. Electron number densities were estimated and interpreted using the recorded Intensified Charge Coupled Device (ICCD) images.

  17. Impact of spot size on plan quality of spot scanning proton radiosurgery for peripheral brain lesions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dongxu, E-mail: dongxu-wang@uiowa.edu; Dirksen, Blake; Hyer, Daniel E.; Buatti, John M.; Sheybani, Arshin; Dinges, Eric; Felderman, Nicole; TenNapel, Mindi; Bayouth, John E.; Flynn, Ryan T. [Department of Radiation Oncology, University of Iowa, Iowa City, Iowa 52242 (United States)

    2014-12-15

    Purpose: To determine the plan quality of proton spot scanning (SS) radiosurgery as a function of spot size (in-air sigma) in comparison to x-ray radiosurgery for treating peripheral brain lesions. Methods: Single-field optimized (SFO) proton SS plans with sigma ranging from 1 to 8 mm, cone-based x-ray radiosurgery (Cone), and x-ray volumetric modulated arc therapy (VMAT) plans were generated for 11 patients. Plans were evaluated using secondary cancer risk and brain necrosis normal tissue complication probability (NTCP). Results: For all patients, secondary cancer is a negligible risk compared to brain necrosis NTCP. Secondary cancer risk was lower in proton SS plans than in photon plans regardless of spot size (p = 0.001). Brain necrosis NTCP increased monotonically from an average of 2.34/100 (range 0.42/100–4.49/100) to 6.05/100 (range 1.38/100–11.6/100) as sigma increased from 1 to 8 mm, compared to the average of 6.01/100 (range 0.82/100–11.5/100) for Cone and 5.22/100 (range 1.37/100–8.00/100) for VMAT. An in-air sigma less than 4.3 mm was required for proton SS plans to reduce NTCP over photon techniques for the cohort of patients studied with statistical significance (p = 0.0186). Proton SS plans with in-air sigma larger than 7.1 mm had significantly greater brain necrosis NTCP than photon techniques (p = 0.0322). Conclusions: For treating peripheral brain lesions—where proton therapy would be expected to have the greatest depth-dose advantage over photon therapy—the lateral penumbra strongly impacts the SS plan quality relative to photon techniques: proton beamlet sigma at patient surface must be small (<7.1 mm for three-beam single-field optimized SS plans) in order to achieve comparable or smaller brain necrosis NTCP relative to photon radiosurgery techniques. Achieving such small in-air sigma values at low energy (<70 MeV) is a major technological challenge in commercially available proton therapy systems.

  18. Impact of spot size on plan quality of spot scanning proton radiosurgery for peripheral brain lesions

    International Nuclear Information System (INIS)

    Wang, Dongxu; Dirksen, Blake; Hyer, Daniel E.; Buatti, John M.; Sheybani, Arshin; Dinges, Eric; Felderman, Nicole; TenNapel, Mindi; Bayouth, John E.; Flynn, Ryan T.

    2014-01-01

    Purpose: To determine the plan quality of proton spot scanning (SS) radiosurgery as a function of spot size (in-air sigma) in comparison to x-ray radiosurgery for treating peripheral brain lesions. Methods: Single-field optimized (SFO) proton SS plans with sigma ranging from 1 to 8 mm, cone-based x-ray radiosurgery (Cone), and x-ray volumetric modulated arc therapy (VMAT) plans were generated for 11 patients. Plans were evaluated using secondary cancer risk and brain necrosis normal tissue complication probability (NTCP). Results: For all patients, secondary cancer is a negligible risk compared to brain necrosis NTCP. Secondary cancer risk was lower in proton SS plans than in photon plans regardless of spot size (p = 0.001). Brain necrosis NTCP increased monotonically from an average of 2.34/100 (range 0.42/100–4.49/100) to 6.05/100 (range 1.38/100–11.6/100) as sigma increased from 1 to 8 mm, compared to the average of 6.01/100 (range 0.82/100–11.5/100) for Cone and 5.22/100 (range 1.37/100–8.00/100) for VMAT. An in-air sigma less than 4.3 mm was required for proton SS plans to reduce NTCP over photon techniques for the cohort of patients studied with statistical significance (p = 0.0186). Proton SS plans with in-air sigma larger than 7.1 mm had significantly greater brain necrosis NTCP than photon techniques (p = 0.0322). Conclusions: For treating peripheral brain lesions—where proton therapy would be expected to have the greatest depth-dose advantage over photon therapy—the lateral penumbra strongly impacts the SS plan quality relative to photon techniques: proton beamlet sigma at patient surface must be small (<7.1 mm for three-beam single-field optimized SS plans) in order to achieve comparable or smaller brain necrosis NTCP relative to photon radiosurgery techniques. Achieving such small in-air sigma values at low energy (<70 MeV) is a major technological challenge in commercially available proton therapy systems

  19. Effect of laser spot size on energy balance in laser induced plasmas

    International Nuclear Information System (INIS)

    Pant, H.C.; Sharma, S.; Bhawalkar, D.D.

    1980-01-01

    The effect of the laser spot size on laser light absorption in laser induced plasmas from solid targets was studied. It was found that at a constant laser intensity on the target, reduction in the laser spot size enhances the net laser energy absorption. It was also observed that the laser light reflection from the target becomes more diffused when the focal spot size is reduced

  20. Determination of pulse profile characteristics of multi spot retinal photocoagulation lasers.

    Science.gov (United States)

    Clarkson, Douglas McG; Makhzoum, Osama; Blackburn, John

    2015-10-01

    A system is described for determination of discrete pulse train characteristics of multi spot laser delivery systems for retinal photocoagulation. While photodiodes provide an ideal detection mechanism, measurement artifacts can potentially be introduced by the spatial pattern of the delivered beam relative to a discrete photodiode element. This problem was overcome by use of an integrating sphere to produce a uniform light field at the site of the photodiode detector. A basic current driven photodiode detection circuit incorporating an operational amplifier was used to generate a signal captured by a commercially available USB interface device at a rate of 10 kHz. Studies were undertaken of a Topcon Pascal Streamline laser system with output at a wavelength of 577 nm (yellow). This laser features the proprietary feature of 'Endpoint Management' ™ where pulses can be delivered as 100% of set energy levels with visible reaction on the retina and also at a reduced energy level to create potentially non visible but clinically effective lesions. Using the pulse train measurement device it was identified that the 'Endpoint Management' ™ delivery mode of pulses of lower energy was achieved by reducing the pulse duration of pulses for non-visible effect pulses while maintaining consistent beam power levels within the delivered pulse profile. The effect of eye geometry in determining safety and effectiveness of multi spot laser delivery for retinal photocoagulation is discussed. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

  1. Motion Interplay as a Function of Patient Parameters and Spot Size in Spot Scanning Proton Therapy for Lung Cancer

    International Nuclear Information System (INIS)

    Grassberger, Clemens; Dowdell, Stephen; Lomax, Antony; Sharp, Greg; Shackleford, James; Choi, Noah; Willers, Henning; Paganetti, Harald

    2013-01-01

    Purpose: To quantify the impact of respiratory motion on the treatment of lung tumors with spot scanning proton therapy. Methods and Materials: Four-dimensional Monte Carlo simulations were used to assess the interplay effect, which results from relative motion of the tumor and the proton beam, on the dose distribution in the patient. Ten patients with varying tumor sizes (2.6-82.3 cc) and motion amplitudes (3-30 mm) were included in the study. We investigated the impact of the spot size, which varies between proton facilities, and studied single fractions and conventionally fractionated treatments. The following metrics were used in the analysis: minimum/maximum/mean dose, target dose homogeneity, and 2-year local control rate (2y-LC). Results: Respiratory motion reduces the target dose homogeneity, with the largest effects observed for the highest motion amplitudes. Smaller spot sizes (σ ≈ 3 mm) are inherently more sensitive to motion, decreasing target dose homogeneity on average by a factor 2.8 compared with a larger spot size (σ ≈ 13 mm). Using a smaller spot size to treat a tumor with 30-mm motion amplitude reduces the minimum dose to 44.7% of the prescribed dose, decreasing modeled 2y-LC from 87.0% to 2.7%, assuming a single fraction. Conventional fractionation partly mitigates this reduction, yielding a 2y-LC of 71.6%. For the large spot size, conventional fractionation increases target dose homogeneity and prevents a deterioration of 2y-LC for all patients. No correlation with tumor volume is observed. The effect on the normal lung dose distribution is minimal: observed changes in mean lung dose and lung V 20 are <0.6 Gy(RBE) and <1.7%, respectively. Conclusions: For the patients in this study, 2y-LC could be preserved in the presence of interplay using a large spot size and conventional fractionation. For treatments using smaller spot sizes and/or in the delivery of single fractions, interplay effects can lead to significant deterioration of the

  2. Laser Surface Modification of H13 Die Steel using Different Laser Spot Sizes

    Science.gov (United States)

    Aqida, S. N.; Naher, S.; Brabazon, D.

    2011-05-01

    This paper presents a laser surface modification process of AISI H13 tool steel using three sizes of laser spot with an aim to achieve reduced grain size and surface roughness. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). Metallographic study and image analysis were done to measure the grain size and the modified surface roughness was measured using two-dimensional surface profilometer. From metallographic study, the smallest grain sizes measured by laser modified surface were between 0.51 μm and 2.54 μm. The minimum surface roughness, Ra, recorded was 3.0 μm. This surface roughness of the modified die steel is similar to the surface quality of cast products. The grain size correlation with hardness followed the findings correlate with Hall-Petch relationship. The potential found for increase in surface hardness represents an important method to sustain tooling life.

  3. Gastrointestinal digital fluoroscopy: Comparison of digital pulsed progressive readout images with 100-mm spot films

    International Nuclear Information System (INIS)

    Steiner, E.; Ferrucci, J.T.; Mueller, P.R.; Hahn, P.F.

    1987-01-01

    New developments in pulsed progressive readout (PPR) techniques allow short, extremely intense pulses of radiation to be used to produce a latent image which is then progressively read off the video camera and placed in 1,024 x 1,024-pixel digital storage. The resulting image is produced by a 10-20-msec pulse, reducing motion artifact to below that achievable with conventional spot film techniques, with a potential for 50%-95% dose reduction. This technique of reducing motion artifact is ideal for digital applications in gastrointestinal radiology. The authors compared 10-mm spot films and PPR digital radiographs of 86 anatomic regions in 43 patients undergoing routine barium enema and cholangiographic examinations. Parameters evaluated included display of normal and pathologic features, image contrast, and resolution. The benefits of the PPR technique include postprocessing to evaluate low contrast region and the potential for significant dose reduction

  4. Sweet Spot Size in Virtual Sound Reproduction: A Temporal Analysis

    DEFF Research Database (Denmark)

    Lacouture Parodi, Yesenia; Rubak, Per

    2009-01-01

    The influence of head misalignments on the performance of binaural reproduction systems through loudspeakers is often evaluated in the frequency domain. The changes in magnitude give us an idea of how much of the crosstalk is leaked into the direct signal and therefore a sweet spot performance can......-correlation we estimate the interaural time delay and define a sweet spot. The analysis is based on measurements carried out on 21 different loudspeaker configurations, including two- and four-channels arrangements. Results show that closely spaced loudspeakers are more robust to lateral displacements than wider...... span angles. Additionally, the sweet spot as a function of head rotations increases systematically when the loudspeakers are placed at elevated positions....

  5. An investigation of the dynamic separation of spot welds under plane tensile pulses

    International Nuclear Information System (INIS)

    Ma, Bohan; Fan, Chunlei; Chen, Danian; Wang, Huanran; Zhou, Fenghua

    2014-01-01

    We performed ultra-high-speed tests for purely opening spot welds using plane tensile pulses. A gun system generated a parallel impact of a projectile plate onto a welded plate. Induced by the interactions of the release waves, the welded plate opened purely under the plane tensile pulses. We used the laser velocity interferometer system for any reflector to measure the velocity histories of the free surfaces of the free part and the spot weld of the welded plate. We then used a scanning electron microscope to investigate the recovered welded plates. We found that the interfacial failure mode was mainly a brittle fracture and the cracks propagated through the spot nugget, while the partial interfacial failure mode was a mixed fracture comprised ductile fracture and brittle fracture. We used the measured velocity histories to evaluate the tension stresses in the free part and the spot weld of the welded plate by applying the characteristic theory. We also discussed the different constitutive behaviors of the metals under plane shock loading and under uniaxial split Hopkinson pressure bar tests. We then compared the numerically simulated velocity histories of the free surfaces of the free part and the spot weld of the welded plate with the measured results. The numerical simulations made use of the fracture stress criteria, and then the computed fracture modes of the tests were compared with the recovered results

  6. Effect on spot welding variables on nugget size and bond strength of 304 austenitic stainless steel

    International Nuclear Information System (INIS)

    Charde, Nachimani

    2012-01-01

    Resistance spot welding (RSW) has revolutionized mechanical assembly in the automotive industry since its introduction in the early 1970s. Currently, one mechanical assembly in five is welded using spot welding technology, with welding of stainless steel sheet becoming increasingly common. Consequently, this research paper examines the spot welding of 2 mm thick 304 austenitic stainless steel sheet. The size of a spot weld nugget is primarily determined by the welding parameters: welding current, welding time, electrode force and electrode tip diameter However, other factors such as electrode deformation, corrosion, dissimilar materials and material properties also affect the nugget size and shape. This paper analyzes only the effects of current, weld time and force variations with unchanged electrode tip diameter. A pneumatically driven 75kVA spot welder was used to accomplish the welding process and the welded samples were subjected to tensile, hardness and metallurgical testing to characterize the size and shape of the weld nugget and the bond strength.

  7. Use of pre-pulse in laser spot welding of materials with high optical reflection

    Science.gov (United States)

    Mys, Ihor; Geiger, Manfred

    2003-11-01

    Laser micro welding has become a standard manufacturing technique, particularly in industry sectors, such as automotive and aerospace electronics or medical devices, where the requirements for strength, miniaturization and temperature resistance are constantly rising. So far the use of laser micro welding is limited due to the fluctuation of the quality of the welded joints, because the welding results for material with high optical reflection and thermal conductivity, such as copper and copper alloys, depend very strongly on the condition of the material surface. This paper presents investigations on the use of a laser pre-pulse in spot welding of electronic materials with Nd:YAG laser. In order to achieve reproducible joining results two strategies are followed-up. The first one utilizes a reflection-based process control for measuring the reflection during the short pre-pulse. The intensity of the reflected light is used to calculate an appropriated welding pulse power, which corresponds to the measured relative absorption. Adjustment of laser parameters according to the condition of the surface is done in real time before laser main pulse. A second possibility for the stabilization of copper welding is the employment of a short and powerful laser pre-pulse before laser main pulse. This pre-pulse affects the workpiece surface and creates more reproducible absorption conditions for the main pulse, independent from the initial situation on material surface.

  8. Angle dependent focal spot size of a conical X-ray target

    International Nuclear Information System (INIS)

    Saeed Raza, Hamid; Jin Kim, Hyun; Nam Kim, Hyun; Oh Cho, Sung

    2015-01-01

    Misaligned phantoms may severely affect the focal spot calculations. A method is proposed to determine the geometry of the X-ray target and the position of the image radiograph around the X-ray target to get a relatively smaller focal spot size. Results reveal that the focal spot size is not always isotropic around the target but it decreases as the point of observation shifts radially away from the center line of the conical X-ray target. This research will help in producing high quality X-ray images in multi-directions by properly aligning the phantoms and the radiograph tallies. - Highlights: • Misaligned phantoms may severely affect the focal spot calculations. • The aim of this research is to analyze systematically the angle dependent behavior of the focal spot size around a conical shaped X-ray target. • A general purpose Monte Carlo (MCNP5) computer code is used to achieve a relatively small focal spot size. • Angular distribution of the X-ray focal spot size mainly depends on the angular orientation of the phantom and its aligned FIR tally. • This research will help in producing high quality X-ray images in multi-directions

  9. Long-term Comparison of a Large Spot Vacuum Assisted Handpiece vs the Small Spot Size Traditional Handpiece of the 800 nm Diode Laser.

    Science.gov (United States)

    Youssef, Nour J; Rizk, Alain G; Ibrahimi, Omar A; Tannous, Zeina S

    2017-09-01

    BACKGROUND The 800 nm long-pulsed diode laser machine is safe and effective for permanent hair reduction. Traditionally, most long-pulsed diode lasers used for hair removal had a relatively small spot size. Recently, a long-pulsed diode laser with a large spot size and vacuum assisted suction handpiece was introduced. The treatment parameters of each type of handpiece differ. Short and long-term clinical efficacy, treatment associated pain, and patient satisfaction are important factors to be considered. This study aims to conduct a direct head to head comparison of both handpieces of the 800nm long-pulsed diode laser by evaluating long term hair reduction, treatment associated pain and patient satisfaction. Thirteen subjects were enrolled in this prospective, self-controlled, single-center study of axillary laser hair removal. The study involved 4 treatments using a long pulsed diode laser with a large spot size HS handpiece (single pass), HS handpiece (double pass), and a small spot size ET handpiece according to a randomized choice. The treatment sessions were done at 4-8 week intervals with follow up visits taken at 6 and 12 months after the last treatment session. Hair clearance and thickness analysis were assessed using macro hair count photographs taken at baseline visit, at each treatment session visit and at follow up visits. Other factors including pain, treatment duration, and patients' preference were secondary study endpoints. At 6 months follow up visits after receiving four laser treatments, there was statistically significant hair clearance in the three treatment arms with 66.1 % mean percentage hair reduction with the ET handpiece, 43.6% with the HSS (single pass) and 64.1 % with the HSD (double). However, at one year follow up, the results significantly varied from the 6 months follow up. The mean percentage hair reduction was 57.8% with the ET handpiece treated axillas (n=9), 16.5% with the HSS (single pass) handpiece treated axillas (n=7), and

  10. Experiments of Nanometer Spot Size Monitor at FETB Using Laser Interferometry

    CERN Document Server

    Walz, D

    2003-01-01

    The nanometer spot size monitor based on the laser interferometry has been developed and installed in the final focus test beam (FFTB) line at SLAC. The beam experiments started in September 1993, the first fringe pattern from the monitor was observed in the beginning of April 1994, then the small vertical spot around 70 nm was observed in May 1994. The spot size monitor has been routinely used for tuning the beam optics in FFTB. Basic principle of this monitor has been well proved, and its high performance as a precise beam monitor in nanometer range has been demonstrated.

  11. Methods for studying the focal spot size and resolution of diagnostic X-ray tubes

    International Nuclear Information System (INIS)

    Fairbanks, R.; Doust, C.

    1979-01-01

    Attention is given to techniques appropriate for use in the clinical situation. The focal spot size is critical to geometric unsharpness and hence the quality of the finished radiograph, but pinhole imaging of the focal spot is extremely difficult in clinical practice. The resolution of an X-ray tube, although a function of focal spot size, is of more importance in radiography. A comparison is made of various resolution grids suitable for quality control use in X-ray departments. (U.K.)

  12. Controlling semiconductor nanoparticle size distributions with tailored ultrashort pulses

    International Nuclear Information System (INIS)

    Hergenroeder, R; Miclea, M; Hommes, V

    2006-01-01

    The laser generation of size-controlled semiconductor nanoparticle formation under gas phase conditions is investigated. It is shown that the size distribution can be changed if picosecond pulse sequences of tailored ultra short laser pulses (<200 fs) are employed. By delivering the laser energy in small packages, a temporal energy flux control at the target surface is achieved, which results in the control of the thermodynamic pathway the material takes. The concept is tested with silicon and germanium, both materials with a predictable response to double pulse sequences, which allows deduction of the materials' response to complicated pulse sequences. An automatic, adaptive learning algorithm was employed to demonstrate a future strategy that enables the definition of more complex optimization targets such as particle size on materials less predictable than semiconductors

  13. A long pulse modulator for reduced size and cost

    International Nuclear Information System (INIS)

    Pfeffer, H.; Bartelson, L.; Bourkland, K.; Jensen, C.; Kerns, Q.; Prieto, P.; Saewert, G.; Wolff, D.

    1994-07-01

    A novel modulator has been designed, built and tested for the TESLA test facility. This e + e - accelerator concept uses superconducting RF cavities and requires 2ms of RF power at 10 pps. As the final accelerator will require several hundred modulators, a cost effective, space saving and high efficiency design is desired. This modulator used a modest size switched capacitor bank that droops approximately 20% during the pulse. This large droop is compensated for by the use of a resonant LC circuit. The capacitor bank is connected to the high side of a pulse transformer primary using a series GTO switch. The resonant circuit is connected to the low side of the pulse transformer primary. The output pulse is flat to within 1% for 1.9 ms during a 2.3 ms base pulse width. Measured efficiency, from breaker to klystron and including energy lost in the rise time, is approximately 85%

  14. Limitations of interaction-point spot-size tuning at the SLC

    International Nuclear Information System (INIS)

    Emma, P.; Hendrickson, L.J.; Zimmermann, F.; Raimondi, P.

    1997-05-01

    At the Stanford Linear Collider (SLC), the interaction-point spot size is minimized by repeatedly correcting, for both beams, various low-order optical aberrations, such as dispersion, waist position or coupling. These corrections are performed about every 8 hours, by minimizing the IP spot size while exciting different orthogonal combinations of final-focus magnets. The spot size itself is determined by measuring the beam deflection angle as a function of the beam-beam separation. Additional information is derived from the energy loss due to beamstrahlung and from luminosity-related signals. In the 1996 SLC run, the typical corrections were so large as to imply a 20-40% average luminosity loss due to residual uncompensated or fluctuating tunable aberrations. In this paper, the authors explore the origin of these large tuning corrections and study possible mitigations for the next SLC run

  15. ATF2 spot size tuning using the rotation matrix

    CERN Document Server

    Scarfe, A; Jones, J K; Angal-Kalinin, D

    2010-01-01

    The Accelerator Test Facility (ATF2) at KEK aims to experimentally verify the local chromaticity correction scheme to achieve a vertical beam size of 37nm. The facility is a scaled down version of the final focus design proposed for the future linear colliders. In order to achieve this goal, high precision tuning methods are being developed. One of the methods proposed for ATF2 is a novel method known as the ‘rotation matrix’ method. Details of the development and testing of this method, including orthogonality optimisation and simulation methods, are presented.

  16. Effect of axial length on laser spot size during photodynamic therapy: an experimental study in monkeys.

    Science.gov (United States)

    Kondo, Mineo; Ito, Yasuki; Miyata, Kentaro; Kondo, Nagako; Ishikawa, Kohei; Terasaki, Hiroko

    2006-01-01

    To investigate the effect of shorter axial length on the laser spot size and laser energy during photodynamic therapy (PDT) in monkeys. Experimental study with four rhesus monkeys. PDT was performed on the normal retina of monkeys whose ocular axial lengths are shorter (19.55 to 20.25 mm) than that of humans. After the PDT, the eyes were enucleated, and the diameter of the irradiated laser spot was measured with a microcaliper. The area of actual laser spot was only 0.56 to 0.61 times of the planned area, which indicated that the laser energy/area was 1.64 to 1.78 times more intense than planned initially. These results are the in vivo demonstration that the diameter of PDT laser spot is smaller for eyes with shorter axial lengths.

  17. Coupling effects of refractive index discontinuity, spot size and spot location on the deflection sensitivity of optical-lever based atomic force microscopy

    International Nuclear Information System (INIS)

    Liu Yu; Yang Jun

    2008-01-01

    Atomic force microscopy (AFM) plays an essential role in nanotechnology and nanoscience. The recent advances of AFM in bionanotechnology include phase imaging of living cells and detection of biomolecular interactions in liquid biological environments. Deflection sensitivity is a key factor in both imaging and force measurement, which is significantly affected by the coupling effects of the refractive index discontinuity between air, the glass window and the liquid medium, and the laser spot size and spot location. The effects of both the spot size and the spot location on the sensitivity are amplified by the refractive index discontinuity. The coupling effects may govern a transition of the deflection sensitivity from enhancement to degradation. It is also found that there is a critical value for the laser spot size, above which the deflection sensitivity is mainly determined by the refractive index of the liquid. Experimental results, in agreement with theoretical predication, elucidate the coupling effects

  18. Comparison of different methods for determining the size of a focal spot of microfocus X-ray tubes

    International Nuclear Information System (INIS)

    Salamon, M.; Hanke, R.; Krueger, P.; Sukowski, F.; Uhlmann, N.; Voland, V.

    2008-01-01

    The EN 12543-5 describes a method for determining the focal spot size of microfocus X-ray tubes up to a minimum spot size of 5 μm. The wide application of X-ray tubes with even smaller focal spot sizes in computed tomography and radioscopy applications requires the evaluation of existing methods for focal spot sizes below 5 μm. In addition, new methods and conditions for determining submicron focal spot sizes have to be developed. For the evaluation and extension of the present methods to smaller focal spot sizes, different procedures in comparison with the existing EN 12543-5 were analyzed and applied, and the results are presented

  19. The Stiles-Crawford Effect: spot-size ratio departure in retinitis pigmentosa

    Science.gov (United States)

    Sharma, Nachieketa K.; Lakshminarayanan, Vasudevan

    2016-04-01

    The Stiles-Crawford effect of the first kind is the retina's compensative response to loss of luminance efficiency for oblique stimulation manifested as the spot-size ratio departure from the perfect power coupling for a normal human eye. In a retinitis pigmentosa eye (RP), the normal cone photoreceptor morphology is affected due to foveal cone loss and disrupted cone mosaic spatial arrangement with reduction in directional sensitivity. We show that the flattened Stiles-Crawford function (SCF) in a RP eye is due to a different spot-size ratio departure profile, that is, for the same loss of luminance efficiency, a RP eye has a smaller departure from perfect power coupling compared to a normal eye. Again, the difference in spot-size ratio departure increases from the centre towards the periphery, having zero value for axial entry and maximum value for maximum peripheral entry indicating dispersal of photoreceptor alignment which prevents the retina to go for a bigger compensative response as it lacks both in number and appropriate cone morphology to tackle the loss of luminance efficiency for oblique stimulation. The slope of departure profile also testifies to the flattened SCF for a RP eye. Moreover, the discrepancy in spot-size ratio departure between a normal and a RP eye is shown to have a direct bearing on the Stiles-Crawford diminution of visibility.

  20. Pulse measurement of the hot spot current in a NbTiN superconducting filament

    Science.gov (United States)

    Harrabi, K.; Mekki, A.; Kunwar, S.; Maneval, J. P.

    2018-02-01

    We have studied the voltage response of superconducting NbTiN filaments to a step-pulse of over-critical current I > Ic. The current induces the destruction of the Cooper pairs and initiates different mechanisms of dissipation depending on the bath temperature T. For the sample investigated, and for T above a certain T*, not far from Tc, the resistance manifests itself in the form of a phase-slip center, which turns into a normal hot spot (HS) as the step-pulse is given larger amplitudes. However, at all temperatures below T*, the destruction of superconductivity still occurs at Ic(T), but leads directly to an ever-growing HS. By lowering the current amplitude during the pulse, one can produce a steady HS and thus define a threshold HS current Ih(T). That is achieved by combining two levels of current, the first and larger one to initiate an HS, the second one to search for constant voltage response. The double diagram of the functions Ic(T) and Ih(T) was plotted in the T-range Tc/2 < T < Tc, and their crossing found at T* = (8.07 ± 0.07) K.

  1. Ablation spot area and impulse characteristics of polymers induced by burst irradiation of 1 μm laser pulses

    Science.gov (United States)

    Tsuruta, Hisashi; Dondelewski, Oskar; Katagiri, Yusuke; Wang, Bin; Sasoh, Akihiro

    2017-07-01

    The ablation spot area and impulse characteristics of various polymers were experimentally investigated against burst irradiation of Nd: YLF laser pulses with a pulse repetition frequency of 1 kHz, wavelength of 1047 nm, temporal pulse width of 10 ns, and single-pulse fluence of 6.1 J/cm2 to 17.1 J/cm2. The dependences of ablation area on the pulse energy from 0.72 to 7.48 mJ and the number of pulses from 10 pulses to 1000 pulses were investigated. In order to characterize their impulse performance as a function of fluence, which should not depend on ablation material, an effective ablation spot area was defined as that obtained against aluminum, 1050 A, as the reference material. An impulse that resulted from a single burst of 200 pulses was measured with a torsion-type impulse stand. Various impulse dependences on the fluence, which were not readily predicted from the optical properties of the material without ablation, were obtained. By fitting the experimentally measured impulse performance to Phipps and Sinko's model in the vapor regime, the effective absorption coefficient with laser ablation was evaluated, thereby resulting in three to six orders of magnitude larger than that without ablation. Among the polymers examined using polytetrafluoroethylene (PTFE) as the best volume absorbers, the highest momentum coupling coefficient of 66 μNs/J was obtained with an effective absorption coefficient more than six times smaller than that of the other polymers.

  2. Focal spot size predictions for beam transport through a gas-filled reactor

    International Nuclear Information System (INIS)

    Yu, S.S.; Lee, E.P.; Buchanan, H.L.

    1980-01-01

    Results from calculations of focal spot size for beam transport through a gas-filled reactor are summarized. In the converging beam mode, we find an enlargement of the focal spot due to multiple scattering and zeroth order self-field effects. This enlargement can be minimized by maintaining small reactors together with a careful choice of the gaseous medium. The self-focused mode, on the other hand, is relatively insensitive to the reactor environment, but is critically dependent upon initial beam quality. This requirement on beam quality can be significantly eased by the injection of an electron beam of modest current from the opposite wall

  3. Microstructural evolution and mechanical performance of resistance spot welded DP1000 steel with single and double pulse welding

    NARCIS (Netherlands)

    Chabok, Ali; van der Aa, Ellen; De Hosson, Jeff; Pei, Yutao T.

    2017-01-01

    Two welding schemes of single and double pulse were used for the resistance spot welding of DP1000 dual phase steel. The changes in the mechanical performance and variant pairing of martensite under two different welding conditions were scrutinized. It is demonstrated that, although both welds fail

  4. Added value of delayed computed tomography angiography in primary intracranial hemorrhage and hematoma size for predicting spot sign.

    Science.gov (United States)

    Wu, Te Chang; Chen, Tai Yuan; Shiue, Yow Ling; Chen, Jeon Hor; Hsieh, Tsyh-Jyi; Ko, Ching Chung; Lin, Ching Po

    2018-04-01

    Background The computed tomography angiography (CTA) spot sign represents active contrast extravasation within acute primary intracerebral hemorrhage (ICH) and is an independent predictor of hematoma expansion (HE) and poor clinical outcomes. The spot sign could be detected on first-pass CTA (fpCTA) or delayed CTA (dCTA). Purpose To investigate the additional benefits of dCTA spot sign in primary ICH and hematoma size for predicting spot sign. Material and Methods This is a retrospective study of 100 patients who underwent non-contrast CT (NCCT) and CTA within 24 h of onset of primary ICH. The presence of spot sign on fpCTA or dCTA, and hematoma size on NCCT were recorded. The spot sign on fpCTA or dCTA for predicting significant HE, in-hospital mortality, and poor clinical outcomes (mRS ≥ 4) are calculated. The hematoma size for prediction of CTA spot sign was also analyzed. Results Only the spot sign on dCTA could predict high risk of significant HE and poor clinical outcomes as on fpCTA ( P spot sign on fpCTA or dCTA in the absence of intraventricular and subarachnoid hemorrhage. Conclusion This study clarifies that dCTA imaging could improve predictive performance of CTA in primary ICH. Furthermore, the XY value is the best predictor for CTA spot sign.

  5. Pain score of patients undergoing single spot, short pulse laser versus conventional laser for diabetic retinopathy.

    Science.gov (United States)

    Mirshahi, Ahmad; Lashay, Alireza; Roozbahani, Mehdi; Fard, Masoud Aghsaei; Molaie, Saber; Mireshghi, Meysam; Zaferani, Mohamad Mehdi

    2013-04-01

    To compare pain score of single spot short duration time (20 milliseconds) panretinal photocoagulation (PRP) with conventional (100 milliseconds) PRP in diabetic retinopathy. Sixty-six eyes from 33 patients with symmetrical severe non-proliferative diabetic retinopathy (non-PDR) or proliferative diabetic retinopathy (PDR) were enrolled in this prospective randomized controlled trial. One eye of each patient was randomized to undergo conventional and the other eye to undergo short time PRP. Spot size of 200 μm was used in both laser types, and energy was adjusted to achieve moderate burn on the retina. Patients were asked to mark the level of pain felt during the PRP session for each eye on the visual analog scale (VAS) and were examined at 1 week, and at 1, 2, 4 and 6 months. Sixteen women and 17 men with mean age 58.9 ± 7.8 years were evaluated. The conventional method required a mean power of 273 ± 107 mW, whereas the short duration method needed 721 ± 406 mW (P = 0.001). An average of 1,218 ± 441 spots were delivered with the conventional method and an average of 2,125 ± 503 spots were required with the short duration method (P = 0.001). Average pain score was 7.5 ± 1.14 in conventional group and 1.75 ± 0.87 in the short duration group (P = 0.001). At 1 week, 1 month, and 4 months following PRP, the mean changes of central macular thickness (CMT) from baseline in the conventional group remained 29.2 μm (P = 0.008), 40.0 μm (P = 0.001), and 40.2 μm (P = 0.007) greater than the changes in CMT for short time group. Patient acceptance of short time single spot PRP was high, and well-tolerated in a single session by all patients. Moreover, this method is significantly less painful than but just as effective as conventional laser during 6 months of follow-up. The CMT change was more following conventional laser than short time laser.

  6. Effects of Variable Spot Size on Human Exposure to 95 GHz Millimeter Wave Energy

    Science.gov (United States)

    2017-05-11

    Laboratory. Ross, J. A., Allen, S. J., Beason, C. W., & Johnson, L. R. (2008). Power density measurement of 94-GHz radiofrequency radiation using carbon...effectiveness) at the smallest spot size. 15. SUBJECT TERMS Avoidance, behavior, millimeter waves, nonlethal weapons, radiofrequency 16...System power density measurements (mean ± standard deviation) for the three different power density settings (low, middle, high) used in Experiment 1B

  7. Development of a Dynamic Spot Size Diagnostic for Flash Radiographic X-Ray Sources

    International Nuclear Information System (INIS)

    Droemer, D. W.; Lutz, S.; Devore, D.; Rovang, D.; Portillo, S.; Maenchen, J.

    2003-01-01

    There has been considerable work in recent years in the development of high-brightness, high-dose flash x-ray radiographic sources. Spot size is one of several parameters that helps characterize source performance and provides a figure of merit to assess the suitability of various sources to specific experimental requirements. Time-integrated spot-size measurements using radiographic film and a high-Z rolled-edge object have been used for several years with great success. The Advanced Radiographic Technologies program thrust to improve diode performance requires extending both modeling and experimental measurements into the transient time domain. A new Time Resolved Spot Detector (TRSD) is under development to provide this information. In this paper we report the initial results of the performance of a 148-element scintillating fiber array that is fiber-optically coupled to a gated streak camera. Spatial and temporal resolution results are discussed and the data obtained FR-om the Sand ia National Laboratories (SNL) RITS-3 (Radiographic Integrated Test Stand) accelerator are presented

  8. Impact of focal spot size on radiologic image quality: A visual grading analysis

    Energy Technology Data Exchange (ETDEWEB)

    Gorham, Sinead [Diagnostic Imaging, Biological Imaging Research, UCD School of Medicine and Medical Science, Health Science, Belfield, UCD, Dublin 4 (Ireland); Brennan, Patrick C., E-mail: patrick.brennan@ucd.i [Diagnostic Imaging, Biological Imaging Research, UCD School of Medicine and Medical Science, Health Science, Belfield, UCD, Dublin 4 (Ireland)

    2010-11-15

    Fine and broad focal spot sizes are available on general X-ray tubes. Excessive use of fine focus can impact on tube life and whilst it is established that fine focal spot size reduces geometric unsharpness, the extent of this benefit on clinical image quality is unclear. The current cadaver-based work compares images produced with effective focal sizes of 0.8 mm and 1.8 mm. Four projection types were included, lateral ankle, antero-posterior (AP) knee, AP thoracic spine and horizontal beam lateral (HBL) lumbar spine, and a visual grading analysis was used to assess visibility of anatomical criteria. Five clinicians scored each image using a 1-4 scoring scale, a reference image was employed for standardization and a Mann-Whitney U statistical test compared results derived from each focus. Radiation doses were monitored using a dose area product (DAP) meter. Statistical analyses demonstrated no significant differences between images produced at each focus, although a relationship between body part thickness and number of criteria with a higher (non-significant) score for the fine focus compared with the broad focal spot size was demonstrated. Choice of focus had no radiation dose implications. Fine foci X-ray sources are used predominantly for extremity imaging to enhance visualization of fine detail such as trabecular patterns, yet there is no evidence to support this practice. The argument for regular employment of fine foci, particularly for the type of acquisition and display devices used in this study, needs to be revisited.

  9. Influence of transverse mode on retinal spot size and retinal injury effect: A theoretical analysis on 532-nm laser

    Directory of Open Access Journals (Sweden)

    Jia-Rui Wang

    2014-05-01

    Full Text Available The fundamental transverse mode (TEM00 is preferable for experimental and theoretical study on the laser-induced retinal injury effect, for it can produce the minimal retinal image and establish the most strict laser safety standards. But actually lasers with higher order mode were frequently used in both earlier and recent studies. Generally higher order mode leads to larger retinal spot size and so higher damage threshold, but there are few quantitative analyses on this problem. In this paper, a four-surface schematic eye model is established for human and macaque. The propagation of 532-nm laser in schematic eye is analyzed by the ABCD law of Gaussian optics. It is shown that retinal spot size increases with laser transverse mode order. For relative lower mode order, the retinal spot diameter will not exceed the minimum laser-induced retinal lesion (25 ~ 30 μm in diameter, and so has little effect on retinal damage threshold. While for higher order mode, the larger retinal spot requires more energy to induce injury and so the damage threshold increases. When beam divergence is lowered, the retinal spot size decreases correspondingly, so the effect of mode order can be compensated. The retinal spot size of macaque is slightly smaller than that of human and the ratio between them is independent of mode order. We conclude that the laser mode order has significant influence on retinal spot size but limited influence on the retinal injury effect.

  10. Quantifying spot size reduction of a 1.8 kA electron beam for flash radiography

    Science.gov (United States)

    Burris-Mog, T. J.; Moir, D. C.

    2018-03-01

    The spot size of Axis-I at the Dual Axis Radiographic Hydrodynamic Test facility was reduced by 15.5% by including a small diameter drift tube that acts to aperture the outer diameter of the electron beam. Comparing the measured values to both analytic calculations and results from a particle-in-cell model shows that one-third to one-half of the spot size reduction is due to a drop in beam emittance. We infer that one-half to two-thirds of the spot-size reduction is due to a reduction in beam-target interactions. Sources of emittance growth and the scaling of the final focal spot size with emittance and solenoid aberrations are also presented.

  11. Impact of Spot Size and Beam-Shaping Devices on the Treatment Plan Quality for Pencil Beam Scanning Proton Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Moteabbed, Maryam, E-mail: mmoteabbed@partners.org; Yock, Torunn I.; Depauw, Nicolas; Madden, Thomas M.; Kooy, Hanne M.; Paganetti, Harald

    2016-05-01

    Purpose: This study aimed to assess the clinical impact of spot size and the addition of apertures and range compensators on the treatment quality of pencil beam scanning (PBS) proton therapy and to define when PBS could improve on passive scattering proton therapy (PSPT). Methods and Materials: The patient cohort included 14 pediatric patients treated with PSPT. Six PBS plans were created and optimized for each patient using 3 spot sizes (∼12-, 5.4-, and 2.5-mm median sigma at isocenter for 90- to 230-MeV range) and adding apertures and compensators to plans with the 2 larger spots. Conformity and homogeneity indices, dose-volume histogram parameters, equivalent uniform dose (EUD), normal tissue complication probability (NTCP), and integral dose were quantified and compared with the respective PSPT plans. Results: The results clearly indicated that PBS with the largest spots does not necessarily offer a dosimetric or clinical advantage over PSPT. With comparable target coverage, the mean dose (D{sub mean}) to healthy organs was on average 6.3% larger than PSPT when using this spot size. However, adding apertures to plans with large spots improved the treatment quality by decreasing the average D{sub mean} and EUD by up to 8.6% and 3.2% of the prescribed dose, respectively. Decreasing the spot size further improved all plans, lowering the average D{sub mean} and EUD by up to 11.6% and 10.9% compared with PSPT, respectively, and eliminated the need for beam-shaping devices. The NTCP decreased with spot size and addition of apertures, with maximum reduction of 5.4% relative to PSPT. Conclusions: The added benefit of using PBS strongly depends on the delivery configurations. Facilities limited to large spot sizes (>∼8 mm median sigma at isocenter) are recommended to use apertures to reduce treatment-related toxicities, at least for complex and/or small tumors.

  12. Fine focal spot size improves image quality in computed tomography abdomen and pelvis

    Energy Technology Data Exchange (ETDEWEB)

    Goh, Yin P.; Low, Keat; Kuganesan, Ahilan [Monash Health, Diagnostic Imaging Department, 246, Clayton Road, Clayton, Victoria (Australia); Lau, Kenneth K. [Monash Health, Diagnostic Imaging Department, 246, Clayton Road, Clayton, Victoria (Australia); Monash University, Department of Medicine, Faculty of Medicine, Nursing and Health Sciences, Victoria (Australia); Buchan, Kevin [Philips Healthcare, Clinical Science, PO Box 312, Mont Albert, Victoria (Australia); Oh, Lawrence Chia Wei [Flinders Medical Centre, Division of Medical Imaging, Bedford Park South (Australia); Huynh, Minh [Swinburne University, Department of Statistics, Data Science and Epidemiology, School of Health Sciences, Faculty of Health, Arts and Design, Hawthorn (Australia)

    2016-12-15

    To compare the image quality between fine focal spot size (FFSS) and standard focal spot size (SFSS) in computed tomography of the abdomen and pelvis (CTAP) This retrospective review included all consecutive adult patients undergoing contrast-enhanced CTAP between June and September 2014. Two blinded radiologists assessed the margin clarity of the abdominal viscera and the detected lesions using a five-point grading scale. Cohen's kappa test was used to examine the inter-observer reliability between the two reviewers for organ margin clarity. Mann-Whitney U testing was utilised to assess the statistical difference of the organ and lesion margin clarity. 100 consecutive CTAPs were recruited. 52 CTAPs were examined with SFSS of 1.1 x 1.2 mm and 48 CTAPs were examined with FFSS of 0.6 x 0.7 mm. Results showed that there was substantial agreement for organ margin clarity (mean κ = 0.759, p < 0.001) among the reviewers. FFSS produces images with clearer organ margins (U = 76194.0, p < 0.001, r = 0.523) and clearer lesion margins (U = 239, p = 0.052, r = 0.269). FFSS CTAP improves image quality in terms of better organ and lesion margin clarity. Fine focus CT scanning is a novel technique that may be applied in routine CTAP imaging. (orig.)

  13. Diode laser trabeculoplasty in open angle glaucoma: 50 micron vs. 100 micron spot size.

    Science.gov (United States)

    Veljko, Andreić; Miljković, Aleksandar; Babić, Nikola

    2011-01-01

    The study was aimed at evaluating the efficacy of diode laser trabeculoplsaty in lowering intraocular pressure in patients with both primary open-angle glaucoma and exfoliation glaucoma by using different size of laser spot. This six-month, unmasked, controlled, prospective study included sixty-two patients with the same number of eyes, who were divided into two groups. Trabeculoplasty was performed with 50 micron and 100 micron laser spot size in the group I and group II, respectively. Other laser parameters were the same for both groups: the wave length of 532 nm, 0.1 second single emission with the power of 600-1200 mW was applied on the 180 degrees of the trabeculum. The mean intraocular pressure decrease in the 50 micron group (group 1) on day 7 was 24% from the baseline and after six-month follow-up period the intraocular pressure decrease was 29.8% (p < 0.001). In the 100 micron group (group II), the mean intraocular pressure decrease on day 7 was 26.5% and after six months it was 39% (p < 0.001).

  14. Using harmonic oscillators to determine the spot size of Hermite-Gaussian laser beams

    Science.gov (United States)

    Steely, Sidney L.

    1993-01-01

    The similarity of the functional forms of quantum mechanical harmonic oscillators and the modes of Hermite-Gaussian laser beams is illustrated. This functional similarity provides a direct correlation to investigate the spot size of large-order mode Hermite-Gaussian laser beams. The classical limits of a corresponding two-dimensional harmonic oscillator provide a definition of the spot size of Hermite-Gaussian laser beams. The classical limits of the harmonic oscillator provide integration limits for the photon probability densities of the laser beam modes to determine the fraction of photons detected therein. Mathematica is used to integrate the probability densities for large-order beam modes and to illustrate the functional similarities. The probabilities of detecting photons within the classical limits of Hermite-Gaussian laser beams asymptotically approach unity in the limit of large-order modes, in agreement with the Correspondence Principle. The classical limits for large-order modes include all of the nodes for Hermite Gaussian laser beams; Sturm's theorem provides a direct proof.

  15. SU-G-206-02: Impact of Focal Spot Sizes On CT Image Quality

    International Nuclear Information System (INIS)

    Bache, S; Rong, J

    2016-01-01

    Purpose: To quantify a radiology team’s assessment of image quality differences between two CT scanner models currently in clinical use, with emphasis on spatial resolution that could be impacted by focal spot size. Methods: Modulation Transfer Functions (MTF) measurements were performed by scanning the impulse source insert module of the Catphan 600 at 120/140 kVp with both large (LFS) and small (SFS) focal spots and reconstructed to 2.5mm and 5.0mm thicknesses on a GE Discovery CT750 HD and a LightSpeed VCT CT scanner. MTFs were calculated by summing the 2D PSF along one-dimension to obtain line-spread-function (LSF), and calculating the Fourier Transform of the zero-padded and background corrected LSF. Spatial resolution performance was evaluated by comparing MTF curves, 50% and 10% MTF cutoff, and total area under the MTF curve (AUC). In addition, images of the Catphan high-contrast module and a Kagaku anthropomorphic body phantom were acquired from the HD scanner for visual comparisons. Results: For each scanner model, SFS was superior to LFS spatial resolution with respect to 50%/10% MTF cutoff and AUC. For the HD, 50%/10% cutoff was 4.29/7.22cm-1 for the LFS and 4.43/7.45cm-1 for the SFS. VCT outperformed HD, with 50%/10% cutoff of 4.40/7.29 cm-1 for LFS and 4.62/7.47cm-1 for SFS. Scanner model performance in order of decreasing AUC performance was VCT SFS (7.43), HD SFS (7.20), VCT LFS (7.09) and HD LFS (6.93). Visual evaluations of Kagaku phantom images confirmed that VCT outperformed HD. Conclusion: VCT outperformed HD and small focal spot is desired for either model over large focal spot in term of spatial resolution – in agreement with radiologist feedback of overall image quality. In-depth evaluations of clinical impact and focal spot selection mechanisms is currently being assessed.

  16. Impact of Spot Size and Spacing on the Quality of Robustly Optimized Intensity Modulated Proton Therapy Plans for Lung Cancer.

    Science.gov (United States)

    Liu, Chenbin; Schild, Steven E; Chang, Joe Y; Liao, Zhongxing; Korte, Shawn; Shen, Jiajian; Ding, Xiaoning; Hu, Yanle; Kang, Yixiu; Keole, Sameer R; Sio, Terence T; Wong, William W; Sahoo, Narayan; Bues, Martin; Liu, Wei

    2018-06-01

    To investigate how spot size and spacing affect plan quality, robustness, and interplay effects of robustly optimized intensity modulated proton therapy (IMPT) for lung cancer. Two robustly optimized IMPT plans were created for 10 lung cancer patients: first by a large-spot machine with in-air energy-dependent large spot size at isocenter (σ: 6-15 mm) and spacing (1.3 σ), and second by a small-spot machine with in-air energy-dependent small spot size (σ: 2-6 mm) and spacing (5 mm). Both plans were generated by optimizing radiation dose to internal target volume on averaged 4-dimensional computed tomography scans using an in-house-developed IMPT planning system. The dose-volume histograms band method was used to evaluate plan robustness. Dose evaluation software was developed to model time-dependent spot delivery to incorporate interplay effects with randomized starting phases for each field per fraction. Patient anatomy voxels were mapped phase-to-phase via deformable image registration, and doses were scored using in-house-developed software. Dose-volume histogram indices, including internal target volume dose coverage, homogeneity, and organs at risk (OARs) sparing, were compared using the Wilcoxon signed-rank test. Compared with the large-spot machine, the small-spot machine resulted in significantly lower heart and esophagus mean doses, with comparable target dose coverage, homogeneity, and protection of other OARs. Plan robustness was comparable for targets and most OARs. With interplay effects considered, significantly lower heart and esophagus mean doses with comparable target dose coverage and homogeneity were observed using smaller spots. Robust optimization with a small spot-machine significantly improves heart and esophagus sparing, with comparable plan robustness and interplay effects compared with robust optimization with a large-spot machine. A small-spot machine uses a larger number of spots to cover the same tumors compared with a large-spot

  17. Laser Spot Welding of Copper-aluminum Joints Using a Pulsed Dual Wavelength Laser at 532 and 1064 nm

    Science.gov (United States)

    Stritt, Peter; Hagenlocher, Christian; Kizler, Christine; Weber, Rudolf; Rüttimann, Christoph; Graf, Thomas

    A modulated pulsed laser source emitting green and infrared laser light is used to join the dissimilar metals copper and aluminum. The resultant dynamic welding process is analyzed using the back reflected laser light and high speed video observations of the interaction zone. Different pulse shapes are applied to influence the melt pool dynamics and thereby the forming grain structure and intermetallic phases. The results of high-speed images and back-reflections prove that a modulation of the pulse shape is transferred to oscillations of the melt pool at the applied frequency. The outcome of the melt pool oscillation is shown by the metallurgically prepared cross-section, which indicates different solidification lines and grain shapes. An energy-dispersivex-ray analysis shows the mixture and the resultant distribution of the two metals, copper and aluminum, within the spot weld. It can be seen that the mixture is homogenized the observed melt pool oscillations.

  18. Size Dependent Male Reproductive Tactic in the Two-Spotted Goby (Gobiusculus flavescens).

    Science.gov (United States)

    Utne-Palm, A C; Eduard, K; Jensen, K H; Mayer, I; Jakobsen, P J

    2015-01-01

    Male investment in testes and sperm duct gland in the polygamous nest breeding two-spotted goby Gobiusculus flavescens (Fabricius) was investigated in relation to time in reproductive season and individual physical parameters. This small teleost fish is most likely the most abundant species found along the rocky shores of the North East Atlantic. The two-spotted goby has a single reproductive season, during which nest-caring males can raise several clutches of offspring. According to the literature the males are on average larger than the females. Here we report for the first time a population showing a reversal of this trend, with males on average being smaller than females, a difference likely caused by a large proportion of small males. Early in the breeding season these small males have typical sneaker characters, with relatively large testes and small seminal duct glands compared to the larger dominant territorial males. The presence of these two alternative male reproductive tactics is confirmed by histological studies, which shows the presence of sperm in the sperm duct glands (SDG) of smaller males, but not in the SDG of intermediate and larger males. To our knowledge, males with typical sneaker characters have not been reported in earlier studied populations of two-spotted goby. Interestingly we found that testes investment declined significantly over the course of the breeding season, and that this reduction was significantly more pronounced in small compared to the large males. Further, a significant increase in seminal duct gland (SDG) mass was observed for the smaller males over the breeding season. We propose that this indicates a possible shift in mating tactic by smaller males from a parasitic to a nest-holding tactic over the course of the breeding season. Thus, the observed size dependent plasticity in investment in SDG over time suggests that the reproductive tactic of G. flavescens is conditional, and possibly influenced by mate availability and

  19. Size Dependent Male Reproductive Tactic in the Two-Spotted Goby (Gobiusculus flavescens.

    Directory of Open Access Journals (Sweden)

    A C Utne-Palm

    Full Text Available Male investment in testes and sperm duct gland in the polygamous nest breeding two-spotted goby Gobiusculus flavescens (Fabricius was investigated in relation to time in reproductive season and individual physical parameters. This small teleost fish is most likely the most abundant species found along the rocky shores of the North East Atlantic. The two-spotted goby has a single reproductive season, during which nest-caring males can raise several clutches of offspring. According to the literature the males are on average larger than the females. Here we report for the first time a population showing a reversal of this trend, with males on average being smaller than females, a difference likely caused by a large proportion of small males. Early in the breeding season these small males have typical sneaker characters, with relatively large testes and small seminal duct glands compared to the larger dominant territorial males. The presence of these two alternative male reproductive tactics is confirmed by histological studies, which shows the presence of sperm in the sperm duct glands (SDG of smaller males, but not in the SDG of intermediate and larger males. To our knowledge, males with typical sneaker characters have not been reported in earlier studied populations of two-spotted goby. Interestingly we found that testes investment declined significantly over the course of the breeding season, and that this reduction was significantly more pronounced in small compared to the large males. Further, a significant increase in seminal duct gland (SDG mass was observed for the smaller males over the breeding season. We propose that this indicates a possible shift in mating tactic by smaller males from a parasitic to a nest-holding tactic over the course of the breeding season. Thus, the observed size dependent plasticity in investment in SDG over time suggests that the reproductive tactic of G. flavescens is conditional, and possibly influenced by mate

  20. Small-sized accelerating tube for electron acceleration to 500 keV at pulse duration of 2 ns

    International Nuclear Information System (INIS)

    Pavlovskaya, N.G.; Ehl'yash, S.L.; Dron', N.A.; Sloeva, G.N.

    1978-01-01

    The design and characteristics (current, voltage, current density, electron beam structure, energy spectrum, and dose rate) of a soldered small-size two-electrode 600 kV accelerating tube are considered. A six-stage Arkadiev-Marx generator is the pulse high-voltage supply of nanosecond duration. When using a cathode (diameter of 8 mm) made of tantalum foil 0.02 mm thick and with interelectrode gap of 10 mm, the amplitude of the electron beam current beyond the beryllium anode equals to 1040 A under maximum voltage of 490 kV, current pulse duration of 2 ns, number of electrons is 10 13 . The increased electron density on the anode in a spot of 4 mm in diameter is observed; the current density in the spot reaches 1 kA/cm 2 . The electron energy in the beam beyond the anode is as much as 0.6-0.8 J per pulse, and the dose rate near the outer surface of the outlet window is 10 14 -10 15 rad/s. The use of an intensifying oil spark gap is shown to increase radiation hardness. The accelerating tube provides more than 10 5 shots in a single-switching mode

  1. Effect of laser pulse parameters on the size and fluorescence of nanodiamonds formed upon pulsed-laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Peikang [School of Materials Science and Engineering, North University of China, Taiyuan 030051 (China); Hu, Shengliang, E-mail: hsliang@yeah.net [Key Laboratory of Instrumentation Science and Dynamic Measurement (North University of China), Ministry of Education, National Key Laboratory Science and Technology on Electronic Test and Measurement, Taiyuan 030051 (China); School of Materials Science and Engineering, North University of China, Taiyuan 030051 (China); Zhang, Taiping; Sun, Jing [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Cao, Shirui [School of Materials Science and Engineering, North University of China, Taiyuan 030051 (China)

    2010-07-15

    The size of nanodiamonds formed upon laser irradiation could be easily controlled over simply adjusting laser pulse parameters. The stable size and structure of nanodiamonds were mostly determined by laser power density and pulse width. Both large nanodiamonds with multiply twinning structure (MTS) and small nanodiamonds with single crystalline structure (SCS) emitted strong visible light after surface passivation, and their fluorescence quantum yield (QY) was 4.6% and 7.1%, respectively.

  2. Effect of laser pulse parameters on the size and fluorescence of nanodiamonds formed upon pulsed-laser irradiation

    International Nuclear Information System (INIS)

    Bai, Peikang; Hu, Shengliang; Zhang, Taiping; Sun, Jing; Cao, Shirui

    2010-01-01

    The size of nanodiamonds formed upon laser irradiation could be easily controlled over simply adjusting laser pulse parameters. The stable size and structure of nanodiamonds were mostly determined by laser power density and pulse width. Both large nanodiamonds with multiply twinning structure (MTS) and small nanodiamonds with single crystalline structure (SCS) emitted strong visible light after surface passivation, and their fluorescence quantum yield (QY) was 4.6% and 7.1%, respectively.

  3. Influence of habitat quality, population size, patch size, and connectivity on patch-occupancy dynamics of the middle spotted woodpecker.

    Science.gov (United States)

    Robles, Hugo; Ciudad, Carlos

    2012-04-01

    Despite extensive research on the effects of habitat fragmentation, the ecological mechanisms underlying colonization and extinction processes are poorly known, but knowledge of these mechanisms is essential to understanding the distribution and persistence of populations in fragmented habitats. We examined these mechanisms through multiseason occupancy models that elucidated patch-occupancy dynamics of Middle Spotted Woodpeckers (Dendrocopos medius) in northwestern Spain. The number of occupied patches was relatively stable from 2000 to 2010 (15-24% of 101 patches occupied every year) because extinction was balanced by recolonization. Larger and higher quality patches (i.e., higher density of oaks >37 cm dbh [diameter at breast height]) were more likely to be occupied. Habitat quality (i.e., density of large oaks) explained more variation in patch colonization and extinction than did patch size and connectivity, which were both weakly associated with probabilities of turnover. Patches of higher quality were more likely to be colonized than patches of lower quality. Populations in high-quality patches were less likely to become extinct. In addition, extinction in a patch was strongly associated with local population size but not with patch size, which means the latter may not be a good surrogate of population size in assessments of extinction probability. Our results suggest that habitat quality may be a primary driver of patch-occupancy dynamics and may increase the accuracy of models of population survival. We encourage comparisons of competing models that assess occupancy, colonization, and extinction probabilities in a single analytical framework (e.g., dynamic occupancy models) so as to shed light on the association of habitat quality and patch geometry with colonization and extinction processes in different settings and species. ©2012 Society for Conservation Biology.

  4. Spot Size Limited Carbon Propellant Characterization for Efficient High Isp Laser Propulsion

    International Nuclear Information System (INIS)

    Uchida, Shigeaki; Shimada, Yoshinori; Hashimoto, Kazuhisa; Yamaura, Michiteru; Birou, Tomoya; Yoshida, Minoru

    2005-01-01

    Laser propulsion has very unique advantage of producing exhausting gas (ions) of very high velocity. Specific impulse from laser plasma could easily exceed 10,000 seconds that reduce the current propellant consumption rate on space born thrusters significantly. For efficient propellant usage, it is desirable that the exhaust plasma has rather narrow velocity distribution of fast ions. In order to accomplish the requirements, thermal conduction and neutral particle losses at and vicinity of the laser heated region have to be eliminated. A concept of spot size limited propellant shape has been proposed and tested in terms of the effects of the loss reduction. Ion and neutral particle measurements from laser plasmas produced on the above mentioned carbon targets are used to characterize the performance of the propellant

  5. Automated translating beam profiler for in situ laser beam spot-size and focal position measurements

    Science.gov (United States)

    Keaveney, James

    2018-03-01

    We present a simple and convenient, high-resolution solution for automated laser-beam profiling with axial translation. The device is based on a Raspberry Pi computer, Pi Noir CMOS camera, stepper motor, and commercial translation stage. We also provide software to run the device. The CMOS sensor is sensitive over a large wavelength range between 300 and 1100 nm and can be translated over 25 mm along the beam axis. The sensor head can be reversed without changing its axial position, allowing for a quantitative estimate of beam overlap with counter-propagating laser beams. Although not limited to this application, the intended use for this device is the automated measurement of the focal position and spot-size of a Gaussian laser beam. We present example data of one such measurement to illustrate device performance.

  6. Impact of Spot Size and Beam-Shaping Devices on the Treatment Plan Quality for Pencil Beam Scanning Proton Therapy

    International Nuclear Information System (INIS)

    Moteabbed, Maryam; Yock, Torunn I.; Depauw, Nicolas; Madden, Thomas M.; Kooy, Hanne M.; Paganetti, Harald

    2016-01-01

    Purpose: This study aimed to assess the clinical impact of spot size and the addition of apertures and range compensators on the treatment quality of pencil beam scanning (PBS) proton therapy and to define when PBS could improve on passive scattering proton therapy (PSPT). Methods and Materials: The patient cohort included 14 pediatric patients treated with PSPT. Six PBS plans were created and optimized for each patient using 3 spot sizes (∼12-, 5.4-, and 2.5-mm median sigma at isocenter for 90- to 230-MeV range) and adding apertures and compensators to plans with the 2 larger spots. Conformity and homogeneity indices, dose-volume histogram parameters, equivalent uniform dose (EUD), normal tissue complication probability (NTCP), and integral dose were quantified and compared with the respective PSPT plans. Results: The results clearly indicated that PBS with the largest spots does not necessarily offer a dosimetric or clinical advantage over PSPT. With comparable target coverage, the mean dose (D_m_e_a_n) to healthy organs was on average 6.3% larger than PSPT when using this spot size. However, adding apertures to plans with large spots improved the treatment quality by decreasing the average D_m_e_a_n and EUD by up to 8.6% and 3.2% of the prescribed dose, respectively. Decreasing the spot size further improved all plans, lowering the average D_m_e_a_n and EUD by up to 11.6% and 10.9% compared with PSPT, respectively, and eliminated the need for beam-shaping devices. The NTCP decreased with spot size and addition of apertures, with maximum reduction of 5.4% relative to PSPT. Conclusions: The added benefit of using PBS strongly depends on the delivery configurations. Facilities limited to large spot sizes (>∼8 mm median sigma at isocenter) are recommended to use apertures to reduce treatment-related toxicities, at least for complex and/or small tumors.

  7. Formation of Porous Structure with Subspot Size under the Irradiation of Picosecond Laser Pulses

    Directory of Open Access Journals (Sweden)

    Bin Liu

    2013-01-01

    Full Text Available A study was presented in this paper on porous structure with microsize holes significantly smaller than laser spot on the stainless steel 304 target surface induced by a picosecond Nd:van regenerative amplified laser, operating at 1064 nm. The target surface variations were studied in air ambience. The estimated surface damage threshold was 0.15 J/cm2. The target specific surface changes and phenomena observed supported a complementary study on the formation and growth of the subspot size pit holes on metal surface with dependence of laser pulse number of 50–1000 and fluences of 0.8 and 1.6 J/cm2. Two kinds of porous structures were presented: periodic holes are formed from Coulomb Explosion during locally spatial modulated ablation, and random holes are formed from the burst of bubbles in overheated liquid during phase explosion. It can be concluded that it is effective to fabricate a large metal surface area of porous structure by laser scanning regime. Generally, it is also difficult for ultrashort laser to fabricate the microporous structures compared with traditional methods. These porous structures potentially have a number of important applications in nanotechnology, industry, nuclear complex, and so forth.

  8. Treatment of melasma with low fluence, large spot size, 1064-nm Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser for the treatment of melasma in Fitzpatrick skin types II-IV.

    Science.gov (United States)

    Brown, Alia S; Hussain, Mussarat; Goldberg, David J

    2011-12-01

    Melasma is a common condition affecting over six million American women. Treatment of dermal or combined melasma is difficult and does not respond well to conventional topical therapies. Various light sources have been used recently in the treatment of melasma including fractionated ablative and non-ablative lasers as well as intense pulse light. We report the use of low fluence, large spot size Q-switched, Nd:Yag laser for the treatment of melasma in skin types II-IV.

  9. Deposition of Bacillus subtilis spores using an airbrush-spray or spots to study surface decontamination by pulsed light.

    Science.gov (United States)

    Levy, Caroline; Bornard, Isabelle; Carlin, Frédéric

    2011-02-01

    Microbial contamination on surfaces of food processing equipment is a major concern in industries. A new method to inoculate a single-cell layer (monolayer) of microorganisms onto polystyrene was developed, using a deposition with an airbrush. A homogeneous dispersion of Bacillus subtilis DSM 402 spores sprayed on the surface was observed using both plate count and scanning electron microscopy. No clusters were found, even with high spore concentrations (10(7) spores/inoculated surface). A monolayer of microorganisms was also obtained after deposition of 10 μL droplets containing 3×10(4) spores/spot on polystyrene disks, but not with a higher spore concentration. Pulsed light (PL) applied to monolayers of B. subtilis spores allowed log reductions higher than 6. As a consequence of clusters formation in spots of 10 μL containing more than 3×10(5) spores, log reductions obtained by PL were significantly lower. The comparative advantages of spot and spray depositions were discussed. Copyright © 2010 Elsevier B.V. All rights reserved.

  10. Hydrometeor Size Distribution Measurements by Imaging the Attenuation of a Laser Spot

    Science.gov (United States)

    Lane, John

    2013-01-01

    The optical extinction of a laser due to scattering of particles is a well-known phenomenon. In a laboratory environment, this physical principle is known as the Beer-Lambert law, and is often used to measure the concentration of scattering particles in a fluid or gas. This method has been experimentally shown to be a usable means to measure the dust density from a rocket plume interaction with the lunar surface. Using the same principles and experimental arrangement, this technique can be applied to hydrometeor size distributions, and for launch-pad operations, specifically as a passive hail detection and measurement system. Calibration of a hail monitoring system is a difficult process. In the past, it has required comparison to another means of measuring hydrometeor size and density. Using a technique recently developed for estimating the density of surface dust dispersed during a rocket landing, measuring the extinction of a laser passing through hail (or dust in the rocket case) yields an estimate of the second moment of the particle cloud, and hydrometeor size distribution in the terrestrial meteorological case. With the exception of disdrometers, instruments that measure rain and hail fall make indirect measurements of the drop-size distribution. Instruments that scatter microwaves off of hydrometeors, such as the WSR-88D (Weather Surveillance Radar 88 Doppler), vertical wind profilers, and microwave disdrometers, measure the sixth moment of the drop size distribution (DSD). By projecting a laser onto a target, changes in brightness of the laser spot against the target background during rain and hail yield a measurement of the DSD's second moment by way of the Beer-Lambert law. In order to detect the laser attenuation within the 8-bit resolution of most camera image arrays, a minimum path length is required. Depending on the intensity of the hail fall rate for moderate to heavy rainfall, a laser path length of 100 m is sufficient to measure variations in

  11. Objective evaluation of the sweet spot size in spatial sound reproduction using elevated loudspeakers

    DEFF Research Database (Denmark)

    Lacouture Parodi, Yesenia; Rubak, Per

    2010-01-01

    to the loudspeakers. This paper presents a follow-up evaluation of the performance of the three inversion techniques when the above mentioned conditions are relaxed. A setup to measure the sweet spot of different loudspeaker arrangements is described. The sweet spot was measured for 21 different loudspeaker...

  12. Escaping Electrons from Intense Laser-Solid Interactions as a Function of Laser Spot Size

    Directory of Open Access Journals (Sweden)

    Rusby Dean

    2018-01-01

    Full Text Available The interaction of a high-intensity laser with a solid target produces an energetic distribution of electrons that pass into the target. These electrons reach the rear surface of the target creating strong electric potentials that act to restrict the further escape of additional electrons. The measurement of the angle, flux and spectra of the electrons that do escape gives insights to the initial interaction. Here, the escaping electrons have been measured using a differentially filtered image plate stack, from interactions with intensities from mid 1020-1017 W/cm2, where the intensity has been reduced by defocussing to increase the size of the focal spot. An increase in electron flux is initially observed as the intensity is reduced from 4x1020 to 6x1018 W/cm2. The temperature of the electron distribution is also measured and found to be relatively constant. 2D particle-in-cell modelling is used to demonstrate the importance of pre-plasma conditions in understanding these observations.

  13. Historical and Contemporary Trends in the Size, Drift, and Color of Jupiter's Great Red Spot

    Science.gov (United States)

    Simon, Amy A.; Tabataba-Vakili, Fachreddin; Cosentino, Richard; Beebe, Reta F.; Wong, Michael H.; Orton, Glenn S.

    2018-04-01

    Observations of Jupiter’s Great Red Spot (GRS) span more than 150 years. This allows for careful measurements of its size and drift rate. High spatial resolution spacecraft data also allow tracking of its spectral characteristics and internal dynamics and structure. The GRS continues to shrink in longitudinal length at an approximately linear rate of 0.°194 yr‑1 and in latitudinal width at 0.°048 yr‑1. Its westward drift rate (relative to System III W. longitude) has increased from ∼0.°26/day in the 1980s to ∼0.°36/day currently. Since 2014, the GRS’s short wavelength (indicating a change in clouds/haze at high altitudes. In addition, its north–south color asymmetry has decreased, and the dark core has become smaller. Internal velocities have increased on its east and west edges, and decreased on the north and south, resulting in decreased relative vorticity and circulation. The GRS’s color changes from 2014 to 2017 may be explained by changes in stretching vorticity or divergence acting to balance the decrease in relative vorticity.

  14. SU-D-BRE-03: Dosimetric Impact of In-Air Spot Size Variations for Commissioning a Room-Matched Beam Model for Pencil Beam Scanning Proton Therapy

    International Nuclear Information System (INIS)

    Zhang, Y; Giebeler, A; Mascia, A; Piskulich, F; Perles, L; Lepage, R; Dong, L

    2014-01-01

    Purpose: To quantitatively evaluate dosimetric consequence of spot size variations and validate beam-matching criteria for commissioning a pencil beam model for multiple treatment rooms. Methods: A planning study was first conducted by simulating spot size variations to systematically evaluate dosimetric impact of spot size variations in selected cases, which was used to establish the in-air spot size tolerance for beam matching specifications. A beam model in treatment planning system was created using in-air spot profiles acquired in one treatment room. These spot profiles were also acquired from another treatment room for assessing the actual spot size variations between the two treatment rooms. We created twenty five test plans with targets of different sizes at different depths, and performed dose measurement along the entrance, proximal and distal target regions. The absolute doses at those locations were measured using ionization chambers at both treatment rooms, and were compared against the calculated doses by the beam model. Fifteen additional patient plans were also measured and included in our validation. Results: The beam model is relatively insensitive to spot size variations. With an average of less than 15% measured in-air spot size variations between two treatment rooms, the average dose difference was −0.15% with a standard deviation of 0.40% for 55 measurement points within target region; but the differences increased to 1.4%±1.1% in the entrance regions, which are more affected by in-air spot size variations. Overall, our single-room based beam model in the treatment planning system agreed with measurements in both rooms < 0.5% within the target region. For fifteen patient cases, the agreement was within 1%. Conclusion: We have demonstrated that dosimetrically equivalent machines can be established when in-air spot size variations are within 15% between the two treatment rooms

  15. Influence of primary prey on home-range size and habitat-use patterns of northern spotted owls (Strix occidentalis caurina)

    Science.gov (United States)

    Cynthia J. Zabel; Kevin S. McKelvey; James P. Ward

    1995-01-01

    Correlations between the home-range size of northern spotted owls (Strix occidentalis caurina) and proportion of their range in old-growth forest have been reported, but there are few data on the relationship between their home-range size and prey. The primary prey of spotted owls are wood rats and northern flying squirrels (Glaucomys sabrinus). Wood...

  16. Determination of the size of X-ray tube focal spots: direct digitalization vs optical evaluation

    International Nuclear Information System (INIS)

    Furquim, Tania A.C.; Yanikian, Denise; Costa, Paulo R.

    1996-01-01

    A comparative study between standard techniques for evaluation of X-ray tubes focal spots and a newer one which uses digital resources for image acquisition is presented. Results from measurements by using both methods are presented

  17. Building A Simulation Model For The Prediction Of Temperature Distribution In Pulsed Laser Spot Welding Of Dissimilar Low Carbon Steel 1020 To Aluminum Alloy 6061

    International Nuclear Information System (INIS)

    Yousef, Adel K. M.; Taha, Ziad A.; Shehab, Abeer A.

    2011-01-01

    This paper describes the development of a computer model used to analyze the heat flow during pulsed Nd: YAG laser spot welding of dissimilar metal; low carbon steel (1020) to aluminum alloy (6061). The model is built using ANSYS FLUENT 3.6 software where almost all the environments simulated to be similar to the experimental environments. A simulation analysis was implemented based on conduction heat transfer out of the key hole where no melting occurs. The effect of laser power and pulse duration was studied.Three peak powers 1, 1.66 and 2.5 kW were varied during pulsed laser spot welding (keeping the energy constant), also the effect of two pulse durations 4 and 8 ms (with constant peak power), on the transient temperature distribution and weld pool dimension were predicated using the present simulation. It was found that the present simulation model can give an indication for choosing the suitable laser parameters (i.e. pulse durations, peak power and interaction time required) during pulsed laser spot welding of dissimilar metals.

  18. Nanometer sized structures grown by pulsed laser deposition

    KAUST Repository

    ElZein, Basma

    2015-10-01

    Nanometer sized materials can be produced by exposing a target to a laser source to remove material from the target and deposit the removed material onto a surface of a substrate to grow a thin film in a vacuum chamber

  19. Relationship between thrombolysis efficiency induced by pulsed focused ultrasound and cavitation bubble size

    International Nuclear Information System (INIS)

    Xu, S; Liu, X; Wang, S; Wan, M

    2015-01-01

    In this study, the relationship between the efficiency of pulsed focused ultrasound (FUS)-induced thrombolysis and the size distribution of cavitation bubbles has been studied. Firstly, the thrombolysis efficiency, evaluated by degree of mechanical fragmentation was investigated with varying duty cycle. Secondly, the size distribution of cavitation bubbles after the 1st, 10 3 th and 10 5 th pulse during experiments for various duty cycles was studied. It was revealed that the thrombolysis efficiency was highest when the cavitation bubble size distribution was centred around linear resonance radius of the emission frequency of the FUS transducer. Therefore, in cavitation enhanced therapeutic applications, the essential of using a pulsed FUS may be controlling the size distribution of cavitation nuclei within an active size range so as to increase the treatment efficiency. (paper)

  20. Radiation dose reduction without compromise to image quality by alterations of filtration and focal spot size in cerebral angiography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Joon; Park, Min Keun; Jung, Da Eun; Kang, Jung Han; Kim, Byung Moon [Dept. of Radiology, Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2017-08-01

    Different angiographic protocols may influence the radiation dose and image quality. In this study, we aimed to investigate the effects of filtration and focal spot size on radiation dose and image quality for diagnostic cerebral angiography using an in-vitro model and in-vivo patient groups. Radiation dose and image quality were analyzed by varying the filtration and focal spot size on digital subtraction angiography exposure protocols (1, inherent filtration + large focus; 2, inherent + small; 3, copper + large; 4, copper + small). For the in-vitro analysis, a phantom was used for comparison of radiation dose. For the in-vivo analysis, bilateral paired injections, and patient cohort groups were compared for radiation dose and image quality. Image quality analysis was performed in terms of contrast, sharpness, noise, and overall quality. In the in-vitro analysis, the mean air kerma (AK) and dose area product (DAP)/frame were significantly lower with added copper filtration (protocols 3 and 4). In the in-vivo bilateral paired injections, AK and DAP/frame were significantly lower with filtration, without significant difference in image quality. The patient cohort groups with added filtration (protocols 3 and 4) showed significant reduction of total AK and DAP/patient without compromise to the image quality. Variations in focal spot size showed no significant differences in radiation dose and image quality. Addition of filtration for angiographic exposure studies can result in significant total radiation dose reduction without loss of image quality. Focal spot size does not influence radiation dose and image quality. The routine angiographic protocol should be judiciously investigated and implemented.

  1. Microfocusing of the FERMI@Elettra FEL beam with a K–B active optics system: Spot size predictions by application of the WISE code

    International Nuclear Information System (INIS)

    Raimondi, L.; Svetina, C.; Mahne, N.; Cocco, D.; Abrami, A.; De Marco, M.; Fava, C.; Gerusina, S.; Gobessi, R.; Capotondi, F.; Pedersoli, E.; Kiskinova, M.; De Ninno, G.; Zeitoun, P.; Dovillaire, G.; Lambert, G.; Boutu, W.; Merdji, H.; Gonzalez, A.I.; Gauthier, D.

    2013-01-01

    FERMI@Elettra, the first seeded EUV-SXR free electron laser (FEL) facility located at Elettra Sincrotrone Trieste has been conceived to provide very short (10–100 fs) pulses with ultrahigh peak brightness and wavelengths from 100 nm to 4 nm. A section fully dedicated to the photon transport and analysis diagnostics, named PADReS, has already been installed and commissioned. Three of the beamlines, EIS-TIMEX, DiProI and LDM, installed after the PADReS section, are in advanced commissioning state and will accept the first users in December 2012. These beam lines employ active X-ray optics in order to focus the FEL beam as well as to perform a controlled beam-shaping at focus. Starting from mirror surface metrology characterization, it is difficult to predict the focal spot shape applying only methods based on geometrical optics such as the ray tracing. Within the geometrical optics approach one cannot take into account the diffraction effect from the optics edges, i.e. the aperture diffraction, and the impact of different surface spatial wavelengths to the spot size degradation. Both these effects are strongly dependent on the photon beam energy and mirror incident angles. We employed a method based on physical optics, which applies the Huygens–Fresnel principle to reflection (on which the WISE code is based). In this work we report the results of the first measurements of the focal spot in the DiProI beamline end-station and compare them to the predictions computed with Shadow code and WISE code, starting from the mirror surface profile characterization

  2. Microfocusing of the FERMI@Elettra FEL beam with a K–B active optics system: Spot size predictions by application of the WISE code

    Energy Technology Data Exchange (ETDEWEB)

    Raimondi, L., E-mail: lorenzo.raimondi@elettra.trieste.it [Sincrotrone Trieste ScpA, S.S. 14 km 163.5 in Area Science Park, 34149 Trieste (Italy); Svetina, C.; Mahne, N. [Sincrotrone Trieste ScpA, S.S. 14 km 163.5 in Area Science Park, 34149 Trieste (Italy); Cocco, D. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, MS-19 Menlo Park, CA 94025 (United States); Abrami, A.; De Marco, M.; Fava, C.; Gerusina, S.; Gobessi, R.; Capotondi, F.; Pedersoli, E.; Kiskinova, M. [Sincrotrone Trieste ScpA, S.S. 14 km 163.5 in Area Science Park, 34149 Trieste (Italy); De Ninno, G. [Sincrotrone Trieste ScpA, S.S. 14 km 163.5 in Area Science Park, 34149 Trieste (Italy); University of Nova Gorica, Vipavska 13, Rozna Dolina, SI-5000 Nova Gorica (Slovenia); Zeitoun, P. [Laboratoire d' Optique Appliquée, CNRS-ENSTA-École Polytechnique, Chemin de la Humiére, 91761 Palaiseau (France); Dovillaire, G. [Imagine Optic, 18 Rue Charles de Gaulle, 91400 Orsay (France); Lambert, G. [Laboratoire d' Optique Appliquée, CNRS-ENSTA-École Polytechnique, Chemin de la Humiére, 91761 Palaiseau (France); Boutu, W.; Merdji, H.; Gonzalez, A.I. [Service des Photons, Atomes et Molécules, IRAMIS, CEA-Saclay, Btiment 522, 91191 Gif-sur-Yvette (France); Gauthier, D. [University of Nova Gorica, Vipavska 13, Rozna Dolina, SI-5000 Nova Gorica (Slovenia); and others

    2013-05-11

    FERMI@Elettra, the first seeded EUV-SXR free electron laser (FEL) facility located at Elettra Sincrotrone Trieste has been conceived to provide very short (10–100 fs) pulses with ultrahigh peak brightness and wavelengths from 100 nm to 4 nm. A section fully dedicated to the photon transport and analysis diagnostics, named PADReS, has already been installed and commissioned. Three of the beamlines, EIS-TIMEX, DiProI and LDM, installed after the PADReS section, are in advanced commissioning state and will accept the first users in December 2012. These beam lines employ active X-ray optics in order to focus the FEL beam as well as to perform a controlled beam-shaping at focus. Starting from mirror surface metrology characterization, it is difficult to predict the focal spot shape applying only methods based on geometrical optics such as the ray tracing. Within the geometrical optics approach one cannot take into account the diffraction effect from the optics edges, i.e. the aperture diffraction, and the impact of different surface spatial wavelengths to the spot size degradation. Both these effects are strongly dependent on the photon beam energy and mirror incident angles. We employed a method based on physical optics, which applies the Huygens–Fresnel principle to reflection (on which the WISE code is based). In this work we report the results of the first measurements of the focal spot in the DiProI beamline end-station and compare them to the predictions computed with Shadow code and WISE code, starting from the mirror surface profile characterization.

  3. Preliminary evaluation of sweet spot size in virtual sound reproduction using dipoles

    DEFF Research Database (Denmark)

    Lacouture Parodi, Yesenia; Rubak, Per

    2009-01-01

    to the loudspeakers. In this paper we present a follow up evaluation of the performance of the three inversion techniques when these conditions are violated. A setup to measure the sweet spot of different loudspeakers arrangements is described. Preliminary measurement results are presented for loudspeakers placed...

  4. Spot size characterization of focused non-Gaussian X-ray laser beams

    NARCIS (Netherlands)

    Chalupsky, J.; Krzywinski, J.; Juha, L.; Hajkova, V.; Cihelka, J.; Burian, T.; Vysin, L.; Gaudin, J.; Gleeson, A.; Jurek, M.; Khorsand, A. R.; Klinger, D.; Wabnitz, H.; Sobierajski, R.; Stormer, M.; Tiedtke, K.; Toleikis, S.

    2010-01-01

    We present a new technique for the characterization of non-Gaussian laser beams which cannot be described by an analytical formula. As a generalization of the beam spot area we apply and refine the definition of so called effective area (A(eff)) [1] in order to avoid using the full-width at half

  5. Spots on electrodes and images of a gap during pulsed discharges in an inhomogeneous electric field at elevated pressures of air, nitrogen and argon

    International Nuclear Information System (INIS)

    Shao, Tao; Yang, Wenjin; Zhang, Cheng; Yan, Ping; Tarasenko, Victor F; Beloplotov, Dmitry V; Lomaev, Mikhail I; Sorokin, Dmitry A

    2014-01-01

    Pulsed discharge in a nonuniform electric field accompanied by the appearance of bright spots due to explosive electron emission on electrodes has been investigated. The experiments were carried out using three experimental setups, a voltage pulse duration at a matched load of 2 ns, 40 ns, and 130 ns, respectively. Data on the formation of electrode spots during diffuse discharges in tube-plate or needle-plate gap configurations filled with gases at elevated pressures (air, nitrogen and argon) were obtained. It was found that in the air and other gases, bright spots arise on the flat electrode, and on the negative polarity of the electrode with a small radius of curvature, during the direction change of the current through the gap and the increase of the voltage pulse duration. It was shown that at the positive polarity of the electrode with a small radius of curvature, bright spots on the flat electrode arise due to the participation of the dynamic displacement current in the gap conductance. (paper)

  6. Illicit Drug Users in the Tanzanian Hinterland: Population Size Estimation Through Key Informant-Driven Hot Spot Mapping.

    Science.gov (United States)

    Ndayongeje, Joel; Msami, Amani; Laurent, Yovin Ivo; Mwankemwa, Syangu; Makumbuli, Moza; Ngonyani, Alois M; Tiberio, Jenny; Welty, Susie; Said, Christen; Morris, Meghan D; McFarland, Willi

    2018-02-12

    We mapped hot spots and estimated the numbers of people who use drugs (PWUD) and who inject drugs (PWID) in 12 regions of Tanzania. Primary (ie, current and past PWUD) and secondary (eg, police, service providers) key informants identified potential hot spots, which we visited to verify and count the number of PWUD and PWID present. Adjustments to counts and extrapolation to regional estimates were done by local experts through iterative rounds of discussion. Drug use, specifically cocaine and heroin, occurred in all regions. Tanga had the largest numbers of PWUD and PWID (5190 and 540, respectively), followed by Mwanza (3300 and 300, respectively). Findings highlight the need to strengthen awareness of drug use and develop prevention and harm reduction programs with broader reach in Tanzania. This exercise provides a foundation for understanding the extent and locations of drug use, a baseline for future size estimations, and a sampling frame for future research.

  7. The influence of laser pulse duration and energy on ICP-MS signal intensity, elemental fractionation, and particle size distribution in NIR fs-LA-ICP-MS

    Science.gov (United States)

    Diwakar, Prasoon K.; Harilal, Sivanandan S.; LaHaye, Nicole L.; Hassanein, Ahmed; Kulkarni, Pramod

    2015-01-01

    Laser parameters, typically wavelength, pulse width, irradiance, repetition rate, and pulse energy, are critical parameters which influence the laser ablation process and thereby influence the LA-ICP-MS signal. In recent times, femtosecond laser ablation has gained popularity owing to the reduction in fractionation related issues and improved analytical performance which can provide matrix-independent sampling. The advantage offered by fs-LA is due to shorter pulse duration of the laser as compared to the phonon relaxation time and heat diffusion time. Hence the thermal effects are minimized in fs-LA. Recently, fs-LA-ICP-MS demonstrated improved analytical performance as compared to ns-LA-ICP-MS, but detailed mechanisms and processes are still not clearly understood. Improvement of fs-LA-ICP-MS over ns-LA-ICP-MS elucidates the importance of laser pulse duration and related effects on the ablation process. In this study, we have investigated the influence of laser pulse width (40 fs to 0.3 ns) and energy on LA-ICP-MS signal intensity and repeatability using a brass sample. Experiments were performed in single spot ablation mode as well as rastering ablation mode to monitor the Cu/Zn ratio. The recorded ICP-MS signal was correlated with total particle counts generated during laser ablation as well as particle size distribution. Our results show the importance of pulse width effects in the fs regime that becomes more pronounced when moving from femtosecond to picosecond and nanosecond regimes. PMID:26664120

  8. Hypopigmentation Induced by Frequent Low-Fluence, Large-Spot-Size QS Nd:YAG Laser Treatments.

    Science.gov (United States)

    Wong, Yisheng; Lee, Siong See Joyce; Goh, Chee Leok

    2015-12-01

    The Q-switched 1064-nm neodymium-doped yttrium aluminum garnet (QS 1064-nm Nd:YAG) laser is increasingly used for nonablative skin rejuvenation or "laser toning" for melasma. Multiple and frequent low-fluence, large-spot-size treatments are used to achieve laser toning, and these treatments are associated with the development of macular hypopigmentation as a complication. We present a case series of three patients who developed guttate hypomelanotic macules on the face after receiving laser toning treatment with QS 1064-nm Nd:YAG.

  9. TH-CD-209-05: Impact of Spot Size and Spacing On the Quality of Robustly-Optimized Intensity-Modulated Proton Therapy Plans for Lung Cancer

    International Nuclear Information System (INIS)

    Liu, W; Ding, X; Hu, Y; Shen, J; Korte, S; Bues, M; Schild, S; Wong, W; Chang, J; Liao, Z; Sahoo, N; Herman, M

    2016-01-01

    Purpose: To investigate how spot size and spacing affect plan quality, especially, plan robustness and the impact of interplay effect, of robustly-optimized intensity-modulated proton therapy (IMPT) plans for lung cancer. Methods: Two robustly-optimized IMPT plans were created for 10 lung cancer patients: (1) one for a proton beam with in-air energy dependent large spot size at isocenter (σ: 5–15 mm) and spacing (1.53σ); (2) the other for a proton beam with small spot size (σ: 2–6 mm) and spacing (5 mm). Both plans were generated on the average CTs with internal-gross-tumor-volume density overridden to irradiate internal target volume (ITV). The root-mean-square-dose volume histograms (RVH) measured the sensitivity of the dose to uncertainties, and the areas under RVH curves were used to evaluate plan robustness. Dose evaluation software was developed to model time-dependent spot delivery to incorporate interplay effect with randomized starting phases of each field per fraction. Patient anatomy voxels were mapped from phase to phase via deformable image registration to score doses. Dose-volume-histogram indices including ITV coverage, homogeneity, and organs-at-risk (OAR) sparing were compared using Student-t test. Results: Compared to large spots, small spots resulted in significantly better OAR sparing with comparable ITV coverage and homogeneity in the nominal plan. Plan robustness was comparable for ITV and most OARs. With interplay effect considered, significantly better OAR sparing with comparable ITV coverage and homogeneity is observed using smaller spots. Conclusion: Robust optimization with smaller spots significantly improves OAR sparing with comparable plan robustness and similar impact of interplay effect compare to larger spots. Small spot size requires the use of larger number of spots, which gives optimizer more freedom to render a plan more robust. The ratio between spot size and spacing was found to be more relevant to determine plan

  10. TH-CD-209-05: Impact of Spot Size and Spacing On the Quality of Robustly-Optimized Intensity-Modulated Proton Therapy Plans for Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W; Ding, X; Hu, Y; Shen, J; Korte, S; Bues, M [Mayo Clinic Arizona, Phoenix, AZ (United States); Schild, S; Wong, W [Mayo Clinic AZ, Phoenix, AZ (United States); Chang, J [MD Anderson Cancer Center, Houston, TX (United States); Liao, Z; Sahoo, N [UT MD Anderson Cancer Center, Houston, TX (United States); Herman, M [Mayo Clinic, Rochester, MN (United States)

    2016-06-15

    Purpose: To investigate how spot size and spacing affect plan quality, especially, plan robustness and the impact of interplay effect, of robustly-optimized intensity-modulated proton therapy (IMPT) plans for lung cancer. Methods: Two robustly-optimized IMPT plans were created for 10 lung cancer patients: (1) one for a proton beam with in-air energy dependent large spot size at isocenter (σ: 5–15 mm) and spacing (1.53σ); (2) the other for a proton beam with small spot size (σ: 2–6 mm) and spacing (5 mm). Both plans were generated on the average CTs with internal-gross-tumor-volume density overridden to irradiate internal target volume (ITV). The root-mean-square-dose volume histograms (RVH) measured the sensitivity of the dose to uncertainties, and the areas under RVH curves were used to evaluate plan robustness. Dose evaluation software was developed to model time-dependent spot delivery to incorporate interplay effect with randomized starting phases of each field per fraction. Patient anatomy voxels were mapped from phase to phase via deformable image registration to score doses. Dose-volume-histogram indices including ITV coverage, homogeneity, and organs-at-risk (OAR) sparing were compared using Student-t test. Results: Compared to large spots, small spots resulted in significantly better OAR sparing with comparable ITV coverage and homogeneity in the nominal plan. Plan robustness was comparable for ITV and most OARs. With interplay effect considered, significantly better OAR sparing with comparable ITV coverage and homogeneity is observed using smaller spots. Conclusion: Robust optimization with smaller spots significantly improves OAR sparing with comparable plan robustness and similar impact of interplay effect compare to larger spots. Small spot size requires the use of larger number of spots, which gives optimizer more freedom to render a plan more robust. The ratio between spot size and spacing was found to be more relevant to determine plan

  11. Source apportionment of aerosol particles at a European air pollution hot spot using particle number size distributions and chemical composition.

    Science.gov (United States)

    Leoni, Cecilia; Pokorná, Petra; Hovorka, Jan; Masiol, Mauro; Topinka, Jan; Zhao, Yongjing; Křůmal, Kamil; Cliff, Steven; Mikuška, Pavel; Hopke, Philip K

    2018-03-01

    Ostrava in the Moravian-Silesian region (Czech Republic) is a European air pollution hot spot for airborne particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs), and ultrafine particles (UFPs). Air pollution source apportionment is essential for implementation of successful abatement strategies. UFPs or nanoparticles of diameter hot-spot including nanoparticles, Positive Matrix Factorization (PMF) was applied to highly time resolved particle number size distributions (NSD, 14 nm-10 μm) and PM 0.09-1.15 chemical composition. Diurnal patterns, meteorological variables, gaseous pollutants, organic markers, and associations between the NSD factors and chemical composition factors were used to identify the pollution sources. The PMF on the NSD reveals two factors in the ultrafine size range: industrial UFPs (28%, number mode diameter - NMD 45 nm), industrial/fresh road traffic nanoparticles (26%, NMD 26 nm); three factors in the accumulation size range: urban background (24%, NMD 93 nm), coal burning (14%, volume mode diameter - VMD 0.5 μm), regional pollution (3%, VMD 0.8 μm) and one factor in the coarse size range: industrial coarse particles/road dust (2%, VMD 5 μm). The PMF analysis of PM 0.09-1.15 revealed four factors: SIA/CC/BB (52%), road dust (18%), sinter/steel (16%), iron production (16%). The factors in the ultrafine size range resolved with NSD have a positive correlation with sinter/steel production and iron production factors resolved with chemical composition. Coal combustion factor resolved with NSD has moderate correlation with SIA/CC/BB factor. The organic markers homohopanes correlate with coal combustion and the levoglucosan correlates with urban background. The PMF applications to NSD and chemical composition datasets are complementary. PAHs in PM 1 were found to be associated with coal combustion factor. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Treatment of acne scarring using a dual-spot-size ablative fractionated carbon dioxide laser: review of the literature.

    Science.gov (United States)

    Tierney, Emily P

    2011-07-01

    Fractional photothermolysis has been reported in the literature to improve pigmentary and textural changes associated with acne scarring. To review the literature for the treatment of acne scarring using nonablative fractional laser (NAFL) and ablative fractional laser (AFL) resurfacing. Review of the Medline literature evaluating NAFL and AFL for acne scarring. NAFL and AFL are safe and effective treatments for acne scarring. It is likely that the controlled, limited dermal heating of fractional resurfacing initiates a cascade of events in which normalization of the collagenesis-collagenolysis cycle occurs. We present the results of a patient treated using a novel dual-spot-size AFL device. Three months after the final treatment, the patient reported 75% improvement in acne scarring and 63% overall improvement in photoaging. Fractionated resurfacing for the treatment of acne scarring is associated with lesser risks of side effects of prolonged erythema and risks of delayed-onset dyspigmentation and scarring which complicate traditional ablative laser resurfacing approaches. We present herein preliminary data suggesting that a dual-spot-size AFL device presents novel advantages of improving texture and pigmentation in acne scarring and photoaging. © 2011 by the American Society for Dermatologic Surgery, Inc.

  13. Quantification of uncertainty in photon source spot size inference during laser-driven radiography experiments at TRIDENT

    Energy Technology Data Exchange (ETDEWEB)

    Tobias, Benjamin John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Palaniyappan, Sasikumar [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gautier, Donald Cort [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mendez, Jacob [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Burris-Mog, Trevor John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Huang, Chengkun K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Favalli, Andrea [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hunter, James F. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Espy, Michelle E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Schmidt, Derek William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nelson, Ronald Owen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sefkow, Adam [Univ. of Rochester, NY (United States); Shimada, Tsutomu [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Johnson, Randall Philip [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Fernandez, Juan Carlos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-24

    Images of the R2DTO resolution target were obtained during laser-driven-radiography experiments performed at the TRIDENT laser facility, and analysis of these images using the Bayesian Inference Engine (BIE) determines a most probable full-width half maximum (FWHM) spot size of 78 μm. However, significant uncertainty prevails due to variation in the measured detector blur. Propagating this uncertainty in detector blur through the forward model results in an interval of probabilistic ambiguity spanning approximately 35-195 μm when the laser energy impinges on a thick (1 mm) tantalum target. In other phases of the experiment, laser energy is deposited on a thin (~100 nm) aluminum target placed 250 μm ahead of the tantalum converter. When the energetic electron beam is generated in this manner, upstream from the bremsstrahlung converter, the inferred spot size shifts to a range of much larger values, approximately 270-600 μm FWHM. This report discusses methods applied to obtain these intervals as well as concepts necessary for interpreting the result within a context of probabilistic quantitative inference.

  14. Pump spot size dependent lasing threshold in organic semiconductor DFB lasers fabricated via nanograting transfer.

    Science.gov (United States)

    Liu, Xin; Klinkhammer, Sönke; Wang, Ziyao; Wienhold, Tobias; Vannahme, Christoph; Jakobs, Peter-Jürgen; Bacher, Andreas; Muslija, Alban; Mappes, Timo; Lemmer, Uli

    2013-11-18

    Optically excited organic semiconductor distributed feedback (DFB) lasers enable efficient lasing in the visible spectrum. Here, we report on the rapid and parallel fabrication of DFB lasers via transferring a nanograting structure from a flexible mold onto an unstructured film of the organic gain material. This geometrically well-defined structure allows for a systematic investigation of the laser threshold behavior. The laser thresholds for these devices show a strong dependence on the pump spot diameter. This experimental finding is in good qualitative agreement with calculations based on coupled-wave theory. With further investigations on various DFB laser geometries prepared by different routes and based on different organic gain materials, we found that these findings are quite general. This is important for the comparison of threshold values of various devices characterized under different excitation areas.

  15. Spot size characterization of focused non-Gaussian X-ray laser beams.

    Science.gov (United States)

    Chalupský, J; Krzywinski, J; Juha, L; Hájková, V; Cihelka, J; Burian, T; Vysín, L; Gaudin, J; Gleeson, A; Jurek, M; Khorsand, A R; Klinger, D; Wabnitz, H; Sobierajski, R; Störmer, M; Tiedtke, K; Toleikis, S

    2010-12-20

    We present a new technique for the characterization of non-Gaussian laser beams which cannot be described by an analytical formula. As a generalization of the beam spot area we apply and refine the definition of so called effective area (A(eff)) [1] in order to avoid using the full-width at half maximum (FWHM) parameter which is inappropriate for non-Gaussian beams. Furthermore, we demonstrate a practical utilization of our technique for a femtosecond soft X-ray free-electron laser. The ablative imprints in poly(methyl methacrylate) - PMMA and amorphous carbon (a-C) are used to characterize the spatial beam profile and to determine the effective area. Two procedures of the effective area determination are presented in this work. An F-scan method, newly developed in this paper, appears to be a good candidate for the spatial beam diagnostics applicable to lasers of various kinds.

  16. Pump spot size dependent lasing threshold in organic semiconductor DFB lasers fabricated via nanograting transfer

    DEFF Research Database (Denmark)

    Liu, Xin; Klinkhammer, Sönke; Wang, Ziyao

    2013-01-01

    material. This geometrically well-defined structure allows for a systematic investigation of the laser threshold behavior. The laser thresholds for these devices show a strong dependence on the pump spot diameter. This experimental finding is in good qualitative agreement with calculations based on coupled......Optically excited organic semiconductor distributed feedback (DFB) lasers enable efficient lasing in the visible spectrum. Here, we report on the rapid and parallel fabrication of DFB lasers via transferring a nanograting structure from a flexible mold onto an unstructured film of the organic gain......-wave theory. With further investigations on various DFB laser geometries prepared by different routes and based on different organic gain materials, we found that these findings are quite general. This is important for the comparison of threshold values of various devices characterized under different...

  17. Granule size control and targeting in pulsed spray fluid bed granulation.

    Science.gov (United States)

    Ehlers, Henrik; Liu, Anchang; Räikkönen, Heikki; Hatara, Juha; Antikainen, Osmo; Airaksinen, Sari; Heinämäki, Jyrki; Lou, Honxiang; Yliruusi, Jouko

    2009-07-30

    The primary aim of the study was to investigate the effects of pulsed liquid feed on granule size. The secondary aim was to increase knowledge of this technique in granule size targeting. Pulsed liquid feed refers to the pump changing between on- and off-positions in sequences, called duty cycles. One duty cycle consists of one on- and off-period. The study was performed with a laboratory-scale top-spray fluid bed granulator with duty cycle length and atomization pressure as studied variables. The liquid feed rate, amount and inlet air temperature were constant. The granules were small, indicating that the powder has only undergone ordered mixing, nucleation and early growth. The effect of atomizing pressure on granule size depends on inlet air relative humidity, with premature binder evaporation as a reason. The duty cycle length was of critical importance to the end product attributes, by defining the extent of intermittent drying and rewetting. By varying only the duty cycle length, it was possible to control granule nucleation and growth, with a wider granule size target range in increased relative humidity. The present study confirms that pulsed liquid feed in fluid bed granulation is a useful tool in end product particle size targeting.

  18. Retrospective Study on Laser Treatment of Oral Vascular Lesions Using the "Leopard Technique": The Multiple Spot Irradiation Technique with a Single-Pulsed Wave.

    Science.gov (United States)

    Miyazaki, Hidetaka; Ohshiro, Takafumi; Romeo, Umberto; Noguchi, Tadahide; Maruoka, Yutaka; Gaimari, Gianfranco; Tomov, Georgi; Wada, Yoshitaka; Tanaka, Kae; Ohshiro, Toshio; Asamura, Shinichi

    2018-06-01

    This study aimed to retrospectively evaluate the efficacy and safety of laser treatment of oral vascular lesions using the multiple spot irradiation technique with a single-pulsed wave. In laser therapy for vascular lesions, heat accumulation induced by excessive irradiation can cause adverse events postoperatively, including ulcer formation, resultant scarring, and severe pain. To prevent heat accumulation and side effects, we have applied a multiple pulsed spot irradiation technique, the so-called "leopard technique" (LT) to oral vascular lesions. This approach was originally proposed for laser treatment of nevi. It can avoid thermal concentration at the same spot and spare the epithelium, which promotes smooth healing. The goal of the study was to evaluate this procedure and treatment outcomes. The subjects were 46 patients with 47 oral vascular lesions treated with the LT using a Nd:YAG laser (1064 nm), including 24 thick lesions treated using a combination of the LT and intralesional photocoagulation. All treatment outcomes were satisfactory without serious complications such as deep ulcer formation, scarring, bleeding, or severe swelling. Laser therapy with the LT is a promising less-invasive treatment for oral vascular lesions.

  19. Operational Experiences Tuning the ATF2 Final Focus Optics Towards Obtaining a 37nm Electron Beam IP Spot Size

    CERN Document Server

    White, Glen; Woodley, Mark; Bai, Sha; Bambade, Philip; Renier, Yves; Bolzon, Benoit; Kamiya, Yoshio; Komamiya, Sachio; Oroku, Masahiro; Yamaguchi, Yohei; Yamanaka, Takashi; Kubo, Kiyoshi; Kuroda, Shigeru; Okugi, Toshiyuki; Tauchi, Toshiaki; Marin, Eduardo

    2010-01-01

    The primary aim of the ATF2 research accelerator is to test a scaled version of the final focus optics planned for use in next-generation linear lepton colliders. ATF2 consists of a 1.3 GeV linac, damping ring providing lowemittance electron beams (<12pm in the vertical plane), extraction line and final focus optics. The design details of the final focus optics and implementation at ATF2 are presented elsewhere. The ATF2 accelerator is currently being commissioned, with a staged approach to achieving the design IP spot size. It is expected that as we implement more demanding optics and reduce the vertical beta function at the IP, the tuning becomes more difficult and takes longer. We present here a description of the implementation of the tuning procedures and describe operational experiences and performances

  20. Influence of the Laser Spot Size, Focal Beam Profile, and Tissue Type on the Lipid Signals Obtained by MALDI-MS Imaging in Oversampling Mode.

    Science.gov (United States)

    Wiegelmann, Marcel; Dreisewerd, Klaus; Soltwisch, Jens

    2016-12-01

    To improve the lateral resolution in matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) beyond the dimensions of the focal laser spot oversampling techniques are employed. However, few data are available on the effect of the laser spot size and its focal beam profile on the ion signals recorded in oversampling mode. To investigate these dependencies, we produced 2 times six spots with dimensions between ~30 and 200 μm. By optional use of a fundamental beam shaper, square flat-top and Gaussian beam profiles were compared. MALDI-MSI data were collected using a fixed pixel size of 20 μm and both pixel-by-pixel and continuous raster oversampling modes on a QSTAR mass spectrometer. Coronal mouse brain sections coated with 2,5-dihydroxybenzoic acid matrix were used as primary test systems. Sizably higher phospholipid ion signals were produced with laser spots exceeding a dimension of ~100 μm, although the same amount of material was essentially ablated from the 20 μm-wide oversampling pixel at all spot size settings. Only on white matter areas of the brain these effects were less apparent to absent. Scanning electron microscopy images showed that these findings can presumably be attributed to different matrix morphologies depending on tissue type. We propose that a transition in the material ejection mechanisms from a molecular desorption at large to ablation at smaller spot sizes and a concomitant reduction in ion yields may be responsible for the observed spot size effects. The combined results indicate a complex interplay between tissue type, matrix crystallization, and laser-derived desorption/ablation and finally analyte ionization. Graphical Abstract ᅟ.

  1. Using a Reduced Spot Size for Intensity-Modulated Proton Therapy Potentially Improves Salivary Gland-Sparing in Oropharyngeal Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Water, Tara A. van de, E-mail: t.a.van.de.water@rt.umcg.nl [Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen (Netherlands); Lomax, Antony J. [Centre for Proton Therapy, Paul Scherrer Institute, Villigen-PSI (Switzerland); Bijl, Hendrik P.; Schilstra, Cornelis [Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen (Netherlands); Hug, Eugen B. [Centre for Proton Therapy, Paul Scherrer Institute, Villigen-PSI (Switzerland); Langendijk, Johannes A. [Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen (Netherlands)

    2012-02-01

    Purpose: To investigate whether intensity-modulated proton therapy with a reduced spot size (rsIMPT) could further reduce the parotid and submandibular gland dose compared with previously calculated IMPT plans with a larger spot size. In addition, it was investigated whether the obtained dose reductions would theoretically translate into a reduction of normal tissue complication probabilities (NTCPs). Methods: Ten patients with N0 oropharyngeal cancer were included in a comparative treatment planning study. Both IMPT plans delivered simultaneously 70 Gy to the boost planning target volume (PTV) and 54 Gy to the elective nodal PTV. IMPT and rsIMPT used identical three-field beam arrangements. In the IMPT plans, the parotid and submandibular salivary glands were spared as much as possible. rsIMPT plans used identical dose-volume objectives for the parotid glands as those used by the IMPT plans, whereas the objectives for the submandibular glands were tightened further. NTCPs were calculated for salivary dysfunction and xerostomia. Results: Target coverage was similar for both IMPT techniques, whereas rsIMPT clearly improved target conformity. The mean doses in the parotid glands and submandibular glands were significantly lower for three-field rsIMPT (14.7 Gy and 46.9 Gy, respectively) than for three-field IMPT (16.8 Gy and 54.6 Gy, respectively). Hence, rsIMPT significantly reduced the NTCP of patient-rated xerostomia and parotid and contralateral submandibular salivary flow dysfunction (27%, 17%, and 43% respectively) compared with IMPT (39%, 20%, and 79%, respectively). In addition, mean dose values in the sublingual glands, the soft palate and oral cavity were also decreased. Obtained dose and NTCP reductions varied per patient. Conclusions: rsIMPT improved sparing of the salivary glands and reduced NTCP for xerostomia and parotid and submandibular salivary dysfunction, while maintaining similar target coverage results. It is expected that rsIMPT improves quality

  2. Focal spot size reduction using asymmetric collimation to enable reduced anode angles with a conventional angiographic x-ray tube for use with high resolution detectors

    Science.gov (United States)

    Russ, M.; Shankar, A.; Setlur Nagesh, S. V.; Ionita, C. N.; Bednarek, D. R.; Rudin, S.

    2017-03-01

    The high-resolution requirements for neuro-endovascular image-guided interventions (EIGIs) necessitate the use of a small focal-spot size; however, the maximum tube output limits for such small focal-spot sizes may not enable sufficient x-ray fluence after attenuation through the human head to support the desired image quality. This may necessitate the use of a larger focal spot, thus contributing to the overall reduction in resolution. A method for creating a higher-output small effective focal spot based on the line-focus principle has been demonstrated and characterized. By tilting the C-arm gantry, the anode-side of the x-ray field-of-view is accessible using a detector placed off-axis. This tilted central axis diminishes the resultant focal spot size in the anode-cathode direction by the tangent of the effective anode angle, allowing a medium focal spot to be used in place of a small focal spot with minimal losses in resolution but with increased tube output. Images were acquired of two different objects at the central axis, and with the C-arm tilted away from the central axis at 1° increments from 0°-7°. With standard collimation settings, only 6° was accessible, but using asymmetric extended collimation a maximum of 7° was accessed for enhanced comparisons. All objects were positioned perpendicular to the anode-cathode direction and images were compared qualitatively. The increasing advantage of the off-axis focal spots was quantitatively evidenced at each subsequent angle using the Generalized Measured-Relative Object Detectability metric (GM-ROD). This anode-tilt method is a simple and robust way of increasing tube output for a small field-of-view detector without diminishing the overall apparent resolution for neuro-EIGIs.

  3. Size-segregated aerosol in a hot-spot pollution urban area: Chemical composition and three-way source apportionment.

    Science.gov (United States)

    Bernardoni, V; Elser, M; Valli, G; Valentini, S; Bigi, A; Fermo, P; Piazzalunga, A; Vecchi, R

    2017-12-01

    In this work, a comprehensive characterisation and source apportionment of size-segregated aerosol collected using a multistage cascade impactor was performed. The samples were collected during wintertime in Milan (Italy), which is located in the Po Valley, one of the main pollution hot-spot areas in Europe. For every sampling, size-segregated mass concentration, elemental and ionic composition, and levoglucosan concentration were determined. Size-segregated data were inverted using the program MICRON to identify and quantify modal contributions of all the measured components. The detailed chemical characterisation allowed the application of a three-way (3-D) receptor model (implemented using Multilinear Engine) for size-segregated source apportionment and chemical profiles identification. It is noteworthy that - as far as we know - this is the first time that three-way source apportionment is attempted using data of aerosol collected by traditional cascade impactors. Seven factors were identified: wood burning, industry, resuspended dust, regional aerosol, construction works, traffic 1, and traffic 2. Further insights into size-segregated factor profiles suggested that the traffic 1 factor can be associated to diesel vehicles and traffic 2 to gasoline vehicles. The regional aerosol factor resulted to be the main contributor (nearly 50%) to the droplet mode (accumulation sub-mode with modal diameter in the range 0.5-1 μm), whereas the overall contribution from the two factors related to traffic was the most important one in the other size modes (34-41%). The results showed that applying a 3-D receptor model to size-segregated samples allows identifying factors of local and regional origin while receptor modelling on integrated PM fractions usually singles out factors characterised by primary (e.g. industry, traffic, soil dust) and secondary (e.g. ammonium sulphate and nitrate) origin. Furthermore, the results suggested that the information on size

  4. Formation of metal nanoparticles of various sizes in plasma plumes produced by Ti:sapphire laser pulses

    International Nuclear Information System (INIS)

    Chakravarty, U.; Naik, P. A.; Mukherjee, C.; Kumbhare, S. R.; Gupta, P. D.

    2010-01-01

    In this paper, an experimental study on generation of nanoparticle various sizes using Ti:sapphire laser pulses, is reported. Nanoparticle formation in plasma plumes of metals like silver and copper, expanding in vacuum, has been studied using stretched pulses of 300 ps duration [subnanoseconds (sub-ns)] from a Ti:sapphire laser. It has been compared with the nanoparticle formation (of the same materials) when compressed pulses of 45 fs duration were used under similar focusing conditions. Nanoparticle formation is observed at intensities as high as 2x10 16 W/cm 2 . The structural analysis of the nanoparticle deposition on a silicon substrate showed that, using 45 fs pulses, smaller nanoparticles of average size ∼20 nm were generated, whereas on using the sub-ns pulses, larger particles were produced. Also, the visible light transmission and reflection from the nanoparticle film of Ag on glass substrate showed surface plasmon resonance (SPR). The SPR curves of the films of nanoparticles deposited by femtosecond pulses were always broader and reflection/transmission was always smaller when compared with the films formed using the sub-ns pulses, indicating smaller size particle formation by ultrashort pulses. Thus, it has been demonstrated that variation in the laser pulse duration of laser offers a simple tool for varying the size of the nanoparticles generated in plasma plumes.

  5. Study on pulsed-discharge devices with high current rising rate for point spot short-wavelength source in dense plasma observations

    International Nuclear Information System (INIS)

    Tachinami, Fumitaka; Anzai, Nobuyuki; Sasaki, Toru; Kikuchi, Takashi; Harada, Nob.

    2014-01-01

    A pulsed-power generator with high current rise based on a pulse-forming-network was studied toward generating intense point-spot X-ray source. To obtain the high rate of current rise, we have designed the compact discharge device with low circuit inductance. The results indicate that the inductance of the compact discharge device was dominated by a gap switch inductance. To reduce the gap switch inductance and operation voltage, the feasible gap switch inductance in the vacuum chamber has been estimated by the circuit simulation. The gap switch inductance can be reduced by the lower pressure operation. It means that the designed discharge device achieves the rate of current rise of 10 12 A/s

  6. Effect of spot size and fluence on Q-switched alexandrite laser treatment for pigmentation in Asians: a randomized, double-blinded, split-face comparative trial.

    Science.gov (United States)

    Wang, Chia-Chen; Chen, Chih-Kang

    2012-10-01

    Q-switched laser treatment for pigment disorders commonly leads to postinflammatory hyperpigmentation (PIH) in Asians. To evaluate the effect of spot size and fluence on Q-switched alexandrite laser (QSAL) treatment for pigmentation in Asians. Ten patients with freckles, 18 with lentigines, and 8 with acquired bilateral nevus of Ota-like macules (ABNOM) received 1 session of QSAL treatment for a 3-mm spot on one cheek and a 4-mm spot on the other cheek. The lowest fluences to achieve a visible biologic effect were chosen. The patients with freckles experienced the highest improvement rate (83-84%), followed by those with lentigines (52%) and ABNOM (35%). Similar efficacy was observed for both cheeks (p > 0.05). PIH developed in 10% (1/10), 44% (8/18), and 75% (6/8) of the patients with freckles, lentigines, and ABNOM, respectively. The severity of PIH was lower in the 4-mm spot with a lower fluence than in the 3-mm spot with a higher fluence in patients with lentigines (p = 0.03), but not in those with freckles or ABNOM. Using a larger spot to achieve the same biologic effect at a lower fluence is associated with equal efficacy and less-severe PIH in patients with lentigines.

  7. Method for measuring the focal spot size of an x-ray tube using a coded aperture mask and a digital detector.

    Science.gov (United States)

    Russo, Paolo; Mettivier, Giovanni

    2011-04-01

    The goal of this study is to evaluate a new method based on a coded aperture mask combined with a digital x-ray imaging detector for measurements of the focal spot sizes of diagnostic x-ray tubes. Common techniques for focal spot size measurements employ a pinhole camera, a slit camera, or a star resolution pattern. The coded aperture mask is a radiation collimator consisting of a large number of apertures disposed on a predetermined grid in an array, through which the radiation source is imaged onto a digital x-ray detector. The method of the coded mask camera allows one to obtain a one-shot accurate and direct measurement of the two dimensions of the focal spot (like that for a pinhole camera) but at a low tube loading (like that for a slit camera). A large number of small apertures in the coded mask operate as a "multipinhole" with greater efficiency than a single pinhole, but keeping the resolution of a single pinhole. X-ray images result from the multiplexed output on the detector image plane of such a multiple aperture array, and the image of the source is digitally reconstructed with a deconvolution algorithm. Images of the focal spot of a laboratory x-ray tube (W anode: 35-80 kVp; focal spot size of 0.04 mm) were acquired at different geometrical magnifications with two different types of digital detector (a photon counting hybrid silicon pixel detector with 0.055 mm pitch and a flat panel CMOS digital detector with 0.05 mm pitch) using a high resolution coded mask (type no-two-holes-touching modified uniformly redundant array) with 480 0.07 mm apertures, designed for imaging at energies below 35 keV. Measurements with a slit camera were performed for comparison. A test with a pinhole camera and with the coded mask on a computed radiography mammography unit with 0.3 mm focal spot was also carried out. The full width at half maximum focal spot sizes were obtained from the line profiles of the decoded images, showing a focal spot of 0.120 mm x 0.105 mm at 35

  8. The influence of tested body size upon longitudinal ultrasonic pulse velocity

    International Nuclear Information System (INIS)

    Suarez Antola, R.

    2001-01-01

    Low ultrasonic frequencies are used in nondestructive testing of heterogeneous materials,such as concrete,rocks and timber.When frequencies are low enough,size and shape of tested bodies may influence measured longitudinal pulse velocities(geometric dispersion).A simplified mathematical model is developed from known experimental and theoretical results obtained for elastic wave propagation in rods of uniform circular cross section.Wave propagation is described by a spatial averaged dilatational field in an approach which is named quasi fluid.A formula is obtained which relates group velocity with an effective lateral size of the body,with transducers a frequency,with a non-dimensional parameter and with asymptotic P-wave velocity.In principle it can be applied to bars of any uniform cross section.The limitations of this formula are discussed in relation to path length,threshold of detection,patterns of radiation and reception and other variables.A more general formula is proposed.Practical application of this formula is briefly exemplified using some experimental data obtained by the author.The problem of longitudinal pulse propagation in reinforcing steel bars embedded in concrete is briefly considered

  9. Simulation of the impact of refractive surgery ablative laser pulses with a flying-spot laser beam on intrasurgery corneal temperature.

    Science.gov (United States)

    Shraiki, Mario; Arba-Mosquera, Samuel

    2011-06-01

    To evaluate ablation algorithms and temperature changes in laser refractive surgery. The model (virtual laser system [VLS]) simulates different physical effects of an entire surgical process, simulating the shot-by-shot ablation process based on a modeled beam profile. The model is comprehensive and directly considers applied correction; corneal geometry, including astigmatism; laser beam characteristics; and ablative spot properties. Pulse lists collected from actual treatments were used to simulate the temperature increase during the ablation process. Ablation efficiency reduction in the periphery resulted in a lower peripheral temperature increase. Steep corneas had lesser temperature increases than flat ones. The maximum rise in temperature depends on the spatial density of the ablation pulses. For the same number of ablative pulses, myopic corrections showed the highest temperature increase, followed by myopic astigmatism, mixed astigmatism, phototherapeutic keratectomy (PTK), hyperopic astigmatism, and hyperopic treatments. The proposed model can be used, at relatively low cost, for calibration, verification, and validation of the laser systems used for ablation processes and would directly improve the quality of the results.

  10. Detecting cm-scale hot spot over 24-km-long single-mode fiber by using differential pulse pair BOTDA based on double-peak spectrum.

    Science.gov (United States)

    Diakaridia, Sanogo; Pan, Yue; Xu, Pengbai; Zhou, Dengwang; Wang, Benzhang; Teng, Lei; Lu, Zhiwei; Ba, Dexin; Dong, Yongkang

    2017-07-24

    In distributed Brillouin optical fiber sensor when the length of the perturbation to be detected is much smaller than the spatial resolution that is defined by the pulse width, the measured Brillouin gain spectrum (BGS) experiences two or multiple peaks. In this work, we propose and demonstrate a technique using differential pulse pair Brillouin optical time-domain analysis (DPP-BOTDA) based on double-peak BGS to enhance small-scale events detection capability, where two types of single mode fiber (main fiber and secondary fiber) with 116 MHz Brillouin frequency shift (BFS) difference have been used. We have realized detection of a 5-cm hot spot at the far end of 24-km single mode fiber by employing a 50-cm spatial resolution DPP-BOTDA with only 1GS/s sampling rate (corresponding to 10 cm/point). The BFS at the far end of 24-km sensing fiber has been measured with 0.54 MHz standard deviation which corresponds to a 0.5°C temperature accuracy. This technique is simple and cost effective because it is implemented using the similar experimental setup of the standard BOTDA, however, it should be noted that the consecutive small-scale events have to be separated by a minimum length corresponding to the spatial resolution defined by the pulse width difference.

  11. The effect of laser power, traverse velocity and spot size on the peel resistance of a polypropylene/adhesive bond

    OpenAIRE

    Dowding, Colin; Dowding, Robert; Franceschini, Federica; Griffiths, Jonathan David

    2015-01-01

    Abstract The mean peel resistance force achieved with respect to variation in the laser power, incident spot traverse velocity and incident spot diameter between linear low density polyethylene film backed by a thin commercial adhesive coating that were bonded to a polypropylene substrate via thermal activation provided by a 27W CO 2 laser is discussed in this work. The results gathered for this work have been used to generate a novel empirical tool that predicts the CO...

  12. Quantitative effects of rapid heating on soot-particle sizing through analysis of two-pulse LII

    KAUST Repository

    Cenker, Emre; Roberts, William L.

    2017-01-01

    particle size, respectively. Overall, effects of these two processes on soot and LII model-based particle sizing are investigated by measuring the two-color time-resolved (2C-TiRe) LII signal decay from in-flame soot after two consecutive laser pulses

  13. Effects of high repetition rate and beam size on hard tissue damage due to subpicosecond laser pulses

    International Nuclear Information System (INIS)

    Kim, Beop-Min; Feit, Michael D.; Rubenchik, Alexander M.; Joslin, Elizabeth J.; Eichler, Juergen; Stoller, Patrick C.; Da Silva, Luiz B.

    2000-01-01

    We report the effects of the repetition rate and the beam size on the threshold for ultrashort laser pulse induced damage in dentin. The observed results are explained as cumulative thermal effects. Our model is consistent with the experimental results and explains the dependence of the threshold on repetition rate, beam size, and exposure time. (c) 2000 American Institute of Physics

  14. Effect of pulsed electric fields treatment and mash size on extraction and composition of apple juices.

    Science.gov (United States)

    Turk, Mohammad F; Baron, Alain; Vorobiev, Eugene

    2010-09-08

    This study explored the effect of pulsed electric field (PEF) treatment (E=450 V/cm; tt=10 ms; Eapple mash size on juice yield, polyphenolic compounds, sugars, and malic acid. Juice yield increased significantly after PEF treatment of large mash (Y=71.4%) and remained higher than the juice yield obtained for a control small mash (45.6%). The acid sweet balance was not altered by PEF. A correlation was established between the decrease of light absorbance (control: 1.43; treated: 1.10) and the decline of native polyphenols yield due to PEF treatment (control: 9.6%; treated: 5.9% for small mash). An enhanced oxidation of phenolic compounds in cells due to electroporation of the inner cell membrane and the adsorption of the oxidized products on the mash may explain both the lower light absorbance and the lower native polyphenol concentration.

  15. Liver spots

    Science.gov (United States)

    ... skin changes - liver spots; Senile or solar lentigines; Skin spots - aging; Age spots ... Liver spots are changes in skin color that occur in older skin. The coloring may be due to aging, exposure to the sun ...

  16. Numerical studies of triplet and Russian quadruplet quadrupole lens systems with the given spot size on the target, for use in a microprobe

    Energy Technology Data Exchange (ETDEWEB)

    Brazhnik, V A; Lebed, S A; Ponomarev, A G; Storizhko, V E [Ukrainian Academy of Sciences, Sumy (Ukraine). Applied Physics Institute; Dymnikov, A D [University of St Petersburg, Stary (Russian Federation). Institute of Computational Mathematics and Control Processes; Jamieson, D N; Legge, S A [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1994-12-31

    In a nuclear microprobe the focusing system is an essential component which determines the beam spot size, i.e. the microprobe resolution. A small beam cross section at the target is the most important of the many conflicting requirements imposed on the beam The second most important factor is the current of the beam which at the given brightness is proportional to the phase volume (or emittance) of the beam. Existing microprobes frequently use a triplet or a Russian quadruplet as the focusing systems. This paper describes the numerical studies of some optimal quadrupole lens systems consisting of three or four lenses suitable for use in a nuclear microprobe taking into account geometrical aberrations of third order. The maximum emittance of changed particle beams for these systems has been found. It is shown how the maximum emittance depends on the spot size. 2 refs., 2 figs.

  17. Numerical studies of triplet and Russian quadruplet quadrupole lens systems with the given spot size on the target, for use in a microprobe

    Energy Technology Data Exchange (ETDEWEB)

    Brazhnik, V.A.; Lebed, S.A.; Ponomarev, A.G.; Storizhko, V.E. [Ukrainian Academy of Sciences, Sumy (Ukraine). Applied Physics Institute; Dymnikov, A.D. [University of St Petersburg, Stary (Russian Federation). Institute of Computational Mathematics and Control Processes; Jamieson, D.N.; Legge, S.A. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1993-12-31

    In a nuclear microprobe the focusing system is an essential component which determines the beam spot size, i.e. the microprobe resolution. A small beam cross section at the target is the most important of the many conflicting requirements imposed on the beam The second most important factor is the current of the beam which at the given brightness is proportional to the phase volume (or emittance) of the beam. Existing microprobes frequently use a triplet or a Russian quadruplet as the focusing systems. This paper describes the numerical studies of some optimal quadrupole lens systems consisting of three or four lenses suitable for use in a nuclear microprobe taking into account geometrical aberrations of third order. The maximum emittance of changed particle beams for these systems has been found. It is shown how the maximum emittance depends on the spot size. 2 refs., 2 figs.

  18. Design optimization and tolerance analysis of a spot-size converter for the taper-assisted vertical integration platform in InP.

    Science.gov (United States)

    Tolstikhin, Valery; Saeidi, Shayan; Dolgaleva, Ksenia

    2018-05-01

    We report on the design optimization and tolerance analysis of a multistep lateral-taper spot-size converter based on indium phosphide (InP), performed using the Monte Carlo method. Being a natural fit to (and a key building block of) the regrowth-free taper-assisted vertical integration platform, such a spot-size converter enables efficient and displacement-tolerant fiber coupling to InP-based photonic integrated circuits at a wavelength of 1.31 μm. An exemplary four-step lateral-taper design featuring 0.35 dB coupling loss at optimal alignment of a standard single-mode fiber; ≥7  μm 1 dB displacement tolerance in any direction in a facet plane; and great stability against manufacturing variances is demonstrated.

  19. Numerical studies of triplet and Russian quadruplet quadrupole lens systems with the given spot size on the target, for use in a microprobe

    International Nuclear Information System (INIS)

    Brazhnik, V.A.; Lebed, S.A.; Ponomarev, A.G.; Storizhko, V.E.; Dymnikov, A.D.; Jamieson, D.N.; Legge, S.A.

    1993-01-01

    In a nuclear microprobe the focusing system is an essential component which determines the beam spot size, i.e. the microprobe resolution. A small beam cross section at the target is the most important of the many conflicting requirements imposed on the beam The second most important factor is the current of the beam which at the given brightness is proportional to the phase volume (or emittance) of the beam. Existing microprobes frequently use a triplet or a Russian quadruplet as the focusing systems. This paper describes the numerical studies of some optimal quadrupole lens systems consisting of three or four lenses suitable for use in a nuclear microprobe taking into account geometrical aberrations of third order. The maximum emittance of changed particle beams for these systems has been found. It is shown how the maximum emittance depends on the spot size. 2 refs., 2 figs

  20. Development and Clinical Implementation of a Universal Bolus to Maintain Spot Size During Delivery of Base of Skull Pencil Beam Scanning Proton Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Both, Stefan, E-mail: Stefan.Both@uphs.upenn.edu [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Shen, Jiajian [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Department of Radiation Oncology, Mayo Clinic, Phoenix, Arizona (United States); Kirk, Maura; Lin, Liyong; Tang, Shikui; Alonso-Basanta, Michelle; Lustig, Robert; Lin, Haibo; Deville, Curtiland; Hill-Kayser, Christine; Tochner, Zelig; McDonough, James [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania (United States)

    2014-09-01

    Purpose: To report on a universal bolus (UB) designed to replace the range shifter (RS); the UB allows the treatment of shallow tumors while keeping the pencil beam scanning (PBS) spot size small. Methods and Materials: Ten patients with brain cancers treated from 2010 to 2011 were planned using the PBS technique with bolus and the RS. In-air spot sizes of the pencil beam were measured and compared for 4 conditions (open field, with RS, and with UB at 2- and 8-cm air gap) in isocentric geometry. The UB was applied in our clinic to treat brain tumors, and the plans with UB were compared with the plans with RS. Results: A UB of 5.5 cm water equivalent thickness was found to meet the needs of the majority of patients. By using the UB, the PBS spot sizes are similar with the open beam (P>.1). The heterogeneity index was found to be approximately 10% lower for the UB plans than for the RS plans. The coverage for plans with UB is more conformal than for plans with RS; the largest increase in sparing is usually for peripheral organs at risk. Conclusions: The integrity of the physical properties of the PBS beam can be maintained using a UB that allows for highly conformal PBS treatment design, even in a simple geometry of the fixed beam line when noncoplanar beams are used.

  1. Growth and shape of indium islands on molybdenum at micro-roughened spots created by femtosecond laser pulses

    Science.gov (United States)

    Ringleb, F.; Eylers, K.; Teubner, Th.; Schramm, H.-P.; Symietz, C.; Bonse, J.; Andree, S.; Heidmann, B.; Schmid, M.; Krüger, J.; Boeck, T.

    2017-10-01

    Indium islands on molybdenum coated glass can be grown in ordered arrays by surface structuring using a femtosecond laser. The effect of varying the molybdenum coated glass substrate temperature and the indium deposition rate on island areal density, volume and geometry is investigated and evaluated in a physical vapor deposition (PVD) process. The joined impact of growth conditions and spacing of the femtosecond laser structured spots on the arrangement and morphology of indium islands is demonstrated. The results yield a deeper understanding of the island growth and its precise adjustment to industrial requirements, which is indispensable for a technological application of such structures at a high throughput, for instance as precursors for the preparation of Cu(In,Ga)Se2 micro concentrator solar cells.

  2. Influence of lateral target size on hot electron production and electromagnetic pulse emission from laser-irradiated metallic targets

    International Nuclear Information System (INIS)

    Chen Ziyu; Li Jianfeng; Yu Yong; Li Xiaoya; Peng Qixian; Zhu Wenjun; Wang Jiaxiang

    2012-01-01

    The influences of lateral target size on hot electron production and electromagnetic pulse emission from laser interaction with metallic targets have been investigated. Particle-in-cell simulations at high laser intensities show that the yield of hot electrons tends to increase with lateral target size, because the larger surface area reduces the electrostatic field on the target, owing to its expansion along the target surface. At lower laser intensities and longer time scales, experimental data characterizing electromagnetic pulse emission as a function of lateral target size also show target-size effects. Charge separation and a larger target tending to have a lower target potential have both been observed. The increase in radiation strength and downshift in radiation frequency with increasing lateral target size can be interpreted using a simple model of the electrical capacity of the target.

  3. Influence of lateral target size on hot electron production and electromagnetic pulse emission from laser-irradiated metallic targets

    Energy Technology Data Exchange (ETDEWEB)

    Chen Ziyu; Li Jianfeng; Yu Yong; Li Xiaoya; Peng Qixian; Zhu Wenjun [National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Wang Jiaxiang [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China)

    2012-11-15

    The influences of lateral target size on hot electron production and electromagnetic pulse emission from laser interaction with metallic targets have been investigated. Particle-in-cell simulations at high laser intensities show that the yield of hot electrons tends to increase with lateral target size, because the larger surface area reduces the electrostatic field on the target, owing to its expansion along the target surface. At lower laser intensities and longer time scales, experimental data characterizing electromagnetic pulse emission as a function of lateral target size also show target-size effects. Charge separation and a larger target tending to have a lower target potential have both been observed. The increase in radiation strength and downshift in radiation frequency with increasing lateral target size can be interpreted using a simple model of the electrical capacity of the target.

  4. Treatment of resistant tattoos using a new generation Q-switched Nd:YAG laser: influence of beam profile and spot size on clearance success.

    Science.gov (United States)

    Karsai, Syrus; Pfirrmann, Gudrun; Hammes, Stefan; Raulin, Christian

    2008-02-01

    Multiple treatments of resistant tattoos often result in fibrosis and visible textural changes that lessen response to subsequent treatments. The aim of this study is to evaluate the influence of beam profile and spot size on clearance rates and side effects in the setting of resistant tattoos. Thirty-six professional, black tattoos (32 patients) were treated unsuccessfully with a Q-switched Nd:YAG laser (MedLite C3, HoyaConBio Inc., Fremont, CA). Because of therapy resistance all tattoos were re-treated using a new generation Nd:YAG laser (MedLite C6, HoyaConBio Inc.). Maximum energy fluence (E (max)), mean energy fluence, mean spot size, level of clearance, side effects and beam profile (irradiance distribution) of both laser systems were assessed and evaluated in a retrospective study. All tattoos were previously treated with the C3 laser at 1,064 nm using a mean E(max) of 5.8+/-0.8 J/cm(2) (range 3.8-7.5 J/cm(2)) as compared with a mean E(max) of 6.4+/-1.6 J/cm(2) (range 3.2-9.0 J/cm(2)) during the C6 treatment course. Corresponding spot sizes were larger during C6 treatments as compared with C3 (5.0+/-0.9 and 3.6+/-0.2 mm, respectively). The C6 laser had a "flat top" and homogenous profile regardless of the spot size. For the C3 laser the beam shape was "Gaussian," and the homogeneity was reduced by numerous micro-spikes and micro-nadirs. After the C6 treatment course 33.3% of the tattoos showed clearance of grade 1 (0-25%), 16.7% of grade 2 (26-50%), 16.7% of grade 3 (51-75%), 30.5% of grade 4 (76-95%), 2.8% of grade 5 (96-100%). The total rate of side effects due to C6 treatment was 8.3% in all tattoos (hyperpigmentation 5.6%, hypopigmentation 2.7%, textural changes/scars 0%). This clinical study documents for the first time the impact of a 1,064-nm Nd:YAG laser with a more homogenous beam profile and a larger spot size on the management of resistant tattoos. Only a few treatment sessions were necessary to achieve an additional clearance with a low rate of

  5. Quantitation of size of myocardial infarctions by computerized transmission tomography. Comparison with hot-spot and cold-spot radionuclide scans

    International Nuclear Information System (INIS)

    Gerber, K.H.; Higgins, C.B.

    1983-01-01

    The current study evaluated the ability to quantitate the volume of myocardial infarctions when they are outlined by intravenously administered contrast media in the myocardial perfusion phase and in the phase of delayed contrast enhancement of the infarct. Quantitation by contrast media was assessed from computerized transmission tomography (CTT) scans of the ex situ heart and compared with quantitation by technetium-99m (/sup 99m/Tc)pyrophosphate (/sup 99m/Tc PYP) and thallium-201 (201Tl) scans of the same ex situ hearts. True volume was defined by histochemical morphometry. CTT during the contrast perfusion phase uniformly underestimated infarct size but had a good correlation with true volume. CTT during enhancement phase correlated closely with true volume (r . 0.98) and most precisely measured true size (y . 1.06 X 0.23). The /sup 99m/Tc PYP scan overestimated infarct volume (predictive overestimation of 6 to 199%) but had a good correlation with true volume. 201Tl underestimated infarct volume but correlated well with true volume. Thus, quantitation of infarct volume from CTT scans performed during either the perfusion or infarct enhancement phase after intravenous contrast media provides a good estimate of true infarct volume. Delineation of the infarct by contrast media in the ex situ heart is more precise during the phase of delayed enhancement of the infarct

  6. Quantitative effects of rapid heating on soot-particle sizing through analysis of two-pulse LII

    KAUST Repository

    Cenker, Emre

    2017-02-27

    During the rapid laser pulse heating and consecutive cooling in laser-induced incandescence (LII), soot particles may undergo thermal annealing and sublimation processes which lead to a permanent change in its optical properties and its primary particle size, respectively. Overall, effects of these two processes on soot and LII model-based particle sizing are investigated by measuring the two-color time-resolved (2C-TiRe) LII signal decay from in-flame soot after two consecutive laser pulses at 1064-nm wavelength. Experiments are carried out on a non-premixed laminar ethylene/air flame from a Santoro burner with both low and moderate laser fluences suitable for particle sizing. The probe volume is set to a radial position close to the flame axis where the soot particles are known to be immature or less graphitic. With the first pulse, soot is pre-heated, and the LII signal after the consecutive second pulse is used for analysis. The two-color incandescence emission technique is used for the pyrometric determination of the LII-heated peak soot temperature at the second pulse. A new LII simulation tool is developed which accounts for particle heating via absorption and annealing, and cooling via sublimation, conduction, and radiation with various existing sub-models from the literature. The same approach of using two laser pulses is implemented in the simulations. Measurements indicate that thermal annealing and associated absorption enhancement becomes important at laser fluences above 0.17 J/cm2 for the immature in-flame soot. After a heating pulse at 0.33 J/cm2, the increase of the soot absorption function is calculated as 35% using the temperature measured at the second pulse and an absorption model based on the Rayleigh approximation. Present annealing model, on the other hand, predicts graphitization of soot even in the absence of laser heating at typical flame temperatures. Recorded experimental LII signal decays and LII-heated peak soot temperature

  7. Enhancement of EUV emission from a liquid microjet target by use of dual laser pulses

    Science.gov (United States)

    Higashiguchi, Takeshi; Rajyaguru, Chirag; Koga, Masato; Kawasaki, Keita; Sasaki, Wataru; Kubodera, Shoichi; Kikuchi, Takashi; Yugami, Noboru; Kawata, Shigeo; Andreev, Alexander A.

    2005-03-01

    Extreme ultraviolet (EUV) radiation at the wavelength of around 13nm waws observed from a laser-produced plasma using continuous water-jet. Strong dependence of the conversion efficiency (CE) on the laser focal spot size and jet diameter was observed. The EUV CE at a given laser spot size and jet diameter was further enhanced using double laser pulses, where a pre-pulse was used for initial heating of the plasma.

  8. Is there a single spot size and grid for intensity modulated proton therapy? Simulation of head and neck, prostate and mesothelioma cases

    Energy Technology Data Exchange (ETDEWEB)

    Widesott, Lamberto; Lomax, Antony J.; Schwarz, Marco [AtreP, Agenzia Provinciale per la Protonterapia, 38122 Trento (Italy); Paul Scherrer Institute, 5232 Villigen (Switzerland); AtreP, Agenzia Provinciale per la Protonterapia, 38122 Trento (Italy)

    2012-03-15

    Purpose: To assess the quality of dose distributions in real clinical cases for different dimensions of scanned proton pencil beams. The distance between spots (i.e., the grid of delivery) is optimized for each dimension of the pencil beam. Methods: The authors vary the {sigma} of the initial Gaussian size of the spot, from {sigma}{sub x} = {sigma}{sub y} = 3 mm to {sigma}{sub x} = {sigma}{sub y} = 8 mm, to evaluate the impact of the proton beam size on the quality of intensity modulated proton therapy (IMPT) plans. The distance between spots, {Delta}x and {Delta}y, is optimized on the spot plane, ranging from 4 to 12 mm (i.e., each spot size is coupled with the best spot grid resolution). In our Hyperion treatment planning system (TPS), constrained optimization is applied with respect to the organs at risk (OARs), i.e., the optimization tries to satisfy the dose objectives in the planning target volume (PTV) as long as all planning objectives for the OARs are met. Three-field plans for a nasopharynx case, two-field plans for a prostate case, and two-field plans for a malignant pleural mesothelioma case are considered in our analysis. Results: For the head and neck tumor, the best grids (i.e., distance between spots) are 5, 4, 6, 6, and 8 mm for {sigma} = 3, 4, 5, 6, and 8 mm, respectively. {sigma} {<=} 5 mm is required for tumor volumes with low dose and {sigma}{<=} 4 mm for tumor volumes with high dose. For the prostate patient, the best grid is 4, 4, 5, 5, and 5 mm for {sigma} = 3, 4, 5, 6, and 8 mm, respectively. Beams with {sigma} > 3 mm did not satisfy our first clinical requirement that 95% of the prescribed dose is delivered to more than 95% of prostate and proximal seminal vesicles PTV. Our second clinical requirement, to cover the distal seminal vesicles PTV, is satisfied for beams as wide as {sigma} = 6 mm. For the mesothelioma case, the low dose PTV prescription is well respected for all values of {sigma}, while there is loss of high dose PTV coverage

  9. Rapid differentiation of rocky mountain spotted fever from chickenpox, measles, and enterovirus infections and bacterial meningitis by frequency-pulsed electron capture gas-liquid chromatographic analysis of sera.

    Science.gov (United States)

    Brooks, J B; McDade, J E; Alley, C C

    1981-01-01

    Normal sera and sera from patients with Rocky Mountain spotted fever, chickenpox, enterovirus infections, measles, and Neisseria meningitidis infections were extracted with organic solvents under acidic and basic conditions and then derivatized with trichloroethanol or heptafluorobutyric anhydride-ethanol to form electron-capturing derivatives of organic acids, alcohols, and amines. The derivatives were analyzed by frequency-pulsed electron capture gas-liquid chromatography (FPEC-GLC). There were unique differences in the FPEC-GLC profiles of sera obtained from patients with these respective diseases. With Rocky Mountain spotted fever patients, typical profiles were detected as early as 1 day after onset of disease and before antibody could be detected in the serum. Rapid diagnosis of Rocky Mountain spotted fever by FPEC-GLC could permit early and effective therapy, thus preventing many deaths from this disease. PMID:7276147

  10. Monte Carlo modeling of small photon fields: Quantifying the impact of focal spot size on source occlusion and output factors, and exploring miniphantom design for small-field measurements

    International Nuclear Information System (INIS)

    Scott, Alison J. D.; Nahum, Alan E.; Fenwick, John D.

    2009-01-01

    The accuracy with which Monte Carlo models of photon beams generated by linear accelerators (linacs) can describe small-field dose distributions depends on the modeled width of the electron beam profile incident on the linac target. It is known that the electron focal spot width affects penumbra and cross-field profiles; here, the authors explore the extent to which source occlusion reduces linac output for smaller fields and larger spot sizes. A BEAMnrc Monte Carlo linac model has been used to investigate the variation in penumbra widths and small-field output factors with electron spot size. A formalism is developed separating head scatter factors into source occlusion and flattening filter factors. Differences between head scatter factors defined in terms of in-air energy fluence, collision kerma, and terma are explored using Monte Carlo calculations. Estimates of changes in kerma-based source occlusion and flattening filter factors with field size and focal spot width are obtained by calculating doses deposited in a narrow 2 mm wide virtual ''milliphantom'' geometry. The impact of focal spot size on phantom scatter is also explored. Modeled electron spot sizes of 0.4-0.7 mm FWHM generate acceptable matches to measured penumbra widths. However the 0.5 cm field output factor is quite sensitive to electron spot width, the measured output only being matched by calculations for a 0.7 mm spot width. Because the spectra of the unscattered primary (Ψ Π ) and head-scattered (Ψ Σ ) photon energy fluences differ, miniphantom-based collision kerma measurements do not scale precisely with total in-air energy fluence Ψ=(Ψ Π +Ψ Σ ) but with (Ψ Π +1.2Ψ Σ ). For most field sizes, on-axis collision kerma is independent of the focal spot size; but for a 0.5 cm field size and 1.0 mm spot width, it is reduced by around 7% mostly due to source occlusion. The phantom scatter factor of the 0.5 cm field also shows some spot size dependence, decreasing by 6% (relative) as

  11. Model Predictions and Measured Skin Damage Thresholds for 1.54 Micrometers Laser Pulses in Porcine Skin

    National Research Council Canada - National Science Library

    Roach, William P; Cain, Clarence; Schuster, Kurt; Stockton, Kevin; Stolarski, David S; Galloway, Robert; Rockwell, Benjamin

    2004-01-01

    A new source-term thermal model was used to determine the skin temperature rise using porcine skin parameters for various wavelengths, pulse durations, and laser spot sizes and is compared to the Takata thermal model...

  12. The effect of laser pulse parameters and initial phase on the acceleration of electrons in a vacuum

    International Nuclear Information System (INIS)

    Singh, Kunwar Pal; Gupta, Devki Nandan; Malik, Hitendra K

    2008-01-01

    Laser driven acceleration of electrons lying along the axis of the laser has been studied. We have considered a linearly polarized laser pulse. The quiver amplitude causes electrons to escape from the pulse. The energy gained by the electrons peaks for a suitable value of laser spot size. The value of a suitable laser spot size increases with laser intensity and initial electron energy. The energy gained by the electron depends upon its initial position with respect to the laser pulse. The electrons close to the pulse peak with initial phase π/2 are scattered least and gain higher energy. The electrons close to the leading edge of the pulse gain sufficient energy for a short laser pulse and the effect of initial phase is not important. A suitable value of laser spot size can be estimated from this study

  13. Influence of media size on energy distribution of pulsed thermal neutrons

    International Nuclear Information System (INIS)

    Dabrowska, J.

    2007-01-01

    The work is devoted to the investigation of the diffusion cooling phenomenon of pulsed thermalized neutron fields in bounded media. It is aimed at the examination of the validity of the neutron temperature model that involves the assumption that an asymptotic energy distribution of neutrons in bounded media can be described by the Maxwell distribution but with a shifted temperature, lower than a temperature of medium. The research carried out entirely by means of Monte Carlo simulation of the neutron transport was preceded by a measurement of the time decay constants obtained in all variants of Monte Carlo simulations of the experiment and the measured one was stated. The form of asymptotic energy distribution of neutrons and its dependence on the size of medium was investigated in three kinds of materials of different thermal neutron transport properties: energy independent scatterer with negligible absorption (silica), energy dependent scatterer with 1/v absorption (borated silica) and energy dependent scatterer with 1/v absorption (water). As it was expected, in the case of large media, which can be treated as infinite, neutrons attained the Maxwell energy distribution at the temperature of the medium. For all materials under investigation the average and the most probable values of the energy distribution steadily decreased with decreasing geometric dimensions of the media. At the same time a growing distortion from the pure Maxwellian energy distribution was observed, which means that the concept of the neutron temperature fails in the case of small media. Although the spectra under investigation in general did not have the Maxwellian shape, the most probable velocity in a neutron density distribution decreased linearly with the increasing geometric buckling of the medium. This dependence manifested a stronger cooling than the one predicted by a certain approximate formula. The neutron spectrum in a small medium of pure silica was cooler than the spectrum in

  14. Probing Growth-Induced Anisotropic Thermal Transport in High-Quality CVD Diamond Membranes by Multifrequency and Multiple-Spot-Size Time-Domain Thermoreflectance.

    Science.gov (United States)

    Cheng, Zhe; Bougher, Thomas; Bai, Tingyu; Wang, Steven Y; Li, Chao; Yates, Luke; Foley, Brian M; Goorsky, Mark; Cola, Baratunde A; Faili, Firooz; Graham, Samuel

    2018-02-07

    The maximum output power of GaN-based high-electron mobility transistors is limited by high channel temperature induced by localized self-heating, which degrades device performance and reliability. Chemical vapor deposition (CVD) diamond is an attractive candidate to aid in the extraction of this heat and in minimizing the peak operating temperatures of high-power electronics. Owing to its inhomogeneous structure, the thermal conductivity of CVD diamond varies along the growth direction and can differ between the in-plane and out-of-plane directions, resulting in a complex three-dimensional (3D) distribution. Depending on the thickness of the diamond and size of the electronic device, this 3D distribution may impact the effectiveness of CVD diamond in device thermal management. In this work, time-domain thermoreflectance is used to measure the anisotropic thermal conductivity of an 11.8 μm-thick high-quality CVD diamond membrane from its nucleation side. Starting with a spot-size diameter larger than the thickness of the membrane, measurements are made at various modulation frequencies from 1.2 to 11.6 MHz to tune the heat penetration depth and sample the variation in thermal conductivity. We then analyze the data by creating a model with the membrane divided into ten sublayers and assume isotropic thermal conductivity in each sublayer. From this, we observe a two-dimensional gradient of the depth-dependent thermal conductivity for this membrane. The local thermal conductivity goes beyond 1000 W/(m K) when the distance from the nucleation interface only reaches 3 μm. Additionally, by measuring the same region with a smaller spot size at multiple frequencies, the in-plane and cross-plane thermal conductivities are extracted. Through this use of multiple spot sizes and modulation frequencies, the 3D anisotropic thermal conductivity of CVD diamond membrane is experimentally obtained by fitting the experimental data to a thermal model. This work provides an improved

  15. Droplet size characteristics and energy input requirements of emulsions formed using high-intensity-pulsed electric fields

    International Nuclear Information System (INIS)

    Scott, T.C.; Sisson, W.G.

    1987-01-01

    Experimental methods have been developed to measure droplet size characteristics and energy inputs associated with the rupture of aqueous droplets by high-intensity-pulsed electric fields. The combination of in situ microscope optics and high-speed video cameras allows reliable observation of liquid droplets down to 0.5 μm in size. Videotapes of electric-field-created emulsions reveal that average droplet sizes of less than 5 μm are easily obtained in such systems. Analysis of the energy inputs into the fluids indicates that the electric field method requires less than 1% of the energy required from mechanical agitation to create comparable droplet sizes. 11 refs., 3 figs., 2 tabs

  16. Enhancement of coercivity with reduced grain size in CoCrPt film grown by pulsed laser deposition

    International Nuclear Information System (INIS)

    Liang, Q.; Hu, X.F.; Li, H.Q.; He, X.X.; Wang, Xiaoru; Zhang, W.

    2006-01-01

    We report a pulsed laser deposition (PLD) growth of VMn/CoCrPt bilayer with a magnetic coercivity (H c ) of 2.2 kOe and a grain size of 12 nm. The effects of VMn underlayer on magnetic properties of CoCrPt layer were studied. The coercivity, H c , and squareness, S, of VMn/CoCrPt bilayer, is dependent on the thickness of VMn. The grain size of the CoCrPt film can also be modified by laser parameters. High laser fluence used for CoCrPt deposition produces a smaller grain size. Enhanced H c and reduced grain size in VMn/CoCrPt is explained by more pronounced surface phase segregation during deposition at high laser fluence

  17. Weld nugget formation in resistance spot welding of new lightweight sandwich material

    DEFF Research Database (Denmark)

    Sagüés Tanco, J.; Nielsen, Chris Valentin; Chergui, Azeddine

    2015-01-01

    Weldability of a new lightweight sandwich material, LITECOR®, by resistance spot welding is analyzed by experiments and numerical simulations. The spot welding process is accommodated by a first pulse squeezing out the non-conductive polymer core of the sandwich material locally to allow metal......–metal contact. This is facilitated by the use of a shunt tool and is followed by a second pulse for the actual spot welding and nugget formation. A weldability lobe in the time-current space of the second pulse reveals a process window of acceptable size for automotive assembly lines. Weld growth curves...... with experimental results in the range of welding parameters leading to acceptable weld nugget sizes. The validated accuracy of the commercially available software proves the tool useful for assisting the choice of welding parameters....

  18. Using penumbral imaging to measure micrometer size plasma hot spots in Gbar equation of state experiments on the National Ignition Facility.

    Science.gov (United States)

    Bachmann, B; Kritcher, A L; Benedetti, L R; Falcone, R W; Glenn, S; Hawreliak, J; Izumi, N; Kraus, D; Landen, O L; Le Pape, S; Ma, T; Pérez, F; Swift, D; Döppner, T

    2014-11-01

    We have developed an experimental platform for absolute equation of state measurements up to Gbar pressures on the National Ignition Facility (NIF) within the Fundamental Science Program. We use a symmetry-tuned hohlraum drive to launch a spherical shock wave into a solid CH sphere. Streaked radiography is the primary diagnostic to measure the density change at the shock front as the pressure increases towards smaller radii. At shock stagnation in the center of the capsule, we observe a short and bright x-ray self emission from high density (∼50 g/cm(3)) plasma at ∼1 keV. Here, we present results obtained with penumbral imaging which has been carried out to characterize the size of the hot spot emission. This allows extending existing NIF diagnostic capabilities for spatial resolution (currently ∼10 μm) at higher sensitivity. At peak emission we find the hot spot radius to be as small as 5.8 +/- 1 μm, corresponding to a convergence ratio of 200.

  19. Using penumbral imaging to measure micrometer size plasma hot spots in Gbar equation of state experiments on the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Bachmann, B., E-mail: bachmann2@llnl.gov; Kritcher, A. L.; Benedetti, L. R.; Glenn, S.; Hawreliak, J.; Izumi, N.; Landen, O. L.; Le Pape, S.; Ma, T.; Pérez, F.; Swift, D.; Döppner, T. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Falcone, R. W. [Department of Physics, University of California, Berkeley, California 94720 (United States); Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kraus, D. [Department of Physics, University of California, Berkeley, California 94720 (United States)

    2014-11-15

    We have developed an experimental platform for absolute equation of state measurements up to Gbar pressures on the National Ignition Facility (NIF) within the Fundamental Science Program. We use a symmetry-tuned hohlraum drive to launch a spherical shock wave into a solid CH sphere. Streaked radiography is the primary diagnostic to measure the density change at the shock front as the pressure increases towards smaller radii. At shock stagnation in the center of the capsule, we observe a short and bright x-ray self emission from high density (∼50 g/cm{sup 3}) plasma at ∼1 keV. Here, we present results obtained with penumbral imaging which has been carried out to characterize the size of the hot spot emission. This allows extending existing NIF diagnostic capabilities for spatial resolution (currently ∼10 μm) at higher sensitivity. At peak emission we find the hot spot radius to be as small as 5.8 +/− 1 μm, corresponding to a convergence ratio of 200.

  20. Using penumbral imaging to measure micrometer size plasma hot spots in Gbar equation of state experiments on the National Ignition Facility

    International Nuclear Information System (INIS)

    Bachmann, B.; Kritcher, A. L.; Benedetti, L. R.; Glenn, S.; Hawreliak, J.; Izumi, N.; Landen, O. L.; Le Pape, S.; Ma, T.; Pérez, F.; Swift, D.; Döppner, T.; Falcone, R. W.; Kraus, D.

    2014-01-01

    We have developed an experimental platform for absolute equation of state measurements up to Gbar pressures on the National Ignition Facility (NIF) within the Fundamental Science Program. We use a symmetry-tuned hohlraum drive to launch a spherical shock wave into a solid CH sphere. Streaked radiography is the primary diagnostic to measure the density change at the shock front as the pressure increases towards smaller radii. At shock stagnation in the center of the capsule, we observe a short and bright x-ray self emission from high density (∼50 g/cm 3 ) plasma at ∼1 keV. Here, we present results obtained with penumbral imaging which has been carried out to characterize the size of the hot spot emission. This allows extending existing NIF diagnostic capabilities for spatial resolution (currently ∼10 μm) at higher sensitivity. At peak emission we find the hot spot radius to be as small as 5.8 +/− 1 μm, corresponding to a convergence ratio of 200

  1. Cavitation enhances coagulated size during pulsed high-intensity focussed ultrasound ablation in an isolated liver perfusion system.

    Science.gov (United States)

    Zhao, Lu-Yan; Liu, Shan; Chen, Zong-Gui; Zou, Jian-Zhong; Wu, Feng

    2016-11-24

    To investigate whether cavitation enhances the degree of coagulation during pulsed high-intensity focussed ultrasound (HIFU) in an isolated liver perfusion system. Isolated liver was treated by pulsed HIFU or continuous-wave HIFU with different portal vein flow rates. The cavitation emission during exposure was recorded, and real-time ultrasound images were used to observe changes in the grey scale. The coagulation size was measured and calculated. HIFU treatment led to complete coagulation necrosis and total cell destruction in the target regions. Compared to exposure at a duty cycle (DC) of 100%, the mean volumes of lesions induced by 6 s exposure at DCs of 50% and 10% were significantly larger (P cavitation activity for the pulsed-HIFU (P > .05). For continuous-wave HIFU exposure, there was a significant decrease in the necrosis volume and cavitation activity for exposure times of 1, 2, 3, 4, and 6 s with increasing portal perfusion rates. Perfusion flow rates negatively influence cavitation activity and coagulation volume. Ablation is significantly enhanced during pulsed HIFU exposure compared with continuous-wave HIFU.

  2. Robustness of unstable attractors in arbitrarily sized pulse-coupled networks with delay

    NARCIS (Netherlands)

    Broer, Hendrik; Efstathiou, Konstantinos; Subramanian, Easwar

    We consider arbitrarily large networks of pulse-coupled oscillators with non-zero delay where the coupling is given by the Mirollo-Strogatz function. We prove that such systems have unstable attractors (saddle periodic orbits whose stable set has non-empty interior) in an open parameter region for

  3. Separation of large DNA molecules by applying pulsed electric field to size exclusion chromatography-based microchip

    Science.gov (United States)

    Azuma, Naoki; Itoh, Shintaro; Fukuzawa, Kenji; Zhang, Hedong

    2018-02-01

    Through electrophoresis driven by a pulsed electric field, we succeeded in separating large DNA molecules with an electrophoretic microchip based on size exclusion chromatography (SEC), which was proposed in our previous study. The conditions of the pulsed electric field required to achieve the separation were determined by numerical analyses using our originally proposed separation model. From the numerical results, we succeeded in separating large DNA molecules (λ DNA and T4 DNA) within 1600 s, which was approximately half of that achieved under a direct electric field in our previous study. Our SEC-based electrophoresis microchip will be one of the effective tools to meet the growing demand of faster and more convenient separation of large DNA molecules, especially in the field of epidemiological research of infectious diseases.

  4. Effect of laser energy on the SPR and size of silver nanoparticles synthesized by pulsed laser ablation in distilled water

    Science.gov (United States)

    Baruah, Prahlad K.; Sharma, Ashwini K.; Khare, Alika

    2018-04-01

    The effect of incident laser energy on the surface plasmon resonance (SPR) and size of silver nanoparticles synthesized via pulsed laser ablation of silver immersed in distilled water is reported in this paper. The broadening in the plasmonic bandwidth of the synthesized nanoparticles with the increase in the laser energy incident onto the silver target indicates the reduction in size of the nanoparticles. This is confirmed by the transmission electron microscope (TEM) images which show a decrease in the average particle size of the nanoparticles from approximately 15 to 10 nm with the increase in incident laser energy from 30 to 70 mJ, respectively. The structural features as revealed by the selected area electron diffraction and ultra-high resolution TEM studies confirmed the formation of both silver as well as silver oxide nanoparticles.

  5. Robustness of unstable attractors in arbitrarily sized pulse-coupled networks with delay

    International Nuclear Information System (INIS)

    Broer, Henk; Efstathiou, Konstantinos; Subramanian, Easwar

    2008-01-01

    We consider arbitrarily large networks of pulse-coupled oscillators with non-zero delay where the coupling is given by the Mirollo–Strogatz function. We prove that such systems have unstable attractors (saddle periodic orbits whose stable set has non-empty interior) in an open parameter region for three or more oscillators. The evolution operator of the system can be discontinuous and we propose an improved model with continuous evolution operator

  6. Small-sized monitor of beam current and profile for the proton pulse electrostatic accelerator

    International Nuclear Information System (INIS)

    Getmanov, V.N.

    1985-01-01

    Design and principle of operation of current monitor and beam profile of range-coordinate type are described. Monitor operation peculiarities are discussed using diagnostics of a beam of 330-420 keV electrostatic pulse proton accelerator with a beam current of up to 20 mA, at a current density of up to 23 mA x cm -2 and wth pulse duraton of about 20 μs. The monitor consists of a vacuum-dense foil of 3.0+-0.1 μm in thickness (or 0.81+-0.0x- mg x cm -2 ) two grid electrodes, each containing 12 wires, and as solid copper bottom. Foil serves for chopping off background particles with a path lesser 3.0 μm and stands thermal pulse load up to 0.5 J/cm -2 . Grid electrode wires are oriented perpendicularly to lach other and form a two-coordinate secondary-emisson roughness indicator. The bothhom is used for measuring an absolute value of beam current

  7. Optimal size of stochastic Hodgkin-Huxley neuronal systems for maximal energy efficiency in coding pulse signals

    Science.gov (United States)

    Yu, Lianchun; Liu, Liwei

    2014-03-01

    The generation and conduction of action potentials (APs) represents a fundamental means of communication in the nervous system and is a metabolically expensive process. In this paper, we investigate the energy efficiency of neural systems in transferring pulse signals with APs. By analytically solving a bistable neuron model that mimics the AP generation with a particle crossing the barrier of a double well, we find the optimal number of ion channels that maximizes the energy efficiency of a neuron. We also investigate the energy efficiency of a neuron population in which the input pulse signals are represented with synchronized spikes and read out with a downstream coincidence detector neuron. We find an optimal number of neurons in neuron population, as well as the number of ion channels in each neuron that maximizes the energy efficiency. The energy efficiency also depends on the characters of the input signals, e.g., the pulse strength and the interpulse intervals. These results are confirmed by computer simulation of the stochastic Hodgkin-Huxley model with a detailed description of the ion channel random gating. We argue that the tradeoff between signal transmission reliability and energy cost may influence the size of the neural systems when energy use is constrained.

  8. A parametric study of laser spot size and coverage on the laser shock peening induced residual stress in thin aluminium samples

    Directory of Open Access Journals (Sweden)

    M. Sticchi

    2015-07-01

    Full Text Available Laser Shock Peening is a fatigue enhancement treatment using laser energy to induce compressive Residual Stresses (RS in the outer layers of metallic components. This work describes the variations of introduced RS-field with peen size and coverage for thin metal samples treated with under-water-LSP. The specimens under investigation were of aluminium alloy AA2024-T351, AA2139-T3, AA7050-T76 and AA7075-T6, with thickness 1.9 mm. The RS were measured by using Hole Drilling with Electronic Speckle Pattern Interferometry and X-ray Diffraction. Of particular interest are the effects of the above mentioned parameters on the zero-depth value, which gives indication of the amount of RS through the thickness, and on the value of the surface compressive stresses, which indicates the magnitude of induced stresses. A 2D-axisymmetrical Finite Element model was created for a preliminary estimation of the stress field trend. From experimental results, correlated with numerical and analytical analysis, the following conclusions can be drawn: increasing the spot size the zero-depth value increases with no significant change of the maximum compressive stress; the increase of coverage leads to significant increase of the compressive stress; thin samples of Al-alloy with low Hugoniot Elastic Limit (HEL reveal deeper compression field than alloy with higher HEL value.

  9. Pulsed electrodeposition of cobalt nanoparticles on copper: influence of the operating parameters on size distribution and morphology

    International Nuclear Information System (INIS)

    Pagnanelli, Francesca; Altimari, Pietro; Bellagamba, Marco; Granata, Giuseppe; Moscardini, Emanuela; Schiavi, Pier Giorgio; Toro, Luigi

    2015-01-01

    Cobalt nanoparticles were synthesized by pulsed electrodeposition on copper substrate. Scanning electron microscopy and image analysis were used to determine morphology and particle size distribution of nanoparticle populations obtained in different operating conditions. After preliminary tests, t on and t off were set at 50 and 300 ms respectively to obtain distinct nanoparticles and avoid dendritic structures. Experimental tests were performed according to two partially superimposed factorial designs with two factors at two levels. First factorial design investigated the effect of current density (I = 10 and 50 mA/cm 2 ) and discharged cobalt (Q = 2.5 × 10 −3 and 1.0 × 10 −2 C); second factorial design investigated the effect of cobalt concentration (C 0 = 0.01 and 0.1 M) for the same two levels of Q. For optimized value of t on /t off , square and hexagonal shaped nanoparticles were obtained. Statistical analysis evidenced that, for C 0 = 0.1 mol/L, current density is the most influencing factor on mean size: increasing I from 10 to 50 mA/cm 2 determined a diminution of mean size of 240 nm. For the same cobalt concentration, increasing the deposition time (Q) determined an increase of mean size of 60 nm. Diminishing the initial cobalt concentration from 0.1 to 0.01 mol/L determined an increase of mean size from 10 nm to 36 nm. For C 0 = 0.01 mol/L nanoparticles grow reaching an optimal size (36 nm) and then, increasing the time of deposition, optimal sized subunits tend to aggregate. As for polydispersity of nanoparticles, statistical tests denoted that increasing I determined significant reduction of variance, while increasing the time of deposition determined a significant increase of variance

  10. Bier spots

    OpenAIRE

    Ahu Yorulmaz,; Seray Kulcu Cakmak; Esra Ar?; Ferda Artuz

    2015-01-01

    Also called as physiologic anemic macules, Bier spots are small, hypopigmented irregularly shaped macules against a background of diffuse erythema, which creates an appearance of speckled vascular mottling of the skin. Bier spots most commonly appear on distal portions of the limbs though there are case reports describing diffuse involvement, which also affect trunk and mucous membranes of the patient. Although the exact pathophysiological mechanisms underlying Bier spots still need to be elu...

  11. Effects of shape and size of agar gels on heating uniformity during pulsed microwave treatment.

    Science.gov (United States)

    Soto-Reyes, Nohemí; Temis-Pérez, Ana L; López-Malo, Aurelio; Rojas-Laguna, Roberto; Sosa-Morales, María Elena

    2015-05-01

    Model gel systems with different shape (sphere, cylinder, and slab) and size (180 and 290 g) were prepared with agar (5%) and sucrose (5%). Dielectric constant (ε'), loss factor (ε"), thermophysical properties, and temperature distribution of the model system were measured. Each agar model system was immersed and suspended in water, and then, heated in a microwave oven with intermittent heating until the core temperature reached 50 °C. The ε' and ε" of agar gels decreased when frequency increased. The density and thermal conductivity values of the agar gels were 1033 kg/m(3) and 0.55 W/m °C, respectively. The temperature distribution of sphere, cylinder, and slab was different when similar power doses were applied. The slab reached 50 °C in less time (10 min) and showed a more uniform heating than spheres and cylinders in both sizes. Agar model systems of 180 g heated faster than those of 290 g. The coldest point was the center of the model systems in all studied cases. Shape and size are critical food factors that affect the heating uniformity during microwave heating processes. © 2015 Institute of Food Technologists®

  12. Investigation of the particle size distribution of the ejected material generated during the single femtosecond laser pulse ablation of aluminium

    International Nuclear Information System (INIS)

    Wu, Han; Zhang, Nan; Zhu, Xiaonong

    2014-01-01

    Highlights: • Single 50 fs laser pulse ablation of an aluminium target in vacuum is investigated in our experiments. • Nanoparticles with large radii of several hundred nanometers are observed. • The nanoparticles are most likely from the mechanical tensile stress relaxation. - Abstract: Single femtosecond laser pulses are employed to ablate an aluminium target in vacuum, and the particle size distribution of the ablated material deposited on a mica substrate is examined with atomic force microscopy (AFM). The recorded AFM images show that these particles have a mean radius of several tens of nanometres. It is also determined that the mean radius of these deposited nanoparticles increases when the laser fluence at the aluminium target increases from 0.44 J/cm 2 to 0.63 J/cm 2 . The mechanism of the laser-induced nanoparticle generation is thought to be photomechanical tensile stress relaxation. Raman spectroscopy measurements confirm that the nanoparticles thus produced have the same structure as the bulk aluminium

  13. Size-based cell sorting with a resistive pulse sensor and an electromagnetic pump in a microfluidic chip.

    Science.gov (United States)

    Song, Yongxin; Li, Mengqi; Pan, Xinxiang; Wang, Qi; Li, Dongqing

    2015-02-01

    An electrokinetic microfluidic chip is developed to detect and sort target cells by size from human blood samples. Target-cell detection is achieved by a differential resistive pulse sensor (RPS) based on the size difference between the target cell and other cells. Once a target cell is detected, the detected RPS signal will automatically actuate an electromagnetic pump built in a microchannel to push the target cell into a collecting channel. This method was applied to automatically detect and sort A549 cells and T-lymphocytes from a peripheral fingertip blood sample. The viability of A549 cells sorted in the collecting well was verified by Hoechst33342 and propidium iodide staining. The results show that as many as 100 target cells per minute can be sorted out from the sample solution and thus is particularly suitable for sorting very rare target cells, such as circulating tumor cells. The actuation of the electromagnetic valve has no influence on RPS cell detection and the consequent cell-sorting process. The viability of the collected A549 cell is not impacted by the applied electric field when the cell passes the RPS detection area. The device described in this article is simple, automatic, and label-free and has wide applications in size-based rare target cell sorting for medical diagnostics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Bier spots

    Directory of Open Access Journals (Sweden)

    Ahu Yorulmaz,

    2015-10-01

    Full Text Available Also called as physiologic anemic macules, Bier spots are small, hypopigmented irregularly shaped macules against a background of diffuse erythema, which creates an appearance of speckled vascular mottling of the skin. Bier spots most commonly appear on distal portions of the limbs though there are case reports describing diffuse involvement, which also affect trunk and mucous membranes of the patient. Although the exact pathophysiological mechanisms underlying Bier spots still need to be elucidated, Bier spots have been suggested to be a vascular anomaly caused by vasoconstriction of small vessels. In addition, several diseases have been proposed to be associated with Bier spots, including scleroderma renal crisis, cryoglobulinemia, Peutz-Jeghers syndrome, alopecia areata and hypoplasia of the aorta, although it has not been shown whether these associations are casual or coincidental. The clinical presentation of Bier spots is quite typical. These tiny whitish macules easily become prominent when the affected limb is placed in a dependent position and fade away when the limb is raised. Here we report a case of Bier spots in a 32-year-old male patient with characteristical clinical manifestations.

  15. A comparative study of x-ray emission from laser spots in laser-heated hohlraums relative to spots on simple disk targets

    International Nuclear Information System (INIS)

    Ze, F.; Langer, S.H.; Kauffman, R.L.; Kilkenny, J.D.; Landen, O.; Ress, D.; Rosen, M.D.; Suter, L.J.; Wallace, R.J.; Wiedwald, J.D.

    1997-01-01

    In this paper we report the results of experiments that compare the x-ray emission from a laser spot in a radiation-filled hohlraum to that from a similar laser spot on a simple disk target. The studies were done using the Nova laser facility [J. D. Lindl, Phys. Plasmas 2, 3933 (1995)] in its 0.35 μm wavelength, 1 ns square pulse configuration. Focal spot intensities were 2 endash 3.5x10 15 W/cm 2 . X-ray images measured x-ray conversion in a hohlraum and from an isolated disk simultaneously. A laser spot inside a hohlraum emitted more x rays, after subtracting the background emission from the hohlraum walls, than a spot on a disk. Numerical models suggest the enhanced spot emission inside the hohlraum is due to an increase in lateral transport relative to the disk. Filamentation in the hohlraum will also increase the spot size. The models agree fairly well with the results on spot spreading but do not explain the overall increase in conversion efficiency. copyright 1997 American Institute of Physics

  16. Age Spots

    Science.gov (United States)

    ... for Every Season How to Choose the Best Skin Care Products In This Section Dermatologic Surgery What is dermatologic ... for Every Season How to Choose the Best Skin Care Products Age Spots Treatment Options Learn more about treatment ...

  17. Spotted inflation

    International Nuclear Information System (INIS)

    Matsuda, Tomohiro

    2010-01-01

    We describe new scenarios for generating curvature perturbations when inflaton (curvaton) has significant interactions. We consider a ''spot'', which arises from interactions associated with an enhanced symmetric point (ESP) on the trajectory. Our first example uses the spot to induce a gap in the field equation. We observe that the gap in the field equation may cause generation of curvature perturbation if it does not appear simultaneous in space. The mechanism is similar to the scenario of inhomogeneous phase transition. Then we observe that the spot interactions may initiate warm inflation in the cold Universe. Creation of cosmological perturbation is discussed in relation to the inflaton dynamics and the modulation associated with the spot interactions

  18. Multiple quasi-monoenergetic electron beams from laser-wakefield acceleration with spatially structured laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Y.; Li, M. H.; Li, Y. F.; Wang, J. G.; Tao, M. Z.; Han, Y. J.; Zhao, J. R.; Huang, K.; Yan, W. C.; Ma, J. L.; Li, Y. T. [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Chen, L. M., E-mail: lmchen@iphy.ac.cn [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, D. Z. [Institute of High Energy Physics, CAS, Beijing 100049 (China); Chen, Z. Y. [Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621999 (China); Sheng, Z. M. [Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Department of Physics, Scottish Universities Physics Alliance, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Zhang, J. [Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2015-08-15

    By adjusting the focus geometry of a spatially structured laser pulse, single, double, and treble quasi-monoenergetic electron beams were generated, respectively, in laser-wakefield acceleration. Single electron beam was produced as focusing the laser pulse to a single spot. While focusing the laser pulse to two spots that are approximately equal in energy and size and intense enough to form their own filaments, two electron beams were produced. Moreover, with a proper distance between those two focal spots, three electron beams emerged with a certain probability owing to the superposition of the diffractions of those two spots. The energy spectra of the multiple electron beams are quasi-monoenergetic, which are different from that of the large energy spread beams produced due to the longitudinal multiple-injection in the single bubble.

  19. Combined effect of pulse density and grid cell size on predicting and mapping aboveground carbon in fast-growing Eucalyptus forest plantation using airborne LiDAR data.

    Science.gov (United States)

    Silva, Carlos Alberto; Hudak, Andrew Thomas; Klauberg, Carine; Vierling, Lee Alexandre; Gonzalez-Benecke, Carlos; de Padua Chaves Carvalho, Samuel; Rodriguez, Luiz Carlos Estraviz; Cardil, Adrián

    2017-12-01

    LiDAR remote sensing is a rapidly evolving technology for quantifying a variety of forest attributes, including aboveground carbon (AGC). Pulse density influences the acquisition cost of LiDAR, and grid cell size influences AGC prediction using plot-based methods; however, little work has evaluated the effects of LiDAR pulse density and cell size for predicting and mapping AGC in fast-growing Eucalyptus forest plantations. The aim of this study was to evaluate the effect of LiDAR pulse density and grid cell size on AGC prediction accuracy at plot and stand-levels using airborne LiDAR and field data. We used the Random Forest (RF) machine learning algorithm to model AGC using LiDAR-derived metrics from LiDAR collections of 5 and 10 pulses m -2 (RF5 and RF10) and grid cell sizes of 5, 10, 15 and 20 m. The results show that LiDAR pulse density of 5 pulses m -2 provides metrics with similar prediction accuracy for AGC as when using a dataset with 10 pulses m -2 in these fast-growing plantations. Relative root mean square errors (RMSEs) for the RF5 and RF10 were 6.14 and 6.01%, respectively. Equivalence tests showed that the predicted AGC from the training and validation models were equivalent to the observed AGC measurements. The grid cell sizes for mapping ranging from 5 to 20 also did not significantly affect the prediction accuracy of AGC at stand level in this system. LiDAR measurements can be used to predict and map AGC across variable-age Eucalyptus plantations with adequate levels of precision and accuracy using 5 pulses m -2 and a grid cell size of 5 m. The promising results for AGC modeling in this study will allow for greater confidence in comparing AGC estimates with varying LiDAR sampling densities for Eucalyptus plantations and assist in decision making towards more cost effective and efficient forest inventory.

  20. SPOT Program

    Science.gov (United States)

    Smith, Jason T.; Welsh, Sam J.; Farinetti, Antonio L.; Wegner, Tim; Blakeslee, James; Deboeck, Toni F.; Dyer, Daniel; Corley, Bryan M.; Ollivierre, Jarmaine; Kramer, Leonard; hide

    2010-01-01

    A Spacecraft Position Optimal Tracking (SPOT) program was developed to process Global Positioning System (GPS) data, sent via telemetry from a spacecraft, to generate accurate navigation estimates of the vehicle position and velocity (state vector) using a Kalman filter. This program uses the GPS onboard receiver measurements to sequentially calculate the vehicle state vectors and provide this information to ground flight controllers. It is the first real-time ground-based shuttle navigation application using onboard sensors. The program is compact, portable, self-contained, and can run on a variety of UNIX or Linux computers. The program has a modular objec-toriented design that supports application-specific plugins such as data corruption remediation pre-processing and remote graphics display. The Kalman filter is extensible to additional sensor types or force models. The Kalman filter design is also strong against data dropouts because it uses physical models from state and covariance propagation in the absence of data. The design of this program separates the functionalities of SPOT into six different executable processes. This allows for the individual processes to be connected in an a la carte manner, making the feature set and executable complexity of SPOT adaptable to the needs of the user. Also, these processes need not be executed on the same workstation. This allows for communications between SPOT processes executing on the same Local Area Network (LAN). Thus, SPOT can be executed in a distributed sense with the capability for a team of flight controllers to efficiently share the same trajectory information currently being computed by the program. SPOT is used in the Mission Control Center (MCC) for Space Shuttle Program (SSP) and International Space Station Program (ISSP) operations, and can also be used as a post -flight analysis tool. It is primarily used for situational awareness, and for contingency situations.

  1. Light electric transformer to transform the size of particles contained in a gas flow into electrical pulses

    Energy Technology Data Exchange (ETDEWEB)

    Berber, V.A.; Zolotenko, V.A.; Naguev, E.N.; Pavlov, V.V.; Sokolov, V.E.; Syromyatnikov, A.N.; Eremenko, A.I.

    1979-08-09

    The equipment measures the air dust. The aerosol flow is hence irradiated with a convergent light bundle. Using mirrors and mechanically operable screens, it is possible to divert part of the light onto a photo receiver to produce electric pulses of the dispersly composed aerosols and another part onto a former for standardized light pulses. The accuracy of the measurement is increased by the stability of the standardized light pulses.

  2. Electron acceleration by a self-diverging intense laser pulse

    International Nuclear Information System (INIS)

    Singh, K.P.; Gupta, D.N.; Tripathi, V.K.; Gupta, V.L.

    2004-01-01

    Electron acceleration by a laser pulse having a Gaussian radial and temporal profile of intensity has been studied. The interaction region is vacuum followed by a gas. The starting point of the gas region has been chosen around the point at which the peak of the pulse interacts with the electron. The tunnel ionization of the gas causes a defocusing of the laser pulse and the electron experiences the action of a ponderomotive deceleration at the trailing part of the pulse with a lower intensity rather than an acceleration at the rising part of the laser pulse with a high intensity, and thus gains net energy. The initial density of the neutral gas atoms should be high enough to properly defocus the pulse; otherwise the electron experiences some deceleration during the trailing part of the pulse and the net energy gain is reduced. The rate of tunnel ionization increases with the increase in the laser intensity and the initial density of neutral gas atoms, and with the decreases in the laser spot size, which causes more defocusing of the laser pulse. The required initial density of neutral gas atoms decreases with the increase in the laser intensity and also with the decrease in the laser spot size

  3. Indel-II region deletion sizes in the white spot syndrome virus genome correlate with shrimp disease outbreaks in southern Vietnam

    NARCIS (Netherlands)

    Tran Thi Tuyet, H.; Zwart, M.P.; Phuong, N.T.; Oanh, D.T.H.; Jong, de M.C.M.; Vlak, J.M.

    2012-01-01

    Sequence comparisons of the genomes of white spot syndrome virus (WSSV) strains have identified regions containing variable-length insertions/deletions (i.e. indels). Indel-I and Indel-II, positioned between open reading frames (ORFs) 14/15 and 23/24, respectively, are the largest and the most

  4. Large spot transpupillary thermotherapy: a quicker laser for treatment of high risk prethreshold retinopathy of prematurity - a randomized study.

    Science.gov (United States)

    Shah, Parag K; Narendran, V; Kalpana, N

    2011-01-01

    To compare structural and functional outcome and time efficiency between standard spot sized conventional pulsed mode diode laser and continuous mode large spot transpupillary thermotherapy (LS TTT) for treatment of high risk prethreshold retinopathy of prematurity (ROP). Ten eyes of five preterm babies having bilateral symmetrical high risk prethreshold ROP were included in this study. One eye of each baby was randomized to get either standard spot sized conventional pulsed mode diode laser or continuous mode LS TTT. There was no significant difference between structural or functional outcome in either group. The mean time taken for conventional diode laser was 20.07 minutes, while that for LS TTT was 12.3 minutes. LS TTT was 40% more time efficient than the conventional laser. It may be better suited for the very small fragile premature infants as it is quicker than the conventional laser.

  5. Large spot transpupillary thermotherapy: A quicker laser for treatment of high risk prethreshold retinopathy of prematurity - A randomized study

    Directory of Open Access Journals (Sweden)

    Shah Parag

    2011-01-01

    Full Text Available To compare structural and functional outcome and time efficiency between standard spot sized conventional pulsed mode diode laser and continuous mode large spot transpupillary thermotherapy (LS TTT for treatment of high risk prethreshold retinopathy of prematurity (ROP. Ten eyes of five preterm babies having bilateral symmetrical high risk prethreshold ROP were included in this study. One eye of each baby was randomized to get either standard spot sized conventional pulsed mode diode laser or continuous mode LS TTT. There was no significant difference between structural or functional outcome in either group. The mean time taken for conventional diode laser was 20.07 minutes, while that for LS TTT was 12.3 minutes. LS TTT was 40% more time efficient than the conventional laser. It may be better suited for the very small fragile premature infants as it is quicker than the conventional laser.

  6. Generation of a few femtoseconds pulses in seeded FELs using a seed laser with small transverse size

    Energy Technology Data Exchange (ETDEWEB)

    Li, Heting, E-mail: liheting@ustc.edu.cn; Jia, Qika

    2016-09-11

    We propose a simple method to generate a few femtosecond pulses in seeded FELs. We use a longitudinal energy-chirped electron beam passing through a dogleg where transverse dispersion will generate a horizontal energy chirp, then in the modulator, a seed laser with narrow beam radius will only modulate the center portion of the electron beam and then short pulses at high harmonics will be generated in the radiator. Using a representative realistic set of parameters, we show that 30 nm XUV pulse based on the HGHG scheme and 9 nm soft x-ray pulse based on the EEHG scheme with duration of about 8 fs (FWHM) and peak power of GW level can be generated from a 180 nm UV seed laser with beam waist of 75 μm. This new scheme can provide an optional operation mode for the existing seeded FEL facilities to meet the requirement of short-pulse FEL.

  7. Compliance of the normal-sized aorta in adolescents with Marfan syndrome: comparison of MR measurements of aortic distensibility and pulse wave velocity

    International Nuclear Information System (INIS)

    Eichhorn, J.G.; Ruediger, H.J.; Gorenflo, M.; Khalil, M.; Ulmer, H.; Krissak, R.; Kauczor, H.U.; Ley, S.; Universitaetsklinik Heidelberg; Arnold, R.; Universitaetskinderklinik Freiburg; Boese, J.; Siemens AG, Medical Solutions, Forchheim; Krug, R.; Fink, C.

    2007-01-01

    Purpose: To compare the aortic compliance of the normal-sized aorta of adolescents with Marfan syndrome and healthy controls using MR measurements of the aortic distensibility and pulse wave velocity. Materials and Methods: Fourteen patients (median age: 15 [9-21] years) and 11 healthy subjects (23 [12-32] years) were examined at 1.5 T. The MR protocol included 2D steady-state free precession (SSFP)-CINE MRI of the aortic distensibility and PC-MRI of the pulse wave velocity. All measurements were positioned perpendicular to the descending aorta at the level of the diaphragm for assessing the changes in the aortic cross-sectional areas and additionally above and below this plane for assessing the pulse wave velocity. In addition contrast-enhanced 3D-MR angiography was performed in adolescents with Marfan syndrome to exclude morphologic changes and to prove normal-sized aorta. Results: Compared with control subjects, adolescents with Marfan syndrome had significantly decreased distensibility and significantly increased pulse wave velocity (χ 2 -test, p = 0.0002) using an age-related non-linear regression analysis. The related aortic compliance was significantly decreased (χ 2 -test, p = 0.0002). There was a good correlation between the two methods (r = 0.86). A low intraobserver variability was found for both methods (≤ 2 %). (orig.)

  8. The System of Nanosecond 280-keV-Hesize="-1">+ Pulsed Beam

    CERN Document Server

    Junphong, Pimporn; Lekprasert, Banyat; Suwannakachorn, Dusadee; Thongnopparat, N; Vilaithong, Thiraphat; Wiedemann, Helmut

    2005-01-01

    At Fast Neutron Research Facility,the 150 kV-pulseds neutron generator is being upgraded to produce a 280-keV-pulsed-He beam for time-of-flight Rutherford backscattering spectrometry. It involves replacing the existing beam line elements by a multicusp ion source, a 400-kV accelerating tube, 45o-double focusing dipole magnet and quadrupole lens. The Multicusp ion source is a compact filament-driven of 2.6 cm in diameter and 8 cm in length. The current extracted is 20.4 μA with 13 kV of extraction voltage and 8.8 kV of Einzel lens voltage. The beam emittance has been found to vary between 6-12 mm mrad. The beam transport system has to be redesigned based on the new elements. The important part of a good pulsed beam depends on the pulsing system. The two main parts are the chopper and buncher. An optimized geometry for the 280 keV pulsed helium ion beam will be presented and discussed. The PARMELA code has been used to optimize the space charge effect, resulting in pulse width of less than 2 ns at a t...

  9. Size properties of colloidal nanoparticles produced by nanosecond pulsed laser ablation and studying the effects of liquid medium and laser fluence

    International Nuclear Information System (INIS)

    Mahdieh, Mohammad Hossein; Fattahi, Behzad

    2015-01-01

    Highlights: • Colloidal aluminum- and titanium-based nanoparticles fabricated by laser ablation. • Various liquid environments and laser fluences were applied as variable parameters. • Physical characteristics of liquid medium influence ablation process and nanoparticle formation. • Size properties of prepared nanoparticles depend on liquid medium and laser fluence. • Ablation of both metals in ethanol results in nanoparticles with smaller size. - Abstract: In this paper, pulsed laser ablation method was used for synthesis of colloidal nanoparticles of aluminum and titanium targets in distilled water, ethanol, and acetone as liquid environments. Ultraviolet–visible (UV–vis) absorption spectrophotometer and scanning electron microscope (SEM) were used for characterization of produced nanoparticles. Using image processing technique and analyzing the SEM images, nanoparticles’ mean size and size distribution were achieved. The results show that liquid medium has strong effect on size properties of produced nanoparticles. From the results, it was found that ablation of both metal targets in ethanol medium leads to formation of smaller size nanoparticles with narrower size distributions. The influence of laser fluence was also investigated. According to the results, higher laser fluence produces larger mean size nanoparticles with broader size distribution

  10. Size properties of colloidal nanoparticles produced by nanosecond pulsed laser ablation and studying the effects of liquid medium and laser fluence

    Energy Technology Data Exchange (ETDEWEB)

    Mahdieh, Mohammad Hossein, E-mail: mahdm@iust.ac.ir; Fattahi, Behzad

    2015-02-28

    Highlights: • Colloidal aluminum- and titanium-based nanoparticles fabricated by laser ablation. • Various liquid environments and laser fluences were applied as variable parameters. • Physical characteristics of liquid medium influence ablation process and nanoparticle formation. • Size properties of prepared nanoparticles depend on liquid medium and laser fluence. • Ablation of both metals in ethanol results in nanoparticles with smaller size. - Abstract: In this paper, pulsed laser ablation method was used for synthesis of colloidal nanoparticles of aluminum and titanium targets in distilled water, ethanol, and acetone as liquid environments. Ultraviolet–visible (UV–vis) absorption spectrophotometer and scanning electron microscope (SEM) were used for characterization of produced nanoparticles. Using image processing technique and analyzing the SEM images, nanoparticles’ mean size and size distribution were achieved. The results show that liquid medium has strong effect on size properties of produced nanoparticles. From the results, it was found that ablation of both metal targets in ethanol medium leads to formation of smaller size nanoparticles with narrower size distributions. The influence of laser fluence was also investigated. According to the results, higher laser fluence produces larger mean size nanoparticles with broader size distribution.

  11. Development and application of resistive pulse spectroscopy: studies on the size, form and deformability of red blood cells

    Energy Technology Data Exchange (ETDEWEB)

    Yee, J.P.

    1979-01-01

    The following studies were conducted using the resistive pulse spectroscopy (RPS) technique: cumulative spectra and individual pulse forms for rigid latex polymer spheres; acquisition and analysis of RPS spectral data by means of special computer program; interaction of red blood cells with glutaraldehyde; membrane properties of erythrocytes undergoing abrupt osmotic hemolysis; reversible effects of the binding of chlorpromazine HCl at the red cell membrane surface; effects of high cholesterol diet on erythrocytes of guinea pigs; and multi-population analysis for a mixture of fetal and maternal red cells. (HLW)

  12. Operating range, hold-up, droplet size and axial mixing of pulsed plate columns in highly disperse and low-continuity volume flows

    International Nuclear Information System (INIS)

    Schmidt, H.; Miller, H.

    Operating behavior, hold-up, droplet size and axial mixing are investigated in highly disperse and slightly continuous volume flows in a pulsed plate column. The geometry of the column of 4-m length and 10-cm inside diameter was held constant. The hole shape of the column bases was changed, wherby the cylindrical, sharp-edge drilled hole is compared with the punched, nozzle-shaped hole in their effects on the fluid-dynamic behavior. In this case we varied the volume flows, the ratio of volume flows, the pulse frequency and the operating temperature. The operation was held constant for the aqueous, the organic, the continuous and the disperse phases. The objective was to demonstrate the applicability of pulsed plate columns with very large differences between the organic disperse and the aqueous continuous volume flow, to obtain design data for such columns and to perform a scale-up to industrial reprocessing plant-size. 18 references, 11 figures, 3 tables

  13. Adjuvant intensity-modulated proton therapy in malignant pleural mesothelioma. A comparison with intensity-modulated radiotherapy and a spot size variation assessment

    Energy Technology Data Exchange (ETDEWEB)

    Lorentini, S. [Agenzia Provinciale per la Protonterapia (ATreP), Trento (Italy); Padova Univ. (Italy). Medical Physics School; Amichetti, M.; Fellin, F.; Schwarz, M. [Agenzia Provinciale per la Protonterapia (ATreP), Trento (Italy); Spiazzi, L. [Brescia Hospital (Italy). Medical Physics Dept.; Tonoli, S.; Magrini, S.M. [Brescia Hospital (Italy). Radiation Oncology Dept.

    2012-03-15

    Intensity-modulated radiation therapy (IMRT) is the state-of-the-art treatment for patients with malignant pleural mesothelioma (MPM). The goal of this work was to assess whether intensity-modulated proton therapy (IMPT) could further improve the dosimetric results allowed by IMRT. We re-planned 7 MPM cases using both photons and protons, by carrying out IMRT and IMPT plans. For both techniques, conventional dose comparisons and normal tissue complication probability (NTCP) analysis were performed. In 3 cases, additional IMPT plans were generated with different beam dimensions. IMPT allowed a slight improvement in target coverage and clear advantages in dose conformity (p < 0.001) and dose homogeneity (p = 0.01). Better organ at risk (OAR) sparing was obtained with IMPT, in particular for the liver (D{sub mean} reduction of 9.5 Gy, p = 0.001) and ipsilateral kidney (V{sub 20} reduction of 58%, p = 0.001), together with a very large reduction of mean dose for the contralateral lung (0.2 Gy vs 6.1 Gy, p = 0.0001). NTCP values for the liver showed a systematic superiority of IMPT with respect to IMRT for both the esophagus (average NTCP 14% vs. 30.5%) and the ipsilateral kidney (p = 0.001). Concerning plans obtained with different spot dimensions, a slight loss of target coverage was observed along with sigma increase, while maintaining OAR irradiation always under planning constraints. Results suggest that IMPT allows better OAR sparing with respect to IMRT, mainly for the liver, ipsilateral kidney, and contralateral lung. The use of a spot dimension larger than 3 x 3 mm (up to 9 x 9 mm) does not compromise dosimetric results and allows a shorter delivery time.

  14. Insights from ecological niche modeling on the taxonomic distinction and niche differentiation between the black-spotted and red-spotted tokay geckoes (Gekko gecko)

    OpenAIRE

    Zhang, Yueyun; Chen, Chongtao; Li, Li; Zhao, Chengjian; Chen, Weicai; Huang, Yong

    2014-01-01

    The black-spotted tokay and the red-spotted tokay are morphologically distinct and have largely allopatric distributions. The black-spotted tokay is characterized by a small body size and dark skin with sundry spots, while the red-spotted tokay has a relatively large body size and red spots. Based on morphological, karyotypic, genetic, and distribution differences, recent studies suggested their species status; however, their classifications remain controversial, and additional data such as e...

  15. Rocky Mountain spotted fever

    Science.gov (United States)

    ... spotted fever on the foot Rocky Mountain spotted fever, petechial rash Antibodies Deer and dog tick References McElligott SC, Kihiczak GG, Schwartz RA. Rocky Mountain spotted fever and other rickettsial infections. In: Lebwohl MG, Heymann ...

  16. Compressing and focusing a short laser pulse by a thin plasma lens

    International Nuclear Information System (INIS)

    Ren, C.; Duda, B. J.; Hemker, R. G.; Mori, W. B.; Katsouleas, T.; Antonsen, T. M.; Mora, P.

    2001-01-01

    We consider the possibility of using a thin plasma slab as an optical element to both focus and compress an intense laser pulse. By thin we mean that the focal length is larger than the lens thickness. We derive analytic formulas for the spot size and pulse length evolution of a short laser pulse propagating through a thin uniform plasma lens. The formulas are compared to simulation results from two types of particle-in-cell code. The simulations give a greater final spot size and a shorter focal length than the analytic formulas. The difference arises from spherical aberrations in the lens which lead to the generation of higher-order vacuum Gaussian modes. The simulations also show that Raman side scattering can develop. A thin lens experiment could provide unequivocal evidence of relativistic self-focusing

  17. A comparative study of pulsed dye laser versus long pulsed Nd:YAG laser treatment in recalcitrant viral warts.

    Science.gov (United States)

    Shin, Yo Sup; Cho, Eun Byul; Park, Eun Joo; Kim, Kwang Ho; Kim, Kwang Joong

    2017-08-01

    Viral warts are common infectious skin disease induced by human papillomavirus (HPV). But the treatment of recalcitrant warts is still challenging. In this study, we compared the effectiveness of pulsed dye laser (PDL) and long pulsed Nd:YAG (LPNY) laser in the treatment of recalcitrant viral warts. We retrospectively analyzed the medical records of patients with recalcitrant warts treated with laser therapy between January 2013 and February 2016. Seventy-two patients with recalcitrant warts were evaluated. Thirty-nine patients were treated with pulsed dye laser and thirty-three patients were treated with LPNY laser. The following parameters were used: PDL (spot size, 7 mm; pulse duration, 1.5 ms; and fluence, 10-14 J/cm 2 ) and LPNY (spot size, 5 mm; pulse duration, 20 ms; and fluence, 240-300 J/cm 2 ). Complete clearance of two patients (5.1%) in PDL group, and three patients (9.1%) in LPNY group were observed without significant side effects. The patients who achieved at least 50% improvement from baseline were 20 (51.3%) in PDL and 22 (66.7%) in LPNY, respectively. This research is meaningful because we compared the effectiveness of the PDL and LPNY in the recalcitrant warts. Both PDL and LPNY laser could be used as a safe and alternative treatment for recalcitrant warts.

  18. Simulation analysis of impulse characteristics of space debris irradiated by multi-pulse laser

    Science.gov (United States)

    Lin, Zhengguo; Jin, Xing; Chang, Hao; You, Xiangyu

    2018-02-01

    Cleaning space debris with laser is a hot topic in the field of space security research. Impulse characteristics are the basis of cleaning space debris with laser. In order to study the impulse characteristics of rotating irregular space debris irradiated by multi-pulse laser, the impulse calculation method of rotating space debris irradiated by multi-pulse laser is established based on the area matrix method. The calculation method of impulse and impulsive moment under multi-pulse irradiation is given. The calculation process of total impulse under multi-pulse irradiation is analyzed. With a typical non-planar space debris (cube) as example, the impulse characteristics of space debris irradiated by multi-pulse laser are simulated and analyzed. The effects of initial angular velocity, spot size and pulse frequency on impulse characteristics are investigated.

  19. Apparatus for real-time size and speed measurements of blow-off particles from pulsed irradiation experiments

    International Nuclear Information System (INIS)

    Von Benken, C.; Johnson, E.A.; Nordberg, M.

    1989-01-01

    The authors present an apparatus capable of detecting micron sized particles traveling at speeds up to 10 6 cm/sec. The apparatus uses light scattering methods with automated data processing. Data generated by this apparatus should be extremely useful in radiation damage studies of components in contamination sensitive optical systems

  20. On red-shift of UV photoluminescence with decreasing size of silicon nanoparticles embedded in SiO2 matrix grown by pulsed laser deposition

    International Nuclear Information System (INIS)

    Chaturvedi, Amita; Joshi, M.P.; Rani, Ekta; Ingale, Alka; Srivastava, A.K.; Kukreja, L.M.

    2014-01-01

    Ensembles of silicon nanoparticles (Si-nps) embedded in SiO 2 matrix were grown by alternate ablation of Si and SiO 2 targets using KrF excimer laser based pulsed laser deposition (PLD). The sizes of Si-nps (mean size ranging from 1–5 nm) were controlled by varying the ablation time of silicon target. Transmission electron microscopy (TEM) along with selected area electron diffraction (SAED) and Raman spectroscopy were used to confirm the growth of silicon nanoparticles, its size variation with growth time and the crystalline quality of the grown nanoparticles. TEM analysis showed that mean size and size distribution of Si-nps increased with increase in the ablation time of Si target. Intense peaks ∼521 cm −1 in Raman analysis showed reasonably good crystalline quality of grown Si-nps. We observed asymmetric broadening of phonon line shapes which also redshift with decreasing size of Si-nps. Photoluminescence (PL) from these samples, obtained at room temperature, was broad band and consisted of three bands in UV and visible range. The intensity of PL band in UV spectral range (peak ∼3.2 eV) was strong compared to visible range bands (peaks ∼2.95 eV and ∼2.55 eV). We observed a small red-shift (∼0.07 eV) of peak position of UV range PL with the decrease in the mean sizes of Si-nps, while there was no appreciable size dependent shift of PL peak positions for other bands in the visible range. The width of UV PL band was also found to increase with decrease of Si-nps mean sizes. Based on the above observations of size dependent redshift of UV range PL band together with the PL lifetimes and PL excitation spectroscopy, the origin of UV PL band is attributed to the direct band transition at the Γ point of Si band structure. Visible range bands were ascribed as defect related transitions. The weak intensities of PL bands ∼2.95 eV and ∼2.55 eV suggested that Si nanoparticles grown by PLD were efficiently capped or passivated by SiO 2 with low density of

  1. Variable-spot ion beam figuring

    International Nuclear Information System (INIS)

    Wu, Lixiang; Qiu, Keqiang; Fu, Shaojun

    2016-01-01

    This paper introduces a new scheme of ion beam figuring (IBF), or rather variable-spot IBF, which is conducted at a constant scanning velocity with variable-spot ion beam collimated by a variable diaphragm. It aims at improving the reachability and adaptation of the figuring process within the limits of machine dynamics by varying the ion beam spot size instead of the scanning velocity. In contrast to the dwell time algorithm in the conventional IBF, the variable-spot IBF adopts a new algorithm, which consists of the scan path programming and the trajectory optimization using pattern search. In this algorithm, instead of the dwell time, a new concept, integral etching time, is proposed to interpret the process of variable-spot IBF. We conducted simulations to verify its feasibility and practicality. The simulation results indicate the variable-spot IBF is a promising alternative to the conventional approach.

  2. Effects of Thickness, Pulse Duration, and Size of Strip Electrode on Ferroelectric Electron Emission of Lead Zirconate Titanate Films

    Science.gov (United States)

    Yaseen, Muhammad; Ren, Wei; Chen, Xiaofeng; Feng, Yujun; Shi, Peng; Wu, Xiaoqing

    2018-02-01

    Sol-gel-derived lead zirconate titanate (PZT) thin-film emitters with thickness up to 9.8 μm have been prepared on Pt/TiO2/SiO2/Si wafer via chemical solution deposition with/without polyvinylpyrrolidone (PVP) modification, and the relationship between the film thickness and electron emission investigated. Notable electron emission was observed on application of a trigger voltage of 120 V for PZT film with thickness of 1.1 μm. Increasing the film thickness decreased the threshold field to initiate electron emission for non-PVP-modified films. In contrast, the electron emission behavior of PVP-modified films did not show significant dependence on film thickness, probably due to their porous structure. The emission current increased with decreasing strip width and space between strips. Furthermore, it was observed that increasing the duration of the applied pulse increased the magnitude of the emission current. The stray field on the PZT film thickness was also calculated and found to increase with increasing ferroelectric sample thickness. The PZT emitters were found to be fatigue free up to 105 emission cycles. Saturated emission current of around 25 mA to 30 mA was achieved for the electrode pattern used in this work.

  3. Greater vertical spot spacing to improve femtosecond laser capsulotomy quality.

    Science.gov (United States)

    Schultz, Tim; Joachim, Stephanie C; Noristani, Rozina; Scott, Wendell; Dick, H Burkhard

    2017-03-01

    To evaluate the effect of adapted capsulotomy laser settings on the cutting quality in femtosecond laser-assisted cataract surgery. Ruhr-University Eye Clinic, Bochum, Germany. Prospective randomized case series. Eyes were treated with 1 of 2 laser settings. In Group 1, the regular standard settings were used (incisional depth 600 μm, pulse energy 4 μJ, horizontal spot spacing 5 μm, vertical spot spacing 10 μm, treatment time 1.2 seconds). In Group 2, vertical spot spacing was increased to 15 μm and the treatment time was 1.0 seconds. Light microscopy was used to evaluate the cut quality of the capsule edge. The size and number of tags (misplaced laser spots, which form a second cut of the capsule with high tear risk) were evaluated in a blinded manner. Groups were compared using the Mann-Whitney U test. The study comprised 100 eyes (50 eyes in each group). Cataract surgery was successfully completed in all eyes, and no anterior capsule tear occurred during the treatment. Histologically, significant fewer tags were observed with the new capsulotomy laser setting. The mean score for the number and size of free tags was significantly lower in this group than with the standard settings (P laser settings improved cut quality and reduced the number of tags. The modification has the potential to reduce the risk for radial capsule tears in femtosecond laser-assisted cataract surgery. With the new settings, no tags and no capsule tears were observed under the operating microscope in any eye. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  4. Damage performance of TiO2/SiO2 thin film components induced by a long-pulsed laser

    International Nuclear Information System (INIS)

    Wang Bin; Dai Gang; Zhang Hongchao; Ni Xiaowu; Shen Zhonghua; Lu Jian

    2011-01-01

    In order to study the long-pulsed laser induced damage performance of optical thin films, damage experiments of TiO 2 /SiO 2 films irradiated by a laser with 1 ms pulse duration and 1064 nm wavelength are performed. In the experiments, the damage threshold of the thin films is measured. The damages are observed to occur in isolated spots, which enlighten the inducement of the defects and impurities originated in the films. The threshold goes down when the laser spot size decreases. But there exists a minimum threshold, which cannot be further reduced by decreasing the laser spot size. Optical microscopy reveals a cone-shaped cavity in the film substrate. Changes of the damaged sizes in film components with laser fluence are also investigated. The results show that the damage efficiency increases with the laser fluence before the shielding effects start to act.

  5. SpotADAPT

    DEFF Research Database (Denmark)

    Kaulakiene, Dalia; Thomsen, Christian; Pedersen, Torben Bach

    2015-01-01

    by Amazon Web Services (AWS). The users aiming for the spot market are presented with many instance types placed in multiple datacenters in the world, and thus it is difficult to choose the optimal deployment. In this paper, we propose the framework SpotADAPT (Spot-Aware (re-)Deployment of Analytical...... of typical analytical workloads and real spot price traces. SpotADAPT's suggested deployments are comparable to the theoretically optimal ones, and in particular, it shows good cost benefits for the budget optimization -- on average SpotADAPT is at most 0.3% more expensive than the theoretically optimal...

  6. Laser based spot weld characterization

    Science.gov (United States)

    Jonietz, Florian; Myrach, Philipp; Rethmeier, Michael; Suwala, Hubert; Ziegler, Mathias

    2016-02-01

    Spot welding is one of the most important joining technologies, especially in the automotive industry. Hitherto, the quality of spot welded joints is tested mainly by random destructive tests. A nondestructive testing technique offers the benefit of cost reduction of the testing procedure and optimization of the fabrication process, because every joint could be examined. This would lead to a reduced number of spot welded joints, as redundancies could be avoided. In the procedure described here, the spot welded joint between two zinc-coated steel sheets (HX340LAD+Z100MB or HC340LA+ZE 50/50) is heated optically on one side. Laser radiation and flash light are used as heat sources. The melted zone, the so called "weld nugget" provides the mechanical stability of the connection, but also constitutes a thermal bridge between the sheets. Due to the better thermal contact, the spot welded joint reveals a thermal behavior different from the surrounding material, where the heat transfer between the two sheets is much lower. The difference in the transient thermal behavior is measured with time resolved thermography. Hence, the size of the thermal contact between the two sheets is determined, which is directly correlated to the size of the weld nugget, indicating the quality of the spot weld. The method performs well in transmission with laser radiation and flash light. With laser radiation, it works even in reflection geometry, thus offering the possibility of testing with just one-sided accessibility. By using heating with collimated laser radiation, not only contact-free, but also remote testing is feasible. A further convenience compared to similar thermographic approaches is the applicability on bare steel sheets without any optical coating for emissivity correction. For this purpose, a proper way of emissivity correction was established.

  7. Photoemission using femtosecond laser pulses

    International Nuclear Information System (INIS)

    Srinivasan-Rao, T.; Tsang, T.; Fischer, J.

    1991-10-01

    Successful operation of short wavelength FEL requires an electron bunch of current >100 A and normalized emittance < 1 mm-mrad. Recent experiments show that RF guns with photocathodes as the electron source may be the ideal candidate for achieving these parameters. To reduce the emittance growth due to space charge and RF dynamics effects, the gun may have to operate at high field gradient (hence at high RF frequency) and a spot size small compared to the aperture. This may necessitate the laser pulse duration to be in the subpicosecond regime to reduce the energy spread. We will present the behavior of metal photocathodes upon irradiation with femtosecond laser beams, comparison of linear and nonlinear photoemission, and scalability to high currents. Theoretical estimate of the intrinsic emittance at the photocathode in the presence of the anomalous heating of the electrons, and the tolerance on the surface roughness of the cathode material will be discussed

  8. Rocky Mountain Spotted Fever

    Science.gov (United States)

    ... with facebook share with twitter share with linkedin Rocky Mountain Spotted Fever Credit: CDC A male cayenne tick, Amblyomma cajennense, ... and New Mexico. Why Is the Study of Rocky Mountain Spotted Fever a Priority for NIAID? Tickborne diseases are becoming ...

  9. Relationship between the Ca/P ratio of hydroxyapatite thin films and the spatial energy distribution of the ablation laser in pulsed laser deposition

    NARCIS (Netherlands)

    Nishikawa, H.; Hasegawa, T; Miyake, A.; Tashiro, Y.; Hashimoto, Y.; Blank, David H.A.; Rijnders, Augustinus J.H.M.

    2016-01-01

    Variation of the Ca/P ratio in hydroxyapatite (Ca10(PO4)6(OH)2) thin films was studied in relation to the spot size of the ablation laser for two different spatial energy distributions in pulsed laser deposition. One energy distribution is the defocus method with a raw distribution and the other is

  10. Formation of various types of nanostructures on germanium surface by nanosecond laser pulses

    Science.gov (United States)

    Mikolutskiy, S. I.; Khasaya, R. R.; Khomich, Yu V.; Yamshchikov, V. A.

    2018-03-01

    The paper describes the formation of micro- and nanostructures in different parts of irradiation zone on germanium surface by multiple action of nanosecond pulses of ArF-laser. It proposes a simple method using only one laser beam without any optional devices and masks for surface treatment. Hexa- and pentagonal cells with submicron dimensions along the surface were observed in peripheral zone of irradiation spot by atomic-force microscopy. Nanostructures in the form of bulbs with rounded peaks with lateral sizes of 40-120 nm were obtained in peripheral low-intensity region of the laser spot. Considering experimental data on material processing by nanosecond laser pulses, a classification of five main types of surface reliefs formed by nanosecond laser pulses with energy density near or slightly above ablation threshold was proposed.

  11. Practical issues of retrieving isolated attosecond pulses

    International Nuclear Information System (INIS)

    Wang He; Chini, Michael; Khan, Sabih D; Chen, Shouyuan; Gilbertson, Steve; Feng Ximao; Mashiko, Hiroki; Chang Zenghu

    2009-01-01

    The attosecond streaking technique is used for the characterization of isolated extreme ultraviolet (XUV) attosecond pulses. This type of measurement suffers from low photoelectron counts in the streaked spectrogram, and is thus susceptible to shot noise. For the retrieval of few- or mono-cycle attosecond pulses, high-intensity streaking laser fields are required, which cause the energy spectrum of above-threshold ionized (ATI) electrons to overlap with that of the streaked photoelectrons. It is found by using the principal component generalized projections algorithm that the XUV attosecond pulse can accurately be retrieved for simulated and experimental spectrograms with a peak value of 50 or more photoelectron counts. Also, the minimum streaking intensity is found to be more than 50 times smaller than that required by the classical streaking camera for retrieval of pulses with a spectral bandwidth supporting 90 as transform-limited pulse durations. Furthermore, spatial variation of the streaking laser intensity, collection angle of streaked electrons and time delay jitter between the XUV pulse and streaking field can degrade the quality of the streaked spectrogram. We find that even when the XUV and streaking laser focal spots are comparable in size, the streaking electrons are collected from a 4π solid angle, or the delay fluctuates by more than the attosecond pulse duration, the attosecond pulses can still be accurately retrieved. In order to explain the insusceptibility of the streaked spectrogram to these factors, the linearity of the streaked spectrogram with respect to the streaking field is derived under the saddle point approximation.

  12. Single-shot and single-spot measurement of laser ablation threshold for carbon nanotubes

    OpenAIRE

    Lednev, Vasily N.; Pershin, Sergey M.; Obraztsova, Elena D.; Kudryashov, Sergey I.; Bunkin, Alexey F.

    2013-01-01

    A simple and convenient procedure for single-shot, single-spot ablation threshold measurement has been developed. It is based on the employment of cylindrical lens to obtain elliptical Gaussian laser spot. The ablated spot chords which are parallel to the minor axis were measured across the spot major axis which is proportional to the fluence cross-section thus providing wide range dependence of damaged spot size versus fluence in one spot measurement. For both conventional and new-developed ...

  13. Disruption effects on the beam size measurement

    International Nuclear Information System (INIS)

    Raimondi, P.; Decker, F.J.; Chen, P.

    1995-01-01

    At the SLC Final Focus with higher currents and smaller beam sizes, the disruption parameter D y is close to one and so the pinch effect should produce a luminosity enhancement. Since a flat beam-beam function is fit to deflection scan data to measure the beam size, disruption can affect the measurement. Here the authors discuss the quantitative effects of disruption for typical SLC beam parameters. With 3.5 10 10 particles per pulse, bunch length of 0.8 mm and beam sizes of 2.1 μm horizontally and 0.55 μm vertically, the measured vertical size can be as much as 25% bigger than the real one. Furthermore during the collision the spot size actually decrease, producing an enhancement factor H D of about 1.25. This would yield to a true luminosity which is 1.6 times that which is estimated from the beam-beam deflection fit

  14. Size-controlled growth of ZnO nanowires by catalyst-free high-pressure pulsed laser deposition and their optical properties

    Directory of Open Access Journals (Sweden)

    W. Z. Liu

    2011-06-01

    Full Text Available Single crystalline ZnO nanowires were fabricated on Si (100 substrates by catalyst-free high-pressure pulsed laser deposition. It is found that the nanowires start to form when the substrate temperature and growth pressure exceed the critical values of 700 oC and 700 Pa, and their size strongly depends on these growth conditions. That is, the aspect ratio of the nanowires decreases with increasing temperature or decreasing pressure. Such a size dependence on growth conditions was discussed in terms of surface migration and scattering of ablated atoms. Room-temperature photoluminescence spectrum of ZnO nanowires shows a dominant near-band-edge emission peak at 3.28 eV and a visible emission band centered at 2.39 eV. Temperature-dependent photoluminescence studies reveal that the former consists of the acceptor-bound exciton and free exciton emissions; while the latter varies in intensity with the aspect ratio of the nanowires and is attributed to the surface-mediated deep level emission.

  15. Multiphoton photoemission from a copper cathode illuminated by ultrashort laser pulses in an RF photoinjector.

    Science.gov (United States)

    Musumeci, P; Cultrera, L; Ferrario, M; Filippetto, D; Gatti, G; Gutierrez, M S; Moody, J T; Moore, N; Rosenzweig, J B; Scoby, C M; Travish, G; Vicario, C

    2010-02-26

    In this Letter we report on the use of ultrashort infrared laser pulses to generate a copious amount of electrons by a copper cathode in an rf photoinjector. The charge yield verifies the generalized Fowler-Dubridge theory for multiphoton photoemission. The emission is verified to be prompt using a two pulse autocorrelation technique. The thermal emittance associated with the excess kinetic energy from the emission process is comparable with the one measured using frequency tripled uv laser pulses. In the high field of the rf gun, up to 50 pC of charge can be extracted from the cathode using a 80 fs long, 2 microJ, 800 nm pulse focused to a 140 mum rms spot size. Taking into account the efficiency of harmonic conversion, illuminating a cathode directly with ir laser pulses can be the most efficient way to employ the available laser power.

  16. Multiphoton Photoemission from a Copper Cathode Illuminated by Ultrashort Laser Pulses in an rf Photoinjector

    International Nuclear Information System (INIS)

    Musumeci, P.; Gutierrez, M. S.; Moody, J. T.; Moore, N.; Rosenzweig, J. B.; Scoby, C. M.; Travish, G.; Cultrera, L.; Ferrario, M.; Filippetto, D.; Gatti, G.; Vicario, C.

    2010-01-01

    In this Letter we report on the use of ultrashort infrared laser pulses to generate a copious amount of electrons by a copper cathode in an rf photoinjector. The charge yield verifies the generalized Fowler-Dubridge theory for multiphoton photoemission. The emission is verified to be prompt using a two pulse autocorrelation technique. The thermal emittance associated with the excess kinetic energy from the emission process is comparable with the one measured using frequency tripled uv laser pulses. In the high field of the rf gun, up to 50 pC of charge can be extracted from the cathode using a 80 fs long, 2 μJ, 800 nm pulse focused to a 140 μm rms spot size. Taking into account the efficiency of harmonic conversion, illuminating a cathode directly with ir laser pulses can be the most efficient way to employ the available laser power.

  17. Glare Spot Phase Doppler Anemometry

    OpenAIRE

    Hespel, Camille; Ren, Kuan Fang; Gréhan, Gérard; Onofri, Fabrice

    2006-01-01

    International audience; The Phase Doppler anemometry has been developed to measure simultaneously the velocity and the size of droplets. The measurement of the refractive index is also necessary since it depends on the temperature and the composition of the particle and its measurement permits both to increase the quality of the diameter measurement and to obtain information on the temperature and/or the composition of the droplets. In this paper, we introduce a Glare Spot Phase Doppler Anemo...

  18. Controlling Laser Spot Size in Outer Space

    Science.gov (United States)

    Bennett, Harold E.

    2005-01-01

    Three documents discuss a method of controlling the diameter of a laser beam projected from Earth to any altitude ranging from low orbit around the Earth to geosynchronous orbit. Such laser beams are under consideration as means of supplying power to orbiting spacecraft at levels of the order of tens of kilowatts apiece. Each such beam would be projected by use of a special purpose telescope having an aperture diameter of 15 m or more. Expanding the laser beam to such a large diameter at low altitude would prevent air breakdown and render the laser beam eyesafe. Typically, the telescope would include an adaptive-optics concave primary mirror and a convex secondary mirror. The laser beam transmitted out to the satellite would remain in the near field on the telescope side of the beam waist, so that the telescope focal point would remain effective in controlling the beam width. By use of positioning stages having submicron resolution and repeatability, the relative positions of the primary and secondary mirrors would be adjusted to change the nominal telescope object and image distances to obtain the desired beam diameter (typically about 6 m) at the altitude of the satellite. The limiting distance D(sub L) at which a constant beam diameter can be maintained is determined by the focal range of the telescope 4 lambda f(sup 2) where lambda is the wavelength and f the f/number of the primary mirror. The shorter the wavelength and the faster the mirror, the longer D(sub L) becomes.

  19. Key technical issues associated with a method of pulse compression. Final technical report

    International Nuclear Information System (INIS)

    Hunter, R.O. Jr.

    1980-06-01

    Key technical issues for angular multiplexing as a method of pulse compression in a 100 KJ KrF laser have been studied. Environmental issues studied include seismic vibrations man-made vibrations, air propagation, turbulence, and thermal gradient-induced density fluctuations. These studies have been incorporated in the design of mirror mounts and an alignment system, both of which are reported. A design study and performance analysis of the final amplifier have been undertaken. The pulse compression optical train has been designed and assessed as to its performance. Individual components are described and analytical relationships between the optical component size, surface quality, damage threshold and final focus properties are derived. The optical train primary aberrations are obtained and a method for aberration minimization is presented. Cost algorithms for the mirrors, mounts, and electrical hardware are integrated into a cost model to determine system costs as a function of pulse length, aperture size, and spot size

  20. Prospective Evaluation of the Safety and Efficacy of a 1060-nm Large Spot Size, Vacuum-Assisted Hair Removal Diode Laser System in Asian/Pacific Fitzpatrick's Skin Types IV-V Patients.

    Science.gov (United States)

    Tahiliani, Sushil T; Tahiliani, Harsh S

    2016-11-01

    Laser-based photoepilation of dark skin types demands a delicate combination of appropriate light wavelengths and spot size to achieve optimal epidermal-to-follicular energy absorption ratios. This prospective study assessed the axillary, arm, thigh, and back hair clearing ef cacy of the LightSheer In nity 1060 nm diode laser in 10 Fitzpatrick skin type IV-V patients. Each area was treated up to ve times, at 4-6-week intervals, after which immediate skin responses and adverse events were recorded. Hair count, color and coarseness were assessed before each treatment session, as well as 1, 3, and 6 months following the last session. Both patients and the treating physician rated the degree of improvement with time, and patients also ranked their satisfaction with the treatment outcome. Percent hair reduction from baseline gradually increased with treatment and peaked at 74.6%, 68.4%, and 65.7% for axillary, arm and thigh regions, respectively, 6 months following the last treatment session. Baseline hair growth patterns precluded effective selection of a representative area for hair counting. Patients satisfaction was consistently higher for axillary hair clearance rates, followed by thigh and arm responses. Throughout the follow-up period, the investigator rated 50-67% of the treated axillae as presenting "good" or "very good" hair clearance, and provided similar ratings for 67% of the treated thigh regions at both the 1 and 6 month follow-up sessions. Immediate responses to treatment were mild to moderate and short-lived and no incidents of brosis or scarring were reported. Taken together, the LightSheer In nity 1060 HS Handpiece provided for an ideal ef cacy-safety balance in treating dark-skinned patients, providing for long-term hair clearance with minimal downtime. J Drugs Dermatol. 2016;15(11):1427-1434.

  1. Finite Element and Experimental Study of Shunting in Resistance Spot Welding

    DEFF Research Database (Denmark)

    Seyyedian Choobi, M.; Nielsen, C. V.; Bay, N.

    2015-01-01

    This research is focused on one of the problems frequently encountered in spot welding in industry. In many applications several spot welds are made close to each other. The spots made after the first spot may become smaller in size due to shunt effect. A numerical and experimental study has been...... conducted to investigate the effect of shunting on nugget size in spot welding of HSLA steel sheets. Different cases with different spacing between weld spots have been examined. The nugget sizes have been measured by metallographic examination and have been compared with 3D finite element simulations...

  2. Nonlinear side effects of fs pulses inside corneal tissue during photodisruption

    Science.gov (United States)

    Heisterkamp, A.; Ripken, T.; Mamom, T.; Drommer, W.; Welling, H.; Ertmer, W.; Lubatschowski, H.

    In order to evaluate the potential for refractive surgery, fs laser pulses of 150-fs pulse duration were used to process corneal tissue of dead and living animal eyes. By focusing the laser radiation down to spot sizes of several microns, very precise cuts could be achieved inside the treated cornea, accompanied with minimum collateral damage to the tissue by thermal or mechanical effects. During histo-pathological analysis by light and transmission electron microscopy considerable side effects of fs photodisruption were found. Due to the high intensities at the focal region several nonlinear effects occurred. Self-focusing, photodissociation, UV-light production were observed, leading to streak formation inside the cornea.

  3. Theory of spin and lattice wave dynamics excited by focused laser pulses

    Science.gov (United States)

    Shen, Ka; Bauer, Gerrit E. W.

    2018-06-01

    We develop a theory of spin wave dynamics excited by ultrafast focused laser pulses in a magnetic film. We take into account both the volume and surface spin wave modes in the presence of applied, dipolar and magnetic anisotropy fields and include the dependence on laser spot exposure size and magnetic damping. We show that the sound waves generated by local heating by an ultrafast focused laser pulse can excite a wide spectrum of spin waves (on top of a dominant magnon–phonon contribution). Good agreement with recent experiments supports the validity of the model.

  4. Simulation of laser-tattoo pigment interaction in a tissue-mimicking phantom using Q-switched and long-pulsed lasers.

    Science.gov (United States)

    Ahn, K J; Kim, B J; Cho, S B

    2017-08-01

    Laser therapy is the treatment of choice in tattoo removal. However, the precise mechanisms of laser-tattoo pigment interactions remain to be evaluated. We evaluated the geometric patterns of laser-tattoo pigment particle interactions using a tattoo pigment-embedded tissue-mimicking (TM) phantom. A Q-switched (QS) neodymium-doped yttrium aluminum garnet laser was used at settings of 532-, 660-, and 1064-nm wavelengths, single-pulse and quick pulse-to-pulse treatment modes, and spot sizes of 4 and 7 mm. Most of the laser-tattoo interactions in the experimental conditions formed cocoon-shaped or oval photothermal and photoacoustic injury zones, which contained fragmented tattoo particles in various sizes depending on the conditions. In addition, a long-pulsed 755-nm alexandrite laser was used at a spot size of 6 mm and pulse widths of 3, 5, and 10 ms. The finer granular pattern of tattoo destruction was observed in TM phantoms treated with 3- and 5-ms pulse durations compared to those treated with a 10-ms pulse. We outlined various patterns of laser-tattoo pigment interactions in a tattoo-embedded TM phantom to predict macroscopic tattoo and surrounding tissue reactions after laser treatment for tattoo removal. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Ultra Stable, Industrial Green Tailored Pulse Fiber Laser with Diffraction-limited Beam Quality for Advanced Micromachining

    International Nuclear Information System (INIS)

    Deladurantaye, P; Roy, V; Desbiens, L; Drolet, M; Taillon, Y; Galarneau, P

    2011-01-01

    We report on a novel pulsed fiber laser platform providing pulse shaping agility at high repetition rates and at a wavelength of 532 nm. The oscillator is based on the direct modulation of a seed laser diode followed by a chain of fiber amplifiers. Advanced Large Mode Area (LMA) fiber designs as well as proprietary techniques to mitigate non-linear effects enable output energy per pulse up to 100 μJ at 1064 nm with diffraction-limited beam quality and narrow line widths suitable for efficient frequency conversion. Ultra stable pulses with tailored pulse shapes were demonstrated in the green region of the spectrum at repetition rates higher than 200 kHz. Pulse durations between 2.5 ns and 640 ns are available, as well as pulse to pulse dynamic shape selection at repetition rates up to 1 MHz. The pulse energy stability at 532 nm is better than ± 1.5%, 3σ, over 10 000 pulses. Excellent beam characteristics were obtained. The M 2 parameter is lower than 1.05, the beam waist astigmatism and beam waist asymmetry are below 10% and below 8% respectively, with high stability over time. We foresee that the small spot size, high repetition rate and pulse tailoring capability of this platform will provide advantages to practitioners who are developing novel, advanced processes in many industrially important applications.

  6. Spot market for uranium

    International Nuclear Information System (INIS)

    Colhoun, C.

    1982-01-01

    The spot market is always quoted for the price of uranium because little information is available about long-term contracts. A review of the development of spot market prices shows the same price curve swings that occur with all raw materials. Future long-term contracts will probably be lower to reflect spot market prices, which are currently in the real-value range of $30-$35. An upswing in the price of uranium could come in the next few months as utilities begin making purchases and trading from stockpiles. The US, unlike Europe and Japan, has already reached a supply and demand point where the spot market share is increasing. Forecasters cannot project the market price, they can only predict the presence of an oscillating spot or a secondary market. 5 figures

  7. DNA double-strand breaks in mammalian cells exposed to γ-rays and very heavy ions. Fragment-size distributions determined by pulsed-field gel electrophoresis

    International Nuclear Information System (INIS)

    Kraxenberger, F.; Friedl, A.A.; Eckardt-Schupp, F.; Weber, K.J.; Flentje, M.; Quicken, P.; Kellerer, A.M.; Ludwig-Maximilians University, Munich

    1998-01-01

    The spatial distribution of DNA double-strand breaks (DSB) was assessed after treatment of mammalian cells (V79) with densely ionizing radiation. Cells were exposed to beams of heavy charged particles (calcium ions: 6.9 MeV/u, 2.1.10 3 keV/μm; uranium ions: 9.0 MeV/u, 1.4.10 4 keV/μm) at the linear accelerator UNILAC of GSI, Darmstadt. DNA was isolated in agarose plugs and subjected to pulsed-field gel electrophoresis under conditions that separated DNA fragments of size 50 kbp to 5 Mbp. The measured fragment distributions were compared to those obtained after γ-irradiation and were analyzed by means of a convolution and a deconvolution technique. In contrast to the finding for γ-radiation, the distributions produced by heavy ions do not correspond to the random breakage model. Their marked overdispersion and the observed excess of short fragments reflect spatial clustering of DSB that extends over large regions of the DNA, up to several mega base pairs (Mbp). At fluences of 0.75 and 1.5/μm 2 , calcium ions produce nearly the same shape of fragment spectrum, merely with a difference in the amount of DNA entering the gel; this suggests that the DNA is fragmented by individual calcium ions. At a fluence of 0.8/μm 2 uranium ions produce a profile that is shifted to smaller fragment sizes in comparison to the profile obtained at a fluence of 0.4/μm 2 ; this suggests cumulative action of two separate ions in the formation of fragments. These observations are not consistent with the expectation that the uranium ions, with their much larger LET, should be more likely to produce single particle action than the calcium ions. However, a consideration of the greater lateral extension of the tracks of the faster uranium ions explains the observed differences; it suggests that the DNA is closely coiled so that even DNA locations several Mbp apart are usually not separated by less than 0.1 or 0.2 μm. (orig.)

  8. Analysis of radial and longitudinal field of plasma wakefield generated by a Laguerre-Gauss laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Firouzjaei, Ali Shekari; Shokri, Babak [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839-63113 (Iran, Islamic Republic of)

    2016-06-15

    In the present paper, we study the wakes known as the donut wake which is generated by Laguerre-Gauss (LG) laser pulses. Effects of the special spatial profile of a LG pulse on the radial and longitudinal wakefields are presented via an analytical model in a weakly non-linear regime in two dimensions. Different aspects of the donut-shaped wakefields have been analyzed and compared with Gaussian-driven wakes. There is also some discussion about the accelerating-focusing phase of the donut wake. Variations of longitudinal and radial wakes with laser amplitude, pulse length, and pulse spot size have been presented and discussed. Finally, we present the optimum pulse duration for such wakes.

  9. Launch and capture of a single particle in a pulse-laser-assisted dual-beam fiber-optic trap

    Science.gov (United States)

    Fu, Zhenhai; She, Xuan; Li, Nan; Hu, Huizhu

    2018-06-01

    The rapid loading and manipulation of microspheres in optical trap is important for its applications in optomechanics and precision force sensing. We investigate the microsphere behavior under coaction of a dual-beam fiber-optic trap and a pulse laser beam, which reveals a launched microsphere can be effectively captured in a spatial region. A suitable order of pulse duration for launch is derived according to the calculated detachment energy threshold of pulse laser. Furthermore, we illustrate the effect of structural parameters on the launching process, including the spot size of pulse laser, the vertical displacement of beam waist and the initial position of microsphere. Our result will be instructive in the optimal design of the pulse-laser-assisted optical tweezers for controllable loading mechanism of optical trap.

  10. Large area crystallization of amorphous Si with overlapping high repetition rate laser pulses

    KAUST Repository

    Ryu, Sang-Gil

    2012-09-01

    This paper presents a pulsed laser crystallization technique, enabling large area crystallization of amorphous Si to produce grains having well-defined size and orientation. The method is developed by first determining the parameters influencing crystallization induced by single laser pulses of circular cross-sectional profile. In a second step, crystallization by overlapping round spots is examined. The experiments reveal three zones characterized by distinctly different crystallized morphologies following the laser irradiation. One of these zones corresponds to the regime of lateral crystal growth, wherein grains are driven towards the center of the spot by the radial temperature gradient. These findings are then applied to processing via line beam profiles that facilitate large area crystallization upon rapid translation of the specimen. Crystallization of extended areas hinges on the determination of the crystal growth length for a single spot. The pitch between successive pulses is then set on the basis of this information. It is shown that the pulse energy has only a weak effect on the crystal growth length. © 2012 Elsevier B.V.

  11. Relationship between hot spot residues and ligand binding hot spots in protein-protein interfaces.

    Science.gov (United States)

    Zerbe, Brandon S; Hall, David R; Vajda, Sandor; Whitty, Adrian; Kozakov, Dima

    2012-08-27

    In the context of protein-protein interactions, the term "hot spot" refers to a residue or cluster of residues that makes a major contribution to the binding free energy, as determined by alanine scanning mutagenesis. In contrast, in pharmaceutical research, a hot spot is a site on a target protein that has high propensity for ligand binding and hence is potentially important for drug discovery. Here we examine the relationship between these two hot spot concepts by comparing alanine scanning data for a set of 15 proteins with results from mapping the protein surfaces for sites that can bind fragment-sized small molecules. We find the two types of hot spots are largely complementary; the residues protruding into hot spot regions identified by computational mapping or experimental fragment screening are almost always themselves hot spot residues as defined by alanine scanning experiments. Conversely, a residue that is found by alanine scanning to contribute little to binding rarely interacts with hot spot regions on the partner protein identified by fragment mapping. In spite of the strong correlation between the two hot spot concepts, they fundamentally differ, however. In particular, while identification of a hot spot by alanine scanning establishes the potential to generate substantial interaction energy with a binding partner, there are additional topological requirements to be a hot spot for small molecule binding. Hence, only a minority of hot spots identified by alanine scanning represent sites that are potentially useful for small inhibitor binding, and it is this subset that is identified by experimental or computational fragment screening.

  12. Plutonium spot of mixed oxide fuel, 2

    International Nuclear Information System (INIS)

    Suzuki, Yukio; Maruishi, Yoshihiro; Satoh, Masaichi; Aoki, Toshimasa; Muto, Tadashi

    1974-01-01

    In a fast reactor, the specification for the homogeneity of plutonium in plutonium-uranium mixed-oxide fuel is mainly dependent on the nuclear characteristics, whereas in a thermal reactor, on thermal characteristics. This homogeneity is measured by autoradiography as the plutonium spot size of the specimens which are arbitrarily chosen fuel pellets from a lot. Although this is a kind of random sampling, it is difficult to apply this method to conventional digital standards including JIS standards. So a special sampling inspection method was studied. First, it is assumed that the shape of plutonium spots is spherical, the size distribution is logarithmic normal, and the standard deviation is constant. Then, if standard deviation and mean spot size are given, the logarithmic normal distribution is decided unitarily, and further if the total weight of plutonium spots for a lot of pellets is known, the number of the spots (No) which does not conform to the specification can be obtained. Then, the fraction defective is defined as No devided by the number of pellets per lot. As to the lot with such fraction defective, the acceptance coefficient of the lot was obtained through calculation, in which the number of sampling, acceptable diameter limit observed and acceptable conditions were used as parameters. (Tai, I.)

  13. ESA uncovers Geminga's `hot spot'

    Science.gov (United States)

    2004-07-01

    16 July 2004 Astronomers using ESA’s X-ray observatory XMM-Newton have detected a small, bright ‘hot spot’ on the surface of the neutron star called Geminga, 500 light-years away. The hot spot is the size of a football field and is caused by the same mechanism producing Geminga’s X-ray tails. This discovery identifies the missing link between the X-ray and gamma-ray emission from Geminga. hi-res Size hi-res: 1284 kb Credits: ESA, P. Caraveo (IASF, Milan) Geminga's hot spot This figure shows the effects of charged particles accelerated in the magnetosphere of Geminga. Panel (a) shows an image taken with the EPIC instrument on board the XMM-Newton observatory. The bright tails, made of particles kicked out by Geminga’s strong magnetic field, trail the neutron star as it moves about in space. Panel (b) shows how electrically charged particles interact with Geminga’s magnetic field. For example, if electrons (blue) are kicked out by the star, positrons (in red) hit the star’s magnetic poles like in an ‘own goal’. Panel (c) illustrates the size of Geminga’s magnetic field (blue) compared to that of the star itself at the centre (purple). The magnetic field is tilted with respect to Geminga’s rotation axis (red). Panel (d) shows the magnetic poles of Geminga, where charged particles hit the surface of the star, creating a two-million degrees hot spot, a region much hotter than the surroundings. As the star spins on its rotation axis, the hot spot comes into view and then disappears, causing the periodic colour change seen by XMM-Newton. An animated version of the entire sequence can be found at: Click here for animated GIF [low resolution, animated GIF, 5536 KB] Click here for AVI [high resolution, AVI with DIVX compression, 19128 KB] hi-res Size hi-res: 371 kb Credits: ESA, P. Caraveo (IASF, Milan) Geminga's hot spot, panel (a) Panel (a) shows an image taken with the EPIC instrument on board the XMM-Newton observatory. The bright tails, made of

  14. Utility of large spot binocular indirect laser delivery for peripheral photocoagulation therapy in children.

    Science.gov (United States)

    Balasubramaniam, Saranya C; Mohney, Brian G; Bang, Genie M; Link, Thomas P; Pulido, Jose S

    2012-09-01

    The purpose of this article is to demonstrate the utility of the large spot size (LSS) setting using a binocular laser indirect delivery system for peripheral ablation in children. One patient with bilateral retinopathy of prematurity received photocoagulation with standard spot size burns placed adjacently to LSS burns. Using a pixel analysis program called Image J on the Retcam picture, the areas of each retinal spot size were determined in units of pixels, giving a standard spot range of 805 to 1294 pixels and LSS range of 1699 to 2311 pixels. Additionally, fluence was calculated using theoretical retinal areas produced by each spot size: the standard spot setting was 462 mJ/mm2 and the LSS setting was 104 mJ/mm2. For eyes with retinopathy of prematurity, our study shows that LSS laser indirect delivery halves the number of spots required for treatment and reduces fluence by almost one-quarter, producing more uniform spots.

  15. Mononucleosis spot test

    Science.gov (United States)

    Monospot test; Heterophile antibody test; Heterophile agglutination test; Paul-Bunnell test; Forssman antibody test ... The mononucleosis spot test is done when symptoms of mononucleosis are ... Fatigue Fever Large spleen (possibly) Sore throat Tender ...

  16. Arc cathode spots

    International Nuclear Information System (INIS)

    Schrade, H.O.

    1989-01-01

    Arc spots are usually highly unstable and jump statistically over the cathode surface. In a magnetic field parallel to the surface, preferably they move in the retrograde direction; i.e., opposite to the Lorentzian rule. If the field is inclined with respect to the surface, the spots drift away at a certain angle with respect to the proper retrograde direction (Robson drift motion). These well-known phenomena are explained by one stability theory

  17. Ignition of a reactive solid by an inert hot spot

    OpenAIRE

    Liñán Martínez, Amable; Kindelan Gómez, Manuel

    1981-01-01

    A theoretical analysis is presented for the description of the ignition of a reactive media by inert hot bodies of finite size, when the activation energy of the reaction is large. The analysis leads to closed-form relations for the minimum "critical" size of the hot spot resulting in ignition and for the ignition time by hot spots of supercritical size. The analysis is carried out, first, for inert spots with heat conductivities and diff usivities of the order of those of the reactive media,...

  18. Dramatic Change in Jupiter's Great Red Spot

    Science.gov (United States)

    Simon, A. A.; Wong, M. H.; Rogers, J. H.; Orton, G. S.; de Pater, I.; Asay-Davis, X.; Carlson, R. W.; Marcus, P. S.

    2015-01-01

    Jupiter's Great Red Spot (GRS) is one of its most distinct and enduring features, having been continuously observed since the 1800's. It currently spans the smallest latitude and longitude size ever recorded. Here we show analyses of 2014 Hubble spectral imaging data to study the color, structure and internal dynamics of this long-live storm.

  19. Ultrashort pulse laser deposition of thin films

    Science.gov (United States)

    Perry, Michael D.; Banks, Paul S.; Stuart, Brent C.

    2002-01-01

    Short pulse PLD is a viable technique of producing high quality films with properties very close to that of crystalline diamond. The plasma generated using femtosecond lasers is composed of single atom ions with no clusters producing films with high Sp.sup.3 /Sp.sup.2 ratios. Using a high average power femtosecond laser system, the present invention dramatically increases deposition rates to up to 25 .mu.m/hr (which exceeds many CVD processes) while growing particulate-free films. In the present invention, deposition rates is a function of laser wavelength, laser fluence, laser spot size, and target/substrate separation. The relevant laser parameters are shown to ensure particulate-free growth, and characterizations of the films grown are made using several diagnostic techniques including electron energy loss spectroscopy (EELS) and Raman spectroscopy.

  20. Technical Note: Spot characteristic stability for proton pencil beam scanning.

    Science.gov (United States)

    Chen, Chin-Cheng; Chang, Chang; Moyers, Michael F; Gao, Mingcheng; Mah, Dennis

    2016-02-01

    The spot characteristics for proton pencil beam scanning (PBS) were measured and analyzed over a 16 month period, which included one major site configuration update and six cyclotron interventions. The results provide a reference to establish the quality assurance (QA) frequency and tolerance for proton pencil beam scanning. A simple treatment plan was generated to produce an asymmetric 9-spot pattern distributed throughout a field of 16 × 18 cm for each of 18 proton energies (100.0-226.0 MeV). The delivered fluence distribution in air was measured using a phosphor screen based CCD camera at three planes perpendicular to the beam line axis (x-ray imaging isocenter and up/down stream 15.0 cm). The measured fluence distributions for each energy were analyzed using in-house programs which calculated the spot sizes and positional deviations of the Gaussian shaped spots. Compared to the spot characteristic data installed into the treatment planning system, the 16-month averaged deviations of the measured spot sizes at the isocenter plane were 2.30% and 1.38% in the IEC gantry x and y directions, respectively. The maximum deviation was 12.87% while the minimum deviation was 0.003%, both at the upstream plane. After the collinearity of the proton and x-ray imaging system isocenters was optimized, the positional deviations of the spots were all within 1.5 mm for all three planes. During the site configuration update, spot positions were found to deviate by 6 mm until the tuning parameters file was properly restored. For this beam delivery system, it is recommended to perform a spot size and position check at least monthly and any time after a database update or cyclotron intervention occurs. A spot size deviation tolerance of spot positions were <2 mm at any plane up/down stream 15 cm from the isocenter.

  1. Simulations of drastically reduced SBS with laser pulses composed of a Spike Train of Uneven Duration and Delay (STUD pulses)

    International Nuclear Information System (INIS)

    Hueller, S.; Afeyan, B.

    2013-01-01

    By comparing the impact of established laser smoothing techniques like Random Phase Plates (RPP) and Smoothing by Spectral Dispersion (SSD) to the concept of 'Spike Trains of Uneven Duration and Delay' (STUD pulses) on the amplification of parametric instabilities in laser-produced plasmas, we show with the help of numerical simulations, that STUD pulses can drastically reduce instability growth by orders of magnitude. The simulation results, obtained with the code Harmony in a nonuniformly flowing mm-size plasma for the Stimulated Brillouin Scattering (SBS) instability, show that the efficiency of the STUD pulse technique is due to the fact that successive re-amplification in space and time of parametrically excited plasma waves inside laser hot spots is minimized. An overall mean fluctuation level of ion acoustic waves at low amplitude is established because of the frequent change of the speckle pattern in successive spikes. This level stays orders of magnitude below the levels of ion acoustic waves excited in hot spots of RPP and SSD laser beams. (authors)

  2. Current indications and new applications of intense pulsed light.

    Science.gov (United States)

    González-Rodríguez, A J; Lorente-Gual, R

    2015-06-01

    Intense pulsed light (IPL) systems have evolved since they were introduced into medical practice 20 years ago. Pulsed light is noncoherent, noncollimated, polychromatic light energy emitted at different wavelengths that target specific chromophores. This selective targeting capability makes IPL a versatile therapy with many applications, from the treatment of pigmented or vascular lesions to hair removal and skin rejuvenation. Its large spot size ensures a high skin coverage rate. The nonablative nature of IPL makes it an increasingly attractive alternative for patients unwilling to accept the adverse effects associated with other procedures, which additionally require prolonged absence from work and social activities. In many cases, IPL is similar to laser therapy in effectiveness, and its versatility, convenience, and safety will lead to an expanded range of applications and possibilities in coming years. Copyright © 2014 Elsevier España, S.L.U. and AEDV. All rights reserved.

  3. Impact of spot charge inaccuracies in IMPT treatments.

    Science.gov (United States)

    Kraan, Aafke C; Depauw, Nicolas; Clasie, Ben; Giunta, Marina; Madden, Tom; Kooy, Hanne M

    2017-08-01

    Spot charge is one parameter of pencil-beam scanning dose delivery system whose accuracy is typically high but whose required value has not been investigated. In this work we quantify the dose impact of spot charge inaccuracies on the dose distribution in patients. Knowing the effect of charge errors is relevant for conventional proton machines, as well as for new generation proton machines, where ensuring accurate charge may be challenging. Through perturbation of spot charge in treatment plans for seven patients and a phantom, we evaluated the dose impact of absolute (up to 5× 10 6 protons) and relative (up to 30%) charge errors. We investigated the dependence on beam width by studying scenarios with small, medium and large beam sizes. Treatment plan statistics included the Γ passing rate, dose-volume-histograms and dose differences. The allowable absolute charge error for small spot plans was about 2× 10 6 protons. Larger limits would be allowed if larger spots were used. For relative errors, the maximum allowable error size for small, medium and large spots was about 13%, 8% and 6% for small, medium and large spots, respectively. Dose distributions turned out to be surprisingly robust against random spot charge perturbation. Our study suggests that ensuring spot charge errors as small as 1-2% as is commonly aimed at in conventional proton therapy machines, is clinically not strictly needed. © 2017 American Association of Physicists in Medicine.

  4. Hot spot formation on different tokamak wall materials

    International Nuclear Information System (INIS)

    Nedospasov, A.V.; Bezlyudny, I.V.

    1998-01-01

    The thermal contraction phenomenon and generation of 'hot spots' due to thermoemission were described. The paper consider non-linear stages of heat contraction on the graphite, beryllium, tungsten and vanadium wall. It is shown that on the beryllium surface hot spot can't appear due to strong cooling by sublimation. For other materials the conditions of hot spot appearance due to local superheating of the wall have been calculated and their parameters were found: critical surface temperature, size of spots and their temperature profiles, heat fluxes from plasma to the spots. It have been calculated fluxes of sublimating materials from spots to the plasma. It is noticed that nominal temperature of the grafite divertor plate, accepted in ITER's project to being equal 1500 C, is lower then critical temperature of the development heat contraction due to thermoemission. (orig.)

  5. Genetic characterization of angular leaf spot resistance in selected ...

    African Journals Online (AJOL)

    Mr Tryphone

    2015-10-28

    Oct 28, 2015 ... Angular leaf spot disease (ALS) caused by Pseudocercospora griseola is one ... Author(s) agree that this article remains permanently open access under the terms ... that results in shrivelled seeds of reduced size and quality.

  6. Pulse Generator

    Science.gov (United States)

    Greer, Lawrence (Inventor)

    2017-01-01

    An apparatus and a computer-implemented method for generating pulses synchronized to a rising edge of a tachometer signal from rotating machinery are disclosed. For example, in one embodiment, a pulse state machine may be configured to generate a plurality of pulses, and a period state machine may be configured to determine a period for each of the plurality of pulses.

  7. Role of Laser Power, Wavelength, and Pulse Duration in Laser Assisted Tin-Induced Crystallization of Amorphous Silicon

    Directory of Open Access Journals (Sweden)

    V. B. Neimash

    2018-01-01

    Full Text Available This work describes tin-induced crystallization of amorphous silicon studied with Raman spectroscopy in thin-film structures Si-Sn-Si irradiated with pulsed laser light. We have found and analyzed dependencies of the nanocrystals’ size and concentration on the laser pulse intensity for 10 ns and 150 μm duration laser pulses at the wavelengths of 535 nm and 1070 nm. Efficient transformation of the amorphous silicon into a crystalline phase during the 10 ns time interval of the acting laser pulse in the 200 nm thickness films of the amorphous silicon was demonstrated. The results were analyzed theoretically by modeling the spatial and temporal distribution of temperature in the amorphous silicon sample within the laser spot location. Simulations confirmed importance of light absorption depth (irradiation wavelength in formation and evolution of the temperature profile that affects the crystallization processes in irradiated structures.

  8. effect of the plasma ion channel on self-focusing of a Gaussian laser pulse in underdense plasma

    Directory of Open Access Journals (Sweden)

    Sh Irani

    2013-09-01

    Full Text Available  We have considered the self-focusing of a Gaussian laser pulse in unmagnetized plasma. High-intensity electromagnetic fields cause the variation of electron density in plasma. These changes in the special conditions cause the acceleration of electrons to the higher energy and velocities. Thus the equation of plasma density evolution was obtained considering the electrons ponderomotive force. Then, an equation for the width of laser pulse with a relativistic mass correction term and the effect of ion channel were derived and the propagation of high-intensity laser pulse in an underdense plasma with weak relativistic approximation was investigated. It is shown that the ratio of ion channel radius to spot size could result in different forms of self focusing for the laser pulse in plasma.

  9. Occurrence of gum spots in black cherry after partial harvest cutting

    Science.gov (United States)

    Charles O. Rexrode; H. Clay Smith; H. Clay Smith

    1990-01-01

    Bark beetles, primarily the bark beetle Phlosotribus liminori (Harris), are the major cause of gum spots in sawtimber-size black cherry Prunus serotina Ehrh. Approximately 90 percent of all gum spots in the bole sections are caused by bark beetles. Gum spots were studied in 95 black cherry trees near Parsons, West Virginia. Over 50 percent of the bark beetle-caused gum...

  10. Molecular and histological characterization of age spots

    Science.gov (United States)

    Choi, Wonseon; Yin, Lanlan; Smuda, Christoph; Batzer, Jan; Hearing, Vincent J.; Kolbe, Ludger

    2016-01-01

    Age spots, also called solar lentigines and lentigo senilis, are light brown to black pigmented lesions of various sizes that typically develop in chronically sun-exposed skin. It is well known that age spots are strongly related to chronic sun exposure and are associated with photodamage and an increased risk for skin cancer, however, the mechanism(s) underlying their development remain poorly understood. We used immunohistochemical analysis and microarray analysis to investigate the processes involved in their formation, focusing on specific markers associated with the functions and proliferation of melanocytes and keratinocytes. A total of 193 genes were differentially expressed in age spots but melanocyte pigment genes were not among them. The increased expression of keratins 5 and 10, markers of basal and suprabasal keratinocytes, respectively, in age spots suggests that the increased proliferation of basal keratinocytes combined with the decreased turnover of suprabasal keratinocytes leads to the exaggerated formation of rete ridges in lesional epidermis which in turn disrupts the normal processing of melanin upwards from the basal layer. Based on our results, we propose a model for the development of age spots that explains the accumulation of melanin and the development of extensive rete ridges in those hyperpigmented lesions. PMID:27621222

  11. Glare Spot Phase Doppler Anemometry

    Science.gov (United States)

    Hespel, Camille; Ren, Kuanfang; Gréhan, Gérard; Onofri, Fabrice

    2007-06-01

    The Phase Doppler anemometry has been developed to measure simultaneously the velocity and the size of droplets. The measurement of the refractive index would be also interesting since it depends on the temperature and the composition of the particle and its measurement permits both to increase the quality of the diameter measurement and to obtain information on the temperature and/or the composition of the droplets. In this paper, we introduce a Glare Spot Phase Doppler Anemometry which uses two large beams. In this case, the images of the particle formed by the reflected and refracted light, known as glare spots, are separated in space. When a particle passes in the probe volume, the two parts in a signal obtained by a detector in forward direction are then separated in time. If two detectors are used the phase differences between two signals, the distance and the intensity ratio of reflected and refracted parts can be obtained and they provide rich information about the particle diameter and its refractive index, as well as its velocity. This paper is devoted to the numerical study of such a configuration with two theoretical models: geometrical optics and rigorous electromagnetism solution.

  12. Integrating sustainable hunting in biodiversity protection in Central Africa: hot spots, weak spots, and strong spots.

    Directory of Open Access Journals (Sweden)

    John E Fa

    Full Text Available Wild animals are a primary source of protein (bushmeat for people living in or near tropical forests. Ideally, the effect of bushmeat harvests should be monitored closely by making regular estimates of offtake rate and size of stock available for exploitation. However, in practice, this is possible in very few situations because it requires both of these aspects to be readily measurable, and even in the best case, entails very considerable time and effort. As alternative, in this study, we use high-resolution, environmental favorability models for terrestrial mammals (N = 165 in Central Africa to map areas of high species richness (hot spots and hunting susceptibility. Favorability models distinguish localities with environmental conditions that favor the species' existence from those with detrimental characteristics for its presence. We develop an index for assessing Potential Hunting Sustainability (PHS of each species based on their ecological characteristics (population density, habitat breadth, rarity and vulnerability, weighted according to restrictive and permissive assumptions of how species' characteristics are combined. Species are classified into five main hunting sustainability classes using fuzzy logic. Using the accumulated favorability values of all species, and their PHS values, we finally identify weak spots, defined as high diversity regions of especial hunting vulnerability for wildlife, as well as strong spots, defined as high diversity areas of high hunting sustainability potential. Our study uses relatively simple models that employ easily obtainable data of a species' ecological characteristics to assess the impacts of hunting in tropical regions. It provides information for management by charting the geography of where species are more or less likely to be at risk of extinction from hunting.

  13. Collaboration spotting for dental science.

    Science.gov (United States)

    Leonardi, E; Agocs, A; Fragkiskos, S; Kasfikis, N; Le Goff, J M; Cristalli, M P; Luzzi, V; Polimeni, A

    2014-10-06

    The goal of the Collaboration Spotting project is to create an automatic system to collect information about publications and patents related to a given technology, to identify the key players involved, and to highlight collaborations and related technologies. The collected information can be visualized in a web browser as interactive graphical maps showing in an intuitive way the players and their collaborations (Sociogram) and the relations among the technologies (Technogram). We propose to use the system to study technologies related to Dental Science. In order to create a Sociogram, we create a logical filter based on a set of keywords related to the technology under study. This filter is used to extract a list of publications from the Web of Science™ database. The list is validated by an expert in the technology and sent to CERN where it is inserted in the Collaboration Spotting database. Here, an automatic software system uses the data to generate the final maps. We studied a set of recent technologies related to bone regeneration procedures of oro--maxillo--facial critical size defects, namely the use of Porous HydroxyApatite (HA) as a bone substitute alone (bone graft) or as a tridimensional support (scaffold) for insemination and differentiation ex--vivo of Mesenchymal Stem Cells. We produced the Sociograms for these technologies and the resulting maps are now accessible on--line. The Collaboration Spotting system allows the automatic creation of interactive maps to show the current and historical state of research on a specific technology. These maps are an ideal tool both for researchers who want to assess the state--of--the--art in a given technology, and for research organizations who want to evaluate their contribution to the technological development in a given field. We demonstrated that the system can be used for Dental Science and produced the maps for an initial set of technologies in this field. We now plan to enlarge the set of mapped

  14. Collaboration Spotting for oral medicine.

    Science.gov (United States)

    Leonardi, E; Agocs, A; Fragkiskos, S; Kasfikis, N; Le Goff, J M; Cristalli, M P; Luzzi, V; Polimeni, A

    2014-09-01

    The goal of the Collaboration Spotting project is to create an automatic system to collect information about publications and patents related to a given technology, to identify the key players involved, and to highlight collaborations and related technologies. The collected information can be visualized in a web browser as interactive graphical maps showing in an intuitive way the players and their collaborations (Sociogram) and the relations among the technologies (Technogram). We propose to use the system to study technologies related to oral medicine. In order to create a sociogram, we create a logical filter based on a set of keywords related to the technology under study. This filter is used to extract a list of publications from the Web of Science™ database. The list is validated by an expert in the technology and sent to CERN where it is inserted in the Collaboration Spotting database. Here, an automatic software system uses the data to generate the final maps. We studied a set of recent technologies related to bone regeneration procedures of oro-maxillo-facial critical size defects, namely the use of porous hydroxyapatite (HA) as a bone substitute alone (bone graft) or as a tridimensional support (scaffold) for insemination and differentiation ex vivo of mesenchymal stem cells. We produced the sociograms for these technologies and the resulting maps are now accessible on-line. The Collaboration Spotting system allows the automatic creation of interactive maps to show the current and historical state of research on a specific technology. These maps are an ideal tool both for researchers who want to assess the state-of-the-art in a given technology, and for research organizations who want to evaluate their contribution to the technological development in a given field. We demonstrated that the system can be used in oral medicine as is produced the maps for an initial set of technologies in this field. We now plan to enlarge the set of mapped technologies in

  15. Self-Guiding of Ultrashort Relativistically Intense Laser Pulses to the Limit of Nonlinear Pump Depletion

    International Nuclear Information System (INIS)

    Ralph, J. E.; Marsh, K. A.; Pak, A. E.; Lu, W.; Clayton, C. E.; Fang, F.; Joshi, C.; Tsung, F. S.; Mori, W. B.

    2009-01-01

    A study of self-guiding of ultra short, relativistically intense laser pulses is presented. Here, the laser pulse length is on the order of the nonlinear plasma wavelength and the normalized vector potential is greater than one. Self-guiding of ultrashort laser pulses over tens of Rayliegh lengths is possible when driving a highly nonlinear wake. In this case, self-guiding is limited by nonlinear pump depletion. Erosion of the pulse due to diffraction at the head of the laser pulse is minimized for spot sizes close to the blow-out radius. This is due to the slowing of the group velocity of the photons at the head of the laser pulse. Using an approximately 10 TW Ti:Sapphire laser with a pulse length of approximately 50 fs, experimental results are presented showing self-guiding over lengths exceeding 30 Rayliegh lengths in various length Helium gas jets. Fully explicit 3D PIC simulations supporting the experimental results are also presented.

  16. TV spots' impact.

    Science.gov (United States)

    El-bakly, S

    1994-09-01

    The Information, Education and Communication (IEC) Center of the State Information Service was established in 1979 for the purpose of providing information to the people on the population issue. The Ministry of Information has accorded the State Information Service free TV and radio air time for family planning dramas and spots. In the early years information campaigns were organized to make people aware of the population problem by slogans, songs, and cartoons. Around 1984 misconceptions about family planning and contraceptives were attacked through a number of TV and radio spots. A few years later 21 spots on specific contraceptive methods were broadcast which were aired for three years over 3000 times. They were extremely successful. The impact of these TV spots was one of the major reasons why the contraceptive prevalence rate increased from 30% in 1984 to 38% in 1988 and 47% in 1992. Spots were also broadcast about the social implications of large families. The TV soap opera "And The Nile Flows On", with the family planning message interwoven into it, was very well received by the target audience. A program entitled "Wedding of the Month" features couples who know family planning well. The most successful radio program is a 15-20 minute long quiz show for residents of the villages where the Select Villages Project is being implemented. The State Information Service has 60 local information centers in the 26 governorates of Egypt that make plans for the family planning campaign. In 1992 the Minya Initiative, a family planning project was implemented in the Minya Governorate. As a result, the contraceptive prevalence rate rose from 22% to 30% over 18 months. A new project, the Select Village Project, was developed in 1993 that replicates the Minya Initiative on the village level in other governorates. This new project that was implemented in sixteen governorates.

  17. Towards shorter wavelength x-ray lasers using a high power, short pulse pump laser

    International Nuclear Information System (INIS)

    Tighe, W.; Krushelnick, K.; Valeo, E.; Suckewer, S.

    1991-05-01

    A near-terawatt, KrF* laser system, focussable to power densities >10 18 W/cm 2 has been constructed for use as a pump laser in various schemes aimed at the development of x-ray lasing below 5nm. The laser system along with output characteristics such as the pulse duration, the focal spot size, and the percentage of amplified spontaneous emission (ASE) emitted along with the laser pulse will be presented. Schemes intended to lead to shorter wavelength x-ray emission will be described. The resultant requirements on the pump laser characteristics and the target design will be outlined. Results from recent solid target experiments and two-laser experiments, showing the interaction of a high-power, short pulse laser with a preformed plasma, will be presented. 13 refs., 5 figs

  18. Allowable propagation of short pulse laser beam in a plasma channel and electromagnetic solitary waves

    International Nuclear Information System (INIS)

    Zhang, Shan; Hong, Xue-Ren; Wang, Hong-Yu; Xie, Bai-Song

    2011-01-01

    Nonparaxial and nonlinear propagation of a short intense laser beam in a parabolic plasma channel is analyzed by means of the variational method and nonlinear dynamics. The beam propagation properties are classified by five kinds of behaviors. In particularly, the electromagnetic solitary wave for finite pulse laser is found beside the other four propagation cases including beam periodically oscillating with defocussing and focusing amplitude, constant spot size, beam catastrophic focusing. It is also found that the laser pulse can be allowed to propagate in the plasma channel only when a certain relation for laser parameters and plasma channel parameters is satisfied. For the solitary wave, it may provide an effective way to obtain ultra-short laser pulse.

  19. Simulation and measurement of short infrared pulses on silicon position sensitive device

    International Nuclear Information System (INIS)

    Krapohl, D; Esebamen, O X; Nilsson, H E; Thungstroem, G

    2011-01-01

    Lateral position sensitive devices (PSD) are important for triangulation, alignment and surface measurements as well as for angle measurements. Large PSDs show a delay on rising and falling edges when irradiated with near infra-red light. This delay is also dependent on the spot position relative to the electrodes. It is however desirable in most applications to have a fast response. We investigated the responsiveness of a Sitek PSD in a mixed mode simulation of a two dimensional full sized detector. For simulation and measurement purposes focused light pulses with a wavelength of 850 nm, duration of 1μs and spot size of 280μm were used. The cause for the slopes of rise and fall time is due to time constants of the device capacitance as well as the photo-generation mechanism itself. To support the simulated results, we conducted measurements of rise and fall times on a physical device. Additionally, we quantified the homogeneity of the device by repositioning a spot of light from a pulsed ir-laser diode on the surface area.

  20. Roth spots in pernicious anaemia

    OpenAIRE

    Macauley, Mavin; Nag, Satyajit

    2011-01-01

    Roth spots are white-centred retinal haemorrhages, previously thought to be pathognomonic for subacute bacterial endocarditis. A number of other conditions can be associated with Roth spots. In this case, the authors describe the association of Roth spots and pernicious anaemia. This association has been rarely described in the medical literature. Correct diagnosis and treatment with intramuscular vitamin B12 injections resulted in complete resolution of the anaemia and Roth spots. The author...

  1. Poisson Spot with Magnetic Levitation

    Science.gov (United States)

    Hoover, Matthew; Everhart, Michael; D'Arruda, Jose

    2010-01-01

    In this paper we describe a unique method for obtaining the famous Poisson spot without adding obstacles to the light path, which could interfere with the effect. A Poisson spot is the interference effect from parallel rays of light diffracting around a solid spherical object, creating a bright spot in the center of the shadow.

  2. Plasma parameters of the cathode spot explosive electron emission cell obtained from the model of liquid-metal jet tearing and electrical explosion

    Science.gov (United States)

    Tsventoukh, M. M.

    2018-05-01

    A model has been developed for the explosive electron emission cell pulse of a vacuum discharge cathode spot that describes the ignition and extinction of the explosive pulse. The pulse is initiated due to hydrodynamic tearing of a liquid-metal jet which propagates from the preceding cell crater boundary and draws the ion current from the plasma produced by the preceding explosion. Once the jet neck has been resistively heated to a critical temperature (˜1 eV), the plasma starts expanding and decreasing in density, which corresponds to the extinction phase. Numerical and analytical solutions have been obtained that describe both the time behavior of the pulse plasma parameters and their average values. For the cell plasma, the momentum per transferred charge has been estimated to be some tens of g cm/(s C), which is consistent with the known measurements of ion velocity, ion erosion rate, and specific recoil force. This supports the model of the pressure-gradient-driven plasma acceleration mechanism for the explosive cathode spot cells. The ohmic electric field within the explosive current-carrying plasma has been estimated to be some tens of kV/cm, which is consistent with the known experimental data on cathode potential fall and explosive cell plasma size. This supports the model that assumes the ohmic nature of the cathode potential fall in a vacuum discharge.

  3. On the Spot: Oceans

    OpenAIRE

    Male, Alan; Butterfield, Moira

    2000-01-01

    This a children's non-fiction, knowledge bearing picture book that is part of a Reader's Digest series called 'On the Spot'. The series deals with a range of topics related to the natural world and this one introduces its young audience to the ecosystems of the oceans. \\ud The publication was illustrated and designed by the author (Alan Male) and is technically described as a board book with interactive 'pop up' features, specifically conceived to engage children's discovery and learning thro...

  4. El spot electoral negativo

    Directory of Open Access Journals (Sweden)

    Palma Peña-Jiménez

    2011-01-01

    Full Text Available l spot político tiene durante la campaña un objetivo final inequívoco: la consecución del voto favorable. Se dirige al cuerpo electoral a través de la televisión y de Internet, y presenta, en muchos casos, un planteamiento negativo, albergando mensajes destinados a la crítica frontal contra el adversario, más que a la exposición de propuestas propias. Este artículo se centra en el análisis del spot electoral negativo, en aquellas producciones audiovisuales construidas sin más causa que la reprobación del contrincante. Se trata de vídeos que, lejos de emplearse en difundir las potencialidades de la organización y las virtudes de su candidato –además de su programa electoral–, consumen su tiempo en descalificar al oponente mediante la transmisión de mensajes, muchas veces, ad hominem. Repasamos el planteamiento negativo del spot electoral desde su primera manifestación, que en España data de 1996, año de emisión del conocido como vídeo del dóberman, sin olvidar otros ejemplos que completan el objeto de estudio.

  5. Roth spots in pernicious anaemia.

    Science.gov (United States)

    Macauley, Mavin; Nag, Satyajit

    2011-04-19

    Roth spots are white-centred retinal haemorrhages, previously thought to be pathognomonic for subacute bacterial endocarditis. A number of other conditions can be associated with Roth spots. In this case, the authors describe the association of Roth spots and pernicious anaemia. This association has been rarely described in the medical literature. Correct diagnosis and treatment with intramuscular vitamin B(12) injections resulted in complete resolution of the anaemia and Roth spots. The authors hope to alert clinicians to think of various differentials of Roth spots, and initiate prompt investigation and management.

  6. Detecting hot spots at hazardous-waste sites

    International Nuclear Information System (INIS)

    Zirschky, J.; Gilbert, R.O.

    1984-01-01

    Evaluating the need for remedial cleanup at a waste site involves both finding the average contaminant concentration and identifying highly contaminated areas, or hot spots. A nomographic procedure to determine the sample configuration needed to locate a hot spot is presented. The technique can be used to develop a waste-site sampling plant - to determine either the grid spacing required to detect a hot spot at a given level of confidence, or the probability of finding a hot spot of a certain size, given a particular grid spacing. The method and computer program (ELIPGRID) were developed for locating geologic deposits, but the basic procedure can also be used to detect hot spots at chemical- or nuclear-waste disposal sites. Nomographs based on the original program are presented for three sampling-grid configurations - square, rectangular and triangular

  7. Effects of Laser Energy Density on Size and Morphology of NiO Nanoparticles Prepared by Pulsed Laser Ablation in Liquid

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Rory; Reddy, M. Amaranatha; Kim, Tae Kyu [Pusan National University, Busan (Korea, Republic of)

    2015-01-15

    Metaloxide nanoparticles are of great importance to a large variety of chemical and material applications ranging from catalysts to electronic devices. Among the metal-oxide nanoparticles, NiO is one of the technologically versatile and important semiconducting materials. It has been extensively investigated because of its myriad applications in catalysts, gas sensors, Li-ion battery materials, electrochromic coatings, active optical fibers, fuel cell electrodes, and so on. The effect of laser ablation at various laser energy densities was investigated. At low energy densities, the produced nanoparticles were of irregular morphology with an average size of 2.4 nm. At higher laser energy densities, the produced nanoparticles were spherical, with a polycrystalline structure and their average size was around 10 nm. More detailed investigations on effects of laser wavelength and energy density as well as the particle size effect on the catalytic activity of synthesized NiO nanoparticles will be investigated in future works.

  8. The Optical Properties of Cu-Ni Nanoparticles Produced via Pulsed Laser Dewetting of Ultrathin Films: The Effect of Nanoparticle Size and Composition on the Plasmon Response

    International Nuclear Information System (INIS)

    Wu, Yeuyeng; Fowlkes, Jason Davidson; Rack, Philip D.

    2011-01-01

    Thin film Cu-Ni alloys ranging from 2-8nm were synthesized and their optical properties were measured as-deposited and after a laser treatment which dewet the films into arrays of spatially correlated nanoparticles. The resultant nanoparticle size and spacing are attributed to laser induced spinodal dewetting process. The evolution of the spinodal dewetting process is investigated as a function of the thin film composition which ultimately dictates the size distribution and spacing of the nanoparticles. The optical measurements of the copper rich alloy nanoparticles reveal a signature absorption peak suggestive of a plasmonic peak which red-shifts with increasing nanoparticle size and blue shifts and dampens with increasing nickel concentration.

  9. Effects of spot parameters in pencil beam scanning treatment planning.

    Science.gov (United States)

    Kraan, Aafke Christine; Depauw, Nicolas; Clasie, Ben; Giunta, Marina; Madden, Tom; Kooy, Hanne M

    2018-01-01

    Spot size σ (in air at isocenter), interspot spacing d, and spot charge q influence dose delivery efficiency and plan quality in Intensity Modulated Proton Therapy (IMPT) treatment planning. The choice and range of parameters varies among different manufacturers. The goal of this work is to demonstrate the influence of the spot parameters on dose quality and delivery in IMPT treatment plans, to show their interdependence, and to make practitioners aware of the spot parameter values for a certain facility. Our study could help as a guideline to make the trade-off between treatment quality and time in existing PBS centers and in future systems. We created plans for seven patients and a phantom, with different tumor sites and volumes, and compared the effect of small-, medium-, and large-spot widths (σ = 2.5, 5, and 10 mm) and interspot distances (1σ, 1.5σ, and 1.75σ) on dose, spot charge, and treatment time. Moreover, we quantified how postplanning charge threshold cuts affect plan quality and the total number of spots to deliver, for different spot widths and interspot distances. We show the effect of a minimum charge (or MU) cutoff value for a given proton delivery system. Spot size had a strong influence on dose: larger spots resulted in more protons delivered outside the target region. We observed dose differences of 2-13 Gy (RBE) between 2.5 mm and 10 mm spots, where the amount of extra dose was due to dose penumbra around the target region. Interspot distance had little influence on dose quality for our patient group. Both parameters strongly influence spot charge in the plans and thus the possible impact of postplanning charge threshold cuts. If such charge thresholds are not included in the treatment planning system (TPS), it is important that the practitioner validates that a given combination of lower charge threshold, interspot spacing, and spot size does not result in a plan degradation. Low average spot charge occurs for small spots, small interspot

  10. Method for laser spot welding monitoring

    Science.gov (United States)

    Manassero, Giorgio

    1994-09-01

    As more powerful solid state laser sources appear on the market, new applications become technically possible and important from the economical point of view. For every process a preliminary optimization phase is necessary. The main parameters, used for a welding application by a high power Nd-YAG laser, are: pulse energy, pulse width, repetition rate and process duration or speed. In this paper an experimental methodology, for the development of an electrooptical laser spot welding monitoring system, is presented. The electromagnetic emission from the molten pool was observed and measured with appropriate sensors. The statistical method `Parameter Design' was used to obtain an accurate analysis of the process parameter that influence process results. A laser station with a solid state laser coupled to an optical fiber (1 mm in diameter) was utilized for the welding tests. The main material used for the experimental plan was zinc coated steel sheet 0.8 mm thick. This material and the related spot welding technique are extensively used in the automotive industry, therefore, the introduction of laser technology in production line will improve the quality of the final product. A correlation, between sensor signals and `through or not through' welds, was assessed. The investigation has furthermore shown the necessity, for the modern laser production systems, to use multisensor heads for process monitoring or control with more advanced signal elaboration procedures.

  11. Vocal complexity and sociality in spotted paca (Cuniculus paca).

    Science.gov (United States)

    Lima, Stella G C; Sousa-Lima, Renata S; Tokumaru, Rosana S; Nogueira-Filho, Sérgio L G; Nogueira, Selene S C

    2018-01-01

    The evolution of sociality is related to many ecological factors that act on animals as selective forces, thus driving the formation of groups. Group size will depend on the payoffs of group living. The Social Complexity Hypothesis for Communication (SCHC) predicts that increases in group size will be related to increases in the complexity of the communication among individuals. This hypothesis, which was confirmed in some mammal societies, may be useful to trace sociality in the spotted paca (Cuniculus paca), a Neotropical caviomorph rodent reported as solitary. There are, however, sightings of groups in the wild, and farmers easily form groups of spotted paca in captivity. Thus, we aimed to describe the acoustic repertoire of captive spotted paca to test the SCHC and to obtain insights about the sociability of this species. Moreover, we aimed to verify the relationship between group size and acoustic repertoire size of caviomorph rodents, to better understand the evolution of sociality in this taxon. We predicted that spotted paca should display a complex acoustic repertoire, given their social behavior in captivity and group sightings in the wild. We also predicted that in caviomorph species the group size would increase with acoustic repertoire, supporting the SCHC. We performed a Linear Discriminant Analysis (LDA) based on acoustic parameters of the vocalizations recorded. In addition, we applied an independent contrasts approach to investigate sociality in spotted paca following the social complexity hypothesis, independent of phylogeny. Our analysis showed that the spotted paca's acoustic repertoire contains seven vocal types and one mechanical signal. The broad acoustic repertoire of the spotted paca might have evolved given the species' ability to live in groups. The relationship between group size and the size of the acoustic repertoires of caviomorph species was confirmed, providing additional support for the SCHC in yet another group of diverse mammals

  12. Demography of Northern Spotted Owls in southwestern Oregon

    Science.gov (United States)

    Zabel, Cynthia J.; Salmons, Susan E.; Forsman, Eric D.; DeStefano, Stephen; Raphael, Martin G.; Gutierrez, R.J.

    1996-01-01

    Northern Spotted Owls (Strix occidentalis caurina) are associated with lower elevation, commercially valuable, late-successional coniferous forests in the Pacific Northwest. Meta-analyses of demographic parameters indicate that Northern Spotted Owl populations are declining throughout their range (Anderson and Burnham 1992, Burnham et al. this volume). Recent research has attempted to determine whether management activities have affected the viability of Spotted Owl populations, and results have led to development of conservation plans for the species (Dawson et al. 1987, Thomas et al. 1990, Murphy and Noon 1992, USDI 1992, Thomas et al. 1993b).In the Recovery Plan for the Northern Spotted Owl (USDI 1992b) threats to the species were identified as small population sizes, declining populations, limited amounts of habitat, continued loss and fragmentation of habitat, geographically isolated populations, and predation and competition from other avian species. Weather and fire are natural processes that also may affect reproductive success of Spotted Owls. Weather may be a factor in the high annual variability in fecundity of Spotted Owls, as has been suggested for other predatory bird species (Newton, 1979, 1986). However, these factors have not been addressed in previous studies of Spotted Owls.Our objectives were to estimate survival, fecundity, and annual rates of population change (l) for resident, territorial female Spotted Owls at two study areas in the coastal mountains of southwestern Oregon. We tested if the amount of rainfall was correlated with reproduction of Spotted Owls. While surveying for Spotted Owls, we documented the increased presence of Barred Owls (Strix varia), a potential competitor of Spotted Owls.

  13. Thermal Stress Analyses for an NLC Positron Target with a 3 mm Spot Radius Beam

    International Nuclear Information System (INIS)

    Stein, W.; Sunwoo, A.; Sheppard, J. C.; Bharadwaj, V.; Schultz, D.

    2002-01-01

    The power deposition of an incident electron beam in a tungsten-rhenium target and the resultant thermal shock stresses in the material have been modeled with a transient, dynamic, structural response finite element code. The Next Linear Collider electron beam is assumed split into three parts, with each part impinging on a 4 radiation lengths thick target. Three targets are required to avoid excessive thermal stresses in the targets. Energy deposition from each beam pulse occurs over 265 nanoseconds and results in heating of the target and pressure pulses straining the material. The rapid power deposition of the electron beam and the resultant temperature profile in the target generates stress and pressure waves in the material that are considerably larger than those calculated by a static analysis. The 6.22 GeV electron beam has a spot radius size of 3 mm and results in a maximum temperature jump of 147 C. Stress pressure pulses are induced in the material from the rapid thermal expansion of the hotter material with peak effective stresses reaching 83 ksi (5.77 x 10 8 Pa) on the back side of the target, which is less than one half of the yield strength of the tungsten/rhenium alloy and below the material fatigue limit

  14. The Spotting Distribution of Wildfires

    Directory of Open Access Journals (Sweden)

    Jonathan Martin

    2016-06-01

    Full Text Available In wildfire science, spotting refers to non-local creation of new fires, due to downwind ignition of brands launched from a primary fire. Spotting is often mentioned as being one of the most difficult problems for wildfire management, because of its unpredictable nature. Since spotting is a stochastic process, it makes sense to talk about a probability distribution for spotting, which we call the spotting distribution. Given a location ahead of the fire front, we would like to know how likely is it to observe a spot fire at that location in the next few minutes. The aim of this paper is to introduce a detailed procedure to find the spotting distribution. Most prior modelling has focused on the maximum spotting distance, or on physical subprocesses. We will use mathematical modelling, which is based on detailed physical processes, to derive a spotting distribution. We discuss the use and measurement of this spotting distribution in fire spread, fire management and fire breaching. The appendix of this paper contains a comprehensive review of the relevant underlying physical sub-processes of fire plumes, launching fire brands, wind transport, falling and terminal velocity, combustion during transport, and ignition upon landing.

  15. Effect of heating rate and grain size on the melting behavior of the alloy Nb-47 mass % Ti in pulse-heating experiments

    International Nuclear Information System (INIS)

    Basak, D.; Boettinger, W.J.; Josell, D.; Coriell, S.R.; McClure, J.L.; Cezairliyan, A.

    1999-01-01

    The effect of heating rate and grain size on the melting behavior of Nb-47 mass% Ti is measured and modeled. The experimental method uses rapid resistive self-heating of wire specimens at rates between ∼10 2 and ∼10 4 K/s and simultaneous measurement of radiance temperature and normal spectral emissivity as functions of time until specimen collapse, typically between 0.4 and 0.9 fraction melted. During heating, a sharp drop in emissivity is observed at a temperature that is independent of heating rate and grain size. This drop is due to surface and grain boundary melting at the alloy solidus temperature even though there is very little deflection (limited melting) of the temperature-time curve from the imposed heating rate. Above the solidus temperature, the emissivity remains nearly constant with increasing temperature and the temperature vs time curve gradually reaches a sloped plateau over which the major fraction of the specimen melts. As the heating rate and/or grain size is increased, the onset temperature of the sloped plateau approaches the alloy liquidus temperature and the slope of the plateau approaches zero. This interpretation of the shapes of the temperature-time-curves is supported by a model that includes diffusion in the solid coupled with a heat balance during the melting process. There is no evidence of loss of local equilibrium at the melt front during melting in these experiments

  16. Emerging hot spot analysis

    DEFF Research Database (Denmark)

    Reinau, Kristian Hegner

    Traditionally, focus in the transport field, both politically and scientifically, has been on private cars and public transport. Freight transport has been a neglected topic. Recent years has seen an increased focus upon congestion as a core issue across Europe, resulting in a great need for know...... speed data for freight. Secondly, the analytical methods used, space-time cubes and emerging hot spot analysis, are also new in the freight transport field. The analysis thus estimates precisely how fast freight moves on the roads in Northern Jutland and how this has evolved over time....

  17. Disruption effects on the beam size measurement

    Energy Technology Data Exchange (ETDEWEB)

    Raimondi, P.; Decker, F.J.; Chen, P.

    1995-06-01

    At the SLC Final Focus with higher currents and smaller beam sizes, the disruption parameter D{sub y} is close to one and so the pinch effect should produce a luminosity enhancement. Since a flat beam-beam function is fit to deflection scan data to measure the beam size, disruption can affect the measurement. Here the authors discuss the quantitative effects of disruption for typical SLC beam parameters. With 3.5 10{sup 10} particles per pulse, bunch length of 0.8 mm and beam sizes of 2.1 {mu}m horizontally and 0.55 {mu}m vertically, the measured vertical size can be as much as 25% bigger than the real one. Furthermore during the collision the spot size actually decrease, producing an enhancement factor H{sub D} of about 1.25. This would yield to a true luminosity which is 1.6 times that which is estimated from the beam-beam deflection fit.

  18. Submicron hollow spot generation by solid immersion lens and structured illumination

    NARCIS (Netherlands)

    Kim, M.S.; Assafrao, A.C.; Scharf, T.; Wachters, A.J.H.; Pereira, S.F.; Urbach, H.P.; Brun, M.; Olivier, S.; Nicoletti, S.; Herzig, H.P.

    2012-01-01

    We report on the experimental and numerical demonstration of immersed submicron-size hollow focused spots, generated by structuring the polarization state of an incident light beam impinging on a micro-size solid immersion lens (?-SIL) made of SiO2. Such structured focal spots are characterized by a

  19. Meteorology of Jupiter's Equatorial Hot Spots and Plumes from Cassini

    Science.gov (United States)

    Choi, David Sanghun; Showman, Adam P.; Vasavada, Ashwin R.; Simon-Miller, Amy A.

    2013-01-01

    We present an updated analysis of Jupiter's equatorial meteorology from Cassini observations. For two months preceding the spacecraft's closest approach, the Imaging Science Subsystem (ISS) onboard regularly imaged the atmosphere. We created time-lapse movies from this period in order to analyze the dynamics of equatorial hot spots and their interactions with adjacent latitudes. Hot spots are relatively cloud-free regions that emit strongly at 5 lm; improved knowledge of these features is crucial for fully understanding Galileo probe measurements taken during its descent through one. Hot spots are quasistable, rectangular dark areas on visible-wavelength images, with defined eastern edges that sharply contrast with surrounding clouds, but diffuse western edges serving as nebulous boundaries with adjacent equatorial plumes. Hot spots exhibit significant variations in size and shape over timescales of days and weeks. Some of these changes correspond with passing vortex systems from adjacent latitudes interacting with hot spots. Strong anticyclonic gyres present to the south and southeast of the dark areas appear to circulate into hot spots. Impressive, bright white plumes occupy spaces in between hot spots. Compact cirrus-like 'scooter' clouds flow rapidly through the plumes before disappearing within the dark areas. These clouds travel at 150-200 m/s, much faster than the 100 m/s hot spot and plume drift speed. This raises the possibility that the scooter clouds may be more illustrative of the actual jet stream speed at these latitudes. Most previously published zonal wind profiles represent the drift speed of the hot spots at their latitude from pattern matching of the entire longitudinal image strip. If a downward branch of an equatorially-trapped Rossby wave controls the overall appearance of hot spots, however, the westward phase velocity of the wave leads to underestimates of the true jet stream speed.

  20. RF-source development for ITER: Large area H- beam extraction, modifications for long pulse operation and design of a half size ITER source

    International Nuclear Information System (INIS)

    Kraus, W.; Heinemann, B.; Falter, H.D.; Franzen, P.; Speth, E.; Entscheva, A.; Fantz, U.; Franke, T.; Holtum, D.; Martens, Ch.; McNeely, P.; Riedl, R.; Wilhelm, R.

    2005-01-01

    With an extraction area of 152 cm 2 a calorimetrically measured H - current density of 19.3 mA/cm 2 has been achieved at 0.45 Pa with 90 kW RF power. With 306 cm 2 the electrically measured H - current has reached up to 9.7 A corresponding to 32 mA/cm 2 at 100 kW. The current on the calorimeter is limited by the extraction system. Down to 0.2 Pa only a weak dependence on the source pressure has been observed. The test bed will be upgraded to demonstrate cw operation with deuterium. Based on the tested prototype a half size ITER RF-source of 80 cm x 90 cm with 360 kW RF power has been designed

  1. Technical Note: Spot characteristic stability for proton pencil beam scanning

    International Nuclear Information System (INIS)

    Chen, Chin-Cheng; Chang, Chang; Mah, Dennis; Moyers, Michael F.; Gao, Mingcheng

    2016-01-01

    Purpose: The spot characteristics for proton pencil beam scanning (PBS) were measured and analyzed over a 16 month period, which included one major site configuration update and six cyclotron interventions. The results provide a reference to establish the quality assurance (QA) frequency and tolerance for proton pencil beam scanning. Methods: A simple treatment plan was generated to produce an asymmetric 9-spot pattern distributed throughout a field of 16 × 18 cm for each of 18 proton energies (100.0–226.0 MeV). The delivered fluence distribution in air was measured using a phosphor screen based CCD camera at three planes perpendicular to the beam line axis (x-ray imaging isocenter and up/down stream 15.0 cm). The measured fluence distributions for each energy were analyzed using in-house programs which calculated the spot sizes and positional deviations of the Gaussian shaped spots. Results: Compared to the spot characteristic data installed into the treatment planning system, the 16-month averaged deviations of the measured spot sizes at the isocenter plane were 2.30% and 1.38% in the IEC gantry x and y directions, respectively. The maximum deviation was 12.87% while the minimum deviation was 0.003%, both at the upstream plane. After the collinearity of the proton and x-ray imaging system isocenters was optimized, the positional deviations of the spots were all within 1.5 mm for all three planes. During the site configuration update, spot positions were found to deviate by 6 mm until the tuning parameters file was properly restored. Conclusions: For this beam delivery system, it is recommended to perform a spot size and position check at least monthly and any time after a database update or cyclotron intervention occurs. A spot size deviation tolerance of <15% can be easily met with this delivery system. Deviations of spot positions were <2 mm at any plane up/down stream 15 cm from the isocenter

  2. Technical Note: Spot characteristic stability for proton pencil beam scanning

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chin-Cheng, E-mail: chen.ccc@gmail.com; Chang, Chang; Mah, Dennis [ProCure Treatment Center, Somerset, New Jersey 08873 (United States); Moyers, Michael F. [ProCure Treatment Center, Somerset, New Jersey 08873 and Shanghai Proton and Heavy Ion Center, Shanghai 201321 (China); Gao, Mingcheng [CDH Proton Center, Warrenville, Illinois 60555 (United States)

    2016-02-15

    Purpose: The spot characteristics for proton pencil beam scanning (PBS) were measured and analyzed over a 16 month period, which included one major site configuration update and six cyclotron interventions. The results provide a reference to establish the quality assurance (QA) frequency and tolerance for proton pencil beam scanning. Methods: A simple treatment plan was generated to produce an asymmetric 9-spot pattern distributed throughout a field of 16 × 18 cm for each of 18 proton energies (100.0–226.0 MeV). The delivered fluence distribution in air was measured using a phosphor screen based CCD camera at three planes perpendicular to the beam line axis (x-ray imaging isocenter and up/down stream 15.0 cm). The measured fluence distributions for each energy were analyzed using in-house programs which calculated the spot sizes and positional deviations of the Gaussian shaped spots. Results: Compared to the spot characteristic data installed into the treatment planning system, the 16-month averaged deviations of the measured spot sizes at the isocenter plane were 2.30% and 1.38% in the IEC gantry x and y directions, respectively. The maximum deviation was 12.87% while the minimum deviation was 0.003%, both at the upstream plane. After the collinearity of the proton and x-ray imaging system isocenters was optimized, the positional deviations of the spots were all within 1.5 mm for all three planes. During the site configuration update, spot positions were found to deviate by 6 mm until the tuning parameters file was properly restored. Conclusions: For this beam delivery system, it is recommended to perform a spot size and position check at least monthly and any time after a database update or cyclotron intervention occurs. A spot size deviation tolerance of <15% can be easily met with this delivery system. Deviations of spot positions were <2 mm at any plane up/down stream 15 cm from the isocenter.

  3. Laser spot welding of cobalt-based amorphous metal foils

    International Nuclear Information System (INIS)

    Runchev, Dobre; Dorn, Lutc; Jaferi, Seifolah; Purbst, Detler

    1997-01-01

    The results concerning weldability of amorphous alloy (VAC 6025F) in shape of foils and the quality of laser-spot welded joints are presented in this paper. The aim of the research was the production of a high quality welding joint, by preserving the amorphous structure. The quality of the joint was tested by shear strength analysis and microhardness measuring. The metallographic studies were made by using optical microscope and SEM. The results show that (1) overlapped Co based amorphous metals foils can be welded with high-quality by a pulsed Nd: YAG-Laser, but only within a very narrow laser parameter window; (2) the laser welded spots show comparably high strength as the basic material; (3) the structure of the welded spot remains amorphous, so that the same characteristics as the base material can be achieved. (author)

  4. Experimental and simulated strength of spot welds

    DEFF Research Database (Denmark)

    Nielsen, Chris Valentin; Bennedbæk, Rune A.K.; Larsen, Morten B.

    2014-01-01

    Weld strength testing of single spots in DP600 steel is presented for the three typical testing procedures, i.e. tensile-shear, cross-tension and peel testing. Spot welds are performed at two sets of welding parameters and strength testing under these conditions is presented by load......-elongation curves revealing the maximum load and the elongation at break. Welding and strength testing is simulated by SORPAS® 3D, which allows the two processes to be prepared in a combined simulation, such that the simulated welding properties are naturally applied to the simulation of strength testing. Besides...... the size and shape of the weld nugget, these properties include the new strength of the material in the weld and the heat affected zone based on the predicted hardness resulting from microstructural phase changes simulated during cooling of the weld before strength testing. Comparisons between overall...

  5. Effect of laser beam parameters on magnetic properties of Nd-Fe-B thick-film magnets fabricated by pulsed laser deposition

    International Nuclear Information System (INIS)

    Fukunaga, H.; Nakano, M.; Yanai, T.; Kamikawatoko, T.; Yamashita, F.

    2011-01-01

    The effects of varying the laser power and the spot diameter of a laser beam on the magnetic properties, morphology, and deposition rate of Nd-Fe-B thick-film magnets fabricated by pulsed laser deposition (PLD) were investigated. Reducing the laser fluence on the target reduces the remanence and increases the Nd content and consequently the coercivity of the prepared films. The spot size of the laser beam was found to affect the film surface morphology, the deposition rate, and the reproducibility of the magnetic properties of the prepared films. Reducing the spot size reduces the number of droplets and the reproducibility of the magnetic properties and increases the droplet size. Controlling the spot size of the laser beam enabled us to maximize the deposition rate. Consequently, a coercivity of 1210 kA/m and a remanence of 0.51 T were obtained at a deposition rate of 11.8 μm/(h·W). This deposition rate is 30% greater than the highest previously reported deposition rate by PLD.

  6. Models of spots and flares

    International Nuclear Information System (INIS)

    Mullan, D.J.

    1983-01-01

    Laboratory experiments in recent years have shown that there are many more ways to drive a plasma out of equilibrium than to preserve equilibrium. In that sense, it is perhaps easier to understand why flares should occur in a stellar atmosphere than why a long-lived feature such as a dark spot should persist. The author summarizes work on the equilibrium structure of cool spots in the sun and stars. Since spots involve complex interactions between convective flows and magnetic fields, he needs to refer to observations for help in identifying the dominant processes which should enter into the modelling. His summary therefore begins by discussing certain relevant properties of spots in the solar atmosphere. The next sections deal with the magnetic fields in spots, the stability of spots, spot cooling and missing flux. The author concludes that spots should be viewed not simply as cool areas, but rather as engines which do the work of converting the energy of convective flows into flare-compatible form. (Auth.)

  7. Black-spot poison ivy.

    Science.gov (United States)

    Schram, Sarah E; Willey, Andrea; Lee, Peter K; Bohjanen, Kimberly A; Warshaw, Erin M

    2008-01-01

    In black-spot poison ivy dermatitis, a black lacquerlike substance forms on the skin when poison ivy resin is exposed to air. Although the Toxicodendron group of plants is estimated to be the most common cause of allergic contact dermatitis in the United States, black-spot poison ivy dermatitis is relatively rare.

  8. Rocky Mountain spotted fever, Colombia.

    Science.gov (United States)

    Hidalgo, Marylin; Orejuela, Leonora; Fuya, Patricia; Carrillo, Pilar; Hernandez, Jorge; Parra, Edgar; Keng, Colette; Small, Melissa; Olano, Juan P; Bouyer, Donald; Castaneda, Elizabeth; Walker, David; Valbuena, Gustavo

    2007-07-01

    We investigated 2 fatal cases of Rocky Mountain spotted fever that occurred in 2003 and 2004 near the same locality in Colombia where the disease was first reported in the 1930s. A retrospective serosurvey of febrile patients showed that > 21% of the serum samples had antibodies aaainst spotted fever group rickettsiae.

  9. Advances in spot curing technology

    International Nuclear Information System (INIS)

    Burga, R.

    1999-01-01

    A brief review of spot curing technology was presented. The process which a spot of energy of a specific wavelength bandwidth and irradiance is used to cause a coating, encapsulant or adhesive to change from a liquid to a solid state

  10. Short intense ion pulses for materials and warm dense matter research

    Energy Technology Data Exchange (ETDEWEB)

    Seidl, Peter A., E-mail: PASeidl@lbl.gov [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Persaud, Arun; Waldron, William L. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Barnard, John J. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Davidson, Ronald C. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Friedman, Alex [Lawrence Livermore National Laboratory, Livermore, CA (United States); Gilson, Erik P. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Greenway, Wayne G. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Grote, David P. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Kaganovich, Igor D. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Lidia, Steven M.; Stettler, Matthew; Takakuwa, Jeffrey H.; Schenkel, Thomas [Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

    2015-11-11

    We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment-II at Lawrence Berkeley National Laboratory, by generating beam spots size with radius r<1 mm within 2 ns FWHM and approximately 10{sup 10} ions/pulse. To enable the short pulse durations and mm-scale focal spot radii, the 1.2 MeV Li{sup +} ion beam is neutralized in a 1.6-meter drift compression section located after the last accelerator magnet. An 8-Tesla short focal length solenoid compresses the beam in the presence of the large volume plasma near the end of this section before the target. The scientific topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including selected topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Here we describe the accelerator commissioning and time-resolved ionoluminescence measurements of yttrium aluminum perovskite using the fully integrated accelerator and neutralized drift compression components.

  11. Short intense ion pulses for materials and warm dense matter research

    International Nuclear Information System (INIS)

    Seidl, Peter A.; Persaud, Arun; Waldron, William L.; Barnard, John J.; Davidson, Ronald C.; Friedman, Alex; Gilson, Erik P.; Greenway, Wayne G.; Grote, David P.; Kaganovich, Igor D.; Lidia, Steven M.; Stettler, Matthew; Takakuwa, Jeffrey H.; Schenkel, Thomas

    2015-01-01

    We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment-II at Lawrence Berkeley National Laboratory, by generating beam spots size with radius r<1 mm within 2 ns FWHM and approximately 10"1"0 ions/pulse. To enable the short pulse durations and mm-scale focal spot radii, the 1.2 MeV Li"+ ion beam is neutralized in a 1.6-meter drift compression section located after the last accelerator magnet. An 8-Tesla short focal length solenoid compresses the beam in the presence of the large volume plasma near the end of this section before the target. The scientific topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including selected topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Here we describe the accelerator commissioning and time-resolved ionoluminescence measurements of yttrium aluminum perovskite using the fully integrated accelerator and neutralized drift compression components.

  12. Development of the pulse transformer for NLC klystron pulse modulator

    International Nuclear Information System (INIS)

    Akemoto, M.; Gold, S.; Koontz, R.; Krasnykh, A.

    1997-05-01

    We have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a rise time of 250ns and pulse droop of 3.6% has been designed and built. The transmission characteristics and pulse time-response were measured. The data were compared with the model. The agreement with the model was good when the measured values were used in the model simulation. The results of the high voltage tests are also presented

  13. Pulse transformer R and D for NLC klystron pulse modulator

    International Nuclear Information System (INIS)

    Akemoto, M.; Gold, S.; Krasnykh, A.; Koontz, R.

    1997-07-01

    The authors have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and requires a larger core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a rise time of 250ns and a pulse droop of 3.6% has been designed and built. The transmission characteristics and pulse time-response were measured. The data were compared with the model. The agreement with the model was good when the measured values were used in the model simulation. The results of the high voltage tests using a klystron load are also presented

  14. Analysis and validation of laser spot weld-induced distortion

    Energy Technology Data Exchange (ETDEWEB)

    Knorovsky, G.A.; Kanouff, M.P.; Maccallum, D.O.; Fuerschbach, P.W.

    1999-12-09

    Laser spot welding is an ideal process for joining small parts with tight tolerances on weld size, location, and distortion, particularly those with near-by heat sensitive features. It is also key to understanding the overlapping laser spot seam welding process. Rather than attempting to simulate the laser beam-to-part coupling (particularly if a keyhole occurs), it was measured by calorimetry. This data was then used to calculate the thermal and structural response of a laser spot welded SS304 disk using the finite element method. Five combinations of process parameter values were studied. Calculations were compared to experimental data for temperature and distortion profiles measured by thermocouples and surface profiling. Results are discussed in terms of experimental and modeling factors. The authors then suggest appropriate parameters for laser spot welding.

  15. Laser reflection spot as a pattern in a diamond coating – a microscopic study

    Directory of Open Access Journals (Sweden)

    GORDANA S. RISTIĆ

    2009-07-01

    Full Text Available Diamond coatings were deposited by the synchronous and coupled action of a hot filament CVD method and a pulsed CO2 laser in spectro-absorbing and spectro-non-absorbing diamond precursor atmospheres. The obtained coatings were structured/patterned, i.e., they were comprised of uncovered, bare locations. An extra effect observed only in the spectro-active diamond precursor atmosphere was the creation of another laser spot in the coating – a reflection spot. In order to establish the practical usability of the latter one, extensive microscopic investigations were performed with consideration of the morphology changes in the spot of the direct laser beam. Normal incidence SEM images of this spot showed a smooth surface, without any pulse radiation damage. AFM imaging revealed the actual surface condition and gave precise data on the surface characteristics.

  16. Complete mitochondrial genome of the red-spotted tokay gecko (Gekko gecko, Reptilia: Gekkonidae): comparison of red- and black-spotted tokay geckos.

    Science.gov (United States)

    Qin, Xin-Min; Qian, Fang; Zeng, De-Long; Liu, Xiao-Can; Li, Hui-Min

    2011-10-01

    Here, we sequenced the complete mitochondrial genome of the red-spotted tokay gecko (Squamata: Gekkonidae). The genome is 16,590 bp in size. Its gene arrangement pattern was identical with that of black-spotted tokay gecko. We compared the mitochondrial genome of red-spotted tokay gecko with that of the black-spotted tokay gecko. Nucleotide sequence of the two whole mitochondrial genomes was 97.99% similar, and the relatively high similarity seems to indicate that they may be separated at the subspecies level. The information of mitochondrial genome comparison of the two morphological types of tokay gecko is discussed in detail.

  17. Pulsed lower-hybrid wave penetration in reactor plasmas

    International Nuclear Information System (INIS)

    Cohen, R.H.; Bonoli, P.T.; Porkolab, M.; Rognlien, T.D.

    1989-01-01

    Providing lower-hybrid power in short, intense (GW) pulses allows enhanced wave penetration in reactor-grade plasmas. We examine nonlinear absorption, ray propagation, and parametric instability of the intense pulses. We find that simultaneously achieving good penetration while avoiding parametric instabilities is possible, but imposes restrictions on the peak power density, pulse duration, and/or r.f. spot shape. In particular, power launched in narrow strips, elongated along the field direction, is desired

  18. Pulsed dye laser application in ablation of vascular ectasias of the larynx: a preliminary animal study

    Science.gov (United States)

    Woo, Peak; Wang, Zhi; Perrault, Donald F., Jr.; McMillan, Kathleen; Pankratov, Michail M.

    1995-05-01

    Vascular ectasias (dilatation) and vascular lesions of the larynx are difficult to treat with exciting modalities. Varix (enlarged vessel) of the vocal folds, vocal fold hemorrhage, vascular polyp, hemangioma, intubation or contact granuloma are common problems which disturb voice. Current applications of CO2 laser and cautery often damage the delicate vocal fold cover. The 585 nm dermatologic pulsed dye laser may be an ideal substitute. Two adult canines were examined under anesthesia via microlaryngoscopy technique. Pulsed dye laser (SPTL-1a, Candela Laser Corp., Wayland, MA) energy was delivered via the micromanipulator with the 3.1-mm spot size in single pulses of 6, 8, and 10 Joules/cm2 and applied to the vessels of the vocal folds, epiglottis, and arytenoid cartilage. Endoscopic examination was carried out immediately after the treatment and at 4 weeks postoperatively. The animals were sacrificed at 3 weeks, larynges excised, and whole organ laryngeal section were prepared for histology. Pulsed dye laser thrombosed vessels of the vocal fold using 6 or 8 Joules/cm2. Vascular break and leakage occurred at 10 Joules/cm2. Follow up examination showed excellent vessel obliteration or thrombosis without scarring or injury to the overlying tissues. Histologic examination shows vascular thrombosis without inflammation and fibrosis in the vocal fold cover. Pulsed dye laser may have promise in treatment of vascular lesions of the larynx and upper airway.

  19. Spotting psychopaths using technology.

    Science.gov (United States)

    Hulbert, Sarah; Adeli, Hojjat

    2015-01-01

    For the past three and a half decades, the Psychopathy Checklist-Revised (PCL-R) and the self-report Psychopathic Personality Inventory-Revised (PPI-R) have been the standard measures for the diagnosis of psychopathy. Technological approaches can enhance these diagnostic methodologies. The purpose of this paper is to present a state-of-the-art review of various technological approaches for spotting psychopathy, such as electroencephalogram (EEG), magnetic resonance imaging (MRI), functional MRI (fMRI), transcranial magnetic stimulation (TMS), and other measures. Results of EEG event-related potential (ERP) experiments support the theory that impaired amygdala function may be responsible for abnormal fear processing in psychopathy, which can ultimately manifest as psychopathic traits, as outlined by the PCL-R or PPI-R. Imaging studies, in general, point to reduced fear processing capabilities in psychopathic individuals. While the human element, introduced through researcher/participant interactions, can be argued as unequivocally necessary for diagnosis, these purely objective technological approaches have proven to be useful in conjunction with the subjective interviewing and questionnaire methods for differentiating psychopaths from non-psychopaths. Furthermore, these technologies are more robust than behavioral measures, which have been shown to fail.

  20. Spot Welding of Honeycomb Structures

    Science.gov (United States)

    Cohal, V.

    2017-08-01

    Honeycomb structures are used to prepare meals water jet cutting machines for textile. These honeycomb structures are made of stainless steel sheet thickness of 0.1-0.2 mm. Corrugated sheet metal strips are between two gears with special tooth profile. Hexagonal cells for obtaining these strips are welded points between them. Spot welding device is three electrodes in the upper part, which carries three welding points across the width of the strip of corrugated sheet metal. Spot welding device filled with press and advance mechanisms. The paper presents the values of the regime for spot welding.

  1. On cold spots in tumor subvolumes

    International Nuclear Information System (INIS)

    Tome, Wolfgang A.; Fowler, Jack F.

    2002-01-01

    Losses in tumor control are estimated for cold spots of various 'sizes' and degrees of 'cold dose'. This question is important in the context of intensity modulated radiotherapy where differential dose-volume histograms (DVHs) for targets that abut a critical structure often exhibit a cold dose tail. This can be detrimental to tumor control probability (TCP) for fractions of cold volumes even as small as 1%, if the cold dose is lower than the prescribed dose by substantially more than 10%. The Niemierko-Goitein linear-quadratic algorithm with γ 50 slope 1-3 was used to study the effect of cold spots of various degrees (dose deficit below the prescription dose) and size (fractional volume of the cold dose). A two-bin model DVH has been constructed in which the cold dose bin is allowed to vary from a dose deficit of 1%-50% below prescription dose and to have volumes varying from 1% to 90%. In order to study and quantify the effect of a small volume of cold dose on TCP and effective uniform dose (EUD), a four-bin DVH model has been constructed in which the lowest dose bin, which has a fractional volume of 1%, is allowed to vary from 10% to 45% dose deficit below prescription dose. The highest dose bin represents a simultaneous boost. For fixed size of the cold spot the calculated values of TCP decreased rapidly with increasing degrees of cold dose for any size of the cold spot, even as small as 1% fractional volume. For the four-subvolume model, in which the highest dose bin has a fractional volume of 80% and is set at a boost dose of 10% above prescription dose, it is found that the loss in TCP and EUD is moderate as long as the cold 1% subvolume has a deficit less than approximately 20%. However, as the dose deficit in the 1% subvolume bin increases further it drives TCP and EUD rapidly down and can lead to a serious loss in TCP and EUD. Since a dose deficit to a 1% volume of the target that is larger than 20% of the prescription dose may lead to serious loss of

  2. Electron acceleration by a radially polarized laser pulse during ionization of low density gases

    Directory of Open Access Journals (Sweden)

    Kunwar Pal Singh

    2011-03-01

    Full Text Available The acceleration of electrons by a radially polarized intense laser pulse has been studied. The axial electric field of the laser is responsible for electron acceleration. The axial electric field increases with decreasing laser spot size; however, the laser pulse gets defocused sooner for smaller values and the electrons do not experience high electric field for long, reducing the energy they can reach. The electron remains confined in the electric field of the laser for longer and the electron energy peaks for the normalized laser spot size nearly equal to the normalized laser intensity parameter. Electron energy peaks for initial laser phase ϕ_{0}=π due to accelerating laser phase and decreases with transverse initial position of the electrons. The energy and angle of the emittance spectrum of the electrons generated during ionization of krypton and argon at low densities have been obtained and a right choice of laser parameters has been suggested to obtain high energy quasimonoenergetic collimated electron beams. It has been found that argon is more suitable than krypton to obtain high energy electron beams due to higher ionization potential of inner shells for the former.

  3. Verification of the anatomy and newly discovered histology of the G-spot complex.

    Science.gov (United States)

    Ostrzenski, A; Krajewski, P; Ganjei-Azar, P; Wasiutynski, A J; Scheinberg, M N; Tarka, S; Fudalej, M

    2014-10-01

    To expand the anatomical investigations of the G-spot and to assess the G-spot's characteristic histological and immunohistochemical features. An observational study. International multicentre. Eight consecutive fresh human female cadavers. Anterior vaginal wall dissections were executed and G-spot microdissections were performed. All specimens were stained with haematoxylin and eosin (H&E). The tissues of two women were selected at random for immunohistochemical staining. The primary outcome measure was to document the anatomy of the G-spot. The secondary outcome measures were to identify the histology of the G-spot and to determine whether histological samples stained with H&E are sufficient to identify the G-spot. The anatomical existence of the G-spot was identified in all women and was in a diagonal plane. In seven (87.5%) and one (12.5%) of the women the G-spot complex was found on the left or right side, respectively. The G-spot was intimately fused with vessels, creating a complex. A large tangled vein-like vascular structure resembled an arteriovenous malformation and there were a few smaller feeding arteries. A band-like structure protruded from the tail of the G-spot. The size of the G-spot varied. Histologically, the G-spot was determined as a neurovascular complex structure. The neural component contained abundant peripheral nerve bundles and a nerve ganglion. The vascular component comprised large vein-like vessels and smaller feeding arteries. Circular and longitudinal muscles covered the G-complex. The anatomy of the G-spot complex was confirmed. The histology of the G-spot presents as neurovascular tissues with a nerve ganglion. H&E staining is sufficient for the identification of the G-spot complex. © 2014 Royal College of Obstetricians and Gynaecologists.

  4. Laser induced single spot oxidation of titanium

    Energy Technology Data Exchange (ETDEWEB)

    Jwad, Tahseen, E-mail: taj355@bham.ac.uk; Deng, Sunan; Butt, Haider; Dimov, S.

    2016-11-30

    Highlights: • A new high resolution laser induced oxidation (colouring) method is proposed (single spot oxidation). • The method is applied to control oxide films thicknesses and hence colours on titanium substrates in micro-scale. • The method enable imprinting high resolution coloured image on Ti substrate. • Optical and morphological periodic surface structures are also produced by an array of oxide spots using the proposed method. • Colour coding of two colours into one field is presented. - Abstract: Titanium oxides have a wide range of applications in industry, and they can be formed on pure titanium using different methods. Laser-induced oxidation is one of the most reliable methods due to its controllability and selectivity. Colour marking is one of the main applications of the oxidation process. However, the colourizing process based on laser scanning strategies is limited by the relative large processing area in comparison to the beam size. Single spot oxidation of titanium substrates is proposed in this research in order to increase the resolution of the processed area and also to address the requirements of potential new applications. The method is applied to produce oxide films with different thicknesses and hence colours on titanium substrates. High resolution colour image is imprinted on a sheet of pure titanium by converting its pixels’ colours into laser parameter settings. Optical and morphological periodic surface structures are also produced by an array of oxide spots and then analysed. Two colours have been coded into one field and the dependencies of the reflected colours on incident and azimuthal angles of the light are discussed. The findings are of interest to a range of application areas, as they can be used to imprint optical devices such as diffusers and Fresnel lenses on metallic surfaces as well as for colour marking.

  5. Laser induced single spot oxidation of titanium

    International Nuclear Information System (INIS)

    Jwad, Tahseen; Deng, Sunan; Butt, Haider; Dimov, S.

    2016-01-01

    Highlights: • A new high resolution laser induced oxidation (colouring) method is proposed (single spot oxidation). • The method is applied to control oxide films thicknesses and hence colours on titanium substrates in micro-scale. • The method enable imprinting high resolution coloured image on Ti substrate. • Optical and morphological periodic surface structures are also produced by an array of oxide spots using the proposed method. • Colour coding of two colours into one field is presented. - Abstract: Titanium oxides have a wide range of applications in industry, and they can be formed on pure titanium using different methods. Laser-induced oxidation is one of the most reliable methods due to its controllability and selectivity. Colour marking is one of the main applications of the oxidation process. However, the colourizing process based on laser scanning strategies is limited by the relative large processing area in comparison to the beam size. Single spot oxidation of titanium substrates is proposed in this research in order to increase the resolution of the processed area and also to address the requirements of potential new applications. The method is applied to produce oxide films with different thicknesses and hence colours on titanium substrates. High resolution colour image is imprinted on a sheet of pure titanium by converting its pixels’ colours into laser parameter settings. Optical and morphological periodic surface structures are also produced by an array of oxide spots and then analysed. Two colours have been coded into one field and the dependencies of the reflected colours on incident and azimuthal angles of the light are discussed. The findings are of interest to a range of application areas, as they can be used to imprint optical devices such as diffusers and Fresnel lenses on metallic surfaces as well as for colour marking.

  6. Influence of repetitive pulsed laser irradiation on the surface characteristics of an aluminum alloy in the melting regime

    International Nuclear Information System (INIS)

    Choi, Sung Ho; Jhang, Kyung Young

    2015-01-01

    We have investigated the influence of repetitive near-infrared (NIR) pulsed laser shots in the melting regime on the surface characteristics of an aluminum 6061-T6 alloy. Characteristics of interest include surface morphology, surface roughness, and surface hardness in the melted zone as well as the size of the melted zone. For this study, the proper pulse energy for inducing surface melting at one shot is selected using numerical simulations that calculate the variation in temperature at the laser beam spot for various input pulse energies in order to find the proper pulse energy for raising the temperature to the melting point. In this study, 130 mJ was selected as the input energy for a Nd:YAG laser pulse with a duration of 5 ns. The size of the melted zone measured using optical microscopy (OM) increased logarithmically with an increasing shot number. The surface morphology observed by scanning electron microscopy (SEM) clearly showed a re-solidified microstructure evolution after surface melting. The surface roughness and hardness were measured by atomic force microscopy (AFM) and nano-indentation, respectively. The surface roughness showed almost no variation due to the surface texturing after laser shots over 10. The hardness inside the melted zone was lower than that outside the zone because the β'' phase was transformed to a β phase or dissolved into a matrix.

  7. The flip-over effect in pulsed laser deposition: Is it relevant at high background gas pressures?

    International Nuclear Information System (INIS)

    Ojeda-G-P, Alejandro; Schneider, Christof W.; Döbeli, Max; Lippert, Thomas; Wokaun, Alexander

    2015-01-01

    Highlights: • The flip-over effect in PLD is observed up to high deposition pressures. • Consistent congruent transfer of the target composition is generally not correct. • The choice of deposition pressure can change the film composition strongly. • Large compositional changes appear at high off-axis angles and large spot sizes. - Abstract: In pulsed laser deposition the use of a rectangular or elliptical beam spot with a non 1:1 aspect ratio leads to the so called flip-over effect. Here, the longest dimension of the laser spot results in the shortest direction of plasma plume expansion. This effect has been mainly reported for vacuum depositions of single element targets and is particularly noticeable when the aspect ratio of the beam spot is large. We investigate the flip-over effect in vacuum and at three relevant background-gas pressures for pulsed laser deposition using a La 0.4 Ca 0.6 MnO 3 target by measuring the thickness dependence of the deposited material as a function of angle. The film thicknesses and compositions are determined by Rutherford backscattering and argon is used to reduce the influence of additional chemical reactions in the plasma. The results show the prevalence of the flip-over effect for all pressures except for the highest, i.e. 1 × 10 −1 mbar, where the film thickness is constant for all angles. The composition profiles show noticeable compositional variations of up to 30% with respect to the target material depending on the background gas pressure, the angular location, and the laser spot dimensions.

  8. The flip-over effect in pulsed laser deposition: Is it relevant at high background gas pressures?

    Energy Technology Data Exchange (ETDEWEB)

    Ojeda-G-P, Alejandro [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland); Schneider, Christof W., E-mail: christof.schneider@psi.ch [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland); Döbeli, Max [Ion Beam Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Lippert, Thomas; Wokaun, Alexander [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland)

    2015-12-01

    Highlights: • The flip-over effect in PLD is observed up to high deposition pressures. • Consistent congruent transfer of the target composition is generally not correct. • The choice of deposition pressure can change the film composition strongly. • Large compositional changes appear at high off-axis angles and large spot sizes. - Abstract: In pulsed laser deposition the use of a rectangular or elliptical beam spot with a non 1:1 aspect ratio leads to the so called flip-over effect. Here, the longest dimension of the laser spot results in the shortest direction of plasma plume expansion. This effect has been mainly reported for vacuum depositions of single element targets and is particularly noticeable when the aspect ratio of the beam spot is large. We investigate the flip-over effect in vacuum and at three relevant background-gas pressures for pulsed laser deposition using a La{sub 0.4}Ca{sub 0.6}MnO{sub 3} target by measuring the thickness dependence of the deposited material as a function of angle. The film thicknesses and compositions are determined by Rutherford backscattering and argon is used to reduce the influence of additional chemical reactions in the plasma. The results show the prevalence of the flip-over effect for all pressures except for the highest, i.e. 1 × 10{sup −1} mbar, where the film thickness is constant for all angles. The composition profiles show noticeable compositional variations of up to 30% with respect to the target material depending on the background gas pressure, the angular location, and the laser spot dimensions.

  9. In situ investigation of formation of self-assembled nanodomain structure in lithium niobate after pulse laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shur, V. Ya.; Kuznetsov, D. K.; Mingaliev, E. A.; Yakunina, E. M.; Lobov, A. I.; Ievlev, A. V. [Ferroelectric Laboratory, Institute of Physics and Applied Mathematics, Ural State University, Lenin Ave. 51, Ekaterinburg 620083 (Russian Federation)

    2011-08-22

    The evolution of the self-assembled quasi-regular micro- and nanodomain structures after pulse infrared laser irradiation was studied by in situ optical observation. The average periods of the structures are much less than the sizes of the laser spots. The polarization reversal occurs through covering of the whole irradiated area by the nets of the spatially separated nanodomain chains and microdomain rays--''hatching effect.'' The main stages of the anisotropic nanodomain kinetics: nucleation, growth, and branching, have been singled out. The observed abnormal domain kinetics was attributed to the action of the pyroelectric field arising during cooling after laser heating.

  10. Using a tungsten rollbar to characterize the source spot of a megavoltage bremsstrahlung linac

    International Nuclear Information System (INIS)

    Schach von Wittenau, A.E.; Logan, C.M.; Rikard, R.

    2002-01-01

    In photon teletherapy, the size and functional form of the photon source spot affect both the sharpness of the penumbra of treatment fields and the sharpness of portal images. Photon source spot parameters are also used in photon teletherapy dose calculation codes. A simple method for characterizing the source spot would complement the existing, more involved methods that have been described in the medical physics literature. Such a method, using a rollbar made of tungsten or other high-Z metal, is used in industrial radiography. We describe the use of a tungsten rollbar for characterizing the source spot edge spread function (and thereby the source spot size and shape) of a megavoltage bremsstrahlung photon source. We use Monte Carlo simulations to quantify anticipated experimental artifacts of the method, assuming typical spot sizes for circ-function, Gaussian, and Bennett line shapes. We illustrate the use of the rollbar method by characterizing the source spot of a typical 9 MV linac used for industrial radiography. The source spot is analyzed using two approaches: (a) fitting the rollbar image with analytic functions and (b) using Abel inversion to obtain the cylindrically symmetric spot profile consistent with the measured rollbar image. Monte Carlo simulations, based on a 6 MV photon teletherapy accelerator, suggest that aspects of the method are applicable to medical bremsstrahlung sources

  11. Simulation of the Focal Spot of the Accelerator Bremsstrahlung Radiation

    Science.gov (United States)

    Sorokin, V.; Bespalov, V.

    2016-06-01

    Testing of thick-walled objects by bremsstrahlung radiation (BR) is primarily performed via high-energy quanta. The testing parameters are specified by the focal spot size of the high-energy bremsstrahlung radiation. In determining the focal spot size, the high- energy BR portion cannot be experimentally separated from the low-energy BR to use high- energy quanta only. The patterns of BR focal spot formation have been investigated via statistical modeling of the radiation transfer in the target material. The distributions of BR quanta emitted by the target for different energies and emission angles under normal distribution of the accelerated electrons bombarding the target have been obtained, and the ratio of the distribution parameters has been determined.

  12. Measuring a narrow Bessel beam spot by scanning a charge-coupled device (CCD) pixel

    International Nuclear Information System (INIS)

    Tiwari, S K; Ram, S P; Jayabalan, J; Mishra, S R

    2010-01-01

    By scanning a charge-coupled device (CCD) camera transverse to the beam axis and observing the variation in counts on a marked pixel, we demonstrate that we can measure a laser beam spot size smaller than the size of the CCD-pixel. We find this method particularly attractive for measuring the size of central spot of a Bessel beam, for which the established scanning knife-edge method does not work appropriately because of the large contribution of the rings surrounding the central spot to the signal

  13. Dried blood spots as a source of anti-malarial antibodies for epidemiological studies

    Science.gov (United States)

    Corran, Patrick H; Cook, Jackie; Lynch, Caroline; Leendertse, Heleen; Manjurano, Alphaxard; Griffin, Jamie; Cox, Jonathan; Abeku, Tarekegn; Bousema, Teun; Ghani, Azra C; Drakeley, Chris; Riley, Eleanor

    2008-01-01

    Background Blood spots collected onto filter paper are an established and convenient source of antibodies for serological diagnosis and epidemiological surveys. Although recommendations for the storage and analysis of small molecule analytes in blood spots exist, there are no published systematic studies of the stability of antibodies under different storage conditions. Methods Blood spots, on filter paper or glass fibre mats and containing malaria-endemic plasma, were desiccated and stored at various temperatures for different times. Eluates of these spots were assayed for antibodies against two Plasmodium falciparum antigens, MSP-119 and MSP2, and calculated titres used to fit an exponential (first order kinetic) decay model. The first order rate constants (k) for each spot storage temperature were used to fit an Arrhenius equation, in order to estimate the thermal and temporal stability of antibodies in dried blood spots. The utility of blood spots for serological assays was confirmed by comparing antibodies eluted from blood spots with the equivalent plasma values in a series of samples from North Eastern Tanzania and by using blood spot-derived antibodies to estimate malaria transmission intensity in this site and for two localities in Uganda. Results Antibodies in spots on filter paper and glass fibre paper had similar stabilities but blood was more easily absorbed onto filter papers than glass fibre, spots were more regular and spot size was more closely correlated with blood volume for filter paper spots. Desiccated spots could be stored at or below 4°C for extended periods, but were stable for only very limited periods at ambient temperature. When desiccated, recoveries of antibodies that are predominantly of IgG1 or IgG3 subclasses were similar. Recoveries of antibodies from paired samples of serum and of blood spots from Tanzania which had been suitably stored showed similar recoveries of antibodies, but spots which had been stored for extended periods

  14. Pulse plating

    CERN Document Server

    Hansal, Wolfgang E G; Green, Todd; Leisner, Peter; Reichenbach, Andreas

    2012-01-01

    The electrodeposition of metals using pulsed current has achieved practical importance in recent years. Although it has long been known that changes in potential, with or without polarity reversal, can significantly affect the deposition process, the practical application of this has been slow to be adopted. This can largely be explained in terms of the complex relationship between the current regime and its effect on the electrodeposition process. In order to harness these effects, an understanding of the anodic and cathodic electrochemical processes is necessary, together with the effects of polarity reversal and the rate of such reversals. In this new monograph, the basics of metal electrodeposition from solution are laid out in great detail in seven distinct chapters. With this knowledge, the reader is able to predict how a given pulse train profile can be adopted to achieve a desired outcome. Equally important is the choice of a suitable rectifier and the ancillary control circuits to enable pulse platin...

  15. Numerical optimisation in spot detector design

    NARCIS (Netherlands)

    van der Heijden, Ferdinand; Apperloo, W.; Spreeuwers, Lieuwe Jan

    1997-01-01

    Spots are image details resulting from objects, the projections of which are so small that the inner structure of these objects cannot be resolved from their image. Spot detectors are image operators aiming at the detection and localisation of spots in the image. Most spot detectors can be tuned

  16. Managing emerging threats to spotted owls

    Science.gov (United States)

    Ho Yi Wan; Joseph L. Ganey; Christina D. Vojta; Samuel A. Cushman

    2018-01-01

    The 3 spotted owl (Strix occidentalis) subspecies in North America (i.e., northern spotted owl [S. o. caurina], California spotted owl [S. o. occidentalis], Mexican spotted owl [S. o. lucida]) have all experienced population declines over the past century due to habitat loss and fragmentation from logging. Now, the emerging influences of climate change, high-severity...

  17. 9 CFR 149.4 - Spot audit.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Spot audit. 149.4 Section 149.4... LIVESTOCK IMPROVEMENT VOLUNTARY TRICHINAE CERTIFICATION PROGRAM § 149.4 Spot audit. (a) In addition to regularly scheduled site audits, certified production sites will be subject to spot audits. (1) Random spot...

  18. The impact of eggshell colour and spot area in Japanese quails: II. Slaughter and carcass characteristic

    Directory of Open Access Journals (Sweden)

    Sema Alasahan

    Full Text Available ABSTRACT This study was carried out to investigate the effects of eggshell colour and spot properties (colour and size of the spot area on growth performance and carcass traits of Japanese quail (Coturnix coturnix japonica eggs. Study material were allocated to five groups according to their eggshell and spot colours: black spots on greyish white coloured eggshell (I, blue spots on greyish white coloured eggshell (II, diffuse brown spots on greyish brown coloured eggshell (III, brown spots on light green colored eggshell (IV, and small brown spots on greyish brown coloured eggshell (V. The size of the spotted area was determined in each egg group using digital image analysis. The groups did not differ for body weight and length of the shank at the end of the growth period. However, the groups differed significantly for carcass yield after slaughter (not eviscerated and carcass yield. These parameters were highest in Group I (82.08 and 76.09% and lowest in Group III (80.20 and 73.86%. Digital image analysis demonstrated that heart length, cardiac fat area, gizzard width, and intestine length varied between the groups. Cardiac fat area was largest in Group III (0.86 cm2 and smallest in Group V (0.65 cm2. Gizzard width was greatest in Group I (2.63 cm and smallest in Group V (2.47 cm. Intestine length was greatest in Group V (78.45 cm and smallest in Group IV (72.39 cm. Body weight, shank length, and slaughter and carcass weight do not vary in relation to eggshell colour or the size of the spotted area. The lengths of intestine and heart, gizzard width, and cardiac fat area do vary in relation to eggshell colour or the size of the spotted area.

  19. On the origin of delta spots

    International Nuclear Information System (INIS)

    Tang, F.

    1983-01-01

    Mount Wilson sunspot drawings from 1966 through 1980 were used in conjunction with Hα filtergrams from Big Bear Solar Observatory to examine the origin of delta spots, spots with bipolar umbrae within one penumbra. Of the six cases we studied, five were formed by the union of non-paired spots. They are either shoved into one another by two neighboring growing bipoles or by a new spot born piggy-back style on an existing spot of opposite polarity. Proper motions of the growing spots take on curvilinear paths around one another to avoid a collision. This is the shear motion observed in delta spots (Tanaka, 1979). In the remaining case, the delta spot was formed by spots that emerged as a pair. Our findings indicate no intrinsic differences in the formation or the behavior between delta spots of normal magnetic configuration. (orig.)

  20. Evaluation of the Weldability in Spot Welding using Ultrasonic Technique

    International Nuclear Information System (INIS)

    Hong, Min Sung; Kim, No Hyu

    2005-01-01

    Spot welding is the most widely used in automotive and aerospace industries. The quality of weld depends upon the size of nugget between the overlapped steel plates. Recently, the thickness of the steel plates is much thinner and hence, it introduces the smaller size of nugget. Therefore, it is necessary not only to develop the criterion to evaluate the quality of weld but also to obtain the optimal welding conditions for the better performance. In this paper, the steel plates, 0.5 mm through 1.5 mm thickness, have been spot welded at different welding conditions and the nugget sizes are examined by ultrasonic technique (C-scan type). The relationships between the nugget sizes and the weldability have been investigated. The result of ultrasonic technique shows the good agreement with that of the tensile test

  1. Evaluation of the Weldability in Spot Welding using Ultrasonic Technique

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Min Sung [Ajou University, Suwon (Korea, Republic of); Kim, No Hyu [Korea University of Technology and Education, Cheonan (Korea, Republic of)

    2005-06-15

    Spot welding is the most widely used in automotive and aerospace industries. The quality of weld depends upon the size of nugget between the overlapped steel plates. Recently, the thickness of the steel plates is much thinner and hence, it introduces the smaller size of nugget. Therefore, it is necessary not only to develop the criterion to evaluate the quality of weld but also to obtain the optimal welding conditions for the better performance. In this paper, the steel plates, 0.5 mm through 1.5 mm thickness, have been spot welded at different welding conditions and the nugget sizes are examined by ultrasonic technique (C-scan type). The relationships between the nugget sizes and the weldability have been investigated. The result of ultrasonic technique shows the good agreement with that of the tensile test

  2. Ultrasonic diagnosis of spot welding in thin plates

    International Nuclear Information System (INIS)

    Kim, No You; Hong, Min Sung

    2005-01-01

    Spot welding widely used in automotive and aerospace industries has made it possible to produce more precise and smaller electric part by robotization and systemization of welding process. The quality of welding depends upon the size of nugget between the overlapped steel plates. Recently, the thickness of the steel plates becomes much thinner and hence, it introduces the smaller size of nugget. Therefore, it is necessary to develop the criterion to evaluate the quality of weld in order to obtain the optimal welding conditions for the better performance. In this paper, a thin steel plates, 0.1 mm through 0.3 mm thickness, have been spot-welded at different welding conditions and the nugget sizes are examined by defocused scanning microscopy. The relationships between nugget sizes and weldability have been investigated experimentally. The result of ultrasonic technique shows the good agreement with that of the tensile test.

  3. Laser ablation comparison by picosecond pulses train and nanosecond pulse

    Science.gov (United States)

    Lednev, V. N.; Filippov, M. N.; Bunkin, A. F.; Pershin, S. M.

    2015-12-01

    A comparison of laser ablation by a train of picosecond pulses and nanosecond pulses revealed a difference in laser craters, ablation thresholds, plasma sizes and spectral line intensities. Laser ablation with a train of picosecond pulses resulted in improved crater quality while ablated mass decreased up to 30%. A reduction in laser plasma dimensions for picosecond train ablation was observed while the intensity of atomic/ionic lines in the plasma spectra was greater by a factor of 2-4 indicating an improved excitation and atomization in the plasma.

  4. Implication of spot position error on plan quality and patient safety in pencil-beam-scanning proton therapy

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Juan; Beltran, Chris J., E-mail: beltran.chris@mayo.edu; Herman, Michael G. [Division of Medical Physics, Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota 55905 (United States)

    2014-08-15

    Purpose: To quantitatively and systematically assess dosimetric effects induced by spot positioning error as a function of spot spacing (SS) on intensity-modulated proton therapy (IMPT) plan quality and to facilitate evaluation of safety tolerance limits on spot position. Methods: Spot position errors (PE) ranging from 1 to 2 mm were simulated. Simple plans were created on a water phantom, and IMPT plans were calculated on two pediatric patients with a brain tumor of 28 and 3 cc, respectively, using a commercial planning system. For the phantom, a uniform dose was delivered to targets located at different depths from 10 to 20 cm with various field sizes from 2{sup 2} to 15{sup 2} cm{sup 2}. Two nominal spot sizes, 4.0 and 6.6 mm of 1 σ in water at isocenter, were used for treatment planning. The SS ranged from 0.5 σ to 1.5 σ, which is 2–6 mm for the small spot size and 3.3–9.9 mm for the large spot size. Various perturbation scenarios of a single spot error and systematic and random multiple spot errors were studied. To quantify the dosimetric effects, percent dose error (PDE) depth profiles and the value of percent dose error at the maximum dose difference (PDE [ΔDmax]) were used for evaluation. Results: A pair of hot and cold spots was created per spot shift. PDE[ΔDmax] is found to be a complex function of PE, SS, spot size, depth, and global spot distribution that can be well defined in simple models. For volumetric targets, the PDE [ΔDmax] is not noticeably affected by the change of field size or target volume within the studied ranges. In general, reducing SS decreased the dose error. For the facility studied, given a single spot error with a PE of 1.2 mm and for both spot sizes, a SS of 1σ resulted in a 2% maximum dose error; a SS larger than 1.25 σ substantially increased the dose error and its sensitivity to PE. A similar trend was observed in multiple spot errors (both systematic and random errors). Systematic PE can lead to noticeable hot

  5. Single-shot and single-spot measurement of laser ablation threshold for carbon nanotubes

    International Nuclear Information System (INIS)

    Lednev, Vasily N; Pershin, Sergey M; Bunkin, Alexey F; Obraztsova, Elena D; Kudryashov, Sergey I

    2013-01-01

    A simple and convenient procedure for single-shot, single-spot ablation threshold measurement is developed. It is based on the employment of cylindrical lens to obtain an elliptical Gaussian laser spot. The ablated spot chords that are parallel to the minor axis are measured across the spot major axis, which is proportional to the fluence cross-section, thus providing wide range dependence of damaged spot size versus fluence in one spot measurement. For both conventional and newly developed procedures the ablation threshold for typical Nd:YAG laser parameters (1064 nm, 10 ns) is measured as 50 ± 5 mJ cm -2 , which is one order of magnitude lower than that for bulk graphite.

  6. Spot temperatures and area coverages on active dwarf stars

    Science.gov (United States)

    Sarr, Steven H.; Neff, James E.

    1990-01-01

    Two active K dwarfs are examined to determine the temperatures of the stars and to estimate the locations and sizes of cool spots on the stellar surfaces. Two wavelength regions with TiO absorption bands at different temperature sensitivities are modeled simultaneously using the method developed by Huenemoerder and Ramsey (1987). The spectrum of BD +26deg730 shows excess absorption in the TiO band, and the absence of the 8860 A band in HD 82558 indicates that its spots are warmer than those of BD +26deg730.

  7. Coherent combining pulse bursts in time domain

    Science.gov (United States)

    Galvanauskas, Almantas

    2018-01-09

    A beam combining and pulse stacking technique is provided that enhances laser pulse energy by coherent stacking pulse bursts (i.e. non-periodic pulsed signals) in time domain. This energy enhancement is achieved by using various configurations of Fabry-Perot, Gires-Tournois and other types of resonant cavities, so that a multiple-pulse burst incident at either a single input or multiple inputs of the system produces an output with a solitary pulse, which contains the summed energy of the incident multiple pulses from all beams. This disclosure provides a substantial improvement over conventional coherent-combining methods in that it achieves very high pulse energies using a relatively small number of combined laser systems, thus providing with orders of magnitude reduction in system size, complexity, and cost compared to current combining approaches.

  8. Systems and methods of varying charged particle beam spot size

    Science.gov (United States)

    Chen, Yu-Jiuan

    2014-09-02

    Methods and devices enable shaping of a charged particle beam. A modified dielectric wall accelerator includes a high gradient lens section and a main section. The high gradient lens section can be dynamically adjusted to establish the desired electric fields to minimize undesirable transverse defocusing fields at the entrance to the dielectric wall accelerator. Once a baseline setting with desirable output beam characteristic is established, the output beam can be dynamically modified to vary the output beam characteristics. The output beam can be modified by slightly adjusting the electric fields established across different sections of the modified dielectric wall accelerator. Additional control over the shape of the output beam can be excreted by introducing intentional timing de-synchronization offsets and producing an injected beam that is not fully matched to the entrance of the modified dielectric accelerator.

  9. Real-time laser cladding control with variable spot size

    Science.gov (United States)

    Arias, J. L.; Montealegre, M. A.; Vidal, F.; Rodríguez, J.; Mann, S.; Abels, P.; Motmans, F.

    2014-03-01

    Laser cladding processing has been used in different industries to improve the surface properties or to reconstruct damaged pieces. In order to cover areas considerably larger than the diameter of the laser beam, successive partially overlapping tracks are deposited. With no control over the process variables this conduces to an increase of the temperature, which could decrease mechanical properties of the laser cladded material. Commonly, the process is monitored and controlled by a PC using cameras, but this control suffers from a lack of speed caused by the image processing step. The aim of this work is to design and develop a FPGA-based laser cladding control system. This system is intended to modify the laser beam power according to the melt pool width, which is measured using a CMOS camera. All the control and monitoring tasks are carried out by a FPGA, taking advantage of its abundance of resources and speed of operation. The robustness of the image processing algorithm is assessed, as well as the control system performance. Laser power is decreased as substrate temperature increases, thus maintaining a constant clad width. This FPGA-based control system is integrated in an adaptive laser cladding system, which also includes an adaptive optical system that will control the laser focus distance on the fly. The whole system will constitute an efficient instrument for part repair with complex geometries and coating selective surfaces. This will be a significant step forward into the total industrial implementation of an automated industrial laser cladding process.

  10. Large area crystallization of amorphous Si with overlapping high repetition rate laser pulses

    KAUST Repository

    Ryu, Sang-Gil; Gruber, Ivan; Grigoropoulos, Costas P.; Poulikakos, Dimos; Moon, Seung-Jae

    2012-01-01

    crystallization induced by single laser pulses of circular cross-sectional profile. In a second step, crystallization by overlapping round spots is examined. The experiments reveal three zones characterized by distinctly different crystallized morphologies

  11. Poisson's spot and Gouy phase

    Science.gov (United States)

    da Paz, I. G.; Soldati, Rodolfo; Cabral, L. A.; de Oliveira, J. G. G.; Sampaio, Marcos

    2016-12-01

    Recently there have been experimental results on Poisson spot matter-wave interferometry followed by theoretical models describing the relative importance of the wave and particle behaviors for the phenomenon. We propose an analytical theoretical model for Poisson's spot with matter waves based on the Babinet principle, in which we use the results for free propagation and single-slit diffraction. We take into account effects of loss of coherence and finite detection area using the propagator for a quantum particle interacting with an environment. We observe that the matter-wave Gouy phase plays a role in the existence of the central peak and thus corroborates the predominantly wavelike character of the Poisson's spot. Our model shows remarkable agreement with the experimental data for deuterium (D2) molecules.

  12. Hybrid multi-response optimization of friction stir spot welds: failure ...

    Indian Academy of Sciences (India)

    O O OJO

    2018-06-08

    Jun 8, 2018 ... Friction stir spot welding; effective bonded size; failure load; expelled flash volume; hybrid multi- response ... eliminated with the application of FSSW process. Conse- ... design of experiment is generally applied in either single.

  13. Is this Red Spot the Blue Spot (locus ceruleum)?

    Energy Technology Data Exchange (ETDEWEB)

    Choe, Won Sick; Lee, Yu Kyung; Lee, Min Kyung; Hwang, Kyung Hoon [Gachon University Gil Hospital, Incheon (Korea, Republic of)

    2010-06-15

    The authors report brain images of 18F-FDG-PET in a case of schizophrenia. The images showed strikingly increased bilateral uptake in the locus ceruleum. The locus ceruleum is called the blue spot and known to be a center of the norepinephrinergic system.

  14. Is this Red Spot the Blue Spot (locus ceruleum)?

    International Nuclear Information System (INIS)

    Choe, Won Sick; Lee, Yu Kyung; Lee, Min Kyung; Hwang, Kyung Hoon

    2010-01-01

    The authors report brain images of 18F-FDG-PET in a case of schizophrenia. The images showed strikingly increased bilateral uptake in the locus ceruleum. The locus ceruleum is called the blue spot and known to be a center of the norepinephrinergic system.

  15. Statistical hot spot analysis of reactor cores

    International Nuclear Information System (INIS)

    Schaefer, H.

    1974-05-01

    This report is an introduction into statistical hot spot analysis. After the definition of the term 'hot spot' a statistical analysis is outlined. The mathematical method is presented, especially the formula concerning the probability of no hot spots in a reactor core is evaluated. A discussion with the boundary conditions of a statistical hot spot analysis is given (technological limits, nominal situation, uncertainties). The application of the hot spot analysis to the linear power of pellets and the temperature rise in cooling channels is demonstrated with respect to the test zone of KNK II. Basic values, such as probability of no hot spots, hot spot potential, expected hot spot diagram and cumulative distribution function of hot spots, are discussed. It is shown, that the risk of hot channels can be dispersed equally over all subassemblies by an adequate choice of the nominal temperature distribution in the core

  16. Pulsed power

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    The key element of our pulsed power program is concentration of power in time and space by suppression of breakdown in dielectrics and in vacuum. Magnetically insulated vacuum transmission lines and magnetic suppression of insulator flashover have continued as the main reserch directions. Vacuum insulated line studies at Physics International have been expanded and a test bed at Sandia, called MITE (Magnetically Insulated Transmission Experiment), is under development. The choice for the baseline EBFA design will depend on the outcome of these studies and should be made in July 1977. The slow and intermediate speed pulsed power approaches to EBFA will be based on Proto I and Proto II results and several of the projected EBFA subsystems are presently being tested in Proto II. A further stage of power concentration, within the vacuum diode itself, would considerably ease the burden on dielectrics; methods of power multiplication involving magnetically imploded plasmas are being considered and tests have begun using the Ripple III apparatus

  17. In situ stabilization wall for containment and hot spot retrieval

    International Nuclear Information System (INIS)

    Loomis, G.G.

    1996-01-01

    This paper presents the results of a full scale field demonstration of a in situ stabilization technology applicable to buried transuranic waste. The technology involves creating a jet grouted wall around selected regions or hot spots within a buried waste site. The resulting wall provides a barrier against further horizontal migration of the contaminants and allows vertical digging of material inside the wall, thus minimizing waste during a hot spot removal action. The demonstration involved creating a open-quotes Uclose quotes shaped wall in the interior of a full sized, simulated waste pit. The wall simulated the main features of a four sided wall. The demonstration also involved a destructive examination and a stability test for a hot spot retrieval scenario

  18. Characterization of continuous and pulsed emission modes of a hybrid micro focus x-ray source for medical imaging applications

    Energy Technology Data Exchange (ETDEWEB)

    Ghani, Muhammad U.; Wong, Molly D.; Ren, Liqiang; Wu, Di; Zheng, Bin [Center for Biomedical Engineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK 73019 (United States); Rong, John X. [Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, TX 77030 (United States); Wu, Xizeng [Department of Radiology, University of Alabama at Birmingham, Birmingham, AL 35249 (United States); Liu, Hong, E-mail: liu@ou.edu [Center for Biomedical Engineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK 73019 (United States)

    2017-05-01

    The aim of this study was to quantitatively characterize a micro focus x-ray tube that can operate in both continuous and pulsed emission modes. The micro focus x-ray source (Model L9181-06, Hamamatsu Photonics, Japan) has a varying focal spot size ranging from 16 µm to 50 µm as the source output power changes from 10 to 39 W. We measured the source output, beam quality, focal spot sizes, kV accuracy, spectra shapes and spatial resolution. Source output was measured using an ionization chamber for various tube voltages (kVs) with varying current (µA) and distances. The beam quality was measured in terms of half value layer (HVL), kV accuracy was measured with a non-invasive kV meter, and the spectra was measured using a compact integrated spectrometer system. The focal spot sizes were measured using a slit method with a CCD detector with a pixel pitch of 22 µm. The spatial resolution was quantitatively measured using the slit method with a CMOS flat panel detector with a 50 µm pixel pitch, and compared to the qualitative results obtained by imaging a contrast bar pattern. The focal spot sizes in the vertical direction were smaller than that of the horizontal direction, the impact of which was visible when comparing the spatial resolution values. Our analyses revealed that both emission modes yield comparable imaging performances in terms of beam quality, spectra shape and spatial resolution effects. There were no significantly large differences, thus providing the motivation for future studies to design and develop stable and robust cone beam imaging systems for various diagnostic applications. - Highlights: • A micro focus x-ray source that operates in both continuous and pulse emission modes was quantitatively characterized. • The source output, beam quality, focal spot measurements, kV accuracy, spectra analyses and spatial resolution were measured. • Our analyses revealed that both emission modes yield comparable imaging performances in terms of beam

  19. Characterization of continuous and pulsed emission modes of a hybrid micro focus x-ray source for medical imaging applications

    International Nuclear Information System (INIS)

    Ghani, Muhammad U.; Wong, Molly D.; Ren, Liqiang; Wu, Di; Zheng, Bin; Rong, John X.; Wu, Xizeng; Liu, Hong

    2017-01-01

    The aim of this study was to quantitatively characterize a micro focus x-ray tube that can operate in both continuous and pulsed emission modes. The micro focus x-ray source (Model L9181-06, Hamamatsu Photonics, Japan) has a varying focal spot size ranging from 16 µm to 50 µm as the source output power changes from 10 to 39 W. We measured the source output, beam quality, focal spot sizes, kV accuracy, spectra shapes and spatial resolution. Source output was measured using an ionization chamber for various tube voltages (kVs) with varying current (µA) and distances. The beam quality was measured in terms of half value layer (HVL), kV accuracy was measured with a non-invasive kV meter, and the spectra was measured using a compact integrated spectrometer system. The focal spot sizes were measured using a slit method with a CCD detector with a pixel pitch of 22 µm. The spatial resolution was quantitatively measured using the slit method with a CMOS flat panel detector with a 50 µm pixel pitch, and compared to the qualitative results obtained by imaging a contrast bar pattern. The focal spot sizes in the vertical direction were smaller than that of the horizontal direction, the impact of which was visible when comparing the spatial resolution values. Our analyses revealed that both emission modes yield comparable imaging performances in terms of beam quality, spectra shape and spatial resolution effects. There were no significantly large differences, thus providing the motivation for future studies to design and develop stable and robust cone beam imaging systems for various diagnostic applications. - Highlights: • A micro focus x-ray source that operates in both continuous and pulse emission modes was quantitatively characterized. • The source output, beam quality, focal spot measurements, kV accuracy, spectra analyses and spatial resolution were measured. • Our analyses revealed that both emission modes yield comparable imaging performances in terms of beam

  20. Pulsed operation of high-pressure-sodium discharge lamps

    International Nuclear Information System (INIS)

    Guenther, K.; Kloss, H.G.; Lehmann, T.; Radtke, R.; Serick, F.

    1990-01-01

    Results of spectral and photometric measurements are presented for pulsed operated high-pressure-sodium lamps. Choosing for the colour temperature a value of 3000 K, the output spectrum was optimized with respect to colour rendition and lamp efficacy taking the pulse parameters, the sodium mole fraction, and the cold spot temperature as quantities to be varied. For the nominal rating of 70 W a maximum lamp efficacy of 70 lm/W and a colour rendering index of 40 can be obtained. Further improvements of the colour rendition require an enhanced sodium vapour pressure which can be achieved by operating the lamp at rised cold spot temperature. (orig.)

  1. Pulsed operation of high-pressure-sodium discharge lamps

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, K; Kloss, H G; Lehmann, T [Zentrum fuer Forschung und Technologie, Berlin (Germany, F.R.); Radtke, R; Serick, F [Zentralinstitut fuer Elektronenphysik, Berlin (Germany, F.R.)

    1990-01-01

    Results of spectral and photometric measurements are presented for pulsed operated high-pressure-sodium lamps. Choosing for the colour temperature a value of 3000 K, the output spectrum was optimized with respect to colour rendition and lamp efficacy taking the pulse parameters, the sodium mole fraction, and the cold spot temperature as quantities to be varied. For the nominal rating of 70 W a maximum lamp efficacy of 70 lm/W and a colour rendering index of 40 can be obtained. Further improvements of the colour rendition require an enhanced sodium vapour pressure which can be achieved by operating the lamp at rised cold spot temperature. (orig.).

  2. Investigations Of A Pulsed Cathodic Vacuum Arc

    Science.gov (United States)

    Oates, T. W. H.; Pigott, J.; Denniss, P.; Mckenzie, D. R.; Bilek, M. M. M.

    2003-06-01

    Cathodic vacuum arcs are well established as a method for producing thin films for coatings and as a source of metal ions. Research into DC vacuum arcs has been going on for over ten years in the School of Physics at the University of Sydney. Recently a project was undertaken in the school to design and build a pulsed CVA for use in the investigation of plasma sheaths and plasma immersion ion implantation. Pulsed cathodic vacuum arcs generally have a higher current and plasma density and also provide a more stable and reproducible plasma density than their DC counterparts. Additionally it has been shown that if a high repetition frequency can be established the deposition rate of pulsed arcs is equal to or greater than that of DC arcs with a concomitant reduction in the rate of macro-particle formation. We present here results of our investigations into the building of a center-triggered pulsed cathodic vacuum arc. The design of the power supply and trigger mechanism and the geometry of the anode and cathode are examined. Observations of type I and II arc spots using a CCD camera, and cathode spot velocity dependence on arc current will be presented. The role of retrograde motion in a high current pulsed arc is discussed.

  3. Investigations Of A Pulsed Cathodic Vacuum Arc

    International Nuclear Information System (INIS)

    Oates, T.W.H.; Pigott, J.; Denniss, P.; Mckenzie, D.R.; Bilek, M.M.M.

    2003-01-01

    Cathodic vacuum arcs are well established as a method for producing thin films for coatings and as a source of metal ions. Research into DC vacuum arcs has been going on for over ten years in the School of Physics at the University of Sydney. Recently a project was undertaken in the school to design and build a pulsed CVA for use in the investigation of plasma sheaths and plasma immersion ion implantation. Pulsed cathodic vacuum arcs generally have a higher current and plasma density and also provide a more stable and reproducible plasma density than their DC counterparts. Additionally it has been shown that if a high repetition frequency can be established the deposition rate of pulsed arcs is equal to or greater than that of DC arcs with a concomitant reduction in the rate of macro-particle formation. We present here results of our investigations into the building of a center-triggered pulsed cathodic vacuum arc. The design of the power supply and trigger mechanism and the geometry of the anode and cathode are examined. Observations of type I and II arc spots using a CCD camera, and cathode spot velocity dependence on arc current will be presented. The role of retrograde motion in a high current pulsed arc is discussed

  4. Control of treatment size in cavitation-enhanced high-intensity focused ultrasound using radio-frequency echo signals

    Science.gov (United States)

    Tomiyasu, Kentaro; Takagi, Ryo; Iwasaki, Ryosuke; Yoshizawa, Shin; Umemura, Shin-ichiro

    2017-07-01

    In high-intensity focused ultrasound (HIFU) treatment, controlling the ultrasound dose at each focal target spot is important because it is a problem that the length of the coagulated region in front of the focal point deviates owing to the differences in absorption in each focal target spot and attenuation in the intervening tissues. In this study, the detected changes in the power spectra of HIFU echoes were used by controlling the HIFU duration in the “trigger HIFU” sequence with the aim to increase coagulation size through the enhancement of the ultrasonic heating by the cavitation induced by the preceding extremely high intensity short “trigger” pulse. The result shows that this method can be used to detect boiling bubbles and the following generated cavitation bubbles at their early stage. By automatically stopping HIFU exposure immediately after detecting the bubbles, overheating was prevented and the deviation of the length of the coagulated region was reduced.

  5. Rocky Mountain spotted fever, Panama.

    Science.gov (United States)

    Estripeaut, Dora; Aramburú, María Gabriela; Sáez-Llorens, Xavier; Thompson, Herbert A; Dasch, Gregory A; Paddock, Christopher D; Zaki, Sherif; Eremeeva, Marina E

    2007-11-01

    We describe a fatal pediatric case of Rocky Mountain spotted fever in Panama, the first, to our knowledge, since the 1950s. Diagnosis was established by immunohistochemistry, PCR, and isolation of Rickettsia rickettsii from postmortem tissues. Molecular typing demonstrated strong relatedness of the isolate to strains of R. rickettsii from Central and South America.

  6. Acceleration of on-axis and ring-shaped electron beams in wakefields driven by Laguerre-Gaussian pulses

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guo-Bo [College of Science, National University of Defense Technology, Changsha 410073 (China); Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Chen, Min, E-mail: minchen@sjtu.edu.cn, E-mail: yanyunma@126.com; Luo, Ji; Zeng, Ming; Yuan, Tao; Yu, Ji-Ye; Yu, Lu-Le; Weng, Su-Ming [Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai 200240 (China); Ma, Yan-Yun, E-mail: minchen@sjtu.edu.cn, E-mail: yanyunma@126.com [College of Science, National University of Defense Technology, Changsha 410073 (China); Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai 200240 (China); Yu, Tong-Pu [College of Science, National University of Defense Technology, Changsha 410073 (China); Sheng, Zheng-Ming [Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai 200240 (China); SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2016-03-14

    The acceleration of electron beams with multiple transverse structures in wakefields driven by Laguerre-Gaussian pulses has been studied through three-dimensional (3D) particle-in-cell simulations. Under different laser-plasma conditions, the wakefield shows different transverse structures. In general cases, the wakefield shows a donut-like structure and it accelerates the ring-shaped hollow electron beam. When a lower plasma density or a smaller laser spot size is used, besides the donut-like wakefield, a central bell-like wakefield can also be excited. The wake sets in the center of the donut-like wake. In this case, both a central on-axis electron beam and a ring-shaped electron beam are simultaneously accelerated. Further, reducing the plasma density or laser spot size leads to an on-axis electron beam acceleration only. The research is beneficial for some potential applications requiring special pulse beam structures, such as positron acceleration and collimation.

  7. Scanning vs. single spot laser ablation (λ=213 nm) inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Gonzalez, Jhanis J.; Fernandez, Alberto; Mao Xianglei; Russo, Richard E.

    2004-01-01

    Sampling strategy is defined in this work as the interaction of a repetitively pulsed laser beam with a fixed position on a sample (single spot) or with a moving sample (scan). Analytical performance of these sampling strategies was compared by using 213 nm laser ablation ICP-MS. A geological rock (Tuff) was quantitatively analyzed based on NIST series 610-616 glass standard reference materials. Laser ablation data were compared to ICP-MS analysis of the dissolved samples. The scan strategy (50 μm/s) produced a flat, steady temporal ICP-MS response whereas the single spot strategy produced a signal that decayed with time (after 60 s). Single-spot sampling provided better accuracy and precision than the scan strategy when the first 15 s of the sampling time was eliminated from the data analysis. In addition, the single spot strategy showed less matrix dependence among the four NIST glasses

  8. Compliance of the normal-sized aorta in adolescents with Marfan syndrome: comparison of MR measurements of aortic distensibility and pulse wave velocity; Compliance der morphologisch unauffaelligen Aorta bei Jugendlichen mit Marfan Syndrom: Vergleich von MR-Messungen der aortalen Dehnbarkeit und der Pulswellengeschwindigkeit

    Energy Technology Data Exchange (ETDEWEB)

    Eichhorn, J.G.; Ruediger, H.J.; Gorenflo, M.; Khalil, M.; Ulmer, H. [Universitaetskinderklinik Heidelberg (Germany). Kardiologie; Krissak, R.; Kauczor, H.U. [Deutsches Krebsforschungszentrum (DKFZ), Heidelberg (Germany). Radiologie; Ley, S. [Deutsches Krebsforschungszentrum (DKFZ), Heidelberg (Germany). Radiologie; Universitaetsklinik Heidelberg (Germany). Paediatrische Kardiologie; Arnold, R. [Universitaetskinderklinik Heidelberg (Germany). Kardiologie; Universitaetskinderklinik Freiburg (Germany). Paediatrische Kardiologie; Boese, J. [Deutsches Krebsforschungszentrum (DKFZ), Heidelberg (Germany). Medizinische Physik in der Radiologie; Siemens AG, Medical Solutions, Forchheim (Germany). Angiography, Fluoroscopic and Radiographic Systems; Krug, R. [Deutsches Krebsforschungszentrum (DKFZ), Heidelberg (Germany). Medizinische Physik in der Radiologie; Fink, C. [Medizinische Fakultaet Mannheim der Univ. Heidelberg, Mannheim (Germany). Inst. fuer Klinische Radiologie

    2007-08-15

    Purpose: To compare the aortic compliance of the normal-sized aorta of adolescents with Marfan syndrome and healthy controls using MR measurements of the aortic distensibility and pulse wave velocity. Materials and Methods: Fourteen patients (median age: 15 [9-21] years) and 11 healthy subjects (23 [12-32] years) were examined at 1.5 T. The MR protocol included 2D steady-state free precession (SSFP)-CINE MRI of the aortic distensibility and PC-MRI of the pulse wave velocity. All measurements were positioned perpendicular to the descending aorta at the level of the diaphragm for assessing the changes in the aortic cross-sectional areas and additionally above and below this plane for assessing the pulse wave velocity. In addition contrast-enhanced 3D-MR angiography was performed in adolescents with Marfan syndrome to exclude morphologic changes and to prove normal-sized aorta. Results: Compared with control subjects, adolescents with Marfan syndrome had significantly decreased distensibility and significantly increased pulse wave velocity ({chi}{sup 2}-test, p = 0.0002) using an age-related non-linear regression analysis. The related aortic compliance was significantly decreased ({chi}{sup 2}-test, p = 0.0002). There was a good correlation between the two methods (r = 0.86). A low intraobserver variability was found for both methods ({<=} 2 %). (orig.)

  9. Investigation of laser plasma instabilities using picosecond laser pulses

    International Nuclear Information System (INIS)

    Kline, J L; Montgomery, D S; Yin, L; Flippo, K A; Shimada, T; Johnson, R P; Rose, H A; Albright, B J; Hardin, R A

    2008-01-01

    A new short-pulse version of the single-hot-spot configuration has been implemented to enhance the performance of experiments to understand Stimulated Raman Scattering. The laser pulse length was reduced from ∼200 to ∼3 ps. The reduced pulse length improves the experiment by minimizing effects such as plasma hydrodynamic evolution and ponderomotive filamentation of the interaction beam. In addition, the shortened laser pulses allow full length 2D particle-in-cell simulations of the experiments. Using the improved single-hot-spot configuration, a series of experiments to investigate kλ D scaling of SRS has been performed. Details of the experimental setup and initial results will be presented

  10. Effect of the small accessary laser spots on the harmonic emission stimulated by self-focusing of a 10-micrometer scale laser spot

    International Nuclear Information System (INIS)

    Lin Zunqi; Zhang Huihuang; He Xingfa

    1992-01-01

    A novel group of experiments has shown that single 10-micrometer-radius-scale laser spot is not able to produce the 90 deg side emitted three half harmonic efficiently in a preformed laser plasmas. However, with the help of one or two accessory laser spots with the size similar to the main one, the side emitted three half can easily built up when some position and angle conditions for the accessory spots are fulfilled. The origin of these phenomena have been analyzed in terms of the two plasmon decay theory and dynamic self-focusing model

  11. PULSE COLUMN

    Science.gov (United States)

    Grimmett, E.S.

    1964-01-01

    This patent covers a continuous countercurrent liquidsolids contactor column having a number of contactor states each comprising a perforated plate, a layer of balls, and a downcomer tube; a liquid-pulsing piston; and a solids discharger formed of a conical section at the bottom of the column, and a tubular extension on the lowest downcomer terminating in the conical section. Between the conical section and the downcomer extension is formed a small annular opening, through which solids fall coming through the perforated plate of the lowest contactor stage. This annular opening is small enough that the pressure drop thereacross is greater than the pressure drop upward through the lowest contactor stage. (AEC)

  12. Pulse radiolysis

    International Nuclear Information System (INIS)

    Greenshields, H.; Seddon, W.A.

    1982-03-01

    This supplement to two bibliographies published in 1970 and 1972 lists 734 references to the literature of pulse radiolysis, arranged under eight broad subject headings. The references were compiled by searching Biological Abstracts, Chemical Abstracts, Nuclear Science Abstracts and the Weekly List of Papers in Radiation Chemistry issued by the Radiation Chemistry Data Center of Notre Dame University. Full bibliographic data is given for papers published in the period 1971 to 1974. A personal author index listing more than 600 authors and a similar number of co-authors is included

  13. Modelling of a proton spot scanning system using MCNP6

    International Nuclear Information System (INIS)

    Ardenfors, O; Gudowska, I; Dasu, A; Kopeć, M

    2017-01-01

    The aim of this work was to model the characteristics of a clinical proton spot scanning beam using Monte Carlo simulations with the code MCNP6. The proton beam was defined using parameters obtained from beam commissioning at the Skandion Clinic, Uppsala, Sweden. Simulations were evaluated against measurements for proton energies between 60 and 226 MeV with regard to range in water, lateral spot sizes in air and absorbed dose depth profiles in water. The model was also used to evaluate the experimental impact of lateral signal losses in an ionization chamber through simulations using different detector radii. Simulated and measured distal ranges agreed within 0.1 mm for R 90 and R 80 , and within 0.2 mm for R 50 . The average absolute difference of all spot sizes was 0.1 mm. The average agreement of absorbed dose integrals and Bragg-peak heights was 0.9%. Lateral signal losses increased with incident proton energy with a maximum signal loss of 7% for 226 MeV protons. The good agreement between simulations and measurements supports the assumptions and parameters employed in the presented Monte Carlo model. The characteristics of the proton spot scanning beam were accurately reproduced and the model will prove useful in future studies on secondary neutrons. (paper)

  14. The spot market and the spot price: applicability and limitations

    International Nuclear Information System (INIS)

    White, G. Jr.

    1987-01-01

    The subject of spot prices and their relationship to long-term contracting is addressed. The author is associated with Nuexco, which originally was called the Nuclear Exchange Corporation. They use the term Exchange Value which originated in the idea that Nuexco operated an exchange 'bank' - those with too much uranium could 'bank it', those with short-term needs could borrow from the 'bank'. If the borrower repaid slightly more or less the difference was settled using the 'exchange value'. This became used for longer-term transactions and now settling the monthly value is an important part of Nuexco's activities. The exact nature of the Exchange Value is defined. Now more and more buyers are insisting on spot market related pricing even where this is not meaningfully related to uranium production costs. (U.K.)

  15. Focusing on butterfly eyespot focus: uncoupling of white spots from eyespot bodies in nymphalid butterflies.

    Science.gov (United States)

    Iwata, Masaki; Otaki, Joji M

    2016-01-01

    Developmental studies on butterfly wing color patterns often focus on eyespots. A typical eyespot (such as that of Bicyclus anynana) has a few concentric rings of dark and light colors and a white spot (called a focus) at the center. The prospective eyespot center during the early pupal stage is known to act as an organizing center. It has often been assumed, according to gradient models for positional information, that a white spot in adult wings corresponds to an organizing center and that the size of the white spot indicates how active that organizing center was. However, there is no supporting evidence for these assumptions. To evaluate the feasibility of these assumptions in nymphalid butterflies, we studied the unique color patterns of Calisto tasajera (Nymphalidae, Satyrinae), which have not been analyzed before in the literature. In the anterior forewing, one white spot was located at the center of an eyespot, but another white spot associated with either no or only a small eyespot was present in the adjacent compartment. The anterior hindwing contained two adjacent white spots not associated with eyespots, one of which showed a sparse pattern. The posterior hindwing contained two adjacent pear-shaped eyespots, and the white spots were located at the proximal side or even outside the eyespot bodies. The successive white spots within a single compartment along the midline in the posterior hindwing showed a possible trajectory of a positional determination process for the white spots. Several cases of focus-less eyespots in other nymphalid butterflies were also presented. These results argue for the uncoupling of white spots from eyespot bodies, suggesting that an eyespot organizing center does not necessarily differentiate into a white spot and that a prospective white spot does not necessarily signify organizing activity for an eyespot. Incorporation of these results in future models for butterfly wing color pattern formation is encouraged.

  16. Laser Pyrometer For Spot Temperature Measurements

    Science.gov (United States)

    Elleman, D. D.; Allen, J. L.; Lee, M. C.

    1988-01-01

    Laser pyrometer makes temperature map by scanning measuring spot across target. Scanning laser pyrometer passively measures radiation emitted by scanned spot on target and calibrated by similar passive measurement on blackbody of known temperature. Laser beam turned on for active measurements of reflectances of target spot and reflectance standard. From measurements, temperature of target spot inferred. Pyrometer useful for non-contact measurement of temperature distributions in processing of materials.

  17. Laser Spot Detection Based on Reaction Diffusion

    OpenAIRE

    Alejandro Vázquez-Otero; Danila Khikhlukha; J. M. Solano-Altamirano; Raquel Dormido; Natividad Duro

    2016-01-01

    Center-location of a laser spot is a problem of interest when the laser is used for processing and performing measurements. Measurement quality depends on correctly determining the location of the laser spot. Hence, improving and proposing algorithms for the correct location of the spots are fundamental issues in laser-based measurements. In this paper we introduce a Reaction Diffusion (RD) system as the main computational framework for robustly finding laser spot centers. The method presente...

  18. WEIBULL MULTIPLICATIVE MODEL AND MACHINE LEARNING MODELS FOR FULL-AUTOMATIC DARK-SPOT DETECTION FROM SAR IMAGES

    Directory of Open Access Journals (Sweden)

    A. Taravat

    2013-09-01

    Full Text Available As a major aspect of marine pollution, oil release into the sea has serious biological and environmental impacts. Among remote sensing systems (which is a tool that offers a non-destructive investigation method, synthetic aperture radar (SAR can provide valuable synoptic information about the position and size of the oil spill due to its wide area coverage and day/night, and all-weather capabilities. In this paper we present a new automated method for oil-spill monitoring. A new approach is based on the combination of Weibull Multiplicative Model and machine learning techniques to differentiate between dark spots and the background. First, the filter created based on Weibull Multiplicative Model is applied to each sub-image. Second, the sub-image is segmented by two different neural networks techniques (Pulsed Coupled Neural Networks and Multilayer Perceptron Neural Networks. As the last step, a very simple filtering process is used to eliminate the false targets. The proposed approaches were tested on 20 ENVISAT and ERS2 images which contained dark spots. The same parameters were used in all tests. For the overall dataset, the average accuracies of 94.05 % and 95.20 % were obtained for PCNN and MLP methods, respectively. The average computational time for dark-spot detection with a 256 × 256 image in about 4 s for PCNN segmentation using IDL software which is the fastest one in this field at present. Our experimental results demonstrate that the proposed approach is very fast, robust and effective. The proposed approach can be applied to the future spaceborne SAR images.

  19. Weibull Multiplicative Model and Machine Learning Models for Full-Automatic Dark-Spot Detection from SAR Images

    Science.gov (United States)

    Taravat, A.; Del Frate, F.

    2013-09-01

    As a major aspect of marine pollution, oil release into the sea has serious biological and environmental impacts. Among remote sensing systems (which is a tool that offers a non-destructive investigation method), synthetic aperture radar (SAR) can provide valuable synoptic information about the position and size of the oil spill due to its wide area coverage and day/night, and all-weather capabilities. In this paper we present a new automated method for oil-spill monitoring. A new approach is based on the combination of Weibull Multiplicative Model and machine learning techniques to differentiate between dark spots and the background. First, the filter created based on Weibull Multiplicative Model is applied to each sub-image. Second, the sub-image is segmented by two different neural networks techniques (Pulsed Coupled Neural Networks and Multilayer Perceptron Neural Networks). As the last step, a very simple filtering process is used to eliminate the false targets. The proposed approaches were tested on 20 ENVISAT and ERS2 images which contained dark spots. The same parameters were used in all tests. For the overall dataset, the average accuracies of 94.05 % and 95.20 % were obtained for PCNN and MLP methods, respectively. The average computational time for dark-spot detection with a 256 × 256 image in about 4 s for PCNN segmentation using IDL software which is the fastest one in this field at present. Our experimental results demonstrate that the proposed approach is very fast, robust and effective. The proposed approach can be applied to the future spaceborne SAR images.

  20. Pulse pile-up. I: Short pulses

    International Nuclear Information System (INIS)

    Wilkinson, D.H.

    1990-07-01

    The search for rare large pulses against an intense background of smaller ones involves consideration of pulse pile-up. Approximate methods are presented, based on ruin theory, by which the probability of such pile-up may be estimated for pulses of arbitrary form and of arbitrary pulse-height distribution. These methods are checked against cases for which exact solutions are available. The present paper is concerned chiefly with short pulses of finite total duration. (Author) (5 refs., 24 figs.)

  1. 7 CFR 1421.11 - Spot checks.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Spot checks. 1421.11 Section 1421.11 Agriculture... ASSISTANCE LOANS AND LOAN DEFICIENCY PAYMENTS FOR 2008 THROUGH 2012 General § 1421.11 Spot checks. (a) CCC... CCC access to the farm and storage facility as necessary to conduct collateral inspections, or “spot...

  2. 21 CFR 886.1435 - Maxwell spot.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Maxwell spot. 886.1435 Section 886.1435 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1435 Maxwell spot. (a) Identification. A Maxwell spot is an AC...

  3. Spot på samtalen:

    DEFF Research Database (Denmark)

    Danneris, Sophie; Jensen, Tanja Dall; Caswell, Dorte

    Spot på samtalen sætter fokus på det, der konkret foregår i samtaler mellem borgere og de beskæftigelsesfaglige medarbejdere i jobcentrene. Da de udsatte grupper i mange tilfælde er langt fra arbejdsmarkedet, er interessen rettet mod, hvilke forhold i kontakten med beskæftigelsessystemet, der...... har betydning hvilke indsatser ledige modtager, men også hvordan de modtager dem. Her rettes blikket mod den centrale del af den beskæftigelsespolitiske indsats som samtalerne udgør. I Spot på samtalen er blikket rettet mod de dynamikker, mønstre og mekanismer, der kommer i spil i samtalerne i...

  4. A Drosophila wing spot test

    International Nuclear Information System (INIS)

    Ayaki, Toshikazu; Yoshikawa, Isao; Niikawa, Norio; Hoshi, Masaharu.

    1986-01-01

    A Drosophila wing spot test system was used to investigate the effects of low doses of X-rays, gamma rays, and both 2.3 and 14.1 MeV neutrons on somatic chromosome mutation (SCM) induction. The incidence of SCM was significantly increased with any type of radiation, with evident linear dose-response relationship within the range of 3 to 20 cGy. It was estimated that relative biological effectiveness value for SCM induction of 2.3 MeV neutrons to X-rays and gamma rays is much higher than that of 14.1 MeV neutrons to those photons (2.4 vs 8.0). The Drosophila wing spot test system seems to become a promising in vivo experimental method for higher animals in terms of the lack of necessity for a marvelously large number of materials required in conventional test system. (Namekawa, K.)

  5. Managing Rocky Mountain spotted fever.

    Science.gov (United States)

    Minniear, Timothy D; Buckingham, Steven C

    2009-11-01

    Rocky Mountain spotted fever is caused by the tick-borne bacterium Rickettsia rickettsii. Symptoms range from moderate illness to severe illness, including cardiovascular compromise, coma and death. The disease is prevalent in most of the USA, especially during warmer months. The trademark presentation is fever and rash with a history of tick bite, although tick exposure is unappreciated in over a third of cases. Other signature symptoms include headache and abdominal pain. The antibiotic therapy of choice for R. rickettsii infection is doxycycline. Preventive measures for Rocky Mountain spotted fever and other tick-borne diseases include: wearing long-sleeved, light colored clothing; checking for tick attachment and removing attached ticks promptly; applying topical insect repellent; and treating clothing with permethrin.

  6. Measurement of laser spot quality

    Science.gov (United States)

    Milster, T. D.; Treptau, J. P.

    1991-01-01

    Several ways of measuring spot quality are compared. We examine in detail various figures of merit such as full width at half maximum (FWHM), full width at 1/(e exp 2) maximum, Strehl ratio, and encircled energy. Our application is optical data storage, but results can be applied to other areas like space communications and high energy lasers. We found that the optimum figure of merit in many cases is Strehl ratio.

  7. Sweet Spots and Door Stops

    Science.gov (United States)

    Thompson, Michael; Tsui, Stella; Leung, Chi Fan

    2011-01-01

    A sweet spot is referred to in sport as the perfect place to strike a ball with a racquet or bat. It is the point of contact between bat and ball where maximum results can be produced with minimal effort from the hand of the player. Similar physics can be applied to the less inspiring examples of door stops; the perfect position of a door stop is…

  8. Justifications shape ethical blind spots.

    Science.gov (United States)

    Pittarello, Andrea; Leib, Margarita; Gordon-Hecker, Tom; Shalvi, Shaul

    2015-06-01

    To some extent, unethical behavior results from people's limited attention to ethical considerations, which results in an ethical blind spot. Here, we focus on the role of ambiguity in shaping people's ethical blind spots, which in turn lead to their ethical failures. We suggest that in ambiguous settings, individuals' attention shifts toward tempting information, which determines the magnitude of their lies. Employing a novel ambiguous-dice paradigm, we asked participants to report the outcome of the die roll appearing closest to the location of a previously presented fixation cross on a computer screen; this outcome would determine their pay. We varied the value of the die second closest to the fixation cross to be either higher (i.e., tempting) or lower (i.e., not tempting) than the die closest to the fixation cross. Results of two experiments revealed that in ambiguous settings, people's incorrect responses were self-serving. Tracking participants' eye movements demonstrated that people's ethical blind spots are shaped by increased attention toward tempting information. © The Author(s) 2015.

  9. Resistance Spot Welding of dissimilar Steels

    Directory of Open Access Journals (Sweden)

    Ladislav Kolařík

    2012-01-01

    Full Text Available This paper presents an analysis of the properties of resistance spot welds between low carbon steel and austenitic CrNi stainless steel. The thickness of the welded dissimilar materials was 2 mm. A DeltaSpot welding gun with a process tape was used for welding the dissimilar steels. Resistance spot welds were produced with various welding parameters (welding currents ranging from 7 to 8 kA. Light microscopy, microhardness measurements across the welded joints, and EDX analysis were used to evaluate the quality of the resistance spot welds. The results confirm the applicability of DeltaSpot welding for this combination of materials.

  10. The effect of defocusing on spot diameter when ablate the silicon surface by femtosecond laser

    Science.gov (United States)

    Luo, Xinkai; Li, Wei; Wu, Tengfei; Wang, Yu; Zhu, Zhenyu

    2018-02-01

    Femtosecond laser has been demonstrated to be a prominent tool to manufacture micro scale structure. In the processing, the focusing lens is usually used as the concentrated tool to assemble the original beam to the tiny spot to provide enough energy for ablation. What is more, different focal length means the diverse scale of the focused spot. In common use, various sizes of the spot are required to adjust to the multifarious profiles and substituting the focus lens is the general method. There is no doubt that changing the lens is a fussy job and frequent replacing the lens may cause the lack of stability. In this paper, we report the defocus of the lens to modify the scale of the spot and it is proved to be an effective way to vary the diameter of the focused spot without changing the focus lens.

  11. Spot formation of radiation particles by electrochemical etching

    International Nuclear Information System (INIS)

    Nozaki, Tetsuya

    1999-01-01

    An electrochemical etching (ECE) spot formation from the top of chemical etching (CE) spot was confirmed by a series of experiments. One of polycarbonate (Iupilon) could not make the spot, because ECE spot had grown up before the microscope confirming the CE spot. Clear CEC spots by α-ray and neutron were found on Harzlas and Baryotrak, both improvements of CR-39. Under the same etching conditions, the growth of ECE spot on Harzlas was more rapid than Baryotrak, but both spots were almost the same. All CE spot by α-ray produced the CEC spots, but a part of CE circle spot by neutron formed them. (S.Y.)

  12. Computational prediction of protein hot spot residues.

    Science.gov (United States)

    Morrow, John Kenneth; Zhang, Shuxing

    2012-01-01

    Most biological processes involve multiple proteins interacting with each other. It has been recently discovered that certain residues in these protein-protein interactions, which are called hot spots, contribute more significantly to binding affinity than others. Hot spot residues have unique and diverse energetic properties that make them challenging yet important targets in the modulation of protein-protein complexes. Design of therapeutic agents that interact with hot spot residues has proven to be a valid methodology in disrupting unwanted protein-protein interactions. Using biological methods to determine which residues are hot spots can be costly and time consuming. Recent advances in computational approaches to predict hot spots have incorporated a myriad of features, and have shown increasing predictive successes. Here we review the state of knowledge around protein-protein interactions, hot spots, and give an overview of multiple in silico prediction techniques of hot spot residues.

  13. Computational Prediction of Hot Spot Residues

    Science.gov (United States)

    Morrow, John Kenneth; Zhang, Shuxing

    2013-01-01

    Most biological processes involve multiple proteins interacting with each other. It has been recently discovered that certain residues in these protein-protein interactions, which are called hot spots, contribute more significantly to binding affinity than others. Hot spot residues have unique and diverse energetic properties that make them challenging yet important targets in the modulation of protein-protein complexes. Design of therapeutic agents that interact with hot spot residues has proven to be a valid methodology in disrupting unwanted protein-protein interactions. Using biological methods to determine which residues are hot spots can be costly and time consuming. Recent advances in computational approaches to predict hot spots have incorporated a myriad of features, and have shown increasing predictive successes. Here we review the state of knowledge around protein-protein interactions, hot spots, and give an overview of multiple in silico prediction techniques of hot spot residues. PMID:22316154

  14. Discharge behavior of vacuum arc ion source working in pulse mode

    International Nuclear Information System (INIS)

    Tang Pingying; Dai Jingyi; Tan Xiaohua; Jin Dazhi; Liu Tie; Ding Bonan

    2005-01-01

    Discharge behavior of the vacuum arc ion source working in pulse mode was investigated using high-speed photography and spectrum diagnosis. The evolvement of cathode spot on hydrogen-impregnated electrode was captured by high-speed photography, and the emission spectra of cathode spot at different pulse currents were analyzed. The experimental results show that in most cases, only one cathode spot can be found in the discharge zone of vacuum arc ion source, and the spot moves a little during the same discharge. Temperature of the cathode spot may rise while the discharge current increases, and ultimately the density of hydrogen ion will be increased. At the same time, sputtering of the electrode is enhanced and the quality of ion plasma will be reduced. (authors)

  15. The spatial thickness distribution of metal films produced by large area pulsed laser deposition

    DEFF Research Database (Denmark)

    Pryds, Nini; Schou, Jørgen; Linderoth, Søren

    2007-01-01

    Thin films of metals have been deposited in the large-area Pulsed Laser Deposition (PLD) Facility at Riso National Laboratory. Thin films of Ag and Ni were deposited with laser pulses from an excimer laser at 248 nm with a rectangular beam spot at a fluence of 10 J/cm(2) on glass substrates of 127...

  16. Enlargement of the pulsing flow regime by periodic operation of a trickle-bed reactor.

    NARCIS (Netherlands)

    Boelhouwer, J.G.; Piepers, H.W.; Drinkenburg, A.A.H.

    1999-01-01

    Potential advantages of pulsing flow in trickle-bed reactors include capacity increase and elimination of hot spots through the enhanced mass and heat transfer rates. A disadvantage of naturally occurring pulsing flow is the necessity of relatively high gas and liquid flow rates, especially at

  17. Influence of pulse electrodeposition parameters on microhardness ...

    Indian Academy of Sciences (India)

    duty cycle on the microhardness and grain size of nanocomposite coatings that produced through the pulse current ... prepared by blowing inert metallic gas on a cold substrate in which fast gas .... were produced by a power supply.

  18. Numerical stud of glare spot phase Doppler anemometry

    OpenAIRE

    Hespel , Camille; Ren , Kuan Fang; Gréhan , Gérard; Onofri , Fabrice

    2008-01-01

    International audience; The phase Doppler anemometry has (PDA) been developed to measure simultaneously the velocity and the size of droplets. When the concentration of particles is high, tightly focused beams must be used, as in the dual burst PDA. The latter permits an access to the refractive index of the particle, but the effect of wave front curvature of the incident beams becomes evident. In this paper, we introduce a glare spot phase Doppler anemometry which uses two large beams. The i...

  19. Optimization of radiographic spot for the TriMeV accelerator

    International Nuclear Information System (INIS)

    Welch, D.R.; Oliver, B.V.; Rosenthal, S.E.; Olson, C.L.

    1999-01-01

    The authors are examining diode configurations for the 3-MeV, 30-kA TriMeV electron-beam accelerator at Bechtel Nevada. These include a flat-cathode diode with focusing into a gas cell and a magnetically-immersed diode similar to that used on HERMES III at Sandia National Laboratories. They are in the process of optimizing the diode designs using the hybrid kinetic-fluid simulation code IPROP which models both vacuum flow and gas breakdown. These configurations will be fielded on TriMeV this year. The TriMeV voltage pulse is somewhat unique in that it has a 3-ns rise and fall time with a 14-ns flat top. This sharp rise and fall in voltage make it ideal for studying beam focusing. The flat-cathode diode uses a 3.5-cm radius velvet electron emitter and a 4-cm anode-cathode gap that has produced a 23 kA beam self-focused in vacuum into a gas cell of 2.8-cm radius. The time-integrated beam spot has been optimized experimentally with 10 Torr nitrogen in the ballistic focusing regime where self fields are minimal. New currents < 5 kA were measured at the gas cell wall for 5--15 Torr nitrogen. Below 2 Torr, the net current increases rapidly to the full beam current. IPROP has simulated this behavior in reasonable agreement with experiment. The code predicts that, due to finite plasma current decay, the time-integrated spot is increased as the beam focus moves upstream of the target. If the diode voltage is sufficiently stable, IPROP predicts a root-mean-square (RMS) radius <2 mm in the runaway regime (1 Torr). In an immersed TriMeV diode, a 10--15 kA electron beam is emitted from a sub-millimeter needle cathode into a strong 12--18 Tesia solenoidal field. The remaining current is lost to the outer wall. The large fields are necessary to limit growth of the magnetized ion-hose instability. With careful design of the cathode structure, the authors can minimize the current flowing into the diode from large radius. IPROP calculates an RMS radius <1 mm. With close

  20. W-1% La2O3 Submitted to a Single Laser Pulse: Effect of Particles on Heat Transfer and Surface Morphology

    Directory of Open Access Journals (Sweden)

    Pasquale Gaudio

    2018-05-01

    Full Text Available W-1% La2O3 has been irradiated by a single laser pulse (λ = 1064 nm, pulse duration τ ≈ 15 ns, pulse energy Ep ≈ 4 J, spot size Φ = 200 μm, surface power density I = 8.5 × 1011 W·cm−2 to simulate the effects of transient thermal loads of high energy occurring in a tokamak under operative conditions. The samples have been then examined by scanning electron microscope (SEM observations to investigate erosion effects and surface morphological features. A surface depression forms in the spot central area surrounded by a ridge due to the movement of molten metal. Owing to the burst of gas bubbles, hemispherical cavities of about 10 μm and deposited droplets are observed in the ridge while the zones surrounding the ridge thermal stresses arising from fast heating and successive cooling produce an extended network of micro-cracks that often follow grain boundaries. The results are discussed and compared to those obtained in a previous work on pure bulk W.

  1. Mechanistic study on black and grey spot growth in OLEDs performed on laser-ablated pinholes in the cathode

    NARCIS (Netherlands)

    Weijer, P. van de; Bouten, P.C.P.; Fledderus, H.; Janssen, R.R.; Winter, S.H.P.M. de; Akkerman, H.B.

    2017-01-01

    Local laser ablation of the cathode of OLEDs has been applied to create a population of pinholes of the same size. This enables the direct comparison at different conditions of black spots and grey spots in the emission of OLEDs as a result of water ingress into the device. We confirmed earlier

  2. Does the G-spot exist? A review of the current literature.

    Science.gov (United States)

    Puppo, Vincenzo; Gruenwald, Ilan

    2012-12-01

    In 1950, Gräfenberg described a distinct erotogenic zone on the anterior wall of the vagina, which was referred to as the Gräfenberg spot (G-spot) by Addiego, Whipple (a nurse) et al. in 1981. As a result, the G-spot has become a central topic of popular speculation and a basis of a huge business surrounding it. In our opinion, these sexologists have made a hotchpotch of Gräfenberg's thoughts and ideas that were set forth and expounded in his 1950 article: the intraurethral glands are not the corpus spongiosum of the female urethra, and Gräfenberg did not report an orgasm of the intraurethral glands. G-spot amplification is a cosmetic surgery procedure for temporarily increasing the size and sensitivity of the G-spot in which a dermal filler or a collagen-like material is injected into the bladder-vaginal septum. All published scientific data point to the fact that the G-spot does not exist, and the supposed G-spot should not be identified with Gräfenberg's name. Moreover, G-spot amplification is not medically indicated and is an unnecessary and inefficacious medical procedure.

  3. Methodology and software to detect viral integration site hot-spots

    Science.gov (United States)

    2011-01-01

    Background Modern gene therapy methods have limited control over where a therapeutic viral vector inserts into the host genome. Vector integration can activate local gene expression, which can cause cancer if the vector inserts near an oncogene. Viral integration hot-spots or 'common insertion sites' (CIS) are scrutinized to evaluate and predict patient safety. CIS are typically defined by a minimum density of insertions (such as 2-4 within a 30-100 kb region), which unfortunately depends on the total number of observed VIS. This is problematic for comparing hot-spot distributions across data sets and patients, where the VIS numbers may vary. Results We develop two new methods for defining hot-spots that are relatively independent of data set size. Both methods operate on distributions of VIS across consecutive 1 Mb 'bins' of the genome. The first method 'z-threshold' tallies the number of VIS per bin, converts these counts to z-scores, and applies a threshold to define high density bins. The second method 'BCP' applies a Bayesian change-point model to the z-scores to define hot-spots. The novel hot-spot methods are compared with a conventional CIS method using simulated data sets and data sets from five published human studies, including the X-linked ALD (adrenoleukodystrophy), CGD (chronic granulomatous disease) and SCID-X1 (X-linked severe combined immunodeficiency) trials. The BCP analysis of the human X-linked ALD data for two patients separately (774 and 1627 VIS) and combined (2401 VIS) resulted in 5-6 hot-spots covering 0.17-0.251% of the genome and containing 5.56-7.74% of the total VIS. In comparison, the CIS analysis resulted in 12-110 hot-spots covering 0.018-0.246% of the genome and containing 5.81-22.7% of the VIS, corresponding to a greater number of hot-spots as the data set size increased. Our hot-spot methods enable one to evaluate the extent of VIS clustering, and formally compare data sets in terms of hot-spot overlap. Finally, we show that the

  4. Treatment of Basal Cell Carcinomas with Pulsed Dye Laser: A Case Series

    Directory of Open Access Journals (Sweden)

    Norman Minars

    2012-01-01

    Full Text Available Background. Basal cell carcinoma (BCC is the most prevalent skin cancer. Because of its highly vascular characteristic, it is amendable to treatment with pulse dye laser (PDL. The goal of this study is to determine the safety and efficacy of PDL therapy for mostly facial BCCs. Materials and Methods. Sixteen men and thirteen women (29 total with 39 biopsy-proven BCCs were treated with 1–4 PDL (595 nm therapies at 2–4-week intervals. The treatment parameters included pulse energy of 15 J/cm 2, pulse length of 3 millisecond, with no dynamic cooling, and 7 mm spot size. The age of the patients was 30–90 years (mean 73 years. Response rates were evaluated by the clinical assessments with mean followup of 11 months. Results. Twenty-four patients with thirty-two tumors reached at least three months followup: 24/32 (75% tumors with complete resolution (mean 3 treatment sessions; 5/32 (16% tumors recurred; 3/32 (9% tumors with incomplete responses after four treatments. Minimal side effects and discomfort were experienced by the patients with PDL therapy. Conclusion. PDL is a safe, tolerable, and moderately effective method of treating various BCCs. The ideal niche and standardized settings for PDL treatment of BCCs are yet to be determined.

  5. In-process monitoring and adaptive control for gap in micro butt welding with pulsed YAG laser

    International Nuclear Information System (INIS)

    Kawahito, Yousuke; Kito, Masayuki; Katayama, Seiji

    2007-01-01

    A gap is one of the most important issues to be solved in laser welding of a micro butt joint, because the gap results in welding defects such as underfilling or a non-bonded joint. In-process monitoring and adaptive control has been expected as one of the useful procedures for the stable production of sound laser welds without defects. The objective of this research is to evaluate the availability of in-process monitoring and adaptive control in micro butt welding of pure titanium rods with a pulsed neodymium : yttrium aluminium garnet (Nd : YAG) laser beam of a 150 μm spot diameter. It was revealed that a 45 μm narrow gap was detected by the remarkable jump in a reflected light intensity due to the formation of the molten pool which could bridge the gap. Heat radiation signal levels increased in proportion to the sizes of molten pools or penetration depths for the respective laser powers. As for adaptive control, the laser peak power was controlled on the basis of the reflected light or the heat radiation signals to stably produce a sound deeply penetrated weld reduced underfilling. In the case of a 100 μm gap, the underfilling was greatly reduced by half smaller than those made with a conventional rectangular pulse shape in seam welding as well as spot welding with a pulsed Nd : YAG laser beam. Consequently, the adaptive control of the laser peak power on the basis of in-process monitoring could reduce the harmful effects due to a gap in micro butt laser welding with a pulsed laser beam

  6. Identification of photoacoustic transients during pulsed laser ablation of the human temporal bone: an experimental model.

    Science.gov (United States)

    Wong, B J; Dickinson, M R; Berns, M W; Neev, J

    1996-12-01

    Laser ablation of hard tissues during neurotologic operations has been accomplished with continuous-wave (CW) lasers in the visible and midinfrared spectrum. The mechanism of ablation at these wavelengths is secondary to photothermal-induced tissue destruction. As a result, significant thermal damage to surrounding tissue may occur. Pulsed ultraviolet (UV) lasers have been suggested as an alternative to the argon, KTP-532, and CO2 lasers currently used in clinical practice. The pulse length of Excimer lasers are considerably shorter than the thermal diffusion time of bone tissue, and as a consequence thermal injury is minimal. This makes pulsed lasers an attractive tool for tissue ablation in the ear: in essence a "cold knife." However, the short pulse width of Excimer lasers (typically 10-150 ns) can create large thermoelastic stresses in the ablation specimen. This study identifies the presence of these photoacoustic waves during the Excimer laser treatment of the cadaveric human temporal bone. A XeCl (lambda = 308 nm, tau p = 12 ns) excimer laser was used to ablate hard tissue surrounding the oval window and facial ridge with energies of 75, 45, 25, and 12 mJ/pulse. Spot size was estimated to be 0.5 mm2. Custom high-frequency polyvinyldifluoride (PVDF) piezoelectric film transducers were fabricated and attached to the promontory, round window niche, and facial ridges. The signals were amplified using a low-noise preamplifier and recorded on a digitizing oscilloscope. Photoacoustic waves were clearly identified. Notably, large acoustic waves were measured on the promontory and on both sides of the facial ridge. The implications and clinical relevance of these findings is discussed and compared to findings obtained from a model system.

  7. Watermarking spot colors in packaging

    Science.gov (United States)

    Reed, Alastair; Filler, TomáÅ.¡; Falkenstern, Kristyn; Bai, Yang

    2015-03-01

    In January 2014, Digimarc announced Digimarc® Barcode for the packaging industry to improve the check-out efficiency and customer experience for retailers. Digimarc Barcode is a machine readable code that carries the same information as a traditional Universal Product Code (UPC) and is introduced by adding a robust digital watermark to the package design. It is imperceptible to the human eye but can be read by a modern barcode scanner at the Point of Sale (POS) station. Compared to a traditional linear barcode, Digimarc Barcode covers the whole package with minimal impact on the graphic design. This significantly improves the Items per Minute (IPM) metric, which retailers use to track the checkout efficiency since it closely relates to their profitability. Increasing IPM by a few percent could lead to potential savings of millions of dollars for retailers, giving them a strong incentive to add the Digimarc Barcode to their packages. Testing performed by Digimarc showed increases in IPM of at least 33% using the Digimarc Barcode, compared to using a traditional barcode. A method of watermarking print ready image data used in the commercial packaging industry is described. A significant proportion of packages are printed using spot colors, therefore spot colors needs to be supported by an embedder for Digimarc Barcode. Digimarc Barcode supports the PANTONE spot color system, which is commonly used in the packaging industry. The Digimarc Barcode embedder allows a user to insert the UPC code in an image while minimizing perceptibility to the Human Visual System (HVS). The Digimarc Barcode is inserted in the printing ink domain, using an Adobe Photoshop plug-in as the last step before printing. Since Photoshop is an industry standard widely used by pre-press shops in the packaging industry, a Digimarc Barcode can be easily inserted and proofed.

  8. Effect of the small-scale auxiliary laser spots on the 3ω0/2 harmonic emission

    International Nuclear Information System (INIS)

    Lin, Z.; Zhang, H.; He, X.; Lin, K.; Wang, X.; Zhuang, Y.; Wang, L.; Wei, X.; Lu, Q.; Shi, A.; Dai, M.; Tian, L.; Fan, G.; Li, J.

    1992-01-01

    Experiments have shown that a single 10-μm-radius laser spot is not able to produce the 90 degree side-emitted 3/2 harmonic efficiently in a preformed laser plasma. However, with the help of one or two auxiliary laser spots with a size similar to that of the main spot, the side-emitted 3/2 harmonic can frequently be detected when some positional and angular conditions for the auxiliary spots are met. The origin of these phenomena has been analyzed in terms of a proposed reflected laser photon-coupling model

  9. X-ray polarization studies of plasma focus experiments with a single hot spots

    International Nuclear Information System (INIS)

    Jakubowski, L.; Sadowski, M.J.; Baronova, E.O.

    2004-01-01

    In high current pulse discharges of the plasma focus (PF) type, inside the collapsing pinch column, there are formed local micro-regions of high-density and high-temperature plasma, so-called hot spots. Individual hot spots are separated in space and time. Each hot spot is characterized by its specific electron concentration and temperature, as well as by the emission of x-ray lines with different polarization. When numerous hot spots are produced it is impossible to determine local plasma parameters and to interpret the polarization effects. To eliminate this problem this study was devoted to the realization of PF-type discharges with single hot spot only. It has been achieved by a choice of the electrode configuration, which facilitated the formation of a single hot spot emitting intense x-ray lines. At the chosen experimental conditions it was possible to determine local plasma parameters and to demonstrate evident differences in the polarization of the observed x-ray lines. (author)

  10. Energy is not Coffee. An assessment of blind spots on energy spot-markets

    International Nuclear Information System (INIS)

    Jepma, C.J.; Spijker, E.; Van der Gaast, W.; De Jong, F.; Overmars, P.

    2006-01-01

    This study was to be the first in a series of studies on the title subject. It specifically focuses on the differences and similarities with a number of other spot-markets and aims to frame the energy spot markets and their potential development into a broader perspective. Main conclusion is that energy spot-markets differ from several other physical and non-physical spot-markets in many ways. This implies that 'perfect' energy spot-markets may inherently be (much) less perfect than other spot-markets that have approximated the stage of theoretical perfection

  11. Numerical analysis of breakdown dynamics dependence on pulse width in laser-induced damage in fused silica: Role of optical system

    Science.gov (United States)

    Hamam, Kholoud A.; Gamal, Yosr E. E.-D.

    2018-06-01

    We report a numerical investigation of the breakdown and damage in fused silica caused by ultra-short laser pulses. The study based on a modified model (Gaabour et al., 2012) that solves the rate equation numerically for the electron density evolution during the laser pulse, under the combined effect of both multiphoton and electron impact ionization processes. Besides, electron loss processes due to diffusion out of the focal volume and recombination are also considered in this analysis. The model is applied to investigate the threshold intensity dependence on laser pulse width in the experimental measurements that are given by Liu et al. (2005). In this experiment, a Ti-sapphire laser source operating at 800 nm with pulse duration varies between 240 fs and 2.5 ps is used to irradiate a bulk of fused silica with dimensions 10 × 5 × 3 mm. The laser beam was focused into the bulk using two optical systems with effective numerical apertures (NA) 0.126 and 0.255 to give beam spot radius at the focus of the order 2.0 μm and 0.95 μm respectively. Reasonable agreement between the calculated thresholds and the measured ones is attained. Moreover, a study is performed to examine the respective role of the physical processes of the breakdown of fused silica in relation to the pulse width and focusing optical system. The analysis revealed a real picture of the location and size of the generated plasma.

  12. Insights from ecological niche modeling on the taxonomic distinction and niche differentiation between the black-spotted and red-spotted tokay geckoes (Gekko gecko).

    Science.gov (United States)

    Zhang, Yueyun; Chen, Chongtao; Li, Li; Zhao, Chengjian; Chen, Weicai; Huang, Yong

    2014-09-01

    The black-spotted tokay and the red-spotted tokay are morphologically distinct and have largely allopatric distributions. The black-spotted tokay is characterized by a small body size and dark skin with sundry spots, while the red-spotted tokay has a relatively large body size and red spots. Based on morphological, karyotypic, genetic, and distribution differences, recent studies suggested their species status; however, their classifications remain controversial, and additional data such as ecological niches are necessary to establish firm hypotheses regarding their taxonomic status. We reconstructed their ecological niches models using climatic and geographic data. We then performed niche similarity tests (niche identity and background tests) and point-based analyses to explore whether ecological differentiation has occurred, and whether such differences are sufficient to explain the maintenance of their separate segments of environmental ranges. We found that both niche models of the black- and the red-spotted tokay had a good fit and a robust performance, as indicated by the high area under the curve (AUC) values ("black" = 0.982, SD = ± 0.002, "red" = 0.966 ± 0.02). Significant ecological differentiation across the entire geographic range was found, indicating that the involvement of ecological differentiation is important for species differentiation. Divergence along the environmental axes is highly associated with climatic conditions, with isothermality being important for the "black" form, while temperature seasonality, precipitation of warmest quarter, and annual temperature range together being important for the "red" form. These factors are likely important factors in niche differentiation between the two forms, which result in morphological replacement. Overall, beside morphological and genetic differentiation information, our results contribute to additional insights into taxonomic distinction and niche differentiation between the black- and the red-spotted

  13. Solar 'hot spots' are still hot

    Science.gov (United States)

    Bai, Taeil

    1990-01-01

    Longitude distributions of solar flares are not random but show evidence for active zones (or hot spots) where flares are concentrated. According to a previous study, two hot spots in the northern hemisphere, which rotate with a synodic period of about 26.72 days, produced the majority of major flares, during solar cycles 20 and 21. The more prominent of these two hot spots is found to be still active during the rising part of cycle 22, producing the majority of northern hemisphere major flares. The synodic rotation period of this hot spot is 26.727 + or - 0.007 days. There is also evidence for hot spots in the southern hemisphere. Two hot spots separated by 180 deg are found to rotate with a period of 29.407 days, with one of them having persisted in the same locations during cycles 19-22 and the other, during cycles 20-22.

  14. Solar hot spots are still hot

    International Nuclear Information System (INIS)

    Bai, T.

    1990-01-01

    Longitude distributions of solar flares are not random but show evidence for active zones (or hot spots) where flares are concentrated. According to a previous study, two hot spots in the northern hemisphere, which rotate with a synodic period of about 26.72 days, produced the majority of major flares, during solar cycles 20 and 21. The more prominent of these two hot spots is found to be still active during the rising part of cycle 22, producing the majority of northern hemisphere major flares. The synodic rotation period of this hot spot is 26.727 + or - 0.007 days. There is also evidence for hot spots in the southern hemisphere. Two hot spots separated by 180 deg are found to rotate with a period of 29.407 days, with one of them having persisted in the same locations during cycles 19-22 and the other, during cycles 20-22. 14 refs

  15. Spot and Runway Departure Advisor

    Science.gov (United States)

    Jung, Yoon Chul

    2013-01-01

    The Spot and Runway Departure Advisor (SARDA) is a research prototype of a decision support tool for ATC tower controllers to assist in manging and controlling traffic on the surface of an airport. SARDA employs a scheduler to generate an optimal runway schedule and gate push-back - spot release sequence and schedule that improves efficiency of surface operations. The advisories for ATC tower controllers are displayed on an Electronic Flight Strip (EFS) system. The human-in-the-loop simulation of the SARDA tool was conducted for east operations of Dallas-Ft. Worth International Airport (DFW) to evaluate performance of the SARDA tool and human factors, such as situational awareness and workload. The results indicates noticeable taxi delay reduction and fuel savings by using the SARDA tool. Reduction in controller workload were also observed throughout the scenario runs. The future plan includes modeling and simulation of the ramp operations of the Charlotte International Airport, and develop a decision support tool for the ramp controllers.

  16. X-ray spot filmer

    International Nuclear Information System (INIS)

    1975-01-01

    An X-ray apparatus is described which includes a spot filmer for feeding sheets of unexposed film one at a time into a vacuum evacuable cassette for exposure, and for returning exposed film sheets to an exposed film magazine. The spot filmer has a housing defining a light-tight enclosure. The film magazines are insertable through a door into the housing and into a film feed mechanism. The film feed mechanism unlatches, opens and positions the magazines; it then feeds a sheet of unexposed film into the vacuum evacuable cassette, releases the film sheet so the cassette can position the film sheet for exposure, and closes the film magazines. An orthogonal drive system positions the vacuum evacuable cassette to expose selected film sheet portions and returns the cassette to a retracted position. The film feed mechanism opens the magazines, feeds the exposed film sheet into the exposed film magazine, and closes the magazines. A film identification system is provided for forming an identifying image on a marginal portion of each film sheet

  17. Oil futures and spot markets

    International Nuclear Information System (INIS)

    Samii, M.V.

    1992-01-01

    In the last decade, the oil futures market has risen to prominence and has become a major factor in influencing oil market psychology and the crude oil market. On a normal day, over 92 thousand contracts, the equivalent of 92 million barrels per day, change hands on the New York Mercantile Exchange, NYMEX. This market has provided a vehicle for hedging against risk. At the same time, it has also created opportunities for speculation. Those who previously were unable to participate in oil market transactions can now become involved through the futures market. The large number of participants in the future market and the availability of information has made this market more efficient and transparent, relative to the crude oil market. While there has been considerable in-depth analysis of other future markets, relatively little theoretical attention has focused on that of oil. This paper looks at the following issues. First, what is the relationship between futures and spot oil prices? And secondly, are futures prices a good predictor of spot crude prices in the future? (author)

  18. Development of a Cardiovascular Simulator for Studying Pulse Diagnosis Mechanisms

    Directory of Open Access Journals (Sweden)

    Min Jang

    2017-01-01

    Full Text Available This research was undertaken to develop a cardiovascular simulator for use in the study of pulse diagnosis. The physical (i.e., pulse wave transmission and reflection and physiological (i.e., systolic and diastolic pressure, pulse pressure, and mean pressure characteristics of the radial pulse wave were reproduced by our simulator. The simulator consisted of an arterial component and a pulse-generating component. Computer simulation was used to simplify the arterial component while maintaining the elastic modulus and artery size. To improve the reflected wave characteristics, a palmar arch was incorporated within the simulator. The simulated radial pulse showed good agreement with clinical data.

  19. Generation and focusing of high energy, 35-kA electron beams for pulsed-diode radiographic machines: Theory and experiment

    International Nuclear Information System (INIS)

    Carlson, R.L.; George, M.J.; Hughes, T.P.; Welch, D.R.

    1993-01-01

    Cathode ball and anode planar-foil geometries used to generate self-focused beams onto x-ray conversion targets via beam-induced ionization in gas cells have been investigated since the early 1970's by J. C. Martin et al at Aldermaston, U.K. The building of a succession of increasingly higher voltage, pulsed-diode machines tailored for flash x radiography has resulted. Given sufficient dose to penetrate an object, the spot size of the x-ray source generally determines the resolution of a radiograph. Reported are particle-in-cell code simulations applied to beam generation in the A-K gap and the self-focusing onto the target. A Monte Carlo code for neutron, photon, and electron transport converts the beam particles at the target to photons with transport to a film plane used to calculate the spot size. Comparisons are made to experiments using the Ector (3.5--4 MeV) and PIXY (4--8 MeV) pulsed-diode radiographic machines at Los Alamos

  20. Ionospheric hot spot at high latitudes

    International Nuclear Information System (INIS)

    Schunk, R.W.; Sojka, J.J.

    1982-01-01

    A hot spot (or spots) can occur in the high-latitude ionosphere depending on the plasma convection pattern. The hot spot corresponds to a small magnetic local time-magnetic latitude region of elevated ion temperatures located near the dusk and/or dawn meridians. For asymmetric convection electric field patterns, with enhanced flow in either the dusk or dawn sector of the polar cap, a single hot spot should occur in association with the strong convection cell. However, on geomagnetically disturbed days, two strong convection cells can occur, and hence, two hot spots should exist. The hot spot should be detectable when the electric field in the strong convection cell exceeds about 40 mV m -1 . For electric fields of the order of 100 mV m -1 in the convection cell, the ion temperature in the hot spot is greatest at low altitudes, reaching 4000 0 K at 160 km, and decreases with altitude in the F-region. An ionospheric hot spot (or spots) can be expected at all seasons and for a wide range of solar cycle conditions

  1. Impact of grain sizes on the quantitative concrete analysis using laser-induced breakdown spectroscopy

    Science.gov (United States)

    Gottlieb, C.; Günther, T.; Wilsch, G.

    2018-04-01

    In civil engineering concrete is the most used building material for making infrastructures like bridges and parking decks worldwide. It is as a porous and multiphase material made of aggregates with a defined grain size distribution, cement and water as well as different additives and admixtures depending on the application. Different grain sizes are important to ensure the needed density and compressive strength. The resulting porous cement matrix contains a mixture of flour grains (aggregates with a grain size below 125 μm) and cement particles (particle size ≈ 50μm). Harmful species like chlorides may penetrate together with water through the capillary pore space and may trigger different damage processes. The damage assessment of concrete structures in Germany is estimated due to the quantification of harmful elements regarding to the cement content only. In the evaluation of concrete using LIBS a two-dimensional scanning is necessary to consider the heterogeneity caused by the aggregates. Therefore, a LIBS system operating with a low energy NdCr:YAG laser, a pulse energy of 3 mJ, a wavelength of 1064 nm, a pulse width of 1.5 ns and a repetition rate of 100 Hz has been used. Different Czerny-Turner spectrometers with CCD detectors in the UV and NIR range have been used for the detection. Large aggregates (macro-heterogeneity) can be excluded from the evaluation, whereas small aggregates in the range of the laser spot size (flour grains) cannot be spatially resolved. In this work the micro heterogeneity caused by flour grains and their impact on the quantification with LIBS will be discussed. To analyze the effect of changing grain sizes and ratios, the ablation behavior has been determined and compared. Samples with defined grain sizes were made and analyzed using LIBS. The grain size distributions were analyzed with laser diffraction (LDA).

  2. Failure mode transition in AHSS resistance spot welds. Part I. Controlling factors

    International Nuclear Information System (INIS)

    Pouranvari, M.; Marashi, S.P.H.

    2011-01-01

    Highlights: → Interfacial to pullout failure mode transition for AHSS RSWs is studied. → An analytical mode is proposed to predict failure mode of AHSS RSWs. → Hardness characteristics of RSWs plays key role in the failure mode transition. - Abstract: Failure mode of resistance spot welds is a qualitative indicator of weld performance. Two major types of spot weld failure are pull-out and interfacial fracture. Interfacial failure, which typically results in reduced energy absorption capability, is considered unsatisfactory and industry standards are often designed to avoid this occurrence. Advanced High Strength Steel (AHSS) spot welds exhibit high tendency to fail in interfacial failure mode. Sizing of spot welds based on the conventional recommendation of 4t 0.5 (t is sheet thickness) does not guarantee the pullout failure mode in many cases of AHSS spot welds. Therefore, a new weld quality criterion should be found for AHSS resistance spot welds to guarantee pull-out failure. The aim of this paper is to investigate and analyze the transition between interfacial and pull-out failure modes in AHSS resistance spot welds during the tensile-shear test by the use of analytical approach. In this work, in the light of failure mechanism, a simple analytical model is presented for estimating the critical fusion zone size to prevent interfacial fracture. According to this model, the hardness ratio of fusion zone to pull-out failure location and the volume fraction of voids in fusion zone are the key metallurgical factors governing type of failure mode of AHSS spot welds during the tensile-shear test. Low hardness ratio and high susceptibility to form shrinkage voids in the case of AHSS spot welds appear to be the two primary causes for their high tendency to fail in interfacial mode.

  3. Matrix phased array (MPA) imaging technology for resistance spot welds

    Science.gov (United States)

    Na, Jeong K.; Gleeson, Sean T.

    2014-02-01

    A three-dimensional MPA probe has been incorporated with a high speed phased array electronic board to visualize nugget images of resistance spot welds. The primary application area of this battery operated portable MPA ultrasonic imaging system is in the automotive industry which a conventional destructive testing process is commonly adopted to check the quality of resistance spot welds in auto bodies. Considering an average of five-thousand spot welds in a medium size passenger vehicle, the amount of time and effort given to popping the welds and measuring nugget size are immeasurable in addition to the millions of dollars' worth of scrap metals recycled per plant per year. This wasteful labor intensive destructive testing process has become less reliable as auto body sheet metal has transitioned from thick and heavy mild steels to thin and light high strength steels. Consequently, the necessity of developing a non-destructive inspection methodology has become inevitable. In this paper, the fundamental aspects of the current 3-D probe design, data acquisition algorithms, and weld nugget imaging process are discussed.

  4. Matrix phased array (MPA) imaging technology for resistance spot welds

    International Nuclear Information System (INIS)

    Na, Jeong K.; Gleeson, Sean T.

    2014-01-01

    A three-dimensional MPA probe has been incorporated with a high speed phased array electronic board to visualize nugget images of resistance spot welds. The primary application area of this battery operated portable MPA ultrasonic imaging system is in the automotive industry which a conventional destructive testing process is commonly adopted to check the quality of resistance spot welds in auto bodies. Considering an average of five-thousand spot welds in a medium size passenger vehicle, the amount of time and effort given to popping the welds and measuring nugget size are immeasurable in addition to the millions of dollars' worth of scrap metals recycled per plant per year. This wasteful labor intensive destructive testing process has become less reliable as auto body sheet metal has transitioned from thick and heavy mild steels to thin and light high strength steels. Consequently, the necessity of developing a non-destructive inspection methodology has become inevitable. In this paper, the fundamental aspects of the current 3-D probe design, data acquisition algorithms, and weld nugget imaging process are discussed

  5. Matrix phased array (MPA) imaging technology for resistance spot welds

    Energy Technology Data Exchange (ETDEWEB)

    Na, Jeong K.; Gleeson, Sean T. [Edison Welding Institute, 1250 Arthur E. Adams Drive, Columbus, OH 43221 (United States)

    2014-02-18

    A three-dimensional MPA probe has been incorporated with a high speed phased array electronic board to visualize nugget images of resistance spot welds. The primary application area of this battery operated portable MPA ultrasonic imaging system is in the automotive industry which a conventional destructive testing process is commonly adopted to check the quality of resistance spot welds in auto bodies. Considering an average of five-thousand spot welds in a medium size passenger vehicle, the amount of time and effort given to popping the welds and measuring nugget size are immeasurable in addition to the millions of dollars' worth of scrap metals recycled per plant per year. This wasteful labor intensive destructive testing process has become less reliable as auto body sheet metal has transitioned from thick and heavy mild steels to thin and light high strength steels. Consequently, the necessity of developing a non-destructive inspection methodology has become inevitable. In this paper, the fundamental aspects of the current 3-D probe design, data acquisition algorithms, and weld nugget imaging process are discussed.

  6. Butterfly Wings Are Three-Dimensional: Pupal Cuticle Focal Spots and Their Associated Structures in Junonia Butterflies.

    Science.gov (United States)

    Taira, Wataru; Otaki, Joji M

    2016-01-01

    Butterfly wing color patterns often contain eyespots, which are developmentally determined at the late larval and early pupal stages by organizing activities of focal cells that can later form eyespot foci. In the pupal stage, the focal position of a future eyespot is often marked by a focal spot, one of the pupal cuticle spots, on the pupal surface. Here, we examined the possible relationships of the pupal focal spots with the underneath pupal wing tissues and with the adult wing eyespots using Junonia butterflies. Large pupal focal spots were found in two species with large adult eyespots, J. orithya and J. almana, whereas only small pupal focal spots were found in a species with small adult eyespots, J. hedonia. The size of five pupal focal spots on a single wing was correlated with the size of the corresponding adult eyespots in J. orithya. A pupal focal spot was a three-dimensional bulge of cuticle surface, and the underside of the major pupal focal spot exhibited a hollowed cuticle in a pupal case. Cross sections of a pupal wing revealed that the cuticle layer shows a curvature at a focal spot, and a positional correlation was observed between the cuticle layer thickness and its corresponding cell layer thickness. Adult major eyespots of J. orithya and J. almana exhibited surface elevations and depressions that approximately correspond to the coloration within an eyespot. Our results suggest that a pupal focal spot is produced by the organizing activity of focal cells underneath the focal spot. Probably because the focal cell layer immediately underneath a focal spot is thicker than that of its surrounding areas, eyespots of adult butterfly wings are three-dimensionally constructed. The color-height relationship in adult eyespots might have an implication in the developmental signaling for determining the eyespot color patterns.

  7. Butterfly Wings Are Three-Dimensional: Pupal Cuticle Focal Spots and Their Associated Structures in Junonia Butterflies.

    Directory of Open Access Journals (Sweden)

    Wataru Taira

    Full Text Available Butterfly wing color patterns often contain eyespots, which are developmentally determined at the late larval and early pupal stages by organizing activities of focal cells that can later form eyespot foci. In the pupal stage, the focal position of a future eyespot is often marked by a focal spot, one of the pupal cuticle spots, on the pupal surface. Here, we examined the possible relationships of the pupal focal spots with the underneath pupal wing tissues and with the adult wing eyespots using Junonia butterflies. Large pupal focal spots were found in two species with large adult eyespots, J. orithya and J. almana, whereas only small pupal focal spots were found in a species with small adult eyespots, J. hedonia. The size of five pupal focal spots on a single wing was correlated with the size of the corresponding adult eyespots in J. orithya. A pupal focal spot was a three-dimensional bulge of cuticle surface, and the underside of the major pupal focal spot exhibited a hollowed cuticle in a pupal case. Cross sections of a pupal wing revealed that the cuticle layer shows a curvature at a focal spot, and a positional correlation was observed between the cuticle layer thickness and its corresponding cell layer thickness. Adult major eyespots of J. orithya and J. almana exhibited surface elevations and depressions that approximately correspond to the coloration within an eyespot. Our results suggest that a pupal focal spot is produced by the organizing activity of focal cells underneath the focal spot. Probably because the focal cell layer immediately underneath a focal spot is thicker than that of its surrounding areas, eyespots of adult butterfly wings are three-dimensionally constructed. The color-height relationship in adult eyespots might have an implication in the developmental signaling for determining the eyespot color patterns.

  8. Repetitively pulsed, high energy KrF lasers for inertial fusion energy

    International Nuclear Information System (INIS)

    Myers, M.C.; Sethian, J.D.; Giuliani, J.L.; Lehmberg, R.; Kepple, P.; Wolford, M.F.; Hegeler, F.; Friedman, M.; Jones, T.C.; Swanekamp, S.B.; Weidenheimer, D.; Rose, D.

    2004-01-01

    Krypton fluoride (KrF) lasers produce highly uniform beams at 248 nm, allow the capability of 'zooming' the spot size to follow an imploding pellet, naturally assume a modular architecture and have been developed into a pulsed-power- based industrial technology that readily scales to a fusion power plant sized system. There are two main challenges for the fusion power plant application: to develop a system with an overall efficiency of greater than 6% (based on target gains of 100) and to achieve a durability of greater than 3 x 10 8 shots (two years at 5 Hz). These two issues are being addressed with the Electra (700 J, 5 Hz) and Nike (3000 J, single shot) KrF lasers at the Naval Research Laboratory. Based on recent advances in pulsed power, electron beam generation and transport, hibachi (foil support structure) design and KrF physics, wall plug efficiencies of greater than 7% should be achievable. Moreover, recent experiments show that it may be possible to realize long lived electron beam diodes using ceramic honeycomb cathodes and anode foils that are convectively cooled by periodically deflecting the laser gas. This paper is a summary of the progress in the development of the critical KrF technologies for laser fusion energy. (author)

  9. Laser modification of silica, simulating pulse shape and length

    International Nuclear Information System (INIS)

    Corrales, L. Rene; Moore, Emily

    2009-01-01

    Computer simulations of instantaneous thermal heating due to a laser pulse is modeled as a pulse occurring over 1 or 100 fs, during which time the atoms within a cylinder are given excess kinetic energy to mimic the effect of adding energy locally to a system by a laser. The response of the material under conditions in which a similar amount of energy is dumped within 1 fs versus over a 100 fs pulse with two distinct shapes, square and Gaussian-like, is explored. Key physics disclosed is that with a pulse width of 100 fs, as the energy is being added it begins to dissipate away from region where it is added. With a 1 fs (instantaneous) pulse there is greater initial ballistic behavior than when it is dumped over a 100 fs period. In the latter, there are localized hot spots displaying ballistic behavior.

  10. Pulse compressor with aberration correction

    Energy Technology Data Exchange (ETDEWEB)

    Mankos, Marian [Electron Optica, Inc., Palo Alto, CA (United States)

    2015-11-30

    In this SBIR project, Electron Optica, Inc. (EOI) is developing an electron mirror-based pulse compressor attachment to new and retrofitted dynamic transmission electron microscopes (DTEMs) and ultrafast electron diffraction (UED) cameras for improving the temporal resolution of these instruments from the characteristic range of a few picoseconds to a few nanoseconds and beyond, into the sub-100 femtosecond range. The improvement will enable electron microscopes and diffraction cameras to better resolve the dynamics of reactions in the areas of solid state physics, chemistry, and biology. EOI’s pulse compressor technology utilizes the combination of electron mirror optics and a magnetic beam separator to compress the electron pulse. The design exploits the symmetry inherent in reversing the electron trajectory in the mirror in order to compress the temporally broadened beam. This system also simultaneously corrects the chromatic and spherical aberration of the objective lens for improved spatial resolution. This correction will be found valuable as the source size is reduced with laser-triggered point source emitters. With such emitters, it might be possible to significantly reduce the illuminated area and carry out ultrafast diffraction experiments from small regions of the sample, e.g. from individual grains or nanoparticles. During phase I, EOI drafted a set of candidate pulse compressor architectures and evaluated the trade-offs between temporal resolution and electron bunch size to achieve the optimum design for two particular applications with market potential: increasing the temporal and spatial resolution of UEDs, and increasing the temporal and spatial resolution of DTEMs. Specialized software packages that have been developed by MEBS, Ltd. were used to calculate the electron optical properties of the key pulse compressor components: namely, the magnetic prism, the electron mirror, and the electron lenses. In the final step, these results were folded

  11. Treatment of port-wine stains with flash lamp pumped pulsed dye laser on Indian skin: A six year study

    Directory of Open Access Journals (Sweden)

    Chandroth Ponnambath Thajudheen

    2014-01-01

    Full Text Available Context: Port-wine stain (PWS is one of the commonly encountered congenital cutaneous vascular lesions, with an equal sex distribution. Pulsed dye lasers (PDL have revolutionized the treatment of both congential and acquired cutaneous vascular lesions. The pulsed dye lasers owing to its superior efficacy and safety profile have become the gold standard for the management of port-wine stains. Aims: To evaluate the efficacy and side effects of pulsed dye laser for the management of Port-wine stain on Indian skin. Materials and Methods: Seventy five patients of Fitzpatrick skin types IV&V with PWS underwent multiple treatments with PDL (V beam-Candela over a period of six years at monthly intervals. Laser parameters were wavelength 595nm, spot sizes 7-10mm, fluence 6-12 j/cm2, pulse duration 0.45-10ms, along with cryogen cooling. Serial photographs were taken before and after every session. Clinical improvement scores of comparable photographs using a quartile grading (o=80% were judged independently by two dermatologists after the series of treatment. Minimum number of treatments was 6 and maximum 17.They were followed up at six monthly intervals to observe re darkening of PWS. Results: No patient showed total clearance.Grade3 improvement was observed in 70 % of children and 50% of adults after 8-10 sessions. Children showed better and faster response than adults. Thirty percent of patients developed post inflammatory hyper pigmentation which resolved over a period of six to eight weeks. Two patients had superficial scarring due to stacking of pulses. None of the patients showed re darkening of PWS till now. Conclusion: Pulsed dye laser is an effective and safe treatment for port-wine stain in Indian skin.

  12. Random pulse generator

    International Nuclear Information System (INIS)

    Guo Ya'nan; Jin Dapeng; Zhao Dixin; Liu Zhen'an; Qiao Qiao; Chinese Academy of Sciences, Beijing

    2007-01-01

    Due to the randomness of radioactive decay and nuclear reaction, the signals from detectors are random in time. But normal pulse generator generates periodical pulses. To measure the performances of nuclear electronic devices under random inputs, a random generator is necessary. Types of random pulse generator are reviewed, 2 digital random pulse generators are introduced. (authors)

  13. Measurements of three dimensional residual stress distribution on laser irradiated spot

    International Nuclear Information System (INIS)

    Tanaka, Hirotomo; Akita, Koichi; Ohya, Shin-ichi; Sano, Yuji; Naito, Hideki

    2004-01-01

    Three dimensional residual stress distributions on laser irradiated spots were measured using synchrotron radiation to study the basic mechanism of laser peening. A water-immersed sample of high tensile strength steel was irradiated with Q-switched and frequency-doubled Nd:YAG laser. The residual stress depth profile of the sample was obtained by alternately repeating the measurement and surface layer removal by electrolytic polishing. Tensile residual stresses were observed on the surface of all irradiated spots, whereas residual stress changed to compressive just beneath the surface. The depth of compressive residual stress imparted by laser irradiation and plastic deformation zone increased with increasing the number of laser pulses irradiated on the same spot. (author)

  14. Dependence of high order harmonics intensity on laser focal spot position in preformed plasma plumes

    International Nuclear Information System (INIS)

    Singhal, H.; Ganeev, R.; Naik, P. A.; Arora, V.; Chakravarty, U.; Gupta, P. D.

    2008-01-01

    The dependence of the high-order harmonic intensity on the laser focal spot position in laser produced plasma plumes is experimentally studied. High order harmonics up to the 59th order (λ∼13.5 nm) were generated by focusing 48 fs laser pulses from a Ti:sapphire laser system in silver plasma plume produced using 300 ps uncompressed laser radiation as the prepulse. The intensity of harmonics nearly vanished when the best focus was located in the plume center, whereas it peaked on either side with unequal intensity. The focal spot position corresponding to the peak harmonic intensity moved away from the plume center for higher order harmonics. The results are explained in terms of the variation of phase mismatch between the driving laser beam and harmonics radiation produced, relativistic drift of electrons, and defocusing effect due to radial ionization gradient in the plasma for different focal spot positions

  15. Programmable pulse generator

    International Nuclear Information System (INIS)

    Xue Zhihua; Lou Binqiao; Duan Xiaohui

    2002-01-01

    The author introduces the design of programmable pulse generator that is based on a micro-controller and controlled by RS232 interface of personal computer. The whole system has good stability. The pulse generator can produce TTL pulse and analog pulse. The pulse frequency can be selected by EPLD. The voltage amplitude and pulse width of analog pulse can be adjusted by analog switches and digitally-controlled potentiometers. The software development tools of computer is National Instruments LabView5.1. The front panel of this virtual instrumentation is intuitive and easy-to-use. Parameters can be selected and changed conveniently by knob and slide

  16. Birth-jump processes and application to forest fire spotting.

    Science.gov (United States)

    Hillen, T; Greese, B; Martin, J; de Vries, G

    2015-01-01

    Birth-jump models are designed to describe population models for which growth and spatial spread cannot be decoupled. A birth-jump model is a nonlinear integro-differential equation. We present two different derivations of this equation, one based on a random walk approach and the other based on a two-compartmental reaction-diffusion model. In the case that the redistribution kernels are highly concentrated, we show that the integro-differential equation can be approximated by a reaction-diffusion equation, in which the proliferation rate contributes to both the diffusion term and the reaction term. We completely solve the corresponding critical domain size problem and the minimal wave speed problem. Birth-jump models can be applied in many areas in mathematical biology. We highlight an application of our results in the context of forest fire spread through spotting. We show that spotting increases the invasion speed of a forest fire front.

  17. Analysis of microstructure-dependent shock dissipation and hot-spot formation in granular metalized explosive

    Science.gov (United States)

    Chakravarthy, Sunada; Gonthier, Keith A.

    2016-07-01

    Variations in the microstructure of granular explosives (i.e., particle packing density, size, shape, and composition) can affect their shock sensitivity by altering thermomechanical fields at the particle-scale during pore collapse within shocks. If the deformation rate is fast, hot-spots can form, ignite, and interact, resulting in burn at the macro-scale. In this study, a two-dimensional finite and discrete element technique is used to simulate and examine shock-induced dissipation and hot-spot formation within low density explosives (68%-84% theoretical maximum density (TMD)) consisting of large ensembles of HMX (C4H8N8O8) and aluminum (Al) particles (size ˜ 60 -360 μm). Emphasis is placed on identifying how the inclusion of Al influences effective shock dissipation and hot-spot fields relative to equivalent ensembles of neat/pure HMX for shocks that are sufficiently strong to eliminate porosity. Spatially distributed hot-spot fields are characterized by their number density and area fraction enabling their dynamics to be described in terms of nucleation, growth, and agglomeration-dominated phases with increasing shock strength. For fixed shock particle speed, predictions indicate that decreasing packing density enhances shock dissipation and hot-spot formation, and that the inclusion of Al increases dissipation relative to neat HMX by pressure enhanced compaction resulting in fewer but larger HMX hot-spots. Ensembles having bimodal particle sizes are shown to significantly affect hot-spot dynamics by altering the spatial distribution of hot-spots behind shocks.

  18. Cosmicflows-3: Cold Spot Repeller?

    Energy Technology Data Exchange (ETDEWEB)

    Courtois, Hélène M.; Graziani, Romain; Dupuy, Alexandra [University of Lyon, UCB Lyon 1, CNRS/IN2P3, IPN, Lyon (France); Tully, R. Brent [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Hoffman, Yehuda [Racah Institute of Physics, Hebrew University, Jerusalem, 91904 (Israel); Pomarède, Daniel [Institut de Recherche sur les Lois Fondamentales de l’Univers, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette (France)

    2017-09-20

    The three-dimensional gravitational velocity field within z ∼ 0.1 has been modeled with the Wiener filter methodology applied to the Cosmicflows-3 compilation of galaxy distances. The dominant features are a basin of attraction and two basins of repulsion. The major basin of attraction is an extension of the Shapley concentration of galaxies. One basin of repulsion, the Dipole Repeller, is located near the anti-apex of the cosmic microwave background dipole. The other basin of repulsion is in the proximate direction toward the “Cold Spot” irregularity in the cosmic microwave background. It has been speculated that a vast void might contribute to the amplitude of the Cold Spot from the integrated Sachs–Wolfe effect.

  19. Single- and multi-pulse femtosecond laser ablation of optical filter materials

    International Nuclear Information System (INIS)

    Krueger, J.; Lenzner, M.; Martin, S.; Lenner, M.; Spielmann, C.; Fiedler, A.; Kautek, W.

    2003-01-01

    Ablation experiments employing Ti:sapphire laser pulses with durations from 30 to 340 fs (centre wavelength 800 nm, repetition rate 1 kHz) were performed in air. Absorbing filters (Schott BG18 and BG36) served as targets. The direct focusing technique was used under single- and multi-pulse irradiation conditions. Ablation threshold fluences were determined from a semi-logarithmic plot of the ablation crater diameter versus laser fluence. The threshold fluence decreases for a shorter pulse duration and an increasing number of pulses. The multi-pulse ablation threshold fluences are similar to those of undoped glass material (∼1 J cm -2 ). That means that the multi-pulse ablation threshold is independent on the doping level of the filters. For more than 100 pulses per spot and all pulse durations applied, the threshold fluence is practically constant. This leads to technically relevant ablation threshold values

  20. Fabrication of Pt nanowires with a diffraction-unlimited feature size by high-threshold lithography

    International Nuclear Information System (INIS)

    Li, Li; Zhang, Ziang; Yu, Miao; Song, Zhengxun; Weng, Zhankun; Wang, Zuobin; Li, Wenjun; Wang, Dapeng; Zhao, Le; Peng, Kuiqing

    2015-01-01

    Although the nanoscale world can already be observed at a diffraction-unlimited resolution using far-field optical microscopy, to make the step from microscopy to lithography still requires a suitable photoresist material system. In this letter, we consider the threshold to be a region with a width characterized by the extreme feature size obtained using a Gaussian beam spot. By narrowing such a region through improvement of the threshold sensitization to intensity in a high-threshold material system, the minimal feature size becomes smaller. By using platinum as the negative photoresist, we demonstrate that high-threshold lithography can be used to fabricate nanowire arrays with a scalable resolution along the axial direction of the linewidth from the micro- to the nanoscale using a nanosecond-pulsed laser source with a wavelength λ 0  = 1064 nm. The minimal feature size is only several nanometers (sub λ 0 /100). Compared with conventional polymer resist lithography, the advantages of high-threshold lithography are sharper pinpoints of laser intensity triggering the threshold response and also higher robustness allowing for large area exposure by a less-expensive nanosecond-pulsed laser

  1. Spot Sign in Acute Intracerebral Hemorrhage in Dynamic T1-Weighted Magnetic Resonance Imaging.

    Science.gov (United States)

    Schindlbeck, Katharina A; Santaella, Anna; Galinovic, Ivana; Krause, Thomas; Rocco, Andrea; Nolte, Christian H; Villringer, Kersten; Fiebach, Jochen B

    2016-02-01

    In computed tomographic imaging of acute intracerebral hemorrhage spot sign on computed tomographic angiography has been established as a marker for hematoma expansion and poor clinical outcome. Although, magnetic resonance imaging (MRI) can accurately visualize acute intracerebral hemorrhage, a corresponding MRI marker is lacking to date. We prospectively examined 50 consecutive patients with acute intracerebral hemorrhage within 24 hours of symptom onset. The MRI protocol consisted of a standard stroke protocol and dynamic contrast-enhanced T1-weighted imaging with a time resolution of 7.07 s/batch. Stroke scores were assessed at admission and at time of discharge. Volume measurements of hematoma size and spot sign were performed with MRIcron. Contrast extravasation within sites of the hemorrhage (MRI spot sign) was seen in 46% of the patients. Patients with an MRI spot sign had a significantly shorter time to imaging than those without (Pspot sign compared with those without (P≤0.001). Hematoma expansion was observed in the spot sign group compared with the nonspot sign group, although the differences were not significant. Spot sign can be detected using MRI on postcontrast T1-weighted and dynamic T1-weighted images. It is associated with worse clinical outcome. The time course of contrast extravasation in dynamic T1 images indicates that these spots represent ongoing bleeding. © 2015 American Heart Association, Inc.

  2. Consistent melanophore spot patterns allow long-term individual recognition of Atlantic salmon Salmo salar.

    Science.gov (United States)

    Stien, L H; Nilsson, J; Bui, S; Fosseidengen, J E; Kristiansen, T S; Øverli, Ø; Folkedal, O

    2017-12-01

    The present study shows that permanent melanophore spot patterns in Atlantic salmon Salmo salar make it possible to use images of the operculum to keep track of individual fish over extended periods of their life history. Post-smolt S. salar (n = 246) were initially photographed at an average mass of 98 g and again 10 months later after rearing in a sea cage, at an average mass of 3088 g. Spots that were present initially remained and were the most overt (largest) 10 months later, while new and less overt spots had developed. Visual recognition of spot size and position showed that fish with at least four initial spots were relatively easy to identify, while identifying fish with less than four spots could be challenging. An automatic image analysis method was developed and shows potential for fast match processing of large numbers of fish. The current findings promote visual recognition of opercular spots as a welfare-friendly alternative to tagging in experiments involving salmonid fishes. © The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of The Fisheries Society of the British Isles.

  3. 7 CFR 28.412 - Strict Middling Light Spotted Color.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Strict Middling Light Spotted Color. 28.412 Section 28... Light Spotted Color. Strict Middling Light Spotted Color is color which in spot or color, or both, is between Strict Middling Color and Strict Middling Spotted Color. ...

  4. 7 CFR 28.415 - Low Middling Light Spotted Color.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Low Middling Light Spotted Color. 28.415 Section 28... Spotted Color. Low Middling Light Spotted Color is color which in spot or color, or both, is between Low Middling Color and Low Middling Spotted Color. ...

  5. 7 CFR 28.411 - Good Middling Light Spotted Color.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Good Middling Light Spotted Color. 28.411 Section 28... Light Spotted Color. Good Middling Light Spotted Color is color which in spot or color, or both, is between Good Middling Color and Good Middling Spotted Color. ...

  6. 7 CFR 28.413 - Middling Light Spotted Color.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Middling Light Spotted Color. 28.413 Section 28.413... Spotted Color. Middling Light Spotted Color is color which in spot or color, or both, is between Middling Color and Middling Spotted Color. ...

  7. Submicron hollow spot generation by solid immersion lens and structured illumination

    International Nuclear Information System (INIS)

    Kim, M-S; Scharf, T; Herzig, H P; Assafrao, A C; Wachters, A J H; Pereira, S F; Urbach, H P; Brun, M; Olivier, S; Nicoletti, S

    2012-01-01

    We report on the experimental and numerical demonstration of immersed submicron-size hollow focused spots, generated by structuring the polarization state of an incident light beam impinging on a micro-size solid immersion lens (μ-SIL) made of SiO 2 . Such structured focal spots are characterized by a doughnut-shaped intensity distribution, whose central dark region is of great interest for optical trapping of nano-size particles, super-resolution microscopy and lithography. In this work, we have used a high-resolution interference microscopy technique to measure the structured immersed focal spots, whose dimensions were found to be significantly reduced due to the immersion effect of the μ-SIL. In particular, a reduction of 37% of the dark central region was verified. The measurements were compared with a rigorous finite element method model for the μ-SIL, revealing excellent agreement between them. (paper)

  8. Hot Spot Removal System: System description

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-09-01

    Hazardous wastes contaminated with radionuclides, chemicals, and explosives exist across the Department of Energy complex and need to be remediated due to environmental concerns. Currently, an opportunity is being developed to dramatically reduce remediation costs and to assist in the acceleration of schedules associated with these wastes by deploying a Hot Spot Removal System. Removing the hot spot from the waste site will remove risk driver(s) and enable another, more cost effective process/option/remedial alternative (i.e., capping) to be applied to the remainder of the site. The Hot Spot Removal System consists of a suite of technologies that will be utilized to locate and remove source terms. Components of the system can also be used in a variety of other cleanup activities. This Hot Spot Removal System Description document presents technologies that were considered for possible inclusion in the Hot Spot Removal System, technologies made available to the Hot Spot Removal System, industrial interest in the Hot Spot Removal System`s subsystems, the schedule required for the Hot Spot Removal System, the evaluation of the relevant technologies, and the recommendations for equipment and technologies as stated in the Plan section.

  9. Rocky Mountain spotted fever in children.

    Science.gov (United States)

    Woods, Charles R

    2013-04-01

    Rocky Mountain spotted fever is typically undifferentiated from many other infections in the first few days of illness. Treatment should not be delayed pending confirmation of infection when Rocky Mountain spotted fever is suspected. Doxycycline is the drug of choice even for infants and children less than 8 years old. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Rocky Mountain Spotted Fever: Statistics and Epidemiology

    Science.gov (United States)

    ... Search Form Controls Cancel Submit Search the CDC Rocky Mountain Spotted Fever (RMSF) Note: Javascript is disabled or is not ... message, please visit this page: About CDC.gov . Rocky Mountain Spotted Fever (RMSF) Transmission Signs and Symptoms Diagnosis and Testing ...

  11. Hot Spot Removal System: System description

    International Nuclear Information System (INIS)

    1997-09-01

    Hazardous wastes contaminated with radionuclides, chemicals, and explosives exist across the Department of Energy complex and need to be remediated due to environmental concerns. Currently, an opportunity is being developed to dramatically reduce remediation costs and to assist in the acceleration of schedules associated with these wastes by deploying a Hot Spot Removal System. Removing the hot spot from the waste site will remove risk driver(s) and enable another, more cost effective process/option/remedial alternative (i.e., capping) to be applied to the remainder of the site. The Hot Spot Removal System consists of a suite of technologies that will be utilized to locate and remove source terms. Components of the system can also be used in a variety of other cleanup activities. This Hot Spot Removal System Description document presents technologies that were considered for possible inclusion in the Hot Spot Removal System, technologies made available to the Hot Spot Removal System, industrial interest in the Hot Spot Removal System''s subsystems, the schedule required for the Hot Spot Removal System, the evaluation of the relevant technologies, and the recommendations for equipment and technologies as stated in the Plan section

  12. Pulsed water jet generated by pulse multiplication

    Czech Academy of Sciences Publication Activity Database

    Dvorský, R.; Sitek, Libor; Sochor, T.

    2016-01-01

    Roč. 23, č. 4 (2016), s. 959-967 ISSN 1330-3651 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : high- pressure pulses * pulse intensifier * pulsed water jet * water hammer effect Subject RIV: JQ - Machines ; Tools Impact factor: 0.723, year: 2016 http://hrcak.srce.hr/163752?lang=en

  13. Finite Cosmology and a CMB Cold Spot

    Energy Technology Data Exchange (ETDEWEB)

    Adler, R.J.; /Stanford U., HEPL; Bjorken, J.D.; /SLAC; Overduin, J.M.; /Stanford U., HEPL

    2006-03-20

    The standard cosmological model posits a spatially flat universe of infinite extent. However, no observation, even in principle, could verify that the matter extends to infinity. In this work we model the universe as a finite spherical ball of dust and dark energy, and obtain a lower limit estimate of its mass and present size: the mass is at least 5 x 10{sup 23}M{sub {circle_dot}} and the present radius is at least 50 Gly. If we are not too far from the dust-ball edge we might expect to see a cold spot in the cosmic microwave background, and there might be suppression of the low multipoles in the angular power spectrum. Thus the model may be testable, at least in principle. We also obtain and discuss the geometry exterior to the dust ball; it is Schwarzschild-de Sitter with a naked singularity, and provides an interesting picture of cosmogenesis. Finally we briefly sketch how radiation and inflation eras may be incorporated into the model.

  14. Laser Spot Detection Based on Reaction Diffusion.

    Science.gov (United States)

    Vázquez-Otero, Alejandro; Khikhlukha, Danila; Solano-Altamirano, J M; Dormido, Raquel; Duro, Natividad

    2016-03-01

    Center-location of a laser spot is a problem of interest when the laser is used for processing and performing measurements. Measurement quality depends on correctly determining the location of the laser spot. Hence, improving and proposing algorithms for the correct location of the spots are fundamental issues in laser-based measurements. In this paper we introduce a Reaction Diffusion (RD) system as the main computational framework for robustly finding laser spot centers. The method presented is compared with a conventional approach for locating laser spots, and the experimental results indicate that RD-based computation generates reliable and precise solutions. These results confirm the flexibility of the new computational paradigm based on RD systems for addressing problems that can be reduced to a set of geometric operations.

  15. Laser Spot Detection Based on Reaction Diffusion

    Directory of Open Access Journals (Sweden)

    Alejandro Vázquez-Otero

    2016-03-01

    Full Text Available Center-location of a laser spot is a problem of interest when the laser is used for processing and performing measurements. Measurement quality depends on correctly determining the location of the laser spot. Hence, improving and proposing algorithms for the correct location of the spots are fundamental issues in laser-based measurements. In this paper we introduce a Reaction Diffusion (RD system as the main computational framework for robustly finding laser spot centers. The method presented is compared with a conventional approach for locating laser spots, and the experimental results indicate that RD-based computation generates reliable and precise solutions. These results confirm the flexibility of the new computational paradigm based on RD systems for addressing problems that can be reduced to a set of geometric operations.

  16. Rocky Mountain spotted fever in Argentina.

    Science.gov (United States)

    Paddock, Christopher D; Fernandez, Susana; Echenique, Gustavo A; Sumner, John W; Reeves, Will K; Zaki, Sherif R; Remondegui, Carlos E

    2008-04-01

    We describe the first molecular confirmation of Rickettsia rickettsii, the cause of Rocky Mountain spotted fever (RMSF), from a tick vector, Amblyomma cajennense, and from a cluster of fatal spotted fever cases in Argentina. Questing A. cajennense ticks were collected at or near sites of presumed or confirmed cases of spotted fever rickettsiosis in Jujuy Province and evaluated by polymerase chain reaction assays for spotted fever group rickettsiae. DNA of R. rickettsii was amplified from a pool of A. cajennense ticks and from tissues of one of four patients who died during 2003-2004 after illnesses characterized by high fever, severe headache, myalgias, and petechial rash. The diagnosis of spotted fever rickettsiosis was confirmed in the other patients by indirect immunofluorescence antibody and immunohistochemical staining techniques. These findings show the existence of RMSF in Argentina and emphasize the need for clinicians throughout the Americas to consider RMSF in patients with febrile rash illnesses.

  17. Assessment of White Spot Lesions and In-Vivo Evaluation of the Effect of CPP-ACP on White Spot Lesions in Permanent Molars of Children.

    Science.gov (United States)

    Munjal, Deepti; Garg, Shalini; Dhindsa, Abhishek; Sidhu, Gagandeep Kaur; Sethi, Harsimran Singh

    2016-05-01

    As hindrance of remineralisation process occurs during orthodontic therapy resulting in decalcification of enamel because number of plaque retention sites increases due to banding and bonding of appliances to teeth. The present analytic study was undertaken to assess the occurrence of white spot lesions in permanent molars of children with and without orthodontic therapy and to evaluate the effect of Casein PhosphoPeptide-Amorphous Calcium Phosphate (CPP-ACP) on white spot lesions in post-orthodontic patients in a given period of time. The study comprised of examination of 679 first permanent molars which were examined to assess the occurrence of smooth surface white spot lesions in children of 8 to 16 years age group. Group I comprised subjects without any orthodontic treatment and Group II comprised of subjects who had undergone orthodontic therapy. The sample size was calculated using the epi-info6 computer package. Treatment group included 20 post-orthodontic patients examined with at least one white spot lesion within the enamel who received remineralizing cream (GC Tooth Mousse, Recaldent, GC Corporation.) i.e., CPP-ACP cream two times a day for 12 consecutive weeks. Computerized image analysis method was taken to evaluate white spot lesions. These frequency and percentages were compared with chi-square test. For comparison of numeric data, paired t-test was used. Of the total 278 (49.6%) first permanent molars showed occurrence of smooth surface white spot lesions out of 560 in Group I and 107 (89.9%) first permanent molars showed presence of white spot lesions out of 119 debanded first permanent molars of children examined in Group II. CPP-ACP therapy group showed reduction in severity of codes which was found to be highly significant after 12 weeks and eight weeks on gingival-third, p-value (spot lesions on teeth undergoing fixed orthodontic therapy according to the present study.

  18. Magnetic phases in Pt/Co/Pt films induced by single and multiple femtosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Kisielewski, J., E-mail: jankis@uwb.edu.pl; Kurant, Z.; Sveklo, I.; Tekielak, M.; Maziewski, A. [Faculty of Physics, University of Białystok, Ciołkowskiego 1L, 15-245 Białystok (Poland); Wawro, A. [Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw (Poland)

    2016-05-21

    Ultrathin Pt/Co/Pt trilayers with initial in-plane magnetization were irradiated with femtosecond laser pulses. In this way, an irreversible structural modification was introduced, which resulted in the creation of numerous pulse fluence-dependent magnetic phases. This was particularly true with the out-of-plane magnetization state, which exhibited a submicrometer domain structure. This effect was studied in a broad range of pulse fluences up to the point of ablation of the metallic films. In addition to this single-pulse experiment, multiple exposure spots were also investigated, which exhibited an extended area of out-of-plane magnetization phases and a decreased damage threshold. Using a double exposure with partially overlapped spots, a two-dimensional diagram of the magnetic phases as a function of the two energy densities was built, which showed a strong inequality between the first and second incoming pulses.

  19. Magnetic phases in Pt/Co/Pt films induced by single and multiple femtosecond laser pulses

    International Nuclear Information System (INIS)

    Kisielewski, J.; Kurant, Z.; Sveklo, I.; Tekielak, M.; Maziewski, A.; Wawro, A.

    2016-01-01

    Ultrathin Pt/Co/Pt trilayers with initial in-plane magnetization were irradiated with femtosecond laser pulses. In this way, an irreversible structural modification was introduced, which resulted in the creation of numerous pulse fluence-dependent magnetic phases. This was particularly true with the out-of-plane magnetization state, which exhibited a submicrometer domain structure. This effect was studied in a broad range of pulse fluences up to the point of ablation of the metallic films. In addition to this single-pulse experiment, multiple exposure spots were also investigated, which exhibited an extended area of out-of-plane magnetization phases and a decreased damage threshold. Using a double exposure with partially overlapped spots, a two-dimensional diagram of the magnetic phases as a function of the two energy densities was built, which showed a strong inequality between the first and second incoming pulses.

  20. Thermal interaction of short-pulsed laser focused beams with skin tissues

    International Nuclear Information System (INIS)

    Jiao Jian; Guo Zhixiong

    2009-01-01

    Time-dependent thermal interaction is developed in a skin tissue cylinder subjected to the irradiation of a train of short laser pulses. The skin embedded with a small tumor is stratified as three layers: epidermis, dermis and subcutaneous fat with different optical, thermal and physiological properties. The laser beam is focused to the tumor site by an objective lens for thermal therapy. The ultrafast radiation heat transfer of the focused beam is simulated by the transient discrete ordinates method. The transient Pennes bio-heat equation is solved numerically by the finite volume method with alternating direction implicit scheme. Emphasis is placed on the characterization of the focused beam propagation and absorption and the temperature rise in the focal spot. The effects of the focal spot size and location, the laser power, and the bio-heat equation are investigated. Comparisons with collimated irradiation are conducted. The focused beam can penetrate a greater depth and produce higher temperature rise at the target area, and thus reduce the possibility of thermal damage to the surrounding healthy tissue. It is ideal for killing cancerous cells and small tumors.

  1. Thermal interaction of short-pulsed laser focused beams with skin tissues

    Energy Technology Data Exchange (ETDEWEB)

    Jiao Jian; Guo Zhixiong [Department of Mechanical and Aerospace Engineering, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States)], E-mail: guo@jove.rutgers.edu

    2009-07-07

    Time-dependent thermal interaction is developed in a skin tissue cylinder subjected to the irradiation of a train of short laser pulses. The skin embedded with a small tumor is stratified as three layers: epidermis, dermis and subcutaneous fat with different optical, thermal and physiological properties. The laser beam is focused to the tumor site by an objective lens for thermal therapy. The ultrafast radiation heat transfer of the focused beam is simulated by the transient discrete ordinates method. The transient Pennes bio-heat equation is solved numerically by the finite volume method with alternating direction implicit scheme. Emphasis is placed on the characterization of the focused beam propagation and absorption and the temperature rise in the focal spot. The effects of the focal spot size and location, the laser power, and the bio-heat equation are investigated. Comparisons with collimated irradiation are conducted. The focused beam can penetrate a greater depth and produce higher temperature rise at the target area, and thus reduce the possibility of thermal damage to the surrounding healthy tissue. It is ideal for killing cancerous cells and small tumors.

  2. Broadband and short (10-ps) pulse generation on Nova

    International Nuclear Information System (INIS)

    Perry, M.D.; Browning, D.; Bibeau, C.; Patterson, F.G.; Wilcox, R.; Henesian, M.

    1990-01-01

    The ability to produce high power broadband pulses for purposes of focal spot beam smoothing has recently become an important issue in inertial confinement fusion (ICF). As the first step toward the generation and propagation of such pulses on Nova, the authors have performed a series of experiments with 10-ps pulses. Aside from the inherently broad bandwidth, these short pulses have important applications in ICF experiments and x-ray laser research. The author's experimental results are discussed. The short pulses were produced by diffraction grating pulse compression of chirped pulses formed from self-phase modulation in a single-mode 10-m fused silica fiber. Use of such a short fiber produces a nonlinearly chirped spectrum of 0.74 nm. The central nearly linearly chirped 0.26 nm is selected by polarization discrimination and compressed using 1800-line/mm diffraction gratings to a nearly Gaussian pulse of 10 ps FWHM with an energy contrast ratio of 20:1. This 1-nJ pulse is injected into a Nova amplifier chain with selected amplifiers unfired

  3. Spotted hyaenas Crocuta crocuta prey on new-born elephant calves in Hwange National Park, Zimbabwe

    Directory of Open Access Journals (Sweden)

    Julia Salnicki

    2001-07-01

    Full Text Available Spotted hyaena Crocuta crocuta are known to be opportunists and to have a varied diet including mammals, reptiles and birds. Prey most often hunted are medium sized ungulates but spotted hyaenas will on occasion take larger species such as giraffe Giraffa camelopardalis and zebra Equus burchellii. They are also known to hunt whichever species are most abundant and will vary their prey seasonally. In this study spotted hyaenas were observed to take an unusual prey species in the form of elephant calves (Loxodonta africana. On a number of occasions hyaenas were observed feeding on or killing newborn and very young elephant calves. These observations were made whilst the authors were conducting research on spotted hyaena ecology in the woodlands of Hwange National Park, Zimbabwe and were made during the dry season between September and November 1999.

  4. Analysis of picosecond pulsed laser melted graphite

    International Nuclear Information System (INIS)

    Steinbeck, J.; Braunstein, G.; Speck, J.; Dresselhaus, M.S.; Huang, C.Y.; Malvezzi, A.M.; Bloembergen, N.

    1986-01-01

    A Raman microprobe and high resolution TEM have been used to analyze the resolidified region of liquid carbon generated by picosecond pulse laser radiation. From the relative intensities of the zone center Raman-allowed mode for graphite at 1582 cm -1 and the disorder-induced mode at 1360 cm -1 , the average graphite crystallite size in the resolidified region is determined as a function of position. By comparison with Rutherford backscattering spectra and Raman spectra from nonosecond pulsed laser melting experiments, the disorder depth for picosecond pulsed laser melted graphite is determined as a function of irradiating energy density. Comparisons of TEM micrographs for nanosecond and picosecond pulsed laser melting experiments show that the structure of the laser disordered regions in graphite are similar and exhibit similar behavior with increasing laser pulse fluence

  5. Laser pulse stacking method

    Science.gov (United States)

    Moses, E.I.

    1992-12-01

    A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter. 2 figs.

  6. Telemetry-based mortality estimates of juvenile spot in two North Carolina estuarine creeks

    Science.gov (United States)

    Friedl, Sarah E.; Buckel, Jeffery A.; Hightower, Joseph E.; Scharf, Frederick S.; Pollock, Kenneth H.

    2013-01-01

    We estimated natural mortality rates (M) of age-1 Spot Leiostomus xanthurus by using a sonic telemetry approach. Sonic transmitters were surgically implanted into a total of 123 age-1 Spot in two North Carolina estuarine creeks during spring 2009 and 2010, and the fish were monitored by using a stationary acoustic receiver array and manual tracking. Fates of telemetered Spot were inferred based on telemetry information from estimated locations and swimming speeds. Potential competitors of age-1 Spot were assessed through simultaneous otter trawl sampling, while potential predators of Spot were collected using gill nets and trammel nets. The number of inferred natural mortalities was zero in 2009 (based on 29 telemetered Spot at risk) and four in 2010 (based on 52 fish at risk), with fish being at risk for up to about 70 d each year. Catches of potential competitors or predators did not differ between years, and age-1 Spot were not found in analyzed stomach contents of potential predators. Our estimated 30-d M of 0.03 (95% credible interval = 0.01–0.07) was lower than that predicted from weight-based (M = 0.07) and life-history-based (M = 0.06–0.36) estimates. Our field-based estimate of M for age-1 Spot in this estuarine system can assist in the assessment and management of Spot by allowing a direct comparison with M-values predicted from fish size or life history characteristics. The field telemetry and statistical analysis techniques developed here provide guidance for future telemetry studies of relatively small fish in open, dynamic habitat systems, as they highlight strengths and weaknesses of using a telemetry approach to estimate M.

  7. Hot spot detection for breast cancer in Ki-67 stained slides: image dependent filtering approach

    Science.gov (United States)

    Niazi, M. Khalid Khan; Downs-Kelly, Erinn; Gurcan, Metin N.

    2014-03-01

    We present a new method to detect hot spots from breast cancer slides stained for Ki67 expression. It is common practice to use centroid of a nucleus as a surrogate representation of a cell. This often requires the detection of individual nuclei. Once all the nuclei are detected, the hot spots are detected by clustering the centroids. For large size images, nuclei detection is computationally demanding. Instead of detecting the individual nuclei and treating hot spot detection as a clustering problem, we considered hot spot detection as an image filtering problem where positively stained pixels are used to detect hot spots in breast cancer images. The method first segments the Ki-67 positive pixels using the visually meaningful segmentation (VMS) method that we developed earlier. Then, it automatically generates an image dependent filter to generate a density map from the segmented image. The smoothness of the density image simplifies the detection of local maxima. The number of local maxima directly corresponds to the number of hot spots in the breast cancer image. The method was tested on 23 different regions of interest images extracted from 10 different breast cancer slides stained with Ki67. To determine the intra-reader variability, each image was annotated twice for hot spots by a boardcertified pathologist with a two-week interval in between her two readings. A computer-generated hot spot region was considered a true-positive if it agrees with either one of the two annotation sets provided by the pathologist. While the intra-reader variability was 57%, our proposed method can correctly detect hot spots with 81% precision.

  8. Role of the carbonate impurities on the surface state of pyrite and arsenopyrite under treatment by high power electromagnetic pulses (HPEMP): oxidation of 50-100 μm size particles

    International Nuclear Information System (INIS)

    Filippova, I; Filippov, L; Ryazantseva, M; Chanturiya, V; Bunin, I

    2013-01-01

    Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and Transmission Electron Microscopy (TEM) have shown the variation of surface phase compositions of carbonate bearing pyrite and arsenopyrite as a result of the combined action of chemical oxidation and thermal processes after the treatment by high power electromagnetic pulses (HPEMP). The monitoring of the surface phase composition allowed to determine the correlation between the treatment conditions, the surface phase composition, and the flotation yield. Thus, HPEMP treatment may be regarded as a tool controlling the surface composition and the sorption ability of flotation collector onto minerals surface, and therefore, allowing to control the hydrophobic-hydrophilic surface balance. It was confirmed in this study that the flotation of pyrite with xanthate as a result of the influence HPEMP may vary depending on the presence of impurities such as calcite.

  9. The effect of current flow direction on motor hot spot allocation by transcranial magnetic stimulation.

    Science.gov (United States)

    Stephani, Caspar; Paulus, Walter; Sommer, Martin

    2016-01-01

    The objective of this study was to investigate the significance of pulse configurations and current direction for corticospinal activation using transcranial magnetic stimulation (TMS). In 11 healthy subjects (8 female), a motor map for the motor evoked potentials (MEPs) recorded from the first dorsal interosseus (FDI), abductor digiti minimi (ADM), extensor carpi radialis, and biceps brachii (BB) muscles of the dominant side was established. Starting from a manually determined hot spot of the FDI representation, we measured MEPs at equal oriented points on an hexagonal grid, with 7 MEPs recorded at each point, using the following pulse configurations: posteriorly directed monophasic (Mo-P), anteriorly directed monophasic (Mo-A), biphasic with the more relevant second cycle oriented posteriorly (Bi-P) as well as a reversed biphasic condition (Bi-A). For each pulse configuration, a hot spot was determined and a center of gravity (CoG) was calculated. We found that the factor current direction had an effect on location of the CoG-adjusted hot spot in the cranio-caudal axis but not in the latero-medial direction with anteriorly directed pulses locating the CoG more anteriorly and vice versa. In addition, the CoG for the FDI was more laterally than the cortical representations for the abductor digiti minimi (ADM) and extensor carpi radialis (ECR) which were registered as well. The results indicate that direction of the current pulse should be taken into account for determination of the motor representation of a muscle by TMS. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

  10. The Mechanism of Ultrasonic Vibration on Grain Refining and Degassing in GTA Spot Welding of Copper Joints.

    Science.gov (United States)

    Al-Ezzi, Salih; Quan, Gaofeng; Elrayah, Adil

    2018-05-07

    This paper examines the effect of ultrasonic vibration (USV) on grain size and interrupted porosity in Gas Tungsten Arc (GTA) spot-welded copper. Grain size was refined by perpendicularly attaching a transducer to the welded sheet and applying USV to the weld pool for a short time (0, 2, 4, and 6 s) in addition improvements to the degassing process. Results illustrate a significant reduction of grain size (57%). Notably, USV provided interaction between reformations (fragmentation) and provided nucleation points (detaching particles from the fusion line) for grains in the nugget zone and the elimination of porosity in the nugget zone. The GTA spot welding process, in conjunction with USV, demonstrated an improvement in the corrosion potential for a copper spot-welded joint in comparison to the joint welded without assistance of USV. Finally, welding of copper by GTA spot welding in conjunction with ultrasound for 2 s presented significant mechanical properties.

  11. Pulse to pulse klystron diagnosis system

    International Nuclear Information System (INIS)

    Nowak, J.; Davidson, V.; Genova, L.; Johnson, R.; Reagan, D.

    1981-03-01

    This report describes a system used to study the behavior of SLAC high powered klystrons operating with a twice normal pulse width of 5 μs. At present, up to eight of the klystrons installed along the accelerator can be operated with long pulses and monitored by this system. The report will also discuss some of the recent findings and investigations

  12. Numerical study of glare spot phase Doppler anemometry

    Science.gov (United States)

    Hespel, C.; Ren, K. F.; Gréhan, G.; Onofri, F.

    2008-03-01

    The phase Doppler anemometry has (PDA) been developed to measure simultaneously the velocity and the size of droplets. When the concentration of particles is high, tightly focused beams must be used, as in the dual burst PDA. The latter permits an access to the refractive index of the particle, but the effect of wave front curvature of the incident beams becomes evident. In this paper, we introduce a glare spot phase Doppler anemometry which uses two large beams. The images of the particle formed by the reflected and refracted light, known as glare spots, are separated in space. When a particle passes through the probe volume, the two parts in a signal obtained by a detector in forward direction are then separated in time. If two detectors are used the phase differences and the intensity ratios between two signals, the distance between the reflected and refracted spots can be obtained. These measured values provide information about the particle diameter and its refractive index, as well as its two velocity components. This paper is devoted to the numerical study of such a configuration with two theoretical models: geometrical optics and rigorous electromagnetism solution.

  13. Gravid Spot Predicts Developmental Progress and Reproductive Output in a Livebearing Fish, Gambusia holbrooki

    Science.gov (United States)

    Norazmi-Lokman, Nor Hakim; Purser, G. J.; Patil, Jawahar G.

    2016-01-01

    In most livebearing fish, the gravid spot is an excellent marker to identify brooding females, however its use to predict progress of embryonic development, brood size, timing of parturition and overall reproductive potential of populations remain unexplored. Therefore, to understand these relationships, this study quantified visual attributes (intensity and size) of the gravid spot in relation to key internal development in Gambusia holbrooki. Observations show that the colour of the gravid spot arises from progressive melanisation on the surface of the ovarian sac at its hind margin, rather than melanisation of the developing embryos or the skin of the brooding mother. More importantly, the gravid spot intensity and size were closely linked with both developmental stages and clutch size, suggesting their reliable use as external surrogates of key internal developmental in the species. Using predictive consistency of the gravid spot, we also determined the effect of rearing temperature (23°C and 25°C) on gestation period and parturition behaviour. The results show that gestation period was significantly reduced (F = 364.58; df = 1,48; P˃0.05) at 25°C. However there was no significant difference in average number of fry parturated in the two temperature groups (Pspot intensity is a reliable predictor of reproductive output. The parturition in the species occurred predominantly in the morning and in contrast to earlier reports, tails of the fry emerged first with a few exceptions of head-first, twin and premature births. This study demonstrates utility of the gravid spot for downstream reproductive investigations in a live-bearing fish both in the field and laboratory. The reproducibility of the relationships (intensity with both developmental stage and clutch size), imply that they are also relevant to wild populations that experience varying temperature climes and stressors, significant deviations of which may serve as indicators of environmental health and

  14. Volume higher; spot price ranges widen

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    This article is the October 1994 uranium market summary. During this reporting period, volume on the spot concentrates market doubled. Twelve deals took place: three in the spot concentrates market, one in the medium and long-term market, four in the conversion market, and four in the enrichment market. The restricted price range widened due to higher prices at the top end of the range, while the unrestricted price range widened because of lower prices at the bottom end. Spot conversion prices were higher, and enrichment prices were unchanged

  15. Modeling characterization of the National Ignition Facility focal spot

    International Nuclear Information System (INIS)

    Williams, W.H.

    1998-01-01

    The predicted focal spot size of the National Ignition Facility laser is parameterized against the finish quality of the optics in the system. Results are reported from simulations which include static optics aberrations, as well as pump-induced distortions, beam self-focusing, and the effect of an adaptive optic. The simulations do not include contributions from optics mounting errors, residual thermal noise in laser slabs from previous shots, air turbulence, a kinoform phase plate, or smoothing by spectral dispersion (SSD). Consequently, these results represent ''first shot of the day'', without-SSD, predictions

  16. Multiple Colliding Electromagnetic Pulses: A Way to Lower the Threshold of e+e- Pair Production from Vacuum

    International Nuclear Information System (INIS)

    Bulanov, S. S.; Mur, V. D.; Narozhny, N. B.; Nees, J.; Popov, V. S.

    2010-01-01

    The scheme of a simultaneous multiple pulse focusing on one spot naturally arises from the structural features of projected new laser systems, such as the Extreme Light Infrastructure (ELI) and High Power laser Energy Research (HiPER). It is shown that the multiple pulse configuration is beneficial for observing e + e - pair production from a vacuum under the action of sufficiently strong electromagnetic fields. The field of focused pulses is described using a realistic three-dimensional model based on an exact solution of the Maxwell equations. The e + e - pair production threshold in terms of electromagnetic field energy can be substantially lowered if, instead of one or even two colliding pulses, multiple pulses are focused on one spot. The multiple pulse interaction geometry gives rise to subwavelength field features in the focal region. These features result in the production of extremely short e + e - bunches.

  17. Combined pulsed dye laser and fiberoptic Nd-YAG laser for the treatment of hypertrophic port wine stain.

    Science.gov (United States)

    Radmanesh, Mohammed; Radmanesh, Ramin

    2017-10-01

    The hypertrophic Port Wine Stain (PWS) is only partially and superficially treated with the Pulsed dye laser (PDL) because of its limited depth of penetration. We used combined PDL and fiberoptic 1444-nm Nd-YAG laser to treat a case with hypertrophic PWS. After tumescent anesthesia, few holes were made by a 16-gauge needle on different sides of the lesion. The fiberoptic tip of 1444-nm Nd-YAG laser was inserted within the holes and was pushed forward while triggering. In a fan pattern and by a back and forth movement, the subcutaneous and deep dermal areas were coagulated. The skin and outer mucosal surfaces were then treated by PDL. The fiberoptic system used was Accusculpt 1444-nm Nd-YAG laser (Lutronic lasers, South Korea), and the PDL used was 585 nm Nlite system (Chromogenex UK). The parameters used for PDL were fluence = 9 Joules/cm 2 and the spot size was 5 mm. The parameters used for fiberoptic 1444-nm Nd-YAG laser were: Pulse rate = 30 Hz, pulse energy = 300 mJ, power = 6 W, and the total energy = 4000 J for the whole face and mucosa. Little sign of regression and moderate purpura were detected immediately after combined fiberoptic Nd-YAG and PDL therapy. The lesion gradually regressed within 4 months with satisfactory color and volume change. Combined fiberoptic Nd-YAG laser and PDL can be used for the treatment of deeper and superficial layers of hypertrophic PWS.

  18. Time-dependent H-like and He-like Al lines produced by ultra-short pulse laser

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Takako; Kato, Masatoshi [National Inst. for Fusion Science, Nagoya (Japan); Shepherd, R; Young, B; More, R; Osterheld, Al

    1998-03-01

    We have performed numerical modeling of time-resolved x-ray spectra from thin foil targets heated by the LLNL Ultra-short pulse (USP) laser. The targets were aluminum foils of thickness ranging from 250 A to 1250 A, heated with 120 fsec pulses of 400 nm light from the USP laser. The laser energy was approximately 0.2 Joules, focused to a 3 micron spot size for a peak intensity near 2 x 10{sup 19} W/cm{sup 2}. Ly{alpha} and He{alpha} lines were recorded using a 900 fsec x-ray streak camera. We calculate the effective ionization, recombination and emission rate coefficients including density effects for H-like and He-like aluminum ions using a collisional radiative model. We calculate time-dependent ion abundances using these effective ionization and recombination rate coefficients. The time-dependent electron temperature and density used in the calculation are based on an analytical model for the hydrodynamic expansion of the target foils. During the laser pulse the target is ionized. After the laser heating stops, the plasma begins to recombine. Using the calculated time dependent ion abundances and the effective emission rate coefficients, we calculate the time dependent Ly{alpha} and He{alpha} lines. The calculations reproduce the main qualitative features of the experimental spectra. (author)

  19. Short pulse, high resolution, backlighters for point projection high-energy radiography at the National Ignition Facility

    Science.gov (United States)

    Tommasini, R.; Bailey, C.; Bradley, D. K.; Bowers, M.; Chen, H.; Di Nicola, J. M.; Di Nicola, P.; Gururangan, G.; Hall, G. N.; Hardy, C. M.; Hargrove, D.; Hermann, M.; Hohenberger, M.; Holder, J. P.; Hsing, W.; Izumi, N.; Kalantar, D.; Khan, S.; Kroll, J.; Landen, O. L.; Lawson, J.; Martinez, D.; Masters, N.; Nafziger, J. R.; Nagel, S. R.; Nikroo, A.; Okui, J.; Palmer, D.; Sigurdsson, R.; Vonhof, S.; Wallace, R. J.; Zobrist, T.

    2017-05-01

    High-resolution, high-energy X-ray backlighters are very active area of research for radiography experiments at the National Ignition Facility (NIF) [Miller et al., Nucl. Fusion 44, S228 (2004)], in particular those aiming at obtaining Compton-scattering produced radiographs from the cold, dense fuel surrounding the hot spot. We report on experiments to generate and characterize point-projection-geometry backlighters using short pulses from the advanced radiographic capability (ARC) [Crane et al., J. Phys. 244, 032003 (2010); Di Nicola et al., Proc. SPIE 2015, 93450I-12], at the NIF, focused on Au micro-wires. We show the first hard X-ray radiographs, at photon energies exceeding 60 keV, of static objects obtained with 30 ps-long ARC laser pulses, and the measurements of strength of the X-ray emission, the pulse duration and the source size of the Au micro-wire backlighters. For the latter, a novel technique has been developed and successfully applied.

  20. Modeling Hot Spot Motor Vehicle Theft Crime in Relation to Landuse and Settlement Patterns

    Directory of Open Access Journals (Sweden)

    Djaka Marwasta

    2004-01-01

    Full Text Available The crowd of Yogyakarta urban has impacted its surrounding area, including Depok sub district, which is indicated by the rising of physical development, for example education facilities and settlements. The progress does not only bring positive impact, but also negative impact for instance the rising of crime number i.e. motor vehicle robbery. The aims of this research are 1 mapping motor vehicle robbery data as the distribution map and identifying motor vehicle robbery hot spot base on distrbution map; and 2 studying the correlation of motor vehicle robbery hot spot with physical environment phenomena, i.e. land use type and settlement pattern. The research method consists of two parts; they are motor vehicle robbery cluster analysis and the relation of motor vehicle robbery and physical environment analysis. Motor vehicle robbery cluster analysis is using distribution data, which analyzes the distribution into motor vehicle robbery hot spot with nearest neighbor tehnique. Contingency coefficient and frequency distribution analysis is used to analyze the correlation of motor vehicle robbery hot spot and physical environment. Contingency coefficient is used to study the relation of motor vehicle robbery hot spot polygon with physical environment condition, whereas frequency distribution is used to study the distribution of motor vehicle robbery in the hot spot with physical environment condition. Physical environment which consists of land use type, housing density, house regularity pattern, and the average of building size, are obtained from interpretation of black and white panchromatic aerial photograph year 2000, in the scale 1 : 20.000. the most motor vehicle robbery hot spot is found on the settlement area, 68,3% from 378 motor vehicle robbery cases in the hot spot. The seond level is found on the education area (16.4%. The most motor vehicle hot spot in the settlement is found on the hight density and irregular settlement, which have big

  1. Intense pulsed light, near infrared pulsed light, and fractional laser combination therapy for skin rejuvenation in Asian subjects: a prospective multi-center study in China.

    Science.gov (United States)

    Tao, Li; Wu, Jiaqiang; Qian, Hui; Lu, Zhong; Li, Yuanhong; Wang, Weizhen; Zhao, Xiaozhong; Tu, Ping; Yin, Rui; Xiang, Leihong

    2015-09-01

    Ablative skin rejuvenation therapies have limitations for Asian people, including post-inflammatory hyperpigmentation and long down time. Non-ablative lasers are safer but have limited efficacy. This study is to investigate the safety and efficacy of a combination therapy consisting of intense pulsed light (IPL), near infrared (NIR) light, and fractional erbium YAG (Er:YAG) laser for skin rejuvenation in Asian people. This study recruited 113 subjects from six sites in China. Subjects were randomly assigned to a full-face group, who received combination therapy, and split-face groups, in which one half of the face received combination therapy and the other half received IPL monotherapy. Each subject received five treatment sessions during a period of 90 days. Subjects were followed up at 1 and 3 months post last treatment. Three months after last treatment, the full-face group (n = 57) had a global improvement rate of 29 % and 29 % for wrinkles, 32 % for skin texture, 33 % for pigment spots, 28 % for pore size, respectively. For patients in the split-face groups (n = 54), monotherapy side had a global improvement rate of 23 % and 20 % for wrinkles, 27 % for skin texture, 25 % for pigment spots, 25 % for pore size, respectively. Both combination therapy and monotherapy resulted in significant improvements at the follow-up visits compared to baseline (P < 0.001). Combination therapy showed significantly greater improvements compared to monotherapy at two follow-up visits (P < 0.05). Combination therapy is a safe and more effective strategy than IPL monotherapy for skin rejuvenation in Asian people.

  2. Time dependence of X-ray polarizability of a crystal induced by an intense femtosecond X-ray pulse

    Directory of Open Access Journals (Sweden)

    A. Leonov

    2014-11-01

    Full Text Available The time evolution of the electron density and the resulting time dependence of Fourier components of the X-ray polarizability of a crystal irradiated by highly intense femtosecond pulses of an X-ray free-electron laser (XFEL is investigated theoretically on the basis of rate equations for bound electrons and the Boltzmann equation for the kinetics of the unbound electron gas. The photoionization, Auger process, electron-impact ionization, electron–electron scattering and three-body recombination have been implemented in the system of rate equations. An algorithm for the numerical solution of the rate equations was simplified by incorporating analytical expressions for the cross sections of all the electron configurations in ions within the framework of the effective charge model. Using this approach, the time dependence of the inner shell populations during the time of XFEL pulse propagation through the crystal was evaluated for photon energies between 4 and 12 keV and a pulse width of 40 fs considering a flux of 1012 photons pulse−1 (focusing on a spot size of ∼1 µm. This flux corresponds to a fluence ranging between 0.8 and 2.4 mJ µm−2. The time evolution of the X-ray polarizability caused by the change of the atomic scattering factor during the pulse propagation is numerically analyzed for the case of a silicon crystal. The time-integrated polarizability drops dramatically if the fluence of the X-ray pulse exceeds 1.6 mJ µm−2.

  3. X-ray focal spot reconstruction by circular penumbra analysis-Application to digital radiography systems.

    Science.gov (United States)

    Di Domenico, Giovanni; Cardarelli, Paolo; Contillo, Adriano; Taibi, Angelo; Gambaccini, Mauro

    2016-01-01

    The quality of a radiography system is affected by several factors, a major one being the focal spot size of the x-ray tube. In fact, the measurement of such size is recognized to be of primary importance during acceptance tests and image quality evaluations of clinical radiography systems. The most common device providing an image of the focal spot emission distribution is a pin-hole camera, which requires a high tube loading in order to produce a measurable signal. This work introduces an alternative technique to obtain an image of the focal spot, through the processing of a single radiograph of a simple test object, acquired with a suitable magnification. The radiograph of a magnified sharp edge is a well-established method to evaluate the extension of the focal spot profile along the direction perpendicular to the edge. From a single radiograph of a circular x-ray absorber, it is possible to extract simultaneously the radial profiles of several sharp edges with different orientations. The authors propose a technique that allows to obtain an image of the focal spot through the processing of these radial profiles by means of a pseudo-CT reconstruction technique. In order to validate this technique, the reconstruction has been applied to the simulated radiographs of an ideal disk-shaped absorber, generated by various simulated focal spot distributions. Furthermore, the method has been applied to the focal spot of a commercially available mammography unit. In the case of simulated radiographs, the results of the reconstructions have been compared to the original distributions, showing an excellent agreement for what regards both the overall distribution and the full width at half maximum measurements. In the case of the experimental test, the method allowed to obtain images of the focal spot that have been compared with the results obtained through standard techniques, namely, pin-hole camera and slit camera. The method was proven to be effective for simulated

  4. X-ray focal spot reconstruction by circular penumbra analysis—Application to digital radiography systems

    Energy Technology Data Exchange (ETDEWEB)

    Di Domenico, Giovanni, E-mail: didomenico@fe.infn.it; Cardarelli, Paolo; Taibi, Angelo; Gambaccini, Mauro [Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Ferrara, via Saragat 1, FE I-44122, Italy and INFN - sezione di Ferrara, via Saragat 1, FE I-44122 (Italy); Contillo, Adriano [Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Ferrara, via Saragat 1, FE I-44122 (Italy)

    2016-01-15

    Purpose: The quality of a radiography system is affected by several factors, a major one being the focal spot size of the x-ray tube. In fact, the measurement of such size is recognized to be of primary importance during acceptance tests and image quality evaluations of clinical radiography systems. The most common device providing an image of the focal spot emission distribution is a pin-hole camera, which requires a high tube loading in order to produce a measurable signal. This work introduces an alternative technique to obtain an image of the focal spot, through the processing of a single radiograph of a simple test object, acquired with a suitable magnification. Methods: The radiograph of a magnified sharp edge is a well-established method to evaluate the extension of the focal spot profile along the direction perpendicular to the edge. From a single radiograph of a circular x-ray absorber, it is possible to extract simultaneously the radial profiles of several sharp edges with different orientations. The authors propose a technique that allows to obtain an image of the focal spot through the processing of these radial profiles by means of a pseudo-CT reconstruction technique. In order to validate this technique, the reconstruction has been applied to the simulated radiographs of an ideal disk-shaped absorber, generated by various simulated focal spot distributions. Furthermore, the method has been applied to the focal spot of a commercially available mammography unit. Results: In the case of simulated radiographs, the results of the reconstructions have been compared to the original distributions, showing an excellent agreement for what regards both the overall distribution and the full width at half maximum measurements. In the case of the experimental test, the method allowed to obtain images of the focal spot that have been compared with the results obtained through standard techniques, namely, pin-hole camera and slit camera. Conclusions: The method was

  5. Polarization dependent nanostructuring of silicon with femtosecond vortex pulse

    Directory of Open Access Journals (Sweden)

    M. G. Rahimian

    2017-08-01

    Full Text Available We fabricated conical nanostructures on silicon with a tip dimension of ∼ 70 nm using a single twisted femtosecond light pulse carrying orbital angular momentum (ℓ=±1. The height of the nano-cone, encircled by a smooth rim, increased from ∼ 350 nm to ∼ 1 μm with the pulse energy and number of pulses, whereas the apex angle remained constant. The nano-cone height was independent of the helicity of the twisted light; however, it is reduced for linear polarization compared to circular at higher pulse energies. Fluid dynamics simulations show nano-cones formation when compressive forces arising from the radial inward motion of the molten material push it perpendicular to the surface and undergo re-solidification. Simultaneously, the radial outward motion of the molten material re-solidifies after reaching the cold boundary to form a rim. Overlapping of two irradiated spots conforms to the fluid dynamics model.

  6. Two-dimensional turning of thermal flux from normal to lateral propagation in thin metal film irradiated by femtosecond laser pulse

    Science.gov (United States)

    Shepelev, V. V.; Inogamov, N. A.

    2018-01-01

    There are various geometrical variants of laser illumination and target design. Important direction of investigations is connected with tightly focused action (spot size may be less than micron) onto a thin metal film: thickness of a film is just few skin-layer depths. Duration of a pulse is τ L ˜ 0.1 ps. In these conditions energy absorbed in a skin layer first propagates normally to a surface: gradient ∂Te /∂x dominates, here and below x and y are normal and lateral directions. This process in 1-2 ps homogenizes electron temperature T e along thickness of a film. We consider conditions when a film or is supported by weakly conducting substrate, or is free standing. Therefore all absorbed energy is confined inside the film. At the next stage the internal energy begin to flow along the lateral direction—thus direction of energy expansion is changed from x to y because of the heat non-penetrating boundary condition imposed on the rear-side of the film. At the short two-temperature stage of lateral expansion the thermal conductivity κ is high. After that electron and ion temperatures equilibrates and later on the heat propagates with usual value of κ. Lateral expansion cools down the hot spot on long time scales and finally the molten spot recrystallizes. Two-dimensional approach allows us to consider all these stages from propagation in x direction (normal to a film) to propagation in y direction (along a film).

  7. A new kind of relativity: Compensated delays as phenomenal blind spots.

    Science.gov (United States)

    Vrobel, Susie

    2015-12-01

    The French phenomenologist Merleau-Ponty identified the human body as the blind spot of perception and cognition. Being situated in its environment both spatially and temporally, the body forms a primordial field of presence, which is transparent from the obserpant's(1) perspective and therefore creates a sytemic blindness. This paper is primarily concerned with what Merleau-Ponty calls the pulse of the duration of the body, which, in his view, "impregnates" our perception. This notion of duration will be described in terms of the temporal extensions of an embodied obserpant. For biological systems, these extensions may be measured in the obserpant's temporal endo-sphere, a time cone, which extends in two dimensions: succession and simultaneity (Δtlength and Δtdepth, respectively). Obserpants are described not as having, but being a model of the world (including themselves). The perception of Δtlength and Δtdepth results in a fractal temporal structure, which correlates with successive and instantaneous perception. This temporal structure becomes important during temporal recalibration, i.e. delay compensation. During such processes, the distribution of the temporal dimensions succession and simultaneity may vary from one obserpant's Now to another's. Furthermore, recalibration provides a window in which the obserpant's Now may be tipped towards either temporal dimension. We can measure the difference between obserpant A's temporal extension and that of obserpant B in Δtlength and Δtdepth. The complexity of an obserpant's temporal perspective - his temporal interface - can thus be compared and quantified by the size of his time cone. The units of this measurement are the number of compensated and uncompensated delays. During temporal recalibration, an obserpant can turn succession into simultaneity and vice-versa. Moreover, what is successive in obserpant A's Now may be simultaneous for obserpant B and vice-versa. This discrepancy can be modelled as time

  8. Finding your innovation sweet spot.

    Science.gov (United States)

    Goldenberg, Jacob; Horowitz, Roni; Levav, Amnon; Mazursky, David

    2003-03-01

    Most new product ideas are either uninspired or impractical. So how can developers hit the innovation sweet spot--far enough from existing products to attract real interest but close enough that they are feasible to make and market? They can apply five innovation patterns that manipulate existing components of a product and its immediate environment to come up with something both ingenious and viable, say the authors. The subtraction pattern works by removing product components, particularly those that seem desirable or indispensable. Think of the legless high chair that attaches to the kitchen table. The multiplication pattern makes one or more copies of an existing component, then alters those copies in some important way. For example, the Gillette double-bladed razor features a second blade that cuts whiskers at a slightly different angle. By dividing an existing product into its component parts--the division pattern--you can see something that was an integrated whole in an entirely different light. Think of the modern home stereo--it has modular speakers, tuners, and CD and tape players, which allow users to customize their sound systems. The task unification pattern involves assigning a new task to an existing product element or environmental attribute, thereby unifying two tasks in a single component. An example is the defrosting filament in an automobile windshield that also serves as a radio antenna. Finally, the attribute dependency pattern alters or creates the dependent relationships between a product and its environment. For example, by creating a dependent relationship between lens color and external lighting conditions, eyeglass developers came up with a lens that changes color when exposed to sunlight.

  9. Separations and hot and cold spot areas for anterior adjacent fields

    International Nuclear Information System (INIS)

    Supe, S.S.; Sharma, A.K.

    1991-01-01

    Due to the limitation on the maximum field size opening on telecobalt machines, the use of two adjoining fields is a necessary requisite for treatment of abdominal malignancies. Matching of these adjoining fields is important to avoid cold and hot spots inside the tumour volume. Detailed treatment planning for these treatment is obligatory. Formulae have been derived for the determination of the separations required at the skin surface for achieving dose homogeneity at the depth of interest. The advantages and disadvantages associated with the use of higher source to skin distances are also discussed. In the case of adjoining fields from both anterior and posterior sides, adjustment in field size is a must. However, cold and hot spots cannot be completely avoided. During the course of treatment continous shifting of separations on the skin surface helps in reducing cold and hot spots. (author). 2 refs., 2 figs

  10. Pre-announcements of price increase intentions in liner shipping spot markets

    DEFF Research Database (Denmark)

    Chen, Gang; Rytter, Niels G M; Jiang, Liping

    2017-01-01

    competition perspective, which will indirectly indicate whether carriers are able to manipulate spot rates following GRI announcements. Taking the Far East–North Europe trade between 2009 and 2013 as an example, the paper first reveals the gradual increase of GRI frequency and size, which reflects carriers...... factors, in sequence of explanation power, are the total capacity of GRI carriers, the idling fleet size, the spot rate level, and the average ship-loading factor. Clearly the latter three factors are market fundamentals, which are unlikely to be influenced by an individual carrier in the short term....... In actual fact, the conclusion reached is that there is little evidence that carriers can manipulate and distort spot rates through GRIs...

  11. Extra spots in the electron diffraction patterns of neutron irradiated zirconium and its alloys

    International Nuclear Information System (INIS)

    Madden, P.K.

    1977-01-01

    Specimens of neutron irradiated zirconium and its alloys were examined in the transmission electron microscope. Groups of extra spots, often exhibiting four-fold symmetry, were observed in thin foil electron diffraction patterns of these specimens. The 'extra-spot' structure, like the expected black-dot/small scale dislocation loop neutron irradiated damage, is approximately 100 A in size. Its nature is uncertain. It may be related to irradiation damage or to some artefact introduced during specimen preparation. If it is the latter, then published irradiation damage defect size distributions and determined irradiation growth strains of other investigators, may require modification. The present inconclusive results indicate that extra-spot structure is likely to consist of oxide particles, but may correspond to hydride precipitation or decoration effects, or even, to electron beam effects. (author)

  12. Uniform irradiation of adjustable target spots in high-power laser driver

    International Nuclear Information System (INIS)

    Jiang Xiujuan; Li Jinghui; Li Huagang; Li Yang; Lin Zunqi

    2011-01-01

    For smoothing and shaping the on-target laser patterns flexibly in high-power laser drivers, a scheme has been developed that includes a zoom lens array and two-dimensional smoothing by spectral dispersion (SSD). The size of the target pattern can be controlled handily by adjusting the focal length of the zoom lens array, while the profile of the pattern can be shaped by fine tuning the distance between the target and the focal plane of the principal focusing lens. High-frequency stripes inside the pattern caused by beamlet interference are wiped off by spectral dispersion. Detailed simulations indicate that SSD works somewhat differently for spots of different sizes. For small spots, SSD mainly smooths the intensity modulation of low-to-middle spatial frequency, while for large spots, SSD sweeps the fine speckle structure to reduce nonuniformity of middle-to-high frequency. Spatial spectra of the target patterns are given and their uniformity is evaluated.

  13. Data for automated, high-throughput microscopy analysis of intracellular bacterial colonies using spot detection.

    Science.gov (United States)

    Ernstsen, Christina L; Login, Frédéric H; Jensen, Helene H; Nørregaard, Rikke; Møller-Jensen, Jakob; Nejsum, Lene N

    2017-10-01

    Quantification of intracellular bacterial colonies is useful in strategies directed against bacterial attachment, subsequent cellular invasion and intracellular proliferation. An automated, high-throughput microscopy-method was established to quantify the number and size of intracellular bacterial colonies in infected host cells (Detection and quantification of intracellular bacterial colonies by automated, high-throughput microscopy, Ernstsen et al., 2017 [1]). The infected cells were imaged with a 10× objective and number of intracellular bacterial colonies, their size distribution and the number of cell nuclei were automatically quantified using a spot detection-tool. The spot detection-output was exported to Excel, where data analysis was performed. In this article, micrographs and spot detection data are made available to facilitate implementation of the method.

  14. Plasma spot welding of ferritic stainless steels

    International Nuclear Information System (INIS)

    Lesnjak, A.; Tusek, J.

    2002-01-01

    Plasma spot wedding of ferritic stainless steels studied. The study was focused on welding parameters, plasma and shieldings and the optimum welding equipment. Plasma-spot welded overlap joints on a 0.8 mm thick ferritic stainless steel sheet were subjected to a visual examination and mechanical testing in terms of tension-shear strength. Several macro specimens were prepared Plasma spot welding is suitable to use the same gas as shielding gas and as plasma gas , i. e. a 98% Ar/2% H 2 gas mixture. Tension-shear strength of plasma-spot welded joint was compared to that of resistance sport welded joints. It was found that the resistance welded joints withstand a somewhat stronger load than the plasma welded joints due to a large weld sport diameter of the former. Strength of both types of welded joints is approximately the same. (Author) 32 refs

  15. A telemetry experiment on spotted grunter Pomadasys ...

    African Journals Online (AJOL)

    associated fish in South Africa was investigated by conducting a tracking experiment on spotted grunter Pomadasys commersonnii in the East Kleinemonde Estuary. The telemetry equipment comprised two VEMCO V8 transmitters and a ...

  16. Asparagus Beetle and Spotted Asparagus Beetle

    OpenAIRE

    Hodgson, Erin W.; Drost, Dan

    2007-01-01

    Asparagus beetle, Crioceris asparagi, and spotted asparagus beetle, C. duodecimpunctata are leaf beetles in the family Chrysomelidae. These beetles feed exclusively on asparagus and are native to Europe. Asparagus beetle is the more economically injurious of the two species.

  17. Detecting Blind Spot By Using Ultrasonic Sensor

    Directory of Open Access Journals (Sweden)

    T. S. Ajay

    2015-08-01

    Full Text Available Safety remains a top concern for automobile industries and new-car shoppers. Detection of Blind Spots is a major concern for safety issues. So automobiles have been constantly updating their products with new technologies to detect blind spots so that they can add more safety to the vehicle and also reduce the road accidents. Almost 1.5 million people die in road accidents each year. Blind spot of an automobile is the region of the vehicle which cannot be observed properly while looking either through side or rear mirror view. To meet the above requirements this paper describes detecting blind spot by using ultrasonic sensor and controlling the direction of car by automatic steering. The technology embedded in the system is capable of automatically steer the vehicle away from an obstacle if the system determines that a collision is impending or if the vehicle is in the vicinity of our car.

  18. How Many Spots Does a Cheetah Have?

    Science.gov (United States)

    Reed, Kristine M.

    2000-01-01

    Describes first grade students' mathematical investigation of the number of spots on a cheetah. The exploration of counting and estimation strategies that grew from the investigation gives evidence that mathematicians come in all ages. (ASK)

  19. Quantitation of pregabalin in dried blood spots and dried plasma spots by validated LC-MS/MS methods.

    Science.gov (United States)

    Kostić, Nađa; Dotsikas, Yannis; Jović, Nebojša; Stevanović, Galina; Malenović, Anđelija; Medenica, Mirjana

    2015-05-10

    In this paper, novel LC-MS/MS methods for the determination of antiepileptic drug pregabalin in dried matrix spots (DMS) are presented. This attractive technique of sample collection in micro amount was utilized in the form of dried blood spots (DBS) and dried plasma spots (DPS). Following a pre-column derivatization procedure, using n-propyl chloroformate in the presence of n-propanol, and consecutive liquid-liquid extraction, derivatized pregabalin and its internal standard, 4-aminocyclohexanecarboxylic acid, were detected in positive ion mode by applying two SRM transitions per analyte. A YMC-Pack Octyl column (50mm×4.0mm, 3μm particle size) maintained at 30°C, was utilized with running mobile phase composed of acetonitrile: 0.15% formic acid (85:15, v/v). Flow rate was 550μL/min and total run time 2min. Established methods were fully validated over the concentration range of 0.200-20.0μg/mL for DBS and 0.400-40.0μg/mL for DPS, respectively, while specificity, accuracy, precision, recovery, matrix-effect, stability, dilution integrity and spot homogeneity were found within acceptance criteria. Validated methods were applied for the determination of pregabalin levels in dried blood and plasma samples obtained from patients with epilepsy, after per os administration of commercial capsules. Comparison of drug level in blood and plasma, as well as correction steps undertaken in order to overcome hematocrit issue, when analyzing DBS, are also given. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. X-ray emission reduction and photon dose lowering by energy loss of fast electrons induced by return current during the interaction of a short-pulse high-intensity laser on a metal solid target

    Science.gov (United States)

    Compant La Fontaine, A.

    2018-04-01

    During the interaction of a short-pulse high-intensity laser with the preplasma produced by the pulse's pedestal in front of a high-Z metal solid target, high-energy electrons are produced, which in turn create an X-ray source by interacting with the atoms of the converter target. The current brought by the hot electrons is almost completely neutralized by a return current j → driven by the background electrons of the conductive target, and the force exerted on the hot electrons by the electric field E → which induces Ohmic heating j → .E → , produced by the background electrons, reduces the energy of the hot electrons and thus lowers the X-ray emission and photon dose. This effect is analyzed here by means of a simple 1-D temperature model which contains the most significant terms of the relativistic Fokker-Planck equation with electron multiple scattering, and the energy equations of ions, hot, and cold electrons are then solved numerically. This Ohmic heating energy loss fraction τOh is introduced as a corrective term in an improved photon dose model. For instance, for a ps laser pulse with 10 μm spot size, the dose obtained with a tantalum target is reduced by less than about 10% to 40% by the Ohmic heating, depending upon the plasma scale length, target thickness, laser parameters, and in particular its spot size. The laser and plasma parameters may be optimized to limit the effect of Ohmic heating, for instance at a small plasma scale length or small laser spot size. Conversely, others regimes not suitable for dose production are identified. For instance, the resistive heating is enhanced in a foam target or at a long plasma scale length and high laser spot size and intensity, as the mean emission angle θ0 of the incident hot electron bunch given by the ponderomotive force is small; thus, the dose produced by a laser interacting in a gas jet may be inhibited under these circumstances. The resistive heating may also be maximized in order to reduce

  1. White-centred retinal haemorrhages (Roth spots).

    OpenAIRE

    Ling, R.; James, B.

    1998-01-01

    Roth spots (white-centred retinal haemorrhages) were classically described as septic emboli lodged in the retina of patients with subacute bacterial endocarditis. Indeed many have considered Roth spots pathognomonic for this condition. More recent histological evidence suggests, however, that they are not foci of bacterial abscess. Instead, they are nonspecific and may be found in many other diseases. A review of the histology and the pathogenesis of these white-centred haemorrhages will be p...

  2. X-ray spot film device

    International Nuclear Information System (INIS)

    1981-01-01

    Improvements are described in an X-ray spot film device which is used in conjunction with an X-ray table to make a selected number of radiographic exposures on a single film and to perform fluoroscopic examinations. To date, the spot film devices consist of two X-ray field defining masks, one of which is moved manually. The present device is more convenient to use and speeds up the procedure. (U.K.)

  3. Potential beneficial effects of electron-hole plasmas created in silicon sensors by XFEL-like high intensity pulses for detector development

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, Joel T.; Becker, Julian; Shanks, Katherine S.; Philipp, Hugh T.; Tate, Mark W. [Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853 (United States); Gruner, Sol M., E-mail: smg26@cornell.edu [Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853 (United States); Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States)

    2016-07-27

    There is a compelling need for a high frame rate imaging detector with a wide dynamic range, from single x-rays/pixel/pulse to >10{sup 6} x-rays/pixel/pulse, that is capable of operating at both x-ray free electron laser (XFEL) and 3rd generation sources with sustained fluxes of > 10{sup 11} x-rays/pixel/s [1, 2, 3]. We propose to meet these requirements with the High Dynamic Range Pixel Array Detector (HDR-PAD) by (a) increasing the speed of charge removal strategies [4], (b) increasing integrator range by implementing adaptive gain [5], and (c) exploiting the extended charge collection times of electron-hole pair plasma clouds that form when a sufficiently large number of x-rays are absorbed in a detector sensor in a short period of time [6]. We have developed a measurement platform similar to the one used in [6] to study the effects of high electron-hole densities in silicon sensors using optical lasers to emulate the conditions found at XFELs. Characterizations of the employed tunable wavelength laser with picosecond pulse duration have shown Gaussian focal spots sizes of 6 ± 1 µm rms over the relevant spectrum and 2 to 3 orders of magnitude increase in available intensity compared to previous measurements presented in [6]. Results from measurements on a typical pixelated silicon diode intended for use with the HDR-PAD (150 µm pixel size, 500 µm thick sensor) are presented.

  4. Intra-pulse transition between ion acceleration mechanisms in intense laser-foil interactions

    Energy Technology Data Exchange (ETDEWEB)

    Padda, H.; King, M.; Gray, R. J.; Powell, H. W.; Gonzalez-Izquierdo, B.; Wilson, R.; Dance, R. J.; MacLellan, D. A.; Butler, N. M. H.; Capdessus, R.; McKenna, P., E-mail: paul.mckenna@strath.ac.uk [SUPA Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Stockhausen, L. C. [Centro de Laseres Pulsados (CLPU), Parque Cientifico, Calle del Adaja s/n. 37185 Villamayor, Salamanca (Spain); Carroll, D. C. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Oxfordshire OX11 0QX (United Kingdom); Yuan, X. H. [Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai 200240 (China); Borghesi, M. [Centre for Plasma Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom); Neely, D. [SUPA Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Central Laser Facility, STFC Rutherford Appleton Laboratory, Oxfordshire OX11 0QX (United Kingdom)

    2016-06-15

    Multiple ion acceleration mechanisms can occur when an ultrathin foil is irradiated with an intense laser pulse, with the dominant mechanism changing over the course of the interaction. Measurement of the spatial-intensity distribution of the beam of energetic protons is used to investigate the transition from radiation pressure acceleration to transparency-driven processes. It is shown numerically that radiation pressure drives an increased expansion of the target ions within the spatial extent of the laser focal spot, which induces a radial deflection of relatively low energy sheath-accelerated protons to form an annular distribution. Through variation of the target foil thickness, the opening angle of the ring is shown to be correlated to the point in time transparency occurs during the interaction and is maximized when it occurs at the peak of the laser intensity profile. Corresponding experimental measurements of the ring size variation with target thickness exhibit the same trends and provide insight into the intra-pulse laser-plasma evolution.

  5. Pseudospark switches (PSS) for pulsed power applications

    Energy Technology Data Exchange (ETDEWEB)

    Heine, F; Prucker, U; Frank, K; Goertler, A; Schwandner, A; Tkotz, R; Hoffmann, D H.H.; Christiansen, J [Univ. of Erlangen (Germany). Physics Dept. I

    1997-12-31

    Based on the pseudospark discharge, a low pressure gas discharge in a special geometry, fast closing switches for different pulsed power applications have been designed. Medium power PSS ({<=} 30 kA peak current) were used in laser circuits whereas high current PSS are tested successfully in high current pulsed power applications ({<=} 200 kA). For currents of a few kA the discharge is supported by cathode spots on the cold cathode surface. For higher currents, anode activity is observed too. Inserting semiconductor material seems not only to suppress high erosive spot formation but to support diffuse large-area electrode emission. A different approach to solving the problem of lowering the erosion rate is the multichannel PSS (MUPS). In order to distribute the discharge current to more than one single channel, three or more discharge channels are radial or coaxial arranged. With regard to high voltage applications the maximum hold-off voltage was increased by adding an intermediate electrode. (author). 1 figs., 12 refs.

  6. System for determining sizes of biological macromolecules

    International Nuclear Information System (INIS)

    Nelson, R.M.; Danby, P.C.

    1987-01-01

    An electrophoresis system for determining the sizes of radiolabelled biological macromolecules is described. It comprises a cell containing an electrophoresis gel and having at least one lane, a voltage source connected across the gel for effecting the movement of macromolecules in the lane, a detector fixed relative to the moving molecules for generating electrical pulses responsive to signals emitted by the radiolabelled molecules; a pulse processor for counting the pulse rate, and a computational device for comparing the pulse rate to a predetermined value. (author)

  7. Modeling deflagration waves out of hot spots

    Science.gov (United States)

    Partom, Yehuda

    2017-01-01

    It is widely accepted that shock initiation and detonation of heterogeneous explosives comes about by a two-step process known as ignition and growth. In the first step a shock sweeping through an explosive cell (control volume) creates hot spots that become ignition sites. In the second step, deflagration waves (or burn waves) propagate out of those hot spots and transform the reactant in the cell into reaction products. The macroscopic (or average) reaction rate of the reactant in the cell depends on the speed of those deflagration waves and on the average distance between neighboring hot spots. Here we simulate the propagation of deflagration waves out of hot spots on the mesoscale in axial symmetry using a 2D hydrocode, to which we add heat conduction and bulk reaction. The propagation speed of the deflagration waves may depend on both pressure and temperature. It depends on pressure for quasistatic loading near ambient temperature, and on temperature at high temperatures resulting from shock loading. From the simulation we obtain deflagration fronts emanating out of the hot spots. For 8 to 13 GPa shocks, the emanating fronts propagate as deflagration waves to consume the explosive between hot spots. For higher shock levels deflagration waves may interact with the sweeping shock to become detonation waves on the mesoscale. From the simulation results we extract average deflagration wave speeds.

  8. Unblinding the dark matter blind spots

    International Nuclear Information System (INIS)

    Han, Tao; Kling, Felix

    2017-01-01

    The dark matter (DM) blind spots in the Minimal Supersymmetric Standard Model (MSSM) refer to the parameter regions where the couplings of the DM particles to the Z-boson or the Higgs boson are almost zero, leading to vanishingly small signals for the DM direct detections. In this paper, we carry out comprehensive analyses for the DM searches under the blind-spot scenarios in MSSM. Guided by the requirement of acceptable DM relic abundance, we explore the complementary coverage for the theory parameters at the LHC, the projection for the future underground DM direct searches, and the indirect searches from the relic DM annihilation into photons and neutrinos. We find that (i) the spin-independent (SI) blind spots may be rescued by the spin-dependent (SD) direct detection in the future underground experiments, and possibly by the indirect DM detections from IceCube and SuperK neutrino experiments; (ii) the detection of gamma rays from Fermi-LAT may not reach the desirable sensitivity for searching for the DM blind-spot regions; (iii) the SUSY searches at the LHC will substantially extend the discovery region for the blind-spot parameters. As a result, the dark matter blind spots thus may be unblinded with the collective efforts in future DM searches.

  9. Dual focal-spot imaging for phase extraction in phase-contrast radiography

    International Nuclear Information System (INIS)

    Donnelly, Edwin F.; Price, Ronald R.; Pickens, David R.

    2003-01-01

    The purpose of this study was to evaluate dual focal spot imaging as a method for extracting the phase component from a phase-contrast radiography image. All measurements were performed using a microfocus tungsten-target x-ray tube with an adjustable focal-spot size (0.01 mm to 0.045 mm). For each object, high-resolution digital radiographs were obtained with two different focal spot sizes to produce matched image pairs in which all other geometric variables as well as total exposure and tube kVp were held constant. For each image pair, a phase extraction was performed using pixel-wise division. The phase-extracted image resulted in an image similar to the standard image processing tool commonly referred to as 'unsharp masking' but with the additional edge-enhancement produced by phase-contrast effects. The phase-extracted image illustrates the differences between the two images whose imaging parameters differ only in focal spot size. The resulting image shows effects from both phase contrast as well as geometric unsharpness. In weakly attenuating materials the phase-contrast effect predominates, while in strongly attenuating materials the phase effects are so small that they are not detectable. The phase-extracted image in the strongly attenuating object reflects differences in geometric unsharpness. The degree of phase extraction depends strongly on the size of the smallest focal spot used. This technique of dual-focal spot phase-contrast radiography provides a simple technique for phase-component (edge) extraction in phase-contrast radiography. In strongly attenuating materials the phase-component is overwhelmed by differences in geometric unsharpness. In these cases the technique provides a form of unsharp masking which also accentuates the edges. Thus, the two effects are complimentary and may be useful in the detection of small objects

  10. Prediction of protein interaction hot spots using rough set-based multiple criteria linear programming.

    Science.gov (United States)

    Chen, Ruoying; Zhang, Zhiwang; Wu, Di; Zhang, Peng; Zhang, Xinyang; Wang, Yong; Shi, Yong

    2011-01-21

    Protein-protein interactions are fundamentally important in many biological processes and it is in pressing need to understand the principles of protein-protein interactions. Mutagenesis studies have found that only a small fraction of surface residues, known as hot spots, are responsible for the physical binding in protein complexes. However, revealing hot spots by mutagenesis experiments are usually time consuming and expensive. In order to complement the experimental efforts, we propose a new computational approach in this paper to predict hot spots. Our method, Rough Set-based Multiple Criteria Linear Programming (RS-MCLP), integrates rough sets theory and multiple criteria linear programming to choose dominant features and computationally predict hot spots. Our approach is benchmarked by a dataset of 904 alanine-mutated residues and the results show that our RS-MCLP method performs better than other methods, e.g., MCLP, Decision Tree, Bayes Net, and the existing HotSprint database. In addition, we reveal several biological insights based on our analysis. We find that four features (the change of accessible surface area, percentage of the change of accessible surface area, size of a residue, and atomic contacts) are critical in predicting hot spots. Furthermore, we find that three residues (Tyr, Trp, and Phe) are abundant in hot spots through analyzing the distribution of amino acids. Copyright © 2010 Elsevier Ltd. All rights reserved.

  11. Spot weld arrangement effects on the fatigue behavior of multi-spot welded joints

    International Nuclear Information System (INIS)

    Hassanifard, Soran; Zehsaz, Mohammad; Esmaeili, Firooz

    2011-01-01

    In the present study, the effects of spot weld arrangements in multi-spot welded joints on the fatigue behavior of the joints are studied. Three different four-spot welded joints are considered: one-row four-spot parallel to the loading direction, one-row four-spot perpendicular to the loading direction and two-row four-spot weld specimens. The experimental fatigue test results reveal that the differences between the fatigue lives of three spot welded types in the low cycle regime are more considerable than those in the high cycle regime. However, all kinds of spot weld specimens have similar fatigue strength when approaching a million cycles. A non-linear finite element analysis is performed to obtain the relative stress gradients, effective distances and notch strength reduction factors based on the volumetric approach. The work here shows that the volumetric approach does a very good job in predicting the fatigue life of the multi-spot welded joints

  12. Spatial and temporal distributions of Martian north polar cold spots before, during, and after the global dust storm of 2001

    Science.gov (United States)

    Cornwall, C.; Titus, T.N.

    2009-01-01

    In the 1970s, Mariner and Viking observed features in the Mars northern polar region that were a few hundred kilometers in diameter with 20 fj,m brightness temperatures as low as 130 K (considerably below C02 ice sublimation temperatures). Over the past decade, studies have shown that these areas (commonly called "cold spots") are usually due to emissivity effects of frost deposits and occasionally to active C02 snowstorms. Three Mars years of Mars Global Surveyor Thermal Emission Spectrometer data were used to observe autumn and wintertime cold spot activity within the polar regions. Many cold spots formed on or near scarps of the perennial cap, probably induced by adiabatic cooling due to orographic lifting. These topographically associated cold spots were often smaller than those that were not associated with topography. We determined that initial grain sizes within the cold spots were on the order of a few millimeters, assuming the snow was uncontaminated by dust or water ice. On average, the half-life of the cold spots was 5 Julian days. The Mars global dust storm in 2001 significantly affected cold spot activity in the north polar region. Though overall perennial cap cold spot activity seemed unaffected, the distribution of cold spots did change by a decrease in the number of topographically associated cold spots and an increase in those not associated with topography. We propose that the global dust storm affected the processes that form cold spots and discuss how the global dust storm may have affected these processes. ?? 2009 by the American Geophysical Union.

  13. Heat-pulse flowmeter for a liquid breeder blanket

    International Nuclear Information System (INIS)

    Kondo, Masatoshi; Shibano, Kyohei; Tanaka, Teruya; Muroga, Takeo

    2013-01-01

    Liquid metals Li, Pb-17Li and Sn-20Li are candidate liquid breeders in fusion reactors. The development of a flowmeter that can be applied to high-temperature liquid metals is an important issue. A heat-pulse flowmeter is proposed in the present study. Its basic performance was investigated by means of a loop experiment with Pb-17Li and a numerical simulation. The temperature distribution in flowing Pb-17Li was obtained by local transient heating of the outer surface of a loop tube. The temperature distribution gradually changed and resembled the movement of a hot spot, which had a higher temperature than its surroundings. This hot spot moved along the flow and passed through the tips of the thermocouples. The change in temperature distribution with the movement of the hot spot was monitored by three thermocouples exposed to the Pb-17Li flow. The results of the loop experiments were numerically simulated by assuming a certain flow rate, and the temperature profile obtained in the loop experiment was in agreement with the simulation results. The time taken by the hot spot to pass through the tips of the thermocouples was measured and simulated, and the correlation between this time and the average flow velocity was evaluated. The results indicated the average flow velocity can be obtained using the heat-pulse flowmeter proposed in this study. (author)

  14. Pulse Holography: Review Of Applications

    Science.gov (United States)

    Smigielski, Paul

    1990-04-01

    Pulse Holography includes studies concerning time-varying phase objects as well as time-varying reflective objects involving the use of pulse ruby- and YAG-lasers. The paper is divided in two parts. One part concerns the direct use of 3-1) images reconstructed from holograms, i.e. applications to particle size analysis, 3-I) velocity measurements, 3-I) cinematography ... The second part describes applications using holographic interferometry in laboratory or in an industrial environment, i.e. applications to fluid mechanics, vibration analysis, non-destructive testing ... Recent developments including interferornetric cineholography, fiber optics, measurement of non-interferometric displacements ... , are also described. The future of holography depends to a great extent on data processing and interpretation of informations contained in holograms or holographic intericrograms. Therefore, we give the state of art in this field in Europe illustrated with some industrial applications.

  15. Effect of the laser spot shape on spatial distribution of the ion bunch accelerated in a superstrong field

    International Nuclear Information System (INIS)

    Scientific research Institute for Optoelectronic Instrument Engineering, Leningrad region (Russian Federation))" data-affiliation=" (Public Limited Company Scientific research Institute for Optoelectronic Instrument Engineering, Leningrad region (Russian Federation))" >Komarov, V M; Scientific research Institute for Optoelectronic Instrument Engineering, Leningrad region (Russian Federation))" data-affiliation=" (Public Limited Company Scientific research Institute for Optoelectronic Instrument Engineering, Leningrad region (Russian Federation))" >Charukhchev, A V; S.I.Vavilov State Optical Institute (FSUE GOI), St.Petersburg (Russian Federation))" data-affiliation=" (Federal State Unitary Enterprise All-Russian Scientific Center S.I.Vavilov State Optical Institute (FSUE GOI), St.Petersburg (Russian Federation))" >Andreev, A A; S.I.Vavilov State Optical Institute (FSUE GOI), St.Petersburg (Russian Federation))" data-affiliation=" (Federal State Unitary Enterprise All-Russian Scientific Center S.I.Vavilov State Optical Institute (FSUE GOI), St.Petersburg (Russian Federation))" >Platonov, K Yu

    2014-01-01

    We have investigated the effect of the laser spot shape on the spatial distribution of accelerated ions on the front and back sides of a thin target irradiated by a picosecond laser pulse having the intensity of (3 – 4) × 10 18 W cm -2 . Experimental data are compared with numerical calculations. It is shown that the spatial structure of the ion bunch on the front side of the target resembles the laser spot structure rotated by 90°. (interaction of laser radiation with matter. laser plasma)

  16. Effect of the laser spot shape on spatial distribution of the ion bunch accelerated in a superstrong field

    Energy Technology Data Exchange (ETDEWEB)

    Komarov, V M; Charukhchev, A V [Public Limited Company " Scientific research Institute for Optoelectronic Instrument Engineering" , Leningrad region (Russian Federation); Andreev, A A; Platonov, K Yu [Federal State Unitary Enterprise All-Russian Scientific Center " S.I.Vavilov State Optical Institute" (FSUE GOI), St.Petersburg (Russian Federation)

    2014-12-31

    We have investigated the effect of the laser spot shape on the spatial distribution of accelerated ions on the front and back sides of a thin target irradiated by a picosecond laser pulse having the intensity of (3 – 4) × 10{sup 18} W cm{sup -2}. Experimental data are compared with numerical calculations. It is shown that the spatial structure of the ion bunch on the front side of the target resembles the laser spot structure rotated by 90°. (interaction of laser radiation with matter. laser plasma)

  17. Asymmetrical color filling-in from the nasal to the temporal side of the blind spot

    Science.gov (United States)

    Li, Hui; Luo, Junxiang; Lu, Yiliang; Kan, Janis; Spillmann, Lothar; Wang, Wei

    2014-01-01

    The physiological blind spot, corresponding to the optic disk in the retina, is a relatively large (6 × 8°) area in the visual field that receives no retinal input. However, we rarely notice the existence of it in daily life. This is because the blind spot fills in with the brightness, color, texture, and motion of the surround. The study of filling-in enables us to better understand the creative nature of the visual system, which generates perceptual information where there is none. Is there any retinotopic rule in the color filling-in of the blind spot? To find out, we used mono-colored and bi-colored annuli hugging the boundary of the blind spot. We found that mono-colored annuli filled in the blind spot uniformly. By contrast, bi-colored annuli, where one half had a given color, while the other half had a different one, filled in the blind spot asymmetrically. Specifically, the color surrounding the nasal half typically filled in about 75% of the blind spot area, whereas the color surrounding the temporal half filled in only about 25%. This asymmetry was dependent on the relative size of the half rings, but not the two colors used, and was absent when the bi-colored annulus was rotated by 90°. Here, the two colors on the upper and lower sides of the blind spot filled in the enclosed area equally. These results suggest that the strength of filling-in decreases with distance from the fovea consistent with the decrease of the cortical magnification factor. PMID:25100977

  18. Spotted owl ecology: theory and methodology—a reply to Rosenberg et al.

    Science.gov (United States)

    A.B. Carey

    1995-01-01

    In their remarks on the study of Spotted Owls (Strix occidentalis) by Carey et al. (1992). Rosenberg et al. (1994) questioned the appropriateness of certain analyses and methods, and specific interpretation of the results. Herein, I respond to the comments of Rosenberg et al. (1994), which are summarized in italics.Sample sizes were nor...

  19. Comparative habitat use of sympatric Mexican spotted and great horned owls

    Science.gov (United States)

    Joseph L. Ganey; William M. Block; Jeffrey S. Jenness; Randolph A. Wilson

    1997-01-01

    To provide information on comparative habitat use, we studied radiotagged Mexican spotted owls (Strix occidentalis lucida: n = 13) and great horned owls (Bubo virginianus: n = 4) in northern Arizona. Home-range size (95% adaptive kernel estimate) did not differ significantly between species during either the breeding or nonbreeding...

  20. 7 CFR 28.423 - Middling Spotted Color.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Middling Spotted Color. 28.423 Section 28.423... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Spotted Cotton § 28.423 Middling Spotted Color. Middling Spotted Color is color which is within the range represented by a set of samples in the custody of...