WorldWideScience

Sample records for repetition rate injection

  1. Generation of tunable, high repetition rate frequency combs with equalized spectra using carrier injection based silicon modulators

    Science.gov (United States)

    Nagarjun, K. P.; Selvaraja, Shankar Kumar; Supradeepa, V. R.

    2016-03-01

    High repetition-rate frequency combs with tunable repetition rate and carrier frequency are extensively used in areas like Optical communications, Microwave Photonics and Metrology. A common technique for their generation is strong phase modulation of a CW-laser. This is commonly implemented using Lithium-Niobate based modulators. With phase modulation alone, the combs have poor spectral flatness and significant number of missing lines. To overcome this, a complex cascade of multiple intensity and phase modulators are used. A comb generator on Silicon based on these principles is desirable to enable on-chip integration with other functionalities while reducing power consumption and footprint. In this work, we analyse frequency comb generation in carrier injection based Silicon modulators. We observe an interesting effect in these comb generators. Enhanced absorption accompanying carrier injection, an undesirable effect in data modulators, shapes the amplitude here to enable high quality combs from a single modulator. Thus, along with reduced power consumption to generate a specific number of lines, the complexity has also been significantly reduced. We use a drift-diffusion solver and mode solver (Silvaco TCAD) along with Soref-Bennett relations to calculate the variations in refractive indices and absorption of an optimized Silicon PIN - waveguide modulator driven by an unbiased high frequency (10 Ghz) voltage signal. Our simulations demonstrate that with a device length of 1 cm, a driving voltage of 2V and minor shaping with a passive ring-resonator filter, we obtain 37 lines with a flatness better than 5-dB across the band and power consumption an order of magnitude smaller than Lithium-Niobate modulators.

  2. A miniature high repetition rate shock tube.

    Science.gov (United States)

    Tranter, R S; Lynch, P T

    2013-09-01

    A miniature high repetition rate shock tube with excellent reproducibility has been constructed to facilitate high temperature, high pressure, gas phase experiments at facilities such as synchrotron light sources where space is limited and many experiments need to be averaged to obtain adequate signal levels. The shock tube is designed to generate reaction conditions of T > 600 K, P shock waves with predictable characteristics are created, repeatably. Two synchrotron-based experiments using this apparatus are also briefly described here, demonstrating the potential of the shock tube for research at synchrotron light sources.

  3. Soliton repetition rate in a silicon-nitride microresonator

    CERN Document Server

    Bao, Chengying; Wang, Cong; Jaramillo-Villegas, Jose A; Leaird, Daniel E; Qi, Minghao; Weiner, Andrew M

    2016-01-01

    The repetition rate of a Kerr comb comprising a single soliton in an anomalous dispersion silicon nitride microcavity is measured as a function of pump frequency tuning. The contributions from the Raman soliton self-frequency shift (SSFS) and from thermal effects are evaluated both experimentally and theoretically; the SSFS is found to dominate the changes in repetition rate. The relationship between the changes in repetition rate and pump frequency detuning is found to be independent of the nonlinearity coefficient and dispersion of the cavity. Modeling of the repetition rate change by using the generalized Lugiato-Lefever equation is discussed; the Kerr shock is found to have only a minor effect on repetition rate for cavity solitons with duration down to ~50 fs.

  4. Soliton repetition rate in a silicon-nitride microresonator.

    Science.gov (United States)

    Bao, Chengying; Xuan, Yi; Wang, Cong; Jaramillo-Villegas, Jose A; Leaird, Daniel E; Qi, Minghao; Weiner, Andrew M

    2017-02-15

    The repetition rate of a Kerr comb composed of a single soliton in an anomalous group velocity dispersion silicon-nitride microcavity is measured as a function of pump frequency. By comparing operation in the soliton and non-soliton states, the contributions from the Raman soliton self-frequency shift (SSFS) and the thermal effects are evaluated; the SSFS is found to dominate the changes in the repetition rate, similar to silica cavities. The relationship between the changes in the repetition rate and the pump frequency detuning is found to be independent of the nonlinearity coefficient and dispersion of the cavity. Modeling of the repetition rate change by using the generalized Lugiato-Lefever equation is discussed; the Kerr shock is found to have only a minor effect on repetition rate for cavity solitons with duration down to ∼50  fs.

  5. Generation of low-timing-jitter femtosecond pulse trains with 2 GHz repetition rate via external repetition rate multiplication.

    Science.gov (United States)

    Chen, Jian; Sickler, Jason W; Fendel, Peter; Ippen, Erich P; Kärtner, Franz X; Wilken, Tobias; Holzwarth, Ronald; Hänsch, Theodor W

    2008-05-01

    Generation of low-timing-jitter 150 fs pulse trains at 1560 nm with 2 GHz repetition rate is demonstrated by locking a 200 MHz fundamental polarization additive-pulse mode-locked erbium fiber laser to high-finesse external Fabry-Perot cavities. The timing jitter and relative intensity noise of the repetition-rate multiplied pulse train are investigated.

  6. Sensor for Injection Rate Measurements

    Directory of Open Access Journals (Sweden)

    Milan Marcic

    2006-10-01

    Full Text Available A vast majority of the medium and high speed Diesel engines are equipped withmulti-hole injection nozzles nowadays. Inaccuracies in workmanship and changinghydraulic conditions in the nozzles result in differences in injection rates between individualinjection nozzle holes. The new deformational measuring method described in the paperallows injection rate measurement in each injection nozzle hole. The differences in injectionrates lead to uneven thermal loads of Diesel engine combustion chambers. All today knownmeasuring method, such as Bosch and Zeuch give accurate results of the injection rate indiesel single-hole nozzles. With multihole nozzles they tell us nothing about possibledifferences in injection rates between individual holes of the nozzle. At deformationalmeasuring method, the criterion of the injected fuel is expressed by the deformation ofmembrane occurring due to the collision of the pressure wave against the membrane. Thepressure wave is generated by the injection of the fuel into the measuring space. For eachhole of the nozzle the measuring device must have a measuring space of its own into whichfuel is injected as well as its measuring membrane and its own fuel outlet. Duringmeasurements procedure the measuring space must be filled with fuel to maintain anoverpressure of 5 kPa. Fuel escaping from the measuring device is conducted into thegraduated cylinders for measuring the volumetric flow through each hole of the nozzle.Themembrane deformation is assessed by strain gauges. They are glued to the membrane andforming the full Wheatstone’s bridge. We devoted special attention to the membrane shapeand temperature compensation of the strain gauges.

  7. Properties of water surface discharge at different pulse repetition rates

    Energy Technology Data Exchange (ETDEWEB)

    Ruma,; Yoshihara, K. [Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555 (Japan); Hosseini, S. H. R., E-mail: hosseini@kumamoto-u.ac.jp; Sakugawa, T.; Akiyama, H. [Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555 (Japan); Institute of Pulsed Power Science, Kumamoto University, Kumamoto 860-8555 (Japan); Akiyama, M. [Department of Electrical and Electronic Engineering, Kagoshima University, Kagoshima 890-0065 (Japan); Lukeš, P. [Institute of Plasma Physics, AS CR, Prague, Prague 18200 (Czech Republic)

    2014-09-28

    The properties of water surface discharge plasma for variety of pulse repetition rates are investigated. A magnetic pulse compression (MPC) pulsed power modulator able to deliver pulse repetition rates up to 1000 Hz, with 0.5 J per pulse energy output at 25 kV, was used as the pulsed power source. Positive pulse with a point-to-plane electrode configuration was used for the experiments. The concentration and production yield of hydrogen peroxide (H₂O₂) were quantitatively measured and orange II organic dye was treated, to evaluate the chemical properties of the discharge reactor. Experimental results show that the physical and chemical properties of water surface discharge are not influenced by pulse repetition rate, very different from those observed for under water discharge. The production yield of H₂O₂ and degradation rate per pulse of the dye did not significantly vary at different pulse repetition rates under a constant discharge mode on water surface. In addition, the solution temperature, pH, and conductivity for both water surface and underwater discharge reactors were measured to compare their plasma properties for different pulse repetition rates. The results confirm that surface discharge can be employed at high pulse repetition rates as a reliable and advantageous method for industrial and environmental decontamination applications.

  8. Breakdown behavior of electronics at variable pulse repetition rates

    OpenAIRE

    Korte, S.; H. Garbe

    2006-01-01

    The breakdown behavior of electronics exposed to single transient electromagnetic pulses is subject of investigations for several years. State-of-the-art pulse generators additionally provide the possibility to generate pulse sequences with variable pulse repetition rate. In this article the influence of this repetition rate variation on the breakdown behavior of electronic systems is described. For this purpose microcontroller systems are examined during line-led exposure to pulses with repe...

  9. High Repetition Rate and Frequency Stabilized Ho:YLF Laser for CO2 Differential Absorption Lidar

    Science.gov (United States)

    Bai, Yingxin; Yu, Jirong; Petros, M.; Petzar, Pau; Trieu, Bo; Lee, Hyung; Singh, U.

    2009-01-01

    High repetition rate operation of an injection seeded Ho:YLF laser has been demonstrated. For 1 kHz operation, the output pulse energy reaches 5.8mJ and the optical-to-optical efficiency is 39% when the pump power is 14.5W.

  10. Single Longitudinal Mode, High Repetition Rate, Q-switched Ho:YLF Laser for Remote Sensing

    Science.gov (United States)

    Bai, Yingxin; Yu, Jirong; Petzar, Paul; Petros, M.; Chen, Songsheng; Trieu, Bo; Lee, Nyung; Singh, U.

    2009-01-01

    Ho:YLF/LuLiF lasers have specific applications for remote sensing such as wind-speed measurement and carbon dioxide (CO2) concentration measurement in the atmosphere because the operating wavelength (around 2 m) is located in the eye-safe range and can be tuned to the characteristic lines of CO2 absorption and there is strong backward scattering signal from aerosol (Mie scattering). Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of with a repetition rate of 5 Hz and pulse energy of 75 mJ [1]. For highly precise CO2 measurements with coherent detection technique, a laser with high repetition rate is required to averaging out the speckle effect [2]. In addition, laser efficiency is critically important for the air/space borne lidar applications, because of the limited power supply. A diode pumped Ho:Tm:YLF laser is difficult to efficiently operate in high repetition rate due to the large heat loading and up-conversion. However, a Tm:fiber laser pumped Ho:YLF laser with low heat loading can be operated at high repetition rates efficiently [3]. No matter whether wind-speed or carbon dioxide (CO2) concentration measurement is the goal, a Ho:YLF/LuLiF laser as the transmitter should operate in a single longitudinal mode. Injection seeding is a valid technique for a Q-switched laser to obtain single longitudinal mode operation. In this paper, we will report the new results for a single longitudinal mode, high repetition rate, Q-switched Ho:YLF laser. In order to avoid spectral hole burning and make injection seeding easier, a four mirror ring cavity is designed for single longitudinal mode, high repetition rate Q-switched Ho:YLF laser. The ramp-fire technique is chosen for injection seeding.

  11. ROBUST REPETITIVE CONTROL FOR IMPROVING RATE SMOOTHNESS OF TEST TURNTABLE

    Institute of Scientific and Technical Information of China (English)

    LIUYu; ZENGMing; SUBao-ku

    2005-01-01

    A robust repetitive control scheme is used to improve the rate smoothness of a brushless DC motor (BLDCM) driven test turntable. The method synthesizes variable structure control (VSC) laws and repetitive control (RC) laws in a complementary manner. The VSC strategy can stabilize the system and suppress uncertainties, such as the aperiodic disturbance and noises, while RC strategy can eliminate the periodic rate fluctuation in a steady state. The convergence of the repetitive learning process is also guaranteed by VSC. A general nonlinear system model is discussed. The model can be considered as an extension of BLDCMs. The stability and asymptotic position tracking performance are validated by using Lyapunov functions. Simulation results show the effectiveness of the proposed approach for improving the rate smoothness.

  12. Demonstration of a high repetition rate capillary discharge waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Gonsalves, A. J., E-mail: ajgonsalves@lbl.gov; Pieronek, C.; Daniels, J.; Bulanov, S. S.; Waldron, W. L.; Mittelberger, D. E.; Leemans, W. P. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Liu, F.; Antipov, S.; Butler, J. E. [Euclid TechLabs, Gaithersburg, Maryland 20879 (United States); Bobrova, N. A.; Sasorov, P. V. [Keldysh Institute of Applied Mathematics, Moscow (Russian Federation)

    2016-01-21

    A hydrogen-filled capillary discharge waveguide operating at kHz repetition rates is presented for parameters relevant to laser plasma acceleration (LPA). The discharge current pulse was optimized for erosion mitigation with laser guiding experiments and MHD simulation. Heat flow simulations and measurements showed modest temperature rise at the capillary wall due to the average heat load at kHz repetition rates with water-cooled capillaries, which is promising for applications of LPAs such as high average power radiation sources.

  13. Medium Repetition Rate TEA Laser For Industrial Applications

    Science.gov (United States)

    Walter, Bruno

    1987-09-01

    The design and performance of an inexpensive compact repetitively pulsed TEA CO2 laser is described. The device uses a modified corona preionization technique and a fast transverse gas flow to achieve high repetition rates. An output energy of 500 mJ per pulse and an out-put power of 6.2W at 40Hz have been obtained. Due to the small energy needed for preionization, the efficiency of the device is high, whereas the gas dissociation is low when compared with commercial laser systems. This results in the relatively small fresh laser gas exchange of 20 ltr h-1 for long term operation.

  14. MOUSE ANTIBODY RESPONSE FOLLOWING REPETITIVE INJECTIONS OF GAMMA-IRRADIATED HUMAN PLACENTA COLLAGENA

    Institute of Scientific and Technical Information of China (English)

    刘秉慈; MelvinSpira; 许增禄

    1994-01-01

    Injectable bovine collagen has been used clinically for years.But both the necessity of repeated injections to maintain corrections and the question of adverse allergic reactions developing from the use of a xenogenic collagen have been an area of serious concern.To overoome these adyerse effects,we have developed injectable collagen preparations from human placenta.Gamma irradiation was used for sterilization and crosslinking of the collagen.We observed the mouse immune respose to gamma-irradiated human placenta soluble and insoluble collagen follow-ing multiple injections.After six injections of these materials,no total IgG level increase was found,nor was anti-body specifically directed against human collagen found.Mouse antibody levels were also observed following Zyderm Ⅱ and Zyplast repetitive injections and follow-ing repetitive implantations of coated vicryl and chromic gut.No humoral immune response was found in this het-erologous type system.

  15. High voltage high repetition rate pulse using Marx topology

    Science.gov (United States)

    Hakki, A.; Kashapov, N.

    2015-06-01

    The paper describes Marx topology using MOSFET transistors. Marx circuit with 10 stages has been done, to obtain pulses about 5.5KV amplitude, and the width of the pulses was about 30μsec with a high repetition rate (PPS > 100), Vdc = 535VDC is the input voltage for supplying the Marx circuit. Two Ferrite ring core transformers were used to control the MOSFET transistors of the Marx circuit (the first transformer to control the charging MOSFET transistors, the second transformer to control the discharging MOSFET transistors).

  16. Bottle microresonator broadband and low repetition rate frequency comb generator

    CERN Document Server

    Dvoyrin, V

    2016-01-01

    We propose a new type of broadband and low repetition rate frequency comb generator which has the shape of an elongated and nanoscale-shallow optical bottle microresonator created at the surface of an optical fiber. The free spectral range (FSR) of the broadband azimuthal eigenfrequency series of this resonator is the exact multiple of the FSR of the dense and narrowband axial series. The effective radius variation of the microresonator is close to a parabola with a nanoscale height which is greater or equal to lambda/2pi*n0 (here lambda is the characteristic radiation wavelength and n0 is the refractive index of the microresonator material). Overall, the microresonator possesses a broadband, small FSR, and accurately equidistant spectrum convenient for the generation of a broadband and low repetition rate optical frequency comb. It is shown that this comb can be generated by pumping with a cw laser, which radiation frequency matches a single axial eigenfrequency of the microresonator, or, alternatively, by p...

  17. Final Report, Photocathodes for High Repetition Rate Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Zvi, Ilan [Stony Brook University

    2014-04-20

    This proposal brought together teams at Brookhaven National Laboratory (BNL), Lawrence Berkeley National Laboratory (LBNL) and Stony Brook University (SBU) to study photocathodes for high repetition rate light sources such as Free Electron Lasers (FEL) and Energy Recovery Linacs (ERL). The work done under this grant comprises a comprehensive program on critical aspects of the production of the electron beams needed for future user facilities. Our program pioneered in situ and in operando diagnostics for alkali antimonide growth. The focus is on development of photocathodes for high repetition rate Free Electron Lasers (FELs) and Energy Recovery Linacs (ERLs), including testing SRF photoguns, both normal-conducting and superconducting. Teams from BNL, LBNL and Stony Brook University (SBU) led this research, and coordinated their work over a range of topics. The work leveraged a robust infrastructure of existing facilities and the support was used for carrying out the research at these facilities. The program concentrated in three areas: a) Physics and chemistry of alkali-antimonide cathodes b) Development and testing of a diamond amplifier for photocathodes c) Tests of both cathodes in superconducting RF photoguns and copper RF photoguns

  18. Resistive Wall Heating of the Undulator in High Repetition Rate

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, J; Corlett, J; Emma, P; Wu, J

    2012-05-20

    In next generation high repetition rate FELs, beam energy loss due to resistive wall wakefields will produce significant amount of heat. The heat load for a superconducting undulator (operating at low temperature), must be removed and will be expensive to remove. In this paper, we study this effect in an undulator proposed for a Next Generation Light Source (NGLS) at LBNL. We benchmark our calculations with measurements at the LCLS and carry out detailed parameter studies using beam from a start-to-end simulation. Our preliminarym results suggest that the heat load in the undulator is about 2 W/m or lower with an aperture size of 6 mm for nominal NGLS preliminary design parameters.

  19. A high repetition rate XUV seeding source for FLASH2

    Energy Technology Data Exchange (ETDEWEB)

    Willner, Arik

    2012-05-15

    Improved performance of free-electron laser (FEL) light sources in terms of timing stability, pulse shape and spectral properties of the amplified FEL pulses is of interest in material science, the fields of ultrafast dynamics, biology, chemistry and even special branches in industry. A promising scheme for such an improvement is direct seeding with high harmonic generation (HHG) in a noble gas target. A free-electron laser seeded by an external extreme ultraviolet (XUV) source is planned for FLASH2 at DESY in Hamburg. The requirements for the XUV/soft X-ray source can be summarized as follows: A repetition rate of at least 100 kHz in a 10 Hz burst is needed at variable wavelengths from 10 to 40 nm and pulse energies of several nJ within a single laser harmonic. This application requires a laser amplifier system with exceptional parameters, mJ-level pulse energy, 10-15 fs pulse duration at 100 kHz (1 MHz) burst repetition rate. A new optical parametric chirped-pulse amplification (OPCPA) system is under development in order to meet these requirements, and very promising results have been achieved in the last three years. In parallel to this development, a new HHG concept is necessary to sustain high average power of the driving laser system and to generate harmonics with high conversion efficiencies. Currently, the highest conversion efficiency with HHG has been demonstrated using gas-filled capillary targets. For our application, only a free-jet target can be used for HHG, in order to overcome damage threshold limitations of HHG target optics at a high repetition rate. A novel dual-gas multijet gas target has been developed and first experiments show remarkable control of the degree of phase matching forming the basis for improved control of the harmonic photon flux and the XUV pulse characteristics. The basic idea behind the dual-gas concept is the insertion of matching zones in between multiple HHG sources. These matching sections are filled with hydrogen which

  20. High Repetition Rate Pulsed 2-Micron Laser Transmitter for Coherent CO2 DIAL Measurement

    Science.gov (United States)

    Singh, Uprendra N.; Bai, Yingxin; Yu, Jirong; Petros, Mulugeta; Petzar, Paul J.; Trieu, Bo C.; Lee, Hyung

    2009-01-01

    A high repetition rate, highly efficient, Q-switched 2-micron laser system as the transmitter of a coherent differential absorption lidar for CO2 measurement has been developed at NASA Langley Research Center. Such a laser transmitter is a master-slave laser system. The master laser operates in a single frequency, either on-line or off-line of a selected CO2 absorption line. The slave laser is a Q-switched ring-cavity Ho:YLF laser which is pumped by a Tm:fiber laser. The repetition rate can be adjusted from a few hundred Hz to 10 kHz. The injection seeding success rate is from 99.4% to 99.95%. For 1 kHz operation, the output pulse energy is 5.5mJ with the pulse length of approximately 50 ns. The optical-to-optical efficiency is 39% when the pump power is 14.5W. The measured standard deviation of the laser frequency jitter is about 3 MHz.

  1. Evaluation of the impact of viscosity, injection volume, and injection flow rate on subcutaneous injection tolerance

    Directory of Open Access Journals (Sweden)

    Berteau C

    2015-11-01

    Full Text Available Cecile Berteau,1 Orchidée Filipe-Santos,1 Tao Wang,2 Humberto E Rojas,2 Corinne Granger,1 Florence Schwarzenbach1 1Becton-Dickinson Medical Pharmaceutical Systems, Le Pont de Claix, France; 2Eli Lilly and Company, Indianapolis, IN, USA Aim: The primary objective of this study was to evaluate the impact of fluid injection viscosity in combination with different injection volumes and flow rates on subcutaneous (SC injection pain tolerance. Methods: The study was a single-center, comparative, randomized, crossover, Phase I study in 24 healthy adults. Each participant received six injections in the abdomen area of either a 2 or 3 mL placebo solution, with three different fluid viscosities (1, 8–10, and 15–20 cP combined with two different injection flow rates (0.02 and 0.3 mL/s. All injections were performed with 50 mL syringes and 27G, 6 mm needles. Perceived injection pain was assessed using a 100 mm visual analog scale (VAS (0 mm/no pain, 100 mm/extreme pain. The location and depth of the injected fluid was assessed through 2D ultrasound echography images. Results: Viscosity levels had significant impact on perceived injection pain (P=0.0003. Specifically, less pain was associated with high viscosity (VAS =12.6 mm than medium (VAS =16.6 mm or low (VAS =22.1 mm viscosities, with a significant difference between high and low viscosities (P=0.0002. Target injection volume of 2 or 3 mL was demonstrated to have no significant impact on perceived injection pain (P=0.89. Slow (0.02 mL/s or fast (0.30 mL/s injection rates also showed no significant impact on perceived pain during SC injection (P=0.79. In 92% of injections, the injected fluid was located exclusively in SC tissue whereas the remaining injected fluids were found located in SC and/or intradermal layers. Conclusion: The results of this study suggest that solutions of up to 3 mL and up to 15–20 cP injected into the abdomen within 10 seconds are well tolerated without pain. High

  2. Investigation of bunch repetition rate deviations in FIR FEL driven by a magnetron-based microtron

    CERN Document Server

    Kazakevitch, Grigori M; Lee Byung Cheol; Lee, J

    2002-01-01

    The stability of the bunch repetition rate in a FIR FEL driven by a 2.8 GHz magnetron-based microtron was investigated using a heterodyne method with a low Q-factor straight-flight measuring cavity. The measuring cavity is located in the straight section of the FIR FEL injection beam line and is excited by the passage of electron bunches. The RF signal from the measuring cavity coupling loop was mixed with a precise heterodyne signal with a frequency difference of several MHz. The beat frequency was analyzed to obtain the temporal distribution of the bunch repetition rate deviation during the macro pulse of the electron beam. The time resolution and the accuracy of measurements are approximately 100 ns and a few kHz, respectively. Based on this data, we could determine the level and shape of the magnetron current and the initial frequency shift between magnetron and accelerating cavity for the FEL operation in the wavelength range 100-300 microns.

  3. Repetition rate continuously tunable 10-GHz picosecond mode-locked fiber ring laser

    Institute of Scientific and Technical Information of China (English)

    Fang Wan; Ziyu Wang

    2006-01-01

    A couple of simple-structure phase modulators were used in active mode-locked fiber laser to implement repetition rate continuous tuning. The laser produces pulse as short as 5.7 ps whose repetition rate tuning can cover the spacing of the adjoining order mode-locking frequencies.

  4. High-repetition-rate XeCl waveguide laser without gas flow

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, C.P.; Gordon C. III; Moutoulas, C.; Feldman, B.J.

    1987-03-01

    Operation of a microwave discharge XeCl laser at pulse-repetition rates extending to 8 kHz without flow of the laser gas is reported. Present limits on pulse-repetition rate appear to be imposed by thermally induced refractive-index gradients.

  5. Evaluation of the impact of viscosity, injection volume, and injection flow rate on subcutaneous injection tolerance.

    Science.gov (United States)

    Berteau, Cecile; Filipe-Santos, Orchidée; Wang, Tao; Rojas, Humberto E; Granger, Corinne; Schwarzenbach, Florence

    2015-01-01

    The primary objective of this study was to evaluate the impact of fluid injection viscosity in combination with different injection volumes and flow rates on subcutaneous (SC) injection pain tolerance. The study was a single-center, comparative, randomized, crossover, Phase I study in 24 healthy adults. Each participant received six injections in the abdomen area of either a 2 or 3 mL placebo solution, with three different fluid viscosities (1, 8-10, and 15-20 cP) combined with two different injection flow rates (0.02 and 0.3 mL/s). All injections were performed with 50 mL syringes and 27G, 6 mm needles. Perceived injection pain was assessed using a 100 mm visual analog scale (VAS) (0 mm/no pain, 100 mm/extreme pain). The location and depth of the injected fluid was assessed through 2D ultrasound echography images. Viscosity levels had significant impact on perceived injection pain (P=0.0003). Specifically, less pain was associated with high viscosity (VAS =12.6 mm) than medium (VAS =16.6 mm) or low (VAS =22.1 mm) viscosities, with a significant difference between high and low viscosities (P=0.0002). Target injection volume of 2 or 3 mL was demonstrated to have no significant impact on perceived injection pain (P=0.89). Slow (0.02 mL/s) or fast (0.30 mL/s) injection rates also showed no significant impact on perceived pain during SC injection (P=0.79). In 92% of injections, the injected fluid was located exclusively in SC tissue whereas the remaining injected fluids were found located in SC and/or intradermal layers. The results of this study suggest that solutions of up to 3 mL and up to 15-20 cP injected into the abdomen within 10 seconds are well tolerated without pain. High viscosity injections were shown to be the most tolerated, whereas injection volume and flow rates did not impact perceived pain.

  6. Safety and efficacy of low fluence, high repetition rate versus high fluence, low repetition rate 810-nm diode laser for axillary hair removal in Chinese women.

    Science.gov (United States)

    Li, Wenhai; Liu, Chengyi; Chen, Zhou; Cai, Lin; Zhou, Cheng; Xu, Qianxi; Li, Houmin; Zhang, Jianzhong

    2016-11-01

    High-fluence diode lasers with contact cooling have emerged as the gold standard to remove unwanted hair. Lowering the energy should result in less pain and could theoretically affect the efficacy of the therapy. To compare the safety and efficacy of a low fluence high repetition rate 810-nm diode laser to those of a high fluence, low repetition rate diode laser for permanent axillary hair removal in Chinese women. Ninety-two Chinese women received four axillae laser hair removal treatments at 4-week intervals using the low fluence, high repetition rate 810-nm diode laser in super hair removal (SHR) mode on one side and the high fluence, low repetition rate diode laser in hair removal (HR) mode on the other side. Hair counts were done at each follow-up visit and 6-month follow-up after the final laser treatment using a "Hi Quality Hair Analysis Program System"; the immediate pain score after each treatment session was recorded by a visual analog scale. The overall median reduction of hair was 90.2% with the 810-nm diode laser in SHR mode and 87% with the same laser in HR mode at 6-month follow-up. The median pain scores in SHR mode and in HR mode were 2.75 and 6.75, respectively. Low fluence, high repetition rate diode laser can efficiently remove unwanted hair but also significantly improve tolerability and reduce adverse events during the course of treatment.

  7. Femtosecond and picosecond laser drilling of metals at high repetition rates and average powers.

    Science.gov (United States)

    Ancona, A; Döring, S; Jauregui, C; Röser, F; Limpert, J; Nolte, S; Tünnermann, A

    2009-11-01

    The influence of pulse duration on the laser drilling of metals at repetition rates of up to 1 MHz and average powers of up to 70 W has been experimentally investigated using an ytterbium-doped-fiber chirped-pulse amplification system with pulses from 800 fs to 19 ps. At a few hundred kilohertz particle shielding causes an increase in the number of pulses for breakthrough, depending on the pulse energy and duration. At higher repetition rates, the heat accumulation effect overbalances particle shielding, but significant melt ejection affects the hole quality. Using femtosecond pulses, heat accumulation starts at higher repetition rates, and the ablation efficiency is higher compared with picosecond pulses.

  8. Pulsed pumped Yb-doped fiber amplifier at low repetition rate

    Institute of Scientific and Technical Information of China (English)

    Changgeng Ye; Ping Yan; Mali Gong; Ming Lei

    2005-01-01

    A pulsed pumped Yb-doped double-clad fiber (DCF) master-oscillator power amplifier (MOPA) at low repetition rate is reported. Seeded by a passive Q-switched Nd:YAG microchip laser, the fiber amplifier can generate 167-kW peak-power and 0.83-ns duration pulses at 200-Hz repetition rate. Because of the pulsed pump approach, the amplified spontaneous emission (ASE) and the spurious lasing between pulses are well avoided, and the repetition rate can be set freely from single-shot to 1 kHz. Peak power scaling limitations that arise from the fiber facet damage are discussed.

  9. Generation of low jitter and discrete tunable dual-wavelength optical pulses at arbitrary repetition rates

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ming-jiang; WANG Yun-cai

    2006-01-01

    A novel and simple method to generate low timing jitter and discrete tunable dual-wavelength optical pulses at arbitrary repetition rates is demonstrated in this paper.Two multiple quantum wells distributed feedback laser diodes,were used as the external seeding sources to inject the external photons into a gain-switched Fabry-Perot laser diode.The output wavelengths can be tuned discretely to coincide with any two lasing modes in the gain spectra range of the Fabry-Perot Laser diode,and the output side mode suppression ratio was better than 25 dB.Moreover,the timing jitter of optical pulses was reduced from 1.89 ps to 0.83 ps.It was empirically found that the lowest timing jitter operation occurred when the injected light wavelength is 0.2-0.3 nm shorter than the locked mode of the Fabry-Perot laser diode.To our knowledge,this is the first report of using two DFB laser diodes as a seeding source to reduce pulses jitter and select lasing dual-wavelength simultaneously.

  10. Hydrodynamic size distribution of gold nanoparticles controlled by repetition rate during pulsed laser ablation in water

    Science.gov (United States)

    Menéndez-Manjón, Ana; Barcikowski, Stephan

    2011-02-01

    Most investigations on the laser generation and fragmentation of nanoparticles focus on Feret particle size, although the hydrodynamic size of nanoparticles is of great importance, for example in biotechnology for diffusion in living cells, or in engineering, for a tuned rheology of suspensions. In this sense, the formation and fragmentation of gold colloidal nanoparticles using femtosecond laser ablation at variable pulse repetition rates (100-5000 Hz) in deionized water were investigated through their plasmon resonance and hydrodynamic diameter, measured by Dynamic Light Scattering. The increment of the repetition rate does not influence the ablation efficiency, but produces a decrease of the hydrodynamic diameter and blue-shift of the plasmon resonance of the generated gold nanoparticles. Fragmentation, induced by inter-pulse irradiation of the colloids was measured online, showing to be more effective low repetition rates. The pulse repetition rate is shown to be an appropriate laser parameter for hydrodynamic size control of nanoparticles without further influence on the production efficiency.

  11. High Energy Single Frequency Fiber Laser at Low Repetition Rate Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR phase II project proposes a single frequency high energy fiber laser system operating at low repetition rate of 10 Hz to 1 kHz for coherent Lidar systems...

  12. Repetition rate tunable ultra-short optical pulse generation based on electrical pattern generator

    Institute of Scientific and Technical Information of China (English)

    Xin Fu; Hongming Zhang; Meng Yan; Minyu Yao

    2009-01-01

    @@ An actively mode-locked laser with tunable repetition rate is proposed and experimentally demonstrated based on a programmable electrical pattern generator.By changing the repetition rate of the electrical patterns applied on the in-cavity modulator, the repetition rate of the output optical pulse sequences changes accordingly while the pulse width of the optical pulse train remains almost constant.In other words, the output ultra-short pulse train has a tunable duty cycle.In a proof-of-principle experiment, optical pulses with repetition rates of 10, 5, 2.5 and 1.25 GHz are obtained by adjusting the electrical pattern applied on the in-cavity modulator while their pulse widths remain almost unchanged.

  13. Femtosecond Ti:sapphire cryogenic amplifier with high gain and MHz repetition rate.

    Science.gov (United States)

    Dantan, Aurélien; Laurat, Julien; Ourjoumtsev, Alexei; Tualle-Brouri, Rosa; Grangier, Philippe

    2007-07-09

    We demonstrate high gain amplification of 160-femtosecond pulses in a compact double-pass cryogenic Ti:sapphire amplifier. The setup involves a negative GVD mirrors recompression stage, and operates with a repetition rate between 0.2 and 4 MHz with a continuous pump laser. Amplification factors as high as 17 and 320 nJ Fourier-limited pulses are obtained at a 800 kHz repetition rate.

  14. High repetition rate femtosecond dye amplifier using a laser diode pumped neodymium:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Zysset, B.; LaGasse, M.J.; Fujimoto, J.G.; Kafka, J.D.

    1989-02-06

    A high repetition rate femtosecond dye amplifier is demonstrated using a laser diode pumped Q-switched Nd:YAG laser. Amplification of wavelength tunable 300 fs pulses from a synchronously mode-locked rhodamine dye laser is achieved with a saturated gain of 70 and a small gain of 200 at a repetition rate of 800 Hz. Maximum pulse energies of 40 nJ are obtained, and pulse compression to as short as 30 fs is demonstrated.

  15. High repetition rate femtosecond dye amplifier using a laser diode pumped neodymium:YAG laser

    Science.gov (United States)

    Zysset, B.; LaGasse, M. J.; Fujimoto, J. G.; Kafka, J. D.

    1989-02-01

    A high repetition rate femtosecond dye amplifier is demonstrated using a laser diode pumped Q-switched Nd:YAG laser. Amplification of wavelength tunable 300 fs pulses from a synchronously mode-locked rhodamine dye laser is achieved with a saturated gain of 70 and a small gain of 200 at a repetition rate of 800 Hz. Maximum pulse energies of 40 nJ are obtained, and pulse compression to as short as 30 fs is demonstrated.

  16. Coupling coefficient for TEA CO2 laser propulsion with variable pulse repetition rate

    Institute of Scientific and Technical Information of China (English)

    Yijun Zheng; Rongqing Tan; Donglei Wang; Guang Zheng; Changjun Ke; Kuohai Zhang; Chongyi Wan; Jin Wu

    2006-01-01

    @@ Because pulse repetition rate affected directly the momentum coupling coefficient of transversely excited atmospheric (TEA) CO2 laser propulsion, a double pulse trigger, controlling high voltage switch of laser excitation circuit, was designed. The pulse interval ranged between 5 and 100 ms. The momentum coupling coefficient for air-breathing mode laser propulsion was studied experimentally. It was found that the momentum coupling coefficient decreased with the pulse repetition rate increasing.

  17. Switchable repetition rate bound solitons passively mode-locked fiber laser

    Science.gov (United States)

    Wang, Xuqin; Yao, Yong

    2016-11-01

    We present a kind of a switchable repetition rate mode-locked of bound-state solitons in a fiber laser based on Bi2Se3 saturable absorber (SA). In the fiber laser, two forms of the bound-state optical spectrum with central wavelength of 1532 nm are observed. The fiber laser is operate at the abnormal group velocity dispersion and the bound state pulses are equally distributed to the temporal domain. The fundamental cavity repetition-rate is 1.11 MHz with a pulse duration of 2.27 ps. The output average power and the pulse peak energy are 1.53 mW and 607 W respectively, which the pump power is 267 mW. The different repetition-rates are also achieved by changing the pump power or adjusting the angle of polarization controller. In the experiment, the repetition-rate is switched from 1.11 MHz to 41.32 MHz (37th-order, the highest repetition-rate).

  18. Design study of a low-emittance high-repetition rate thermionic rf gun

    Science.gov (United States)

    Opanasenko, A.; Mytrochenko, V.; Zhaunerchyk, V.; Goryashko, V. A.

    2017-05-01

    We propose a novel gridless continuous-wave radiofrequency (rf) thermionic gun capable of generating nC ns electron bunches with a rms normalized slice emittance close to the thermal level of 0.3 mm mrad. In order to gate the electron emission, an externally heated thermionic cathode is installed into a stripline-loop conductor. Two high-voltage pulses propagating towards each other in the stripline-loop overlap in the cathode region and create a quasielectrostatic field gating the electron emission. The repetition rate of pulses is variable and can reach up to one MHz with modern solid-state pulsers. The stripline attached to a rf gun cavity wall has with the wall a common aperture that allows the electrons to be injected into the rf cavity for further acceleration. Thanks to this innovative gridless design, simulations suggest that the bunch emittance is approximately at the thermal level after the bunch injection into the cavity provided that the geometry of the cathode and aperture are properly designed. Specifically, a concave cathode is adopted to imprint an Ƨ-shaped distribution onto the beam transverse phase-space to compensate for an S-shaped beam distribution created by the spherical aberration of the aperture-cavity region. In order to compensate for the energy spread caused by rf fields of the rf gun cavity, a 3rd harmonic cavity is used. A detailed study of the electrodynamics of the stripline and rf gun cavity as well as the beam optics and bunch dynamics are presented.

  19. Multi-Rate Fractional-Order Repetitive Control of Shunt Active Power Filter

    DEFF Research Database (Denmark)

    Xie, Chuan; Zhao, Xin; Savaghebi, Mehdi

    2017-01-01

    This paper presents a multi-rate fractional-order repetitive control (MRFORC) scheme for three-phase shunt active power filter (APF). The proposed APF control scheme includes an inner proportional-integral (PI) control loop with a sampling rate identical to switching frequency and an external plug-in...

  20. Near- infrared, mode-locked waveguide lasers with multi-GHz repetition rates

    Science.gov (United States)

    Choudhary, A.; Lagatsky, A. A.; Zhang, Z. Y.; Zhou, K. J.; Wang, Q.; Hogg, R. A.; Pradeesh, K.; Rafailov, E. U.; Resan, B.; Oehler, A. E. H.; Weingarten, K. J.; Sibbett, W.; Brown, C. T. A.; Shepherd, D. P.

    2014-02-01

    In this work, we discuss mode-locking results obtained with low-loss, ion-exchanged waveguide lasers. With Yb3+-doped phosphate glass waveguide lasers, a repetition rate of up to 15.2 GHz was achieved at a wavelength of 1047 nm with an average power of 27 mW and pulse duration of 811 fs. The gap between the waveguide and the SESAM introduced negative group velocity dispersion via the Gires Tournois Interferometer (GTI) effect which allowed the soliton mode-locking of the device. A novel quantum dot SESAM was used to mode-lock Er3+, Yb3+-doped phosphate glass waveguide lasers around 1500 nm. Picosecond pulses were achieved at a maximum repetition rate of 6.8 GHz and an average output power of 30 mW. The repetition rate was tuned by more than 1 MHz by varying the pump power.

  1. Design of a low emittance and high repetition rate S-band photoinjector

    Science.gov (United States)

    Han, Jang-Hui

    2014-09-01

    As an electron beam injector of X-ray free-electron lasers (FELs), photoinjectors have been developed for the past few decades. Such an injector starting with a photocathode RF gun provides high brightness beams and therefore it is being adopted as an injector of X-ray FELs. In this paper we show how to improve photoinjector performance in terms of emittance and repetition rates by means of injector components optimization, especially with the gun. Transverse emittance at the end of an injector is reduced by optimizing the gun design, gun solenoid position, and accelerating section position. The repetition rate of an injector mainly depends on the gun. It is discussed that a repetition rate of 1 kHz at a normal-conducting S-band photoinjector is feasible by adopting a coaxial RF coupler and improving cooling-water channels surrounding the gun.

  2. High repetition rate passively Q-switched fiber and microchip lasers for optical resolution photoacoustic imaging

    Science.gov (United States)

    Shi, Wei; Utkin, Ilya; Ranasinghesagara, Janaka; Pan, Lei; Godwal, Yogesh; Kerr, Shaun; Zemp, Roger J.; Fedosejevs, Robert

    2010-02-01

    Optical-resolution photoacoustic microscopy is a novel imaging technology for visualizing optically-absorbing superficial structures in vivo with lateral spatial resolution determined by optical focusing rather than acoustic detection. Since scanning of the illumination spot is required, the imaging speed is limited by the scanning speed and the laser pulse repetition rate. Unfortunately, lasers with high-repetition rate and suitable pulse durations and energies are difficult to find. We are developing compact laser sources for this application. Passively Q-switched fiber and microchip lasers with pulse repetition rates up to 300 kHz are demonstrated. Using a diode-pumped microchip laser fiber-coupled to a large mode-area Yb-doped fiber amplifier we obtained 60μJ 1-ns pulses at the frequency-doubled 532-nm wavelength. The pulse-repetition rate was determined by the power of the microchip laser pump source at 808nm and may exceed 10 kHz. Additionally, a passively Q-switched fiber laser utilizing a Yb-doped double-cladding fiber and an external saturable absorber has shown to produce 250ns pulses at repetition rates of 100-300 KHz. A photoacoustic probe enabling flexible scanning of the focused output of these lasers consisted of a 45-degree glass prism in an optical index-matching fluid. Photoacoustic signals exiting the sample are deflected by the prism to an ultrasound transducer. Phantom studies with a 7.5-micron carbon fiber demonstrate the ability to image with optical rather than acoustic resolution. We believe that the high pulse-repetition rates and the potentially compact and fiber-coupled nature of these lasers will prove important for clinical imaging applications where realtime imaging performance is essential.

  3. A contactless microwave-based diagnostic tool for high repetition rate laser systems

    CERN Document Server

    Braggio, C

    2014-01-01

    We report on a novel electro-optic device for the diagnostics of high repetition rate laser systems. It is composed of a microwave receiver and of a second order nonlinear crystal, whose irradiation with a train of short laser pulses produces a time-dependent polarization in the crystal itself as a consequence of optical rectification. This process gives rise to the emission of microwave radiation that is detected by a receiver and is analyzed to infer the repetition rate and intensity of the pulses. We believe that this new method may overcome some of the limitations of photodetection techniques.

  4. High power, high repetition rate, few picosecond Nd:LuVO₄ oscillator with cavity dumping.

    Science.gov (United States)

    Gao, Peng; Guo, Jie; Li, Jinfeng; Lin, Hua; Yu, Haohai; Zhang, Huaijin; Liang, Xiaoyan

    2015-12-28

    We investigate the potential use of Nd:LuVO4 in high average power, high repetition rate ultrafast lasers. Maximum mode-locked average power of 28 W is obtained at the repetition rate of 58 MHz. The shortest pulse duration is achieved at 4 ps without dispersion compensation. With a cavity dumping technique, the pulse energy is scaling up to 40.7 μJ at 300 kHz and 14.3 μJ at 1.5 MHz.

  5. Low-loss waveguides fabricated in BK7 glass by high repetition rate femtosecond fiber laser.

    Science.gov (United States)

    Eaton, Shane M; Ng, Mi Li; Bonse, Jörn; Mermillod-Blondin, Alexandre; Zhang, Haibin; Rosenfeld, Arkadi; Herman, Peter R

    2008-04-20

    For the first time femtosecond-laser writing has inscribed low-loss optical waveguides in Schott BK7 glass, a commercially important type of borosilicate widely used in optical applications. The use of a variable repetition rate laser enabled the identification of a narrow processing window at 1 MHz repetition rate with optimal waveguides exhibiting propagation losses of 0.3 dB/cm and efficient mode matching to standard optical fibers at a 1550 nm wavelength. The waveguides were characterized by complementary phase contrast and optical transmission microscopy, identifying a micrometer-sized guiding region within a larger complex structure of both positive and negative refractive index variations.

  6. High-q microring resonator with narrow free spectral range for pulse repetition rate multiplication

    DEFF Research Database (Denmark)

    Pu, Minhao; Ji, Hua; Frandsen, Lars Hagedorn

    2009-01-01

    We demonstrate a silicon-on-insulator microring resonator with a free-spectral-range of 0.32 nm, an extinction ratio of 27 dB, and a quality factor of ~140900 at 1550 nm that is used for pulse repetition-rate multiplication from 10 to 40 GHz.......We demonstrate a silicon-on-insulator microring resonator with a free-spectral-range of 0.32 nm, an extinction ratio of 27 dB, and a quality factor of ~140900 at 1550 nm that is used for pulse repetition-rate multiplication from 10 to 40 GHz....

  7. Programmable Control of the Pulse Repetition Rate in the Multiwave Strontium Vapor Laser System

    Directory of Open Access Journals (Sweden)

    Soldatov Anatoly

    2016-01-01

    Full Text Available The aim of the present work was the development of laser systems for ablation of biological tissues with a programmable control over the lasing pulse repetition rate in a wide range. A two-stage laser system consisting of a master oscillator and a power amplifier based on strontium vapor laser has been developed. The operation of the laser system in a single-pulse mode operation, multipulse mode operation, and with a pulse repetition rate up to 20 kHz has been technically implemented. The possibility of a bone tissue ablation with no visible thermal damage is shown.

  8. Injector Beam Dynamics for a High-Repetition Rate 4th-Generation Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Papadopoulos, C. F.; Corlett, J.; Emma, P.; Filippetto, D.; Penn, G.; Qiang, J.; Reinsch, M.; Sannibale, F.; Steier, C.; Venturini, M.; Wells, R.

    2013-05-20

    We report on the beam dynamics studies and optimization methods for a high repetition rate (1 MHz) photoinjector based on a VHF normal conducting electron source. The simultaneous goals of beamcompression and reservation of 6-dimensional beam brightness have to be achieved in the injector, in order to accommodate a linac driven FEL light source. For this, a parallel, multiobjective optimization algorithm is used. We discuss the relative merits of different injector design points, as well as the constraints imposed on the beam dynamics by technical considerations such as the high repetition rate.

  9. Frequency and amplitude characteristics of a high-repetition-rate hybrid TEA-CO/sub 2/ laser

    Energy Technology Data Exchange (ETDEWEB)

    Lachambre, J.L.; Lavigne, P.; Verreault, M.; Otis, G.

    1978-02-01

    The envelope and frequency characteristics of the output pulse of a high-repetition-rate hybrid TEA-CO/sub 2/ laser are presented. Both the intrapulse and interpulse laser frequency stability are experimentally determined at repetition rates up to 300 Hz. The recovery of the CW laser signal following the generation of the TEA laser pulse is analyzed theoretically and experimentally. Short term reproducibilities of + or - 2 MHz are observed at a pulse repetition rate of 300 Hz with initial chirp rates of about 1.5 MHz/microsec. Improvements and limits on power and repetition rate are discussed.

  10. Femtosecond Ti:sapphire cryogenic amplifier with high gain and MHz repetition rate

    DEFF Research Database (Denmark)

    Dantan, Aurelien Romain; Laurat, Julien; Ourjoumtsev, Alexei

    2007-01-01

    We demonstrate high gain amplification of 160-femtosecond pulses in a compact double-pass cryogenic Ti:sapphire amplifier. The setup involves a negative GVD mirrors recompression stage, and operates with a repetition rate between 0.2 and 4 MHz with a continuous pump laser. Amplification factors...

  11. Effect of the pulse repetition rate on fiber-assisted tissue ablation

    Science.gov (United States)

    Kang, Hyun Wook

    2016-07-01

    The effect of the pulse repetition rate on ablation performance was evaluated ex vivo at various fiber sweeping speeds for an effective 532-nm laser prostatectomy. Three pulse repetition rates (7.5, 15, and 30 kHz) at 100 W were delivered to bovine liver tissue at three sweeping speeds (2, 4, and 6 mm/s) to achieve bulky tissue removal. Ablation performance was quantitatively compared in terms of the ablation volume and the coagulation thickness. The lowest pulse repetition rate of 7.5 kHz attained the highest ablation volume (101.5 ± 12.0 mm3) and the thinnest coagulation (0.7 ± 0.1 mm) along with superficial carbonization. The highest pulse repetition rate of 30 kHz was associated with the least tissue removal (65.8 ± 5.0 mm3) and the deepest thermal denaturation (1.1 ± 0.2 mm). Quantitative evaluations of laser parameters can be instrumental in facilitating ablation efficiency and maintaining hemostatic coagulation during treatment of large-sized benign prostate hyperplasia.

  12. Multi-gigahertz repetition rate ultrafast waveguide lasers mode-locked with graphene saturable absorbers

    Science.gov (United States)

    Obraztsov, P. A.; Okhrimchuk, A. G.; Rybin, M. G.; Obraztsova, E. D.; Garnov, S. V.

    2016-08-01

    We report the development of an approach to build compact waveguide lasers that operate in the stable fundamental mode-locking regime with multigigahertz repetition rates. The approach is based on the use of depressed cladding multi- or single-mode waveguides fabricated directly in the active laser crystal using the femtosecond laser inscription method and a graphene saturable absorber. Using this approach we achieve the stable self-starting mode-locking operation of a diode-pumped waveguide Nd:YAG laser that delivers picosecond pulses at a repetition rate of up to 11.5 GHz with an average power of 12 mW at a central wavelength of 1064 nm. The saturable absorbers are formed through the chemical vapor deposition of single-layer graphene on the output coupler mirror or directly on the end facet of the laser crystal. The stable self-starting mode-locking operation is achieved by controlling the group delay dispersion in the laser cavity with an intracavity interferometer. The method developed for the creation of compact ultrashort pulse laser generators with gigahertz repetition rates can be extended further and applied for the development of compact high-repetition rate lasers that operate at a wide range of IR wavelengths.

  13. Operation and Thermal Modeling of the ISIS H– Source from 50 to 2 Hz Repetition Rates

    CERN Document Server

    Pereira, H; Lettry, J

    2013-01-01

    CERN’s Linac4 accelerator H− ion source, currently under construction, will operate at a 2 Hz repetition rate, with pulse length of 0.5 ms and a beam current of 80 mA. Its reliability must exceed 99 % with a mandatory 3 month uninterrupted operation period. A Penning ion source is successfully operated at ISIS; at 50 Hz repetition rate it reliably provides 55 mA H− pulses of 0.25 ms duration over 1 month. The discharge plasma ignition is very sensitive to the temperatures of the discharge region, especially of its cathode. The investigation by modeling and measurement of operation parameters suitable for arc ignition and H− production at 2 Hz is of paramount importance and must be understood prior to the implementation of discharge ion sources in the Linac4 accelerator. In its original configuration, the ISIS H− source delivers beam only if the repetition rate is above 12.5 Hz, this paper describes the implementation of a temperature control of the discharge region aiming at lower repetition rate op...

  14. DFB diode seeded low repetition rate fiber laser system operating in burst mode

    Science.gov (United States)

    Šajn, M.; Petelin, J.; Agrež, V.; Vidmar, M.; Petkovšek, R.

    2017-02-01

    A distributed feedback (DFB) diode, gain switched to produce pulses from 60 ps at high peak power of over 0.5 W, is used in burst mode to seed a fiber amplifier chain. High seed power, spectral filtering between amplifier stages and pulsed pumping are used to mitigate amplified spontaneous emission (ASE). The effect of pulse pumping synchronized with the seed on the ASE is explored for the power amplifier at low repetition. Different input and output energies at different burst repetition rates are examined and up to 85% reduction in ASE is achieved compared to continuous pumping. Finally, a numerical model is used to predict further reduction of ASE.

  15. Passively Mode-Locked Fiber Laser with a Sub-Megahertz Repetition Rate

    Institute of Scientific and Technical Information of China (English)

    CHEN Jiong; JIA Dong-Fang; WU Yong-Chao; WANG Chang-Le; WANG Zhao-Ying; YANG Tian-Xin

    2011-01-01

    We demonstrate an ultra-long cavity by which an all-fiber erbium-doped fiber laser is passively mode-locked by nonlinear polarization rotation.The length of the resonant cavity amounts to 466m,which can be achieved by incorporating a 420m highly nonlinear fiber.The laser generates stable mode-locked pulses with a 444 kHz fundamental repetition rate.A near transform-limited subpicosecond pulse is obtained without any dispersion compensation.The maximum average power of the output pulses is 5.16 mW,which corresponds to a per-pulse energy of 11.62nJ.A low-repetition-rate optical pulse train is required for many applications such as micromachining,biomedical diagnostics and lidar systems.[1-3] However,the repetition rate of conventional fiber lasers is normally tens of MHz.Pulse pickers such as Pockels cells or acousto-optic modulators are always used to lower the repetition rate,however,reduction in this way introduces significant energy losses,impairs the signal-to-noise ratio (SNR) and increases complexity.Because the pulse repetition rate of a modelocked laser is inversely proportional to its resonator length,longer cavities lead to lower pulse repetition rates and,consequently,to higher pulse energy at the same average power of radiation.%We demonstrate an ultra-long cavity by which an all-fiber erbium-doped fiber laser is passively mode-locked by nonlinear polarization rotation. The length of the resonant cavity amounts to 466 m, which can be achieved by incorporating a 420 m highly nonlinear fiber. The laser generates stable mode-locked pulses with a 444 kHz fundamental repetition rate. A near transform-limited subpicosecond pulse is obtained without any dispersion compensation. The maximum average power of the output pulses is 5.16mW, which corresponds to a per-pulse energy of 11.62 nJ.

  16. Effect of Repetition Rate on Femtosecond Laser-Induced Homogenous Microstructures

    Directory of Open Access Journals (Sweden)

    Sanchari Biswas

    2016-12-01

    Full Text Available We report on the effect of repetition rate on the formation and surface texture of the laser induced homogenous microstructures. Different microstructures were micromachined on copper (Cu and titanium (Ti using femtosecond pulses at 1 and 10 kHz. We studied the effect of the repetition rate on structure formation by comparing the threshold accumulated pulse ( F Σ p u l s e values and the effect on the surface texture through lacunarity analysis. Machining both metals at low F Σ p u l s e resulted in microstructures with higher lacunarity at 10 kHz compared to 1 kHz. On increasing F Σ p u l s e , the microstructures showed higher lacunarity at 1 kHz. The effect of the repetition rate on the threshold F Σ p u l s e values were, however, considerably different on the two metals. With an increase in repetition rate, we observed a decrease in the threshold F Σ p u l s e on Cu, while on Ti we observed an increase. These differences were successfully allied to the respective material characteristics and the resulting melt dynamics. While machining Ti at 10 kHz, the melt layer induced by one laser pulse persists until the next pulse arrives, acting as a dielectric for the subsequent pulse, thereby increasing F Σ p u l s e . However, on Cu, the melt layer quickly resolidifies and no such dielectric like phase is observed. Our study contributes to the current knowledge on the effect of the repetition rate as an irradiation parameter.

  17. Effect of Repetition Rate on Femtosecond Laser-Induced Homogenous Microstructures.

    Science.gov (United States)

    Biswas, Sanchari; Karthikeyan, Adya; Kietzig, Anne-Marie

    2016-12-19

    We report on the effect of repetition rate on the formation and surface texture of the laser induced homogenous microstructures. Different microstructures were micromachined on copper (Cu) and titanium (Ti) using femtosecond pulses at 1 and 10 kHz. We studied the effect of the repetition rate on structure formation by comparing the threshold accumulated pulse ( F Σ p u l s e ) values and the effect on the surface texture through lacunarity analysis. Machining both metals at low F Σ p u l s e resulted in microstructures with higher lacunarity at 10 kHz compared to 1 kHz. On increasing F Σ p u l s e , the microstructures showed higher lacunarity at 1 kHz. The effect of the repetition rate on the threshold F Σ p u l s e values were, however, considerably different on the two metals. With an increase in repetition rate, we observed a decrease in the threshold F Σ p u l s e on Cu, while on Ti we observed an increase. These differences were successfully allied to the respective material characteristics and the resulting melt dynamics. While machining Ti at 10 kHz, the melt layer induced by one laser pulse persists until the next pulse arrives, acting as a dielectric for the subsequent pulse, thereby increasing F Σ p u l s e . However, on Cu, the melt layer quickly resolidifies and no such dielectric like phase is observed. Our study contributes to the current knowledge on the effect of the repetition rate as an irradiation parameter.

  18. Longitudinally excited CO2 laser with short laser pulse operating at high repetition rate

    Science.gov (United States)

    Li, Jianhui; Uno, Kazuyuki; Akitsu, Tetsuya; Jitsuno, Takahisa

    2016-11-01

    A short-pulse longitudinally excited CO2 laser operating at a high repetition rate was developed. The discharge tube was made of a 45 cm-long or 60 cm-long dielectric tube with an inner diameter of 16 mm and two metallic electrodes at the ends of the tube. The optical cavity was formed by a ZnSe output coupler with a reflectivity of 85% and a high-reflection mirror. Mixed gas (CO2:N2:He = 1:1:2) was flowed into the discharge tube. A high voltage of about 33 kV with a rise time of about 200 ns was applied to the discharge tube. At a repetition rate of 300 Hz and a gas pressure of 3.4 kPa, the 45 cm-long discharge tube produced a short laser pulse with a laser pulse energy of 17.5 mJ, a spike pulse energy of 0.2 mJ, a spike width of 153 ns, and a pulse tail length of 90 μs. The output power was 5.3 W. The laser pulse waveform did not depend on the repetition rate, but the laser beam profile did. At a low repetition rate of less than 50 Hz, the laser beam had a doughnut-like shape. However, at a high repetition rate of more than 150 Hz, the discharge concentrated at the center of the discharge tube, and the intensity at the center of the laser beam was higher. The laser beam profile depended on the distribution of the discharge. An output power of 7.0 W was achieved by using the 60 cm-long tube.

  19. Effects of picosecond laser repetition rate on ablation of Cr12MoV cold work mold steel

    Science.gov (United States)

    Wu, Baoye; Deng, Leimin; Liu, Peng; Zhang, Fei; Duan, Jun; Zeng, Xiaoyan

    2017-07-01

    In this paper, the effects of pulse repetition rate on ablation efficiency and quality of Cr12MoV cold work mold steel have been studied using a picosecond (ps) pulse Nd:YVO4 laser system at λ= 1064 nm. The experimental results of area ablation on target surface reveal that laser repetition rate plays a significant role in controlling ablation efficiency and quality. Increasing the laser repetition rate, while keeping a constant mean power improves the ablation efficiency and quality. For each laser mean power, there is an optimal repetition rate to achieve a higher laser ablation efficiency with low surface roughness. A high ablation efficiency of 42.29, 44.11 and 47.52 μm3/mJ, with surface roughness of 0.476, 0.463 and 0.706 μm could be achieved at laser repetition rate of 10 MHz, for laser mean power of 15, 17 and 19 W, respectively. Scanning electron microcopy images revels that the surface morphology evolves from rough with numerous craters, to flat without pores when we increased the laser repetition rate. The effects of laser repetition rate on the heat accumulation, plasma shield and ablation threshold were analyzed by numerical simulation, spectral analysis and multi-laser shot, respectively. The synergetic effects of laser repetition rate on laser ablation rate and machining quality were analyzed and discussed systemically in this paper.

  20. KAPTURE-2. A picosecond sampling system for individual THz pulses with high repetition rate

    Science.gov (United States)

    Müller, A.-S.

    2017-01-01

    This paper presents a novel data acquisition system for continuous sampling of ultra-short pulses generated by terahertz (THz) detectors. Karlsruhe Pulse Taking Ultra-fast Readout Electronics (KAPTURE) is able to digitize pulse shapes with a sampling time down to 3 ps and pulse repetition rates up to 500 MHz. KAPTURE has been integrated as a permanent diagnostic device at ANKA and is used for investigating the emitted coherent synchrotron radiation in the THz range. A second version of KAPTURE has been developed to improve the performance and flexibility. The new version offers a better sampling accuracy for a pulse repetition rate up to 2 GHz. The higher data rate produced by the sampling system is processed in real-time by a heterogeneous FPGA and GPU architecture operating up to 6.5 GB/s continuously. Results in accelerator physics will be reported and the new design of KAPTURE be discussed.

  1. The influence of the repetition rate on the nanosecond pulsed pin-to-pin microdischarges

    Science.gov (United States)

    Huang, Bang-Dou; Takashima, Keisuke; Zhu, Xi-Ming; Pu, Yi-Kang

    2014-10-01

    The effect of repetition rate on a nanosecond atmospheric pressure discharge is investigated. The discharge is generated between two pins in a mixture of Ne and Ar. The voltage, current, power waveforms and the temporally and spatially resolved electron density and an ‘effective’ electron temperature are measured, with a pulse interval between 1.5 and 200 µs. It is found that not only does the repetition rate have a strong influence on the breakdown voltage and the peak discharge power, but it can also affect the rise rate of the volume averaged electron density and its peak value. Temporally and spatially resolved measurement of the electron density and the effective electron temperature show that the spatial distributions of both quantities are also influenced by the repetition rate. In the initial discharge period of all cases, the sharp rise of the electron density correlates with the drastic drop of the effective electron temperature. It is suggested that the residual charges have a strong impact on the axial distribution of the electric field and energetic electrons between the electrodes during the breakdown period, as illustrated by a simple sheath model.

  2. A simple sub-nanosecond ultraviolet light pulse generator with high repetition rate and peak power.

    Science.gov (United States)

    Binh, P H; Trong, V D; Renucci, P; Marie, X

    2013-08-01

    We present a simple ultraviolet sub-nanosecond pulse generator using commercial ultraviolet light-emitting diodes with peak emission wavelengths of 290 nm, 318 nm, 338 nm, and 405 nm. The generator is based on step recovery diode, short-circuited transmission line, and current-shaping circuit. The narrowest pulses achieved have 630 ps full width at half maximum at repetition rate of 80 MHz. Optical pulse power in the range of several hundreds of microwatts depends on the applied bias voltage. The bias voltage dependences of the output optical pulse width and peak power are analysed and discussed. Compared to commercial UV sub-nanosecond generators, the proposed generator can produce much higher pulse repetition rate and peak power.

  3. A High Power and High Repetition Rate Modelocked Ti-Sapphire Laser for Photoinjectors

    Energy Technology Data Exchange (ETDEWEB)

    J. Hansknecht; M. Poelker

    2001-07-01

    A high power cw mode-locked Ti-sapphire laser has been constructed to drive the Jefferson Lab polarized photoinjector and provide > 500 mW average power with 50 ps pulsewidths at 499 MHz or 1497 MHz pulse repetition rates. This laser allows efficient, high current synchronous photoinjection for extended periods of time before intrusive steps must be taken to restore the quantum efficiency of the strained layer GaAs photocathode. The use of this laser has greatly enhanced the maximum high polarization beam current capability and operating lifetime of the Jefferson Lab photoinjector compared with previous performance using diode laser systems. A novel modelocking technique provides a simple means to phase-lock the optical pulse train of the laser to the accelerator and allows for operation at higher pulse repetition rates to {approx} 3 GHz without modification of the laser cavity. The laser design and characteristics are described below.

  4. Group velocity locked vector dissipative solitons in a high repetition rate fiber laser

    CERN Document Server

    Luo, Yiyang; Li, Lei; Sun, Qizhen; Wu, Zhichao; Xu, Zhilin; Fu, Songnian; Zhao, Luming

    2016-01-01

    Vectorial nature of dissipative solitons (DSs) with high repetition rates is studied for the first time in a normal-dispersion fiber laser. Despite the fact that the formed DSs are strongly chirped and the repetition rate is greater than 100 MHz, polarization locked and polarization rotating group velocity locked vector DSs can be formed under 129.3 MHz fundamental mode-locking and 258.6 MHz harmonic mode-locking of the fiber laser, respectively. The two orthogonally polarized components of these vector DSs possess distinctly different central wavelengths and travel together at the same group velocity in the laser cavity, resulting in a gradual spectral edge and small steps on the optical spectra, which can be considered as an auxiliary indicator of the group velocity locked vector DSs.

  5. Spectral-temporal encoding and decoding of the femtosecond pulses sequences with a THz repetition rate

    Science.gov (United States)

    Tcypkin, A. N.; Putilin, S. E.

    2017-01-01

    Experimental and numerical modeling techniques demonstrated the possibilities of the spectral-time encoding and decoding for time division multiplexing sequence of femtosecond subpulses with a repetition rate of up to 6.4 THz. The sequence was formed as a result of the interference of two phase-modulated pulses. We report the limits of the application of the developed method of controlling formed sequence at the spectral-temporal coding.

  6. High repetition rate, compact micro-pulse all-solid-state laser

    Institute of Scientific and Technical Information of China (English)

    Yutong Feng; Junqing Meng; Weibiao Chen

    2007-01-01

    A high repetition rate, compact micro-pulse all-solid-state laser is designed. The diffusion bonded crystal of YAG, Nd:YAG, and Cr4+:YAG is taken as a monolithic cavity. The optimized initial transmission,output coupling, and pumping size of Cr4+:YAG are calculated. The experimental results show that the laser satisfies the requirement of a spaceborne laser range finder.

  7. Impact of visual repetition rate on intrinsic properties of low frequency fluctuations in the visual network.

    Directory of Open Access Journals (Sweden)

    Yi-Chia Li

    Full Text Available BACKGROUND: Visual processing network is one of the functional networks which have been reliably identified to consistently exist in human resting brains. In our work, we focused on this network and investigated the intrinsic properties of low frequency (0.01-0.08 Hz fluctuations (LFFs during changes of visual stimuli. There were two main questions to be discussed in this study: intrinsic properties of LFFs regarding (1 interactions between visual stimuli and resting-state; (2 impact of repetition rate of visual stimuli. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed scanning sessions that contained rest and visual stimuli in various repetition rates with a novel method. The method included three numerical approaches involving ICA (Independent Component Analyses, fALFF (fractional Amplitude of Low Frequency Fluctuation, and Coherence, to respectively investigate the modulations of visual network pattern, low frequency fluctuation power, and interregional functional connectivity during changes of visual stimuli. We discovered when resting-state was replaced by visual stimuli, more areas were involved in visual processing, and both stronger low frequency fluctuations and higher interregional functional connectivity occurred in visual network. With changes of visual repetition rate, the number of areas which were involved in visual processing, low frequency fluctuation power, and interregional functional connectivity in this network were also modulated. CONCLUSIONS/SIGNIFICANCE: To combine the results of prior literatures and our discoveries, intrinsic properties of LFFs in visual network are altered not only by modulations of endogenous factors (eye-open or eye-closed condition; alcohol administration and disordered behaviors (early blind, but also exogenous sensory stimuli (visual stimuli with various repetition rates. It demonstrates that the intrinsic properties of LFFs are valuable to represent physiological states of human brains.

  8. Generation of picosecond laser pulses at 1030 nm with gigahertz range continuously tunable repetition rate.

    Science.gov (United States)

    Aubourg, Adrien; Lhermite, Jérôme; Hocquet, Steve; Cormier, Eric; Santarelli, Giorgio

    2015-12-01

    We report on a watt range laser system generating picosecond pulses using electro-optical modulation of a 1030 nm single frequency low noise laser diode. Its repetition rate is continuously tunable between 11 and 18 GHz. Over this range, output spectra and pulse characteristics are measured and compared with a numerical simulation. Finally, amplitude and residual phase noise measurements of the source are also presented.

  9. Steady State Microbunching for High Brilliance and High Repetition Rate Storage Ring-Based Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Alex; Ratner, Daniel; /SLAC; Jiao, Yi; /Beijing, Inst. High Energy Phys.

    2012-09-06

    Electron-based light sources have proven to be effective sources of high brilliance, high frequency radiation. Such sources are typically either linac-Free Electron Laser (FEL) or storage ring types. The linac-FEL type has high brilliance (because the beam is microbunched) but low repetition rate. The storage ring type has high repetition rate (rapid beam circulation) but comparatively low brilliance or coherence. We propose to explore the feasibility of a microbunched beam in a storage ring that promises high repetition rate and high brilliance. The steady-state-micro-bunch (SSMB) beam in storage ring could provide CW sources for THz, EUV, or soft X-rays. Several SSMB mechanisms have been suggested recently, and in this report, we review a number of these SSMB concepts as promising directions for high brilliance, high repetition rate light sources of the future. The trick of SSMB lies in the RF system, together with the associated synchrotron beam dynamics, of the storage ring. Considering various different RF arrangements, there could be considered a number of scenarios of the SSMB. In this report, we arrange these scenarios more or less in order of the envisioned degree of technical challenge to the RF system, and not in the chronological order of their original references. Once the stored beam is steady-state microbunched in a storage ring, it passes through a radiator repeatedly every turn (or few turns). The radiator extracts a small fraction of the beam energy as coherent radiation with a wavelength corresponding to the microbunched period of the beam. In contrast to an FEL, this radiator is not needed to generate the microbunching (as required e.g. by SASE FELs or seeded FELs), so the radiator can be comparatively simple and short.

  10. Studies of a Linac Driver for a High Repetition Rate X-Ray FEL

    Energy Technology Data Exchange (ETDEWEB)

    Venturini, M.; Corlett, J.; Doolittle, L.; Filippetto, D.; Papadopoulos, C.; Penn, G.; Prosnitz, D.; Qiang, J.; Reinsch, M.; Ryne, R.; Sannibale, F.; Staples, J.; Wells, R.; Wurtele, J.; Zolotorev, M.; Zholents, A.

    2011-06-01

    We report on on-going studies of a superconducting CW linac driver intended to support a high repetition rate FEL operating in the soft x-rays spectrum. We present a pointdesign for a 1.8 GeV machine tuned for 300 pC bunches and delivering low-emittance, low-energy spread beams as needed for the SASE and seeded beamlines.

  11. Steady State Microbunching for High Brilliance and High Repetition Rate Storage Ring-Based Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Alex; Ratner, Daniel; /SLAC; Jiao, Yi; /Beijing, Inst. High Energy Phys.

    2012-09-06

    Electron-based light sources have proven to be effective sources of high brilliance, high frequency radiation. Such sources are typically either linac-Free Electron Laser (FEL) or storage ring types. The linac-FEL type has high brilliance (because the beam is microbunched) but low repetition rate. The storage ring type has high repetition rate (rapid beam circulation) but comparatively low brilliance or coherence. We propose to explore the feasibility of a microbunched beam in a storage ring that promises high repetition rate and high brilliance. The steady-state-micro-bunch (SSMB) beam in storage ring could provide CW sources for THz, EUV, or soft X-rays. Several SSMB mechanisms have been suggested recently, and in this report, we review a number of these SSMB concepts as promising directions for high brilliance, high repetition rate light sources of the future. The trick of SSMB lies in the RF system, together with the associated synchrotron beam dynamics, of the storage ring. Considering various different RF arrangements, there could be considered a number of scenarios of the SSMB. In this report, we arrange these scenarios more or less in order of the envisioned degree of technical challenge to the RF system, and not in the chronological order of their original references. Once the stored beam is steady-state microbunched in a storage ring, it passes through a radiator repeatedly every turn (or few turns). The radiator extracts a small fraction of the beam energy as coherent radiation with a wavelength corresponding to the microbunched period of the beam. In contrast to an FEL, this radiator is not needed to generate the microbunching (as required e.g. by SASE FELs or seeded FELs), so the radiator can be comparatively simple and short.

  12. Ultrafast, high repetition rate, ultraviolet, fiber based laser source: application towards Yb+ fast quantum-logic

    CERN Document Server

    Hussain, Mahmood Irtiza; Bentley, Christopher D B; Taylor, Richard L; Carvalho, Andre R R; Hope, Joseph J; Streed, Erik W; Lobino, Mirko; Kielpinski, David

    2016-01-01

    Trapped ions are one of the most promising approaches for the realization of a universal quantum computer. Faster quantum logic gates could dramatically improve the performance of trapped-ion quantum computers, and require the development of suitable high repetition rate pulsed lasers. Here we report on a robust frequency upconverted fiber laser based source, able to deliver 2.5 ps ultraviolet (UV) pulses at a stabilized repetition rate of 300.00000 MHz with an average power of 190 mW. The laser wavelength is resonant with the strong transition in Ytterbium (Yb+) at 369.53 nm and its repetition rate can be scaled up using high harmonic mode locking. We show that our source can produce arbitrary pulse patterns using a programmable pulse pattern generator and fast modulating components. Finally, simulations demonstrate that our laser is capable of performing resonant, temperature-insensitive, two-qubit quantum logic gates on trapped Yb$^+$ ions faster than the trap period and with fidelity above 99%.

  13. Compact X-ray Source using a High Repetition Rate Laser and Copper Linac

    CERN Document Server

    Graves, W S; Brown, P; Carbajo, S; Dolgashev, V; Hong, K -H; Ihloff, E; Khaykovich, B; Lin, H; Murari, K; Nanni, E A; Resta, G; Tantawi, S; Zapata, L E; Kärtner, F X; Moncton, D E

    2014-01-01

    A design for a compact x-ray light source (CXLS) with flux and brilliance orders of magnitude beyond existing laboratory scale sources is presented. The source is based on inverse Compton scattering of a high brightness electron bunch on a picosecond laser pulse. The accelerator is a novel high-efficiency standing-wave linac and RF photoinjector powered by a single ultrastable RF transmitter at x-band RF frequency. The high efficiency permits operation at repetition rates up to 1 kHz, which is further boosted to 100 kHz by operating with trains of 100 bunches of 100 pC charge, each separated by 5 ns. The 100 kHz repetition rate is orders of magnitude beyond existing high brightness copper linacs. The entire accelerator is approximately 1 meter long and produces hard x-rays tunable over a wide range of photon energies. The colliding laser is a Yb:YAG solid-state amplifier producing 1030 nm, 100 mJ pulses at the same 1 kHz repetition rate as the accelerator. The laser pulse is frequency-doubled and stored for m...

  14. Effects of shifts in the rate of repetitive stimulation on sustained attention

    Science.gov (United States)

    Krulewitz, J. E.; Warm, J. S.; Wohl, T. H.

    1975-01-01

    The effects of shifts in the rate of presentation of repetitive neutral events (background event rate) were studied in a visual vigilance task. Four groups of subjects experienced either a high (21 events/min) or a low (6 events/min) event rate for 20 min and then experienced either the same or the alternate event rate for an additional 40 min. The temporal occurrence of critical target signals was identical for all groups, irrespective of event rate. The density of critical signals was 12 signals/20 min. By the end of the session, shifts in event rate were associated with changes in performance which resembled contrast effects found in other experimental situations in which shift paradigms were used. Relative to constant event rate control conditions, a shift from a low to a high event rate depressed the probability of signal detections, while a shift in the opposite direction enhanced the probability of signal detections.

  15. Acousto-optic pulse picking scheme with carrier-frequency-to-pulse-repetition-rate synchronization.

    Science.gov (United States)

    de Vries, Oliver; Saule, Tobias; Plötner, Marco; Lücking, Fabian; Eidam, Tino; Hoffmann, Armin; Klenke, Arno; Hädrich, Steffen; Limpert, Jens; Holzberger, Simon; Schreiber, Thomas; Eberhardt, Ramona; Pupeza, Ioachim; Tünnermann, Andreas

    2015-07-27

    We introduce and experimentally validate a pulse picking technique based on a travelling-wave-type acousto-optic modulator (AOM) having the AOM carrier frequency synchronized to the repetition rate of the original pulse train. As a consequence, the phase noise characteristic of the original pulse train is largely preserved, rendering this technique suitable for applications requiring carrier-envelope phase stabilization. In a proof-of-principle experiment, the 1030-nm spectral part of an 74-MHz, carrier-envelope phase stable Ti:sapphire oscillator is amplified and reduced in pulse repetition frequency by a factor of two, maintaining an unprecedentedly low carrier-envelope phase noise spectral density of below 68 mrad. Furthermore, a comparative analysis reveals that the pulse-picking-induced additional amplitude noise is minimized, when the AOM is operated under synchronicity. The proposed scheme is particularly suitable when the down-picked repetition rate is still in the multi-MHz-range, where Pockels cells cannot be applied due to piezoelectric ringing.

  16. Optimization of graffiti removal on natural stone by means of high repetition rate UV laser

    Science.gov (United States)

    Fiorucci, M. P.; López, A. J.; Ramil, A.; Pozo, S.; Rivas, T.

    2013-08-01

    The use of laser for graffiti removal is a promising alternative to conventional cleaning methods, though irradiation parameters must be carefully selected in order to achieve the effective cleaning without damaging the substrate, especially when referring to natural stone. From a practical point of view, once a safe working window is selected, it is necessary to determine the irradiation conditions to remove large paint areas, with minimal time consumption. The aim of this paper is to present a systematic procedure to select the optimum parameters for graffiti removal by means of the 3rd harmonic of a high repetition rate nanosecond Nd:YVO4 laser. Ablation thresholds of four spray paint colors were determined and the effect of pulse repetition frequency, beam diameter and line scan separation was analyzed, obtaining a set of values which optimize the ablation process.

  17. Optimization of graffiti removal on natural stone by means of high repetition rate UV laser

    Energy Technology Data Exchange (ETDEWEB)

    Fiorucci, M.P., E-mail: m.p.fiorucci@udc.es [Centro de Investigacións Tecnolóxicas, Universidade da Coruña, 15403 Ferrol (Spain); Dpto. Enxeñaría dos Recursos Naturais e Medio Ambiente, E.T.S.E. Minas, Universidade de Vigo, 36200 Vigo (Spain); López, A.J., E-mail: ana.xesus.lopez@udc.es [Centro de Investigacións Tecnolóxicas, Universidade da Coruña, 15403 Ferrol (Spain); Ramil, A., E-mail: alberto.ramil@udc.es [Centro de Investigacións Tecnolóxicas, Universidade da Coruña, 15403 Ferrol (Spain); Pozo, S., E-mail: ipozo@uvigo.es [Dpto. Enxeñaría dos Recursos Naturais e Medio Ambiente, E.T.S.E. Minas, Universidade de Vigo, 36200 Vigo (Spain); Rivas, T., E-mail: trivas@uvigo.es [Dpto. Enxeñaría dos Recursos Naturais e Medio Ambiente, E.T.S.E. Minas, Universidade de Vigo, 36200 Vigo (Spain)

    2013-08-01

    The use of laser for graffiti removal is a promising alternative to conventional cleaning methods, though irradiation parameters must be carefully selected in order to achieve the effective cleaning without damaging the substrate, especially when referring to natural stone. From a practical point of view, once a safe working window is selected, it is necessary to determine the irradiation conditions to remove large paint areas, with minimal time consumption. The aim of this paper is to present a systematic procedure to select the optimum parameters for graffiti removal by means of the 3rd harmonic of a high repetition rate nanosecond Nd:YVO{sub 4} laser. Ablation thresholds of four spray paint colors were determined and the effect of pulse repetition frequency, beam diameter and line scan separation was analyzed, obtaining a set of values which optimize the ablation process.

  18. 100 kV/2A three-phase constant-current repetitive-rate charging equipment

    CERN Document Server

    Tan Yu Gang; Chen Li Dong; Guo Zhi Gang; Zou Xiao Bing; Luo Min; Cao Shao Yun; Chang An Bi

    2002-01-01

    A 100 kV/2A three-phase constant-current repetitive-rate charging equipment was designed and constructed. A three-phase L-C converter is adopted as constant-current power source. Six Insulated Gate Bipolar Transistors (IGBTs) are connected in parallel to control the stop of charge. A Programmable Logical Controller (PLC) is the central element of the control unit. The equipment is used in the repetitive-rate discharge features test of the switch. It works stably under the conditions of 2A charging current, 10 Hz operating voltage, 100 kV repetitive rate and 1 mu F capacitor

  19. Ultraviolet excimer laser ablation: the effect of wavelength and repetition rate on in vivo guinea pig skin

    Energy Technology Data Exchange (ETDEWEB)

    Morelli, J.; Kibbi, A.G.; Farinelli, W.; Boll, J.; Tan, O.T.

    1987-06-01

    Multiple dermatologic conditions that are currently treated with traditional cold-knife surgery are amenable to laser therapy. The ideal surgical treatment would be precise and total removal of abnormal tissue with maximal sparing of remaining structures. The ultraviolet (UV) excimer laser is capable of such precise tissue removal due to the penetration depth of 193 nm and 248 nm irradiation of 1 micron per pulse. This type of ablative tissue removal requires a high repetition rate for efficient lesional destruction. Excimer laser radiation at 193 nm is capable of high repetition rates, which are necessary while 248 nm radiation causes increasing nonspecific thermal injury as the laser repetition rate is increased.

  20. Effect of Air Injection on Nucleation Rates

    DEFF Research Database (Denmark)

    Capellades Mendez, Gerard; Kiil, Søren; Dam-Johansen, Kim

    2017-01-01

    to study the effects on formation of the first crystal and subsequent turbidity buildup. To account for the typically large sample-to-sample variation, nucleation rates were evaluated for a large number of replicates using probability distributions of induction times. The slope and the intercept...... was reduced from 69 to 13 min, and the mean induction time decreased from 128 to 36 min. The effect on aqueous solutions of l-arginine was less apparent, with a detection delay reduction from 15 to 3 min, and no significant changes on the rate of primary nucleation. These results demonstrate the potential...

  1. Statistical analysis of laser driven protons using a high-repetition-rate tape drive target system

    Directory of Open Access Journals (Sweden)

    Muhammad Noaman-ul-Haq

    2017-04-01

    Full Text Available One of the challenges for laser-driven proton beams for many potential applications is their stability and reproducibility. We investigate the stability of the laser driven proton beams through statistical analysis of the data obtained by employing a high repetition rate tape driven target system. The characterization of the target system shows the positioning of the target within ∼15  μm in the focal plane of an off-axis parabola, with less than a micron variation in surface flatness. By employing this stable target system, we study the stability of the proton beams driven by ultrashort and intense laser pulses. Protons with maximum energies of ∼6±0.3  MeV were accelerated for a large number of laser shots taken at a rate of 0.2 Hz with a stability of less than 5% variations in cutoff energy. The development of high repetition rate target system may provide a platform to understand the dynamics of laser driven proton beams at the rate required for future applications.

  2. High energy high repetition-rate thin-disk amplifier for OPCPA pumping

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Michael

    2013-08-15

    The development of a pump laser system for a high power and high repetition rate optical parametric chirped-pulse amplification (OPCPA) is presented in this thesis. The OPCPA system requires pump pulse energies in the range of tens of millijoules at high repetition rates with sub-picosecond pulse durations. This can be achieved to some extend with Innoslab amplifier technology. However, scaling to higher pulse energies at high repetition rates may be problematic. With the thin-disk amplifier presented in this thesis, output energies of 140 mJ at 100 kHz repetition rate could be achieved in burst-mode operation, which is a world record for this type of laser amplifier. Due to its material and spectral properties, ytterbium doped YAG (Yb:YAG) is used as a gain medium for the high power amplifier stages. The low quantum defect and the comparatively large emission bandwidth makes this material the choice for high power operation and sub-picosecond compressed pulse durations. The output beam profile as well as the shape of the output bursts is ideal to pump an OPCPA system. An OPCPA output energy in the millijoule range with repetition rates of 100 kHz to 1 MHz is needed to generate seed pulses for the FEL and for the application as pump-probe laser at the FEL facility. Since the development of this laser system needs to meet requirements set by the Free-Electron Laser in Hamburg (FLASH), the amplifier is conceived for burst-mode operation. The main requirement is a high intra-burst pulse repetition rate of more than 100 kHz and a uniform pulse train (burst) with equal properties for every pulse. The burst-mode is an operation mode where the laser never reaches a lasing equilibrium, which means that the behavior of the amplifier is similar to a switch-on of the laser system for every burst. This makes the development of the amplifier system difficult. Therefore, an analytical model has been developed to study the amplification process during the burst. This includes the

  3. Single-pass high harmonic generation at high repetition rate and photon flux

    Science.gov (United States)

    Hädrich, Steffen; Rothhardt, Jan; Krebs, Manuel; Demmler, Stefan; Klenke, Arno; Tünnermann, Andreas; Limpert, Jens

    2016-09-01

    Sources of short wavelength radiation with femtosecond to attosecond pulse durations, such as synchrotrons or free electron lasers, have already made possible numerous, and will facilitate more, seminal studies aimed at understanding atomic and molecular processes on fundamental length and time scales. Table-top sources of coherent extreme ultraviolet to soft x-ray radiation enabled by high harmonic generation (HHG) of ultrashort pulse lasers have also gained significant attention in the last few years due to their enormous potential for addressing a plethora of applications, therefore constituting a complementary source to large-scale facilities (synchrotrons and free electron lasers). Ti:sapphire based laser systems have been the workhorses for HHG for decades, but are limited in repetition rate and average power. On the other hand, it has been widely recognized that fostering applications in fields such as photoelectron spectroscopy and microscopy, coincidence detection, coherent diffractive imaging and frequency metrology requires a high repetition rate and high photon flux HHG sources. In this article we will review recent developments in realizing the demanding requirement of producing a high photon flux and repetition rate at the same time. Particular emphasis will be put on suitable ultrashort pulse and high average power lasers, which directly drive harmonic generation without the need for external enhancement cavities. To this end we describe two complementary schemes that have been successfully employed for high power fiber lasers, i.e. optical parametric chirped pulse amplifiers and nonlinear pulse compression. Moreover, the issue of phase-matching in tight focusing geometries will be discussed and connected to recent experiments. We will highlight the latest results in fiber laser driven high harmonic generation that currently produce the highest photon flux of all existing sources. In addition, we demonstrate the first promising applications and

  4. All-optical repetition rate multiplication of pseudorandom bit sequences based on cascaded TOADs

    Science.gov (United States)

    Sun, Zhenchao; Wang, Zhi; Wu, Chongqing; Wang, Fu; Li, Qiang

    2016-03-01

    A scheme for all-optical repetition rate multiplication of pseudorandom bit sequences (PRBS) is demonstrated with all-optical wavelength conversion and optical logic gate 'OR' based on cascaded Tera-Hertz Optical Asymmetric Demultiplexers (TOADs). Its feasibility is verified by multiplication experiments from 500 Mb/s to 4 Gb/s for 23-1 PRBS and from 1 Gb/s to 4 Gb/s for 27-1 PRBS. This scheme can be employed for rate multiplication for much longer cycle PRBS at much higher bit rate over 40 Gb/s when the time-delay, the loss and the dispersion of the optical delay line are all precisely managed. The upper limit of bit rate will be restricted by the recovery time of semiconductor optical amplifier (SOA) finally.

  5. Development of a cryogenic hydrogen microjet for high-intensity, high-repetition rate experiments

    Science.gov (United States)

    Kim, J. B.; Göde, S.; Glenzer, S. H.

    2016-11-01

    The advent of high-intensity, high-repetition-rate lasers has led to the need for replenishing targets of interest for high energy density sciences. We describe the design and characterization of a cryogenic microjet source, which can deliver a continuous stream of liquid hydrogen with a diameter of a few microns. The jet has been imaged at 1 μm resolution by shadowgraphy with a short pulse laser. The pointing stability has been measured at well below a mrad, for a stable free-standing filament of solid-density hydrogen.

  6. Observation of Repetition-Rate Dependent Emission From an Un-Gated Thermionic Cathode Rf Gun

    Energy Technology Data Exchange (ETDEWEB)

    Edelen, J. P.; Sun, Y.; Harris, J.R.; Lewellen, J.W.

    2017-06-02

    Recent work at Fermilab in collaboration with the Advanced Photon Source and members of other national labs, designed an experiment to study the relationship between the RF repetition rate and the average current per RF pulse. While existing models anticipate a direct relationship between these two parameters we observed an inverse relationship. We believe this is a result of damage to the barium coating on the cathode surface caused by a change in back-bombardment power that is unaccounted for in the existing theories. These observations shed new light on the challenges and fundamental limitations associated with scaling an ungated thermionic cathode RF gun to high average current.

  7. Power scaling of supercontinuum seeded megahertz-repetition rate optical parametric chirped pulse amplifiers.

    Science.gov (United States)

    Riedel, R; Stephanides, A; Prandolini, M J; Gronloh, B; Jungbluth, B; Mans, T; Tavella, F

    2014-03-15

    Optical parametric chirped-pulse amplifiers with high average power are possible with novel high-power Yb:YAG amplifiers with kW-level output powers. We demonstrate a compact wavelength-tunable sub-30-fs amplifier with 11.4 W average power with 20.7% pump-to-signal conversion efficiency. For parametric amplification, a beta-barium borate crystal is pumped by a 140 W, 1 ps Yb:YAG InnoSlab amplifier at 3.25 MHz repetition rate. The broadband seed is generated via supercontinuum generation in a YAG crystal.

  8. OBSERVATION OF REPETITION-RATE DEPENDANT EMISSION FROM AN UN-GATED THERMIONIC CATHODE RF GUN

    Energy Technology Data Exchange (ETDEWEB)

    Edelen, J. P. [Fermilab; Sun, Y. [Argonne; Harris, J. R. [AFRL, NM; Lewellen, J. W. [Los Alamos Natl. Lab.

    2016-09-28

    Recent work at Fermilab in collaboration with the Advanced Photon Source and members of other national labs, designed an experiment to study the relationship between the RF repetition rate and the average current per RF pulse. While existing models anticipate a direct relationship between these two parameters we observed an inverse relationship. We believe this is a result of damage to the barium coating on the cathode surface caused by a change in back-bombardment power that is unaccounted for in the existing theories. These observations shed new light on the challenges and fundamental limitations associated with scaling an ungated thermionic cathode RF gun to high average current machines.

  9. Adjustable high-repetition-rate pulse trains in a passively-mode-locked fiber laser

    Science.gov (United States)

    Si Fodil, Rachid; Amrani, Foued; Yang, Changxi; Kellou, Abdelhamid; Grelu, Ph.

    2016-07-01

    We experimentally investigate multipulse regimes obtained within a passively-mode-locked fiber laser that includes a Mach-Zehnder (MZ) interferometer. By adjusting the time delay imbalance of the MZ, ultrashort pulse trains at multi-GHz repetition rates are generated. We compare the observed dynamics with high-harmonic mode locking, and show that the multi-GHz pulse trains display an inherent instability, which has been overlooked. By using a recirculation loop containing the MZ, we demonstrate a significant improvement of the pulse train stability.

  10. Optical Fiber Pumped High Repetition Rate and High Power Nd:YVO4 Picosecond Regenerative Amplifier

    Directory of Open Access Journals (Sweden)

    Zhen-Ao Bai

    2015-08-01

    Full Text Available We report a stable optical fiber pumped Nd:YVO4 all solid state regenerative amplifier with all fiber picosecond laser as seed source. 888 nm Yb optical fiber lasers was chosen as pump source to reduce quantum defect for improved thermal performance. At the repetition rate of 99.6 kHz, maximum power of 19.63 W with 36 ps pulse duration were achieved when seeded by a 150 mW picosecond oscillator. The wavelength delivered was 1064.07 nm with spectral width of 0.14 nm.

  11. HIGH REPETITION RATE MICROCHIP ER3+,YB3+:YAL3(BO34 DIODE-PUMPED LASER

    Directory of Open Access Journals (Sweden)

    K. N. Gorbachenya

    2012-01-01

    Full Text Available Diode-pumped passively Q-switched microchip Er,Yb:YAl3(BO34 laser for range-finding has been demonstrated. By using a Co2+:MgAl2O4 as a saturable absorber TEM00–mode Q-switched average output power of 315 mW was demonstrated at 1522 nm with pulse duration of 5 ns and pulse energy of 5,25 μJ at a repetition rate of 60 kHz.

  12. High-harmonic generation from plasma mirrors at kilohertz repetition rate

    OpenAIRE

    Quéré, Fabien

    2011-01-01

    International audience; We report the first demonstration of high-harmonic generation from plasma mirrors at a 1 kHz repetition rate. Harmonics up to nineteenth order are generated at peak intensities close to 1018 W=cm2 by focusing 1 mJ, 25 fs laser pulses down to 1:7 μm FWHM spot size without any prior wavefront correction onto a moving target. We minimize target surface motion with respect to the laser focus using online interferometry to ensure reproducible interaction conditions for ever...

  13. Spectrum analysis of all parameter noises in repetition-rate laser pulse train

    Institute of Scientific and Technical Information of China (English)

    Junhua Tang; Yuncai Wang

    2006-01-01

    @@ The theoretical investigation of all parameter noises in repetition-rate laser pulse train was presented. The expression of power spectrum of laser pulse trains with all parameter noises was derived, and the power spectra of pulse trains with different noise parameters were numerically simulated. By comparing the power spectra with and without pulse-width jitter, we noted that pulse-width jitter could not be neglected compared with amplitude noise and timing jitter and contributed a great amount of noise into the power spectrum under the condition that the product of pulse width and angular frequency was larger than 1.

  14. Choppers to optimise the repetition rate multiplication technique on a direct geometry neutron chopper spectrometer

    DEFF Research Database (Denmark)

    Vickery, Anette; Deen, P. P.

    2014-01-01

    In recent years the use of repetition rate multiplication (RRM) on direct geometry neutron spectrometers has been established and is the common mode of operation on a growing number of instruments. However, the chopper configurations are not ideally optimised for RRM with a resultant 100 fold flu...... in time resolution probed for a single European Spallation Source (ESS) period, which is ideal to probe complex relaxational behaviour. These two chopper configurations have been simulated for the Versatile Optimal Resolution direct geometry spectrometer, VOR, that will be built at ESS....

  15. High-repetition-rate femtosecond dye amplifier using a laser-diode-pumped neodymium:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Zysset, B.; LaGasse, M.J.; Fujimoto, J.G.; Kafka, J.D.

    1989-02-06

    A high-repetition-rate femotosecond dye amplifier is demonstrated using a laser-diode-pumped Q-switched Nd:YAG laser. Amplification of wavelength-tunable 300-fs pulses from a synchronously mode-locked rhodamine dye laser is achieved with a saturated gain of 70 and a small gain of 200 at a repetition rate of 800 Hz. Maximum pulse energies of 40 nJ are obtained, and pulse compression to as short as 30 fs is demonstrated.

  16. Scheme for independently stabilizing the repetition rate and optical frequency of a laser using a regenerative mode-locking technique.

    Science.gov (United States)

    Nakazawa, Masataka; Yoshida, Masato

    2008-05-15

    We have succeeded in achieving independent control of the repetition rate and optical frequency of a pulse laser by employing a regenerative mode-locking technique. By adopting a voltage-controlled microwave phase shifter or an optical delay line in a regenerative feedback loop we can control the repetition rate of the laser without directly disturbing the optical frequencies. We experimentally show how this independent control can be realized by employing a 40 GHz harmonically and regeneratively mode-locked fiber laser.

  17. BEAM DYNAMICS STUDIES OF A HIGH-REPETITION RATE LINAC-DRIVER FOR A 4TH GENERATION LIGHT SOURCE

    Energy Technology Data Exchange (ETDEWEB)

    Ventturini, M.; Corlett, J.; Emma, P.; Papadopoulos, C.; Penn, G.; Placidi, M.; Qiang, J.; Reinsch, M.; Sannibale, F.; Steier, C.; Sun, C.; Wells, R.

    2012-05-18

    We present recent progress toward the design of a super-conducting linac driver for a high-repetition rate FEL-based soft x-ray light source. The machine is designed to accept beams generated by the APEX photo-cathode gun operating with MHz-range repetition rate and deliver them to an array of SASE and seeded FEL beamlines. We review the current baseline design and report results of beam dynamics studies.

  18. How Do Algebra I Course Repetition Rates Vary among English Learner Students by Length of Time to Reclassification as English Proficient? REL 2017-222

    Science.gov (United States)

    Jaquet, Karina; Fong, Anthony B.

    2017-01-01

    Research has found high repetition rates for students in Algebra I, with one study finding a repetition rate of 44 percent for students in a large urban high school district. Less is known about how math performance and Algebra I course repetition rates vary among students with different levels of English proficiency. This report examines Algebra…

  19. The effects of laser repetition rate on femtosecond laser ablation of dry bone: a thermal and LIBS study.

    Science.gov (United States)

    Gill, Ruby K; Smith, Zachary J; Lee, Changwon; Wachsmann-Hogiu, Sebastian

    2016-01-01

    The aim of this study is to understand the effect of varying laser repetition rate on thermal energy accumulation and dissipation as well as femtosecond Laser Induced Breakdown Spectroscopy (fsLIBS) signals, which may help create the framework for clinical translation of femtosecond lasers for surgical procedures. We study the effect of repetition rates on ablation widths, sample temperature, and LIBS signal of bone. SEM images were acquired to quantify the morphology of the ablated volume and fsLIBS was performed to characterize changes in signal intensity and background. We also report for the first time experimentally measured temperature distributions of bone irradiated with femtosecond lasers at repetition rates below and above carbonization conditions. While high repetition rates would allow for faster cutting, heat accumulation exceeds heat dissipation and results in carbonization of the sample. At repetition rates where carbonization occurs, the sample temperature increases to a level that is well above the threshold for irreversible cellular damage. These results highlight the importance of the need for careful selection of the repetition rate for a femtosecond laser surgery procedure to minimize the extent of thermal damage to surrounding tissues and prevent misclassification of tissue by fsLIBS analysis.

  20. Fetal Heart Rate Monitoring from Phonocardiograph Signal Using Repetition Frequency of Heart Sounds

    Directory of Open Access Journals (Sweden)

    Hong Tang

    2016-01-01

    Full Text Available As a passive, harmless, and low-cost diagnosis tool, fetal heart rate (FHR monitoring based on fetal phonocardiography (fPCG signal is alternative to ultrasonographic cardiotocography. Previous fPCG-based methods commonly relied on the time difference of detected heart sound bursts. However, the performance is unavoidable to degrade due to missed heart sounds in very low signal-to-noise ratio environments. This paper proposes a FHR monitoring method using repetition frequency of heart sounds. The proposed method can track time-varying heart rate without both heart sound burst identification and denoising. The average accuracy rate comparison to benchmark is 88.3% as the SNR ranges from −4.4 dB to −26.7 dB.

  1. Analyzing the effect of high repetition laser shock peening on dynamic corrosion rate of magnesium

    Science.gov (United States)

    Caralapatti, Vinodh Krishna; Narayanswamy, Sivakumar

    2017-08-01

    Magnesium as implant material is being investigated extensively due to its superior suitability. With corrosion rate being the major obstacle, this paper aims to determine the effects of high repetition laser shock peening (HRLSP) on the dynamic corrosion rate of magnesium. While there is lot of research on corrosion of magnesium, in this work, a specially designed test bench was used for characterization of dynamic corrosion to mimic the physiological conditions experienced by the implant inside human body. From the results, it can be inferred that corrosion rate of peened samples reduced by at least 6 times compared to unpeened sample and sample peened with 66% overlap 1 scans exhibited the least corrosion. The wettability of the samples was also determined as a measure to analyze the effects of HRLSP on biocompatibility. In addition, peening is seen to induce surface corrosion, which minimizes the risks of implant failure.

  2. Diagnostic for a high-repetition rate electron photo-gun and first measurements

    Science.gov (United States)

    Filippetto, D.; Doolittle, L.; Huang, G.; Norum, E.; Portmann, G.; Qian, H.; Sannibale, F.

    2015-05-01

    The APEX electron source at LBNL combines the high-repetition-rate with the high beam brightness typical of photoguns, delivering low emittance electron pulses at MHz frequency. Proving the high beam quality of the beam is an essential step for the success of the experiment, opening the doors of the high average power to brightness-hungry applications as X-Ray FELs, MHz ultrafast electron diffraction etc.. As first step, a complete characterization of the beam parameters is foreseen at the Gun beam energy of 750 keV. Diagnostics for low and high current measurements have been installed and tested, and measurements of cathode lifetime and thermal emittance in a RF environment with mA current performed. The recent installation of a double slit system, a deflecting cavity and a high precision spectrometer, allow the exploration of the full 6D phase space. Here we discuss the present layout of the machine and future upgrades, showing the latest results at low and high repetition rate, together with the tools and techniques used.

  3. Crossatron switch as thyratron replacement in high repetition rate, high average power modulators

    Science.gov (United States)

    Sullivan, J. S.

    1988-06-01

    The Crossatron is a cold cathode, low pressure, gas discharge switch with opening and closing capabilities. Due to its cold cathode operation, the Crossatron may offer lifetime advantages compared to the hydrogen thyratron. Unfortunately, little information regarding Crossatron lifetime and performance in high repetition rate, high average power, pulse modulators exists. Four prototype Crossatron devices, fabricated by Hughes Aircraft, were obtained to evaluate their performance and lifetime in high repetition rate, high average power, pulse modulators that had previously been equipped with hydrogen thyratrons. The prototype Crossatrons were evaluated over a range of operating parameters. Various grid drive, keep alive power levels and triggering schemes were employed in the tests. Switch parameters such as trigger time, anode fall time, jitter, recovery time, peak di/dt, switch efficiency, and the gas pumping effect of the discharge were observed. One Crossatron prototype was also subjected to lifetime tests that accumulated tens of billions of pulses. Lifetime data will be compared to various thyratron models tested similarly.

  4. Repetition rate multiplication of frequency comb using all-pass fiber resonator

    Science.gov (United States)

    Yang, Lijun; Yang, Honglei; Zhang, Hongyuan; Wei, Haoyun; Li, Yan

    2016-09-01

    We propose a stable method for repetition rate multiplication of a 250-MHz Er-fiber frequency comb by a phase-locked all-pass fiber ring resonator, whose phase-locking configuration is simple. The optical path length of the fiber ring resonator is automatically controlled to be accurately an odd multiple of half of the original cavity length using an electronical phase-locking unit with an optical delay line. As for shorter cavity length of the comb, high-order odd multiple is preferable. Because the power loss depends only on the net-attenuation of the fiber ring resonator, the energetic efficiency of the proposed method is high. The input and output optical spectrums show that the spectral width of the frequency comb is clearly preserved. Besides, experimental results show less pulse intensity fluctuation and 35 dB suppression ratio of side-modes while providing a good long-term and short-term frequency stability. Higher-order repetition rate multiplication to several GHz can be obtained by using several fiber ring resonators in cascade configuration.

  5. Characterization of MHz pulse repetition rate femtosecond laser-irradiated gold-coated silicon surfaces

    Directory of Open Access Journals (Sweden)

    Venkatakrishnan Krishnan

    2011-01-01

    Full Text Available Abstract In this study, MHz pulse repetition rate femtosecond laser-irradiated gold-coated silicon surfaces under ambient condition were characterized by scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction analysis (XRD, and X-ray photoelectron spectroscopy (XPS. The radiation fluence used was 0.5 J/cm2 at a pulse repetition rate of 25 MHz with 1 ms interaction time. SEM analysis of the irradiated surfaces showed self-assembled intermingled weblike nanofibrous structure in and around the laser-irradiated spots. Further TEM investigation on this nanostructure revealed that the nanofibrous structure is formed due to aggregation of Au-Si/Si nanoparticles. The XRD peaks at 32.2°, 39.7°, and 62.5° were identified as (200, (211, and (321 reflections, respectively, corresponding to gold silicide. In addition, the observed chemical shift of Au 4f and Si 2p lines in XPS spectrum of the irradiated surface illustrated the presence of gold silicide at the irradiated surface. The generation of Si/Au-Si alloy fibrous nanoparticles aggregate is explained by the nucleation and subsequent condensation of vapor in the plasma plume during irradiation and expulsion of molten material due to high plasma pressure.

  6. Relativistic electron beams driven by single-cycle laser pulses at kHz repetition rate (Conference Presentation)

    Science.gov (United States)

    Faure, Jérôme; Guénot, Diego; Gustas, Dominykas; Vernier, Aline; Beaurepaire, Benoît; Böhle, Frederik; López-Martens, Rodrigo; Lifschitz, Agustin

    2017-05-01

    Laser-plasma accelerators are usually driven by 100-TW class laser systems with rather low repetition rates. However, recent years have seen the emergence of laser-plasma accelerators operating with kHz lasers and energies lower than 10 mJ. The high repetition-rate is particularly interesting for applications requiring high stability and high signal-to-noise ratio but lower energy electrons. For example, our group recently demonstrated that kHz laser-driven electron beams could be used to capture ultrafast structural dynamics in Silicon nano-membranes via electron diffraction with picosecond resolution. In these first experiments, electrons were injected in the density gradients located at the plasma exit, resulting in rather low energies in the 100 keV range. The electrons being nonrelativistic, the bunch duration quickly becomes picosecond long. Relativistic energies are required to mitigate space charge effects and maintain femtosecond bunches. In this paper, we will show very recent results where electrons are accelerated in laser-driven wakefields to relativistic energies, reaching up to 5 MeV at kHz repetition rate. The electron energy was increased by nearly two orders of magnitude by using single-cycle laser pulses of 3.5 fs, with only 2.5 mJ of energy. Using such short pulses of light allowed us to resonantly excite high amplitude and nonlinear plasma waves at high plasma density, ne=1.5-2×1020 cm-3, in a regime close to the blow-out regime. Electrons had a peaked distribution around 5 MeV, with a relative energy spread of 30 %. Charges in the 100's fC/shot and up to pC/shot where measured depending on plasma density. The electron beam was fairly collimated, 20 mrad divergence at Full Width Half Maximum. The results show remarkable stability of the beam parameters in terms of beam pointing and electron distribution. 3D PIC simulations reproduce the results very well and indicate that electrons are injected by the ionization of Nitrogen atoms, N5+ to N6

  7. The ringer - An efficient, high repetition rate circuit for electromagnetic launchers

    Science.gov (United States)

    Giorgi, D.; Helava, H.; Lindner, K.; Long, J.; Zucker, O.

    1989-01-01

    The Meatgrinder is an efficient, current-multiplying circuit which can be used to optimize the energy transfer to various electromagnetic gun configurations. The authors present a simple variant of the Meatgrinder circuit which permits a first-order current profiling into the gun and recovery of the inductive energy in the barrel at a high repetition rate. The circuit is basically a one-stage Meatgrinder which utilizes the ringing of the energy storage capacitor (less than 40 percent reversal) to perform the opening switch function and a solid-state diode as the crowbar switch between the two mutually coupled inductors. With resonant charging, this results in a completely passive, high-repetiton-rate electromagnetic-gun power supply. Since most of the barrel energy is recovered, a railgun with negligible muzzle flash can be realized.

  8. Temporal dynamics of high repetition rate pulsed single longitudinal mode dye laser

    Indian Academy of Sciences (India)

    G Sridhar; V S Rawar; S Singh; L M Gantayet

    2013-08-01

    Theoretical and experimental studies of temporal dynamics of grazing incidence grating (GIG) cavity, single-mode dye laser pumped by high repetition rate copper vapour laser (CVL) are presented. Spectral chirp of the dye laser as they evolve in the cavity due to transient phase dynamics of the amplifier gain medium is studied. Effect of grating efficiency, focal spot size, pump power and other cavity parameters on the temporal behaviour of narrow band dye laser such as build-up time, pulse shape and pulse width is studied using the four level dye laser rate equation and photon evolution equation. These results are compared with experimental observations of GIG single-mode dye laser cavity. The effect of pulse stretching of CVL pump pulse on the temporal dynamics of the dye laser is studied.

  9. Closed-Loop Control of Chemical Injection Rate for a Direct Nozzle Injection System

    Directory of Open Access Journals (Sweden)

    Xiang Cai

    2016-01-01

    Full Text Available To realize site-specific and variable-rate application of agricultural pesticides, accurately metering and controlling the chemical injection rate is necessary. This study presents a prototype of a direct nozzle injection system (DNIS by which chemical concentration transport lag was greatly reduced. In this system, a rapid-reacting solenoid valve (RRV was utilized for injecting chemicals, driven by a pulse-width modulation (PWM signal at 100 Hz, so with varying pulse width the chemical injection rate could be adjusted. Meanwhile, a closed-loop control strategy, proportional-integral-derivative (PID method, was applied for metering and stabilizing the chemical injection rate. In order to measure chemical flow rates and input them into the controller as a feedback in real-time, a thermodynamic flowmeter that was independent of chemical viscosity was used. Laboratory tests were conducted to assess the performance of DNIS and PID control strategy. Due to the nonlinear input–output characteristics of the RRV, a two-phase PID control process obtained better effects as compared with single PID control strategy. Test results also indicated that the set-point chemical flow rate could be achieved within less than 4 s, and the output stability was improved compared to the case without control strategy.

  10. Heart rate effects of intraosseous injections using slow and fast rates of anesthetic solution deposition.

    Science.gov (United States)

    Susi, Louis; Reader, Al; Nusstein, John; Beck, Mike; Weaver, Joel; Drum, Melissa

    2008-01-01

    The authors, using a crossover design, randomly administered, in a single-blind manner, 3 primary intraosseous injections to 61 subjects using: the Wand local anesthetic system at a deposition rate of 45 seconds (fast injection); the Wand local anesthetic system at a deposition rate of 4 minutes and 45 seconds (slow injection); a conventional syringe injection at a deposition rate of 4 minutes and 45 seconds (slow injection), in 3 separate appointments spaced at least 3 weeks apart. A pulse oximeter measured heart rate (pulse). The results demonstrated the mean maximum heart rate was statistically higher with the fast intraosseous injection (average 21 to 28 beats/min increase) than either of the 2 slow intraosseous injections (average 10 to 12 beats/min increase). There was no statistically significant difference between the 2 slow injections. We concluded that an intraosseous injection of 1.4 mL of 2% lidocaine with 1 : 100,000 epinephrine with the Wand at a 45-second rate of anesthetic deposition resulted in a significantly higher heart rate when compared with a 4-minute and 45-second anesthetic solution deposition using either the Wand or traditional syringe.

  11. Heat accumulation during high repetition rate ultrafast laser interaction: Waveguide writing in borosilicate glass

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haibin; Eaton, Shane M; Li, Jianzhao; Herman, Peter R [The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Toronto, ON, M5S 3G4 (Canada)

    2007-04-15

    During high repetition rate (>200 kHz) ultrafast laser waveguide writing, visible heat modified zones surrounding the formed waveguide occur as a result of heat accumulation. The radii of the heat-modified zones increase with the laser net fluence, and were found to correlate with the formation of low-loss and cylindrically symmetric optical waveguides. A numerical thermal model based on the finite difference method is applied here to account for cumulative heating and diffusion effects. The model successfully shows that heat propagation and accumulation accurately predict the radius of the 'heat modified' zones observed in borosilicate glass waveguides formed across a wide range of laser exposure conditions. Such modelling promises better control of thermal effects for optimizing the fabrication and performance of three-dimensional optical devices in transparent materials.

  12. Cavity-enhanced field-free molecular alignment at high repetition rate

    CERN Document Server

    Benko, Craig; Allison, Thomas K; Labaye, François; Ye, Jun

    2015-01-01

    Extreme ultraviolet frequency combs are a versatile tool with applications including precision measurement, strong-field physics, and solid-state physics. Here we report on an application of extreme ultraviolet frequency combs and their driving lasers to studying strong-field effects in molecular systems. We perform field-free molecular alignment and high-order hamonic generation with aligned molecules in a gas jet at 154 MHz repetition rate using a high-powered optical frequency comb inside a femtosecond enhancement cavity. The cavity-enhanced system provides means to reach suitable intensities to study field-free molecular alignment and enhance the observable effects of the molecule-field interaction. We observe modulations of the driving field, arising from the nature of impulsive stimulated Raman scattering responsible for coherent molecular rotations. We foresee impact of this work on the study of molecule-based strong-field physics, with improved precision and a more fundamental understanding of the int...

  13. High repetition rate tunable femtosecond pulses and broadband amplification from fiber laser pumped parametric amplifier.

    Science.gov (United States)

    Andersen, T V; Schmidt, O; Bruchmann, C; Limpert, J; Aguergaray, C; Cormier, E; Tünnermann, A

    2006-05-29

    We report on the generation of high energy femtosecond pulses at 1 MHz repetition rate from a fiber laser pumped optical parametric amplifier (OPA). Nonlinear bandwidth enhancement in fibers provides the intrinsically synchronized signal for the parametric amplifier. We demonstrate large tunability extending from 700 nm to 1500 nm of femtosecond pulses with pulse energies as high as 1.2 muJ when the OPA is seeded by a supercontinuum generated in a photonic crystal fiber. Broadband amplification over more than 85 nm is achieved at a fixed wavelength. Subsequent compression in a prism sequence resulted in 46 fs pulses. With an average power of 0.5 W these pulses have a peak-power above 10 MW. In particular, the average power and pulse energy scalability of both involved concepts, the fiber laser and the parametric amplifier, will enable easy up-scaling to higher powers.

  14. Low-repetition rate femtosecond laser writing of optical waveguides in water-white glass slides.

    Science.gov (United States)

    Lazcano, H E; Vázquez, G V

    2016-04-20

    Energy dose ranges for fabrication of subsurface and ablated ridge waveguides were defined using a low repetition rate femtosecond laser. The waveguides were written along the width of water-white glass slides. The buried waveguides written between 0.23 and 0.62  μJ/μm3 energy dose show strong guidance at 633 nm, reaching in the best cases propagation losses of 0.7 dB/cm. Meanwhile, the ridge waveguides were fabricated between 2.04 and 31.9  μJ/μm3, with a best case of 3.1 dB/cm. Outcomes of this study are promising for use in the manufacturing of sensing devices.

  15. High-power, high repetition-rate, green-pumped, picosecond LBO optical parametric oscillator.

    Science.gov (United States)

    Kienle, Florian; Teh, Peh Siong; Lin, Dejiao; Alam, Shaif-Ul; Price, Jonathan H V; Hanna, D C; Richardson, David J; Shepherd, David P

    2012-03-26

    We report on a picosecond, green-pumped, lithium triborate optical parametric oscillator with record-high output power. It was synchronously pumped by a frequency-doubled (530 nm), pulse-compressed (4.4 ps), high-repetition-rate (230 MHz), fiber-amplified gain-switched laser diode. For a pump power of 17 W, a maximum signal and idler power of 3.7 W and 1.8 W was obtained from the optical parametric oscillator. A signal pulse duration of ~3.2 ps was measured and wide tunability from 651 nm to 1040 nm for the signal and from 1081 nm to 2851 nm for the idler was achieved.

  16. High repetition rate Q-switched radially polarized laser with a graphene-based output coupler

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lifei; Jin, Chenjie; Qi, Mei; Chen, Xiaoming; Ren, Zhaoyu, E-mail: zhengxl@nwu.edu.cn, E-mail: rzy@nwu.edu.cn [National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base), and Institute of Photonics and Photon-Technology, Northwest University, Xi' an 710069 (China); Zheng, Xinliang, E-mail: zhengxl@nwu.edu.cn, E-mail: rzy@nwu.edu.cn [Department of Physics, Northwest University, Xi' an 710069 (China); Bai, Jintao [National Key Laboratory of Photoelectric Technology and Functional Materials (Culture Base), and Institute of Photonics and Photon-Technology, Northwest University, Xi' an 710069 (China); Department of Physics, Northwest University, Xi' an 710069 (China); Sun, Zhipei [Department of Micro- and Nanosciences, Aalto University, P.O. Box 13500, FI-00076 Aalto (Finland)

    2014-12-01

    We demonstrate a Q-switched radially polarized all-solid-state laser by transferring a graphene film directly onto an output coupler. The laser generates Q-switched radially polarized beam (QRPB) with a pulse width of 192 ns and 2.7 W average output power. The corresponding single pulse energy is up to 16.2 μJ with a high repetition rate of 167 kHz. The M{sup 2} factor and the polarization purity are ∼2.1 and 96%, respectively. Our QRPB source is a simple and low-cost source for a variety of applications, such as industrial material processing, optical trapping, and microscopy.

  17. A high repetition rate passively Q-switched microchip laser for controllable transverse laser modes

    Science.gov (United States)

    Dong, Jun; Bai, Sheng-Chuang; Liu, Sheng-Hui; Ueda, Ken-Ichi; Kaminskii, Alexander A.

    2016-05-01

    A Cr4+:YAG passively Q-switched Nd:YVO4 microchip laser for versatile controllable transverse laser modes has been demonstrated by adjusting the position of the Nd:YVO4 crystal along the tilted pump beam direction. The pump beam diameter-dependent asymmetric saturated inversion population inside the Nd:YVO4 crystal governs the oscillation of various Laguerre-Gaussian, Ince-Gaussian and Hermite-Gaussian modes. Controllable transverse laser modes with repetition rates over 25 kHz and up to 183 kHz, depending on the position of the Nd:YVO4 crystal, have been achieved. The controllable transverse laser beams with a nanosecond pulse width and peak power over hundreds of watts have been obtained for potential applications in optical trapping and quantum computation.

  18. Design Studies for a High-Repetition-Rate FEL Facility at LBNL.

    Energy Technology Data Exchange (ETDEWEB)

    CORLETT, J.; BELKACEM, A.; BYRD, J. M.; FAWLEY, W.; KIRZ, J.; LIDIA, S.; MCCURDY, W.; PADMORE, H.; PENN, G.; POGORELOV, I.; QIANG, J.; ROBIN, D.; SANNIBALE, F.; SCHOENLEIN, R.; STAPLES, J.; STEIER, C.; VENTURINI, M.; WAN, W.; WILCOX, R.; ZHOLENTS, A.

    2007-10-04

    Lawrence Berkeley National Laboratory (LBNL) is working to address the needs of the primary scientific Grand Challenges now being considered by the U.S. Department of Energy, Office of Basic Energy Sciences: we are exploring scientific discovery opportunities, and new areas of science, to be unlocked with the use of advanced photon sources. A partnership of several divisions at LBNL is working to define the science and instruments needed in the future. To meet these needs, we propose a seeded, high-repetition-rate, free-electron laser (FEL) facility. Temporally and spatially coherent photon pulses, of controlled duration ranging from picosecond to sub-femtosecond, are within reach in the vacuum ultraviolet (VUV) to soft X-ray regime, and LBNL is developing critical accelerator physics and technologies toward this goal. We envision a facility with an array of FELs, each independently configurable and tunable, providing a range of photon-beam properties with high average and peak flux and brightness.

  19. Compact, high-repetition-rate source for broadband sum-frequency generation spectroscopy

    Science.gov (United States)

    Heiner, Zsuzsanna; Petrov, Valentin; Mero, Mark

    2017-06-01

    We present a high-efficiency optical parametric source for broadband vibrational sum-frequency generation (BB-VSFG) for the chemically important mid-infrared spectral range at 2800-3600 cm-1 to study hydrogen bonding interactions affecting the structural organization of biomolecules at water interfaces. The source consists of a supercontinuum-seeded, dual-beam optical parametric amplifier with two broadband infrared output beams and a chirped sum-frequency mixing stage providing narrowband visible pulses with adjustable bandwidth. Utilizing a pulse energy of only 60 μJ from a turn-key, 1.03-μm pump laser operating at a repetition rate of 100 kHz, the source delivers 6-cycle infrared pulses at 1.5 and 3.2 μm with pulse energies of 4.6 and 1.8 μJ, respectively, and narrowband pulses at 0.515 μm with a pulse energy of 5.0 μJ. The 3.2-μm pulses are passively carrier envelope phase stabilized with fluctuations at the 180-mrad level over a 10-s time period. The 1.5-μm beamline can be exploited to deliver pump pulses for time-resolved studies after suitable frequency up-conversion. The high efficiency, stability, and two orders of magnitude higher repetition rate of the source compared to typically employed systems offer great potential for providing a boost in sensitivity in BB-VSFG experiments at a reduced cost.

  20. Assessing Sub-Antarctic Zone primary productivity from fast repetition rate fluorometry

    Science.gov (United States)

    Cheah, Wee; McMinn, Andrew; Griffiths, F. Brian; Westwood, Karen J.; Wright, Simon W.; Molina, Ernesto; Webb, Jason P.; van den Enden, Rick

    2011-11-01

    In situ primary productivity (PP) in the Sub-Antarctic Zone (SAZ) and the Polar Frontal Zone (PFZ) south of Australia was estimated using fast repetition rate fluorometry (FRRF). FRRF-derived PP at Process station 3 (P3) southeast of Tasmania (46°S, 153°E) were higher than P1 in the southwest of Tasmania (46°S, 140°E) and P2 in the Polar Frontal Zone (54°S, 146°E). The FRRF-derived PP rates were well correlated with 14C-uptake rates from one-hour incubations ( r2=0.85, slope=1.23±0.05, pMehler reaction, which are stimulated at high irradiance. Our results indicate that FRRF can be used to estimate photosynthesis rates in the SAZ and PFZ but to derive an accurate estimation of C-fixation requires a detailed understanding of the physiological properties of the cells and their response to oceanographic parameters under different environmental conditions.

  1. High-repetition rate industrial TEA CO2 laser with average output power of 1.5 kW

    Science.gov (United States)

    Wan, Chongyi; Liu, Shiming; Zhou, Jinwen; Qi, Jilan; Yang, Xiaola; Wu, Jin; Tan, Rongqing; Wang, Lichun; Mei, Qichu

    1995-03-01

    High power high repetition rate TEA CO2 laser has potential importance in material processing such as shock hardening, glazing, drilling, welding, and cutting for high damage threshold materials, as well as in chemical reaction and isotope separation. This paper describes a transverse-flow closed-cycle UV-preionized TEA CO2 laser with peak pulse power of 20 MW, maximum average power of 1.5 KW at repetition rate of 300 HZ. The laser has compact constructure of gas flow circulation system using tangential fans. With addition of small amounts of H2 and CO to the normal CO2-N2-He gas mixture, one filling sealed operating lifetime is up to millions of pulses. A novel spark gap switch has been developed for very high repetition rate laser discharge in the condition of high pulse power.

  2. Dynamics of dissipative solitons in a high repetition rate normal-dispersion erbium-doped fiber laser

    CERN Document Server

    Luo, Yiyang; Zhao, Luming; Sun, Qizhen; Wu, Zhichao; Xu, Zhilin; Fu, Songnian; Liu, Deming

    2016-01-01

    The dynamics of dissipative solitons (DSs) are explored in a high repetition rate normal-dispersion erbium-doped fiber laser for the first time. Despite of the high fundamental repetition rate of 129 MHz and thus the low pulse energy, a DS train with a dechirped pulse width of 418 fs, period-doubling of single and dual DSs, as well as 258 MHz 2nd-order harmonic mode-locking of DSs can be observed in the fiber laser with increasing pump power and appropriate settings. A transmitted semiconductor saturable absorber and a wavelength division multiplexer/isolator/tap hybrid module are employed to simplify the laser configuration, thus not only increasing the repetition rate, but also enhancing the stability and robustness of the fiber laser due to the commercial availability of all the components.

  3. A Real-Time Terahertz Time-Domain Polarization Analyzer with 80-MHz Repetition-Rate Femtosecond Laser Pulses

    Directory of Open Access Journals (Sweden)

    Takehiro Tachizaki

    2013-03-01

    Full Text Available We have developed a real-time terahertz time-domain polarization analyzer by using 80-MHz repetition-rate femtosecond laser pulses. Our technique is based on the spinning electro-optic sensor method, which we recently proposed and demonstrated by using a regenerative amplifier laser system; here we improve the detection scheme in order to be able to use it with a femtosecond laser oscillator with laser pulses of a much higher repetition rate. This improvement brings great advantages for realizing broadband, compact and stable real-time terahertz time-domain polarization measurement systems for scientific and industrial applications.

  4. A real-time terahertz time-domain polarization analyzer with 80-MHz repetition-rate femtosecond laser pulses.

    Science.gov (United States)

    Watanabe, Shinichi; Yasumatsu, Naoya; Oguchi, Kenichi; Takeda, Masatoshi; Suzuki, Takeshi; Tachizaki, Takehiro

    2013-03-11

    We have developed a real-time terahertz time-domain polarization analyzer by using 80-MHz repetition-rate femtosecond laser pulses. Our technique is based on the spinning electro-optic sensor method, which we recently proposed and demonstrated by using a regenerative amplifier laser system; here we improve the detection scheme in order to be able to use it with a femtosecond laser oscillator with laser pulses of a much higher repetition rate. This improvement brings great advantages for realizing broadband, compact and stable real-time terahertz time-domain polarization measurement systems for scientific and industrial applications.

  5. Compact and high repetition rate Kerr-lens mode-locked 532 nm Nd:YVO4 laser

    Science.gov (United States)

    Li, Zuohan; Peng, Jiying; Yuan, Ruixia; Wang, Tongtong; Yao, Jianquan; Zheng, Yi

    2015-11-01

    A compact and feasible CW Kerr-lens-induced mode-locked 532 nm Nd:YVO4 laser system was experimentally demonstrated for the first time with theoretical analysis. Kerr-lens mode locking with intracavity second harmonic generation provides a promising method to generate a high-repetition-rate picosecond green laser. With an incident pump power of 6 W, the average output power of mode locking was 258 mW at a high repetition rate of 1.1 GHz.

  6. Study of filamentation with a high power high repetition rate ps laser at 1.03 µm.

    Science.gov (United States)

    Houard, A; Jukna, V; Point, G; André, Y-B; Klingebiel, S; Schultze, M; Michel, K; Metzger, T; Mysyrowicz, A

    2016-04-01

    We study the propagation of intense, high repetition rate laser pulses of picosecond duration at 1.03 µm central wavelength through air. Evidence of filamentation is obtained from measurements of the beam profile as a function of distance, from photoemission imaging and from spatially resolved sonometric recordings. Good agreement is found with numerical simulations. Simulations reveal an important self shortening of the pulse duration, suggesting that laser pulses with few optical cycles could be obtained via double filamentation. An important lowering of the voltage required to induce guided electric discharges between charged electrodes is measured at high laser pulse repetition rate.

  7. Mode-locked Yb-doped fiber laser emitting broadband pulses at ultra-low repetition rates

    CERN Document Server

    Bowen, Patrick; Provo, Richard; Harvey, John D; Broderick, Neil G R

    2016-01-01

    We report on an environmentally stable, Yb-doped, all-normal dispersion, mode-locked fibre laser that is capable of creating broadband pulses with ultra-low repetition rates. Specifically, through careful positioning of fibre sections in an all-PM-fibre cavity mode-locked with a nonlinear amplifying loop mirror, we achieve stable pulse trains with repetition rates as low as 506 kHz. The pulses have several nanojules of energy and are compressible down to ultrashort (< 500 fs) durations.

  8. High-repetition rate relativistic electron beam generation from intense laser solid interactions

    Science.gov (United States)

    Batson, Thomas; Nees, John; Hou, Bixue; Thomas, A. G. R.; Krushelnick, Karl

    2015-05-01

    Relativistic electron beams have applications spanning materials science, medicine, and home- land security. Recent advances in short pulse laser technology have enabled the production of very high focused intensities at kHz rep rates. Consequently this has led to the generation of high ux sources of relativistic electrons- which is a necessary characteristic of these laser plasma sources for any potential application. In our experiments, through the generation of a plasma with the lambda cubed laser system at the University of Michigan (a 5 × 1018W=cm2, 500 Hz, Ti:Sapphire laser), we have measured electrons ejected from the surface of fused silica nd Cu targets having energies in excess of an MeV. The spectrum of these electrons was measured with respect to incident laser angle, prepulse timing, and focusing conditions. While taken at a high repetition rate, the pulse energy of the lambda cubed system was consistently on the order of 10 mJ. In order to predict scaling of the electron energy with laser pulse energy, simulations are underway which compare the spectrum generated with the lambda cubed system to the predicted spectrum generated on the petawatt scale HERCULES laser system at the University of Michigan.

  9. Research of application of high-repetition-rate green laser in underwater imaging system

    Science.gov (United States)

    Han, Jie-fei; Luo, Tao; Sun, Li-ying; Ding, Chi-zhu; Xia, Min; Yang, Ke-cheng

    2013-09-01

    It is commonly known that absorption and scattering are the main causes of reducing performance of imaging system, especially imaging distance and resolution. Generally, various techniques are applied to decrease the effect of scattering, such as synchronous scanning and range-gated technique. Continuous-laser imaging technique meets requirements of imaging objects in the large field of view in real time, but imaging distance is less than 2 attenuation lengths in natural water. High-repetition-rate green laser, called quasi-continuous wave (QCW) green laser, is a better light source for underwater imaging. It has 1 kHz-100 kHz modulated rate, and its single pulse peak power is KW magnitude, which can be applied to range-gated imaging as Canadian LUCIE system. In addition, its polarization property is excellent for underwater polarization imaging. Therefore, it has enormous potential to underwater imaging. In order to realize its performance in underwater imaging system, we setup a separated underwater staring imaging system. For this system, a theoretic model is built by the lidar equation and optic transmission theory, and the system is evaluated by modulation transfer function (MTF). The effects of laser and receiver's parameters for the system are analyzed. Then the comparative experiments are conducted in turbid water in laboratory. The results indicate that high pulse energy improves imaging distance. Aperture and polarization could reduce the effect of scattering effectively in staring system. The result shows that this underwater system performs better by choosing suitable parameters of source and receiver.

  10. Improved repetition rate mixed isotope CO{sub 2} TEA laser

    Energy Technology Data Exchange (ETDEWEB)

    Cohn, D. B., E-mail: dbctechnology@earthlink.net [DBC Technology Corp., 4221 Mesa St, Torrance, California 90505 (United States)

    2014-09-15

    A compact CO{sub 2} TEA laser has been developed for remote chemical detection that operates at a repetition rate of 250 Hz. It emits 700 mJ/pulse at 10.6 μm in a multimode beam with the {sup 12}C{sup 16}O{sub 2} isotope. With mixed {sup 12}C{sup 16}O{sub 2} plus {sup 13}C{sup 16}O{sub 2} isotopes it emits multiple lines in both isotope manifolds to improve detection of a broad range of chemicals. In particular, output pulse energies are 110 mJ/pulse at 9.77 μm, 250 mJ/pulse at 10 μm, and 550 mJ/pulse at 11.15 μm, useful for detection of the chemical agents Sarin, Tabun, and VX. Related work shows capability for long term sealed operation with a catalyst and an agile tuner at a wavelength shift rate of 200 Hz.

  11. Heart Rate Variability and Skin Conductance During Repetitive TMS Course in Children with Autism.

    Science.gov (United States)

    Wang, Yao; Hensley, Marie K; Tasman, Allan; Sears, Lonnie; Casanova, Manuel F; Sokhadze, Estate M

    2016-03-01

    Autism spectrum disorder (ASD) is a developmental disorder marked by difficulty in social interactions and communication. ASD also often present symptoms of autonomic nervous system (ANS) functioning abnormalities. In individuals with autism the sympathetic branch of the ANS presents an over-activation on a background of the parasympathetic activity deficits, creating an autonomic imbalance, evidenced by a faster heart rate with little variation and increased tonic electrodermal activity. The objective of this study was to explore the effect of 12 sessions of 0.5 Hz repetitive transcranial magnetic stimulation (rTMS) over dorsolateral prefrontal cortex (DLPFC) on autonomic activity in children with ASD. Electrocardiogram and skin conductance level (SCL) were recorded and analyzed during each session of rTMS. The measures of interest were time domain (i.e., R-R intervals, standard deviation of cardiac intervals, NN50-cardio-intervals >50 ms different from preceding interval) and frequency domain heart rate variability (HRV) indices [i.e., power of high frequency (HF) and low frequency (LF) components of HRV spectrum, LF/HF ratio]. Based on our prior pilot studies it was proposed that the course of 12 weekly inhibitory low-frequency rTMS bilaterally applied to the DLPFC will improve autonomic balance probably through improved frontal inhibition of the ANS activity, and will be manifested in an increased length of cardiointervals and their variability, and in higher frequency-domain HRV in a form of increased HF power, decreased LF power, resulting in decreased LF/HF ratio, and in decreased SCL. Our post-12 TMS results showed significant increases in cardiac intervals variability measures and decrease of tonic SCL indicative of increased cardiac vagal control and reduced sympathetic arousal. Behavioral evaluations showed decreased irritability, hyperactivity, stereotype behavior and compulsive behavior ratings that correlated with several autonomic variables.

  12. [INVITED] Laser welding of glasses at high repetition rates - Fundamentals and prospects

    Science.gov (United States)

    Richter, Sören; Zimmermann, Felix; Tünnermann, Andreas; Nolte, Stefan

    2016-09-01

    We report on the welding of various glasses with ultrashort laser pulses. Femtosecond laser pulses at repetition rates in the MHz range are focused at the interface between two substrates, resulting in multiphoton absorption and heat accumulation from successive pulses. This leads to local melting and subsequent resolidification which can be used to weld the glasses. The fundamental interaction process was studied using an in-situ micro Raman setup to measure the laser induced temperature distribution and its temporal decay. The induced network changes were analyzed by Raman spectrocopy identifying an increase of three and four membered silicon rings within the laser irradiated area. In order to determine the stability of the laser welded samples a three point bending test was used. Thereby, we identified that the maximal achievable breaking strength is limited by laser induced stress surrounding the modified material. To minimize the amount of stress bursts of laser pulses or an post processing annealing step can be applied. Besides fused silica, we welded borosilicate glasses and glasses with a low thermal expansion coefficient. Even the welding of different glass combinations is possible demonstrating the versatility of ultrashort pulse induced laser welding.

  13. Bottle microresonator broadband and low-repetition-rate frequency comb generator.

    Science.gov (United States)

    Dvoyrin, V; Sumetsky, M

    2016-12-01

    We propose a new type of broadband and low repetition rate (RR) frequency comb generator that has the shape of an elongated and nanoscale-shallow optical bottle microresonator created at the surface of an optical fiber. The free spectral range (FSR) of the broadband azimuthal eigenfrequency series of this resonator is the exact multiple of the FSR of the dense and narrowband axial series. The effective radius variation of the microresonator is close to a parabola with a nanoscale height that is greater or equal to λ/2πn0. (Here λ is the characteristic radiation wavelength and n0 is the refractive index of the microresonator material.) Overall, the microresonator possesses a broadband, small FSR and accurately equidistant spectrum convenient for the generation of a broadband and low RR optical frequency comb. It is shown that this comb can be generated by pumping with a cw laser, with a radiation frequency that matches a single axial eigenfrequency of the microresonator or, alternatively, by pumping with a mode-locked laser, which generates a narrowband low RR comb matching a series of equidistant axial eigenfrequencies situated between adjacent azimuthal eigenfrequencies.

  14. A high repetition rate experimental setup for quantum non-linear optics with cold Rydberg atoms

    Science.gov (United States)

    Busche, Hannes; Ball, Simon W.; Huillery, Paul

    2016-12-01

    Using electromagnetically induced transparency and photon storage, the strong dipolar interactions between Rydberg atoms and the resulting dipole blockade can be mapped onto light fields to realise optical non-linearities and interactions at the single photon level. We report on the realisation of an experimental apparatus designed to study interactions between single photons stored as Rydberg excitations in optically trapped microscopic ensembles of ultracold 87Rb atoms. A pair of in-vacuum high numerical aperture lenses focus excitation and trapping beams down to 1 μm, well below the Rydberg blockade. Thanks to efficient magneto-optical trap (MOT) loading from an atomic beam generated by a 2D MOT and the ability to recycle the microscopic ensembles more than 20000 times without significant atom loss, we achieve effective repetition rates exceeding 110 kHz to obtain good photon counting statistics on reasonable time scales. To demonstrate the functionality of the setup, we present evidence of strong photon interactions including saturation of photon storage and the retrieval of non-classical light. Using in-vacuum antennae operating at up to 40 GHz, we perform microwave spectroscopy on photons stored as Rydberg excitations and observe an interaction induced change in lineshape depending on the number of stored photons.

  15. Design of high gradient, high repetition rate damped C -band rf structures

    Science.gov (United States)

    Alesini, David; Bellaveglia, Marco; Bini, Simone; Gallo, Alessandro; Lollo, Valerio; Pellegrino, Luigi; Piersanti, Luca; Cardelli, Fabio; Migliorati, Mauro; Mostacci, Andrea; Palumbo, Luigi; Tocci, Simone; Ficcadenti, Luca; Pettinacci, Valerio

    2017-03-01

    The gamma beam system of the European Extreme Light Infrastructure-Nuclear Physics project foresees the use of a multibunch train colliding with a high intensity recirculated laser pulse. The linac energy booster is composed of 12 traveling wave C -band structures, 1.8 m long with a field phase advance per cell of 2 π /3 and a repetition rate of 100 Hz. Because of the multibunch operation, the structures have been designed with a dipole higher order mode (HOM) damping system to avoid beam breakup (BBU). They are quasiconstant gradient structures with symmetric input couplers and a very effective damping of the HOMs in each cell based on silicon carbide (SiC) rf absorbers coupled to each cell through waveguides. An optimization of the electromagnetic and mechanical design has been done to simplify the fabrication and to reduce the cost of the structures. In the paper, after a review of the beam dynamics issues related to the BBU effects, we discuss the electromagnetic and thermomechanic design criteria of the structures. We also illustrate the criteria to compensate the beam loading and the rf measurements that show the effectiveness of the HOM damping.

  16. A high repetition rate transverse beam profile diagnostic for laser-plasma proton sources

    Science.gov (United States)

    Dover, Nicholas; Nishiuchi, Mamiko; Sakaki, Hironao; Kando, Masaki; Nishitani, Keita

    2016-10-01

    The recently upgraded J-KAREN-P laser can provide PW peak power and intensities approaching 1022 Wcm-2 at 0.1 Hz. Scaling of sheath acceleration to such high intensities predicts generation of protons to near 100 MeV, but changes in electron heating mechanisms may affect the emitted proton beam properties, such as divergence and pointing. High repetition rate simultaneous measurement of the transverse proton distribution and energy spectrum are therefore key to understanding and optimising the source. Recently plastic scintillators have been used to measure online proton beam transverse profiles, removing the need for time consuming post-processing. We are therefore developing a scintillator based transverse proton beam profile diagnostic for use in ion acceleration experiments using the J-KAREN-P laser. Differential filtering provides a coarse energy spectrum measurement, and time-gating allows differentiation of protons from other radiation. We will discuss the design and implementation of the diagnostic, as well as proof-of-principle results from initial experiments on the J-KAREN-P system demonstrating the measurement of sheath accelerated proton beams up to 20 MeV.

  17. Design of a high repetition rate S-band photocathode gun

    Science.gov (United States)

    Han, Jang-Hui; Cox, Matthew; Huang, Houcheng; Pande, Shivaji

    2011-08-01

    Photocathode RF guns have been developed in many laboratories for generating high quality electron beams for free-electron lasers based on linear accelerators. Such guns can generate electron beams with an exceptionally high peak current as well as a small transverse emittance. Their applications have been recently expanded for ultrafast electron diffraction, coherent terahertz radiation, and X-ray or γ-ray radiation by Compton scattering. In this paper, we design an S-band normal-conducting gun with capabilities of high quality beam generation and high repetition rate operation. The RF design and thermal analysis of the gun cavity and coupler are introduced. Optimal position of the gun focusing solenoid for low emittance beam generation is found by performing particle tracking simulations. Then, the gun system is designed to be able to afford the optimal solenoid position. The cooling-water channel surrounding the gun cavity and coupler is designed and analyzed numerically. The pressure in the gun is simulated with a vacuum model containing the detailed inner structure of the gun. An injector for a free-electron laser application is designed by using this gun and the beam dynamics simulation is shown. A cold test with a prototype gun for confirmation of the RF design is reported.

  18. A HIGH REPETITION RATE VUV-SOFT X-RAY FEL CONCEPT

    Energy Technology Data Exchange (ETDEWEB)

    Corlett, J.; Byrd, J.; Fawley, W.M.; Gullans, M.; Li, D.; Lidia,S.M.; Padmore, H.; Penn, G.; Pogorelov, I.; Qiang, J.; Robin, D.; Sannibale, F.; Staples, J.W.; Steier, C.; Venturini, M.; Virostek, S.; Wan, W.; Wells, R.; Wilcox, R.; Wurtele, J.; Zholents, A.

    2007-06-24

    We report on design studies for a seeded FEL light source that is responsive to the scientific needs of the future. The FEL process increases radiation flux by several orders of magnitude above existing incoherent sources, and offers the additional enhancements attainable by optical manipulations of the electron beam: control of the temporal duration and bandwidth of the coherent output, reduced gain length in the FEL, utilization of harmonics to attain shorter wavelengths, and precise synchronization of the x-ray pulse with seed laser systems. We describe an FEL facility concept based on a high repetition rate RF photocathode gun, that would allow simultaneous operation of multiple independent FEL's, each producing high average brightness, tunable over the VUV-soft x-ray range, and each with individual performance characteristics determined by the configuration of the FEL. SASE, enhanced-SASE (ESASE), seeded, harmonic generation, and other configurations making use of optical manipulations of the electron beam may be employed, providing a wide range of photon beam properties to meet varied user demands.

  19. Design of a VHF-band RF Photoinjector with Megahertz BeamRepetition Rate

    Energy Technology Data Exchange (ETDEWEB)

    Staples, J.W.; Baptiste, K.M.; Corlett, J.N.; Kwiatkowski, S.; Lidia, S.M.; Qiang, J.; Sannibale, F.; Sonnad, K.G.; Virostek, S.P.; Wells, R.P.

    2007-06-01

    New generation accelerator-based X-ray light sources require high quality beams with high average brightness. Normal conducting L- and S-band photoinjectors are limited in repetition rate and D-C (photo)injectors are limited in field strength at the cathode. We propose a low frequency normal-conducting cavity, operating at 50 to 100MHz CW, to provide beam bunches of up to the cavity frequency. The photoinjector uses a re-entrant cavity structure, requiring less than 100 kW CW, with a peak wall power density less than 10 W/cm{sup 2}. The cavity will support a vacuum down to 10 picoTorr, with a load-lock mechanism for easy replacement of photocathodes. The photocathode can be embedded in a magnetic field to provide correlations useful for emittance exchange. Beam dynamics simulations indicate that normalized emittances smaller than 1 mm-mrad are possible with gap voltage of 750 kV, with fields up to 20 MV/m at the photocathode, for 1 nanocoulomb charge per bunch after acceleration and emittance compensation. Long-bunch operation (10's of picosecond) is made possible by the low cavity frequency, permitting low bunch current at the 750 kV gap voltage.

  20. High-repetition-rate picosecond pump laser based on a Yb:YAG disk amplifier for optical parametric amplification.

    Science.gov (United States)

    Metzger, Thomas; Schwarz, Alexander; Teisset, Catherine Yuriko; Sutter, Dirk; Killi, Alexander; Kienberger, Reinhard; Krausz, Ferenc

    2009-07-15

    We report an optically synchronized picosecond pump laser for optical parametric amplifiers based on an Yb:YAG thin-disk amplifier. At 3 kHz repetition rate, pulse energies of 25 mJ with 1.6 ps pulse duration were achieved with an rms fluctuation in pulse energy of pumped regenerative amplifier.

  1. High-repetition-rate optical delay line using a micromirror array and galvanometer mirror for a terahertz system.

    Science.gov (United States)

    Kitahara, Hideaki; Tani, Masahiko; Hangyo, Masanori

    2009-07-01

    We developed a high-repetition-rate optical delay line based on a micromirror array and galvanometer mirror for terahertz time-domain spectroscopy. The micromirror array is fabricated by using the x-ray lithographic technology. The measurement of terahertz time-domain waveforms with the new optical delay line is demonstrated successfully up to 25 Hz.

  2. High Repetition Rate Electron Beam RF-Acceleration and Sub-Millimeter Wave Generation Via a Free Electron Laser.

    Science.gov (United States)

    1986-02-14

    Period, Including Journal References: (a) D.B. McDermott, W.J. Nunan and N.C. Luhmann, Jr., "A High Duty Cycle, Compact 94 GHz Free Electron Laser...34 submitted to Journal IR and am-Waves. (b) W.J. Nunan , D.B. McDermott and N.C. Luhmann, Jr., "A High Repetition *Rate, Compact 94 GHz Free Electron Laser...34 Bulletin of the American Phy- * ) sical Society 30, 1543 (1985). L J (c) D.B. McDermott, W.J. Nunan and N.C. Luhmann, Jr., "A High RepetitionLL

  3. Oral-diadochokinetic rates for Hebrew-speaking healthy ageing population: non-word versus real-word repetition.

    Science.gov (United States)

    Ben-David, Boaz M; Icht, Michal

    2017-05-01

    Oral-diadochokinesis (oral-DDK) tasks are extensively used in the evaluation of motor speech abilities. Currently, validated normative data for older adults (aged 65 years and older) are missing in Hebrew. The effect of task stimuli (non-word versus real-word repetition) is also non-clear in the population of older adult Hebrew speakers. (1) To establish a norm for oral-DDK rate for older adult (aged 65 years and older) Hebrew speakers, and to investigate the possible effect of age and gender on performance rate; and (2) to examine the effects of stimuli (non-word versus real word) on oral-DDK rates. In experiment 1, 88 healthy older Hebrew speakers (60-95 years, 48 females and 40 males) were audio-recorded while performing an oral-DDK task (repetition of /pataka/), and repetition rates (syllables/s) were coded. In experiment 2, the effect of real-word repetition was evaluated. Sixty-eight older Hebrew speakers (aged 66-95 years, 43 females and 25 males) were asked to repeat 'pataka' (non-word) and 'bodeket' (Hebrew real word). Experiment 1: Oral-DDK performance for older adult Hebrew speakers was 5.07 syllables/s (SD = 1.16 syllables/s), across age groups and gender. Comparison of this data with Hebrew norms for younger adults (and equivalent data in English) shows the following gradient of oral-DDK rates: ages 15-45 > 65-74 > 75-86 years. Gender was not a significant factor in our data. Experiment 2: Repetition of real words was faster than that of non-words, by 13.5%. The paper provides normative values for oral-DDK rates for older Hebrew speakers. The data show the large impact of ageing on oro-motor functions. The analysis further indicates that speech and language pathologists should consider separate norms for clients of 65-74 years and those of 75-86 years. Hebrew rates were found to be different from English norms for the oldest group, shedding light on the impact of language on these norms. Finally, the data support using a dual-protocol (real- and non

  4. A Device and Methodology for Measuring Repetitive Lifting VO2max (Oxygen Consumption Rate)

    Science.gov (United States)

    1987-08-01

    and its estimate from skinfold thicknesses ; measurements on 481 men and women aged from 16 to 72 years. Br J Nutr 32:77-92. 3. Intaranont K, Ayoub MM...Justificaton --. By ......... AvaI~bty Co’der, L Ust Avdi iUl I r /1- Table of Contents Table of Contents iii List of Figures iv List of Tables v...during 28 repetitive lifting exercise iv List of Tables 1. Repetitive lifting device specifications 15 2. Subject sample descriptive data 24 3

  5. Repetition rate stabilization of an erbium-doped all-fiber laser via opto-mechanical control of the intracavity group velocity

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Xuling; He, Boqu; Zhao, Jian; Liu, Yang; Bai, Dongbi; Wang, Chao; Liu, Geping; Luo, Daping; Liu, Fengjiang; Li, Wenxue; Zeng, Heping, E-mail: hpzeng@phy.ecnu.edu.cn [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China); Yang, Kangwen; Hao, Qiang [Shanghai Key Laboratory of Modern Optical System, Engineering Research Center of Optical Instrument and System (Ministry of Education), School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China)

    2015-01-19

    We present a method for stabilizing the repetition rate of an erbium-doped all-fiber laser by inserting an electronic polarization controller (EPC) in the fiber laser cavity. The device exhibited good integration, low cost, and convenient operation. Such a repetition rate stabilization may facilitate an all-fiber laser comb system with high integration. The repetition rate was phase-locked to a Rb reference more than 72 h with a low feedback voltage applied to one channel of the EPC. The repetition rate was 74.6 MHz. The standard deviation and the repetition rate linewidth were 1.4 and 1.7 mHz, respectively.

  6. Real-time energy measurement of high repetition rate ultrashort laser pulses using pulse integration and FPGA processing.

    Science.gov (United States)

    Tang, Qi-Jie; Yang, Dong-Xu; Wang, Jian; Feng, Yi; Zhang, Hong-Fei; Chen, Teng-Yun

    2016-11-01

    Real-time energy measurement using pulse integration method for high repetition rate ultrashort laser pulses based on FPGA (Field-Programmable Gate Array) and high-speed pipeline ADC (Analog-to-Digital Convertor) is introduced in this paper. There are two parts contained in this method: pulse integration and real-time data processing. The pulse integration circuit will convert the pulse to the step type signals which are linear to the laser pulse energy. Through the real-time data processing part, the amplitude of the step signals will be obtained by ADC sampling and conducting calculation in real time in FPGA. The test result shows that the method with good linearity (4.770%) and without pulse measurement missing is suitable for ultrashort laser pulses with high repetition rate up to 100 MHz.

  7. 1  J, 0.5  kHz repetition rate picosecond laser.

    Science.gov (United States)

    Baumgarten, Cory; Pedicone, Michael; Bravo, Herman; Wang, Hanchen; Yin, Liang; Menoni, Carmen S; Rocca, Jorge J; Reagan, Brendan A

    2016-07-15

    We report the demonstration of a diode-pumped chirped pulse amplification Yb:YAG laser that produces λ=1.03  μm pulses of up to 1.5 J energy compressible to sub-5 ps duration at a repetition rate of 500 Hz (750 W average power). Amplification to high energy takes place in cryogenically cooled Yb:YAG active mirrors designed for kilowatt average power laser operation. This compact laser system will enable new advances in high-average-power ultrashort-pulse lasers and high-repetition-rate tabletop soft x-ray lasers. As a first application, the laser was used to pump a 400 Hz λ=18.9  nm laser.

  8. High-peak-power, high-repetition-rate intracavity optical parametric oscillator at 1.57μm

    Institute of Scientific and Technical Information of China (English)

    Yuye Wang; Degang Xu; Yizhong Yu; Wuqi Wen; Jingping Xiong; Peng Wang; Jianquan Yao

    2007-01-01

    We report a high-peak-power, high-repetition-rate diode-side-pumped Nd:YAG Q-switched intracavity optical parametric oscillator (IOPO) at 1.57μm with a type-Ⅱ non-critically phase-matched x-cut KTP crystal. The average power of 1.15 W at 1.57μm is obtained at 4.3-kHz repetition rate. The peak power of the pulses amounts to 33.4 kW with 8-ns duration. The average conversion efficiency from Q-switched 1.064-μm-wavelength input power to OPO signal output power is up to 10.5%.

  9. Real-time energy measurement of high repetition rate ultrashort laser pulses using pulse integration and FPGA processing

    Science.gov (United States)

    Tang, Qi-jie; Yang, Dong-xu; Wang, Jian; Feng, Yi; Zhang, Hong-fei; Chen, Teng-yun

    2016-11-01

    Real-time energy measurement using pulse integration method for high repetition rate ultrashort laser pulses based on FPGA (Field-Programmable Gate Array) and high-speed pipeline ADC (Analog-to-Digital Convertor) is introduced in this paper. There are two parts contained in this method: pulse integration and real-time data processing. The pulse integration circuit will convert the pulse to the step type signals which are linear to the laser pulse energy. Through the real-time data processing part, the amplitude of the step signals will be obtained by ADC sampling and conducting calculation in real time in FPGA. The test result shows that the method with good linearity (4.770%) and without pulse measurement missing is suitable for ultrashort laser pulses with high repetition rate up to 100 MHz.

  10. Optical breakdown and filamentation of femtosecond laser pulses propagating in air at a kHz repetition rate

    Institute of Scientific and Technical Information of China (English)

    Duan Zuo-Liang; Chen Jian-Ping; Li Ru-Xin; Lin Li-Huang; Xu Zhi-Zhan

    2004-01-01

    We report the experiments on the optical breakdown and filamentation of femtosecond laser pulses propagating in air at a kHz repetition rate and with several hundreds micro-joule-energy. A 10m-long filament and its breakup and merging at the nonlinear focal region produced by modulational instability of femtosecond laser pulses in air are observed. A simple model based on the nonlinear Schrodinger equation coupled with multiphoton ionization law is presented to explain the several experimental results.

  11. High energy picosecond Yb:YAG CPA system at 10 Hz repetition rate for pumping optical parametric amplifiers.

    Science.gov (United States)

    Klingebiel, Sandro; Wandt, Christoph; Skrobol, Christoph; Ahmad, Izhar; Trushin, Sergei A; Major, Zsuzsanna; Krausz, Ferenc; Karsch, Stefan

    2011-03-14

    We present a chirped pulse amplification (CPA) system based on diode-pumped Yb:YAG. The stretched ns-pulses are amplified and have been compressed to less than 900 fs with an energy of 200 mJ and a repetition rate of 10 Hz. This system is optically synchronized with a broadband seed laser and therefore ideally suited for pumping optical parametric chirped pulse amplification (OPCPA) stages on a ps-timescale.

  12. Generation of a Sub-10 fs Laser Pulse by a Ring Oscillator with a High Repetition Rate

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qing; ZHAO Yan-Ying; WEI Zhi-Yi

    2009-01-01

    @@ A compact femtoescond Ti:sapphire ring oscillator composed of chirped mirrors is designed. By accurately optimizing the intra-cavity dispersion and the mode locking range of the ring configuration, we generate laser pulses as short as 7.7 fs with a repetition rate as high as 745 MHz. The spectrum spans from 660nm to 940nm and the average output power is 480row under the cw pump laser of 7.5 W.

  13. High repetition rate Yb:CaF2 multipass amplifiers operating in the 100 mJ range

    OpenAIRE

    Dimitrios PAPADOPOULOS; Friebel, Florence; Pellegrina, Alain; Hanna, Marc; Camy, Patrice; Doualan, Jean-Louis; Moncorgé, Richard; Georges, Patrick; Druon, Frédéric

    2014-01-01

    International audience; — We present the research advances on the development of 50-200 mJ energy range diode-pumped Yb:CaF 2-based multipass amplifiers operating at relatively high repetition rates. These laser amplifiers are based on diverse innovative geometries. All these innovations aim to design compact, stable and reliable amplifiers adapted to our application that consists in pumping ultrashort-pulse OPCPA (optical parametric chirped pulse amplifier) systems in the frame of the Apollo...

  14. Neodymium glass laser with a pulse energy of 220 J and a pulse repetition rate of 0.02 Hz

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmin, A A; Kulagin, O V; Khazanov, Efim A; Shaykin, A A [Institute of Applied Physics, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

    2013-07-31

    A compact neodymium glass laser with a pulse energy of 220 J and a record-high pulse repetition rate of 0.02 Hz (pulse duration 30 ns) is developed. Thermally induced phase distortions are compensated using wave phase conjugation. The integral depolarisation of radiation is decreased to 0.4% by using linear compensation schemes. The second harmonic of laser radiation can be used for pumping Ti : sapphire multipetawatt complexes. (letters)

  15. Wakefield-acceleration of relativistic electrons with few-cycle laser pulses at kHz-repetition-rate

    Science.gov (United States)

    Guenot, Diego; Gustas, Dominykas; Vernier, Aline; Boehle, Frederik; Beaurepaire, Benoit; Lopez-Martens, Rodrigo; Faure, Jerome; Appli Team

    2016-10-01

    The generation of relativistic electron beams using laser wakefield acceleration has become a standard technique, providing low emittance electron bunches with femtosecond durations. However, this technique usually requires multi-ten-terawatt lasers and is thus limited to low repetition-rate (typically 10 Hz or less). We have recently demonstrated the generation of few MeV electrons using 2.5-mJ, 4-fs, 1-kHz repetition-rate laser pulses, focused to relativistic intensity onto a gas jet with electron density 1020 cm-3. We have investigated the influence of the pulse duration, the gas density. We demonstrated that an electron beam with a charge in the range of 10-fC/shot, with a divergence of 20-mrad and a peaked spectrum with energies between 2 and 4 MeV can be generated at kHz repetition-rate. These results confirm the possibility of using few-cycle laser pulses with very low energy for exciting wakefields in the bubble regime and for trapping electrons, as predicted by PIC simulations. This kHz electron source is ideally suited for performing electron diffraction experiments with very high temporal resolution. Our results also open the way to other applications, such as the generation of a kHz ultrafast X-ray source. ERC femtoelec.

  16. High speed laser drilling of metals using a high repetition rate, high average power ultrafast fiber CPA system.

    Science.gov (United States)

    Ancona, A; Röser, F; Rademaker, K; Limpert, J; Nolte, S; Tünnermann, A

    2008-06-09

    We present an experimental study on the drilling of metal targets with ultrashort laser pulses at high repetition rates (from 50 kHz up to 975 kHz) and high average powers (up to 68 Watts), using an ytterbium-doped fiber CPA system. The number of pulses to drill through steel and copper sheets with thicknesses up to 1 mm have been measured as a function of the repetition rate and the pulse energy. Two distinctive effects, influencing the drilling efficiency at high repetition rates, have been experimentally found and studied: particle shielding and heat accumulation. While the shielding of subsequent pulses due to the ejected particles leads to a reduced ablation efficiency, this effect is counteracted by heat accumulation. The experimental data are in good qualitative agreement with simulations of the heat accumulation effect and previous studies on the particle emission. However, for materials with a high thermal conductivity as copper, both effects are negligible for the investigated processing parameters. Therefore, the full power of the fiber CPA system can be exploited, which allows to trepan high-quality holes in 0.5mm-thick copper samples with breakthrough times as low as 75 ms.

  17. Effects of high-repetition-rate femtosecond laser micromachining on the physical and chemical properties of polylactide (PLA).

    Science.gov (United States)

    Jia, Wei; Luo, Yiming; Yu, Jian; Liu, Bowen; Hu, Minglie; Chai, Lu; Wang, Chingyue

    2015-10-19

    The effects of femtosecond laser ablation, with 115 fs pulses at 1040 nm wavelength and 57 MHz repetition-rate, on the physical and chemical properties of polylactide (PLA) were studied in air and in water. The surface of the PLA sample ablated by high-repetition-rate femtosecond laser was analysed using field emission scanning electron microscopy, infrared spectroscopy, raman spectroscopy, as well as X-ray photoelectron spectroscopy. Compared with the experiments in the air at ambient temperature, melting resolidification was negligible for the experiments conducted under water. Neither in air nor under water did oxidation and crystallization process take place in the laser ablated surface. In addition, the intensity of some oxygen related peaks increased for water experiments, probably due to the hydrolysis. Meantime, the chemical shift to higher energies appeared in C1s XPS spectrum of laser processing in water. Interestingly, a large amount of defects were observed after laser processing in air, while no significant change was shown under water experiments. This indicates that thermal and mechanical effects by high-repetition-rate femtosecond laser ablation in water are quite limited, which could be even ignored.

  18. Ultrafast, high repetition rate, ultraviolet, fiber-laser-based source: application towards Yb+ fast quantum-logic.

    Science.gov (United States)

    Hussain, Mahmood Irtiza; Petrasiunas, Matthew Joseph; Bentley, Christopher D B; Taylor, Richard L; Carvalho, André R R; Hope, Joseph J; Streed, Erik W; Lobino, Mirko; Kielpinski, David

    2016-07-25

    Trapped ions are one of the most promising approaches for the realization of a universal quantum computer. Faster quantum logic gates could dramatically improve the performance of trapped-ion quantum computers, and require the development of suitable high repetition rate pulsed lasers. Here we report on a robust frequency upconverted fiber laser based source, able to deliver 2.5 ps ultraviolet (UV) pulses at a stabilized repetition rate of 300.00000 MHz with an average power of 190 mW. The laser wavelength is resonant with the strong transition in Ytterbium (Yb+) at 369.53 nm and its repetition rate can be scaled up using high harmonic mode locking. We show that our source can produce arbitrary pulse patterns using a programmable pulse pattern generator and fast modulating components. Finally, simulations demonstrate that our laser is capable of performing resonant, temperature-insensitive, two-qubit quantum logic gates on trapped Yb+ ions faster than the trap period and with fidelity above 99%.

  19. A Simulation of the Effects of Varying Repetition Rate and Pulse Width of Nanosecond Discharges on Premixed Lean Methane-Air Combustion

    Directory of Open Access Journals (Sweden)

    Moon Soo Bak

    2012-01-01

    Full Text Available Two-dimensional kinetic simulation has been carried out to investigate the effects of repetition rate and pulse width of nanosecond repetitively pulsed discharges on stabilizing premixed lean methane-air combustion. The repetition rate and pulse width are varied from 10 kHz to 50 kHz and from 9 ns to 2 ns while the total power is kept constant. The lower repetition rates provide larger amounts of radicals such as O, H, and OH. However, the effect on stabilization is found to be the same for all of the tested repetition rates. The shorter pulse width is found to favor the production of species in higher electronic states, but the varying effects on stabilization are also found to be small. Our results indicate that the total deposited power is the critical element that determines the extent of stabilization over this range of discharge properties studied.

  20. Design concept and performance considerations for fast high power semiconductor switching for high repetition rate and high power excimer laser

    Science.gov (United States)

    Goto, Tatsumi; Kakizaki, Kouji; Takagi, Shigeyuki; Satoh, Saburoh; Shinohe, Takashi; Ohashi, Hiromichi; Endo, Fumihiko; Okamura, Katsuya; Ishii, Akira; Teranishi, Tsuneharu; Yasuoka, Koichi

    1997-07-01

    A semiconductor switching power supply has been developed, in which a novel structure semiconductor device, metal-oxide-semiconductor assisted gate-triggered thyristor (MAGT) was incorporated with a single stage magnetic pulse compression circuit (MPC). The MAGT was specially designed to directly replace thyratrons in a power supply for a high repetition rate laser. Compared with conventional high power semiconductor switching devices, it was designed to enable a fast switching, retaining a high blocking voltage and to extremely reduce the transient turn-on power losses, enduring a higher peak current. A maximum peak current density of 32 kA/cm2 and a current density risetime rate di/dt of 142 kA/(cm2×μs) were obtained at the chip area with an applied anode voltage of 1.5 kV. A MAGT switching unit connecting 32 MAGTs in series was capable of switching on more than 25 kV-300 A at a repetition rate of 5 kHz, which, coupled with the MPC, was equivalent to the capability of a high power thyratron. A high repetition rate and high power XeCl excimer laser was excited by the power supply. The results confirmed the stable laser operation of a repetition rate of up to 5 kHz, the world record to our knowledge. An average output power of 0.56 kW was obtained at 5 kHz where the shortage of the total discharge current was subjoined by a conventional power supply with seven parallel switching thyratrons, simultaneously working, for the MAGT power supply could not switch a greater current than that switched by one thyratron. It was confirmed by those excitations that the MAGT unit with the MPC could replace a high power commercial thyratron directly for excimer lasers. The switching stability was significantly superior to that of the thyratron in a high repetition rate region, judging from the discharge current wave forms. It should be possible for the MAGT unit, in the future, to directly switch the discharge current within a rise time of 0.1 μs with a magnetic assist.

  1. Thermal distortion and birefringence in repetition-rate plasma electrode Pockels cell for high average power

    Institute of Scientific and Technical Information of China (English)

    Dingxiang Cao; Xiongjun Zhang; Wanguo Zheng; Shaobo He; Zhan Sui

    2007-01-01

    We numerically study thermally induced birefringence and distortion in plasma electrode Pockels cell based on KD*P as the electro-optic material. This device can repetitively operate under the heat capacity mode.Simulation results indicate that the excellent switching performances and low wave-front distortion are achieved within several tens seconds working time at average power in excess of 1 kW.

  2. The effect of laser repetition rate on the LASiS synthesis of biocompatible silver nanoparticles in aqueous starch solution

    Directory of Open Access Journals (Sweden)

    Zamiri R

    2013-01-01

    Full Text Available Reza Zamiri,1 Azmi Zakaria,1,* Hossein Abbastabar Ahangar,2 Majid Darroudi,3 Golnoosh Zamiri,1 Zahid Rizwan,1 Gregor PC Drummen4,* 1Department of Physics, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 2Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Selangor Darul Ehsan, Malaysia; 3Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 4Bionanoscience and Bio-Imaging Program, Cellular Stress and Ageing Program, Bio&Nano-Solutions, Düsseldorf, Germany*These authors contributed to this work equallyAbstract: Laser ablation-based nanoparticle synthesis in solution is rapidly becoming popular, particularly for potential biomedical and life science applications. This method promises one pot synthesis and concomitant bio-functionalization, is devoid of toxic chemicals, does not require complicated apparatus, can be combined with natural stabilizers, is directly biocompatible, and has high particle size uniformity. Size control and reduction is generally determined by the laser settings; that the size and size distribution scales with laser fluence is well described. Conversely, the effect of the laser repetition rate on the final nanoparticle product in laser ablation is less well-documented, especially in the presence of stabilizers. Here, the influence of the laser repetition rate during laser ablation synthesis of silver nanoparticles in the presence of starch as a stabilizer was investigated. The increment of the repetition rate does not negatively influence the ablation efficiency, but rather shows increased productivity, causes a red-shift in the plasmon resonance peak of the silver–starch nanoparticles, an increase in mean particle size and size distribution, and a distinct lack of agglomerate formation. Optimal results were achieved at 10 Hz repetition rate, with a mean particle size of ~10 nm and a

  3. Oral-diadochokinetic rates for Hebrew-speaking school-age children: real words vs. non-words repetition.

    Science.gov (United States)

    Icht, Michal; Ben-David, Boaz M

    2015-02-01

    Oral-diadochokinesis (DDK) tasks are a common tool for evaluating speech disorders. Usually, these tasks involve repetitions of non-words. It has been suggested that repeating real words can be more suitable for preschool children. But, the impact of using real words with elementary school children has not been studied yet. This study evaluated oral-DDK rates for Hebrew-speaking elementary school children using non-words and real words. The participants were 60 children, 9-11 years old, with normal speech and language development, who were asked to repeat "pataka" (non-word) and "bodeket" (Hebrew real word). Data replicate the advantage generally found for real word repetition with preschoolers. Children produced real words faster than non-words for all age groups, and repetition rates were higher for the older children. The findings suggest that adding real words to the standard oral-DDK task with elementary school children may provide a more comprehensive picture of oro-motor function.

  4. Laser-diode pumped self-mode-locked praseodymium visible lasers with multi-gigahertz repetition rate.

    Science.gov (United States)

    Zhang, Yuxia; Yu, Haohai; Zhang, Huaijin; Di Lieto, Alberto; Tonelli, Mauro; Wang, Jiyang

    2016-06-15

    We demonstrate efficient laser-diode pumped multi-gigahertz (GHz) self-mode-locked praseodymium (Pr3+) visible lasers with broadband spectra from green to deep red for the first time to our knowledge. With a Pr3+-doped GdLiF4 crystal, stable self-mode-locked visible pulsed lasers at the wavelengths of 522 nm, 607 nm, 639 nm, and 720 nm have been obtained with the repetition rates of 2.8 GHz, 3.1 GHz, 3.1 GHz, and 3.0 GHz, respectively. The maximum output power was 612 mW with the slope efficiency of 46.9% at 639 nm. The mode-locking mechanism was theoretically analyzed. The stable second-harmonic mode-locking with doubled repetition frequency was also realized based on the Fabry-Perot effect formed in the laser cavity. In addition, we find that the polarization directions were turned with lasing wavelengths. This work may provide a new way for generating efficient ultrafast pulses with high- and changeable-repetition rates in the visible range.

  5. Fertilization rate and its determinants in intracytoplasmic sperm injection

    Science.gov (United States)

    Jawed, Shireen; Rehman, Rehana; Ali, Mohammad Ashfaq; Abdullah, Umme Hani; Gul, Hina

    2016-01-01

    Objective: To identify predictors of fertilization rate in patients of unexplained infertility after intracytoplasmic sperm injection (ICSI). Methods: Retrospective analysis of females (282) enrolled in quasi experimental design for ICSI at “Islamabad Clinic Serving Infertile Couples” was carried out from July 2013 till June 2014. Females with unexplained infertility were included, whereas well defined male and female causes of infertility were excluded. Fertilization rate (FR) was calculated as percentage transformation of micro injected oocytes into two pronuclei. Categorical variable of FR defined on the basis of 50% FR grouped females; Group I with FR ≤50% and Group II with FR >50%. The groups were compared in terms of demographic variables, base line hormones and oocyte parameters. Univariate logistic regression was executed to obtain odds ratio with 95% confidence interval to quantify the association of predictors like age, duration of infertility, oocytes parameters, hormones; Estradiol, progesterone, follicle stimulating hormone (FSH), luteinizing hormone, prolactin and cytokines interleukin-Iβ (IL-Iβ) with the FR. Results: In our study out of 282 females, 19 (6.73%) were in group I and 263 (93.26%) comprised of Group II. Females with high FR(group II) had low Progesterone and FSH (p=0.04, p=0.02) respectively. Mature oocytes (OR: 0.35; 95% CI 1 – 2.56) and IL-Iβ in follicular phase (OR: 1.04; 95% CI: 0.000- 1.20) were significant positive predictors of FR while peak progesterone and FSH had significant negative effect on it Conclusion: Fertilization of oocytes in females of unexplained infertility depended on maturity of oocytes and optimal amounts of ILI- β released by developing follicles in the follicular phase of stimulation cycles of ICSI. PMID:27022334

  6. 3.7 GHz repetition rate operated narrow-bandwidth picosecond pulsed Yb fiber amplifier with an all-fiber multiplier

    Science.gov (United States)

    Wei, K. H.; Wen, R. H.; Guo, Y.

    2016-04-01

    A high power picosecond pulsed Yb fiber amplifier with a pulse repetition rate of 3.7 GHz is experimentally demonstrated. The seed is a gain switched distributed Bragg reflection (DBR) structured laser diode (LD) with a pulse duration of 130 ps and a repetition rate of 460 MHz. The pulse repetition rate is increased to 3.7 GHz by introducing an all-fiber multiplier, which is composed of four 2  ×  2 structured fiber couplers. The multiplied pulse train is amplified to 81 W through two stage Yb fiber amplifiers.

  7. Investigation on repetition rate and pulse duration influences on ablation efficiency of metals using a high average power Yb-doped ultrafast laser

    Directory of Open Access Journals (Sweden)

    Lopez J.

    2013-11-01

    Full Text Available Ultrafast lasers provide an outstanding processing quality but their main drawback is the low removal rate per pulse compared to longer pulses. This limitation could be overcome by increasing both average power and repetition rate. In this paper, we report on the influence of high repetition rate and pulse duration on both ablation efficiency and processing quality on metals. All trials have been performed with a single tunable ultrafast laser (350 fs to 10ps.

  8. End-pumped all solid-state high repetition rate Tm, Ho:LuLF laser

    Institute of Scientific and Technical Information of China (English)

    Shijiang Shu; Ting Yu; Junyan Hou; Rongtao Liu; Minjie Huang; Weibiao Chen

    2011-01-01

    @@ The characteristics of diode end-pumped Tm,Ho:LuLiF for continuous wave (CW) running and high pulse repetition frequency (PRF) Q-switched operation are illustrated. In the CW mode, 950-mW output power with a slope efficiency of 24% is obtained. In the Q-switched mode, output energy of 78 μJ under 10 kHz with a slope efficiency of 23% is achieved. The pulse stability, pulse width as a function of pump intensity, and spectral characteristics are also analyzed.%The characteristics of diode end-pumped Tm,Ho:LuLiF for continuous wave (CW) running and high pulse repetition frequency (PRF) Q-switched operation are illustrated. In the CW mode, 950-mW output power with a slope efficiency of 24% is obtained. In the Q-switched mode, output energy of 78μJ under 10 kHz with a slope efficiency of 23% is achieved. The pulse stability, pulse width as a function of pump intensity, and spectral characteristics are also analyzed.

  9. Rates of inappropriate antiretroviral prescription among injection drug users

    Directory of Open Access Journals (Sweden)

    Bonner Simon

    2007-01-01

    Full Text Available Abstract Background Although the survival benefits of antiretroviral therapy (ART for the treatment of HIV infection are well established, the clinical management of HIV disease continues to present major challenges. There are particular concerns regarding access to appropriate HIV treatment among HIV-infected injection drug users (IDU. Methods In a prospective cohort study of HIV-infected IDU in Vancouver, Canada, we examined initial ART regimens vis-à-vis the provincial government's therapeutic guidelines at the time ART was initiated. Briefly, there have been four sets of guidelines: Era 1 (1992 to November 1995; double-drug (dual NRTIs ART for patients with a CD4 cell count of 350 or less; Era 2 (December 1995 to May 1996; double-drug therapy for patients with a CD4+ cell count of 500 or less; Era 3 (June 1996 to June 1997; triple-drug therapy (dual NRTIs with a PI or NNRTI for patients who had a plasma viral load of > 100,000 HIV-1 RNA copies/mL; dual therapy with two NRTIs for those with a plasma viral load of 5,000 to 100,000 HIV-1 RNA copies/mL; Era 4 (since July 1997; universal use of triple drug therapy as first-line treatment. Results Between May 1996 and May 2003, 431 HIV-infected individuals were enrolled into the cohort. By May 31, 2003, 291 (67.5% individuals had initiated ART. We noted instances of inappropriate antiretroviral prescription in each guideline era, with 9 (53% in Era 1, 3 (12% in Era 2, 22 (28% in Era 3, and 23 (15% in Era 4. Of the 57 subjects who received an inappropriate ART regimen initially, 14 never received the appropriate therapy; among the remaining 43, the median time to the initiation of a guideline-appropriate ART regimen was 12 months (inter-quartile range 5 – 20. Conclusion The present study identified measurable rates of guideline-inappropriate ART prescription for patients who were injection drug users. Rates were highest in the era of dual therapy, although high rates persisted into the triple

  10. High-power LD side-pump Nd: YAG regenerative amplifier at 1 kHz repetition rate with volume Bragg gratings (VBG) for broadening and compressor

    Science.gov (United States)

    Long, Ming-Liang; Chen, Li-Yuan; Chen, Meng; Li, Gang

    2016-05-01

    Pulse width of 8.7 ps was broadened to 102.2, 198 ps with single and double pass the VBG respectively. When the 102.2 ps pulse was injected into 1 kHz repetition rate of LD side-pump Nd: YAG regenerative amplifier (RA), pulse width of 87.5 ps at 1 kHz was obtained with the pulse energy of 9.4 mJ, the beam quality of M^2 factor was 1.2. The pulse width was compressed to 32.7 ps with a single pass VBG and the pulse energy reduced to 8.8 mJ, and the power density was up to 15.2 GW/cm2, the stability for pulse to pulse rms is about 0.6 %, beam pointing was about 35 μrad. In addition, when 198 ps pulse was injected into RA, pulse width of 156 ps was obtained which energy was 9.6 mJ, the pulse width was compressed to 38 ps by double passing the VBG, the pulse energy decreased to 8.5 mJ. Chirped VBG is a new way to obtain high-intensity picosecond pulse laser system simple and smaller.

  11. SU-E-T-460: Impact of the LINAC Repetition Rate On a High-Resolution Liquid Ionization Chamber Array for Patient-Specific QA

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S; Driewer, J; Zheng, D; Lei, Y; Zhang, Q; Zhu, X; Li, S; Enke, C; Zhou, S [University of Nebraska Medical Center, Omaha, NE (United States); Xu, B [The Fujian Medical University Union Hospital, Fu Zhou, Fu Jian (China)

    2015-06-15

    Purpose: The purpose of this study is to investigate the LINAC repetition-rate (dose-rate) dependence of OCTAVIUS 1000SRS liquid ionization chamber (LIC) array for patient specific QA of SRT plans delivered with flattening-filter-free (FFF) beams. Methods: 1) The repetition-rate dependence of 1000SRS was measured in a phantom constructed with 5-cm solid water above and below the array for build-up and backscatter. A 0.3cc calibrated ion chamber was also placed along the central axis 2.3cm below the center chamber of the array for normalizing LINAC output fluctuation. The signals from the center chamber of the array under different repetition rates in the range of 400–2400 MU/min for 6xFFF and 10xFFF beams on a Varian TrueBeamSTx LINAC, normalized by the independent chamber readings, were analyzed for the array response dependence on repetition rates. 2) Twelve Step-and-shoot IMRS QA plans (6xFFF and 10xFFF) were delivered to the array under different repetition rates for analysis and comparison. 3) The absolute doses measured by the center chamber were compared to measurements using an independent ionization chamber with the identical setup, taken as the gold standard. 4) The correction factors based on the actual delivery repetition rate were applied to the measurements, and the results were compared again to the gold standard. Results: 1) The 1000SRS array exhibited repetition-rate dependence for FFF beams, up to 5% for 6xFFF and 10% for 10xFFF; 2) The array showed clinically-acceptable repetition-rate dependence for regular flattened beams; 3) This repetition-rate dependence significantly affected the measurement accuracy, thereby affecting IMRS QA results; 4) By applying an empirical repetition-rate correction, the corrected measurements agreed better with the gold standard ion chamber measurements. Conclusion: OCTAVIUS 1000SRS LIC array exhibited considerable repetition-rate dependence for FFF beams, which will affect the accuracy of the absolute QA

  12. Efficient intracavity frequency doubling of a high-repetition-rate diode-pumped Nd:YAG laser.

    Science.gov (United States)

    Hanson, F; Poirier, P

    1994-10-01

    Efficient operation of a pulsed, high-repetition-rate diode-pumped and intracavity frequency-doubled Nd:YAG laser is reported. A 3-mm-diameter laser rod was side-pumped with a 5-bar stack of high-duty-cycle 1-cm diodearrays. The average Q-switched power at 1.06microum was 3.8 W at 1.33 kH(z), and more than 4 W at 0.532 ,microm wasobtained through intracavity frequency doubling with LiB(3)O(5).

  13. Femtosecond laser ablation: Experimental study of the repetition rate influence on inductively coupled plasma mass spectrometry performance

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, Jhanis J. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Fernandez, Alberto [Centro de Fisicoquimica. Escuela de Quimica, Universidad Central de Venezuela, Caracas 1020-A (Venezuela); Oropeza, Dayana; Mao Xianglei [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Russo, Richard E. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)], E-mail: RERusso@lbl.gov

    2008-02-15

    This paper demonstrates the feasibility of performing bulk chemical analysis based on laser ablation for good lateral resolution with only nominal mass ablated per pulse. The influence of repetition rate (1-1000 Hz) and scan speed (1-200 {mu}m/s) using a low energy (30 {mu}J) and a small spot size ({approx} 10 {mu}m) UV-femtosecond laser beam was evaluated for chemical analysis of silica glass samples, based on laser ablation sampling and inductively coupled plasma mass spectrometry (ICP-MS). Accuracy to approximately 14% and precision of 6% relative standard deviation (RSD) were measured.

  14. Mechanisms of high-regularity periodic structuring of silicon surface by sub-MHz repetition rate ultrashort laser pulses

    Science.gov (United States)

    Gnilitskyi, Iaroslav; Gruzdev, Vitaly; Bulgakova, Nadezhda M.; Mocek, Tomáš; Orazi, Leonardo

    2016-10-01

    Silicon is one of the most abundant materials which is used in many areas of modern research and technology. A variety of those applications require surface nanopatterning with minimum structure defects. However, the high-quality nanostructuring of large areas of silicon surface at industrially acceptable speed is still a challenge. Here, we report a rapid formation of highly regular laser-induced periodic surface structures (HR-LIPSS) in the regime of strong ablation by infrared femtosecond laser pulses at sub-MHz repetition rate. Parameters of the laser-surface interactions and obtained experimental results suggest an important role of electrostatically assisted bond softening in initiating the HR-LIPSS formation.

  15. Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate

    Science.gov (United States)

    He, Z.-H.; Thomas, A. G. R.; Beaurepaire, B.; Nees, J. A.; Hou, B.; Malka, V.; Krushelnick, K.; Faure, J.

    2013-02-01

    We show that electron bunches in the 50-100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.

  16. A Compact, Transportable, Microchip-Based System for High Repetition Rate Production of Bose-Einstein Condensates

    CERN Document Server

    Farkas, Daniel M; Salim, Evan A; Segal, Stephen R; Squires, Matthew B; Anderson, Dana Z

    2009-01-01

    We present a compact, transportable system that produces Bose-Einstein condensates (BECs) near the surface of an integrated atom microchip. The system occupies a volume of 0.4 m^3 and operates at a repetition rate as high as 0.3 Hz. Evaporative cooling in a chip trap with trap frequencies of several kHz leads to nearly pure condensates containing 1.9x10^4 87Rb atoms. Partial condensates are observed at a temperature of 1.58(8) \\mu K, close to the theoretical transition temperature of 1.1 \\mu K.

  17. Actual laser removal of black soiling crust from siliceous sandstone by high pulse repetition rate equipment: effects on surface morphology

    Directory of Open Access Journals (Sweden)

    Iglesias-Campos, M. A.

    2016-03-01

    Full Text Available This research project studies the role of pulse repetition rate in laser removal of black soiling crust from siliceous sandstone, and specifically, how laser fluence correlates with high pulse repetition rates in cleaning practice. The aim is to define practical cleaning processes and determine simple techniques for evaluation based on end-users’ perspective (restorers. Spot and surface tests were made using a Q-switched Nd:YAG laser system with a wide range of pulse repetition rates (5–200 Hz, systematically analysed and compared by macrophotography, portable microscope, stereomicroscope with 3D visualizing and area roughness measurements, SEM imaging and spectrophotometry. The results allow the conclusion that for operation under high pulse repetition rates the average of total energy applied per spot on a treated surface should be attendant upon fluence values in order to provide a systematic and accurate description of an actual laser cleaning intervention.En este trabajo se estudia el papel de la frecuencia de repetición en la limpieza láser de costras de contaminación sobre una arenisca silícea, y concretamente, como se relaciona fluencia y frecuencias elevadas en una limpieza real. Se pretende definir un procedimiento práctico de limpieza y determinar técnicas sencillas de evaluación desde el punto de vista de los usuarios finales (restauradores. Para el estudio se realizaron diferentes ensayos en spot y en superficie mediante un equipo Q-switched Nd:YAG con un amplio rango de frecuencias (5–200 Hz, que se analizaron y compararon sistemáticamente mediante macrofotografía, microscopio portátil, estereomicroscopio con visualización 3D y mediciones de rugosidad en área, imágenes SEM y espectrofotometría. Los resultados permiten proponer que, al trabajar con altas frecuencias, la media de la energía total depositada por spot en la superficie debería acompañar los valores de fluencia para describir y comprender mejor una

  18. Performance Optimization of a High-Repetition-Rate KrF Laser Plasma X-Ray Source for Microlithography.

    Science.gov (United States)

    Bukerk, F; Louis, E; Turcu, E C; Tallents, G J; Batani, D

    1992-01-01

    In order to develop a high-intensity laser plasma x-ray source appropriate for industrial application of x-ray lithography, experiments have been carried out using a high-repetition-rate (up to 40 Hz) excimer laser (249 nm, 300 mJ) with a power density of 2 × 1013 W/ cm2 in the laser focus. In this study emphasis is given to remedying specific problems inherent in operating the laser plasma x-ray source at high repetition rates and in its prolonged operation. Two different methods of minimizing the production of target debris are investigated. First, the use of helium as a quenching gas results in a reduction of the amount of atomic debris particles by more than two orders of magnitude with negligible x-ray absorption. Second, a tape target as opposed to a solid target reduces the production of larger debris particles by a further factor of 100. Remaining debris is stopped by an aluminized plastic or beryllium filter used to avoid exposure of the resist by plasma ultraviolet radiation. The x-ray source has been used to image x-ray transmission mask structures down to 0.3 μm onto general purpose x-ray photo-resist. Results have been analyzed with SEM. The x-ray emission spectrum of the repetitive laser plasmas created from an iron target has been recorded and the conversion efficiency of the laser light into x-rays that contribute to exposure of the resist was measured to be 0.3% over 2π sr.

  19. Embedded computer controlled premixing inline injection system for air-assisted variable-rate sprayers

    Science.gov (United States)

    Improvements to reduce chemical waste and environmental pollution for variable-rate sprayers used in orchards and ornamental nurseries require inline injection techniques. A microprocessor controlled premixing inline injection system implementing a ceramic piston chemical metering pump and two small...

  20. High-power, highly stable KrF laser with a 4-kHz pulse repetition rate

    Science.gov (United States)

    Borisov, V. M.; El'tsov, A. V.; Khristoforov, O. B.

    2015-08-01

    An electric-discharge KrF laser (248 nm) with an average output power of 300 W is developed and studied. A number of new design features are related to the use of a laser chamber based on an Al2O3 ceramic tube. A high power and pulse repetition rate are achieved by using a volume discharge with lateral preionisation by the UV radiation of a creeping discharge in the form of a homogeneous plasma sheet on the surface of a plane sapphire plate. Various generators for pumping the laser are studied. The maximum laser efficiency is 3.1%, the maximum laser energy is 160 mJ pulse-1, and the pulse duration at half maximum is 7.5 ns. In the case of long-term operation at a pulse repetition rate of 4 kHz and an output power of 300 W, high stability of laser output energy (σ <= 0.7%) is achieved using an all-solid-state pump system.

  1. Fiber-laser-based, high-repetition-rate, picosecond ultraviolet source tunable across 329-348  nm.

    Science.gov (United States)

    Devi, Kavita; Chaitanya Kumar, S; Ebrahim-Zadeh, M

    2016-10-15

    We report a compact, fiber-laser-based, high-repetition-rate picosecond source for the ultraviolet (UV), providing multi-tens of milliwatt of average power across 329-348 nm. The source is based on internal sum-frequency-generation (SFG) in a singly resonant optical parametric oscillator (OPO), synchronously pumped at 532 nm by the second harmonic of a picosecond Yb-fiber laser at 80 MHz repetition rate. Using a 30-mm-long single-grating MgO:sPPLT crystal for the OPO and a 5-mm-long BiB3O6 crystal for intracavity SFG, we generate up to 115 mW of average UV power at 339.9 nm, with >50  mW over 73% of the tuning range, for 1.6 W of input pump power. The UV output exhibits a passive rms power stability of ∼2.9% rms over 1 min and 6.5% rms over 2 h in high beam quality. Angular acceptance bandwidth and cavity detuning effects have also been studied.

  2. Bright high-repetition-rate source of narrowband extreme-ultraviolet harmonics beyond 22 eV

    Energy Technology Data Exchange (ETDEWEB)

    Wang, He [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Xu, Yiming [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Ulonska, Stefan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Robinson, Joseph S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Ranitovic, Predrag [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Kaindl, Robert A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division

    2015-06-11

    Novel table-top sources of extreme-ultraviolet light based on high-harmonic generation yield unique insight into the fundamental properties of molecules, nanomaterials or correlated solids, and enable advanced applications in imaging or metrology. Extending high-harmonic generation to high repetition rates portends great experimental benefits, yet efficient extreme-ultraviolet conversion of correspondingly weak driving pulses is challenging. In this article, we demonstrate a highly-efficient source of femtosecond extreme-ultraviolet pulses at 50-kHz repetition rate, utilizing the ultraviolet second-harmonic focused tightly into Kr gas. In this cascaded scheme, a photon flux beyond ≈3 × 1013 s-1 is generated at 22.3 eV, with 5 × 10-5 conversion efficiency that surpasses similar harmonics directly driven by the fundamental by two orders-of-magnitude. The enhancement arises from both wavelength scaling of the atomic dipole and improved spatio-temporal phase matching, confirmed by simulations. Finally, spectral isolation of a single 72-meV-wide harmonic renders this bright, 50-kHz extreme-ultraviolet source a powerful tool for ultrafast photoemission, nanoscale imaging and other applications.

  3. Monolithic all-fiber repetition-rate tunable gain-switched single-frequency Yb-doped fiber laser.

    Science.gov (United States)

    Hou, Yubin; Zhang, Qian; Qi, Shuxian; Feng, Xian; Wang, Pu

    2016-12-12

    We report a monolithic gain-switched single-frequency Yb-doped fiber laser with widely tunable repetition rate. The single-frequency laser operation is realized by using an Yb-doped distributed Bragg reflection (DBR) fiber cavity, which is pumped by a commercial-available laser diode (LD) at 974 nm. The LD is electronically modulated by the driving current and the diode output contains both continuous wave (CW) and pulsed components. The CW component is set just below the threshold of the single-frequency fiber laser for reducing the requirement of the pump pulse energy. Above the threshold, the gain-switched oscillation is trigged by the pulsed component of the diode. Single-frequency pulsed laser output is achieved at 1.063 μm with a pulse duration of ~150 ns and a linewidth of 14 MHz. The repetition rate of the laser output can be tuned between 10 kHz and 400 kHz by tuning the electronic trigger signal. This kind of lasers shows potential for the applications in the area of coherent LIDAR etc.

  4. Filamentation effect in a gas attenuator for high-repetition-rate X-ray FELs

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Yiping; Krzywinski, Jacek; Schafer, Donald W.; Ortiz, Eliazar; Rowen, Michael; Raubenheimer, Tor O.

    2016-01-01

    A sustained filamentation or density depression phenomenon in an argon gas attenuator servicing a high-repetition femtosecond X-ray free-electron laser has been studied using a finite-difference method applied to the thermal diffusion equation for an ideal gas. A steady-state solution was obtained by assuming continuous-wave input of an equivalent time-averaged beam power and that the pressure of the entire gas volume has reached equilibrium. Both radial and axial temperature/density gradients were found and describable as filamentation or density depression previously reported for a femtosecond optical laser of similar attributes. The effect exhibits complex dependence on the input power, the desired attenuation, and the geometries of the beam and the attenuator. Time-dependent simulations were carried out to further elucidate the evolution of the temperature/density gradients in between pulses, from which the actual attenuation received by any given pulse can be properly calculated.

  5. Fluid dynamics analysis of a gas attenuator for X-ray FELs under high-repetition-rate operation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Bo; Wu, Juhao; Raubenheimer, Tor O.; Feng, Yiping

    2017-04-18

    Newtonian fluid dynamics simulations were performed using the Navier–Stokes–Fourier formulations to elucidate the short time-scale (µs and longer) evolution of the density and temperature distributions in an argon-gas-filled attenuator for an X-ray free-electron laser under high-repetition-rate operation. Both hydrodynamic motions of the gas molecules and thermal conductions were included in a finite-volume calculation. It was found that the hydrodynamic wave motions play the primary role in creating a density depression (also known as a filament) by advectively transporting gas particles away from the X-ray laser–gas interaction region, where large pressure and temperature gradients have been built upon the initial energy depositionviaX-ray photoelectric absorption and subsequent thermalization. Concurrent outward heat conduction tends to reduce the pressure in the filament core region, generating a counter gas flow to backfill the filament, but on an initially slower time scale. If the inter-pulse separation is sufficiently short so the filament cannot recover, the depth of the filament progressively increases as the trailing pulses remove additional gas particles. Since the rate of hydrodynamic removal decreases while the rate of heat conduction back flow increases as time elapses, the two competing mechanisms ultimately reach a dynamic balance, establishing a repeating pattern for each pulse cycle. By performing simulations at higher repetition rates but lower per pulse energies while maintaining a constant time-averaged power, the amplitude of the hydrodynamic motion per pulse becomes smaller, and the evolution of the temperature and density distributions approach asymptotically towards, as expected, those calculated for a continuous-wave input of the equivalent power.

  6. Silicon chip based wavelength conversion of ultra-high repetition rate data signals

    DEFF Research Database (Denmark)

    Hu, Hao; Ji, Hua; Galili, Michael

    2011-01-01

    We report on all-optical wavelength conversion of 160, 320 and 640 Gbit/s line-rate data signals using four-wave mixing in a 3.6 mm long silicon waveguide. Bit error rate measurements validate the performance within FEC limits.......We report on all-optical wavelength conversion of 160, 320 and 640 Gbit/s line-rate data signals using four-wave mixing in a 3.6 mm long silicon waveguide. Bit error rate measurements validate the performance within FEC limits....

  7. An experimental investigation on hydrogen fuel injection in intake port and manifold with different EGR rates

    Directory of Open Access Journals (Sweden)

    N.Saravanan, G.Nagarajan

    2010-03-01

    Full Text Available In the present investigation hydrogen was used in a diesel engine in the dual fuel mode using diesel as an ignition source. In order to have a precise control of hydrogen flow and to avoid the backfire and pre-ignition problems hydrogen was injected into the intake system. Experiments were conducted to determine the optimized injection timing, injection duration and injection quantity of the fuel in manifold and port injected hydrogen-operated engine using diesel as ignition source for hydrogen operation. From the results it was observed that in manifold injection technique the optimized condition was start of injection at gas exchange top dead centre (GTDC with injection duration of 30o crank angle (CA with hydrogen flow rate of 7.5 litres/min. In port injection technique, the optimized condition was start of injection at 5o before gas exchange top dead centre (5o BGTDC with injection duration of 30o CA with hydrogen flow rate of 7.5 litres/min. With the above optimized timings of port and manifold injection it was observed that brake thermal efficiency in port injection increases by 13 % and 16 % in manifold injection at 75 % load. However at full load the brake thermal efficiency decreases by 1 % in port injection and 8 % in manifold injection. A reduction in NOX emission by 4 times is observed in port injection and 7 times in manifold injection at full load. At 75 % load the NOX emission reduces by 3 times in both port injection and manifold injection. Smoke emission increases with increase in EGR percentage. The smoke increases by 36 % at full load in port injection and by 44 % in manifold injection. At 75 % load the smoke emission reduces by 13 % in port injection and 9 % in manifold injection. In both the port injection and manifold injection ignition delay was 12o or 1.33 ms while for diesel it was 11o or 1.22 ms. Port injection system with diesel as ignition source operates smoothly and shows improved performance and emit lesser

  8. High Repetition-Rate Wakefield Electron Source Generated by Few-millijoule, 30 femtosecond Laser Pulses on a Density Downramp

    CERN Document Server

    He, Z -H; Easter, J H; Krushelnick, K; Nees, J A; Thomas, A G R

    2012-01-01

    We report on an experimental demonstration of laser wakefield electron acceleration using a sub-TW power laser by tightly focusing 30-fs laser pulses with only 8 mJ pulse energy on a 100 \\mu m scale gas target. The experiments are carried out at an unprecedented 0.5 kHz repetition rate, allowing "real time" optimization of accelerator parameters. Well-collimated and stable electron beams with a quasi-monoenergetic peak in excess of 100 keV are measured. Particle-in-cell simulations show excellent agreement with the experimental results and suggest an acceleration mechanism based on electron trapping on the density downramp, due to the time varying phase velocity of the plasma waves.

  9. Octave-spanning spectrum of femtosecond Yb:fiber ring laser at 528 MHz repetition rate in microstructured tellurite fiber.

    Science.gov (United States)

    Wang, Guizhong; Jiang, Tongxiao; Li, Chen; Yang, Hongyu; Wang, Aimin; Zhang, Zhigang

    2013-02-25

    The octave-spanning spectrum was generated in a tellurite glass based microstructured fiber pumped by a 528 MHz repetition rate Yb:fiber ring laser without amplification. The laser achieved 40% output optical-to-optical efficiency with the output power of 410 mW. By adjusting the grating pair in the cavity, this oscillator can work at different cavity dispersion regimes with the shortest dechirped pulse width of 46 fs. The output pulses were then launched into a high-nonlinearity tellurite fiber, which has the zero-dispersion wavelength at ~1 μm. The high nonlinearity coefficient (1348 km⁻¹W⁻¹) and the matched zero-dispersion wavelength with pump laser enable the octave-spanning supercontinuum generated from 750 nm to 1700 nm with the coupled pulse energy above 10 pJ.

  10. Time-gated single-photon detection module with 110 ps transition time and up to 80 MHz repetition rate

    Energy Technology Data Exchange (ETDEWEB)

    Buttafava, Mauro, E-mail: mauro.buttafava@polimi.it; Boso, Gianluca; Ruggeri, Alessandro; Tosi, Alberto [Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Dalla Mora, Alberto [Politecnico di Milano, Dipartimento di Fisica, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy)

    2014-08-15

    We present the design and characterization of a complete single-photon counting module capable of time-gating a silicon single-photon avalanche diode with ON and OFF transition times down to 110 ps, at repetition rates up to 80 MHz. Thanks to this sharp temporal filtering of incoming photons, it is possible to reject undesired strong light pulses preceding (or following) the signal of interest, allowing to increase the dynamic range of optical acquisitions up to 7 decades. A complete experimental characterization of the module highlights its very flat temporal response, with a time resolution of the order of 30 ps. The instrument is fully user-configurable via a PC interface and can be easily integrated in any optical setup, thanks to its small and compact form factor.

  11. Development of a 16 kHz repetition rate, 110 W average power copper HyBrID laser

    Indian Academy of Sciences (India)

    R Biswal; P K Agrawal; G K Mishra; S V Nakhe; S K Dixit; J K Mittal

    2010-11-01

    This paper presents the design and performance analysis of an indigenously developed 110 W average output power copper HyBrID laser operating at 16 kHz pulse repetition rate. The laser active medium was confined within a fused silica tube of ∼ 6 cm diameter and ∼ 200 cm active length. An in-house developed high-power (∼ 10 kW) solid-state pulser was used as the electrical excitation source. A simple estimation of deposited electrical power, at the laser head, was carried out and based on it, the laser tube efficiency was found to be 2.9% at 70 W and 2.2% at 110 W laser power levels.

  12. Periodic disruptions induced by high repetition rate femtosecond pulses on magnesium-oxide-doped lithium niobate surfaces

    Science.gov (United States)

    Zhang, Shuanggen; Kan, Hongli; Zhai, Kaili; Ma, Xiurong; Luo, Yiming; Hu, Minglie; Wang, Qingyue

    2017-02-01

    In this paper, we demonstrate the periodic disruption formation on magnesium-oxide-doped lithium niobate surfaces by a femtosecond fiber laser system with wavelength and repetition rate of 1040 nm and 52 MHz, respectively. Three main experimental conditions, laser average power, scanning speed, and orientation of sample were systematically studied. In particular, the ablation morphologies of periodic disruptions under different crystal orientations were specifically researched. The result shows that such disruptions consisting of a bamboo-like inner structure appears periodically for focusing on the surface of X-, Y- and Z-cut wafers, which are formed by a rapid quenching of the material. Meanwhile, due to the anisotropic property, the bamboo-like inner structures consist of a cavity only arise from X- and Z-cut orientation.

  13. Ultrastable fiber amplifier delivering 145-fs pulses with 6-μJ energy at 10-MHz repetition rate.

    Science.gov (United States)

    Wunram, Marcel; Storz, Patrick; Brida, Daniele; Leitenstorfer, Alfred

    2015-03-01

    A high-power femtosecond Yb:fiber amplifier operating with exceptional noise performance and long-term stability is demonstrated. It generates a 10-MHz train of 145-fs pulses at 1.03 μm with peak powers above 36 MW. The system features a relative amplitude noise of 1.5·10⁻⁶  Hz(-1/2) at 1 MHz and drifts of the 60-W average power below 0.3% over 72 hours of continuous operation. The passively phase-stable Er:fiber seed system provides ultrabroadband pulses that are synchronized at a repetition rate of 40 MHz. This combination aims at new schemes for sensitive experiments in ultrafast scientific applications.

  14. The readout of the LHC beam luminosity monitor: accurate shower energy measurements at a 40 MHz repetition rate

    Energy Technology Data Exchange (ETDEWEB)

    Manfredi, P.F. E-mail: pfmanfredi@lbl.gov; Ratti, L.; Speziali, V.; Traversi, G.; Manghisoni, M.; Re, V.; Denes, P.; Placidi, M.; Ratti, A.; Turner, W.C.; Datte, P.S.; Millaud, J.E

    2004-02-01

    The LHC beam luminosity monitor is based on the following principle. The neutrals that originate in LHC at every PP interaction develop showers of minimum ionizing particles in the absorbers placed in front of the separation dipoles. The shower energy, measured by suitable detectors in the absorbers is proportional to the number of neutral particles and, therefore, to the luminosity. The principle lends itself to a luminosity measurement on a bunch-by-bunch basis. However, to make such a measurement feasible, the system must comply with extremely stringent requirements. Its speed of operation must match the 40 MHz bunch repetition rate of LHC. Besides, the detector must stand extremely high radiation doses. This paper discusses the solutions adopted to comply with these requirements.

  15. The readout of the LHC beam luminosity monitor Accurate shower energy measurements at a 40 MHz repetition rate

    CERN Document Server

    Manfredi, P F; Speziali, V; Traversi, G; Manghisoni, M; Re, V; Denes, P; Placidi, Massimo; Ratti, A; Turner, W C; Datte, P S; Millaud, J E

    2004-01-01

    The LHC beam luminosity monitor is based on the following principle. The neutrals that originate in LHC at every PP interaction develop showers of minimum ionizing particles in the absorbers placed in front of the separation dipoles. The shower energy, measured by suitable detectors in the absorbers is proportional to the number of neutral particles and, therefore, to the luminosity. The principle lends itself to a luminosity measurement on a bunch-by-bunch basis. However, to make such a measurement feasible, the system must comply with extremely stringent requirements. Its speed of operation must match the 40 MHz bunch repetition rate of LHC. Besides, the detector must stand extremely high radiation doses. This paper discusses the solutions adopted to comply with these requirements.

  16. Experimental and theoretical study of the laser micro-machining of glass using high-repetition-rate ultrafast laser

    Science.gov (United States)

    Yashkir, Yuri; Liu, Qiang

    2006-04-01

    We present a systematic study of the ultrafast laser micro-machining of glass using a Ti:Spp laser with moderate pulse energy (<5 μJ) at a high repetition rate (50 kHz). Optimal conditions were identified for high resolution surface laser etching, and via drilling. Several practical applications were developed: glass templates for micro fluid diffraction devices, phase gratings for excimer laser projection techniques, micro fluid vertical channel-connectors, etc. It is demonstrated that the interaction of ultrafast laser pulses with glass combines several different processes (direct ablation, explosive material ejection, and thermal material modification). A dynamic numerical model was developed for this process. It was successfully used for modelling of laser micro-machining with arbitrary 3D translations of the target.

  17. Does intrauterine injection of low-molecular-weight heparin improve the clinical pregnancy rate in intracytoplasmic sperm injection?

    Science.gov (United States)

    Kamel, Ahmed Mohamed; El-Faissal, Yahia; Aboulghar, Mona; Mansour, Ragaa; Serour, Gamal I; Aboulghar, Mohamed

    2016-12-01

    Heparin can modulate proteins, and influence processes involved in implantation and trophoblastic development. This study aimed to assess the improvement of clinical pregnancy and implantation rates after local intrauterine injection of low-molecular-weight heparin (LMWH) in patients undergoing intracytoplasmic sperm injection (ICSI). A randomised case/control design was followed in women scheduled for ICSI. The study arm was injected with intrauterine LMWH during mock embryo transfer immediately following the ovum pickup procedure, while the control arm was given an intrauterine injection with a similar volume of tissue culture media. Side effects, the clinical pregnancy rate, and the implantation rate were recorded. The pregnancy rate was acceptable (33.9%) in the LMWH arm with no significant reported side effects, confirming the safety of the intervention. No statistically significant differences were found in the clinical pregnancy and implantation rates between both groups (p=0.182 and p=0.096, respectively). The odds ratio of being pregnant after intrauterine injection with LMWH compared to the control group was 0.572 (95% confidence interval [CI], 0.27-1.22), while the risk ratio was 0.717 (95% CI, 0.46-1.13; p=0.146). No statistical significance was found between the two groups in other factors affecting implantation, such as day of transfer (p=0.726), number of embryos transferred (p=0.362), or embryo quality. Intrauterine injection of LMWH is a safe intervention, but the dose used in this study failed to improve the outcome of ICSI. Based on its safety, further research involving modification of the dosage and/or the timing of administration could result in improved ICSI success rates.

  18. Miniaturized two-stack Blumlein pulser with a variable repetition-rate for non-thermal irreversible-electroporation experiments

    Science.gov (United States)

    Min, Sun-Hong; Kwon, Ohjoon; Sattorov, Matlabjon; Baek, In-Keun; Kim, Seontae; Jeong, Jin-Young; Hong, Dongpyo; Park, Seunghyuk; Park, Gun-Sik

    2017-01-01

    Non-thermal irreversible electroporation (NTIRE) to avoid thermal damage to cells during intense DC ns pulsed electric fields (nsPEFs) is a recent modality for medical applications. This mechanism, related to bioelectrical dynamics of the cell, is linked to the effect of a DC electric field and a threshold effect with an electrically stimulated membrane for the charge distribution in the cell. To create the NTIRE condition, the pulse width of the nsPEF should be shorter than the charging time constant of the membrane related to the cell radius, membrane capacitance, cytoplasm resistivity, and medium resistivity. It is necessary to design and fabricate a very intense nanosecond DC electric field pulser that is capable of producing voltages up to the level of 100 kV/cm with an artificial pulse width (˜ns) with controllable repetition rates. Many devices to generate intense DC nsPEF using various pulse-forming line technologies have been introduced thus far. However, the previous Blumlein pulse-generating devices are clearly inefficient due to the energy loss between the input voltage and the output voltage. An improved two-stage stacked Blumlein pulse-forming line can overcome this limitation and decrease the energy loss from a DC power supply. A metal oxide silicon field-effect transistor switch with a fast rise and fall time would enable a high repetition rate (max. 100 kHz) and good endurance against very high voltages (DC ˜ 30 kV). The load is designed to match the sample for exposure to cell suspensions consisting of a 200 Ω resistor matched with a Blumlein circuit and two electrodes without the characteristic RC time effect of the circuit (capacitance =0.174 pF).

  19. Effect of laser annealing using high repetition rate pulsed laser on optical properties of phosphorus-ion-implanted ZnO nanorods

    Science.gov (United States)

    Shimogaki, Tetsuya; Ofuji, Taihei; Tetsuyama, Norihiro; Okazaki, Kota; Higashihata, Mitsuhiro; Nakamura, Daisuke; Ikenoue, Hiroshi; Asano, Tanemasa; Okada, Tatsuo

    2014-02-01

    The effect of high repetition rate pulsed laser annealing with a KrF excimer laser on the optical properties of phosphorus-ion-implanted zinc oxide nanorods has been investigated. The recovery levels of phosphorus-ion-implanted zinc oxide nanorods have been measured by photoluminescence spectra and cathode luminescence images. Cathode luminescence disappeared over 300 nm below the surface due to the damage caused by ion implantation with an acceleration voltage of 25 kV. When the annealing was performed at a low repetition rate of the KrF excimer laser, cathode luminescence was recovered only in a shallow area below the surface. The depth of the annealed area was increased along with the repetition rate of the annealing laser. By optimizing the annealing conditions such as the repetition rate, the irradiation fluence and so on, we have succeeded in annealing the whole damaged area of over 300 nm in depth and in observing cathode luminescence. Thus, the effectiveness of high repetition rate pulsed laser annealing on phosphorus-ion-implanted zinc oxide nanorods was demonstrated.

  20. A 600 VOLT MULTI-STAGE, HIGH REPETITION RATE GAN FET SWITCH

    Energy Technology Data Exchange (ETDEWEB)

    Frolov, D. [Fermilab; Pfeffer, H. [Fermilab; Saewert, G. [Fermilab

    2016-10-05

    Using recently available GaN FETs, a 600 Volt three- stage, multi-FET switch has been developed having 2 nanosecond rise time driving a 200 Ohm load with the potential of approaching 30 MHz average switching rates. Possible applications include driving particle beam choppers kicking bunch-by-bunch and beam deflectors where the rise time needs to be custom tailored. This paper reports on the engineering issues addressed, the design approach taken and some performance results of this switch.

  1. Femtosecond laser bone ablation with a high repetition rate fiber laser source.

    Science.gov (United States)

    Mortensen, Luke J; Alt, Clemens; Turcotte, Raphaël; Masek, Marissa; Liu, Tzu-Ming; Côté, Daniel C; Xu, Chris; Intini, Giuseppe; Lin, Charles P

    2015-01-01

    Femtosecond laser pulses can be used to perform very precise cutting of material, including biological samples from subcellular organelles to large areas of bone, through plasma-mediated ablation. The use of a kilohertz regenerative amplifier is usually needed to obtain the pulse energy required for ablation. This work investigates a 5 megahertz compact fiber laser for near-video rate imaging and ablation in bone. After optimization of ablation efficiency and reduction in autofluorescence, the system is demonstrated for the in vivo study of bone regeneration. Image-guided creation of a bone defect and longitudinal evaluation of cellular injury response in the defect provides insight into the bone regeneration process.

  2. Implementation of time-resolved step-scan fourier transform infrared (FT-IR) spectroscopy using a kHz repetition rate pump laser.

    Science.gov (United States)

    Magana, Donny; Parul, Dzmitry; Dyer, R Brian; Shreve, Andrew P

    2011-05-01

    Time-resolved step-scan Fourier transform infrared (FT-IR) spectroscopy has been shown to be invaluable for studying excited-state structures and dynamics in both biological and inorganic systems. Despite the established utility of this method, technical challenges continue to limit the data quality and more wide ranging applications. A critical problem has been the low laser repetition rate and interferometer stepping rate (both are typically 10 Hz) used for data acquisition. Here we demonstrate significant improvement in the quality of time-resolved spectra through the use of a kHz repetition rate laser to achieve kHz excitation and data collection rates while stepping the spectrometer at 200 Hz. We have studied the metal-to-ligand charge transfer excited state of Ru(bipyridine)(3)Cl(2) in deuterated acetonitrile to test and optimize high repetition rate data collection. Comparison of different interferometer stepping rates reveals an optimum rate of 200 Hz due to minimization of long-term baseline drift. With the improved collection efficiency and signal-to-noise ratio, better assignments of the MLCT excited-state bands can be made. Using optimized parameters, carbonmonoxy myoglobin in deuterated buffer is also studied by observing the infrared signatures of carbon monoxide photolysis upon excitation of the heme. We conclude from these studies that a substantial increase in performance of ss-FT-IR instrumentation is achieved by coupling commercial infrared benches with kHz repetition rate lasers.

  3. High-average-power 2 μm few-cycle optical parametric chirped pulse amplifier at 100 kHz repetition rate.

    Science.gov (United States)

    Shamir, Yariv; Rothhardt, Jan; Hädrich, Steffen; Demmler, Stefan; Tschernajew, Maxim; Limpert, Jens; Tünnermann, Andreas

    2015-12-01

    Sources of long wavelengths few-cycle high repetition rate pulses are becoming increasingly important for a plethora of applications, e.g., in high-field physics. Here, we report on the realization of a tunable optical parametric chirped pulse amplifier at 100 kHz repetition rate. At a central wavelength of 2 μm, the system delivered 33 fs pulses and a 6 W average power corresponding to 60 μJ pulse energy with gigawatt-level peak powers. Idler absorption and its crystal heating is experimentally investigated for a BBO. Strategies for further power scaling to several tens of watts of average power are discussed.

  4. Repetition-rate-selectable high-speed optical gating in a VO{sub 2} thin film based on gain modulation of optical amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yong Wook; Kim, Bong Jun; Choi, Sung Youl; Chae, Byung Gyu; Kim, Hyun Tak [Electronics and Telecommunications Research Institute, Daejeon (Korea, Republic of); Lee, Yong Wook [Pukyong National University, Busan (Korea, Republic of); Seo, Gi Wan [University of Science and Technology, Daejeon (Korea, Republic of); Lee, Yong Wan [University of Minnesota, Minneapolis, MN (United States)

    2010-12-15

    In this research, we investigated the dependence of the saturation-induced gain modulation (SIGM) on the modulation frequency of the input signal in an erbium-doped fiber amplifier (EDFA). By finding and incorporating the modulation frequency invariance of the SIGM realizable within some frequency range, we demonstrated a repetition-rate-selectable high-speed optical gating in two-terminal electrical devices based on vanadium-dioxide thin films. In the implemented optical gating system, the repetition rate could be freely chosen as an arbitrary frequency between 0.27 and 10 kHz without any degradation of the gating speed and the signal-to-noise ratio.

  5. Strong modulation of ectopic focus as a mechanism of repetitive interpolated ventricular bigeminy with heart rate doubling.

    Science.gov (United States)

    Takayanagi, Kan; Nakahara, Shiro; Toratani, Noritaka; Chida, Ryuji; Kobayashi, Sayuki; Sakai, Yoshihiko; Takeuchi, Akihiro; Ikeda, Noriaki

    2013-10-01

    Repetitive interpolated ventricular bigeminy (RIVB) can introduce a doubling of the ventricular rate. To clarify the mechanism of RIVB, we hypothesized that it was introduced by a strong modulation of the ventricular automatic focus. RIVB, defined as more than 7 bigeminy events, was detected by instantaneous heart rate and bigeminy interval (BI) tachograms in 1450 successive patients with frequent ventricular premature contractions (≥3000 per day). Postextrasystolic interval bigeminy interval curves were plotted to determine the degree of modulation. Mean sinus cycle length bigeminy interval curves were plotted for selection. RIVB was simulated by using a computer-based parasystole model. RIVB was observed in 7 patients (age 60 ± 16 years; 2 men and 5 women) with a heart rate of 58.2 ± 6.5 beats/min during a rest period both during the day and at night. The tachograms disclosed the onset of the RIVB with a doubled ventricular rate to 112.3 ± 8.5 beats/min. On the postextrasystolic interval bigeminy interval curves, compensatory bigeminy and interpolated bigeminy constituted overlapping regression lines with slopes close to 1.00 and RIVB was located in the lower left portion. RIVB lasting for up to 3 hours was quickly detected by mean sinus cycle length bigeminy interval curve. The PQ interval immediately after RIVB was prolonged in comparison with baseline (0.18 ± 0.02 to 0.21 ± 0.02 seconds; P heart rate. Our findings support the hypothesis that RIVB was introduced by strongly modulated ventricular pacemaker accelerated by an intervening normal QRS. © 2013 Heart Rhythm Society. All rights reserved.

  6. Tralokinumab pharmacokinetics and tolerability when administered by different subcutaneous injection methods and rates

    Science.gov (United States)

    Jain, Meena; Doughty, Diane; Clawson, Corbin; Li, Xiaobai; White, Nicholas; Agoram, Balaji; van der Merwe, René

    2017-01-01

    Objective: Tralokinumab, administered as two 1-mL subcutaneous injections every 2 weeks, at the target dose 300 mg, has been shown to improve lung function in patients with asthma. This study evaluated the pharmacokinetic (PK) and tolerability profile of tralokinumab 300 mg when administered by different rates of subcutaneous injection, as part of a pilot investigation of new injection regimens. Methods: This phase I study randomized 60 healthy adults to receive 300 mg tralokinumab, as two 1-mL subcutaneous injections, each delivered over 10 seconds, or one 2-mL injection delivered over 10 seconds (12 mL/min), 1 minute (2 mL/min), or 12 minutes (0.167 mL/min). Results: No differences in the PK profile of tralokinumab were observed between cohorts. Immediately following injection, injection-site pain intensity (mean (SD)) was lowest following 0.167 mL/min injection (5.1 mm (8.0) via visual analog scale (VAS)) and greatest following 12 mL/min injection (41 mm (27.7) via VAS); with mean injection-site pruritus intensity low for all participants. Two types of local injection-site reactions were observed: erythema (58.3%) and hematoma/bleeding (18.3%). All treatment-emergent adverse events were mild. Conclusions: Tralokinumab 300 mg is well tolerated, with comparable PK, when administered by a single 2-mL injection at different rates of subcutaneous injection vs. two 1-mL injections. PMID:28590244

  7. 500 MW peak power degenerated optical parametric amplifier delivering 52 fs pulses at 97 kHz repetition rate.

    Science.gov (United States)

    Rothhardt, J; Hädrich, S; Röser, F; Limpert, J; Tünnermann, A

    2008-06-09

    We present a high peak power degenerated parametric amplifier operating at 1030 nm and 97 kHz repetition rate. Pulses of a state-of-the art fiber chirped-pulse amplification (FCPA) system with 840 fs pulse duration and 410 microJ pulse energy are used as pump and seed source for a two stage optical parametric amplifier. Additional spectral broadening of the seed signal in a photonic crystal fiber creates enough bandwidth for ultrashort pulse generation. Subsequent amplification of the broadband seed signal in two 1 mm BBO crystals results in 41 microJ output pulse energy. Compression in a SF 11 prism compressor yields 37 microJ pulses as short as 52 fs. Thus, pulse shortening of more than one order of magnitude is achieved. Further scaling in terms of average power and pulse energy seems possible and will be discussed, since both concepts involved, the fiber laser and the parametric amplifier have the reputation to be immune against thermo-optical effects.

  8. Synthesis, characterization and evaluation of CO-oxidation catalysts for high repetition rate CO2 TEA lasers

    Science.gov (United States)

    Moser, Thomas P.

    1990-06-01

    An extremely active class of noble metal catalysts supported on titania was developed and fabricated at Hughes for the recombination of oxygen (O2) and carbon monoxide (CO) in closed-cycle CO2 TEA lasers. The incipient wetness technique was used to impregnate titania and alumina pellets with precious metals including platinum and palladium. In particular, the addition of cerium (used as an oxygen storage promoter) produced an extremely active Pt/Ce/TiO2 catalyst. By comparison, the complementary Pt/Ce/ gamma-Al2O3 catalyst was considerably less active. In general, chloride-free catalyst precursors proved critical in obtaining an active catalyst while also providing uniform metal distributions throughout the support structure. Detailed characterization of the Pt/Ce/TiO2 catalyst demonstrated uniform dendritic crystal growth of the metals throughout the support. Electron spectroscopy for Chemical Analysis (ESCA) analysis was used to characterize the oxidation states of Pt, Ce and Ti. The performance of the catalysts was evaluated with an integral flow reactor system incorporating real time analysis of O2 and CO. With this system, the transient and steady-state behavior of the catalysts were evaluated. The kinetic evaluation was complemented by tests in a compact, closed-cycle Hughes CO2 TEA laser operating at a pulse repetition rate of 100 Hz with a catalyst temperature of 75 to 95 C. The Pt/Ce/TiO2 catalyst was compatible with a C(13)O(16)2 gas fill.

  9. Low-repetition rate femtosecond laser writing of optical waveguides in KTP crystals: analysis of anisotropic refractive index changes.

    Science.gov (United States)

    Butt, Muhammad Ali; Nguyen, Huu-Dat; Ródenas, Airán; Romero, Carolina; Moreno, Pablo; Vázquez de Aldana, Javier R; Aguiló, Magdalena; Solé, Rosa Maria; Pujol, Maria Cinta; Díaz, Francesc

    2015-06-15

    We report on the direct low-repetition rate femtosecond pulse laser microfabrication of optical waveguides in KTP crystals and the characterization of refractive index changes after the thermal annealing of the sample, with the focus on studying the potential for direct laser fabricating Mach-Zehnder optical modulators. We have fabricated square cladding waveguides by means of stacking damage tracks, and found that the refractive index decrease is large for vertically polarized light (c-axis; TM polarized) but rather weak for horizontally polarized light (a-axis; TE polarized), this leading to good near-infrared light confinement for TM modes but poor for TE modes. However, after performing a sample thermal annealing we have found that the thermal process enables a refractive index increment of around 1.5x10(-3) for TE polarized light, while maintaining the negative index change of around -1x10(-2) for TM polarized light. In order to evaluate the local refractive index changes we have followed a multistep procedure: We have first characterized the waveguide cross-sections by means of Raman micro-mapping to access the lattice micro-modifications and their spatial extent. Secondly we have modeled the waveguides following the modified region sizes obtained by micro-Raman with finite element method software to obtain a best match between the experimental propagation modes and the simulated ones. Furthermore we also report the fabrication of Mach-Zehnder structures and the evaluation of propagation losses.

  10. Intense high repetition rate Mo Kα x-ray source generated from laser solid interaction for imaging application

    Energy Technology Data Exchange (ETDEWEB)

    Huang, K.; Li, M. H.; Yan, W. C.; Ma, Y.; Zhao, J. R.; Li, Y. F.; Chen, L. M., E-mail: lmchen@iphy.ac.cn [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100190 (China); Guo, X. [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100190 (China); Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); School of Optoelectronics, Beijing Institute of Technology, Beijing 100081 (China); Li, D. Z. [Institute of High Energy Physics, CAS, Beijing 100049 (China); Chen, Y. P.; Zhang, J. [Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2014-11-15

    We report an efficient Mo Kα x-ray source produced by interaction of femtosecond Ti: sapphire laser pulses with a solid Molybdenum target working at 1 kHz repetition rate. The generated Mo Kα x-ray intensity reaches to 4.7 × 10{sup 10} photons sr{sup −1} s{sup −1}, corresponding to an average power of 0.8 mW into 2π solid angle. The spatial resolution of this x-ray source is measured to be 26 lp/mm. With the high flux and high spatial resolution characteristics, high resolving in-line x-ray radiography was realized on test objects and large size biological samples within merely half a minute. This experiment shows the possibility of laser plasma hard x-ray source as a new low cost and high resolution system for radiography and its ability of ultrafast x-ray pump-probe study of matter.

  11. Vernier effect within a versatile femtosecond optical parametric oscillator for broad-tunable, high-repetition-rate oscillator

    CERN Document Server

    Jin, Yuwei; Harren, Frans J M; Mandon, Julien

    2015-01-01

    Within a synchronously pumped optical parametric oscillator (SPOPO), the inherent synchronism between the pump and the resonating signal is the magic to partly transfer the coherence property of the pump to the signal. In our demonstration, Vernier effect is observed within a femtosecond SPOPO by simply detuning the FSR of the cavity, generating signal pulses at tunable repetition rate from several GHz to 1 THz with a maximum 22.58 nm full width half maximum (FWHM) bandwidth supporting 160 fs pulses covering the C- and L-bands of the telecom wavelength region. This technique offers a simple method of active ?filtering of dense frequency comb lines instead of using Fabry-P?erot (FP) cavities with complex locking system for astro-comb generation. Beside, as a promising source for frequency combs with tunable and large comb-spacing, it offers potential opportunities for applications such as high speed coherent data transmission, line-by-line pulse shaping, optical clocks and precision metrology.

  12. In-situ, variable thickness, liquid crystal film target formation at moderate repetition rate for intense laser applications

    CERN Document Server

    Poole, P L; Cochran, G E; Hanna, R J; Andereck, C D; Schumacher, D W

    2015-01-01

    Liquid crystal films have recently been demonstrated as variable thickness, planar targets for ultra-intense laser matter experiments and applications such as ion acceleration. By controlling the parameters of film formation, including liquid crystal temperature and volume, their thickness can be varied on-demand from 10 $nm$ to above 10 $\\mu m$. This thickness range enables for the first time real-time selection and optimization of various ion acceleration mechanisms using low cost, high quality targets. Our previous work employed these targets in single shot configuration, requiring chamber cycling after the pre-made films were expended. Presented here is a film formation device capable of drawing films from a bulk liquid crystal source volume to any thickness in the aforementioned range. This device will form films under vacuum within 2 $\\mu m$ of the same location each time, well within the Rayleigh range of even tight $F/ \\#$ systems. The repetition rate of the device exceeds 0.1 $Hz$ for sub-100 $nm$ fi...

  13. Low-timing-jitter, stretched-pulse passively mode-locked fiber laser with tunable repetition rate and high operation stability

    Science.gov (United States)

    Liu, Yuanshan; Zhang, Jian-Guo; Chen, Guofu; Zhao, Wei; Bai, Jing

    2010-09-01

    We design a low-timing-jitter, repetition-rate-tunable, stretched-pulse passively mode-locked fiber laser by using a nonlinear amplifying loop mirror (NALM), a semiconductor saturable absorber mirror (SESAM), and a tunable optical delay line in the laser configuration. Low-timing-jitter optical pulses are stably produced when a SESAM and a 0.16 m dispersion compensation fiber are employed in the laser cavity. By inserting a tunable optical delay line between NALM and SESAM, the variable repetition-rate operation of a self-starting, passively mode-locked fiber laser is successfully demonstrated over a range from 49.65 to 50.47 MHz. The experimental results show that the newly designed fiber laser can maintain the mode locking at the pumping power of 160 mW to stably generate periodic optical pulses with width less than 170 fs and timing jitter lower than 75 fs in the 1.55 µm wavelength region, when the fundamental repetition rate of the laser is continuously tuned between 49.65 and 50.47 MHz. Moreover, this fiber laser has a feature of turn-key operation with high repeatability of its fundamental repetition rate in practice.

  14. Phase-stable, multi-µJ femtosecond pulses from a repetition-rate tunable Ti:Sa-oscillator-seeded Yb-fiber amplifier

    Science.gov (United States)

    Saule, T.; Holzberger, S.; De Vries, O.; Plötner, M.; Limpert, J.; Tünnermann, A.; Pupeza, I.

    2017-01-01

    We present a high-power, MHz-repetition-rate, phase-stable femtosecond laser system based on a phase-stabilized Ti:Sa oscillator and a multi-stage Yb-fiber chirped-pulse power amplifier. A 10-nm band around 1030 nm is split from the 7-fs oscillator output and serves as the seed for subsequent amplification by 54 dB to 80 W of average power. The µJ-level output is spectrally broadened in a solid-core fiber and compressed to 30 fs with chirped mirrors. A pulse picker prior to power amplification allows for decreasing the repetition rate from 74 MHz by a factor of up to 4 without affecting the pulse parameters. To compensate for phase jitter added by the amplifier to the feed-forward phase-stabilized seeding pulses, a self-referencing feed-back loop is implemented at the system output. An integrated out-of-loop phase noise of less than 100 mrad was measured in the band from 0.4 Hz to 400 kHz, which to the best of our knowledge corresponds to the highest phase stability ever demonstrated for high-power, multi-MHz-repetition-rate ultrafast lasers. This system will enable experiments in attosecond physics at unprecedented repetition rates, it offers ideal prerequisites for the generation and field-resolved electro-optical sampling of high-power, broadband infrared pulses, and it is suitable for phase-stable white light generation.

  15. Sub-picosecond Graphene-based Harmonically Mode-Locked Fiber Laser With Repetition Rates up to 2.22 GHz

    Directory of Open Access Journals (Sweden)

    Abramski K.M.

    2013-03-01

    Full Text Available Passive harmonic-mode locking (PHML of erbium-doped fiber laser with multilayer graphene is presented. The laser could operate at several harmonics (from 2nd to 21st of the fundamental repetition frequency of the ring resonator (106 MHz. The highest achieved repetition rate was 2.22 GHz (which corresponds to the 21st harmonic with 900 fs pulse duration and 50 dB of the supermode noise suppression. The saturable absorber was formed by multilayer graphene, mechanically exfoliated from pure graphite block through Scotch-tape and deposited on the fiber ferrule.

  16. Effect of injection rate on contrast-enhanced MR angiography image quality: Modulation transfer function analysis.

    Science.gov (United States)

    Clark, Toshimasa J; Wilson, Gregory J; Maki, Jeffrey H

    2017-07-01

    Contrast-enhanced (CE)-MRA optimization involves interactions of sequence duration, bolus timing, contrast recirculation, and both R1 relaxivity and R2*-related reduction of signal. Prior data suggest superior image quality with slower gadolinium injection rates than typically used. A computer-based model of CE-MRA was developed, with contrast injection, physiologic, and image acquisition parameters varied over a wide gamut. Gadolinium concentration was derived using Verhoeven's model with recirculation, R1 and R2* calculated at each time point, and modulation transfer curves used to determine injection rates, resulting in optimal resolution and image contrast for renal and carotid artery CE-MRA. Validation was via a vessel stenosis phantom and example patients who underwent carotid CE-MRA with low effective injection rates. Optimal resolution for renal and carotid CE-MRA is achieved with injection rates between 0.5 to 0.9 mL/s and 0.2 to 0.3 mL/s, respectively, dependent on contrast volume. Optimal image contrast requires slightly faster injection rates. Expected signal-to-noise ratio varies with both contrast volume and cardiac output. Simulated vessel phantom and clinical carotid CE-MRA exams at an effective contrast injection rate of 0.4 to 0.5 mL/s demonstrate increased resolution. Optimal image resolution is achieved at intuitively low, effective injection rates (0.2-0.9 mL/s, dependent on imaging parameters and contrast injection volume). Magn Reson Med 78:357-369, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  17. Rate of Post-traumatic Endophthalmitis with or without Injection of Balanced Salt Solution

    Directory of Open Access Journals (Sweden)

    Nasrin Rafati

    2013-01-01

    Full Text Available Purpose: In a study complementing a previous multicenter randomized clinical trial on prophylactic injection of intraocular antibiotics during primary repair of penetrating eye injuries (PEIs, we sought to determine whether needle entrance and injection of balanced salt solution (BSS, per se, could increase the rate of acute post-traumatic bacterial endophthalmitis (APBE. Methods: Patients randomized to the BSS injection arm (n=167 of the Traumatic Endophthalmitis Trial, and eligible patients who had refused enrollment and received no intraocular injections during primary repair (n=111 were compared for the development of APBE. Results: APBE occurred in 8 of 167 (4.8% eyes in the BSS group and in 5 of 111 (4.5% eyes in the non-injection group (P=0.91. Retained intraocular foreign bodies were present in 46 eyes including 25 (15% eyes in the BSS injection group and 21 (18.9% eyes in the non-injection group (P=0.38. Logistic regression analysis showed no significant difference between BSS injected and non-injected eyes in terms of APBE (P=0.69. However, the presence of intraocular foreign bodies was strongly associated with the risk of endophthalmitis (P<0.001, OR=14.1, 95% CI: 4.1-48.5. Conclusion: Needle entrance and intraocular injection of BSS during primary repair of PEIs does not increase the risk of APBE.

  18. Effect of sodium injection rate in reduction process on characteristics of tantalum powders

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The paper presents a research the effect of sodium injection rate in a melt containing potassium tantalum fluoride and a flux on morphology and characteristics of tantalum powders obtained by sodium reduction.

  19. High-repetition-rate compact excimer laser: UV light source for metrology, inspection, direct writing, and material testing

    Science.gov (United States)

    Huber, Heinz P.; Pflanz, Tobias; Goertler, Andreas; Schillinger, Helmut

    2003-06-01

    The discharge pumped excimer laser is a gas laser providing ultra violet (UV) radiation with well defined spectral, temporal and spatial properties. The fast development of excimer lasers in recent years has succeeded in designing very compact, table-top and turn-key systems delivering up to 20 W of radiation at 248 nm, 10 W at 193 nm and 2 W at 157 nm with repetition rates up to 2000 Hz (1, 5). Due to their short emission wavelength and compactness they are continuously replacing other light sources, like lamps and ion lasers, in applications as metrology, inspection, direct writing and material testing. Spatial and temporal beam properties of compact excimer lasers are very suitable to be utilized as illumination source in these applications. The compact excimer laser is combining the advantages of both, lamp and laser sources. It displays low temporal and spatial coherence, but has a narrow spectral emission range of a few hundred pm. The beam area is approximately 1/2 cm2, the divergence is in the order of 1 mrad. Variation of beam position and beam direction are negligible for most illumination applications. Compact excimer lasers are easy to integrate in measurement and inspection systems. Typically their footprint area is 0.25 m2. The power consumption is less than 1 kW, enabling single phase electrical supply and air cooling. State-of-the-art compact excimer lasers are compliant to all relevant SEMI regulations. The laser optics exceeds the life time of the laser tube, thus no optics cleaning and exchange is necessary in a whole life time of a laser tube of a few billion pulses (6).

  20. Confirmation of gravitationally induced attitude drift of spinning satellite Ajisai with Graz high repetition rate SLR data

    Science.gov (United States)

    Kucharski, Daniel; Kirchner, Georg; Otsubo, Toshimichi; Lim, Hyung-Chul; Bennett, James; Koidl, Franz; Kim, Young-Rok; Hwang, Joo-Yeon

    2016-02-01

    The high repetition rate Satellite Laser Ranging system Graz delivers the millimeter precision range measurements to the corner cube reflector panels of Ajisai. The analysis of 4599 passes measured from October 2003 until November 2014 reveals the secular precession and nutation of Ajisai spin axis due to the gravitational forces as predicted by Kubo (1987) with the periods of 35.6 years and 116.5 days respectively. The observed precession cone is oriented at RA = 88.9°, Dec = -88.85° (J2000) and has a radius of 1.08°. The radius of the nutation cone increases from 1.32° to 1.57° over the 11 years of the measurements. We also detect a draconitic wobbling of Ajisai orientation due to the 'motion' of the Sun about the satellite's orbit. The observed spin period of Ajisai increases exponentially over the investigated time span according to the trend function: T = 1.492277·exp(0.0148388·Y) [s], where Y is in years since launch (1986.6133), RMS = 0.412 ms. The physical simulation model fitted to the observed spin parameters proves a very low interaction between Ajisai and the Earth's magnetic field, what assures that the satellite's angular momentum vector will remain in the vicinity of the south celestial pole for the coming decades. The developed empirical model of the spin axis orientation can improve the accuracy of the range determination between the ground SLR systems and the satellite's center-of-mass (Kucharski et al., 2015) and enable the accurate attitude prediction of Ajisai for the laser time-transfer experiments (Kunimori et al., 1992).

  1. 10  GHz pulse repetition rate Er:Yb:glass laser modelocked with quantum dot semiconductor saturable absorber mirror.

    Science.gov (United States)

    Resan, B; Kurmulis, S; Zhang, Z Y; Oehler, A E H; Markovic, V; Mangold, M; Südmeyer, T; Keller, U; Hogg, R A; Weingarten, K J

    2016-05-10

    Semiconductor saturable absorber mirror (SESAM) modelocked high pulse repetition rate (≥10  GHz) diode-pumped solid-state lasers are proven as an enabling technology for high data rate coherent communication systems owing to their low noise and high pulse-to-pulse optical phase-coherence. Compared to quantum well, quantum dot (QD)-based SESAMs offer potential advantages to such laser systems in terms of reduced saturation fluence, broader bandwidth, and wavelength flexibility. Here, we describe the first 10 GHz pulse repetition rate QD-SESAM modelocked laser at 1.55 μm, exhibiting 2 ps pulse width from an Er-doped glass oscillator (ERGO). The 10 GHz ERGO laser is modelocked with InAs/GaAs QD-SESAM with saturation fluence as low as 9  μJ/cm2.

  2. Derivation of a formula describing the saturation correction of plane-parallel ionization chambers in pulsed fields with arbitrary repetition rate.

    Science.gov (United States)

    Karsch, Leonhard

    2016-04-21

    Gas-filled ionization chambers are widely used radiation detectors in radiotherapy. A quantitative description and correction of the recombination effects exists for two cases, for continuous radiation exposure and for pulsed radiation fields with short single pulses. This work gives a derivation of a formula for pulsed beams with arbitrary pulse rate for which the prerequisites of the two existing descriptions are not fulfilled. Furthermore, an extension of the validity of the two known cases is investigated. The temporal evolution of idealized charge density distributions within a plane parallel chamber volume is described for pulsed beams of vanishing pulse duration and arbitrary pulse repetition rate. First, the radiation induced release, movement and collection of the charge carriers without recombination are considered. Then, charge recombination is calculated basing on these simplified charge distributions and the time dependent spatial overlap of positive and negative charge carrier distributions. Finally, a formula for the calculation of the saturation correction factor is derived by calculation and simplification of the first two terms of a Taylor expansion for small recombination. The new formula of saturation correction contains the two existing cases, descriptions for exposure by single pulses and continuous irradiation, as limiting cases. Furthermore, it is possible to determine the pulse rate range for which each of the three descriptions is applicable by comparing the dependencies of the new formula with the two existing cases. As long as the time between two pulses is lower than one third of the collection time of the chamber, the formalism for a continuous exposure can be used. The known description for single pulse irradiation is only valid if the repetition rate is less than 1.2 times the inverse collection time. For all other repetition rates in between the new formula should be used. The experimental determination by Jaffe diagrams can be

  3. Derivation of a formula describing the saturation correction of plane-parallel ionization chambers in pulsed fields with arbitrary repetition rate

    Science.gov (United States)

    Karsch, Leonhard

    2016-04-01

    Gas-filled ionization chambers are widely used radiation detectors in radiotherapy. A quantitative description and correction of the recombination effects exists for two cases, for continuous radiation exposure and for pulsed radiation fields with short single pulses. This work gives a derivation of a formula for pulsed beams with arbitrary pulse rate for which the prerequisites of the two existing descriptions are not fulfilled. Furthermore, an extension of the validity of the two known cases is investigated. The temporal evolution of idealized charge density distributions within a plane parallel chamber volume is described for pulsed beams of vanishing pulse duration and arbitrary pulse repetition rate. First, the radiation induced release, movement and collection of the charge carriers without recombination are considered. Then, charge recombination is calculated basing on these simplified charge distributions and the time dependent spatial overlap of positive and negative charge carrier distributions. Finally, a formula for the calculation of the saturation correction factor is derived by calculation and simplification of the first two terms of a Taylor expansion for small recombination. The new formula of saturation correction contains the two existing cases, descriptions for exposure by single pulses and continuous irradiation, as limiting cases. Furthermore, it is possible to determine the pulse rate range for which each of the three descriptions is applicable by comparing the dependencies of the new formula with the two existing cases. As long as the time between two pulses is lower than one third of the collection time of the chamber, the formalism for a continuous exposure can be used. The known description for single pulse irradiation is only valid if the repetition rate is less than 1.2 times the inverse collection time. For all other repetition rates in between the new formula should be used. The experimental determination by Jaffe diagrams can be

  4. Influences of Injection Barrier and Mobility on Recombination Rate and Zone in OLEDs

    Institute of Scientific and Technical Information of China (English)

    ZHU Ru-hui; LI Hong-jian; YAN Ling-ling; HU Jin; PAN Yan-zhi

    2006-01-01

    The luminous efficiency of organic light-emitting devices depends on the recombination probability of electrons injected at the cathode and holes at the anode. A theoretical model to calculate the distribution of current densities and the recombination rate in organic single layer devices is presented taking into account the charge injection process at each electrode, charge transport and recombination in organic layer. The calculated results indicate that efficient single-layer devices are possible by adjusting the barrier heights at two electrodes and the carrier mobilities. Lowering the barrier heights can improve the electroluminescent(EL) efficiency pronouncedly in many cases, and efficient devices are still possible using an ohmic contact to inject the low mobility carrier, and a contact limited contact to inject the high mobility carrier. All in all, high EL efficiency needs to consider sufficient recombination, enough injected carriers and well transport.

  5. REDUCING THE REJECTION RATE OF ENGINES MANUFACTURING DUE TO INJECTION TIMING VARIATION

    Directory of Open Access Journals (Sweden)

    Mrs. P.SIVASHANKARI

    2015-12-01

    Full Text Available The white paper is on HINO 6 cylinder engine and the aim is to reduce the rejection rate of engines during testing due to the problems occur in valve timing and injection timing. The concept of Six Sigma is mainly practiced as a design to eliminate the production defects by improving the process of manufacturing. In the observation, the injection timing mark (spill mark is not perfectly done and also the imperfection in flywheel marking machine locator pin increases engine rejection. The aim is to eliminate the engines getting rejected during engine test due to problems arising in the injection timing and valve timing. As there are a lot of problems arising in the test bed where the engine is tested, few of which are related to injection timing and valve timing. These problems mainly arise due to changes in the valve and injection timing variation.

  6. Oral-Diadochokinetic Rates for Hebrew-Speaking Healthy Ageing Population: Non-Word versus Real-Word Repetition

    Science.gov (United States)

    Ben-David, Boaz M.; Icht, Michal

    2017-01-01

    Background: Oral-diadochokinesis (oral-DDK) tasks are extensively used in the evaluation of motor speech abilities. Currently, validated normative data for older adults (aged 65 years and older) are missing in Hebrew. The effect of task stimuli (non-word versus real-word repetition) is also non-clear in the population of older adult Hebrew…

  7. LOW ENDOPHTHALMITIS RATES AFTER INTRAVITREAL ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR INJECTIONS IN AN OPERATION ROOM

    DEFF Research Database (Denmark)

    Freiberg, Florentina J; Brynskov, Troels; Munk, Marion R

    2017-01-01

    PURPOSE: To evaluate the rate of presumed endophthalmitis (EO) after intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections in three European hospitals performed in an operation room (OR) under sterile conditions. METHODS: A retrospective multicenter study between 2003 and 2016...... at three European sites, City Hospital Triemli Zurich, Switzerland (CHT), Zealand University Hospital Roskilde, Denmark (ZUH) and University Clinic Bern, Switzerland (UCB). Intravitreal injection (IVI) database of each department was reviewed. All anti-vascular endothelial growth factor injections were.......0074% per injection (95% CI: 0.0070-0.0078%). Positive cultures were found in 4 out of 10 presumed endophthalmitis cases. CONCLUSION: The standardized sterile technique in an operation room with laminar airflow showed very low rates of endophthalmitis at three European sites....

  8. Optimizing stimulus repetition rate for recording ocular vestibular evoked myogenic potential elicited by air-conduction tone bursts of 500 Hz

    Directory of Open Access Journals (Sweden)

    Niraj Kumar Singh

    2014-03-01

    Full Text Available Amidst several publications reporting the effects of stimulus-related parameters on ocular vestibular evoked myogenic potential (oVEMP, the effect of the repetition rate on oVEMP responses has largely gone unexplored. Studies have used a repetition rate of ~5.1 Hz mainly due to a presumption that oVEMP, like cervical VEMP, should produce best responses for ~5 Hz, although there is paucity of experimental evidence to support this hypothesis. 52 healthy individuals in the age range of 17-35 years underwent air-conduction oVEMP elicited by 500 Hz tone-bursts using seven different repetition rates (3.1, 5.1, 10.1, 15.1, 20.1, 25.1 and 30.1 Hz. The results revealed a tendency for prolongation of latencies and reduction in amplitude with increasing repetition rate. However, significantly longer latencies were observed only for 20.1 Hz and larger amplitudes for 3.1 and 5.1 Hz (P<0.05. There was no significant difference between the rates of 3.1 Hz and 5.1 Hz. However 3.1 Hz produced poorer signal-to-noise ratio and required considerably longer time and thereby had lesser efficiency than 5.1 Hz (P<0.05. This would also result in higher fatigue and irritation levels considering the physical act of maintaining a supero-medial gaze. Thus the use of 5.1 Hz is recommended for clinical recording of oVEMP.

  9. Optimizing Stimulus Repetition Rate for Recording Ocular Vestibular Evoked Myogenic Potential Elicited by Air-Conduction Tone Bursts of 500 Hz.

    Science.gov (United States)

    Singh, Niraj Kumar; Kadisonga, Peter; Ashitha, Palliyath

    2014-03-06

    Amidst several publications reporting the effects of stimulus-related parameters on ocular vestibular evoked myogenic potential (oVEMP), the effect of the repetition rate on oVEMP responses has largely gone unexplored. Studies have used a repetition rate of ~5.1 Hz mainly due to a presumption that oVEMP, like cervical VEMP, should produce best responses for ~5 Hz, although there is paucity of experimental evidence to support this hypothesis. 52 healthy individuals in the age range of 17-35 years underwent air-conduction oVEMP elicited by 500 Hz tone-bursts using seven different repetition rates (3.1, 5.1, 10.1, 15.1, 20.1, 25.1 and 30.1 Hz). The results revealed a tendency for prolongation of latencies and reduction in amplitude with increasing repetition rate. However, significantly longer latencies were observed only for 20.1 Hz and larger amplitudes for 3.1 and 5.1 Hz (P<0.05). There was no significant difference between the rates of 3.1 Hz and 5.1 Hz. However 3.1 Hz produced poorer signal-to-noise ratio and required considerably longer time and thereby had lesser efficiency than 5.1 Hz (P<0.05). This would also result in higher fatigue and irritation levels considering the physical act of maintaining a supero-medial gaze. Thus the use of 5.1 Hz is recommended for clinical recording of oVEMP.

  10. Disturbance and recovery of trunk mechanical and neuromuscular behaviours following repetitive lifting: influences of flexion angle and lift rate on creep-induced effects.

    Science.gov (United States)

    Toosizadeh, Nima; Bazrgari, Babak; Hendershot, Brad; Muslim, Khoirul; Nussbaum, Maury A; Madigan, Michael L

    2013-01-01

    Repetitive lifting is associated with an increased risk of occupational low back disorders, yet potential adverse effects of such exposure on trunk mechanical and neuromuscular behaviours were not well described. Here, 12 participants, gender balanced, completed 40 min of repetitive lifting in all combinations of three flexion angles (33, 66, and 100% of each participant's full flexion angle) and two lift rates (2 and 4 lifts/min). Trunk behaviours were obtained pre- and post-exposure and during recovery using sudden perturbations. Intrinsic trunk stiffness and reflexive responses were compromised after lifting exposures, with larger decreases in stiffness and reflexive force caused by larger flexion angles, which also delayed reflexive responses. Consistent effects of lift rate were not found. Except for reflex delay no measures returned to pre-exposure values after 20 min of recovery. Simultaneous changes in both trunk stiffness and neuromuscular behaviours may impose an increased risk of trunk instability and low back injury. An elevated risk of low back disorders is attributed to repetitive lifting. Here, the effects of flexion angle and lift rate on trunk mechanical and neuromuscular behaviours were investigated. Increasing flexion angle had adverse effects on these outcomes, although lift rate had inconsistent effects and recovery time was more than 20 min.

  11. Theoretical prediction of regression rates in swirl-injection hybrid rocket engines

    Science.gov (United States)

    Ozawa, K.; Shimada, T.

    2016-07-01

    The authors theoretically and analytically predict what times regression rates of swirl injection hybrid rocket engines increase higher than the axial injection ones by estimating heat flux from boundary layer combustion to the fuel port. The schematic of engines is assumed as ones whose oxidizer is injected from the opposite side of the nozzle such as ones of Yuasa et al. propose. To simplify the estimation, we assume some hypotheses such as three-dimensional (3D) axisymmetric flows have been assumed. The results of this prediction method are largely consistent with Yuasa's experiments data in the range of high swirl numbers.

  12. High-repetition-rate quasi-CW side-pumped mJ eye-safe laser with a monolithic KTP crystal for intracavity optical parametric oscillator.

    Science.gov (United States)

    Cho, C Y; Chen, Y C; Huang, Y P; Huang, Y J; Su, K W; Chen, Y F

    2014-04-01

    We demonstrate a high-repetition-rate millijoule passively Q-switched eye-safe Nd:YVO(4) laser pumped by a quasi-CW diode stack. A theoretical analysis has been explored for the design criteria of generating TEM(n,0) mode in the diode-stack directly side-pumping configuration. We successfully generate TEM(n,0) modes at 1064 nm by adjusting the gain medium with respected to the laser axis. We further observe the spatial cleaning ability for generating an nearly TEM(0,0) mode output at 1573 nm with a monolithic OPO cavity. At the repetition rate up to 200 Hz, the output pulse energy reaches 1.21 mJ with the threshold pump energy of 17.9 mJ.

  13. Dual-frequency comb generation with differing GHz repetition rates by parallel Fabry-Perot cavity filtering of a single broadband frequency comb source

    Science.gov (United States)

    Mildner, Jutta; Meiners-Hagen, Karl; Pollinger, Florian

    2016-07-01

    We present a dual-comb-generator based on a coupled Fabry-Perot filtering cavity doublet and a single seed laser source. By filtering a commercial erbium-doped fiber-based optical frequency comb with CEO-stabilisation and 250 MHz repetition rate, two broadband coherent combs of different repetition rates in the GHz range are generated. The filtering doublet consists of two Fabry-Perot cavities with a tunable spacing and Pound-Drever-Hall stabilisation scheme. As a prerequisite for the development of such a filtering unit, we present a method to determine the actual free spectral range and transmission bandwidth of a Fabry-Perot cavity in situ. The transmitted beat signal of two diode lasers is measured as a function of their tunable frequency difference. Finally, the filtering performance and resulting beat signals of the heterodyned combs are discussed as well as the optimisation measures of the whole system.

  14. Testing of super conducting low-beta 704 Mhz cavities at 50 Hz pulse repetition rate in view of SPL- first results

    CERN Document Server

    Höfle, W; Lollierou, J; Valuch, D; Chel, S; Devanz, G; Desmons, M; Piquet, O; Paparella, R; Pierini, P

    2010-01-01

    In the framework of the preparatory phase for the luminosity upgrade of the LHC (SLHC-PP ) it is foreseen to characterize two superconducting RF cavities and demonstrate compliance of the required SPL field stability in amplitude and phase using a prototype LLRF system. We report on the preparation for testing of two superconducting low-beta cavities at 50 Hz pulse repetition rate including the setting-up of the low level RF control system to evaluate the performance of the piezo-tuning system and cavity field stability in amplitude and phase. Results from tests with 50 Hz pulse repetition rate are presented. Simulations of the RF system will be used to predict the necessary specifications for power and bandwidth to control the cavity field and derive specifications for the RF system and its control. Exemplary results of the simulation are presented.

  15. A high-repetition rate scheme for synchrotron-based picosecond laser pump/x-ray probe experiments on chemical and biological systems in solution.

    Science.gov (United States)

    Lima, Frederico A; Milne, Christopher J; Amarasinghe, Dimali C V; Rittmann-Frank, Mercedes Hannelore; van der Veen, Renske M; Reinhard, Marco; Pham, Van-Thai; Karlsson, Susanne; Johnson, Steven L; Grolimund, Daniel; Borca, Camelia; Huthwelker, Thomas; Janousch, Markus; van Mourik, Frank; Abela, Rafael; Chergui, Majed

    2011-06-01

    We present the extension of time-resolved optical pump/x-ray absorption spectroscopy (XAS) probe experiments towards data collection at MHz repetition rates. The use of a high-power picosecond laser operating at an integer fraction of the repetition rate of the storage ring allows exploitation of up to two orders of magnitude more x-ray photons than in previous schemes based on the use of kHz lasers. Consequently, we demonstrate an order of magnitude increase in the signal-to-noise of time-resolved XAS of molecular systems in solution. This makes it possible to investigate highly dilute samples at concentrations approaching physiological conditions for biological systems. The simplicity and compactness of the scheme allows for straightforward implementation at any synchrotron beamline and for a wide range of x-ray probe techniques, such as time-resolved diffraction or x-ray emission studies.

  16. Broadly wavelength- and pulse width-tunable high-repetition rate light pulses from soliton self-frequency shifting photonic crystal fiber integrated with a frequency doubling crystal.

    Science.gov (United States)

    Lanin, Aleksandr A; Fedotov, Andrei B; Zheltikov, Aleksei M

    2012-09-01

    Soliton self-frequency shift (SSFS) in a photonic crystal fiber (PCF) pumped by a long-cavity mode-locked Cr:forsterite laser is integrated with second harmonic generation (SHG) in a nonlinear crystal to generate ultrashort light pulses tunable within the range of wavelengths from 680 to 1800 nm at a repetition rate of 20 MHz. The pulse width of the second harmonic output is tuned from 70 to 600 fs by varying the thickness of the nonlinear crystal, beam-focusing geometry, and the wavelength of the soliton PCF output. Wavelength-tunable pulses generated through a combination of SSFS and SHG are ideally suited for coherent Raman microspectroscopy at high repetition rates, as verified by experiments on synthetic diamond and polystyrene films.

  17. Gigahertz repetition rate, sub-femtosecond timing jitter optical pulse train directly generated from a mode-locked Yb:KYW laser

    CERN Document Server

    Yang, Heewon; Shin, Junho; Kim, Chur; Choi, Sun Young; Kim, Guang-Hoon; Rotermund, Fabian; Kim, Jungwon

    2014-01-01

    We show that a 1.13-GHz repetition rate optical pulse train with 0.70 fs high-frequency timing jitter (integration bandwidth of 17.5 kHz - 10 MHz, where the measurement instrument-limited noise floor contributes 0.41 fs in 10 MHz bandwidth) can be directly generated from a free-running, single-mode diode-pumped Yb:KYW laser mode-locked by single-walled carbon nanotube (SWCNT)-coated mirrors. To our knowledge, this is the lowest timing jitter optical pulse train with the GHz repetition rate ever measured. If this pulse train is used for direct sampling of 565-MHz signals (Nyquist frequency of the pulse train), the demonstrated jitter level corresponds to the projected effective-number-of-bit (ENOB) of 17.8, which is much higher than the thermal noise limit of 50-ohm load resistance (~14 bits).

  18. Current injection and receptor-mediated excitation produce similar maximal firing rates in hypoglossal motoneurons.

    Science.gov (United States)

    Wakefield, Hilary E; Fregosi, Ralph F; Fuglevand, Andrew J

    2016-03-01

    The maximum firing rates of motoneurons (MNs), activated in response to synaptic drive, appear to be much lower than that elicited by current injection. It could be that the decrease in input resistance associated with increased synaptic activity (but not current injection) might blunt overall changes in membrane depolarization and thereby limit spike-frequency output. To test this idea, we recorded, in the same cells, maximal firing responses to current injection and to synaptic activation. We prepared 300 μm medullary slices in neonatal rats that contained hypoglossal MNs and used whole-cell patch-clamp electrophysiology to record their maximum firing rates in response to triangular-ramp current injections and to glutamate receptor-mediated excitation. Brief pressure pulses of high-concentration glutamate led to significant depolarization, high firing rates, and temporary cessation of spiking due to spike inactivation. In the same cells, we applied current clamp protocols that approximated the time course of membrane potential change associated with glutamate application and with peak current levels large enough to cause spike inactivation. Means (SD) of maximum firing rates obtained in response to glutamate application were nearly identical to those obtained in response to ramp current injection [glutamate 47.1 ± 12.0 impulses (imp)/s, current injection 47.5 ± 11.2 imp/s], even though input resistance was 40% less during glutamate application compared with current injection. Therefore, these data suggest that the reduction in input resistance associated with receptor-mediated excitation does not, by itself, limit the maximal firing rate responses in MNs.

  19. Compact High-Repetition-Rate Monochromatic Terahertz Source Based on Difference Frequency Generation from a Dual-Wavelength Nd:YAG Laser and DAST Crystal

    Science.gov (United States)

    Zhong, Kai; Mei, Jialin; Wang, Maorong; Liu, Pengxiang; Xu, Degang; Wang, Yuye; Shi, Wei; Yao, Jianquan; Teng, Bing; Xiao, Yong

    2017-01-01

    Although high-repetition-rate dual-wavelength Nd:YAG lasers at 1319 and 1338 nm have been realized for quite a long time, we have employed it in generating monochromatic terahertz (THz) wave in this paper for the first time. The dual-wavelength laser was LD-end-pumped and acousto-optically (AO) Q-switched with the output power of watt level operating at different repetition rates from 5.5 to 30 kHz. Using a 0.6-mm-thick organic nonlinear crystal DAST for difference frequency generation (DFG), a compact terahertz source was achieved at 3.28 THz. The maximum average output power was about 0.58 μW obtained at a repetition rate of 5.5 kHz, corresponding to the conversion efficiency of about 6.4 × 10-7. The output power scaling is still feasible with higher pump power and a longer nonlinear DFG crystal. Owing to the compactness of the dual-wavelength laser and the nonlinear crystal, a palm-top terahertz source is expected for portable applications such as imaging and so on.

  20. Tunable GHz pulse repetition rate operation in high-power TEM(00)-mode Nd:YLF lasers at 1047 nm and 1053 nm with self mode locking.

    Science.gov (United States)

    Huang, Y J; Tzeng, Y S; Tang, C Y; Huang, Y P; Chen, Y F

    2012-07-30

    We report on a high-power diode-pumped self-mode-locked Nd:YLF laser with the pulse repetition rate up to several GHz. A novel tactic is developed to efficiently select the output polarization state for achieving the stable TEM(00)-mode self-mode-locked operations at 1053 nm and 1047 nm, respectively. At an incident pump power of 6.93 W and a pulse repetition rate of 2.717 GHz, output powers as high as 2.15 W and 1.35 W are generated for the σ- and π-polarization, respectively. We experimentally find that decreasing the separation between the gain medium and the input mirror not only brings in the pulse shortening thanks to the enhanced effect of the spatial hole burning, but also effectively introduces the effect of the spectral filtering to lead the Nd:YLF laser to be in a second harmonic mode-locked status. Consequently, pulse durations as short as 8 ps and 8.5 ps are obtained at 1053 nm and 1047 nm with a pulse repetition rate of 5.434 GHz.

  1. Highly efficient, versatile, self-Q-switched, high-repetition-rate microchip laser generating Ince-Gaussian modes for optical trapping

    Science.gov (United States)

    Dong, Jun; He, Yu; Zhou, Xiao; Bai, Shengchuang

    2016-03-01

    Lasers operating in the Ince-Gaussian (IG) mode have potential applications for optical manipulation of microparticles and formation of optical vortices, as well as for optical trapping and optical tweezers. Versatile, self-Q-switched, high-peak-power, high-repetition-rate Cr, Nd:YAG microchip lasers operating in the IG mode are implemented under tilted, tightly focused laser-diode pumping. An average output power of over 2 W is obtained at an absorbed pump power of 6.4 W. The highest optical-to-optical efficiency of 33.2% is achieved at an absorbed pump power of 3.9 W. Laser pulses with a pulse energy of 7.5 μJ, pulse width of 3.5 ns and peak power of over 2 kW are obtained. A repetition rate up to 335 kHz is reached at an absorbed pump power of 5.8 W. Highly efficient, versatile, IG-mode lasers with a high repetition rate and a high peak power ensure a better flexibility in particle manipulation and optical trapping.

  2. Highly efficient, versatile, self-Q-switched, high-repetition-rate microchip laser generating Ince–Gaussian modes for optical trapping

    Energy Technology Data Exchange (ETDEWEB)

    Jun Dong; Yu He; Xiao Zhou; Shengchuang Bai [Department of Electronics Engineering, School of Information Science and Engineering, Xiamen, 361005 (China)

    2016-03-31

    Lasers operating in the Ince-Gaussian (IG) mode have potential applications for optical manipulation of microparticles and formation of optical vortices, as well as for optical trapping and optical tweezers. Versatile, self-Q-switched, high-peak-power, high-repetition-rate Cr, Nd:YAG microchip lasers operating in the IG mode are implemented under tilted, tightly focused laser-diode pumping. An average output power of over 2 W is obtained at an absorbed pump power of 6.4 W. The highest optical-to-optical efficiency of 33.2% is achieved at an absorbed pump power of 3.9 W. Laser pulses with a pulse energy of 7.5 μJ, pulse width of 3.5 ns and peak power of over 2 kW are obtained. A repetition rate up to 335 kHz is reached at an absorbed pump power of 5.8 W. Highly efficient, versatile, IG-mode lasers with a high repetition rate and a high peak power ensure a better flexibility in particle manipulation and optical trapping. (control of laser radiation parameters)

  3. Bandwidth and repetition rate programmable Nyquist sinc-shaped pulse train source based on intensity modulators and four-wave mixing.

    Science.gov (United States)

    Cordette, S; Vedadi, A; Shoaie, M A; Brès, C-S

    2014-12-01

    We propose and experimentally demonstrate an all-optical Nyquist sinc-shaped pulse train source based on intensity modulation and four-wave mixing. The proposed scheme allows for the tunability of the bandwidth and the full flexibility of the repetition rate in the limit of the electronic bandwidth of the modulators used through the flexible synthesis of rectangular frequency combs. Bandwidth up to 360 GHz at 40 GHz rate and up to 45 frequency lines at 5 GHz rate are demonstrated with 40 GHz modulators.

  4. Preoperative Hip Injections Increase the Rate of Periprosthetic Infection After Total Hip Arthroplasty.

    Science.gov (United States)

    Schairer, William W; Nwachukwu, Benedict U; Mayman, David J; Lyman, Stephen; Jerabek, Seth A

    2016-09-01

    Intraarticular injections are both diagnostic and therapeutic for patients with osteoarthritis. A potential risk of periprosthetic joint infection (PJI) after total hip arthroplasty (THA) may occur from direct inoculation and/or immune suppression by corticosteroids. Large population-level databases were used to evaluate hip injection on the 1-year rate of PJI in patients undergoing primary THA. State-level ambulatory surgery and inpatient databases for Florida and California (2005-2012) were used to identify primary THA patients with 1-year preoperative and postoperative windows to evaluate possible injections or PJI, respectively. Patients were grouped as no injection or as THA performed 6-12 months, 3-6 months, or 0-3 months after injection. Risk adjustment was performed with multivariable regression. A total of 173,958 patients were included; 5421 (3.1%) underwent THA after an injection: 1395 (1.1%) of patients after 6-12 months, 1863 patients after 3-6 months, and 2163 (1.2%) after 0-3 months. In the 0-3 month group, PJI was significantly increased at 3 months (1.58%, P = .015), 6 months (1.76%, P = .022), and 1 year (2.04%, P = .031) compared with the noninjection control group (1.04%, 1.21%, and 1.47%, respectively). There were no differences in the 3- to 6-month and 6- to 12-month injection groups. There is an increased risk of PJI when THA is performed within 3 months of hip injection. We recommend that patients and their surgeons consider delaying elective THA until 3 months after an injection to avoid this elevated risk of infection. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Single-pulse picking at kHz repetition rates using a Ge plasma switch at the free-electron laser FELBE.

    Science.gov (United States)

    Schmidt, J; Winnerl, S; Seidel, W; Bauer, C; Gensch, M; Schneider, H; Helm, M

    2015-06-01

    We demonstrate a system for picking of mid-infrared and terahertz (THz) radiation pulses from the free-electron laser (FEL) FELBE operating at a repetition rate of 13 MHz. Single pulses are reflected by a dense electron-hole plasma in a Ge slab that is photoexcited by amplified near-infrared (NIR) laser systems operating at repetition rates of 1 kHz and 100 kHz, respectively. The peak intensity of picked pulses is up to 400 times larger than the peak intensity of residual pulses. The required NIR fluence for picking pulses at wavelengths in the range from 5 μm to 30 μm is discussed. In addition, we show that the reflectivity of the plasma decays on a time scale from 100 ps to 1 ns dependent on the wavelengths of the FEL and the NIR laser. The plasma switch enables experiments with the FEL that require high peak power but lower average power. Furthermore, the system is well suited to investigate processes with decay times in the μs to ms regime, i.e., much longer than the 77 ns long pulse repetition period of FELBE.

  6. Fines stabilizing agent reduces production decline rates in steam injected wells

    Energy Technology Data Exchange (ETDEWEB)

    Castillo de Castillo, Milagros; Fernandez Andrades, Jarvi [PDVSA - Petroleos de Venezuela S.A., Caracas (Venezuela); Navarro Cornejo, Willian; Curtis, James [BJ Services do Brasil Ltda., RJ (Brazil)

    2004-07-01

    The Bachaquero Lago heavy oil field, located in Lake Maracaibo, Venezuela, with an area of 9800 ha, in which more than 1800 wells have been drilled. The Lagunillas formation in this field is a mature, clastic, unconsolidated sandstone of Miocene age with good permeability. Clays are present, in laminated form or dispersed within the productive sandstones. Heavy oil, less than 12 deg API, is produced by cyclic steam injection. Wells are completed with cased-hole gravel packs to prevent sand and fines production. Rapid production decline rates are typically observed after the steam injection cycles, due to fines migration and plugging of the reservoir and gravel pack. This paper describes the methodology used to treat the wells with a fines stabilizing agent during the steam injection cycles in order to successfully reduce the subsequent production decline rate. Results from a multi-well pilot project are presented and analyzed. (author)

  7. Repetitive recombinant human bone morphogenetic protein 2 injections improve the callus microarchitecture and mechanical stiffness in a sheep model of distraction osteogenesis

    Directory of Open Access Journals (Sweden)

    Marc-Frederic Pastor

    2012-03-01

    Full Text Available Evidence suggests that recombinant human bone morphogenetic protein 2 (rhBMP-2 increases the mechanical integrity of callus tissue during bone healing. This effect may be either explained by an increase of callus formation or a modification of the trabecular microarchitecture. Therefore the purpose of the study was to evaluate the potential benefit of rhBMP-2 on the trabecular microarchitecture and on multidirectional callus stiffness. Further we asked, whether microarchitecture changes correlate with optimized callus stiffness. In this study a tibial distraction osteogenesis (DO model in 12 sheep was used to determine, whether percutaneous injection of rhBMP-2 into the distraction zone influences the microarchitecture of the bone regenerate. After a latency period of 4 days, the tibiae were distracted at a rate of 1.25 mm/day over a period of 20 days, resulting in total lengthening of 25 mm. The operated limbs were randomly assigned to one treatment groups and one control group: (A triple injection of rhBMP-2 (4 mg rhBMP-2/injection and (B no injection. The tibiae were harvested after 74 days and scanned by μCT (90 μm/voxel. In addition, we conducted a multidirectional mechanical testing of the tibiae by using a material testing system to assess the multidirectional strength. The distraction zones were tested for torsional stiffness and bending stiffness antero-posterior (AP and medio-lateral (ML direction, compression strength and maximum axial torsion. Statistical analysis was performed using multivariate analysis of variance (ANOVA followed by student’s t-test and Regression analysis using power functions with a significance level of P<0.05. Triple injections of rhBMP-2 induced significant changes in the trabecular architecture of the regenerate compared with the control: increased trabecular number (Tb.N. (treatment group 1.73 mm/1 vs. control group 1.2 mm/1, increased cortical bone volume fraction (BV/TV (treatment group 0.68 vs

  8. Numerical Modeling of Variable Fluid Injection-Rate Modes on Fracturing Network Evolution in Naturally Fractured Formations

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2016-05-01

    Full Text Available In this study, variable injection-rate technology was numerically investigated in a pre-existing discrete fracture network (DFN formation, the Tarim Basin in China. A flow-stress-damage (FSD coupling model has been used in an initial attempt towards how reservoir response to variable injection-rates at different hydraulic fracturing stages. The established numerical model simultaneously considered the macroscopic and microscopic heterogeneity characteristics. Eight numerical cases were studied. Four cases were used to study the variable injection-rate technology, and the other four cases were applied for a constant injection-rate in order to compare with the variable injection-rate technology. The simulation results show that the variable injection-rate technology is a potentially good method to a form complex fracturing networks. The hydraulic fracturing effectiveness when increasing the injection-rate at each stage is the best, also, the total injected fluid is at a minimum. At the initial stage, many under-fracturing points appear around the wellbore with a relatively low injection-rate; the sudden increase of injection rate drives the dynamic propagation of hydraulic fractures along many branching fracturing points. However, the case with decreasing injection rate is the worst. By comparing with constant injection-rate cases, the hydraulic fracturing effectiveness with variable flow rate technology is generally better than those with constant injection-rate technology. This work strongly links the production technology and hydraulic fracturing effectiveness evaluation and aids in the understanding and optimization of hydraulic fracturing simulations in naturally fractured reservoirs.

  9. 40 CFR 62.15275 - How do I monitor the injection rate of activated carbon?

    Science.gov (United States)

    2010-07-01

    ... activated carbon? 62.15275 Section 62.15275 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... August 30, 1999 Other Monitoring Requirements § 62.15275 How do I monitor the injection rate of activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans...

  10. 40 CFR 60.1330 - How do I monitor the injection rate of activated carbon?

    Science.gov (United States)

    2010-07-01

    ... activated carbon? 60.1330 Section 60.1330 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Requirements § 60.1330 How do I monitor the injection rate of activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or mercury emissions, you must meet...

  11. The effects of varying injection rates in Osage County, Oklahoma, on the 2016 Mw5.8 Pawnee earthquake

    Science.gov (United States)

    Barbour, Andrew J.; Norbeck, Jack H.; Rubinstein, Justin L.

    2017-01-01

    The 2016 Mw 5.8 Pawnee earthquake occurred in a region with active wastewater injection into a basal formation group. Prior to the earthquake, fluid injection rates at most wells were relatively steady, but newly collected data show significant increases in injection rate in the years leading up to earthquake. For the same time period, the total volumes of injected wastewater were roughly equivalent between variable‐rate and constant‐rate wells. To understand the possible influence of these changes in injection, we simulate the variable‐rate injection history and its constant‐rate equivalent in a layered poroelastic half‐space to explore the interplay between pore‐pressure effects and poroelastic effects on the fault leading up to the mainshock. In both cases, poroelastic stresses contribute a significant proportion of Coulomb failure stresses on the fault compared to pore‐pressure increases alone, but the resulting changes in seismicity rate, calculated using a rate‐and‐state frictional model, are many times larger when poroelastic effects are included, owing to enhanced stressing rates. In particular, the variable‐rate simulation predicts more than an order of magnitude increase in seismicity rate above background rates compared to the constant‐rate simulation with equivalent volume. The observed cumulative density of earthquakes prior to the mainshock within 10 km of the injection source exhibits remarkable agreement with seismicity predicted by the variable‐rate injection case.

  12. Simulation for estimation of hydrogen sulfide scavenger injection dose rate for treatment of crude oil

    Directory of Open Access Journals (Sweden)

    T.M. Elshiekh

    2015-12-01

    Full Text Available The presence of hydrogen sulfide in the hydrocarbon fluids is a well known problem in many oil and gas fields. Hydrogen sulfide is an undesirable contaminant which presents many environmental and safety hazards. It is corrosive, malodorous, and toxic. Accordingly, a need has been long left in the industry to develop a process which can successfully remove hydrogen sulfide from the hydrocarbons or at least reduce its level during the production, storage or processing to a level that satisfies safety and product specification requirements. The common method used to remove or reduce the concentration of hydrogen sulfide in the hydrocarbon production fluids is to inject the hydrogen sulfide scavenger into the hydrocarbon stream. One of the chemicals produced by the Egyptian Petroleum Research Institute (EPRI is EPRI H2S scavenger. It is used in some of the Egyptian petroleum producing companies. The injection dose rate of H2S scavenger is usually determined by experimental lab tests and field trials. In this work, this injection dose rate is mathematically estimated by modeling and simulation of an oil producing field belonging to Petrobel Company in Egypt which uses EPRI H2S scavenger. Comparison between the calculated and practical values of injection dose rate emphasizes the real ability of the proposed equation.

  13. Effect of the helicity injection rate and the Lundquist number on spheromak sustainment

    Energy Technology Data Exchange (ETDEWEB)

    García-Martínez, Pablo Luis, E-mail: pablogm@cab.cnea.gov.ar [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Sede Andina—Universidad Nacional de Río Negro (UNRN), Av. Bustillo 9500, 8400 San Carlos de Bariloche, Río Negro (Argentina); Lampugnani, Leandro Gabriel; Farengo, Ricardo [Instituto Balseiro and Centro Atómico Bariloche (CAB-CNEA), Av. Bustillo 9500, 8400 San Carlos de Bariloche, Río Negro (Argentina)

    2014-12-15

    The dynamics of the magnetic relaxation process during the sustainment of spheromak configurations at different helicity injection rates is studied. The three-dimensional activity is recovered using time-dependent resistive magnetohydrodynamic simulations. A cylindrical flux conserver with concentric electrodes is used to model configurations driven by a magnetized coaxial gun. Magnetic helicity is injected by tangential boundary flows. Different regimes of sustainment are identified and characterized in terms of the safety factor profile. The spatial and temporal behavior of fluctuations is described. The dynamo action is shown to be in close agreement with existing experimental data. These results are relevant to the design and operation of helicity injected devices, as well as to basic understanding of the plasma relaxation mechanism in quasi-steady state.

  14. Effect of the helicity injection rate and the Lundquist number on spheromak sustainment

    Science.gov (United States)

    García-Martínez, Pablo Luis; Lampugnani, Leandro Gabriel; Farengo, Ricardo

    2014-12-01

    The dynamics of the magnetic relaxation process during the sustainment of spheromak configurations at different helicity injection rates is studied. The three-dimensional activity is recovered using time-dependent resistive magnetohydrodynamic simulations. A cylindrical flux conserver with concentric electrodes is used to model configurations driven by a magnetized coaxial gun. Magnetic helicity is injected by tangential boundary flows. Different regimes of sustainment are identified and characterized in terms of the safety factor profile. The spatial and temporal behavior of fluctuations is described. The dynamo action is shown to be in close agreement with existing experimental data. These results are relevant to the design and operation of helicity injected devices, as well as to basic understanding of the plasma relaxation mechanism in quasi-steady state.

  15. High-power, high-repetition-rate performance characteristics of β-BaB₂O₄ for single-pass picosecond ultraviolet generation at 266 nm.

    Science.gov (United States)

    Kumar, S Chaitanya; Casals, J Canals; Wei, Junxiong; Ebrahim-Zadeh, M

    2015-10-19

    We report a systematic study on the performance characteristics of a high-power, high-repetition-rate, picosecond ultraviolet (UV) source at 266 nm based on β-BaB2O4 (BBO). The source, based on single-pass fourth harmonic generation (FHG) of a compact Yb-fiber laser in a two-crystal spatial walk-off compensation scheme, generates up to 2.9 W of average power at 266 nm at a pulse repetition rate of ~80 MHz with a single-pass FHG efficiency of 35% from the green to UV. Detrimental issues such as thermal effects have been studied and confirmed by performing relevant measurements. Angular and temperature acceptance bandwidths in BBO for FHG to 266 nm are experimentally determined, indicating that the effective interaction length is limited by spatial walk-off and thermal gradients under high-power operation. The origin of dynamic color center formation due to two-photon absorption in BBO is investigated by measurements of intensity-dependent transmission at 266 nm. Using a suitable theoretical model, two-photon absorption coefficients as well as the color center densities have been estimated at different temperatures. The measurements show that the two-photon absorption coefficient in BBO at 266 nm is ~3.5 times lower at 200°C compared to that at room temperature. The long-term power stability as well as beam pointing stability is analyzed at different output power levels and focusing conditions. Using cylindrical optics, we have circularized the generated elliptic UV beam to a circularity of >90%. To our knowledge, this is the first time such high average powers and temperature-dependent two-photon absorption measurements at 266 nm are reported at repetition rates as high as ~80 MHz.

  16. Flow rate dependent extra-column variance from injection in capillary liquid chromatography.

    Science.gov (United States)

    Aggarwal, Pankaj; Liu, Kun; Sharma, Sonika; Lawson, John S; Dennis Tolley, H; Lee, Milton L

    2015-02-01

    Efficiency and resolution in capillary liquid chromatography (LC) can be significantly affected by extra-column band broadening, especially for isocratic separations. This is particularly a concern in evaluating column bed structure using non-retained test compounds. The band broadening due to an injector supplied with a commercially available capillary LC system was characterized from experimental measurements. The extra-column variance from the injection valve was found to have an extra-column contribution independent of the injection volume, showing an exponential dependence on flow rate. The overall extra-column variance from the injection valve was found to vary from 34 to 23 nL. A new mathematical model was derived that explains this exponential contribution of extra-column variance on chromatographic performance. The chromatographic efficiency was compromised by ∼130% for a non-retained analyte because of injection valve dead volume. The measured chromatographic efficiency was greatly improved when a new nano-flow pumping system with integrated injection valve was used.

  17. μJ-level, kHz-repetition rate femtosecond fiber-CPA system at 1555 nm

    Science.gov (United States)

    Sobon, Grzegorz; Kaczmarek, Pawel; Gluszek, Aleksander; Sotor, Jaroslaw; Abramski, Krzysztof M.

    2015-07-01

    In this work, we demonstrate a high-power, fiber-based chirped pulse amplification (CPA) setup utilizing Er- and Er/Yb-doped fibers, operating at 1555 nm central wavelength. The integrated all-fiber pulse-picker allows to reduce the repetition frequency down to the kHz-range, which enables generation of sub-picosecond pulses with energies above 2 μJ and pulse peak power exceeding 1 MW. The system utilizes an Er/Yb co-doped large mode area fiber in the final amplification stage. Thanks to the used mode-field adapters and fiber-based components, the setup is almost fully fiberized, except the bulk grating pulse compressor. In order to provide compactness and simplicity, the compressor was designed using dense 1100 lines per millimeter gratings, that allow to keep the small grating separation.

  18. 1-J operation of monolithic composite ceramics with Yb:YAG thin layers: multi-TRAM at 10-Hz repetition rate and prospects for 100-Hz operation.

    Science.gov (United States)

    Divoky, Martin; Tokita, Shigeki; Hwang, Sungin; Kawashima, Toshiyuki; Kan, Hirofumi; Lucianetti, Antonio; Mocek, Tomas; Kawanaka, Junji

    2015-03-15

    Experimental amplification of 10-ns pulses to energy of 1 J at repetition rate of 10-100 Hz in cryogenic multipass total-reflection active-mirror (TRAM) amplifier is reported for the first time. By using a monolithic multi-TRAM, which is a YAG ceramic composite with three thin Yb:YAG active layers, efficient energy extraction was achieved without parasitic lasing. A detailed measurement of output characteristics of the laser amplifier is presented; results are discussed and compared with numerical calculations.

  19. 615 fs pulses with 17 mJ energy generated by an Yb:thin-disk amplifier at 3 kHz repetition rate.

    Science.gov (United States)

    Fischer, Jonathan; Heinrich, Alexander-Cornelius; Maier, Simon; Jungwirth, Julian; Brida, Daniele; Leitenstorfer, Alfred

    2016-01-15

    A combination of Er/Yb:fiber and Yb:thin-disk technology produces 615 fs pulses at 1030 nm with an average output power of 72 W. The regenerative amplifier allows variation of the repetition rate between 3 and 5 kHz with pulse energies from 13 to 17 mJ. A broadband and intense seed provided by the compact and versatile fiber front-end minimizes gain narrowing. The resulting sub-ps performance is ideal for nonlinear frequency conversion and pulse compression. Operating in the upper branch of a bifurcated pulse train, the system exhibits exceptional noise performance and stability.

  20. Generation of 220 mJ nanosecond pulses at a 10 Hz repetition rate with excellent beam quality in a diode-pumped Yb:YAG MOPA system.

    Science.gov (United States)

    Wandt, Christoph; Klingebiel, Sandro; Siebold, Mathias; Major, Zsuzsanna; Hein, Joachim; Krausz, Ferenc; Karsch, Stefan

    2008-05-15

    A novel all-diode-pumped master oscillator power amplifier system based on Yb:YAG crystal rods has been developed. It consists of a Q-switched oscillator delivering 3 mJ, 6.4 ns pulses at a 10 Hz repetition rate and an additional four-pass amplifier, which boosts the output energy to 220 mJ, while a close to TEM(00) beam quality could be observed. Additionally a simulation of the amplification was written that allows for further scaling considerations.

  1. 1-MW peak power, 574-kHz repetition rate picosecond pulses at 515 nm from a frequency-doubled fiber amplifier

    Science.gov (United States)

    Zou, Feng; Wang, Ziwei; Wang, Zhaokun; Bai, Yang; Li, Qiurui; Zhou, Jun

    2016-11-01

    1-MW peak power picosecond, 574-kHz repetition rate green laser at 515-nm is generated from a frequency-doubled fiber amplifier. 12-ps pulses with 13.9-μJ energy at 515 nm are achieved with a noncritically phase-matched lithium triborate (LBO) crystal through second harmonic generation of a 1030 nm infrared source. The infrared source employs ultra-large-mode-area rod-type photonic crystal fiber (Rod-PCF) for direct picosecond amplification and delivers 20-W 11.6-ps 2.97-MW pulse train with near-diffraction-limited beam quality (M2 = 1.01).

  2. Laser-induced backside wet etching of silica glass with ns-pulsed DPSS UV laser at the repetition rate of 40 kHz

    Energy Technology Data Exchange (ETDEWEB)

    Niino, Hiroyuki; Kawaguchi, Yoshizo; Sato, Tadatake; Narazaki, Aiko; Gumpenberger, Thomas; Kurosaki, Ryozo [Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, Higashi, Tsukuba, Ibaraki 305-8565 (Japan)

    2007-04-15

    Surface micro-structuring of silica glass plates was performed by using laser- induced backside wet etching (LIBWE) upon irradiation with a single-mode laser beam from a diode-pumped solid-state (DPSS) UV laser with 40 kHz repetition rate at 266 nm. We have succeeded in a well-defined micro-pattern formation without debris and microcrack generation around the etched area on the basis of a galvanometer scanning system for the laser beam. Bubble dynamics after liquid ablation was monitored by impulse pressure detection with a fast- response piezoelectric pressure gauge.

  3. A K-alpha x-ray source using high energy and high repetition rate laser system for phase contrast imaging

    OpenAIRE

    Serbanescu, Cristina; Fourmaux, Sylvain; Kieffer, Jean-Claude; Kincaid, Russell; Krol, Andrzej

    2009-01-01

    K-alpha x-ray sources from laser produced plasmas provide completely new possibilities for x-ray phase-contrast imaging applications. By tightly focusing intense femtosecond laser pulses onto a solid target K-alpha x-ray pulses are generated through the interaction of energetic electrons created in the plasma with the bulk target. In this paper, we present a continuous and efficient Mo K-alpha x-ray source produced by a femtosecond laser system operating at 100 Hz repetition rate with maximum...

  4. Subharmonic resonant optical excitation of confined acoustic modes in a free-standing semiconductor membrane at GHz frequencies with a high-repetition-rate femtosecond laser.

    Science.gov (United States)

    Bruchhausen, A; Gebs, R; Hudert, F; Issenmann, D; Klatt, G; Bartels, A; Schecker, O; Waitz, R; Erbe, A; Scheer, E; Huntzinger, J-R; Mlayah, A; Dekorsy, T

    2011-02-18

    We propose subharmonic resonant optical excitation with femtosecond lasers as a new method for the characterization of phononic and nanomechanical systems in the gigahertz to terahertz frequency range. This method is applied for the investigation of confined acoustic modes in a free-standing semiconductor membrane. By tuning the repetition rate of a femtosecond laser through a subharmonic of a mechanical resonance we amplify the mechanical amplitude, directly measure the linewidth with megahertz resolution, infer the lifetime of the coherently excited vibrational states, accurately determine the system's quality factor, and determine the amplitude of the mechanical motion with femtometer resolution.

  5. Effect of fuel injection rate and timing on the physical, chemical, and biological character of particulate emissions from a direct injection diesel

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J.; Scholl, J.; Hibbler, F.; Bagley, S.; Leddy, D.; Abata, D.; Johnson, J.

    1981-01-01

    Formation of pollutants from diesel combustion and methods for their control have been reviewed. Of these methods, fuel injection rate and timing were selected for a parametric study relative to total particulate, soluble organic fraction (SOF), sulfates, solids and NO and NO/sub 2/ emissions from a heavy-duty, turbocharged, after-cooled, direct-injection (DI) diesel. Chemical analyses of the SOF were performed at selected engine conditions to determine the effects of injection rate and timing on each of the eight chemical subfractions comprising the SOF. Biological character of the SOF was determined using the Ames Salmonella/microsome bioassay. 54 refs.

  6. Effect of rheological parameters on curing rate during NBR injection molding

    Science.gov (United States)

    Kyas, Kamil; Stanek, Michal; Manas, David; Skrobak, Adam

    2013-04-01

    In this work, non-isothermal injection molding process for NBR rubber mixture considering Isayev-Deng curing kinetic model, generalized Newtonian model with Carreau-WLF viscosity was modeled by using finite element method in order to understand the effect of volume flow rate, index of non-Newtonian behavior and relaxation time on the temperature profile and curing rate. It was found that for specific geometry and processing conditions, increase in relaxation time or in the index of non-Newtonian behavior increases the curing rate due to viscous dissipation taking place at the flow domain walls.

  7. Antibacterial properties of 2% lidocaine and reduced rate of endophthalmitis after intravitreal injection.

    Science.gov (United States)

    Tustin, Aaron; Kim, Stephen J; Chomsky, Amy; Hubbard, G Baker; Sheng, Jinsong

    2014-05-01

    To determine whether the application of subconjunctival 2% lidocaine/0.1% methylparaben for anesthesia may reduce rates of endophthalmitis after intravitreal (IVT) injection. We performed in vitro experiments to determine the antibacterial properties of 2% lidocaine/0.1% methylparaben (lidocaine) against causative organisms of endophthalmitis. Isolates of Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus viridans from patients with endophthalmitis were incubated with or without lidocaine. Aliquots (100 µL) were plated on Mueller-Hinton (S. aureus and S. epidermidis) or blood agar plates (S. viridans) at 0, 10, 30, 120, and 240 minutes, and colonies were counted after 24 hours. A retrospective review of 15,042 IVT injections was performed from January 2004 to February 2011 to determine the rate of endophthalmitis with or without application of subconjunctival lidocaine for anesthesia. Lidocaine demonstrated rapid bactericidal effects against all 3 organisms. After 10 minutes of exposure, there was approximately a 90% (P 2% (P lidocaine and 8 cases of endophthalmitis of 8,189 (0.1%) IVT injections performed with other methods of anesthesia (P = 0.03). Application of subconjunctival 2% lidocaine/0.1% methylparaben for anesthesia may reduce the incidence of endophthalmitis after IVT injection.

  8. Practice of promoting pulverized coal injection rate at no.4 blast furnace of China Steel Corporation

    Energy Technology Data Exchange (ETDEWEB)

    Liang, N.W.; Chang, C.T [China Steel Corp., Kaohsiung, Taiwan (China)

    2008-07-01

    In 2006, the China Steel Corporation (CSC) upgraded the injection system of its no.4 blast furnace to increase the pulverized coal (PC) rate which averaged 136 to 143 kg/thm. This paper described the scheduled shutdown of the furnace in May 2007 in order to modify it from a dilute phase injection system to a dense phase system using the technology of the Kuettner Company. Through proper burden distribution and operational parameter adjustments, the pulverized coal (PC) rate was increased to 178 kg/thm by November 2007, corresponding to a 65 t/hr injection rate with a productivity of 2.58 t/m{sup 3}/d. This paper described the challenges encountered following commissioning as well as the strategies of process control. The main differences between the existing and new injection system were that nitrogen was used to substitute compressed air as the conveying gas and the coal to gas ratio was increased from about 10 to 30 kg/kg. As a result, the transport method and the operation pressure had to be reassessed. This paper described the coal blend injection; screening facility for coal preparation; location of the distributor; and coal accumulation in the coal flow meter. The blast furnace adjustments included burden thickness control; burden distribution adjustment; improvement of raw material quality; and theoretical flame temperature adjustment. The upgrade project has proven to be very successful and has improved the competitiveness of CSC blast furnace no.4 significantly. Plans to upgrade the no.2 and no.3 blast furnaces are underway. Once completed, the operating cost and coke consumption of the blast furnaces will be reduced considerably. The modification to dense phase conveying system has shown that coal with high Hardgrove Index requires a higher driving force in the pneumatic dense phase transport and that coal mill equipped with a rotating classifier is recommended along with screens at the upstream of the feed tank. 3 refs., 6 tabs., 9 figs.

  9. Effect of unequal injection rates on asymmetric exclusion processes with junction

    Institute of Scientific and Technical Information of China (English)

    Xiao Song; Liu Ming-Zhe; Wang Jian-Jun; Wang Hua

    2011-01-01

    In this paper, we investigate the effect of unequal injection rates on totally asymmetric simple exclusion processes (TASEPs) with a 2-input 1-output junction and parallel update. A mean-field approach is developed to deal with the junction that connects two sub-chains and the single main chain. We obtain the stationary particle currents, density profiles and phase diagrams. Interestingly, we find that the number of stationary-state phases is changeable depending on the value of α1 (α1 is the injection rate on the first sub-chain). When α1 > 1/3, there are seven stationary-state phases in the system, however when α1 < 1/3, only six stationary-state phases exist in the system. The theoretical calculations are shown to be in agreement with Monte Carlo simulations.

  10. Gain-switched laser diode seeded Yb-doped fiber amplifier delivering 11-ps pulses at repetition rates up to 40-MHz

    CERN Document Server

    Ryser, Manuel; Pilz, Soenke; Burn, Andreas; Romano, Valerio

    2014-01-01

    Here, we demonstrate all-fiber direct amplification of 11 picosecond pulses from a gain-switched laser diode at 1063nm. The diode was driven at a repetition rate of 40MHz and delivered 13$\\mu$W of fiber-coupled average output power. For the low output pulse energy of 0.33pJ we have designed a multi-stage core pumped preamplifier based on single clad Yb-doped fibers in order to keep the contribution of undesired amplified spontaneous emission as low as possible and to minimize temporal and spectral broadening. After the preamplifier we reduced the 40MHz repetition rate to 1MHz using a fiber coupled pulse-picker. The final amplification was done with a cladding pumped Yb-doped large mode area fiber and a subsequent Yb-doped rod-type fiber. With our setup we achieved amplification of 72dBs to an output pulse energy of 5.7$\\mu$J, pulse duration of 11ps and peak power of >0.6MW.

  11. Optimum injection dose rate of hydrogen sulfide scavenger for treatment of petroleum crude oil

    Directory of Open Access Journals (Sweden)

    T.M. Elshiekh

    2016-03-01

    Full Text Available Hydrogen sulfide H2S scavengers are chemicals that favorably react with hydrogen sulfide gas to eliminate it and produce environmental friendly products. These products depend on the type and composition of the scavenger and the conditions at which the reaction takes place. The scavenger should be widely available and economical for industry acceptance by having a low unit cost. The optimum values of H2S scavenger injection dose rate of scavenging hydrogen sulfide from the multiphase fluid produced at different wells conditions in one of the Petroleum Companies in Egypt were studied. The optimum values of H2S scavenger injection dose rate depend on pipe diameter, pipe length, gas molar mass velocity, inlet H2S concentration and pressure. The optimization results are obtained for different values of these parameters using the software program Lingo. In general, the optimum values of H2S scavenger injection dose rate of the scavenging of hydrogen sulfide are increased by increasing of the pipe diameter and increasing the inlet H2S concentration, and decreased by increasing the pipe length, gas molar mass velocity and pressure.

  12. On the Optimality of Repetition Coding among Rate-1 DC-offset STBCs for MIMO Optical Wireless Communications

    KAUST Repository

    Sapenov, Yerzhan

    2017-07-06

    In this paper, an optical wireless multiple-input multiple-output communication system employing intensity-modulation direct-detection is considered. The performance of direct current offset space-time block codes (DC-STBC) is studied in terms of pairwise error probability (PEP). It is shown that among the class of DC-STBCs, the worst case PEP corresponding to the minimum distance between two codewords is minimized by repetition coding (RC), under both electrical and optical individual power constraints. It follows that among all DC-STBCs, RC is optimal in terms of worst-case PEP for static channels and also for varying channels under any turbulence statistics. This result agrees with previously published numerical results showing the superiority of RC in such systems. It also agrees with previously published analytic results on this topic under log-normal turbulence and further extends it to arbitrary turbulence statistics. This shows the redundancy of the time-dimension of the DC-STBC in this system. This result is further extended to sum power constraints with static and turbulent channels, where it is also shown that the time dimension is redundant, and the optimal DC-STBC has a spatial beamforming structure. Numerical results are provided to demonstrate the difference in performance for systems with different numbers of receiving apertures and different throughput.

  13. A numerical study of the effects of injection rate shape on combustion and emission of diesel engines

    Directory of Open Access Journals (Sweden)

    He Zhixia

    2014-01-01

    Full Text Available The spray characteristics including spray droplet sizes, droplet distribution, spray tip penetration length and spray diffusion angle directly affects the mixture process of fuel and oxygen and then plays an important role for the improvement of combustion and emission performance of diesel engines. Different injection rate shapes may induce different spray characteristics and then further affect the subsequent combustion and emission performance of diesel engines. In this paper, the spray and combustion processes based on four different injection rate shapes with constant injection duration and injected fuel mass were simulated in the software of AVL FIRE. The numerical models were validated through comparing the results from the simulation with those from experiment. It was found that the dynamic of diesel engines with the new proposed hump shape of injection rate and the original saddle shape is better than that with the injection rate of rectangle and triangle shape, but the emission of NOX is higher. And the soot emission is lowest during the late injection period for the new hump-shape injection rate because of a higher oxidation rate with a better mixture between fuel and air under the high injection pressure.

  14. Improvement of denitrification rates in confined zones of fractured subsoils under continuous wastewater injection.

    Science.gov (United States)

    Carrieri, Carmelo; Masciopinto, Costantino

    2003-01-01

    An attempt to improve the natural biodegradation rate in a fractured aquifer (Nardò (Le), Southern Italy) subject since '91 to the injection of 12,000 m3/d of treated municipal wastewater, has been carried out through tests on pilot plants. The lab experiments showed that a complete nitrogen removal can be realized after 10 d of infiltration in fractures by adding whey in the influent waste. The lab results have been used in a mathematical model in order to simulate ground water quality changes caused by the addition of whey in the injecting water. The analytical parameters of ground water sampled in monitoring wells located at different distances from the injection site, have been compared with mathematical model results. Moreover for preserving such resource from pollution, the mathematical model allowed two areas, around the injection site to be drawn. These areas, where withdrawals would be prohibited, are required to avoid infections by pathogens and bacteria in ground water due to incomplete biodegradation processes. The experimental results can be useful to identify standardized methodology for artificial ground water recharge which could be required for aquifer clean up (Water Frame Directive 2000/60).

  15. Strong Asymmetric Coupling of Two Parallel Exclusion Processes: Effect of Unequal Injection Rates

    Science.gov (United States)

    Xiao, Song; Dong, Peng; Zhang, Yingjie; Liu, Yanna

    2016-03-01

    In this letter, strong asymmetric coupling of two parallel exclusion processes: effect of unequal injection rates will be investigated. It is a generalization of the work of Xiao et al. (Phys. Lett. A 8, 374 (2009)), in which the particles only move on two lanes with rate 1 toward right. We can obtain the diverse phase diagram and density profiles of the system. The vertical cluster mean-field approach and extensively Monte Carlo simulations are used to study the system, and theoretical predictions are in excellent agreement with simulation results.

  16. Human sensory-evoked responses differ coincident with either "fusion-memory" or "flash-memory", as shown by stimulus repetition-rate effects

    Directory of Open Access Journals (Sweden)

    Baird Bill

    2006-02-01

    Full Text Available Abstract Background: A new method has been used to obtain human sensory evoked-responses whose time-domain waveforms have been undetectable by previous methods. These newly discovered evoked-responses have durations that exceed the time between the stimuli in a continuous stream, thus causing an overlap which, up to now, has prevented their detection. We have named them "A-waves", and added a prefix to show the sensory system from which the responses were obtained (visA-waves, audA-waves, somA-waves. Results: When A-waves were studied as a function of stimulus repetition-rate, it was found that there were systematic differences in waveshape at repetition-rates above and below the psychophysical region in which the sensation of individual stimuli fuse into a continuity. The fusion phenomena is sometimes measured by a "Critical Fusion Frequency", but for this research we can only identify a frequency-region [which we call the STZ (Sensation-Transition Zone]. Thus, the A-waves above the STZ differed from those below the STZ, as did the sensations. Study of the psychophysical differences in auditory and visual stimuli, as shown in this paper, suggest that different stimulus features are detected, and remembered, at stimulation rates above and below STZ. Conclusion: The results motivate us to speculate that: 1 Stimulus repetition-rates above the STZ generate waveforms which underlie "fusion-memory" whereas rates below the STZ show neuronal processing in which "flash-memory" occurs. 2 These two memories differ in both duration and mechanism, though they may occur in the same cell groups. 3 The differences in neuronal processing may be related to "figure" and "ground" differentiation. We conclude that A-waves provide a novel measure of neural processes that can be detected on the human scalp, and speculate that they may extend clinical applications of evoked response recordings. If A-waves also occur in animals, it is likely that A-waves will provide

  17. Wrist Pulse Rate Monitor Using Self-Injection-Locked Radar Technology

    Directory of Open Access Journals (Sweden)

    Fu-Kang Wang

    2016-10-01

    Full Text Available To achieve sensitivity, comfort, and durability in vital sign monitoring, this study explores the use of radar technologies in wearable devices. The study first detected the respiratory rates and heart rates of a subject at a one-meter distance using a self-injection-locked (SIL radar and a conventional continuous-wave (CW radar to compare the sensitivity versus power consumption between the two radars. Then, a pulse rate monitor was constructed based on a bistatic SIL radar architecture. This monitor uses an active antenna that is composed of a SIL oscillator (SILO and a patch antenna. When attached to a band worn on the subject’s wrist, the active antenna can monitor the pulse on the subject’s wrist by modulating the SILO with the associated Doppler signal. Subsequently, the SILO’s output signal is received and demodulated by a remote frequency discriminator to obtain the pulse rate information.

  18. Wrist Pulse Rate Monitor Using Self-Injection-Locked Radar Technology.

    Science.gov (United States)

    Wang, Fu-Kang; Tang, Mu-Cyun; Su, Sheng-Chao; Horng, Tzyy-Sheng

    2016-10-26

    To achieve sensitivity, comfort, and durability in vital sign monitoring, this study explores the use of radar technologies in wearable devices. The study first detected the respiratory rates and heart rates of a subject at a one-meter distance using a self-injection-locked (SIL) radar and a conventional continuous-wave (CW) radar to compare the sensitivity versus power consumption between the two radars. Then, a pulse rate monitor was constructed based on a bistatic SIL radar architecture. This monitor uses an active antenna that is composed of a SIL oscillator (SILO) and a patch antenna. When attached to a band worn on the subject's wrist, the active antenna can monitor the pulse on the subject's wrist by modulating the SILO with the associated Doppler signal. Subsequently, the SILO's output signal is received and demodulated by a remote frequency discriminator to obtain the pulse rate information.

  19. Laminar flow at a three-dimensional stagnation point with large rates of injection

    Science.gov (United States)

    Libby, P. A.

    1976-01-01

    Exact calculations of the titled flow are presented and compared to the predictions of an asymptotic analysis for large rates of injection. The inner layer of the boundary layer is found to involve outflow in both orthogonal directions whether the external flow along the y axis is inward or outward. As a result, the flow at a nearly two-dimensional stagnation point involves drastic changes as a weak outflow changes to a weak inflow. It is also found that the velocity profiles in the two directions in the inner layer are quite different.

  20. Phase-matched high-order harmonics by interaction of Ar atoms with high-repetition-rate low-energy femtosecond laser pulses

    Institute of Scientific and Technical Information of China (English)

    XIE Xinhua; ZENG Zhinan; LI Ruxin; CHEN Shu; LU Haihe; YIN Dingjun; XU Zhizhan

    2004-01-01

    Phase-matched high-order harmonic generation in Ar gas-filled cell was investigated experimentally. We obtained phase-matched 27th order harmonic driven by a commercially available solid-state femtosecond laser system at 0.55 m J/pulse energy level and 1 kHz repetition rate. To our knowledge, this is the lowest driving laser energy used to obtain phase-matched 27th order harmonic in a static gas cell. High-order harmonic generation at different gas density was studied systematically. Spectral blueshift and broadening of high harmonics under different pressure were analyzed. We found that the source size and spatial distribution of high-order harmonics are quite different under the phase-matching condition from those of the phase-mismatching case.

  1. Generation of microwave radiation by nonlinear interaction of a high-power, high-repetition rate, 1064-nm laser in KTP crystals

    CERN Document Server

    Borghesani, A F; Carugno, G

    2013-01-01

    We report measurements of microwave (RF) generation in the centimeter band accomplished by irradiating a nonlinear KTiOPO$_4$ (KTP) crystal with a home-made, infrared laser at $1064\\,$nm as a result of optical rectification (OR). The laser delivers pulse trains of duration up to $1\\,\\mu$s. Each train consists of several high-intensity pulses at an adjustable repetition rate of approximately $ 4.6\\,$GHz. The duration of the generated RF pulses is determined by that of the pulse trains. We have investigated both microwave- and second harmonic (SHG) generation as a function of the laser intensity and of the orientation of the laser polarization with respect to the crystallographic axes of KTP.

  2. PULSAR: A High-Repetition-Rate, High-Power, CE Phase-Locked Laser for the J.R. Macdonald Laboratory at Kansas State University

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Itzhak, Itzik (Itzhak) [J.R. Macdonald Laboratory, Physics Department, Kansas State University; Carnes, Kevin D. [J.R. Macdonald Laboratory, Physics Department, Kansas State University; Cocke, C. Lew [J.R. Macdonald Laboratory, Physics Department, Kansas State University; Fehrenbach, Charles W. [J.R. Macdonald Laboratory, Physics Department, Kansas State University; Kumarappan, Vinod [PULSAR: A High-Repetition-Rate, High-Power, CE Phase-Locked Laser for the J.R. Macdonald Laboratory at Kansas State University; Rudenko, Artem [J.R. Macdonald Laboratory, Physics Department, Kansas State University; Trallero, Carlos [J.R. Macdonald Laboratory, Physics Department, Kansas State University

    2014-05-09

    This instrumentation grant funded the development and installation of a state-of-the-art laser system to be used for the DOE funded research at the J.R. Macdonald Laboratory at Kansas State University. Specifically, we purchased a laser based on the KMLABs Red-Dragon design, which has a high repetition rate of 10-20 kHz crucial for multi-parameter coincidence measurements conducted in our lab. This laser system is carrier-envelope phase (CEP) locked and provides pulses as short as 21 fs directly from the amplifier (see details below). In addition, we have developed a pulse compression setup that provides sub 5 fs pulses and a CEP tagging capability that allows for long measurements of CEP dependent processes.

  3. Nanosecond pulsed power generator for a voltage amplitude up to 300 kV and a repetition rate up to 16 Hz for fine disintegration of quartz

    Energy Technology Data Exchange (ETDEWEB)

    Krastelev, E. G., E-mail: ekrastelev@yandex.ru; Sedin, A. A.; Tugushev, V. I. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2015-12-15

    A generator of high-power high-voltage nanosecond pulses is intended for electrical discharge disintegration of mineral quartz and other nonconducting minerals. It includes a 320 kV Marx pulsed voltage generator, a high-voltage glycerin-insulated coaxial peaking capacitor, and an output gas spark switch followed by a load, an electric discharge disintegration chamber. The main parameters of the generator are as follows: a voltage pulse amplitude of up to 300 kV, an output impedance of ≈10 Ω, a discharge current amplitude of up to 25 kA for a half-period of 80–90 ns, and a pulse repetition rate of up to 16 Hz.

  4. Laser ablation efficiency during the production of Ag nanoparticles in ethanol at a low pulse repetition rate (1-10 Hz)

    Science.gov (United States)

    Valverde-Alva, M. A.; García-Fernández, T.; Esparza-Alegría, E.; Villagrán-Muniz, M.; Sánchez-Aké, C.; Castañeda-Guzmán, R.; de la Mora, M. B.; Márquez-Herrera, C. E.; Sánchez Llamazares, J. L.

    2016-10-01

    We studied the effect of the repetition rate of laser pulses (RRLP) in the range from 1-10 Hz in the production of silver nanoparticles (Ag-NPs) by laser ablation in ethanol. Laser pulses with a duration of 7 ns, a wavelength of 1064 nm and an energy of 60 mJ were used to ablate a 99.99% pure silver target immersed in 10 ml of ethanol. Transmittance analysis and atomic absorption spectroscopy were used to study the silver concentration in the colloidal solutions. The ablation process was studied by measuring the transmission of the laser pulses through the colloid. It is shown that for a fixed number of laser pulses (NLP) the ablation efficiency, in terms of the ablated silver mass per laser pulse, increases with the RRLP. This result contradicts what had previously been established in the literature.

  5. Effect of pulse repetition rate and number of pulses in the analysis of polypropylene and high density polyethylene by nanosecond infrared laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Leme, Flavio O. [Laboratorio de Quimica Analitica ' Henrique Bergamin Filho' , Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, Av. Centenario 303, 13416-000 Piracicaba, SP (Brazil); Godoi, Quienly [Laboratorio de Quimica Analitica ' Henrique Bergamin Filho' , Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, Av. Centenario 303, 13416-000 Piracicaba, SP (Brazil); Departamento de Quimica, Universidade Federal de Sao Carlos, Rod. Washington Luis, km 235, 13565-905 Sao Carlos, SP (Brazil); Kiyataka, Paulo H.M. [Centro de Tecnologia de Embalagens, Instituto de Tecnologia de Alimentos, Av. Brasil 2880, 13070-178 Campinas, SP (Brazil); Santos, Dario [Departamento de Ciencias Exatas e da Terra, Universidade Federal de Sao Paulo, Rua Prof. Artur Riedel 275, 09972-270 Diadema, SP (Brazil); Agnelli, Jose A.M. [Departamento de Engenharia de Materiais, Universidade Federal de Sao Carlos, Rod. Washington Luis, km 235, 13565-905 Sao Carlos, SP (Brazil); and others

    2012-02-01

    Pulse repetition rates and the number of laser pulses are among the most important parameters that do affect the analysis of solid materials by laser induced breakdown spectroscopy, and the knowledge of their effects is of fundamental importance for suggesting analytical strategies when dealing with laser ablation processes of polymers. In this contribution, the influence of these parameters in the ablated mass and in the features of craters was evaluated in polypropylene and high density polyethylene plates containing pigment-based PbCrO{sub 4}. Surface characterization and craters profile were carried out by perfilometry and scanning electron microscopy. Area, volume and profile of craters were obtained using Taylor Map software. A laser induced breakdown spectroscopy system consisted of a Q-Switched Nd:YAG laser (1064 nm, 5 ns) and an Echelle spectrometer equipped with ICCD detector were used. The evaluated operating conditions consisted of 10, 25 and 50 laser pulses at 1, 5 and 10 Hz, 250 mJ/pulse (85 J cm{sup -2}), 2 {mu}s delay time and 6 {mu}s integration time gate. Differences in the topographical features among craters of both polymers were observed. The decrease in the repetition rate resulted in irregular craters and formation of edges, especially in polypropylene sample. The differences in the topographical features and ablated masses were attributed to the influence of the degree of crystallinity, crystalline melting temperature and glass transition temperature in the ablation process of the high density polyethylene and polypropylene. It was also observed that the intensities of chromium and lead emission signals obtained at 10 Hz were two times higher than at 5 Hz by keeping the number of laser pulses constant.

  6. Tunable Yb-doped fiber laser based on a FBG array and a theta ring resonator ensuring a constant repetition rate (Conference Presentation)

    Science.gov (United States)

    Tiess, Tobias; Becker, Martin; Rothhardt, Manfred; Bartelt, Hartmut; Jäger, Matthias L.

    2017-03-01

    Fiber lasers provide the perfect basis to develop broadly tunable lasers with high efficiency, excellent beam quality and user-friendly operation as they are increasingly demanded by applications in biophotonics and spectroscopy. Recently, a novel tuning scheme has been presented using fiber Bragg grating (FBG) arrays as fiber-integrated spectral filters containing many standard FBGs with different feedback wavelengths. Based on the discrete spectral sampling, these reflective filters uniquely enable tailored tuning ranges and broad bandwidths to be implemented into fiber lasers. Even though the first implementation of FBG arrays in pulsed tunable lasers based on a sigma ring resonators works with good emission properties, the laser wavelength is tuned by a changing repetition rate, which causes problems with applications in synchronized environments. In this work, we present a modified resonator scheme to maintain a constant repetition rate over the tuning range and still benefit from the advantages of FBG arrays as filters. With a theta ring cavity and two counter propagating filter passes, the distributed feedback of the FBG array is compensated resulting in a constant pulse round trip time for each filter wavelength. Together with an adapted gating scheme controlling the emission wavelength with a modulator, the tuning principle has been realized based on a Ytterbium-doped fiber laser. We present first experimental results demonstrating a tuning range of 25nm, high signal contrast and pulse durations of about 10ns. With the prospect of tailored tuning ranges, this pulsed fiber-integrated laser may be the basis to tackle challenging applications in spectroscopy.

  7. Very-high-flow injection rate for upper abdominal CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Masashi; Minamiguti, Hiroki; Hagihira, Takami; Kishi, Kazushi; Sato, Morio [Wakayama Medical Coll. (Japan); Shioyama, Yasukazu; Okumura, Toshiyuki; Yamada, Kouji; Kawashima, Michihisa [Central Hospital and Cancer Center of Ibaraki Prefecture, Tomobe (Japan)

    2002-06-01

    The purpose of this study was to compare a very-high-flow injection-rate method (group A) and a conventional injection-rate method (group B) for visualization of upper abdominal arteries by multidetector helical computed tomography (MDHCT). The subjects were 240 patients suspected to have abdominal lesions. They were randomly assigned to group A (120 patients) and group B (120 patients). In group A, the bilateral medial cubital veins were punctured, and contrast medium was infused at a rate of 8.6-9.6 ml/s. In group B, the unilateral medial cubital vein was punctured, and contrast medium was infused at a rate of 2.0-3.0 ml/s. The quality of vascular visualization was graded as poor, good, or excellent by three radiologists. All visualizations of the celiac trunk (CE) and superior mesenteric artery (SMA) were graded as excellent in both group A and group B. Visualization grades of the subsegmental branches of the hepatic artery (HA), right gastric artery (RGA), cystic artery, dorsal pancreatic artery (DPA), and superior pancreaticoduodenal artery (SPDA) were good or excellent in 75% (paging method)/53.3% (three-dimensional method), 85%/30%, 77.7%/18.3%, 76.7%/28.3%, and 88.3%/42.5%, respectively, in group A, and 33.3%/11.7%, 46.7%/3.4%, 41.6%/5%, 55%/4.2%, and 72.5%/14.2%, respectively, in group B. The appearance rate of intrahepatic portal branches was 28.3% in group A and 66.7% in group B in the arterial dominant phase. Group A showed better visualization results than Group B in upper abdominal arteries according to MDHCT. (author)

  8. Heart Rate Detection During Sleep Using a Flexible RF Resonator and Injection-Locked PLL Sensor.

    Science.gov (United States)

    Kim, Sung Woo; Choi, Soo Beom; An, Yong-Jun; Kim, Byung-Hyun; Kim, Deok Won; Yook, Jong-Gwan

    2015-11-01

    Novel nonintrusive technologies for wrist pulse detection have been developed and proposed as systems for sleep monitoring using three types of radio frequency (RF) sensors. The three types of RF sensors for heart rate measurement on wrist are a flexible RF single resonator, array resonators, and an injection-locked PLL resonator sensor. To verify the performance of the new RF systems, we compared heart rates between presleep time and postsleep onset time. Heart rates of ten subjects were measured using the RF systems during sleep. All three RF devices detected heart rates at 0.2 to 1 mm distance from the skin of the wrist over clothes made of cotton fabric. The wrist pulse signals of a flexible RF single resonator were consistent with the signals obtained by a portable piezoelectric transducer as a reference. Then, we confirmed that the heart rate after sleep onset time significantly decreased compared to before sleep. In conclusion, the RF system can be utilized as a noncontact nonintrusive method for measuring heart rates during sleep.

  9. Experimental study of the inverse diffusion flame using high repetition rate OH/acetone PLIF and PIV

    KAUST Repository

    Elbaz, Ayman M.

    2015-10-29

    Most previous work on inverse diffusion flames (IDFs) has focused on laminar IDF emissions and the soot formation characteristics. Here, we investigate the characteristics and structure of methane IDFs using high speed planar laser-induced fluorescence (PLIF) images of OH, particle image velocimetry (PIV), and acetone PLIF imaging for non-reacting cases. First, the flame appearance was investigated with fixed methane loading (mass flux) but with varying airflow rates, yielding a central air jet Reynolds number (Re) of 1,000 to 6,000 (when blow-off occurs). Next, it was investigated a fixed central air jet Re of 4500, but with varied methane mass flux such that the global equivalence ratio spanned 0.5 to 4. It was observed that at Re smaller than 2000, the inner air jet promotes the establishment of an inverse diffusion flame surrounded by a normal diffusion flame. However, when the Re was increased to 2500, two distinct zones became apparent in the flame, a lower entrainment zone and an upper mixing and combustion zone. 10 kHz OH-PLIF images, and 2D PIV allow the identification of the fate and spatial flame structure. Many flame features were identified and further analyzed using simple but effective image processing methods, where three types of structure in all the flames investigated here: flame holes or breaks; closures; and growing kernels. Insights about the rate of evolution of these features, the dynamics of local extinction, and the sequence of events that lead to re-ignition are reported here. In the lower entrainment zone, the occurrence of the flame break events is counterbalanced by closure events, and the edge propagation appears to control the rate at which the flame holes and closures propagate. The rate of propagation of holes was found to be statistically faster than the rate of closure. As the flames approach blow-off, flame kernels become the main mechanism for flame re-ignition further downstream. The simultaneous OH-PLIF/Stereo PIV

  10. Peach Bottom Atomic Power Station recirc pipe dose rates with zinc injection and condenser replacement

    Energy Technology Data Exchange (ETDEWEB)

    DiCello, D.C.; Odell, A.D.; Jackson, T.J. [PECO Energy Co., Delta, PA (United States)

    1995-03-01

    Peach Bottom Atomic Power Station (PBAPS) is located near the town of Delta, Pennsylvania, on the west bank of the Susquehanna River. It is situated approximately 20 miles south of Lancaster, Pennsylvania. The site contains two boiling water reactors of General Electric design and each rated at 3,293 megawatts thermal. The units are BWR 4s and went commercial in 1977. There is also a decommissioned high temperature gas-cooled reactor on site, Unit 1. PBAPS Unit 2 recirc pipe was replaced in 1985 and Unit 3 recirc pipes replaced in 1988 with 326 NGSS. The Unit 2 replacement pipe was electropolished, and the Unit 3 pipe was electropolished and passivated. The Unit 2 brass condenser was replaced with a Titanium condenser in the first quarter of 1991, and the Unit 3 condenser was replaced in the fourth quarter of 1991. The admiralty brass condensers were the source of natural zinc in both units. Zinc injection was initiated in Unit 2 in May 1991, and in Unit 3 in May 1992. Contact dose rate measurements were made in standard locations on the 28-inch recirc suction and discharge lines to determine the effectiveness of zinc injection and to monitor radiation build-up in the pipe. Additionally, HPGe gamma scans were performed to determine the isotopic composition of the oxide layer inside the pipe. In particular, the specific ({mu}Ci/cm{sup 2}) of Co-60 and Zn-65 were analyzed.

  11. A self-consistent model for the discharge kinetics in a high-repetition-rate copper-vapor laser

    Energy Technology Data Exchange (ETDEWEB)

    Carman, R.J.; Brown, D.J.W.; Piper, J.A. (Macquarie Univ., Sydney (Australia). Centre for Lasers and Applications)

    1994-08-01

    A self-consistent computer model has been developed to simulate the discharge kinetics and lasing characteristics of a copper-vapor laser (CVL) for typical operating conditions. Using a detailed rate-equation analysis, the model calculates the spatio-temporal evolution of the population densities of 11 atomic and ionic copper levels, four neon levels, and includes 70 collisional and radiative processes, in addition to radial particle transport. The long-term evolution of the plasma is taken into account by integrating the set of coupled rate equations describing the discharge and electrical circuit through multiple excitation-afterglow cycles. A time-dependent two-electron group model, based on a bi-Maxwellian electron energy distribution function, has been used to evaluate the energy partitioning between the copper vapor and the neon-buffer gas. The behavior of the plasma in the cooler end regions of the discharge tube near the electrodes, where the plasma kinetics are dominated by the buffer gas, has also been modeled. Results from the model have been compared to experimental data for a narrow-bore ([phi] = 1.8 cm) CVL operating under optimum conditions.

  12. Demonstration of a time-resolved x-ray scattering instrument utilizing the full-repetition rate of x-ray pulses at the Pohang Light Source

    Science.gov (United States)

    Jo, Wonhyuk; Eom, Intae; Landahl, Eric C.; Lee, Sooheyong; Yu, Chung-Jong

    2016-03-01

    We report on the development of a new experimental instrument for time-resolved x-ray scattering (TRXS) at the Pohang Light Source (PLS-II). It operates with a photon energy ranging from 5 to 18 keV. It is equipped with an amplified Ti:sappahire femtosecond laser, optical diagnostics, and laser beam delivery for pump-probe experiments. A high-speed single-element detector and high trigger-rate oscilloscope are used for rapid data acquisition. While this instrument is capable of measuring sub-nanosecond dynamics using standard laser pump/x-ray probe techniques, it also takes advantage of the dense 500 MHz standard fill pattern in the PLS-II storage ring to efficiently record nano-to-micro-second dynamics simultaneously. We demonstrate this capability by measuring both the (fast) impulsive strain and (slower) thermal recovery dynamics of a crystalline InSb sample following intense ultrafast laser excitation. Exploiting the full repetition rate of the storage ring results in a significant improvement in data collection rates compared to conventional bunch-tagging methods.

  13. Efficient generation of twin photons at telecom wavelengths with 2.5 GHz repetition-rate-tunable comb laser

    Science.gov (United States)

    Jin, Rui-Bo; Shimizu, Ryosuke; Morohashi, Isao; Wakui, Kentaro; Takeoka, Masahiro; Izumi, Shuro; Sakamoto, Takahide; Fujiwara, Mikio; Yamashita, Taro; Miki, Shigehito; Terai, Hirotaka; Wang, Zhen; Sasaki, Masahide

    2014-12-01

    Efficient generation and detection of indistinguishable twin photons are at the core of quantum information and communications technology (Q-ICT). These photons are conventionally generated by spontaneous parametric down conversion (SPDC), which is a probabilistic process, and hence occurs at a limited rate, which restricts wider applications of Q-ICT. To increase the rate, one had to excite SPDC by higher pump power, while it inevitably produced more unwanted multi-photon components, harmfully degrading quantum interference visibility. Here we solve this problem by using recently developed 10 GHz repetition-rate-tunable comb laser, combined with a group-velocity-matched nonlinear crystal, and superconducting nanowire single photon detectors. They operate at telecom wavelengths more efficiently with less noises than conventional schemes, those typically operate at visible and near infrared wavelengths generated by a 76 MHz Ti Sapphire laser and detected by Si detectors. We could show high interference visibilities, which are free from the pump-power induced degradation. Our laser, nonlinear crystal, and detectors constitute a powerful tool box, which will pave a way to implementing quantum photonics circuits with variety of good and low-cost telecom components, and will eventually realize scalable Q-ICT in optical infra-structures.

  14. Estimation of the dust production rate from the tungsten armour after repetitive ELM-like heat loads

    Science.gov (United States)

    Pestchanyi, S.; Garkusha, I.; Makhlaj, V.; Landman, I.

    2011-12-01

    Experimental simulations for the erosion rate of tungsten targets under ITER edge-localized mode (ELM)-like surface heat loads of 0.75 MJ m-2 causing surface melting and of 0.45 MJ m-2 without melting have been performed in the QSPA-Kh50 plasma accelerator. Analytical considerations allow us to conclude that for both energy deposition values the erosion mechanism is solid dust ejection during surface cracking under the action of thermo-stress. Tungsten influx into the ITER containment of NW~5×1018 W per medium size ELM of 0.75 MJ m-2 and 0.25 ms time duration has been estimated. The radiation cooling power of Prad=150-300 MW due to such influx of tungsten is intolerable: it should cool the ITER core to 1 keV within a few seconds.

  15. Use of Follicular Output Rate to Predict Intracytoplasmic Sperm Injection Outcome

    Science.gov (United States)

    Rehman, Rehana; Mustafa, Rozina; Baig, Mukhtiar; Arif, Sara; Hashmi, Muhammad Faisal

    2016-01-01

    Background The measurement of follicular output rate (FORT) has been proposed as a good indicator for evaluating follicular response to the exogenous recombinant folliclestimulating hormone (rFSH). This places FORT as a promising qualitative marker for ovarian function. The objective of the study was to determine FORT as a predictor of oocyte competence, embryo quality and clinical pregnancy after intracytoplasmic sperm injection (ICSI). Materials and Methods This prospective study was carried out on a group of infer- tile females (n=282) at Islamabad Clinic Serving Infertile Couples, Islamabad, Pakistan, from June 2010 till August 2013. Downregulated females were stimulated in injection gonadotropins and on ovulation induction day, pre-ovulatory follicle count (PFC) was determined using transvaginal ultrasound scan (TVUS), and FORT was determined as a ratio of PFC to antral follicle count (AFC)×100. Group I consisted of females with a negative pregnancy test, while group II had a positive pregnancy test that was confirmed with the appearance of fetal cardiac activity. Linear regression analyses of categorical variables of clinical pregnancy along with other independent variables, including FORT, were performed using SPSS version 15.0. Results Pregnancy occurred in 101/282 women who were tested, recording a clinical pregnancy rate of about 35.8%. FORT values were higher in group II as compared to group I females (P=0.0001). In multiple regression analysis, 97.7, 87.1, 78.2, and 83.4% variations were explained based on the number of retrieved oocytes per patients, number of metaphase II oocytes retrieved, number of fertilized oocytes, and number of cleaved embryos, respectively, indicating FORT as an independent predictor. Conclusion FORT is a predictor of oocyte competence in terms of a number of retrieved, mature and fertilized oocytes. It also gives information about the number of cleaved embryos and clinical pregnancy rate. PMID:27441049

  16. Comparative effect of order based resistance exercises on number of repetitions, rating of perceived exertion and muscle damage biomarkers in men

    Directory of Open Access Journals (Sweden)

    H. Arazi

    2015-12-01

    Conclusion: It can be concluded that both of the resistance exercise orders were equally effective in muscle damage parameters (CK, lactate, RPE and the average of the total number of exercise repetitions, although when the exercise session progressed, the number of repetitions performed to volitional failure decreased in last exercise in one single order, and the exercise order can influence performance.

  17. Sensitivity of CO2 storage performance to varying rates and dynamic injectivity in the Bunter Sandstone, UK

    Science.gov (United States)

    Kolster, C.; Mac Dowell, N.; Krevor, S. C.; Agada, S.

    2016-12-01

    Carbon capture and storage (CCS) is needed for meeting legally binding greenhouse gas emissions targets in the UK (ECCC 2016). Energy systems models have been key to identifying the importance of CCS but they tend to impose few constraints on the availability and use of geologic CO2 storage reservoirs. Our aim is to develop simple models that use dynamic representations of limits on CO2 storage resources. This will allow for a first order representation of the storage reservoir for use in systems models with CCS. We use the ECLIPSE reservoir simulator and a model of the Southern North Sea Bunter Sandstone saline aquifer. We analyse reservoir performance sensitivities to scenarios of varying CO2 injection demand for a future UK low carbon energy market. With 12 injection sites, we compare the impact of injecting at a constant 2MtCO2/year per site and varying this rate by a factor of 1.8 and 0.2 cyclically every 5 and 2.5 years over 50 years of injection. The results show a maximum difference in average reservoir pressure of 3% amongst each case and a similar variation in plume migration extent. This suggests that simplified models can maintain accuracy by using average rates of injection over similar time periods. Meanwhile, by initiating injection at rates limited by pressurization at the wellhead we find that injectivity steadily increases. As a result, dynamic capacity increases. We find that instead of injecting into sites on a need basis, we can strategically inject the CO2 into 6 of the deepest sites increasing injectivity for the first 15 years by 13%. Our results show injectivity as highly dependent on reservoir heterogeneity near the injection site. Injecting 1MTCO2/year into a shallow, low permeability and porosity site instead of into a deep injection site with high permeability and porosity reduces injectivity in the first 5 years by 52%. ECCC. 2016. Future of Carbon Capture and Storage in the UK. UK Parliament House of Commons, Energy and Climate Change

  18. Reservoir characterization based on tracer response and rank analysis of production and injection rates

    Energy Technology Data Exchange (ETDEWEB)

    Refunjol, B.T. [Lagoven, S.A., Pdvsa (Venezuela); Lake, L.W. [Univ. of Texas, Austin, TX (United States)

    1997-08-01

    Quantification of the spatial distribution of properties is important for many reservoir-engineering applications. But, before applying any reservoir-characterization technique, the type of problem to be tackled and the information available should be analyzed. This is important because difficulties arise in reservoirs where production records are the only information for analysis. This paper presents the results of a practical technique to determine preferential flow trends in a reservoir. The technique is a combination of reservoir geology, tracer data, and Spearman rank correlation coefficient analysis. The Spearman analysis, in particular, will prove to be important because it appears to be insightful and uses injection/production data that are prevalent in circumstances where other data are nonexistent. The technique is applied to the North Buck Draw field, Campbell County, Wyoming. This work provides guidelines to assess information about reservoir continuity in interwell regions from widely available measurements of production and injection rates at existing wells. The information gained from the application of this technique can contribute to both the daily reservoir management and the future design, control, and interpretation of subsequent projects in the reservoir, without the need for additional data.

  19. Handheld nonlinear microscope system comprising a 2 MHz repetition rate, mode-locked Yb-fiber laser for in vivo biomedical imaging.

    Science.gov (United States)

    Krolopp, Ádám; Csákányi, Attila; Haluszka, Dóra; Csáti, Dániel; Vass, Lajos; Kolonics, Attila; Wikonkál, Norbert; Szipőcs, Róbert

    2016-09-01

    A novel, Yb-fiber laser based, handheld 2PEF/SHG microscope imaging system is introduced. It is suitable for in vivo imaging of murine skin at an average power level as low as 5 mW at 200 kHz sampling rate. Amplified and compressed laser pulses having a spectral bandwidth of 8 to 12 nm at around 1030 nm excite the biological samples at a ~1.89 MHz repetition rate, which explains how the high quality two-photon excitation fluorescence (2PEF) and second harmonic generation (SHG) images are obtained at the average power level of a laser pointer. The scanning, imaging and detection head, which comprises a conventional microscope objective for beam focusing, has a physical length of ~180 mm owing to the custom designed imaging telescope system between the laser scanner mirrors and the entrance aperture of the microscope objective. Operation of the all-fiber, all-normal dispersion Yb-fiber ring laser oscillator is electronically controlled by a two-channel polarization controller for Q-switching free mode-locked operation. The whole nonlinear microscope imaging system has the main advantages of the low price of the fs laser applied, fiber optics flexibility, a relatively small, light-weight scanning and detection head, and a very low risk of thermal or photochemical damage of the skin samples.

  20. High-rate low-temperature dc pulsed magnetron sputtering of photocatalytic TiO2films: the effect of repetition frequency

    Directory of Open Access Journals (Sweden)

    Strýhal Z

    2007-01-01

    Full Text Available AbstractThe article reports on low-temperature high-rate sputtering of hydrophilic transparent TiO2thin films using dc dual magnetron (DM sputtering in Ar + O2mixture on unheated glass substrates. The DM was operated in a bipolar asymmetric mode and was equipped with Ti(99.5 targets of 50 mm in diameter. The substrate surface temperature Tsurfmeasured by a thermostrip was less than 180 °C for all experiments. The effect of the repetition frequency frwas investigated in detail. It was found that the increase of frfrom 100 to 350 kHz leads to (a an improvement of the efficiency of the deposition process that results in a significant increase of the deposition rate aDof sputtered TiO2films and (b a decrease of peak pulse voltage and sustaining of the magnetron discharge at higher target power densities. It was demonstrated that several hundreds nm thick hydrophilic TiO2films can be sputtered on unheated glass substrates at aD = 80 nm/min, Tsurf < 180 °C when high value of fr = 350 kHz was used. Properties of a thin hydrophilic TiO2film deposited on a polycarbonate substrate are given.

  1. 新型高重复频率脉冲CO2激光器%Novel high repetition-rate pulse CO2 laser

    Institute of Scientific and Technical Information of China (English)

    郑义军; 刁伟伦; 谭荣清; 王东雷; 张阔海; 黄文武; 刘世明; 李能文; 孙科; 卢远添

    2013-01-01

    A novel transversely excited atmospheric (TEA) CO2 laser with high repetition- rate was reported. The size of laser is 300 mmí300 mmí300 mm. The discharge volume is 12í103 mm3, the length of cavity is 310 mm. The ultraviolet preionization makes the discharge even and stable, the output energy can be as high as 15 mJ under the circumstance of free oscillation, and the full width at half maximum of the light pulse is 70 ns. To acquire the high wind velocity, a turbocharger was used in the system of the fast- gas flow cycle. When the pressure in the cavity is 100 kPa, the wind speed is 100 m/s, and the repetition rate of the TEA CO2 laser is up to 1.5 kHz. On the basis of preliminary experiment, the system of the grating tuning line selection can be applied to the high repetition- rate pulse laser to abtain the output of grating line selection accurately and fast.%报道了一种新型高重复频率的脉冲CO2激光器。该型激光器结构紧凑,激光器外型尺寸为300 mm×300 mm×300 mm,工作气体放电增益体积为12×103 mm3,谐振腔的长度为310 mm。为了获得大体积均匀稳定的气体放电,激光器采用了紫外电晕预电离方式。在激光器自由运转时,单脉冲激光的输出能量达到15 mJ ,输出脉冲的半高全宽为70 ns。激光器采用紧凑型高速涡轮增压风机,在一个大气压的条件下,气流循环速度超过100 m/s,激光脉冲重复频率为1.5 kHz,采用大体积强迫冷却和气体主动置换技术,可以获得较长时间激光稳定输出。在已有的实验基础上,采用光栅调谐,可快速准确地实现高重复频率脉冲CO2激光器的谱线选支输出。

  2. Effect of ethnicity on live birth rates after in vitro fertilisation or intracytoplasmic sperm injection treatment.

    Science.gov (United States)

    Jayaprakasan, K; Pandian, D; Hopkisson, J; Campbell, B K; Maalouf, W E

    2014-02-01

    To assess the relationship between the ethnicity of women and the clinical success of in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) treatment. Observational cohort study. Nottingham University Research and Treatment Unit in Reproduction (NURTURE), UK. A total of 1517 women, of which 1291 were white Europeans and 226 belonged to an ethnic minority group. All the women were undergoing their first cycle of assisted reproductive technology (ART) between 2006 and 2011. All of the women underwent their first cycle of ART between 2006 and 2011. Live birth rates following IVF or ICSI treatment. Although pre-treatment ovarian reserve variables [mean age, basal follicle stimulating hormone (FSH), and total antral follicle count] were significantly favourable in the ethnic group, the live birth rates were significantly lower in this group (35%) compared with the white European group (43.8%) (relative risk 0.8; 95% CI 0.66-0.97). On logistic regression analysis, ethnicity was an independent predictor of live birth rate (OR 0.688; 95% CI 0.513-0.924). After controlling for the other independent variables (age and FSH), the significant association between ethnicity and live birth rate remained strong (OR 0.591; 95% CI 0.425-0.822) on multivariate logistic regression analysis. Live birth rates following IVF or ICSI treatment were significantly lower in the ethnic minority group compared with white European women, which suggests that ethnicity is a major determinant of live birth following IVF treatment. © 2013 Royal College of Obstetricians and Gynaecologists.

  3. Flow Rates Measurement and Uncertainty Analysis in Multiple-Zone Water-Injection Wells from Fluid Temperature Profiles

    Directory of Open Access Journals (Sweden)

    José E. O. Reges

    2016-07-01

    Full Text Available This work is a contribution to the development of flow sensors in the oil and gas industry. It presents a methodology to measure the flow rates into multiple-zone water-injection wells from fluid temperature profiles and estimate the measurement uncertainty. First, a method to iteratively calculate the zonal flow rates using the Ramey (exponential model was described. Next, this model was linearized to perform an uncertainty analysis. Then, a computer program to calculate the injected flow rates from experimental temperature profiles was developed. In the experimental part, a fluid temperature profile from a dual-zone water-injection well located in the Northeast Brazilian region was collected. Thus, calculated and measured flow rates were compared. The results proved that linearization error is negligible for practical purposes and the relative uncertainty increases as the flow rate decreases. The calculated values from both the Ramey and linear models were very close to the measured flow rates, presenting a difference of only 4.58 m³/d and 2.38 m³/d, respectively. Finally, the measurement uncertainties from the Ramey and linear models were equal to 1.22% and 1.40% (for injection zone 1; 10.47% and 9.88% (for injection zone 2. Therefore, the methodology was successfully validated and all objectives of this work were achieved.

  4. Flow Rates Measurement and Uncertainty Analysis in Multiple-Zone Water-Injection Wells from Fluid Temperature Profiles.

    Science.gov (United States)

    Reges, José E O; Salazar, A O; Maitelli, Carla W S P; Carvalho, Lucas G; Britto, Ursula J B

    2016-07-13

    This work is a contribution to the development of flow sensors in the oil and gas industry. It presents a methodology to measure the flow rates into multiple-zone water-injection wells from fluid temperature profiles and estimate the measurement uncertainty. First, a method to iteratively calculate the zonal flow rates using the Ramey (exponential) model was described. Next, this model was linearized to perform an uncertainty analysis. Then, a computer program to calculate the injected flow rates from experimental temperature profiles was developed. In the experimental part, a fluid temperature profile from a dual-zone water-injection well located in the Northeast Brazilian region was collected. Thus, calculated and measured flow rates were compared. The results proved that linearization error is negligible for practical purposes and the relative uncertainty increases as the flow rate decreases. The calculated values from both the Ramey and linear models were very close to the measured flow rates, presenting a difference of only 4.58 m³/d and 2.38 m³/d, respectively. Finally, the measurement uncertainties from the Ramey and linear models were equal to 1.22% and 1.40% (for injection zone 1); 10.47% and 9.88% (for injection zone 2). Therefore, the methodology was successfully validated and all objectives of this work were achieved.

  5. Three-dimensional polymer nanostructures for applications in cell biology generated by high-repetition rate sub-15 fs near-infrared laser pulses

    Science.gov (United States)

    Licht, Martin; Straub, Martin; König, Karsten; Afshar, Maziar; Feili, Dara; Seidel, Helmut

    2011-03-01

    In recent years two-photon photopolymerization has emerged as a novel and extremely powerful technique of three-dimensional nanostructure formation. Complex-shaped structures can be generated using appropriate beam steering or nanopositioning systems. Here, we report on the fabrication of three-dimensional arrangements made of biocompatible polymer material, which can be used as templates for cell growth. Using three-dimensional cell cages as cell culture substrates is advantageous, as cells may develop in a more natural environment as compared to conventional planar growth methods. The two-photon fabrication experiments were carried out on a commercial microscope setup. Sub-15 fs pulsed Ti:Sapphire laser light (centre wavelength 800 nm, bandwidth 120 nm, repetition rate 85 MHz) was focused into the polymer material by a high-numerical aperture oil immersion objective. Due to the high peak intensities picojoule pulse energies in the focal spot are sufficient to polymerize the material at sub-100 nm structural element dimensions. Therefore, cell cages of sophisticated architecture can be constructed involving very fine features which take into account the specific needs of various types of cells. Ultimately, our research aims at three-dimensional assemblies of photopolymerized structural elements involving sub-100 nm features, which provide cell culture substrates far superior to those currently existing.

  6. Welding of glasses in optical and partial-optical contact via focal position adjustment of femtosecond-laser pulses at moderately high repetition rate

    Science.gov (United States)

    Tan, Hua; Duan, Ji'an

    2017-07-01

    We used 1030-nm femtosecond-laser pulses focused above/at/below the interface of two fused-silica glass substrates in optical and partial-optical contact to successfully weld them at a moderately high repetition rate of 600 kHz. Variation in the laser focal position for these two gap-distance regimes (optical and partial-optical contact) yields different bonding strengths (BSs) and machining mechanisms. The maximum bonding strength (58.2 MPa) can be achieved for a gap distance ≤λ /4 for optical-contact welding when laser focused below the interface, and the corresponding height of the welding seam was 23 μm. In addition, our results demonstrated that the "filamentation welding technique" is critical to the femtosecond-laser direct welding of glasses. Furthermore, line welding is significantly easier to realize when the femtosecond laser focuses at the interface in partial-optical-contact welding applications due to the combined effects of filamentation welding and ablation.

  7. Fast repetition rate (FRR) fluorometry: variability of chlorophyll a fluorescence yields in colonies of the corals, Montastraea faveolata (w.) and Diploria labyrinthiformes (h.) recovering from bleaching.

    Science.gov (United States)

    Lombardi; Lesser; Gorbunov

    2000-09-05

    Recently, an underwater version of a fast repetition rate fluorometer (FRRF) was developed for the non-destructive study of fluorescence yields in benthic photoautotrophs. We used an FRRF to study bleached colonies of the corals, Montastraea faveolata and Diploria labyrinthiformes at sites surrounding Lee Stocking Island, Exuma, Bahamas, to assess their recovery from bleaching ( approximately 1 year after the initial bleaching event) induced by elevated temperatures. The steady state quantum yields of chlorophyll a fluorescence (DeltaF'/F'(m)) from photosystem II (PSII) within coral colonies were separated into three categories representing visibly distinct degrees of bleaching ranging from no bleaching to completely bleached areas. Differences in DeltaF'/F'(m) were significantly different from bleached to unbleached regions within colonies. Dark, unbleached regions within colonies exhibited significantly higher DeltaF'/F'(m) values (0.438+/-0.019; mean+/-S.D.) when compared to lighter regions, and occupied a majority of the colonies' surface area (46-73%). Bleached regions exhibited significantly lower DeltaF'/F'(m) (0.337+/-0.014) and covered only 7-25% of the colonies' surface area. The observations from this study suggest that zooxanthellae in bleached regions of a colony exhibit reduced photosynthetic activity as long as one year after a bleaching event and that in situ fluorescence techniques such as FRRF are an effective means of studying coral responses and recovery from natural or anthropogenic stress in a non-destructive manner.

  8. A shock tube with a high-repetition-rate time-of-flight mass spectrometer for investigations of complex reaction systems

    Science.gov (United States)

    Dürrstein, Steffen H.; Aghsaee, Mohammad; Jerig, Ludger; Fikri, Mustapha; Schulz, Christof

    2011-08-01

    A conventional membrane-type stainless steel shock tube has been coupled to a high-repetition-rate time-of-flight mass spectrometer (HRR-TOF-MS) to be used to study complex reaction systems such as the formation of pollutants in combustion processes or formation of nanoparticles from metal containing organic compounds. Opposed to other TOF-MS shock tubes, our instrument is equipped with a modular sampling unit that allows to sample with or without a skimmer. The skimmer unit can be mounted or removed in less than 10 min. Thus, it is possible to adjust the sampling procedure, namely, the mass flux into the ionization chamber of the HRR-TOF-MS, to the experimental situation imposed by species-specific ionization cross sections and vapor pressures. The whole sampling section was optimized with respect to a minimal distance between the nozzle tip inside the shock tube and the ion source inside the TOF-MS. The design of the apparatus is presented and the influence of the skimmer on the measured spectra is demonstrated by comparing data from both operation modes for conditions typical for chemical kinetics experiments. The well-studied thermal decomposition of acetylene has been used as a test system to validate the new setup against kinetics mechanisms reported in literature.

  9. Texturing of titanium (Ti6Al4V) medical implant surfaces with MHz-repetition-rate femtosecond and picosecond Yb-doped fiber lasers.

    Science.gov (United States)

    Erdoğan, Mutlu; Öktem, Bülent; Kalaycıoğlu, Hamit; Yavaş, Seydi; Mukhopadhyay, Pranab K; Eken, Koray; Ozgören, Kıvanç; Aykaç, Yaşar; Tazebay, Uygar H; Ilday, F Ömer

    2011-05-23

    We propose and demonstrate the use of short pulsed fiber lasers in surface texturing using MHz-repetition-rate, microjoule- and sub-microjoule-energy pulses. Texturing of titanium-based (Ti6Al4V) dental implant surfaces is achieved using femtosecond, picosecond and (for comparison) nanosecond pulses with the aim of controlling attachment of human cells onto the surface. Femtosecond and picosecond pulses yield similar results in the creation of micron-scale textures with greatly reduced or no thermal heat effects, whereas nanosecond pulses result in strong thermal effects. Various surface textures are created with excellent uniformity and repeatability on a desired portion of the surface. The effects of the surface texturing on the attachment and proliferation of cells are characterized under cell culture conditions. Our data indicate that picosecond-pulsed laser modification can be utilized effectively in low-cost laser surface engineering of medical implants, where different areas on the surface can be made cell-attachment friendly or hostile through the use of different patterns.

  10. A shock tube with a high-repetition-rate time-of-flight mass spectrometer for investigations of complex reaction systems.

    Science.gov (United States)

    Dürrstein, Steffen H; Aghsaee, Mohammad; Jerig, Ludger; Fikri, Mustapha; Schulz, Christof

    2011-08-01

    A conventional membrane-type stainless steel shock tube has been coupled to a high-repetition-rate time-of-flight mass spectrometer (HRR-TOF-MS) to be used to study complex reaction systems such as the formation of pollutants in combustion processes or formation of nanoparticles from metal containing organic compounds. Opposed to other TOF-MS shock tubes, our instrument is equipped with a modular sampling unit that allows to sample with or without a skimmer. The skimmer unit can be mounted or removed in less than 10 min. Thus, it is possible to adjust the sampling procedure, namely, the mass flux into the ionization chamber of the HRR-TOF-MS, to the experimental situation imposed by species-specific ionization cross sections and vapor pressures. The whole sampling section was optimized with respect to a minimal distance between the nozzle tip inside the shock tube and the ion source inside the TOF-MS. The design of the apparatus is presented and the influence of the skimmer on the measured spectra is demonstrated by comparing data from both operation modes for conditions typical for chemical kinetics experiments. The well-studied thermal decomposition of acetylene has been used as a test system to validate the new setup against kinetics mechanisms reported in literature.

  11. High-repetition-rate and high-photon-flux 70 eV high-harmonic source for coincidence ion imaging of gas-phase molecules

    CERN Document Server

    Rothhardt, Jan; Shamir, Yariv; Tschnernajew, Maxim; Klas, Robert; Hoffmann, Armin; Tadesse, Getnet K; Klenke, Arno; Gottschall, Thomas; Eidam, Tino; Boll, Rebecca; Bomme, Cedric; Dachraoui, Hatem; Erk, Benjamin; Di Fraia, Michele; Horke, Daniel A; Kierspel, Thomas; Mullins, Terence; Przystawik, Andreas; Savelyev, Evgeny; Wiese, Joss; Laarmann, Tim; Küpper, Jochen; Rolles, Daniel; Limpert, Jens; Tünnermann, Andreas

    2016-01-01

    Unraveling and controlling chemical dynamics requires techniques to image structural changes of molecules with femtosecond temporal and picometer spatial resolution. Ultrashort-pulse x-ray free-electron lasers have significantly advanced the field by enabling advanced pump-probe schemes. There is an increasing interest in using table-top photon sources enabled by high-harmonic generation of ultrashort-pulse lasers for such studies. We present a novel high-harmonic source driven by a 100 kHz fiber laser system, which delivers 10$^{11}$ photons/s in a single 1.3 eV bandwidth harmonic at 68.6 eV. The combination of record-high photon flux and high repetition rate paves the way for time-resolved studies of the dissociation dynamics of inner-shell ionized molecules in a coincidence detection scheme. First coincidence measurements on CH$_3$I are shown and it is outlined how the anticipated advancement of fiber laser technology and improved sample delivery will, in the next step, allow pump-probe studies of ultrafas...

  12. A high-repetition rate edge localised mode replication system for the Magnum-PSI and Pilot-PSI linear devices

    Science.gov (United States)

    Morgan, T. W.; de Kruif, T. M.; van der Meiden, H. J.; van den Berg, M. A.; Scholten, J.; Melissen, W.; Krijger, B. J. M.; Bardin, S.; De Temmerman, G.

    2014-09-01

    A high-power edge-localized mode (ELM) striking onto divertor components presents one of the strongest lifetime and performance challenges for plasma facing components in future fusion reactors. A high-repetition-rate ELM replication system has been constructed and was commissioned at the Magnum-PSI linear device to investigate the synergy between steady state plasma exposure and the large increase in heat and particle flux to the plasma facing surface during repeated ELM transients in conditions aiming to mimic as closely as possible those in the ITER divertor. This system is capable of increasing the electron density and temperature from ˜1 × 1020 m-3 to ˜1 × 1021 m-3 and from 1 to 5 eV respectively, leading to a heat flux increase at the surface to ˜130 MW m-2. By combining Thomson scattering measurements with heat fluxes determined using the THEODOR code, the sheath heat transmission factor during the pulses was determined to be ≈7.7, in agreement with sheath theory. The heat flux is found to be linearly dependent upon the strength of the magnetic field at the target position, and, by adapting the system to Pilot-PSI, tests at 1.6 T showed heat fluxes of more than 600 MW m-2. This gives confidence that with the installation of a 2.5 T superconducting magnetic solenoid at Magnum-PSI the heat flux will reach the ITER-relevant gigawatt per square metre heat flux regime.

  13. High-energy femtosecond Yb-doped all-fiber monolithic chirped-pulse amplifier at repetition rate of 1 MHz

    Science.gov (United States)

    Lv, Zhi-Guo; Teng, Hao; Wang, Li-Na; Wang, Jun-Li; Wei, Zhi-Yi

    2016-09-01

    A high-energy femtosecond all ytterbium fiber amplifier based on a chirped-pulse amplification (CPA) technique at a repetition rate of 1 MHz seeded by a dispersion-management mode-locked picosecond broadband oscillator is studied. We find that the compressed pulse duration is dependent on the amplified energy, the pulse duration of 804 fs corresponds to the maximum amplified energy of 10.5 μJ, while the shortest pulse duration of 424 fs corresponds to the amplified energy of 6.75 μJ. The measured energy fluctuation is approximately 0.46% root mean square (RMS) over 2 h. The low-cost femtosecond fiber laser source with super-stability will be widely used in industrial micromachines, medical therapy, and scientific studies. Project supported by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (Grant No. 2012BAC23B03), the National Key Basic Research Program of China (Grant No. 2013CB922401), and the National Natural Science Foundation of China (Grant No. 11474002).

  14. A K-alpha x-ray source using high energy and high repetition rate laser system for phase contrast imaging.

    Science.gov (United States)

    Serbanescu, Cristina; Fourmaux, Sylvain; Kieffer, Jean-Claude; Kincaid, Russell; Krol, Andrzej

    2009-01-01

    K-alpha x-ray sources from laser produced plasmas provide completely new possibilities for x-ray phase-contrast imaging applications. By tightly focusing intense femtosecond laser pulses onto a solid target K-alpha x-ray pulses are generated through the interaction of energetic electrons created in the plasma with the bulk target. In this paper, we present a continuous and efficient Mo K-alpha x-ray source produced by a femtosecond laser system operating at 100 Hz repetition rate with maximum pulse energy of 110 mJ before compression. The source has an x-ray conversion efficiency of greater than 10(-5) into K-alpha line emission. In preparation for phase contrast imaging applications, the size of the resultant K-alpha x-ray emission spot has been also characterized. The source exhibits sufficient spatial coherence to observe phase contrast. We observe a relatively small broadening of the K-alpha source size compared to the size of the laser beam itself. Detailed characterization of the source including the x-ray spectrum and the x-ray average yield along with phase contrast images of test objects will be presented.

  15. High speed inscription of uniform, large-area laser-induced periodic surface structures in Cr films using a high repetition rate fs laser.

    Science.gov (United States)

    Ruiz de la Cruz, A; Lahoz, R; Siegel, J; de la Fuente, G F; Solis, J

    2014-04-15

    We report on the fabrication of laser-induced periodic surface structures in Cr films upon high repetition rate fs laser irradiation (up to 1 MHz, 500 fs, 1030 nm), employing beam scanning. Highly regular large-area (9  cm2) gratings with a relative diffraction efficiency of 42% can be produced within less than 6 min. The ripple period at moderate and high fluences is 0.9 μm, with a small period of 0.5 μm appearing at lower energies. The role of the irradiation parameters on the characteristics of the laser-induced periodic surface structures (LIPSS) is studied and discussed in the frame of the models presently used. We have identified the polarization vector orientation with respect to the scan direction as a key parameter for the fabrication of high-quality, large-area LIPSS, which, for perpendicular orientation, allows the coherent extension of the sub-wavelength structure over macroscopic distances. The processing strategy is robust in terms of broad parameter windows and applicable to other materials featuring LIPSS.

  16. High Repetition-Rate Neutron Generation by Several-mJ, 35 fs pulses interacting with Free-Flowing D2O

    Science.gov (United States)

    Hah, Jungmoo; Petrov, George; Nees, John; He, Zhaohan; Hammig, Mark; Krushelnick, Karl; Thomas, Alexander

    2016-10-01

    Recent advance in ultra-high power laser technology allows a development of laser-based neutron sources. Here we demonstrate heavy-water based neutron source. Using several-mJ energy pulses from a high-repetition rate (½kHz), ultrashort (35 fs) pulsed laser interacting with a 10 μm diameter stream of free-flowing heavy water (D2O), we get a 2.45 MeV neutron flux of 105/s. In the intentionally generated pre-plasma, laser pulse energy is efficiently absorbed, and energetic deuterons are generated. As a convertor, the bulk heavy water stream target and the large volume of low density D2O vapor near the target are collided with accelerated deuterons, generating neutron through d(d,n)3He reactions. As laser pulse energy increased from 6mJ to 12mJ, the neutron flux increased. From the 2D particle-in-cell simulation, comparable neutron fluxes are shown at the similar laser characteristics to the experiment. Also, simulation shows forward and backward moving deuterons, which are main distributing ions impinging upon D2O stream and vapor, respectively. This material is based upon work supported by the Air Force Office of Scien- tific Research under Award Numbers FA9550-12-1-0310 (Young Investigator Program) and FA9550-14-1-0282.

  17. Could sperm aneuploidy rate determination be used as a predictive test before intracytoplasmic sperm injection?

    Science.gov (United States)

    Petit, François M; Frydman, Nelly; Benkhalifa, Moncef; Le Du, Anne; Aboura, Azzedine; Fanchin, Renato; Frydman, Rene; Tachdjian, Gerard

    2005-01-01

    Chromosome abnormalities in embryos are a major cause of implantation and development failures. Some couples with normal karyotypes have repeated implantation failures after intracytoplasmic sperm injection (ICSI). In order to value patients at risk for genetic ICSI failures and the validity of sperm aneuploidy analysis, we have studied cytogenetic abnormalities in sperm from ICSI patients. Twenty-nine patients with normal karyotypes were included. Ten patients had at least 4 ICSI treatments without pregnancy (group A). Nine patients had a pregnancy after 1 to 3 ICSI treatments (group B). Ten fertile men with normal semen parameters were studied as controls (group C). Fluorescent in situ hybridization (FISH) was used for sperm nucleus cytogenetic analysis using chromosomes 8, 9, 13, 18, 21, X, and Y specific probes. Aneuploidy for each chromosome and diploidy rates were significantly higher in group A than in group B and in group B than in group C (P < .05). Considering each patient in groups A and B, aneuploidy rate for each chromosome was too variable to be considered as a significant test. We proposed analysis of the total sperm aneuploidy. Chromosomal sperm nuclei profile could be used as a predictive biological test before ICSI in order to improve genetic counseling for oligoasthenoteratozoospermia patients.

  18. Relationship between the length of the uterine cavity and clinical pregnancy rates after in vitro fertilization or intracytoplasmic sperm injection.

    Science.gov (United States)

    Chun, Sang Sik; Chung, Min Ji; Chong, Gun Oh; Park, Kee Sang; Lee, Taek Hoo

    2010-02-01

    In this prospective clinical study involving 354 IVF-intracytoplasmic sperm injection cycles, we determined the influence of the length of the uterine cavity on clinical pregnancy rates. Our data showed that clinical pregnancy and implantation rates are associated positively with an increased length of the uterine cavity.

  19. Association between Number of Formed Embryos, Embryo Morphology and Clinical Pregnancy Rate after Intracytoplasmic Sperm Injection.

    Science.gov (United States)

    Luz, Caroline Mantovani da; Giorgi, Vanessa Silvestre Innocenti; Coelho Neto, Marcela Alencar; Martins, Wellington de Paula; Ferriani, Rui Alberto; Navarro, Paula Andrea

    2016-09-01

    Introduction Infertility has a high prevalence in the general population, affecting ∼ 5 to 15% of couples in reproductive age. The assisted reproduction techniques (ART) include in vitro manipulation of gametes and embryos and are an important treatment indicated to these couples. It is well accepted that the implantation rate is positively influenced by the morphology of transferred embryos. However, we question if, apart from the assessment of embryo morphology, the number of produced embryos per cycle is also related to pregnancy rates in the first fresh transfer cycle. Purpose To evaluate the clinical pregnancy rate according to the number of formed embryos and the transfer of top quality embryos (TQEs). Methods In a retrospective cohort study, between January 2011 and December 2012, we evaluated women who underwent intracytoplasmic sperm injection (ICSI), aged < 40 years, and with at least 1 formed embryo fresh transferred in cleavage stage. These women were stratified into 3 groups according to the number of formed embryos (1 embryo, 2-3 and ≥ 4 embryos). Each group was divided into 2 subgroups according to the presence or not of at least 1 transferred TQE (1 with TQE; 1 without TQE; 2-3 with TQE, 2-3 without TQE; ≥ 4 with TQE; ≥ 4 without TQE). The clinical pregnancy rates were compared in each subgroup based on the presence or absence of at least one transferred TQE. Results During the study period, 636 women had at least one embryo to be transferred in the first fresh cycle (17.8% had 1 formed embryo [32.7% with TQE versus 67.3% without TQE], 42.1% of women had 2-3 formed embryos [55.6% with TQE versus 44.4% without TQE], and 40.1% of patients had ≥ 4 formed embryos [73.7% with TQE versus 26.3% without TQE]). The clinical pregnancy rate was significantly higher in the subgroup with ≥ 4 formed embryos with at least 1 transfered TQE (45.2%) compared with the subgroup without TQE (28.4%). Conclusions Having at

  20. Aseismic and seismic slip induced by fluid injection from poroelastic and rate-state friction modeling

    Science.gov (United States)

    Liu, Y.; Deng, K.; Harrington, R. M.; Clerc, F.

    2016-12-01

    Solid matrix stress change and pore pressure diffusion caused by fluid injection has been postulated as key factors for inducing earthquakes and aseismic slip on pre-existing faults. In this study, we have developed a numerical model that simulates aseismic and seismic slip in a rate-and-state friction framework with poroelastic stress perturbations from multi-stage hydraulic fracturing scenarios. We apply the physics-based model to the 2013-2015 earthquake sequences near Fox Creek, Alberta, Canada, where three magnitude 4.5 earthquakes were potentially induced by nearby hydraulic fracturing activity. In particular, we use the relocated December 2013 seismicity sequence to approximate the fault orientation, and find the seismicity migration spatiotemporally correlate with the positive Coulomb stress changes calculated from the poroelastic model. When the poroelastic stress changes are introduced to the rate-state friction model, we find that slip on the fault evolves from aseismic to seismic in a manner similar to the onset of seismicity. For a 15-stage hydraulic fracturing that lasted for 10 days, modeled fault slip rate starts to accelerate after 3 days of fracking, and rapidly develops into a seismic event, which also temporally coincides with the onset of induced seismicity. The poroelastic stress perturbation and consequently fault slip rate continue to evolve and remain high for several weeks after hydraulic fracturing has stopped, which may explain the continued seismicity after shut-in. In a comparison numerical experiment, fault slip rate quickly decreases to the interseismic level when stress perturbations are instantaneously returned to zero at shut-in. Furthermore, when stress perturbations are removed just a few hours after the fault slip rate starts to accelerate (that is, hydraulic fracturing is shut down prematurely), only aseismic slip is observed in the model. Our preliminary results thus suggest the design of fracturing duration and flow

  1. Structure and Dynamics of Fuel Jets Injected into a High-Temperature Subsonic Crossflow: High-Data-Rate Laser Diagnostic Investigation under Steady and Oscillatory Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lucht, Robert [Purdue Univ., West Lafayette, IN (United States); Anderson, William [Purdue Univ., West Lafayette, IN (United States)

    2015-01-23

    An investigation of subsonic transverse jet injection into a subsonic vitiated crossflow is discussed. The reacting jet in crossflow (RJIC) system investigated as a means of secondary injection of fuel in a staged combustion system. The measurements were performed in test rigs featuring (a) a steady, swirling crossflow and (b) a crossflow with low swirl but significant oscillation in the pressure field and in the axial velocity. The rigs are referred to as the steady state rig and the instability rig. Rapid mixing and chemical reaction in the near field of the jet injection is desirable in this application. Temporally resolved velocity measurements within the wake of the reactive jets using 2D-PIV and OH-PLIF at a repetition rate of 5 kHz were performed on the RJIC flow field in a steady state water-cooled test rig. The reactive jets were injected through an extended nozzle into the crossflow which is located in the downstream of a low swirl burner (LSB) that produced the swirled, vitiated crossflow. Both H2/N2 and natural gas (NG)/air jets were investigated. OH-PLIF measurements along the jet trajectory show that the auto-ignition starts on the leeward side within the wake region of the jet flame. The measurements show that jet flame is stabilized in the wake of the jet and wake vortices play a significant role in this process. PIV and OH–PLIF measurements were performed at five measurement planes along the cross- section of the jet. The time resolved measurements provided significant information on the evolution of complex flow structures and highly transient features like, local extinction, re-ignition, vortex-flame interaction prevalent in a turbulent reacting flow. Nanosecond-laser-based, single-laser-shot coherent anti-Stokes Raman scattering (CARS) measurements of temperature and H2 concentraiton were also performed. The structure and dynamics of a reacting transverse jet injected into a vitiated oscillatory crossflow presents a unique opportunity for

  2. Optimal scan time of dual-phase spiral CT in normal rabbit liver : effect of contrast injection rate

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Byung Kook; Kim, Sang Ho; Liu, Wei Chiang [Sungae General Hospital, Seoul (Korea, Republic of)] (and others)

    1999-06-01

    To determine the effect of contrast injection rate on rabbit liver enhancement and the optimal temporal window for dual-phase spiral CT of rabbit liver at each injection rate Using spiral CT, seven New Zealand White rabbits underwent dynamic scanning at one level of liver. Three protocols of contrast injection rates were employed, namely 0.3ml/sec(group 1), 1 ml/sec(group 2) and 2 ml/sec(group 3). During 120 seconds of total scan time, the scan interval was 3 seconds. Densities of the aorta, liver and portal vein were averaged in equivalent time. The different injection rate protocols were compared for peak enhancement/time on a time density curve. Mean peak enhancement (HU) in equivalent time(secs) was 310/18(group 1), 383/9(group 2) and 357/6(group 3) in the aorta ; 34/36, 40/36 and 41/30 in the liver ; and 135/36, 153/24 and 170/21 in the portal vein. The temporal window during the arterial phase was 12-21 sec(group 1), 6-12 sec(group 2), and 6-12 sec(group 3). The temporal window during the portal phase was from 30 sec(0.3ml/sec), 21 sec(1ml/sec) and 21sec(2ml/sec). During dual-phase spiral CT, the temporal window for liver scanning should be determined according to each contrast injection rate. A slow contrast injection rate prolongs the temporal window during the arterial phase.

  3. Efficacy of methylprednisolone sodium succinate for injection (postotic injection) on the auditory threshold and speech recognition rate of sudden deafness patients.

    Science.gov (United States)

    Li, Xin; Zhang, Xiao-Yan; Wang, Qiu-Ju; Wang, Da-Yong

    2015-01-01

    To investigate the effect of injecting the methylprednisolone in the ear for the sudden deafness and the improvement of speech discrimination test. 50 inpatients with a sudden hearing loss were recruited. Inject the methylprednisolone in the subperiosteal of the ear which is 0.5 cm distance to the ear ditch every three days. Methylprednisolone was placed for fifteen days. Simultaneously vasodilation, neurotrophic, thrombolysis and insulin hypoglycemia were administered in all patients. Pure tone test and speech discrimination test were conducted at Days 7 & 14 after intervention. The outcome was as follows: cure (n = 8), efficacy (n = 9), effect (n = 18) and no effect (n = 15) respectively. The overall effective rate of 70%. The improvement of pure tone threshold and speech discrimination had significant statistical difference (P sudden hearing loss.

  4. Fe-burden quality at high coal injection rates. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Muelheims, K.; Rosenplaenter, R.; Hess, E.; Lectard, E.; Sert, D.; Pastore, M.; Lindert, M.Te.; Matthews, T. [TKS, Duisburg (Germany)

    2002-07-01

    The aim of the project, funded by the ECSC, was to investigate the chemical and physical properties of different production and laboratory sinter and to improve the sinter quality to characterise the quality requirements for high coal injection rates in the blast furnace. Studies on synthetically prepared material have shown that softening is triggered by the initial formation of metal within the core region of partly reduced iron bearing material. The temperatures at which the deformation of pellets or sinter started do not correspond with the temperatures detected by the differential thermal analysis on single phases. From sinter pot and sinter plant test results it could be confirmed that sinter disintegration can be influenced by its chemical composition. The basicity has a dominant influence on the sinter quality. The sinter degradation decreases as the FeO content increases and the porosity decreases. Results from the melting down tests showed that the reduction of sinter at different temperatures progresses faster as the porosity increases. Further on, the beginning of the melting down temperature increases as the reduction degree increases. Pilot blast furnace trials increased confidence in the validity of the melting down test in evaluating key material parameters and assisted in establishing realistic gas/temperature reducing cycles. The ASAM tests highlighted the importance of gangue composition in determining the sinter's melting/dripping qualities.

  5. Effect of Helicobacter pylori infection on pregnancy rates and early pregnancy loss after intracytoplasmic sperm injection

    Directory of Open Access Journals (Sweden)

    Hajishafiha M

    2011-10-01

    Full Text Available Masomeh Hajishafiha1, Mohammad Ghasemi-rad1, Aishe Memari1, Siamak Naji1, Nikol Mladkova2, Vida Saeedi1 1Urmia University of Medical Sciences, Urmia, Iran; 2Institute of Cell and Molecular Science, London, UK Background: There is a need to elucidate what affects the implantation and early pregnancy course in pregnancies conceived with assisted reproductive technology (ART so that pregnancy rates and outcomes can be improved. Our aim was to determine the role of maternal Helicobacter pylori infection. Material and methods: We did a prospective study of 187 infertile couples undergoing intracytoplasmic sperm injection (ICSI and segregated those according to underlying infertility etiology. We assessed the status of H. pylori IgG antibodies and anti-CagA IgG antibodies by ELISA assay. All pregnancies were followed for early pregnancy loss (EPL, first 12 weeks. Results: The likelihood of H. pylori infection increased with age (1.01, 95% confidence interval [CI]: 1.0–1.13; P = 0.040 but there was no association with EPL. Women infected with CagA-positive strains were more likely to have EPL (19.39, 95% CI: 1.8–208.4; P = 0.014. Women with tubal factor or ovulatory disorder infertility were more likely to abort early (12.95, 95% CI: 1.28–131.11; P = 0.030, 10.84, 95% CI: 1.47–80.03; P = 0.020, respectively. There was no association between EPL and age, number of embryos formed or transferred, or number of oocytes retrieved. Conclusion: Our findings suggest that infection with CagA-positive H. pylori strains is linked to an increase in women's potential to abort early (possibly through increased release of inflammatory cytokines. In addition, tubal factor and ovulatory disorder infertility are linked to EPL after ICSI due to unknown mechanisms. Proposals to eradicate H. pylori infection prior to ICSI could lead to a decrease in EPL after ART.Keywords: Helicobacter pylori, early pregnancy loss, early abortion, infertility, intracytoplasmic sperm

  6. Spaced planar laminations formed by repetitive basal erosion and resurgence to high-sedimentation-rate regime: new insight from a bedform-like structures and laterally continuous exposures

    Science.gov (United States)

    Ishihara, Yoshiro; Yuri, Onishi; Tsuda, Keisuke; Yokokawa, Miwa

    2017-04-01

    Spaced planar laminations (SPL), or so-called traction carpet deposits, are frequently observed in deposits of sediment gravity flows. Several sedimentation models for a succession of inversely graded units have been suggested from field observations and flume experiments. The formation of the inversely graded unit could be summarized as follows: (1) abrupt sedimentation on freezing of an inversely graded layer, or (2) interruptions in flow causing a freezing of an inversely graded layer at the most basal part of flow. In either case, traction carpets as a bed load overlying the erosive boundary at the base of flow are required. Although some descriptions have reported SPLs forming antidune bedform-like structures and the association of SPLs with structureless massive deposits have not been clearly explained. In this study, we suggest a novel model of SPL formation by repetition of basal erosion and resurgence to high-sedimentation rates, based on detail examinations of SPLs both showing bedform-like structures and lateral extents of hundreds of meters. SPLs were investigated in the Mio-Pliocene Kiyosumi Formation in central Japan and the Miocene Aoshima Formation in southwest Japan. In a turbidite in the Kiyosumi Formation, SPLs show three mound-like structures, suggesting antidune bedforms with wavelengths of about 6 to 7 m. On the upcurrent flanks, SPLs show lenticular cross laminations or pinching out of units; those units do not show clear inverse grading. Rip-up mud clasts and relatively high-angle imbrications are also observed. On the other hand, SPLs on the downcurrent flanks show relatively clear inverse grading and transition downcurrent into a massive structureless bed. In the Aoshima Formation, SPLs with ca. 1 cm unit thickness continue approximately 50 m along a palaeocurrent direction without changes in thickness. These SPLs gradually transition upward into a massive structureless unit. From the observations described above, in addition to

  7. Ultra-high-resolution inelastic X-ray scattering at high-repetition-rate self-seeded X-ray free-electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Chubar, Oleg [Brookhaven National Laboratory, Upton, NY 11973 (United States); Geloni, Gianluca [European X-ray Free-Electron Laser, Albert-Einstein-Ring 19, 22761 Hamburg (Germany); Kocharyan, Vitali [Deutsches Elektronen-Synchrotron, 22761 Hamburg (Germany); Madsen, Anders [European X-ray Free-Electron Laser, Albert-Einstein-Ring 19, 22761 Hamburg (Germany); Saldin, Evgeni; Serkez, Svitozar [Deutsches Elektronen-Synchrotron, 22761 Hamburg (Germany); Shvyd’ko, Yuri, E-mail: shvydko@aps.anl.gov [Argonne National Laboratory, Argonne, IL 60439 (United States); Sutter, John [Diamond Light Source Ltd, Didcot OX11 0DE (United Kingdom)

    2016-02-12

    This article explores novel opportunities for ultra-high-resolution inelastic X-ray scattering (IXS) at high-repetition-rate self-seeded XFELs. These next-generation light sources are promising a more than three orders of magnitude increase in average spectral flux compared with what is possible with storage-ring-based radiation sources. In combination with the advanced IXS spectrometer described here, this may become a real game-changer for ultra-high-resolution X-ray spectroscopies, and hence for the studies of dynamics in condensed matter systems. Inelastic X-ray scattering (IXS) is an important tool for studies of equilibrium dynamics in condensed matter. A new spectrometer recently proposed for ultra-high-resolution IXS (UHRIX) has achieved 0.6 meV and 0.25 nm{sup −1} spectral and momentum-transfer resolutions, respectively. However, further improvements down to 0.1 meV and 0.02 nm{sup −1} are required to close the gap in energy–momentum space between high- and low-frequency probes. It is shown that this goal can be achieved by further optimizing the X-ray optics and by increasing the spectral flux of the incident X-ray pulses. UHRIX performs best at energies from 5 to 10 keV, where a combination of self-seeding and undulator tapering at the SASE-2 beamline of the European XFEL promises up to a 100-fold increase in average spectral flux compared with nominal SASE pulses at saturation, or three orders of magnitude more than what is possible with storage-ring-based radiation sources. Wave-optics calculations show that about 7 × 10{sup 12} photons s{sup −1} in a 90 µeV bandwidth can be achieved on the sample. This will provide unique new possibilities for dynamics studies by IXS.

  8. Coke, char and organic waste behaviour in the blast furnace with high injection rate

    Directory of Open Access Journals (Sweden)

    Gudenau, H. W.

    2003-10-01

    Full Text Available Blast furnace operation with low coke rate, high amount of auxiliary hydrocarbons and use of nut coke causes a change in coke quality requirements. In particular, not burned in the raceway residues of injected substances (char and ash can influence the coke behaviour. Therefore combustion efficiency of various organic wastes with and without pulverized coal injection (PCI and coal char has been investigated under the raceway simulation conditions. Mixing of various substances improves their combustion efficiency. Study on coke gasification by carbon dioxide in the presence of char showed that with the increase of char concentration, coke strength reduction becomes smaller. The reactivity of char with CO2 is higher than that of coke. Therefore char is consumed preferentially. In presence of injected char, total pore volume in coke and its wear resistance were increased. Coke reactivity and microstructure in the presence of various kinds of ash has been studied. Many ash spheres were observed on the surface of coke matrix and its size was dependent on ash properties.

    La operación del horno alto con una tasa baja de coque, una cantidad elevada de hidrocarburos auxiliares y el empleo de coque calibrado, origina un cambio en las necesidades de calidad del coque. En particular, pueden influir en el comportamiento del coque los residuos inquemados en el raceway (cavidad enfrente a las toberas del horno de las sustancias que se inyectan (char y cenizas. El char es el residuo de carbón que se origina después que el carbón libera sus sustancias volátiles. Por tanto, se ha investigado la eficiencia de la combustión de varios residuos orgánicos con y sin inyección de carbón pulverizado (ICP y char, bajo las condiciones de simulación del raceway. La mezcla de varias sustancias mejora la eficiencia a la combustión. El estudio de la gasificación del coque por el dióxido de carbono en la

  9. Intra-hippocampal injection of lipopolysaccharide inhibits kindled seizures and retards kindling rate in adult rats.

    Science.gov (United States)

    Ahmadi, Amin; Sayyah, Mohammad; Khoshkholgh-Sima, Baharak; Choopani, Samira; Kazemi, Jafar; Sadegh, Mehdi; Moradpour, Farshad; Nahrevanian, Hossein

    2013-04-01

    Neuroinflammation facilitates seizure acquisition and epileptogenesis in developing brain. Yet, the studies on impact of neuroinflammation on mature brain epileptogenesis have led to inconsistent results. Hippocampus is particularly vulnerable to damage caused by ischemia, hypoxia and trauma, and the consequent neuroinflammation, which can lead in turn to epilepsy. Lipopolysaccharide (LPS) is extensively used in experimental studies to induce neuroinflammation. In this study, effect of acute and chronic intra-CA1 infusion of LPS on amygdala-kindled seizures and epileptogenesis was examined in mature rats. LPS (5 μg/rat) inhibited evoked amygdala afterdischarges and behavioral seizures. Anticonvulsant effect of LPS was observed 0.5 h after administration and continued up to 24 h. This effect was accompanied by intra-hippocampal elevation of nitric oxide (NO), interleukin1-β, and tumor necrosis factor-α and was prevented by microglia inhibitor, naloxone, NO synthase inhibitor, Nω-nitro-L-arginine methyl ester, cyclooxygenase inhibitor, piroxicam, and interleukin1-β receptor antagonist, interleukin1-ra. Moreover, daily intra-hippocampal injection of LPS significantly retarded kindling rate. In order to further elucidate the effect of LPS on synaptic transmission and short-term plasticity, changes in field excitatory postsynaptic potentials and population spikes were measured in stratum radiatum and stratum pyramidale of LPS-treated kindled rats. LPS impaired baseline synaptic transmission in hippocampal Schaffer collateral-CA1 synapse and reduced the magnitude of paired-pulse facilitation. Our results suggest that direct suppression of presynaptic mechanisms in Schaffer collateral-CA1 synapses, as well as the inflammatory mediators released by LPS in the hippocampus, is involved in antiepileptic effect of LPS.

  10. Effect of Helicobacter pylori infection on pregnancy rates and early pregnancy loss after intracytoplasmic sperm injection.

    Science.gov (United States)

    Hajishafiha, Masomeh; Ghasemi-Rad, Mohammad; Memari, Aishe; Naji, Siamak; Mladkova, Nikol; Saeedi, Vida

    2011-01-01

    There is a need to elucidate what affects the implantation and early pregnancy course in pregnancies conceived with assisted reproductive technology (ART) so that pregnancy rates and outcomes can be improved. Our aim was to determine the role of maternal Helicobacter pylori infection. We did a prospective study of 187 infertile couples undergoing intracytoplasmic sperm injection (ICSI) and segregated those according to underlying infertility etiology. We assessed the status of H. pylori IgG antibodies and anti-CagA IgG antibodies by ELISA assay. All pregnancies were followed for early pregnancy loss (EPL, first 12 weeks). The likelihood of H. pylori infection increased with age (1.01, 95% confidence interval [CI]: 1.0-1.13; P = 0.040) but there was no association with EPL. Women infected with CagA-positive strains were more likely to have EPL (19.39, 95% CI: 1.8-208.4; P = 0.014). Women with tubal factor or ovulatory disorder infertility were more likely to abort early (12.95, 95% CI: 1.28-131.11; P = 0.030, 10.84, 95% CI: 1.47-80.03; P = 0.020, respectively). There was no association between EPL and age, number of embryos formed or transferred, or number of oocytes retrieved. Our findings suggest that infection with CagA-positive H. pylori strains is linked to an increase in women's potential to abort early (possibly through increased release of inflammatory cytokines). In addition, tubal factor and ovulatory disorder infertility are linked to EPL after ICSI due to unknown mechanisms. Proposals to eradicate H. pylori infection prior to ICSI could lead to a decrease in EPL after ART.

  11. Angular Gamma Dose Rate Distribution at the Surface of Injected Ducted Concrete Shield

    Science.gov (United States)

    Sayed Ahmed, Fikria M.; Abboud, Aida

    The shielding problems that arise due to the irregular penetrations such as neutral beam injection ducts should be treated carefully to aid in the shield design. The present work was undertaken to describe the effects arising due to radiation streaming through the neutral beam injector ducts (NBID) on the angular distribution of the total gamma ray doses at the outer surface of illmenite concrete shield ( = 4.6g/cm3). The shield is pierced with NBID of different diameters and lengths.The measurements were performed using a collimated beam of both gamma rays and neutrons emitted from one of the horizontal channels of the ET-RR-1 reactor. The measurements were carried out using 7LiF teflon thermoliminescent dosimeters. Generally the obtained data reveal that the presence of the total dose increase at the centerline of NBID and which in turn tends to decrease with the increase of scattered angle. An empirical formula describing the differential dose rate ratio is predicted. The experimental data obtained reveal good agreement with the calculated ones.Translated AbstractDie radiale Verteilung der -Dosisrate auf der Oberfläuche einer durchlöcherten BetonabschirmungAbschirmprobleme, die ihren Ursprung in irregulärem Durchlaßvermögen haben, sollten sorgfältig untersucht werden, um die Konstruktion von Abschirmungen zu unterstützen. In der vorliegenden Arbeit wird versucht, den Effekt von ausgetretener Strahlung (nach dem Mechanismus der neutralen Strahlinjektordurchführung NBID) auf die radiale Verteilung der totalen y- Strahlendosis auf der äußeren Oberfläche einer Illmenitbetonabschirmung ( = 4,6 g/cm3) aufzuzeigen. Der Schild ist mit NBID's verschiedener Längen und Durchmesser versehen. Die experimentellen Werte stimmen gut mit berechneten überein. Eine empirische Formel für die radiale Verteilung wird angegeben.

  12. Comparing the survival rate of juvenile Chinook salmon migrating through hydropower systems using injectable and surgical acoustic transmitters

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Z. D.; Martinez, J. J.; Li, H.; Harnish, R. A.; Woodley, C. M.; Hughes, J. A.; Li, X.; Fu, T.; Lu, J.; McMichael, G. A.; Weiland, M. A.; Eppard, M. B.; Skalski, J. R.; Townsend, R. L.

    2017-02-21

    Acoustic telemetry is one of the primary technologies for studying the behavior and survival of fishes throughout the world. The size and performance of the transmitters is still the key limiting factor despite that considerable effort has been expended to understand the biological effects of implantation of acoustic transmitters in yearling and subyearling Chinook salmon. The newly developed injectable transmitter is the first active acoustic tag that can be implanted via injection instead of surgery. It also lasts more than four times longer than the commercially-available transmitters. A two-part field study was conducted to evaluate the performance of the injectable transmitter and its effect on the survival of implanted fish. The injectable transmitter performed well and similarly to the other commercially-available transmitters tested. Snake River subyearling Chinook salmon smolts implanted with the injectable tag had a higher survival probability from release to each of 11 downstream detection arrays than concurrent releases of fish surgically implanted with commercially-available tags. In addition, reach-specific survival estimates were significantly higher for the injectable group in three of the eleven reaches examined. Overall, the injectable group had a 0.263 (SE = 0.017) survival probability over the entire 500 km study area compared to 0.199 (0.012) for the surgically implanted group. The differences in survival may have been caused by warm water temperatures and higher rates of infection experienced by the surgically implanted group due to the presence of sutures acting as an attachment site for pathogens. The reduction in size and ability to implant the new transmitter via injection has further reduced the tag or tagging effect bias associated with studying small fishes. The information gathered with this new technology is helping minimize the impact of dams on fish, leading to more environmentally sustainable energy systems.

  13. Effect of botulinum toxin type A injection into human masseter muscle on stimulated parotid saliva flow rate.

    Science.gov (United States)

    Kwon, J S; Kim, S T; Jeon, Y M; Choi, J H

    2009-04-01

    Botulinum toxin type A (BTX-A) injection into the masseter muscles is used to treat masseteric hypertrophy. No serious side effects of BTX-A have been reported, but patients sometimes complain of xerostomia. The aim of this study was to evaluate the effect of injecting BTX-A into the masseter for the treatment of masseteric hypertrophy on the flow of saliva from the parotid gland. 34 volunteers enrolled in this study. A total of 25 units of BTX-A was injected into each side bilaterally at two points at the center of the lower third of the masseter muscle. Saliva was collected from the parotid gland over a period of 10 min to determine the flow rate for 18 weeks after injection. The flow rate was calculated by dividing the amount in milliliters by the collection time in minutes. There were no significant changes in the stimulated parotid saliva flow at 4, 8, 12 or 18 weeks compared with the baseline. Within this limited study, it can be concluded that BTX-A injection into the masseter does not cause any significant decrease in the production of saliva from the parotid gland.

  14. Effect of intrauterine injection of human chorionic gonadotropin before embryo transfer on pregnancy rate: A prospective randomized study.

    Science.gov (United States)

    Mostajeran, Fatemeh; Godazandeh, Farzaneh; Ahmadi, Sayed Mehdi; Movahedi, Minoo; Jabalamelian, Seyed Abolfazl

    2017-01-01

    Human chorionic gonadotropin (hCG) as the most important factor to controlled implantation is one of the early embryonic signals in primates that is secreted by the embryo before its implantation. This study was designed to assess the effects of intrauterine injection of hCG before the embryo transfer in an in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) cycle on pregnancy rate in infertile patients. This randomized study was done on 100 infertile patients in two groups: intervention group received injection of 700 IU of intrauterine hCG 10 min before embryo transfer and control group did not receive hCG. The pregnancy rate was tested 2 weeks after embryo transfer, and if the pregnancy test was positive, a transvaginal ultrasound was performed 3 weeks later to search for signs of pregnancy, such as the presence of a gestational sac, embryo, and fetal heart rate, and confirmed as successful pregnancy. Pregnancy test was positive in 13 (28.6%) of 46 patients in hCG group and in control group was positive in 6 (12.5%) of 48 patients. The pregnancy rate between hCG group and control group was not significantly different (P = 0.54). The pregnancy rate in hCG group with IVF fertilization was 20.8% and in their controls was 7.4% (P = 0.51). The pregnancy rate in hCG group with ICSI fertilization was 36.4% and in their controls was 19% (P = 0.16). The intrauterine injection of 700 IU of hCG before embryo transfer improved pregnancy rate compared to control group but was not significantly different.

  15. LD-pumped high repetition rate Q-switched Nd:YVO4 laser by using La3Ga5SiO14 single crystal electro-optic modulator

    Institute of Scientific and Technical Information of China (English)

    Chunyu Wang; Huaguo Zang; Xiaoli Li; Yutian Lu; Xiaolei Zhu

    2006-01-01

    A diode-end-pumped electro-optic (EO) Q-switched Nd:YVO4 laser operating at repetition rate of 10 kpps (pulses per second) was reported. A block of La3Ga5SiO14 (LGS) single crystal was used as a Q-switch and the driver was a metal oxide semiconductor field effect transistor (MOS-FET) pulser of high repetition rate and high voltage. At continuous wave (CW) operation, the slope efficiency of the laser was 46%, and maximum optical-to-optical efficiency was 38.5%. Using an output coupler with transmission of 70%, a 10-kpps Q-switched pulse train with 0.4-mJ monopulse energy and 8.2-ns pulse width was achieved, the optical conversion efficiency was around 15%, and the beam quality M2 factor was less than 1.2.

  16. Modeling normal tissue complication probability from repetitive computed tomography scans during fractionated high-dose-rate brachytherapy and external beam radiotherapy of the uterine cervix.

    Science.gov (United States)

    Dale, E; Hellebust, T P; Skjønsberg, A; Høgberg, T; Olsen, D R

    2000-07-01

    To calculate the normal tissue complication probability (NTCP) of late radiation effects on the rectum and bladder from repetitive CT scans during fractionated high-dose-rate brachytherapy (HDRB) and external beam radiotherapy (EBRT) of the uterine cervix and compare the NTCP with the clinical frequency of late effects. Fourteen patients with cancer of the uterine cervix (Stage IIb-IVa) underwent 3-6 (mean, 4.9) CT scans in treatment position during their course of HDRB using a ring applicator with an Iridium stepping source. The rectal and bladder walls were delineated on the treatment-planning system, such that a constant wall volume independent of organ filling was achieved. Dose-volume histograms (DVH) of the rectal and bladder walls were acquired. A method of summing multiple DVHs accounting for variable dose per fraction were applied to the DVHs of HDRB and EBRT together with the Lyman-Kutcher NTCP model fitted to clinical dose-volume tolerance data from recent studies. The D(mean) of the DVH from EBRT was close to the D(max) for both the rectum and bladder, confirming that the DVH from EBRT corresponded with homogeneous whole-organ irradiation. The NTCP of the rectum was 19.7% (13.5%, 25. 9%) (mean and 95% confidence interval), whereas the clinical frequency of late rectal sequelae (Grade 3-4, RTOG/EORTC) was 13% based on material from 200 patients. For the bladder the NTCP was 61. 9% (46.8%, 76.9%) as compared to the clinical frequency of Grade 3-4 late effects of 14%. If only 1 CT scan from HDRB was assumed available, the relative uncertainty (standard deviation or SD) of the NTCP value for an arbitrary patient was 20-30%, whereas 4 CT scans provided an uncertainty of 12-13%. The NTCP for the rectum was almost consistent with the clinical frequency of late effects, whereas the NTCP for bladder was too high. To obtain reliable (SD of 12-13%) NTCP values, 3-4 CT scans are needed during 5-7 fractions of HDRB treatments.

  17. Quasi-flat-top frequency-doubled Nd:glass laser for pumping of high-power Ti:sapphire amplifiers at a 0.1 Hz repetition rate.

    Science.gov (United States)

    Yanovsky, Victor; Kalinchenko, Galina; Rousseau, Pascal; Chvykov, Vladimir; Mourou, Gerard; Krushelnick, Karl

    2008-04-20

    A Nd:glass laser based on a novel design delivers up to 120 J energy pulses with a quasi-flat-top spatial profile at a 0.1 Hz repetition rate. The laser output is frequency-doubled with 50% efficiency and used to pump Ti:sapphire amplifiers. The developed design is perspective for use in the currently contemplated next step in ultra-high-intensity laser development.

  18. Stable mode-locked operation of a low repetition rate diode-pumped Nd:GdVO4 laser by combining quadratic polarisation switching and a semiconductor saturable absorber mirror.

    Science.gov (United States)

    Gerhard, Christoph; Druon, Frédéric; Georges, Patrick; Couderc, Vincent; Leproux, Philippe

    2006-08-07

    In this paper, we present the mode-locked operation of an ultra-robustly stabilised Nd:GdVO(4) laser with low repetition rate by combining quadratic polarisation switching and a semiconductor saturable absorber mirror (SESAM). In addition, similar experiment was also done with Nd:YVO(4). For Nd:GdVO(4), 16-ps pulses at 1063 nm with a repetition rate of 3.95 MHz have been obtained for a laser average output power of 1.4 W. For Nd:YVO(4), the performance was 2.5 W of average power for 15-ps pulses at 1064 nm. Moreover, we demonstrate experimentally the advantage of combining these two passive mode locking techniques in terms of stability ranges. We show how the dual mode-locking technique is crucial to obtain a stable and long-term mode-locked regime in our case of a diode-pumped Nd:GdVO(4) laser operating at low repetition rate and more generally how this dual mode-locking technique improves the stability range of the mode-locked operation giving more flexibility on different parameters.

  19. Task Repetition and Second Language Speech Processing

    Science.gov (United States)

    Lambert, Craig; Kormos, Judit; Minn, Danny

    2017-01-01

    This study examines the relationship between the repetition of oral monologue tasks and immediate gains in L2 fluency. It considers the effect of aural-oral task repetition on speech rate, frequency of clause-final and midclause filled pauses, and overt self-repairs across different task types and proficiency levels and relates these findings to…

  20. 40 CFR 60.1820 - How do I monitor the injection rate of activated carbon?

    Science.gov (United States)

    2010-07-01

    ... activated carbon? 60.1820 Section 60.1820 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or mercury emissions, you must meet three requirements: (a) Select a carbon injection system...

  1. Repetitive maladaptive behavior: beyond repetition compulsion.

    Science.gov (United States)

    Bowins, Brad

    2010-09-01

    Maladaptive behavior that repeats, typically known as repetition compulsion, is one of the primary reasons that people seek psychotherapy. However, even with psychotherapeutic advances it continues to be extremely difficult to treat. Despite wishes and efforts to the contrary repetition compulsion does not actually achieve mastery, as evidenced by the problem rarely resolving without therapeutic intervention, and the difficulty involved in producing treatment gains. A new framework is proposed, whereby such behavior is divided into behavior of non-traumatic origin and traumatic origin with some overlap occurring. Repetitive maladaptive behavior of non-traumatic origin arises from an evolutionary-based process whereby patterns of behavior frequently displayed by caregivers and compatible with a child's temperament are acquired and repeated. It has a familiarity and ego-syntonic aspect that strongly motivates the person to retain the behavior. Repetitive maladaptive behavior of traumatic origin is characterized by defensive dissociation of the cognitive and emotional components of trauma, making it very difficult for the person to integrate the experience. The strong resistance of repetitive maladaptive behavior to change is based on the influence of both types on personality, and also factors specific to each. Psychotherapy, although very challenging at the best of times, can achieve the mastery wished and strived for, with the aid of several suggestions provided.

  2. Computational Fluid Dynamics (CFD) Modeling for High Rate Pulverized Coal Injection (PCI) into the Blast Furnace

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Chenn Zhou

    2008-10-15

    Pulverized coal injection (PCI) into the blast furnace (BF) has been recognized as an effective way to decrease the coke and total energy consumption along with minimization of environmental impacts. However, increasing the amount of coal injected into the BF is currently limited by the lack of knowledge of some issues related to the process. It is therefore important to understand the complex physical and chemical phenomena in the PCI process. Due to the difficulty in attaining trus BF measurements, Computational fluid dynamics (CFD) modeling has been identified as a useful technology to provide such knowledge. CFD simulation is powerful for providing detailed information on flow properties and performing parametric studies for process design and optimization. In this project, comprehensive 3-D CFD models have been developed to simulate the PCI process under actual furnace conditions. These models provide raceway size and flow property distributions. The results have provided guidance for optimizing the PCI process.

  3. Synthetic modeling of a fluid injection-induced fault rupture with slip-rate dependent friction coefficient

    Science.gov (United States)

    Urpi, Luca; Rinaldi, Antonio Pio; Rutqvist, Jonny; Cappa, Frédéric; Spiers, Christopher J.

    2016-04-01

    Poro-elastic stress and effective stress reduction associated with deep underground fluid injection can potentially trigger shear rupture along pre-existing faults. We modeled an idealized CO2 injection scenario, to assess the effects on faults of the first phase of a generic CO2 aquifer storage operation. We used coupled multiphase fluid flow and geomechanical numerical modeling to evaluate the stress and pressure perturbations induced by fluid injection and the response of a nearby normal fault. Slip-rate dependent friction and inertial effects have been aken into account during rupture. Contact elements have been used to take into account the frictional behavior of the rupture plane. We investigated different scenarios of injection rate to induce rupture on the fault, employing various fault rheologies. Published laboratory data on CO2-saturated intact and crushed rock samples, representative of a potential target aquifer, sealing formation and fault gouge, have been used to define a scenario where different fault rheologies apply at different depths. Nucleation of fault rupture takes place at the bottom of the reservoir, in agreement with analytical poro-elastic stress calculations, considering injection-induced reservoir inflation and the tectonic scenario. For the stress state here considered, the first triggered rupture always produces the largest rupture length and slip magnitude, correlated with the fault rheology. Velocity weakening produces larger ruptures and generates larger magnitude seismic events. Heterogeneous faults have been considered including velocity-weakening or velocity strengthening sections inside and below the aquifer, while upper sections being velocity-neutral. Nucleation of rupture in a velocity strengthening section results in a limited rupture extension, both in terms of maximum slip and rupture length. For a heterogeneous fault with nucleation in a velocity-weakening section, the rupture may propagate into the overlying velocity

  4. The regulatory system for diabetes mellitus: Modeling rates of glucose infusions and insulin injections

    Science.gov (United States)

    Yang, Jin; Tang, Sanyi; Cheke, Robert A.

    2016-08-01

    Novel mathematical models with open and closed-loop control for type 1 or type 2 diabetes mellitus were developed to improve understanding of the glucose-insulin regulatory system. A hybrid impulsive glucose-insulin model with different frequencies of glucose infusions and insulin injections was analyzed, and the existence and uniqueness of the positive periodic solution for type 1 diabetes, which is globally asymptotically stable, was studied analytically. Moreover, permanence of the system for type 2 diabetes was demonstrated which showed that the glucose concentration level is uniformly bounded above and below. To investigate how to prevent hyperinsulinemia and hyperglycemia being caused by this system, we developed a model involving periodic intakes of glucose with insulin injections applied only when the blood glucose level reached a given critical glucose threshold. In addition, our numerical analysis revealed that the period, the frequency and the dose of glucose infusions and insulin injections are crucial for insulin therapies, and the results provide clinical strategies for insulin-administration practices.

  5. Assessing Rates of Global Warming Emissions from Port- Fuel Injection and Gasoline Direct Injection Engines in Light-Duty Passenger Vehicles

    Science.gov (United States)

    Short, D.; , D., Vi; Durbin, T.; Karavalakis, G.; Asa-Awuku, A. A.

    2013-12-01

    Passenger vehicles are known emitters of climate warming pollutants. CO2 from automobile emissions are an anthropogenic greenhouse gas (GHG) and a large contributor to global warming. Worldwide, CO2 emissions from passenger vehicles are responsible for 11% of the total CO2 emissions inventory. Black Carbon (BC), another common vehicular emission, may be the second largest contributor to global warming (after CO2). Currently, 52% of BC emissions in the U.S are from the transportation sector, with ~10% originating from passenger vehicles. The share of pollutants from passenger gasoline vehicles is becoming larger due to the reduction of BC from diesel vehicles. Currently, the majority of gasoline passenger vehicles in the United States have port- fuel injection (PFI) engines. Gasoline direct injection (GDI) engines have increased fuel economy compared to the PFI engine. GDI vehicles are predicted to dominate the U.S. passenger vehicle market in the coming years. The method of gasoline injection into the combustion chamber is the primary difference between these two technologies, which can significantly impact primary emissions from light-duty vehicles (LDV). Our study will measure LDV climate warming emissions and assess the impact on climate due to the change in U.S vehicle technologies. Vehicles were tested on a light- duty chassis dynamometer for emissions of CO2, methane (CH4), and BC. These emissions were measured on F3ederal and California transient test cycles and at steady-state speeds. Vehicles used a gasoline blend of 10% by volume ethanol (E10). E10 fuel is now found in 95% of gasoline stations in the U.S. Data is presented from one GDI and one PFI vehicle. The 2012 Kia Optima utilizes GDI technology and has a large market share of the total GDI vehicles produced in the U.S. In addition, The 2012 Toyota Camry, equipped with a PFI engine, was the most popular vehicle model sold in the U.S. in 2012. Methane emissions were ~50% lower for the GDI technology

  6. Grammatical Change through Repetition.

    Science.gov (United States)

    Arevart, Supot

    1989-01-01

    The effect of repetition on grammatical change in an unrehearsed talk is examined based on a case study of a single learner. It was found that repetition allows for accuracy monitoring in that errors committed in repeated contexts undergo correction. Implications for teaching are discussed. (23 references) (LB)

  7. The Negative Repetition Effect

    Science.gov (United States)

    Mulligan, Neil W.; Peterson, Daniel J.

    2013-01-01

    A fundamental property of human memory is that repetition enhances memory. Peterson and Mulligan (2012) recently documented a surprising "negative repetition effect," in which participants who studied a list of cue-target pairs twice recalled fewer targets than a group who studied the pairs only once. Words within a pair rhymed, and…

  8. Ultrafast high-repetition imaging of fuel sprays using picosecond fiber laser.

    Science.gov (United States)

    Purwar, Harsh; Wang, Hongjie; Tang, Mincheng; Idlahcen, Saïd; Rozé, Claude; Blaisot, Jean-Bernard; Godin, Thomas; Hideur, Ammar

    2015-12-28

    Modern diesel injectors operate at very high injection pressures of about 2000 bar resulting in injection velocities as high as 700 m/s near the nozzle outlet. In order to better predict the behavior of the atomization process at such high pressures, high-resolution spray images at high repetition rates must be recorded. However, due to extremely high velocity in the near-nozzle region, high-speed cameras fail to avoid blurring of the structures in the spray images due to their exposure time. Ultrafast imaging featuring ultra-short laser pulses to freeze the motion of the spray appears as an well suited solution to overcome this limitation. However, most commercial high-energy ultrafast sources are limited to a few kHz repetition rates. In the present work, we report the development of a custom-designed picosecond fiber laser generating ∼ 20 ps pulses with an average power of 2.5 W at a repetition rate of 8.2 MHz, suitable for high-speed imaging of high-pressure fuel jets. This fiber source has been proof tested by obtaining backlight images of diesel sprays issued from a single-orifice injector at an injection pressure of 300 bar. We observed a consequent improvement in terms of image resolution compared to standard white-light illumination. In addition, the compactness and stability against perturbations of our fiber laser system makes it particularly suitable for harsh experimental conditions.

  9. Roles of repetitive sequences

    Energy Technology Data Exchange (ETDEWEB)

    Bell, G.I.

    1991-12-31

    The DNA of higher eukaryotes contains many repetitive sequences. The study of repetitive sequences is important, not only because many have important biological function, but also because they provide information on genome organization, evolution and dynamics. In this paper, I will first discuss some generic effects that repetitive sequences will have upon genome dynamics and evolution. In particular, it will be shown that repetitive sequences foster recombination among, and turnover of, the elements of a genome. I will then consider some examples of repetitive sequences, notably minisatellite sequences and telomere sequences as examples of tandem repeats, without and with respectively known function, and Alu sequences as an example of interspersed repeats. Some other examples will also be considered in less detail.

  10. Roles of repetitive sequences

    Energy Technology Data Exchange (ETDEWEB)

    Bell, G.I.

    1991-12-31

    The DNA of higher eukaryotes contains many repetitive sequences. The study of repetitive sequences is important, not only because many have important biological function, but also because they provide information on genome organization, evolution and dynamics. In this paper, I will first discuss some generic effects that repetitive sequences will have upon genome dynamics and evolution. In particular, it will be shown that repetitive sequences foster recombination among, and turnover of, the elements of a genome. I will then consider some examples of repetitive sequences, notably minisatellite sequences and telomere sequences as examples of tandem repeats, without and with respectively known function, and Alu sequences as an example of interspersed repeats. Some other examples will also be considered in less detail.

  11. Migration rates and formation injectivity to determine containment time scales of sequestered carbon dioxide

    Science.gov (United States)

    Burke, Lauri

    2012-01-01

    Supercritical carbon dioxide exhibits highly variable behavior over a range of reservoir pressure and temperature conditions. Because geologic sequestration of supercritical carbon dioxide is targeted for subsurface injection and containment at depths ranging from approximately 3,000 to 13,000 feet, the investigation into the physical properties of this fluid can be restricted to the pressure and temperature conditions likely encountered in the sedimentary strata within this depth interval. A petrophysical based approach was developed to study the widest range of formation properties potentially encountered in sedimentary strata. Fractional porosities were varied from 5 to 95 percent, in 5-percent increments, and permeability values were varied over thirteen orders of magnitude, from 10.0 darcys down to 1.0 picodarcy.

  12. 50-GHz repetition-rate, 280-fs pulse generation at 100-mW average power from a mode-locked laser diode externally compressed in a pedestal-free pulse compressor

    Science.gov (United States)

    Tamura, Kohichi R.; Sato, Kenji

    2002-07-01

    280-fs pedestal-free pulses are generated at average output powers exceeding 100 mW at a repetition rate of 50 GHz by compression of the output of a mode-locked laser diode (MLLD) by use of a pedestal-free pulse compressor (PFPC). The MLLD consists of a monolithically integrated chirped distributed Bragg reflector, a gain section, and an electroabsorption modulator. The PFPC is composed of a dispersion-flattened dispersion-decreasing fiber and a dispersion-flattened dispersion-imbalanced nonlinear optical loop mirror. Frequency modulation for linewidth broadening is used to overcome the power limitation imposed by stimulated Brillouin scattering.

  13. Repetition and Translation Shifts

    Directory of Open Access Journals (Sweden)

    Simon Zupan

    2006-06-01

    Full Text Available Repetition manifests itself in different ways and at different levels of the text. The first basic type of repetition involves complete recurrences; in which a particular textual feature repeats in its entirety. The second type involves partial recurrences; in which the second repetition of the same textual feature includes certain modifications to the first occurrence. In the article; repetitive patterns in Edgar Allan Poe’s short story “The Fall of the House of Usher” and its Slovene translation; “Konec Usherjeve hiše”; are compared. The author examines different kinds of repetitive patterns. Repetitions are compared at both the micro- and macrostructural levels. As detailed analyses have shown; considerable microstructural translation shifts occur in certain types of repetitive patterns. Since these are not only occasional; sporadic phenomena; but are of a relatively high frequency; they reduce the translated text’s potential for achieving some of the gothic effects. The macrostructural textual property particularly affected by these shifts is the narrator’s experience as described by the narrative; which suffers a reduction in intensity.

  14. Controlled Isotropic and Anisotropic Shell Growth in β-NaLnF4 Nanocrystals Induced by Precursor Injection Rate.

    Science.gov (United States)

    Fischer, Stefan; Swabeck, Joseph K; Alivisatos, A Paul

    2017-09-06

    Precise morphology and composition control is vital for designing multifunctional lanthanide-doped core/shell nanocrystals. Herein, we report controlled isotropic and anisotropic shell growth techniques in hexagonal sodium rare-earth tetrafluoride (β-NaLnF4) nanocrystals by exploiting the kinetics of the shell growth. A drastic change of the shell morphology was observed by changing the injection rate of the shell precursors while keeping all other reaction conditions constant. We obtained isotropic shell growth for fast sequential injection and a preferred growth of the shell layers along the crystal's c-axis [001] for slow dropwise injection. Using this slow shell growth technique, we have grown rod-like shells around different almost spherical core nanocrystals. Bright and efficient upconversion was measured for both isotropic and rod-like shells around β-NaYF4 nanocrystals doped with Yb(3+)/Er(3+) and Yb(3+)/Tm(3+). Photoluminescence upconversion quantum yield and lifetime measurements reveal the high quality of the core/shell nanocrystal. Furthermore, multishell rod-like nanostructures have been prepared with optically active cores and tips separated by an inert intermediate shell layer. The controlled anisotropic shell growth allows the design of new core/multishell nanostructures and enables independent investigations of the chemistry and physics of different nanocrystal facets.

  15. Effects of cooling rate on vermicular graphite percentage in a brake drum produced by one-step cored wire injection

    Directory of Open Access Journals (Sweden)

    Yu-shuang Feng

    2015-09-01

    Full Text Available In this research, a vermicular graphite cast iron brake drum was produced by cored wire injection in a one-step method. Silica sand and low-density alumina-silicate ceramic were used as molding materials in order to investigate the effect of cooling rate on percentage of vermicular graphite and mechanical properties of the brake drum casting. Several thermocouples were inserted into the casting in the desired positions to measure the temperature change. By means of one-step cored wire injection, the two residual concentrations of Mg and RE were effectively controlled in the ranges of 0.013%-0.017% and 0.019%-0.025%, respectively, which are crucial for the production of vermicular graphite cast iron and the formation of vermicular graphite. In addition, the cooling rate had a significant effect on the vermicular graphite percentage. In the case of the silica mold brake drum casting, there was an obvious difference in the cooling rate with the wall change, leading to a change in vermicular graphite percentage from 70.8% to 90%. In the low-density alumina-silicate ceramic mold casting, no obvious change in temperature was detected by the thermocouples and the percentage of the vermicular graphite was stable at 85%. Therefore, the vermicular graphite cast iron brake drum with a better combination of mechanical properties could be obtained.

  16. Applying data mining techniques for increasing implantation rate by selecting best sperms for intra-cytoplasmic sperm injection treatment.

    Science.gov (United States)

    Mirroshandel, Seyed Abolghasem; Ghasemian, Fatemeh; Monji-Azad, Sara

    2016-12-01

    Aspiration of a good-quality sperm during intracytoplasmic sperm injection (ICSI) is one of the main concerns. Understanding the influence of individual sperm morphology on fertilization, embryo quality, and pregnancy probability is one of the most important subjects in male factor infertility. Embryologists need to decide the best sperm for injection in real time during ICSI cycle. Our objective is to predict the quality of zygote, embryo, and implantation outcome before injection of each sperm in an ICSI cycle for male factor infertility with the aim of providing a decision support system on the sperm selection. The information was collected from 219 patients with male factor infertility at the infertility therapy center of Alzahra hospital in Rasht from 2012 through 2014. The prepared dataset included the quality of zygote, embryo, and implantation outcome of 1544 injected sperms into the related oocytes. In our study, embryo transfer was performed at day 3. Each sperm was represented with thirteen clinical features. Data preprocessing was the first step in the proposed data mining algorithm. After applying more than 30 classifiers, 9 successful classifiers were selected and evaluated by 10-fold cross validation technique using precision, recall, F1, and AUC measures. Another important experiment was measuring the effect of each feature in prediction process. In zygote and embryo quality prediction, IBK and RandomCommittee models provided 79.2% and 83.8% F1, respectively. In implantation outcome prediction, KStar model achieved 95.9% F1, which is even better than prediction of human experts. All these predictions can be done in real time. A machine learning-based decision support system would be helpful in sperm selection phase of ICSI cycle to improve the success rate of ICSI treatment. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. Precision markedly attenuates repetitive lift capacity.

    Science.gov (United States)

    Collier, Brooke R; Holland, Laura; McGhee, Deirdre; Sampson, John A; Bell, Alison; Stapley, Paul J; Groeller, Herbert

    2014-01-01

    This study investigated the effect of precision on time to task failure in a repetitive whole-body manual handling task. Twelve participants were required to repetitively lift a box weighing 65% of their single repetition maximum to shoulder height using either precise or unconstrained box placement. Muscle activity, forces exerted at the ground, 2D body kinematics, box acceleration and psychophysical measures of performance were recorded until task failure was reached. With precision, time to task failure for repetitive lifting was reduced by 72%, whereas the duration taken to complete a single lift and anterior deltoid muscle activation increased by 39% and 25%, respectively. Yet, no significant difference was observed in ratings of perceived exertion or heart rate at task failure. In conclusion, our results suggest that when accuracy is a characteristic of a repetitive manual handling task, physical work capacity will decline markedly. The capacity to lift repetitively to shoulder height was reduced by 72% when increased accuracy was required to place a box upon a shelf. Lifting strategy and muscle activity were also modified, confirming practitioners should take into consideration movement precision when evaluating the demands of repetitive manual handling tasks.

  18. Diagnosis of high-repetition-rate pulse laser with pyroelectric detector%基于热释电探测器的重频脉冲激光诊断

    Institute of Scientific and Technical Information of China (English)

    张磊; 邵碧波; 杨鹏翎; 王振宝; 闫燕

    2011-01-01

    Based on the working principles of a pyroelectric detector, the transient response of the detector to the pulse laser is researched. The model of pyroelectric detector is built, and the response in practical application is simulated according to the parameters of materials and structures. Signal process circuits which are suitable for a high-repetition-rate pulse laser are designed. Finally', a number of the repetition frequency laser radiation experiments on the pyroelectric detector are carried out. The experiments on frequency response and pulse width of the detector are completed, and the feasibility of applying the pyroelectric detector to the energy measurement of the high-repetition-rate and narrow pulse laser is verified.%摘以热释电探测器的工作原理为基础,研究了热释电探测器对重频脉冲激光的瞬态响应特性,建立了热释电探测器对单脉冲激光辐照响应的工作模型,分析了影响探测器频率特性的主要因素。根据材料和结构参数模拟计算了实际应用中的响应模型。设计了信号检测电路并对其进行计算仿事。完成了探测器的频率响应、脉宽响应等实验测量,验证了热释电探测器用于高重频、窄脉冲激光能量测量的可行性。

  19. Perceptual Repetition Blindness Effects

    Science.gov (United States)

    Hochhaus, Larry; Johnston, James C.; Null, Cynthia H. (Technical Monitor)

    1994-01-01

    The phenomenon of repetition blindness (RB) may reveal a new limitation on human perceptual processing. Recently, however, researchers have attributed RB to post-perceptual processes such as memory retrieval and/or reporting biases. The standard rapid serial visual presentation (RSVP) paradigm used in most RB studies is, indeed, open to such objections. Here we investigate RB using a "single-frame" paradigm introduced by Johnston and Hale (1984) in which memory demands are minimal. Subjects made only a single judgement about whether one masked target word was the same or different than a post-target probe. Confidence ratings permitted use of signal detection methods to assess sensitivity and bias effects. In the critical condition for RB a precue of the post-target word was provided prior to the target stimulus (identity precue), so that the required judgement amounted to whether the target did or did not repeat the precue word. In control treatments, the precue was either an unrelated word or a dummy.

  20. Endometriosis, Ovarian Reserve and Live Birth Rate Following In Vitro Fertilization/Intracytoplasmic Sperm Injection.

    Science.gov (United States)

    Coelho Neto, Marcela Alencar; Martins, Wellington de Paula; Luz, Caroline Mantovani da; Jianini, Bruna Talita Gazeto Melo; Ferriani, Rui Alberto; Navarro, Paula Andrea

    2016-05-01

    Purpose To evaluate whether women with endometriosis have different ovarian reserves and reproductive outcomes when compared with women without this diagnosis undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI), and to compare the reproductive outcomes between women with and without the diagnosis considering the ovarian reserve assessed by antral follicle count (AFC). Methods This retrospective cohort study evaluated all women who underwent IVF/ICSI in a university hospital in Brazil between January 2011 and December 2012. All patients were followed up until a negative pregnancy test or until the end of the pregnancy. The primary outcomes assessed were number of retrieved oocytes and live birth. Women were divided into two groups according to the diagnosis of endometriosis, and each group was divided again into a group that had AFC ≤ 6 (poor ovarian reserve) and another that had AFC ≥ 7 (normal ovarian reserve). Continuous variables with normal distribution were compared using unpaired t-test, and those without normal distribution, using Mann-Whitney test. Binary data were compared using either Fisher's exact test or Chi-square (χ(2)) test. The significance level was set as p live birth was similar between women with the diagnosis of endometriosis and those without it (19.1 versus 22.5%), and also when considering only women with a poor ovarian reserve (9.4 versus 8.9%) and only those with a normal ovarian reserve (25.5 versus 26.5%). Conclusions Women diagnosed with endometriosis are more likely to have a poor ovarian reserve; however, their chance of conceiving by IVF/ICSI is similar to the one observed in patients without endometriosis and with a comparable ovarian reserve. Thieme Publicações Ltda Rio de Janeiro, Brazil.

  1. Trialogue: Preparation, Repetition and...

    Science.gov (United States)

    Oberg, Antoinette; And Others

    1996-01-01

    This paper interrogates both curriculum theory and the limits and potentials of textual forms. A set of overlapping discourses (a trialogue) focuses on inquiring into the roles of obsession and repetition in creating deeply interpretive locations for understanding. (SM)

  2. Pulsed UV-C disinfection of Escherichia coli with light-emitting diodes, emitted at various repetition rates and duty cycles.

    Science.gov (United States)

    Wengraitis, Stephen; McCubbin, Patrick; Wade, Mary Margaret; Biggs, Tracey D; Hall, Shane; Williams, Leslie I; Zulich, Alan W

    2013-01-01

    A 2010 study exposed Staphylococcus aureus to ultraviolet (UV) radiation and thermal heating from pulsed xenon flash lamps. The results suggested that disinfection could be caused not only by photochemical changes from UV radiation, but also by photophysical stress damage caused by the disturbance from incoming pulses. The study called for more research in this area. The recent advances in light-emitting diode (LED) technology include the development of LEDs that emit in narrow bands in the ultraviolet-C (UV-C) range (100-280 nm), which is highly effective for UV disinfection of organisms. Further, LEDs would use less power, and allow more flexibility than other sources of UV energy in that the user may select various pulse repetition frequencies (PRFs), pulse irradiances, pulse widths, duty cycles and types of waveform output (e.g. square waves, sine waves, triangular waves, etc.). Our study exposed Escherichia coli samples to square pulses of 272 nm radiation at various PRFs and duty cycles. A statistically significant correlation was found between E. coli's disinfection sensitivity and these parameters. Although our sample size was small, these results show promise and are worthy of further investigation. Comparisons are also made with pulsed disinfection by LEDs emitting at 365 nm, and pulsed disinfection by xenon flash lamps. © 2012 U.S. Government. Photochemistry and Photobiology © 2012 The American Society of Photobiology.

  3. Tachyphylaxis associated with repeated epidural injections of lidocaine is not related to changes in distribution or the rate of elimination from the epidural space

    DEFF Research Database (Denmark)

    Mogensen, T; Simonsen, L; Scott, N B

    1989-01-01

    technetium-99m diethylenetriaminepentaacetate [99mTc-DTPA]) and elimination of lidocaine from the epidural space (as measured by serum concentrations of lidocaine) was investigated in 18 patients undergoing minor surgery during lumbar epidural analgesia. Twelve patients received four injections of 20 mL of 2......% lidocaine at 2-hr intervals. Epidural distribution was assessed by injection of 99mTc-DTPA diluted in saline on the preoperative day and diluted in an equal volume of 2% lidocaine on the morning before surgery and again after the fourth injection of lidocaine 6 hr later. The distribution of 99m......L of 2% lidocaine were injected three times at 2-hr intervals before surgery, with measurements of serum concentrations of lidocaine after the first and last injections. Despite tachyphylaxis (no patient had sensory analgesia 2 hr after the third injection), there was no difference in the rate...

  4. Experiment on damage in K9 glass due to repetition rate pulsed CO2 laser radiation%重频脉冲CO2激光损伤K9玻璃的实验

    Institute of Scientific and Technical Information of China (English)

    王玺; 卞进田; 李华; 聂劲松; 孙晓泉; 尹学忠; 雷鹏

    2013-01-01

      对脉冲CO2激光在不同重频模式下损伤K9玻璃进行了实验研究。采用输出能量为10 J,脉宽为90 ns,重复频率在100 Hz至300 Hz之间连续可调的脉冲CO2激光器,对K9玻璃样品进行了激光损伤实验,观察到两次不同重频条件下样品的损伤形貌。实验结果表明,重频越高,对样品的损伤程度就越严重;应力损伤成为K9玻璃激光损伤的最主要的原因,在重频强激光的辐照下,K9玻璃表面出现强烈的等离子体闪光,伴随明显的熔融气化破坏,并形成等离子体爆轰波。爆轰波对玻璃材料产生了严重的力学冲击作用,这种应力作用足以对K9玻璃造成毁灭性破坏。运用有限元分析对激光辐照K9玻璃的温度与应力分布进行仿真,其计算结果与实验基本吻合。%  In this paper, the experiment on damage in K9 glass induced by pulsed CO2 laser under different repetition rates was carried out, which had a pulse width of 90 ns. The laser pulse energy was 10 J and the repetition rate was kept within the range of 100 Hz to 300 Hz. The damage morphologies of two kind repetition rates after laser irradiation were characterized. The experimental results indicate that the effect of laser irradiation on samples can be affected considerably by the change of laser repetition rate, and the intensity of damage morphology on the sample increases with the laser repetition rate, and the damage in K9 glass induced by pulsed CO2 laser is dominated by stress. As a result, the plasma detonation wave induced by laser occured, the material was broken result from the melting and evaporation of K9 glass. It is shown that the plasma detonation wave affected stress damage considerably, and this mechanical effect almost destroyed K9 glass sample. A numerical simulation was performed to calculate temperature and stress distributions in K9 glass sample irradiated by pulsed CO2 laser using finite element method. The model

  5. Apparatus for measuring the flow rate of a heat carrier and injection wells

    Energy Technology Data Exchange (ETDEWEB)

    Putilov, M.F.; Bar-Sliva, V.I.; Dichenko, M.A.; Nikiforov, Yu.V.; Petrov, A.I.; Turchaninov, Yu.N.

    1981-01-01

    A device is proposed for measuring the flow rate of the heat carrier in N wells, which contains a housing, turbine ( a permanent magnet is attached to the shaft eccentrically), a reed relay, a secondary converter and a power supply. In order to expand the measurement range by developing torque in the turbine it is equipped with additional reed relay, which is installed diametrically opposite the primary reed relay, and it also has a breaking unit made in the form of an additional permanent magnet placed on the turbine shaft. There was also a torodial core with a two-section winding and a winding power supply polarity switch in the frame. The primary and secondary reed relays are connected to the winding power supply polarity switch circuit. It in turn is connected to the secondary converter. In order to assure the possibility of changing the slope of the flow rate converter into a number of turbine revolutions it is equipped with a frequency to voltage converter with a setting mechanism. The frequency to voltage converter input is connected to the secondary converter, and the output is connected to the power supply source.

  6. Longitudinal proton relaxation rates in rabbit tissues after intravenous injection of free and chelated Mn2+

    Energy Technology Data Exchange (ETDEWEB)

    Spiller, M.; Brown, R.D. III; Koenig, S.H.; Wolf, G.L.

    1988-11-01

    The factors that determine the field-dependent increase in 1/T1 of tissue water protons were investigated for MnCl2 and Mn2+ (PDTA) (1,3-propylenediamine-N,N',N'',N'''-tetraacetic acid) introduced intravenously into rabbits. Mn2+ was used in preference to other paramagnetic ions in part because of the distinct NMRD profiles (magnetic field dependence of 1/T1) of free Mn2+ ions, their small chelate complexes, and their macromolecular conjugates, and in part because the relatively low toxicity of Mn2+ is favorable for animal studies. Tissue content of Mn2+ was determined in all samples by inductively coupled plasma analyses the state of Mn2+ in excised tissues was determined from the form of the 1/T1 NMRD profile of water protons; and distribution of contrast agent within tissue and access of water on a T1 time scale were determined by double-exponential analyses of proton relaxation behavior in intact doped tissue, as well as by the change of single-exponential relaxation rates and proton signal intensity upon gentle disruption of the tissue. MnCl2 is found in all tissues, except fat and skeletal muscle, but liver is most avid at low dose, and Mn2+ accumulates in spleen after high doses. Chelation targets Mn2+ to liver and kidney, saturating the liver chemically at relatively low dose. We suggest that pronounced increase in tissue relaxivity results from irrotationally bound Mn2+, ostensibly associated with the polar head groups of cell membranes. Compartmentalization of contrast agent and restricted diffusion of tissue water influences the maximum relaxation rates attainable, so that there is an optimal dose of these contrast agents which is rather low.

  7. Longitudinal proton relaxation rates in rabbit tissues after intravenous injection of free and chelated Mn2+.

    Science.gov (United States)

    Spiller, M; Brown, R D; Koenig, S H; Wolf, G L

    1988-11-01

    The factors that determine the field-dependent increase in 1/T1 of tissue water protons were investigated for MnCl2 and Mn2+ (PDTA) (1,3-propylenediamine-N,N',N'',N'''-tetraacetic acid) introduced intravenously into rabbits. Mn2+ was used in preference to other paramagnetic ions in part because of the distinct NMRD profiles (magnetic field dependence of 1/T1) of free Mn2+ ions, their small chelate complexes, and their macromolecular conjugates, and in part because the relatively low toxicity of Mn2+ is favorable for animal studies. Tissue content of Mn2+ was determined in all samples by inductively coupled plasma analyses the state of Mn2+ in excised tissues was determined from the form of the 1/T1 NMRD profile of water protons; and distribution of contrast agent within tissue and access of water on a T1 time scale were determined by double-exponential analyses of proton relaxation behavior in intact doped tissue, as well as by the change of single-exponential relaxation rates and proton signal intensity upon gentle disruption of the tissue. MnCl2 is found in all tissues, except fat and skeletal muscle, but liver is most avid at low dose, and Mn2+ accumulates in spleen after high doses. Chelation targets Mn2+ to liver and kidney, saturating the liver chemically at relatively low dose. We suggest that pronounced increase in tissue relaxivity results from irrotationally bound Mn2+, ostensibly associated with the polar head groups of cell membranes. Compartmentalization of contrast agent and restricted diffusion of tissue water influences the maximum relaxation rates attainable, so that there is an optimal dose of these contrast agents which is rather low.

  8. Subcutaneous Injections

    DEFF Research Database (Denmark)

    Thomsen, Maria

    This thesis is about visualization and characterization of the tissue-device interaction during subcutaneous injection. The tissue pressure build-up during subcutaneous injections was measured in humans. The insulin pen FlexTouchr (Novo Nordisk A/S) was used for the measurements and the pressure...... build-up was evaluated indirectly from the changes in the flow rate between subcutaneous injections and air injections. This method enabled the tissue counter pressure to be evaluated without a formal clinical study approval. The measurements were coupled to a model for the pressure evolution...

  9. Tachyphylaxis associated with repeated epidural injections of lidocaine is not related to changes in distribution or the rate of elimination from the epidural space

    Energy Technology Data Exchange (ETDEWEB)

    Mogensen, T.; Simonsen, L.; Scott, N.B.; Henriksen, J.H.; Kehlet, H. (Univ. of Copenhagen (Denmark))

    1989-08-01

    The relationship between tachyphylaxis (measured as a decrease in the rate of regression of sensory levels of analgesia) during repeated epidural injections of lidocaine and both the distribution of lidocaine within the epidural space (as measured by spread of simultaneous injection of the tracer technetium-99m diethylenetriaminepentaacetate (99mTc-DTPA)) and elimination of lidocaine from the epidural space (as measured by serum concentrations of lidocaine) was investigated in 18 patients undergoing minor surgery during lumbar epidural analgesia. Twelve patients received four injections of 20 mL of 2% lidocaine at 2-hr intervals. Epidural distribution was assessed by injection of 99mTc-DTPA diluted in saline on the preoperative day and diluted in an equal volume of 2% lidocaine on the morning before surgery and again after the fourth injection of lidocaine 6 hr later. The distribution of 99mTc-DTPA in the epidural space was unchanged during the three measurements despite significant tachyphylaxis in both sensory analgesia and motor blockade (11 of 12 patients had sensory analgesia 2 hr after the first injection in contrast to only 3 of 12 patients during the third injection). In another six patients 20 mL of 2% lidocaine were injected three times at 2-hr intervals before surgery, with measurements of serum concentrations of lidocaine after the first and last injections. Despite tachyphylaxis (no patient had sensory analgesia 2 hr after the third injection), there was no difference in the rate of disappearance of lidocaine from the epidural space as assessed by plasma lidocaine concentration curves during the first and third injection (0.5 +/- 0.1 and 0.3 +/- 0.04 microgram.mL-1.min-1, respectively).

  10. Higher abnormal fertilization, higher cleavage rate, and higher arrested embryos rate were found in conventional IVF than in intracytoplasmic sperm injection.

    Science.gov (United States)

    Ming, Li; Yuan, Chen; Ping, Liu; Jie, Qiao

    2015-01-01

    The aim of this study was to investigate whether performing different fertilization technologies (intracytoplasmic sperm injection [ICSI] and in vitro fertilization [IVF]) may affect the result of fertilization in the normal fertilization cycles. The authors performed a retrospective analysis of 164 cycles using sibling oocytes in combined IVF/ICSI with achieved a normal fertilization ( ≥ 25%) both conventional IVF and ICSI in this infertility centre. It was found that there were no differences in 2PN rate (70.25% vs 70.60%), but higher cleavage rate in ICSI than IVF insemination (98.99% vs 96.81%), higher arrested embryos rate in IVF than ICSI in 2PN group (20.00% vs 13.95%), and higher abnormal fertilization IPN (3.87% vs 1.92%) and 3PN (3.63 vs 0.854%) in IVF than ICSI. There were some differences fertilization outcomes between ICSI and IVF, which may be related to different procedures between two techniques.

  11. Importance of estimation of follicular output rate (FORT in females assisted by intracytoplasmic sperm injection

    Directory of Open Access Journals (Sweden)

    Rehana Rehman

    2015-02-01

    Full Text Available Background: We aimed to estimate pregnancy outcome after ICSI in terms of oocyte parameters, embryo quality, endometrial thickness, hormone and cytokine levels in women stratified on the basis of follicular output rate (FORT. Methods: Quasi experimental design was carried out after approval from and ldquo;Ethical review board of Islamabad clinic serving infertile couples and rdquo; from July 2010 to August 2013. One thousand and fifty females were selected with the criteria of age between 21-40 years, infertility of more than 2 years, body mass index of 18-35 kg/m2, menstrual cycle of 25 +/- 7 days, both ovaries present with normal uterine cavity, serum FSH levels less than 8 IU/ml and normal thyroid-stimulating hormone levels. Females on short agonist or antagonist protocol with diagnosis of polycystic ovarian syndrome, fibroids or in their male partner sperms retrieved by testicular biopsy were excluded from the study. Down regulation of ovaries was followed by controlled ovarian stimulation, Ovulation Induction (OI, oocyte pick up, in vitro fertilization, Embryo Transfer (ET and confirmation of pregnancy was done by serum beta hCG of more than 25 mIU/ml and cardiac activity on trans vaginal scan. Enzyme linked immuno sorbent assay was used for peak and mid luteal estradiol (E2, progesterone (P and interleukin I-beta estimation on OI and ET days respectively. FORT (ratio of preovulatory follicle count to antral follicle count and times; 100 on OI day stratified females into low under the 33rd percentile, medium between the 33rd and the 67th percentile and high above the 67th percentile. Characteristics of groups were compared by one way analysis of variance. Results: Females 276 (33%, 288 (34% and 282 (33% comprised of low, medium and high FORT groups respectively. The number of retrieved, mature and fertilized oocytes, cleaved embryos, endometrial thickness and number of gestational sacs in the high FORT group was significantly high (P <0

  12. High-power, narrow-band, high-repetition-rate, 5.9 eV coherent light source using passive optical cavity for laser-based angle-resolved photoelectron spectroscopy.

    Science.gov (United States)

    Omachi, J; Yoshioka, K; Kuwata-Gonokami, M

    2012-10-08

    We demonstrate a scheme for efficient generation of a 5.9 eV coherent light source with an average power of 23 mW, 0.34 meV linewidth, and 73 MHz repetition rate from a Ti: sapphire picosecond mode-locked laser with an output power of 1 W. Second-harmonic light is generated in a passive optical cavity by a BiB(3)O(6) crystal with a conversion efficiency as high as 67%. By focusing the second-harmonic light transmitted from the cavity into a β-BaB(2)O(4) crystal, we obtain fourth-harmonic light at 5.9 eV. This light source offers stable operation for at least a week. We discuss the suitability of the laser light source for high-resolution angle-resolved photoelectron spectroscopy by comparing it with other sources (synchrotron radiation facilities and gas discharge lamp).

  13. 基于光导开关的重复频率闪光X光机%Repetitive rate flash X-ray generator with photo conductive semiconductor switches

    Institute of Scientific and Technical Information of China (English)

    马勋; 袁建强; 刘宏伟; 王凌云; 姜苹; 李洪涛

    2016-01-01

    A repetitive rate flash X-ray generator was developed recently to meet the demands in scientific research and in-dustrial area.A repetitive pulsed power supply was fabricated with GaAs photo conductive semiconductor switches and stacked Blumlein pulse forming networks to drive industrial X-ray diode,and a novel X-ray diode was proposed with spoked metal ceramic flashover cathode.The results show that 2 pulse burst X rays were generated under 1 kHz frame rate with novel cathode,and the two power pulses of diode and X-ray signals were identical.%采用砷化镓光导开关和Blumlein 型脉冲形成网络以级联的拓扑形式构建平顶输出功率源,驱动工业 X 光二极管产生 X 射线。提出了一种轮辐状金属-陶瓷沿面阴极,并与普通金属阴极工业 X 光二极管重复频率实验结果进行比较。研究表明:受限于阴极重复频率下的电流发射能力,普通金属阴极工业 X 光二极管难以实现1 kHz 重复频率,采用新型阴极二极管实现了1 kHz 重复频率2猝发脉冲 X 光输出,这两个脉冲的二极管功率、X 射线信号基本一致。

  14. COMBUSTION HEAT RELEASE RATE ANALYSIS OF C.I. ENGINE WITH SECONDARY CO-INJECTION OF DEE-H2O SOLUTION - A VIBRATIONAL APPROACH

    Directory of Open Access Journals (Sweden)

    Y. V. V. SATYANARAYANA MURTHY

    2015-08-01

    Full Text Available This paper discusses the combustion propensity of single cylinder direct injection engine fueled with palm kernel methyl ester (PKME, which is non- edible oil and a secondary co-injection of saturated Diethyl ether (DEE with water. DEE along with water is fumigated through a high pressure nozzle fitted to the inlet manifold of the engine and the flow rate of the secondary injection was electronically controlled. DEE is known to improve the cold starting problem in engines when used in straight diesel fuel. However, its application in emulsion form is little known. Experimental results show that for 5% DEE- H2O solution injection, occurrence of maximum net heat release rate is delayed due to controlled premixed combustion, which normally helped in better torque conversion when the piston is in accelerated mode. Vibration measurements in the frequency range of 900Hz to 1300Hz revealed that a new mode of combustion has taken place with different excitation frequencies.

  15. Pregnancy rate evaluation in lactating and non-lactating Nelore cows subjected to fixed-time artificial insemination using injectable progesterone

    Directory of Open Access Journals (Sweden)

    Jefferson Tadeu Campos

    2016-08-01

    Full Text Available Most fixed-time artificial insemination (FTAI protocols utilize progesterone (P4 as a hormonal source to achieve synchronization of estrus in cattle. The use of an injectable P4 source to control estrus would be an interesting pharmacological strategy owing to the practicality of parenteral application. However, the effects of injectable P4 on estrus cycle control in cattle remain poorly studied. In particular, no existing studies have investigated the effect of injectable P4 on the fertility of cows subjected to FTAI. The aim of this study was to evaluate the pregnancy rate of lactating and non-lactating Nelore cows subjected to FTAI with injectable P4. Of the 422 non-lactating cows in this study, 162 (38.3% became pregnant by 60 days post-FTAI. In the lactating group (n = 516, 166 (32.1% were pregnant by 60 days after treatment with injectable P4. The proportions of lactating and non-lactating cows becoming pregnant were compared using the chi-square test, adopting a significance level of P < 0.05. It was found that the pregnancy rate of the cows subjected to FTAI with injectable P4 was influenced by lactation status. Lactating cows had lower reproductive performance, possibly because of their higher nutritional requirements. However, the use of injectable P4 shows promising results and may prove to be a useful strategy in large-scale livestock production.

  16. A Methodology for the Optimization of Flow Rate Injection to Looped Water Distribution Networks through Multiple Pumping Stations

    Directory of Open Access Journals (Sweden)

    Christian León-Celi

    2016-12-01

    Full Text Available The optimal function of a water distribution network is reached when the consumer demands are satisfied using the lowest quantity of energy, maintaining the minimal pressure required at the same time. One way to achieve this is through optimization of flow rate injection based on the use of the setpoint curve concept. In order to obtain that, a methodology is proposed. It allows for the assessment of the flow rate and pressure head that each pumping station has to provide for the proper functioning of the network while the minimum power consumption is kept. The methodology can be addressed in two ways: the discrete method and the continuous method. In the first method, a finite set of combinations is evaluated between pumping stations. In the continuous method, the search for the optimal solution is performed using optimization algorithms. In this paper, Hooke–Jeeves and Nelder–Mead algorithms are used. Both the hydraulics and the objective function used by the optimization are solved through EPANET and its Toolkit. Two case studies are evaluated, and the results of the application of the different methods are discussed.

  17. Novel porcine repetitive elements

    Directory of Open Access Journals (Sweden)

    Nonneman Dan J

    2006-12-01

    Full Text Available Abstract Background Repetitive elements comprise ~45% of mammalian genomes and are increasingly known to impact genomic function by contributing to the genomic architecture, by direct regulation of gene expression and by affecting genomic size, diversity and evolution. The ubiquity and increasingly understood importance of repetitive elements contribute to the need to identify and annotate them. We set out to identify previously uncharacterized repetitive DNA in the porcine genome. Once found, we characterized the prevalence of these repeats in other mammals. Results We discovered 27 repetitive elements in 220 BACs covering 1% of the porcine genome (Comparative Vertebrate Sequencing Initiative; CVSI. These repeats varied in length from 55 to 1059 nucleotides. To estimate copy numbers, we went to an independent source of data, the BAC-end sequences (Wellcome Trust Sanger Institute, covering approximately 15% of the porcine genome. Copy numbers in BAC-ends were less than one hundred for 6 repeat elements, between 100 and 1000 for 16 and between 1,000 and 10,000 for 5. Several of the repeat elements were found in the bovine genome and we have identified two with orthologous sites, indicating that these elements were present in their common ancestor. None of the repeat elements were found in primate, rodent or dog genomes. We were unable to identify any of the replication machinery common to active transposable elements in these newly identified repeats. Conclusion The presence of both orthologous and non-orthologous sites indicates that some sites existed prior to speciation and some were generated later. The identification of low to moderate copy number repetitive DNA that is specific to artiodactyls will be critical in the assembly of livestock genomes and studies of comparative genomics.

  18. The mechanism of the transient depression of the erythropoietic rate induced in the rat by a single injection of uranyl nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Giglio, M.J.; Brandan, N.; Leal, T.L.; Bozzini, C.E.

    1989-06-15

    With the purpose of assessing the effect of uranyl nitrate (UN) on the rate of erythropoiesis, 1 mg/kg of the compound was injected iv to adult female Wistar rats. The dosing vehicle was injected into control animals. A single injection of UN induced a transient depression of the rate of red cell volume /sup 59/Fe uptake, which reached its lowest value (68% depression) by the seventh postinjection day. By 14 days, /sup 59/Fe incorporation had returned to normal. The amount of iron going to erythroid tissue per hour, reticulocyte count, and immunoreactive erythropoietin concentration in both plasma and kidney extracts were also significantly depressed in UN-treated rats in relation to these values in vehicle-injected rats by the seventh postinjection day. Dose-response curves for exogenous erythropoietin (Epo) performed in polycythemic intact and UN-treated rats 7 days after drug injection revealed a significant depression of the response in UN-injected animals. Moreover, bone marrow cells obtained from rats pretreated with UN formed a reduced number of erythroid colonies in vitro in response to Epo. Therefore, possible mechanisms for the observed transient depression in the rate of erythropoiesis associated with acute UN treatment include decreased Epo production and direct or indirect damage of erythroid progenitor cells.

  19. Subcutaneous Injections

    DEFF Research Database (Denmark)

    Thomsen, Maria

    This thesis is about visualization and characterization of the tissue-device interaction during subcutaneous injection. The tissue pressure build-up during subcutaneous injections was measured in humans. The insulin pen FlexTouchr (Novo Nordisk A/S) was used for the measurements and the pressure...... build-up was evaluated indirectly from the changes in the flow rate between subcutaneous injections and air injections. This method enabled the tissue counter pressure to be evaluated without a formal clinical study approval. The measurements were coupled to a model for the pressure evolution...... in subcutaneous tissue, based on mass conservation and flow in a porous medium. From the measurements the flow permeability and bulk modulus of the tissue were determined. In the adipose tissue the drug forms a bolus from where it is absorbed by the blood capillaries. The spatial distribution of the injected...

  20. Intravitreal injection analysis at the Bascom Palmer Eye Institute: evaluation of clinical indications for the treatment and incidence rates of endophthalmitis

    Directory of Open Access Journals (Sweden)

    Ludimila L Cavalcante

    2010-05-01

    Full Text Available Ludimila L Cavalcante, Milena L Cavalcante, Timothy G Murray, Michael M Vigoda, Yolanda Piña, Christina L Decatur, R Prince Davis, Lisa C Olmos, Amy C Schefler, Michael B Parrott, Kyle J Alliman, Harry W Flynn, Andrew A MoshfeghiBascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USAObjective: To report the incidence of endophthalmitis, in addition to its clinical and microbiological aspects, after intravitreal injection of vascular-targeting agents.Methods: A retrospective review of a consecutive series of 10,142 intravitreal injections of vascular targeting agents (bevacizumab, ranibizumab, triamcinolone acetonide, and preservative-free triamcinolone acetonide between June 1, 2007 and January 31, 2010, performed by a single service (TGM at the Bascom Palmer Eye Institute.Results: One case of clinically-suspected endophthalmitis was identified out of a total of 10,142 injections (0.009%, presenting within three days of injection of bevacizumab. The case was culture-positive for Staphylococcus epidermidis. Final visual acuity was 20/40 after pars plana vitrectomy surgery.Conclusions: In this series, the incidence of culture-positive endophthalmitis after intravitreal injection of vascular agents in an outpatient setting was very low. We believe that following a standardized injection protocol, adherence to sterile techniques and proper patient follow-up are determining factors for low incidence rates.Keywords: endophthalmitis, intravitreal injections, vascular targeting agents 

  1. Effects of 4-week administration of simvastatin in different doses on heart rate and blood pressure after metoprolol injection in normocholesterolaemic and normotensive rats.

    Science.gov (United States)

    Owczarek, Jacek; Jasińska, Magdalena; Wejman, Irena; Kurczewska, Urszula; Orszulak-Michalak, Daria

    2012-02-29

    Statins and β1-adrenergic antagonists are well established in cardiovascular events therapy and prevention. The previous study showed that statins might impact on β-adrenergic signalling and blood pressure in a dose-dependent manner. The aim of the study was to evaluate the impact of 4-week administration of simvastatin given at different doses on the heart rate and blood pressure after injection of metoprolol in rats. The experiments were performed in normocholesterolaemic and normotensive Wistar rats. Rats received simvastatin in doses of 1, 10 and 20 mg/kg body weight (bw) for 4 weeks. The control group received 0.2% methylcellulose. For the further estimation of the heart rate and blood pressure, metoprolol at 5 mg/kg bw or 0.9% NaCl was injected intraperitoneally. Simvastatin at doses of 1, 10 and 20 mg/kg bw did not influence the heart rate or blood pressure as compared to the control group. Metoprolol injection statistically significantly decreased the heart rate (439.29±14.03 min(-1) vs. 374.41±13.32 min(-1); pheart rate and blood pressure (mean, systolic, diastolic) were similar as compared to the group receiving metoprolol alone. Simvastatin administration during a 4-week period in different doses did not influence the heart rate or blood pressure after metoprolol injection in normocholesterolaemic and normotensive rats.

  2. Period Doubling in a Fabry-Perot Laser Diode Subject to Optical Pulse Injection

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yue-Peng; WANG Yun-Cai; ZHANG Ming-Jiang; AN Yi; WANG Ji-Long

    2007-01-01

    Experimental study and numerical simulations of the period doubling of injected optical pulses in Fabry-Perot laser diodes are presented. In our experiments, the period doubling is achieved within a wide input frequency range and the period doubling of the injected optical pulses with 6.32 GHz repetition rate is investigated in detail. The obtained experimental results indicate that period doubling occurs at an appropriate injected optical power level when the bias current of the Fabry-Perot laser diode is located in lower ranges. Moreover, the experimental observed features have been numerically demonstrated by using a coupled rate-equation model. Numerical simulations are consistent with the experimental results.

  3. Comparing the survival rate of juvenile Chinook salmon migrating through hydropower systems using injectable and surgical acoustic transmitters

    Science.gov (United States)

    Deng, Z. D.; Martinez, J. J.; Li, H.; Harnish, R. A.; Woodley, C. M.; Hughes, J. A.; Li, X.; Fu, T.; Lu, J.; McMichael, G. A.; Weiland, M. A.; Eppard, M. B.; Skalski, J. R.; Townsend, R. L.

    2017-01-01

    Acoustic telemetry is one of the primary technologies for studying the behavior and survival of fishes throughout the world. The size and performance of the transmitter are key limiting factors. The newly developed injectable transmitter is the first acoustic transmitter that can be implanted via injection instead of surgery. A two-part field study was conducted to evaluate the performance of the injectable transmitter and its effect on the survival of implanted fish. The injectable transmitter performed well and similarly to the proceeding generation of commercially-available JSATS transmitters tested concurrently. Snake River subyearling Chinook salmon smolts implanted with the injectable transmitter had a higher survival probability from release to each of eleven downstream detection arrays, because reach-specific survival estimates were significantly higher for the injectable group in three of the eleven reaches examined. Overall, the injectable group had a 0.263 (SE = 0.017) survival probability over the entire 500 km study area compared to 0.199 (0.012) for the surgically implanted group. The reduction in size and ability to implant the new transmitter via injection has reduced the tag or tagging effect bias associated with studying small fishes. The information gathered with this new technology is helping to evaluate the impacts of dams on fishes. PMID:28220850

  4. Comparing the survival rate of juvenile Chinook salmon migrating through hydropower systems using injectable and surgical acoustic transmitters.

    Science.gov (United States)

    Deng, Z D; Martinez, J J; Li, H; Harnish, R A; Woodley, C M; Hughes, J A; Li, X; Fu, T; Lu, J; McMichael, G A; Weiland, M A; Eppard, M B; Skalski, J R; Townsend, R L

    2017-02-21

    Acoustic telemetry is one of the primary technologies for studying the behavior and survival of fishes throughout the world. The size and performance of the transmitter are key limiting factors. The newly developed injectable transmitter is the first acoustic transmitter that can be implanted via injection instead of surgery. A two-part field study was conducted to evaluate the performance of the injectable transmitter and its effect on the survival of implanted fish. The injectable transmitter performed well and similarly to the proceeding generation of commercially-available JSATS transmitters tested concurrently. Snake River subyearling Chinook salmon smolts implanted with the injectable transmitter had a higher survival probability from release to each of eleven downstream detection arrays, because reach-specific survival estimates were significantly higher for the injectable group in three of the eleven reaches examined. Overall, the injectable group had a 0.263 (SE = 0.017) survival probability over the entire 500 km study area compared to 0.199 (0.012) for the surgically implanted group. The reduction in size and ability to implant the new transmitter via injection has reduced the tag or tagging effect bias associated with studying small fishes. The information gathered with this new technology is helping to evaluate the impacts of dams on fishes.

  5. Comparing the survival rate of juvenile Chinook salmon migrating through hydropower systems using injectable and surgical acoustic transmitters

    Science.gov (United States)

    Deng, Z. D.; Martinez, J. J.; Li, H.; Harnish, R. A.; Woodley, C. M.; Hughes, J. A.; Li, X.; Fu, T.; Lu, J.; McMichael, G. A.; Weiland, M. A.; Eppard, M. B.; Skalski, J. R.; Townsend, R. L.

    2017-02-01

    Acoustic telemetry is one of the primary technologies for studying the behavior and survival of fishes throughout the world. The size and performance of the transmitter are key limiting factors. The newly developed injectable transmitter is the first acoustic transmitter that can be implanted via injection instead of surgery. A two-part field study was conducted to evaluate the performance of the injectable transmitter and its effect on the survival of implanted fish. The injectable transmitter performed well and similarly to the proceeding generation of commercially-available JSATS transmitters tested concurrently. Snake River subyearling Chinook salmon smolts implanted with the injectable transmitter had a higher survival probability from release to each of eleven downstream detection arrays, because reach-specific survival estimates were significantly higher for the injectable group in three of the eleven reaches examined. Overall, the injectable group had a 0.263 (SE = 0.017) survival probability over the entire 500 km study area compared to 0.199 (0.012) for the surgically implanted group. The reduction in size and ability to implant the new transmitter via injection has reduced the tag or tagging effect bias associated with studying small fishes. The information gathered with this new technology is helping to evaluate the impacts of dams on fishes.

  6. Multi-purpose two- and three-dimensional momentum imaging of charged particles for attosecond experiments at 1 kHz repetition rate.

    Science.gov (United States)

    Månsson, Erik P; Sorensen, Stacey L; Arnold, Cord L; Kroon, David; Guénot, Diego; Fordell, Thomas; Lépine, Franck; Johnsson, Per; L'Huillier, Anne; Gisselbrecht, Mathieu

    2014-12-01

    We report on the versatile design and operation of a two-sided spectrometer for the imaging of charged-particle momenta in two dimensions (2D) and three dimensions (3D). The benefits of 3D detection are to discern particles of different mass and to study correlations between fragments from multi-ionization processes, while 2D detectors are more efficient for single-ionization applications. Combining these detector types in one instrument allows us to detect positive and negative particles simultaneously and to reduce acquisition times by using the 2D detector at a higher ionization rate when the third dimension is not required. The combined access to electronic and nuclear dynamics available when both sides are used together is important for studying photoreactions in samples of increasing complexity. The possibilities and limitations of 3D momentum imaging of electrons or ions in the same spectrometer geometry are investigated analytically and three different modes of operation demonstrated experimentally, with infrared or extreme ultraviolet light and an atomic/molecular beam.

  7. Relationship between repetitive firing and afterhyperpolarizations in human neocortical neurons.

    Science.gov (United States)

    Lorenzon, N M; Foehring, R C

    1992-02-01

    1. Human neocortical neurons fire repetitively in response to long depolarizing current injections. The slope of the relationship between average firing frequency and injected current (f-I slope) was linear or bilinear in these cells. The mean steady-state f-I slope (average of the last 500 ms of a 1-s firing episode) was 57.8 Hz/nA. The instantaneous firing rate decreased with time during a 1-s constant-current injection (spike frequency adaptation). Also, human neurons exhibited habituation in response to a 1-s current stimulus repeated every 2 s. 2. Afterhyperpolarizations (AHPs) reflect the active ionic conductances after action potentials. We studied AHPs with the use of intracellular recordings and pharmacological manipulations in the in vitro slice preparation to 1) gain insight into the ionic mechanisms underlying the AHPs and 2) elucidate the role that the underlying currents play in the functional behavior of human cortical neurons. 3. We have classified three AHPs in human neocortical neurons on the basis of their time courses: fast, medium, and slow. The amplitude of the AHPs was dependent on stimulus intensity and duration, number and frequency of spikes, and membrane potential. 4. The fast AHP had a reversal potential of -65 mV and was eliminated in extracellular Co2+, tetraethylammonium (TEA) or 4-aminopyridine, and intracellular TEA or CsCl. These manipulations also caused an increase in spike width. 5. The medium AHP had a reversal potential of -90 to -93 mV (22-24 mV hyperpolarized from mean resting potential). This AHP was reduced by Co2+, apamin, tubocurare, muscarine, norepinephrine (NE), and serotonin (5-HT). Pharmacological manipulations suggest that the medium AHP is produced in part by 1) a Ca-dependent K+ current and 2) a time-dependent anomalous rectifier (IH). 6. The slow AHP reversed at -83 to -87 mV (14-18 mV hyperpolarized from mean resting potential). This AHP was diminished by Co2+, muscarine, NE, and 5-HT. The pharmacology of the

  8. 降低焦炉机车电器运行重复故障率%Reduce the Repetition Rate of Electric Operation of the Coke Oven Locomotive

    Institute of Scientific and Technical Information of China (English)

    姜玉怀

    2016-01-01

    the coking coal coking company of masteel outdated 1 # 4 # coke oven in order to real-ize the coal charging and coke pushing, blocking water coke dry quenching, quenching, screen coke and dust removal, etc. By the four major locomotive ( coke pusher, coal car, stop coke car, coke quenching car) , due to the special environment of the equipment operation ( mobile, high tempera-ture, dust, stop frequent restart, etc. ) , make the equipment in the process of running frequent fail-ure, not only increase the workload of maintenance, because maintenance delayed production at the same time, reduces the coke oven coke rate, thus the ascension of the whole economic benefit of mas-teel.%马钢煤焦化公司老区焦化1#-4#焦炉为了实现装煤、推焦、拦焦、干熄焦、水熄焦、筛焦、除尘等工艺。由四大机车(推焦车、装煤车、拦焦车、熄焦车)来实现,由于设备运行的特殊环境(移动、高温、多灰尘、停启动频繁等),使得设备在运行过程中故障频发,这不仅仅增加了维修工作量,同时因为检修耽误了生产,降低了焦炉的出焦率,从而影响了整个马钢的经济效益的提升。

  9. Development of a compact and reliable repetitively pulsed Xe Cl (308 nm) excimer laser

    Indian Academy of Sciences (India)

    N S Benerji; N Varshnay; J K Mittal

    2013-02-01

    Development and operation characteristics of a repetitively pulsed UV spark pre-ionized XeCl(Xenon Chloride) excimer laser is described. The laser uses discharge pumped C–C charge transfer excitation. A compact gas circulation loop was adopted to achieve high repetition rate operation. The laser generates optical pulses of energy 150 mJ at 150 Hz reliably. The electrical to optical conversion efficiency obtained is 1%. The laser pulse duration is ∼8 nS (FWHM). The single fill gas lifetime have been found to be 2 × 106 shots for 20% reduction of energy without any halogen injection. The system is compact and reliable.

  10. Comparison of O2 saturation, heart and respiratory rate following injection of vasoconstrictor containing anesthetic (lidocaine 2% and without vasoconstrictor anesthetic (Mepivacaine

    Directory of Open Access Journals (Sweden)

    Bayat M.

    2005-07-01

    Full Text Available Background and Aim: Along with higher usage of dental local anesthesia with risks to people health together with their positive role, the important goal of dentistry, patients’ health, has been stressed repeatedly nowadays. This study was conducted to compare O2 saturation, respiratory rate and heart rate of patients following injection of anesthetic containing vasoconstrictor (lidocaine 2% and without vasoconstrictor (Mepivacaine. Materials and Methods: This experimental study was conducted on 32 healthy humans (16 females and 16 males with 25-50 years age range and no history of drug usage. Cases were classified into two matched groups. O2 saturation, heart and respiratory rate were recorded before extraction of a mandibular posterior tooth. In the first group, 3.6 ml lidocaine 2% with 1:80,000 epinephrine and in the second group Mepivacaine 3% was injected, using inferior alveolar dental nerve block with aspiration. Variables were measured and recorded. Tooth extraction was performed and the mentioned variables were recorded again. Data were analyzed with SPSS software using t and Paired t-test with P<0.05 as the limit of significance. Results: After injection of lidocaine, the heart rate was increased (12.25±1.75 bpm, and the time to reach the maximum rate was 64.75±11.26 seconds. After extraction of tooth, heart rate in both groups was increased not considering the type of injection. Conclusion: The study showed that the injection of lidocaine (containing epinephrine in patients without contraindication has no risk. Also, possible increase in heart rate is not risky and is not associated with O2 saturation decrease and respiratory interruption.

  11. The effects of timing and rate of marine cloud brightening aerosol injection on albedo changes during the diurnal cycle of marine stratocumulus clouds

    Directory of Open Access Journals (Sweden)

    A. K. L. Jenkins

    2012-09-01

    Full Text Available The marine-cloud brightening geoengineering technique has been suggested as a~possible means of counteracting the positive radiative forcing associated with anthropogenic atmospheric CO2 increases. The focus of this study is to quantify the albedo response to aerosols injected into marine stratocumulus cloud from a point source at different times of day. We use a cloud-resolving model to investigate both weakly precipitating and non-precipitating regimes. Injection into both regimes induces a first indirect aerosol effect. Additionally, the weakly precipitating regime shows evidence of the second indirect aerosol effect and leads to cloud changes indicative of a regime change to more persistent cloud. This results in a cloud albedo increase up to six times larger than in the non-precipitating case. These indirect effects show considerable variation with injection at different times in the diurnal cycle. For the weakly precipitating case, aerosol injection results in average increases in cloud albedo of 0.28 and 0.17 in the early and mid morning (03:00:00 local time (LT and 08:00:00 LT, respectively and 0.01 in the evening (18:00:00 LT. No cloud develops when injecting into the cloud-free day (13:00:00 LT. However, the all-sky albedo increases (which include both the indirect and direct aerosol effects are highest for early morning injection (0.11. Mid-morning and daytime injections produce increases of 0.06, with the direct aerosol effect compensating for the lack of cloud albedo perturbation during the cloud-free day. Evening injection results in an increase of 0.04. Penetration and accumulation of aerosols above the cloud top may lead to a reduction of all-sky albedo that tempers the cloud albedo increases. The apparent direct aerosol tempering effect increases with injection rate, although not enough to overcome the increase in all-sky planetary albedo resulting from increases in cloud albedo. For the weakly precipitating case

  12. All-solid-state high-repetition-rate magnetic pulse compression generator%全固态高重复频率磁脉冲压缩发生器

    Institute of Scientific and Technical Information of China (English)

    张东东; 周媛; 李文峰; 许家雨; 王珏; 邵涛; 赵莹; 徐蓉

    2012-01-01

    The paper presents an all-solid-state high-repetition-rate pulse generator with adjustable output amplitude based on magnetic pulse compression (MPC) technique. The pulse compression network makes use of commercially available IGBTs switching a capacitor bank into a metglas transformer together with a voltage doubling circuit. The capacitor bank is charged to 500 V by a resonant LC charger, and also switched by a commercial diode. The output of the pulse generator is controlled by the gate voltage of the IGBTs. Pulses with a width of 70 ns can be generated with repetition rates up to 5 kHz. The amplitude can be controlled from 4 kV to 40 kV into a 500 Ω load. Equivalent circuits for the final operation stage of the compressor accounting for pre-pulse in magnetic switches are presented and analyzed, and the pre-pulse generation process of the MPC system is discussed. Simulation results show that, increasing the unsaturated inductance of the magnetic switch and reducing the load resistance enhance the pre-pulse peak. Thus to diminish the pre-pulse, a better ferrite core with higher permeability should be considered.%设计制作了全固态高重复频率磁脉冲压缩发生器,最高重复频率5 kHz,脉宽70 ns,通过调节初始储能电容上的电压可在500 Ω阻性负载上获得4~40 kV连续可调的输出电压.通过分析简化的磁压缩末级回路,分析了预脉冲产生的过程,得出了预脉冲的电压表达式,选取适当的磁芯相对磁导率,经过求解,得出在磁开关未饱和电感一定时预脉冲随负载阻值变化的曲线簇,从曲线中可以看出:随着负载的阻值的增大,预脉冲的峰值绝对值也增大;在负载恒定的情况下,增大磁开关未饱和电感的大小可以显著地减小负载两端预脉冲的峰值绝对值,这要求磁开关磁芯有更高的相对磁导率.

  13. Injection Seeded Laser for Formaldehyde Differential Fluorescence Lidar

    Directory of Open Access Journals (Sweden)

    Schwemmer G.

    2016-01-01

    Full Text Available We describe the design and development of an injection seeded Nd:YVO4 laser for use in a differential fluorescence lidar for measuring atmospheric formaldehyde profiles. A high repetition rate Q-switched laser is modified to accept injection seed input to spectrally narrow and tune the output. The third harmonic output is used to excite formaldehyde (HCHO fluorescence when tuned to a HCHO absorption line. Spectral confirmation is made with the use of a photoacoustic cell and grating spectrometer.

  14. MIMICRY, DIFFERENCE AND REPETITION

    Directory of Open Access Journals (Sweden)

    Marcelo Mendes de Souza

    2008-07-01

    Full Text Available This article addresses Homi K. Bhabha’s concept of mimicry in a broader context, other than that of cultural studies and post-colonial studies, bringing together other concepts, such as that of Gilles Deleuze in Difference and repetition, among other texts, and other names, such as Silviano Santiago, Jorge Luís Borges, Franz Kafka and Giorgio Agamben. As a partial conclusion, the article intends to oppose Bhabha’s freudian-marxist view to Five propositions on Psychoanalysis (1973, Gilles Deleuze’s text about Psychoanalysis published right after his book The Anti-Oedipus.

  15. High Repetition Rate Thermometry System And Method

    KAUST Repository

    Chrystie, Robin

    2015-05-14

    A system and method for rapid thermometry using intrapulse spectroscopy can include a laser for propagating pulses of electromagnetic radiation to a region. Each of the pulses can be chirped. The pulses from the region can be detected. An intrapulse absorbance spectrum can be determined from the pulses. An instantaneous temperature of the region based on the intrapulse absorbance spectrum can be determined.

  16. Effects of rocuronium injection rates on injection pain of rocuronium in children%不同静脉注射速度对小儿罗库溴铵注射痛反应的影响

    Institute of Scientific and Technical Information of China (English)

    周加倩; 陈依君; 陈锡明; 王英伟

    2009-01-01

    目的 观察静脉注射速度对小儿罗库溴铵静脉注射痛反应的影响.方法 全麻下择期手术患儿60例均分为两组,给予咪唑安定、氯胺酮,入睡后给予罗库溴铵0.6 mg/kg(浓度10mg/ml).A组注速≤3 s,B组注速60 s.采用加速度肌松监测仪监测肌松指标,观察罗库溴铵静脉注射痛反应、气管插管条件和肌松起效时间.结果 B组静脉注射痛反应的发生率明显低于A组(P<0.01);两组插管条件和肌松起效时间的差异无统计学意义.结论 缓慢静脉注射罗库溴铵能明显减轻罗库溴铵静脉注射痛,对气管插管条件和肌松起效时间无明显影响.%Objective To compare the effects of rocuronium injection rates on rocuroniuminduced injection pain in children. Methods Sixty children undergoing general anesthesia were divided into two groups with 30 eases each. Anesthesia was induced with midazolam, ketamine and rocuronium 0.6 mg/kg. Rocuronium was injected within 3 seconds in group A or slowly in 60 seconds in group R The neuromuscular blockade was monitored by acceleromyography with train-of-four stimulation. The pain of rocuronium injection and intubation Conditions were assessed. Results The incidence and intensity of injection pain were significantly lower in group B than those in group A(P<0.01).The onset time and intubation conditions of two groups were similar. Conclusion The lower injection rate of rocuronium significantly reduces the incidence and intensity of injection pain without any effect on the onset time and intubation condition in children.

  17. Assessment of industrial operation at low coke rate and coal injection in excess of 220 kg/tHM. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sert, D.; Godijn, R. [IRSID, Maizieres-les-Metz (France)

    2002-07-01

    High coal injection rates have been achieved on several blast furnaces, but only for limited periods. The aim of this project was to establish the required conditions for achieving very low coke rates (greater than 300 kg/tHM) and coal rate in excess of 220 kg/tHM, under long-term industrial conditions. But despite some improvement in the coke and coal ratio ratios, the search for safe operation, on the one hand, and some technological problems, on the other, did not enable the initial objectives to be reached. Despite this result, various studies undertaken during the course of the project produced some interesting conclusions related to the search for high coal rate operation. These studies dealt with: the comparison of the burden at both plants; the way to promote coal combustion; evaluation of the thermo-chemical conditions of the shaft at coal rates around 18 kg/tHM; monitoring the evolution in time of the hearth ocnditions at high coal injection practice; the blast furnace process at high coal injection rate.

  18. A single-pulse shock tube coupled with high-repetition-rate time-of-flight mass spectrometry and gas chromatography for high-temperature gas-phase kinetics studies

    Science.gov (United States)

    Sela, P.; Shu, B.; Aghsaee, M.; Herzler, J.; Welz, O.; Fikri, M.; Schulz, C.

    2016-10-01

    Shock tubes are frequently used to investigate the kinetics of chemical reactions in the gas phase at high temperatures. Conventionally, two complementary arrangements are used where either time-resolved intermediate species measurements are conducted after the initiation of the reaction or where the product composition is determined after rapid initiation and quenching of the reaction through gas-dynamic processes. This paper presents a facility that combines both approaches to determine comprehensive information. A single-pulse shock tube is combined with high-sensitivity gas chromatography/mass spectrometry for product composition and concentration measurement as well as high-repetition-rate time-of-flight mass spectrometry for time-dependent intermediate concentration determination with 10 μs time resolution. Both methods can be applied simultaneously. The arrangement is validated with investigations of the well-documented thermal unimolecular decomposition of cyclohexene towards ethylene and 1,3-butadiene at temperatures between 1000 and 1500 K and pressures ranging from 0.8 to 2.4 bars. The comparison shows that the experimental results for both detections are in very good agreement with each other and with literature data.

  19. DOE-HEP Final Report for 2013-2016: Studies of plasma wakefields for high repetition-rate plasma collider, and Theoretical study of laser-plasma proton and ion acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Katsouleas, Thomas C. [Duke Univ., Durham, NC (United States). Dept. of Electrical and Computer Engineering; Sahai, Aakash A. [Imperial College, London (United Kingdom). Dept. of Physics

    2016-08-08

    There were two goals for this funded project: 1. Studies of plasma wakefields for high repetition-rate plasma collider, and 2. Theoretical study of laser-plasma proton and ion acceleration. For goal 1, an analytical model was developed to determine the ion-motion resulting from the interaction of non-linear “blow-out” wakefields excited by beam-plasma and laser-plasma interactions. This is key to understanding the state of the plasma at timescales of 1 picosecond to a few 10s of picoseconds behind the driver-energy pulse. More information can be found in the document. For goal 2, we analytically and computationally analyzed the longitudinal instabilities of the laser-plasma interactions at the critical layer. Specifically, the process of “Doppler-shifted Ponderomotive bunching” is significant to eliminate the very high-energy spread and understand the importance of chirping the laser pulse frequency. We intend to publish the results of the mixing process in 2-D. We intend to publish Chirp-induced transparency. More information can be found in the document.

  20. Laser radiation frequency conversion in carbon- and cluster-containing plasma plumes under conditions of single and two-color pumping by pulses with a 10-Hz repetition rate

    Science.gov (United States)

    Ganeev, R. A.

    2013-07-01

    This work reviews a series of investigations of different plasma plumes using single- and two-color laser systems that emit femtosecond pulses with a 10-Hz repetition rate. Results of investigation of the resonant enhancement of harmonics in tin plasma with the use of two types of pumps are analyzed, and it is shown that the tuning of the wavelengths of harmonics to ion-resonance levels plays an important role in increasing the conversion efficiency to high-order harmonics of the radiation to be converted. Investigations of different carbon-containing plasma media (carbon nanotubes, graphite, carbon aerogel, etc.) exhibit attractive properties of the nonlinear medium of this type for efficient generation of high-order harmonics. The results of the first experiments on the use of nanoparticles produced directly in the course of laser ablation of metals for increasing the efficiency of harmonics generated in this cluster-containing medium are analyzed. It is shown that new approaches realized in these investigations give hope that the nonlinear optical response of plasma media in the far-ultraviolet range can be further increased.

  1. Estimating the number of persons who inject drugs in the united states by meta-analysis to calculate national rates of HIV and hepatitis C virus infections.

    Directory of Open Access Journals (Sweden)

    Amy Lansky

    Full Text Available BACKGROUND: Injection drug use provides an efficient mechanism for transmitting bloodborne viruses, including human immunodeficiency virus (HIV and hepatitis C virus (HCV. Effective targeting of resources for prevention of HIV and HCV infection among persons who inject drugs (PWID is based on knowledge of the population size and disparity in disease burden among PWID. This study estimated the number of PWID in the United States to calculate rates of HIV and HCV infection. METHODS: We conducted meta-analysis using data from 4 national probability surveys that measured lifetime (3 surveys or past-year (3 surveys injection drug use to estimate the proportion of the United States population that has injected drugs. We then applied these proportions to census data to produce population size estimates. To estimate the disease burden among PWID by calculating rates of disease we used lifetime population size estimates of PWID as denominators and estimates of HIV and HCV infection from national HIV surveillance and survey data, respectively, as numerators. We calculated rates of HIV among PWID by gender-, age-, and race/ethnicity. RESULTS: Lifetime PWID comprised 2.6% (95% confidence interval: 1.8%-3.3% of the U.S. population aged 13 years or older, representing approximately 6,612,488 PWID (range: 4,583,188-8,641,788 in 2011. The population estimate of past-year PWID was 0.30% (95% confidence interval: 0.19 %-0.41% or 774,434 PWID (range: 494,605-1,054,263. Among lifetime PWID, the 2011 HIV diagnosis rate was 55 per 100,000 PWID; the rate of persons living with a diagnosis of HIV infection in 2010 was 2,147 per 100,000 PWID; and the 2011 HCV infection rate was 43,126 per 100,000 PWID. CONCLUSION: Estimates of the number of PWID and disease rates among PWID are important for program planning and addressing health inequities.

  2. Repetition in Waiting for Godot

    Institute of Scientific and Technical Information of China (English)

    李想; 魏妍

    2015-01-01

    Waiting for Godot is one of the most famous plays written by Samuel Barclay Beckett, and also is the founding work of“Theatre of the Absurd”. In the drama, repetitive phenomena shed light on the whole construction considerably. All the charac-ters were helpless and unthinking. Their dialogues were simple, nonsense and repetitive. Two scenes were cyclical. Repetition was used subtly in order to express the theme of the play, showing mental crisis after depravation of WWII.

  3. Pain and Efficacy Rating of a Microprocessor-Controlled Metered Injection System for Local Anaesthesia in Minor Hand Surgery

    Directory of Open Access Journals (Sweden)

    André S. Nimigan

    2011-01-01

    Full Text Available Purpose. Little attention has been given to syringe design and local anaesthetic administration methods. A microprocessor-controlled anaesthetic delivery device has become available that may minimize discomfort during injection. The purpose of this study was to document the pain experience associated with the use of this system and to compare it with use of a conventional syringe. Methods. A prospective, randomized clinical trial was designed. 40 patients undergoing carpal tunnel release were block randomized according to sex into a two groups: a traditional syringe group and a microprocessor-controlled device group. The primary outcome measure was surgical pain and local anaesthetic administration pain. Secondary outcomes included volume of anaesthetic used and injection time. Results. Analysis showed that equivalent anaesthesia was achieved in the microprocessor-controlled group despite using a significantly lower volume of local anaesthetic (P=.0002. This same group, however, has significantly longer injection times (P<.0001. Pain during the injection process or during surgery was not different between the two groups. Conclusions. This RCT comparing traditional and microprocessor controlled methods of administering local anaesthetic showed similar levels of discomfort in both groups. While the microprocessor-controlled group used less volume, the total time for the administration was significantly greater.

  4. Active power filter for harmonic compensation using a digital dual-mode-structure repetitive control approach

    DEFF Research Database (Denmark)

    Zou, Zhixiang; Wang, Zheng; Cheng, Ming;

    2012-01-01

    This paper presents an digital dual-mode-structure repetitive control approach for the single-phase shunt active power filter (APF), which aims to enhance the tracking ability and eliminate arbitrary order harmonic. The proposed repetitive control scheme blends the characteristics of both odd......-harmonic repetitive control and even-harmonic repetitive control. Moreover, the convergence rate is faster than conventional repetitive controller. Additionally, the parameters have been designed and optimized for the dual-mode structure repetitive control to improve the performance of APF system. Experimental...... results on a laboratory setup are given to verify the proposed control scheme....

  5. Repetitive energy transfer from an inductive energy store

    Energy Technology Data Exchange (ETDEWEB)

    Honig, E.M.

    1984-01-01

    The theoretical and experimental results of a research program aimed at finding practical ways to transfer energy repetitively from an inductive energy store to various loads are discussed. The objectives were to investigate and develop the high power opening switches and transfer circuits needed to enable high-repetition-rate operation of such systems, including a feasibility demonstration at a current level near 10 kA and a pulse repetition rate of 1-10 kpps with a 1-ohm load. The requirements of nonlinear, time-varying loads, such as the railgun electromagnetic launcher, were also addressed. Energy storage capability is needed for proper power conditioning in systems where the duty factor of the output pulse train is low. Inductive energy storage is attractive because it has both a high energy storage density and a fast discharge capability. By producing a pulse train with a peak power of 75 MW at a pulse repetition rate of 5 kpps in a one-ohm load system, this research program was the first to demonstrate fully-controlled, high-power, high-repetition-rate operation of an inductive energy storage and transfer system with survivable switches. Success was made possible by using triggered vacuum gap switches as repetitive, current-zero opening switches and developing several new repetitive transfer circuits using the counterpulse technique.

  6. Understanding maximal repetitions in strings

    CERN Document Server

    Crochemore, Maxime

    2008-01-01

    The cornerstone of any algorithm computing all repetitions in a string of length n in O(n) time is the fact that the number of runs (or maximal repetitions) is O(n). We give a simple proof of this result. As a consequence of our approach, the stronger result concerning the linearity of the sum of exponents of all runs follows easily.

  7. Basin-scale spatio-temporal variability and control of phytoplankton photosynthesis in the Baltic Sea: The first multiwavelength fast repetition rate fluorescence study operated on a ship-of-opportunity

    Science.gov (United States)

    Houliez, Emilie; Simis, Stefan; Nenonen, Susanna; Ylöstalo, Pasi; Seppälä, Jukka

    2017-05-01

    This study presents the results of the first field application of a flow-through multi-wavelength Fast Repetition Rate fluorometer (FRRF) equipped with two excitation channels (458 and 593 nm). This device aims to improve the measurement of mixed cyanobacteria and algae community's photosynthetic parameters and was designed to be easily incorporated into existing ferrybox systems. We present a spatiotemporal analysis of the maximum photochemical efficiency (Fv/Fm) and functional absorption cross section (σPSII) recorded from April to August 2014 on a ship-of-opportunity commuting twice per week between Helsinki (Finland) and Travemünde (Germany). Temporal variations of Fv/Fm and σPSII differed between areas of the Baltic Sea. However, even though the Baltic Sea is characterized by several physico-chemical gradients, no gradient was observed in Fv/Fm and σPSII spatial distribution suggesting complex interactions between biotic and abiotic controls. σPSII was sensitive to phytoplankton seasonal succession and thus differed according to the wavelength used to excite photosystems II (PSII) pigments. This was particularly true in summer when high σPSII(593) values were observed later and longer than high σPSII(458) values, reflecting the role of cyanobacteria in photosynthetic light uptake measured at community scale. In contrast, Fv/Fm variations were similar after excitation at 458 nm or 593 nm suggesting that the adjustment of Fv/Fm in response to environmental factors was similar for the different groups (algae vs. cyanobacteria) present within the phytoplankton community.

  8. Pain and efficacy rating of a microprocessor-controlled metered injection system for local anaesthesia in minor hand surgery.

    Science.gov (United States)

    Nimigan, André S; Gan, Bing Siang

    2011-01-01

    Purpose. Little attention has been given to syringe design and local anaesthetic administration methods. A microprocessor-controlled anaesthetic delivery device has become available that may minimize discomfort during injection. The purpose of this study was to document the pain experience associated with the use of this system and to compare it with use of a conventional syringe. Methods. A prospective, randomized clinical trial was designed. 40 patients undergoing carpal tunnel release were block randomized according to sex into a two groups: a traditional syringe group and a microprocessor-controlled device group. The primary outcome measure was surgical pain and local anaesthetic administration pain. Secondary outcomes included volume of anaesthetic used and injection time. Results. Analysis showed that equivalent anaesthesia was achieved in the microprocessor-controlled group despite using a significantly lower volume of local anaesthetic (P = .0002). This same group, however, has significantly longer injection times (P microprocessor controlled methods of administering local anaesthetic showed similar levels of discomfort in both groups. While the microprocessor-controlled group used less volume, the total time for the administration was significantly greater.

  9. On the repetitive operation of a self-switched transversely excited atmosphere CO2 laser

    Indian Academy of Sciences (India)

    Pallavi Raote; Gautam Patil; J Padma Nilaya; D J Biswas

    2010-11-01

    The repetition rate capability of self-switched transversely excited atmosphere (TEA) CO2 laser was studied for different gas flow configurations. For an optimized gas flow configuration, repetitive operation was achieved at a much smaller gas replenishment factor between two successive pulses when compared with repetitive systems energized by conventional pulsers.

  10. Numerical Investigation of Influence of In-Situ Stress Ratio, Injection Rate and Fluid Viscosity on Hydraulic Fracture Propagation Using a Distinct Element Approach

    Directory of Open Access Journals (Sweden)

    Bo Zhang

    2016-02-01

    Full Text Available Numerical simulation is very useful for understanding the hydraulic fracturing mechanism. In this paper, we simulate the hydraulic fracturing using the distinct element approach, to investigate the effect of some critical parameters on hydraulic fracturing characteristics. The breakdown pressure obtained by the distinct element approach is consistent with the analytical solution. This indicates that the distinct element approach is feasible on modeling the hydraulic fracturing. We independently examine the influence of in-situ stress ratio, injection rate and fluid viscosity on hydraulic fracturing. We further emphasize the relationship between these three factors and their contributions to the hydraulic fracturing. With the increase of stress ratio, the fracture aperture increases almost linearly; with the increase of injection rate and fluid viscosity, the fracture aperture and breakdown pressure increase obviously. A low value of product of injection rate and fluid viscosity (i.e., Qμ will lead to narrow fracture aperture, low breakdown pressure, and complex or dispersional hydraulic fractures. A high value of Qμ would lead wide fracture aperture, high breakdown pressure, and simple hydraulic fractures (e.g., straight or wing shape. With low viscosity fluid, the hydraulic fracture geometry is not sensitive to stress ratio, and thus becomes a complex fracture network.

  11. Success rate of 10th semester dental students of Tehran University of Medical students in infra alveolar nerve block injection technique

    Directory of Open Access Journals (Sweden)

    Hoseinitodashki H.

    2009-03-01

    Full Text Available "nBackground and Aim: Inducing anesthesia is one of the important tasks in dentistry. Among various techniques for injection, the Inferior Alveolar Nerve Block (IANB technique is one of the most practical and prevalent methods. However, according to some proofs in reference books, the success rate for this technique is some how low. Therefore the success rate of IANB performed by 10th-semester undergraduare students from Faculty of Dentistry of Tehran University of Medical Sciences was assessed in this study. "nMaterials and Methods: In this cross-sectional study from patients referring to oral and maxillofacial surgery ward, 20 patients with predefined conditions were selected. For each of them, two IANB injections were done in two separated days; one by a student and the other by an attend (or resident of maxillofacial surgery ward. Success or failure of each injection was examined by Pin Prick test. In this study, the non-parametric Willcoxon test was used. "nResults: In this study, the success rate of IANB was 70% and 90%, respectively for students and attends (or resident. "nConclusion: Significant statistically difference was seen between the two groups, we hope that through further practical education, this differences rsduce in following similar studies.

  12. Adaptive upstream rate adjustment by RSOA-ONU depending on different injection power of seeding light in standard-reach and long-reach PON systems

    Science.gov (United States)

    Yeh, C. H.; Chow, C. W.; Shih, F. Y.; Pan, C. L.

    2012-08-01

    The wavelength division multiplexing-time division multiplexing (WDM-TDM) passive optical network (PON) using reflective semiconductor optical amplifier (RSOA)-based colorless optical networking units (ONUs) is considered as a promising candidate for the realization of fiber-to-the-home (FTTH). And this architecture is actively considered by Industrial Technology Research Institute (ITRI) for the realization of FTTH in Taiwan. However, different fiber distances and optical components would introduce different power budgets to different ONUs in the PON. Besides, due to the aging of optical transmitter (Tx), the power decay of the distributed optical carrier from the central office (CO) could also reduce the injection power into each ONU. The situation will be more severe in the long-reach (LR) PON, which is considered as an option for the future access. In this work, we investigate a WDM-TDM PON using RSOA-based ONU for upstream data rate adjustment depending on different continuous wave (CW) injection powers. Both standard-reach (25 km) and LR (100 km) transmissions are evaluated. Moreover, a detail analysis of the upstream signal bit-error rate (BER) performances at different injection powers, upstream data rates, PON split-ratios under stand-reach and long-reach is presented.

  13. Emotional arousal enhances word repetition priming

    OpenAIRE

    Thomas, Laura A.; LaBar, Kevin S.

    2005-01-01

    Three experiments were conducted to determine if emotional content increases repetition priming magnitude. In the study phase of Experiment 1, participants rated high-arousing negative (taboo) words and neutral words for concreteness. In the test phase, they made lexical decision judgements for the studied words intermixed with novel words (half taboo, half neutral) and pseudowords. In Experiment 2, low-arousing negative (LAN) words were substituted for the taboo words, and in Experiment 3 al...

  14. Blastocyst transfer ameliorates live birth rate compared with cleavage-stage embryos transfer in fresh in vitro fertilization or intracytoplasmic sperm injection cycles: reviews and meta-analysis.

    Science.gov (United States)

    Wang, Shan-Shan; Sun, Hai-Xiang

    2014-05-01

    Blastocyst transfer has been recommended to raise the implantation rate without affecting the pregnancy rate. The objective of this meta-analysis is to systematically evaluate whether the live birth rate and other pregnancy outcomes can be improved by blastocyst transfer compared with cleavage-stage embryos transfer. EMBASE and MEDLINE databases were searched for papers published between March 2004 and March 2013. An extensive range of the electronic databases yielded initially 317 studies from which seven trials met the inclusion criteria for further analysis. Our outcome measures were the live birth rate, clinical pregnancy rate, implantation rate, ongoing pregnancy rate, multiple pregnancy rate, first trimester miscarriage rate and ectopic pregnancy rate. Fixed effects models were chosen to calculate the odds ratio (OR). Seven trials (n=1446 cases) were finally analyzed. Compared with cleavage-stage embryos transfer, the blastocyst transfer was statistically significantly associated with an increase in clinical pregnancy rate [OR 1.43; 95% confidence interval (CI), 1.15-1.78], implantation rate (OR 1.38; 95% CI, 1.09-1.74) and ongoing pregnancy rate (OR 2.15; 95% CI, 1.57-2.94), and also a reduction in the probability of first trimester miscarriage rate (OR 0.51; 95% CI, 0.30-0.87). The improvement in the live birth rate was also observed (OR 1.77; 95% CI, 1.32-2.37). Moreover, there was no evidence of difference in multiple pregnancy and ectopic pregnancy rates. The available evidences suggest that live birth and other pregnancy outcomes after fresh in vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) are significantly improved following blastocyst transfer as compared to cleavage-stage embryo transfer.

  15. Quasi-Static and High Strain Rate Compressive Response of Injection-Molded Cenosphere/HDPE Syntactic Foam

    Science.gov (United States)

    Bharath Kumar, B. R.; Singh, Ashish Kumar; Doddamani, Mrityunjay; Luong, Dung D.; Gupta, Nikhil

    2016-07-01

    High strain rate compressive properties of high-density polyethylene (HDPE) matrix syntactic foams containing cenosphere filler are investigated. Thermoplastic matrix syntactic foams have not been studied extensively for high strain rate deformation response despite interest in them for lightweight underwater vehicle structures and consumer products. Quasi-static compression tests are conducted at 10-4 s-1, 10-3 s-1 and 10-2 s-1 strain rates. Further, a split-Hopkinson pressure bar is utilized for characterizing syntactic foams for high strain rate compression. The compressive strength of syntactic foams is higher than that of HDPE resin at the same strain rate. Yield strength shows an increasing trend with strain rate. The average yield strength values at high strain rates are almost twice the values obtained at 10-4 s-1 for HDPE resin and syntactic foams. Theoretical models are used to estimate the effectiveness of cenospheres in reinforcing syntactic foams.

  16. Investigation of parameter estimation and impact of injection rate on relative permeability measurements for supercritical CO2 and water by unsteady-state method

    Science.gov (United States)

    Hiratsuka, Y.; Yamamoto, H.

    2014-12-01

    CCS (Carbon dioxide Capture and Storage) is a promising option for mitigating climate changes. To predict the behavior of injected CO2 in a deep reservoir, relative permeability of supercritical CO2 and water of the reservoir rock is one of the most fundamental and influential properties. For determining the relative permeability, we employed the unsteady state method, in which the relative permeability is determined based on history matching of transient monitoring data with a multi-phase flow model. The unsteady-state method is relatively simple and short, but obviously its accuracy strongly depends on the flow model assumed in the history matching. In this study, we conducted relative permeability measurements of supercritical CO2-water system for Berea sandstone with the unsteady-state method under a reservoir condition at a 1km depth (P= 9.5MPa, T = 44˚C). Automatic history matching was performed with an inversion simulator iTOUGH2/ECO2N for multi-phase flow system of supercritical CO2, NaCl, and water. A sensitivity analysis of relative permeability parameters for CO2 and water was carried out to better understand the uniqueness and the uncertainty of the optimum solution estimated by the history matching. Among the parameters of the Corey-type curve employed in this study, while the end-point permeability could be optimized in a limited range, the other parameters were correlated and their combinations were not unique. However it was found that any combination of these parameters results in nearly identical shapes of the curve in the range of CO2 saturation in this study (0 to 60%). The optimally estimated curve from the unsteady-method was well comparable with those from the steady-state method acquired in the previous studies. Our experiment also focuses on the impact of injection rate on the estimates of relative permeability, as it is known that the injection rate could have a significant effect on fluid distribution such as viscous fingering with

  17. Impacts of trunk and soil injections of low rates of imidacloprid on hemlock woolly adelgid (Hemiptera: Adelgidae) and eastern hemlock (Pinales: Pinaceae) health.

    Science.gov (United States)

    Eisenback, Brian M; Salom, Scott M; Kok, Loke T; Lagalante, Anthony F

    2014-02-01

    Eastern hemlocks (Tsuga canadensis Carrière) at two sites in southwestern Virginia were treated by trunk and soil injections of imidacloprid to determine the insecticide's impact on hemlock woolly adelgid, Adelges tsugae Annand. Treatments were 25, 50, and 100% of the highest labeled dosage rates for both stem and soil injection. Three and 4 yr after treatment, the half and full rates had significantly reduced A. tsugae populations, which were accompanied by increased new hemlock shoot growth and higher hemlock health scores on a visual rating of tree appearance. Imidacloprid and metabolite concentrations in tissue of treated trees were determined by liquid chromatography-tandem mass spectrometry, and A. tsugae density decreased as imidacloprid concentrations increased in wood tissue. There were no observed A. tsugae populations in all trees with imidacloprid tissue concentrations >413 ppb. Olefin, di-hydroxy, and 6-chloro-nicotinic-acid metabolites were the imidacloprid metabolites recovered in the highest concentrations. This suggests that hemlock metabolism of imidacloprid may increase efficacy of the parent compound. Stem and soil treatments of low rates of systemic imidacloprid reduce adelgid populations and promote hemlock health, but still may provide a remnant food source for beneficial predators.

  18. Injection deep level transient spectroscopy: An improved method for measuring capture rates of hot carriers in semiconductors

    Science.gov (United States)

    Fleming, R. M.; Seager, C. H.; Lang, D. V.; Campbell, J. M.

    2015-07-01

    An improved method for measuring the cross sections for carrier trapping at defects in semiconductors is described. This method, a variation of deep level transient spectroscopy (DLTS) used with bipolar transistors, is applied to hot carrier trapping at vacancy-oxygen, carbon-oxygen, and three charge states of divacancy centers (V2) in n- and p-type silicon. Unlike standard DLTS, we fill traps by injecting carriers into the depletion region of a bipolar transistor diode using a pulse of forward bias current applied to the adjacent diode. We show that this technique is capable of accurately measuring a wide range of capture cross sections at varying electric fields due to the control of the carrier density it provides. Because this technique can be applied to a variety of carrier energy distributions, it should be valuable in modeling the effect of radiation-induced generation-recombination currents in bipolar devices.

  19. FRB repetition and non-Poissonian statistics

    CERN Document Server

    Connor, Liam; Oppermann, Niels

    2016-01-01

    We discuss some of the claims that have been made regarding the statistics of fast radio bursts (FRBs). In an earlier paper \\citep{2015arXiv150505535C} we conjectured that flicker noise associated with FRB repetition could show up in non-cataclysmic neutron star emission models, like supergiant pulses. We show how the current limits of repetition would be significantly weakened if their repeat rate really were non-Poissonian and had a pink or red spectrum. Repetition and its statistics have implications for observing strategy, generally favouring shallow wide-field surveys, since in the non-repeating scenario survey depth is unimportant. We also discuss the statistics of the apparent latitudinal dependence of FRBs, and offer a simple method for calculating the significance of this effect. We provide a generalized Bayesian framework for addressing this problem, which allows for direct model comparison. It is shown how the evidence for a steep latitudinal gradient of the FRB rate is less strong than initially s...

  20. Detection of liver metastases: usefulness of dynamic spiral CT during the portal phase with a higher IV injection rate of contrast material

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Youn Sin; Cho, June Sik; Youn, Wan Gyu; Ahn, Young Jun; Choi, Chang Lak; Lee, Young Hwan [Chungnam National Univ. College of Medicine, Taejon (Korea, Republic of)

    1996-07-01

    To evaluate the usefulness of dynamic spiral computed tomography(CT) during the portal phase with a higher IV injection rate of contrast material in detecting hepatic metastases. We reviewed two-phase dynamic spiral CT in 44 patients with hepatic metastases of pathologically proven primary malignancy. One hundred and fifty ml. of non-ionic contrast material was administered with a power injector at a rate of 5ml/sec., and two-phase images at 55-80 sec.(portal phase) and 2-5min. (equilibrium phase) were obtained after the start of bolus injection. Two phase images were compared for detectability of hepatic metastases according to size, number and enhancement pattern. In cases of metastases less than 1 cm, 113 lesions(100%) that showed clearly defined hypodense lesions were detected in the portal phase of dynamic CT. However, the equilibrium phase images showed hypodense lesions in 58 cases(51%) and isodense lesions in 55 cases(49%). In cases of metastases 1-2cm in size, the portal phase images detected 70 hypodense lesions(92%) and six hyperdense lesions(8%). In the equilibrium phase, however, the lesions were hypodense in 54 cases(71%), hyperdense in four(5%), and isodense in 18(24%). In cases of metastases larger than 2cm, portal phase images showed 29 hypodense lesions(97%) and one hyperdense lesion(3%). In the equilibrium phase, however, the lesions were hypodense in 25 cases(83%), hyperdense in two(7%), and mixed in three(10%). As compared with the portal phase, most metastatic lesions were detected as poorly defined hypodense or isodense lesions in the equilibrium phase and decrease in size due to peripheral enahncement. Dynamic spiral CT during the portal phase with a higher IV injection rate(5ml/sec) of contrast material is a useful method for detecting hepatic metastases, especially small lesions less than 1cm.

  1. Transport of sucrose-modified nanoscale zero-valent iron in saturated porous media: role of media size, injection rate and input concentration.

    Science.gov (United States)

    Li, Hui; Zhao, Yong-sheng; Han, Zhan-tao; Hong, Mei

    2015-01-01

    The growing use of nanoscale zero-valent iron (NZVI) in the remediation of contaminated groundwater raises concerns regarding its transport in aquifers. Laboratory-scale sand-packed column experiments were conducted with bare and sucrose-modified NZVI (SM-NZVI) to improve our understanding of the transport of the nanoparticles in saturated porous media, as well as the role of media size, suspension injection rate and concentration on the nanoparticle behavior. As the main indicative parameters, the normalized effluent concentration was measured and the deposition rate coefficient (k) was calculated for different simulated conditions. Overall, compared to the high retention of bare NZVI in the saturated silica column, SM-NZVI suspension could travel through the coarse sand column easily. However, the transport of SM-NZVI particles was not very satisfactory in a smaller size granular matrix especially in fine silica sand. Furthermore, the value of k regularly decreased with the increasing injection rate of suspension but increased with suspension concentration, which could reflect the role of these factors in the SM-NZVI travel process. The calculation of k-value at the tests condition adequately described the experimental results from the point of deposition dynamics, which meant the assumption of first-order deposition kinetics for the transport of NZVI particles was reasonable and feasible.

  2. Capillary permeability of 99mTc-DTPA and blood flow rate in the human myocardium determined by intracoronary bolus injection and residue detection

    DEFF Research Database (Denmark)

    Svendsen, Jesper Hastrup; Efsen, F; Haunsø, S

    1992-01-01

    of 99mTc-DTPA were quantitated during coronary angiography by the single injection, residue detection method. Eighteen patients undergoing a diagnostic coronary angiography because of uncharacteristic chest pain were studied. In 12 patients with angiographically normal epicardial coronary arteries...... myocardial blood flow rate in the human heart are in accordance with values obtained by other methods, and the PS product of 99mTc-DTPA is similar to results obtained in canine hearts. Localized coronary atheroma leading to insignificant coronary artery stenosis does not produce any measurable dysfunction...

  3. Validation of a heterologous fertilization assay and comparison of fertilization rates of equine oocytes using in vitro fertilization, perivitelline, and intracytoplasmic sperm injections.

    Science.gov (United States)

    Sessions-Bresnahan, D R; Graham, J K; Carnevale, E M

    2014-07-15

    IVF in horses is rarely successful. One reason for this could be the failure of sperm to fully capacitate or exhibit hyperactive motility. We hypothesized that the zona pellucida (ZP) of equine oocytes prevents fertilization in vitro, and bypassing the ZP would increase fertilization rates. Limited availability of equine oocytes for research has necessitated the use of heterologous oocyte binding assays using bovine oocytes. We sought to validate an assay using bovine oocytes and equine sperm and then to demonstrate that bypassing the ZP using perivitelline sperm injections (PVIs) with equine sperm capacitated with dilauroyl phosphatidylcholine would result in higher fertilization rates than standard IVF in bovine and equine oocytes. In experiment 1, bovine oocytes were used for (1) IVF with bovine sperm, (2) IVF with equine sperm, and (3) intracytoplasmic sperm injections (ICSIs) with equine sperm. Presumptive zygotes were either stained with 4',6-diamidino-2-phenylindole from 18 to 26 hours at 2-hour intervals or evaluated for cleavage at 56 hours after addition of sperm. Equine sperm fertilized bovine oocytes; however, pronuclei formation was delayed compared with bovine sperm after IVF. The delayed pronuclear formation was not seen after ICSI. In experiment 2, bovine oocytes were assigned to the following five groups: (1) cumulus oocyte complexes (COCs) coincubated with bovine sperm; (2) COC exposed to sucrose then coincubated with bovine sperm; (3) COC coincubated with equine sperm; (4) COC exposed to sucrose, and coincubated with equine sperm; and (5) oocytes exposed to sucrose, and 10 to 15 equine sperm injected into the perivitelline (PV) space. Equine sperm tended (P = 0.08) to fertilize more bovine oocytes when injected into the PV space than after IVF. In experiment 3, oocytes were assigned to the following four groups: (1) IVF, equine, and bovine COC coincubated with equine sperm; (2) PVI of equine and bovine oocytes; (3) PVI with equine oocytes

  4. Metropolitan social environments and pre-HAART/HAART era changes in mortality rates (per 10,000 adult residents among injection drug users living with AIDS.

    Directory of Open Access Journals (Sweden)

    Samuel R Friedman

    Full Text Available BACKGROUND: Among the largest US metropolitan areas, trends in mortality rates for injection drug users (IDUs with AIDS vary substantially. Ecosocial, risk environment and dialectical theories suggest many metropolitan areas characteristics that might drive this variation. We assess metropolitan area characteristics associated with decline in mortality rates among IDUs living with AIDS (per 10,000 adult MSA residents after highly active antiretroviral therapy (HAART was developed. METHODS: This is an ecological cohort study of 86 large US metropolitan areas from 1993-2006. The proportional rate of decline in mortality among IDUs diagnosed with AIDS (as a proportion of adult residents from 1993-1995 to 2004-2006 was the outcome of interest. This rate of decline was modeled as a function of MSA-level variables suggested by ecosocial, risk environment and dialectical theories. In multiple regression analyses, we used 1993-1995 mortality rates to (partially control for pre-HAART epidemic history and study how other independent variables affected the outcomes. RESULTS: In multivariable models, pre-HAART to HAART era increases in 'hard drug' arrest rates and higher pre-HAART income inequality were associated with lower relative declines in mortality rates. Pre-HAART per capita health expenditure and drug abuse treatment rates, and pre- to HAART-era increases in HIV counseling and testing rates, were weakly associated with greater decline in AIDS mortality. CONCLUSIONS: Mortality among IDUs living with AIDS might be decreased by reducing metropolitan income inequality, increasing public health expenditures, and perhaps increasing drug abuse treatment and HIV testing services. Given prior evidence that drug-related arrest rates are associated with higher HIV prevalence rates among IDUs and do not seem to decrease IDU population prevalence, changes in laws and policing practices to reduce such arrests while still protecting public order should be

  5. Repetition in English Political Public Speaking

    Institute of Scientific and Technical Information of China (English)

    李红梅

    2010-01-01

    Repetition is frequently used in English political public speaking to make it easy to be remembered and powerful to move the feelings of the public. This paper is intended to analyze the functions of repetition and different levels of repetition to highlight the significance of repetition in English political public speaking and the ability of using it in practice.

  6. A CCL5 Haplotype Is Associated with Low Seropositivity Rate of HCV Infection in People Who Inject Drugs.

    Directory of Open Access Journals (Sweden)

    Kristi Huik

    Full Text Available The role of CC chemokine receptor 5 (CCR5 and its ligand CCL5 on the pathogenesis of HIV infection has been well studied but not for HCV infection. Here, we investigated whether CCL5 haplotypes influence HIV and HCV seropositivity among 373 Caucasian people who inject drugs (PWID from Estonia.Study included 373 PWID; 56% were HIV seropositive, 44% HCV seropositive and 47% co-infected. Four CCL5 haplotypes (A-D were derived from three CCL5 polymorphisms (rs2107538/rs2280788/rs2280789 typed by Taqman allelic discrimination assays. The data of CCR5 haplotypes were used from our previous study. The association between CCL5 haplotypes with HIV and/or HCV seropositivity was determined using logistic regression analysis.Possessing CCL5 haplotype D (defined by rs2107538A/rs2280788G/rs2280789C decreased the odds of HCV seropositivity compared to those not possessing it (OR = 0.19; 95% CI 0.09-0.40, which remained significant after adjustment to co-variates (OR = 0.08; 95% CI 0.02-0.29. An association of this haplotype with HIV seropositivity was not found. In step-wise logistic regression with backward elimination CCL5 haplotype D and CCR5 HHG*1 had reduced odds for HCV seropositivity (OR = 0.28 95% CI 0.09-0.92; OR = 0.23 95% CI 0.08-0.68, respectively compared to those who did not possess these haplotypes, respectively.Our results suggest that among PWID CCL5 haplotype D and CCR5 HHG*1 independently protects against HCV. Our findings highlight the importance of CCL5 genetic variability and CCL5-CCR5 axis on the susceptibility to HCV.

  7. Environmental conditions, political economy, and rates of injection drug use in large US metropolitan areas 1992-2002.

    Science.gov (United States)

    Roberts, Eric T; Friedman, Samuel R; Brady, Joanne E; Pouget, Enrique R; Tempalski, Barbara; Galea, Sandro

    2010-01-15

    City-specific studies have suggested the quality of the local environment and economic circumstances are associated with greater risk of injection drug use (IDU). No studies have assessed the relation among the quality of the local environment, economic circumstances, and IDU over time across US metropolitan areas. Annual numbers of IDUs in the 88 largest US metropolitan statistical areas (MSAs) were estimated by extrapolating, adjusting, and allocating existing estimates using various data sources. Generalized estimating equations were used to assess the relation among the quality of the local environment, metropolitan political economy, and IDU prevalence using lagged models taking into account potential confounders. MSAs with a worse local environment (measured as a one standard deviation difference) had a greater risk of IDU (relative risk [RR]=1.03, 95% confidence interval [CI]: 1.01, 1.06); similarly, a one-percentage point worsening of the political economy for an MSA was associated with greater risk of IDU (RR=1.04-1.10). Final models stratified by region indicated heterogeneity of effect by region whereby the quality of the local environment was associated with IDU strongest in the South (RR=1.12, CI: 1.05, 1.12) followed by the West (RR=1.04, CI: 1.01, 1.07) and Midwest (RR=1.03, CI: 1.00, 1.06), and the metropolitan political economy was associated with IDU in the West (RR=1.03-1.09) and Northeast (RR=1.04-1.12). Our results underscore the importance of sociopolitical factors as determinants of IDU in MSAs. Structural solutions targeted at improving environmental conditions and economic circumstances should be considered as drug use interventions. Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.

  8. New concept of combustion technology in small DI diesel engines. 4th Report. Effects of fuel injection rates on MK combustion; Kogata chokufun diesel kikan no shinnensho concept. 4. Funsharitsu no MK nensho eno eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, S.; Matsui, Y.; Kamihara, T. [Nissan Motor Co. Ltd., Tokyo (Japan)

    1997-10-01

    A previous paper showed that EGR cooling and a low compression ratio which prolongs the ignition delay can expand the area of the new combustion concept. Experimental investigations were conducted in this research to examine the effects of the fuel injection rates, the injection pressure and the injection duration, on the exhaust emissions of an engine incorporating the MK concept The results showed that a higher injection pressure was effective in reducing NOx and particulate matter (PM) under MK combustion conditions. 10 refs., 9 figs., 1 tab.

  9. High-energy feedback microwave thermotherapy and intraprostatic injections of mepivacaine and adrenaline: an evaluation of calculated cell kill accuracy and responder rate.

    Science.gov (United States)

    Stenmark, Fredrik; Brudin, Lars; Stranne, Johan; Peeker, Ralph

    2014-08-01

    The aim of this study was to evaluate cell kill accuracy and responder rate when using injections of intraprostatic mepivacaine and adrenaline (MA) before high-energy microwave thermotherapy (HE-TUMT). This retrospective evaluation encompassed 283 treatments in men with lower urinary tract symptoms or urinary retention due to benign prostatic hyperplasia. They were treated consecutively during 2003-2008 using HE-TUMT with a feedback technique. Immediately before treatment, MA was administered into the prostate via a Schelin Catheter®. Clinical outcome was evaluated 3 months after treatment using a validated symptom score, transrectal ultrasound, peak urinary flow and postvoid residual. Systematic underestimation of the resulting coagulation necrosis was a consistent finding when using MA, a calculated cell kill of 21% yielding a volume reduction of 26% for prostate volumes less than 100 ml and 31% for prostate volumes greater than or equal to 100 ml. Mean prostate volume was 74 ml and mean treatment time was 13 min. Less than 1% of the patients needed analgesics or sedatives on demand. Analysis of the data showed an estimated clinical responder rate of approximately 87%. The resulting prostate volume reduction corresponds to the earlier empirically recommended 30% cell kill for CoreTherm® without MA. The treatment concept combining CoreTherm with intraprostatic injections of MA corresponds to the clinical outcome of thermotherapy without MA, with the benefits of reduced pain, shortened treatment time and decreased energy consumption.

  10. Short-time X-ray diffraction with an efficient-optimized, high repetition-rate laser-plasma X-ray-source; Kurzzeit-Roentgenbeugung mit Hilfe einer Effizienz-optimierten, hochrepetierenden Laser-Plasma-Roentgenquelle

    Energy Technology Data Exchange (ETDEWEB)

    Kaehle, Stephan

    2009-04-23

    This thesis deals with the production and application of ultrashort X-ray pulses. In the beginning different possibilities for the production of X-ray pulses with pulse durations of below one picosecond are presented, whereby the main topic lies on the so called laser-plasma X-ray sources with high repetition rate. In this case ultrashort laser pulses are focused on a metal, so that in the focus intensities of above 10{sup 16} W/cm{sup 2} dominate. In the ideal case in such way ultrafast electrons are produced, which are responsible for line radiation. In these experiments titanium K{sub {alpha}} radiation is produced, thes photons possess an energy of 4.51 keV. For the efficient production of line radiation here the Ti:Sa laser is optimized in view of the laser energy and the pulse shape and the influence of the different parameters on the K{sub {alpha}} production systematically studied. The influences of laser intensity, system-conditioned pre-pulses and of phase modulation are checked. It turns out that beside the increasement of the K{sub {alpha}} radiation by a suited laser intensity a reduction of the X-ray background radiation is of deciding importance for the obtaining of clear diffraction images. This background radiation is mainly composed of bremsstrahlung. It can be suppressed by the avoidance of intrinsic pre-pulses and by means of 2nd-order phase modulation. By means of optical excitation and X-ray exploration experiments the production of acoustic waves after ultrashort optical excitation in a 150 nm thick Ge(111) film on Si(111) is studied. These acoustic waves are driven by thermal (in this time scale time-independent) and electronic (time dependent) pressure amounts. As essential results it turns out that the relative amount of the electronic pressure increases with decreasing excitation density. [German] Diese Arbeit befasst sich mit der Erzeugung und Anwendung ultrakurzer Roentgenimpulse. Zu Beginn werden verschiedene Moeglichkeiten zur

  11. Fertility Rates of Ewes Treated with Medroxyprogesterone and Injected with Equine Chorionic Gonadotropin plus Human Chorionic Gonadotropin in Anoestrous Season

    Directory of Open Access Journals (Sweden)

    I. W. Santos

    2010-01-01

    Full Text Available The aim of the present paper was to investigate the efficiency of the equine chorionic gonadotropin (eCG plus human chorionic gonadotropin (hCG associated with medroxyprogesterone acetate (MAP to estrous ewes synchronization. Ninety Texel ewes were investigated during seasonal anoestrous. The ewes received intravaginal sponges containing MAP (60 mg for nine days. At the time of sponges' withdrawal, the ewes were divided into three groups (G: (1 receiving 2 mL of saline i.m. (n=30, (2 receiving eCG 400 IU i.m. (n=30, and (3 receiving eCG 400 IU plus hCG 200 IU i.m. (n=30. Twelve h after sponges' removal, teaser rams were used to estrus check and remained with the ewes for 96 h. The artificial insemination was made with fresh semen 10 h after estrus detection. The effect of the treatment was not significant for the estrous rates among the groups: 73%, 90%, and 86%, respectively. The main effect was observed in the pregnancy and lambing rates among the groups: 70%, 86%, 56%, and 80%, 120%, 56%, respectively. Based on these results from our study, the use of the MAP—eCG is the best choice to improve the fertility rate on ewes.

  12. Effect of γ-dose rate and total dose interrelation on the polymeric hydrogel: A novel injectable male contraceptive

    Science.gov (United States)

    Jha, Pradeep K.; Jha, Rakhi; Gupta, B. L.; Guha, Sujoy K.

    2010-05-01

    Functional necessity to use a particular range of dose rate and total dose of γ-initiated polymerization to manufacture a novel polymeric hydrogel RISUG ® (reversible inhibition of sperm under guidance) made of styrene maleic anhydride (SMA) dissolved in dimethyl sulphoxide (DMSO), for its broad biomedical application explores new dimension of research. The present work involves 16 irradiated samples. They were tested by fourier transform infrared spectroscopy, matrix assisted laser desorption/ionization-TOF, field emission scanning electron microscopy, high resolution transmission electron microscopy, etc. to see the interrelation effect of gamma dose rates (8.25, 17.29, 20.01 and 25.00 Gy/min) and four sets of doses (1.8, 2.0, 2.2 and 2.4 kGy) on the molecular weight, molecular weight distribution and porosity analysis of the biopolymeric drug RISUG ®. The results of randomized experiment indicated that a range of 18-24 Gy/min γ-dose rate and 2.0-2.4 kGy γ-total doses is suitable for the desirable in vivo performance of the contraceptive copolymer.

  13. Effect of gamma-dose rate and total dose interrelation on the polymeric hydrogel: A novel injectable male contraceptive

    Energy Technology Data Exchange (ETDEWEB)

    Jha, Pradeep K. [School of Medical Science and Technology, Indian Institute of Technology, Kharagpur 721302 (India); Department of Management Science, U.P. Technical University, Lucknow 226021 (India); Jha, Rakhi [School of Medical Science and Technology, Indian Institute of Technology, Kharagpur 721302 (India); Toxicology Laboratory, Department of Zoology, Ch. C.S. University, Meerut 200005 (India); Gupta, B.L. [CH3/56 Kendriya Vihar, Kharghar, Sector-11, Navi Mumbai-410 210 (India); Guha, Sujoy K., E-mail: guha_sk@yahoo.co [School of Medical Science and Technology, Indian Institute of Technology, Kharagpur 721302 (India)

    2010-05-15

    Functional necessity to use a particular range of dose rate and total dose of gamma-initiated polymerization to manufacture a novel polymeric hydrogel RISUG (reversible inhibition of sperm under guidance) made of styrene maleic anhydride (SMA) dissolved in dimethyl sulphoxide (DMSO), for its broad biomedical application explores new dimension of research. The present work involves 16 irradiated samples. They were tested by fourier transform infrared spectroscopy, matrix assisted laser desorption/ionization-TOF, field emission scanning electron microscopy, high resolution transmission electron microscopy, etc. to see the interrelation effect of gamma dose rates (8.25, 17.29, 20.01 and 25.00 Gy/min) and four sets of doses (1.8, 2.0, 2.2 and 2.4 kGy) on the molecular weight, molecular weight distribution and porosity analysis of the biopolymeric drug RISUG. The results of randomized experiment indicated that a range of 18-24 Gy/min gamma-dose rate and 2.0-2.4 kGy gamma-total doses is suitable for the desirable in vivo performance of the contraceptive copolymer.

  14. Varianish: Jamming with Pattern Repetition

    Directory of Open Access Journals (Sweden)

    Jort Band

    2014-10-01

    Full Text Available In music, patterns and pattern repetition are often regarded as a machine-like task, indeed often delegated to drum Machines and sequencers. Nevertheless, human players add subtle differences and variations to repeated patterns that are musically interesting and often unique. Especially when looking at minimal music, pattern repetitions create hypnotic effects and the human mind blends out the actual pattern to focus on variation and tiny differences over time. Varianish is a musical instrument that aims at turning this phenomenon into a new musical experience for musician and audience: Musical pattern repetitions are found in live music and Varianish generates additional (musical output accordingly that adds substantially to the overall musical expression. Apart from the theory behind the pattern finding and matching and the conceptual design, a demonstrator implementation of Varianish is presented and evaluated.

  15. Optimization of injection dose based on noise-equivalent count rate with use of an anthropomorphic pelvis phantom in three-dimensional 18F-FDG PET/CT.

    Science.gov (United States)

    Inoue, Kazumasa; Kurosawa, Hideo; Tanaka, Takashi; Fukushi, Masahiro; Moriyama, Noriyuki; Fujii, Hirofumi

    2012-07-01

    The optimal injection dose for imaging of the pelvic region in 3D FDG PET tests was investigated based on the noise-equivalent count (NEC) rate with use of an anthropomorphic pelvis phantom. Count rates obtained from an anthropomorphic pelvis phantom were compared with those of pelvic images of 60 patients. The correlation between single photon count rates obtained from the pelvic regions of patients and the doses per body weight was also evaluated. The radioactivity at the maximum NEC rate was defined as an optimal injection dose, and the optimal injection dose for the body weight was evaluated. The image noise of a phantom was also investigated. Count rates obtained from an anthropomorphic pelvis phantom corresponded well with those from the human pelvis. The single photon count rate obtained from the phantom was 9.9 Mcps at the peak NEC rate. The coefficient of correlation between the single photon count rate and the dose per weight obtained from patient data was 0.830. The optimal injection doses for a patient with weighing 60 kg were estimated to be 375 MBq (6.25 MBq/kg) and 435 MBq (7.25 MBq/kg) for uptake periods of 60 and 90 min, respectively. The image noise was minimal at the peak NEC rate. We successfully estimated the optimal injection dose based on the NEC rate in the pelvic region on 3D FDG PET tests using an anthropomorphic pelvis phantom.

  16. Developments of repetitive pneumatic pipe-gun pellet injector

    Energy Technology Data Exchange (ETDEWEB)

    Sudo, Shigeru [National Inst. for Fusion Science, Nagoya (Japan); Viniar, I.

    1997-05-01

    A pellet injector of repetitive pneumatic pipe-gun type has been designed for advanced plasma fueling applications. This new concept is estimated to be able to reduce the time for pellet formation by an in situ technique from 3 - 5 minutes to 2 - 10 seconds. The basic idea of the new approach to pellet formation is to supply a hydrogen isotope pellet through a copper porous unit into a pipe-gun-type barrel. Two modes are possible: (1) to push liquid hydrogen isotope through a porous unit and re-freezing inside of the barrel, (2) to push solid hydrogen isotope through a porous unit to the inside of the barrel. This principle provides a continuous injection of an unlimited amount of pellets. For demonstration of the proof-of-principle, several experiments have been carried out. Hydrogen pellets of 3 mm in diameter and 3 to 10 mm in length were accelerated to 1.2 km/s at a rate of 1 pellet per 10 - 34 s with a manually controlled injector operation. (author)

  17. Medroxyprogesterone Injection

    Science.gov (United States)

    Medroxyprogesterone intramuscular (into a muscle) injection and medroxyprogesterone subcutaneous (under the skin) injection are used to prevent pregnancy. Medroxyprogesterone subcutaneous injection is also used to treat endometriosis (a condition in which ...

  18. Pentamidine Injection

    Science.gov (United States)

    Pentamidine injection is used to treat pneumonia caused by a fungus called Pneumocystis carinii. It is in ... Pentamidine injection comes as powder to be mixed with liquid to be injected intramuscularly (into a muscle) ...

  19. REPETITIVE CLUSTER-TILTED ALGEBRAS

    Institute of Scientific and Technical Information of China (English)

    Zhang Shunhua; Zhang Yuehui

    2012-01-01

    Let H be a finite-dimensional hereditary algebra over an algebraically closed field k and CFm be the repetitive cluster category of H with m ≥ 1.We investigate the properties of cluster tilting objects in CFm and the structure of repetitive clustertilted algebras.Moreover,we generalize Theorem 4.2 in [12](Buan A,Marsh R,Reiten I.Cluster-tilted algebra,Trans.Amer.Math.Soc.,359(1)(2007),323-332.) to the situation of CFm,and prove that the tilting graph KCFm of CFm is connected.

  20. Repetitive elements in parasitic protozoa

    Directory of Open Access Journals (Sweden)

    Clayton Christine

    2010-05-01

    Full Text Available Abstract A recent paper published in BMC Genomics suggests that retrotransposition may be active in the human gut parasite Entamoeba histolytica. This adds to our knowledge of the various types of repetitive elements in parasitic protists and the potential influence of such elements on pathogenicity. See research article http://www.biomedcentral.com/1471-2164/11/321

  1. Development of a repetitive compact torus injector

    Science.gov (United States)

    Onchi, Takumi; McColl, David; Dreval, Mykola; Rohollahi, Akbar; Xiao, Chijin; Hirose, Akira; Zushi, Hideki

    2013-10-01

    A system for Repetitive Compact Torus Injection (RCTI) has been developed at the University of Saskatchewan. CTI is a promising fuelling technology to directly fuel the core region of tokamak reactors. In addition to fuelling, CTI has also the potential for (a) optimization of density profile and thus bootstrap current and (b) momentum injection. For steady-state reactor operation, RCTI is necessary. The approach to RCTI is to charge a storage capacitor bank with a large capacitance and quickly charge the CT capacitor bank through a stack of integrated-gate bipolar transistors (IGBTs). When the CT bank is fully charged, the IGBT stack will be turned off to isolate banks, and CT formation/acceleration sequence will start. After formation of each CT, the fast bank will be replenished and a new CT will be formed and accelerated. Circuits for the formation and the acceleration in University of Saskatchewan CT Injector (USCTI) have been modified. Three CT shots at 10 Hz or eight shots at 1.7 Hz have been achieved. This work has been sponsored by the CRC and NSERC, Canada.

  2. Simplified Two-Time Step Method for Calculating Combustion and Emission Rates of Jet-A and Methane Fuel With and Without Water Injection

    Science.gov (United States)

    Molnar, Melissa; Marek, C. John

    2005-01-01

    A simplified kinetic scheme for Jet-A, and methane fuels with water injection was developed to be used in numerical combustion codes, such as the National Combustor Code (NCC) or even simple FORTRAN codes. The two time step method is either an initial time averaged value (step one) or an instantaneous value (step two). The switch is based on the water concentration in moles/cc of 1x10(exp -20). The results presented here results in a correlation that gives the chemical kinetic time as two separate functions. This two time step method is used as opposed to a one step time averaged method previously developed to determine the chemical kinetic time with increased accuracy. The first time averaged step is used at the initial times for smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, initial water to fuel mass ratio, temperature, and pressure. The second instantaneous step, to be used with higher water concentrations, gives the chemical kinetic time as a function of instantaneous fuel and water mole concentration, pressure and temperature (T4). The simple correlations would then be compared to the turbulent mixing times to determine the limiting rates of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates are used to calculate the necessary chemical kinetic times. Chemical kinetic time equations for fuel, carbon monoxide and NOx are obtained for Jet-A fuel and methane with and without water injection to water mass loadings of 2/1 water to fuel. A similar correlation was also developed using data from NASA's Chemical Equilibrium Applications (CEA) code to determine the equilibrium concentrations of carbon monoxide and nitrogen oxide as functions of overall equivalence ratio, water to fuel mass ratio, pressure and temperature (T3). The temperature of the gas entering

  3. Repetition suppression and repetition priming are processing outcomes.

    Science.gov (United States)

    Wig, Gagan S

    2012-01-01

    Abstract There is considerable evidence that repetition suppression (RS) is a cortical signature of previous exposure to the environment. In many instances RS in specific brain regions is accompanied by improvements in specific behavioral measures; both observations are outcomes of repeated processing. In understanding the mechanism by which brain changes give rise to behavioral changes, it is important to consider what aspect of the environment a given brain area or set of areas processes, and how this might be expressed behaviorally.

  4. H$^{-}$ painting injection system for the JKJ 3 GeV high-intensity proton synchrotron

    CERN Document Server

    Sakai, I; Irie, Y; Ishi, Y; Machida, S; Noda, F; Shigaki, K; Shimada, T; Sugai, I; Takeda, Y; Watanabe, Y; Yamamoto, K

    2002-01-01

    The JAERI KEK Joint Project 3 GeV proton synchrotron is designed to accelerate 8.3*l0/sup 13/ protons per pulse at a 25 Hz repetition rate. The incoming beam emittance of the 400 MeV linac is 4 pi .mm.mrad and the acceptance in the 3 GeV synchrotron is 324 pi .mm.mrad in both the horizontal and vertical planes. Painting injection is designed to realize a uniform distribution of charged particles in real space. The bump orbit for painting injection is designed to have a full acceptance of the circulating orbit through the injection period. A full-acceptance bump orbit will enable both correlated and anticorrelated painting injection. (4 refs).

  5. New Reduced Two-Time Step Method for Calculating Combustion and Emission Rates of Jet-A and Methane Fuel With and Without Water Injection

    Science.gov (United States)

    Molnar, Melissa; Marek, C. John

    2004-01-01

    A simplified kinetic scheme for Jet-A, and methane fuels with water injection was developed to be used in numerical combustion codes, such as the National Combustor Code (NCC) or even simple FORTRAN codes that are being developed at Glenn. The two time step method is either an initial time averaged value (step one) or an instantaneous value (step two). The switch is based on the water concentration in moles/cc of 1x10(exp -20). The results presented here results in a correlation that gives the chemical kinetic time as two separate functions. This two step method is used as opposed to a one step time averaged method previously developed to determine the chemical kinetic time with increased accuracy. The first time averaged step is used at the initial times for smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, initial water to fuel mass ratio, temperature, and pressure. The second instantaneous step, to be used with higher water concentrations, gives the chemical kinetic time as a function of instantaneous fuel and water mole concentration, pressure and temperature (T4). The simple correlations would then be compared to the turbulent mixing times to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates were then used to calculate the necessary chemical kinetic times. Chemical kinetic time equations for fuel, carbon monoxide and NOx were obtained for Jet-A fuel and methane with and without water injection to water mass loadings of 2/1 water to fuel. A similar correlation was also developed using data from NASA's Chemical Equilibrium Applications (CEA) code to determine the equilibrium concentrations of carbon monoxide and nitrogen oxide as functions of overall equivalence ratio, water to fuel mass ratio, pressure and temperature (T3

  6. Cohesive Function of Lexical Repetition in Text

    Institute of Scientific and Technical Information of China (English)

    张莉; 卢沛沛

    2013-01-01

    Lexical repetition is the most direct form of lexical cohesion,which is the central device for making texts hang together. Although repetition is the most direct way to emphasize,it performs the cohesive effect more apparently.

  7. Analysis of the influence of well spacing on the injection rate behaviour for water injection under fracturing conditions; Analise da influencia do espacamento de pocos na determinacao da vazao de injecao para o processo de injecao com pressao cima da pressao de fratura

    Energy Technology Data Exchange (ETDEWEB)

    Munoz Mazo, Eduin Orlando [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Centro de Estudo do Petroleo. Lab. de Simulacao de Fluxo em Meios Porosos (UNISIM); Costa, Odair Jose; Schiozer, Denis Jose [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia de Petroleo

    2008-07-01

    Water injection under fracturing conditions is a proved manner of overcoming injectivity loss in reservoirs affected by formation damage. Nevertheless, as shown by Munoz Mazo et al. (2006), there is the possibility of the generated and propagated fractures intercept the producer wells making that the injected water shall be re-circulated into the reservoir instead of its main function which is to drive the oil contained in the reservoir pore space. The objective of this work is to determine the influence of well spacing on the determination of the water injection rate under fracturing conditions, aiming to study its effects on the production performance and the sweep efficiency. To accomplish the work, an analytical model for representing the absolute permeability reduction near the wellbore and a model which reproduces the fracture propagation in a coupled manner are used. In this way the model sensitivity to several well spacing and the injection rate effects are analyzed using the Net Present Value and the sweep efficiency is evaluated as a function of the Recovery Factor. The results show that the water injection under fracturing conditions is an effective way of overcoming the injectivity loss problem and evidence its sensitivity to different spacing between the injector and the producer wells. (author)

  8. Doripenem Injection

    Science.gov (United States)

    ... injection is in a class of medications called carbapenem antibiotics. It works by killing bacteria.Antibiotics such ... if you are allergic to doripenem injection; other carbapenem antibiotics such as imipenem/cilastatin (Primaxin) or meropenem ( ...

  9. Methotrexate Injection

    Science.gov (United States)

    Methotrexate injection is used alone or in combination with other medications to treat gestational trophoblastic tumors (a ... in bones) after surgery to remove the tumor. Methotrexate injection is also used to treat severe psoriasis ( ...

  10. Bendamustine Injection

    Science.gov (United States)

    Bendamustine injection is used to treat chronic lymphocytic leukemia (CLL; a type of cancer of the white ... injection. You should use birth control to prevent pregnancy in yourself or your partner during your treatment ...

  11. Caspofungin Injection

    Science.gov (United States)

    Caspofungin injection is used in adults and children 3 months of age and older to treat yeast ... people with a weakened ability to fight infection. Caspofungin injection is in a class of antifungal medications ...

  12. Temozolomide Injection

    Science.gov (United States)

    Temozolomide is used to treat certain types of brain tumors. Temozolomide is in a class of medications called alkylating ... Temozolomide injection comes as a powder to be added to fluid and injected over 90 minutes intravenously ( ...

  13. Pembrolizumab Injection

    Science.gov (United States)

    Pembrolizumab injection is used to treat melanoma (a type of skin cancer) that cannot be treated with ... who have a specific type of melanoma tumor. Pembrolizumab injection is also used to treat a certain ...

  14. Lacosamide Injection

    Science.gov (United States)

    ... injection is in a class of medications called anticonvulsants. It works by decreasing abnormal electrical activity in ... older (about 1 in 500 people) who took anticonvulsants like lacosamide injection to treat various conditions during ...

  15. Midazolam Injection

    Science.gov (United States)

    ... injection is in a class of medications called benzodiazepines. It works by slowing activity in the brain ... breast-feeding.talk to your doctor about the risks and benefits of receiving midazolam injection if you ...

  16. Doxycycline Injection

    Science.gov (United States)

    Doxycycline injection is used to treat or prevent bacterial infections, including pneumonia and other respiratory tract infections. ... certain skin, genital, intestine, and urinary system infections. Doxycycline injection may be used to treat or prevent ...

  17. Paclitaxel Injection

    Science.gov (United States)

    ... with other medications. Paclitaxel injection manufactured with polyoxyethylated castor oil is used to treat ovarian cancer (cancer that ... cancer, and lung cancer. Paclitaxel injection with polyoxyethylated castor oil is also used to treat Kaposi's sarcoma (a ...

  18. Etanercept Injection

    Science.gov (United States)

    ... will be using the prefilled syringe or automatic injection device, tell your doctor if you or the person who will be injecting the medication for you are allergic to rubber or latex.tell your doctor and pharmacist what ...

  19. Cyclosporine Injection

    Science.gov (United States)

    Cyclosporine injection is used with other medications to prevent transplant rejection (attack of the transplanted organ by ... who have received kidney, liver, and heart transplants. Cyclosporine injection should only be used to treat people ...

  20. Estrogen Injection

    Science.gov (United States)

    The estradiol cypionate and estradiol valerate forms of estrogen injection are used to treat hot flushes (hot ... should consider a different treatment. These forms of estrogen injection are also sometimes used to treat the ...

  1. Cefotaxime Injection

    Science.gov (United States)

    Cefotaxime injection is used to treat certain infections caused by bacteria including pneumonia and other lower respiratory ... skin, blood, bone, joint, and urinary tract infections. Cefotaxime injection may also be used before surgery, and ...

  2. Patient-rated suitability of a novel electronic device for self-injection of subcutaneous interferon beta-1a in relapsing multiple sclerosis: an international, single-arm, multicentre, Phase IIIb study

    Directory of Open Access Journals (Sweden)

    Verdun di Cantogno Elisabetta

    2010-04-01

    Full Text Available Abstract Background Multiple sclerosis (MS currently requires long-term treatment with disease-modifying drugs, administered parenterally up to once daily. The need for regular self-injection can be a barrier to treatment for many patients. Autoinjectors can help patients overcome problems or concerns with self-injection and could, therefore, improve treatment adherence. This study was performed to assess the suitability of a new electronic device for the subcutaneous (sc administration of interferon (IFN beta-1a, 44 mcg three times weekly, for relapsing MS. Methods In this Phase IIIb, multicentre, single-arm study, patients with relapsing MS who had been consistently self-injecting sc IFN beta-1a using an autoinjector for at least 6 weeks were taught to use the new device and self-administered treatment for 12 weeks thereafter. Patient-rated suitability of the device was assessed at the end of Week 12 using the Patient User Trial Questionnaire. Patient satisfaction with, and evaluation of, the injection process was assessed using the MS Treatment Concern Questionnaire. Trainers evaluated the device using the Trainer User Trial Questionnaire. Results At Week 12, 71.6% (73/102 of patients considered the device 'very suitable' or 'suitable' for self-injection; 92.2% (94/102 reported some degree of suitability and only 7.8% (8/102 found the device 'not at all suitable'. At Weeks 4, 8 and 12, most patients reported that injection preparation and clean-up, performing injections and ease of device use in the previous 4 weeks compared favourably with, or was equivalent to, their previous experience of self-injection. Injection-related pain, injection reactions and 'flu-like' symptoms remained stable over the 12 weeks. Each device feature was rated 'very useful' or 'useful' by at least 80% of patients. All trainers and 95.2% (99/104 of patients found device functions 'very easy' or 'easy' to use. Overall convenience was considered the most important

  3. Patient-rated suitability of a novel electronic device for self-injection of subcutaneous interferon beta-1a in relapsing multiple sclerosis: an international, single-arm, multicentre, Phase IIIb study

    Science.gov (United States)

    2010-01-01

    Background Multiple sclerosis (MS) currently requires long-term treatment with disease-modifying drugs, administered parenterally up to once daily. The need for regular self-injection can be a barrier to treatment for many patients. Autoinjectors can help patients overcome problems or concerns with self-injection and could, therefore, improve treatment adherence. This study was performed to assess the suitability of a new electronic device for the subcutaneous (sc) administration of interferon (IFN) beta-1a, 44 mcg three times weekly, for relapsing MS. Methods In this Phase IIIb, multicentre, single-arm study, patients with relapsing MS who had been consistently self-injecting sc IFN beta-1a using an autoinjector for at least 6 weeks were taught to use the new device and self-administered treatment for 12 weeks thereafter. Patient-rated suitability of the device was assessed at the end of Week 12 using the Patient User Trial Questionnaire. Patient satisfaction with, and evaluation of, the injection process was assessed using the MS Treatment Concern Questionnaire. Trainers evaluated the device using the Trainer User Trial Questionnaire. Results At Week 12, 71.6% (73/102) of patients considered the device 'very suitable' or 'suitable' for self-injection; 92.2% (94/102) reported some degree of suitability and only 7.8% (8/102) found the device 'not at all suitable'. At Weeks 4, 8 and 12, most patients reported that injection preparation and clean-up, performing injections and ease of device use in the previous 4 weeks compared favourably with, or was equivalent to, their previous experience of self-injection. Injection-related pain, injection reactions and 'flu-like' symptoms remained stable over the 12 weeks. Each device feature was rated 'very useful' or 'useful' by at least 80% of patients. All trainers and 95.2% (99/104) of patients found device functions 'very easy' or 'easy' to use. Overall convenience was considered the most important benefit of the device

  4. Effect of ethnicity on live birth rates after in vitro fertilisation/intracytoplasmic sperm injection treatment: analysis of UK national database.

    Science.gov (United States)

    Maalouf, W; Maalouf, W; Campbell, B; Jayaprakasan, K

    2017-05-01

    To evaluate the effect of ethnicity of women on the outcome of in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) treatment. Observational cohort study. UK National Database. Data from 2000 to 2010 involving 38 709 women undergoing their first IVF/ICSI cycle were analysed. Anonymous data were obtained from the Human Fertilization and Embryology Authority (HFEA), the statutory regulator of IVF and ICSI treatment in the UK. Data analysis was performed by regression analysis with adjustment for age, cause and type of infertility and treatment type (IVF or ICSI) to express results as odds ratio (OR) and 95% confidence intervals (95% CI). Live birth rate per cycle of IVF or ICSI treatment. While white Irish (OR 0.73; 95% CI 0.60-0.90), Indian (0.85; 0.75-0.97), Bangladeshi (0.53: 0.33-0.85), Pakistani (0.68; 0.58-0.80), Black African (0.60; 0.51-0.72), and other non-Caucasian Asian (0.86; 0.73-0.99) had a significantly lower odds of live birth rates per fresh IVF/ICSI cycle than White British women, ethnic groups of White European (1.04; 0.96-1.13), Chinese (1.12; 0.77-1.64), Black Caribbean (0.76; 0.51-1.13), Middle Eastern (0.73; 0.51-1.04), Mediterranean European (1.18; 0.83-1.70) and Mixed race population (0.94; 0.73-1.19) had live birth rates that did not differ significantly. The cumulative live birth rates showed similar patterns across different ethnic groups. Ethnicity is a major determinant of IVF/ICSI treatment outcome as indicated by significantly lower live birth rates in some of the ethnic minority groups compared with white British women. Ethnicity affects IVF outcome with lower live birth rates in some ethnic groups more than in white British. © 2016 Crown copyright. BJOG:An International Journal of Obstetrics and Gynaecology © 2016 Royal College of Obstetricians and Gynaecologists.

  5. Ustekinumab Injection

    Science.gov (United States)

    ... Do not inject into an area where the skin is tender, bruised, red, or hard or where you have scars or stretch marks.Your doctor or pharmacist will ... injection.you should know that ustekinumab injection may decrease your ability ... new or changing skin lesions, minor infections (such as open cuts or ...

  6. Ranitidine Injection

    Science.gov (United States)

    Ranitidine injection comes as a solution (liquid) to be mixed with another fluid and injected intravenously (into a vein) over 5 to 20 minutes. Ranitidine may also be injected into a muscle. It is usually given every 6 to 8 hours, but may also be given ...

  7. 提高分注井作业成功率工艺研究与应用%Improve the success rate of separate injection well technology research and application

    Institute of Scientific and Technical Information of China (English)

    王薇; 陆小兵; 魏向军

    2012-01-01

    分层注水是解决油田开发过程中层间矛盾,实现有效注水,提高水驱动用程度及采收率的重要手段,而分注井作业的成功与否直接关系到分层注水效果的好坏。本文通过对长庆超低渗透油田分注现状进行调研,分析了影响超低渗透油藏分注井作业成功率低的主要原因,并针对存在问题开展了小卡距分注、免投死水嘴以及测调一体化工艺研究与应用,现场试验成功率100%,有效地提高分注井作业成功率。%Stratified water injection is to solve the contradiction between the middle of the oil field development process to achieve effective water injection,to improve an important means of water driving the degree of recovery,while the sub-injection wells operating success of a direct relationship to the stratified injection effect of good or bad. In this paper, ultra-low permeability in Changqing Oilfield separate injection status quo research analyzed the effect on the main reason for low success rate of sub-injection wells operating,and problems to car- ry out the technology and application to a small card from the separate injection, free vote in the dead tap cast and test deployment of integration, the success rate of 100 % in field test , effectively improve the success rate of sub-injection wells operating.

  8. Dimethyl Ether Injection Studies

    DEFF Research Database (Denmark)

    Sorenson, Spencer C.; Glensvig, Michael; Abata, Duane L.

    1998-01-01

    effects of DME in high pressure injection have also been observed. DME has a higher compressibility than diesel fuel, resulting in larger pressure oscillations in the injection system during the injection process. The oscillations with DME also have a slower delay rate than those of diesel fuel......A series of preliminary investigations has been performed in order to investigate the behavior of DME in a diesel injection environment. These studies have in-cluded visual observations of the spray penetration and angles for high pressure injection into Nitrogen using conventional jerk pump...... in the same system. As a first attempt to simulate combustion of DME in Diesel engines, the results of the spray studies have been incorporated into a simplified spray combustion model. A turbulent jet structure was adjusted to fit the penetration rates of the observed sprays. The observed spray widths agreed...

  9. Circuit considerations for repetitive railguns

    Energy Technology Data Exchange (ETDEWEB)

    Honih, E.M.

    1986-01-01

    Railgun electromagnetic launchers have significant military and scientific potential. They provide direct conversion of electrical energy to projectile kinetic energy, and they offer the hope of achieving projectile velocities greatly exceeding the limits of conventional guns. With over 10 km/sec already demonstrated, railguns are attracting attention for tactical and strategic weapons systems and for scientific equation-of-state research. The full utilization of railguns will require significant improvements in every aspect of system design - projectile, barrel, and power source - to achieve operation on a large scale. This paper will review fundamental aspects of railguns, with emphasis on circuit considerations and repetitive operation.

  10. The influence of plasma horizontal position on the neutron rate and flux of neutral atoms in injection heating experiment on the TUMAN-3M tokamak

    Science.gov (United States)

    Kornev, V. A.; Chernyshev, F. V.; Melnik, A. D.; Askinazi, L. G.; Wagner, F.; Vildjunas, M. I.; Zhubr, N. A.; Krikunov, S. V.; Lebedev, S. V.; Razumenko, D. V.; Tukachinsky, A. S.

    2013-11-01

    Horizontal displacement of plasma along the major radius has been found to significantly influence the fluxes of 2.45 MeV DD neutrons and high-energy charge-exchange atoms from neutral beam injection (NBI) heated plasma of the TUMAN-3M tokamak. An inward shift by Δ R = 1 cm causes 1.2-fold increase in the neutron flux and 1.9-fold increase in the charge-exchange atom flux. The observed increase in the neutron flux is attributed to joint action of several factors-in particular, improved high-energy ion capture and confinement and, probably, decreased impurity inflow from the walls, which leads to an increase in the density of target ions. A considerable increase in the flux of charge-exchange neutrals in inward-shifted plasma is due to the increased number of captured high-energy ions and, to some extent, the increased density of the neutral target. As a result of the increase in the content of high-energy ions, the central ion temperature T i (0) increased from 250 to 350 eV. The dependence of the neutron rate on major radius R 0 should be taken into account when designing compact tokamak-based neutron sources.

  11. Effect of repetitive mckenzie lumbar spine exercises on cardiovascular system

    Directory of Open Access Journals (Sweden)

    Agrawal Sonal S

    2014-07-01

    Full Text Available Background & Purpose: McKenzie exercises for the lumbar spine, which are done repeatedly, such as flexion in standing (FIS, extension in standing flexion in lying (FIL & extension in lying (EIL have been used in the management of low back pain for over three decades. The cardiovascular effects of exercises that involve postural stabilization, arm exercises and of exercises performed in lying are well known, but there are seldom studies performed to assess the cardiovascular effects of these commonly used McKenzie exercises. Therefore the study focused on evaluating the effects of 4 commonly used McKenzie exercises on the cardiovascular system. Methods: 80 subjects in the age group of 20-59 years were randomly assigned into 4 groups according to their age, such that such that each group comprised of an equal number of subjects & equal number of males & females. Each subject performed all the 4 exercises (FIS, EIS, FIL & EIL for 10, 15 & 20 repetitions respectively. Heart rate, blood pressure & rate pressure product were recorded before & after each set of repetitions & after each type of exercise. Results: Repetitive McKenzie lumbar spine exercises had cardiovascular effects in apparently healthy subjects (both male & female. Exercises performed in lying were hemodynamically more demanding than that performed in standing, also exercises involving flexion of the lumbar spine elicited greater cardiovascular demand as compared to extension exercises i.e. FIL>EIL>FIS>EIS irrespective of the number of repetitions, 10, 15 or 20. The cardiovascular demand for a given subject increased as the number of repetitions increased, for all the 4 exercises. Conclusion: McKenzie exercises when done repetitively have cardiovascular effects in healthy subjects.

  12. Tachyphylaxis associated with repeated epidural injections of lidocaine is not related to changes in distribution or the rate of elimination from the epidural space

    DEFF Research Database (Denmark)

    Mogensen, T; Simonsen, L; Scott, N B

    1989-01-01

    technetium-99m diethylenetriaminepentaacetate [99mTc-DTPA]) and elimination of lidocaine from the epidural space (as measured by serum concentrations of lidocaine) was investigated in 18 patients undergoing minor surgery during lumbar epidural analgesia. Twelve patients received four injections of 20 mL of 2......% lidocaine at 2-hr intervals. Epidural distribution was assessed by injection of 99mTc-DTPA diluted in saline on the preoperative day and diluted in an equal volume of 2% lidocaine on the morning before surgery and again after the fourth injection of lidocaine 6 hr later. The distribution of 99mTc-DTPA...

  13. Digital repetitive control under varying frequency conditions

    OpenAIRE

    Ramos Fuentes, Germán Andrés

    2012-01-01

    The tracking/rejection of periodic signals constitutes a wide field of research in the control theory and applications area and Repetitive Control has proven to be an efficient way to face this topic; however, in some applications the period of the signal to be tracked/rejected changes in time or is uncertain, which causes and important performance degradation in the standard repetitive controller. This thesis presents some contributions to the open topic of repetitive control workin...

  14. Chromosomal aberrations in in-vitro matured oocytes influence implantation and ongoing pregnancy rates in a mouse model undergoing intracytoplasmic sperm injection.

    Directory of Open Access Journals (Sweden)

    Min Li

    Full Text Available Implantation failure and early pregnancy loss have been reported to be closely related to the quality of mammalian oocytes; however, the pregnant outcome of embryos from in-vitro matured (IVM oocytes remains unknown. In this study we examined spindle assembly and chromosome segregation during differentiation, and the duration of IVM of mouse oocytes. The resulting implantation and pregnancy outcomes were analyzed to clarify the relationship between the spindle and chromosomes of IVM oocytes and implantation and early pregnancy. Cumulus-enclosed germinal vesicle oocytes were collected and randomly cultured in IVM medium with different IVM durations. One part of IVM oocytes were analyzed the spindle and chromosome morphology by immunofluorescence method, and the other part of them were fertilized by intracytoplasmic sperm injection. The resulting embryos were transferred into pseudo-pregnant female mice, and the post-implantation and full term development was observed. The chromosome aberrations and incorrect spindle assembly seems not affect the early development and blastocyst cell number derived from IVM oocytes, however the development potential of the resulting embryos after implantation were significant decreased with the ratio increasing of chromosome aberrations and incorrect spindle assembly. Accordingly, the full-term development was also decreased. In conclusion, the present study showed the spindle assembly of in vitro-matured oocytes was one of the most important factors that affected the implantation and ongoing pregnancy rates of IVM oocytes, and the improvement by an appropriate duration of maturation in vitro will enhance the post-implantation development potential of the resulting embryos, and decrease implantation failure and early pregnancy loss.

  15. Chromosomal aberrations in in-vitro matured oocytes influence implantation and ongoing pregnancy rates in a mouse model undergoing intracytoplasmic sperm injection.

    Science.gov (United States)

    Li, Min; Zhao, Hong-Cui; Li, Rong; Yu, Yang; Qiao, Jie

    2014-01-01

    Implantation failure and early pregnancy loss have been reported to be closely related to the quality of mammalian oocytes; however, the pregnant outcome of embryos from in-vitro matured (IVM) oocytes remains unknown. In this study we examined spindle assembly and chromosome segregation during differentiation, and the duration of IVM of mouse oocytes. The resulting implantation and pregnancy outcomes were analyzed to clarify the relationship between the spindle and chromosomes of IVM oocytes and implantation and early pregnancy. Cumulus-enclosed germinal vesicle oocytes were collected and randomly cultured in IVM medium with different IVM durations. One part of IVM oocytes were analyzed the spindle and chromosome morphology by immunofluorescence method, and the other part of them were fertilized by intracytoplasmic sperm injection. The resulting embryos were transferred into pseudo-pregnant female mice, and the post-implantation and full term development was observed. The chromosome aberrations and incorrect spindle assembly seems not affect the early development and blastocyst cell number derived from IVM oocytes, however the development potential of the resulting embryos after implantation were significant decreased with the ratio increasing of chromosome aberrations and incorrect spindle assembly. Accordingly, the full-term development was also decreased. In conclusion, the present study showed the spindle assembly of in vitro-matured oocytes was one of the most important factors that affected the implantation and ongoing pregnancy rates of IVM oocytes, and the improvement by an appropriate duration of maturation in vitro will enhance the post-implantation development potential of the resulting embryos, and decrease implantation failure and early pregnancy loss.

  16. A repetitive 0.14 THz relativistic surface wave oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guangqiang; Tong Changjiang; Li Xiaoze; Wang Xuefeng; Li Shuang; Lu Xicheng [Northwest Institute of Nuclear Technology, P.O. Box 69-1, Xi' an 710024 (China); Wang Jianguo [Northwest Institute of Nuclear Technology, P.O. Box 69-1, Xi' an 710024 (China); School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China)

    2013-04-15

    Preliminary experimental results of a repetitive 0.14 THz overmoded relativistic surface wave oscillator (RSWO) are presented in this paper. The repetitive RSWO is developed by using a rectangularly corrugated slow-wave structure with overmoded ratio of 3 and a foilless diode emitting annular electron beam with thickness of 0.5 mm. The high quality electron beams at the repetition rate of 10 are obtained over a wide range of diode voltage (180 kV < U < 240 kV) and current (700 A < I < 1.2 kA). The generation experiments of RSWO are conducted at an axial pulsed magnetic field whose maximum strength and duration can reach about 2.7 T and 1 s, respectively. The experimental results show that the RSWO successfully produces reasonable uniform terahertz pulses at repetition rate of 10, and the pulse duration, frequency, and power of a single pulse are about 1.5 ns, 0.154 THz, and 2.6 MW, respectively, whereas the dominated radiation mode of the RSWO is TM{sub 02}.

  17. [Evaluation of genotoxicity induced by repetitive administration of local anaesthetics: an experimental study in rats].

    Science.gov (United States)

    Nai, Gisele Alborghetti; de Oliveira, Mariliza Casanova; de Oliveira Tavares, Graziela; Pereira, Laís Fabrício Fonseca; Soares, Nádia Derli Salvador Lemes; Silva, Patrícia Gatti

    2015-01-01

    Previous studies regarding the effects of some local anaesthetics have suggested that these agents can cause genetic damage. However, they have not been tested for genotoxicity related to repetitive administration. The aim of this study was to evaluate the genotoxic potential of local anaesthetics upon repetitive administration. 80 male Wistar rats were divided into: group A - 16 rats intraperitoneally injected with lidocaine hydrochloride 2%; group B - 16 rats IP injected with mepivacaine 2%; group C - 16 rats intraperitoneally injected with articaine 4%; group D - 16 rats IP injected with prilocaine 3% (6.0mg/kg); group E - 8 rats subcutaneously injected with a single dose of cyclophosphamide; and group F - 8 rats intraperitoneally injected with saline. Eight rats from groups A to D received a single dose of anaesthetic on Day 1 of the experiment; the remaining rats were dosed once a day for 5 days. The median number of micronuclei in the local anaesthetics groups exposed for 1 or 5 days ranged from 0.00 to 1.00, in the cyclophosphamide-exposed group was 10.00, and the negative control group for 1 and 5 days was 1.00 and 0.00, respectively (plocal anaesthetic groups (p=0.0001), but not between the negative control group and the local anaesthetic groups (p>0.05). No genotoxicity effect was observed upon repetitive exposure to any of the local anaesthetics evaluated. Copyright © 2013 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

  18. Evaluation of genotoxicity induced by repetitive administration of local anaesthetics: an experimental study in rats

    Directory of Open Access Journals (Sweden)

    Gisele Alborghetti Nai

    2015-02-01

    Full Text Available BACKGROUND AND OBJECTIVE: Previous studies regarding the effects of some local anaesthetics have suggested that these agents can cause genetic damage. However, they have not been tested for genotoxicity related to repetitive administration. The aim of this study was to evaluate the genotoxic potential of local anaesthetics upon repetitive administration. METHODS: 80 male Wistar rats were divided into: group A - 16 rats intraperitoneally injected with lidocaine hydrochloride 2%; group B - 16 rats IP injected with mepivacaine 2%; group C - 16 rats intraperitoneally injected with articaine 4%; group D - 16 rats IP injected with prilocaine 3% (6.0 mg/kg; group E - 8 rats subcutaneously injected with a single dose of cyclophosphamide; and group F - 8 rats intraperitoneally injected with saline. Eight rats from groups A to D received a single dose of anaesthetic on Day 1 of the experiment; the remaining rats were dosed once a day for 5 days. RESULTS: The median number of micronuclei in the local anaesthetics groups exposed for 1 or 5 days ranged from 0.00 to 1.00, in the cyclophosphamide-exposed group was 10.00, and the negative control group for 1 and 5 days was 1.00 and 0.00, respectively (p 0.05. CONCLUSION: No genotoxicity effect was observed upon repetitive exposure to any of the local anaesthetics evaluated.

  19. [Repetition and fear of dying].

    Science.gov (United States)

    Lerner, B D

    1995-03-01

    In this paper a revision is made of the qualifications of Repetition (R) in Freuds work, i.e. its being at the service of the Pleasure Principle and, beyond it, the binding of free energy due to trauma. Freud intends to explain with this last concept the "fort-da" and the traumatic dreams (obsessively reiterated self-reproaches may be added to them). The main thesis of this work is that R. is not only a defense against the recollection of the ominous past (as in the metaphorical deaths of abandonment and desertion) but also a way of maintaining life and identify fighting against the inescapable omninous future (known but yet experienced), i.e. our own death. Some forms of R. like habits, identificatory behaviors and sometimes even magic, are geared to serve the life instinct. A literary illustration shows this desperate fight.

  20. Pressure rig for repetitive casting

    Science.gov (United States)

    Vasquez, Peter (Inventor); Hutto, William R. (Inventor); Philips, Albert R. (Inventor)

    1989-01-01

    The invention is a pressure rig for repetitive casting of metal. The pressure rig performs like a piston for feeding molten metal into a mold. Pressure is applied to an expandable rubber diaphragm which expands like a balloon to force the metal into the mold. A ceramic cavity which holds molten metal is lined with blanket-type insulating material, necessitating only a relining for subsequent use and eliminating the lengthy cavity preparation inherent in previous rigs. In addition, the expandable rubber diaphragm is protected by the insulating material thereby decreasing its vulnerability to heat damage. As a result of the improved design the life expectancy of the pressure rig contemplated by the present invention is more than doubled. Moreover, the improved heat protection has allowed the casting of brass and other alloys with higher melting temperatures than possible in the conventional pressure rigs.

  1. Injection MD

    CERN Document Server

    Bartmann, W; Bracco, C; Drosdal, L; Gianfelice, E; Goddard, B; Kain, V; Papaphilippou, Y; Vanbavinckhove, G

    2012-01-01

    This note summarizes the results obtained at injection during the 2nd MD block and the floating MD block in July. Highlights are presented for injection in the LHC with the Q20 SPS optics, influence of the supercycle and injection with 25 ns bunch spacing. Beams were successfully injected into the LHC using the Q20 optics [1, 3]. Small corrections were needed to steer the beam in the transfer lines. Dispersion measurements were conducted for both beams. The horizontal normalized dispersion in TI2 was a factor 2 smaller for Q20 with respect to Q26, for TI8 on the other hand the opposite was observed. The results for injection loss dependency on super cycle composition show only a small increase in losses for beam 2. The losses observed must therefore mainly come from other sources such as shot-by-shot stability or quality of scraping. For the injection with 25 ns bunch spacing bunches were injected for both beams. For B1 up to the maximum of 288 bunches. For B2 on the other only up to 144 bunches were injected...

  2. Interaction of Repetitively Pulsed High Energy Laser Radiation With Matter

    Science.gov (United States)

    Hugenschmidt, Manfred

    1986-10-01

    The paper is concerned with laser target interaction processes involving new methods of improving the overall energy balance. As expected theoretically, this can be achieved with high repetition rate pulsed lasers even for initially highly reflecting materials, such as metals. Experiments were performed by using a pulsed CO2 laser at mean powers up to 2 kW and repetition rates up to 100 Hz. The rates of temperature rise of aluminium for example were thereby increased by lore than a factor of 3 as compared to cw-radiation of comparable power density. Similar improvements were found for the overall absorptivities that were increased by this method by more than an order of magnitude.

  3. Output Characteristics of LD End-pumping Nd:YVO_4 Laser with Pulse Repetition Rates up to 1 kHz%LD端面抽运1KHz电光调Q Nd:YVO_4激光器输出功率特性研究

    Institute of Scientific and Technical Information of China (English)

    宋标; 李传起; 谢爱根; 王铁邦

    2009-01-01

    A laser diode (LD) continuous-wave (CW) end-pumping high repetition rate electro-optic ( EO) Q-switching Nd : YVO_4 laser was experimentally and theoretically studied. In experiments , using BBO single crystal as an EO Q-switch,with 10 W pump power ,about 170 mW average power was obtained at 1 kHz repetition rate. The dips in the output power curves were analyzed, A reasonable explaination was given and a way of improving the output was pointed out through the graphic analysis of the transmitting and transforming circle.%报道了全固态激光器连续抽运高重复率电光调Q Nd:YVO_4激光器的实验和理论分析结果,用BBO晶体作电光调Q元件,在激光二极管(LD)端面抽运Nd:YVO_4激光器中实现了较高重复率的电光调Q输出.实验中在1 kHz重复率下,抽运功率为10 W时,平均功率超过170 mW.对输出功率曲线中的凹陷现象进行了分析,指出了制约激光器的内在诸因素,并用传播圆-变换圆图解分析方法给出了合理的解释.

  4. Hepatic Arterial Phase on Gadoxetic Acid-Enhanced Liver MR Imaging: A Randomized Comparison of 0.5 mL/s and 1 mL/s Injection Rates

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Mo; Heo, Suk Hee; Kim, Jin Woong; Lim, Hyo Soon; Jeong, Yong Yeon; Kang, Heoung Keun [Dept. of Radiology, Chonnam National University Hwasun Hospital, Hwasun (Korea, Republic of); Shin, Sang Soo [Dept. of Radiology, Chonnam National University Hospital, Gwangju (Korea, Republic of)

    2014-10-15

    To compare gadoxetic acid injection rates of 0.5 mL/s and 1 mL/s for hepatic arterial-phase magnetic resonance (MR) imaging. In this prospective study, 101 consecutive patients with suspected focal liver lesions were included and randomly divided into two groups. Each group underwent dynamic liver MR imaging using a 3.0-T scanner after an intravenous injection of gadoxetic acid at rates of either 0.5 mL/s (n = 50) or 1 mL/s (n = 51). Arterial phase images were analyzed after blinding the injection rates. The signal-to-noise ratios (SNRs) of the liver, aorta, portal vein, hepatic vein, spleen, and pancreas were measured. The contrast-to-noise ratios (CNRs) of the hepatocellular carcinomas (HCC) were calculated. Finally, two experienced radiologists were independently asked to identify, if any, HCCs in the liver on the images and score the image quality in terms of the presence of artifacts and the proper enhancement of the liver, aorta, portal vein, hepatic vein, hepatic artery, spleen, pancreas, and kidney. The SNRs were not significantly different between the groups (p = 0.233-0.965). The CNRs of the HCCs were not significantly different (p = 0.597). The sensitivity for HCC detection and the image quality scores were not significantly different between the two injection rates (p = 0.082-1.000). Image quality and sensitivity for hepatic HCCs of arterial-phase gadoxetic acid-enhanced MR were not significantly improved by reducing the contrast injection rate to 0.5 mL/s compared with 1 mL/s.

  5. Mid-luteal phase injection of subcutaneous leuprolide acetate improves live delivered pregnancy and implantation rates in younger women undergoing in vitro fertilization-embryo transfer (IVF-ET).

    Science.gov (United States)

    Check, J H; Wilson, C; Cohen, R; Choe, J K; Corley, D

    2015-01-01

    To see if the single injection of one mg of the gonadotropin releasing hormone agonist (GnRHa) leuprolide acetate given in the mid-luteal phase can increase live delivered pregnancy and implantation rates. Furthermore the purpose was to determine if improvement was found, did the mechanism involve increased secretion of human chorionic gonadotropin (hCG). A prospective study was conducted in women aged 35 who were undergoing in vitro fertilization-embryo transfer (IVF-ET). They were advised of data from Tesarik et al. and a previous pilot study conducted in the present IVF center showing improved pregnancy rates with the injection of a GnRHa three days after embryo transfer. They were offered the option of returning for a one-mg injection s.c. of leuprolide acetate or not. Clinical and live delivered pregnancy rates were compared according to those taking or not the leuprolide acetate one-mg injection. Chi-square analysis was used for statistical comparisons. Serum beta-hCG levels were compared between those conceiving with or without the extra injection of leuprolide. There was a non-significant trend for higher live delivered pregnancy rates in those taking leuprolide (47.8%, 64/134) vs. those not taking it (38.6%, 76/197). For those pregnant there was no difference in hCG levels according to taking the GnRHa or not. The 25% increased live delivered pregnancy rate per transfer was insufficiently powered to detect a significant difference. The results do justify continuing the study. Perhaps the difference could be wider using a slightly older age group whose embryos are frequently less hearty.

  6. Efeito da ordem dos exercícios no número de repetições e na percepção subjetiva de esforço em homens treinados em força The effect of the exercises order on number of repetitions and rate of perceived effort in resistance trained men

    Directory of Open Access Journals (Sweden)

    Saulo Gil

    2011-03-01

    Full Text Available A ordem dos exercícios refere-se à sequência de execução durante uma sessão de treinamento. Evidências demonstram que essa ordem pode afetar o número de repetições realizadas nos exercícios. A percepção subjetiva de esforço (PSE, assim como o número de repetições realizadas, depende da sobrecarga utilizada. Assim, alterações no número de repetições podem afetar a PSE. O volume total de trabalho (VTT influencia nas adaptações crônicas ao treinamento e também pode ser afetado pela ordem dos exercícios. O objetivo foi verificar o efeito da ordem dos exercícios para membros inferiores no número de repetições realizadas, na PSE e no VTT. Doze homens treinados (19,3 ± 2,1 anos, 71,1 ± 9,8 kg, 172,4 ± 6,1 cm, 23,3 ± 11,5 meses/treino realizaram duas sessões com os exercícios "leg-press" (L, mesa flexora (F e cadeira extensora (E em diferentes ordens (LFE ou EFL. Foram utilizados testes t de "Student" pareados com ajuste de Bonferroni para comparações múltiplas. O número de repetições em L e E diminuiu quando realizados no final da sessão. As repetições realizadas em F diminuíram na LFE. A PSE de E foi maior quando realizada no final da sessão, porém de L e de F não foram afetadas pelas diferentes ordens. O volume de trabalho total de LFE foi maior. Em conclusão, a ordem dos exercícios envolvendo membros inferiores afeta o número de repetições e a PSE de um exercício além do VTT, ressaltando a importância da ordem dos exercícios como uma importante variável na prescrição do treinamento.The order of exercises refers to the sequence during a training bout. Some evidence shows that the number of repetitions may be affected by the order of exercises. Both the number of repetitions and the rate of perceived effort (PSE are influenced by exercise load. Thus, changes in the number of repetitions may affect PSE. Additionally, total work volume influences long term training adaptations and can be

  7. Comparing repetition-based melody segmentation models

    NARCIS (Netherlands)

    Rodríguez López, M.E.; de Haas, Bas; Volk, Anja

    2014-01-01

    This paper reports on a comparative study of computational melody segmentation models based on repetition detection. For the comparison we implemented five repetition-based segmentation models, and subsequently evaluated their capacity to automatically find melodic phrase boundaries in a corpus of 2

  8. Repetitions: A Cross-Cultural Study.

    Science.gov (United States)

    Murata, Kumiko

    1995-01-01

    This study investigated how repetition is used in conversation among native speakers of British English, native speakers of Japanese, and Japanese speakers of English. Five interactional functions of repetition (interruption-orientated, solidarity, silence-avoidance, hesitation, and reformulation) were identified, as well as the cultural factors…

  9. Digital repetitive control under varying frequency conditions

    CERN Document Server

    Ramos, Germán A; Olm, Josep M

    2013-01-01

    The tracking/rejection of periodic signals constitutes a wide field of research in the control theory and applications area. Repetitive Control has proven to be an efficient way to face this topic. However, in some applications the frequency of the reference/disturbance signal is time-varying or uncertain. This causes an important performance degradation in the standard Repetitive Control scheme. This book presents some solutions to apply Repetitive Control in varying frequency conditions without loosing steady-state performance. It also includes a complete theoretical development and experimental results in two representative systems. The presented solutions are organized in two complementary branches: varying sampling period Repetitive Control and High Order Repetitive Control. The first approach allows dealing with large range frequency variations while the second allows dealing with small range frequency variations. The book also presents applications of the described techniques to a Roto-magnet plant and...

  10. Ionization-injected electron acceleration with sub-terawatt laser pulses

    Science.gov (United States)

    Feder, Linus; Goers, Andy; Hine, George; Miao, Bo; Salehi, Fatholah; Woodbury, Daniel; Milchberg, Howard

    2016-10-01

    The vast majority of laser wakefield acceleration (LWFA) experiments use drive lasers with peak powers >10 TW and repetition rates from 10 Hz to less than once an hour. However, it was recently demonstrated that by using a thin, high density gas target, LWFA can be driven by laser pulses well below a TW and with high repetition rates. We present experiments and particle-in-cell (PIC) simulations of the effect of doping the high density gas jet with higher Z molecules (here nitrogen). Our earlier experiments with low-Z gas relied on self-injection of electrons into the accelerating wake through wave-breaking. In ionization injection, the relativistically self-focused laser pulse ionizes the inner shell of the dopant inside the plasma wake. High energy electrons are then trapped by the wakefield in the earliest potential buckets, which overlap with the laser pulse. PIC simulations show acceleration of these electrons by LWFA and directly by the laser pulse, with the direct contribution significantly increasing the electron energy beyond the LWFA contribution alone. Additionally, ionization injection can be controlled to prevent dephasing of the electron beam, resulting in a narrower energy spectrum and lower spatial divergence. This research is supported by the Department of Energy and the National Science Foundation.

  11. Optical beam dynamics in a gas repetitively heated by femtosecond filaments

    CERN Document Server

    Jhajj, N; Wahlstrand, J K; Milchberg, H M

    2013-01-01

    We investigate beam pointing dynamics in filamentation in gases driven by high repetition rate femtosecond laser pulses. Upon suddenly exposing a gas to a kilohertz train of filamenting pulses, the filament is steered from its original direction to a new stable direction whose equilibrium is determined by a balance among buoyant, viscous, and diffusive processes in the gas. Results are shown for Xe and air, but are broadly applicable to all configurations employing high repetition rate femtosecond laser propagation in gases.

  12. Fertilization after intracytoplasmic sperm injection with cryopreserved testicular spermatozoa.

    Science.gov (United States)

    Romero, J; Remohí, J; Mínguez, Y; Rubio, C; Pellicer, A; Gil-Salom, M

    1996-04-01

    To assess the possibility of cryopreserving testicular tissue extracted sperm for intracytoplasmic sperm injection (ICSI). A report of two cases. Our study was approved by the Ethical Committee at the Instituto Valenciano de Infertilidad. In vitro fertilization program at the Instituto Valenciano de Infertilidad. Two azoospermic patients with severe spermatogenic failure but with focal spermatogenesis on testicular biopsies. In both cases, a first ICSI attempt with fresh testicular biopsy extracted sperm was unsuccessful. Cryopreservation of testicular spermatozoa in 100-micro L "pills." Intracytoplasmic sperm injection with thawed testicular spermatozoa. Fertilization rate, cleavage rate, embryo quality, clinical pregnancy. Fertilization rates were 36 percent and 100 percent after ICSI with fresh testicular spermatozoa, and 63 percent and 57 percent after ICSI with cryopreserved testicular sperm. In both cases, cleavage rates and embryo quality were similar when using fresh and cryopreserved testicular spermatozoa. No clinical pregnancies were achieved. High fertilization rates can be obtained after ICSI with frozen-thawed testicular tissue extracted spermatozoa. Cryopreservation of testicular sperm may avoid repetition of testicular biopsies in azoospermic patients in whom the only source of spermatozoa is the testicle.

  13. Mepolizumab Injection

    Science.gov (United States)

    ... or do not go away: pain, redness, swelling, warmth, burning, or itching in the place mepolizumab was injected headache dry and itchy skin with or without red, scaly rashes back pain muscle spasms Some side ...

  14. Metoclopramide Injection

    Science.gov (United States)

    ... and feeling of fullness that lasts long after meals. Metoclopramide injection is also used to prevent nausea ... tranylcypromine (Parnate); narcotic medications for pain; sedatives; sleeping pills; tetracycline (Bristacycline, Sumycin); tranquilizers. Your doctor may need ...

  15. Ramucirumab Injection

    Science.gov (United States)

    ... dose of ramucirumab injection. Tell your doctor or nurse if you experience any of the following while you receive ramucirumab: uncontrollable shaking of a part of the body; back pain or spasms; chest pain and tightness; chills; flushing; ...

  16. Alemtuzumab Injection

    Science.gov (United States)

    Alemtuzumab injection is used to treat B-cell chronic lymphocytic leukemia (a slowly developing cancer in which ... of white blood cell accumulate in the body). Alemtuzumab is in a class of medications called monoclonal ...

  17. Ferumoxytol Injection

    Science.gov (United States)

    Ferumoxytol injection is used to treat iron-deficiency anemia (a lower than normal number of red blood ... pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or ...

  18. Fludarabine Injection

    Science.gov (United States)

    Fludarabine injection is used to treat chronic lymphocytic leukemia (CLL; a type of cancer of the white ... a reliable method of birth control to prevent pregnancy during this time. Talk to your doctor for ...

  19. Insulin Injection

    Science.gov (United States)

    ... or buttocks. Do not inject insulin into muscles, scars, or moles. Use a different site for each ... you are using insulin.Alcohol may cause a decrease in blood sugar. Ask your doctor about the ...

  20. Tigecycline Injection

    Science.gov (United States)

    ... in a person who was not in the hospital), skin infections, and infections of the abdomen (area between the ... that developed in people who were in a hospital or foot infections in people who have diabetes. Tigecycline injection is ...