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Sample records for previously studied laser

  1. On the Tengiz petroleum deposit previous study

    International Nuclear Information System (INIS)

    Nysangaliev, A.N.; Kuspangaliev, T.K.

    1997-01-01

    Tengiz petroleum deposit previous study is described. Some consideration about structure of productive formation, specific characteristic properties of petroleum-bearing collectors are presented. Recommendation on their detail study and using of experience on exploration and development of petroleum deposit which have analogy on most important geological and industrial parameters are given. (author)

  2. Laser in situ keratomileusis enhancements with the Ziemer FEMTO LDV femtosecond laser following previous LASIK treatments.

    Science.gov (United States)

    Pietilä, Juhani; Huhtala, Anne; Mäkinen, Petri; Uusitalo, Hannu

    2013-02-01

    The aim of this paper is to present the accuracy, predictability, and safety outcomes of LASIK enhancements performed with the FEMTO LDV femtosecond laser (Ziemer Ophthalmic Systems, Port, Switzerland) and the Allegretto Wave Concerto 500 Hz excimer laser (Wavelight AG, Erlangen, Germany), following previous LASIK treatments. FEMTO LDV was used for flap creation in 85 previously LASIK-treated eyes of 62 patients. The intended flap thickness was 90 μm in 81 eyes and 140 μm in 4 eyes. The size of the suction ring was 9.0 mm in 72 eyes and 9.5 mm in 13 eyes. Flap dimensions were measured and correlated to preoperative characteristics. With the intended flap thickness of 90 μm in previously LASIK-treated eyes, the actual flap thickness was 90.2 ± 6.6 μm (range 80-122), and the flap diameter was 9.2 ± 0.2 mm (range 8.7-9.9). The mean hinge length was 4.0 ± 0.2 mm (range 3.0-4.8). Flap thickness correlated positively with patient age and hinge length. Complications were reported in 12 eyes (14.1 %). Most of the complications were very mild, and none of them prevented further refractive laser treatment. One eye lost two Snellen lines of best spectacle-corrected visual acuity. Femtosecond LASIK enhancement is warranted only in rare cases. Surgical experience is needed and special caution must be practiced. For cases of a primary free cap, femtosecond LASIK is not recommended.

  3. Efficacy and safety of 10,600-nm carbon dioxide fractional laser on facial skin with previous volume injections

    Directory of Open Access Journals (Sweden)

    Josiane Hélou

    2013-01-01

    Full Text Available Background: Fractionated carbon dioxide (CO 2 lasers are a new treatment modality for skin resurfacing. The cosmetic rejuvenation market abounds with various injectable devices (poly-L-lactic acid, polymethyl-methacrylate, collagens, hyaluronic acids, silicone. The objective of this study is to examine the efficacy and safety of 10,600-nm CO 2 fractional laser on facial skin with previous volume injections. Materials and Methods: This is a retrospective study including 14 patients treated with fractional CO 2 laser and who have had previous facial volume restoration. The indication for the laser therapy, the age of the patients, previous facial volume restoration, and side effects were all recorded from their medical files. Objective assessments were made through clinical physician global assessment records and improvement scores records. Patients′ satisfaction rates were also recorded. Results: Review of medical records of the 14 patients show that five patients had polylactic acid injection prior to the laser session. Eight patients had hyaluronic acid injection prior to the laser session. Two patients had fat injection, two had silicone injection and one patient had facial thread lift. Side effects included pain during the laser treatment, post-treatment scaling, post-treatment erythema, hyperpigmentation which spontaneously resolved within a month. Concerning the previous facial volume restoration, no granulomatous reactions were noted, no facial shape deformation and no asymmetry were encountered whatever the facial volume product was. Conclusion: CO 2 fractional laser treatments do not seem to affect facial skin which had previous facial volume restoration with polylactic acid for more than 6 years, hyaluronic acid for more than 0.5 year, silicone for more than 6 years, or fat for more than 1.4 year. Prospective larger studies focusing on many other variables (skin phototype, injected device type are required to achieve better

  4. Personality disorders in previously detained adolescent females: a prospective study

    NARCIS (Netherlands)

    Krabbendam, A.; Colins, O.F.; Doreleijers, T.A.H.; van der Molen, E.; Beekman, A.T.F.; Vermeiren, R.R.J.M.

    2015-01-01

    This longitudinal study investigated the predictive value of trauma and mental health problems for the development of antisocial personality disorder (ASPD) and borderline personality disorder (BPD) in previously detained women. The participants were 229 detained adolescent females who were assessed

  5. Radon anomalies prior to earthquakes (1). Review of previous studies

    International Nuclear Information System (INIS)

    Ishikawa, Tetsuo; Tokonami, Shinji; Yasuoka, Yumi; Shinogi, Masaki; Nagahama, Hiroyuki; Omori, Yasutaka; Kawada, Yusuke

    2008-01-01

    The relationship between radon anomalies and earthquakes has been studied for more than 30 years. However, most of the studies dealt with radon in soil gas or in groundwater. Before the 1995 Hyogoken-Nanbu earthquake, an anomalous increase of atmospheric radon was observed at Kobe Pharmaceutical University. The increase was well fitted with a mathematical model related to earthquake fault dynamics. This paper reports the significance of this observation, reviewing previous studies on radon anomaly before earthquakes. Groundwater/soil radon measurements for earthquake prediction began in 1970's in Japan as well as foreign countries. One of the most famous studies in Japan is groundwater radon anomaly before the 1978 Izu-Oshima-kinkai earthquake. We have recognized the significance of radon in earthquake prediction research, but recently its limitation was also pointed out. Some researchers are looking for a better indicator for precursors; simultaneous measurements of radon and other gases are new trials in recent studies. Contrary to soil/groundwater radon, we have not paid much attention to atmospheric radon before earthquakes. However, it might be possible to detect precursors in atmospheric radon before a large earthquake. In the next issues, we will discuss the details of the anomalous atmospheric radon data observed before the Hyogoken-Nanbu earthquake. (author)

  6. Simulation of the Effect of Different Presbyopia-Correcting Intraocular Lenses With Eyes With Previous Laser Refractive Surgery.

    Science.gov (United States)

    Camps, Vicente J; Miret, Juan J; García, Celia; Tolosa, Angel; Piñero, David P

    2018-04-01

    To simulate the optical performance of three presbyopia-correcting intraocular lenses (IOLs) implanted in eyes with previous laser refractive surgery. A simulation of the through-focus modulation transfer function (MTF) was performed for three presbyopia-correcting IOLs (Mplus, Oculentis GmbH, Berlin, Germany; Symfony, Johnson & Johnson Vision, Santa Ana, CA; and Mini Well, SIFI S.p.A., Lavinaio, Italy) in one eye with previous myopic LASIK and another with hyperopic LASIK. Real topographic data and the wavefront aberration profile of each IOL obtained with a Hartmann-Shack sensor were used. In the eye with myopic LASIK, all IOLs lost optical quality at near and intermediate distances for 4- and 4.7-mm pupil size. For 3-mm pupil size, the Mini Well IOL showed the best intermediate and near MTF and maintained the far focus independently of the pupil. In the eye with hyperopic LASIK, the Mini Well IOL showed an intermediate, distance, and -4.00-diopter (D) foci for all pupils. The Symfony IOL showed a depth of focus at far and intermediate distance for 3-mm and a focus at -2.50 D in the rest. The Mplus showed a focus of -4.50 and -3.00 D for the 3- and 4-mm pupil, respectively. The Mini Well and Symfony IOLs seem to work better than the Mplus IOL in eyes with previous myopic LASIK. With previous hyperopic LASIK, the Mini Well IOL seems to be able to provide acceptable near, intermediate, and far foci for all pupil sizes. These findings should be confirmed in future clinical studies. [J Refract Surg. 2018;34(4):222-227.]. Copyright 2018, SLACK Incorporated.

  7. Treatment of Previously Treated Facial Capillary Malformations: Results of Single-Center Retrospective Objective 3-Dimensional Analysis of the Efficacy of Large Spot 532 nm Lasers.

    Science.gov (United States)

    Kwiek, Bartłomiej; Ambroziak, Marcin; Osipowicz, Katarzyna; Kowalewski, Cezary; Rożalski, Michał

    2018-06-01

    Current treatment of facial capillary malformations (CM) has limited efficacy. To assess the efficacy of large spot 532 nm lasers for the treatment of previously treated facial CM with the use of 3-dimensional (3D) image analysis. Forty-three white patients aged 6 to 59 were included in this study. Patients had 3D photography performed before and after treatment with a 532 nm Nd:YAG laser with large spot and contact cooling. Objective analysis of percentage improvement based on 3D digital assessment of combined color and area improvement (global clearance effect [GCE]) were performed. The median maximal improvement achieved during the treatment (GCE) was 59.1%. The mean number of laser procedures required to achieve this improvement was 6.2 (range 1-16). Improvement of minimum 25% (GCE25) was achieved by 88.4% of patients, a minimum of 50% (GCE50) by 61.1%, a minimum of 75% (GCE75) by 25.6%, and a minimum of 90% (GCE90) by 4.6%. Patients previously treated with pulsed dye lasers had a significantly less response than those treated with other modalities (GCE 37.3% vs 61.8%, respectively). A large spot 532 nm laser is effective in previously treated patients with facial CM.

  8. Study on laser atomic spectroscopy

    International Nuclear Information System (INIS)

    Lee, Jong Min; Song, Kyu Seok; Jeong, Do Young; Kim, Chul Joong; Han, Phil Soon

    1992-01-01

    Electric discharge type atomic vaporizer is developed for the spectroscopic study on actinide elements. Laser induced fluorescence study on actinide elements is performed by using this high temperature type atomizer. For the effective photoionization of elements, copper vapor laser pumped dye laser and electron beam heating type atomic vaporizer are built and their characteristics are measured. In addition, resonance ionization mass spectroscopic analysis for lead sample as well as laser induced fluorescence study on uranium sample in solution phase is made. (Author)

  9. Laser-driven hydrothermal process studied with excimer laser pulses

    Science.gov (United States)

    Mariella, Raymond; Rubenchik, Alexander; Fong, Erika; Norton, Mary; Hollingsworth, William; Clarkson, James; Johnsen, Howard; Osborn, David L.

    2017-08-01

    Previously, we discovered [Mariella et al., J. Appl. Phys. 114, 014904 (2013)] that modest-fluence/modest-intensity 351-nm laser pulses, with insufficient fluence/intensity to ablate rock, mineral, or concrete samples via surface vaporization, still removed the surface material from water-submerged target samples with confinement of the removed material, and then dispersed at least some of the removed material into the water as a long-lived suspension of nanoparticles. We called this new process, which appears to include the generation of larger colorless particles, "laser-driven hydrothermal processing" (LDHP) [Mariella et al., J. Appl. Phys. 114, 014904 (2013)]. We, now, report that we have studied this process using 248-nm and 193-nm laser light on submerged concrete, quartzite, and obsidian, and, even though light at these wavelengths is more strongly absorbed than at 351 nm, we found that the overall efficiency of LDHP, in terms of the mass of the target removed per Joule of laser-pulse energy, is lower with 248-nm and 193-nm laser pulses than with 351-nm laser pulses. Given that stronger absorption creates higher peak surface temperatures for comparable laser fluence and intensity, it was surprising to observe reduced efficiencies for material removal. We also measured the nascent particle-size distributions that LDHP creates in the submerging water and found that they do not display the long tail towards larger particle sizes that we had observed when there had been a multi-week delay between experiments and the date of measuring the size distributions. This is consistent with transient dissolution of the solid surface, followed by diffusion-limited kinetics of nucleation and growth of particles from the resulting thin layer of supersaturated solution at the sample surface.

  10. QED studies using high-power lasers

    International Nuclear Information System (INIS)

    Mattias Marklund

    2010-01-01

    Complete text of publication follows. The event of extreme lasers, which intensities above 10 22 W/cm 2 will be reached on a routine basis, will give us opportunities to probe new aspects of quantum electrodynamics. In particular, the non-trivial properties of the quantum vacuum can be investigated as we reach previously unattainable laser intensities. Effects such as vacuum birefringence and pair production in strong fields could thus be probed. The prospects of obtaining new insights regarding the non-perturbative structure of quantum field theories shows that the next generation laser facilities can be important tool for fundamental physical studies. Here we aim at giving a brief overview of such aspects of high-power laser physics.

  11. Study on Laser Welding Process Monitoring Method

    OpenAIRE

    Knag , Heeshin

    2017-01-01

    International audience; In this paper, a study of quality monitoring technology for the laser welding was conducted. The laser welding and the industrial robotic systems were used with robot-based laser welding systems. The laser system used in this study was 1.6 kW fiber laser, while the robot system was Industrial robot (pay-load : 130 kg). The robot-based laser welding system was equipped with a laser scanner system for remote laser welding. The welding joints of steel plate and steel plat...

  12. Study on Laser Welding Process Monitoring Method

    OpenAIRE

    Heeshin Knag

    2016-01-01

    In this paper, a study of quality monitoring technology for the laser welding was conducted. The laser welding and the industrial robotic systems were used with robot-based laser welding systems. The laser system used in this study was 1.6 kW fiber laser, while the robot system was Industrial robot (pay-load : 130 kg). The robot-based laser welding system was equipped with a laser scanner system for remote laser welding. The welding joints of steel plate and steel plate coated with zinc were ...

  13. Parametric study of laser photovoltaic energy converters

    Science.gov (United States)

    Walker, G. H.; Heinbockel, J. H.

    1987-01-01

    Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.

  14. 40 CFR 152.93 - Citation of a previously submitted valid study.

    Science.gov (United States)

    2010-07-01

    ... Data Submitters' Rights § 152.93 Citation of a previously submitted valid study. An applicant may demonstrate compliance for a data requirement by citing a valid study previously submitted to the Agency. The... the original data submitter, the applicant may cite the study only in accordance with paragraphs (b...

  15. Study on guided waves in semiconductor lasers

    International Nuclear Information System (INIS)

    Pudensi, M.A.A.

    1980-01-01

    In This work we studied the guided waves in semiconductor lasers. In the first part we carried on the experimental measurements on lasers with stripe nonorthogonal to the mirrors. In the second part we developed a matrix method for the study of propagation and reflection of guided waves in lasers. (author) [pt

  16. Biomedical Studies with the Free Electron Laser

    Science.gov (United States)

    1989-05-15

    and Berns. Mi. W. User pitotora- 26. Kestel. D.. And Chou. T. C. Tumer -localizing components of the ptirph% rin diation therapy of cancer following... cancer , (2) laser tissue interactions for the study of atherosclerosis, (3) pulsed laser effects on the eye, (4) laser application in genetic...these studies. Please refer to the appropriate article/abstract for further detail. 1. Dye plus laser photosensitization of cancer . Significant

  17. Summary of Previous Chamber or Controlled Anthrax Studies and Recommendations for Possible Additional Studies

    Energy Technology Data Exchange (ETDEWEB)

    Piepel, Gregory F.; Amidan, Brett G.; Morrow, Jayne B.

    2010-12-29

    This report and an associated Excel file(a) summarizes the investigations and results of previous chamber and controlled studies(b) to characterize the performance of methods for collecting, storing and/or transporting, extracting, and analyzing samples from surfaces contaminated by Bacillus anthracis (BA) or related simulants. This report and the Excel are the joint work of the Pacific Northwest National Laboratory (PNNL) and the National Institute of Standards and Technology (NIST) for the Department of Homeland Security, Science and Technology Directorate. The report was originally released as PNNL-SA-69338, Rev. 0 in November 2009 with limited distribution, but was subsequently cleared for release with unlimited distribution in this Rev. 1. Only minor changes were made to Rev. 0 to yield Rev. 1. A more substantial update (including summarizing data from other studies and more condensed summary tables of data) is underway

  18. Scaling studies of solar pumped lasers

    Science.gov (United States)

    Christiansen, W. H.; Chang, J.

    1985-01-01

    A progress report of scaling studies of solar pumped lasers is presented. Conversion of blackbody radiation into laser light has been demonstrated in this study. Parametric studies of the variation of laser mixture composition and laser gas temperature were carried out for CO2 and N2O gases. Theoretical analysis and modeling of the system have been performed. Reasonable agreement between predictions in the parameter variation and the experimental results have been obtained. Almost 200 mW of laser output at 10.6 micron was achieved by placing a small sapphire laser tube inside an oven at 1500 K the tube was filled with CO2 laser gas mixture and cooled by longitudinal nitrogen gas flow.

  19. Studying antimatter with laser precision

    CERN Multimedia

    Katarina Anthony

    2012-01-01

    The next generation of antihydrogen trapping devices, ALPHA-2, is moving into CERN’s Antiproton Decelerator (AD) hall. This brand-new experiment will allow the ALPHA collaboration to conduct studies of antimatter with greater precision. ALPHA spokesperson Jeffrey Hangst was recently awarded a grant by the Carlsberg Foundation, which will be used to purchase equipment for the new experiment.   A 3-D view of the new magnet (in blue) and cryostat. The red lines show the paths of laser beams. LHC-type current leads for the superconducting magnets are visible on the top-right of the image. The ALPHA collaboration has been working to trap and study antihydrogen since 2006. Using antiprotons provided by CERN’s Antiproton Decelerator (AD), ALPHA was the first experiment to trap antihydrogen and to hold it long enough to study its properties. “The new ALPHA-2 experiment will use integrated lasers to probe the trapped antihydrogen,” explains Jeffrey Hangst, ALP...

  20. Matched cohort study of external cephalic version in women with previous cesarean delivery.

    Science.gov (United States)

    Keepanasseril, Anish; Anand, Keerthana; Soundara Raghavan, Subrahmanian

    2017-07-01

    To evaluate the efficacy and safety of external cephalic version (ECV) among women with previous cesarean delivery. A retrospective study was conducted using data for women with previous cesarean delivery and breech presentation who underwent ECV at or after 36 weeks of pregnancy during 2011-2016. For every case, two multiparous women without previous cesarean delivery who underwent ECV and were matched for age and pregnancy duration were included. Characteristics and outcomes were compared between groups. ECV was successful for 32 (84.2%) of 38 women with previous cesarean delivery and 62 (81.6%) in the control group (P=0.728). Multivariate regression analysis confirmed that previous cesarean was not associated with ECV success (odds ratio 1.89, 95% confidence interval 0.19-18.47; P=0.244). Successful vaginal delivery after successful ECV was reported for 19 (59.4%) women in the previous cesarean delivery group and 52 (83.9%) in the control group (P<0.001). No ECV-associated complications occurred in women with previous cesarean delivery. To avoid a repeat cesarean delivery, ECV can be offered to women with breech presentation and previous cesarean delivery who are otherwise eligible for a trial of labor. © 2017 International Federation of Gynecology and Obstetrics.

  1. Theoretical studies of solar pumped lasers

    Science.gov (United States)

    Harries, Wynford L.

    1990-01-01

    One concept for collecting solar energy is to use large solar collectors and then use lasers as energy converters whose output beams act as transmission lines to deliver the energy to a destination. The efficiency of the process would be improved if the conversion could be done directly using solar pumped lasers, and the possibility of making such lasers is studied. There are many applications for such lasers, and these are examined. By including the applications first, the requirements for the lasers will be more evident. They are especially applicable to the Space program, and include cases where no other methods of delivering power seem possible. Using the lasers for conveying information and surveillance is also discussed. Many difficulties confront the designer of an efficient system for power conversion. These involve the nature of the solar spectrum, the method of absorbing the energy, the transfer of power into laser beams, and finally, the far field patterns of the beams. The requirements of the lasers are discussed. Specific laser configurations are discussed. The thrust is into gas laser systems, because for space applications, the laser could be large, and also the medium would be uniform and not subject to thermal stresses. Dye and solid lasers are treated briefly. For gas lasers, a chart of the various possibilities is shown, and the various families of gas lasers divided according to the mechanisms of absorbing solar radiation and of lasing. Several specific models are analyzed and evaluated. Overall conclusions for the program are summarized, and the performances of the lasers related to the requirements of various applications.

  2. Design study of laser fusion rocket

    International Nuclear Information System (INIS)

    Nakashima, Hideki; Shoyama, Hidetoshi; Kanda, Yukinori

    1991-01-01

    A design study was made on a rocket powered by laser fusion. Dependence of its flight performance on target gain, driver repetition rate and fuel composition was analyzed to obtain optimal design parameters of the laser fusion rocket. The results indicate that the laser fusion rocket fueled with DT or D 3 He has the potential advantages over other propulsion systems such as fission rocket for interplanetary travel. (author)

  3. Study of some physical aspects previous to design of an exponential experiment

    International Nuclear Information System (INIS)

    Caro, R.; Francisco, J. L. de

    1961-01-01

    This report presents the theoretical study of some physical aspects previous to the design of an exponential facility. The are: Fast and slow flux distribution in the multiplicative medium and in the thermal column, slowing down in the thermal column, geometrical distribution and minimum needed intensity of sources access channels and perturbations produced by possible variations in its position and intensity. (Author) 4 refs

  4. Study of functional-performance deficits in athletes with previous ankle sprains

    Directory of Open Access Journals (Sweden)

    hamid Babaee

    2008-04-01

    Full Text Available Abstract Background: Despite the importance of functional-performance deficits in athletes with history of ankle sprain few, studies have been carried out in this area. The aim of this research was to study relationship between previous ankle sprains and functional-performance deficits in athletes. Materials and methods: The subjects were 40 professional athletes selected through random sampling among volunteer participants in soccer, basketball, volleyball and handball teams of Lorestan province. The subjects were divided into 2 groups: Injured group (athletes with previous ankle sprains and healthy group (athletes without previous ankle sprains. In this descriptive study we used Functional-performance tests (figure 8 hop test and side hop test to determine ankle deficits and limitations. They participated in figure 8 hop test including hopping in 8 shape course with the length of 5 meters and side hop test including 10 side hop repetitions in course with the length of 30 centimeters. Time were recorded via stopwatch. Results: After data gathering and assessing information distributions, Pearson correlation was used to assess relationships, and independent T test to assess differences between variables. Finally the results showed that there is a significant relationship between previous ankle sprains and functional-performance deficits in the athletes. Conclusion: The athletes who had previous ankle sprains indicated functional-performance deficits more than healthy athletes in completion of mentioned functional-performance tests. The functional-performance tests (figure 8 hop test and side hop test are sensitive and suitable to assess and detect functional-performance deficits in athletes. Therefore we can use the figure 8 hop and side hop tests for goals such as prevention, assessment and rehabilitation of ankle sprains without spending too much money and time.

  5. LPI studies with grazing incidence irradiation at the Nike laser

    Science.gov (United States)

    Weaver, J.; Kehne, D.; Schmitt, A.; Obenschain, S.; Serlin, V.; Oh, J.; Lehmberg, R.; Seely, J.

    2013-10-01

    Studies of laser plasma instabilities (LPI) at the Nike laser facility at NRL have previously concentrated on planar targets irradiated with their surface normal aligned to the central axis of the laser. Shots with planar targets rotated up 60° to the laser have shown changes in thresholds for the two-plasmon decay instability and stimulated Raman scattering near the quarter critical region. In the case of rotated low-Z targets, spectra were observed to shift to lower wavelength and were substantially stronger in the visible and ultraviolet spectral ranges. The low-Z target data show growth at an incident intensity slightly below (~30%) the threshold values observed at normal incidence. A rapid rise in signal level over the same laser intensities was also observed in the hard x-ray data which serve as an overall indicator of LPI activity. Shots with rotated planar high-Z targets showed that the visible and ultraviolet emissions dropped significantly when compared to low-Z targets in the same geometry. This presentation will include results from upcoming experiments to determine the LPI signal for low-Z, high-Z, and high-Z coated targets at lower laser intensities for several angles of target rotation. Shots with widely separated laser beams are also planned to explore cross beam energy transport at Nike. Work supported by DoE/NNSA.

  6. Data from studies of previous radioactive waste disposal in Massachusetts Bay

    International Nuclear Information System (INIS)

    Curtis, W.R.; Mardis, H.M.

    1984-12-01

    This report presents the results of studies conducted in Massachusetts Bay during 1981 and 1982. Included are data from: (1) a side scan sonar survey of disposal areas in the Bay that was carried out by the National Oceanic and Atmospheric Administration (NOAA) for EPA; (2) Collections of sediment and biota by NOAA for radiochemical analysis by EPA; (3) collections of marketplace seafood samples by the Food and Drug Administration (FDA) for radioanalysis by both FDA and EPA; and (4) a radiological monitoring survey of LLW disposal areas by EPA to determine whether there should be any concern for public health resulting from previous LLW disposals in the Bay

  7. Laser isotope separation studies in JAERI

    International Nuclear Information System (INIS)

    Arisawa, Takashi; Shiba, Koreyuki

    1986-01-01

    For uranium enrichment, Japan Atomic Energy Research Institute (JAERI) has been studying atomic vapor laser isotope separation since 1976, in addition to such separation methods as gas diffusion, chemical exchange and gas-dynamic techniques. Studies carried out to date in JAERI is briefly summarized in the first part of the report. Then, some major separation techniques which have been studied in JAERI are outlined, and typical results obtained are presented. A large part is devoted to the multiple-photon photoionization technique, which is commonly known as the atomic laser isotope separation method for uranium enrichment. It has such advantages as 1) very high spectral selectivity for the relevant isotope and 2) highly improved photoionizing effect by means of two- and three-step resonance photoionization processes. Here, the atomic laser isotope separation method is discussed in detail with respect to the evaporation process, energy levels, photoionization, selectivity, photoionization schemes, ion recovery, separation in macroscopic amounts, and separation of trace amounts of isotopes. Typical observed and claculated results related to these subjects are shown. In addition, the report briefly describes some other separation processes including laser induced chemical reaction, multiple photo-dissociation, multiple-photo excitation and UV dissociation, laser induced thermal diffusion, and laser centrifugation. (Nogami, K.)

  8. A longitudinal study of plasma insulin and glucagon in women with previous gestational diabetes

    DEFF Research Database (Denmark)

    Damm, P; Kühl, C; Hornnes, P

    1995-01-01

    OBJECTIVE: To investigate whether plasma insulin or glucagon predicts later development of diabetes in women with gestational diabetes mellitus (GDM). RESEARCH DESIGN AND METHODS: The subjects studied were 91 women with diet-treated GDM and 33 healthy women. Plasma insulin and glucagon during a 50...... at follow-up (2 had insulin-dependent diabetes mellitus, 13 had non-insulin-dependent diabetes mellitus, and 12 had impaired glucose tolerance). Compared with the control subjects, women with previous GDM had relatively impaired insulin secretion (decreased insulinogenic index and delayed peak insulin...... for subsequent development of overt diabetes (logistic regression analysis). CONCLUSIONS: Women who develop GDM have a relative insulin secretion deficiency, the severity of which is predictive for later development of diabetes. Furthermore, our data indicate that their relatively reduced beta-cell function may...

  9. Case-control study for colorectal cancer genetic susceptibility in EPICOLON: previously identified variants and mucins

    Directory of Open Access Journals (Sweden)

    Moreno Victor

    2011-08-01

    Full Text Available Abstract Background Colorectal cancer (CRC is the second leading cause of cancer death in developed countries. Familial aggregation in CRC is also important outside syndromic forms and, in this case, a polygenic model with several common low-penetrance alleles contributing to CRC genetic predisposition could be hypothesized. Mucins and GALNTs (N-acetylgalactosaminyltransferase are interesting candidates for CRC genetic susceptibility and have not been previously evaluated. We present results for ten genetic variants linked to CRC risk in previous studies (previously identified category and 18 selected variants from the mucin gene family in a case-control association study from the Spanish EPICOLON consortium. Methods CRC cases and matched controls were from EPICOLON, a prospective, multicenter, nationwide Spanish initiative, comprised of two independent stages. Stage 1 corresponded to 515 CRC cases and 515 controls, whereas stage 2 consisted of 901 CRC cases and 909 controls. Also, an independent cohort of 549 CRC cases and 599 controls outside EPICOLON was available for additional replication. Genotyping was performed for ten previously identified SNPs in ADH1C, APC, CCDN1, IL6, IL8, IRS1, MTHFR, PPARG, VDR and ARL11, and 18 selected variants in the mucin gene family. Results None of the 28 SNPs analyzed in our study was found to be associated with CRC risk. Although four SNPs were significant with a P-value ADH1C (OR = 1.63, 95% CI = 1.06-2.50, P-value = 0.02, recessive, rs1800795 in IL6 (OR = 1.62, 95% CI = 1.10-2.37, P-value = 0.01, recessive, rs3803185 in ARL11 (OR = 1.58, 95% CI = 1.17-2.15, P-value = 0.007, codominant, and rs2102302 in GALNTL2 (OR = 1.20, 95% CI = 1.00-1.44, P-value = 0.04, log-additive 0, 1, 2 alleles], only rs3803185 achieved statistical significance in EPICOLON stage 2 (OR = 1.34, 95% CI = 1.06-1.69, P-value = 0.01, recessive. In the joint analysis for both stages, results were only significant for rs3803185 (OR = 1

  10. Case-control study for colorectal cancer genetic susceptibility in EPICOLON: previously identified variants and mucins

    International Nuclear Information System (INIS)

    Abulí, Anna; Morillas, Juan D; Rigau, Joaquim; Latorre, Mercedes; Fernández-Bañares, Fernando; Peña, Elena; Riestra, Sabino; Payá, Artemio; Jover, Rodrigo; Xicola, Rosa M; Llor, Xavier; Fernández-Rozadilla, Ceres; Carvajal-Carmona, Luis; Villanueva, Cristina M; Moreno, Victor; Piqué, Josep M; Carracedo, Angel; Castells, Antoni; Andreu, Montserrat; Ruiz-Ponte, Clara; Castellví-Bel, Sergi; Alonso-Espinaco, Virginia; Muñoz, Jenifer; Gonzalo, Victoria; Bessa, Xavier; González, Dolors; Clofent, Joan; Cubiella, Joaquin

    2011-01-01

    Colorectal cancer (CRC) is the second leading cause of cancer death in developed countries. Familial aggregation in CRC is also important outside syndromic forms and, in this case, a polygenic model with several common low-penetrance alleles contributing to CRC genetic predisposition could be hypothesized. Mucins and GALNTs (N-acetylgalactosaminyltransferase) are interesting candidates for CRC genetic susceptibility and have not been previously evaluated. We present results for ten genetic variants linked to CRC risk in previous studies (previously identified category) and 18 selected variants from the mucin gene family in a case-control association study from the Spanish EPICOLON consortium. CRC cases and matched controls were from EPICOLON, a prospective, multicenter, nationwide Spanish initiative, comprised of two independent stages. Stage 1 corresponded to 515 CRC cases and 515 controls, whereas stage 2 consisted of 901 CRC cases and 909 controls. Also, an independent cohort of 549 CRC cases and 599 controls outside EPICOLON was available for additional replication. Genotyping was performed for ten previously identified SNPs in ADH1C, APC, CCDN1, IL6, IL8, IRS1, MTHFR, PPARG, VDR and ARL11, and 18 selected variants in the mucin gene family. None of the 28 SNPs analyzed in our study was found to be associated with CRC risk. Although four SNPs were significant with a P-value < 0.05 in EPICOLON stage 1 [rs698 in ADH1C (OR = 1.63, 95% CI = 1.06-2.50, P-value = 0.02, recessive), rs1800795 in IL6 (OR = 1.62, 95% CI = 1.10-2.37, P-value = 0.01, recessive), rs3803185 in ARL11 (OR = 1.58, 95% CI = 1.17-2.15, P-value = 0.007, codominant), and rs2102302 in GALNTL2 (OR = 1.20, 95% CI = 1.00-1.44, P-value = 0.04, log-additive 0, 1, 2 alleles], only rs3803185 achieved statistical significance in EPICOLON stage 2 (OR = 1.34, 95% CI = 1.06-1.69, P-value = 0.01, recessive). In the joint analysis for both stages, results were only significant for rs3803185 (OR = 1.12, 95% CI = 1

  11. Parametric study on femtosecond laser pulse ablation of Au films

    International Nuclear Information System (INIS)

    Ni Xiaochang; Wang Chingyue; Yang Li; Li Jianping; Chai Lu; Jia Wei; Zhang Ruobing; Zhang Zhigang

    2006-01-01

    Ablation process of 1 kHz rate femtosecond lasers (pulse duration 148 fs, wavelength 775 nm) with Au films on silica substrates has been systemically studied. The single-pulse threshold can be obtained directly. For the multiple pulses the ablation threshold varies with the number of pulses applied to the surface due to the incubation effect. From the plot of accumulated laser fluence N x φ th (N) and the number of laser pulses N, incubation coefficient of Au film can be obtained (s = 0.765). As the pulse energy is increased, the single pulse ablation rate is increasing following two ablation logarithmic regimes, which can be explained by previous research

  12. A study about the interest and previous contact of high school students with Astronomy

    Science.gov (United States)

    Carvalho, C. L.; Zanitti, M. H. R.; Felicidade, B. L.; Gomes, A. D. T.; Dias, E. W.; Coelho, F. O.

    2016-04-01

    The currently problems in Astronomy teaching in Brazilian Basic Education contrast with the space, and the popularity that astronomical themes have in various media in the country. In this work, we present the results of a study about the interest, and previous contact of high school students from a public school in the city of "São João del-Rei"/MG with topics related to Astronomy. The study and the pedagogical intervention were carried out by students of the PIBID/CAPES/UFSJ. The intervention was performed through an oral exposition with the students' participation, followed by the use of the Stellarium program. The results suggest the majority of students surveyed are interested in Astronomy, and have had some contact with the area. However, some inconsistencies in their responses were identified and examined. The implications for research and for Astronomy Education are discussed. We also make some considerations about relationship between the lack of specific knowledge and the misinformation as one possible reason for the little interest of students in various areas of Science.

  13. Fire Risk Scoping Study: Investigation of nuclear power plant fire risk, including previously unaddressed issues

    International Nuclear Information System (INIS)

    Lambright, J.A.; Nowlen, S.P.; Nicolette, V.F.; Bohn, M.P.

    1989-01-01

    An investigation of nuclear power plant fire risk issues raised as a result of the USNRC sponsored Fire Protection Research Program at Sandia National Laboratories has been performed. The specific objectives of this study were (1) to review and requantify fire risk scenarios from four fire probabilistic risk assessments (PRAs) in light of updated data bases made available as a result of USNRC sponsored Fire Protection Research Program and updated computer fire modeling capabilities, (2) to identify potentially significant fire risk issues that have not been previously addressed in a fire risk context and to quantify the potential impact of those identified fire risk issues where possible, and (3) to review current fire regulations and plant implementation practices for relevance to the identified unaddressed fire risk issues. In performance of the fire risk scenario requantifications several important insights were gained. It was found that utilization of a more extensive operational experience base resulted in both fire occurrence frequencies and fire duration times (i.e., time required for fire suppression) increasing significantly over those assumed in the original works. Additionally, some thermal damage threshold limits assumed in the original works were identified as being nonconservative based on more recent experimental data. Finally, application of the COMPBRN III fire growth model resulted in calculation of considerably longer fire damage times than those calculated in the original works using COMPBRN I. 14 refs., 2 figs., 16 tabs

  14. Theoretical studies of solar-pumped lasers

    Science.gov (United States)

    Harries, W. L.

    1983-01-01

    Possible types of lasers were surveyed for solar power conversion. The types considered were (1) liquid dye lasers, (2) vapor dye lasers, and (3) nondissociative molecular lasers. These are discussed.

  15. Dynamical study of a laser with a saturable absorber

    Energy Technology Data Exchange (ETDEWEB)

    Dignowity, D; RamIrez, R [Centro de Investigaciones en Optica, Loma del Bosque 115, Col. Lomas del Campestre, 37150, Leon, Guanajuato (Mexico)

    2005-01-01

    The study of a laser including a saturable absorber is presented. The non-linear system describing the complex dynamics of the laser is presented. The laser is shown to operate in several regimes depending on the parameters used. It is also shown how the control of the laser is possible depending on the operating regime parameters.

  16. Studies on CO2-laser Hybrid-Welding of Copper

    DEFF Research Database (Denmark)

    Nielsen, Jakob Skov; Olsen, Flemming Ove; Bagger, Claus

    2005-01-01

    CO2-laser welding of copper is known to be difficult due to the high heat conductivity of the material and the high reflectivity of copper at the wavelength of the CO2-laser light. THis paper presents a study of laser welding of copper, applying laser hybrid welding. Welding was performed as a hy...

  17. The biomechanics of running in athletes with previous hamstring injury: A case-control study.

    Science.gov (United States)

    Daly, C; Persson, U McCarthy; Twycross-Lewis, R; Woledge, R C; Morrissey, D

    2016-04-01

    Hamstring injury is prevalent with persistently high reinjury rates. We aim to inform hamstring rehabilitation by exploring the electromyographic and kinematic characteristics of running in athletes with previous hamstring injury. Nine elite male Gaelic games athletes who had returned to sport after hamstring injury and eight closely matched controls sprinted while lower limb kinematics and muscle activity of the previously injured biceps femoris, bilateral gluteus maximus, lumbar erector spinae, rectus femoris, and external oblique were recorded. Intergroup comparisons of muscle activation ratios and kinematics were performed. Previously injured athletes demonstrated significantly reduced biceps femoris muscle activation ratios with respect to ipsilateral gluteus maximus (maximum difference -12.5%, P = 0.03), ipsilateral erector spinae (maximum difference -12.5%, P = 0.01), ipsilateral external oblique (maximum difference -23%, P = 0.01), and contralateral rectus femoris (maximum difference -22%, P = 0.02) in the late swing phase. We also detected sagittal asymmetry in hip flexion (maximum 8°, P = 0.01), pelvic tilt (maximum 4°, P = 0.02), and medial rotation of the knee (maximum 6°, P = 0.03) effectively putting the hamstrings in a lengthened position just before heel strike. Previous hamstring injury is associated with altered biceps femoris associated muscle activity and potentially injurious kinematics. These deficits should be considered and addressed during rehabilitation. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. Molecular dynamics study of lubricant depletion by pulsed laser heating

    Science.gov (United States)

    Seo, Young Woo; Rosenkranz, Andreas; Talke, Frank E.

    2018-05-01

    In this study, molecular dynamics simulations were performed to numerically investigate the effect of pulsed laser heating on lubricant depletion. The maximum temperature, the lubricant depletion width, the number of evaporated lubricant beads and the number of fragmented lubricant chains were studied as a function of laser peak power, pulse duration and repetition rate. A continuous-wave laser and a square pulse laser were simulated and compared to a Gaussian pulse laser. With increasing repetition rate, pulsed laser heating was found to approach continuous-wave laser heating.

  19. Studies on corrosion protection of laser hybrid welded AISI 316 by laser remelting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Ambat, Rajan; Rasmussen, A.J.

    2005-01-01

    laser surface melting on microstructure and corrosion behaviour of AISI 316L welds. Welding and laser treatment parameters were varied. General corrosion behaviour of the weld and laser treated surface was characterised using a gel visualization test. The local electrochemistry of the weld and laser......Unlike in autogenous laser welding, hybrid laser welding of stainless steel could introduce grain boundary carbides due to low cooling rates. Formation of grain boundary carbides leads to reduced corrosion properties. Studies have initially been carried out on hybrid laser welding and subsequent...... treated surface was investigated using a novel micro electrochemical technique with a tip resolution of ~1 mm. Results show that hybrid laser welding of 316L has increased corrosion susceptibility probably as a result of grain boundary carbide formation. However a suitable post laser treatment could...

  20. Laser fusion system design study. Final report

    International Nuclear Information System (INIS)

    1975-01-01

    The following studies were completed: (1) The synthesis of a pointing/control system compatible with existing and advanced laser opto-mechanical configurations. (2) Attainment of the required pointing angle, longitudinal focus, and differential pathlength accuracies. (3) Maximum modularization of the sensor and gimbal assemblies to provide the required accuracies at minimum cost. Detailed information is given on each. (MOW)

  1. Rancidity inhibition study in frozen whole mackerel (scomber scombrus by a previous plant extract treatment.

    Directory of Open Access Journals (Sweden)

    Aubourg, Santiago P.

    2005-09-01

    Full Text Available The effect of flaxseeds (Linum usitatissimum on rancidity development in frozen whole mackerel (Scomber scombrus was studied. For it, fresh mackerel were dipped in flaxseeds aqueous extract during 60 min, frozen at –80 ºC during 24 hours and kept frozen (–20 ºC up to 12 months. Sampling was carried out on the initial material and at months 1, 3, 5, 7, 9 and 12 of frozen storage at –20 ºC. A parallel experiment with non treated fish was carried out in the same conditions. Rancidity development was measured by several biochemical indices (free fatty acids, peroxides, conjugated dienes and trienes, secondary oxidation products and lipoxygenase activity and complemented by the sensory analysis (skin, flesh odour, consistency and flesh appearance. As a result of the previous antioxidant treatment, peroxides showed to breakdown faster (pSe ha estudiado el efecto del lino (Linum usitatissimum en el desarrollo de rancidez en caballa entera congelada (Scomber scombrus. Para ello, caballas frescas fueron sumergidas en extractos acuosos de semillas de lino durante 60 min, congeladas a -80 ºC durante 24 h y mantenidas congeladas ( -20 ºC durante 12 meses. Se tomaron muestras del material inicial y tras 1, 3, 5, 7, 9 y 12 meses de congelación a -20 ºC . Un experimento paralelo con pescado no tratado fue llevado acabo en las mismas condiciones. El desarrollo de la rancidez fue medido por varios índices bioquímicos (ácidos grasos libres, peróxidos, dienos y trienos conjugados, productos secundarios de oxidación y actividad lipoxigenasa y completado con análisis sensorial (piel, olor de la carne, consistencia y apariencia de la carne. Como resultado del tratamiento antioxidante, los peróxidos se degradaron más rápidos (p < 0.05 después del mes 7, y por tanto, contenidos mayores (p < 0.05 de dienos y trienos conjugados pudieron ser detectados en el pescado tratado. El tratamiento antioxidante también condujo a un

  2. Effect of Previous Irradiation on Vascular Thrombosis of Microsurgical Anastomosis: A Preclinical Study in Rats

    Science.gov (United States)

    Gallardo-Calero, Irene; López-Fernández, Alba; Romagosa, Cleofe; Vergés, Ramona; Aguirre-Canyadell, Marius; Soldado, Francisco; Velez, Roberto

    2016-01-01

    Background: The objective of the present investigation was to compare the effect of neoadjuvant irradiation on the microvascular anastomosis in cervical bundle using an experimental model in rats. Methods: One hundred forty male Sprague–Dawley rats were allocated into 4 groups: group I, control, arterial microanastomosis; group II, control, venous microanastomosis; group III, arterial microanastomosis with previous irradiation (20 Gy); and group IV, venous microanastomosis with previous irradiation (20 Gy). Clinical parameters, technical values of anastomosis, patency, and histopathological parameters were evaluated. Results: Irradiated groups (III and IV) and vein anastomosis groups (II and IV) showed significantly increased technical difficulties. Group IV showed significantly reduced patency rates (7/35) when compared with the control group (0/35). Radiotherapy significantly decreased the patency rates of the vein (7/35) when compared with the artery (1/35). Groups III and IV showed significantly reduced number of endothelial cells and also showed the presence of intimal thickening and adventitial fibrosis as compared with the control group. Conclusion: Neoadjuvant radiotherapy reduces the viability of the venous anastomosis in a preclinical rat model with a significant increase in the incidence of vein thrombosis. PMID:27975009

  3. Sun protection behavior and knowledge of patients attending laser clinic to prevent adverse events of laser: A Cross-sectional, Single Center, Tertiary Care Study.

    Science.gov (United States)

    Tempark, Therdpong; Lueangarun, Suparuj; Chatproedprai, Susheera; Panchaprateep, Ratchathorn; Pongprutthipan, Marisa; Wananukul, Siriwan

    2018-06-08

    Limited data of sun protection knowledge in laser treatment patients exists therefore, preventative information should be provided by dermatologists to minimize harmful effects. To assess sun protection knowledge-behavior and knowledge to prevent adverse events from laser therapy among patients who visited a laser clinic at a tertiary university hospital in Bangkok, Thailand. This is a self-reported questionnaire, cross-sectional survey. All participants from the Laser Clinic in KCMH were recruited into the study. A Total of 385 patients were enrolled into the study; 80.5% female participants. Patients who never received laser treatment significantly lacked proper sun protection knowledge to prevent adverse events of lasers when compared to those who previous received laser treatments regarding the application of sunscreen after laser treatment (56.6% vs 17.4%, p protection in the post laser area (41.9% vs 20.4%, p knowledge of sun protection to prevent adverse events were significantly different among the group of educational levels and previous history of laser treatment. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  4. Study of Laser Reflectivity on Skin

    International Nuclear Information System (INIS)

    Oidor-Garcia, J. J. J.; Trevino-Palacios, C. G.

    2008-01-01

    The response to the light on the skin can be manifested as temperature increase or creation of biochemical byproducts, in which further studies are required to asset the light effect. This response changes the average response over time and can produce discrepancies between similar studies. In this work we present a Low Level Laser Therapy (LLLT) study with feedback. We study the time response reflectivity of a 980 nm laser diode of 25 mW modulated at frequencies close to 40 kHz and detect the reflected light on a silicon photodiode, finding no direct correlation between different test points or individuals, while finding reproducible responses within the same individual and test point

  5. Late preterm birth and previous cesarean section: a population-based cohort study.

    Science.gov (United States)

    Yasseen Iii, Abdool S; Bassil, Kate; Sprague, Ann; Urquia, Marcelo; Maguire, Jonathon L

    2018-02-21

    Late preterm birth (LPB) is increasingly common and associated with higher morbidity and mortality than term birth. Yet, little is known about the influence of previous cesarean section (PCS) and the occurrence of LPB in subsequent pregnancies. We aim to evaluate this association along with the potential mediation by cesarean sections in the current pregnancy. We use population-based birth registry data (2005-2012) to establish a cohort of live born singleton infants born between 34 and 41 gestational weeks to multiparous mothers. PCS was the primary exposure, LPB (34-36 weeks) was the primary outcome, and an unplanned or emergency cesarean section in the current pregnancy was the potential mediator. Associations were quantified using propensity weighted multivariable Poisson regression, and mediating associations were explored using the Baron-Kenny approach. The cohort included 481,531 births, 21,893 (4.5%) were LPB, and 119,983 (24.9%) were predated by at least one PCS. Among mothers with at least one PCS, 6307 (5.26%) were LPB. There was increased risk of LPB among women with at least one PCS (adjusted Relative Risk (aRR): 1.20 (95%CI [1.16, 1.23]). Unplanned or emergency cesarean section in the current pregnancy was identified as a strong mediator to this relationship (mediation ratio = 97%). PCS was associated with higher risk of LPB in subsequent pregnancies. This may be due to an increased risk of subsequent unplanned or emergency preterm cesarean sections. Efforts to minimize index cesarean sections may reduce the risk of LPB in subsequent pregnancies.

  6. Laser fusion study. Final report

    International Nuclear Information System (INIS)

    1975-06-01

    The following appendices are included: (1) sensor performance calculation techniques, (2) focus sensing, (3) purchased item data, (4) pointing and focusing configuration tradeoff studies, (5) false start centering sensor, (6) RCA application notes on quad delection, (7) elliptical flex pivot analysis, (8) servo mirrors cross coupling, (9) optical misalignment analysis, (10) stress induced birefrigent quarter-wave retarder, (11) data bulletin on incramute damping alloy, (12) the utilization of stepping motors, and (13) computer program listing for stepper motor load simulation

  7. Phase III Study of Cabozantinib in Previously Treated Metastatic Castration-Resistant Prostate Cancer: COMET-1.

    Science.gov (United States)

    Smith, Matthew; De Bono, Johann; Sternberg, Cora; Le Moulec, Sylvestre; Oudard, Stéphane; De Giorgi, Ugo; Krainer, Michael; Bergman, Andries; Hoelzer, Wolfgang; De Wit, Ronald; Bögemann, Martin; Saad, Fred; Cruciani, Giorgio; Thiery-Vuillemin, Antoine; Feyerabend, Susan; Miller, Kurt; Houédé, Nadine; Hussain, Syed; Lam, Elaine; Polikoff, Jonathan; Stenzl, Arnulf; Mainwaring, Paul; Ramies, David; Hessel, Colin; Weitzman, Aaron; Fizazi, Karim

    2016-09-01

    Cabozantinib is an inhibitor of kinases, including MET and vascular endothelial growth factor receptors, and has shown activity in men with previously treated metastatic castration-resistant prostate cancer (mCRPC). This blinded phase III trial compared cabozantinib with prednisone in patients with mCRPC. Men with progressive mCRPC after docetaxel and abiraterone and/or enzalutamide were randomly assigned at a two-to-one ratio to cabozantinib 60 mg once per day or prednisone 5 mg twice per day. The primary end point was overall survival (OS). Bone scan response (BSR) at week 12 as assessed by independent review committee was the secondary end point; radiographic progression-free survival (rPFS) and effects on circulating tumor cells (CTCs), bone biomarkers, serum prostate-specific antigen (PSA), and symptomatic skeletal events (SSEs) were exploratory assessments. A total of 1,028 patients were randomly assigned to cabozantinib (n = 682) or prednisone (n = 346). Median OS was 11.0 months with cabozantinib and 9.8 months with prednisone (hazard ratio, 0.90; 95% CI, 0.76 to 1.06; stratified log-rank P = .213). BSR at week 12 favored cabozantinib (42% v 3%; stratified Cochran-Mantel-Haenszel P < .001). rPFS was improved in the cabozantinib group (median, 5.6 v 2.8 months; hazard ratio, 0.48; 95% CI, 0.40 to 0.57; stratified log-rank P < .001). Cabozantinib was associated with improvements in CTC conversion, bone biomarkers, and post-random assignment incidence of SSEs but not PSA outcomes. Grade 3 to 4 adverse events and discontinuations because of adverse events were higher with cabozantinib than with prednisone (71% v 56% and 33% v 12%, respectively). Cabozantinib did not significantly improve OS compared with prednisone in heavily treated patients with mCRPC and progressive disease after docetaxel and abiraterone and/or enzalutamide. Cabozantinib had some activity in improving BSR, rPFS, SSEs, CTC conversions, and bone biomarkers but not PSA outcomes. © 2016 by

  8. Radiotherapy enhances laser palliation of malignant dysphagia: a randomised study

    Energy Technology Data Exchange (ETDEWEB)

    Sargeant, I.R.; Thorpe, S.; Glover, J.R.; Bown, S.G. [National Medical Laser Centre, London (United Kingdom); Tobias, J.S.; Blackman, G. [University Coll., London (United Kingdom). Meyerstein Inst. of Oncology

    1997-03-01

    A major drawback of laser endoscopy in the palliation of malignant dysphagia is the need for repeated treatments. This study was designed to test whether external beam radiotherapy would reduce the necessity for repeated laser therapy. (author).

  9. Radiotherapy enhances laser palliation of malignant dysphagia: a randomised study

    International Nuclear Information System (INIS)

    Sargeant, I.R.; Thorpe, S.; Glover, J.R.; Bown, S.G.; Tobias, J.S.; Blackman, G.

    1997-01-01

    A major drawback of laser endoscopy in the palliation of malignant dysphagia is the need for repeated treatments. This study was designed to test whether external beam radiotherapy would reduce the necessity for repeated laser therapy. (author)

  10. Radon diffusion coefficients for soils. Previous studies and their application to uranium-bearing wastes

    International Nuclear Information System (INIS)

    Sasaki, Tomozo; Gunji, Yasuyoshi; Iida, Takao

    2008-01-01

    Radon diffusion in soils has been studied over the years by many researchers. The application of such studies to the evaluation of radiation exposure caused by radon from uranium-bearing wastes disposed in a shallow land site is very important. The present paper surveyed closely relevant studies and elucidated the inherent nature of radon diffusion in terms of the definition of radon diffusion coefficients. Then, basic features of measurement methods for determining radon diffusion coefficients in soils were explained. Furthermore, theoretical aspects of radon diffusion in soils were discussed in terms of microscopic radon diffusion in soils and large-scale radon diffusion through cover soil defects for uranium mill tailings. Finally, in order to apply the radon diffusion studies to uranium-bearing waste disposal in shallow land sites, new challenges were presented: elucidation of radon diffusion in uranium-bearing wastes and cover-soil cracks, and demonstration of the validity of applying only radon diffusion in the evaluation of radiation exposure caused by radon, which would come through Japanese cover soils for uranium-bearing waste disposal. (author)

  11. Interbirth interval and history of previous preeclampsia: a case–control study among multiparous women

    OpenAIRE

    Harutyunyan, Arusyak; Armenian, Haroutune; Petrosyan, Varduhi

    2013-01-01

    Abstract Background Preeclampsia is a disorder with a reported incidence of 2%-8% among all pregnancies, accounting for more than 50,000 deaths worldwide each year. In low- and middle- income countries maternal/perinatal morbidity and mortality associated with preeclampsia are high due to the lack of proper prenatal and hospital care and limited access to neonatal intensive care. The objectives of our study were to determine the association of long in...

  12. A Review of Previous Studies on Information Processing in Career Decision Making among University Students

    OpenAIRE

    池田, 智子; Satoko, Ikeda

    2018-01-01

    This review of the researches of career choice of Japanese university students focused the studies on decision-making theory conducted in Japan. The present review suggested the necessity of examination of the effect of self-efficacy about career information search on the process of career choice. It is also needed to examine the relationship between specific self-efficacy about career information search and career decision-making self-efficacy, moreover, general self-efficacy.

  13. A Comment Upon Previous Studies on 3-D Boundary Layer Transition

    OpenAIRE

    ÇARPINLIOĞLU, Melda Özdinç

    2014-01-01

    The common feature of the experimental studies upon 3-D boundary layer development on swept flat plates cited in the available literature is the application of streamwise and/or spanwise pressure gradients. In fact; presence of the pressure gradients was suggested to be vital for having crossflow effective in 3-D boundary layer transition. In the presented paper here, this idea is questioned evaluating the results of an experimental investigation conducted on swept flat plates under the ab...

  14. Neuropsychiatric and cardiometabolic comorbidities in patients with previously diagnosed Cushing's disease: a longitudinal observational study

    OpenAIRE

    Dimopoulou, C; Geraedts, V; Stalla, G K; Sievers, C

    2015-01-01

    INTRODUCTION: Only few studies have systematically investigated neuropsychiatric aspects in patients with Cushing's disease (CD). Pain syndromes have been described in patients with pituitary adenomas, but so far no systematical investigation has been conducted in patients with CD. Additionally, CD has an association with cardiometabolic comorbidities which ultimately leads to increased morbidity and mortality. Long-term treatment of the hypercortisolic state cannot prevent the persistence of...

  15. A New Zealand based cohort study of anaesthetic trainees' career outcomes compared with previously expressed intentions.

    Science.gov (United States)

    Moran, E M L; French, R A; Kennedy, R R

    2011-09-01

    Predicting workforce requirements is a difficult but necessary part of health resource planning. A 'snapshot' workforce survey undertaken in 2002 examined issues that New Zealand anaesthesia trainees expected would influence their choice of future workplace. We have restudied the same cohort to see if that workforce survey was a good predictor of outcome. Seventy (51%) of 138 surveys were completed in 2009 compared with 100 (80%) of 138 in the 2002 survey. Eighty percent of the 2002 respondents planned consultant positions in New Zealand. We found 64% of respondents were working in New Zealand (P New Zealand based respondents but only 40% of those living outside New Zealand agreed or strongly agreed with this statement (P New Zealand but was important for only 2% of those resident in New Zealand (P New Zealand were predominantly between NZ$150,000 and $200,000 while those overseas received between NZ$300,000 and $400,000. Of those that are resident in New Zealand, 84% had studied in a New Zealand medical school compared with 52% of those currently working overseas (P < 0.01). Our study shows that stated career intentions in a group do not predict the actual group outcomes. We suggest that 'snapshot' studies examining workforce intentions are of little value for workforce planning. However we believe an ongoing program matching career aspirations against career outcomes would be a useful tool in workforce planning.

  16. Exploratory laser-driven shock wave studies

    International Nuclear Information System (INIS)

    Solem, J.C.; Veeser, L.R.

    1977-11-01

    We show the results of a feasibility study for investigating shock structure and for measuring equation-of-state parameters using high-energy, short-pulse lasers. We discuss the temporal and spatial structure of the luminosity from laser-driven shock unloading in aluminum foils. We demonstrate that shock velocity can be measured by observing the time interval between shock emergence across two thicknesses and show data for shocks of 1.3 and 2.1 Mbar. The fact that we observe shock fronts cleanly breaking through steps as small as 3 μm indicates that the shock front thickness is very small in the few megabar region; this is the first experimental verification that these fronts are not more than a few micrometers thick. We present approximate measurements of free-surface velocity. Finally, we speculate on the use of these techniques to obtain detailed equation-of-state data

  17. Laser fusion hybrid reactor systems study

    International Nuclear Information System (INIS)

    1976-07-01

    The work was performed in three phases. The first phase included a review of the many possible laser-reactor-blanket combinations and resulted in the selection of a ''demonstration size'' 500 MWe plant for further study. A number of fast fission blankets using uranium metal, uranium-molybdenum alloy, and uranium carbide as fuel were investigated. The second phase included design of the reactor vessel and internals, heat transfer system, tritium processing system, and the balance of plant, excluding the laser building and equipment. A fuel management scheme was developed, safety considerations were reviewed, and capital and operating costs were estimated. Costs developed during the second phase were unexpectedly high, and a thorough review indicated considerable unit cost savings could be obtained by scaling the plant to a larger size. Accordingly, a third phase was added to the original scope, encompassing the redesign and scaling of the plant from 500 MWe to 1200 MWe

  18. Life cycle impact assessment of ammonia production in Algeria: A comparison with previous studies

    Energy Technology Data Exchange (ETDEWEB)

    Makhlouf, Ali, E-mail: almakhsme@gmail.com; Serradj, Tayeb; Cheniti, Hamza

    2015-01-15

    In this paper, a Life Cycle Analysis (LCA) from “cradle to gate” of one anhydrous ton of ammonia with a purity of 99% was achieved. Particularly, the energy and environmental performance of the product (ammonia) were evaluated. The eco-profile of the product and the share of each stage of the Life Cycle on the whole environmental impacts have been evaluated. The flows of material and energy for each phase of the life cycle were counted and the associated environmental problems were identified. Evaluation of the impact was achieved using GEMIS 4.7 software. The primary data collection was executed at the production installations located in Algeria (Annaba locality). The analysis was conducted according to the LCA standards ISO 14040 series. The results show that Cumulative Energy Requirement (CER) is of 51.945 × 10{sup 3} MJ/t of ammonia, which is higher than the global average. Global Warming Potential (GWP) is of 1.44 t CO{sub 2} eq/t of ammonia; this value is lower than the world average. Tropospheric ozone precursor and Acidification are also studied in this article, their values are: 549.3 × 10{sup −6} t NMVOC eq and 259.3 × 10{sup −6} t SO{sub 2} eq respectively.

  19. Life cycle impact assessment of ammonia production in Algeria: A comparison with previous studies

    International Nuclear Information System (INIS)

    Makhlouf, Ali; Serradj, Tayeb; Cheniti, Hamza

    2015-01-01

    In this paper, a Life Cycle Analysis (LCA) from “cradle to gate” of one anhydrous ton of ammonia with a purity of 99% was achieved. Particularly, the energy and environmental performance of the product (ammonia) were evaluated. The eco-profile of the product and the share of each stage of the Life Cycle on the whole environmental impacts have been evaluated. The flows of material and energy for each phase of the life cycle were counted and the associated environmental problems were identified. Evaluation of the impact was achieved using GEMIS 4.7 software. The primary data collection was executed at the production installations located in Algeria (Annaba locality). The analysis was conducted according to the LCA standards ISO 14040 series. The results show that Cumulative Energy Requirement (CER) is of 51.945 × 10 3 MJ/t of ammonia, which is higher than the global average. Global Warming Potential (GWP) is of 1.44 t CO 2 eq/t of ammonia; this value is lower than the world average. Tropospheric ozone precursor and Acidification are also studied in this article, their values are: 549.3 × 10 −6 t NMVOC eq and 259.3 × 10 −6 t SO 2 eq respectively

  20. X-ray laser studies at LLE

    International Nuclear Information System (INIS)

    Yaakobi, B.; Boehly, T.; Audebert, P.; Epstein, R.; Boswell, B.; Richardson, M.C.; Soures, J.M.; Shvarts, D.

    1988-01-01

    New target geometries for collisional excitation X-ray laser experiments (in nickel) were proposed, analyzed, and experimentally studied on the GDL laser. Experiments using a short line focus lens with new target geometries showed general agreement with predictions. The new geometries are designed to yield a higher gain and reduced refraction due to 1) a higher plasma density, 2) a wider lateral density profile, and 3) a concave lateral density profile. These new geometries were a) two parallel exploding (thin) foils, irradiated from one side only, b) two ablating (thick) foils, one of which is irradiated on its inner face, and c) an exploding foil in front of an ablating foil, irradiated by a single laser beam incident on the thin foil. The experiments with a long line focus are in progress. The intensity ratio of Ne-like and F-like Ni lines is used to deduce the temperature, and these results together with the absolute intensity yields the density profile. The results show improvement achieved with the new target geometries: the density is higher (leading to a higher gain), and the concave density profile results in collimation rather than divergence of the X-ray laser beam. Theoretical developments included development of a ray-tracing code for an amplifying medium of varying (e.g., collimating) lateral density profile (results using this code are shown for convex as well as concave lateral density profiles) and prediction of high gain on new type transitions in neonlike ions, involving the excitation of an inner (2s) electron

  1. Study of Laser Created Metal Vapor Plasmas.

    Science.gov (United States)

    1979-11-16

    Leventhal(1 indicate a value closer to 10-1 cm. might be expected. In the case of’ laser induced penniinf, ionization., wec -,;4-,rit LIP 32 LIP L J where...modified Kramer’s formulae.(25) In figure 11 we demonstrate the impact of associative ionization and laser induced penning ionization upon the temporal...34Laser Induced Fluorescence and Environmental Sensing", Invited paper for Optical Society of America, Topical Mcetixg on "Applications of Laser

  2. Ifosfamide in previously untreated disseminated neuroblastoma. Results of Study 3A of the European Neuroblastoma Study Group.

    Science.gov (United States)

    Kellie, S J; De Kraker, J; Lilleyman, J S; Bowman, A; Pritchard, J

    1988-05-01

    A prospective study of the effectiveness of ifosfamide as a single agent in the management of previously untreated patients with Evans stage IV neuroblastoma was undertaken. Eighteen children aged more than 1 year were treated with ifosfamide (IFX) 3 g/m2 daily for 2 days immediately after diagnosis and 3 weeks later. Treatment was continued with combination chemotherapy using vincristine, cyclophosphamide, cisplatinum and etoposide (OPEC) or a variant. Mesna (2-mercaptoethane sulphonate) was given to all patients during IFX treatment to prevent urotoxicity. Eight of the 18 patients (44%) responded to IFX. Nine had greater than 66% reduction in baseline tumor volume. Of 15 evaluable patients with raised pre-treatment urinary catecholamine excretion, six (40%) achieved greater than 50% reduction in pretreatment levels. Two of 10 patients evaluable for bone marrow response had complete clearance. Toxicity was mild in all patients. Upon completing 'first line' therapy, only four patients (22%) achieved a good partial remission (GPR) or complete response (CR). Median survival was 11 months. There was a lower rate of attaining GPR and shortened median survival in patients receiving phase II IFX before OPEC or variant, compared to patients with similar pre-treatment characteristics treated with OPEC from diagnosis in an earlier study.

  3. Semiconductor laser joint study program with Rome Laboratory

    Science.gov (United States)

    Schaff, William J.; Okeefe, Sean S.; Eastman, Lester F.

    1994-09-01

    A program to jointly study vertical-cavity surface emitting lasers (VCSEL) for high speed vertical optical interconnects (VOI) has been conducted under an ES&E between Rome Laboratory and Cornell University. Lasers were designed, grown, and fabricated at Cornell University. A VCSEL measurement laboratory has been designed, built, and utilized at Rome Laboratory. High quality VCSEL material was grown and characterized by fabricating conventional lateral cavity lasers that emitted at the design wavelength of 1.04 microns. The VCSEL's emit at 1.06 microns. Threshold currents of 16 mA at 4.8 volts were obtained for 30 microns diameter devices. Output powers of 5 mW were measured. This is 500 times higher power than from the light emitting diodes employed previously for vertical optical interconnects. A new form of compositional grading using a cosinusoidal function has been developed and is very successful for reducing diode series resistance for high speed interconnection applications. A flip-chip diamond package compatible with high speed operation of 16 VCSEL elements has been designed and characterized. A flip-chip device binding effort at Rome Laboratory was also designed and initiated. This report presents details of the one-year effort, including process recipes and results.

  4. Femtosecond laser studies of ultrafast intramolecular processes

    Energy Technology Data Exchange (ETDEWEB)

    Hayden, C. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    The goal of this research is to better understand the detailed mechanisms of chemical reactions by observing, directly in time, the dynamics of fundamental chemical processes. In this work femtosecond laser pulses are used to initiate chemical processes and follow the progress of these processes in time. The authors are currently studying ultrafast internal conversion and subsequent intramolecular relaxation in unsaturated hydrocarbons. In addition, the authors are developing nonlinear optical techniques to prepare and monitor the time evolution of specific vibrational motions in ground electronic state molecules.

  5. Theoretcial studies of solar-pumped lasers

    Science.gov (United States)

    Harries, W. L.; Fong, Z. S.

    1984-01-01

    A method of pumping a COhZ laser by a hot cavity was demonstrated. The cavity, heated by solar radiation, should increase the efficiency of solar pumped lasers used for energy conversion. Kinetic modeling is used to examine the behavior of such a COhZ laser. The kinetic equations are solved numerically vs. time and, in addition, steady state solutions are obtained analytically. The effect of gas heating filling the lower laser level is included. The output power and laser efficiency are obtained as functions of black body temperature and gas ratios (COhZ-He-Ar) and pressures. The values are compared with experimental results.

  6. Laser ablation studies in southern Africa

    Science.gov (United States)

    McKenzie, Edric; Forbes, A.; Turner, G. R.; Michaelis, Max M.

    2000-08-01

    With the launch of the South African National Laser Centre, new programs will need to be defined. Medical, environmental and industrial laser applications must obviously take top priority -- as opposed to the uranium isotope separation and military applications of the past. We argue however, that a small effort in laser ablation for space propulsion is justifiable, since a few very large CO2 lasers are available and since two tentative propulsion experiments have already been conducted in South Africa. We attempt to give LISP (Laser Impulse Space Propulsion) an equatorial and a Southern dimension.

  7. Estimating the effect of current, previous and never use of drugs in studies based on prescription registries

    DEFF Research Database (Denmark)

    Nielsen, Lars Hougaard; Løkkegaard, Ellen; Andreasen, Anne Helms

    2009-01-01

    of this misclassification for analysing the risk of breast cancer. MATERIALS AND METHODS: Prescription data were obtained from Danish Registry of Medicinal Products Statistics and we applied various methods to approximate treatment episodes. We analysed the duration of HT episodes to study the ability to identify......PURPOSE: Many studies which investigate the effect of drugs categorize the exposure variable into never, current, and previous use of the study drug. When prescription registries are used to make this categorization, the exposure variable possibly gets misclassified since the registries do...... not carry any information on the time of discontinuation of treatment.In this study, we investigated the amount of misclassification of exposure (never, current, previous use) to hormone therapy (HT) when the exposure variable was based on prescription data. Furthermore, we evaluated the significance...

  8. Studies into laser ignition of confined pyrotechnics

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, S.R.; Russell, D.A. [Centre for Applied Laser Spectroscopy, DASSR, Defence Academy, Cranfield University, Shrivenham, Swindon (United Kingdom)

    2008-10-15

    Ignition tests were carried out on three different pyrotechnics using laser energy from the multimode output from an Ar-Ion laser (av) at 500 nm and a near-IR diode laser pigtailed to a fibre optic cable and operating at 808 nm. The pyrotechnics investigated were: G20 black powder, SR44 and SR371C. The confined ignition tests were conducted in a specially designed ignition chamber. Pyrotechnics were ignited by a free space beam entering the chamber through an industrial sapphire window in the case of the Ar-ion laser. For the NIR diode laser, fibre was ducted through a block into direct contact with the pyrotechnic. The Ar-Ion laser was chosen as this was found to ignite all three pyrotechnics in the unconfined condition. It also allowed for a direct comparison of confined/unconfined results to be made. The threshold laser flux densities to initiate reproducible ignitions at this wavelength were found to be between {proportional_to}12.7 and {proportional_to}0.16 kW cm{sup -2}. Plotted on the ignition maps are the laser flux densities versus the start of ignition times for the three confined pyrotechnics. It was found from these maps that the times for confined ignition were substantially lower than those obtained for unconfined ignition under similar experimental conditions. For the NIR diode laser flux densities varied between {proportional_to}6.8 and {proportional_to}0.2 kW cm{sup -2}. The minimum ignition times for the NIR diode laser for SR371C ({proportional_to}11.2 ms) and G20 ({proportional_to}17.1 ms) were faster than those achieved by the use of the Ar-ion laser. However, the minimum ignition time was shorter ({proportional_to}11.7 ms) with the Ar-ion laser for SR44. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  9. An fMRI study of neuronal activation in schizophrenia patients with and without previous cannabis use

    Directory of Open Access Journals (Sweden)

    Else-Marie eLøberg

    2012-10-01

    Full Text Available Previous studies have mostly shown positive effects of cannabis use on cognition in patients with schizophrenia, which could reflect lower neurocognitive vulnerability. There are however no studies comparing whether such cognitive differences have neuronal correlates. Thus, the aim of the present study was to compare whether patients with previous cannabis use differ in brain activation from patients who has never used cannabis. The patients groups were compared on the ability to up-regulate an effort mode network during a cognitive task and down-regulate activation in the same network during a task-absent condition. Task-present and task-absent brain activation was measured by functional magnetic resonance neuroimaging (fMRI. Twenty-six patients with a DSM-IV and ICD-10 diagnosis of schizophrenia were grouped into a previous cannabis user group and a no-cannabis group. An auditory dichotic listening task with instructions of attention focus on either the right or left ear stimulus was used to tap verbal processing, attention and cognitive control, calculated as an aggregate score. When comparing the two groups, there were remaining activations in the task-present condition for the cannabis group, not seen in the no-cannabis group, while there was remaining activation in the task-absent condition for the no-cannabis group, not seen in the cannabis group. Thus, the patients with previous cannabis use showed increased activation in an effort mode network and decreased activation in the default mode network as compared to the no-cannabis group. It is concluded that the present study show some differences in brain activation to a cognitively challenging task between previous cannabis and no-cannabis schizophrenia patients.

  10. Study of laser cladding nuclear valve parts

    International Nuclear Information System (INIS)

    Shi Shihong; Wang Xinlin; Huang Guodong

    1998-12-01

    The mechanism of laser cladding is discussed by using heat transfer model of laser cladding, heat conduction model of laser cladding and convective transfer mass model of laser melt-pool. Subsequently the laser cladding speed limit and the influence of laser cladding parameters on cladding layer structure is analyzed. A 5 kW with CO 2 transverse flow is used in the research for cladding treatment of sealing surface of stop valve parts of nuclear power stations. The laser cladding layer is found to be 3.0 mm thick. The cladding surface is smooth and has no such defects as crack, gas pore, etc. A series of comparisons with plasma spurt welding and arc bead welding has been performed. The results show that there are higher grain grade and hardness, lower dilution and better performances of resistance to abrasion, wear and of anti-erosion in the laser cladding layer. The new technology of laser cladding can obviously improve the quality of nuclear valve parts. Consequently it is possible to lengthen the service life of nuclear valve and to raise the safety and reliability of the production system

  11. A study of optical design and optimization of laser optics

    Science.gov (United States)

    Tsai, C.-M.; Fang, Yi-Chin

    2013-09-01

    This paper propose a study of optical design of laser beam shaping optics with aspheric surface and application of genetic algorithm (GA) to find the optimal results. Nd: YAG 355 waveband laser flat-top optical system, this study employed the Light tools LDS (least damped square) and the GA of artificial intelligence optimization method to determine the optimal aspheric coefficient and obtain the optimal solution. This study applied the aspheric lens with GA for the flattening of laser beams using collimated laser beam light, aspheric lenses in order to achieve best results.

  12. Airborne laser: a tool to study landscape surface features

    International Nuclear Information System (INIS)

    Ritchie, J.C.; Jackson, T.J.; Everitt, J.H.; Escobar, D.E.; Murphey, J.B.; Grissinger, E.H.

    1992-01-01

    Landscape surface features related to erosion and hydrology were measured using an airborne laser profiler. The airborne laser profiler made 4,000 measurements per second with a recording accuracy of 5 cm (1.9 inches) on a single measurement. Digital data from the laser are recorded and analyzed with a personal computer. These airborne laser profiles provide information on surface landscape features. Topography and canopy heights, cover, and distribution of natural vegetation were determined in studies in South Texas. Laser measurements of shrub cover along flightlines were highly correlated (R 2 = 0.98) with ground measurements made with line-intercept methods. Stream channel cross sections on Goodwin Creek in Mississippi were measured quickly and accurately with airborne laser data. Airborne laser profile data were used to measure small gullies in a level fallow field and in field with mature soybeans. While conventional ground-based techniques can be used to make these measurements, airborne laser profiler techniques allow data to be collected quickly, at a high density, and in areas that are essentially inaccessible for ground surveys. Airborne laser profiler data can quantify landscape features related to erosion and runoff, and the laser proler has the potential to be a useful tool for providing other data for studying and managing natural resources

  13. KrF laser kinetics studies

    International Nuclear Information System (INIS)

    Mandl, A.; Klimek, D.; Parks, J.H.

    1984-01-01

    A series of measurements characterizing an e beam pumped KrF* laser was carried out using a 200-nsec e-beam pulse having a rise time of 25 nsec at current densities up to 50 A/cm 2 . These pump conditions are relevent for inertial confinement fusion laser drivers. The measurements include fluorescence efficiency, sidelight suppression of the fluorescence during lasing, and laser energy output over a wide range of laser parameters including: total density 0.5--2.0 amagats, temperature 300--400 K, fluorine density 0.15%--0.5%, current density 38--50 A/cm 2 and various mirror transmissions. This data was used to verify and refine a model of KrF* kinetics which was then used to estimate the performance of an angular multiplexed power amplifier suitable for laser fusion applications

  14. Dexamethasone intravitreal implant in previously treated patients with diabetic macular edema : Subgroup analysis of the MEAD study

    OpenAIRE

    Augustin, A.J.; Kuppermann, B.D.; Lanzetta, P.; Loewenstein, A.; Li, X.; Cui, H.; Hashad, Y.; Whitcup, S.M.; Abujamra, S.; Acton, J.; Ali, F.; Antoszyk, A.; Awh, C.C.; Barak, A.; Bartz-Schmidt, K.U.

    2015-01-01

    Background Dexamethasone intravitreal implant 0.7?mg (DEX 0.7) was approved for treatment of diabetic macular edema (DME) after demonstration of its efficacy and safety in the MEAD registration trials. We performed subgroup analysis of MEAD study results to evaluate the efficacy and safety of DEX 0.7 treatment in patients with previously treated DME. Methods Three-year, randomized, sham-controlled phase 3 study in patients with DME, best-corrected visual acuity (BCVA) of 34?68 Early Treatment...

  15. Youth suicide: an insight into previous hospitalisation for injury and sociodemographic conditions from a nationwide cohort study.

    Science.gov (United States)

    Zambon, Francesco; Laflamme, Lucie; Spolaore, Paolo; Visentin, Cristiana; Hasselberg, Marie

    2011-06-01

    This study investigates the degree to which a previous hospitalisation for injury of any intent is a risk of subsequent youth suicide and whether this association is influenced by family socioeconomic status or economic stress. A nationwide register-based cohort study was conducted covering all Swedish subjects born between January 1977 and December 1991 (N=1,616,342, male/female ratio=1.05). The cohort subjects were followed-up from January 1998 to December 2003, when aged 7-26 years. Poisson regression and the likelihood ratio test (95% CI) were used to assess the age-adjusted effect of hospitalisation for injuries of various intent on youth suicide and its effect once adjusted for family sociodemographic and social circumstances. Each set of exposures was associated independently and significantly with suicide mortality. Being hospitalised for self-inflicted injuries or injuries of undetermined intent was associated with a risk of suicide 36 to 47 times, respectively, that of subjects never hospitalised in the period under study (95% CI 28.36 to 45.58 and 26.67 to 83.87 for self-inflicted injuries and for events of undetermined intent, respectively; overall psuicide (RR 3.08; 95% CI 2.26 to 4.19). These effects were solid and not substantially altered after adjustment for family demographic and socioeconomic circumstances. A strong association exists between previous hospitalisation for injury of any intent and youth suicide. The association is robust and unaltered by family socioeconomic circumstances.

  16. Previous Fractures at Multiple Sites Increase the Risk for Subsequent Fractures: The Global Longitudinal Study of Osteoporosis in Women

    Science.gov (United States)

    Gehlbach, Stephen; Saag, Kenneth G.; Adachi, Jonathan D.; Hooven, Fred H.; Flahive, Julie; Boonen, Steven; Chapurlat, Roland D.; Compston, Juliet E.; Cooper, Cyrus; Díez-Perez, Adolfo; Greenspan, Susan L.; LaCroix, Andrea Z.; Netelenbos, J. Coen; Pfeilschifter, Johannes; Rossini, Maurizio; Roux, Christian; Sambrook, Philip N.; Silverman, Stuart; Siris, Ethel S.; Watts, Nelson B.; Lindsay, Robert

    2016-01-01

    Previous fractures of the hip, spine, or wrist are well-recognized predictors of future fracture, but the role of other fracture sites is less clear. We sought to assess the relationship between prior fracture at 10 skeletal locations and incident fracture. The Global Longitudinal Study of Osteoporosis in Women (GLOW) is an observational cohort study being conducted in 17 physician practices in 10 countries. Women ≥ 55 years answered questionnaires at baseline and at 1 and/or 2 years (fractures in previous year). Of 60,393 women enrolled, follow-up data were available for 51,762. Of these, 17.6%, 4.0%, and 1.6% had suffered 1, 2, or ≥3 fractures since age 45. During the first 2 years of follow-up, 3149 women suffered 3683 incident fractures. Compared with women with no prior fractures, women with 1, 2, or ≥ 3 prior fractures were 1.8-, 3.0-, and 4.8-fold more likely to have any incident fracture; those with ≥3 prior fractures were 9.1-fold more likely to sustain a new vertebral fracture. Nine of 10 prior fracture locations were associated with an incident fracture. The strongest predictors of incident spine and hip fractures were prior spine fracture (hazard ratio 7.3) and hip (hazard ratio 3.5). Prior rib fractures were associated with a 2.3-fold risk of subsequent vertebral fracture, previous upper leg fracture predicted a 2.2-fold increased risk of hip fracture; women with a history of ankle fracture were at 1.8-fold risk of future fracture of a weight-bearing bone. Our findings suggest that a broad range of prior fracture sites are associated with an increased risk of incident fractures, with important implications for clinical assessments and risk model development. PMID:22113888

  17. Previous experiences and emotional baggage as barriers to lifestyle change - a qualitative study of Norwegian Healthy Life Centre participants.

    Science.gov (United States)

    Følling, Ingrid S; Solbjør, Marit; Helvik, Anne-S

    2015-06-23

    Changing lifestyle is challenging and difficult. The Norwegian Directorate of Health recommends that all municipalities establish Healthy Life Centres targeted to people with lifestyle issues. Little is known about the background, experiences and reflections of participants. More information is needed about participants to shape effective lifestyle interventions with lasting effect. This study explores how participants in a lifestyle intervention programme describe previous life experiences in relation to changing lifestyle. Semi-structured qualitative in-depth interviews were performed with 23 participants (16 women and 7 men) aged 18 - 70 years. The data were analysed using systematic text condensation searching for issues describing participants' responses, and looking for the essence, aiming to share the basis of life-world experiences as valid knowledge. Participants identified two main themes: being stuck in old habits, and being burdened with emotional baggage from their previous negative experiences. Participants expressed a wish to change their lifestyles, but were unable to act in accordance with the health knowledge they possessed. Previous experiences with lifestyle change kept them from initiating attempts without professional assistance. Participants also described being burdened by an emotional baggage with problems from childhood and/or with family, work and social life issues. Respondents said that they felt that emotional baggage was an important explanation for why they were stuck in old habits and that conversely, being stuck in old habits added load to their already emotional baggage and made it heavier. Behavioural change can be hard to perform as psychological distress from life baggage can influence the ability to change. The study participants' experience of being stuck in old habits and having substantial emotional baggage raises questions as to whether or not Healthy Life Centres are able to help participants who need to make a lifestyle

  18. Everolimus for Previously Treated Advanced Gastric Cancer: Results of the Randomized, Double-Blind, Phase III GRANITE-1 Study

    Science.gov (United States)

    Ohtsu, Atsushi; Ajani, Jaffer A.; Bai, Yu-Xian; Bang, Yung-Jue; Chung, Hyun-Cheol; Pan, Hong-Ming; Sahmoud, Tarek; Shen, Lin; Yeh, Kun-Huei; Chin, Keisho; Muro, Kei; Kim, Yeul Hong; Ferry, David; Tebbutt, Niall C.; Al-Batran, Salah-Eddin; Smith, Heind; Costantini, Chiara; Rizvi, Syed; Lebwohl, David; Van Cutsem, Eric

    2013-01-01

    Purpose The oral mammalian target of rapamycin inhibitor everolimus demonstrated promising efficacy in a phase II study of pretreated advanced gastric cancer. This international, double-blind, phase III study compared everolimus efficacy and safety with that of best supportive care (BSC) in previously treated advanced gastric cancer. Patients and Methods Patients with advanced gastric cancer that progressed after one or two lines of systemic chemotherapy were randomly assigned to everolimus 10 mg/d (assignment schedule: 2:1) or matching placebo, both given with BSC. Randomization was stratified by previous chemotherapy lines (one v two) and region (Asia v rest of the world [ROW]). Treatment continued until disease progression or intolerable toxicity. Primary end point was overall survival (OS). Secondary end points included progression-free survival (PFS), overall response rate, and safety. Results Six hundred fifty-six patients (median age, 62.0 years; 73.6% male) were enrolled. Median OS was 5.4 months with everolimus and 4.3 months with placebo (hazard ratio, 0.90; 95% CI, 0.75 to 1.08; P = .124). Median PFS was 1.7 months and 1.4 months in the everolimus and placebo arms, respectively (hazard ratio, 0.66; 95% CI, 0.56 to 0.78). Common grade 3/4 adverse events included anemia, decreased appetite, and fatigue. The safety profile was similar in patients enrolled in Asia versus ROW. Conclusion Compared with BSC, everolimus did not significantly improve overall survival for advanced gastric cancer that progressed after one or two lines of previous systemic chemotherapy. The safety profile observed for everolimus was consistent with that observed for everolimus in other cancers. PMID:24043745

  19. Generation of nanoclusters by ultrafast laser ablation of Al: Molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Miloshevsky, Alexander; Phillips, Mark C.; Harilal, Sivanandan S.; Dressman, Phillip; Miloshevsky, Gennady

    2017-11-01

    The laser ablation of materials induced by an ultrashort femtosecond pulse is a complex phenomenon, which depends on both the material properties and the properties of the laser pulse. The unique capability of a combination of molecular dynamics (MD) and Momentum Scaling Model (MSM) methods is developed and applied to a large atomic system for studying the process of ultrafast laser-material interactions, behavior of matter in a highly non-equilibrium state, material disintegration, and formation of nanoparticles (NPs). Laser pulses with several fluences in the range from 500 J/m2 to 5000 J/m2 interacting with a large system of aluminum atoms are simulated. The response of Al material to the laser energy deposition is investigated within the finite-size laser spot. It is found that the shape of the plasma plume is dynamically changing during an expansion process. At several tens of picoseconds it can be characterized as a long hollow ellipsoid surrounded by atomized and nano-clustered particles. The time evolution of NP clusters in the plume is investigated. The collisions between the single Al atoms and generated NPs and fragmentation of large NPs determine the fractions of different-size NP clusters in the plume. The MD-MSM simulations show that laser fluence greatly affects the size distribution of NPs, their polar angles, magnitude and direction vectors of NP velocities. These results and predictions are supported by the experimental data and previous MD simulations.

  20. Laser-material interactions: A study of laser energy coupling with solids

    Energy Technology Data Exchange (ETDEWEB)

    Shannon, Mark Alan [Univ. of California, Berkeley, CA (United States)

    1993-11-01

    This study of laser-light interactions with solid materials ranges from low-temperature heating to explosive, plasma-forming reactions. Contained are four works concerning laser-energy coupling: laser (i) heating and (ii) melting monitored using a mirage effect technique, (iii) the mechanical stress-power generated during high-powered laser ablation, and (iv) plasma-shielding. First, a photothermal deflection (PTD) technique is presented for monitoring heat transfer during modulated laser heating of opaque solids that have not undergone phase-change. Of main interest is the physical significance of the shape, magnitude, and phase for the temporal profile of the deflection signal. Considered are the effects that thermophysical properties, boundary conditions, and geometry of the target and optical probe-beam have on the deflection response. PTD is shown to monitor spatial and temporal changes in heat flux leaving the surface due to changes in laser energy coupling. The PTD technique is then extended to detect phase-change at the surface of a solid target. Experimental data shows the onset of melt for indium and tin targets. The conditions for which melt can be detected by PTD is analyzed in terms of geometry, incident power and pulse length, and thermophysical properties of the target and surroundings. Next, monitoring high-powered laser ablation of materials with stress-power is introduced. The motivation for considering stress-power is given, followed by a theoretical discussion of stress-power and how it is determined experimentally. Experiments are presented for the ablation of aluminum targets as a function of energy and intensity. The stress-power response is analyzed for its physical significance. Lastly, the influence of plasma-shielding during high-powered pulsed laser-material interactions is considered. Crater size, emission, and stress-power are measured to determine the role that the gas medium and laser pulse length have on plasma shielding.

  1. Laser-material interactions: A study of laser energy coupling with solids

    International Nuclear Information System (INIS)

    Shannon, M.A.; California Univ., Berkeley, CA

    1993-11-01

    This study of laser-light interactions with solid materials ranges from low-temperature heating to explosive, plasma-forming reactions. Contained are four works concerning laser-energy coupling: laser (i) heating and (ii) melting monitored using a mirage effect technique, (iii) the mechanical stress-power generated during high-powered laser ablation, and (iv) plasma-shielding. First, a photothermal deflection (PTD) technique is presented for monitoring heat transfer during modulated laser heating of opaque solids that have not undergone phase-change. Of main interest is the physical significance of the shape, magnitude, and phase for the temporal profile of the deflection signal. Considered are the effects that thermophysical properties, boundary conditions, and geometry of the target and optical probe-beam have on the deflection response. PTD is shown to monitor spatial and temporal changes in heat flux leaving the surface due to changes in laser energy coupling. The PTD technique is then extended to detect phase-change at the surface of a solid target. Experimental data shows the onset of melt for indium and tin targets. The conditions for which melt can be detected by PTD is analyzed in terms of geometry, incident power and pulse length, and thermophysical properties of the target and surroundings. Next, monitoring high-powered laser ablation of materials with stress-power is introduced. The motivation for considering stress-power is given, followed by a theoretical discussion of stress-power and how it is determined experimentally. Experiments are presented for the ablation of aluminum targets as a function of energy and intensity. The stress-power response is analyzed for its physical significance. Lastly, the influence of plasma-shielding during high-powered pulsed laser-material interactions is considered. Crater size, emission, and stress-power are measured to determine the role that the gas medium and laser pulse length have on plasma shielding

  2. Study into penetration speed during laser cutting of brain tissues.

    Science.gov (United States)

    Yilbas, Z; Sami, M; Patiroglu, T

    1998-01-01

    The applications of CO2 continuous-wave lasers in neurosurgery have become important in recent years. Theoretical considerations of laser applicability in medicine are subsequently confirmed experimentally. To obtain precision operation in the laser cutting process, further theoretical developments and experimental studies need to be conducted. Consequently, in the present study, the heat transfer mechanism taking place during laser-tissue interaction is introduced using Fourier theory. The results obtained from the theoretical model are compared with the experimental results. In connection with this, an experiment is designed to measure the penetration speed during the laser cutting process. The measurement is carried out using an optical method. It is found that both results for the penetration speed obtained from the theory and experiment are in a good agreement.

  3. Comparative study on Pulsed Laser Deposition and Matrix Assisted Pulsed Laser Evaporation of urease thin films

    International Nuclear Information System (INIS)

    Smausz, Tomi; Megyeri, Gabor; Kekesi, Renata; Vass, Csaba; Gyoergy, Eniko; Sima, Felix; Mihailescu, Ion N.; Hopp, Bela

    2009-01-01

    Urease thin films were produced by Matrix Assisted Pulsed Laser Evaporation (MAPLE) and Pulsed Laser Deposition from two types of targets: frozen water solutions of urease with different concentrations (1-10% m/v) and pure urease pellets. The fluence of the ablating KrF excimer laser was varied between 300 and 2200 mJ/cm 2 . Fourier transform infrared spectra of the deposited films showed no difference as compared to the original urease. Morphologic studies proved that the films consist of a smooth 'base' layer with embedded micrometer-sized droplets. Absorption-coefficient measurements contradicted the traditional 'absorptive matrix' model for MAPLE deposition. The laser energy was absorbed by urease clusters leading to a local heating-up and evaporation of the frozen matrix from the uppermost layer accompanied by the release of dissolved urease molecules. Significant enzymatic activity of urease was preserved only during matrix assisted transfer.

  4. Doxorubicin and ifosfamide combination chemotherapy in previously treated acute leukemia in adults: a Southwest Oncology Group pilot study.

    Science.gov (United States)

    Ryan, D H; Bickers, J N; Vial, R H; Hussein, K; Bottomley, R; Hewlett, J S; Wilson, H E; Stuckey, W J

    1980-01-01

    The Southwest Oncology Group did a limited institutional pilot study of the combination of doxorubicin and ifosfamide in the treatment of previously treated adult patients with acute leukemia. Thirty-four patients received one or two courses of the combination. All patients had received prior chemotherapy and 32 had received prior anthracycline chemotherapy. Three patients died before their responses could be fully evaluated. Fourteen patients achieved complete remission (41%) and one patient achieved partial remission. The complete remission rate was 27% for patients with acute myeloblastic leukemia (myelomonoblastic leukemia, monoblastic leukemia, and erythroleukemia) and 89% for patients with acute lymphocytic and undifferentiated leukemia (ALL). Toxic effects included severe hematologic reactions in 33 of 34 patients, hematuria in six patients, altered sensorium in one patient, and congestive heart failure in one patient. The safety of the combination was established and toxic side effects of this therapy were tolerable. The 89% complete remission rate for previously treated patients with ALL suggests that the combination of doxorubicin and ifosfamide may be particularly effective in ALL.

  5. Direct solar pumping of semiconductor lasers: A feasibility study

    Science.gov (United States)

    Anderson, Neal G.

    1992-01-01

    This report describes results of NASA Grant NAG-1-1148, entitled Direct Solar Pumping of Semiconductor Lasers: A Feasibility Study. The goals of this study were to provide a preliminary assessment of the feasibility of pumping semiconductor lasers in space with directly focused sunlight and to identify semiconductor laser structures expected to operate at the lowest possible focusing intensities. It should be emphasized that the structures under consideration would provide direct optical-to-optical conversion of sunlight into laser light in a single crystal, in contrast to a configuration consisting of a solar cell or storage battery electrically pumping a current injection laser. With external modulation, such lasers could perhaps be efficient sources for intersatellite communications. We proposed specifically to develop a theoretical model of semiconductor quantum-well lasers photopumped by a broadband source, test it against existing experimental data where possible, and apply it to estimating solar pumping requirements and identifying optimum structures for operation at low pump intensities. These tasks have been accomplished, as described in this report of our completed project. The report is organized as follows: Some general considerations relevant to the solar-pumped semiconductor laser problem are discussed in Section 2, and the types of structures chosen for specific investigation are described. The details of the laser model we developed for this work are then outlined in Section 3. In Section 4, results of our study are presented, including designs for optimum lattice-matched and strained-layer solar-pumped quantum-well lasers and threshold pumping estimates for these structures. It was hoped at the outset of this work that structures could be identified which could be expected to operate continuously at solar photoexcitation intensities of several thousand suns, and this indeed turned out to be the case as described in this section. Our project is

  6. Laser-welded ureteral anastomoses: experimental studies with three techniques.

    Science.gov (United States)

    Gürpinar, T; Gürer, S; Kattan, M W; Wang, L; Griffith, D P

    1996-01-01

    Tissue welding with laser energy is a new technique for reconstructive surgery. The potential advantages of laser welding are (a) lack of foreign body reaction, (b) decreased operative time, (c) less tissue manipulation, and (d) effective union of tissues equivalent to sutured anastomoses. We have performed ureteral anastomoses in adult mongrel dogs using a KTP 532 nm laser at an intensity of 1.4 W. Multiple "spot welds" of 1-s duration were utilized in a single layer anastomosis. Laser-welded anastomoses were performed with and without protein solder (33% and 50% human albumin) and were compared to sutured anastomoses. The laser-welded anastomoses required less operative time and provided bursting pressure levels similar to those of traditional sutured anastomoses. There was no advantage or disadvantage to the addition of human albumin as a solder in these experimental studies.

  7. Study on process of laser cladded nuclear valve parts

    International Nuclear Information System (INIS)

    Zhang Chunliang

    2000-01-01

    The microstructure and performances of the Co-base alloy coatings that are formed by laser cladding, plasma spurt welding and arc surfacing on the nuclear valve-sealing surface have been studied and compared. The combination costs of laser cladding, plasma spurt welding and arc, surfacing have been analyzed and compared. The results showed that the laser cladding processing has the advantages of high efficiency, low energy cost, a little machining allowance, high rate of finished products and low combination cost, compared with plasma spurt welding processing and arc surfacing processing. The laser cladding technology can improve the qualities of nuclear valve parts and increase their service life. Therefore, the laser cladding processing is a new technology with developing potential

  8. The suitability of XRF analysis for compositional classification of archaeological ceramic fabric: A comparison with a previous NAA study

    International Nuclear Information System (INIS)

    Padilla, R.; Espen, P. van; Torres, P.P. Godo

    2006-01-01

    The main drawbacks of EDXRF techniques, restricting its more frequent use for the specific purpose of compositional analysis of archaeological ceramic fabric, have been the insufficient sensitivity to determine some important elements (like Cr, REE, among others), a somewhat worse precision and the inability to perform standard-less quantitative procedures in the absence of suitable certified reference materials (CRM) for ceramic fabric. This paper presents the advantages of combining two energy dispersive X-ray fluorescence methods for fast and non-destructive analysis of ceramic fabric with increased sensitivity. Selective polarized excitation using secondary targets (EDPXRF) and radioisotope excitation (R-XRF) using a 241 Am source. The analytical performance of the methods was evaluated by analyzing several CRM of sediment type, and the fitness for the purpose of compositional classification was compared with that obtained by using Instrumental Neutron Activation Analysis in a previous study of Cuban aborigine pottery

  9. The suitability of XRF analysis for compositional classification of archaeological ceramic fabric: A comparison with a previous NAA study

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, R. [Centro de Aplicaciones Tecnologicas y Desarrollo Nuclear (CEADEN), Laboratorio de Analisis Quimico, Calle 30 no. 502, Playa, Ciudad Habana (Cuba)]. E-mail: roman.padilla@infomed.sld.cu; Espen, P. van [University of Antwerp (Belgium); Torres, P.P. Godo [Centro de Antropologia, Havana (Cuba)

    2006-02-03

    The main drawbacks of EDXRF techniques, restricting its more frequent use for the specific purpose of compositional analysis of archaeological ceramic fabric, have been the insufficient sensitivity to determine some important elements (like Cr, REE, among others), a somewhat worse precision and the inability to perform standard-less quantitative procedures in the absence of suitable certified reference materials (CRM) for ceramic fabric. This paper presents the advantages of combining two energy dispersive X-ray fluorescence methods for fast and non-destructive analysis of ceramic fabric with increased sensitivity. Selective polarized excitation using secondary targets (EDPXRF) and radioisotope excitation (R-XRF) using a {sup 241}Am source. The analytical performance of the methods was evaluated by analyzing several CRM of sediment type, and the fitness for the purpose of compositional classification was compared with that obtained by using Instrumental Neutron Activation Analysis in a previous study of Cuban aborigine pottery.

  10. Treatment satisfaction with paliperidone extended-release tablets: open-label study in schizophrenia patients dissatisfied with previous antipsychotic medication

    Directory of Open Access Journals (Sweden)

    Yang FD

    2017-04-01

    Full Text Available Fu De Yang,1 Juan Li,1 Yun Long Tan,1 Wei Ye Liang,1 Rongzhen Zhang,1 Ning Wang,1 Wei Feng,1 Shangli Cai,2 Jian Min Zhuo,2 Li Li Zhang2 1Beijing Hui-Long-Guan Hospital, 2Department of Medical Affairs, Xian Janssen Pharmaceutical Ltd, Beijing, People’s Republic of China Objective: The aim of this study was to evaluate the changes in treatment satisfaction after switching to paliperidone extended-release (ER in Chinese schizophrenia patients dissatisfied with their previous antipsychotic treatment.Methods: In this 8-week, open-label, single-arm, multicenter, prospective study, 1,693 patients dissatisfied with previous antipsychotic medication were enrolled and switched to paliperidone ER tablets (3–12 mg/d based on clinical judgment. The primary efficacy end point was change in Medication Satisfaction Questionnaire (MSQ score from baseline to week 8. The secondary end points included percentage of patients with MSQ score ≥4, as well as changes in Clinical Global Improvement-Severity (CGI-S and Personal and Social Performance (PSP scores.Results: MSQ scores increased significantly from baseline (mean [standard deviation {SD}]: 2.48 [0.55] to week 8 (5.47 [0.89], P<0.0001; primary end point, full analysis set. The percentage of patients with MSQ score ≥4 was 95.9% at week 8, indicating that most of the patients were satisfied with their treatment. Significant (P<0.0001 improvements from baseline to week 8 were noted in CGI-S score (2.37 [1.20] and PSP score (25.5 [15.0]. A total of 174 (10.28% patients experienced adverse events (AEs. The most common (>10 patients events were extrapyramidal disorder (n=84, 4.96%, poor quality sleep (n=18, 1.06% and akathisia (n=13, 0.77%. The majority of AEs were mild to moderate in severity. No deaths occurred.Conclusion: Treatment satisfaction improved after switching to paliperidone ER from the previous antipsychotic in Chinese patients with schizophrenia. Keywords: atypical antipsychotics, open label

  11. Status of fiber lasers study of on ytterbium doped fiber laser and laser spectroscopy of doped fibers

    International Nuclear Information System (INIS)

    Magne, S.

    1994-07-01

    This work shows all the advantages and drawbacks of the rare-earth-doped fiber lasers and fiber optical amplifiers, pointing out their potential use for instrumentation and optical fiber sensor technology. The theory of light propagation in optical fibers is presented in order to understand the manufacturing methods. A comparative study of preform surface and concentration analysis is performed. The gain behaviour is also thoroughly examined. A synthesis of all technological parameters of the fiber laser is then established and all technologies of the constituting integrated components are reviewed and compared. The experimental techniques mainly involve: site selective excitation tunability, cooperative luminescence, oxidation state changes induced by gamma irradiation, ytterbium-doped mono-mode continuous wave tunable three-level fiber laser. (TEC). 622 refs., 176 figs

  12. Experimental study on concrete cutting by CO2 laser beam

    International Nuclear Information System (INIS)

    Kutsumizu, Akira; Tomura, Hidemasa; Wakizaka, Tatsuya; Hishikawa, Kyoichi; Moriya, Masahiro

    1994-01-01

    Methods for dismantling nuclear reactor facilities must meet particularly exacting requirements imposed by heavily reinforced and radioactivated reactor shield walls. Conventional methods do not meet all such requirements, however. Intrigued by excellent characteristics of the laser cutting method relative to nuclear facility demolition, we carried out an experimental study to make a comprehensive evaluation of its characteristics, especially for deep cutting, with success in identifying main factors affecting the cutting depth of a laser and characterizing its cutting behavior. The study results indicate that a 50 kW class CO 2 laser has a potential to provide a practicable cutting speed and depth. (author)

  13. Preparation and study of laser plasma diamond

    Energy Technology Data Exchange (ETDEWEB)

    Collins, C.B.; Davanloo, F.; Juengerman, E.M.; Jander, D.R.; Lee, T.J. (Center for Quantum Electronics, Univ. of Texas, Dallas (USA))

    1991-08-01

    Films of diamond-like material can be deposited with a laser plasma source of carbon ions in an ultrahigh vacuum environment without involving hydrogen in the growth mechanism. These films are distinguished by transparency at visible wavelengths which is a result of a high percentage of sp{sup 3} bonds. They resemble materials first quenched from ion beams at very slow deposition rates. In our method an Nd:YAG laser was focused on a graphite feedstock in an ultrahigh vacuum chamber at intensities in excess of 5x10{sup 11} W cm{sup -2}. A high current discharge confined to the path of the laser-ignited plasma provided further heat and aided processing of the ion flux. At a laser repetition rate of 10 Hz, a deposition rate of 0.5 {mu}m h{sup -1} over a 100 cm{sup 2} area was attainable with no measurable substrate heating. The substrates required no special preparation or seeding and materials including silicon, fused silica, glass, gold, copper, germanium, InP, ZnS, and polycarbonate and polyimide plastics were readily coated. Complex shapes could be accommodated and spheres of 440C stainless steel were covered successfully. Over 1000 samples were prepared to a variety of specifications with thicknesses reaching 5 {mu}m and hardness exceeding 37 GPa. (orig.).

  14. Value and reliability of findings from previous epidemiologic studies in the assessment of radiation-related cancer risks. Pt. 3

    International Nuclear Information System (INIS)

    Frasch, G.; Martignoni, K.

    1990-01-01

    The theories put forward here are predominantly based on pooled data from previous studies in a number of cohorts made up by mostly non-average individuals. These studies were carried out by various researchers and differed in procedures and aims. Factors of major importance to the validity and reliability of the conclusions drawn from this study are pointed out. In one chapter some light is thrown on factors known to bear a relation to the incidence of radiation-induced cancer of the breast, even though at present this can only very vaguely be described on a quantitative basis. These factors include fractionated dose regimens, pregnancies and parturitions, menarche, menopause, synergisms as well as secondary cancer of the breast. The available body of evidence suggests that exposure of each of 1 million women to a dose of 10 mGy (rad) can be linked with approx. 3 additional cases of mammary cancer reported on an average per year after the latency period. The fact that there is some statistical scatter around this value is chiefly attributable to age-related causes at the beginning of exposure. Differences in ethnic and cultural characteristics between the populations investigated appeared to be less important here. (orig./MG) [de

  15. Barriers to postpartum screening for type 2 diabetes: a qualitative study of women with previous gestational diabetes.

    Science.gov (United States)

    Rafii, Forough; Rahimparvar, Seyedeh Fatemeh Vasegh; Mehrdad, Neda; Keramat, Afsaneh

    2017-01-01

    Risk of developing type 2 diabetes is increased in women with previous gestational diabetes mellitus (GDM). Postpartum glycemic screening is recommended in women with recent GDM. But this screening rate is low and the reasons are unclear. The aim of this study was to explore the experiences of Iranian women with recent GDM on barriers of postpartum screening for diabetes. This qualitative study was conducted in Tehran, Iran in 2016. Semi-structured interview was used for data collection. 22 women with recent GDM were interviewed. These women gave birth in Tehran hospitals at a minimum of 6 months before interview. The missed screening defined as not attending to laboratory for Fasting Blood Sugar and/or Oral Glucose Tolerance Test, 6 week to 6 month after their child birthing. The data was analyzed by content analysis method. Themes and sub-themes that illustrated the barriers to postpartum diabetes screening were: inadequate education (about developing diabetes in the future, implementation of the screening, and glucometer validity in diagnosis of diabetes), perceiving the screening as difficult (feeling comfortable with the glucometer, poor laboratory conditions, issues related to the baby/babies, and financial problems), improper attitudes toward the screening (unwilling to get diagnosed, not giving priority to oneself, having false beliefs) and procrastination (gap to intention and action, self-deception and self-regulation failure). Women with recent GDM reported several barriers for postpartum diabetes screening. This study help to develop the evidence-based interventions for improving this screening rate.

  16. A Flexible-Dose Study of Paliperidone ER in Patients With Nonacute Schizophrenia Previously Treated Unsuccessfully With Oral Olanzapine.

    Science.gov (United States)

    Kotler, Moshe; Dilbaz, Nesrin; Rosa, Fernanda; Paterakis, Periklis; Milanova, Vihra; Smulevich, Anatoly B; Lahaye, Marjolein; Schreiner, Andreas

    2016-01-01

    The goal of this study was to explore the tolerability, safety, and treatment response of switching from oral olanzapine to paliperidone extended release (ER). Adult patients with nonacute schizophrenia who had been treated unsuccessfully with oral olanzapine were switched to flexible doses of paliperidone ER (3 to 12 mg/d). The primary efficacy outcome was a ≥ 20% improvement in Positive and Negative Syndrome Scale (PANSS) total scores from baseline to endpoint for patients who switched medications because of lack of efficacy with olanzapine and noninferiority versus previous olanzapine treatment (mean endpoint change in PANSS total scores vs. baseline of ≤ 5 points) for patients who switched for reasons other than lack of efficacy. Safety and tolerability were assessed by monitoring adverse events, extrapyramidal symptoms, and weight change. Of 396 patients, 65.2% were men, mean age was 40.0 ± 12.0 years, and 75.5% had paranoid schizophrenia. Among the patients whose main reason for switching was lack of efficacy, an improvement in the PANSS total score of ≥ 20% occurred in 57.4% of patients. Noninferiority was confirmed for each subgroup of patients whose main reason for switching was something other than lack of efficacy. Paliperidone ER was generally well tolerated. Extrapyramidal symptoms as measured by total Extrapyramidal Symptom Rating Scale scores showed statistically significant and clinically relevant improvements at endpoint, the average weight decreased by 0.8 ± 5.2 kg at endpoint, and a clinically relevant weight gain of ≥ 7% occurred in 8.0% of patients. Paliperidone ER flexibly-dosed over 6 months was well tolerated and associated with a meaningful clinical response in patients with nonacute schizophrenia who had previously been unsuccessfully treated with oral olanzapine.

  17. Biological Studies with Laser-Polarized ^129Xe

    Science.gov (United States)

    Tseng, C. H.; Oteiza, E. R.; Wong, G. A.; Walsworth, R. L.; Albert, M. S.; Nascimben, L.; Peled, S.; Sakai, K.; Jolesz, F. A.

    1996-05-01

    We have studied several biological systems using laser-polarized ^129Xe. In certain tissues magnetic resonance imaging (MRI) using inhaled laser-polarized noble gases may provide images superior to those from conventional proton MRI. High resolution laser-polarized ^3He images of air spaces in the human lung were recently obtained by the Princeton/Duke group. However, ^3He is not very soluble in tissue. Therefore, we are using laser polarized ^129Xe (tissue-soluble), with the long term goal of biomedical functional imaging. We have investigated multi-echo and multi-excitation magnetic resonance detection schemes to exploit the highly non-thermal ^129Xe magnetization produced by the laser polarization technique. We have inhalated live rats with laser-polarized ^129Xe gas and measured three distinct ^129Xe tissue resonances that last 20 to 40 sec. As a demonstration, we obtained a laser polarized ^129Xe image of the human oral cavity. Currently we are measuring the polarization lifetime of ^129Xe dissolved in human blood, the biological transporting medium. These studies and other recent developments will be reported.

  18. Study of CW Nd-Yag laser welding of Zn-coated steel sheets

    International Nuclear Information System (INIS)

    Fabbro, Remy; Coste, Frederic; Goebels, Dominique; Kielwasser, Mathieu

    2006-01-01

    The welding of Zn-coated steel thin sheets is a great challenge for the automotive industry. Previous studies have defined the main physical processes involved. For non-controlled conditions, the zinc vapour expelled from the interface of the two sheets violently expands inside the keyhole and expels the melt pool. When using CO 2 lasers, we have previously shown that an elongated laser spot produces an elongated keyhole, which is efficient for suppressing this effect. We have adopted a similar approach for CW Nd : Yag laser welding and we observe that an elongated spot is not necessary for achieving good weld seams. Several diagnostics were used in order to understand these interesting results. High-speed video camera visualizations of the top and the bottom of the keyhole during the process show the dynamics of the keyhole hydrodynamic behaviour. It appears that the role of the reflected beam on the front keyhole wall for generating a characteristic rear wall deformation is crucial for an efficient stabilization of the process. Our dynamic keyhole modelling, which includes ray tracing, totally confirms this interpretation and explains the results for very different experimental conditions (effect of welding speed, laser intensity, variable sheet thickness, laser beam intensity distribution) that will be presented

  19. Diagnostics for studies of novel laser ion acceleration mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Senje, Lovisa; Aurand, Bastian; Wahlström, Claes-Göran [Department of Physics, Lund University, P. O. Box 118, S-221 00 Lund (Sweden); Yeung, Mark; Kuschel, Stephan; Rödel, Christian [Helmholtz-Institut Jena, D-07743 Jena (Germany); Wagner, Florian; Roth, Markus [Technische Universität Darmstadt, D-64289 Darmstadt (Germany); Li, Kun; Neumayer, Paul [ExtreMe Matter Institut, D-64291 Darmstadt (Germany); Dromey, Brendan; Jung, Daniel [Department of Physics and Astronomy, Queen' s University, Belfast BT7 1NN (United Kingdom); Bagnoud, Vincent [Helmholtz-Institut Jena, D-07743 Jena (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Zepf, Matthew [Helmholtz-Institut Jena, D-07743 Jena (Germany); Department of Physics and Astronomy, Queen' s University, Belfast BT7 1NN (United Kingdom); Kuehl, Thomas [ExtreMe Matter Institut, D-64291 Darmstadt (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Universität Mainz, D-55099 Mainz (Germany)

    2014-11-15

    Diagnostic for investigating and distinguishing different laser ion acceleration mechanisms has been developed and successfully tested. An ion separation wide angle spectrometer can simultaneously investigate three important aspects of the laser plasma interaction: (1) acquire angularly resolved energy spectra for two ion species, (2) obtain ion energy spectra for multiple species, separated according to their charge to mass ratio, along selected axes, and (3) collect laser radiation reflected from and transmitted through the target and propagating in the same direction as the ion beam. Thus, the presented diagnostic constitutes a highly adaptable tool for accurately studying novel acceleration mechanisms in terms of their angular energy distribution, conversion efficiency, and plasma density evolution.

  20. Diagnostics for studies of novel laser ion acceleration mechanisms

    International Nuclear Information System (INIS)

    Senje, Lovisa; Aurand, Bastian; Wahlström, Claes-Göran; Yeung, Mark; Kuschel, Stephan; Rödel, Christian; Wagner, Florian; Roth, Markus; Li, Kun; Neumayer, Paul; Dromey, Brendan; Jung, Daniel; Bagnoud, Vincent; Zepf, Matthew; Kuehl, Thomas

    2014-01-01

    Diagnostic for investigating and distinguishing different laser ion acceleration mechanisms has been developed and successfully tested. An ion separation wide angle spectrometer can simultaneously investigate three important aspects of the laser plasma interaction: (1) acquire angularly resolved energy spectra for two ion species, (2) obtain ion energy spectra for multiple species, separated according to their charge to mass ratio, along selected axes, and (3) collect laser radiation reflected from and transmitted through the target and propagating in the same direction as the ion beam. Thus, the presented diagnostic constitutes a highly adaptable tool for accurately studying novel acceleration mechanisms in terms of their angular energy distribution, conversion efficiency, and plasma density evolution

  1. Conceptual design study for a laser fusion hybrid

    International Nuclear Information System (INIS)

    Maniscalco, J.A.

    1976-01-01

    Lawrence Livermore Laboratory and Bechtel Corporation have been involved in a joint effort to conceptually design a laser fusion hybrid reactor. The design which has evolved is a depleted-uranium fueled fast-fission blanket which produces fissile plutonium and electricity. A major objective of the design study was to evaluate the feasibility of producing fissile fuel with laser fusion. This feasibility evaluation was carried out by analyzing the integrated engineering performance of the complete conceptual design and by identifying the required laser/pellet performance. The performance of the laser fusion hybrid has also been compared to a typical fast breeder reactor. The results show that the laser fusion hybrid produces enough fissile material to fuel more than six light water reactors (LWRs) of equivalent thermal power while operating in a regime which requires an order of magnitude less laser and pellet performance than pure laser fusion. In comparison to a fast breeder reactor the hybrid produces 10 times more fissile fuel. An economic analysis of the design shows that the cost of electricity in a combined hybrid-LWR scenario increases by only 20 to 40 percent when the capital cost of the hybrid ranges from 2 to 3 times more than an LWR

  2. Conceptual design study for a laser fusion hybrid

    International Nuclear Information System (INIS)

    Maniscalco, J.A.

    1976-09-01

    Lawrence Livermore Laboratory and Bechtel Corporation have been involved in a joint effort to conceptually design a laser fusion hybrid reactor. The design which has evolved is a depleted-uranium fueled fast-fission blanket which produces fissile plutonium and electricity. A major objective of the design study was to evaluate the feasibility of producing fissile fuel with laser fusion. This feasibility evaluation was carried out by analyzing the integrated engineering performance of the complete conceptual design and by identifying the required laser/pellet performance. The performance of the laser fusion hybrid has also been compared to a typical fast breeder reactor. The results show that the laser fusion hybrid produces enough fissile material to fuel more than six light water reactors (LWR's) of equivalent thermal power while operating in a regime which requires an order of magnitude less laser and pellet performance than pure laser fusion. In comparison to a fast breeder reactor the hybrid produces 10 times more fissile fuel. An economic analysis of the design shows that the cost of electricity in a combined hybrid-LWR scenario is insensitive to the capital cost of the hybrid, increasing by only 20 to 40 percent when the capital cost of the hybrid ranges from 2 to 3 times more than an LWR

  3. Pilot Study of an Individualised Early Postpartum Intervention to Increase Physical Activity in Women with Previous Gestational Diabetes

    Directory of Open Access Journals (Sweden)

    Harold David McIntyre

    2012-01-01

    Full Text Available Optimal strategies to prevent progression towards overt diabetes in women with recent gestational diabetes remain ill defined. We report a pilot study of a convenient, home based exercise program with telephone support, suited to the early post-partum period. Twenty eight women with recent gestational diabetes were enrolled at six weeks post-partum into a 12 week randomised controlled trial of Usual Care (n=13 versus Supported Care (individualised exercise program with regular telephone support; n=15. Baseline characteristics (Mean ± SD were: Age  33±4  years; Weight 80 ± 20 kg and Body Mass Index (BMI 30.0±9.7 kg/m2. The primary outcome, planned physical activity {Median (Range}, increased by 60 (0–540 mins/week in the SC group versus 0 (0–580 mins/week in the UC group (P=0.234. Walking was the predominant physical activity. Body weight, BMI, waist circumference, % body fat, fasting glucose and insulin did not change significantly over time in either group. This intervention designed to increase physical activity in post-partum women with previous gestational diabetes proved feasible. However, no measurable improvement in metabolic or biometric parameters was observed over a three month period.

  4. Patterns and Determinants of Treatment Seeking among Previously Untreated Psychotic Patients in Aceh Province, Indonesia: A Qualitative Study

    Directory of Open Access Journals (Sweden)

    Marthoenis Marthoenis

    2016-01-01

    Full Text Available Immediate treatment of first-episode psychosis is essential in order to achieve a positive outcome. However, Indonesian psychiatric patients often delay accessing health services, the reason for which is not yet fully understood. The current study aimed to understand patterns of treatment seeking and to reveal determinants of the delay in accessing psychiatric care among first-time user psychotic patients. Qualitative interviews were conducted with sixteen family members who accompanied the patients to a psychiatric hospital. Many families expressed beliefs that mental illness appertains to village sickness and not hospital sickness; therefore, they usually take the patients to traditional or religious healers before taking them to a health professional. They also identified various factors that potentially delay accessing psychiatric treatment: low literacy and beliefs about the cause of the illness, stigmatisation, the role of extended family, financial problems, and long distance to the psychiatric hospital. On the other hand, the family mentioned various factors related to timely help seeking, including being a well-educated family, living closer to health facilities, previous experience of successful psychotic therapy, and having more positive symptoms of psychosis. The findings call for mental health awareness campaigns in the community.

  5. Studies of intense-laser plasma instabilities

    Czech Academy of Sciences Publication Activity Database

    Láska, Leoš; Krása, Josef; Badziak, J.; Jungwirth, Karel; Krouský, Eduard; Margarone, Daniele; Parys, P.

    2013-01-01

    Roč. 272, May (2013), 94-98 ISSN 0169-4332 R&D Projects: GA MŠk(CZ) 7E09092; GA MŠk(CZ) LC528; GA AV ČR IAA100100715 Institutional research plan: CEZ:AV0Z10100523 Keywords : laser plasma instabilities * self-generated magnetic field * longitudinal structure of the expanding plasma Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.538, year: 2013

  6. Interferometric studies of laser-created plasmas using compact soft x-ray lasers

    International Nuclear Information System (INIS)

    Dunn, J; Nilsen, J; Moon, S; Keenan, R; Jankowska, E; Maconi, M C; Hammarsten, E C; Filevich, J; Hunter, J R; Smith, R F; Shlyaptsev, V; Rocca, J J

    2003-01-01

    We summarize results of several successful dense plasma diagnostics experiments realized by combining two different kinds of table-top soft x-ray lasers with an amplitude division interferometer based on diffraction grating beam splitters. In the first set of experiments this robust high throughput diffraction grating interferometer (DGI) was used with a 46.9 nm portable capillary discharge laser to study the dynamics of line focus and point focus laser-created plasmas. The measured electron density profiles, which differ significantly from those expected from a classical expansion, unveil important two-dimensional effects of the dynamics of these plasmas. A second DGI customized to operate in combination with a 14.7 nm Ni-like Pd transient gain laser was used to perform interferometry of line focus laser-created plasmas with picosecond time resolution. These measurements provide valuable new benchmarks for complex hydrodynamic codes and help bring new understanding of the dynamics of dense plasmas. The instrumentation and methodology we describe is scalable to significantly shorter wavelengths, and constitutes a promising scheme for extending interferometry to the study of very dense plasmas such as those investigated for inertial confinement fusion

  7. Lasers

    CERN Document Server

    Milonni, Peter W

    1988-01-01

    A comprehensive introduction to the operating principles and applications of lasers. Explains basic principles, including the necessary elements of classical and quantum physics. Provides concise discussions of various laser types including gas, solid state, semiconductor, and free electron lasers, as well as of laser resonators, diffraction, optical coherence, and many applications including holography, phase conjugation, wave mixing, and nonlinear optics. Incorporates many intuitive explanations and practical examples. Discussions are self-contained in a consistent notation and in a style that should appeal to physicists, chemists, optical scientists and engineers.

  8. A Questionnaire Study on the Attitudes and Previous Experience of Croatian Family Physicians toward their Preparedness for Disaster Management.

    Science.gov (United States)

    Pekez-Pavliško, Tanja; Račić, Maja; Jurišić, Dinka

    2018-04-01

    To explore family physicians' attitudes, previous experience and self-assessed preparedness to respond or to assist in mass casualty incidents in Croatia. The cross-sectional survey was carried out during January 2017. Study participants were recruited through a Facebook group that brings together family physicians from Croatia. They were asked to complete the questionnaire, which was distributed via google.docs. Knowledge and attitudes toward disaster preparedness were evaluated by 18 questions. Analysis of variance, Student t test and Kruskal-Wallis test t were used for statistical analysis. Risk awareness of disasters was high among respondents (M = 4.89, SD=0.450). Only 16.4 of respondents have participated in the management of disaster at the scene. The majority (73.8%) of physicians have not been participating in any educational activity dealing with disaster over the past two years. Family physicians believed they are not well prepared to participate in national (M = 3.02, SD=0.856) and local community emergency response system for disaster (M = 3.16, SD=1.119). Male physicians scored higher preparedness to participate in national emergency response system for disaster ( p =0.012), to carry out accepted triage principles used in the disaster situation ( p =0.003) and recognize differences in health assessments indicating potential exposure to specific agents ( p =0,001) compared to their female colleagues. Croatian primary healthcare system attracts many young physicians, who can be an important part of disaster and emergency management. However, the lack of experience despite a high motivation indicates a need for inclusion of disaster medicine training during undergraduate studies and annual educational activities.

  9. Previous injuries and some training characteristics predict running-related injuries in recreational runners: a prospective cohort study.

    Science.gov (United States)

    Hespanhol Junior, Luiz Carlos; Pena Costa, Leonardo Oliveira; Lopes, Alexandre Dias

    2013-12-01

    What is the incidence of running-related injuries (RRIs) in recreational runners? Which personal and training characteristics predict RRIs in recreational runners? Prospective cohort study. A total of 200 recreational runners answered a fortnightly online survey containing questions about their running routine, races, and presence of RRI. These runners were followed-up for a period of 12 weeks. The primary outcome of this study was running-related injury. The incidence of injuries was calculated taking into account the exposure to running and was expressed by RRI/1000 hours. The association between potential predictive factors and RRIs was estimated using generalised estimating equation models. A total of 84 RRIs were registered in 60 (31%) of the 191 recreational runners who completed all follow-up surveys. Of the injured runners 30% (n=18/60) developed two or more RRIs, with 5/18 (28%) being recurrences. The incidence of RRI was 10 RRI/1000 hours of running exposure. The main type of RRI observed was muscle injuries (30%, n=25/84). The knee was the most commonly affected anatomical region (19%, n=16/84). The variables associated with RRI were: previous RRI (OR 1.88, 95% CI 1.01 to 3.51), duration of training although the effect was very small (OR 1.01, 95% CI 1.00 to 1.02), speed training (OR 1.46, 95% CI 1.02 to 2.10), and interval training (OR 0.61, 95% CI 0.43 to 0.88). Physiotherapists should be aware and advise runners that past RRI and speed training are associated with increased risk of further RRI, while interval training is associated with lower risk, although these associations may not be causative. Copyright © 2013 Australian Physiotherapy Association. Published by Elsevier B.V. All rights reserved.

  10. Kinetics studies following state-selective laser excitation

    International Nuclear Information System (INIS)

    Keto, J.W.

    1994-04-01

    The objective of this contract was the study of state-to-state, electronic energy transfer reactions relevant to the excited state chemistry observed in discharges. We studied deactivation reactions and excitation transfer in collisions of excited states of xenon and krypton atoms with Ar, Kr, Xe and chlorine. The reactant states were excited selectively in two-photon transitions using tunable u.v. and v.u.v. lasers. Excited states produced by the collision were observed by their fluorescence. Reaction rates were measured by observing the time dependent decay of signals from reactant and product channels. In addition we measured interaction potentials of the reactants by laser spectroscopy where the laser induced fluorescence or ionization is measured as a function of laser wavelength (excitation spectra) or by measuring fluorescence spectra at fixed laser frequencies with monochromators. The spectra were obtained in the form of either lineshapes or individual lines from rovibrational transitions of bound states. Our research then required several categories of experiments in order to fully understand a reaction process: 1. High resolution laser spectroscopy of bound molecules or lineshapes of colliding pairs is used to determine potential curves for reactants. 2. Direct measurements of state-to-state reaction rates were measured by studying the time dependent loss of excited reactants and the time dependent formation of products. 3. The energy selectivity of a laser can be used to excite reactants on an excited surface with controlled internuclear configurations. For free states of reactants (as exist in a gas cell) this has been termed laser assisted reactions, while for initially bound states (as chemically bound reactants or dimers formed in supersonic beams) the experiments have been termed photo-fragmentation spectroscopy

  11. Blood donations from previously transfused or pregnant donors: a multicenter study to determine the frequency of alloexposure.

    Science.gov (United States)

    Rios, Jorge A; Schlumpf, Karen S; Kakaiya, Ram M; Triulzi, Darrell J; Roback, John D; Kleinman, Steve H; Murphy, Edward L; Gottschall, Jerome L; Carey, Patricia M

    2011-06-01

    Transfusion-related acute lung injury (TRALI) mitigation strategies include the deferral of female donors from apheresis platelet (PLT) donations and the distribution of plasma for transfusion from male donors only. We studied the implications of these policies in terms of component loss at six blood centers in the United States. We collected data from allogeneic blood donors making whole blood and blood component donations during calendar years 2006 through 2008. We analyzed the distribution of donations in terms of the sex, transfusion and pregnancy histories, and blood type. A TRALI mitigation policy that would not allow plasma from female whole blood donors to be prepared into transfusable plasma components would result in nearly a 50% reduction in the units of whole blood available for plasma manufacturing and would decrease the number of type AB plasma units that could be made from whole blood donations by the same amount. Deferral of all female apheresis PLT donors, all female apheresis PLT donors with histories of prior pregnancies, or all female apheresis PLT donors with histories of prior pregnancies and positive screening test results for antibodies to human leukocyte antigens (HLAs) will result in a loss of 37.1, 22.5, and 5.4% of all apheresis PLT donations, respectively. A TRALI mitigation policy that only defers female apheresis PLT donors with previous pregnancies and HLAs would result in an approximately 5% decrease in the inventory of apheresis PLTs, but would eliminate a large proportion of components that are associated with TRALI. © 2010 American Association of Blood Banks.

  12. PCNL - a comparative study in nonoperated and in previously operated (open nephrolithotomy/pyelolithotomy patients - a single-surgeon experience

    Directory of Open Access Journals (Sweden)

    Rahul Gupta

    2011-12-01

    Full Text Available PURPOSE: Re-procedure in patients with history of open stone surgery is usually challenging due to the alteration in the retroperitoneal anatomy. The aim of this study was to determine the possible impact of open renal surgery on the efficacy and morbidity of subsequent percutaneous nephrolithotomy (PCNL. MATERIALS AND METHODS: From March 2009 until September 2010, 120 patients underwent PCNL. Of these, 20 patients were excluded (tubeless or bilateral simultaneous PCNL. Of the remaining 100, 55 primary patients were categorized as Group 1 and the remaining (previous open nephrolithotomy as Group 2. Standard preoperative evaluation was carried out prior to intervention, Statistical analysis was performed using SPSS v. 11 with the chi-square test, independent samples t-test, and Mann-Whitney U test. A p-value < 0.05 was taken as statistically significant. RESULTS: Both groups were similar in demographic profile and stone burden. Attempts to access the PCS was less in Group 1 compared to Group 2 (1.2 + 1 2 vs 3 + 1.3 respectively and this was statistically significant (p < 0.04. However, the mean operative time between the two groups was not statistically significant (p = 0.44. Blood transfusion rate was comparable in the two groups (p = 0.24. One patient in Group 2 developed hemothorax following a supra-11th puncture. Remaining complications were comparable in both groups. CONCLUSION: Patients with past history of renal stone surgery may need more attempts to access the pelvicaliceal system and have difficulty in tract dilation secondary to retroperitoneal scarring. But overall morbidity and efficacy is same in both groups.

  13. Laser damage studies on MgF2 thin films

    International Nuclear Information System (INIS)

    Protopapa, Maria Lucia; De Tomasi, Ferdinando; Perrone, Maria Rita; Piegari, Angela; Masetti, Enrico; Ristau, Detlev; Quesnel, Etienne; Duparre, Angela

    2001-01-01

    The results of laser damage studies performed at 248 nm (KrF excimer laser) on MgF 2 thin films deposited by different techniques (electron-beam evaporation, thermal boat evaporation, and ion-beam sputtering) on fused silica and CaF 2 substrates are presented. We find that the films deposited on CaF 2 substrates by the electron-beam evaporation technique present the highest damage threshold fluence (9 J/cm2). The photoacoustic (PA) beam deflection technique was employed, in addition to microscopical inspection, to determine laser damage fluences. We confirm, by scanning electron microscopy analysis of the damaged spots, the capability of the PA technique to provide information on the mechanisms leading to damage. The dependence of both laser damage fluence and damage morphology on the film deposition technique, as well as on the film substrate, is discussed

  14. Sunburn and sun-protective behaviors among adults with and without previous nonmelanoma skin cancer: a population-based study

    Science.gov (United States)

    Fischer, Alexander H.; Wang, Timothy S.; Yenokyan, Gayane; Kang, Sewon; Chien, Anna L.

    2016-01-01

    Background Individuals with previous nonmelanoma skin cancer (NMSC) are at increased risk for subsequent skin cancer, and should therefore limit UV exposure. Objective To determine whether individuals with previous NMSC engage in better sun protection than those with no skin cancer history. Methods We pooled self-reported data (2005 and 2010 National Health Interview Surveys) from US non-Hispanic white adults (758 with and 34,161 without previous NMSC). We calculated adjusted prevalence odds ratios (aPOR) and 95% confidence intervals (95% CI), taking into account the complex survey design. Results Individuals with previous NMSC versus no history of NMSC had higher rates of frequent use of shade (44.3% versus 27.0%; aPOR=1.41; 1.16–1.71), long sleeves (20.5% versus 7.7%; aPOR=1.55; 1.21–1.98), a wide-brimmed hat (26.1% versus 10.5%; aPOR=1.52; 1.24–1.87), and sunscreen (53.7% versus 33.1%; aPOR=2.11; 95% CI=1.73–2.59), but did not have significantly lower odds of recent sunburn (29.7% versus 40.7%; aPOR=0.95; 0.77–1.17). Among subjects with previous NMSC, recent sunburn was inversely associated with age, sun avoidance, and shade but not sunscreen. Limitations Self-reported cross-sectional data and unavailable information quantifying regular sun exposure. Conclusion Physicians should emphasize sunburn prevention when counseling patients with previous NMSC, especially younger adults, focusing on shade and sun avoidance over sunscreen. PMID:27198078

  15. Study on laser welding of austenitic stainless steel by varying incident angle of pulsed laser beam

    Science.gov (United States)

    Kumar, Nikhil; Mukherjee, Manidipto; Bandyopadhyay, Asish

    2017-09-01

    In the present work, AISI 304 stainless steel sheets are laser welded in butt joint configuration using a robotic control 600 W pulsed Nd:YAG laser system. The objective of the work is of twofold. Firstly, the study aims to find out the effect of incident angle on the weld pool geometry, microstructure and tensile property of the welded joints. Secondly, a set of experiments are conducted, according to response surface design, to investigate the effects of process parameters, namely, incident angle of laser beam, laser power and welding speed, on ultimate tensile strength by developing a second order polynomial equation. Study with three different incident angle of laser beam 89.7 deg, 85.5 deg and 83 deg has been presented in this work. It is observed that the weld pool geometry has been significantly altered with the deviation in incident angle. The weld pool shape at the top surface has been altered from semispherical or nearly spherical shape to tear drop shape with decrease in incident angle. Simultaneously, planer, fine columnar dendritic and coarse columnar dendritic structures have been observed at 89.7 deg, 85.5 deg and 83 deg incident angle respectively. Weld metals with 85.5 deg incident angle has higher fraction of carbide and δ-ferrite precipitation in the austenitic matrix compared to other weld conditions. Hence, weld metal of 85.5 deg incident angle achieved higher micro-hardness of ∼280 HV and tensile strength of 579.26 MPa followed by 89.7 deg and 83 deg incident angle welds. Furthermore, the predicted maximum value of ultimate tensile strength of 580.50 MPa has been achieved for 85.95 deg incident angle using the developed equation where other two optimum parameter settings have been obtained as laser power of 455.52 W and welding speed of 4.95 mm/s. This observation has been satisfactorily validated by three confirmatory tests.

  16. Tattoo removal with the alexandrite laser: a clinical and histologic study

    Science.gov (United States)

    Fitzpatrick, Richard E.; Goldman, Mitchel P.

    1993-07-01

    The incident of tattoos in the United States is estimated to be in the range of 9 to 11% of the adult population. Various studies have shown that of these persons having tattoos, as many as 50 to 80% regret having gotten the tattoo and may desire tattoo removal. Previous treatment modalities have all used methods which require tissue destruction in order to remove the tattoo ink. The primary problems with use of these modalities has been the unpredictability of scarring. Also, residual tattoo pigment remaining after completion of the treatment process has been a problem. In response to these problems, the Q-switched lasers have been developed which target the tattoo pigments specifically rather than the tissue containing the tattoo pigment. The alexandrite laser (made by Candela Laser Corporation) has a wavelength of 755 nm and a pulse width of 100 nsec plus or minus 10 nsec. Reflectance studies have indicated that black, blue and green ink should absorb this wavelength relatively well, while red ink would not be expected to absorb this wavelength well. The mechanism of action of this laser is selective absorption of the laser energy by the tattoo pigment resulting in fragmentation of the pigment and then engulfment by tissue macrophages which remove the fragmented tattoo pigment. Preliminary studies using a Yucatan mini pig confirmed these expectations with black ink being easier to remove than blue and green, and red ink being minimally responsive. Higher fluences were more effective.

  17. SOLASE conceptual laser fusion reactor study

    International Nuclear Information System (INIS)

    Moses, G.A.; Conn, R.W.; Abdel-Khalik, S.I.; Cooper, G.W.; Howard, J.; Magelssen, G.R.

    1978-01-01

    A conceptual laser fusion reactor for electric power, SOLASE, has been designed. The SOLASE design utilizes a 1 MJ, 6.7% efficient laser to implode 20 fusion targets per second. The target gain is 150 and produces a net electrical power of 1000 MW. The reactor cavity is spherical with a 6 m radius. The first wall is graphite and has a neutron wall loading of 5 MW/m 2 . It is protected from the target debris by low pressure xenon gas that is introduced into the cavity. The blanket structure is a honeycombed graphite composite. The tritium breeding and heat transport medium is Li 2 O in the form of pellets that flow through the blanket. The tritium breeding ration is 1.34. Temperature decoupling of the graphite structure and the Li 2 O coolant enables the structure to operate at temperatures that minimize radiation damage effects. The graphite blanket is replaced every year but exhibits low levels of radioactivity so that limited hands on maintenance is possible two weeks after shutdown, thus facilitating rapid replacement

  18. Laparoscopy After Previous Laparotomy

    Directory of Open Access Journals (Sweden)

    Zulfo Godinjak

    2006-11-01

    Full Text Available Following the abdominal surgery, extensive adhesions often occur and they can cause difficulties during laparoscopic operations. However, previous laparotomy is not considered to be a contraindication for laparoscopy. The aim of this study is to present that an insertion of Veres needle in the region of umbilicus is a safe method for creating a pneumoperitoneum for laparoscopic operations after previous laparotomy. In the last three years, we have performed 144 laparoscopic operations in patients that previously underwent one or two laparotomies. Pathology of digestive system, genital organs, Cesarean Section or abdominal war injuries were the most common causes of previouslaparotomy. During those operations or during entering into abdominal cavity we have not experienced any complications, while in 7 patients we performed conversion to laparotomy following the diagnostic laparoscopy. In all patients an insertion of Veres needle and trocar insertion in the umbilical region was performed, namely a technique of closed laparoscopy. Not even in one patient adhesions in the region of umbilicus were found, and no abdominal organs were injured.

  19. Studies of bandwidth dependence of laser plasma instabilities driven by the Nike laser

    Science.gov (United States)

    Weaver, J.; Kehne, D.; Obenschain, S.; Serlin, V.; Schmitt, A. J.; Oh, J.; Lehmberg, R. H.; Brown, C. M.; Seely, J.; Feldman, U.

    2012-10-01

    Experiments at the Nike laser facility of the Naval Research Laboratory are exploring the influence of laser bandwidth on laser plasma instabilities (LPI) driven by a deep ultraviolet pump (248 nm) that incorporates beam smoothing by induced spatial incoherence (ISI). In early ISI studies with longer wavelength Nd:glass lasers (1054 nm and 527 nm),footnotetextObenschain, PRL 62(1989);Mostovych, PRL 62(1987);Peyser, Phys. Fluids B 3(1991). stimulated Raman scattering, stimulated Brillouin scattering, and the two plasmon decay instability were reduced when wide bandwidth ISI (δν/ν˜0.03-0.19%) pulses irradiated targets at moderate to high intensities (10^14-10^15 W/cm^2). The current studies will compare the emission signatures of LPI from planar CH targets during Nike operation at large bandwidth (δν˜1THz) to observations for narrower bandwidth operation (δν˜0.1-0.3THz). These studies will help clarify the relative importance of the short wavelength and wide bandwidth to the increased LPI intensity thresholds observed at Nike. New pulse shapes are being used to generate plasmas with larger electron density scale-lengths that are closer to conditions during pellet implosions for direct drive inertial confinement fusion.

  20. NATO Advanced Study Institute on Physics of New Laser Sources

    CERN Document Server

    Arecchi, F; Mooradian, Aram; Sona, Alberto

    1985-01-01

    This volume contains the lectures and seminars presented at the NATO Advanced Study Institute on "Physics of New Laser Sources", the twelfth course of the Europhysics School of Quantum Electronics, held under the supervision of the Quantum Electronics Division of the European Physical Society. The Institute was held at Centro "I Cappuccini" San Miniato, Tuscany, July 11-21, 1984. The Europhysics School of Quantum Electronics was started in 1970 with the aim of providing instruction for young researchers and advanced students already engaged in the area of quantum electronics or for those wishing to switch into this area after working previously in other areas. From the outset, the School has been under the direction of Prof. F. T. Arecchi, then at the University of Pavia, now at the University of Florence, and Dr. D. Roess of Heraeus, Hanau. In 1981, Prof. H. Walther, University of Munich and Max-Planck Institut fur Quantenoptik joined as co-director. Each year the Directors choose a subj~ct of particular int...

  1. Study of the mechanisms of matrix assisted laser desorption / ionization

    International Nuclear Information System (INIS)

    Manuelli, Pascal

    1995-01-01

    This research thesis aims at a better knowledge of some aspects of a complex mechanism: the matrix-assisted laser desorption/ionization (MALDI). The author first proposes a comparative analysis of results obtained by time-of-flight (TOF) mass spectrometry and by Fourier transform mass spectrometry. He reports the study of the matrix role (notably a polymeric matrix) as a matter submitted to laser desorption. In this respect, the influence of the incident wavelength has been studied. The author also reports a comparative of ions produced by matrix laser desorption (study performed by Fourier transform mass spectrometry) and of neutral molecules (study performed by flash pyrolysis coupled with gas chromatography and with mass spectrometry). Finally, results obtained on derivatives and complexes based on beta-cyclodextrins highlight benefits as well as limitations of this technique [fr

  2. Radioimmunotherapy with Y-90-epratuzumab in patients with previously treated B-cell lymphoma. A fractionated dose-escalation study

    International Nuclear Information System (INIS)

    Linden, O.; Cavallin-Stahl, E.; Tennvall, J.; Hindorf, C.; Olsson, T.; Strand, S.E.; Stenberg, L.; Wingardh, K.

    2002-01-01

    Aim: Fractionated RIT may improve outcome by decreasing heterogeneity in absorbed dose and by increasing therapeutic window. The humanised anti-CD22 antibody, Epratuzumab, (Immunomedics, Inc., Morris Plains, NJ) can be given repeatedly with minimal risk of neutralising Ab (HAHA), making fractionated treatment with 90 Y-labelled epratuzumab possible. Materials and Methods: Patients with previously treated B-cell lymphoma received increasing number (2-4) of weekly infusions of 90 Y-epratuzumab. Patients received either 185 MBq/m 2 per infusion (group A), or, if they had a history of high-dose chemotherapy with stem-cell rescue, 92.5 MBq/m 2 per infusion (group B). The first infusion included 150 MBq of 111 Indium for scintigraphic verification of tumour targeting and dosimetry. 1.5 mg/kg epratuzumab was administered with each infusion. The treatment could be repeated once after 3 m. Results: Of 23 patients, 16 in group A and 6 in group B were evaluable for response. The RR in group A was 62% objective response (OR) and 25% CR/CRu. One patient in group B showed OR. OR was seen in aggressive and indolent lymphoma. Response was also long-lasting and event-free survival of patients showing CR/CRu was 14 to 25+ months. In group A all seven patient, receiving three infusions, showed less than grade 3 platelet and neutrophil toxicity, except for two patients suffering grade 3 neutropenia. Of five patients with 4 weekly infusions there were two patients with dose-limiting haematological toxicity (DLT), both recently treated with high dose cytosar before RIT. With criteria used the maximal tolerated dose was three infusions 185 MBq/m 2 . In group B no patient suffered DLT and one patient exhibited OR. Seven patients were retreated after 3 months with minor toxicity, but improvement in OR in two cases. No patient has developed HAHA. CD22 expression on tumour cells, as assessed by flow cytometry, is available in 18 of 22 patients. In group A, seven of eight patients with

  3. He-Ne laser effects on blood microcirculation. An in vivo study through laser doppler flowmetry

    International Nuclear Information System (INIS)

    Nunez, Silvia Cristina

    2002-01-01

    Blood microcirculation performs an important function in tissue repair process, as well as in pain control, allowing for greater oxygenation of the tissues and the accelerated expulsion of metabolic products, that may be contributing to pain. Low Intensity Laser Therapy (LILT) is widely used to promote healing, and there is an assumption that it is mechanism of action may be due to an enhancement of blood supply. The purpose of this study was to evaluate, using laser Doppler flowmetry (LDF), the stated effects caused by radiation emitted by a He-Ne laser (λ=632.8 nm) on blood microcirculation during tissue repair. To this end, 15 male mice were selected and received a liquid nitrogen provoked lesion, above the dorsal region, and blood flow was measured periodically, during 21 days. Due to radiation emission by the LDF equipment, a control group was established to evaluate possible effects caused by this radiation on microcirculation. To evaluate the He-Ne laser effects, a 1.15 J/cm 2 dose was utilized, with an intensity of 6 mW/cm 2 . The results obtained demonstrate flow alterations, provoked by the lesion, and subsequent inflammatory response. There was no statistical difference between the studied groups. As per the analysis of the results there is no immediate effect due the radiation emitted by a He Ne laser on microcirculation, although a percentage increase was observed in day 7 on medium blood flow rate in irradiated specimens. New studies are necessary to validate the use of this wavelength, in order to promote beneficial alterations in blood supply in radiated areas. (author)

  4. Preliminary cutting and drilling studies using new generation lasers

    International Nuclear Information System (INIS)

    Kautz, D.D.; Sze, J.S.; Dragon, E.P.; Hargrove, R.S.

    1992-01-01

    High power and radiance dye lasers developed at Lawrence Livermore National Laboratory show promise for material processing tanks. Evaluation using welding heat flow models suggest significant increases in precision and speed are expected. We developed tooling and instrumentation to diagnose important parameters including spot geometry and optical train quality. We started processing studies to determine the viability of these lasers of cutting and drilling. We used titanium alloys first in the studies due to the availability of comparable parametric studies in the technical literature. Results show that cuts and holes with extremely fine features can be made with dye lasers. The high radiance beam produces low distortion and small heat-affected zones. We have accomplished very high aspect ratios and micron scale kerfs and holes. Through continued system improvement and process optimization, we believe that submicron levels will be achieved

  5. Infrared laser sealing of porcine vascular tissues using a 1,470 nm diode laser: Preliminary in vivo studies.

    Science.gov (United States)

    Cilip, Christopher M; Kerr, Duane; Latimer, Cassandra A; Rosenbury, Sarah B; Giglio, Nicholas C; Hutchens, Thomas C; Nau, William H; Fried, Nathaniel M

    2017-04-01

    Infrared (IR) lasers are being explored as an alternative to radiofrequency (RF) and ultrasonic (US) devices for rapid hemostasis with minimal collateral zones of thermal damage and tissue necrosis. Previously, a 1,470 nm IR laser sealed and cut ex vivo porcine renal arteries of 1-8 mm diameter in 2 seconds, yielding burst pressures greater than 1,200 mmHg and thermal coagulation zones less than 3 mm. This preliminary study describes in vivo testing of a handheld laser probe in a porcine model. A handheld prototype with vessel/tissue clasping mechanism was tested on 73 blood vessels less than 6 mm diameter using 1,470 nm laser power of 35 W for 1-5 seconds. Device power settings, irradiation time, tissue type, vessel diameter, and histology sample number were recorded for each procedure. The probe was evaluated for hemostasis after sealing isolated and bundled arteriole/venous (A/V) vasculature of porcine abdomen and hind leg. Sealed vessel samples were collected for histological analysis of lateral thermal damage. Hemostasis was achieved in 57 of 73 seals (78%). The probe consistently sealed vasculature in small bowel mesentery, mesometrium, and gastrosplenic and epiploic regions. Seal performance was less consistent on hind leg vasculature including saphenous arteries/bundles and femoral and iliac arteries. Collagen denaturation averaged 1.6 ± 0.9 mm in eight samples excised for histologic examination. A handheld laser probe sealed porcine vessels, in vivo. Further probe development and laser parameter optimization is necessary before infrared lasers may be evaluated as an alternative to RF and US vessel sealing devices. Lasers Surg. Med. 49:366-371, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  6. Prospective study on laser-assisted laparascopic partial nephrectomy

    Science.gov (United States)

    Sroka, Ronald; Hennig, Georg; Zilinberg, Katja; Khoder, Wael Y.

    2012-02-01

    rinsing. Conclusion: This prospective in-vivo feasibility study shows that laser assisted partial nephrectomy seems to be a safe and promising medical technique which could be provided either during open surgery as well as laparascopically. This application showed good haemostasis and minimal parenchymal damage. Further investigations and development are needed for on-line detection of the remain coagulation margin. An optimised treatment equipment will support the applicability of laser assisted laparoscopic partial nephrectomy.

  7. Studies on mechanisms of the laser particle acceleration; Untersuchungen zu Mechanismen der Laser-Teilchenbeschleunigung

    Energy Technology Data Exchange (ETDEWEB)

    Aurand, Bastian

    2012-06-20

    Within the last decade, many developments towards higher energies and particle numbers paved the way of particle acceleration performed by high intensity laser systems. Up to now, the process of a field-induced acceleration process (Target-Normal-Sheath-Acceleration (TNSA)) is investigated the most. Acceleration occurs as a consequence of separation of charges on a surface potential. Here, the broad energy spectrum is a problem not yet overcome although many improvements were achieved. Calculations for intensities higher than 10{sup 20..21} W/cm{sup 2} give hint that Radiation-Pressure-Acceleration (RPA) may lead to a sharper, monoenergetic energy spectrum. Within the framework of this thesis, the investigation of the acceleration mechanism is studied experimentally in the intensity range of 10{sup 19} W/cm{sup 2}. Suitable targets were developed and applied for patent. A broad range of parameters was scanned by means of high repetition rates together with an adequate laser system to provide high statistics of several thousands of shots, and the dependence of target material, intensity, laser polarisation and pre plasma-conditions was verified. Comparisons with 2-d numeric simulations lead to a model of the acceleration process which was analyzed by several diagnostic methods, giving clear evidence for a new, not field-induced acceleration process. In addition, a system for a continuous variation of the polarization based on reflective optics was developed in order to overcome the disadvantages of retardation plates, and their practicability of high laser energies can be achieved.

  8. Feasibility Study of Laser Cutting for Fabrication of Tensile Specimen

    International Nuclear Information System (INIS)

    Jin, Y. G.; Baik, S. J.; Kim, G. S.; Heo, G. S.; Yoo, B. O.; Ahn, S. B.; Chun, Y. B.

    2015-01-01

    The specimen fabrication technique was established to machine the specimen from the irradiated materials. The wire cut EDM(electric discharge machine) was modified to fabricate the mechanical testing specimens from irradiated components and fuel claddings. The oxide layer removal system was also developed because the oxide layer on the surface of the irradiated components and claddings interrupted the applying the electric current during the processing. However, zirconium oxide is protective against further corrosion as well as beneficial to mechanical strength for the tensile deformation of the cladding. Thus, it is important to fabricate the irradiated specimens without removal of oxide layer on the surface of the irradiated structural components and claddings. In the present study, laser cutting system was introduced to fabricate the various mechanical testing specimens from the unirradiated fuel cladding and the feasibility of the laser cutting system was studied for the fabrication of various types of irradiated specimens in a hot cell at IMEF (Irradiated Materials Examination Facility) of KAERI. Laser beam machining system was introduced to fabricate the various mechanical testing specimens from the unirradiated fuel cladding and the dimensions were compared for the feasibility of the laser cutting system. The effect of surface oxide layer was also investigated for machining process of the zircaloy-4 fuel cladding and it was found that laser beam machining could be a useful tool to fabricate the specimens with surface oxide layer

  9. Feasibility Study of Laser Cutting for Fabrication of Tensile Specimen

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Y. G.; Baik, S. J.; Kim, G. S.; Heo, G. S.; Yoo, B. O.; Ahn, S. B.; Chun, Y. B. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    The specimen fabrication technique was established to machine the specimen from the irradiated materials. The wire cut EDM(electric discharge machine) was modified to fabricate the mechanical testing specimens from irradiated components and fuel claddings. The oxide layer removal system was also developed because the oxide layer on the surface of the irradiated components and claddings interrupted the applying the electric current during the processing. However, zirconium oxide is protective against further corrosion as well as beneficial to mechanical strength for the tensile deformation of the cladding. Thus, it is important to fabricate the irradiated specimens without removal of oxide layer on the surface of the irradiated structural components and claddings. In the present study, laser cutting system was introduced to fabricate the various mechanical testing specimens from the unirradiated fuel cladding and the feasibility of the laser cutting system was studied for the fabrication of various types of irradiated specimens in a hot cell at IMEF (Irradiated Materials Examination Facility) of KAERI. Laser beam machining system was introduced to fabricate the various mechanical testing specimens from the unirradiated fuel cladding and the dimensions were compared for the feasibility of the laser cutting system. The effect of surface oxide layer was also investigated for machining process of the zircaloy-4 fuel cladding and it was found that laser beam machining could be a useful tool to fabricate the specimens with surface oxide layer.

  10. Laser Correction of Delayed Posthypoxic Encephalopathies (Experimental Study

    Directory of Open Access Journals (Sweden)

    V. V. Moroz

    2009-01-01

    Full Text Available Objective: to study whether posthypoxic brain dysfunctions may be corrected by low-intensity laser irradiation an hour after hypovolemic hypotension at late postresuscitation stages (following 30 days. Material and methods. Experiments were carried out on high-anxious male albino rats weighing 280—300 g. The study model was one-hour hypovolemic hypotension (blood pressure 40 mm Hg, followed by blood reinfusion. The integrative brain function was evaluated from the indices of the rat orientative-trying behavior in the elevated cross labyrinth test. The depressive component of the rats’ behavior was examined in the forced swimming test. Plasma norepinephrine levels were measured. Laser irradiation was performed 30 days after blood reinfusion. Results. Laser irradiation used at late postresuscitation stages leads to the normalization of plasma norepinephrine levels, the reduction of anxiety in the rats, and their improved orientative-trying behavior. Conclusion. The positive impact of laser irradiation on the rat orientative-trying behavior is associated with its anxiolytic effect, in which the recovery of autonomic homeostasis plays a considerable role. Key words: blood loss, postresuscitative period, behavior, laser, posthypoxic encephalopathy, norepinephrine.

  11. Cutting and drilling studies using high power visible lasers

    International Nuclear Information System (INIS)

    Kautz, D.D.; Dragon, E.P.; Werve, M.E.; Hargrove, R.S.; Warner, B.E.

    1993-01-01

    High power and radiance laser technologies developed at Lawrence Livermore National Laboratory such as copper-vapor and dye lasers show great promise for material processing tasks. Evaluation of models suggests significant increases in welding, cutting, and drilling capabilities, as well as applications in emerging technologies such as micromachining, surface treatment, and stereolithography. Copper lasers currently operate at 1.8 kW output at approximately three times the diffraction limit and achieve mean time between failures of more than 1,000 hours. Dye lasers have near diffraction limited beam quality at greater than 1.0 kW. Results from cutting and drilling studies in titanium and stainless steel alloys show that cuts and holes with extremely fine features can be made with dye and copper-vapor lasers. High radiance beams produce low distortion and small heat-affected zones. The authors have accomplished very high aspect ratios (> 60:1) and features with micron scale (5-50 μm) sizes. The paper gives a description of the equipment; discusses cutting theory; and gives experimental results of cutting and drilling studies on Ti-6Al-4V and 304 stainless steel

  12. A study of particle generation during laser ablation with applications

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chunyi [Univ. of California, Berkeley, CA (United States)

    2005-01-01

    A study has been made of the generation of particles during laser ablation and has included size distribution measurements and observation of the formation processes. The particle size distribution with respect to different laser parameters was obtained in-line using a differential mobility analyzer (DMA) and a particle counter. The experimental results show that the particle size varies with laser energy, laser pulsewidth, ambient gas flow rate and sample properties. The results serve as a basis for controlling the size of nanoparticles generated by laser ablation. Laser shadowgraph imaging was used to study mass ejection processes and mechanisms. At higher laser irradiance, some particles were ejected in the liquid and even in the solid phase. Time-resolved images show the propagation of the shockwaves: external shockwaves propagate outward and decelerate, and internal shockwaves reflect back and forth between the gas contact surface and the sample surface. The internal shockwave is proposed to cause the ejection of liquid particles when the internal shockwave strikes the liquid molten layer. A simulation based on vapor plume expansion was carried out and provides satisfactory agreement with experimental results. Different material properties result in different particle ejection behavior:particle ejection for most materials including metals result in a conically shaped envelope for the ejected material while ejection for silicon resembles a liquid jet. The difference in density change when the materials melt was proposed to be an important factor in the different ejection behavior. The characteristics of particles generated by laser ablation have a strong influence on the chemical analysis of the irradiated sample. Large particles are more difficult to completely vaporize and ionize, and induced preferential vaporization causes fractionation (i.e. a detected chemical composition that differs from the sample material). Large particles also result in spikes in

  13. Nuclear fuel safety studies by laser pulse heating

    International Nuclear Information System (INIS)

    Viswanadham, C.S.; Kumar, Santosh; Dey, G.K.; Kutty, T.R.G.; Khan, K.B.; Kumar, Arun; Jathar, V.P.; Sahoo, K.C.

    2009-01-01

    The behaviour of nuclear fuels under transient heating conditions is vital to nuclear safety. A laser pulse based heating system to simulate the transient heating conditions experienced by the fuel during reactor accidents like LOCA and RIA is under development at BARC, Mumbai. Some of the concepts used in this system are under testing in pilot studies. This paper describes the results of some pilot studies carried out on unirradiated UO 2 specimens by laser pulse heating, followed by metallography and X-ray diffraction measurements. (author)

  14. GAP WIDTH STUDY IN LASER BUTT-WELDING

    DEFF Research Database (Denmark)

    Gong, Hui; Olsen, Flemming Ove

    power : 2 and 2.6 kW and the focal point position : 0 and -1.2 mm. Quality of all the butt welds are destructively tested according to ISO 13919-1.Influences of the variable process parameters to the maximum allowable gap width are observed as (1) the maximum gap width is inversely related......In this paper the maximum allowable gap width in laser butt-welding is intensively studied. The gap width study (GWS) is performed on the material of SST of W1.4401 (AISI 316) under various welding conditions, which are the gap width : 0.00-0.50 mm, the welding speed : 0.5-2.0 m/min, the laser...... to the welding speed, (2) the larger laser power leads to the bigger maximum allowable gap width and (3) the focal point position has very little influence on the maximum gap width....

  15. Study of multicharged ions in the laser-produced plasmas

    International Nuclear Information System (INIS)

    Jaegle, P.; Carillon, A.; Jamelot, G.; Wehenkel, C.; Sureau, A.; Guennou, H.

    1980-01-01

    With respect to hot plasmas, laser induced plasmas have an especially high density, with a steep partial gradient and a fast temporal variation of temperature and density. The study of multicharged ion radiation, wich is necessary to perform diagnostics of plasma parameters, opens a new field for atomic physics investigations, including identification of peculiar lines, which are not observed in other conditions, large changes in line profiles due to radiative transfer and to both shift and broadening by Stark effect. Departure from population equilibrium takes place in these plasmas, going possibly so far as population inversion between ionic levels in an energy range covering EUV and soft X-rays. Experimental and theoretical study of these phenomena are in progress and needs to find solutions for complicated problems. Here, recent works performed with the laser of the GRECO 'Interaction Laser-Matiere' are briefly presented [fr

  16. Caries like lesion initiation in sound enamel following CW CO2 laser irradiation: an in vitro study

    International Nuclear Information System (INIS)

    Nafie, A.; Issam, A.; Ali, M. S. R.

    2005-01-01

    This Study aimed to asses the caries - preventive potential of various CW CO 2 laser parameters, and to explore the effect of the laser power density, and the exposure time on the varies inhibition activity. Materials and Methods: Extracted human premolar teeth were irradiated with three different power densities (7.95, 15.9 and 31.8) W/Cm 2 for three different exposure times (0.2, 0.4 and 0.8) sec of 10.6 μm CW CO 2 laser. All teeth were subjected to caries like lesion formation by 3.5 pH lactic acid for 21 days. The teeth after that were sectioned into ground cross section and the lesion depths were measured using a graticule polarizing microscope. CW CO 2 laser preventive treatments inhibit caries like lesion progression up to 44%. This effect was improved with: (1) Increased power density for each of the three exposure times. (2) Decreased exposure time for each of the three power densities within the limits of the previously listed laser parameters. Conclusion: (1) short exposure time of CW CO 2 laser results in a significant inhibition of the enamel caries like lesion formation. (2) The inhibitory effect depends upon the power density and the exposure time of the laser beam. (3) The optimal CW CO 2 laser parameters used for caries inhibition purpose is achieved with approximately 30 W/Cm 2 power density and 0.2 sec exposure time. (author)

  17. Studies of the confinement at laser-induced backside dry etching using infrared nanosecond laser pulses

    Science.gov (United States)

    Ehrhardt, M.; Lorenz, P.; Bayer, L.; Han, B.; Zimmer, K.

    2018-01-01

    In the present study, laser-induced backside etching of SiO2 at an interface to an organic material using laser pulses with a wavelength of λ = 1064 nm and a pulse length of τ = 7 ns have been performed in order to investigate selected processes involved in etching of the SiO2 at confined ablation conditions with wavelengths well below the band gap of SiO2. Therefore, in between the utilized metallic absorber layer and the SiO2 surface, a polymer interlayer with a thickness between 20 nm to 150 nm was placed with the aim, to separate the laser absorption process in the metallic absorber layer from the etching process of the SiO2 surface due to the provided organic interlayer. The influence of the confinement of the backside etching process was analyzed by the deposition of different thick polymer layers on top of the metallic absorber layer. In particular, it was found that the SiO2 etching depth decreases with higher polymer interlayer thickness. However, the etching depth increases with increasing the confinement layer thickness. SEM images of the laser processed areas show that the absorber and confinement layers are ruptured from the sample surface without showing melting, and suggesting a lift off process of these films. The driving force for the layers lift off and the etching of the SiO2 is probably the generated laser-induce plasma from the confined ablation that provides the pressure for lift off, the high temperatures and reactive organic species that can chemically attack the SiO2 surface at these conditions.

  18. Laser study of phase changes in the surface layer of porous materials

    International Nuclear Information System (INIS)

    Wojtatowicz, T W

    2001-01-01

    The paper presents some aspects of the use of interference patterns observed upon reflection of laser radiation from the surface of a porous solid (laser speckles) for the study of moisture condensation in the near-surface layer. (interaction of laser radiation with matter. laser plasma)

  19. The study on laser photochemical process of Diazonaphthoquinon-Cresol system

    International Nuclear Information System (INIS)

    Wei Jie; Huang Yu Li; Wang Wenke

    1999-01-01

    The kinetic process of laser photochemical reaction of diazonaphthoquinon-cresol system was studied by using laser spectrophotofluorimetry and laser induced fluorescence attenuation method. The nonlinear relationship between photodecomposition rate of the sensitizer and laser power, exposure time and concentration of solutions was discussed in detail

  20. Study of laser bending of a preloaded Titanium alloy sheet

    Directory of Open Access Journals (Sweden)

    Wang Xiufeng

    2014-01-01

    Full Text Available Laser bending of sheet metals with preload offers some attractive characteristics/merits, comparing to laser free bending without prestressing on the metals. The study reported in this paper was focused on a Titanium alloy which finds widespread applications in aerospace manufacturing. FE simulation of laser bending with prestressing on the Titanium alloy sheet was conducted for the analysis of the bending process and experiment carried out to verify the model and the result. It was shown that the simulation result is close to that measured in the experiment. Based on the computed result, the load-displacement curve was analysed and transmission efficiency of the elastic energy defined to evaluate the bending effect. These enhanced understanding of the mechanism of laser bending with a preload. A method for the optimization on technological parameters was further proposed. Referring to the deformation targeted, the preload value was determined through the FE simulation. The result showed that, on the premise that the specimen surface can be prevented from damaging, transmission efficiency of the elastic energy could reach to the maximum value through adjusting technological parameters of the laser system and deformation accuracy of the specimen could also be improved through this approach. The work presented in this paper may find its application in the manufacture of Titanium alloy sheets with a more cost-effective and a more precise way.

  1. Studies on widely tunable ultra-short laser pulses using energy transfer distributed feedback dye laser

    International Nuclear Information System (INIS)

    Ahamed, M.B.; Ramalingam, A.; Palanisamy, P.K.

    2003-01-01

    This paper presents both theoretical and experimental study of the characteristics of Nd: YAG laser pumped energy transfer distributed feedback dye laser (ETDFDL). Using theoretical model proposed, the behavior of ETDFDL such as the characteristics of donor DFDL, the acceptor DFDL, the dependence of their pulse width and output power on donor-acceptor concentrations and pump power are studied for dye mixture Rhodamine 6G and Cresyl Violet in detail. Experimentally using prism-dye cell configuration, the ETDFDL output is obtained and the output energy of DFDL is measured at the emission peaks of donor and acceptor dyes for different pump powers and donor-acceptor concentrations. In addition, the DFDL linewidth measurement has been carried out at the lasing wavelengths of the donor and acceptor dyes using Fabry-Perot etalon and the tunability of DFDL is measured to be in the wavelength range of 545-680 nm

  2. Studying the mechanism of micromachining by short pulsed laser

    Science.gov (United States)

    Gadag, Shiva

    economical, because the micromachining rates are much higher than in the case of the ultra-short pulsed lasers. Hence, studying the mechanisms of micromachining by nanosecond pulsed laser of semiconductor silicon, transparent dielectric glass and quartz is undertaken for this research work. Laser drilling of an array of miniaturized micro holes is termed as laser micro via. A study of the effect of laser wavelengths, frequency, and energy of the pulses on the depth and diameter of craters and micro via are carried out using high resolution optical microscopy and a nano via 3D profiler. Analytical equations correlating depth and volume of the crater in terms of the optical absorption coefficient and ratio of peak applied to the threshold fluence for ablation of the silicon are derived. The depth of crater is scaled in terms of optical penetration depth times the ratio of crater diameter to the beam diameter. The shorter UV wavelengths are found to be more suitable for ablation of Si and SiO2 than longer IR wavelengths from the study of the absorption coefficient of Si varying with wavelength. Hence, the UV lasers (266 nm or 355 nm) are used for micromachining of Si and SiO2 involving cutting, cleaning, drilling and dicing, micro-milling and texturing of submicron size vertically oriented silicon wires for photovoltaic applications. The high density vertical wires are useful to grab a greater density of solar energy to generate more environmentally-friendly green power. The laser drilling of micro via can be typically of two types: (1) percussion drilling using a stationary laser beam with single or multiple pulses of the laser or (2) trepanned drilling of micro via by the circular motion of laser. Numerical simulation of dynamic drilling of laser micro via of silicon is performed, using control volume (FV) Fluent code in a Cartesian co-ordinate system. Total enthalpy formulation is used to simulate the phase change taking place during the laser ablation process from melting

  3. Performance of a high repetition pulse rate laser system for in-gas-jet laser ionization studies with the Leuven laser ion source LISOL

    International Nuclear Information System (INIS)

    Ferrer, R.; Sonnenschein, V.T.; Bastin, B.; Franchoo, S.; Huyse, M.; Kudryavtsev, Yu.; Kron, T.; Lecesne, N.; Moore, I.D.; Osmond, B.; Pauwels, D.; Radulov, D.; Raeder, S.; Rens, L.

    2012-01-01

    The laser ionization efficiency of the Leuven gas cell-based laser ion source was investigated under on- and off-line conditions using two distinctly different laser setups: a low-repetition rate dye laser system and a high-repetition rate Ti:sapphire laser system. A systematic study of the ion signal dependence on repetition rate and laser pulse energy was performed in off-line tests using stable cobalt and copper isotopes. These studies also included in-gas-jet laser spectroscopy measurements on the hyperfine structure of 63 Cu. A final run under on-line conditions in which the radioactive isotope 59 Cu (T 1/2 = 81.5 s) was produced, showed a comparable yield of the two laser systems for in-gas-cell ionization. However, a significantly improved time overlap by using the high-repetition rate laser system for in-gas-jet ionization was demonstrated by an increase of the overall duty cycle, and at the same time, pointed to the need for a better shaped atomic jet to reach higher ionization efficiencies.

  4. In vitro studies with a pulsed neodymium/YAG laser.

    Science.gov (United States)

    Venkatesh, S; Guthrie, S; Foulds, W S; Lee, W R; Cruickshank, F R; Bailey, R T

    1985-02-01

    The relationships between the destructive effects of Q-switched Nd/YAG laser pulses and a number of experimental parameters were studied for various target materials including in particular excised, fixed samples of human trabecular meshwork. The laser parameters altered were the pulse energy, the convergence angle of the focused beam, and the position of the focus of the beam relative to the target's axial position. The main finding was that it was possible to make deep holes, of a diameter less than 100 micron, in virtually transparent samples of trabecular meshwork with a laser delivery system of 6 degrees convergence and pulse energies of 14 mJ or more. The relevance of this and the other experimental results to the development of a reliable system for performing internal trabeculotomies for the treatment of open-angle glaucoma is presented.

  5. Bibliographic study of photophysical and photochemical properties of laser dyes

    International Nuclear Information System (INIS)

    Doizi, D.

    1986-06-01

    Laser isotope separation of uranium requires high power and precise wave length. This report is a bibliographic and experimental study of the photophysical and photochemical properties of seven commercial laser dyes which have an emission wavelength in the range 5500-6500 A: Rhodamine 110 or 560, rhodamine 6G or 590, rhodamine B or 610, rhodamine 101 or 640, sulforhodamine B or kiton red 620, sulforhodamine 101 or 640 and DCM or LC 6500. Absorption and emission cross section values, fluorescence lifetimes and quantum yields in various solvents are indicated. For each dye, a non exhaustive list of laboratory experiments made with two types of pump sources: Nd YAG (532) and copper vapor laser is given. When it is known, the toxicity of the dyes is mentioned [fr

  6. Laser fusion systems design study. Final technical report

    International Nuclear Information System (INIS)

    1975-06-01

    This study investigated: (1) the formulation and evaluation of an alignment system to accomplish pointing, focusing, centering and translation for the 20-arm SHIVA laser, (2) the formulation and evaluation of concepts for the correction of static phase distortions introduced by the accumulated optical elements in the laser chains, (3) the formulation and evaluation of concepts for the correction of optical path length differences between the arms of the SHIVA system, and (4) the conceptual design of appropriate control system hardware. (U.S.)

  7. A case study of IMRT planning (Plan B) subsequent to a previously treated IMRT plan (Plan A)

    International Nuclear Information System (INIS)

    2Department of Radiation Oncology, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada))" data-affiliation=" (Department of Medical Physics and 2Department of Radiation Oncology, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada))" >Cao, F; 2Department of Radiation Oncology, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada))" data-affiliation=" (Department of Medical Physics and 2Department of Radiation Oncology, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada))" >Leong, C; 2Department of Radiation Oncology, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada))" data-affiliation=" (Department of Medical Physics and 2Department of Radiation Oncology, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada))" >Schroeder, J; 2Department of Radiation Oncology, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada))" data-affiliation=" (Department of Medical Physics and 2Department of Radiation Oncology, Fraser Valley Centre, BC Cancer Agency, Surrey, British Columbia (Canada))" >Lee, B

    2014-01-01

    Background and purpose: Treatment of the contralateral neck after previous ipsilateral intensity modulated radiation therapy (IMRT) for head and neck cancer is a challenging problem. We have developed a technique that limits the cumulative dose to the spinal cord and brainstem while maximizing coverage of a planning target volume (PTV) in the contralateral neck. Our case involves a patient with right tonsil carcinoma who was given ipsilateral IMRT with 70Gy in 35 fractions (Plan A). A left neck recurrence was detected 14 months later. The patient underwent a neck dissection followed by postoperative left neck radiation to a dose of 66 Gy in 33 fractions (Plan B). Materials and Methods: The spinal cord-brainstem margin (SCBM) was defined as the spinal cord and brainstem with a 1.0 cm margin. Plan A was recalculated on the postoperative CT scan but the fluence outside of SCBM was deleted. A further modification of Plan A resulted in a base plan that was summed with Plan B to evaluate the cumulative dose received by the spinal cord and brainstem. Plan B alone was used to evaluate for coverage of the contralateral neck PTV. Results: The maximum cumulative doses to the spinal cord with 0.5cm margin and brainstem with 0.5cm margin were 51.96 Gy and 45.60 Gy respectively. For Plan B, 100% of the prescribed dose covered 95% of PTVb1. Conclusion: The use of a modified ipsilateral IMRT plan as a base plan is an effective way to limit the cumulative dose to the spinal cord and brainstem while enabling coverage of a PTV in the contralateral neck.

  8. Evaluation of a rapid dipstick (Crystal VC for the diagnosis of cholera in Zanzibar and a comparison with previous studies.

    Directory of Open Access Journals (Sweden)

    Benedikt Ley

    Full Text Available The gold standard for the diagnosis of cholera is stool culture, but this requires laboratory facilities and takes at least 24 hours. A rapid diagnostic test (RDT that can be used by minimally trained staff at treatment centers could potentially improve the reporting and management of cholera outbreaks.We evaluated the Crystal VC™ RDT under field conditions in Zanzibar in 2009. Patients presenting to treatment centers with watery diarrhea provided a stool sample for rapid diagnostic testing. Results were compared to stool culture performed in a reference laboratory. We assessed the overall performance of the RDT and evaluated whether previous intake of antibiotics, intravenous fluids, location of testing, and skill level of the technician affected the RDT results.We included stool samples from 624 patients. Compared to culture, the overall sensitivity of the RDT was 93.1% (95%CI: 88.7 to 96.2%, specificity was 49.2% (95%CI: 44.3 to 54.1%, the positive predictive value was 47.0% (95%CI: 42.1 to 52.0% and the negative predictive value was 93.6% (95%CI: 89.6 to 96.5%. The overall false positivity rate was 50.8% (213/419; fieldworkers frequently misread very faint test lines as positive.The observed sensitivity of the Crystal VC RDT evaluated was similar compared to earlier versions, while specificity was poorer. The current version of the RDT could potentially be used as a screening tool in the field. Because of the high proportion of false positive results when field workers test stool specimens, positive results will need to be confirmed with stool culture.

  9. Parametric study of a target factory for laser fusion

    International Nuclear Information System (INIS)

    Sherohman, J.W.; Meier, W.R.

    1980-01-01

    An analysis of a target factory leading to the derivation of production rate equations has provided the basis for a parametric study. Rate equations describing the production of laser fusion targets have been developed for the purpose of identifying key parameters, attractive production techniques and cost scaling relationships for a commercial target factory

  10. TEM studies of P+ implanted and subsequently laser annealed Si

    International Nuclear Information System (INIS)

    Sadana, D.K.; Wilson, M.C.; Booker, G.R.; Washburn, J.

    1979-05-01

    The present investigation is concerned with laser annealing of P + implanted Si. The aim of the work was to study the crystallization behavior of damage structure occurring due to high dose rate implantation using transmission electron microscopy (TEM) as the method of examination

  11. Study of shock coalescence in laser-irradiated targets

    International Nuclear Information System (INIS)

    Coe, S.E.; Willi, O.; Afshar-Rad, T.; Rose, S.J.

    1988-01-01

    We report on the first direct experimental observation of the coalescence of two shocks induced by a shaped laser pulse. Optical streak photography of the rear surface of aluminum multiple step targets was used to study the breakout of these shocks and observe their behavior. The experimental results are compared with simulations by a one-dimensional Lagrangian hydrodynamic code

  12. Recent studies of laser science in paintings conservation and research.

    Science.gov (United States)

    Pouli, Paraskevi; Selimis, Alexandros; Georgiou, Savas; Fotakis, Costas

    2010-06-15

    The removal of aged and deteriorated molecular overlayers from the surface of paintings is a delicate and critical intervention in Cultural Heritage (CH) conservation. This irreversible action gets particularly complicated given the multitude of materials that may be present within a painted work of art (often in ultrathin layers or traces), as well as the exceptional sensitivity of the original surfaces to environmental conditions such as heat, light, and so on. Lasers hold an important role among the available cleaning methodologies, as they enable high control and accuracy, material selectivity, and immediate feedback. Still, prior to their implementation, it is imperative to optimize the cleaning parameters, so to ensure that any potential implications to the remaining materials are minimal and well understood. Toward this aim, research at IESL-FORTH is focused on both refining and continuously updating the laser-cleaning protocols (by introducing novel laser technologies into the field, i.e., ultrashort laser pulses), as well as on investigating and studying the nature and extent of laser-induced physicochemical alterations to the involved materials. In this Account, extended work for the understanding of ultraviolet (UV) laser ablation of polymers is presented. Emphasis is placed on the use of model systems (polymers doped with chromophores of known photochemistry) to examine the in-depth laser-induced modifications at the processed surfaces and thus to illustrate the dependence of their nature and extent on laser parameters and material properties. Furthermore, studies for the potential use of femtosecond UV pulses to overcome certain limitations involved with the nanosecond ablation of molecular overlayers from CH surfaces are highlighted. In particular, it is demonstrated that in the femtosecond regime any chemical modifications are, qualitatively and quantitatively, highly defined, limited and nearly independent of the material properties, such as the

  13. Studies of Positron Generation from Ultraintense Laser-Matter Interactions

    Science.gov (United States)

    Williams, Gerald Jackson

    Laser-produced pair jets possess unique characteristics that offer great potential for their use in laboratory-astrophysics experiments to study energetic phenomenon such as relativistic shock accelerations. High-flux, high-energy positron sources may also be used to study relativistic pair plasmas and useful as novel diagnostic tools for high energy density conditions. Copious amounts of positrons are produced with MeV energies from directly irradiating targets with ultraintense lasers where relativistic electrons, accelerated by the laser field, drive positron-electron pair production. Alternatively, laser wakefield accelerated electrons can produce pairs by the same mechanisms inside a secondary converter target. This dissertation describes a series of novel experiments that investigate the characteristics and scaling of pair production from ultraintense lasers, which are designed to establish a robust platform for laboratory-based relativistic pair plasmas. Results include a simple power-law scaling to estimate the effective positron yield for elemental targets for any Maxwellian electron source, typical of direct laser-target interactions. To facilitate these measurements, a solenoid electromagnetic coil was constructed to focus emitted particles, increasing the effective collection angle of the detector and enabling the investigation of pair production from thin targets and low-Z materials. Laser wakefield electron sources were also explored as a compact, high repetition rate platform for the production of high energy pairs with potential applications to the creation of charge-neutral relativistic pair plasmas. Plasma accelerators can produce low-divergence electron beams with energies approaching a GeV at Hz frequencies. It was found that, even for high-energy positrons, energy loss and scattering mechanisms in the target create a fundamental limit to the divergence and energy spectrum of the emitted positrons. The potential future application of laser

  14. Study of the laser-induced forward transfer of liquids for laser bioprinting

    Science.gov (United States)

    Duocastella, M.; Colina, M.; Fernández-Pradas, J. M.; Serra, P.; Morenza, J. L.

    2007-07-01

    Laser-induced forward transfer (LIFT) is a direct-writing technique that allows printing patterns of diverse materials with a high degree of spatial resolution. In conventional LIFT a small fraction of a solid thin film is vaporized by means of a laser pulse focused on the film through its transparent holder, and the resulting material recondenses on the receptor substrate. It has been recently shown that LIFT can also be used to transfer materials from liquid films. This widened its field of application to biosensors manufacturing, where small amounts of biomolecules-containing solutions have to be deposited with high precision on the sensing elements. However, there is still little knowledge on the physical processes and parameters determining the characteristics of the transfers. In this work, different parameters and their effects upon the transferred material were studied. It was found that the deposited material corresponds to liquid droplets which volume depends linearly on the laser pulse energy, and that a minimum threshold energy has to be overcome for transfer to occur. The liquid film thickness was varied and droplets as small as 10 μm in diameter were obtained. Finally, the effects of the variation of the film to substrate distance were also studied and it was found that there exists a wide range of distances where the morphology of the transferred droplets is independent of this parameter, what provides LIFT with a high degree of flexibility.

  15. Nd:YAG laser in caries prevention: a clinical study

    International Nuclear Information System (INIS)

    Boari, Heloisa Gomes Dimiranda

    2000-01-01

    The caries prevention by using laser irradiation has been investigated during the last 30 years. The Nd: YAG laser associated with acidulated phosphate fluoride has been shown as a very promising technique for enamel caries prevention. The aim of this work was to clinically evaluate the efficiency of Nd: YAG laser associated with acidulated phosphate fluoride in pit and fissure caries prevention of children and adolescents. In this work it was determined the dye that enhance the effect of Nd: YAG laser in enamel. It was selected 242 pre-molar and molar teeth from 33 children and adolescents, aged from 7 to 15 years old. The selected teeth were free from caries or decalcification marks (active white marks) to the clinical and radiographic exams. The teeth were divided into two groups: the first group was laser irradiated and their homologous remained as a control. The right side teeth were dye-assisted Nd:YAG laser irradiated. The dye solution was a moisture of dust coal and equal parts of water and alcohol. The irradiation conditions were 60 mJ/10 Hz, optical fiber in contact mode, with diameter of 300 μm, resulting in an energy density of 84,9 J/cm 2 . The oclusal surface of the teeth was completely irradiated, specially on the slopes and in the deepest part of the pits and fissures. This procedure was repeated three times. In the sequence it was applied the acidulated phosphate fluoride for 4 minutes. On the left side teeth - control group- only acidulated phosphate fluoride was applied for the same time. The final examination considered the presence of caries and active white marks after a period of one year. There were statistical significant differences (p < 0.01) between the lased + fluoride group and the non irradiated group. The present study concluded that the technique used in this work can be an alternative clinical method for caries prevention. (author)

  16. Experimental study and numerical simulation of the propulsion of microbeads by femtosecond laser filament

    International Nuclear Information System (INIS)

    Zhang Nan; Liu Weiwei; Xu Zhijun; Wang Mingwei; Zhu Xiaonong

    2008-01-01

    The light filament formed by intense femtosecond laser pulses in air can be used to generate the effective impulse to propel a micro glass bead. In this report, through both experimental studies and the corresponding numerical simulations that involve the dynamics of the nonlinear propagation of light and the laser ablation mechanism, we confirm that this propulsion scheme is based on the laser ablation of the target material. The fundamental characteristics of laser propulsion using a single ultrafast laser filament is also revealed

  17. Studies in iodine metabolism: 33 year summary, 1948-1979 (as previously submitted) with appendix, 1979-1982

    International Nuclear Information System (INIS)

    Middlesworth, L.V.

    1982-01-01

    The results of research into iodine metabolism from 1948 to 1982 are summarized. Study areas included the monitoring of iodine 131 from fallout in the thyroid glands of cattle and humans, the biological functions and metabolism of thyroid hormones, and methods to reduce the retention of radioiodine in the thyroid

  18. Microscopic study on lasing characteristics of the UVSOR storage ring free electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Hama, H. [Institute for Molecular Science, Okazaki (Japan)]|[Graduate Univ. for Advanced Stuides, Okazaki (Japan); Yamazaki, J.; Kinoshita, T. [Institute for Molecular Science, Okazaki (Japan)] [and others

    1995-12-31

    Characteristics of storage ring free electron laser (SRFEL) at a short wavelength region (UV and visible) has been studied at the UVSOR facility, Institute for Molecular Science. We have measured the laser power evolution by using a biplanar photodiode, and the micro-macro temporal structure of both the laser and the electron bunch with a dualsweep streak camera. The saturated energy of the laser micropulse in the gain-switching (Q-switching) mode has been measured as a function of the ring current. We have not observed a limitation of the output power yet within the beam current can be stored. We have analyzed the saturated micropulse energy based on a model of gain reduction due to the bunch-heating. The bunch-heating process seems to be very complicate. We derived time dependent gain variations from the shape of macropulse and the bunch length. Those two gain variations are almost consistent with each other but slightly different in detail. The gain may be not only simply reduced by the energy spread but also affected by the phase space rotation due to synchrotron oscillation of the electron bunch. As reported in previous issue, the lasing macropulse consists of a couple of micropulses that are simultaneously evolved. From high resolution two-dimensional spectra taken by the dual-sweep streak camera, we noticed considerable internal substructures of the laser micropulse in both the time distribution and the spectral shape. There are a couple of peaks separated with almost same distance in a optical bunch. Such substructure does not seem to result from statistical fluctuations of laser seeds. Although the origin of the substructure of macropulse is not dear at the present, we are going to discuss about SRFEL properties.

  19. Basic studies on laser-assisted phacoemulsification using diode-pumped Er:YAG laser

    Science.gov (United States)

    Hausladen, Florian; Wurm, Holger; Stock, Karl

    2016-03-01

    The aim of this study was to determine the potential of a novel diode-pumped Er:YAG laser for phacoemulsification in basic experimental investigations. An appropriate experimental setup was created, including a translation stage for sample movement, a sample holder, a water spray for sample humidification and a surgical microscope with a CCD camera for video documentation. The analysis of the laser cuts and histological sections was done by light microscopy. As samples porcine eye lenses hardened by formalin were used. In ablation experiments with different spot diameters and radiant powers and a constant repetition rate νr = 200 Hz the maximum ablation depths of (4.346 +/- 0.044) mm have reached at (Ø = 480 μm, Φ = 24.15 W) with a maximum extend of thermal damage of (0.165 +/- 0.030) mm. The average ablation efficiency is 0.241 mm3/J. With a spot diameter of 308 μm the maximum ablation depth is (4.238 +/- 0.040) mm at 24.65 W with a mean ablation efficiency of 0.293 mm3/J. The extend of the thermally damaged region is (0.171 +/- 0.024) mm at this laser power. Using a sapphire cylinder with a diameter of 412 μm (length 38.5 mm) in direct tissue contact with water spray for sample humidification the ablation depth reaches (1.017 +/- 0.074) mm at 4.93 W and (1.840 +/- 0.092) mm at 9.87 W with a mean efficiency of 0.261 mm3/J. A thermal damage zone of (0.064 +/-0.024) mm at 9.87 W was measured. Additionally, at this high power, a progressive contamination and destruction of the cylinder end facet was observed. In conclusion, the investigations show that the diode-pumped Er:YAG laser has considerable potential for cataract surgery.

  20. Comparison of two picosecond lasers to a nanosecond laser for treating tattoos: a prospective randomized study on 49 patients.

    Science.gov (United States)

    Lorgeou, A; Perrillat, Y; Gral, N; Lagrange, S; Lacour, J-P; Passeron, T

    2018-02-01

    Q-switched nanosecond lasers demonstrated their efficacy in treating most types of tattoos, but complete disappearance is not always achieved even after performing numerous laser sessions. Picosecond lasers are supposed to be more efficient in clearing tattoos than nanosecond lasers, but prospective comparative data remain limited. To compare on different types of tattoos the efficacy of a nanosecond laser with two types of picosecond lasers. We conducted a prospective randomized study performed from December 2014 to June 2016 on adult patients with all types of tattoos. The tattoos were divided into two halves of equal size. After randomization, half of the tattoo was treated with a picosecond laser and the other half with a nanosecond laser. The evaluation was performed on standardized pictures performed before treatment and 2 months after the last session, by two physicians, not involved in the treatment, blinded on the type of treatments received. The main end point was a clearance above 75% of the tattoos. A total of 49 patients were included. Professional tattoos represented 85.7%, permanent make-up 8.2% and non-professional tattoo 6.1%. The majority were black or blue and 10.2% were polychromatic. No patient was lost during follow-up. A reduction of 75% or more of the colour intensity was obtained for 33% of the tattoos treated with the picosecond lasers compared to 14% with the nanosecond laser (P = 0.008). An improvement superior to 75% was obtained in 34% monochromic black or blue tattoos with the picosecond lasers compared to 9% for the nanosecond laser. Only one of the five polychromic tattoos achieved more than 75% of improvement with the two types of laser. Our results show a statistically significant superiority of the picosecond lasers compared to the nanosecond laser for tattoo clearance. However, they do not show better efficacy for polychromic tattoos and the difference in terms of side-effects was also minimal with a tendency of picosecond

  1. CHRONOVAC VOYAGEUR: A study of the immune response to yellow fever vaccine among infants previously immunized against measles.

    Science.gov (United States)

    Goujon, Catherine; Gougeon, Marie-Lise; Tondeur, Laura; Poirier, Béatrice; Seffer, Valérie; Desprès, Philippe; Consigny, Paul-Henri; Vray, Muriel

    2017-10-27

    For administration of multiple live attenuated vaccines, the Advisory Committee on Immunization Practices recommends either simultaneous immunization or period of at least 28days between vaccines, due to a possible reduction in the immune response to either vaccine. The main objective of this study was to compare the immune response to measles (alone or combined with mumps and rubella) and yellow fever vaccines among infants aged 6-24months living in a yellow fever non-endemic country who had receivedmeasles and yellow fever vaccines before travelling to a yellow fever endemic area. A retrospective, multicenter case-control study was carried out in 7 travel clinics in the Paris area from February 1st 2011 to march 31, 2015. Cases were defined as infants immunized with the yellow fever vaccine and with the measles vaccine, either alone or in combination with mumps and rubella vaccine, with a period of 1-27days between each immunization. For each case, two controls were matched based on sex and age: a first control group (control 1) was defined as infants having received the measles vaccine and the yellow fever vaccine simultaneously; a second control group (control 2) was defined as infants who had a period of more than 27days between receiving the measles vaccine and yellow fever vaccine. The primary endpoint of the study was the percentage of infants with protective immunity against yellow fever, measured by the titer of neutralizing antibodies in a venous blood sample. One hundred and thirty-one infants were included in the study (62 cases, 50 infants in control 1 and 19 infants in control 2). Of these, 127 (96%) were shown to have a protective titer of yellow fever antibodies. All 4 infants without a protective titer of yellow fever antibodies were part of control group 1. The measles vaccine, alone or combined with mumps and rubella vaccines, appears to have no influence on humoral immune response to the yellow fever vaccine when administered between 1 and 27

  2. New application of the long-pulsed Nd-YAG laser as an ablative resurfacing tool for skin rejuvenation: a 7-year study.

    Science.gov (United States)

    Alshami, Mohammad Ali

    2013-09-01

    Carbon dioxide (CO2 ) and erbium-yttrium aluminum garnet (Er-YAG) lasers are the gold standards in ablative skin resurfacing. Neodymium-doped yttrium aluminum garnet (Nd-YAG) laser is considered a nonablative skin resurfacing laser whose usage is limited due to its high cost. To assess the efficacy and safety of Nd-YAG as an ablative resurfacing laser and to compare the results with those previously published for CO2 and Erbium-YAG lasers. A total of 296 patients (251 female and 45 male) with Fitzpatrick skin types III-IV and dermatological conditions amenable to ablative skin resurfacing participated in this study. Nd-YAG laser parameters assessed were wavelength (1064 nm), pulse duration (5 ms), fluence (10 J/cm(2) ), and spot size (8-10 mm). Efficacy of Nd-YAG laser was assessed by comparing pre- and posttreatment photographs. An improvement of 30-80% was observed in treated patients. The degree of improvement correlated positively with the number of laser sessions. The most common side effect was hyperpigmentation. Other side effects were less common and mild in intensity compared with published results for gold standard ablative lasers. Not only was the Nd-YAG laser found to be as effective as Er-YAG and CO2 lasers, but treated patients also had shorter recovery and treatment times, and at lower cost. © 2013 Wiley Periodicals, Inc.

  3. Structural Study and Evaluation of Previous Restoration Work of Mohammad 'Ali Pasha Mosque at the Citadel in Cairo

    Directory of Open Access Journals (Sweden)

    dr.Yaser Yehya Amin Abdel-Aty

    2011-01-01

    Full Text Available Mohammad 'Ali Pasha Mosque at the Citadel in Cairo is considered one of the main landmarks in Egypt. It majestically stands at a northwestern bend of the Citadel and it is visible from numerous locations in Cairo. It has become the symbol of the Citadel, to the point that its name is given to the whole complex in the colloquial Egyptian parlance. This paper studies analytically the static and dynamic structural behavior of this great mosque using computer numerical modeling techniques, to reach the main reasons for past cracking and failures in its domed-roof and other structural elements, which occurred by the end of 19th Century. A number of 3D-models are analyzed to study the mosque, in both original and after restoration conditions, under static (i.e. dead and live loads and dynamic (i.e. Eigenvector modal analysis, response-spectrum and time-history cases of loading. Besides, structural evaluation of major restoration project, in 1930s, is conducted to determine the current structural safety status of the mosque

  4. Short-pulse CO2-laser damage studies of NaCl and KCl windows

    International Nuclear Information System (INIS)

    Newnam, B.E.; Nowak, A.V.; Gill, D.H.

    1979-01-01

    The damage resistance of bare surfaces and the bulk interior of NaCl and KCl windows was measured with a short-pulse CO 2 laser at 10.6 μm. Parametric studies with 1.7-ns pulses indicated that adsorbed water was probably the limiting agent on surface thresholds in agreement with previous studies at long pulsewidths. Rear-surface thresholds up to 7 J/cm 2 were measured for polished NaCl windows, whereas KCl surfaces damaged at approximately 60% of this level. The breakdown electric-field thresholds of exit surfaces were only 50% of the value of the bulk materials. The pulsewidth dependence of surface damage from 1 to 65 ns, in terms of incident laser fluence, increased as t/sup 1/3/

  5. Comparative study of a novel application of automated HR HPV assay and stability in a previously untested Preservative media.

    Science.gov (United States)

    Morel, Mike E; McBride, Simon E; Gomez, Maria P

    2017-12-01

    The suitability and stability of cervical cells in Novaprep media (NHQ) for certain HPV assays is unknown. We evaluated the accuracy of an automated HPV assay (Abbott RealTime HR HPV) for cervical cells prepared in NHQ and NHQ with a pre-treatment to mimic a worst case clinical use, compared to the assay manufacturers media; repeatability and reproducibility of HPV results and the stability of detectable HPV in NHQ over time compared to CE marked liquid based cytology preservatives. Cell lines were used to simulate patient samples. Cells stored in NHQ produced accurate, repeatable and reproducible results. Stability in NHQ was comparable to the best performing LBC, with at least 7 months' stability at 18-25°C, 2-8°C, -20°C and -80°C; and at least 3 months' stability at 40°C. Similar results were obtained for pre-treated NHQ except only 3.5 months' stability at 18-25°C. Cell line samples in all media and concentrations tested were detected appropriately by the assay. Based on this first stage validation analytical study, cervical cells stored in NHQ are suitable for the Realtime HPV assay. There should be no reservations for inclusion of NHQ in any further validation and clinical performance evaluation of this assay. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  6. Comparative study of a novel application of automated HR HPV assay and stability in a previously untested Preservative media

    Directory of Open Access Journals (Sweden)

    Mike E. Morel

    2017-12-01

    Full Text Available Background: The suitability and stability of cervical cells in Novaprep media (NHQ for certain HPV assays is unknown. Methods: We evaluated the accuracy of an automated HPV assay (Abbott RealTime HR HPV for cervical cells prepared in NHQ and NHQ with a pre-treatment to mimic a worst case clinical use, compared to the assay manufacturers media; repeatability and reproducibility of HPV results and the stability of detectable HPV in NHQ over time compared to CE marked liquid based cytology preservatives. Cell lines were used to simulate patient samples. Results: Cells stored in NHQ produced accurate, repeatable and reproducible results. Stability in NHQ was comparable to the best performing LBC, with at least 7 months’ stability at 18–25 °C, 2–8 °C, −20 °C and −80 °C; and at least 3 months’ stability at 40 °C. Similar results were obtained for pre-treated NHQ except only 3.5 months’ stability at 18–25 °C. Cell line samples in all media and concentrations tested were detected appropriately by the assay. Conclusions: Based on this first stage validation analytical study, cervical cells stored in NHQ are suitable for the Realtime HPV assay. There should be no reservations for inclusion of NHQ in any further validation and clinical performance evaluation of this assay. Keywords: HPV, Preservative, Sample stability, Automated HR HPV assay

  7. Impurity studies in fusion devices using laser-fluorescence-spectroscopy

    International Nuclear Information System (INIS)

    Husinsky, W.R.

    1980-08-01

    Resonance fluorescence excitation of neutral atoms using tunable radiation from dye lasers offers a number of unique advantages for impurity studies in fusion devices. Using this technique, it is possible to perform local, time-resolved measurements of the densities and velocity distributions of metallic impurities in fusion devices without disturbing the plasma. Velocities are measured by monitoring the fluorescence intensity while tuning narrow bandwidth laser radiation through the Doppler - broadened absorbtion spectrum of the transition. The knowledge of the velocity distribution of neutral impurities is particularly useful for the determination of impurity introduction mechanisms. The laser fluorescence technique will be described in terms of its application to metallic impurities in fusion devices and related laboratory experiments. Particular attention will be given to recent results from the ISX-B tokamak using pulsed dye lasers where detection sensitivities for neutral Fe of 10 6 atoms/cm 3 with a velocity resolution of 600 m/sec (0.1 eV) have been achieved. Techniques for exciting plasma particles (H,D) will also be discussed

  8. Studies on mechanisms of the laser particle acceleration

    International Nuclear Information System (INIS)

    Aurand, Bastian

    2012-01-01

    Within the last decade, many developments towards higher energies and particle numbers paved the way of particle acceleration performed by high intensity laser systems. Up to now, the process of a field-induced acceleration process (Target-Normal-Sheath-Acceleration (TNSA)) is investigated the most. Acceleration occurs as a consequence of separation of charges on a surface potential. Here, the broad energy spectrum is a problem not yet overcome although many improvements were achieved. Calculations for intensities higher than 10 20..21 W/cm 2 give hint that Radiation-Pressure-Acceleration (RPA) may lead to a sharper, monoenergetic energy spectrum. Within the framework of this thesis, the investigation of the acceleration mechanism is studied experimentally in the intensity range of 10 19 W/cm 2 . Suitable targets were developed and applied for patent. A broad range of parameters was scanned by means of high repetition rates together with an adequate laser system to provide high statistics of several thousands of shots, and the dependence of target material, intensity, laser polarisation and pre plasma-conditions was verified. Comparisons with 2-d numeric simulations lead to a model of the acceleration process which was analyzed by several diagnostic methods, giving clear evidence for a new, not field-induced acceleration process. In addition, a system for a continuous variation of the polarization based on reflective optics was developed in order to overcome the disadvantages of retardation plates, and their practicability of high laser energies can be achieved.

  9. Diode Laser Irradiation in Endodontic Therapy through Cycles - in vitro Study

    Directory of Open Access Journals (Sweden)

    Trišić Dijana

    2017-07-01

    Full Text Available Background/Aim: The aim of this in vitro study was to investigate the influence of irradiation cycles and resting periods, on thermal effects on the external root surface during root canal irradiation of two diode laser systems (940 nm and 975 nm, at output powers of 1 W and 2 W in continuous mode. In previous studies the rising of temperature above 7°C has been reported as biologically accepted to avoid periodontal damage on the external root surface. Material and Methods: Twenty human inferior incisors were randomly distributed into four groups, the 940 nm, and the 975 nm diode laser irradiation, both with an output power of 1 W and 2 W, in continuous mode. The thermographic camera was used to detect temperature variations on the external root surface. Digital radiography of the samples was made. Results: After three cycles of irradiation, at apical third of the root, mean temperature variation by 940 nm diode laser irradiation was 2.88°C for output power of 1 W, and 6.52°C for output power of 2 W. The 975 nm laser caused a higher temperature increase in the apical region, with temperature variation of 13.56°C by an output power of 1 W, and 30.60°C at 2 W, with a statistical significance of p ≤ 0.0001 between two laser systems compared for the same power. The resting periods of 20 s between cycles were enough to lower temperature under 7°C in the case of 1 W and 2 W for 940 nm diode laser, while for 975 nm laser, after three irradiation cycles overheating occurred at both output power rates. Conclusion: Three cycles irradiation of 940 nm diode laser, with resting periods of 20 seconds, allowed safe usage of 1 W and 2 W in CW for endodontic treatment. For 975 nm at a power rate of 1 W, the last resting period drop the temperature near the safe limit and it came under 7°C in a period less than a minute, while at the power of 2 W the resting periods were not long enough for the safe temperature decrease.

  10. Pilot study of synchronization on a femtosecond scale between the electronic gun REGAE and a laser-plasma accelerator

    International Nuclear Information System (INIS)

    Titberidze, Mikheil

    2017-10-01

    given. Second, an advanced Mach-Zehnder modulator (MZM) based laser-to-RF synchronization setup has been successfully developed and tested. The conceptual design, a mathematical analysis, tolerance studies and experimental evaluation is presented. Electron beam-based measurements have been performed at REGAE where MZM based laser synchronization achieved a factor of 10 performance improvement in terms of amplitude-to-phase modulation (AM-PM) conversion compared to the previously used conventional photodiode based laser synchronization setup. This setup has been employed to phase lock the REGAE photo-injector laser with excellent long term timing drift performance of 31 fs peak-to-peak over 43 h and a short term timing jitter of 11 fs rms.

  11. Pilot study of synchronization on a femtosecond scale between the electronic gun REGAE and a laser-plasma accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Titberidze, Mikheil

    2017-10-15

    are given. Second, an advanced Mach-Zehnder modulator (MZM) based laser-to-RF synchronization setup has been successfully developed and tested. The conceptual design, a mathematical analysis, tolerance studies and experimental evaluation is presented. Electron beam-based measurements have been performed at REGAE where MZM based laser synchronization achieved a factor of 10 performance improvement in terms of amplitude-to-phase modulation (AM-PM) conversion compared to the previously used conventional photodiode based laser synchronization setup. This setup has been employed to phase lock the REGAE photo-injector laser with excellent long term timing drift performance of 31 fs peak-to-peak over 43 h and a short term timing jitter of 11 fs rms.

  12. High-power laser experiments to study collisionless shock generation

    Directory of Open Access Journals (Sweden)

    Sakawa Y.

    2013-11-01

    Full Text Available A collisionless Weibel-instability mediated shock in a self-generated magnetic field is studied using two-dimensional particle-in-cell simulation [Kato and Takabe, Astophys. J. Lett. 681, L93 (2008]. It is predicted that the generation of the Weibel shock requires to use NIF-class high-power laser system. Collisionless electrostatic shocks are produced in counter-streaming plasmas using Gekko XII laser system [Kuramitsu et al., Phys. Rev. Lett. 106, 175002 (2011]. A NIF facility time proposal is approved to study the formation of the collisionless Weibel shock. OMEGA and OMEGA EP experiments have been started to study the plasma conditions of counter-streaming plasmas required for the NIF experiment using Thomson scattering and to develop proton radiography diagnostics.

  13. Marginal microleakage in vitro study on class V cavities prepared with Er:YAG laser and etched with acid or etched with Er:YAG laser and acid

    International Nuclear Information System (INIS)

    Tavares, Henrique Dutra Simoes

    2001-01-01

    Microleakage at the interface between the teeth and the restorative materials remains a problem with composite resin restorations. Microleakage at the gingival margins of class V cavities restorations still challenge as they are usually placed in dentin and/or cementum. Previous studies have shown that the cavity preparation with Er:YAG laser is possible. It has been reported that Er:YAG laser has ability to create irregular surface providing micromechanical retention for adhesive dental restorative materials and to improve marginal sealing. The purpose of this in vitro study was to evaluate the marginal microleakage on class V cavities prepared with Er:YAG laser and etched with acid or with Er:YAG laser and acid, in compared to those prepared and etched conventionally. Thirty human molars were divided into three groups, namely: group I - prepared with Er:YAG laser (KaVo KEY Laser II - Germany) and etched with 37% phosphoric acid; group II - prepared with Er:YAG laser and etched with Er:YAG laser and 37% phosphoric acid; group III (control group) - prepared with high speed drill and etched with 37% phosphoric acid. All cavities were treated with same adhesive system (Single Bond - 3M) and restored with the composite resin (Z100 - 3M), according to the manufacturer's instructions. The specimens were stored at 37 deg C in water for 24 hours, polished with Sof-Lex discs (3M), thermally stressed, sealed with a nail polish coating except for the area of the restoration and 1 mm around it, and immersed in a 50% aqueous solution of silver nitrate for 24 hours. After that, the specimens were rinsed in water, soaked in a photodeveloping solution and exposed to a fluorescent light for 8 hours. The teeth were embedded in an autopolymerizing resin and sectioned longitudinally using a diamond saw microtome under running water. The sections were photographed. The microleakage at the occlusal cavity and at the gingival margins of each specimen was evaluated with scores (0-3) by

  14. Laser-plasma based electron acceleration studies planned at CAT, Indore

    International Nuclear Information System (INIS)

    Naik, P.A.; Gupta, P.D.

    2005-01-01

    The Laser Plasma Division at the Centre for Advanced Technology is engaged in a variety of R and D activities on laser-plasma interaction with special emphasis on laser-matter interaction at ultra-high intensities. An important aspect of our future work is studies in laser-plasma based acceleration using an elaborate infrastructural set-up of ultra-fast laser and plasma diagnostic systems and recently acquired 10 TW, 50 fs Ti: Sapphire laser system. This paper presents outline of the planned studies in this field. (author)

  15. [Crystalline lens photodisruption using femtosecond laser: experimental study].

    Science.gov (United States)

    Chatoux, O; Touboul, D; Buestel, C; Balcou, P; Colin, J

    2010-09-01

    The aim of this study was to analyze the interactions during femtosecond (fs) laser photodisruption in ex vivo porcine crystalline lenses and to study the parameters for laser interaction optimization. An experimental femtosecond laser was used. The laser characteristics were: 1030 nm wavelength; pulse duration, 400 fs; and numerical aperture, 0.13. Specific software was created to custom and monitor any type of photoablation pattern for treatment purposes. Porcine crystalline lenses were placed in an open sky holder filled with physiological liquid (BSS) covered by a glass plate. A numerical camera was associated with metrological software in order to magnify and quantify the results. Transmission electron microscopy (TEM) was performed on some samples to identify the microscopic plasma interactions with the lens. The optimization of parameters was investigated in terms of the optical breakdown threshold, the sizing of interactions, and the best pattern for alignments. More than 150 crystalline lenses of freshly enucleated pigs were treated. The optical breakdown threshold (OBT) was defined as the minimal energy level per pulse necessary to observe a physical interaction. In our study, the OBT varied according to the following parameters: the crystalline lens itself, varying from 4.2 to 7.6 μJ (mean, 5.1 μJ), and the depth of laser focus, varying up to 1 μJ, increasing in the depth of the tissue. Analyzing the distance between impacts, we observed that the closer the impacts were the less power was needed to create a clear well-drawn defect pattern (lines), i.e., with a 4-μJ optimized OBT, when the impacts were placed every 2 μm for the x,y directions and 60 μm for the z direction. Coalescent bubbles created by plasma formation always disappeared in less than 24h. The nonthermal effect of plasma and the innocuousness on surrounding tissues were proven by the TEM results. The crystalline lens photodisruption by the femtosecond laser seems an innovative

  16. A numerical study of the integral equations for the laser fields in free-electron lasers

    International Nuclear Information System (INIS)

    Yoo, J. G.; Park, S. H.; Jeong, Y. U.; Lee, B. C.; Rhee, Y. J.; Cho, S. O.

    2004-01-01

    The dynamics of the radiation fields in free-electron lasers is investigated on the basis of the integro-differential equations in the one-dimensional formulation. For simple cases we solved the integro-differential equations analytically and numerically to test our numerical procedures developed on the basis of the Filon method. The numerical results showed good agreement with the analytical solutions. To confirm the legitimacy of the numerical package, we carried out numerical studies on the inhomogeneous broadening effects, where no analytic solutions are available, due to the energy spread and the emittance of the electron beam.

  17. The theoretical study of the optical klystron free electron laser

    International Nuclear Information System (INIS)

    Yang Zhenhua

    2001-01-01

    The work of the theoretical study and numerical simulation of optical klystron free electron laser is supported by National 863 Research Development Program and National Science Foundation of China. The object of studying UV band free electron laser (FEL) is to understand the physical law of optical klystron FEL and to gain experience for design. A three-dimensional code OPFEL are made and it is approved that the code is correct completely. The magnetic field of the optical klystron, the energy modulation of the electron beam, the density modulation of the electron beam, spontaneous emission of the electron beam in optical klystron, the harmonic super-radiation of the electron beam, and the effects of the undulator magnetic field error on modulation of the electron beam energy are simulated. These results are useful for the future experiments

  18. Nonlinear scattering in hard tissue studied with ultrashort laser pulses

    International Nuclear Information System (INIS)

    Eichler, J.; Kim, B.M.

    2002-01-01

    The back-scattered spectrum of ultrashort laser pulses (800 nm, 0.2 ps) was studied in human dental and other hard tissues in vitro below the ablation threshold. Frequency doubled radiation (SHG), frequency tripled radiation and two-photon fluorescence were detected. The relative yield for these processes was measured for various pulse energies. The dependence of the SHG signal on probe thickness was determined in forward and back scattering geometry. SHG is sensitive to linear polarization of the incident laser radiation. SHG in human teeth was studied in vitro showing larger signals in dentin than in cementum and enamel. In carious areas no SHG signal could be detected. Possible applications of higher harmonic radiation for diagnostics and microscopy are discussed. (orig.)

  19. Uranium speciation in biofilms studies by laser fluorescence techniques

    International Nuclear Information System (INIS)

    Arnold, Thuro; Grossmann, Kay; Baumann, Nils

    2010-01-01

    Biofilms may immobilize toxic heavy metals in the environment and thereby influence their migration behaviour. The mechanisms of these processes are currently not understood, because the complexity of such biofilms creates many discrete geochemical microenvironments which may differ from the surrounding bulk solution in their bacterial diversity, their prevailing geochemical properties, e.g. pH and dissolved oxygen concentration, the presence of organic molecules, e.g. metabolites, and many more, all of which may affect metal speciation. To obtain such information, which is necessary for performance assessment studies or the development of new cost-effective strategies for cleaning waste waters, it is very important to develop new non-invasive methods applicable to study the interactions of metals within biofilm systems. Laser fluorescence techniques have some superior features, above all very high sensitivity for fluorescent heavy metals. An approach combining confocal laser scanning microscopy and laser-induced fluorescence spectroscopy for study of the interactions of biofilms with uranium is presented. It was found that coupling these techniques furnishes a promising tool for in-situ non-invasive study of fluorescent heavy metals within biofilm systems. Information on uranium speciation and uranium redox states can be obtained.

  20. Study of melt flow dynamics and influence on quality for CO{sub 2} laser fusion cutting

    Energy Technology Data Exchange (ETDEWEB)

    Riveiro, A; Quintero, F; Lusquinos, F; Comesana, R; Pou, J [Applied Physics Department, University of Vigo, ETSII, Lagoas-Marcosende, 9, 36310 Vigo (Spain)

    2011-04-06

    The understanding of melt flow dynamics during fusion laser cutting is still a topic of great importance because this determines the quality characteristics of the processed workpiece. Despite the complexity of the experimental study of the physical processes involved in this technique, fusion laser cutting can be visualized during the processing of glass because this material absorbs the laser radiation provided by a CO{sub 2} laser but shows transparency to visible radiation. Then, we present in this work the results of the study of the melt flow dynamics during laser cutting of glass. Under different experimental conditions, the dynamics of the cutting front and its complete geometry (front wall inclination), and the evolution of the melt along the cut edge were analysed using a high-speed video camera to study the process. A phenomenon concerning the plasma plume formed during the process was observed, which has not been previously reported in the literature. This can displace the normal shock wave (MSD) commonly formed in the inlet kerf and can affect the assist gas flow into the kerf. On the other hand, the analysis of the recorded images allowed the determination of not only the amount of molten material along the cut edge but also the direction and velocity of the melt. Relevant processing parameters affecting the flow of molten material were assessed. These results were used as a basis to explain the different processes involved in the generation of dross, a typical imperfection appearing in laser cutting.

  1. [Laser Raman Spectroscopy and Its Application in Gas Hydrate Studies].

    Science.gov (United States)

    Fu, Juan; Wu, Neng-you; Lu, Hai-long; Wu, Dai-dai; Su, Qiu-cheng

    2015-11-01

    Gas hydrates are important potential energy resources. Microstructural characterization of gas hydrate can provide information to study the mechanism of gas hydrate formation and to support the exploitation and application of gas hydrate technology. This article systemly introduces the basic principle of laser Raman spectroscopy and summarizes its application in gas hydrate studies. Based on Raman results, not only can the information about gas composition and structural type be deduced, but also the occupancies of large and small cages and even hydration number can be calculated from the relative intensities of Raman peaks. By using the in-situ analytical technology, laser Raman specstropy can be applied to characterize the formation and decomposition processes of gas hydrate at microscale, for example the enclathration and leaving of gas molecules into/from its cages, to monitor the changes in gas concentration and gas solubility during hydrate formation and decomposition, and to identify phase changes in the study system. Laser Raman in-situ analytical technology has also been used in determination of hydrate structure and understanding its changing process under the conditions of ultra high pressure. Deep-sea in-situ Raman spectrometer can be employed for the in-situ analysis of the structures of natural gas hydrate and their formation environment. Raman imaging technology can be applied to specify the characteristics of crystallization and gas distribution over hydrate surface. With the development of laser Raman technology and its combination with other instruments, it will become more powerful and play a more significant role in the microscopic study of gas hydrate.

  2. Explosive Nucleosynthesis Study Using Laser Driven γ-ray Pulses

    Directory of Open Access Journals (Sweden)

    Takehito Hayakawa

    2017-03-01

    Full Text Available We propose nuclear experiments using γ-ray pulses provided from high field plasma generated by high peak power laser. These γ-ray pulses have the excellent features of extremely short pulse, high intensity, and continuous energy distribution. These features are suitable for the study of explosive nucleosyntheses in novae and supernovae, such as the γ process and ν process. We discuss how to generate suitable γ-ray pulses and the nuclear astrophysics involved.

  3. Long Scalelength Plasmas for LPI Studies at the Nike Laser

    Science.gov (United States)

    Weaver, J. L.; Oh, J.; Bates, J. W.; Schmitt, A. J.; Kehne, D. M.; Wolford, M. F.; Obenschain, S. P.; Serlin, V.; Lehmberg, R. H.; Follett, R. K.; Shaw, J. G.; Myatt, J. F.; McKenty, P. W.; Wei, M. S.; Reynolds, H.; Williams, J.; Tsung, F.

    2017-10-01

    Studies of laser plasma instabilities (LPI) at the Nike laser have mainly used short pulses, small focal spots, and solid plastic (CH) targets that have yielded maximum gradient scalelengths below 200 microns. The current experimental effort aims to produce larger volume plasmas with 5-10x reduction in the density and velocity gradients as a platform for SBS, SRS, and TPD studies. The next campaign will concentrate on the effects of wavelength shifting and bandwidth changes on CBET in low density (5-10 mg/cm3) CH foam targets. This poster will discuss the development of this new LPI target platform based on modelling with the LPSE code developed at LLE. The presentation will also discuss alternative target schemes (e.g. exploding foils) and improvements to the LPI diagnostic suite and laser operations; for example, a new set of etalons will be available for the next campaign that should double the range of available wavelength shifting. Upgrades to the scattered light spectrometers in general use for LPI studies will also be presented. Work supported by DoE/NNSA.

  4. Two-dimensional study of shock breakout at the rear face of laser irradiated metallic targets

    Energy Technology Data Exchange (ETDEWEB)

    Cottet, F.; Marty, L.; Hallouin, M.; Romain, J.P.; Virmont, J.; Fabbro, R.; Faral, B.

    1988-11-01

    The two-dimensional propagation dynamics of laser-driven shock waves in solids is studied through the analysis of the shock breakout at the rear face of the target for a set of materials and laser intensities. The laser shock simulations were carried out by means of a two-dimensional hydrodynamics code in which the laser-ablation pressure is replaced by an equivalent pressure pulse. It is shown that the two-dimensional code is a very useful tool to analyze laser-shock experiments where two-dimensional effects arise from a finite laser-spot size or a heterogeneous energy deposition.

  5. Two-dimensional study of shock breakout at the rear face of laser irradiated metallic targets

    International Nuclear Information System (INIS)

    Cottet, F.; Marty, L.; Hallouin, M.; Romain, J.P.; Virmont, J.; Fabbro, R.; Faral, B.

    1988-01-01

    The two-dimensional propagation dynamics of laser-driven shock waves in solids is studied through the analysis of the shock breakout at the rear face of the target for a set of materials and laser intensities. The laser shock simulations were carried out by means of a two-dimensional hydrodynamics code in which the laser-ablation pressure is replaced by an equivalent pressure pulse. It is shown that the two-dimensional code is a very useful tool to analyze laser-shock experiments where two-dimensional effects arise from a finite laser-spot size or a heterogeneous energy deposition

  6. Molecular dynamics stimulations to study laser dye aggregation in water (comparison with experiments)

    International Nuclear Information System (INIS)

    Dare-Doyen, St.; Doizi, D.

    2000-01-01

    A laser facility consists of dye laser chains where the active medium is composed of fluorescent dyes dissolved in ethanol. The use of water as a solvent would offer two major advantages: greater safety of the laser facility by drastically reducing fire risks, easier design of the laser beam correcting devices required at the end of the dye laser chains, thanks to the properties of water. Unfortunately, laser dyes exhibit poor optical properties in water, due to the formation of dye aggregates. Molecular dynamics simulations were used to study and develop means to prevent this behavior between two charged species. The results were compared with NMR (Nuclear Magnetic Resonance) experiments

  7. Study on Laser Induced Plasma Produced in Liquid

    International Nuclear Information System (INIS)

    Tsuda, N.; Yamada, J.

    2003-01-01

    When an intense laser light is focused in liquid, a hot plasma is produced at the focal spot. The breakdown threshold and the transmittance of sodium choroids solution are observed using excimer laser or YAG laser. The breakdown threshold decreases with increasing NaCl concentration. Threshold intensity of plasma produced by YAG laser is lower than excimer laser. The behavior of plasma development is observed by a streak camera. The plasma produced by a YAG laser develops only backward. However, the plasma produced by excimer laser develops not only backward but also forward same as the plasma development in high-pressure gases

  8. Study of liquid deposition during laser printing of liquids

    Energy Technology Data Exchange (ETDEWEB)

    Duocastella, M.; Patrascioiu, A. [Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Marti i Franques 1, E-08028 Barcelona (Spain); Dinca, V. [Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Marti i Franques 1, E-08028 Barcelona (Spain); National Institute for Lasers, Plasma and Radiation Physics, Atomistilor No. 409, PO Box MG 16, 077125 Bucharest (Romania); Fernandez-Pradas, J.M.; Morenza, J.L. [Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Marti i Franques 1, E-08028 Barcelona (Spain); Serra, P., E-mail: pserra@ub.edu [Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Marti i Franques 1, E-08028 Barcelona (Spain)

    2011-04-01

    Laser-induced forward transfer (LIFT) is a direct-writing technique which can be used to successfully print various complex and sensitive materials with a high degree of spatial resolution. However, the optimization of its performances requires a deep understanding of the LIFT dynamics. Such understanding should allow correlating the phenomena underlying the liquid transfer process with the morphology of the obtained deposits. To this end, in this work it is presented a study related to two aspects: first, the correlation of the morphological characteristics of the transferred droplets with the variation of the film thickness combined with laser fluence; and second, a correlation of the dependences observed with the dynamics of the transfer process. The work is focused on the understanding of the observed dependences for which the information provided by time-resolved analysis on liquid transfer dynamics has proved to be crucial.

  9. Study of liquid deposition during laser printing of liquids

    International Nuclear Information System (INIS)

    Duocastella, M.; Patrascioiu, A.; Dinca, V.; Fernandez-Pradas, J.M.; Morenza, J.L.; Serra, P.

    2011-01-01

    Laser-induced forward transfer (LIFT) is a direct-writing technique which can be used to successfully print various complex and sensitive materials with a high degree of spatial resolution. However, the optimization of its performances requires a deep understanding of the LIFT dynamics. Such understanding should allow correlating the phenomena underlying the liquid transfer process with the morphology of the obtained deposits. To this end, in this work it is presented a study related to two aspects: first, the correlation of the morphological characteristics of the transferred droplets with the variation of the film thickness combined with laser fluence; and second, a correlation of the dependences observed with the dynamics of the transfer process. The work is focused on the understanding of the observed dependences for which the information provided by time-resolved analysis on liquid transfer dynamics has proved to be crucial.

  10. Pilot study in neonates using low-level laser therapy in the immediate postoperative period of myelomeningocele

    Directory of Open Access Journals (Sweden)

    Nathali Cordeiro Pinto

    2010-03-01

    Full Text Available Objective: To analyze the tissue repair behavior after corrective surgical incision in neonates submitted to low-level laser therapy, in an attempt to diminish the incidence of postoperative dehiscence following the surgery for myelomeningocele performed immediately after birth. Methods: It is a prospective pilot study with 13 myelomeningocele patients submitted to surgery at birth who received adjuvant treatment with low-level laser therapy (Group A. Diode laser C.W., λ = 685t nm, p = 21 mW, E = 0.19 J was punctually applied along the surgical incision, summing up 4 to 10 J energy delivered per patient, according to the surgical wound area and, then, compared with the previous results, which were obtained from 23 patients undergoing surgery without laser therapy (Group B. Results: This pilot study showed a significant decline in dehiscence of surgical wounds in neonates submitted to low-level laser therapy as compared to controls (7.69 versus 17.39%, respectively, demonstrating this is an effective, safe and noninvasive treatment method. Conclusion: This new adjuvant therapeutic proposal with low-level laser therapy aided healing of surgical wounds, preventing morbidities, as well as decreasing hospital stay, which implies cost of reduction for patients and for the institution.

  11. Treatment of Dentine Hypersensitivity by Diode Laser: A Clinical Study

    Directory of Open Access Journals (Sweden)

    Romeo Umberto

    2012-01-01

    Full Text Available Introduction. Dentine hypersensitivity (DH is characterized by pain after stimuli that usually provoke no symptoms. This study compared the effectiveness of GaAlAs diode laser alone and with topical sodium fluoride gel (NaF. Materials and Methods. The study was conducted on 10 patients (8 F/2 M, age 25–60 and 115 teeth with DH assessed by air and tactile stimuli measured by Numeric Rating Scale (NRS. Teeth were randomly divided into G1 (34 teeth treated by 1.25% NaF; G2 (33 teeth lased at 0.5 W PW (T on 100 m and T off 100 ms, fluence 62.2 J/cm2 in defocused mode with a 320 μ fiber. Each tooth received three 1′ applications; G3 (48 teeth received NaF gel plus laser at same G2 parameters. NRS was checked at each control. Results. Significant pain reduction was showed. The NRS reduction percentages were calculated, and there was a concrete decrease of DH above all in G3 than G2 and G1. Conclusion. Diode laser is a useful device for DH treatment if used alone and mainly if used with NaF gel.

  12. A study on laser welding deformation of 304 stainless steel

    International Nuclear Information System (INIS)

    Kitagawa, Akikazu; Maehara, Kenji; Takeda, Shinnosuke; Matsunawa, Akira

    2002-01-01

    In heavy industries, 304 austenitic stainless steel is the most popular material which is used for nuclear equipment, chemical vessels, vacuum vessels and so on. On the fabrication, not only a joint quality but also severe dimensional accuracy is required. To keep dimensional accuracy, considerable cost and efforts are requested, because the welding deformation of austenitic stainless steel is deeply depended on the physical properties of material itself. To decrease welding deformation, big jigs or water cooling method are commonly used which lead to the high cost. In general, the fusion welding by high energy density heat source results in less distortion. Today, laser welding technology has grown up to the stage that enables to weld thick plate with small deformation. The researches of welding deformation have been conducted intensively, but they are mainly concerned for arc welding, and studies for laser welding are very few. In this report, the authors will show the test results of deformation behavior in laser welding of 304 stainless steel. Also, they will discuss the deformation behavior comparing to that in arc welding. The main results of this study are as follows. 1. The angular distortion of laser welding can be unified by heat input parameter (Hp) which is used for arc welding deformation. 2. The angular distortion are same under the condition of Hp 3 in spite of different welding method, however under the condition of Hp>6-9 J/mm 3 the angular distortion is quite different depending on the power density of welding method. 3. Pure angular distortion seemed to complete just after welding, but following longitudinal distortion took place for long period. 4. The critical value of longitudinal distortion can be estimated from heat input parameter. The transverse deformation can be also estimated by heat input parameter. (author)

  13. MicroRNA Expression in Laser Micro-dissected Breast Cancer Tissue Samples - a Pilot Study.

    Science.gov (United States)

    Seclaman, Edward; Narita, Diana; Anghel, Andrei; Cireap, Natalia; Ilina, Razvan; Sirbu, Ioan Ovidiu; Marian, Catalin

    2017-10-28

    Breast cancer continues to represent a significant public health burden despite outstanding research advances regarding the molecular mechanisms of cancer biology, biomarkers for diagnostics and prognostic and therapeutic management of this disease. The studies of micro RNAs in breast cancer have underlined their potential as biomarkers and therapeutic targets; however most of these studies are still done on largely heterogeneous whole breast tissue samples. In this pilot study we have investigated the expression of four micro RNAs (miR-21, 145, 155, 92) known to be involved in breast cancer, in homogenous cell populations collected by laser capture microdissection from breast tissue section slides. Micro RNA expression was assessed by real time PCR, and associations with clinical and pathological characteristics were also explored. Our results have confirmed previous associations of miR-21 expression with poor prognosis characteristics of breast cancers such as high stage, large and highly proliferative tumors. No statistically significant associations were found with the other micro RNAs investigated, possibly due to the small sample size of our study. Our results also suggest that miR-484 could be a suitable endogenous control for data normalization in breast tissues, these results needing further confirmation by future studies. In summary, our pilot study showed the feasibility of detecting micro RNAs expression in homogenous laser captured microdissected invasive breast cancer samples, and confirmed some of the previously reported associations with poor prognostic characteristics of breast tumors.

  14. Laser assisted bioprinting using a femtosecond laser with and without a gold transductive layer: a parametric study

    Science.gov (United States)

    Desrus, H.; Chassagne, B.; Catros, S.; Artiges, C.; Devillard, R.; Petit, S.; Deloison, F.; Fricain, J. C.; Guillemot, F.; Kling, R.

    2016-03-01

    Experimental results of femtosecond Laser Assisted Bioprinting (LAB) are reported on. Two set-up, used to print different model bioinks and keratinocytes cells line HaCaT, were studied: first one was using a femtosecond laser with low pulse energy and an absorbing gold layer, whereas the second one used high pulse energy enabling the removal of the absorbing layer. Printed drop diameter and resulting height of the bioink jet are then quantified as a function of the LAB parameters such as laser energy, focus spot location or numerical aperture.

  15. Parametric Study and Multi-Criteria Optimization in Laser Cladding by a High Power Direct Diode Laser

    Science.gov (United States)

    Farahmand, Parisa; Kovacevic, Radovan

    2014-12-01

    In laser cladding, the performance of the deposited layers subjected to severe working conditions (e.g., wear and high temperature conditions) depends on the mechanical properties, the metallurgical bond to the substrate, and the percentage of dilution. The clad geometry and mechanical characteristics of the deposited layer are influenced greatly by the type of laser used as a heat source and process parameters used. Nowadays, the quality of fabricated coating by laser cladding and the efficiency of this process has improved thanks to the development of high-power diode lasers, with power up to 10 kW. In this study, the laser cladding by a high power direct diode laser (HPDDL) as a new heat source in laser cladding was investigated in detail. The high alloy tool steel material (AISI H13) as feedstock was deposited on mild steel (ASTM A36) by a HPDDL up to 8kW laser and with new design lateral feeding nozzle. The influences of the main process parameters (laser power, powder flow rate, and scanning speed) on the clad-bead geometry (specifically layer height and depth of the heat affected zone), and clad microhardness were studied. Multiple regression analysis was used to develop the analytical models for desired output properties according to input process parameters. The Analysis of Variance was applied to check the accuracy of the developed models. The response surface methodology (RSM) and desirability function were used for multi-criteria optimization of the cladding process. In order to investigate the effect of process parameters on the molten pool evolution, in-situ monitoring was utilized. Finally, the validation results for optimized process conditions show the predicted results were in a good agreement with measured values. The multi-criteria optimization makes it possible to acquire an efficient process for a combination of clad geometrical and mechanical characteristics control.

  16. GreenLight laser vs diode laser vaporization of the prostate: 3-year results of a prospective nonrandomized study.

    Science.gov (United States)

    Guo, Sanwei; Müller, Georg; Bonkat, Gernot; Püschel, Heike; Gasser, Thomas; Bachmann, Alexander; Rieken, Malte

    2015-04-01

    Laser vaporization of the prostate is one of the alternatives to transurethral resection of the prostate. Short-term studies report a comparable outcome after laser vaporization with the 532 nm 120-W GreenLight high-performance system (HPS) laser and the 980 nm 200 W high-intensity diode (diode) laser. In this study, we analyzed the intermediate-term results of both techniques. From January 2007 to January 2008, 112 consecutive patients with symptomatic benign prostate enlargement were nonrandomly assigned to treatment with the GreenLight laser or the diode laser. Perioperative parameters, postoperative functional outcome, complications, and the reoperation rate at 3 years were analyzed. Improvement of voiding symptoms (International Prostate Symptom Score, quality-of-life) and micturition parameters (maximum flow rate, postvoid residual volume) showed no significant difference between the HPS group and the diode group. A significantly higher reoperation rate was observed in the diode group in comparison to the HPS group (37.5% vs 8.9%, p=0.0003) due to obstructive necrotic tissue (16.1% vs 0%, p=0.0018), bladder neck stricture (16.1% vs 1.8%, p=0.008), and persisting or recurrent adenoma (5.4% vs 7.1%, p=0.70), respectively. Both lasers lead to comparable improvement of voiding parameters and micturition symptoms. Treatment with the 200 W diode laser led to a significantly higher reoperation rate, which might be attributed to a higher degree of coagulation necrosis. Thus, a careful clinical application of this diode laser type is warranted.

  17. A high-repetition rate LWFA for studies of laser propagation and electron generation

    Science.gov (United States)

    He, Zhaohan; Easter, James; Hou, Bixue; Krushelnick, Karl; Nees, John; Thomas, Alec

    2010-11-01

    Advances in ultrafast optics today have enabled laser systems to deliver ever shorter and more intense pulses. When focused, such laser pulses can easily exceed relativistic intensities where the wakefield created by the strong laser electric field can be used to accelerate electrons. Laser wakefield acceleration of electrons holds promise for future compact electron accelerators or drivers of other radiation sources in many scientific, medical and engineering applications. We present experimental studies of laser wakefield acceleration using the λ-cubed laser at the University of Michigan -- a table-top high-power laser system operating at 500 Hz repetition rate. The high repetition rate allows statistical studies of laser propagation and electron acceleration which are not accessible with typical sub-0.1 Hz repetition rate systems. In addition, we compare the experiments with particle-in-cell simulations using the code OSIRIS.

  18. Studies on the influence of laser beams on wound granulation

    International Nuclear Information System (INIS)

    Brunner, R.

    1982-01-01

    The influence of laser light of law energy on wound healing was tested on 204 rats in a blind study. The growth of granulation tissue in a polyvinylchloride cylinder implanted on the backs of the animals served as parameter for wound healing. Irradiation was carried out with a helium-neon laser (wavelength 632.8 nm) at daily doses of 0.5 J/cm 2 , 1.5 J/cm 2 , 4 J/cm 2 , 10 J/cm 2 and 20 J/cm 2 , and with incoherent non-linear polarized red light (wavelength 630 nm) with a daily dose of 4 J/cm 2 . This was repeated 8 times. Laser irradiation caused a statistically significant increase in wet and dry granulation tissue weight of 25% in the dose range 1.5 J/cm 2 to 20 J/cm 2 . At 0.5 J/cm 2 the effect was less, but the least effect was achieved by non-linear polarized incoherent red light. Bacteriological evaluation of wound germ counts revealed a marginally lower presence of high germ cell densities. In irradiated animals, histological and enzyme cytochemical findings revealed, in addition to a significant findings revealed, in addition to a significant increase in mast cells, a smaller increase in fibroblast count and a slight decrease in granulocytic and histiocytic elements. The biochemical evaluation of granulation tissue revealed no differences in collagen content between irradiated and unirradiated animals. (orig.) [de

  19. Polychlorinated biphenyl exposure, diabetes and endogenous hormones: a cross-sectional study in men previously employed at a capacitor manufacturing plant.

    Science.gov (United States)

    Persky, Victoria; Piorkowski, Julie; Turyk, Mary; Freels, Sally; Chatterton, Robert; Dimos, John; Bradlow, H Leon; Chary, Lin Kaatz; Burse, Virlyn; Unterman, Terry; Sepkovic, Daniel W; McCann, Kenneth

    2012-08-29

    Studies have shown associations of diabetes and endogenous hormones with exposure to a wide variety of organochlorines. We have previously reported positive associations of polychlorinated biphenyls (PCBs) and inverse associations of selected steroid hormones with diabetes in postmenopausal women previously employed in a capacitor manufacturing plant. This paper examines associations of PCBs with diabetes and endogenous hormones in 63 men previously employed at the same plant who in 1996 underwent surveys of their exposure and medical history and collection of bloods and urine for measurements of PCBs, lipids, liver function, hematologic markers and endogenous hormones. PCB exposure was positively associated with diabetes and age and inversely associated with thyroid stimulating hormone and triiodothyronine-uptake. History of diabetes was significantly related to total PCBs and all PCB functional groupings, but not to quarters worked and job score, after control for potential confounders. None of the exposures were related to insulin resistance (HOMA-IR) in non-diabetic men. Associations of PCBs with specific endogenous hormones differ in some respects from previous findings in postmenopausal women employed at the capacitor plant. Results from this study, however, do confirm previous reports relating PCB exposure to diabetes and suggest that these associations are not mediated by measured endogenous hormones.

  20. Study on microstructure and high temperature wear resistance of laser cladded nuclear valve clack

    International Nuclear Information System (INIS)

    Zhang Chunliang; Chen Zichen

    2002-01-01

    Laser cladding of Co-base alloy on the nuclear valve-sealing surface are performed with a 5 kW CO 2 transverse flowing laser. The microstructure and the high temperature impact-slide wear resistance of the laser cladded coating and the plasma cladded coating are studied. The results show that the microstructure, the dilution rate and the high temperature impact-slide wear resistance of the laser cladded coating have obvious advantages over the spurt cladding processing

  1. Conformational reduction of DOPA in the gas phase studied by laser desorption supersonic jet laser spectroscopy.

    Science.gov (United States)

    Ishiuchi, Shun-ichi; Mitsuda, Haruhiko; Asakawa, Toshiro; Miyazaki, Mitsuhiko; Fujii, Masaaki

    2011-05-07

    The conformational reduction in catecholamine neurotransmitters was studied by resonance enhanced multi photon ionization (REMPI), ultraviolet-ultraviolet (UV-UV) hole burning and infrared (IR) dip spectroscopy with applying a laser desorption supersonic jet technique to DOPA, which is one of the catecholamine neurotransmitters and has one more phenolic OH group than tyrosine. It is concluded that DOPA has a single observable conformer in the gas phase at low temperature. Quantum chemical calculations at several levels with or without the dispersion correction were also carried out to study stable conformations. From the comparison between the computational IR spectra and the experimental ones, the most stable structure was determined. It is strongly suggested that the conformational reduction is caused by electrostatic interactions, such as a dipole-dipole interaction, between the chain and OH groups. This journal is © the Owner Societies 2011

  2. Small laser spot versus standard laser spot photodynamic therapy for idiopathic choroidal neovascularization: a randomized controlled study.

    Science.gov (United States)

    Li, Xiao-xin; Tao, Yong

    2012-12-01

    Idiopathic choroidal neovascularization (ICNV) affects young patients and thus may have a significant impact on vision and life quality over a patient's lifespan. This study was designed to compare the visual outcome and retinal pigment epithelium (RPE) damage after photodynamic therapy (PDT) with small laser spot and PDT with standard laser spot for idiopathic choroidal neovascularization (ICNV). This was a randomized controlled study. Fifty-two patients with ICNV were enrolled and randomly divided into a study group (small laser spot PDT, n = 27) and a control group (standard laser spot PDT, n = 25). Best corrected visual acuity (BCVA), optic coherence tomography (OCT) and fluorescein angiography (FA) findings were the main measurements. The patients were followed up 1 week, 1, 3, 6, 9 months and 1 year after PDT. BCVA improvement was statistically significantly higher in the study group than the control group at 6-month ((25.53 ± 15.01) letters vs. (14.71 ± 11.66) letters, P = 0.025) and 9-month follow-ups ((27.53 ± 17.78) letters vs. (15.59 ± 12.21) letters, P = 0.039). At 3- and 6-month follow-ups, the quadrants of RPE damage between the two groups varied significantly (P laser spot PDT group than in the standard laser spot PDT group for ICNV.

  3. STUDIES ON WETTABILITY OF STAINLESS STEEL 316L POWDER IN LASER MELTING PROCESS

    Directory of Open Access Journals (Sweden)

    KURIAN ANTONY

    2014-10-01

    Full Text Available Laser sintering is one of the techniques used in additive manufacturing processes. The main objective of the work is to study the effects of process parameters on wetting phenomenon and interfacial energy during laser melting of stainless steel powder. This paper reports wetting of laser melted powder particles and its use for the determination of surface energy of stainless steel powder under laser beam exposure. Process parameters such as laser power, scan speed and beam diameter are considered for study. This study also identifies the process parameters for better wettability which produces smooth surfaces.

  4. Alternative wavelengths for sutureless laser microvascular anastomosis: a preliminary study on acute samples.

    Science.gov (United States)

    Bass, L S; Oz, M C; Libutti, S K; Treat, M R

    1992-06-01

    Attempts to improve the speed and patency of microvascular anastomosis with laser-assisted techniques have provided a modest reduction in operative time and comparable success rates. Using sutureless microvascular anastomoses, 30 end-to-end anastomoses were created in the rat carotid artery using the gallium-aluminum-arsenide diode laser (808 nm). Indocyanine green and fibrinogen were applied to enhance tissue absorption of the laser energy and strengthen the bond created. These were compared with previously reported welds using the THC:YAG laser (2150 nm). Mean welding times were 140 and 288 s, and mean bursting pressures immediately after welding were 515 and 400 mmHg for the diode and THC:YAG laser groups, respectively. Histologically, both lateral and vertical spread of thermal damage was limited. Since both lasers create welds of adequate initial strength without stay sutures and are faster and easier to use than existing systems, evaluation of long-term patency would be worthwhile.

  5. Experimental studies of the laser-controlled collective ion accelerator

    International Nuclear Information System (INIS)

    Destler, W.W.; Rodgers, J.; Segalov, Z.

    1989-01-01

    Detailed experimental studies of a collective acceleration experiment in which a time-sequenced laser-generated ionization channel is used to control the propagation of an intense relativistic electron beamfront are presented. Ions trapped in the potential well at the beamfront are accelerated as the velocity of the beamfront is increased in a manner controlled by the time-dependent axial extent of the ionization channel. Beamfront propagation data for two different accelerating gradients are presented, together with results of ion acceleration studies for both gradients

  6. Quantifying the influence of previously burned areas on suppression effectiveness and avoided exposure: A case study of the Las Conchas Fire

    Science.gov (United States)

    Matthew P. Thompson; Patrick Freeborn; Jon D. Rieck; Dave Calkin; Julie W. Gilbertson-Day; Mark A. Cochrane; Michael S. Hand

    2016-01-01

    We present a case study of the Las Conchas Fire (2011) to explore the role of previously burned areas (wildfires and prescribed fires) on suppression effectiveness and avoided exposure. Methodological innovations include characterisation of the joint dynamics of fire growth and suppression activities, development of a fire line effectiveness framework, and...

  7. Study of some physical aspects previous to design of an exponential experiment; Estudio de algunos aspectos fisicos previos al diseno de una experiencia exponencial

    Energy Technology Data Exchange (ETDEWEB)

    Caro, R; Francisco, J L. de

    1961-07-01

    This report presents the theoretical study of some physical aspects previous to the design of an exponential facility. The are: Fast and slow flux distribution in the multiplicative medium and in the thermal column, slowing down in the thermal column, geometrical distribution and minimum needed intensity of sources access channels and perturbations produced by possible variations in its position and intensity. (Author) 4 refs.

  8. Laser Raman Spectroscopy in studies of corrosion and electrocatalysis

    International Nuclear Information System (INIS)

    Melendres, C.A.

    1988-01-01

    Laser Raman Spectroscopy (LRS) has become an important tool for the in-situ structural study of electrochemical systems and processes in recent years. Following a brief introduction of the experimental techniques involved in applying LRS to electrochemical systems, we survey the literature for examples of studies in the inhibition of electrode reactions by surface films (e.g., corrosion and passivation phenomena) as well as the acceleration of reactions by electro-sorbates (electrocatalysis). We deal mostly with both normal and resonance Raman effects on fairly thick surface films in contrast to surface-enhanced Raman investigations of monolayer adsorbates, which is covered in another lecture. Laser Raman spectroelectrochemical studies of corrosion and film formation on such metals as Pb, Ag, Fe, Ni, Co, Cr, Au, stainless steel, etc. in various solution conditions are discussed. Further extension of the technique to studies in high-temperature and high-pressure aqueous environments is demonstrated. Results of studies of the structure of corrosion inhibitors are also presented. As applications of the LRS technique in the area of electrocatalysis, we cite studies of the structure of transition metal macrocyclic compounds, i.e., phthalocyanines and porphyrins, used for catalysis of the oxygen reduction reaction. 104 refs., 20 figs

  9. Turbulence characterization by studying laser beam wandering in a differential tracking motion setup

    Science.gov (United States)

    Pérez, Darío G.; Zunino, Luciano; Gulich, Damián; Funes, Gustavo; Garavaglia, Mario

    2009-09-01

    The Differential Image Motion Monitor (DIMM) is a standard and widely used instrument for astronomical seeing measurements. The seeing values are estimated from the variance of the differential image motion over two equal small pupils some distance apart. The twin pupils are usually cut in a mask on the entrance pupil of the telescope. As a differential method, it has the advantage of being immune to tracking errors, eliminating erratic motion of the telescope. The Differential Laser Tracking Motion (DLTM) is introduced here inspired by the same idea. Two identical laser beams are propagated through a path of air in turbulent motion, at the end of it their wander is registered by two position sensitive detectors-at a count of 800 samples per second. Time series generated from the difference of the pair of centroid laser beam coordinates is then analyzed using the multifractal detrended fluctuation analysis. Measurements were performed at the laboratory with synthetic turbulence: changing the relative separation of the beams for different turbulent regimes. The dependence, with respect to these parameters, and the robustness of our estimators is compared with the non-differential method. This method is an improvement with respect to previous approaches that study the beam wandering.

  10. Study of inverse methods in remote sensing with laser

    International Nuclear Information System (INIS)

    Jesus, Wellington Carlos de

    2009-01-01

    The Laboratory of Environmental Applications of Lasers at IPEN realizes a study about atmospherics properties, such as extinction and backscattering coefficient. These coefficient are estimated by an inverse method, whose estimate quality is difficult to measure. This work presents a method with good statistic approach to retrieval the same coefficients. The new method, however, offers a number of advantages compared to the first method in use, including (1) the ability to incorporate different kinds of information under a common retrieval philosophy and (2) the method provides number of ways for evaluating the quality of the retrieval. Thus we hope improve the accuracy of estimates. (author)

  11. Facial recognition and laser surface scan: a pilot study

    DEFF Research Database (Denmark)

    Lynnerup, Niels; Clausen, Maja-Lisa; Kristoffersen, Agnethe May

    2009-01-01

    Surface scanning of the face of a suspect is presented as a way to better match the facial features with those of a perpetrator from CCTV footage. We performed a simple pilot study where we obtained facial surface scans of volunteers and then in blind trials tried to match these scans with 2D...... photographs of the faces of the volunteers. Fifteen male volunteers were surface scanned using a Polhemus FastSCAN Cobra Handheld Laser Scanner. Three photographs were taken of each volunteer's face in full frontal, profile and from above at an angle of 45 degrees and also 45 degrees laterally. Via special...

  12. Study of laser monitoring techniques of pollutants in atmosphere

    International Nuclear Information System (INIS)

    Hassan, T. A. A.

    2006-01-01

    There are several techniques used as a tool for monitoring the pollutions in the atmosphere, where the laser radiation sending through the sample of atmosphere to be investigated ether transmission or the scattering of the light, all the way through a variety of different techniques for monitoring the air quality. We are showed in this study the comparison of detection techniques through measuring the light scattered in some particular direction, rather than measuring direction the attenuation due to two type of scattering (Rayieh scattering and Mie scattering) during (optical Radar, Roman backscattering and Resonance fluorescence).(Author)

  13. Advanced diagnostics for laser plasma interaction studies and some recent experiments

    International Nuclear Information System (INIS)

    Chaurasia, S.; Munda, D.S.; Dhareshwar, L.J.

    2008-10-01

    The complete characterization of Laser plasma interaction studies related to inertial confinement fusion laser and Equation of state (EOS) studies needs many diagnostics to explain the several physical phenomena occurring simultaneously in the laser produced plasma. This involves many on ion emission are important to understand physical phenomena which are responsible for generation of laser plasma as well as its interaction with an intense laser. In this report we describe the development of various x-ray diagnostics which are used in determining temporal, spatial and spectral properties of x-rays radiated from laser produced plasma. Diagnostics which have been used in experiments for investigation of laser-produced plasma as a source of ions are also described. Techniques using an optical streak camera and VISAR which are being used in the Equation of States (EOS) studies of various materials, which are important for material science, astrophysics as well as ICF is described in details. (author)

  14. A cross-sectional study of tuberculosis drug resistance among previously treated patients in a tertiary hospital in Accra, Ghana: public health implications of standardized regimens.

    Science.gov (United States)

    Forson, Audrey; Kwara, Awewura; Kudzawu, Samuel; Omari, Michael; Otu, Jacob; Gehre, Florian; de Jong, Bouke; Antonio, Martin

    2018-04-02

    Mycobacterium tuberculosis drug resistance is a major challenge to the use of standardized regimens for tuberculosis (TB) therapy, especially among previously treated patients. We aimed to investigate the frequency and pattern of drug resistance among previously treated patients with smear-positive pulmonary tuberculosis at the Korle-Bu Teaching Hospital Chest Clinic, Accra. This was a cross-sectional survey of mycobacterial isolates from previously treated patients referred to the Chest Clinic Laboratory between October 2010 and October 2013. The Bactec MGIT 960 system for mycobactrerial culture and drug sensitivity testing (DST) was used for sputum culture of AFB smear-positive patients with relapse, treatment failure, failure of smear conversion, or default. Descriptive statistics were used to summarize patient characteristics, and frequency and patterns of drug resistance. A total of 112 isolates were studied out of 155 from previously treated patients. Twenty contaminated (12.9%) and 23 non-viable isolates (14.8%) were excluded. Of the 112 studied isolates, 53 (47.3%) were pan-sensitive to all first-line drugs tested Any resistance (mono and poly resistance) to isoniazid was found in 44 isolates (39.3%) and any resistance to streptomycin in 43 (38.4%). Thirty-one (27.7%) were MDR-TB. Eleven (35.5%) out of 31 MDR-TB isolates were pre-XDR. MDR-TB isolates were more likely than non-MDR isolates to have streptomycin and ethambutol resistance. The main findings of this study were the high prevalence of MDR-TB and streptomycin resistance among previously treated TB patients, as well as a high prevalence of pre-XDR-TB among the MDR-TB patients, which suggest that first-line and second-line DST is essential to aid the design of effective regimens for these groups of patients in Ghana.

  15. Ion beam production and study of radioactive isotopes with the laser ion source at ISOLDE

    Science.gov (United States)

    Fedosseev, Valentin; Chrysalidis, Katerina; Day Goodacre, Thomas; Marsh, Bruce; Rothe, Sebastian; Seiffert, Christoph; Wendt, Klaus

    2017-08-01

    At ISOLDE the majority of radioactive ion beams are produced using the resonance ionization laser ion source (RILIS). This ion source is based on resonant excitation of atomic transitions by wavelength tunable laser radiation. Since its installation at the ISOLDE facility in 1994, the RILIS laser setup has been developed into a versatile remotely operated laser system comprising state-of-the-art solid state and dye lasers capable of generating multiple high quality laser beams at any wavelength in the range of 210-950 nm. A continuous programme of atomic ionization scheme development at CERN and at other laboratories has gradually increased the number of RILIS-ionized elements. At present, isotopes of 40 different elements have been selectively laser-ionized by the ISOLDE RILIS. Studies related to the optimization of the laser-atom interaction environment have yielded new laser ion source types: the laser ion source and trap and the versatile arc discharge and laser ion source. Depending on the specific experimental requirements for beam purity or versatility to switch between different ionization mechanisms, these may offer a favourable alternative to the standard hot metal cavity configuration. In addition to its main purpose of ion beam production, the RILIS is used for laser spectroscopy of radioisotopes. In an ongoing experimental campaign the isotope shifts and hyperfine structure of long isotopic chains have been measured by the extremely sensitive in-source laser spectroscopy method. The studies performed in the lead region were focused on nuclear deformation and shape coexistence effects around the closed proton shell Z = 82. The paper describes the functional principles of the RILIS, the current status of the laser system and demonstrated capabilities for the production of different ion beams including the high-resolution studies of short-lived isotopes and other applications of RILIS lasers for ISOLDE experiments. This article belongs to the Focus on

  16. Comparative Study of Diode Laser Versus Neodymium-Yttrium Aluminum: Garnet Laser Versus Intense Pulsed Light for the Treatment of Hirsutism.

    Science.gov (United States)

    Puri, Neerja

    2015-01-01

    Lasers are widely used for the treatment of hirsutism. But the choice of the right laser for the right skin type is very important. Before starting with laser therapy, it is important to assess the skin type, the fluence, the pulse duration and the type of laser to be used. To compare the efficacy and side effects of Diode laser, Neodymium-yttrium aluminum - garnet (Nd: YAG) laser and intense pulsed light (IPL) on 30 female patients of hirsutism. Thirty female patients with hirsutism were selected for a randomised controlled study. The patients were divided into three groups of 10 patients each. In group I patients diode laser was used, in group II patients long pulsed Nd: YAG laser was used and in group III, IPL was used. The patients were evaluated and result graded according to a 4-point scale as excellent, >75% reduction; good, 50-75% reduction; fair; 25-50% reduction; and poor, diode laser group, followed by 35% hair reduction in the Nd: Yag laser group and 10% hair reduction in the IPL group. The percentage of hair reduction after four sessions of treatment was maximum (64%) in the diode laser group, followed by 62% hair reduction in the Nd: Yag laser group and 48% hair reduction in the IPL group. The percentage of hair reduction after eight sessions of treatment was maximum (92%) in the diode laser group, followed by 90% hair reduction in the Nd: YAG group and 70% hair reduction in the IPL group. To conclude for the Indian skin with dark hairs, the diode laser still stands the test of time. But, since the diode laser has a narrow margin of safety, proper pre and post-procedure cooling is recommended. Although, the side effects of Nd: YAG laser are less as compared to the diode laser, it is less efficacious as compared to the diode laser.

  17. Raman microspectrometry of laser-reshaped rabbit auricular cartilage: preliminary study on laser-induced cartilage mineralization

    Science.gov (United States)

    Heger, Michal; Mordon, Serge R.; Leroy, Gérard; Fleurisse, Laurence; Creusy, Collette

    2006-03-01

    Laser-assisted cartilage reshaping (LACR) is a relatively novel technique designed to noninvasively and permanently restructure cartilaginous tissue. It is believed that heat-induced stress relaxation, in which a temperature-mediated disruption of H2O binding is associated with conformational alterations in the proteoglycan and collagen-rich matrix, constitutes the underlying mechanism of LACR. Several reports have suggested that laser-mediated cartilage mineralization may contribute to the permanent shape change of laser-reshaped cartilage. In an effort to validate these results in the context of Er:glass LACR, we performed a preliminary Raman microspectrometric study to characterize the crystal deposits in laser-irradiated chondrocytes and extracellular matrix. For the first time, we identified intracellular calcium sulfate deposits and extracellular calcium phosphate (apatite) crystals in laser-reshaped rabbit auricular cartilage. Calcium carbonate deposits are localized in both irradiated and nonirradiated samples, suggesting that this mineral plays no role in conformational retention. In our discussion, we elaborate on the possible molecular and cellular mechanisms responsible for intra- and extracellular crystallization, and propose a novel hypothesis on the formation of apatite, inasmuch as the biological function of this mineral (providing structure and rigidity in bones and dental enamel) may be extrapolated to the permanent shape change of laser-irradiated cartilage.

  18. Comparative in vitro study of tissue welding using a 808 nm diode laser and a Ho:YAG laser.

    Science.gov (United States)

    Ott, B; Züger, B J; Erni, D; Banic, A; Schaffner, T; Weber, H P; Frenz, M

    2001-01-01

    In vitro porcine arteries and veins have been welded end-to-end using either a 808 nm diode laser combined with an indocyanine green enhanced albumin solder, or with a continuous-wave (cw) Ho:YAG laser without biological solder. The vascular stumps were approached to each other over a coronary dilatation catheter in order to obtain a precise alignment and good coaptation. Standard histology revealed for both welding techniques lateral tissue damage between 2 and 3 mm caused by laser-induced heat. Good solder attachment to the tissue was observed by the use of a scanning electron microscope. The vessels soldered with the 808 nm diode laser using albumin solder showed considerably higher tensile strength (1 N compared to 0.3 N) than vessels welded exclusively by Ho:YAG laser radiation. In contrast, leaking pressure (350 +/- 200 mmHg) and bursting pressure (457 +/- 200 mmHg) were found to be independent of the welding technique used. This study demonstrates that fast (total welding time about 2-5 min), stable and tight microvascular anastomosis can be achieved with the use of a dye-enhanced albumin laser soldering technique and an ancillary coronary dilatation catheter.

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

    Science.gov (United States)

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

    2017-08-01

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

  20. Previously unknown species of Aspergillus.

    Science.gov (United States)

    Gautier, M; Normand, A-C; Ranque, S

    2016-08-01

    The use of multi-locus DNA sequence analysis has led to the description of previously unknown 'cryptic' Aspergillus species, whereas classical morphology-based identification of Aspergillus remains limited to the section or species-complex level. The current literature highlights two main features concerning these 'cryptic' Aspergillus species. First, the prevalence of such species in clinical samples is relatively high compared with emergent filamentous fungal taxa such as Mucorales, Scedosporium or Fusarium. Second, it is clearly important to identify these species in the clinical laboratory because of the high frequency of antifungal drug-resistant isolates of such Aspergillus species. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently been shown to enable the identification of filamentous fungi with an accuracy similar to that of DNA sequence-based methods. As MALDI-TOF MS is well suited to the routine clinical laboratory workflow, it facilitates the identification of these 'cryptic' Aspergillus species at the routine mycology bench. The rapid establishment of enhanced filamentous fungi identification facilities will lead to a better understanding of the epidemiology and clinical importance of these emerging Aspergillus species. Based on routine MALDI-TOF MS-based identification results, we provide original insights into the key interpretation issues of a positive Aspergillus culture from a clinical sample. Which ubiquitous species that are frequently isolated from air samples are rarely involved in human invasive disease? Can both the species and the type of biological sample indicate Aspergillus carriage, colonization or infection in a patient? Highly accurate routine filamentous fungi identification is central to enhance the understanding of these previously unknown Aspergillus species, with a vital impact on further improved patient care. Copyright © 2016 European Society of Clinical Microbiology and

  1. Study on Effectiveness of the chaos laser radar

    OpenAIRE

    成田, 義之; 津田, 紀生; 山田, 諄

    2003-01-01

    A laser is widely applied for measurements, since it is invented. There are two types of laser distance meter for short and long distance. For long distance, a laser radar using propagation time of laser light is used. Generally, a distance is measured from delay time using either a periodic signal or a single pulse. But the signal becomes to be buried in noise with increasing distance. A new type of chaos laser radar which processes by only an addition is proposed. This radar can quickly pro...

  2. Study on effective laser cleaning method to remove carbon layer from a gold surface

    International Nuclear Information System (INIS)

    Singh, Amol; Modi, Mohammed H; Lodha, G S; Choubey, A K; Upadhyaya, B N

    2013-01-01

    Hydrocarbon cracking and carbon contamination is a common problem in soft x-ray Synchrotron Radiation (SR) beamlines. Carbon contamination on optics is known to absorb and scatter radiation close to the C K-edge (284 eV) spectral region. The purpose of this work is to study and develop a laser cleaning method that can effectively remove the carbon contaminations without damaging the underneath gold-coated optics. The laser cleaning process is a non-contact, accurate, efficient and safe. Nd:YAG laser of 100 ns pulse duration is used for carbon cleaning. The effect of laser pulse duration, laser fluence, number of laser passes, angle of incidence and spot overlapping on the cleaning performance is studied. Cleaning effect and subsequent film quality after laser irradiation is analyzed using x-ray photoelectron spectroscopy (XPS) and soft x-ray reflectivity (SXR) techniques.

  3. Is email a reliable means of contacting authors of previously published papers? A study of the Emergency Medicine Journal for 2001.

    Science.gov (United States)

    O'Leary, F

    2003-07-01

    To determine whether it is possible to contact authors of previously published papers via email. A cross sectional study of the Emergency Medicine Journal for 2001. 118 articles were included in the study. The response rate from those with valid email addresses was 73%. There was no statistical difference between the type of email address used and the address being invalid (p=0.392) or between the type of article and the likelihood of a reply (p=0.197). More responses were obtained from work addresses when compared with Hotmail addresses (86% v 57%, p=0.02). Email is a valid means of contacting authors of previously published articles, particularly within the emergency medicine specialty. A work based email address may be a more valid means of contact than a Hotmail address.

  4. Femtosecond study of laser dyes soluble in water: coumarins

    International Nuclear Information System (INIS)

    Cassara, Laurence

    1996-01-01

    Coumarins build up one of the great families of laser dyes, and this research thesis addresses the study of four water-soluble coumarins (ATC, DMATC, DATC, and CHOS) which are analogue to conventional coumarins (C120, C311, C1, and C102). These molecules are made water-soluble by substitution of the methyl group in position 4 by a polyether group. Mechanisms of deactivation are studied by means of time-resolved fluorescence and transient adsorption methods which allow the reaction dynamics of coumarins after light excitation to be studied. Several time scales, from femto- to nano-second, have been reached and allowed various processes to be studied: relaxation, solvation dynamics, solute orientation diffusion, process of deactivation of radiative and non-radiative relaxation in various solvents [fr

  5. Equation of state study of Laser Megajoule capsules ablator materials

    International Nuclear Information System (INIS)

    Colin-Lalu, Pierre

    2016-01-01

    This PhD thesis enters the field of inertial confinement fusion studies. In particular, it focuses on the equation of state tables of ablator materials synthesized on LMJ capsules. This work is indeed aims at improving the theoretical models introduced into the equation of state tables. We focused in the Mbar-eV pressure-temperature range because it can be access on kJ-scale laser facilities.In order to achieve this, we used the QEOS model, which is simple to use, configurable, and easily modifiable.First, quantum molecular dynamics (QMD) simulations were performed to generate cold compression curve as well as shock compression curves along the principal Hugoniot. Simulations were compared to QEOS model and showed that atomic bond dissociation has an effect on the compressibility. Results from these simulations are then used to parametrize the Grueneisen parameter in order to generate a tabulated equation of state that includes dissociation. It allowed us to show its influence on shock timing in a hydrodynamic simulation.Second, thermodynamic states along the Hugoniot were measured during three experimental campaigns upon the LULI2000 and GEKKO XII laser facilities. Experimental data confirm QMD simulations.This study was performed on two ablator materials which are an undoped polymer CHO, and a silicon-doped polymer CHOSi. Results showed universal shock compression properties. (author) [fr

  6. Previous dropout from diabetic care as a predictor of patients' willingness to use mobile applications for self-management: A cross-sectional study.

    Science.gov (United States)

    Yamaguchi, Satoko; Waki, Kayo; Tomizawa, Nobuko; Waki, Hironori; Nannya, Yasuhito; Nangaku, Masaomi; Kadowaki, Takashi; Ohe, Kazuhiko

    2017-07-01

    Preventing dropout is crucial in managing diabetes. Accordingly, we investigated whether patients who had dropped out of diabetic care are suitable candidates for the use of mobile technologies - such as smartphone applications - to support self-management (mHealth), which might help prevent dropout. We carried out a cross-sectional study in Tokyo, Japan. Patients aged 20 years or older who were clinically diagnosed as diabetic and who regularly visited the outpatient unit at the University of Tokyo Hospital were recruited between August 2014 and March 2015. Data were collected through face-to-face structured interviews, physical measurements and medical records. Participants were asked whether they were willing to use mHealth after being shown DialBetics - an mHealth application for diabetics - as an example, and about their history of dropout and previous mHealth experience. Data were analyzed by multivariate logistic regression models. Of 307 patients with type 1 and type 2 diabetes, 34 (11.1%) had previously dropped out from diabetic care. Multivariate analysis identified previous mHealth experience as a negative predictor of dropout (odds ratio 0.211, P = 0.023). Of those 34 patients, 27 (79.4%) expressed willingness to use mHealth, a significantly higher percentage than for those who had never dropped out (51.5%, P = 0.002). After adjusting for confounders, history of dropout remained a strong predictor of willingness (odds ratio 3.870, P = 0.004). Patients who previously dropped out of diabetic care are suitable candidates for mHealth. Future studies must evaluate whether mHealth is effective for preventing repeated dropout and improving glycemic control among this population. © 2016 The Authors. Journal of Diabetes Investigation published by Asian Association for the Study of Diabetes (AASD) and John Wiley & Sons Australia, Ltd.

  7. A comparative study of modified transcanalicular diode laser dacryocystorhinostomy versus conventional transcanalicular diode laser dacryocystorhinostomy.

    Science.gov (United States)

    Feijó, Eduardo Damous; Caixeta, Juliana Alves; de Souza Nery, Ana Carla; Limongi, Roberto Murillo; Matayoshi, Suzana

    2017-08-01

    External dacryocystorhinostomy (DCR) is the gold standard surgical technique for the treatment of primary acquired nasolacrimal duct obstruction (PANDO). However, new techniques such as endoscopic DCR and transcanalicular dacryocystorhinostomy (T-DCR) are being studied in an attempt to reduce surgical time, avoid external scarring and preserve the lacrimal pump while achieving the same efficacy. The purpose of this study was to compare the efficacy between conventional T-DCR and modified transcanalicular dacryocystorhinostomy (MT-DCR) in patients with PANDO. MT-DCR is performed to remove nasal mucosa prior to laser osteotomy. This is a comparative, prospective, interventionist and randomized study. Patients with PANDO were selected to undergo MT-DCR or T-DCR by blocked randomization. PANDO was diagnosed based on clinical presentation, dye disappearance test and dacryocystography. All of the procedures were performed by the same surgery team members. Anatomical success outcome was defined as positive lacrimal syringing and functional success outcome was defined as the absence or improvement of epiphora. A total of 44 surgical procedures were performed (22 MT-DCR and 22 T-DCR). In the case of MT-DCR, the anatomical and functional success rates after 12 months were 90 and 86%, respectively. After T-DCR, these rates were 77 and 72%, respectively (p = 0.162). MT-DCR and T-DCR are both safe and fast procedures with low morbidity and well-tolerated.

  8. Mortality and cardiovascular risk associated with different insulin secretagogues compared with metformin in type 2 diabetes, with or without a previous myocardial infarction: a nationwide study

    DEFF Research Database (Denmark)

    Schramm, Tina Ken; Gislason, Gunnar Hilmar; Vaag, Allan

    2011-01-01

    Aims The impact of insulin secretagogues (ISs) on long-term major clinical outcomes in type 2 diabetes remains unclear. We examined mortality and cardiovascular risk associated with all available ISs compared with metformin in a nationwide study. Methods and results All Danish residents >20 years......, initiating single-agent ISs or metformin between 1997 and 2006 were followed for up to 9 years (median 3.3 years) by individual-level linkage of nationwide registers. All-cause mortality, cardiovascular mortality, and the composite of myocardial infarction (MI), stroke, and cardiovascular mortality...... associated with individual ISs were investigated in patients with or without previous MI by multivariable Cox proportional-hazard analyses including propensity analyses. A total of 107 806 subjects were included, of whom 9607 had previous MI. Compared with metformin, glimepiride (hazard ratios and 95...

  9. Process Studies on Laser Welding of Copper with Brilliant Green and Infrared Lasers

    OpenAIRE

    Engler, Sebastian; Ramsayer, Reiner; Poprawe, Reinhart

    2011-01-01

    Copper materials are classified as difficult to weld with state-of-the-art lasers. High thermal conductivity in combination with low absorption at room temperature require high intensities for reaching a deep penetration welding process. The low absorption also causes high sensitivity to variations in surface conditions. Green laser radiation shows a considerable higher absorption at room temperature. This reduces the threshold intensity for deep penetration welding significantly. The influen...

  10. Narrow-linewidth Si/III-V lasers: A study of laser dynamics and nonlinear effects

    Science.gov (United States)

    Vilenchik, Yaakov Yasha

    Narrow-linewidth lasers play an important role in a wide variety of applications, from sensing and spectroscopy to optical communication and on-chip clocks. Current narrow-linewidth systems are usually implemented in doped fibers and are big, expensive, and power-hungry. Semiconductor lasers compete favorably in size, cost, and power consumption, but their linewidth is historically limited to the sub-MHz regime. However, it has been recently demonstrated that a new design paradigm, in which the optical energy is stored away from the active region in a composite high-Q resonator, has the potential to dramatically improve the coherence of the laser. This work explores this design paradigm, as applied on the hybrid Si/III-V platform. It demonstrates a record sub-KHz white-noise-floor linewidth. It further shows, both theoretically and experimentally, that this strategy practically eliminates Henry's linewidth enhancement by positioning a damped relaxation resonance at frequencies as low as 70 MHz, yielding truly quantum limited devices at frequencies of interest. In addition to this empirical contribution, this work explores the limits of performance of this platform. Here, the effect of two-photon-absorption and free-carrier-absorption are analyzed, using modified rate equations and Langevin force approach. The analysis predicts that as the intra-cavity field intensity builds up in the high-Q resonator, non-linear effects cause a new domain of performance-limiting factors. Steady-state behavior, laser dynamics, and frequency noise performance are examined in the context of this unique platform, pointing at the importance of nonlinear effects. This work offers a theoretical model predicting laser performance in light of nonlinear effects, obtaining a good agreement with experimental results from fabricated high-Q Si/III-V lasers. In addition to demonstrating unprecedented semiconductor laser performance, this work establishes a first attempt to predict and demonstrate

  11. Laser Spectroscopy Studies in the Neutron-Rich Sn Region

    CERN Multimedia

    Obert, J

    2002-01-01

    We propose to use the powerful laser spectroscopy method to determine the magnetic moment $\\mu$ and the variation of the mean square charge radius ($\\delta\\,\\langle$r$_{c}^{2}\\,\\rangle$) for ground and long-lived isomeric states of the Sn isotopes from A=125 to the doubly-magic $^{132}$Sn isotope and beyond. For these neutron-rich Sn nuclei, numerous $\\delta\\,\\langle$r$^{2}_{c}\\,\\rangle$ curves have already been calculated and the predictions depend upon the effective interactions used. Therefore, a study of the effect of the shell closure N=82 on the $\\delta\\,\\langle$r$^{2}_{c}\\,\\rangle$ values in the Z=50 magic nuclei is of great interest, especially because $^{132}$Sn is located far from the stability valley. It will help to improve the parameters of the effective interactions and make them more suitable to predict the properties of exotic nuclei. \\\\ \\\\The neutron-rich Sn isotopes produced with an uranium carbide target, are ionized using either a hot plasma ion source or the resonant ionization laser ion ...

  12. Kinetic studies following state-selective laser excitation

    International Nuclear Information System (INIS)

    Keto, J.W.

    1992-01-01

    We have made measurements of state-to-state deactivation cross sections and radiative lifetimes for Xe*(6p,6p',7p) and Kr*(5p) states in xenon and krypton buffer gases. These results are relevant to kinetic models and both excimer lasers and the infrared xenon laser; and they are a significant improvement in the precision of the known radiative lifetimes. This type of experiment can now be compared with recent calculations of state-to-state collisional relaxation in rare-gases by Hickman, Huestis, and Saxon. We have also made significant progress in the study of the electronic spectra of small molecules of the rare gases. Spectra have been obtained for Xe 2 , Xe 3 , Xe 4 , and larger clusters. As guidance for the larger clusters of the rare gases we have obtained the first multiphoton spectra for excitons in condensed xenon. In collaboration with research on the multiphoton spectra of the rare gases, we have continued experiments using synchrotron radiation in collaboration with the University of Hamburg. In experiments there we have observed excitation and fluorescence spectra for single xenon atoms at the surface, within the second layer, and within the bulk of large argon clusters

  13. Cytogenetic studies with laser or X-ray exposures

    International Nuclear Information System (INIS)

    Bozduganov, A.; Genkov, P.

    1975-01-01

    Account is given of studies involving a total of 21 peripheral blood cultures given the following treatments: exposure to 20 0.13-joule pulses from an optic quantum generator (ruby), 9; exposure to 1000 R X-rays, 9; and unexposed controls, 3. Exposures were carried out on three cultures from each experimental series at each of three time intervals, namely 24 h, 48 h, and 72 h after initiation of cultures. On any day, 40 well-spread metaphases were examined. High quality metaphases were photographed and karyotyped in conformity to the Chicago Conference criteria. In the laser experiment, chromosome aberrations were observed in 65% of methaphases analyzed vs. 5.3% in controls. Anomalies encountered included aneuploidy, with hypoploid metaphases predominating, polyploidy (triploidy, tetraploidy, and partial endoreduplication), and structural alterations. The following structural chromosome rearrangements are found: acentric fragments, mostly pairs, occasionally single, including minute chromosomes; dicentric and tricentric chromosomes; interstitial deletions; and chromosome translocations. Most varied and abundant chromosome aberrations were seen in 72-h irradiated cultures. The data presented offer a new opportunity for assessing genetic lesions after laser exposure and may help to determine threshold doses. (author)

  14. Novel 755-nm diode laser vs. conventional 755-nm scanned alexandrite laser: Side-by-side comparison pilot study for thorax and axillary hair removal.

    Science.gov (United States)

    Paasch, Uwe; Wagner, Justinus A; Paasch, Hartmut W

    2015-01-01

    Alexandrite (755 nm) and diode lasers (800-810 nm) are commonly used for hair removal. The alexandrite laser technology is somewhat cumbersome whereas new diode lasers are more robust. Recently, alexandrite-like 755 nm wavelength diodes became available. To compare the efficacy, tolerability, and subject satisfaction of a 755 nm diode laser operated in conventional (HR) and non-conventional in-motion (SHR) modes with a conventional scanned alexandrite 755 nm laser for chest and axillary hair removal. A prospective, single-center, proof of principle study was designed to evaluate the safety, efficacy and handling of a 755 nm diode laser system in comparison to a standard alexandrite 755 nm scanning hair removal laser. The new 755 nm diode is suitable to be used in SHR and HR mode and has been tested for its safety, efficacy and handling in a volunteer with success. Overall, both systems showed a high efficacy in hair reduction (88.8% 755 nm diode laser vs. 77.7% 755 nm alexandrite laser). Also, during the study period, no severe adverse effects were reported. The new 755 nm diode laser is as effective and safe as the traditional 755 nm alexandrite laser. Additionally, treatment with the 755 nm diode laser with HR and SHR modes was found to be less painful.

  15. Time-resolved resonance fluorescence spectroscopy for study of chemical reactions in laser-induced plasmas.

    Science.gov (United States)

    Liu, Lei; Deng, Leimin; Fan, Lisha; Huang, Xi; Lu, Yao; Shen, Xiaokang; Jiang, Lan; Silvain, Jean-François; Lu, Yongfeng

    2017-10-30

    Identification of chemical intermediates and study of chemical reaction pathways and mechanisms in laser-induced plasmas are important for laser-ablated applications. Laser-induced breakdown spectroscopy (LIBS), as a promising spectroscopic technique, is efficient for elemental analyses but can only provide limited information about chemical products in laser-induced plasmas. In this work, time-resolved resonance fluorescence spectroscopy was studied as a promising tool for the study of chemical reactions in laser-induced plasmas. Resonance fluorescence excitation of diatomic aluminum monoxide (AlO) and triatomic dialuminum monoxide (Al 2 O) was used to identify these chemical intermediates. Time-resolved fluorescence spectra of AlO and Al 2 O were used to observe the temporal evolution in laser-induced Al plasmas and to study their formation in the Al-O 2 chemistry in air.

  16. Study on laser beam welding technology for nuclear power plants

    International Nuclear Information System (INIS)

    Chida, Itaru; Shiihara, Katsunori; Fukuda, Takeshi; Kono, Wataru; Obata, Minoru; Morishima, Yasuo

    2012-01-01

    Laser beam welding is one of the jointing processes by irradiating laser beam on the material surface locally and widely used at various industrial fields. Toshiba has developed various laser-based maintenance and repair technologies and already applied them to several existing nuclear power plants. Laser cladding is a technique to weld the corrosion resistant metal onto a substrate surface by feeding filler wire to improve the corrosion resistance. Temper-bead welding is the heat input process to provide the desired microstructure properties of welded low alloy steels without post weld heat treatment, by inducing proper heat cycle during laser welding. Both laser welding technologies would be performed underwater by blowing the shielding gas for creating the local dry area. In this report, some evaluation results of material characteristics by temper-bead welding to target at Reactor Coolant System nozzle of PWR are presented. (author)

  17. Laser damage study of material of the first wall of target chamber of the future laser Megajoule

    International Nuclear Information System (INIS)

    Dubern, Christelle

    1999-01-01

    Study on damage of carbon-like, boron carbide, and stainless steel materials by ultraviolet laser light, has been carried out at CEA/CESTA in France. This work was performed to help designing and dimensioning the target chamber of the future Laser MegaJoule (LMJ) facility to be used for Inertial Confinement Fusion research. The study revealed that depending the laser fluence, the considered materials were ablated in different manners. lt was demonstrated that at low fluence, damage of carbon-like and boron carbide occurs through a thermal-mechanical mechanism resulting in sputtering of material. At higher fluence, damage was driven by a thermal mechanism, dissipating heat inside material until phase change developed. For stainless steel material, failures were the result of heat absorption associated to physical changes only. To explain and validate the proposed mechanisms, theoretical and experimental works were performed and satisfactory results came out. (author) [fr

  18. Studies of ion acceleration in a one meter laser controlled collective accelerator

    International Nuclear Information System (INIS)

    Destler, W.W.; Rodgers, J.; Striffler, C.D.; Yao, R.L.

    1991-01-01

    The basic concept behind the Laser Controlled Beam-front Experiment has been described in detail in previous reports. In the experiment, control over the propagation of a virtual cathode at the front of an intense relativistic electron beam is achieved by a time-sequenced plasma channel produced by laser-target interactions. Ions are trapped and accelerated by the very strong electric fields (50-400 MV/m) at the virtual cathode

  19. Welding with high power fiber lasers - A preliminary study

    International Nuclear Information System (INIS)

    Quintino, L.; Costa, A.; Miranda, R.; Yapp, D.; Kumar, V.; Kong, C.J.

    2007-01-01

    The new generation of high power fiber lasers presents several benefits for industrial purposes, namely high power with low beam divergence, flexible beam delivery, low maintenance costs, high efficiency and compact size. This paper presents a brief review of the development of high power lasers, and presents initial data on welding of API 5L: X100 pipeline steel with an 8 kW fiber laser. Weld bead geometry was evaluated and transition between conduction and deep penetration welding modes was investigated

  20. Study of laser plasma emission from doped targets

    Czech Academy of Sciences Publication Activity Database

    Velardi, L.; Krása, Josef; Velyhan, Andriy; Nassisi, V.

    2012-01-01

    Roč. 83, č. 2 (2012), , "02B911-1"-"02B911-3" ISSN 0034-6748 R&D Projects: GA MŠk(CZ) 7E09092; GA MŠk(CZ) LC528 EU Projects: European Commission(XE) 228334 - LASERLAB-EUROPE Institutional research plan: CEZ:AV0Z10100523 Keywords : copper * excimer lasers * ion mobility * krypton compounds * laser ablation Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.602, year: 2012

  1. Diagnostics for studies of novel laser ion acceleration mechanisms

    OpenAIRE

    Senje, Lovisa; Yeung, Mark; Aurand, Bastian; Kuschel, Stephan; Rödel, Christian; Wagner, Florian; Li, Kun; Dromey, Brendan; Bagnoud, Vincent; Neumayer, Paul; Roth, Markus; Wahlström, Claes-Göran; Zepf, Matthew; Kuehl, Thomas; Jung, Daniel

    2014-01-01

    Diagnostic for investigating and distinguishing different laser ion acceleration mechanisms has been developed and successfully tested. An ion separation wide angle spectrometer can simultaneously investigate three important aspects of the laser plasma interaction: (1) acquire angularly resolved energy spectra for two ion species, (2) obtain ion energy spectra for multiple species, separated according to their charge to mass ratio, along selected axes, and (3) collect laser radiation reflecte...

  2. Acceleration and Orientation Jumping Performance Differences Among Elite Professional Male Handball Players With or Without Previous ACL Reconstruction: An Inertial Sensor Unit-Based Study.

    Science.gov (United States)

    Setuain, Igor; González-Izal, Miriam; Alfaro, Jesús; Gorostiaga, Esteban; Izquierdo, Mikel

    2015-12-01

    Handball is one of the most challenging sports for the knee joint. Persistent biomechanical and jumping capacity alterations can be observed in athletes with an anterior cruciate ligament (ACL) injury. Commonly identified jumping biomechanical alterations have been described by the use of laboratory technologies. However, portable and easy-to-handle technologies that enable an evaluation of jumping biomechanics at the training field are lacking. To analyze unilateral/bilateral acceleration and orientation jumping performance differences among elite male handball athletes with or without previous ACL reconstruction via a single inertial sensor unit device. Case control descriptive study. At the athletes' usual training court. Twenty-two elite male (6 ACL-reconstructed and 16 uninjured control players) handball players were evaluated. The participants performed a vertical jump test battery that included a 50-cm vertical bilateral drop jump, a 20-cm vertical unilateral drop jump, and vertical unilateral countermovement jump maneuvers. Peak 3-dimensional (X, Y, Z) acceleration (m·s(-2)), jump phase duration and 3-dimensional orientation values (°) were obtained from the inertial sensor unit device. Two-tailed t-tests and a one-way analysis of variance were performed to compare means. The P value cut-off for significance was set at P handball athletes with previous ACL reconstruction demonstrated a jumping biomechanical profile similar to control players, including similar jumping performance values in both bilateral and unilateral jumping maneuvers, several years after ACL reconstruction. These findings are in agreement with previous research showing full functional restoration of abilities in top-level male athletes after ACL reconstruction, rehabilitation and subsequent return to sports at the previous level. Copyright © 2015 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

  3. New laser-driven nuclear excitation studies. Concepts and proposals

    International Nuclear Information System (INIS)

    Drska, L.; Hanus, V.; Sinor, M.

    2010-01-01

    Complete text of publication follows. There has been a great interest in the processes of nuclear excitation and triggering in high-parameter laser-produced plasmas in recent years. A series of papers devoted to the theory of this event has been published. Several experiments have already been attempted to study the excitation of the lowest nuclear levels of medium / high-Z nuclides (Ta 181, U 235 etc.), all the same unsuccessful or inconclusive. In the first part of this paper, the situation will be overviewed and analysis of the reasons of this unsatisfactory state of affairs will be accomplished. Prospects of the possible solving of the problem by using novel / projected laser facilities (esp. LIL / PETAL, XFEL, ELI-Phase) will be outlined. Potential of the future ELI Beam Facility in the Czech Republic in this area will be stressed. In the second part, some proposals for the excitation and triggering studies using combined high-power and high-intensity LIL / PETAL system (2012) with multi-kilojoule and multi-petawatt parameters will be discussed. Results of preliminary simulations supporting the thinking about potential projects will be shown and conditions essential for meaningful effort in this area will be analyzed. Problems of realistic simulations of such experiments will be addressed. Completely novel chances for the excitation / triggering studies would be started by constructed / projected facilities XFEL (coherent X-rays ∼ 12 keV, 2014) and ELI (multi-petawatt Phase 1, 2015). Application of intense / coherent high-energy X-rays and / or intense electron / ion beams allows new experimental schemes, extends the range of nuclides to be studied and (maybe) will enable to test some new triggering methods. In the last part of the presentation some possibilities in point (esp. for ELI Beamlines), will be drawn up. Acknowledgements. This research has been supported by the Research Program no. 6840770022 of the Ministry of Education, Youth and Sports of the

  4. Space electric power design study. [laser energy conversion

    Science.gov (United States)

    Martini, W. R.

    1976-01-01

    The conversion of laser energy to electrical energy is discussed. Heat engines in which the laser heats the gas inside the engine through a window as well as heat engines in which the gas is heated by a thermal energy storage reservoir which has been heated by laser radiation are both evaluated, as well as the necessary energy storage, transmission and conversion components needed for a full system. Preliminary system concepts are presented and a recommended development program is outlined. It appears possible that a free displacer Stirling engine operating directly a linear electric generator can convert 65% of the incident laser energy into electricity.

  5. Study of underwater laser propulsion using different target materials.

    Science.gov (United States)

    Qiang, Hao; Chen, Jun; Han, Bing; Shen, Zhong-Hua; Lu, Jian; Ni, Xiao-Wu

    2014-07-14

    In order to investigate the influence of target materials, including aluminum (Al), titanium (Ti) and copper (Cu), on underwater laser propulsion, the analytical formula of the target momentum IT is deduced from the enhanced coupling theory of laser propulsion in atmosphere with transparent overlay metal target. The high-speed photography method and numerical simulation are employed to verify the IT model. It is shown that the enhanced coupling theory, which was developed originally for laser propulsion in atmosphere, is also applicable to underwater laser propulsion with metal targets.

  6. De novo adamantinomatous craniopharyngioma presenting anew in an elderly patient with previous normal CT and MRI studies: A case report and implications on pathogenesis

    Directory of Open Access Journals (Sweden)

    Amy Walker, B.S.

    2015-09-01

    Full Text Available Adamantinomatous craniopharyngiomas are histologically benign epithelial tumors which arise from embryonic remnants of the craniopharyngeal duct and Rathke’s pouch. They are thought to have a congenital origin and are histologically unique from papillary craniopharyngioma. We describe the case of an elderly male who presented with symptoms related to a large craniopharyngioma with previously normal brain magnetic resonance and computed tomography imaging studies. These findings dispute the embryogenic theory that craniopharyngiomas observed in adults develop from the persistent slow growth of embryonic remnants.

  7. An expanded study of long-pulsed 1064 nm Nd:YAG laser treatment of basal cell carcinoma.

    Science.gov (United States)

    Ortiz, Arisa E; Anderson, R Rox; DiGiorgio, Catherine; Jiang, Shang I Brian; Shafiq, Faiza; Avram, Mathew M

    2018-02-13

    Basal cell carcinoma (BCC) is an indolent form of skin cancer that is rarely life threatening, but can cause significant cosmetic and functional morbidity. Surgical treatments often result in disfiguring scars, while topical therapies frequently result in recurrence. The need for a more effective nonsurgical alternative has led to the investigation of laser treatment of BCC. We have previously conducted a pilot study which showed 100% histologic clearance at high fluences. Treatments were well tolerated with no significant adverse events. The objective of this larger study was to confirm preliminary results that the 1064 nm Nd:YAG laser is a safe and effective method for treating non-facial BCC. This is an IRB-approved, prospective, multi-center study evaluating the safety and efficacy of the 1064 nm Nd:YAG laser for the treatment of BCC on the trunk and extremities. Thirty-three subjects seeking treatment for biopsy-proven BCC that did not meet the criteria for Mohs surgery were recruited. Subjects on current anticoagulation therapy, or with a history of immunosuppression were excluded. Subjects received one treatment with the 1064 nm Nd:YAG laser as follows: 5-6 mm spot, fluence of 125-140 J/cm 2 and a pulse duration of 7-10 ms. Standard excision with 5 mm clinical margins was performed at 30 days after laser treatment to evaluate clinical and histologic clearance of BCC. Standardized photographs and adverse assessments were taken at the baseline visit, immediately after laser treatment and on the day of excision. Thirty-one subjects completed the study. BCC tumors had a 90% (28 of 31 BCC tumors) histologic clearance rate after one treatment with the long-pulsed 1064 nm Nd:YAG laser. Treatments were generally well tolerated without any anesthesia. Immediate side effects included edema and erythema. At 1-month follow-up, some patients had residual crusting. No significant adverse events occurred. The 1064 nm long-pulsed Nd:YAG laser is an

  8. Studies of Hot Crack Properties of Laser Welded Stainless Steel

    DEFF Research Database (Denmark)

    Juhl, Thomas Winther

    During the present work crack testing concerning small and fast solidifying laser welds in austenitic stainless steel has been studied. A set of methods has been applied to investigate alloy properties, including ·Application of known information to predict solidification phases from the alloy...... composition. ·Weld metal solidification rate measurements for prediction of phases. ·Various crack tests to assess the crack susceptibility of alloys. ·A combination of the above for selection of suitable, weldable alloys. The possibility of using such specific methods for alloys and applications has been...... to the crack behaviour, but do not show an expected correlation between the crack resistance and the solidification rate. The employment of pulsed seams is therefore assessed not to be usable in the present selection methods. From evaluation of several crack tests, the Weeter spot weld test has been chosen...

  9. A Comparative Study on Cutting Electrodes for Batteries with Lasers

    Science.gov (United States)

    Luetke, Matthias; Franke, Volker; Techel, Anja; Himmer, Thomas; Klotzbach, Udo; Wetzig, Andreas; Beyer, Eckhard

    E-mobility is still one of the most discussed topics within the automotive industry. Electric powered vehicles can drive emissionfree and present consequently the future propulsion. Nearly all global players in the automotive industry are making great efforts to develop cost-efficient electric drives, which are suitable for series production. The national governments support this evolution progressively. For example the mobility research programme of the Federal Republic of Germany looks at the production of Li- Ion cells in its entirety. Within this programme the cutting of electrodes for Li-Ion cells by lasers is an issue, too. This paper provides a comparative study on cutting materials relevant for Li-Ion cells with beam sources operating in a cw mode and a pulsed mode respectively.

  10. Sputtering of amorphous carbon layers studied by laser induced fluorescence

    International Nuclear Information System (INIS)

    Pasch, E.

    1992-07-01

    In order to minimize the radiation losses, it is desirable to keep the plasmas in nuclear fusion devices free of high-Z-impurities. Therefore, the walls of TEXTOR and other tokamaks are covered with thin layers of amorphous carbon layers (a-C:H) or amorphous carbon/boron layers (a-C/B:H). The sputtering behaviour of these layers has been studied under bombardment by Ar + ions with energies of 1.5 keV and current densities of a few mA/cm 2 . Investigations of these coatings were carried out with the object to measure the velocity distribution of the sputtered atoms and the sputtered yields by laser induced fluorescence in the vacuum ultraviolet. (orig.)

  11. Pulsed laser photoacoustic spectrometer for study of solid materials

    International Nuclear Information System (INIS)

    Patel, N.D.; Kartha, V.B.

    1991-01-01

    The technique of photoacoustic spectroscopy has wide applications bacause it is extremely sensitive, and can be used to obtain spectra in wide spectral range for solids, liquids, gases, solutions, crystals etc. which may be usually difficult by conventional methods. For studying a variety of materials, a pulsed laser photoacoustic spectrometer has been set up in the laboratory. The report discusses the design and performance of the instrument. Some of the spectra of materials like Nd 2 O 9 powder, Nd-YAG crystal, CoCl 2 6H 2 O etc. are shown. A detailed discussion on assignment of the spectra of Nd-YAG is also presented. (author). 4 refs., 5 figs., 1 tab

  12. Impact of Availability and Use of ART/PMTCT Services on Fertility Desires of Previously Pregnant Women in Rakai, Uganda: A Retrospective Cohort Study.

    Science.gov (United States)

    Litwin, Lindsay E; Makumbi, Frederick E; Gray, Ronald; Wawer, Maria; Kigozi, Godfrey; Kagaayi, Joseph; Nakigozi, Gertrude; Lutalo, Tom; Serwada, David; Brahmbhatt, Heena

    2015-07-01

    To assess fertility desires by availability and use of antiretroviral therapy and prevention of mother-to-child transmission (ART/PMTCT) services in Rakai, Uganda. Retrospective analyses of longitudinal data from the Rakai Community Cohort Study. Study participants were retrospectively identified and categorized by HIV status. Availability of ART/PMTCT services in Rakai was defined in three periods: (1) pre-ART/PMTCT (ART/PMTCT rollout (2005-2006), and (3) universal ART/PMTCT (>2006); and use of ART/PMTCT was coded as yes if the woman received services. Trends in fertility desires were assessed by χ. "Modified" Poisson regression was performed using generalized linear models with a log link and Poisson family to estimate prevalence rate ratios (PRRs) and 95% confidence intervals (CIs) of desire for another child among previously and currently pregnant women; PRRs were adjusted for demographic and behavioral factors. A total of 4227 sexually active women in Rakai, including 436 HIV+ women, contributed 13,970 observations over 5 survey rounds. Fertility desires increased in the population in the ART/PMTCT rollout [adjusted (adj.) PRR: 1.08, 95% CI: 1.04 to 1.13] and the universal availability periods (adj. PRR: 1.11, 95% CI: 1.08 to 1.14) compared with pre-ART/PMTCT period. A total of 862 woman observations used ART/PMTCT services. Fertility desires were similar among ART/PMTCT service users and nonusers in cross-sectional analysis (adj. PRR: 0.84, 95% CI: 0.62 to 1.14) and 1 year after ART/PMTCT use (adj. PRR: 1.27, 95% CI: 0.83 to 1.94). Availability of ART/PMTCT may increase fertility desires of previously pregnant women in Rakai, Uganda. Use of ART/PMTCT services was not correlated with fertility desires of previously or current pregnant women.

  13. ILIAS. Ion and laser beam interaction and application studies. Progress report no. 3 of the PHELIX theory group

    Energy Technology Data Exchange (ETDEWEB)

    Mulser, P. (ed.)

    2008-04-15

    The following topics are dealt with: The PHELIX laser-plasma facility, coupling of nuclear matter to intense photon fields, QED effects in strong laser fields, relativistic critical density increase in a linearly polarized laser beam, absorption of ultrashort laser pulses in strongly overdense targets, Coulomb focusing in electron-ion collisions in a strong laser field, quasiperiodic waves in relativistic plasmas, high-energy-density physics studied by intense particle beams, heavy ions in a high-power laser beam, Monte-Carlo study of electron dynamics in silicon during irradiation with an ultrashort VUV laser pulse. (HSI)

  14. ILIAS. Ion and laser beam interaction and application studies. Progress report no. 3 of the PHELIX theory group

    International Nuclear Information System (INIS)

    Mulser, P.

    2008-04-01

    The following topics are dealt with: The PHELIX laser-plasma facility, coupling of nuclear matter to intense photon fields, QED effects in strong laser fields, relativistic critical density increase in a linearly polarized laser beam, absorption of ultrashort laser pulses in strongly overdense targets, Coulomb focusing in electron-ion collisions in a strong laser field, quasiperiodic waves in relativistic plasmas, high-energy-density physics studied by intense particle beams, heavy ions in a high-power laser beam, Monte-Carlo study of electron dynamics in silicon during irradiation with an ultrashort VUV laser pulse. (HSI)

  15. Comprehensive study of electro-optic and passive Q-switching in solid state lasers for altimeter applications

    Science.gov (United States)

    Bhardwaj, Atul; Agrawal, Lalita; Pal, Suranjan; Kumar, Anil

    2006-12-01

    Laser Science and Technology Center (LASTEC), Delhi, is developing a space qualified diode pumped Nd: YAG laser transmitter capable of generating 10 ns pulses of 30 mJ energy @ 10 pps. This paper presents the results of experiments for comparative studies between electro-optic and passively Q-switched Nd: YAG laser in a crossed porro prism based laser resonator. Experimental studies have been performed by developing an economical bench model of flash lamp pumped Nd: YAG laser (rod dimension, \

  16. Theoretical study of laser feedback interferometry for dynamical material's behaviour studies

    International Nuclear Information System (INIS)

    Le-Barbier, Laura

    2017-01-01

    The purpose of this thesis is to study the feasibility of optical feedback interferometry (OFI) for measuring velocities for dynamical material's behaviour studies. Dynamical material's behaviour studies permit to analyse the shocked material when subjects to shocks (laser shocks, isentropic compression, projectiles, etc.). In these conditions, we seek to measure velocities up to 10 km/s. The OFI technique is regularly used as an embedded system to measure slow velocities in various fields. However, very few studies have been performed for determining velocities measurement limits for this system. As a matter of fact, the optical feedback induces nonlinear effects into the laser's cavity: it disrupts the laser's emitted optical power. Depending on the optical feedback strength, the laser can show chaotic behaviour, then it is no longer possible to get the information for the target's velocity or displacement regarding the signal. In this study, we have been developing mathematical models and performing a wide range of numerical simulations to study the performances and the limits of the OFI technique. We have been also studying the influence of the targets reflectivity, the length and the modulation frequency of the external cavity. (author) [fr

  17. Outcome of secondary high-grade glioma in children previously treated for a malignant condition: A study of the Canadian Pediatric Brain Tumour Consortium

    International Nuclear Information System (INIS)

    Carret, Anne-Sophie; Tabori, Uri; Crooks, Bruce; Hukin, Juliette; Odame, Isaac; Johnston, Donna L.; Keene, Daniel L.; Freeman, Carolyn; Bouffet, Eric

    2006-01-01

    Background and purpose: Reports of secondary high-grade glioma (HGG) in survivors of childhood cancer are scarce. The aim of this study was to review the pattern of diagnosis, the treatment, and outcome of secondary pediatric HGG. Patients and methods: We performed a multi-center retrospective study among the 17 paediatric institutions participating in the Canadian Pediatric Brain Tumour Consortium (CPBTC). Results: We report on 18 patients (14 males, 4 females) treated in childhood for a primary cancer, who subsequently developed a HGG as a second malignancy. All patients had previously received radiation therapy +/- chemotherapy for either acute lymphoblastic leukaemia (n = 9) or solid tumour (n = 9). All HGG occurred within the previous radiation fields. At the last follow-up, 17 patients have died and the median survival time is 9.75 months. Conclusion: Although aggressive treatment seems to provide sustained remissions in some patients, the optimal management is still to be defined. Further documentation of such cases is necessary in order to better understand the pathogenesis, the natural history and the prevention of these tumours

  18. Study of XUV lasers produced by a CO/sub 2/ laser

    International Nuclear Information System (INIS)

    Daido, H.; Miura, E.; Kitagawa, Y.; Kato, Y.; Nishihara, K.; Sawai, K.; Nakai, S.S.; Yamanaka, C.

    1988-01-01

    The authors present recent progress at ILE, Osaka University in plasma recombination-pumped XUV lasers produced by a CO/sub 2/ laser. One way to produce large-population inversion with this scheme is rapid cooling of the gain medium keeping a high electron density, because the three-body recombination probability is proportional to the square of the electron density. The authors used a cylinder-type target made of 30-μm thick parylene (C/sub 8/H/sub 8/) whose diameter and length are 3 and 4 mm. The laser irradiated the 2500-A thick parylene foil attached to the center of the cylinder. The fully ablated plasma expands isotropically, producing an almost uniform plasma on the cylinder wall. Then the almost fully ionized carbon plasma is cooled by heat transport from the hot plasma to the wall. The estimated cooling time is a few nanoseconds assuming classical heat transport

  19. Study of non-thermal effects from laser radiation on live tissues

    International Nuclear Information System (INIS)

    Cotta, M.A.

    1987-02-01

    The functional biological effects related to the irradiation of live tissues with low power lasers, called non-thermal effects were theoretical and experimentally studied. For the experimental part, a device which allows to: irradiation lesions artificially created on the back of rats by a He-Ne laser, or put a moving ground glass in front of the laser beam, by irradiation of this same laser with its coherence degree decreased. The relevance of the radiation coherence in the lesion cicatrization process was shown. The electrical field distribution and the intensity distribution on a surface with micro-roughness when irradiated by coherent light are theoretically studied. (M.C.K.) [pt

  20. Experimental studies of laser guiding and wake excitation in plasma channels

    International Nuclear Information System (INIS)

    Volfbeyn, P.; Lawrence Berkeley National Lab., CA

    1998-06-01

    This thesis presents results of experimental investigations of laser guiding in plasma channels. A new technique for plasma channel creation, the Ignitor-Heater scheme was proposed and experimentally tested in hydrogen and nitrogen. It made use of two laser pulses. The Ignitor, an ultrashort ( 17 W/cm 2 , 75fs laser pulse. The guiding properties and transmission and coupling efficiency were studied as a function of relative position of the channel and the injection pulse focus. Whereas entrance coupling efficiency into the channel was lower than expected, channel coupling to continuum losses were found to be in good agreement with analytical predictions. The authors speculate that increased coupling efficiency can be achieved through better mode matching into the channel. Analytic and numerical one dimensional (1-D), nonrelativistic theory of laser pulse propagation in underdense plasma was presented, in the context of laser wakefield acceleration. The relation between the laser pulse energy depletion, longitudinal laser pulse shape distortion, and changes in the group velocity and center wavelength was explored. 1-D theory was extended to treat the case of a laser exciting a wake in a hollow plasma channel, by making use of an energy conservation argument. Based on the results of this theory, a laser wakefield diagnostic was proposed where, by measuring the changes in phase or spectrum of the driving laser pulse, it is possible to infer the amplitude of the plasma wake

  1. Experiment and simulation study of laser dicing silicon with water-jet

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Jiading; Long, Yuhong, E-mail: longyuhong@guet.edu.cn; Tong, Youqun; Yang, Xiaoqing; Zhang, Bin; Zhou, Zupeng

    2016-11-30

    Highlights: • The explosive melt expulsion could be a dominant process for the laser ablating silicon in liquids with ns-pulsed laser of 1064 nm irradiating. • Self-focusing phenomenon was found and its causes are analyzed. • SPH modeling technique was employed to understand the effect of water and water-jet on debris removal during water-jet laser machining. - Abstract: Water-jet laser processing is an internationally advanced technique, which combines the advantages of laser processing with water jet cutting. In the study, the experiment of water-jet laser dicing are conducted with ns pulsed laser of 1064 nm irradiating, and Smooth Particle Hydrodynamic (SPH) technique by AUTODYN software was modeled to research the fluid dynamics of water and melt when water jet impacting molten material. The silicon surface morphology of the irradiated spots has an appearance as one can see in porous formation. The surface morphology exhibits a large number of cavities which indicates as bubble nucleation sites. The observed surface morphology shows that the explosive melt expulsion could be a dominant process for the laser ablating silicon in liquids with nanosecond pulse laser of 1064 nm irradiating. Self-focusing phenomenon was found and its causes are analyzed. Smooth Particle Hydrodynamic (SPH) modeling technique was employed to understand the effect of water and water-jet on debris removal during water-jet laser machining.

  2. Experimental study of laser-plasma interaction physics with short laser wavelength

    International Nuclear Information System (INIS)

    Labaune, C.; Amiranoff, F.; Fabre, E.; Matthieussent, G.; Rousseaux, C.; Baton, S.

    1989-01-01

    Many non-linear processes can affect laser-plasma coupling in fusion experiments. The interaction processes of interest involve three or more waves, including the incident electromagnetic wave and various selections of electromagnetic, electrostatic and accoustic waves. Whenever plasma waves are involved (stimulated Raman scattering, two-plasmon decay instability, parametric decay instability and others), energetic electrons are created through the various damping processes of these waves: these energetic electrons in turn deleteriously affect the compression phase in laser fusion experiments through pre-heating of the fuel core. Some parametric processes lead primarily to loss of incident laser energy (stimulated Brillouin scattering) while others, such as filamentation, lead to strongly enhanced local laser intensities through the focusing of part (or all) of the laser beam into filaments of very small dimensions with a concomitant expulsion of the plasma out of these regions. So filamentation destroys the uniformity of energy deposition in the plasma and prevents high compression efficiency of the target. These interaction effects are typically of parametric nature, with their thresholds and growth rates depending critically on plasma scale lengths. Since these scale lengths increase with available laser energy and since millimeter sized plasmas are expected from reactor targets which will be used in direct drive implosion experiments, a good understanding of these processes and their saturation mechanisms becomes imperative. We report here the results on absolute energy measurements and time-resolved spectra of SRS and SBS obtained in various types of plasmas where the major changes were the inhomogeneity scale lengths. (author) 7 refs., 7 figs

  3. Application of laser resonance scattering to the study of high-temperature plasma-wall interaction

    International Nuclear Information System (INIS)

    Maeda, Mitsuo; Muraoka, Katsunori; Hamamoto, Makoto; Akazaki, Masanori; Miyazoe, Yasushi

    1981-01-01

    Studies on laser resonance scattering and its application to the study of high-temperature plasma-wall interaction are reviewed. The application of dye laser beam to resonant scattering method has been developed. This method is able to detect low density atoms. The fluorescent photon counts can be estimated for a two-level system and a three-level system. The S/N ratio, Which is in close connection with the detection limit, has been estimated. The doppler effect due to the thermal motion of atoms is taken into consideration. The calibration of the absolute number of atoms is necessary. Tunable coherent light is used as the light source for resonance scattering method. This is able to excite atoms strongly and to increase the detection efficiency. As dye lasers, a N 2 laser, a YAG laser, and a KrF excimer laser have been studied. In VUV region, rare gas or rare gas halide lasers can be used. The strong output power can be expected when the resonance lines of atoms meet the synchronizing region of the excimer laser. The resonance scattering method is applied to the detection of impurity metal atoms in plasma. The studies of laser systems for the detection of hydrogen atoms are also in progress. (Kato, T.)

  4. Process Studies on Laser Welding of Copper with Brilliant Green and Infrared Lasers

    Science.gov (United States)

    Engler, Sebastian; Ramsayer, Reiner; Poprawe, Reinhart

    Copper materials are classified as difficult to weld with state-of-the-art lasers. High thermal conductivity in combination with low absorption at room temperature require high intensities for reaching a deep penetration welding process. The low absorption also causes high sensitivity to variations in surface conditions. Green laser radiation shows a considerable higher absorption at room temperature. This reduces the threshold intensity for deep penetration welding significantly. The influence of the green wavelength on energy coupling during heat conduction welding and deep penetration welding as well as the influence on the weld shape has been investigated.

  5. Studies on 16 μm spin-flip raman lasers in Tottori University

    International Nuclear Information System (INIS)

    Miyazaki, Kazuhiko

    1986-01-01

    This report outlines the studies on 16 μm spin-flip Raman lasers which have been carried out in Tottori University, Japan. Following the introductory section, the second section of the report deals with performance of infrared lasers for molecular laser isotope separation of UF 6 . It is stressed that the wavelength of the oscillation line should be accurately controlled in the vicinity of 628 cm -1 . The third section addresses 16 μm infrared lasers. Semiconductor diode lasers of Pb 1-x Sn x Te or Pb 1-x Sn x Se are available for the infrared region around 16 μm. Though the wavelength resolution is high and the oscillation wavelength is adjustable in these lasers, their oscillation outputs are not sufficient for the purpose of uranium separation. On the other hand, there are active studies on light-excited infrared gas lasers. It seems very difficult, however, to adjust the wavelength of their oscillation lines to the infrared absorption wavelength of 235 U. Thus, attention is currently focused on Raman lasers in the region around 16 μm. The fourth section briefly summarizes studies conducted in the University during these ten-odd years and the research facilities currently used. In particular, the major part is devoted to research and development of infrared NH 3 lasers and studies on InSb SFR (spin-flip Raman) lasers pumped with an NH 3 laser. A 12.97 μm and a 13.27 μm oscillation line have been obtained with a high output, which is hoped to serve for increasing the output of the 15.9 μm line of InSb SFR lasers. (Nogami, K.)

  6. PRK by Er:YAG laser: in-vitro studies and first in-vivo experiences

    Science.gov (United States)

    Steiner, Rudolf W.; Leiacker, Richard; Russ, Detlef; Seiler, Theo

    1996-01-01

    Photorefractive keratectomy (PRK) is usually performed by an excimer laser at 193 nm wavelength. Ablatio of corneal tissue is, however, not only possible in the UV region of the optical spectrum but also in the IR where water is an excellent absorber. Therefore, an Er:YAG laser was used at 2.94 micrometer wavelength as an alternative laser light source to perform in vitro studies of corneal ablation and also first clinical experiments to correct myopia of patients with blind eyes.

  7. A thyratron-switched modular CO2 TEA laser for infrared photochemical studies

    International Nuclear Information System (INIS)

    Hamilton, N.; Kelly, J.W.; Struve, H.

    1982-09-01

    A thyratron-switched, ultraviolet pre-ionised CO 2 TEA laser, consisting of four modules connected in series, has been designed and constructed. The laser can be operated in the TEM 00 mode and is able to produce 2.5 J per pulse. The design and operation of the laser as a tool for infrared studies is discussed together with an evaluation of the effect of operating parameters on output characteristics

  8. High Intensity Laser Therapy (HILT) versus TENS and NSAIDs in low back pain: clinical study

    Science.gov (United States)

    Zati, Allesandro; Fortuna, Damiano; Valent, A.; Filippi, M. V.; Bilotta, Teresa W.

    2004-09-01

    Low back pain, caused by lumbar disc herniation, is prevalently treated with a conservative approach. In this study we valued the efficacy of High Intensity Laser Therapy (HILT), compared with accepted therapies such as TENS and NSAIDs. Laser therapy obtained similar results in the short term, but better clinical effect over time than TENS and NSAIDs. In conclusion high intensity laser therapy appears to be a interesting new treatment, worthy of further research.

  9. Laser-enhanced cavitation during high intensity focused ultrasound: An in vivo study

    OpenAIRE

    Cui, Huizhong; Zhang, Ti; Yang, Xinmai

    2013-01-01

    Laser-enhanced cavitation during high intensity focused ultrasound (HIFU) was studied in vivo using a small animal model. Laser light was employed to illuminate the sample concurrently with HIFU radiation. The resulting cavitation was detected with a passive cavitation detector. The in vivo measurements were made under different combinations of HIFU treatment depths, laser wavelengths, and HIFU durations. The results demonstrated that concurrent light illumination during HIFU has the potentia...

  10. Vitamin D deficiency in medical patients at a central hospital in Malawi: a comparison with TB patients from a previous study.

    Directory of Open Access Journals (Sweden)

    Yamikani Mastala

    Full Text Available OBJECTIVES: To determine the prevalence of vitamin D deficiency (VDD in adult medical, non-tuberculous (non-TB patients. To investigate associations with VDD. To compare the results with a similar study in TB patients at the same hospital. DESIGN: Cross-sectional sample. SETTING: Central hospital in Malawi. PARTICIPANTS: Adult non-TB patients (n = 157, inpatients and outpatients. OUTCOME MEASURES: The primary outcome was the prevalence of VDD. Potentially causal associations sought included nutritional status, in/outpatient status, HIV status, anti-retroviral therapy (ART and, by comparison with a previous study, a diagnosis of tuberculosis (TB. RESULTS: Hypovitaminosis D (≤75 nmol/L occurred in 47.8% (75/157 of patients, 16.6% (26/157 of whom had VDD (≤50 nmol/L. None had severe VDD (≤25 nmol/L. VDD was found in 22.8% (23/101 of in-patients and 5.4% (3/56 of out-patients. In univariable analysis in-patient status, ART use and low dietary vitamin D were significant predictors of VDD. VDD was less prevalent than in previously studied TB patients in the same hospital (68/161 = 42%. In multivariate analysis of the combined data set from both studies, having TB (OR 3.61, 95%CI 2.02-6.43 and being an in-patient (OR 2.70, 95%CI 1.46-5.01 were significant independent predictors of VDD. CONCLUSIONS: About half of adult medical patients without TB have suboptimal vitamin D status, which is more common in in-patients. VDD is much more common in TB patients than non-TB patients, even when other variables are controlled for, suggesting that vitamin D deficiency is associated with TB.

  11. Central Pain Processing in Early-Stage Parkinson's Disease: A Laser Pain fMRI Study.

    Directory of Open Access Journals (Sweden)

    Christine Petschow

    Full Text Available Pain is a common non-motor symptom in Parkinson's disease. As dopaminergic dysfunction is suggested to affect intrinsic nociceptive processing, this study was designed to characterize laser-induced pain processing in early-stage Parkinson's disease patients in the dopaminergic OFF state, using a multimodal experimental approach at behavioral, autonomic, imaging levels.13 right-handed early-stage Parkinson's disease patients without cognitive or sensory impairment were investigated OFF medication, along with 13 age-matched healthy control subjects. Measurements included warmth perception thresholds, heat pain thresholds, and central pain processing with event-related functional magnetic resonance imaging (erfMRI during laser-induced pain stimulation at lower (E = 440 mJ and higher (E = 640 mJ target energies. Additionally, electrodermal activity was characterized during delivery of 60 randomized pain stimuli ranging from 440 mJ to 640 mJ, along with evaluation of subjective pain ratings on a visual analogue scale.No significant differences in warmth perception thresholds, heat pain thresholds, electrodermal activity and subjective pain ratings were found between Parkinson's disease patients and controls, and erfMRI revealed a generally comparable activation pattern induced by laser-pain stimuli in brain areas belonging to the central pain matrix. However, relatively reduced deactivation was found in Parkinson's disease patients in posterior regions of the default mode network, notably the precuneus and the posterior cingulate cortex.Our data during pain processing extend previous findings suggesting default mode network dysfunction in Parkinson's disease. On the other hand, they argue against a genuine pain-specific processing abnormality in early-stage Parkinson's disease. Future studies are now required using similar multimodal experimental designs to examine pain processing in more advanced stages of Parkinson's disease.

  12. In vitro study of 960 nm high power diode laser applications in dental enamel, aided by the presence of a photoinitiator dye: scanning electron microscopy analysis

    International Nuclear Information System (INIS)

    Oliveira, Marcelo Vinicius de

    2002-06-01

    The objective of this study is to verify if a high power diode laser can effectively modify the morphology of an enamel surface, and if this can be done in a controlled fashion by changing the lasers parameters. Previous studies using SEM demonstrated that through irradiation with Nd:YAG laser (1064 nm) it is possible to modify the morphology of the dental surface in such way as to increase its resistance against caries decays. The desired procedures that should achieve a decrease of the index of caries decays and of its sequels are on a primary level, which means that action is necessary before the disease installs itself. In this study it was used for the first time a prototype of a high power diode laser operating at 960 nm, produced by the Laboratory of Development of Lasers of the Center for Lasers and Applications of the IPEN. This equipment can present several advantages as reliability, reduced size and low cost. The aim was establish parameters of laser irradiation that produce the desired effects wanted in the enamel and protocols that guarantee its safety during application in dental hard tissues, protecting it of heating effects such as fissures and carbonization. (author)

  13. Experimental study of laser-oxygen cutting of low-carbon steel using fibre and CO2 lasers under conditions of minimal roughness

    International Nuclear Information System (INIS)

    Golyshev, A A; Malikov, A G; Orishich, A M; Shulyatyev, V B

    2014-01-01

    The results of an experimental study of laser-oxygen cutting of low-carbon steel using fibre and CO 2 lasers are generalised. The dependence of roughness of the cut surface on the cutting parameters is investigated, and the conditions under which the surface roughness is minimal are formulated. It is shown that for both types of lasers these conditions can be expressed in the same way in terms of the dimensionless variables – the Péclet number Pe and the output power Q of laser radiation per unit thickness of the cut sheet – and take the form of the similarity laws: Pe = const, Q = const. The optimal values of Pe and Q are found. We have derived empirical expressions that relate the laser power and cutting speed with the thickness of the cut sheet under the condition of minimal roughness in the case of cutting by means of radiation from fibre and CO 2 lasers. (laser technologies)

  14. Kinetic studies following state-selective laser excitation: Progress report, March 15, 1988--March 14, 1989

    International Nuclear Information System (INIS)

    Keto, J.W.

    1988-11-01

    The objective of this contract is the study of state-to-state, electronic energy transfer reactions following two-photon laser excitation. We have chosen to study reactions of Xe 5p 5 np because of their relevance to the XeCl excimer laser. We are studying deactivation reactions in collisions with heavy atoms such as Ar, Kr, and Xe and reactive collisions with chlorides. The reactants are excited by multiphoton laser absorption. Product channels are observed by their fluorescence, or by laser induced fluorescence using a second color laser. Reaction rates are measured by observing the time dependent decay of signals from reactant and product channels. In addition we measure interaction potentials of the reactants by laser spectroscopy where the laser induced fluorescence or ionization is measured as a function of laser wavelength (excitation spectra) or by measuring fluorescence spectra at fixed laser frequencies with monochromators. The spectra are obtained in the form of either lineshapes or individual lines from rovibrational transitions of bound states. 11 refs. 4 figs., 3 tabs

  15. Laser-activated solid protein bands for peripheral nerve repair: an vivo study.

    Science.gov (United States)

    Lauto, A; Trickett, R; Malik, R; Dawes, J M; Owen, E R

    1997-01-01

    Severed tibial nerves in rats were repaired using a novel technique, utilizing a semiconductor diode-laser-activated protein solder applied longitudinally across the join. Welding was produced by selective laser denaturation of solid solder bands containing the dye indocyanine green. An in vivo study, using 48 adult male Wistar rats, compared conventional microsuture-repaired tibial nerves with laser solder-repaired nerves. Nerve repairs were characterised immediately after surgery and after 3 months. Successful regeneration with average compound muscle action potentials of 2.5 +/- 0.5 mV and 2.7 +/- 0.3 mV (mean and standard deviation) was demonstrated for the laser-soldered nerves and the sutured nerves, respectively. Histopathology confirmed comparable regeneration of axons in laser- and suture-operated nerves. The laser-based nerve repair technique was easier and faster than microsuture repair, minimising manipulation damage to the nerve.

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

    Science.gov (United States)

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

    2006-01-01

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

  17. Study of silica coatings degradation under laser irradiation and in controlled environment

    International Nuclear Information System (INIS)

    Becker, S.

    2006-11-01

    Performances of optical components submitted to high laser intensities are usually determined by their laser-induced damage threshold. This value represents the highest density of energy (fluence) sustainable by the component before its damage. When submitted to laser fluences far below this threshold, optical performances may also decrease with time. The degradation processes depend on laser characteristics, optical materials, and environment around the component. Silica being the most used material in optics, the aim of this study was to describe and analyse the physical-chemical mechanisms responsible for laser-induced degradation of silica coatings in controlled environment. Experimental results show that degradation is due to the growth of a carbon deposit in the irradiated zone. From these results, a phenomenological model has been proposed and validated with numerical simulations. Then, several technological solutions have been tested in order to reduce the laser-induced contamination of silica coatings. (author)

  18. Laser assisted crystallization of ferromagnetic amorphous ribbons: A multimodal characterization and thermal model study

    Energy Technology Data Exchange (ETDEWEB)

    Katakam, Shravana; Santhanakrishnan, S.; Smith, Casey; Banerjee, Rajarshi; Dahotre, Narendra B. [Laboratory of Laser Materials Processing and Synthesis Department of Materials Science and Engineering University of North Texas, Denton, Texas 76207 (United States); Devaraj, Arun; Bowden, Mark; Thevuthasan, Suntharampillai [William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Ramanujan, R. V. [Schhol of Materials Science and Engineering Nanyang Technological University, Singapore 639798 (Singapore)

    2013-11-14

    This paper focuses on laser-based de-vitrification of amorphous soft magnetic Fe-Si-B ribbons and its consequent influence on the magnetic properties. Laser processing resulted in a finer scale of crystallites due to rapid heating and cooling during laser annealing compared to conventional furnace annealing process. A significant increase in saturation magnetization is observed for laser-annealed ribbons compared to both as-received and furnace annealed samples coupled with an increase in coercivity compared to the as received samples. The combined effect of thermal histories and stresses developed during laser annealing results in the formation of nano-crystalline phase along the laser track. The phase evolution is studied by micro-XRD and TEM analysis. Solute partitioning and compositional variation within the phases are obtained by Local Electrode Atom probe analysis. The evolution of microstructure is rationalized using a Finite Element based heat transfer multi-physics model.

  19. Prospective study of the 532 nm laser (KTP) versus diode laser 980 nm in the resection of hyperplastic lesions of the oral cavity

    Science.gov (United States)

    Bargiela-Pérez, Patricia; González-Merchán, Jorge; Díaz-Sánchez, Rosa; Serrera-Figallo, Maria-Angeles; Volland, Gerd; Joergens, Martin; Gutiérrez-Pérez, Jose-Luis

    2018-01-01

    Background The aim of this study is to evaluate the resection of hyperplastic lesions on the buccal mucosa comparing the 532nm laser (KTP), versus diode 980nm laser, considering pain, scarring, inflammation and drug consumption that occurred postoperatively with each lasers. Material and Methods A prospective study of consecutive series of 20 patients in two groups that presents hyperplastic lesions on the buccal mucosa. The choice of the KTP laser or diode 980nm laser for the surgery was made randomly. The power used was 1.5W in both groups in a continuous wave mode with a 320 μm optical fiber. Parameters of pain, scarring, inflammation and consumption of drugs were recorded by a Numerical Rating Scale and evaluated postoperatively. These recordings were made the day of the surgery, 24 hours after, 14 and 28 days after. Results Pain and inflammation was light - moderate. The consumption of paracetamol was somewhat higher in the diode 980nm laser versus the KTP laser after 24 hours, although data was not statistically significant; significant differences were found after 28 days in regards to pain (p = 0.023) and inflammation (p = 0.023), but always in the absence parameter so we find no pain in both lasers. Scarring in the two types of laser showed no differences along the visits, with not detected scar retractable. Conclusions Although there is a slight histological difference regarding the KTP laser in the oral soft tissues for clinical use, both wavelengths are very suitable for excision of oral fibroma. Key words:Laser surgery, Laser therapy, oral surgery, soft tissue, 980 nm diode laser, 532 nm KTP laser. PMID:29274158

  20. Study on the effect of thermal property of metals in ultrasonic-assisted laser machining

    International Nuclear Information System (INIS)

    Lee, Hu Seung; Kim, Gun Woo; Park, Jong Eun; Cho, Sung Hak; Yang, Min Yang; Park, Jong Kweon

    2015-01-01

    The laser machining process has been proposed as an advanced process for the selective fabrication of electrodes without a mask. In this study, we adapt laser machining to metals that have different thermal properties. Based on the results, the metals exhibit a different surface morphology, heat-affected zone (HAZ), and a recast layer around the machined surface according to their thermal conductivity, boiling point, and thermal diffusivity. Then, we apply ultrasonic-assisted laser machining to remove the recast layer. The ultrasonic-assisted laser machining exhibits a better surface quality in metals with higher diffusivity than those having lower diffusivity

  1. Study of x-ray emission enhancement via high contrast femtosecond laser interacting with solid foil

    International Nuclear Information System (INIS)

    Chen, Liming; Kando, Masaki; Bulanov, S.V.; Koga, James K.; Tajima, Toshiki; Xu M.H.; Yuan X.H.; Li Y.T.; Dong Q.L.; Zhang J.

    2007-01-01

    We studied the hard x-ray emission and the Kα x-ray conversion efficiency (η K ) produced by 60 fs high contrast frequency doubled Ti: sapphire laser pulse focused on Cu foil target. Cu Kα photon emission obtained with second harmonic laser pulse is more intense than the case of fundamental laser pulse. The Cu η K shows strong dependence on laser nonlinearly skewed pulse shape and reaches the maximum value 4x10 -4 with 100 fs negatively skewed pulse. It shows the electron spectrum shaping contribute to the increase of η K . (author)

  2. Plantar pressure in diabetic peripheral neuropathy patients with active foot ulceration, previous ulceration and no history of ulceration: a meta-analysis of observational studies.

    Science.gov (United States)

    Fernando, Malindu Eranga; Crowther, Robert George; Pappas, Elise; Lazzarini, Peter Anthony; Cunningham, Margaret; Sangla, Kunwarjit Singh; Buttner, Petra; Golledge, Jonathan

    2014-01-01

    Elevated dynamic plantar pressures are a consistent finding in diabetes patients with peripheral neuropathy with implications for plantar foot ulceration. This meta-analysis aimed to compare the plantar pressures of diabetes patients that had peripheral neuropathy and those with neuropathy with active or previous foot ulcers. Published articles were identified from Medline via OVID, CINAHL, SCOPUS, INFORMIT, Cochrane Central EMBASE via OVID and Web of Science via ISI Web of Knowledge bibliographic databases. Observational studies reporting barefoot dynamic plantar pressure in adults with diabetic peripheral neuropathy, where at least one group had a history of plantar foot ulcers were included. Interventional studies, shod plantar pressure studies and studies not published in English were excluded. Overall mean peak plantar pressure (MPP) and pressure time integral (PTI) were primary outcomes. The six secondary outcomes were MPP and PTI at the rear foot, mid foot and fore foot. The protocol of the meta-analysis was published with PROPSERO, (registration number CRD42013004310). Eight observational studies were included. Overall MPP and PTI were greater in diabetic peripheral neuropathy patients with foot ulceration compared to those without ulceration (standardised mean difference 0.551, 95% CI 0.290-0.811, pdiabetic peripheral neuropathy with a history of foot ulceration compared to those with diabetic neuropathy without a history of ulceration. More homogenous data is needed to confirm these findings.

  3. Modeling and Implementing Nonlinear Equations in Solid-State Lasers for Studying their Performance

    Directory of Open Access Journals (Sweden)

    Ali Roudehghat Shotorbani

    2018-05-01

    Full Text Available In this paper, the effect of radius variation of beam light on output efficacy of SFD Yttrium aluminium borate laser doped with Neodymium ion, which is simultaneously a non-linear and active laser crystal, is investigated in a double-pass cavity. This is done with a concave lens that concentrates (Reduction of optical radius within nonlinear material as much optical laser as possible, resulting in increasing the laser efficiency, second harmonic and the population inversion difference. In this study, we first developed five discrete differential equations describing the interactions of 807 nm pump beam, 1060nm laser beam and 530nm second harmonic beam. Output efficiencies of laser and second harmonic beams at pumping power of Pp =20W and beam radius of 5μm have been presented. Meanwhile, in this paper, the first experiment for creating second harmonic in solid state lasers was fully described with a figure and its procedure was investigated and then the equations (second harmonic and laser and population inversion were studied. Radius variation of beam light aims at increasing laser output efficacy and improving second harmonic and population inversion. The analytic methods which have been solved the discrete differential equations via Matlab.

  4. Phase II study of a 3-day schedule with topotecan and cisplatin in patients with previously untreated small cell lung cancer and extensive disease

    DEFF Research Database (Denmark)

    Sorensen, M.; Lassen, Ulrik Niels; Jensen, Peter Buhl

    2008-01-01

    INTRODUCTION: Treatment with a topoisomerase I inhibitor in combination with a platinum results in superior or equal survival compared with etoposide-based treatment in extensive disease small cell lung cancer (SCLC). Five-day topotecan is inconvenient and therefore shorter schedules of topotecan...... and cisplatin are needed. The aim of this phase II study was to establish the response rate and response duration in chemo-naive patients with SCLC receiving a 3-day topotecan and cisplatin schedule. METHODS: Simons optimal two-stage design was used. Patients with previously untreated extensive disease SCLC...... age was 59 (range 44-74), 79% had performance status 0 or 1. Thirty-one patients completed all six cycles. Grade 3/4 anemia, neutrocytopenia, and thrombocytopenia were recorded in 9.5%, 66.7%, and 21.4% of patients, respectively. Fourteen percent of patients experienced neutropenic fever. No episodes...

  5. EXPERIMENTAL CHALLENGE STUDY OF FV3-LIKE RANAVIRUS INFECTION IN PREVIOUSLY FV3-LIKE RANAVIRUS INFECTED EASTERN BOX TURTLES (TERRAPENE CAROLINA CAROLINA) TO ASSESS INFECTION AND SURVIVAL.

    Science.gov (United States)

    Hausmann, Jennifer C; Wack, Allison N; Allender, Matthew C; Cranfield, Mike R; Murphy, Kevin J; Barrett, Kevin; Romero, Jennell L; Wellehan, James F X; Blum, Stella A; Zink, M Christine; Bronson, Ellen

    2015-12-01

    The Maryland Zoo in Baltimore experienced an outbreak of Frog virus-3 (FV3)-like ranavirus during the summer of 2011, during which 14 of 27 (52%) of its captive eastern box turtles (Terrapene carolina carolina) survived. To assess survival, immunity, and viral shedding, an experimental challenge study was performed in which the surviving, previously infected turtles were reinfected with the outbreak strain of FV3-like ranavirus. Seven turtles were inoculated with virus intramuscularly and four control turtles received saline intramuscularly. The turtles were monitored for 8 wk with blood and oral swabs collected for quantitative polymerase chain reaction (qPCR). During that time, one of seven (14%) inoculated turtles and none of the controls (0%) died; there was no significant difference in survival. Clinical signs of the inoculated turtles, except for the turtle that died, were mild compared to the original outbreak. Quantitative PCR for FV3-like ranavirus on blood and oral swabs was positive for all inoculated turtles and negative for all controls. The turtle that died had intracytoplasmic inclusion bodies in multiple organs. Three inoculated and two control turtles were euthanized at the end of the study. No inclusion bodies were present in any of the organs. Quantitative PCR detected FV3-like ranavirus in the spleen of a control turtle, which suggested persistence of the virus. The surviving five turtles were qPCR-negative for FV3-like ranavirus from blood and oral swabs after brumation. Quantitative PCR for Terrapene herpesvirus 1 found no association between ranavirus infection and herpesvirus loads. In conclusion, previously infected eastern box turtles can be reinfected with the same strain of FV3-like ranavirus and show mild to no clinical signs but can shed the virus from the oral cavity.

  6. Trial of labour and vaginal birth after previous caesarean section: A population based study of Eastern African immigrants in Victoria, Australia.

    Science.gov (United States)

    Belihu, Fetene B; Small, Rhonda; Davey, Mary-Ann

    2017-03-01

    Variations in caesarean section (CS) between some immigrant groups and receiving country populations have been widely reported. Often, African immigrant women are at higher risk of CS than the receiving population in developed countries. However, evidence about subsequent mode of birth following CS for African women post-migration is lacking. The objective of this study was to examine differences in attempted and successful vaginal birth after previous caesarean (VBAC) for Eastern African immigrants (Eritrea, Ethiopia, Somalia and Sudan) compared with Australian-born women. A population-based observational study was conducted using the Victorian Perinatal Data Collection. Pearson's chi-square test and logistic regression analysis were performed to generate adjusted odds ratios for attempted and successful VBAC. Victoria, Australia. 554 Eastern African immigrants and 24,587 Australian-born eligible women with previous CS having singleton births in public care. 41.5% of Eastern African immigrant women and 26.1% Australian-born women attempted a VBAC with 50.9% of Eastern African immigrants and 60.5% of Australian-born women being successful. After adjusting for maternal demographic characteristics and available clinical confounding factors, Eastern African immigrants were more likely to attempt (OR adj 1.94, 95% CI 1.57-2.47) but less likely to succeed (OR adj 0.54 95% CI 0.41-0.71) in having a VBAC. There are disparities in attempted and successful VBAC between Eastern African origin and Australian-born women. Unsuccessful VBAC attempt is more common among Eastern African immigrants, suggesting the need for improved strategies to select and support potential candidates for vaginal birth among these immigrants to enhance success and reduce potential complications associated with failed VBAC attempt. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  7. Biomarker-driven trial in metastatic pancreas cancer: feasibility in a multicenter study of saracatinib, an oral Src inhibitor, in previously treated pancreatic cancer

    International Nuclear Information System (INIS)

    Arcaroli, John; Quackenbush, Kevin; Dasari, Arvind; Powell, Rebecca; McManus, Martine; Tan, Aik-Choon; Foster, Nathan R; Picus, Joel; Wright, John; Nallapareddy, Sujatha; Erlichman, Charles; Hidalgo, Manuel; Messersmith, Wells A

    2012-01-01

    Src tyrosine kinases are overexpressed in pancreatic cancers, and the oral Src inhibitor saracatinib has shown antitumor activity in preclinical models of pancreas cancer. We performed a CTEP-sponsored Phase II clinical trial of saracatinib in previously treated pancreas cancer patients, with a primary endpoint of 6-month survival. A Simon MinMax two-stage phase II design was used. Saracatinib (175 mg/day) was administered orally continuously in 28-day cycles. In the unselected portion of the study, 18 patients were evaluable. Only two (11%) patients survived for at least 6 months, and three 6-month survivors were required to move to second stage of study as originally designed. The study was amended as a biomarker-driven trial (leucine rich repeat containing protein 19 [LRRC19] > insulin-like growth factor-binding protein 2 [IGFBP2] “top scoring pairs” polymerase chain reaction [PCR] assay, and PIK3CA mutant) based on preclinical data in a human pancreas tumor explant model. In the biomarker study, archival tumor tissue or fresh tumor biopsies were tested. Biomarker-positive patients were eligible for the study. Only one patient was PIK3CA mutant in a 3′ untranslated region (UTR) portion of the gene. This patient was enrolled in the study and failed to meet the 6-month survival endpoint. As the frequency of biomarker-positive patients was very low (<3%), the study was closed. Although we were unable to conclude whether enriching for a subset of second/third line pancreatic cancer patients treated with a Src inhibitor based on a biomarker would improve 6-month survival, we demonstrate that testing pancreatic tumor samples for a biomarker-driven, multicenter study in metastatic pancreas cancer is feasible

  8. Krypton fluoride laser mirror study. Final report, October 1978-November 1979

    International Nuclear Information System (INIS)

    Flint, B.K.; Najmi, A.; Stelmack, L.A.

    1979-12-01

    Rare gas halide lasers at 193 and 248/nm will require lower-loss optics if mirrors ad windows are not to be limiting factors in advanced DOE applications in laser fusion and photochemistry. This project addresses this problem in a number of ways, including materials investigations, test coatings, and fabrication of new uv laser coating designs, as described in more detail in the previous quarterly reports. Described in the final report are the process of making uv laser mirrors and the experimental strategy for attempting to improve them. Materials research is essential, and included selection and deposition of several condidate materials and an approximate ranking of their optical properties, so that new material combinations could be chosen, computer simulated, and deposited using improved vacuum techniques. Analysis of the electric fields within a laser mirror were employed to lower coating loss. A summary of test data is included, along with remarks on the survivability of uv laser optics, and possible future areas of inquiry, if truly low-loss uv laser mirrors are to ever be developed

  9. Laser fusion study. Final report, volume I, study results

    International Nuclear Information System (INIS)

    1975-06-01

    The primary goal of this study was to devise, evaluate, and conceptually design a complete, end-to-end, alignment system capable of handling 30 to 32 Shiva amplifier chains to specified accuracies in space and time. A secondary goal was to accomplish the primary goal with an acceptably low development and procurement cost and with an acceptably high day-after-day performance reliability. This report presents such a system: it is comprised of sensors, actuating mechanisms, controls, and displays that perform well within the current art-state. (U.S.)

  10. The Study Of Optometry Apparatus Of Laser Speckles

    Science.gov (United States)

    Bao-cheng, Wang; Kun, Yao; Xiu-qing, Wu; Chang-ying, Long; Jia-qi, Shi; Shi-zhong, Shi

    1988-01-01

    Based on the regularity of laser speckles movement the method of exam the uncorrected eyes is determined. The apparatus with micro-computer and optical transformation is made. Its practical function is excellent.

  11. Laser ablation/ionization studies in a glow discharge

    International Nuclear Information System (INIS)

    Hess, K.R.; Harrison, W.W.

    1985-01-01

    The pin cathode glow discharge is used in the laboratory as an atomization/ionization source for a variety of applications, including solids mass spectrometry. Coupled with a tunable dye laser, the glow discharge may also serve as an atom reservoir for resonance ionization mass spectrometry in which the laser ionizes the discharge sputtered atoms. By tightly focusing the laser onto solid samples, various ablation effects may also be investigated. The laser may be used to generate an ionized plasma which may be directly analyzed by mass spectrometry. Alternatively, the ablated neutral atoms may be used in post-ablation excitation/ionization processes, in this case the glow discharge. The results of these investigations are the basis of this paper

  12. Laser ablation studies of Deposited Silver Colloids Active in SERS

    International Nuclear Information System (INIS)

    La Porte, R.T.; Moreno, D.S.; Striano, M.C.; Munnoz, M.M.; Garcia-Ramos, J.V.; Cortes, S.S.; Koudoumas, E.

    2002-01-01

    Laser ablation of deposited silver colloids, active in SERS, is carried out at three different laser wavelengths (KrF, XeCl and Nd:YAG at λ = 248, 308 and 532 nm respectively). Emission form excited neutral Ag and Na atoms, present in the ablation plume, is detected with spectral and temporal resolution. The expansion velocity of Ag in the plume is estimated in ∼1x104m s-1, Low-fluence laser ablation of the colloids yields ionized species that are analyzed by time-of-flight mass spectroscopy. Na+ and Agn+(n≤3) are observed. Composition of the mass spectra and widths of the mass peaks are found to be dependent on laser wavelength, suggesting that the dominant ablation mechanisms are different at the different wavelenghts.

  13. Women's decision-making processes and the influences on their mode of birth following a previous caesarean section in Taiwan: a qualitative study.

    Science.gov (United States)

    Chen, Shu-Wen; Hutchinson, Alison M; Nagle, Cate; Bucknall, Tracey K

    2018-01-17

    Vaginal birth after caesarean (VBAC) is an alternative option for women who have had a previous caesarean section (CS); however, uptake is limited because of concern about the risks of uterine rupture. The aim of this study was to explore women's decision-making processes and the influences on their mode of birth following a previous CS. A qualitative approach was used. The research comprised three stages. Stage I consisted of naturalistic observation at 33-34 weeks' gestation. Stage II involved interviews with pregnant women at 35-37 weeks' gestation. Stage III consisted of interviews with the same women who were interviewed postnatally, 1 month after birth. The research was conducted in a private medical centre in northern Taiwan. Using a purposive sampling, 21 women and 9 obstetricians were recruited. Data collection involved in-depth interviews, observation and field notes. Constant comparative analysis was employed for data analysis. Ensuring the safety of mother and baby was the focus of women's decisions. Women's decisions-making influences included previous birth experience, concern about the risks of vaginal birth, evaluation of mode of birth, current pregnancy situation, information resources and health insurance. In communicating with obstetricians, some women complied with obstetricians' recommendations for repeat caesarean section (RCS) without being informed of alternatives. Others used four step decision-making processes that included searching for information, listening to obstetricians' professional judgement, evaluating alternatives, and making a decision regarding mode of birth. After birth, women reflected on their decisions in three aspects: reflection on birth choices; reflection on factors influencing decisions; and reflection on outcomes of decisions. The health and wellbeing of mother and baby were the major concerns for women. In response to the decision-making influences, women's interactions with obstetricians regarding birth choices

  14. Study of geometry angles forming a coaxial nozzle to performance of laser fusion powder composition

    Directory of Open Access Journals (Sweden)

    Павло Васильович Кондрашев

    2017-06-01

    Full Text Available The main purpose of scientific and experimental research, as reflected in this work is the search for solutions and approaches aimed at improving process performance laser alloying powder composition focused laser radiation. Priori information analysis showed the complexity of the process of laser powder fusion tracks from the physical point of view with a lot of technological impacts. Therefore, in this paper we used the method of experimental design, which will allow a more accurate experimental results compared with other methods of research. Based on the experimental screening were identified most significant technological factors influence. These are: powder mass flow, the geometric configuration of the delivery means of powder composition in the area of laser processing, the speed of movement of the substrate. To study the process performance laser alloying powder compositions were applied methods of mathematical statistics, namely, was elected symmetric quasi-D-optimal plan Pisochynskoho for 3 technological factors influence that has good statistical properties and sold regression equation of second order. As a result of the measures was received mathematical model of laser powder fusion focused laser radiation in a second order polynomial. The technique demonstrated the productivity of the process of laser powder fusion focused laser radiation, obtained by using a mathematical model of the process.

  15. Study on the pathogenesis of transient intraocular pressure after laser iridectomy with Krypton laser combined with Q-switched Nd:YAG laser

    Directory of Open Access Journals (Sweden)

    Zhi-Juan Pei

    2017-12-01

    Full Text Available AIM: To study the pathogenesis of transient intraocular pressure(IOPafter laser iridectomy with Krypton laser combined with Q-switched Nd:YAG laser. METHODS: Totally 42 healthy rabbits(84 eyesprovided by the Animal Experimental Center of our hospital were selected, including 18 female rabbits, 24 male rabbits, average weight 2.24±0.31kg, and they were randomly divided into 6 groups, 7 rats in each group(14 eyes. We observed the change of intraocular pressure after laser iridectomy surgery at 20min, 2, 6, 18, 24h and the nitric oxide(NO, malondialdehyde(MDA, superoxide dismutase(SOD, 6-keto-prostaglandin(6-keto-PGF1αand nitric oxide synthase(NOScontent in aqueous. RESULTS: There was no significant difference in intraocular pressure, NO, NOS, SOD, MAD and 6-keto- PGF1α before operation(P>0.05. The intraocular pressure increased after operation, and the difference was statistically significant(PP>0.05. The levels of NO, NOS and SOD in the aqueous humor of the two groups decreased 20min, 2 and 6h after the operation(PP>0.05. The levels of MDA and 6-keto-prostaglandin in the aqueous humor increased after the operation, and the difference was statistically significant at 20min, 2 and 6h after operation(PP>0.05.CONCLUSION: The increase of transient intraocular pressure after laser iridectomy may relate to the increase of malondialdehyde, 6-keto-prostaglandin content and the decrease of superoxide dismutase and nitric oxide in the aqueous humor after operation.

  16. Kinetic studies following state-selective laser excitation

    International Nuclear Information System (INIS)

    Keto, J.W.

    1991-01-01

    During the past year, we have made measurements of state-to-state energy transfer cross sections and radiative lifetimes for Xe*(6p,6p',7p) and Kr*(5p) states in xenon and krypton buffer gases. These results are relevant to kinetic models of both excimer lasers and the infrared xenon laser; and they are a significant improvement in the precision of the known radiative lifetimes. 3 refs., 2 figs., 2 tabs

  17. Experimental study of a laser-heated solenoid

    International Nuclear Information System (INIS)

    Rutkowski, H.L.

    1975-01-01

    An experimental investigation was made of the interaction of an intense CO 2 laser beam with a column of initially uv-ionized hydrogen immersed in a steady magnetic field of up to 100 kG. Under the intense laser radiation, the gas becomes ionized and heated to temperatures as high as 150 eV (1.6 x 10 6 0 K). The primary purpose of the investigation was to determine the properties of the dense, hot plasma formed in this manner. Time and space resolved measurements of the plasma electron density were made using holographic interferometry along the axis and Mach--Zehnder interferometry across the column. The temperature was determined by measuring the decay rate of a line from CV in the quartz uv. These measurements were supplemented by streak photography to provide data on the development of the luminosity of the plasma column, radially and axially, as a function of time. From these various diagnostic techniques, it was possible to determine that a density minimum is formed on-axis within a few tens of nanoseconds after initiation of the laser pulse. This effectively produces a light pipe which traps the beam, and suggests that long columns can be formed by laser irradiation. The beam energy was efficiently absorbed and plasma loss rates appeared to be those expected from classical MHD modelling. While a completely unambiguous answer as to the mode of laser discharge propagation occurring in the experiment was not obtained, the bulk of the evidence suggests a ''bleaching wave'' rather than a laser driven detonator. In summary, the experiment was successful in demonstrating the creation of dense, slender columns by laser breakdown, in support of the ''laser-heated solenoid'' fusion concept

  18. In vitro study of morphological and chemical modification threshold of bovine dental enamel irradiated by the holmium laser

    International Nuclear Information System (INIS)

    Eduardo, Patricia Lerro de Paula

    2001-01-01

    The aim of this study is to investigate the Ho:YLF laser effects on the dental enamel surface with regards to its morphology, thermal variations during its irradiation in the pulp chamber and its increased resistance to demineralization through quantitative analysis of calcium and phosphorous atoms reactive concentrations in samples. Twenty samples of bovine enamel were used and divided in four groups: control - acidulated phosphate fluoride (APF) application followed by demineralization treatment with lactic acid; irradiation with Ho:YLF laser (100 J/cm 2 ) followed by APF topic application and demineralization treatment with lactic acid; irradiation with Ho:YLF laser (350 J/cm 2 ) followed by APF topic application and demineralization treatment with lactic acid: and irradiation with Ho:YLF laser ( 450 J/cm 2 ) followed by APF topic application and demineralization treatment with lactic acid. Ali samples were quantified according to their calcium and phosphorous atoms relative concentrations before and after the treatments above. X-Ray fluorescence spectrochemical analysis and scanning electron microscopy were carried out. It was observed an increase on the calcium and phosphorous atoms concentration ratio and therefore the enamel demineralization reduction as a result of the lactic acid treatment in the samples irradiated with the holmium laser followed by the APF application. In order to evaluate the feasibility of this study for clinical purposes, morphological changes caused by the holmium laser irradiation were analyzed. Such modifications were characterized by melted and re-solidified regions of the enamel with consequent changes on its permeability and solubility. Temperature changes of ten human pre-molars teeth irradiated with 350 J/cm 2 and 450 J/cm 2 were also monitored in the pulp chamber in real time. Temperature increases over 4,20 C did not occur. The results obtained from this study along with the results from previous researches developed at

  19. XPS studies of short pulse laser interaction with copper

    International Nuclear Information System (INIS)

    Stefanov, P.; Minkovski, N.; Balchev, I.; Avramova, I.; Sabotinov, N.; Marinova, Ts.

    2006-01-01

    The effect of laser ablation on copper foil irradiated by a short 30 ns laser pulse was investigated by X-ray photoelectron spectroscopy. The laser fluence was varied from 8 to 16.5 J/cm 2 and the velocity of the laser beam from 10 to 100 mm/s. This range of laser fluence is characterized by a different intensity of laser ablation. The experiments were done in two kinds of ambient atmosphere: air and argon jet gas. The chemical state and composition of the irradiated copper surface were determined using the modified Auger parameter (α') and O/Cu intensity ratio. The ablation atmosphere was found to influence the size and chemical state of the copper particles deposited from the vapor plume. During irradiation in air atmosphere the copper nanoparticles react with oxygen and water vapor from the air and are deposited in the form of a CuO and Cu(OH) 2 thin film. In argon atmosphere the processed copper surface is oxidized after exposure to air

  20. Study on two-color planar laser induced fluorescence thermometry

    International Nuclear Information System (INIS)

    Li Shaodan; Tan Sichao; Gao Puzhen; Lin Yuansheng

    2014-01-01

    Many of the convection heat transfer process are involved in the research of nuclear reactor thermal hydraulics. To experimentally determine the variation of the temperature field in those processes is important for the design and safety operation of the nuclear reactor. The application of the two-color planar laser induced fluorescence (PLIF) in the measurements of fluid temperature distribution is discussed in the paper. The laser dyes used here is rhodamine B (RhB) with negative temperature coefficient and fluorescein 27 (F127) with positive temperature coefficient. The beam of the laser light is adjusted to laser sheet by using the lens group. The fluid with dyes is excited by this laser sheet in a specific plane and temperature dependent fluorescence is released. The temperature field of the plane can be determined through the intensity information. Some technical aspects encountered in the application of the two-laser PLIF are discussed in the paper, such as the spectra characteristic of the dyes and the separation of the spectra. The calibration temperature is higher than the water saturation temperature (at atmosphere pressure). (authors)

  1. Study of laser plasma interactions in the relativistic regime

    International Nuclear Information System (INIS)

    Umstadter, D.

    1997-01-01

    We discuss the first experimental demonstration of electron acceleration by a laser wakefield over instances greater than a Rayleigh range (or the distance a laser normally propagates in vacuum). A self-modulated laser wakefield plasma wave is shown to have a field gradient that exceeds that of an RF linac by four orders of magnitude (E => 200 GV/m) and accelerates electrons with over 1-nC of charge per bunch in a beam with space-charge-limited emittance (1 mm-mrad). Above a laser power threshold, a plasma channel, created by the intense ultrashort laser pulse (I approx. 4 x1018 W/CM2, gamma = 1 micron, r = 400 fs), was found to increase the laser propagation distance, decrease the electron beam divergence, and increase the electron energy. The plasma wave, directly measured with coherent Thomson scattering is shown to damp-due to beam loading-in a duration of 1.5 ps or approx. 100 plasma periods. These results may have important implications for the proposed fast ignitor concept

  2. Near‐IR laser cleaning of Cu‐ based artefacts: a comprehensive study of the methodology standardization

    DEFF Research Database (Denmark)

    Hrnjic, Mahir

    2015-01-01

    . In this study, laser cleaning was performed with near-IR lasers on artificially aged copper specimens and on two copper coins coming from Bubastis (Egypt) in order to remove the patinas in a totally non invasive way. Different irradiance and different number of passes were utilised and compared. Treated surface...

  3. Numerical study of the properties of optical vortex array laser tweezers.

    Science.gov (United States)

    Kuo, Chun-Fu; Chu, Shu-Chun

    2013-11-04

    Chu et al. constructed a kind of Ince-Gaussian modes (IGM)-based vortex array laser beams consisting of p x p embedded optical vortexes from Ince-Gaussian modes, IG(e)(p,p) modes [Opt. Express 16, 19934 (2008)]. Such an IGM-based vortex array laser beams maintains its vortex array profile during both propagation and focusing, and is applicable to optical tweezers. This study uses the discrete dipole approximation (DDA) method to study the properties of the IGM-based vortex array laser tweezers while it traps dielectric particles. This study calculates the resultant force exerted on the spherical dielectric particles of different sizes situated at the IGM-based vortex array laser beam waist. Numerical results show that the number of trapping spots of a structure light (i.e. IGM-based vortex laser beam), is depended on the relation between the trapped particle size and the structure light beam size. While the trapped particle is small comparing to the beam size of the IGM-based vortex array laser beams, the IGM-based vortex array laser beams tweezers are suitable for multiple traps. Conversely, the tweezers is suitable for single traps. The results of this study is useful to the future development of the vortex array laser tweezers applications.

  4. Study of 2ω and 3/2ω harmonics in ultrashort high-intensity laser ...

    Indian Academy of Sciences (India)

    An experimental study is presented on measurements of optical spectrum of the laser light scattered from solid surface irradiated by Ti:sapphire laser pulses up to an intensity of 1.2 × 1018 W cm-2. The spectrum has well-defined peaks at wavelengths corresponding to 2 and 3/2 radiations. The spectral features vary with ...

  5. ULTRAVIOLET TRANSITIONS IN EUROPIUM STUDIED WITH A FREQUENCY-DOUBLED CW RING DYE-LASER

    NARCIS (Netherlands)

    Eliel, E.R.; Hogervorst, W.; van Leeuwen, K.A.H.; Post, B.H.

    1981-01-01

    High resolution laser spectroscopy has been applied to the study of three ultraviolet transitions in Europium at λ = 294.8, 295.1 and 295.8 nm. The tunable narrowband UV has been generated by intracavity frequency doubling in a cw ring dye laser using a temperate tuned, Brewster angled ADA crystal.

  6. Feasibility study of multipoint based laser alignment system for CLIC

    CERN Document Server

    Stern, G; Mainaud-Durand, H; Piedigrossi, D; Geiger, A

    2012-01-01

    CLIC (Compact LInear Collider) is a study for a future electron-positron collider that would allow physicists to explore a new energy region beyond the capabilities oftoday’s particle accelerators. Alignment is one of the major challenges within the CLIC study in order to achieve the high requirement of a multi-TeV center of mass colliding beam energy range (nominal 3 TeV). To reach this energy in a realistic and cost efficient scenario all accelerator components have to be aligned with an accuracy of 10 μm over a sliding window of 200 m. The demand for a straight line reference is so far based on stretched wires coupled with Wire Positioning Sensors (WPS). These solutions are currently further developed inorder to reduce the drawbacks which are mainly given by their costs and difficult implementation. However, it should be validated through inter-comparison with a solution ideally based on a different physical principle. Therefore, a new metrological approach is proposed using a laser beam as straight lin...

  7. Numerical and experimental study on multi-pass laser bending of AH36 steel strips

    Science.gov (United States)

    Fetene, Besufekad N.; Kumar, Vikash; Dixit, Uday S.; Echempati, Raghu

    2018-02-01

    Laser bending is a process of bending of plates, small sized sheets, strips and tubes, in which a moving or stationary laser beam heats the workpiece to achieve the desired curvature due to thermal stresses. Researchers studied the effects of different process parameters related to the laser source, material and workpiece geometry on laser bending of metal sheets. The studies are focused on large sized sheets. The workpiece geometry parameters like sheet thickness, length and width also affect the bend angle considerably. In this work, the effects of width and thickness on multi-pass laser bending of AH36 steel strips were studied experimentally and numerically. Finite element model using ABAQUS® was developed to investigate the size effect on the prediction of the bend angle. Microhardness and flexure tests showed an increase in the flexural strength as well as microhardness in the scanned zone. The microstructures of the bent strips also supported the physical observations.

  8. A feasibility study of a linear laser heated solenoid fusion reactor. Final report

    International Nuclear Information System (INIS)

    Steinhauer, L.C.

    1976-02-01

    This report examines the feasibility of a laser heated solenoid as a fusion or fusion-fission reactor system. The objective of this study, was an assessment of the laser heated solenoid reactor concept in terms of its plasma physics, engineering design, and commercial feasibility. Within the study many pertinent reactor aspects were treated including: physics of the laser-plasma interaction; thermonuclear behavior of a slender plasma column; end-losses under reactor conditions; design of a modular first wall, a hybrid (both superconducting and normal) magnet, a large CO 2 laser system; reactor blanket; electrical storage elements; neutronics; radiation damage, and tritium processing. Self-consistent reactor configurations were developed for both pure fusion and fusion-fission designs, with the latter designed both to produce power and/or fissile fuels for conventional fission reactors. Appendix A is a bibliography with commentary of theoretical and experimental studies that have been directed at the laser heated solenoid

  9. Marginal microleakage in vitro study on class V cavities prepared with Er:YAG laser and etched with acid or etched with Er:YAG laser and acid; Estudo in vitro da microinfiltracao marginal em cavidades classe V preparadas com laser de Er:YAG e condicionadas com acido ou com laser de Er:YAG e acido

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, Henrique Dutra Simoes

    2001-07-01

    Microleakage at the interface between the teeth and the restorative materials remains a problem with composite resin restorations. Microleakage at the gingival margins of class V cavities restorations still challenge as they are usually placed in dentin and/or cementum. Previous studies have shown that the cavity preparation with Er:YAG laser is possible. It has been reported that Er:YAG laser has ability to create irregular surface providing micromechanical retention for adhesive dental restorative materials and to improve marginal sealing. The purpose of this in vitro study was to evaluate the marginal microleakage on class V cavities prepared with Er:YAG laser and etched with acid or with Er:YAG laser and acid, in compared to those prepared and etched conventionally. Thirty human molars were divided into three groups, namely: group I - prepared with Er:YAG laser (KaVo KEY Laser II - Germany) and etched with 37% phosphoric acid; group II - prepared with Er:YAG laser and etched with Er:YAG laser and 37% phosphoric acid; group III (control group) - prepared with high speed drill and etched with 37% phosphoric acid. All cavities were treated with same adhesive system (Single Bond - 3M) and restored with the composite resin (Z100 - 3M), according to the manufacturer's instructions. The specimens were stored at 37 deg C in water for 24 hours, polished with Sof-Lex discs (3M), thermally stressed, sealed with a nail polish coating except for the area of the restoration and 1 mm around it, and immersed in a 50% aqueous solution of silver nitrate for 24 hours. After that, the specimens were rinsed in water, soaked in a photodeveloping solution and exposed to a fluorescent light for 8 hours. The teeth were embedded in an autopolymerizing resin and sectioned longitudinally using a diamond saw microtome under running water. The sections were photographed. The microleakage at the occlusal cavity and at the gingival margins of each specimen was evaluated with scores (0-3) by

  10. Marginal microleakage in vitro study on class V cavities prepared with Er:YAG laser and etched with acid or etched with Er:YAG laser and acid; Estudo in vitro da microinfiltracao marginal em cavidades classe V preparadas com laser de Er:YAG e condicionadas com acido ou com laser de Er:YAG e acido

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, Henrique Dutra Simoes

    2001-07-01

    Microleakage at the interface between the teeth and the restorative materials remains a problem with composite resin restorations. Microleakage at the gingival margins of class V cavities restorations still challenge as they are usually placed in dentin and/or cementum. Previous studies have shown that the cavity preparation with Er:YAG laser is possible. It has been reported that Er:YAG laser has ability to create irregular surface providing micromechanical retention for adhesive dental restorative materials and to improve marginal sealing. The purpose of this in vitro study was to evaluate the marginal microleakage on class V cavities prepared with Er:YAG laser and etched with acid or with Er:YAG laser and acid, in compared to those prepared and etched conventionally. Thirty human molars were divided into three groups, namely: group I - prepared with Er:YAG laser (KaVo KEY Laser II - Germany) and etched with 37% phosphoric acid; group II - prepared with Er:YAG laser and etched with Er:YAG laser and 37% phosphoric acid; group III (control group) - prepared with high speed drill and etched with 37% phosphoric acid. All cavities were treated with same adhesive system (Single Bond - 3M) and restored with the composite resin (Z100 - 3M), according to the manufacturer's instructions. The specimens were stored at 37 deg C in water for 24 hours, polished with Sof-Lex discs (3M), thermally stressed, sealed with a nail polish coating except for the area of the restoration and 1 mm around it, and immersed in a 50% aqueous solution of silver nitrate for 24 hours. After that, the specimens were rinsed in water, soaked in a photodeveloping solution and exposed to a fluorescent light for 8 hours. The teeth were embedded in an autopolymerizing resin and sectioned longitudinally using a diamond saw microtome under running water. The sections were photographed. The microleakage at the occlusal cavity and at the gingival margins of each specimen was evaluated with scores (0

  11. Comparative Evaluation of Effects of Laser Modalities on Shear Bond Strengths of Veneering Porcelains to Laser Sintered Substructures: An In Vitro Study.

    Science.gov (United States)

    Gorler, Oguzhan; Saygin, Aysegul Goze

    2017-06-01

    Laser modalities and direct metal laser sintering (DMLS) have a potential to enhance micromechanical bonding between dental super- and infrastructures. However, the effect of different manufacturing methods on the metal-ceramic bond strength needs further evaluation. We investigated the effect of surface treatment with Er:YAG, Nd:YAG, and Ho:YAG lasers on the shear bond strength (SBS) of high-fusion dental porcelains (Vita and G-Ceram) to infrastructures prepared with DMLS in vitro settings. Study specimens (n = 128) were randomly divided into study subsets (n = 8), considering treatment types applied on the surface of infrastructures, including sandblasting and selected laser modalities; infrastructure types as direct laser sintered (DLS) and Ni-Cr based; and superstructure porcelains as Vita and G-Ceram. The SBS test was performed to assess the effectiveness of surface modifications that were also examined with a stereo microscope. Considering laser procedure types, the highest SBS values were obtained by Er:YAG laser, followed by, with a decreasing efficiency, Ho:YAG laser and sandblasting procedures, and Nd:YAG laser procedure (p laser decreases the bonding of Vita and G-Ceram in all the infrastructures compared with sandblasting. Considering porcelains, the highest SBS values were obtained by Vita (p laser procedures caused surface irregularities as revealed by the stereo microscopic examination. In current experimental settings, Er:YAG laser applied to DLS infrastructure veneered with Vita porcelain increases bonding strength more distinctly, and Nd:YAG laser applied to Ni-Cr-based infrastructure veneered with G-Ceram porcelain alters bonding strength unfavorably.

  12. Hydroxyapatite thin films grown by pulsed laser deposition and matrix assisted pulsed laser evaporation: Comparative study

    Science.gov (United States)

    Popescu-Pelin, G.; Sima, F.; Sima, L. E.; Mihailescu, C. N.; Luculescu, C.; Iordache, I.; Socol, M.; Socol, G.; Mihailescu, I. N.

    2017-10-01

    Pulsed Laser Deposition (PLD) and Matrix Assisted Pulsed Laser Evaporation (MAPLE) techniques were applied for growing hydroxyapatite (HA) thin films on titanium substrates. All experiments were conducted in a reaction chamber using a KrF* excimer laser source (λ = 248 nm, τFWHM ≈ 25 ns). Half of the samples were post-deposition thermally treated at 500 °C in a flux of water vapours in order to restore crystallinity and improve adherence. Coating surface morphologies and topographies specific to the deposition method were evidenced by scanning electron, atomic force microscopy investigations and profilometry. They were shown to depend on deposition technique and also on the post-deposition treatment. Crystalline structure of the coatings evaluated by X-ray diffraction was improved after thermal treatment. Biocompatibility of coatings, cellular adhesion, proliferation and differentiation tests were conducted using human mesenchymal stem cells (MSCs). Results showed that annealed MAPLE deposited HA coatings were supporting MSCs proliferation, while annealed PLD obtained films were stimulating osteogenic differentiation.

  13. Preparation of laser micropore porcine acellular dermal matrix for skin graft: an experimental study.

    Science.gov (United States)

    Chai, Jia-Ke; Liang, Li-Ming; Yang, Hong-Ming; Feng, Rui; Yin, Hui-Nan; Li, Feng-Yu; Sheng, Zhi-Yong

    2007-09-01

    In our previous study, we used composite grafts consisting of meshed porcine acellular dermal matrix (PADM) and thin split-thickness autologous epidermis to cover full thickness burn wounds in clinical practice. However, a certain degree of contraction might occur because the distribution of dermal matrix was not uniform in burn wound. In this study, we prepare a composite skin graft consisting of PADM with the aid of laser to improve the quality of healing of burn wound. PADM was prepared by the trypsin/Triton X-100 method. Micropores were produced on the PADM with a laser punch. The distance between micropores varied from 0.8, 1.0, 1.2 to 1.5mm. Full thickness defect wounds were created on the back of 144 SD rats. The rats were randomly divided into six groups: micropore groups I-IV in which the wound were grafted with PADM with micropores, in four different distances, respectively and split-thickness autograft; mesh group rats received meshed PADM graft and split-thickness autograft; control group received simple split-thickness autografting. The status of wound healing was histologically observed at regular time points after surgery. The wound healing rate and contraction rate were calculated. The wound healing rate in micropore groups I and II was not statistically different from that in control group, but was significantly higher than that in mesh group 6 weeks after grafting. The wound healing rate in micropore groups III and IV was lower than that in mesh and control groups 4 and 6 weeks after grafting. The wound contraction rate in micropore groups I and II was remarkably lower than that in control group 4 and 6 weeks after surgery and it was significantly much lower than that in mesh group 6 weeks after surgery. Histological examination revealed good epithelization, regularly arranged collagenous fibers and integral structure of basement membrane. Laser micropore PADM (0.8 or 1.0mm in distance) grafting in combination with split-thickness autografting can

  14. Cohort study comparing prostate photovaporisation with XPS 180W and HPS 120W laser.

    Science.gov (United States)

    López, B; Capitán, C; Hernández, V; de la Peña, E; Jiménez-Valladolid, I; Guijarro, A; Pérez-Fernández, E; Llorente, C

    2016-01-01

    Prostate photovaporisation with Greenlight laser for the surgical treatment of benign prostate hyperplasia has rapidly evolve to the new XPS 180W. We have previously demonstrated the safety and efficacy of the HPS 120W. The aim of this study was to assess the functional and safety results, with a year of follow-up, of photovaporisation using the XPS 180W laser compared with its predecessor. A cohort study was conducted with a series of 191 consecutive patients who underwent photovaporisation between 1/2008 and 5/2013. The inclusion criteria were an international prostate symptom score (IPSS) >15 after medical failure, a prostate volume <80 cm(3) and a maximum flow <15 mL/s. We assessed preoperative and intraoperative variables (energy used, laser time and total surgical time), complications, catheter hours, length of stay and functional results (maximum flow, IPSS, prostate-specific antigen and prostate volume) at 3, 6 and 12 months. We analysed the homogeneity in preoperative characteristics of the 2 groups through univariate analysis techniques. The postoperative functional results were assessed through an analysis of variance of repeated measures with mixed models. A total of 109 (57.1%) procedures were performed using HPS 120W, and 82 (42.9%) were performed using XPS. There were no differences between the preoperative characteristics. We observed significant differences both in the surgical time and effective laser time in favour of the XPS system. This advantage was 11% (48 ± 15.7 vs. 53.8 ± 16.2, p<.05) and 9% (32.8 ± 11.7 vs. 36 ± 11.6, p<.05), respectively. There were no statistically significant differences in the rest of the analysed parameters. The technical improvements in the XPS 180W system help reduce surgical time, maintaining the safety and efficacy profile offered by the HPS 120W system, with completely superimposable results at 1 year of follow-up. Copyright © 2015 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.

  15. Four Forensic Entomology Case Studies: Records and Behavioral Observations on Seldom Reported Cadaver Fauna With Notes on Relevant Previous Occurrences and Ecology.

    Science.gov (United States)

    Lindgren, Natalie K; Sisson, Melissa S; Archambeault, Alan D; Rahlwes, Brent C; Willett, James R; Bucheli, Sibyl R

    2015-03-01

    A yearlong survey of insect taxa associated with human decomposition was conducted at the Southeast Texas Applied Forensic Science (STAFS) facility located in the Center for Biological Field Studies of Sam Houston State University in Huntsville, TX. During this study, four insect-cadaver interactions were observed that represent previously poorly documented yet forensically significant interactions: Syrphidae maggots colonized a corpse in an aquatic situation; Psychodidae adults mated and oviposited on an algal film that was present on a corpse that had been recently removed from water; several Panorpidae were the first insects to feed upon a freshly placed corpse in the autumn; and a noctuid caterpillar was found chewing and ingesting dried human skin. Baseline knowledge of insect-cadaver interactions is the foundation of forensic entomology, and unique observations have the potential to expand our understanding of decomposition ecology. © The Author 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  16. Fractional CO2 laser treatment for vaginal laxity: A preclinical study.

    Science.gov (United States)

    Kwon, Tae-Rin; Kim, Jong Hwan; Seok, Joon; Kim, Jae Min; Bak, Dong-Ho; Choi, Mi-Ji; Mun, Seok Kyun; Kim, Chan Woong; Ahn, Seungwon; Kim, Beom Joon

    2018-05-07

    Various studies have investigated treatment for vaginal laxity with microablative fractional carbon dioxide CO 2 laser in humans; however, this treatment has not yet been studied in an animal model. Herein, we evaluate the therapeutic effects of fractional CO 2 laser for tissue remodeling of vaginal mucosa using a porcine model, with the aim of improving vaginal laxity. The fractional CO 2 laser enables minimally invasive and non-incisional procedures. By precisely controlling the laser energy pulses, energy is sent to the vaginal canal and the introitus area to induce thermal denaturation and contraction of collagen. We examined the effects of fractional CO 2 laser on a porcine model via clinical observation and ultrasound measurement. Also, thermal lesions were histologically examined via hematoxylin-eosin staining, Masson's trichrome staining, and Elastica van Gieson staining and immunohistochemistry. The three treatment groups, which were determined according to the amount of laser-energy applied (60, 90, and 120 mJ), showed slight thermal denaturation in the vaginal mucosa, but no abnormal reactions, such as excessive hemorrhaging, vesicles, or erythema, were observed. Histologically, we also confirmed that the denatured lamina propria induced by fractional CO 2 laser was dose-dependently increased after laser treatment. The treatment groups also showed an increase in collagen and elastic fibers due to neocollagenesis and angiogenesis, and the vaginal walls became firmer and tighter because of increased capillary and vessel formation. Also, use of the fractional CO 2 laser increased HSP (heat shock protein) 70 and collagen type I synthesis. Our results show that microablative fractional CO 2 laser can produce remodeling of the vaginal connective tissue without causing damage to surrounding tissue, and the process of mucosa remodeling while under wound dressings enables collagen to increase and the vaginal wall to become thick and tightened. Lasers Surg. Med

  17. Studies of harmonic generation in free electron lasers

    International Nuclear Information System (INIS)

    Goldammer, K.

    2007-01-01

    Nonlinear harmonic generation is one of the most interesting aspects of Free Electron Lasers under study today. It provides for coherent, high intensity radiation at higher harmonics of the FEL resonant frequency. The sources, numerical simulation and applications of harmonic radiation in cascaded High Gain Harmonic Generation FELs were the subject of this thesis. Harmonic emission in FELs originates from harmonic microbunching of the particles and the particular electron trajectory during FEL interaction. Numerical FEL simulation codes model these analytical equations and predict the performance of Free Electron Lasers with good accuracy. This thesis has relied heavily upon the FEL simulation code Genesis 1.3 which has been upgraded in the framework of this thesis to compute harmonic generation in a self-consistent manner. Tests against analytical predictions suggest that the harmonic power levels as well as harmonic gain lengths are simulated correctly. A benchmark with the FEL simulation code GINGER yields excellent agreement of the harmonic saturation length and saturation power. The new version of the simulation code Genesis was also tested against measurements from the VUV-FEL FLASH at DESY. The spectral power distributions of fundamental and third harmonic radiation were recorded at 25.9 nm and 8.6 nm, respectively. The relative bandwidths (FWHM) were in the range of 2 % for both the fundamental as well as the third harmonic, which was accurately reproduced by time-dependent simulations with Genesis. The new code was also used to propose and evaluate a new design for the BESSY Soft X-Ray FEL, a cascaded High Gain Harmonic Generation FEL proposed by BESSY in Berlin. The original design for the BESSY High Energy FEL line requires four HGHG stages to convert the initial seed laser wavelength of 297.5 nm down to 1.24 nm. A new scheme is proposed that makes use of fifth harmonic radiation from the first stage and reduces the number of HGHG stages to three. It

  18. Studies of harmonic generation in free electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Goldammer, K.

    2007-11-12

    Nonlinear harmonic generation is one of the most interesting aspects of Free Electron Lasers under study today. It provides for coherent, high intensity radiation at higher harmonics of the FEL resonant frequency. The sources, numerical simulation and applications of harmonic radiation in cascaded High Gain Harmonic Generation FELs were the subject of this thesis. Harmonic emission in FELs originates from harmonic microbunching of the particles and the particular electron trajectory during FEL interaction. Numerical FEL simulation codes model these analytical equations and predict the performance of Free Electron Lasers with good accuracy. This thesis has relied heavily upon the FEL simulation code Genesis 1.3 which has been upgraded in the framework of this thesis to compute harmonic generation in a self-consistent manner. Tests against analytical predictions suggest that the harmonic power levels as well as harmonic gain lengths are simulated correctly. A benchmark with the FEL simulation code GINGER yields excellent agreement of the harmonic saturation length and saturation power. The new version of the simulation code Genesis was also tested against measurements from the VUV-FEL FLASH at DESY. The spectral power distributions of fundamental and third harmonic radiation were recorded at 25.9 nm and 8.6 nm, respectively. The relative bandwidths (FWHM) were in the range of 2 % for both the fundamental as well as the third harmonic, which was accurately reproduced by time-dependent simulations with Genesis. The new code was also used to propose and evaluate a new design for the BESSY Soft X-Ray FEL, a cascaded High Gain Harmonic Generation FEL proposed by BESSY in Berlin. The original design for the BESSY High Energy FEL line requires four HGHG stages to convert the initial seed laser wavelength of 297.5 nm down to 1.24 nm. A new scheme is proposed that makes use of fifth harmonic radiation from the first stage and reduces the number of HGHG stages to three. It

  19. Late tamoxifen in patients previously operated for breast cancer without postoperative tamoxifen: 5-year results of a single institution randomised study

    International Nuclear Information System (INIS)

    Veronesi, Andrea; Miolo, GianMaria; Magri, Maria D; Crivellari, Diana; Scalone, Simona; Bidoli, Ettore; Lombardi, Davide

    2010-01-01

    A population of breast cancer patients exists who, for various reasons, never received adjuvant post-operative tamoxifen (TAM). This study was aimed to evaluate the role of late TAM in these patients. From 1997 to 2003, patients aged 35 to 75 years, operated more than 2 years previously for monolateral breast cancer without adjuvant TAM, with no signs of metastases and no contraindication to TAM were randomized to TAM 20 mg/day orally for 2 years or follow-up alone. Events were categorized as locoregional relapse, distant metastases, metachronous breast cancer, tumours other than breast cancer and death from any causes, whichever occurred first. The sample size (197 patients per arm, plus 10% allowance) was based on the assumption of a 30% decrease in the number of events occurring at a rate of 5% annually in the 10 years following randomization. Four hundred and thirty-three patients were randomized in the study (TAM 217, follow-up 216). Patients characteristics (TAM/follow-up) included: median age 55/55 years, median time from surgery 25/25 months (range, 25-288/25-294), in situ carcinoma 18/24, oestrogen receptor (ER) positive in 75/68, negative in 70/57, unknown in 72/91 patients. Previous adjuvant treatment included chemotherapy in 131/120 and an LHRH analogue in 11/13 patients. Thirty-six patients prematurely discontinued TAM after a median of 1 month, mostly because of subjective intolerance. Eighty-three events (TAM 39, follow-up 44) occurred: locoregional relapse in 10/8, distant metastases in 14/16, metachronous breast cancer in 4/10, other tumours in 11/10 patients. Less ER-positive secondary breast cancers occurred in the TAM treated patients than in follow-up patients (1 vs 10, p = 0.005). Event-free survival was similar in both groups of patients. This 5-year analysis revealed significantly less metachronous ER-positive breast cancers in the TAM treated patients. No other statistically significant differences have emerged thus far

  20. Dipeptidyl Peptidase-4 Inhibitor Sitagliptin Prevented Weight Regain in Obese Women with Polycystic Ovary Syndrome Previously Treated with Liraglutide: A Pilot Randomized Study.

    Science.gov (United States)

    Ferjan, Simona; Janez, Andrej; Jensterle, Mojca

    2017-12-01

    Weight loss is often nonsustainable after liraglutide cessation. The present study is the first insight into the potential prevention of weight regain in obese subjects who have been withdrawn from liraglutide. We evaluated whether dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin in adjunct to metformin prevents body weight regain more effectively than metformin alone in obese polycystic ovary syndrome (PCOS) previously treated with liraglutide. A 12-week prospective randomized open-label study was conducted with 24 obese women with PCOS who had been pretreated with liraglutide 3.0 mg due to antiobesity management (aged 34.3 ± 6.8 years, body mass index [BMI] 36.3 ± 5.2 kg/m 2 , mean ± standard deviation). They were randomized to combined treatment (COMBO) with sitagliptin 100 mg per day (QD) and metformin (MET) 1000 mg twice daily (BID) (n = 12) or MET 1000 mg BID (n = 12). Lifestyle intervention was promoted in both groups. The primary outcome was change in anthropometric measures of obesity. Women treated with MET regain 4.7 ± 2.7 kg (P = 0.002) compared with a 0.9 ± 2.5 kg in COMBO (P = 0.147). BMI increased for 1.7 ± 0.9 kg/m 2 in MET (P = 0.002) compared with 0.3 ± 0.8 kg/m 2 increase in COMBO (P = 0.136). MET group regain 4.5% ± 2.5% of body weight as opposed to 0.8% ± 2.6% in COMBO. The between-treatment differences were significant for weight change (P weight change (P weight regain in obese women with PCOS previously treated with liraglutide.

  1. Plasma interpenetration study on the Omega laser facility

    Science.gov (United States)

    Le Pape, Sebastien; Divol, Laurent; Ross, Steven; Wilks, Scott; Amendt, Peter; Berzak Hopkins, Laura; Huser, Gael; Moody, John; MacKinnon, Andy; Meezan, Nathan

    2016-10-01

    The Near Vacuum Campaign on the National Ignition Facility has sparked an interest on the nature of the gold/carbon interface at high velocity, high electron temperature, low-electron density. Indeed radiation-hydrodynamic simulations have been unable to accurately reproduce the experimental shape of the hot spot resulting from implosion driven in Near Vacuum Holhraum. The experimental data are suggesting that the inner beams are freely propagating to the waist of the hohlraum when simulations predict that a density ridge at the gold/carbon interface blocks the inner beams. The discrepancy between experimental data and simulation might be explained by the fluid description of the plasma interface in a rad-hydro code which is probably not valid in when two plasma at high velocity, high temperature are meeting. To test our assumption, we went to the Omega laser facility to study gold/carbon interface in the relevant regime. Time resolved images of the self-emission as well as Thomson scattering data will be presented. For the first time, a transition from a multifluid to a single fluid is observed as plasmas are interacting. This work was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

  2. Theoretical study on the thermal and optical features of a diode side-pumped alkali laser

    Science.gov (United States)

    Han, Juhong; Liu, Xiaoxu; Wang, Hongyuan; Cai, He; An, Guofei; Zhang, Wei; Wang, You

    2018-03-01

    As one of the most hopeful candidates to achieve high power performances, a diode-pumped alkali laser (DPAL) has attracted a lot of attention in the last decade. Comparing with a diode end-pumped alkali laser (DEPAL), a diode side-pumped alkali laser (DSPAL) has great potentiality to realize an even-higher output of alkali lasers. However, there are few related researching studies concern DSPAL. In this paper, we introduce a theoretical model to investigate the physical features of a double-directions side-pumped alkali laser. The distributions of the population density, temperature, and absorption power at the cross section of a vapor cell are systematically studied. The analyses should be valuable for design of a steady high-powered DPAL.

  3. Study of Material Consolidation at Higher Throughput Parameters in Selective Laser Melting of Inconel 718

    Science.gov (United States)

    Prater, Tracie

    2016-01-01

    Selective Laser Melting (SLM) is a powder bed fusion additive manufacturing process used increasingly in the aerospace industry to reduce the cost, weight, and fabrication time for complex propulsion components. SLM stands poised to revolutionize propulsion manufacturing, but there are a number of technical questions that must be addressed in order to achieve rapid, efficient fabrication and ensure adequate performance of parts manufactured using this process in safety-critical flight applications. Previous optimization studies for SLM using the Concept Laser M1 and M2 machines at NASA Marshall Space Flight Center have centered on machine default parameters. The objective of this work is to characterize the impact of higher throughput parameters (a previously unexplored region of the manufacturing operating envelope for this application) on material consolidation. In phase I of this work, density blocks were analyzed to explore the relationship between build parameters (laser power, scan speed, hatch spacing, and layer thickness) and material consolidation (assessed in terms of as-built density and porosity). Phase II additionally considers the impact of post-processing, specifically hot isostatic pressing and heat treatment, as well as deposition pattern on material consolidation in the same higher energy parameter regime considered in the phase I work. Density and microstructure represent the "first-gate" metrics for determining the adequacy of the SLM process in this parameter range and, as a critical initial indicator of material quality, will factor into a follow-on DOE that assesses the impact of these parameters on mechanical properties. This work will contribute to creating a knowledge base (understanding material behavior in all ranges of the AM equipment operating envelope) that is critical to transitioning AM from the custom low rate production sphere it currently occupies to the world of mass high rate production, where parts are fabricated at a rapid

  4. Enhanced diagnostic of skin conditions by polarized laser speckles: phantom studies and computer modeling

    Science.gov (United States)

    Tchvialeva, Lioudmila; Lee, Tim K.; Markhvida, Igor; Zeng, Haishan; Doronin, Alexander; Meglinski, Igor

    2014-03-01

    The incidence of the skin melanoma, the most commonly fatal form of skin cancer, is increasing faster than any other potentially preventable cancer. Clinical practice is currently hampered by the lack of the ability to rapidly screen the functional and morphological properties of tissues. In our previous study we show that the quantification of scattered laser light polarization provides a useful metrics for diagnostics of the malignant melanoma. In this study we exploit whether the image speckle could improve skin cancer diagnostic in comparison with the previously used free-space speckle. The study includes skin phantom measurements and computer modeling. To characterize the depolarization of light we measure the spatial distribution of speckle patterns and analyse their depolarization ratio taken into account radial symmetry. We examine the dependences of depolarization ratio vs. roughness for phantoms which optical properties are of the order of skin lesions. We demonstrate that the variation in bulk optical properties initiates the assessable changes in the depolarization ratio. We show that image speckle differentiates phantoms significantly better than free-space speckle. The results of experimental measurements are compared with the results of Monte Carlo simulation.

  5. In vitro evaluation of oestrogenic/androgenic activity of the serum organochlorine pesticide mixtures previously described in a breast cancer case–control study

    International Nuclear Information System (INIS)

    Rivero, Javier; Luzardo, Octavio P.; Henríquez-Hernández, Luis A.; Machín, Rubén P.; Pestano, José; Zumbado, Manuel; Boada, Luis D.; Camacho, María; Valerón, Pilar F.

    2015-01-01

    Some organochlorine pesticides (OCs) have been individually linked to breast cancer (BC) because they exert oestrogenic effects on mammary cells. However, humans are environmentally exposed to more or less complex mixtures of these organochlorines, and the biological effects of these mixtures must be elucidated. In this work we evaluated the in vitro effects exerted on human BC cells by the OC mixtures that were most frequently detected in two groups of women who participated in a BC case–control study developed in Spain: healthy women and women diagnosed with BC. The cytotoxicity, oestrogenicity, and androgenicity of the most prevalent OC mixtures found in healthy women (H-mixture) and in BC patients (BC-mixture) were tested at concentrations that resembled those found in the serum of the evaluated women. Our results showed that both OC mixtures presented a similar oestrogenic activity and effect on cell viability, but BC-mixture showed an additional anti-androgenic effect. These results indicate that although the proliferative effect exerted by these mixtures on human breast cells seems to depend mainly on their oestrogenic action, the BC-mixture might additionally induce cell proliferation due to its anti-androgenic activity, therefore increasing the carcinogenic potential of this mixture. The findings of this study demonstrate that subtle variations in the composition of a mixture may induce relevant changes in its biological action. - Highlights: • E-screen and A-screen of two mixtures of organochlorine pesticides (OCP) • Assay concentrations based on a previous breast cancer case–control study • Only non-cytotoxic concentrations assayed • Both OCP mixtures induce proliferation mediated by oestrogen receptor. • OCP mixture of breast cancer patients exhibits additional androgenic activity.

  6. In vitro evaluation of oestrogenic/androgenic activity of the serum organochlorine pesticide mixtures previously described in a breast cancer case–control study

    Energy Technology Data Exchange (ETDEWEB)

    Rivero, Javier; Luzardo, Octavio P., E-mail: octavio.perez@ulpgc.es; Henríquez-Hernández, Luis A.; Machín, Rubén P.; Pestano, José; Zumbado, Manuel; Boada, Luis D.; Camacho, María; Valerón, Pilar F.

    2015-12-15

    Some organochlorine pesticides (OCs) have been individually linked to breast cancer (BC) because they exert oestrogenic effects on mammary cells. However, humans are environmentally exposed to more or less complex mixtures of these organochlorines, and the biological effects of these mixtures must be elucidated. In this work we evaluated the in vitro effects exerted on human BC cells by the OC mixtures that were most frequently detected in two groups of women who participated in a BC case–control study developed in Spain: healthy women and women diagnosed with BC. The cytotoxicity, oestrogenicity, and androgenicity of the most prevalent OC mixtures found in healthy women (H-mixture) and in BC patients (BC-mixture) were tested at concentrations that resembled those found in the serum of the evaluated women. Our results showed that both OC mixtures presented a similar oestrogenic activity and effect on cell viability, but BC-mixture showed an additional anti-androgenic effect. These results indicate that although the proliferative effect exerted by these mixtures on human breast cells seems to depend mainly on their oestrogenic action, the BC-mixture might additionally induce cell proliferation due to its anti-androgenic activity, therefore increasing the carcinogenic potential of this mixture. The findings of this study demonstrate that subtle variations in the composition of a mixture may induce relevant changes in its biological action. - Highlights: • E-screen and A-screen of two mixtures of organochlorine pesticides (OCP) • Assay concentrations based on a previous breast cancer case–control study • Only non-cytotoxic concentrations assayed • Both OCP mixtures induce proliferation mediated by oestrogen receptor. • OCP mixture of breast cancer patients exhibits additional androgenic activity.

  7. Fibre laser cutting of polycaprolactone sheet for stents manufacturing: A feasibility study

    Science.gov (United States)

    Guerra, Antonio J.; Farjas, Jordi; Ciurana, Joaquim

    2017-10-01

    The role of the stent is temporary and it is limited to the intervention and shortly thereafter. Bioresorbable polymer stents were introduced to overcome this problem, making the stent manufacturing process rather difficult considering the complexity of the material. The stent forecast sale makes constant technology development necessary on this field. The adaptation of the laser manufacturing industry to these new materials is costly, thus further studies employing different sorts of lasers are necessary. This paper aims to explore the feasibility of 1.08 μm wavelength fibre laser to cut polycaprolactone sheet, which is especially interesting for long-term implantable devices, such as stents. The laser cut samples were analysed by Differential Scanning Calorimetry (DSC), Tensile Stress Test, and Optical Microscopy in order to study the effects of the laser process over the workpiece. The parameters measured were: taper angle, dimensional precision, material structure changes and mechanical properties changes. Results showed a dimensional precision above 95.75% with a taper angle lower than 0.033°. The laser ablation process has exhibited a minor influence upon material properties. Results exhibit the feasibility of fibre laser to cut polycaprolactone, making the fibre laser an alternative to manufacture stents.

  8. Evaluation of the Widal tube agglutination test for the diagnosis of typhoid fever among children admitted to a rural hdospital in Tanzania and a comparison with previous studies

    Directory of Open Access Journals (Sweden)

    Malahiyo Rajabu

    2010-06-01

    Full Text Available Abstract Background The diagnosis of typhoid fever is confirmed by culture of Salmonella enterica serotype Typhi (S. typhi. However, a more rapid, simpler, and cheaper diagnostic method would be very useful especially in developing countries. The Widal test is widely used in Africa but little information exists about its reliability. Methods We assessed the performance of the Widal tube agglutination test among febrile hospitalized Tanzanian children. We calculated the sensitivity, specificity, positive predictive value (PPV, and negative predictive value (NPV of various anti-TH and -TO titers using culture-confirmed typhoid fever cases as the "true positives" and all other febrile children with blood culture negative for S. typhi as the "true negatives." Results We found that 16 (1% of 1,680 children had culture-proven typhoid fever. A single anti-TH titer of 1:80 and higher was the optimal indicator of typhoid fever. This had a sensitivity of 75%, specificity of 98%, NPV of 100%, but PPV was only 26%. We compared our main findings with those from previous studies. Conclusion Among febrile hospitalized Tanzanian children with a low prevalence of typhoid fever, a Widal titer of ≥ 1:80 performed well in terms of sensitivity, specificity, and NPV. However a test with improved PPV that is similarly easy to apply and cost-efficient is desirable.

  9. Caring for women wanting a vaginal birth after previous caesarean section: A qualitative study of the experiences of midwives and obstetricians.

    Science.gov (United States)

    Foureur, Maralyn; Turkmani, Sabera; Clack, Danielle C; Davis, Deborah L; Mollart, Lyndall; Leiser, Bernadette; Homer, Caroline S E

    2017-02-01

    One of the greatest contributors to the overall caesarean section rate is elective repeat caesarean section. Decisions around mode of birth are often complex for women and influenced by the views of the doctors and midwives who care for and counsel women. Women may be more likely to choose a repeat elective caesarean section (CS) if their health care providers lack skills and confidence in supporting vaginal birth after caesarean section (VBAC). To explore the views and experiences of providers in caring for women considering VBAC, in particular the decision-making processes and the communication of risk and safety to women. A descriptive interpretive method was utilised. Four focus groups with doctors and midwives were conducted. The central themes were: 'developing trust', 'navigating the system' and 'optimising support'. The impact of past professional experiences; the critical importance of continuity of carer and positive relationships; the ability to weigh up risks versus benefits; and the language used were all important elements. The role of policy and guidelines on providing standardised care for women who had a previous CS was also highlighted. Midwives and doctors in this study were positively oriented towards assisting and supporting women to attempt a VBAC. Care providers considered that women who have experienced a prior CS need access to midwifery continuity of care with a focus on support, information-sharing and effective communication. Copyright © 2016 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.

  10. Gefitinib plus cisplatin and radiotherapy in previously untreated head and neck squamous cell carcinoma: A phase II, randomized, double-blind, placebo-controlled study

    International Nuclear Information System (INIS)

    Gregoire, Vincent; Hamoir, Marc; Chen Changhu; Kane, Madeleine; Kawecki, Andrzej; Julka, Pramod K.; Wang, Hung-Ming; Prasad, Srihari; D'Cruz, Anil K.; Radosevic-Jelic, Ljiljana; Kumar, Rejnish R.; Korzeniowski, Stanislaw; Fijuth, Jacek; Machiels, Jean-Pascal; Sellers, Mark V.; Tchakov, Ilian; Raben, David

    2011-01-01

    Background and purpose: To assess the efficacy and safety of gefitinib given concomitantly and/or as maintenance therapy to standard cisplatin/radiotherapy for previously untreated, unresected, stage III/IV non-metastatic SCCHN. Materials and methods: In this phase II, double-blind, study, 226 patients were randomized to gefitinib 250 mg/day, 500 mg/day or placebo in two phases: a concomitant phase (gefitinib or placebo with chemoradiotherapy), followed by a maintenance phase (gefitinib or placebo alone). Primary endpoint was local disease control rate (LDCR) at 2 years; secondary endpoints were LDCR at 1 year, objective response rate, progression-free survival, overall survival, and safety and tolerability. Results: Gefitinib (250 and 500 mg/day) did not improve 2-year LDCR compared with placebo either when given concomitantly with chemoradiotherapy (32.7% vs. 33.6%, respectively; OR 0.921, 95% CI 0.508, 1.670 [1-sided p = 0.607]) or as maintenance therapy (28.8% vs. 37.4%, respectively; OR 0.684, 95% CI 0.377, 1.241 [1-sided p = 0.894]). Secondary efficacy outcomes were broadly consistent with the 2-year LDCR results. In both doses, gefitinib was well-tolerated and did not adversely affect the safety and tolerability of concomitant chemoradiotherapy. Conclusion: Gefitinib was well-tolerated, but did not improve efficacy compared with placebo when given concomitantly with chemoradiotherapy, or as maintenance therapy alone.

  11. Simulation study of the sub-terawatt laser wakefield acceleration operated in self-modulated regime

    Science.gov (United States)

    Hsieh, C.-Y.; Lin, M.-W.; Chen, S.-H.

    2018-02-01

    Laser wakefield acceleration (LWFA) can be accomplished by introducing a sub-terawatt (TW) laser pulse into a thin, high-density gas target. In this way, the self-focusing effect and the self-modulation that happened on the laser pulse produce a greatly enhanced laser peak intensity that can drive a nonlinear plasma wave to accelerate electrons. A particle-in-cell model is developed to study sub-TW LWFA when a 0.6-TW laser pulse interacts with a dense hydrogen plasma. Gas targets having a Gaussian density profile or a flat-top distribution are defined for investigating the properties of sub-TW LWFA when conducting with a gas jet or a gas cell. In addition to using 800-nm laser pulses, simulations are performed with 1030-nm laser pulses, as they represent a viable approach to realize the sub-TW LWFA driven by high-frequency, diode-pumped laser systems. The peak density which allows the laser peak power PL˜2 Pc r of self-focusing critical power is favourable for conducting sub-TW LWFA. Otherwise, an excessively high peak density can induce an undesired filament effect which rapidly disintegrates the laser field envelope and violates the process of plasma wave excitation. The plateau region of a flat-top density distribution allows the self-focusing and the self-modulation of the laser pulse to develop, from which well-established plasma bubbles can be produced to accelerate electrons. The process of electron injection is complicated in such high-density plasma conditions; however, increasing the length of the plateau region represents a straightforward method to realize the injection and acceleration of electrons within the first bubble, such that an improved LWFA performance can be accomplished.

  12. A study of the laser power online detecting

    Science.gov (United States)

    Zhang, Qiue; Zhang, Rong; Li, Yongzheng

    2008-12-01

    This article introduced a fundamental of new intelligent instruments. It can be used in laser power online detecting. Based in this theory, we have made a new intelligent mini-power meter. The device adopt SPCE061A MPU to control and process the all detected data, Its CPU core is used 16-bits MPU, it is a perfect unit in industry field. It can process complicated digital signals. Its detecting parts adopt high-speed responding and high-sensitive photoelectric dynatron 3DU13 to detecting the beam's output. It respond spectrum is from 0.4 to 1.1µm, can detect any other laser source's online detecting. Which locate in this spectrum range, optical design is made up of 45 degrees high reflect device and dark body scattering structure. The detector receive a little scatter light, use on-chip ADC to sampling the detector's output. By subsection, insert value linearity, proportion calculate to beam's output powers. And then real-time to displaying by LCD. It can communicate to PC by RS232. By communicate to upper instrument and others, the users can use detected data to achieve laser power's closed-loop control, to control laser source's real time output correctly and calibrating by itself. This mini-power meter need use standard power meter to calibrate in installing, after this process, the device can detect laser power's output from 1 to 200 watts correctly. It error is less than 5 percent.

  13. Study and design on USB wireless laser communication system

    Science.gov (United States)

    Wang, Aihua; Zheng, Jiansheng; Ai, Yong

    2004-04-01

    We give the definition of USB wireless laser communication system (WLCS) and the brief introduction to the protocol of USB, the standard of hardware is also given. The paper analyses the hardware and software of USB WLCS. Wireless laser communication part and USB interface circuit part are discussed in detail. We also give the periphery design of the chip AN2131Q, the control circuit to realize the transformation from parallel port to serial bus, and the circuit of laser sending and receiving of laser communication part, which are simply, cheap and workable. And then the four part of software are analyzed as followed. We have consummated the ISR in the firmware frame to develop the periphery device of USB. We have debugged and consummated the 'ezload,' and the GPD of the drivers. Windows application performs functions and schedules the corresponding API functions to let the interface practical and beautiful. The system can realize USB wireless laser communication between computers, which distance is farther than 50 meters, and top speed can be bigger than 8 Mbps. The system is of great practical sense to resolve the issues of high-speed communication among increasing districts without fiber trunk network.

  14. Numerical studies of pair creation in counterpropagating laser fields

    Energy Technology Data Exchange (ETDEWEB)

    Ruf, Matthias

    2009-05-27

    Pair creation from vacuum induced by electromagnetic fields is probably one of the most intriguing phenomena in physics. If the fields are sufficiently strong, the QED vacuum become unstable. Due to the remarkable progress in laser technology during recent years an experimental investigation of pair creation by pure laser light is coming into reach. The focus of this thesis is on pair creation in counterpropagating laser beams. The pair creation probability is calculated employing the numerically obtained solutions of the Dirac equation. This numerical ansatz has the capability of calculating the momentum distribution of the created pairs in a single propagation, for pure time dependent field configurations. Furthermore, it allows to take the magnetic component of the laser fields into account, which is usually neglected. The latter strongly affects the creation process at high laser frequency. The involved numerical calculations are rather time consuming, therefore the second project of this thesis was to develop a highly efficient code for solving relativistic quantum mechanical problems. This is accomplished by adopting the split-operator method to the Klein-Gordon equation. Here the possibility arises to use parallel computing. However the corresponding spin-statistics becomes crucial in the case of pair creation, demonstrated in several examples. (orig.)

  15. Numerical studies of pair creation in counterpropagating laser fields

    International Nuclear Information System (INIS)

    Ruf, Matthias

    2009-01-01

    Pair creation from vacuum induced by electromagnetic fields is probably one of the most intriguing phenomena in physics. If the fields are sufficiently strong, the QED vacuum become unstable. Due to the remarkable progress in laser technology during recent years an experimental investigation of pair creation by pure laser light is coming into reach. The focus of this thesis is on pair creation in counterpropagating laser beams. The pair creation probability is calculated employing the numerically obtained solutions of the Dirac equation. This numerical ansatz has the capability of calculating the momentum distribution of the created pairs in a single propagation, for pure time dependent field configurations. Furthermore, it allows to take the magnetic component of the laser fields into account, which is usually neglected. The latter strongly affects the creation process at high laser frequency. The involved numerical calculations are rather time consuming, therefore the second project of this thesis was to develop a highly efficient code for solving relativistic quantum mechanical problems. This is accomplished by adopting the split-operator method to the Klein-Gordon equation. Here the possibility arises to use parallel computing. However the corresponding spin-statistics becomes crucial in the case of pair creation, demonstrated in several examples. (orig.)

  16. Photon-phonon laser on crystalline silicon: a feasibility study

    International Nuclear Information System (INIS)

    Zadernovsky, A A

    2015-01-01

    We discuss a feasibility of photon-phonon laser action in bulk silicon with electron population inversion. It is well known, that only direct gap semiconductors are used as an active medium in optical lasers. In indirect gap semiconductors, such as crystalline silicon, the near-to-gap radiative electron transitions must be assisted by emission or absorption of phonons to conserve the momentum. The rate of such two-quantum transitions is much less than in direct gap semiconductors, where the similar radiative transitions are single-quantum. As a result, the quantum efficiency of luminescence in silicon is too small to get it as a laser material. Numerous proposals to overcome this problem are aimed at increasing the rate of radiative recombination. We suggest enhancing the quantum efficiency of luminescence in silicon by stimulating the photon part of the two-quantum transitions by light from an appropriate external laser source. This allows us to obtain initially an external-source-assisted lasing in silicon and then a true photon-phonon lasing without any external source of radiation. Performed analysis revealed a number of requirements to the silicon laser medium (temperature, purity and perfection of crystals) and to the intensity of stimulating radiation. We discuss different mechanisms that may hinder the implementation of photon-phonon lasing in silicon

  17. [Study on the change of optical zone after femtosecond laser assisted laser in situ keratomileusis].

    Science.gov (United States)

    Li, H; Chen, M; Tian, L; Li, D W; Peng, Y S; Zhang, F F

    2018-01-11

    Objective: To explore the change of optical zone after femtosecond laser assisted laser in sitn keratomileusis(FS-LASIK) so as to provide the reference for measurement and design of clinical optical zone. Methods: This retrospective case series study covers 41 eyes of 24 patients (7 males and 17 females, aged from 18 to 42 years old) with myopia and myopic astigmatism who have received FS-LASIK surgery at Corneal Refractive Department of Qingdao Eye Hospital and completed over 6 months of clinical follow-up. Pentacam system (with the application of 6 corneal topographic map modes including: the pure axial curvature topographic map, the pure tangential curvature topographic map, the axial curvature difference topographic map, the tangential curvature difference topographic map, the postoperative front elevation map and the corneal thickness difference topographic map), combined with transparent concentric software (a system independently developed by Qingdao Eye Hospital) was used to measure the optical zone at 1, 3 and 6 months postoperatively, the optical zone diameters measurement results among different follow-up times in group were analyzed with the repeated measures analysis of variance, and the actual measured values and the theoretical design values of the optical zone were analyzed with independent-samples t-testing. Spearman correlation coefficient ( r(s) ) have been applied to evaluate the relationship between postoperative optical zone measurement values and the potential influencing factors. Results: The optical zone diameters measured by pure axial curvature topographic map at 1, 3 and 6 months after FS-LASIK showed (6.55±0.50)mm, (6.50±0.53)mm and (6.48±0.53)mm respectively. The differences between values are of no statistical significance ( F= 1.60, P= 0.21), the optical zone diameter measured by pure tangential curvature topographic map at 1, 3 and 6 months after FS-LASIK showed (5.44±0.46)mm, (5.46±0.52)mm and (5.44±0.50)mm respectively, the

  18. Fs-laser processing of polydimethylsiloxane

    Energy Technology Data Exchange (ETDEWEB)

    Atanasov, Petar A., E-mail: paatanas@ie.bas.bg; Nedyalkov, Nikolay N. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Shose, Sofia 1784 (Bulgaria); Valova, Eugenia I.; Georgieva, Zhenya S.; Armyanov, Stefan A.; Kolev, Konstantin N. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, Sofia 1113 (Bulgaria); Amoruso, Salvatore; Wang, Xuan; Bruzzese, Ricardo [CNR-SPIN, Dipartimento di Scienze Fisiche, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Sawczak, Miroslaw; Śliwiński, Gerard [Photophysics Department, The Szewalski Institute, Polish Academy of Sciences, 14 Fiszera St, 80-231 Gdańsk (Poland)

    2014-07-14

    We present an experimental analysis on surface structuring of polydimethylsiloxane films with UV (263 nm) femtosecond laser pulses, in air. Laser processed areas are analyzed by optical microscopy, SEM, and μ-Raman spectroscopy. The laser-treated sample shows the formation of a randomly nanostructured surface morphology. μ-Raman spectra, carried out at both 514 and 785 nm excitation wavelengths, prior and after laser treatment allow evidencing the changes in the sample structure. The influence of the laser fluence on the surface morphology is studied. Finally, successful electro-less metallization of the laser-processed sample is achieved, even after several months from the laser-treatment contrary to previous observation with nanosecond pulses. Our findings address the effectiveness of fs-laser treatment and chemical metallization of polydimethylsiloxane films with perspective technological interest in micro-fabrication devices for MEMS and nano-electromechanical systems.

  19. Ultra-short laser pulse ablation using shear-force feedback: Femtosecond laser induced breakdown spectroscopy feasibility study

    International Nuclear Information System (INIS)

    Samek, Ota; Kurowski, Andre; Kittel, Silke; Kukhlevsky, Sergei; Hergenroeder, Roland

    2005-01-01

    This work reports on a feasibility study of proximity ablation using femtosecond pulses. Ultra-short pulses were launched to a bare tapered optical fiber and delivered to the sample. The tip-sample distance was controlled by means of shear-force feedback. Consequently, ablation craters with submicrometer dimensions were obtained. Potential analytical applications for Laser Induced Breakdown Spectroscopy (LIBS) technique, such as e.g. inclusions in steel or bio cells, are suggested

  20. Study of silica coatings degradation under laser irradiation and in controlled environment; Etude de la degradation de couches minces de silice sous flux laser et en environnement controle

    Energy Technology Data Exchange (ETDEWEB)

    Becker, S

    2006-11-15

    Performances of optical components submitted to high laser intensities are usually determined by their laser-induced damage threshold. This value represents the highest density of energy (fluence) sustainable by the component before its damage. When submitted to laser fluences far below this threshold, optical performances may also decrease with time. The degradation processes depend on laser characteristics, optical materials, and environment around the component. Silica being the most used material in optics, the aim of this study was to describe and analyse the physical-chemical mechanisms responsible for laser-induced degradation of silica coatings in controlled environment. Experimental results show that degradation is due to the growth of a carbon deposit in the irradiated zone. From these results, a phenomenological model has been proposed and validated with numerical simulations. Then, several technological solutions have been tested in order to reduce the laser-induced contamination of silica coatings. (author)

  1. Prevalence of pain in the head, back and feet in refugees previously exposed to torture: a ten-year follow-up study

    DEFF Research Database (Denmark)

    Olsen, Dorthe Reff; Montgomery, Edith; Bøjholm, Søren

    2007-01-01

    AIM: To estimate change over 10 years concerning the prevalence of pain in the head, back and feet, among previously tortured refugees settled in Denmark, and to compare associations between methods of torture and prevalent pain at baseline and at 10-year follow-up. METHODS: 139 refugees previous...... associated with the type and bodily focus of the torture. This presents a considerable challenge to future evidence-based development of effective treatment programs....

  2. Theoretical study of annealed proton-exchanged Nd $LiNbO_{3}$ channel waveguide lasers with variational method

    CERN Document Server

    De Long Zhang; Yuan Guo Xie; Guilan, Ding; Yuming, Cui; Cai He Chen

    2001-01-01

    The controllable fabrication parameters, including anneal time, initial exchange time, channel width, dependences of TM/sub 00/ mode size, corresponding effective refractive index, effective pump area, and coupling efficiency between pump and laser modes in z-cut annealed proton-exchanged (APE) Nd:LiNbO/sub 3/ channel waveguide lasers were studied by using variational method. The effect of channel width on the surface index increment and the waveguide depth was taken into account. The features of mode size and effective refractive index were summarized, discussed, and compared with previously published experimental results. The effective pump area, which is directly proportional to threshold pump power, increases strongly, slightly, and very slightly with the increase of anneal time, channel width, and initial exchange time, respectively. However, the coupling efficiency, which is directly proportional to slope efficiency, remains constant (around 0.82) no matter what changes made to these parameters. The var...

  3. Studies of high repetition rate laser-produced plasma soft-X-ray amplifiers

    International Nuclear Information System (INIS)

    Cassou, K.

    2006-12-01

    The progress made as well on the Ti:Sa laser system, as in the control and the knowledge of laser produced X-UV sources allowed the construction of a X-UV laser station dedicated to the applications. My thesis work falls under the development of this station and more particularly on the characterization of a X-UV laser plasma amplifier. The experimental study relates to the coupling improvement of the pump infra-red laser with plasma within the framework of the transient collisional X-UV laser generation. These X-UV lasers are generated in a plasma formed by the interaction of a solid target and a laser pulse of approximately 500 ps duration, followed by a second infra-red laser pulse known as of pump (about 5 ps) impinging on the target in grazing incidence. For the first time, a complete parametric study was undertaken on the influence of the grazing angle on the pumping of the amplifying medium. One of the results was to reach very high peak brightness about 10 28 ph/s/mm 2 /mrad 2 /(0.1%bandwidth), which compares well with the free-electron laser brightness. Moreover, we modified then used a new two-dimensional hydrodynamic code with adaptive mesh refinement in order to understand the influence of the space-time properties of the infra-red laser on the formation and the evolution of the amplifying plasma. Our modeling highlighted the interest to use a super Gaussian transverse profile for the line focus leading to an increase in a factor two of the gain region size and a reduction of the electron density gradient by three orders of magnitude. These improvements should strongly increase the energy contained in X-UV laser beam. We thus used X-UV laser to study the appearance of transient defects produced by a laser IR on a beam-splitter rear side. We also began research on the mechanisms of DNA damage induced by a very intense X-UV radiation. (author)

  4. Immunogenicity and safety of tetravalent dengue vaccine in 2-11 year-olds previously vaccinated against yellow fever: randomized, controlled, phase II study in Piura, Peru.

    Science.gov (United States)

    Lanata, Claudio F; Andrade, Teresa; Gil, Ana I; Terrones, Cynthia; Valladolid, Omar; Zambrano, Betzana; Saville, Melanie; Crevat, Denis

    2012-09-07

    In a randomized, placebo-controlled, monocenter, observer blinded study conducted in an area where dengue is endemic, we assessed the safety and immunogenicity of a recombinant, live, attenuated, tetravalent dengue vaccine candidate (CYD-TDV) in 2-11 year-olds with varying levels of pre-existing yellow-fever immunity due to vaccination 1-7 years previously. 199 children received 3 injections of CYD-TDV (months 0, 6 and 12) and 99 received placebo (months 0 and 6) or pneumococcal polysaccharide vaccine (month 12). One month after the third dengue vaccination, serotype specific neutralizing antibody GMTs were in the range of 178-190 (1/dil) (versus 16.7-38.1 in the control group), a 10-20 fold-increase from baseline, and 94% of vaccines were seropositive to all four serotypes (versus 39% in the control group). There were no vaccine-related SAEs. The observed reactogenicity profile was consistent with phase I studies, with severity grade 1-2 injection site pain, headache, malaise and fever most frequently reported and no increase after subsequent vaccinations. Virologically confirmed dengue cases were seen after completion of the 3 doses: 1 in the CYD-TDV group (N=199), and 3 in the control group (N=99). A 3-dose regimen of CYD-TDV had a good safety profile in 2-11 year olds with a history of YF vaccination and elicited robust antibody responses that were balanced against the four serotypes. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. A phase II study of VP-16-ifosfamide-cisplatin combination chemotherapy plus early concurrent thoracic irradiation for previously untreated limited small cell lung cancer

    International Nuclear Information System (INIS)

    Woo, In Sook; Park, Young Suk; Kwon, Sung Hee

    2000-01-01

    At present the addition of thoracic irradiation to combination chemotherapy is a standard treatment for limited staged small cell ling cancer. However, there is still controversy about the optimum timing of chest irradiation. We conducted a phase II study of etoposide (VP-16)-ifosfamide-cisplatin (VIP) combination chemotherapy plus early concurrent thoracic irradiation for the patients with previously untreated limited small cell lung cancer in order to assess if the treatment modality could improve the response rate and the toxicity. Forty-four patients with limited small cell lung cancer were treated with etoposide-ifosfamide-cisplatin and concurrent thoracic irradiation. Combination chemotherapy consisted of etoposide 100 mg/m 2 (on day 1-3), ifosfamide 1000 mg/m 2 (on days 1 and 2) and cisplatin 100 mg/m 2 (on day 1). Concurrent thoracic irradiation consisted of a total of 4000 cGy over 4 weeks starting on the first day of the first chemotherapy. All patients who showed a complete response were given prophylactic cranial irradiation for 2.5 weeks. Forty-four of the 49 patients who entered the study from May 1994 to August 1998 were evaluable. The median age was 59 years and 40 patients had a performance status of 0 or 1. The median survival time was 22.5 months. Twenty-eight patients (62%) showed a complete response and 16 (38%) a partial response. Twenty-four patients (54%) developed grade 3 or 4 neutropenia; there was a 9% RTOG score 3 or 4 esophagitis. VIP combination chemotherapy and early concurrent thoracic irradiation for patients with limited stage small cell lung cancer revealed excellent antitumor response with tolerable toxicity. (author)

  6. Laser-induced damage study of polymer PMMA

    International Nuclear Information System (INIS)

    Mansour, N.

    2001-01-01

    This article presents the results of bulk laser-induced damage measurements in polymer PMMA at 532 nm and 1064 nm for nanosecond laser pulses. The damage thresholds were measured for focused spot sizes ranging over two orders of magnitude. In this work, self-focusing effects were verified to be absent by measurements of breakdown thresholds using both linearly and circularly polarized light. At both 1064 nm and 532 nm, the dependence of the breakdown field, E B , on the spot size, ω, was empirically determined to be E B = C/√ω, where C depends on the wavelength. The extracted value for C(λ) at 1064 nm is larger by a factor of 5 than at 532 nm. Possible reasons for this strong dispersion and mechanism for laser-induced damage in polymer materials will be discussed

  7. Demonstrator study for micro-ranging-laser device

    Science.gov (United States)

    Henkel, Hartmut; Bernhardt, Bodo; Pereira do Carmo, J.

    2017-11-01

    Within ESA's Innovation Triangle Initiative (ITI) a demonstrator breadboard for a micro-ranging-laser device "MYLRAD" has been developed. Its working principle is the measurement of the round-trip delay time of a laser beam as a phase shift. The demonstrator consists of the laser diode (30 mW, square wave AM), optics, APD detector, narrowband preamplifier, limiter, and a phase digitiser based on a novel noise-shaping synchroniser (NSS) circuit; this works without ADCs and can be built from rad-hard components for space. The system timing and the digitiser algorithm are performed by an FPGA. The demonstrator has been tested at ranges from 1 m to 30 m. With a static non-cooperative target an RMS noise of 1 mm at a result rate of 60 Hz was reached. The demonstrator needs less than 2.5 W power.

  8. An in-vitro morphological study of Q-switched neodymium/YAG laser trabeculotomy.

    Science.gov (United States)

    Venkatesh, S; Lee, W R; Guthrie, S; Cruickshank, F R; Foulds, W S; Quigley, R J; Bailey, R T

    1986-02-01

    Laser trabeculotomies produced by directing a pulsed neodymium/YAG laser beam at specimens of human anterior chamber angle obtained post mortem or after enucleation were studied by light microscopy and by scanning and transmission electron microscopy to assess the dimensions of the openings created in the trabecular meshwork, their penetrance to the canal of Schlemm, and the extent or absence of laser induced cellular damage in immediately adjacent tissue. A pulse duration of 40-50 ns at energy levels of around 30 mJ was used and the laser cavity carefully tuned to give a Gaussian spatial mode pattern. Openings in the trabecular meshwork typically of 100 microns in diameter and penetrating through to the canal of Schlemm could be regularly created with only minimal damage to adjacent tissue as judged by transmission electron microscopy. The information so gained may be useful in determining the parameters required for successful laser trabeculotomy as a treatment for primary open-angle glaucoma.

  9. NATO Advanced Study Institute on Laser Control & Monitoring in New Materials, Biomedicine, Environment, Security & Defense

    CERN Document Server

    Hall, Trevor J; Paredes, Sofia A; Extreme Photonics & Applications

    2010-01-01

    "Extreme Photonics & Applications" arises from the 2008 NATO Advanced Study Institute in Laser Control & Monitoring in New Materials, Biomedicine, Environment, Security and Defense. Leading experts in the manipulation of light offered by recent advances in laser physics and nanoscience were invited to give lectures in their fields of expertise and participate in discussions on current research, applications and new directions. The sum of their contributions to this book is a primer for the state of scientific knowledge and the issues within the subject of photonics taken to the extreme frontiers: molding light at the ultra-finest scales, which represents the beginning of the end to limitations in optical science for the benefit of 21st Century technological societies. Laser light is an exquisite tool for physical and chemical research. Physicists have recently developed pulsed lasers with such short durations that one laser shot takes the time of one molecular vibration or one electron rotation in an ...

  10. Fusion welding studies using laser on Ti-SS dissimilar combination

    Science.gov (United States)

    Shanmugarajan, B.; Padmanabham, G.

    2012-11-01

    Laser welding investigations were carried out on dissimilar Ti-SS combination. The study is aimed to improve the weld strength and ductility by minimizing harmful intermetallics and taking advantage of high cooling rates in laser welding. Results of continuous wave 3.5 kW CO2 laser welding of totally dissimilar combination of Titanium and stainless steel (304) have been discussed. Bead on plate welding experiments were conducted to identify the laser welding parameters using depth of penetration as criteria. The welding of dissimilar combination has been attempted both autogenously and with interlayers such as Vanadium (V) and Tantalum (Ta) in the form of laser cladding as well as strip. Autogenous welds were carried out by varying the laser power, welding speed and position of the laser beam with respect to the joint centre. The resultant welds are characterized by macrostructure analysis, SEM/EDAX and XRD and as welded tensile test in UTM. The autogenous welds have exhibited extensive cracking even when welded at high speeds or by manipulating the beam position with respect to the joint. Similarly Vandaium as interlayer could not achieve crack free joint. A joint with 40 MPa strength could be made with Ta as interlayer. Results and analysis of these variants of laser welded joints are reported and discussed.

  11. Study on modes of energy action in laser-induction hybrid cladding

    International Nuclear Information System (INIS)

    Huang Yongjun; Zeng Xiaoyan

    2009-01-01

    The shape and microstructure in laser-induction hybrid cladding were investigated, in which the cladding material was provided by means of three different methods including the powder feeding, cold pre-placed coating (CPPC) and thermal pre-placed coating (TPPC). Moreover, the modes of energy action in laser-induction hybrid cladding were also studied. The results indicate that the cladding material supplying method has an important influence on the shape and microstructure of coating. The influence is decided by the mode of energy action in laser-induction hybrid cladding. During the TPPC hybrid cladding of Ni-based alloy, the laser and induction heating are mainly performed on coating. During the CPPC hybrid cladding of Ni-based alloy, the laser and induction heating are mainly performed on coating and substrate surface, respectively. In powder feeding hybrid cladding, a part of laser is absorbed by the powder particles directly, while the other part of laser penetrating powder cloud radiates on the molten pool. Meanwhile, the induction heating is entirely performed on the substrate. In addition, the wetting property on the interface is improved and the metallurgical bond between the coating and substrate is much easier to form. Therefore, the powder feeding laser-induction hybrid cladding has the highest cladding efficiency and the best bond property among three hybrid cladding methods.

  12. Study into the applicabilities of lasers for the dismantling of decommissioned nuclear power plant

    International Nuclear Information System (INIS)

    Haferkamp, H.; Bach, F.W.; Vinke, T.; Kinzel, A.; Mack, N.; Kuboschek, M.; Grobe, K.

    1989-01-01

    The project was intended to screen current laser technology for potential applications of laser beams in the dismantling of decommissioned nuclear power plant. As with CO 2 , Nd-YAG, or excimer lasers, developments clearly proceed towards higher output power. The market survey shows the CO 2 -laser to be the most efficient at present, with a great number of laser units available on the market in the range up to 5 kW, and some in the range up to 15 kW. The CO 2 -laser has exclusively been used so far for cutting work in steel plates thicker than 10 mm. Characteristic conditions of application include the high output power of more than 2 kW, long beam lengths, oxygen supply at strongly increased working pressure, sometimes from external sources. The maximum cutting work achieved in the laboratory was 110 mm in structural steel, 90 mm in austenitic steel, and 160 mm in concrete, all under conditions of easy access to the material. It remains to be examined whether steel cutting work at constrained positions will allow separation of wall thicknesses of more than 10 mm. Laser beam cutting under water is feasible in principle but has not been much studied yet. There also are only few sampling results of measurements of dust and aerosol quantities resulting from laser beam cutting work. (orig.) [de

  13. [Study of enhancement effect of laser-induced crater on plasma radiation].

    Science.gov (United States)

    Chen, Jin-Zhong; Zhang, Xiao-Ping; Guo, Qing-Lin; Su, Hong-Xin; Li, Guang

    2009-02-01

    Single pulses exported from high-energy neodymium glass laser were used to act on the same position of soil sample surface repeatedly, and the plasma emission spectra generated from sequential laser pulse action were collected by spectral recording system. The experimental results show that the laser-induced soil plasma radiation was enhanced continuously under the confinement effect of the crater walls, and the line intensities and signal-to-background ratios both had different improvements along with increasing the number of acting pulses. The photographs of the plasma image and crater appearance were taken to study the plasma shape, laser-induced crater appearance, and the mass of the ablated sample. The internal mechanism behind that laser-induced crater enhanced plasma radiation was researched. Under the sequential laser pulse action, the forming plasma as a result enlarges gradually first, leading to distortion at the trail of plasma plume, and then, its volume diminishes slowly. And also, the color of the plasma changes from buff to white gradually, which implies that the temperature increases constantly. The laser-induced crater had a regular shape, that is, the diameter increased from its bottom to top gradually, thus forming a taper. The mass of the laser-ablated substance descends along with increasing the amount of action pulse. Atomization degree of vaporized substance was improved in virtue of the crater confinement effect, Fresnel absorption produced from the crater walls reflection, and the inverse bremsstrahlung, and the plasma radiation intensity was enhanced as a result.

  14. NATO Advanced Study Institute on Laser Interactions with Atoms, Solids,and Plasmas

    CERN Document Server

    1994-01-01

    The aim of this NATO Advanced Study Institute was to bring together scientists and students working in the field of laser matter interactions in order to review and stimulate developmentoffundamental science with ultra-short pulse lasers. New techniques of pulse compression and colliding-pulse mode-locking have made possible the construction of lasers with pulse lengths in the femtosecond range. Such lasers are now in operation at several research laboratories in Europe and the United States. These laser facilities present a new and exciting research direction with both pure and applied science components. In this ASI the emphasis is on fundamental processes occurring in the interaction of short laser pulses with atoms, molecules, solids, and plasmas. In the case of laser-atom (molecule) interactions, high power lasers provide the first access to extreme high-intensity conditions above 10'8 Watts/em', a new frontier for nonlinear interaction of photons with atoms and molecules. New phenomena observed include ...

  15. Study and Development of a Laser Based Alignment System

    CERN Multimedia

    Stern, G

    2014-01-01

    CLIC (Compact Linear Collider) has tight requirements regarding pre-alignment of beam related components: 10 µm accuracy over a sliding window of 200 m along the 20 km of linac. To perform such an alignment, a new system is proposed combining laser beam as straight line reference and camera/shutter assemblies as sensors. The poster describes the alignment system and shows results regarding laser pointing stability with respect to time, shutter type, distance and environment. These results give a frame for future building and calibrating of sensors.

  16. Study on profile measurement of extruding tire tread by laser

    Science.gov (United States)

    Wang, LiangCai; Zhang, Wanping; Zhu, Weihu

    1996-10-01

    This paper presents a new 2D measuring system-profile measurement of extruding tire tread by laser. It includes the thickness measurement of extruding tire tread by laser and the width measurement of extruding tire tread using Moire Fringe. The system has been applied to process line of extruding tire tread. Two measuring results have been obtained. One is a standard profile picture of extruding tire tread including seven measuring values. Another one is a series of thickness and width values. When the scanning speed thickness range is thickness < +/- 0.1mm.

  17. Experimental study of population inversion in laser plasmas

    International Nuclear Information System (INIS)

    Bocher, J.L.; Busquet, M.; Combis, P.; Le Breton, J.P.; Louis-Jacquet, M.; Mexmain, J.M.; Naudy, M.

    1986-01-01

    Thin and thick composite targets of various materials (Al, CH, Au) have been irradiated on both circular and linear focal spots with the OCTAL laser facility at wavelengths 1.06 μm and 0.35 μm and laser irradiances 5 10 12 w/cm 2 to 5 10 14 w/cm 2 . X ray spectra in the range 5 - 8 A and 15 - 300 A recorded respectively by means of flat TlaP and grazing incidence spectrographs gave some experimental evidence of population inversion in aluminum plasma

  18. Experimental study of population inversion in laser plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Bocher, J.L.; Busquet, M.; Combis, P.; Le Breton, J.P.; Louis-Jacquet, M.; Mexmain, J.M.; Naudy, M.

    1986-10-01

    Thin and thick composite targets of various materials (Al, CH, Au) have been irradiated on both circular and linear focal spots with the OCTAL laser facility at wavelengths 1.06 ..mu..m and 0.35 ..mu..m and laser irradiances 5 10/sup 12/ w/cm/sup 2/ to 5 10/sup 14/ w/cm/sup 2/. X-ray spectra in the range 5 - 8 A and 15 - 300 A recorded respectively by means of flat TlaP and grazing incidence spectrographs gave some experimental evidence of population inversion in aluminum plasma.

  19. Experimental study of population inversion in laser plasmas

    International Nuclear Information System (INIS)

    Bocher, J.L.; Busquet, M.; Combis, M.; Le Breton, J.P.; Louis-Jacquet, M.; Mexmain, J.M.; Naudy, M.

    1986-06-01

    Thin and thick composite targets of various material (Al, CH, Au) have been irradiated on both circular and linear focal spot with the laser Octal facility at wavelength 1.06 μm and 0.35 μm and laser irradiances (5.10 12 .W/cm 2 to 5.10 14 .W/cm 2 ). X-ray spectra, in the ranges 5-8 A and 15 - 300 A, recorded respectively by means of flat TIAP and grazing incidence spectrographs show an experimental evidence of population inversion in aluminium plasmas

  20. Laser studies of chemical reaction and collision processes

    Energy Technology Data Exchange (ETDEWEB)

    Flynn, G. [Columbia Univ., New York, NY (United States)

    1993-12-01

    This work has concentrated on several interrelated projects in the area of laser photochemistry and photophysics which impinge on a variety of questions in combustion chemistry and general chemical kinetics. Infrared diode laser probes of the quenching of molecules with {open_quotes}chemically significant{close_quotes} amounts of energy in which the energy transferred to the quencher has, for the first time, been separated into its vibrational, rotational, and translational components. Probes of quantum state distributions and velocity profiles for atomic fragments produced in photodissociation reactions have been explored for iodine chloride.

  1. Fabrication of Ta nanoparticles induced by nanosecond laser ablation in ethanol: the study of laser fluence effects

    Science.gov (United States)

    Azadi Kenari, Fariba; Moniri, Samira; Hantehzadeh, Mohammad Reza; Dorranian, Davoud; Ghoranneviss, Mahmood

    2018-05-01

    Tantalum nanoparticles (Ta NPs) were synthesized in ethanol solution by ablation with a 1064 nm Nd:YAG laser. Prepared NPs were investigated by UV-visible absorption spectroscopy, Transmission electron microscopy, X-ray diffraction and Photoluminescence measurement. The average sizes of NPs were calculated to be in the range of 12-18 nm. From the UV-visible studies, the plasmon peak position of Ta NPs was observed in the spectral range of 206-208 nm. The XRD spectra clearly showed the crystalline structure of NPs and various peaks of Ta and Ta2O5. Moreover, the UV region in the PL spectrum included the free exciton and the bound exciton emission correlated with the defect concentration. In fact, the laser ablation in the organic and inorganic solvents is a strong technique to obtain some NPs with particular structures, which are impossible to produce by conventional methods.

  2. Study of Short-Pulsed Laser Retinal Injury Mechanisms By Time-Resolved Imaging of Photomechanical Transients in RPE

    National Research Council Canada - National Science Library

    Lin, Charles

    2000-01-01

    We studied RPE cell damage mechanism for laser duration from 100 femtosec to 5 microsec, and we have investigated the dependence of threshold fluence for cell damage on the laser spot size on the RPE...

  3. Studies on fatigue life enhancement of pre-fatigued spring steel specimens using laser shock peening

    International Nuclear Information System (INIS)

    Ganesh, P.; Sundar, R.; Kumar, H.; Kaul, R.; Ranganathan, K.; Hedaoo, P.; Raghavendra, G.; Anand Kumar, S.; Tiwari, P.; Nagpure, D.C.; Bindra, K.S.; Kukreja, L.M.; Oak, S.M.

    2014-01-01

    Highlights: • Laser peening significantly extended fatigue life of pre-fatigued spring steel. • Increase in fatigue life of laser peened specimens was more than 15 times. • Black PVC tape is an effective coating for laser peening of ground surfaces. • Repeat peening repaired local surface melted regions on laser peened surface. • Technique is effective for life extension of in-service automobile parts. - Abstract: SAE 9260 spring steel specimens after enduring 50% of their mean fatigue life were subjected to laser shock peening using an in-house developed 2.5 J/7 ns pulsed Neodymium-doped Yttrium Aluminum Garnet (Nd:YAG) laser for studying their fatigue life enhancement. In the investigated range of process parameters, laser shock peening resulted in the extension of fatigue life of these partly fatigue damaged specimens by more than 15 times. Contributing factors for the enhanced fatigue life of laser peened specimens are: about 400 μm thick compressed surface layer with magnitude of surface stress in the range of −600 to −700 MPa, about 20% increase in surface hardness and unaltered surface finish. For laser peening of ground steel surface, an adhesive-backed black polyvinyl chloride (PVC) tape has been found to be a superior sacrificial coating than conventionally used black paint. The effect of repeated laser peening treatment was studied to repair locally surface melted regions and the treatment has been found to be effective in re-establishing desired compressive stress pattern on the erstwhile tensile-stressed surface

  4. Study of the dynamic fragmentation of laser shock-loaded metallic target

    International Nuclear Information System (INIS)

    Lescoute, E.

    2010-01-01

    The irradiation of a metallic target by a high power laser pulse induces a shock wave in the material. Under some conditions, it leads to the production of high velocity ejecta which can damage the optical environment (lenses, mirrors, windows, etc.). With the ongoing development of high energy laser facilities designed to achieve inertial confinement fusion, such as the Laser MegaJoule in France or the National Ignition Facility in the USA, the question of debris ejection from metallic samples subjected to intense laser irradiation has become a key issue. It is necessary to understand fragmentation processes induced by laser shock, and to anticipate and quantify generated fragments, in order to design suitable protections and experiments, and to preserve laser facilities. The main fragmentation processes which can occur in a laser-shock-loaded metallic target and generate high velocity ejecta are: (i) micro-jetting, which occurs upon reflection of the incident compressive front from the free surface, (ii) spallation, which is due to the later interaction of the release wave reflected from that surface with the incident unloading wave and (iii) dynamic punching of thin targets. Experimental campaigns have been performed on high energy laser facilities in the Centre d'Etudes Scientifiques et Techniques d'Aquitaine (CESTA, CEA, Alise facility) and in the Laboratoire pour l'Utilisation des Lasers Intenses (LULI, Ecole Polytechnique, LULI 2000 facility). Gold and aluminium have been mainly studied because they are the two main metallic components of the target which will be used to achieved the inertial confinement fusion. Specific diagnostics have been developed and used during these experiments to study the dynamic fragmentation: transverse shadowgraphy, free surface velocity measurement and recovery of generated fragments. Experimental results have been compared with numerical predictions obtained with a bi-dimensional hydrodynamic code, where a specific numerical

  5. Preliminary study of laser welding for aortic dissection in a porcine model using a diode laser with indocyanine green.

    Science.gov (United States)

    Fujita, Masanori; Morimoto, Yuji; Ohmori, Sayaka; Usami, Noriko; Arai, Tsunenori; Maehara, Tadaaki; Kikuchi, Makoto

    2003-01-01

    The objective of this study was to determine whether a dissected aorta could be welded by a diode laser with a solder using an in vitro porcine aortic dissection model. Porcine aortic strips were dissected into two flaps and the dissected faces were immersed in a solution of indocyanine green. The two flaps were pressed at 0.2 kg/cm2 with contact between the two immersed faces. The pressed flaps were irradiated with a diode laser (810 nm) at intensities of 170-425 W/cm2 for 8 seconds. The welded flaps were studied by light microscopy and the adhesive strengths were measured. The irradiated flaps were successfully welded. The breaking stress, the maximum stress recorded in a stress-strain curve, increased with increase in irradiation intensity up to 396 W/cm2 (2.7 x 10(2) mmHg) and decreased when the intensity reached 425 W/cm2. In the specimen irradiated at 396 W/cm2, the welded faces showed continuous fusion of elastin layers, while some voids were seen between the welded faces in the specimen irradiated at 425 W/cm2. The dissected porcine aortas were successfully welded using a laser with solder. The results suggest that the welded aorta can bear physiological blood pressure. Copyright 2003 Wiley-Liss, Inc.

  6. In vitro study of demineralization resistance and fluoride retention in dental enamel irradiated with Er,Cr: YSGG laser

    International Nuclear Information System (INIS)

    Ana, Patricia Aparecida da.

    2007-01-01

    This study aimed to establish irradiation conditions of Er,Cr:YSGG laser (λ of 2.79 μm) which could propitiate changes on human dental enamel and increase its resistance to demineralization, when associated or not with topical application of acidulated phosphate fluoride (APF). Fluences of 2,8 J/cm 2 , 5,6 J/cm 2 e 8,5 J/cm 2 were selected; they were associated or not with previous application of a photo absorber (coal paste) and then APF was applied or not after laser irradiation. In a first step, the morphological findings, the surface temperatures, and the pupal temperatures were evaluated during laser irradiation. After that, the treated samples were submitted to a a ten-day pH-cycling model. After producing the incipient white-spots lesions, the following aspects were evaluated: the mineral loss, the loosely bound fluoride and the firmly bound fluoride. All the demineralizing and remineralizing pH-cycling solutions were evaluated with respect to their calcium (Ca), inorganic phosphorous (Pi) and fluoride (F - ) concentrations. The data had their normality and homogeneity distribution statistically evaluated, and it was chosen an appropriated statistical test for each performed analysis according to the obtained results, considering 5% significant level. The fluences selected for this study created ablated surfaces; the fluences of 5.6 J/cm 2 and 8.5 J/cm 2 promoted increments in surface temperature above 110 deg C. The intrapupal temperature changes revealed that laser irradiation did not increase the pulpal temperatures above the critical threshold for induction of pulpitis. The coal paste did not promote any changes on surface morphology or in the intrapulpal temperature changes; however, this paste increased the surface temperatures during laser irradiation. Only laser irradiation at 8.5 J/cm 2 was able to decrease the mineral loss when compared to the no-treatment group; although the association of coal paste + laser at 2.8 J/cm 2 + APF application

  7. Cryogenic-laser-fusion target implosion studies performed with the OMEGA uv-laser system

    International Nuclear Information System (INIS)

    Marshall, F.J.; Letzring, S.A.; Verdon, C.P.; Skupsky, S.; Keck, R.L.; Knauer, J.P.; Kremens, R.L.; Bradley, D.K.; Kessler, T.; Delettrez, J.; and others.

    1989-01-01

    A series of direct-drive laser-fusion implosion experiments was performed on cryogenically cooled, DT-filled glass microballoons with the OMEGA 24-beam uv (351-nm) laser system. The targets consisted of glass microballoons having radii of 100 to 150 μm, wall thicknesses of 3 to 7 μm, filled with DT gas at pressures of 75 to 100 atm. The targets were cooled to below the freezing point of DT, in situ, by a cryogenic target system. The targets were irradiated by approximately 1 to 1.2 kJ of uv light in 650-ps Gaussian pulses. The on-target irradiation uniformity was enhanced for these experiments by the use of distributed phase plates, which brought the estimated irradiation nonuniformities to ∼12% (σ rms ). Target performance was diagnosed by an array of x-ray, plasma, and nuclear instruments. The measured target performance showed ∼70% absorption, thermonuclear yields of 10 6 to 10 8 neutrons, and final fuel areal densities of 20 to 40 mg/cm 2 for the optimum targets examined in these experiments. Fuel densities at the time of thermonuclear neutron production, inferred from direct measurements of the fuel areal density, were in the range of 20 to 50 g/cm 3 (100 to 200 times the density of liquid DT) for the optimum targets

  8. Experimental study of the interaction of two laser-driven radiative shocks at the PALS laser

    Czech Academy of Sciences Publication Activity Database

    Singh, R.L.; Stehlé, C.; Suzuki-Vidal, F.; Kozlová, Michaela; Larour, J.; Chaulagain, Uddhab P.; Clayson, T.; Rodriguez, R.; Gil, J.M.; Nejdl, Jaroslav; Krůs, Miroslav; Dostál, Jan; Dudžák, Roman; Barroso, P.; Acef, O.; Cotelo, M.; Velarde, P.

    2017-01-01

    Roč. 23, June (2017), s. 20-30 ISSN 1574-1818 R&D Projects: GA MŠk EE2.3.30.0057; GA MŠk EE2.3.20.0279; GA MŠk ED1.1.00/02.0061; GA MŠk(CZ) LM2015083 EU Projects: European Commission(XE) 284464 - LASERLAB-EUROPE Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; OP VK 4 POSTDOK(XE) CZ.1.07/2.3.00/30.0057; LaserZdroj (OP VK 3)(XE) CZ.1.07/2.3.00/20.0279; ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061 Institutional support: RVO:68378271 ; RVO:61389021 Keywords : radiative shocks * hydrodynamics laser-plasmas * spectroscopy * laboratory astrophysics Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 0.908, year: 2016

  9. Reaction between laser ablation plume and ambient gas studied by laser-induced fluorescence imaging spectroscopy

    International Nuclear Information System (INIS)

    Sasaki, K; Watarai, H

    2007-01-01

    We visualized the density distributions of C 2 (plume), NO (ambient gas), and CN (reaction product) when a graphite target was ablated by irradiating YAG laser pulses at wavelengths of 1064 and 355 nm in ambient gas mixture of NO and He. It has been shown by the density distributions of C 2 and NO that the expansion of the plume removes the ambient gas and the plume and the ambient gas locate exclusively in both the cases at 1064 and 355 nm. A high CN density was observed at the interface between the plume and the ambient gas at 1064 nm, which is reasonable since chemical reactions between the plume and the ambient gas may occur only at their interface. On the other hand, in the case at 355 nm, we observed considerable CN inside the plume, indicating that the chemical reaction processes in the laser ablation at 355 nm is different from that expected from the density distributions of the plume and the ambient gas

  10. Food and Drug Administration criteria for the diagnosis of drug-induced valvular heart disease in patients previously exposed to benfluorex: a prospective multicentre study.

    Science.gov (United States)

    Maréchaux, Sylvestre; Rusinaru, Dan; Jobic, Yannick; Ederhy, Stéphane; Donal, Erwan; Réant, Patricia; Arnalsteen, Elise; Boulanger, Jacques; Garban, Thierry; Ennezat, Pierre-Vladimir; Jeu, Antoine; Szymanski, Catherine; Tribouilloy, Christophe

    2015-02-01

    The Food and Drug Administration (FDA) criteria for diagnosis of drug-induced valvular heart disease (DIVHD) are only based on the observation of aortic regurgitation ≥ mild and/or mitral regurgitation ≥ moderate. We sought to evaluate the diagnostic value of FDA criteria in a cohort of control patients and in a cohort of patients exposed to a drug (benfluorex) known to induce VHD. This prospective, multicentre study included 376 diabetic control patients not exposed to valvulopathic drugs and 1000 subjects previously exposed to benfluorex. Diagnosis of mitral or aortic DIVHD was based on a combined functional and morphological echocardiographic analysis of cardiac valves. Patients were classified according to the FDA criteria [mitral or aortic-FDA(+) and mitral or aortic-FDA(-)]. Among the 376 control patients, 2 were wrongly classified as mitral-FDA(+) and 17 as aortic-FDA(+) (0.53 and 4.5% of false positives, respectively). Of those exposed to benfluorex, 48 of 58 with a diagnosis of mitral DIVHD (83%) were classified as mitral-FDA(-), and 901 of the 910 patients (99%) without a diagnosis of the mitral DIVHD group were classified as mitral-FDA(-). All 40 patients with a diagnosis of aortic DIVHD were classified as aortic-FDA(+), and 105 of the 910 patients without a diagnosis of aortic DIVHD (12%) were classified aortic-FDA(+). Older age and lower BMI were independent predictors of disagreement between FDA criteria and the diagnosis of DIVHD in patients exposed to benfluorex (both P ≤ 0.001). FDA criteria solely based on the Doppler detection of cardiac valve regurgitation underestimate for the mitral valve and overestimate for the aortic valve the frequency of DIVHD. Therefore, the diagnosis of DIVHD must be based on a combined echocardiographic and Doppler morphological and functional analysis of cardiac valves. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

  11. SAFETY AND ACTIVITY OF TEMSIROLIMUS AND BEVACIZUMAB IN PATIENTS WITH ADVANCED RENAL CELL CARCINOMA PREVIOUSLY TREATED WITH TYROSINE KINASE INHIBITORS: A PHASE 2 CONSORTIUM STUDY

    Science.gov (United States)

    Merchan, Jaime R.; Qin, Rui; Pitot, Henry; Picus, Joel; Liu, Glenn; Fitch, Tom; Maples, William J.; Flynn, Patrick J.; Fruth, Briant F.; Erlichman, Charles

    2015-01-01

    Purpose Bevacizumab or Temsirolimus regimens have clinical activity in the first line treatment of advanced renal cell carcinoma (RCC). This phase I/II trial was conducted to determine the safety of combining both agents and its efficacy in RCC patients who progressed on at least one prior anti-VEGF receptor tyrosine kinase inhibitor (RTKI) agent. Methods In the phase I portion, eligible patients were treated with Temsirolimus (25 mg IV weekly) and escalating doses of IV Bevacizumab (level 1=5mg/kg; level 2=10 mg/kg) every other week. The primary endpoint for the phase II portion (RTKI resistant patients) was the 6-month progression free rate. Secondary endpoints were response rate, toxicity evaluation, PFS and OS. Results MTD was not reached at the maximum dose administered in 12 phase I patients. Forty evaluable patients were treated with the phase II recommended dose (Temsirolimus 25 mg IV weekly and Bevacizumab 10 mg/kg IV every two weeks). The 6-month progression free rate was 40% (16/40 pts). Median PFS was 5.9 (4-7.8) months, and median OS was 20.6 (11.5-23.7) months. Partial response/stable/progressive disease were seen in 23%/63%/14% of patients. Most common grade 3-4 AEs included fatigue (17.8%), hypertriglyceridemia (11.1%), stomatitis (8.9%), proteinuria (8.9%), abdominal pain (6.7%), and anemia (6.7%). Baseline levels of serum sFLT-1 and VEGF-A were inversely correlated with PFS and OS, respectively. Conclusions Temsirolimus and Bevacizumab is a feasible combination in patients with advanced RCC previously exposed to oral anti-VEGF agents. The safety and efficacy results warrant further confirmatory studies in this patient population. PMID:25556030

  12. Low-calorie energy drink improves physiological response to exercise in previously sedentary men: a placebo-controlled efficacy and safety study.

    Science.gov (United States)

    Lockwood, Christopher M; Moon, Jordan R; Smith, Abbie E; Tobkin, Sarah E; Kendall, Kristina L; Graef, Jennifer L; Cramer, Joel T; Stout, Jeffrey R

    2010-08-01

    Energy drink use has grown despite limited research to support efficacy or safety and amid concerns when combined with exercise. The purpose of this study was to assess the effects of 10 weeks of once-daily energy drink consumption or energy drink consumption with exercise on measures of body composition, cardiorespiratory fitness, strength, mood, and safety in previously sedentary males. Thirty-eight males were randomly assigned to energy drink + exercise (EX-A), energy drink (NEX-A), placebo + exercise (EX-B), or placebo (NEX-B). All participants consumed 1 drink per day for 10 weeks; EX-A and EX-B participated in 10 weeks of resistance and endurance exercise. Testing was performed before (PRE) and after (POST) the 10-week intervention. No significant (p > 0.05) changes were observed for body composition, fitness, or strength in NEX-A; however, significantly greater decreases in fat mass and percentage body fat and increases in VO2peak were observed in EX-A versus EX-B. Ventilatory threshold (VT), minute ventilation, VO2 at VT, and power output at VT improved significantly PRE to POST in EX-A but not in EX-B or nonexercising groups. Clinical markers for hepatic, renal, cardiovascular, and immune function, as determined by PRE and POST blood work revealed no adverse effects in response to the energy drink. Mood was not affected by energy drink use. Absent energy restriction or other dietary controls, chronic ingestion of a once-daily low-calorie energy drink appears ineffective at improving body composition, cardiorespiratory fitness, or strength in sedentary males. However, when combined with exercise, preworkout energy drink consumption may significantly improve some physiological adaptations to combined aerobic and resistance training.

  13. Phase I/II study of gefitinib (Iressa(®)) and vorinostat (IVORI) in previously treated patients with advanced non-small cell lung cancer.

    Science.gov (United States)

    Han, Ji-Youn; Lee, Soo Hyun; Lee, Geon Kook; Yun, Tak; Lee, Young Joo; Hwang, Kum Hui; Kim, Jin Young; Kim, Heung Tae

    2015-03-01

    Vorinostat has been shown to overcome resistance to gefitinib. We performed a phase I/II study combining gefitinib with vorinostat in previously treated non-small cell lung cancer (NSCLC). A 3 + 3 dose-escalation design was used to determine maximum tolerated dose (MTD) and recommended phase II dose (RP2D). Three dose levels were tested: 250 mg/day gefitinib on days 1-28 and 200, 300 or 400 mg/day vorinostat on days 1-7, and 15-21 out of every 28 days. The primary endpoint was median progression-free survival (PFS). Fifty-two patients were enrolled and treated (43 in phase II). The median age was 59 years, 28 patients were male, 44 had adenocarcinoma, 29 had never smoked, and 36 had undergone one prior treatment. Twenty-two patients exhibited sensitive EGFR mutations. Planned dose escalation was completed without reaching the MTD. The RP2D was 250 mg gefitinib and 400 mg vorinostat. In 43 assessable patients in phase II, the median PFS was 3.2 months; the overall survival (OS) was 19.0 months. There were 16 partial responses and six cases of stable disease. In EGFR-mutant NSCLC, response rate was 77 %, median PFS was 9.1 months, and median OS was 24.1 months. The most common adverse events were anorexia and diarrhea. Treatment with 250 mg gefitinib daily with biweekly 400 mg/day vorinostat was feasible and well tolerated. In an unselected patient population, this combination dose did not improve PFS. However, this combination showed a potential for improving efficacy of gefitinib in EGFR-mutant NSCLC (NCT01027676).

  14. Effect of donepezil in patients with Alzheimer's disease previously untreated or treated with memantine or nootropic agents in Germany: an observational study.

    Science.gov (United States)

    Klinger, Tatjana; Ibach, Bernd; Schoenknecht, Peter; Kamleiter, Martin; Silver, Gabrielle; Schroeder, Johannes; Mielke, Ruediger

    2005-05-01

    This open-label, prospective, observational, Post-Marketing Surveillance (PMS) study assessed the efficacy and safety of donepezil in patients who had been switched from therapies currently used in Germany to treat Alzheimer's disease (AD), such as memantine and nootropics, due to insufficient efficacy or poor tolerability. A treatment-naive population was included as a comparator. Patients with AD were treated with donepezil and observed for a period of approximately 3 months. A cognitive assessment was made using the Mini-Mental State Examination (MMSE). Quality of life (QoL) was assessed by the investigators who answered the question 'How did therapy with donepezil influence the QoL of the patient and/or his family over the observation period?' and was graded using three ratings: improved/unchanged/worsened. Adverse events (AEs) were also monitored. A total of 913 patients entered the study (mean +/- SD MMSE score 18.03 +/- 5.34). Efficacy assessments were analyzed for three groups: an overall group of patients who had received any form of prior AD drug therapy (N+ group; n = 709); a subgroup of patients from the N+ group who had received prior memantine therapy only (M+ group; n = 111) and patients who were drug treatment naive (N- group; n = 204). In the evaluable population donepezil improved MMSE scores by 2.21 +/- 3.47 points on average, with similar improvements observed in all three groups. QoL was judged to be improved in at least 70% of patients, again with similar results obtained for all three groups. Donepezil was well tolerated, with 85 of 913 (9.3%) patients reporting AEs. The most common AEs were those typically seen with cholinergic therapies (i.e., diarrhoea, vomiting and nausea). In this observational PMS study, donepezil was shown to be efficacious and well tolerated in patients who were being insufficiently treated with memantine or nootropic therapy. The magnitude of response was similar to that observed in patients who were previously

  15. The impact of laser ablation on optical soft tissue differentiation for tissue specific laser surgery-an experimental ex vivo study

    Directory of Open Access Journals (Sweden)

    Stelzle Florian

    2012-06-01

    Full Text Available Abstract Background Optical diffuse reflectance can remotely differentiate various bio tissues. To implement this technique in an optical feedback system to guide laser surgery in a tissue-specific way, the alteration of optical tissue properties by laser ablation has to be taken into account. It was the aim of this study to evaluate the general feasibility of optical soft tissue differentiation by diffuse reflectance spectroscopy under the influence of laser ablation, comparing the tissue differentiation results before and after laser intervention. Methods A total of 70 ex vivo tissue samples (5 tissue types were taken from 14 bisected pig heads. Diffuse reflectance spectra were recorded before and after Er:YAG-laser ablation. The spectra were analyzed and differentiated using principal component analysis (PCA, followed by linear discriminant analysis (LDA. To assess the potential of tissue differentiation, area under the curve (AUC, sensitivity and specificity was computed for each pair of tissue types before and after laser ablation, and compared to each other. Results Optical tissue differentiation showed good results before laser exposure (total classification error 13.51%. However, the tissue pair nerve and fat yielded lower AUC results of only 0.75. After laser ablation slightly reduced differentiation results were found with a total classification error of 16.83%. The tissue pair nerve and fat showed enhanced differentiation (AUC: 0.85. Laser ablation reduced the sensitivity in 50% and specificity in 80% of the cases of tissue pair comparison. The sensitivity of nerve–fat differentiation was enhanced by 35%. Conclusions The observed results show the general feasibility of tissue differentiation by diffuse reflectance spectroscopy even under conditions of tissue alteration by laser ablation. The contrast enhancement for the differentiation between nerve and fat tissue after ablation is assumed to be due to laser removal of the

  16. Fluorescence line-narrowing studies of Nd:glass laser materials

    International Nuclear Information System (INIS)

    Riseberg, L.A.; Brecher, C.

    The increasing importance of Nd glass lasers in laser fusion technology has emphasized the inadequacy in the understanding of the optical properties of rare earth ions in glasses. Indeed, it has been difficult to generate models for the performance of these devices, and the selection of host glasses could be done by little more than a trial-and-error approach. The technique of laser-induced fluorescence line-narrowing developed within the last few years provides a new and powerful tool for the study of these systems. In this technique, a laser excites within the inhomogeneously broadened absorption bands a selected subgroup of the ions in the system, namely those whose absorption energy is resonant with the laser. If the excitation does not migrate among the entire collection of ions prior to fluorescence, the fluorescence that is observed is only from the group that was excited and is narrowed. This permits the selective study of classes of ion sites within the ensemble. The concept is indicated schematically. By the use of a tunable laser, such as a dye laser, it is possible to vary the class of sites, defined by energy, that is excited and thereby study the important spectroscopic properties and their variations, unclouded by the averaging that occurs under excitation of the entire system. Furthermore, it is then possible to use the spectroscopic information to infer a description of the variation of the microscopic environment, and a rationalization of the effects of compositional changes. Use of a pulsed dye laser and time-resolved detection permits the study of the dynamics, including, for example, the energy transfer among ions of different energies within the inhomogeneously-broadened spectrum. The goal of this project has been to apply such studies to glasses of interest to glass laser technology, providing information for device modeling, and establishing design criteria for glass selection

  17. Study of a low power dissipation, miniature laser-pumped rubidium frequency standard

    Institute of Scientific and Technical Information of China (English)

    Liu Guo-Bin; Zhao Feng; Gu Si-Hong

    2009-01-01

    This paper studies a miniature low power consumption laser-pumped atom vapour cell clock scheme. Pumping 87Rb with a vertical cavity surface emitting laser diode pump and locking the laser frequency on a Doppler-broadened spectral line,it records a 5×10-11τ-1/2 (τ<500 s) frequency stability with a table-top system in a primary experiment.The study reveals that the evaluated scheme is at the level of 2.7 watts power consumption,90 cm3 volume and 10-12τ- 1/2 short-term frequency stability.

  18. Studies of momentum transfer and X-ray spectra in a laser-produced plasma

    International Nuclear Information System (INIS)

    Leroy, Pierre

    Studies of momentum transfer from a ballistic pendulum appear to give satisfactory results for absorbed laser energies in excess of 200 mJ i.e. for fluxes in the 3.10 10 to 3.10 12 W.cm -2 range. A hard X-ray component attributed to fast electrons was revealed by an X-ray spectrometer with a PM system of greater sensitivity than PIN diodes. The laser energy is however too weak to enable studies to be conducted as a function of laser flux or measurements to be performed on targets of low Z [fr

  19. Experimental study on concrete cutting by CO{sub 2} laser beam

    Energy Technology Data Exchange (ETDEWEB)

    Kutsumizu, Akira; Tomura, Hidemasa; Wakizaka, Tatsuya; Hishikawa, Kyoichi; Moriya, Masahiro [Ohbayashi Corp., Tokyo (Japan)

    1994-10-01

    Methods for dismantling nuclear reactor facilities must meet particularly exacting requirements imposed by heavily reinforced and radioactivated reactor shield walls. Conventional methods do not meet all such requirements, however. Intrigued by excellent characteristics of the laser cutting method relative to nuclear facility demolition, we carried out an experimental study to make a comprehensive evaluation of its characteristics, especially for deep cutting, with success in identifying main factors affecting the cutting depth of a laser and characterizing its cutting behavior. The study results indicate that a 50 kW class CO{sub 2} laser has a potential to provide a practicable cutting speed and depth. (author).

  20. Sunburn and sun-protective behaviors among adults with and without previous nonmelanoma skin cancer (NMSC): A population-based study.

    Science.gov (United States)

    Fischer, Alexander H; Wang, Timothy S; Yenokyan, Gayane; Kang, Sewon; Chien, Anna L

    2016-08-01

    Individuals with previous nonmelanoma skin cancer (NMSC) are at increased risk for subsequent skin cancer, and should therefore limit ultraviolet exposure. We sought to determine whether individuals with previous NMSC engage in better sun protection than those with no skin cancer history. We pooled self-reported data (2005 and 2010 National Health Interview Surveys) from US non-Hispanic white adults (758 with and 34,161 without previous NMSC). We calculated adjusted prevalence odds ratios (aPOR) and 95% confidence intervals (CI), taking into account the complex survey design. Individuals with previous NMSC versus no history of NMSC had higher rates of frequent use of shade (44.3% vs 27.0%; aPOR 1.41; 95% CI 1.16-1.71), long sleeves (20.5% vs 7.7%; aPOR 1.55; 95% CI 1.21-1.98), a wide-brimmed hat (26.1% vs 10.5%; aPOR 1.52; 95% CI 1.24-1.87), and sunscreen (53.7% vs 33.1%; aPOR 2.11; 95% CI 1.73-2.59), but did not have significantly lower odds of recent sunburn (29.7% vs 40.7%; aPOR 0.95; 95% CI 0.77-1.17). Among those with previous NMSC, recent sunburn was inversely associated with age, sun avoidance, and shade but not sunscreen. Self-reported cross-sectional data and unavailable information quantifying regular sun exposure are limitations. Physicians should emphasize sunburn prevention when counseling patients with previous NMSC, especially younger adults, focusing on shade and sun avoidance over sunscreen. Copyright © 2016 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

  1. Study of charged fusion products in laser produced plasmas

    International Nuclear Information System (INIS)

    Rosenblum, M.

    1981-07-01

    Charged reaction products play a central role in inertial confinement fusion. The investigation of the various processes these particles undergo in laser produced plasmas, their influence on the dynamics of the fusion and their utilization as a diagnostic tool are the main subjects of this thesis. (author)

  2. Integrated code development for studying laser driven plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Takabe, Hideaki; Nagatomo, Hideo; Sunahara, Atsusi; Ohnishi, Naofumi; Naruo, Syuji; Mima, Kunioki [Osaka Univ., Suita (Japan). Inst. of Laser Engineering

    1998-03-01

    Present status and plan for developing an integrated implosion code are briefly explained by focusing on motivation, numerical scheme and issues to be developed more. Highly nonlinear stage of Rayleigh-Taylor instability of ablation front by laser irradiation has been simulated so as to be compared with model experiments. Improvement in transport and rezoning/remapping algorithms in ILESTA code is described. (author)

  3. RHEED study of titanium dioxide with pulsed laser deposition

    DEFF Research Database (Denmark)

    Rasmussen, Inge Lise; Pryds, Nini; Schou, Jørgen

    2009-01-01

    Reflection high-energy electron diffraction (RHEED) operated at high pressure has been used to monitor the growth of thin films of titanium dioxide (TiO2) on (1 0 0) magnesium oxide (MgO) substrates by pulsed laser deposition (PLD). The deposition is performed with a synthetic rutile TiO2 target...

  4. Flow Profile Study using miniature Laser-Doppler velocimetry

    NARCIS (Netherlands)

    Booij, W.E.; Booij, W.E.; de Jongh, A.; de Mul, F.F.M.

    1995-01-01

    We present a physics experiment, in which laser - Doppler velocimetry is used to make first - year university physics students realize that the idealized solutions offered by standard text books seldom are applicable without corrections, which often are numerical. This is demonstrated by carefully

  5. Laser beam shaping for studying thermally induced damage

    CSIR Research Space (South Africa)

    Masina, BN

    2011-08-01

    Full Text Available into a flat-top beam profile by using a diffractive optical element as a phase element in conjunction with a Fourier transforming lens. In this paper, they have successfully demonstrated temperature profiles across the diamond tool surface using two laser...

  6. Medical application of laser hair removal

    International Nuclear Information System (INIS)

    Fadlalla, Alwalled Hussein Ataalmannan

    2015-12-01

    The use of laser in medical treatment has become of paramount importance proportional to what has high therapeutic privileges such as speed and accuracy in penetrating tissues and high quality especially when used in hair removal which is the subject of our study, this laser operates cards may cause some change in the color of the skin when used in a manner that is correct ratio of the thermal impact force in the laser hair removal process, or if it is exposed directly to his eye. This study is a comparison between the physical properties of laser of lasers used in hair removal, according to previous studies to be the basis for the benefit of doctors who use lasers for hair removal. The aim of this study was to study the effect of laser hair removal using the Nd: YAG laser with a wavelength 1064 nm as well as the risks airing from the assessment. The aim of this study was to identify the appropriate laser energy that absorbed in the hair follicle with a dark color and the appropriate thermal effect occurs to vaporize the follicle cell, a 40 J/cm"2 is to be significant without side effects for healthy tissue. In this study doses for a few laser beam is considered when compared to previous studies. Laser danger to the patient during the operation increases with increasing laser energy emitted during treatment. Laser hair removal by the user and energy emitted by wavelength of the laser device also depends on the hair color and roughness as well as skin color. (Author)

  7. In vitro study for laser gene transfer in BHK-21 fibroblast cell line

    Science.gov (United States)

    Abdel Aziz, M.; Salem, D. S.; Salama, M. S.; Badr, Y.

    2009-02-01

    Modifications to our previously introduced system for laser microbeam cell surgery were carried out in the present work to match animal cells. These modifications included: 1- Using other laser system that used before, Excimer laser with 193 and 308 nm wavelengths. The used laser here, is He-Cd with low power and 441.5 nm wavelength in the visible region. 2- Instead of using pulsed laser, we used here CW He-Cd chopped by electrical chopper, which is synchronized with the mechanical motion of the mobile stage with step 40 microns, according to cell dimensions to avoid puncturing the same cell twice. The advantages of the modified here laser setup for gene transfer is: it is less damaging to the sensitive animal cell which has thin cell membrane. The present work aimed to: 1- Design a modified laser microbeam cell surgery, applicable to animal cells, such as fibroblast cells 2- To examine the efficiency of such system. 3- To assure gene transfer and its expression in the used cells. 4- To evaluate the ultra damages produced from using the laser beam as a modality for gene transfer. On the other wards, to introduce: safe, efficient and less damaging modality for gene transfer in animal cells. To achieve these goals, we applied the introduced here home-made laser setup with its synchronized parameters to introduce pBK-CMV phagemid, containing LacZ and neomycin resistance (neor )genes into BHK-21 fibroblast cell line. The results of the present work showed that: 1- Our modified laser microbeam cell surgery setup proved to be useful and efficient tool for gene transfer into fibroblast cells. 2- The presence and expression of LacZ gene was achieved using histochemical LacZ assay. 3- Selection of G418 antibiotic sensitivity assay confirmed the presence and expression towards stability of neor gene with time. 4- Presence of LacZ and neor genes in the genomic DNA of transfected fibroblast cells was indicated using PCR analysis. 5- Transmission electron microscopy indicated

  8. Studies on free electron lasers using a compact electro-static accelerator. 2. Basic specifications and estimation of the gain

    International Nuclear Information System (INIS)

    Kawamura, Yoshiyuki; Tanabe, Toshiya; Li, Dian-Jun; Toyoda, Koichi

    1994-01-01

    An experimental facility for the studies on sub-millimeter wavelength free electron lasers has been constructed using a micro-wiggler and the relativistic electron beam source described in a previous report. The pitch length, the number of periods, and the peak wiggler magnetic field strength for a gap length of 8 mm, are 12 mm, 50, and 2 kG respectively. The small signal gain as the amplifier has been estimated, and found to be high enough to overcome the loss due to coupling holes of a cavity resonator. (author)

  9. Theoretical and experimental studies of optical feedback on solid-state lasers

    International Nuclear Information System (INIS)

    Kervevan, L.

    2006-12-01

    The main objective of this Phd thesis was to implement solid-state lasers based on codoped Yb 3+ :Er 3+ phosphate glasses pumped by laser diode and to study their behavior when submitted to an optical feedback. This kind of lasers presents as main advantages a very high sensibility to the optical feedback due to the optical properties of the Er 3+ ion enhancing the relaxation oscillations. Moreover, the emission wavelength around 1,535 μm belongs to the eye safe spectral domain. First, we have established the rate equations of the population inversion and the electric field for a three-level laser (Yb:Er) submitted to an optical feedback. We have done a comparative study of the influence of the amplifying medium (three-level system Yb:Er or four-level system LNA:Nd) and cavity parameters on the sensitivity due to the optical feedback. The home-made lasers were implemented in optical feedback experiments allowing original measurement of speed, absolute distance or vibration for optical detection of sound restitution. The fourth part of this thesis deals with the behavior a dual frequency laser submitted to a optical feedback. Such a laser oscillates simultaneously on two polarization eigenstates whose optical frequencies are slightly different. The beating mode between these two eigenstates allows self-heterodyne detection. (author)

  10. Developments towards in-gas-jet laser spectroscopy studies of actinium isotopes at LISOL

    International Nuclear Information System (INIS)

    Raeder, S.; Bastin, B.; Block, M.; Creemers, P.; Delahaye, P.; Ferrer, R.; Fléchard, X.; Franchoo, S.; Ghys, L.; Gaffney, L.P.; Granados, C.; Heinke, R.; Hijazi, L.

    2016-01-01

    To study exotic nuclides at the borders of stability with laser ionization and spectroscopy techniques, highest efficiencies in combination with a high spectral resolution are required. These usually opposing requirements are reconciled by applying the in-gas-laser ionization and spectroscopy (IGLIS) technique in the supersonic gas jet produced by a de Laval nozzle installed at the exit of the stopping gas cell. Carrying out laser ionization in the low-temperature and low density supersonic gas jet eliminates pressure broadening, which will significantly improve the spectral resolution. This article presents the required modifications at the Leuven Isotope Separator On-Line (LISOL) facility that are needed for the first on-line studies of in-gas-jet laser spectroscopy. Different geometries for the gas outlet and extraction ion guides have been tested for their performance regarding the acceptance of laser ionized species as well as for their differential pumping capacities. The specifications and performance of the temporarily installed high repetition rate laser system, including a narrow bandwidth injection-locked Ti:sapphire laser, are discussed and first preliminary results on neutron-deficient actinium isotopes are presented indicating the high capability of this novel technique.

  11. An experimental study on choroidal neovascularization induced by Krypton laser in rat model.

    Science.gov (United States)

    Cui, Jing; Liu, Yuanyuan; Zhang, Jingkai; Yan, Hua

    2014-01-01

    The purpose of this work was to study the efficacy and safety of choroidal neovascularization (CNV) formation induced by Krypton laser in Brown Norway (BN) rats, and observe the trend of the change of CNV after laser photocoagulation. Twenty-five male BN rats were involved in this study. Two eyes of one rat without any laser photocoagulation were randomly selected as the control group, and the other 48 eyes of 24 rats were selected as the experimental group. Eight eyes of four rats were randomly selected to receive the examinations of fundus fluorescein angiography (FFA), histopathology, and transmission electron microscopy 3, 7, 14, 21, 28, and 56 days after laser photocoagulation. After laser photocoagulation, the leakage appeared in burns on day 7 (59%), reached the peak on day 21 (84%), (p0.05). The thickness of CNV increased from day 7 to day 21 (p0.05). The experimental model of CNV can be successfully induced by Krypton laser in rats with a stable, long-lasting, and high success rate. After laser photocoagulation, the leakages appear on day 7, reach the peak on day 21, and remain stable after day 21.

  12. Developments towards in-gas-jet laser spectroscopy studies of actinium isotopes at LISOL

    Energy Technology Data Exchange (ETDEWEB)

    Raeder, S., E-mail: s.raeder@gsi.de [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Helmholtz-Institut Mainz, 55128 Mainz (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Bastin, B. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 55027, 14076 Caen (France); Block, M. [Helmholtz-Institut Mainz, 55128 Mainz (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Institut für Kernchemie, Johannes Gutenberg Universität, 55128 Mainz (Germany); Creemers, P. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Delahaye, P. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 55027, 14076 Caen (France); Ferrer, R. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Fléchard, X. [LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen (France); Franchoo, S. [Institute de Physique Nucléaire (IPN) d’Orsay, 91406 Orsay, Cedex (France); Ghys, L. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); SCK-CEN, Belgian Nuclear Research Center, Boeretang 200, 2400 Mol (Belgium); Gaffney, L.P.; Granados, C. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Heinke, R. [Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz (Germany); Hijazi, L. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 55027, 14076 Caen (France); and others

    2016-06-01

    To study exotic nuclides at the borders of stability with laser ionization and spectroscopy techniques, highest efficiencies in combination with a high spectral resolution are required. These usually opposing requirements are reconciled by applying the in-gas-laser ionization and spectroscopy (IGLIS) technique in the supersonic gas jet produced by a de Laval nozzle installed at the exit of the stopping gas cell. Carrying out laser ionization in the low-temperature and low density supersonic gas jet eliminates pressure broadening, which will significantly improve the spectral resolution. This article presents the required modifications at the Leuven Isotope Separator On-Line (LISOL) facility that are needed for the first on-line studies of in-gas-jet laser spectroscopy. Different geometries for the gas outlet and extraction ion guides have been tested for their performance regarding the acceptance of laser ionized species as well as for their differential pumping capacities. The specifications and performance of the temporarily installed high repetition rate laser system, including a narrow bandwidth injection-locked Ti:sapphire laser, are discussed and first preliminary results on neutron-deficient actinium isotopes are presented indicating the high capability of this novel technique.

  13. Innovation Study for Laser Cutting of Complex Geometries with Paper Materials

    Science.gov (United States)

    Happonen, A.; Stepanov, A.; Piili, H.; Salminen, A.

    Even though technology for laser cutting of paper materials has existed for over 30 years, it seems that results of applications of this technology and possibilities of laser cutting systems are not easily available. The aim of this study was to analyze the feasibility of the complex geometry laser cutting of paper materials and to analyze the innovation challenges and potential of current laser cutting technologies offer. This research studied the potential and possible challenges in applying CO2 laser cutting technology for cutting of paper materials in current supply chains trying to fulfil the changing needs of customer in respect of shape, fast response during rapid delivery cycle. The study is focused on examining and analyzing the different possibilities of laser cutting of paper material in application area of complex low volume geometry cutting. The goal of this case was to analyze the feasibility of the laser cutting from technical, quality and implementation points of view and to discuss availability of new business opportunities. It was noticed that there are new business models still available within laser technology applications in complex geometry cutting. Application of laser technology, in business-to-consume markets, in synergy with Internet service platforms can widen the customer base and offer new value streams for technology and service companies. Because of this, existing markets and competition has to be identified, and appropriate new and innovative business model needs to be developed. And to be competitive in the markets, models like these need to include the earning logic and the stages from production to delivery as discussed in the paper.

  14. Parametric study of transport beam lines for electron beams accelerated by laser-plasma interaction

    Science.gov (United States)

    Scisciò, M.; Lancia, L.; Migliorati, M.; Mostacci, A.; Palumbo, L.; Papaphilippou, Y.; Antici, P.

    2016-03-01

    In the last decade, laser-plasma acceleration of high-energy electrons has attracted strong attention in different fields. Electrons with maximum energies in the GeV range can be laser-accelerated within a few cm using multi-hundreds terawatt (TW) lasers, yielding to very high beam currents at the source (electron bunches with up to tens-hundreds of pC in a few fs). While initially the challenge was to increase the maximum achievable electron energy, today strong effort is put in the control and usability of these laser-generated beams that still lack of some features in order to be used for applications where currently conventional, radio-frequency (RF) based, electron beam lines represent the most common and efficient solution. Several improvements have been suggested for this purpose, some of them acting directly on the plasma source, some using beam shaping tools located downstream. Concerning the latter, several studies have suggested the use of conventional accelerator magnetic devices (such as quadrupoles and solenoids) as an easy implementable solution when the laser-plasma accelerated beam requires optimization. In this paper, we report on a parametric study related to the transport of electron beams accelerated by laser-plasma interaction, using conventional accelerator elements and tools. We focus on both, high energy electron beams in the GeV range, as produced on petawatt (PW) class laser systems, and on lower energy electron beams in the hundreds of MeV range, as nowadays routinely obtained on commercially available multi-hundred TW laser systems. For both scenarios, our study allows understanding what are the crucial parameters that enable laser-plasma accelerators to compete with conventional ones and allow for a beam transport. We show that suitable working points require a tradeoff-combination between low beam divergence and narrow energy spread.

  15. Risks and advantages of using surface laser photogrammetry on free-ranging marine organisms: a case study on white sharks Carcharodon carcharias.

    Science.gov (United States)

    Leurs, G; O'Connell, C P; Andreotti, S; Rutzen, M; Vonk Noordegraaf, H

    2015-06-01

    This study employed a non-lethal measurement tool, which combined an existing photo-identification technique with a surface, parallel laser photogrammetry technique, to accurately estimate the size of free-ranging white sharks Carcharodon carcharias. Findings confirmed the hypothesis that surface laser photogrammetry is more accurate than crew-based estimations that utilized a shark cage of known size as a reference tool. Furthermore, field implementation also revealed that the photographer's angle of reference and the shark's body curvature could greatly influence technique accuracy, exposing two limitations. The findings showed minor inconsistencies with previous studies that examined pre-caudal to total length ratios of dead specimens. This study suggests that surface laser photogrammetry can successfully increase length estimation accuracy and illustrates the potential utility of this technique for growth and stock assessments on free-ranging marine organisms, which will lead to an improvement of the adaptive management of the species. © 2015 The Fisheries Society of the British Isles.

  16. Gender Differences in Laser Acupuncture—Results of a Crossover Study with Green and Yellow Laser at the Ear Point Shenmen

    Science.gov (United States)

    Litscher, Daniela; Wang, Junying; Li, Guangzong; Bosch, Peggy; Wang, Lu

    2018-01-01

    Background: One of the most commonly used auricular acupuncture points selected for different pain treatment regimens is Shenmen. This point on the ear has been recognized as having a wide number of applications, as found by scientific investigation. Methods: Within this crossover study, the ear acupoint Shenmen was stimulated with two different kinds of laser (green, 532 nm and yellow, 589 nm) in 22 healthy volunteers (13 female, 9 male; mean age ± SD = 25.3 ± 4.1 years; range 21–36 years). Both green and yellow lasers were used for 15 min in the same volunteers in two different sessions. Results: The most prominent finding was that systolic blood pressure decreased significantly (p = 0.048) after yellow laser stimulation. Heart rate also decreased significantly (p laser acupuncture. However, a comparison with other publications was impossible because this is the first study using green and yellow laser stimulation on the ear. PMID:29543742

  17. Experimental techniques for subnanosecond resolution of laser-launched plates and impact studies

    Energy Technology Data Exchange (ETDEWEB)

    Paisley, D.L.; Warnes, R.H.; Stahl, D.B. [Los Alamos National Lab., NM (United States). Dynamic Experimentation Div.

    1994-09-01

    Miniature laser-launched plates have applications in shock wave physics, studying dynamic properties of materials and can be used to generate experimental data in a manner similar to a laboratory gas gun for one-dimensional impact experiments. Laser-launched plates have the advantage of small size, low kinetic energy, and can be launched with ubiquitous laboratory lasers. Because of the small size and high accelerations (10{sup 7}--10{sup 10} g`s), improved temporal resolution and optical non-contact methods to collect data are required. Traditional mechanical in-situ gauges would significantly impair the data quality and do not have the required time response.

  18. Studies on a laser driven photoemissive high-brightness electron source and novel photocathodes

    International Nuclear Information System (INIS)

    Geng Rongli; Song Jinhu; Yu Jin

    1997-01-01

    A laser driven photoemissive high-brightness electron source at Beijing University is reported. Through a DC accelerating gap of 100 kV voltage, the device is capable of delivering high-brightness electron beam of 35-100 ps pulse duration when irradiated with a mode-locked YAG laser. The geometry of the gun is optimized with the aid of simulation codes EGUN and POISSON. The results of experimental studies on ion implanted photocathode and cesium telluride photocathode are given. The proposed laser driven superconducting RF gun is also discussed

  19. Laser driven shock wave experiments for equation of state studies at megabar pressures

    CERN Document Server

    Pant, H C; Senecha, V K; Bandyopadhyay, S; Rai, V N; Khare, P; Bhat, R K; Gupta, N K; Godwal, B K

    2002-01-01

    We present the results from laser driven shock wave experiments for equation of state (EOS) studies of gold metal. An Nd:YAG laser chain (2 J, 1.06 mu m wavelength, 200 ps pulse FWHM) is used to generate shocks in planar Al foils and Al + Au layered targets. The EOS of gold in the pressure range of 9-13 Mbar is obtained using the impedance matching technique. The numerical simulations performed using the one-dimensional radiation hydrodynamic code support the experimental results. The present experimental data show remarkable agreement with the existing standard EOS models and with other experimental data obtained independently using laser driven shock wave experiments.

  20. Some studies on weld bead geometries for laser spot welding process using finite element analysis

    International Nuclear Information System (INIS)

    Siva Shanmugam, N.; Buvanashekaran, G.; Sankaranarayanasamy, K.

    2012-01-01

    Highlights: → In this study, a 2 kW Nd:YAG laser welding system is used to conduct laser spot welding trials. → The size and shape of the laser spot weld is predicted using finite element simulation. → The heat input is assumed to be a three-dimensional conical Gaussian heat source. → The result highlights the effect of beam incident angle on laser spot welds. → The achieved results of numerical simulation are almost identical with a real weldment. -- Abstract: Nd:YAG laser beam welding is a high power density welding process which has the capability to focus the beam to a very small spot diameter of about 0.4 mm. It has favorable characteristics namely, low heat input, narrow heat affected zone and lower distortions, as compared to conventional welding processes. In this study, finite element method (FEM) is applied for predicting the weld bead geometry i.e. bead length (BL), bead width (BW) and depth of penetration (DP) in laser spot welding of AISI 304 stainless steel sheet of thickness 2.5 mm. The input parameters of laser spot welding such as beam power, incident angle of the beam and beam exposure time are varied for conducting experimental trials and numerical simulations. Temperature-dependent thermal properties of AISI 304 stainless steel, the effect of latent heat of fusion, and the convective and radiative aspects of boundary conditions are considered while developing the finite element model. The heat input to the developed model is assumed to be a three-dimensional conical Gaussian heat source. Finite-element simulations of laser spot welding were carried out by using Ansys Parametric Design Language (APDL) available in finite-element code, ANSYS. The results of the numerical analysis provide the shape of the weld beads for different ranges of laser input parameters that are subsequently compared with the results obtained through experimentation and it is found that they are in good agreement.

  1. Wavelength dependence in laser floating zone processing. A case study with Bi-Sr-Ca-Cu-O superconductors

    International Nuclear Information System (INIS)

    Fuente, G.F. de la; Diez, J.C.; Angurel, L.A.; Pena, J.I.; Sotelo, A.; Navarro, R.

    1995-01-01

    Laser floating zone processing methods are particularly suitable for studying crystal growth and the development of texture from the melt in many materials used in electrooptics, for example. A system is described that allows different laser wavelengths to be used, and first results on BSCCO superconducting fibers processed using different lasers are presented. (orig.)

  2. A cross-sectional study of 'yaws' in districts of Ghana which have previously undertaken azithromycin mass drug administration for trachoma control.

    Directory of Open Access Journals (Sweden)

    Rosanna Ghinai

    2015-01-01

    Full Text Available Yaws, caused by Treponema pallidum ssp. pertenue, is reportedly endemic in Ghana. Mass distribution of azithromycin is now the cornerstone of the WHO yaws eradication campaign. Mass distribution of azithromycin at a lower target dose was previously undertaken in two regions of Ghana for the control of trachoma. Ongoing reporting of yaws raises the possibility that resistance may have emerged in T. pallidum pertenue, or that alternative infections may be responsible for some of the reported cases. We conducted a cross-sectional survey in thirty communities in two districts of Ghana where MDA for trachoma had previously been conducted. Children aged 5-17 years with ulcerative lesions compatible with yaws were enrolled. Samples for treponemal serology and lesion PCR were collected from all children. 90 children with 98 lesions were enrolled. Syphilis serology was negative in all of them. PCR for T. pallidum ssp pertenue was negative in all children, but Haemophilus ducreyi DNA was detected in 9 lesions. In these communities, previously treated for trachoma, we found no evidence of ongoing transmission of yaws. H. ducreyi was associated with a proportion of skin lesions, but the majority of lesions remain unexplained. Integration of diagnostic testing into both pre and post-MDA surveillance systems is required to better inform yaws control programmes.

  3. Experimental study on 800 nm femtosecond laser ablation of fused silica in air and vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Shi-zhen, E-mail: xusz@uestc.edu.cn [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Yao, Cai-zhen; Liao, Wei [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Yuan, Xiao-dong, E-mail: yxd66my@163.com [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Wang, Tao [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Zu, Xiao-tao [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2016-10-15

    Ablation rates of fused silica were studied as a function of femtosecond laser pulse fluences (0.7–41 J/cm{sup 2}) in air and vacuum. The experiment was conducted by using a Ti:sapphire laser that emits radiation at 800 nm with a pulse width of 35 fs and a repetition rate of 10 Hz. The morphology and ablation depth of laser-induced damage crater were evaluated by using optical microscopy and scanning electron microscopy (SEM). Ablation rates were calculated from the depth of craters induced by multiple laser pulses. Results showed that two ablation regimes, i.e. non-thermal and thermal ablation co-existed in air and vacuum at low and moderate fluences. A drop of ablation rate was observed at high fluence (higher than 9.5 J/cm{sup 2}) in air. While in vacuum, the ablation rate increased continuously with the increasing of laser fluence and much higher than that in air. The drop of ablation rate observed at high fluence in air was due to the strong defocusing effects associated with the non-equilibrium ionization of air. Furthermore, the laser-induced damage threshold (LIDT), which was determined from the relationship between crater area and the logarithm of laser energy, was found to depend on the number of incident pulses on the same spot, and similar phenomenon was observed in air and vacuum.

  4. A comparative study on laser induced shock cleaning of radioactive contaminants in air and water

    Science.gov (United States)

    Kumar, Aniruddha; Prasad, Manisha; Bhatt, R. B.; Behere, P. G.; Biswas, D. J.

    2018-03-01

    Efficient removal of Uranium-di-oxide (UO2) particulates from stainless steel surface was effected by Nd-YAG laser induced plasma shock waves in air as well as in water environment. The propagation velocity of the generated shock wave was measured by employing the photo-acoustic probe deflection method. Monitoring of the alpha activity of the sample with a ZnS (Ag) scintillation detector before and after the laser exposure allowed the estimation of decontamination efficiency defined as the percentage removal of the initial activity. Experiments were carried out to study the effect of laser pulse energy, number of laser exposures, orientation of the sample, the separation between the substrate surface and the onset point of the shock wave on the de-contamination efficiency. The most optimised cleaning was found to occur when the laser beam impinged normally on the sample that was immersed in water and placed at a distance of ∼0.7 mm from the laser focal spot. Analysis of the cleaned surface by optical microscopes established that laser induced shock cleaning in no way altered the surface property. The shock force generated in both air and water has been estimated theoretically and has been found to exceed the Van der Waal's binding force for spherical contaminant particulate.

  5. Laser-generated acoustic wave studies on tattoo pigment

    Science.gov (United States)

    Paterson, Lorna M.; Dickinson, Mark R.; King, Terence A.

    1996-01-01

    A Q-switched alexandrite laser (180 ns at 755 nm) was used to irradiate samples of agar embedded with red, black and green tattoo dyes. The acoustic waves generated in the samples were detected using a PVDF membrane hydrophone and compared to theoretical expectations. The laser pulses were found to generate acoustic waves in the black and green samples but not in the red pigment. Pressures of up to 1.4 MPa were produced with irradiances of up to 96 MWcm-2 which is comparable to the irradiances used to clear pigment embedded in skin. The pressure gradient generated across pigment particles was approximately 1.09 X 1010 Pam-1 giving a pressure difference of 1.09 +/- 0.17 MPa over a particle with mean diameter 100 micrometers . This is not sufficient to permanently damage skin which has a tensile strength of 7.4 MPa.

  6. Study of pseudo noise CW diode laser for ranging applications

    Science.gov (United States)

    Lee, Hyo S.; Ramaswami, Ravi

    1992-01-01

    A new Pseudo Random Noise (PN) modulated CW diode laser radar system is being developed for real time ranging of targets at both close and large distances (greater than 10 KM) to satisy a wide range of applications: from robotics to future space applications. Results from computer modeling and statistical analysis, along with some preliminary data obtained from a prototype system, are presented. The received signal is averaged for a short time to recover the target response function. It is found that even with uncooperative targets, based on the design parameters used (200-mW laser and 20-cm receiver), accurate ranging is possible up to about 15 KM, beyond which signal to noise ratio (SNR) becomes too small for real time analog detection.

  7. Laser Spark Formamide Decomposition Studied by FT-IR Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Ferus, Martin; Kubelík, Petr; Civiš, Svatopluk

    2011-01-01

    Roč. 115, č. 44 (2011), s. 12132-12141 ISSN 1089-5639 R&D Projects: GA AV ČR IAA400400705; GA AV ČR IAAX00100903; GA ČR GAP208/10/2302 Institutional research plan: CEZ:AV0Z40400503 Keywords : FT-IR spectroscopy * high-power laser * induced dielectric-breakdown Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.946, year: 2011

  8. Langmuir probe study of plasma expansion in pulsed laser ablation

    DEFF Research Database (Denmark)

    Hansen, T.N.; Schou, Jørgen; Lunney, J.G.

    1999-01-01

    Langmuir probes were used to monitor the asymptotic expansion of the plasma produced by the laser ablation of a silver target in a vacuum. The measured angular and temporal distributions of the ion flux and electron temperature were found to be in good agreement with the self-similar isentropic...... and adiabatic solution of the gas dynamics equations describing the expansion. The value of the adiabatic index gamma was about 1.25, consistent with the ablation plume being a low temperature plasma....

  9. High energy laser optics manufacturing: a preliminary study

    International Nuclear Information System (INIS)

    Baird, E.D.

    1980-07-01

    This report presents concepts and methods, major conclusions, and major recommendations concerning the fabrication of high energy laser optics (HELO) that are to be machined by the Large Optics Diamond Turning Machine (LODTM) at the Lawrence Livermore National Laboratory (LLNL). Detailed discussions of concepts and methods proposed for metrological operations, polishing of reflective surfaces, mounting of optical components, construction of mirror substrates, and applications of coatings are included

  10. Laser stimulating ST36 with optical fiber induce blood component changes in mice: a Raman spectroscopy study.

    Science.gov (United States)

    Zhang, Heng; Chen, Zhenyi; Wu, Jiping; Chen, Na; Xu, Wenjie; Li, Taihao; Liu, Shupeng

    2018-02-15

    ST36 is a commonly-used acupoint in traditional Chinese medicine (TCM) for treatment of inflammations, pains and gastrointestinal disturbs. For decades, the low power laser acupuncture has been widely applied as an alternative therapy to traditional metal needle acupuncture and achieved relatively fine therapeutic effect for ST36-related symptoms with reduction of uncomfortableness and infection risks. However its disadvantages of low penetrativity and lack of manipulation skills limit its potential performance. An optical fiber laser acupuncture introduced by the previous study combines traditional needling acupuncture and the laser stimulation together, making a stronger therapeutic effect and showing a potential value in clinical application. To evaluate its acupunctural effect on blood, mice are taken as experimental model and Raman spectroscopic technique is used to analysis the changes of blood components after stimulating on ST36. The results show that both the traditional needling acupuncture and optical fiber acupuncture could lead to some spectral changes of blood in mice. This study explores the optical fiber acupuncture's effect on blood in mice using Raman spectroscopy technique for mechanism of acupuncture therapy. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Laser Velocimeter for Studies of Microgravity Combustion Flowfields

    Science.gov (United States)

    Varghese, Philip L.

    2003-01-01

    A velocimeter was developed based on modulated filtered Rayleigh scattering (MFRS). The MFRS velocimeter was successfully demonstrated by making one-component velocity measurements in a supersonic expansion using molecular Rayleigh scattering in a jet of N2. These measurements were made in a sweep mode where the Rayleigh scattered profile is cross-correlated with absorption in a static cell to determine velocity. To improve temporal resolution the frequency-locked mode of operation was developed, with an in-situ referencing scheme to compensate for signal fluctuations arising from density variations in the probe volume. Spectroscopic grade (i.e. continuously tunable, single-mode) laser sources with high power (greater than 100 mW) are not commercially available at the wavelength of interest (780 nm). We developed an all-solid-state system with a low power (approximately 10 mW) spectroscopic grade laser source in a Littrow cavity is amplified by a broad-area diode laser. We have demonstrated that the slaved output tracks the injected input but have not yet demonstrated power gain by the end of the grant period.

  12. Semi-analytical fluid study of the laser wake field excitation in the strong intensity regime

    Energy Technology Data Exchange (ETDEWEB)

    Jovanović, D., E-mail: djovanov@ipb.ac.rs [Institute of Physics, University of Belgrade, Belgrade (Serbia); Fedele, R., E-mail: renato.fedele@na.infn.it [Dipartimento di Fisica, Universitá di Napoli Federico II, Napoli (Italy); INFN Sezione di Napoli, Napoli (Italy); Belić, M., E-mail: milivoj.belic@qatar.tamu.edu [Texas A & M University at Qatar, Doha (Qatar); De Nicola, S., E-mail: sergio.denicola@spin.cnr.it [Dipartimento di Fisica, Universitá di Napoli Federico II, Napoli (Italy); INFN Sezione di Napoli, Napoli (Italy); CNR-SPIN, Complesso Universitario di Monte S' Angelo, Napoli (Italy)

    2016-09-01

    We present an analytical and numerical study of the interaction of a multi-petawatt, pancake-shaped laser pulse with an unmagnetized plasma. The study has been performed in the ultrarelativistic regime of electron jitter velocities, in which the plasma electrons are almost completely expelled from the pulse region. The calculations are applied to a laser wake field acceleration scheme with specifications that may be available in the next generation of Ti:Sa lasers and with the use of recently developed pulse compression techniques. A set of novel nonlinear equations is derived using a three-timescale description, with an intermediate timescale associated with the nonlinear phase of the electromagnetic wave and with the spatial bending of its wave front. They describe, on an equal footing, both the strong and the moderate laser intensity regimes, pertinent to the core and to the edges of the pulse.

  13. Comparative study of digital laser film and analog paper image recordings

    International Nuclear Information System (INIS)

    Lee, K.R.; Cox, G.G.; Templeton, A.W.; Preston, D.F.; Anderson, W.H.; Hensley, K.S.; Dwyer, S.J.

    1987-01-01

    The increase in the use of various imaging modalities demands higher quality and more efficacious analog image recordings. Laser electronic recordings with digital array prints of 4,000 x 5,000 x 12 bits obtained using laser-sensitive film or paper are being evaluated. Dry silver paper recordings are being improved and evaluated. High-resolution paper dot printers are being studied to determine their gray-scale capabilities. The authors evaluated the image quality, costs, clinical utilization, and acceptability of CT scans, MR images, digital subtraction angiograms, digital radiographs, and radionuclide scans recorded by seven different printers (three laser, three silver paper, and one dot) and compared the same features in conventional film recording. This exhibit outlines the technical developments and instrumentation of digital laser film and analog paper recorders and presents the results of the study

  14. Studies of photoionization in liquids using a laser two-photon ionization conductivity technique

    International Nuclear Information System (INIS)

    Siomos, K.; Christophorou, L.G.

    1981-01-01

    One-photon ionization studies of solute molecules in a liquid medium are limited by the absorption of the host medium. A laser two-photon ionization (TPI) technique using a frequency tunable dye laser has been developed, whereby the photoionization threshold of a solute molecule was determined from the induced conductivity in the liquid medium under study due to electron-ion pair formation via two-photon ionization of the solute. The two-photon induced electron-ion current is measured as a function of the laser wavelength, lambda/sub laser/. In this paper, results are reported and discussed on the photoionization of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD), pyrene and fluoranthene in liquid n-pentane

  15. A study of the effect of low intensity laser therapy on the osseointegration of hydroxyapatite implants

    International Nuclear Information System (INIS)

    Rajab, A.A.

    1999-01-01

    were as follows: 1. There was a significant increase in both LILT energy groups by comparison with control at 4 weeks in the x-ray microtomographic interface density index (IDI) with a trend towards maximal values in the low energy group. At 12 weeks there was no significant difference between groups. 2. There was a trend towards increased results for the laser groups at 4 weeks in both the mechanical push out tests (interface shear strength ISS) and radiovisiography (interface radiographic density IRD). There was however no increase noted at 12 weeks for either modality, indeed there was a trend towards equilibrium in the laser groups. 3. Histological study showed sound osseointegration at both 4 and 12 weeks in all groups. There was a trend towards increased bone deposition in the laser groups at 4 weeks and an impression of increased remodelling in the same groups at 12 weeks. 4. Histomorphometry showed a significant increase in the fluorochrome labelled volume fraction percentage (tetracycline, calcein green) for the 2 week period in the laser groups. At 12 weeks there was a significant reduction (whole labelling) for the laser groups, which could relate to the increased remodelling activity observed by plain histology previously mentioned. 5. Overall the pattern of response for the implants at both jaw and femur was similar, despite the seemingly adverse factors in the mandibular site of potential bacterial contamination and dentally invoked infection. 6. The evolved technique of investigation including XMT histomorphometry, push out tests and RVG, proved to be a meaningful combination for the investigation of the effect of LILT on osseointegration of implants. XMT proved to be the most objective of the methods examined for quantitative evaluation. Push out tests and RVG however require careful evaluation and improved standardisation in the case of RVG. 7. The results of this work indicate a potential for the enhancement of early osseointegration of HA implants

  16. Hypospadias repair using laser tissue soldering (LTS): preliminary results of a prospective randomized study

    Science.gov (United States)

    Kirsch, Andrew J.; Cooper, Christopher S.; Canning, Douglas A.; Snyder, Howard M., III; Zderic, Stephen A.

    1998-07-01

    Purpose: The purpose of this study was to evaluate laser tissue soldering using an 808 nm diode laser and wavelength- matched human albumin solder for urethral surgery in children. Methods: Currently, 30 boys, ages 3 months to 8 years were randomized to standard suturing (n equals 22) or 'sutureless' laser hypospadias repair (n equals 18). Laser soldering was performed with a human albumin solder doped with indocyanine green dye (2.5 mg/ml) using a laser power output of 0.5 W, pulse duration of 0.5 sec, and interval of 0.1 sec. Power density was approximately 16 W/cm2. In the laser group, sutures were used for tissue alignment only. At the time of surgery, neourethral and penile lengths, operative time for urethral repair, and number of sutures/throws were measured. Postoperatively, patients were examined for complications of wound healing, stricture, or fistula formation. Results: Mean age, severity of urethral defect, type of repair, and neourethra length were equivalent between the two groups. Operative time was significantly faster for laser soldering in both simple (1.6 plus or minus 0.21 min, p less than 0.001) and complex (5.4 plus or minus 0.28 min, p less than 0.0001) hypospadias repairs compared to controls (10.6 plus or minus 1.4 min and 27.8 plus or minus 2.9 min, respectively). The mean number of sutures used in the laser group for simple and complex repairs (3.3 plus or minus 0.3 and 8.1 plus or minus 0.64, respectively) were significantly (p less than 0.0001) less than for controls (8.2 plus or minus 0.84 and 20 plus or minus 2.3, respectively). Followup was between 3 months and 14 months. The overall complication rate in the laser group (11%) was lower than the controls (23%). However, statistical significance (p less than 0.05) was achieved only for the subgroup of patients undergoing simple repairs (LTS, 100% success versus suturing, 69% success). Conclusions: These preliminary results indicate that laser tissue soldering for hypospadias repair

  17. Study etching characteristics of a track detector CR-39 with ultraviolet laser irradiation

    International Nuclear Information System (INIS)

    Dwaikat, Nidal; Iida, Toshiyuki; Sato, Fuminobu; Kato, Yushi; Ishikawa, Ippei; Kada, Wataru; Kishi, Atsuya; Sakai, Makoto; Ihara, Yohei

    2007-01-01

    The effect of pulsed ultraviolet Indium-doped Yttrium Aluminum Garnet (UV-In:YAG) laser of λ=266 nm, pulse energy 42 mJ/pulse at repetition rate10 Hz on the etching characteristics of Japanese CR-39 was studied at various energy intensities. Fifteen detectors were divided into two sets, each of seven samples and one sample was kept as a reference.The first set (post-exposed) was first exposed to alpha radiation with close contact to 241 Am and then treated in air with laser in the energy intensity range from 40 to160 J/cm 2 , 20 J/cm 2 in step. The second set (pre-exposed) was irradiated in reverse process (laser+alpha) with the same sources as the first set and under the same condition. The laser energy intensities ranged between 20 and 140 J/cm 2 , 20 J/cm 2 in step. For post-exposed samples (alpha+laser) bulk etch rate decreases up to 60 J/cm 2 and increases thereafter, while for pre-exposed samples (laser+alpha) the bulk etch rate oscillates without showing any precise periodicity. The bulk etch rate for both sets was found to be the same at 60≤energy intensity≤80 J/cm 2 and this may indicate that the same structural changes have happened. The track etch rate was found to be equal to the bulk etch rate for both sets, so the sensitivity is constant. In both sets several changes on the detector surfaces: tracks of different sizes and shapes and high density within the laser spot were observed. Out of the laser spot, the tracks become larger and lower density, indicating cross-linking and scission have happened, simultaneously, on the same surface as a result of UV-laser irradiation

  18. Spectroscopic studies on diamond like carbon films synthesized by pulsed laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Panda, Madhusmita; Krishnan, R., E-mail: krish@igcar.gov.in; Ravindran, T. R.; Das, Arindam; Mangamma, G.; Dash, S.; Tyagi, A. K. [Material Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam - 603102, Tamil Nadu (India)

    2016-05-23

    Hydrogen free Diamond like Carbon (DLC) thin films enriched with C-C sp{sup 3} bonding were grown on Si (111) substrates at laser pulse energies varying from 100 to 400 mJ (DLC-100, DLC-200, DLC-300, DLC-400), by Pulsed Laser Ablation (PLA) utilizing an Nd:YAG laser operating at fundamental wavelength. Structural, optical and morphological evolutions as a function of laser pulse energy were studied by micro Raman, UV-Vis spectroscopic studies and Atomic Force Microscopy (AFM), respectively. Raman spectra analysis provided critical clues for the variation in sp{sup 3} content and optical energy gap. The sp{sup 3} content was estimated using the FWHM of the G peak and found to be in the range of 62-69%. The trend of evolution of sp{sup 3} content matches well with the evolution of I{sub D}/I{sub G} ratio with pulse energy. UV-Vis absorption study of DLC films revealed the variation of optical energy gap with laser pulse energy (1.88 – 2.23 eV), which matches well with the evolution of G-Peak position of the Raman spectra. AFM study revealed that roughness, size and density of particulate in DLC films increase with laser pulse energy.

  19. Axicon-based annular laser trap for studies on sperm activity

    Science.gov (United States)

    Shao, Bing; Vinson, Jaclyn M.; Botvinick, Elliot L.; Esener, Sadik C.; Berns, Michael W.

    2005-08-01

    As a powerful and noninvasive tool, laser trapping has been widely applied for the confinement and physiological study of biological cells and organelles. Researchers have used the single spot laser trap to hold individual sperm and quantitatively evaluated the motile force generated by a sperm. Early studies revealed the relationship between sperm motility and swimming behavior and helped the investigations in medical aspects of sperm activity. As sperm chemotaxis draws more and more interest in fertilization research, the studies on sperm-egg communication may help to explain male or female infertility and provide exciting new approaches to contraception. However, single spot laser trapping can only be used to investigate an individual target, which has limits in efficiency and throughput. To study the chemotactic response of sperm to eggs and to characterize sperm motility, an annular laser trap with a diameter of several hundred microns is designed, simulated with ray tracing tool, and implemented. An axicon transforms the wavefront such that the laser beam is incident on the microscope objective from all directions while filling the back aperture completely for high efficiency trapping. A trapping experiment with microspheres is carried out to evaluate the system performance. The power requirement for annular sperm trapping is determined experimentally and compared with theoretical calculations. With a chemo-attractant located in the center and sperm approaching from all directions, the annular laser trapping could serve as a speed bump for sperm so that motility characterization and fertility sorting can be performed efficiently.

  20. Studies of multi-wavelength laser-induced damage on KDP crystals in the nanosecond regime

    International Nuclear Information System (INIS)

    Reyne, Stephane

    2011-01-01

    This thesis interests in the laser-induced damage mechanisms of KDP and DKDP crystals in the nanosecond regime. KDP is a non-linear material particularly used in the frequency converters of the Laser MegaJoule, which is under construction at the CEA-Cesta in France. For this facility, the KDP laser damage resistance is one of the keystones and is still under investigations to fix this problem. This is why this manuscript presents different studies which highlight the two main aspects of the nanosecond laser-induced damage of KDP frequency converters: the precursor defects and the mechanisms to initiate damage. First, we propose a study based on the analysis of several photos obtained by DIC microscopy of damage initiated by different wavelengths. A comparison with a code coupling the energy deposition and hydrodynamic is also done. Then, we interest in the influence of the defects geometry through a study based on the laser polarization effect on the laser damage resistance. By the comparison with a CEA home-made code, this study particularly underlines the possibility to define a new geometry for the precursor defects. This geometry proposed has the shape of an ellipsoid and is supposed to keep the crystal structure properties. Finally, we enlarge on the physical mechanisms initiating laser damage with pump-pump experiments. These tests consist in combining two radiations of different wavelengths which impacting the crystal simultaneously or are delayed one by the other. We then observe the influence of this wavelengths mixing on the KDP laser damage resistance. In particular, a coupling effect between the wavelengths of the mixture may occur as a function of the fluences combination. Finally, the goal of these specific studies is to accumulate new data in order to improve the understanding in the initiation of the laser damage in KDP and DKDP crystals in the nanosecond regime. In the end, these data will allow us to develop predictive models to simulate the laser

  1. Study of mode locking in a microwave-pumped diode laser close to the generation threshold

    International Nuclear Information System (INIS)

    Bagaev, Sergei N; Zakharyash, Valerii F; Kashirsky, Aleksandr V; Klementyev, Vasilii M; Kuznetsov, Sergei A; Pivtsov, V S

    2004-01-01

    Active mode locking is studied in a diode laser with a three-mirror resonator upon the microwave modulation of the pump current. The mode-locking region with the minimal width of the spectrum of intermode beats is found, when the microwave frequency is close to the intermode frequency of an external resonator. This region is shown to be located close to the threshold pump current. (lasers, active media)

  2. Nonintrusive gas monitoring in neonatal lungs using diode laser spectroscopy: feasibility study.

    Science.gov (United States)

    Lewander, Märta; Bruzelius, Anders; Svanberg, Sune; Svanberg, Katarina; Fellman, Vineta

    2011-12-01

    A feasibility study on noninvasive, real-time monitoring of gases in lungs of preterm infants is reported, where a laser-spectroscopic technique using diode lasers tuned to oxygen and water vapor absorption lines was employed on realistic tissue phantoms. Our work suggests that the technique could provide a new possibility for surveillance of the lung function of preterm infants, in particular the oxygenation, which is of prime importance in this patient group.

  3. Studies of Lifetimes in an Ion Storage Ring Using Laser Technique

    International Nuclear Information System (INIS)

    Rostohar, Danijela; Derkatch, Anna; Hartman, Henrik; Norlin, Lars-Olov; Royen, Peder; Schef, Peter; Mannervik, Sven

    2003-01-01

    The laser-probing method for lifetime measurements of metastable levels, performed by applying the Fast Ion Beam Laser (FIBLAS) method to ions stored in a storage ring, has been developed by the Stockholm group. Recently, we have applied this method to lifetime measurements of close lying metastable levels. In this paper we discuss experimental studies of ions with complex structure and present the first experimentally obtained lifetimes of selected metastable levels in complex systems as Fe + , Eu + and La + .

  4. Study of the high power laser-metal interactions in the gaseous atmospheres

    Science.gov (United States)

    Lugomer, Stjepan; Bitelli, G.; Stipancic, M.; Jovic, F.

    1994-08-01

    The tantalum and titanium plates were treated by pulsed, high power CO2 laser in the pressurized atmospheres of N2 and O2. Studies performed by the optical microscopy, microhardness measurements, and the auger electron spectroscopy revealed: (1) topographic modification of the surface caused by the temperature field; (2) metal hardening, caused by the laser shock; and (3) alloying/cladding, caused by the chemical reaction between the metal surface and the gaseous atmosphere.

  5. Carbon dioxide laser versus erbium:YAG laser in treatment of epidermal verrucous nevus: a comparative randomized clinical study.

    Science.gov (United States)

    Osman, Mai Abdel Raouf; Kassab, Ahmed Nazmi

    2017-08-01

    A verrucous epidermal nevus (VEN) is a skin disorder that has been treated using different treatment modalities with varying results. Ablative lasers such as carbon dioxide laser (CO 2 ) and erbium:yttrium-aluminum-garnet (Er:YAG) laser have been considered as the gold standard for the treatment of epidermal nevi. To evaluate and compare the efficacy, postoperative wound healing and side effects of pulsed CO 2 laser and Er:YAG laser for the treatment of verrucous epidermal nevi. Twenty patients with localized VEN were randomly divided into two groups. Group 1 was administered CO 2 laser and group 2 underwent Er:YAG laser treatment. A blinded physician evaluated the photographs and dermoscopic photomicrographs for the efficacy and possible side effects. All patients received one treatment session and were followed up over a 6-month period. Both lasers induced noticeable clinical improvement, but there were no significant differences between two lasers in treatment response, patient satisfaction, duration of erythema and side effects. The average time to re-epithelialization was 13.5 days with CO 2 and 7.9 days with Er:YAG laser (plaser group and no lesional recurrence was detected in CO 2 laser group since treatment. Apart from re-epithelialization, both lasers showed equivalent outcomes with respect to treatment response, patient satisfaction, side effects and complications.

  6. CO2 and diode laser for excisional biopsies of oral mucosal lesions. A pilot study evaluating clinical and histopathological parameters.

    Science.gov (United States)

    Suter, Valérie G A; Altermatt, Hans Jörg; Sendi, Pedram; Mettraux, Gérald; Bornstein, Michael M

    2010-01-01

    The present pilot study evaluates the histopathological characteristics and suitability of CO2 and diode lasers for performing excisional biopsies in the buccal mucosa with special emphasis on the extent of the thermal damage zone created. 15 patients agreed to undergo surgical removal of their fibrous hyperplasias with a laser. These patients were randomly assigned to one diode or two CO2 laser groups. The CO2 laser was used in a continuous wave mode (cw) with a power of 5 W (Watts), and in a pulsed char-free mode (cf). Power settings for the diode laser were 5.12 W in a pulsed mode. The thermal damage zone of the three lasers and intraoperative and postoperative complications were assessed and compared. The collateral thermal damage zone on the borders of the excisional biopsies was significantly smaller with the CO, laser for both settings tested compared to the diode laser regarding values in pm or histopathological index scores. The only intraoperative complication encountered was bleeding, which had to be controlled with electrocauterization. No postoperative complications occurred in any of the three groups. The CO2 laser seems to be appropriate for excisional biopsies of benign oral mucosal lesions. The CO2 laser offers clear advantages in terms of smaller thermal damage zones over the diode laser. More study participants are needed to demonstrate potential differences between the two different CO2 laser settings tested.

  7. Laser Therapy in the Treatment of Paresthesia: A Retrospective Study of 125 Clinical Cases.

    Science.gov (United States)

    de Oliveira, Renata Ferreira; da Silva, Alessandro Costa; Simões, Alyne; Youssef, Michel Nicolau; de Freitas, Patrícia Moreira

    2015-08-01

    The aim of this retrospective study was to evaluate the effectiveness of laser therapy for acceleration and recovery of nerve sensitivity after orthognathic or minor oral surgeries, by analysis of clinical records of patients treated at the Special Laboratory of Lasers in Dentistry (LELO, School of Dentistry, University of São Paulo), throughout the period 2007-2013. Nerve tissue lesions may occur during various dental and routine surgical procedures, resulting in paresthesia. Laser therapy has been shown to be able to accelerate and enhance the regeneration of the affected nerve tissue; however, there are few studies in the literature that evaluate the effects of treatment with low-power laser on neural changes after orthognathic or minor oral surgeries. A total of 125 clinical records were included, and the data on gender, age, origin of the lesion, nerve, interval between surgery and onset of laser therapy, frequency of laser irradiation (one or two times per week), final evolution, and if there was a need to change the irradiation protocol, were all recorded. These data were related to the recovery of sensitivity in the affected nerve area. Descriptive analyses and modeling for analysis of categorical data (α=5%) were performed. The results from both analyses showed that the recovery of sensitivity was correlated with patient age (p=0.015) and interval between surgery and onset of laser therapy (p=0.002). Within the limits of this retrospective study, it was found that low- power laser therapy with beam emission band in the infrared spectrum (808 nm) can positively affect the recovery of sensitivity after orthognathic or minor oral surgeries.

  8. He-Ne laser effects on blood microcirculation. An in vivo study through laser doppler flowmetry; Efeito do laser de helio neonio sobre a microcirculacao sanguinea durante a reparacao tecidual. Estudo in vivo por meio de fluxometria laser doppler

    Energy Technology Data Exchange (ETDEWEB)

    Nunez, Silvia Cristina

    2002-07-01

    Blood microcirculation performs an important function in tissue repair process, as well as in pain control, allowing for greater oxygenation of the tissues and the accelerated expulsion of metabolic products, that may be contributing to pain. Low Intensity Laser Therapy (LILT) is widely used to promote healing, and there is an assumption that it is mechanism of action may be due to an enhancement of blood supply. The purpose of this study was to evaluate, using laser Doppler flowmetry (LDF), the stated effects caused by radiation emitted by a He-Ne laser ({lambda}=632.8 nm) on blood microcirculation during tissue repair. To this end, 15 male mice were selected and received a liquid nitrogen provoked lesion, above the dorsal region, and blood flow was measured periodically, during 21 days. Due to radiation emission by the LDF equipment, a control group was established to evaluate possible effects caused by this radiation on microcirculation. To evaluate the He-Ne laser effects, a 1.15 J/cm{sup 2} dose was utilized, with an intensity of 6 mW/cm{sup 2}. The results obtained demonstrate flow alterations, provoked by the lesion, and subsequent inflammatory response. There was no statistical difference between the studied groups. As per the analysis of the results there is no immediate effect due the radiation emitted by a He Ne laser on microcirculation, although a percentage increase was observed in day 7 on medium blood flow rate in irradiated specimens. New studies are necessary to validate the use of this wavelength, in order to promote beneficial alterations in blood supply in radiated areas. (author)

  9. Experimental studies of a zeeman-tuned xenon laser differential absorption apparatus.

    Science.gov (United States)

    Linford, G J

    1973-06-01

    A Zeeman-tuned cw xenon laser differential absorption device is described. The xenon laser was tuned by axial magnetic fields up to 5500 G generated by an unusually large water-cooled dc solenoid. Xenon laser lines at 3.37 micro, 3.51 micro, and 3.99 micro were tuned over ranges of 6 A, 6 A, and 11 A, respectively. To date, this apparatus has been used principally to study the details of formaldehyde absorption lines lying near the 3 .508-micro xenon laser transition. These experiments revealed that the observed absorption spectrum of formaldehyde exhibits a sufficiently unique spectral structure that the present technique may readily be used to measure relative concentrations of formaldehyde in samples of polluted air.

  10. In Vitro UV-Visible Spectroscopy Study of Yellow Laser Irradiation on Human Blood

    Science.gov (United States)

    Fuad, Siti Sakinah Mohd; Suardi, N.; Mustafa, I. S.

    2018-04-01

    This experimental study was performed to investigate the effect of low level yellow laser of 589nm wavelength with various laser irradiation time. Human blood samples with random diseases are irradiated with yellow laser of power density of 450mW/cm2 from 10 minutes to 60 minutes at 10 minutes intervals. The morphology of the red blood cell were also observed for different irradiation time. The result shows that there is a significant different in the absorption of light with varying laser irradiation time (p<0.01). The maximum absorption recorded at 40 minutes of irradiation at 340nm peak. Blood smear of the samples reveals that there are observable changes in the morphology of the red blood cell at 40 minutes and 60 minutes of irradiation.

  11. An Experimental Study on Energy Conversion Process of an in-Space CW Laser Thruster

    International Nuclear Information System (INIS)

    Uehara, Susumu; Inoue, Takayoshi; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2005-01-01

    CW laser propulsion has been investigated to develop a prospective propulsion system that may be used in space. OTV (Orbit Transfer Vehicle) is placed as one of the most effective applications of the propulsion system. In this study, the energy partitioning of incident laser energy was investigated over the wide range of velocity of the flow field in low pressure. Flow velocity is thought to have significant effects on energy conversion process because the distribution of temperature and the position of a laser sustained plasma in the focusing laser beam should be determined so that flow velocity and propagation velocity of optical discharge balance out. It was found that the higher energy conversion efficiency can be achieved by lowering the pressure and increasing the velocity of the flow field

  12. Study of the laser-induced damage of reflective components in the sub-picosecond regime

    International Nuclear Information System (INIS)

    Sozet, Martin

    2016-01-01

    In this thesis, laser-induced damage phenomenon of reflective components is investigated in the sub-picosecond regime. These components, made of stacks of dielectric materials, are widely used in powerful laser facilities such as PETAL laser. PETAL laser has been built at the CEA-CESTA in France to deliver multi-kJ/500 fs pulses at 1053 nm and reach a power higher than 6 PW. For this kind of laser systems, reflective components are commonly used instead of optics operating in transmission to limit the accumulation of non-linear phase along the beam propagation due to the high intensities. Optical components irradiated by the highest power densities are the pulse compression gratings, transport mirrors and the focusing parabola, located at the end of the laser chain. Nowadays, laser-induced damage is the main factor that limits the overall performances of powerful laser systems. This manuscript presents three study axes to better understand and control damage phenomenon. The first one concerns the conception of reflective optics for the peta-watt applications. The design of new structures has been investigated to reach high diffraction efficiencies in the case of pulse compression gratings and a high reflectivity in the case of mirrors, while reducing the Electric-field enhancement which is one of the causes of the laser-induced damage. The second axis deals with the development of a precise damage metrology with new testing tools which brings new perspectives and a new viewpoint for the assessment of the laser resistance of optical components. Finally, the third axis concerns the study the damage growth after several irradiations in the sub-picosecond regime. The evolution of the damage area during growth sequences is observed and compared to numerical simulations. It enables to improve the understanding in the growth phenomenon. In the end, these studies will allow to develop predictive models of the laser-induced damage and new tools for the conception of

  13. Treatment of advanced, recurrent, resistant to previous treatments basal and squamous cell skin carcinomas with a synergistic formulation of interferons. Open, prospective study

    Directory of Open Access Journals (Sweden)

    Lopez-Saura Pedro

    2009-07-01

    Full Text Available Abstract Background Aggressive non-melanoma skin cancer (deeply infiltrating, recurrent, and morphea form lesions are therapeutically challenging because they require considerable tissue loss and may demand radical disfiguring surgery. Interferons (IFN may provide a non-surgical approach to the management of these tumors. The aim of this work was to evaluate the effect of a formulation containing IFNs-α and -γ in synergistic proportions on patients with recurrent, advanced basal cell (BCC or squamous cell skin carcinomas (SCSC. Methods Patients with extensive, recurrent, resistant to other procedures BCC or SCSC received the IFN formulation peri- and intralesionally, three times per week for 3 weeks. They had been previously treated with surgery and/or radiotherapy or chemotherapy. Thirteen weeks after the end of treatment, the original lesion sites were examined for histological evidence of remaining tumor. Results Sixteen elder (median 70 years-old patients were included. They beared 12 BCC and 4 SCSC ranging from 1.5 to 12.5 cm in the longest dimension. At the end of treatment 47% CR (complete tumor elimination, 40% PR (>30% tumor reduction, and 13% stable disease were obtained. None of the patients relapsed during the treatment period. The median duration of the response was 38 months. Only one patient with complete response had relapsed until today. Principal adverse reactions were influenza-like symptoms well known to occur with interferon therapy, which were well tolerated. Conclusion The peri- and intralesional combination of IFNs-α and -γ was safe and showed effect for the treatment of advanced, recurrent and resistant to previous treatments of BCC and SCSC in elder patients. This is the first report of such treatment in patients with advance non-melanoma skin cancer. The encouraging result justifies further confirmatory trials. Trial registration Current Controlled Trials RPCEC00000052.

  14. Treatment of advanced, recurrent, resistant to previous treatments basal and squamous cell skin carcinomas with a synergistic formulation of interferons. Open, prospective study

    International Nuclear Information System (INIS)

    Anasagasti-Angulo, Lorenzo; Garcia-Vega, Yanelda; Barcelona-Perez, Silvia; Lopez-Saura, Pedro; Bello-Rivero, Iraldo

    2009-01-01

    Aggressive non-melanoma skin cancer (deeply infiltrating, recurrent, and morphea form lesions) are therapeutically challenging because they require considerable tissue loss and may demand radical disfiguring surgery. Interferons (IFN) may provide a non-surgical approach to the management of these tumors. The aim of this work was to evaluate the effect of a formulation containing IFNs-α and -γ in synergistic proportions on patients with recurrent, advanced basal cell (BCC) or squamous cell skin carcinomas (SCSC). Patients with extensive, recurrent, resistant to other procedures BCC or SCSC received the IFN formulation peri- and intralesionally, three times per week for 3 weeks. They had been previously treated with surgery and/or radiotherapy or chemotherapy. Thirteen weeks after the end of treatment, the original lesion sites were examined for histological evidence of remaining tumor. Sixteen elder (median 70 years-old) patients were included. They beared 12 BCC and 4 SCSC ranging from 1.5 to 12.5 cm in the longest dimension. At the end of treatment 47% CR (complete tumor elimination), 40% PR (>30% tumor reduction), and 13% stable disease were obtained. None of the patients relapsed during the treatment period. The median duration of the response was 38 months. Only one patient with complete response had relapsed until today. Principal adverse reactions were influenza-like symptoms well known to occur with interferon therapy, which were well tolerated. The peri- and intralesional combination of IFNs-α and -γ was safe and showed effect for the treatment of advanced, recurrent and resistant to previous treatments of BCC and SCSC in elder patients. This is the first report of such treatment in patients with advance non-melanoma skin cancer. The encouraging result justifies further confirmatory trials. Current Controlled Trials RPCEC00000052

  15. An experimental study of noise in mid-infrared quantum cascade lasers of different designs

    Science.gov (United States)

    Schilt, Stéphane; Tombez, Lionel; Tardy, Camille; Bismuto, Alfredo; Blaser, Stéphane; Maulini, Richard; Terazzi, Romain; Rochat, Michel; Südmeyer, Thomas

    2015-04-01

    We present an experimental study of noise in mid-infrared quantum cascade lasers (QCLs) of different designs. By quantifying the high degree of correlation occurring between fluctuations of the optical frequency and voltage between the QCL terminals, we show that electrical noise is a powerful and simple mean to study noise in QCLs. Based on this outcome, we investigated the electrical noise in a large set of 22 QCLs emitting in the range of 7.6-8 μm and consisting of both ridge-waveguide and buried-heterostructure (BH) lasers with different geometrical designs and operation parameters. From a statistical data processing based on an analysis of variance, we assessed that ridge-waveguide lasers have a lower noise than BH lasers. Our physical interpretation is that additional current leakages or spare injection channels occur at the interface between the active region and the lateral insulator in the BH geometry, which induces some extra noise. In addition, Schottky-type contacts occurring at the interface between the n-doped regions and the lateral insulator, i.e., iron-doped InP, are also believed to be a potential source of additional noise in some BH lasers, as observed from the slight reduction in the integrated voltage noise observed at the laser threshold in several BH-QCLs.

  16. Er:YAG Laser and Fractured Incisor Restorations: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    C. Fornaini

    2012-01-01

    Full Text Available Introduction. The aim of this study was to analyse the effects of an Er:YAG laser on enamel and dentine in cases of dental restorations involving fractured teeth, utilizing the dental fragment. Materials and Methods. Seventy-two freshly extracted bovine incisors were fractured at the coronal level by using a hammer applied with a standardized method, and the fragment was reattached by using three different methods: Er:YAG laser, orthophosphoric acid, and laser plus acid. The different groups were evaluated by a test realized with the dynamometer to know the force required to successfully detach the reattached fragment and by a microinfiltration test by using a 0.5% methylene blue solution followed by the optic microscope observation. Results. The compression test showed only a slight difference between the three groups, without any statistical significance. The infiltration test used to evaluate the marginal seal between the fracture fragment and the tooth demonstrated that etching with Er:YAG laser alone or in combination with orthophosphoric acid gives better results than orthophosphoric acid alone, with a highly significant statistical result. Discussion. Reattaching a tooth fragment represents a clinically proven methodology, in terms of achieving resistance to detachment, and the aim of this work was to demonstrate the advantages of Er:YAG laser on this procedure. Conclusion. This “in vitro” study confirms that Er:YAG laser can be employed in dental traumatology to restore frontal teeth after coronal fracture.

  17. Study of optical confinement of quantum cascade lasers and applications to detection

    International Nuclear Information System (INIS)

    Moreau, Virginie

    2008-01-01

    Quantum cascade lasers have been invented in 1994 and they have already established themselves as the semiconductor laser source of choice in the mid- and far-infrared ranges of the electromagnetic spectrum. As most molecules of chemical interest exhibit roto-vibrational transitions in these spectral ranges, quantum cascade lasers are especially suited for applications such as spectroscopy, trace gas detection or medical imaging. One of the current leading research axis targets the device optimization and miniaturization, with possible applications in detection microsystems. This PhD thesis work focused on the study and optimization of the vertical optical confinement in quantum cascade lasers featuring optical waveguides without top cladding layers. These structures are interesting because they are compatible with two different guiding mechanisms at the same time, i.e. surface-plasmons and air confinement. The study of the characteristics of the optical mode and of the electrical current dispersion allowed us to conceive original structures which open new perspectives, for instance in the domain of analytic detection in a fluidic environment. Furthermore, we have shown that the observation by near field microscopy is a powerful tool to characterize and understand quantum cascade lasers. Finally, we have laid the foundations for the optimization of miniaturized arrays of single-mode lasers based on photonic crystal technology. (author) [fr

  18. An experimental study of percutaneous laser nucleotomy of the intervertebral cervical disc

    International Nuclear Information System (INIS)

    Wang Yiqing; Wang Zhimin; Guo Weiping; Zhang Hongxin; Guan Yan; Li Wenxian; Ni Daihui

    2002-01-01

    Objective: To study the effectiveness and safety of laser nucleotomy of the intervertebral cervical disc. Methods: The experimental study was performed in 10 dogs, and each dog was treated with laser nucleolysis in C3-4 and C4-5. The laser energy was turned on in 1.0-second pulses with 1.0 second (C3-4) and 5.0 second (C4-5) pause interval, and the total energy was up to 1000 joules. The temperatures were measured at the place between the posterior longitudinal ligament and the dura and at the vertebral foramen by using a tip type thermometer. Chronic histologic changes were observed by light microscopy at 2-4 weeks after laser irradiation. Results: The temperatures at the place between the posterior longitudinal ligament and the dura and at the vertebral Forman did not exceed 40 degree C when the pause interval was 5 second. Two dogs were euthanized immediately after treatment, and the oval-shaped cavity was observed on the macroscopic view in the nucleus. The cavity measured between 5 mm and 6 mm in long axis and between 2 mm and 4 mm in short. 4 weeks after the laser irradiation, the nucleus pulposus was replaced by cartilaginous cells and fibrous tissues. Conclusion: The laser nucleotomy of the intervertebral cervical disc is effective and feasible at the suitable condition

  19. Study and development of a soft X-ray laser seeded by high-order harmonic

    International Nuclear Information System (INIS)

    Goddet, J.Ph.

    2009-05-01

    The work in this thesis aimed to study a geometry of X-UV lasers inspired by high power laser. This architecture, consisting of an injector (a source of high-order harmonics) coupled to an amplifier (plasma created by laser), corresponds to that of a laser chain in the spectral range of the X-UV. The laser at 32.8 nm studied here, is produced by the injection of high-order harmonic in a krypton plasma created by Optical Field Ionization (OFI). This scheme, initially tested by T. Ditmire in 1995, was validated in 2003 with a plasma amplifier created by the interaction of intense laser and a gaseous medium. This thesis is a continuation of that work in trying to address different aspects, not only a better understanding of the physical processes involved, but also of the spatio-temporal characterization of this type of source. We have demonstrated experimentally for the first time a source in the X-UV, which can be highly compact, energetic (1 μJ per pulse), close to the diffraction limit and Fourier transform limited. Indeed, through the spatial filtering of harmonics by the amplifying medium, the injected X-UV laser at 32.8 nm shows a Gaussian spatial profile with a divergence of 0.7 mrad (at 1/e 2 ). The wavefront was measured with a Hartmann sensor and presents a value of λ/17 in standard deviation, demonstrating that the X-UV source is diffraction limited. The temporal characterization of laser shows that the coherence time is of the order of the duration of spontaneous emission of the amplifier. The temporal coherence presents a Gaussian profile with a relative spectral width Δλ/λ equal to 10 -5 (FWHM) corresponding to a pulse duration of about 5 ps. (author)

  20. The advantages of carbon dioxide laser applications in paediatric oral surgery. A prospective cohort study.

    Science.gov (United States)

    Hanna, R; Parker, S

    2016-11-01

    The aim of this study is to evaluate and demonstrate the advantages of the carbon dioxide laser in paediatric oral surgery patients in terms of less post-operative complications, healing without scaring, functional benefits, positive patient perception and acceptance of the treatment. One hundred fit and healthy paediatric patients (aged 4-15 years) were recruited to undergo laser surgery for different soft tissue conditions. The outcome of these laser treatments was examined. The Wong-Baker Faces Pain Rating Scale was employed to evaluate the pain before, immediately after laser treatment in the clinic and 1 day after post-operatively at home. Post-operative complications and patients' perception and satisfaction were self-reported during a review telephone call the day after treatment. The patients were reviewed 2 weeks after surgery. Laser parameter was 1.62 W, measured by power meter, continuous wave mode with 50 % emission cycle. The beam spot size at the target tissue was 0.8 mm. The pain score pre-operative, during and immediately after laser treatment was rated 0. Whilst the pain score 1 day after surgery was rated between 0 and 2, the healing time was measured over 2 weeks. None of the patients reported post-operative complications after surgery. Patients' perception and acceptance were rated very good. Laser dentistry is a promising field in modern minimally invasive dentistry, which enables provision of better care for children and adolescents. In this cohort study, the use of the carbon dioxide laser therapy offers a desirable, acceptable and minimally invasive technique in the surgical management of soft tissues in paediatric oral surgery with minimal post-operative complications.

  1. Review of studies for thermonuclear ignition with 1.8 MJ laser (LMJ): theory and experiment

    International Nuclear Information System (INIS)

    Holstein, P.A.; Bastian, J.; Bowen, C.; Casanova, M.; Chaland, F.; Cherfils, C.; Dattolo, E.; Galmiche, D.; Gauthier, P.; Giorla, J.; Laffite, S.; Liberatore, S.; Loiseau, P.; Larroche, O.; Lours, L.; Malinie, G.; Masse, L.; Monteil, M.C.; Morice, O.; Paillard, D.; Poggi, F.; Saillard, Y.; Seytor, P.; Teychenne, D.; Vandenboomgaerde, M.; Wagon, F.; Bonnefille, M.; Hedde, T.; Lefebvre, E.; Riazuelo, G.; Babonneau, D.; Primout, M.; Casner, A.; Depierreux, S.; Girard, F.; Huser, G.; Jadaud, J.P.; Juraszek, D.; Miquel, J.L.; Naudy, M.; Philippe, F.; Rousseaux, C.; Videau, L.

    2008-01-01

    The purpose of the laser Megajoule (LMJ) is the ignition of thermonuclear fusion reactions in a microscopic capsule of cryogenic DT whose implosion is obtained by a laser pulse in the range of 10 -20 ns, delivering a power of 400 - 500 TW. In this report we have tried to gather in one document the main part of the work made from 1995 to 2005 by the teams of Cea/DAM to design the LMJ targets. This report deals with the targets adapted to the laser energy of 1.8 MJ corresponding to 60 laser beams (called quadruplets because of their 4 beamlets), so primarily, with the target called A1040. The targets studied more recently adapted to lower laser energy are too new to appear in it. It concerns all the topics of the physics of target LMJ: laser-plasma interaction, radiative budget of the hohlraum, implosion interaction, hydrodynamic instabilities and robustness of the target to the technological uncertainties. The approach made for the robustness study is original and makes it possible to specify the features of the laser and the targets. This review scans all the aspects of the target design done with numerical simulations of bi-dimensional radiative hydrodynamics but it points out also the main results of the experiments made with the lasers Phebus, Nova and Omega for 20 years. This review also addresses to scientist not specialists in the problems of inertial confinement fusion. It is organized by topics of physics and the experiments appear at the end of each chapter. It does not concern the aspects of target fabrication nor the problems of diagnostic. (authors)

  2. A feasibility study for a remote laser water turbidity meter

    Science.gov (United States)

    Hickman, G. D.; Ghovanlou, A. H.; Friedman, E. J.; Gault, C. S.; Hogg, J. E.

    1974-01-01

    A technique to remotely determine the attenuation coefficient (alpha) of the water was investigated. The backscatter energy (theta = 180 deg) of a pulse laser (lambda = 440 - 660 nm) was found directly related to the water turbidity. The greatest sensitivity was found to exist at 440 nm. For waters whose turbidity was adjusted using Chesapeake Bay sediment, the sensitivity in determining alpha at 440 nm was found to be approximately 5 - 10%. A correlation was also found to exist between the water depth (time) at which the peak backscatter occurs and alpha.

  3. Study of a Laser-Produced Plasma by Langmuir Probes

    DEFF Research Database (Denmark)

    Chang, C. T.; Hasimi, M.; Pant, H. C.

    1977-01-01

    -emission peak and the main plasma from the target. The flow velocity, density and electron temperature of the plasma were determined. The expansion of the plasma was found to be adiabatic, yielding gamma =5/3. The spatial distribution of the plasma was observed to be strongly anisotropic.......The structure, the parameters and the expansion of the plasma produced by focusing a 7 J, 20 ns Nd-glass laser on stainless-steel and glass targets suspended in a high-vacuum chamber were investigated by Langmuir probes. It was observed that the probe signals consisted of a photoelectric...

  4. Study on load temperature control system of ground laser communication

    Science.gov (United States)

    Zhai, Xunhua; Zhang, Hongtao; Liu, Wangsheng; Zhang, Chijun; Zhou, Xun

    2007-12-01

    The ground laser communication terminal as the termination of a communication system, works at the temperature which varies from -40°C to 50°C. We design a temperature control system to keep optical and electronic components working properly in the load. The load is divided into two sections to control temperature respectively. Because the space is limited, we use heater film and thermoelectric cooler to clearify and refrigerate the load. We design a hardware and a software for the temperature control system, establish mathematic model, and emulate it with Matlab.

  5. Comparative Study Showing The Application Of Three Dimensional Oct And Ffa Correlation After Combined Bevacizumab/Laser And Triamcinolone/Laser In The Management Of Diabetic Macular Edema

    International Nuclear Information System (INIS)

    Helal, N.; Afahmoud, A.F.; Eliwa, T.F.; Omar, O.A.A.

    2012-01-01

    Purpose: to compare combined therapy by intravitreal triamicinolone acetonide and laser versus intravitreal bevacizumab and laser by three dimensional OCT in the management of diabetic macular edema regarding, the efficacy, duration of action, side effects, and complications of both regimens. Patients and methods: 40 eyes of 32 patients with type II diabetes mellitus, with clinically significant macular edema were enrolled into the study. They were divided equally into two groups, the first group was treated with intravitreal triamicinolone acetonide (4 mg/0.1 ml) followed 6 weeks later by focal Laser and the other group was treated by intravitreal bevacizumab (1.25 mg) followed 4 weeks later by focal Laser. Complete ophthalmological examination including BCVA, OCT and FFA were done preoperative and postoperative at 1, 3, 6, and 9 months. Results: the IVTA/Laser group showed an earlier improvement of BCVA by one line at the 3 month visit (p value 0.025 <0.05), compared to the IVA/Laser group that showed this change to be statistically significant at the 6 month visit (p value 0.048) with a one line improvement in BCVA. Regarding CMT and decrease of CMT than IVA/Laser although in both groups the improvement was transient, and relapses in both parameters occurred. There was a high incidence of cataract and steroid induced glaucoma in susceptible subjects in the IVTA/laser group than the IVA/Laser group. IVA/Laser may have a detrimental effect on FAZ integrity, and progression of the stage of diabetic retinopathy. Regarding mean change in CMT the IVTA/Laser has a stronger effect in reducing CMT, which is statistically significant at three months (p value <0.05). On the other hand IVA/Laser group, statistically significant change in mean CMT was at 1 month. Mean change in CMT between the 2 groups was not statistically significant throughout the study, although IVTA/Laser had a more powerful effect on the metric reduction of CMT, this difference was transient in both

  6. Quantitative laser diagnostic and modeling study of C2 and CH chemistry in combustion.

    Science.gov (United States)

    Köhler, Markus; Brockhinke, Andreas; Braun-Unkhoff, Marina; Kohse-Höinghaus, Katharina

    2010-04-15

    Quantitative concentration measurements of CH and C(2) have been performed in laminar, premixed, flat flames of propene and cyclopentene with varying stoichiometry. A combination of cavity ring-down (CRD) spectroscopy and laser-induced fluorescence (LIF) was used to enable sensitive detection of these species with high spatial resolution. Previously, CH and C(2) chemistry had been studied, predominantly in methane flames, to understand potential correlations of their formation and consumption. For flames of larger hydrocarbon fuels, however, quantitative information on these small intermediates is scarce, especially under fuel-rich conditions. Also, the combustion chemistry of C(2) in particular has not been studied in detail, and although it has often been observed, its role in potential build-up reactions of higher hydrocarbon species is not well understood. The quantitative measurements performed here are the first to detect both species with good spatial resolution and high sensitivity in the same experiment in flames of C(3) and C(5) fuels. The experimental profiles were compared with results of combustion modeling to reveal details of the formation and consumption of these important combustion molecules, and the investigation was devoted to assist the further understanding of the role of C(2) and of its potential chemical interdependences with CH and other small radicals.

  7. In vitro study of morphological and chemical modification threshold of bovine dental enamel irradiated by the holmium laser; Estudo in vitro das alteracoes morfologicas e quimicas do esmalte dental bovino irradiado pelo laser de holmio

    Energy Technology Data Exchange (ETDEWEB)

    Eduardo, Patricia Lerro de Paula

    2001-07-01

    The aim of this study is to investigate the Ho:YLF laser effects on the dental enamel surface with regards to its morphology, thermal variations during its irradiation in the pulp chamber and its increased resistance to demineralization through quantitative analysis of calcium and phosphorous atoms reactive concentrations in samples. Twenty samples of bovine enamel were used and divided in four groups: control - acidulated phosphate fluoride (APF) application followed by demineralization treatment with lactic acid; irradiation with Ho:YLF laser (100 J/cm{sup 2}) followed by APF topic application and demineralization treatment with lactic acid; irradiation with Ho:YLF laser (350 J/cm{sup 2}) followed by APF topic application and demineralization treatment with lactic acid: and irradiation with Ho:YLF laser ( 450 J/cm{sup 2}) followed by APF topic application and demineralization treatment with lactic acid. Ali samples were quantified according to their calcium and phosphorous atoms relative concentrations before and after the treatments above. X-Ray fluorescence spectrochemical analysis and scanning electron microscopy were carried out. It was observed an increase on the calcium and phosphorous atoms concentration ratio and therefore the enamel demineralization reduction as a result of the lactic acid treatment in the samples irradiated with the holmium laser followed by the APF application. In order to evaluate the feasibility of this study for clinical purposes, morphological changes caused by the holmium laser irradiation were analyzed. Such modifications were characterized by melted and re-solidified regions of the enamel with consequent changes on its permeability and solubility. Temperature changes of ten human pre-molars teeth irradiated with 350 J/cm{sup 2} and 450 J/cm{sup 2} were also monitored in the pulp chamber in real time. Temperature increases over 4,20 C did not occur. The results obtained from this study along with the results from previous

  8. Vestibuloplasty: a retrospective study on conventional and laser operation techniques

    Science.gov (United States)

    Neckel, Claus P.

    1999-05-01

    40 patients with edentulous maxillary jaws were referred to our private practice limited to maxillofacial surgery, due to atrophy of the alveolar ridge. Before prosthetic renewal of the upper removable prosthesis the restorative dentist requested a sufficient vestibule. After supraperiostal preparation, soft tissue advancement and fixation with absorbable sutures. The recipient site was covered with a free gingival graft. Group I was operated on traditionally using a scalpel. In group II incision and soft tissue preparation was performed using a diode laser. Wavelength: 810 nm; Continuous wave mode; 400 micron optic fiber; Output power 1.6 Watt. All operations were performed by one surgeon experienced in both operation techniques. Every patient was followed-up 1, 4, 8 weeks, 6 and 12 months. The vestibular height directly adjacent to the nasal cavity and 2cm distal to these first measuring locations were taken. Each patient was asked to evaluate their individual discomfort and postoperative pain level. Both groups showed no significant difference in vestibular height after 1, 4, 8 weeks, 6 months and 1 year. The postoperative height of 1.28 cm was reduced to 0.84 cm after 1 year. Furthermore both groups showed uneventful healing and take of the free gingival grafts. The assessment of the pain and discomfort level by the patients brought a significant difference between both groups in favor of the laser assisted operation technique.

  9. Cartilage ablation studies using mid-IR free electron laser

    Science.gov (United States)

    Youn, Jong-In; Peavy, George M.; Venugopalan, Vasan

    2005-04-01

    The ablation rate of articular cartilage and fibrocartilage (meniscus), were quantified to examine wavelength and tissue-composition dependence of ablation efficiency for selected mid-infrared wavelengths. The wavelengths tested were 2.9 um (water dominant absorption), 6.1 (protein and water absorption) and 6.45 um (protein dominant absorption) generated by the Free Electron Laser (FEL) at Vanderbilt University. The measurement of tissue mass removal using a microbalance during laser ablation was conducted to determine the ablation rates of cartilage. The technique can be accurate over methods such as profilometer and histology sectioning where tissue surface and the crater morphology may be affected by tissue processing. The ablation efficiency was found to be dependent upon the wavelength. Both articular cartilage and meniscus (fibrocartilage) ablations at 6.1 um were more efficient than those at the other wavelengths evaluated. We observed the lowest ablation efficiency of both types of cartilage with the 6.45 um wavelength, possibly due to the reduction in water absorption at this wavelength in comparison to the other wavelengths that were evaluated.

  10. Health effects of laser printer emissions: a controlled exposure study.

    Science.gov (United States)

    Karrasch, S; Simon, M; Herbig, B; Langner, J; Seeger, S; Kronseder, A; Peters, S; Dietrich-Gümperlein, G; Schierl, R; Nowak, D; Jörres, R A

    2017-07-01

    Ultrafine particles emitted from laser printers are suspected to elicit adverse health effects. We performed 75-minute exposures to emissions of laser printing devices (LPDs) in a standardized, randomized, cross-over manner in 23 healthy subjects, 14 mild, stable asthmatics, and 15 persons reporting symptoms associated with LPD emissions. Low-level exposures (LLE) ranged at the particle background (3000 cm -3 ) and high-level exposures (HLE) at 100 000 cm -3 . Examinations before and after exposures included spirometry, body plethysmography, transfer factors for CO and NO (TLCO, TLNO), bronchial and alveolar NO, cytokines in serum and nasal secretions (IL-1β, IL-5, IL-6, IL-8, GM-CSF, IFNγ, TNFα), serum ECP, and IgE. Across all participants, no statistically significant changes occurred for lung mechanics and NO. There was a decrease in volume-related TLNO that was more pronounced in HLE, but the difference to LLE was not significant. ECP and IgE increased in the same way after exposures. Nasal IL-6 showed a higher increase after LLE. There was no coherent pattern regarding the responses in the participant subgroups or single sets of variables. In conclusion, the experimental acute responses to short but very high-level LPD exposures were small and did not indicate clinically relevant effects compared to low particle number concentrations. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Beam Dynamics Studies for a Laser Acceleration Experiment

    CERN Document Server

    Spencer, James; Noble, Robert; Palmer, Dennis T; Siemann, Robert

    2005-01-01

    The NLC Test Accelerator at SLAC was built to address various beam dynamics issues for the Next Linear Collider. An S-Band RF gun, originally proposed for the NLCTA, is being installed together with a large-angle extraction line at 60 MeV. This is followed by a matching section, final focus and buncher for the laser acceleration experiment, E163. The laser-electron interaction area is followed by a broad range, high resolution spectrometer (HES) for electron bunch analysis. The RF gun is discussed in another paper. We discuss only the beam dynamics and high resolution analysis system at 6 MeV based on using Parmela and high-order Transport for bunch charges from 50 pC to 1 nC. Beyond the diagnostics, this system uses the emittance compensating solenoids and a low energy, high resolution spectrometer (LES) to help tune for best operating point and match to the linac. Optical symmetries in the design of the 25.5° extraction line provide 1:1 phase space transfer without linear dispersion or use of sextu...

  12. Study of noninvasive detection of latent fingerprints using UV laser

    Science.gov (United States)

    Li, Hong-xia; Cao, Jing; Niu, Jie-qing; Huang, Yun-gang; Mao, Lin-jie; Chen, Jing-rong

    2011-06-01

    Latent fingerprints present a considerable challenge in forensics, and noninvasive procedure that captures a digital image of the latent fingerprints is significant in the field of criminal investigation. The capability of photography technologies using 266nm UV Nd:YAG solid state laser as excitation light source to provide detailed images of unprocessed latent fingerprints is demonstrated. Unprocessed latent fingerprints were developed on various non-absorbent and absorbing substrates. According to the special absorption, reflection, scattering and fluorescence characterization of the various residues in fingerprints (fatty acid ester, protein, and carbosylic acid salts etc) to the UV light to weaken or eliminate the background disturbance and increase the brightness contrast of fingerprints with the background, and using 266nm UV laser as excitation light source, fresh and old latent fingerprints on the surface of four types of non-absorbent objects as magazine cover, glass, back of cellphone, wood desktop paintwork and two types of absorbing objects as manila envelope, notebook paper were noninvasive detected and appeared through reflection photography and fluorescence photography technologies, and the results meet the fingerprint identification requirements in forensic science.

  13. Study on high power ultraviolet laser oil detection system

    Science.gov (United States)

    Jin, Qi; Cui, Zihao; Bi, Zongjie; Zhang, Yanchao; Tian, Zhaoshuo; Fu, Shiyou

    2018-03-01

    Laser Induce Fluorescence (LIF) is a widely used new telemetry technology. It obtains information about oil spill and oil film thickness by analyzing the characteristics of stimulated fluorescence and has an important application in the field of rapid analysis of water composition. A set of LIF detection system for marine oil pollution is designed in this paper, which uses 355nm high-energy pulsed laser as the excitation light source. A high-sensitivity image intensifier is used in the detector. The upper machine sends a digital signal through a serial port to achieve nanoseconds range-gated width control for image intensifier. The target fluorescence spectrum image is displayed on the image intensifier by adjusting the delay time and the width of the pulse signal. The spectral image is coupled to CCD by lens imaging to achieve spectral display and data analysis function by computer. The system is used to detect the surface of the floating oil film in the distance of 25m to obtain the fluorescence spectra of different oil products respectively. The fluorescence spectra of oil products are obvious. The experimental results show that the system can realize high-precision long-range fluorescence detection and reflect the fluorescence characteristics of the target accurately, with broad application prospects in marine oil pollution identification and oil film thickness detection.

  14. Prognostic factors in multiple myeloma: definition of risk groups in 410 previously untreated patients: a Grupo Argentino de Tratamiento de la Leucemia Aguda study.

    Science.gov (United States)

    Corrado, C; Santarelli, M T; Pavlovsky, S; Pizzolato, M

    1989-12-01

    Four hundred ten previously untreated multiple myeloma patients entered onto two consecutive Grupo Argentino de Tratamiento de la Leucemia Aguda (GATLA) protocols were analyzed to identify significant prognostic factors influencing survival. The univariate analysis selected the following variables: performance status, renal function, percentage of bone marrow plasma cells at diagnosis, hemoglobin, and age. A multivariate analysis showed that performance status, renal function, percentage of bone marrow plasma cells, hemoglobin, and age were the best predictive variables for survival. A score was assigned to each patient according to these variables, which led to their classification in three groups: good, intermediate, and poor risk, with a probability of survival of 26% and 10% at 96 months, and 5% at 56 months, and median survival of 60, 37, and 14 months, respectively (P = .0000). In our patient population, this model proved to be superior to the Durie-Salmon staging system in defining prognostic risk groups, and separating patients with significantly different risks within each Durie-Salmon stage.

  15. Implementation of an electronic medical record system in previously computer-naïve primary care centres: a pilot study from Cyprus.

    Science.gov (United States)

    Samoutis, George; Soteriades, Elpidoforos S; Kounalakis, Dimitris K; Zachariadou, Theodora; Philalithis, Anastasios; Lionis, Christos

    2007-01-01

    The computer-based electronic medical record (EMR) is an essential new technology in health care, contributing to high-quality patient care and efficient patient management. The majority of southern European countries, however, have not yet implemented universal EMR systems and many efforts are still ongoing. We describe the development of an EMR system and its pilot implementation and evaluation in two previously computer-naïve public primary care centres in Cyprus. One urban and one rural primary care centre along with their personnel (physicians and nurses) were selected to participate. Both qualitative and quantitative evaluation tools were used during the implementation phase. Qualitative data analysis was based on the framework approach, whereas quantitative assessment was based on a nine-item questionnaire and EMR usage parameters. Two public primary care centres participated, and a total often health professionals served as EMR system evaluators. Physicians and nurses rated EMR relatively highly, while patients were the most enthusiastic supporters for the new information system. Major implementation impediments were the physicians' perceptions that EMR usage negatively affected their workflow, physicians' legal concerns, lack of incentives, system breakdowns, software design problems, transition difficulties and lack of familiarity with electronic equipment. The importance of combining qualitative and quantitative evaluation tools is highlighted. More efforts are needed for the universal adoption and routine use of EMR in the primary care system of Cyprus as several barriers to adoption exist; however, none is insurmountable. Computerised systems could improve efficiency and quality of care in Cyprus, benefiting the entire population.

  16. Experimental study of proton acceleration with ultra-high intensity, high contrast laser beam

    International Nuclear Information System (INIS)

    Flacco, A.

    2008-07-01

    This thesis reports experimental work in the domain of laser-matter interaction to study the production of energetic proton beams. The ion beams accelerated by laser have been increasing in quality, in energy and in repeatability as laser technology keeps improving. The presence of the pedestal before the high peak laser pulse introduces many unknowns in the accelerating conditions that are created on the front and on the rear surface of the target. The first part of the experimental activities is focused to a better comprehension and the experimental validation of the interaction of a 'pedestal-like', moderate intensity, laser pulse on Aluminum targets. The developed interferometric technique proved to be reliable and produced a complete set of maps of the early stages of the plasma expansion. The reflectometry experiment stresses the importance of the quality of the metallic targets and underlines some obscure points on the behaviour of the rear surface of the illuminated foil. For instance the reflectometry measurements on the thicker targets are significantly different from what is foreseen by the simulations about the timescale of the shock break out. In the second part, the XPW laser pulse is used in ion acceleration from thin metal foils. The laser and target parameters are varied to put in evidence the dependence of the ion beam to the experimental condition. In conclusion I can say that first, during the variation of the target thickness, an optimum is put in evidence. Secondly, the correlation between the laser pulse duration and the proton cutoff energy is qualitatively different between thicker (15 μm) and thinner (1.5 μm, 3 μm) targets. For the first, an optimal pulse duration exists while for the seconds, no variation is found - in the searched space - from the monotonic decreasing of the cutoff energy with the peak intensity. The experimental results put however in evidence some points that are not completely understood. (A.C.)

  17. Experimental erbium: YAG laser photoablation of trabecular meshwork in rabbits: an in-vivo study.

    Science.gov (United States)

    Dietlein, T S; Jacobi, P C; Schröder, R; Krieglstein, G K

    1997-05-01

    Photoablative laser trabecular surgery has been proposed as an outflow-enhancing treatment for open-angle glaucoma. The aim of the study was to investigate the time course of repair response following low-thermal Erbium: YAG laser trabecular ablation. In 20 anaesthetized rabbits gonioscopically controlled ab-interno photoablation of the ligamenta pectinata and underlying trabecular meshwork (TM) was performed with a single-pulsed (200 microseconds) Erbium: YAG (2.94 microns) laser. The right eye received 12-15 single laser pulses (2 mJ) delivered through an articulated zirconium fluoride fiberoptic and a 200 microns (core diameter) quartz fiber tip, the left unoperated eye served as control. At time intervals of 30 minutes, 2, 10, 30, and 60 days after laser treatment, eyes were processed for light- and scanning electron microscopy. The applied energy density of 6-4 J cm-2 resulted in visible dissection of the ligamenta pectinata and reproducible microperforations of the TM exposing scleral tissue accompanied by blood reflux from the aqueous plexus. The initial ablation zones measured 154 +/- 36 microns in depth and 45 +/- 6 microns in width. Collateral thermal damage zones were 22 +/- 8 microns. At two days post-operative, ablation craters were still blood- and fibrin-filled. The inner surface of the craters were covered with granulocytes. No cellular infiltration of the collateral thermal damage zone was observed. At 10 days post-operative, progressive fibroblastic proliferation was observed, resulting in dense scar tissue formation with anterior synechiae, proliferating capillaries and loss of intertrabecular spaces inside the range of former laser treatment at 60 days post-operative. Trabecular microperforations were closed 60 days after laser treatment in all rabbits. IOP in treated and contralateral eyes did not significantly change its level during whole period of observation. Low-thermal infrared laser energy with minimal thermal damage to collateral

  18. In Vitro Study of Dentin Hypersensitivity Treated by 980-nm Diode Laser.

    Science.gov (United States)

    Liu, Ying; Gao, Jie; Gao, Yan; Xu, Shuaimei; Zhan, Xueling; Wu, Buling

    2013-01-01

    To investigate the ultrastructural changes of dentin irradiated with 980-nm diode laser under different parameters and to observe the morphological alterations of odontoblasts and pulp tissue to determine the safety parameters of 980-nm diode laser in the treatment of dentin hypersensitivity (DH). Twenty extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into four areas and was irradiated by 980-nm diode laser under different parameters: Group A: control group, 0 J/cm(2); Group B: 2 W/CW (continuous mode), 166 J/cm(2); Group C: 3W/CW, 250 J/cm(2); and Group D: 4W/CW, 333 J/cm(2). Ten additional extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into two areas and was irradiated by 980-nm diode laser: Group E: control group, 0 J/cm(2); and Group F: 2.0 W/CW, 166 J/cm(2). The morphological alterations of the dentin surfaces and odontoblasts were examined with scanning electron microscopy (SEM), and the morphological alterations of the dental pulp tissue irradiated by laser were observed with an upright microscope. The study demonstrated that dentinal tubules can be entirely blocked after irradiation by 980-nm diode laser, regardless of the parameter setting. Diode laser with settings of 2.0 W and 980-nm sealed exposed dentin tubules effectively, and no significant morphological alterations of the pulp and odontoblasts were observed after irradiation. Irradiation with 980-nm diode laser could be effective for routine clinical treatment of DH, and 2.0W/CW (166 J/cm(2)) was a suitable energy parameter due to its rapid sealing of the exposed dentin tubules and its safety to the odontoblasts and pulp tissue.

  19. In Vitro Study of Dentin Hypersensitivity Treated by 980-nm Diode Laser

    Science.gov (United States)

    Liu, Ying; Gao, Jie; Gao, Yan; XU, Shuaimei; Zhan, Xueling; Wu, Buling

    2013-01-01

    Introduction: To investigate the ultrastructural changes of dentin irradiated with 980-nm diode laser under different parameters and to observe the morphological alterations of odontoblasts and pulp tissue to determine the safety parameters of 980-nm diode laser in the treatment of dentin hypersensitivity (DH). Methods: Twenty extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into four areas and was irradiated by 980-nm diode laser under different parameters: Group A: control group, 0 J/cm2; Group B: 2 W/CW (continuous mode), 166 J/cm2; Group C: 3W/CW, 250 J/cm2; and Group D: 4W/CW, 333 J/cm2. Ten additional extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into two areas and was irradiated by 980-nm diode laser: Group E: control group, 0 J/cm2; and Group F: 2.0 W/CW, 166 J/cm2. The morphological alterations of the dentin surfaces and odontoblasts were examined with scanning electron microscopy (SEM), and the morphological alterations of the dental pulp tissue irradiated by laser were observed with an upright microscope. Results: The study demonstrated that dentinal tubules can be entirely blocked after irradiation by 980-nm diode laser, regardless of the parameter setting. Diode laser with settings of 2.0 W and 980-nm sealed exposed dentin tubules effectively, and no significant morphological alterations of the pulp and odontoblasts were observed after irradiation. Conclusions: Irradiation with 980-nm diode laser could be effective for routine clinical treatment of DH, and 2.0W/CW (166 J/cm2) was a suitable energy parameter due to its rapid sealing of the exposed dentin tubules and its safety to the odontoblasts and pulp tissue. PMID:25606318

  20. Study of gelatin as an effective energy absorbing layer for laser bioprinting.

    Science.gov (United States)

    Xiong, Ruitong; Zhang, Zhengyi; Chai, Wenxuan; Chrisey, Douglas B; Huang, Yong

    2017-06-09

    Laser-induced forward transfer printing, also commonly known as laser printing, has been widely implemented for three-dimensional bioprinting due to its unique orifice-free nature during printing. However, the printing quality has the potential to be further improved for various laser bioprinting applications. The objectives of this study are to investigate the feasibility of using gelatin as an energy absorbing layer (EAL) material for laser bioprinting and its effects on the quality of printed constructs, bioink printability, and post-printing cell viability and process-induced DNA damage. The gelatin EAL is applied between the quartz support and the coating of build material, which is to be printed. Printing quality can be improved by EAL-assisted laser printing when using various alginate solutions (1%, 2%, and 4%) and cell-laden bioinks (2% alginate and 5 × 10 6 cells ml -1 in cell culture medium). The required laser fluence is also reduced due to a higher absorption coefficient of gelatin gel, in particular when to achieve the best printing type/quality. The post-printing cell viability is improved by ∼10% and DNA double-strand breaks are reduced by ∼50%. For all the build materials investigated, the gelatin EAL helps reduce the droplet size and average jet velocity.

  1. Microstructure and properties of laser clad coatings studied by orientation imaging microscopy

    International Nuclear Information System (INIS)

    Ocelik, V.; Furar, I.; De Hosson, J.Th.M.

    2010-01-01

    In this work orientation imaging microscopy (OIM), based on electron backscatter diffraction in scanning electron microscopy, was employed to examine in detail the relationship between laser cladding processing parameters and he properties and the microstructure of single and overlapping laser tracks. The study was performed on thick (∼1 mm) Co-based coatings prepared by 2 kW Nd:YAG laser cladding a 42CrMo4 steel substrate using different laser beam scanning speeds (1.0-15 mm s -1 ). It was found that the directional growth of individual primary grains led to the formation of a typical solidification fiber texture. The dependence of this texture on the processing speed and the shape of the solidification front were investigated in detail. Strong epitaxial growth of Co grains on austenitic steel substrate grains was found, which did not depend on the laser beam scanning velocity. During laser cladding a strong temperature gradient exists just below the coating-substrate interface that promotes the formation of a Greninger-Troiano orientation relationship between martensitic plates and the original austenitic grain inside the heat affected zone: {1 1 1} γ ∼ 1 o to {1 1 0} α and γ ∼ 2 o to α . Relatively drastic changes in grain size at the internal coating interfaces did not exhibit sharp changes in microhardness.

  2. Study on surface properties of gilt-bronze artifacts, after Nd:YAG laser cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyeyoun [Division of Restoration Technology, National Research Institute of Cultural Heritage, Daejeon (Korea, Republic of); Cho, Namchul, E-mail: nam1611@hanmail.net [Department of Cultural Heritage Conservation Science, Kongju National University, Gongju, 314-701 (Korea, Republic of); Lee, Jongmyoung [Laser Engineering Group, IMT Co. Ltd, Gyeonggi (Korea, Republic of)

    2013-11-01

    As numerous pores are formed at plating gilt-bronze artifacts, the metal underlying the gold is corroded and corrosion products are formed on layer of gold. Through this study, the surfaces of gilt-bronze are being investigated before and after the laser irradiation to remove corrosion products of copper by using Nd:YAG laser. For gilt-bronze specimens, laser and chemical cleaning were performed, and thereafter, surface analysis with SEM-EDS, AFM, and XPS were used to determine the surface characteristics. Experimental results show that chemical cleaning removes corrosion products of copper through dissolution but it was not removed uniformly and separated the metal substrate and the gold layer. Nevertheless, through laser cleaning, some of the corrosions were removed with some damaged areas due to certain conditions and brown residues remained. Brown residues were copper corrosion products mixed with soil left within the gilt layer. It was due to surface morphology of uneven and rough gilt layer. Hence, they did not react effectively to laser beams, and thus, remained as residues. The surface properties of gilt-bronze should be thoroughly investigated with various surface analyses to succeed in laser cleaning without damages or residues.

  3. Study of fast electron generation using multi beam of LFEX-class laser

    International Nuclear Information System (INIS)

    Hata, M; Nagatomo, H; Sakagami, H; Johzaki, T; Sentoku, Y

    2016-01-01

    Fast Ignition Realization Experiment project phase-I (FIREX-I) is being performed at Institute of Laser Engineering, Osaka University. In this project, the four-beam bundled high-energy Petawatt laser (LFEX) is being operated. LFEX laser provides great multi-beam irradiation flexibility, with the possibility of arrange the pulses in temporal sequence, spatially separate them in distinct spots of focus them in a single spot. In this paper, we study the two- beam interference effects on high-intensity picosecond laser-plasma interaction (LPI) by twodimensional relativistic Particle-In-Cell simulations. The interference causes surface perturbation, which enhances laser absorption and underdense plasma generation, increasing the accelerated electron number and their slope temperature. The laser-to-electron energy conversion efficiency for two-beam interference case is suitable for Fast Ignition (FI) compared to the single beam case, but the increment of fast electron divergence leads to lower energy coupling. To optimize the target design for FI, these interference effects should be taken into consideration. (paper)

  4. Shock wave generation in laser ablation studied using pulsed digital holographic interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Amer, Eynas; Gren, Per; Sjoedahl, Mikael [Division of Experimental Mechanics, Luleaa University of Technology, SE-971 87 Luleaa (Sweden)], E-mail: eynas.amer@ltu.se, E-mail: per.gren@ltu.se, E-mail: mikael.sjodahl@ltu.se

    2008-11-07

    Pulsed digital holographic interferometry has been used to study the shock wave induced by a Q-switched Nd-YAG laser ({lambda} = 1064 nm and pulse duration 12 ns) on a polycrystalline boron nitride (PCBN) ceramic target under atmospheric air pressure. A special setup based on using two synchronized wavelengths from the same laser for processing and measurement simultaneously has been introduced. Collimated laser light ({lambda} = 532 nm) passed through the volume along the target and digital holograms were recorded for different time delays after processing starts. Numerical data of the integrated refractive index field were calculated and presented as phase maps showing the propagation of the shock wave generated by the process. The location of the induced shock wave front was observed for different focusing and time delays. The amount of released energy, i.e. the part of the incident energy of the laser pulse that is eventually converted to a shock wave has been estimated using the point explosion model. The released energy is normalized by the incident laser pulse energy and the energy conversion efficiency between the laser pulse and PCBN target has been calculated at different power densities. The results show that the energy conversion efficiency seems to be constant around 80% at high power densities.

  5. Femtosecond laser machining for characterization of local mechanical properties of biomaterials: a case study on wood

    Science.gov (United States)

    Jakob, Severin; Pfeifenberger, Manuel J.; Hohenwarter, Anton; Pippan, Reinhard

    2017-12-01

    The standard preparation technique for micro-sized samples is focused ion beam milling, most frequently using Ga+ ions. The main drawbacks are the required processing time and the possibility and risks of ion implantation. In contrast, ultrashort pulsed laser ablation can process any type of material with ideally negligible damage to the surrounding volume and provides 4 to 6 orders of magnitude higher ablation rates than the ion beam technique. In this work, a femtosecond laser was used to prepare wood samples from spruce for mechanical testing at the micrometre level. After optimization of the different laser parameters, tensile and compressive specimens were produced from microtomed radial-tangential and longitudinal-tangential sections. Additionally, laser-processed samples were exposed to an electron beam prior to testing to study possible beam damage. The specimens originating from these different preparation conditions were mechanically tested. Advantages and limitations of the femtosecond laser preparation technique and the deformation and fracture behaviour of the samples are discussed. The results prove that femtosecond laser processing is a fast and precise preparation technique, which enables the fabrication of pristine biological samples with dimensions at the microscale.

  6. Effect of Argon Laser on Enamel Demineralization around Orthodontic Brackets: An In Vitro Study

    Science.gov (United States)

    Miresmaeili, Amirfarhang; Etrati Khosroshahi, Mohammad; Motahary, Pouya; Rezaei-Soufi, Loghman; Mahjub, Hossein; Dadashi, Maryam; Farhadian, Nasrin

    2014-01-01

    Objective This study was designed to evaluate the effect of argon laser irradiation on development and progress of enamel demineralization around orthodontic brackets. Materials and Methods: Fifty caries-free, intact human premolars were randomly assigned to one of the following five equal groups: Groups 1 (control) and 2: The brackets were bonded using conventional halogen light for 40s and argon laser for 10s, respectively. Teeth in group 3 were lased with argon laser for 10s before bracket bonding with halogen light. Group 4 was the same as group 3 except that brackets were also bonded with argon laser. In group 5 samples were bonded conventionally, immersed in an artificial caries solution for two days and then irradiated for 10s with argon laser. All samples were subjected to demineralization by artificial caries solution for 10 days. After bracket removal, samples were buccolingually sectioned and evaluated by polarized light microscopy. Decalcified lesion depth in each section was measured by a trained examiner in a blind fashion. Data were analyzed in SPSS 14 using one-way ANOVA and Tukey’s HSD post hoc test. Results: The control group showed the greatest mean lesion depth while group 5 revealed the lowest. The laser-treated groups had significantly lower mean lesion depth compared with the control group (Pbracket bonding can increase caries resistance of intact and demineralized enamel. PMID:25584052

  7. Study and development of a laser based alignment system for the compact linear collider

    CERN Document Server

    AUTHOR|(CDS)2083149

    The first objective of the PhD thesis is to develop a new type of positioning sensor to align components at micrometre level over 200 m with respect to a laser beam as straight line reference. The second objective is to estimate the measurement accuracy of the total alignment system over 200 m. The context of the PhD thesis is the Compact Linear Collider project, which is a study for a future particle accelerator. The proposed positioning sensor is made of a camera and an open/close shutter. The sensor can measure the position of the laser beam with respect to its own coordinate system. To do a measurement, the shutter closes, a laser spot appears on it, the camera captures a picture of the laser spot and the coordinates of the laser spot centre are reconstructed in the sensor coordinate system with image processing. Such a measurement requires reference targets on the positioning sensor. To reach the rst objective of the PhD thesis, we used laser theory...

  8. The marginal fit of selective laser melting-fabricated metal crowns: an in vitro study.

    Science.gov (United States)

    Xu, Dan; Xiang, Nan; Wei, Bin

    2014-12-01

    The selective laser melting technique is attracting interest in prosthetic dentistry. The marginal fit is a key criterion for fixed restorations. The purpose of the study was to evaluate the marginal fit of cast cobalt-chromium alloy crowns versus the fit of selective laser melting-fabricated crowns. The marginal gap widths of 36 single crowns (18 selective laser melting-fabricated cobalt-chromium metal crowns and 18 cobalt-chromium cast crowns) were determined with a silicone replica technique. Each crown specimen was cut into 4 sections, and the marginal gap width of each cross section was evaluated by stereomicroscopy (× 100). The Student t test was used to evaluate whether significant differences occurred in the marginal gap widths between the selective laser melting-fabricated and cast cobalt-chromium metal crowns (α=.05). The mean marginal gap width of the cast crowns (170.19 μm) was significantly wider than that of the selective laser melting-fabricated crowns (102.86 μm). Selective laser melting-fabricate cobalt-chromium dental crowns found improved marginal gap widths compared with traditional cast crowns. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  9. Studies on perovskite film ablation and scribing with ns-, ps- and fs-laser pulses

    Science.gov (United States)

    Bayer, Lukas; Ye, Xinyuan; Lorenz, Pierre; Zimmer, Klaus

    2017-10-01

    Hybrid organic-inorganic perovskites attract much attention due to their exceptional optoelectronic properties, in particular for photovoltaic (PV) applications. The accurate, high-speed and reliable patterning of the PV films is required for perovskite solar modules fabrication. Laser scribing provides these characteristics needed for industrial fabrication processes. In this work, the laser ablation and scribing of perovskite layers (CH3NH3PbI3: MAPbI3) with different laser sources (ns-, ps-, fs-laser pulses with wavelengths of 248 nm to 2.5 µm) were systematically investigated. The perovskite material was irradiated from both the film side and the substrate (rear side) side to study and compare the particular processes. The patterning results of the perovskite film can be classified into (1) regular laser ablation, (2) thin-film delamination lift-off process, and (3) lift-off with thermal modifications. A particular process, the localised lift-off of single grains from the perovskite film, has been observed and is discussed in relation to the thin-film lift-off process. Ablation and ablation-related mechanisms provide good conditions for laser scribing of the perovskite layer required for module interconnection via P2.

  10. In vitro study of temperature changes in root during Er:YAG laser application

    International Nuclear Information System (INIS)

    Brandao, Redson Vilela

    2001-01-01

    The temperature increase in root dentine irradiated by Er:YAG laser beam was analyzed, for different dentine thickness and different energy and frequency conditions, aiming the evaluation of Er:YAG laser in endodontic therapy, without causing any damages to close tissues. Twenty four human teeth were separated in four groups with six teeth each, and longitudinally sectioned in thickness of 0.5 mm (first group), 1,0 mm (second group), 1,5 mm (third group) and 2,0 mm (fourth group). Those samples were irradiated with the Er:YAG laser, emitting at the wavelength of 2.94μm, by using a sapphire optic fiber with diameter of 0.375 mm, and forming an angle of 5 deg with the irradiated dentine surface. Three different laser energies were used in this study, 180 mJ, 160 mJ and 140 mJ, with frequencies of 10 Hz and 15 Hz. The temperature data were collected in a digital-analog system and sent to a computer for analysis. It was verified that the time for temperature increases of 5 deg in the external root walls varies according to the laser energy, repetition rate and dentine root thickness. Thus, in this work we could obtain laser parameters to avoid thermal damages in periodontal tissues. (author)

  11. Laser reduction of specific microorganisms in the periodontal pocket using Er:YAG and Nd:YAG lasers: a randomized controlled clinical study.

    Science.gov (United States)

    Grzech-Leśniak, K; Sculean, A; Gašpirc, Boris

    2018-05-15

    The objective of this study was to evaluate the microbiological and clinical outcomes following nonsurgical treatment by either scaling and root planing, combination of Nd:YAG and Er:YAG lasers, or by Er:YAG laser treatment alone. The study involved 60 patients with generalized chronic periodontitis, randomly assigned into one of three treatment groups of 20 patients. The first group received scaling and root planing by hand instruments (SRP group), the second group received Er:YAG laser treatment alone (Er group), and the third group received combined treatment with Nd:YAG and Er:YAG lasers (NdErNd group). Microbiological samples, taken from the periodontal pockets at baseline and 6 months after treatments, were assessed with PET Plus tests. The combined NdErNd laser (93.0%), followed closely by Er:YAG laser (84.9%), treatment resulted in the highest reduction of all bacteria count after 6 months, whereas SRP (46.2%) failed to reduce Treponema denticola, Peptostreptococcus micros, and Capnocytophaga gingivalis. Full-mouth plaque and bleeding on probing scores dropped after 6 months and were the lowest in both laser groups. The combination of NdErNd resulted in higher probing pocket depth reduction and gain of clinical attachment level (1.99 ± 0.23 mm) compared to SRP (0.86 ± 0.13 mm) or Er:YAG laser alone (0.93 ± 0.20 mm) in 4-6 mm-deep pockets. Within their limits, the present results provide support for the combination of Nd:YAG and Er:YAG lasers to additionally improve the microbiological and clinical outcomes of nonsurgical periodontal therapy in patients with moderate to severe chronic periodontitis.

  12. Clinical and bacteriological study of the effect of Nd:YAG laser in gingivitis therapy

    Science.gov (United States)

    Colojoara, Carmen; Mavrantoni, Androniki; Miron, Mariana I.

    2000-06-01

    The relationship between dental plaque and gingivitis was verified. Nonspecific gingivitis is an inflammatory process, frequently caused by enzymes and toxins liberate by bacteria form dental plaque. Loose plaque has come under a great deal of investigation because of its role in attachment loss. The current methods used in the treatment of non specific gingivitis encompass the use of antibiotics and conventional surgical techniques. Treating gingivitis with laser energy may further reduce the gingival inflammation and decrease the wound healing time. The lack of correlation between the quantity of dental plaque and the intensity of gingivitis determined us to study the effect of Nd:YAG pulsed laser in reduction of gingival inflammation and wound healing. The aim of this work is to evaluate clinically the anti- inflammatory and wound healing effect of pulsed Nd:YAG laser and to compare the appearance and the levels of the bacteria in the supergingival and subgingival plaque in adolescents with tooth crowding after Nd:YAG laser. The experimental procedure consisted of a clinical and bacteriological study which was undertaken in 20 patients presenting moderate gingivitis. A group of 10 patients was the subject of a bacteriological study and the other group of 10 was used for clinical and histological examination. For each group the clinical criteria of evaluation were: the gingival index, papillary bleeding index, spontaneous aches. Each patient was tested before and after laser exposure or conventional therapy for bacteriological analyses. The results prove that early gingivitis exposure to laser registers a decrease of bacterial colony number and absence of loss of attachment as compared to the application of the conventional treatment. Clinical study has shown that the combination of scaling and root planning with laser therapy is enough to provide improvement in clinical indices and reduction in the number of bacterial colonies.

  13. Prospective monitoring and self-report of previous falls among older women at high risk of falls and fractures: a study of comparison and agreement.

    Science.gov (United States)

    Garcia, Patrícia A; Dias, João M D; Silva, Silvia L A; Dias, Rosângela C

    2015-01-01

    The identification of the occurrence of falls is an important step for screening and for rehabilitation processes for the elderly. The methods of monitoring these events are susceptible to recording biases, and the choice of the most accurate method remains challenging. (i) To investigate the agreement between retrospective self-reporting and prospective monitoring of methods of recording falls, and (ii) to compare the retrospective self-reporting of falls and the prospective monitoring of falls and recurrent falls over a 12-month period among older women at high risk of falls and fractures. A total of 118 community-dwelling older women with low bone density were recruited. The incidence of falls was monitored prospectively in 116 older women (2 losses) via monthly phone calls over the course of a year. At the end of this monitoring period, the older women were asked about their recall of falls in the same 12-month period. The agreement between the two methods was analyzed, and the sensitivity and specificity of self-reported previous falls in relation to the prospective monitoring were calculated. There was moderate agreement between the prospective monitoring and the retrospective self-reporting of falls in classifying fallers (Kappa = 0.595) and recurrent fallers (Kappa = 0.589). The limits of agreement were 0.35 ± 1.66 falls. The self-reporting of prior falls had a 67.2% sensitivity and a 94.2% specificity in classifying fallers among older women and a 50% sensitivity and a 98.9% specificity in classifying recurrent fallers. Self-reporting of falls over a 12-month period underestimated 32.8% of falls and 50% of recurrent falls. The findings recommend caution if one is considering replacing monthly monitoring with annual retrospective questioning.

  14. The importance of continued exercise participation in quality of life and psychological well-being in previously inactive postmenopausal women: a pilot study.

    Science.gov (United States)

    Asbury, Elizabeth A; Chandrruangphen, Pornpat; Collins, Peter

    2006-01-01

    Exercise and physical activity provide a wide range of health benefits for postmenopausal women, although the impact of maintained exercise participation on psychological well-being is unclear. An exploration of continued exercise participation in psychological well-being after a moderate-intensity exercise program in previously inactive postmenopausal women was therefore undertaken. : Twenty-three healthy sedentary postmenopausal women (age 56 +/- 4 years) were randomly assigned to two groups. All participants completed the Short Form-36, Hospital Anxiety and Depression Scale (HADS), and Health Anxiety Questionnaire (HAQ) and then began a 6-week walking program at 50% heart rate reserve defined by (.-)V(O(2)) treadmill testing. Post-intervention, all participants underwent (.-)V(O(2)) treadmill testing and questionnaires. Group 1 was then instructed to continue exercising, whereas group 2 was instructed to desist for an additional 6-week period. On completion of the 6-week follow-up, participants completed a final set of questionnaires. Participants performed 97% of the prescribed 15-hour (900 minute) exercise program (875.1 +/- 177.4 minutes) in an average of 26 +/- 5 sessions. Total HAQ (P = 0.001), health worry (P = 0.001), fear of illness (P = 0.037), reassurance seeking behavior (P = 0.037), SF-36 well-being (P = 0.037), total HADS (P = 0.019), and HADS depression (P = 0.015) improved significantly following the exercise program. At follow-up, group 1 had lower HADS anxiety (P = 0.013), total HADS (P = 0.02), total HAQ (P = 0.03), and HAQ interference with life (P = 0.03) and significantly higher SF-36 energy (P = 0.01) than group 2. Healthy postmenopausal women gain significant psychological benefit from moderate-intensity exercise. However, exercise participation must continue to maintain improvements in psychological well-being and quality of life.

  15. Experimental and numerical studies on the issues in laser welding of light-weight alloys in a zero-gap lap joint configuration

    Science.gov (United States)

    Harooni, Masoud

    current study a non-destructive evaluation method based on spectroscopy is proposed to detect the presence of pores in the lap joint of laser welded AZ31B magnesium alloy. The electron temperature that is calculated by the Boltzmann plot method is correlated to the presence of pores in the weld bead. A separate series of experiments was performed to evaluate the effect of an oxide coating layer on the dynamic behavior of the molten pool in the laser welding of an AZ31B magnesium alloy in a zero-gap lap joint configuration. A high speed CCD camera assisted with a green laser as an illumination source was selected to record the weld pool dynamics. Another technique used in this study was two-pass laser welding process to join AZ31B magnesium sheet in a zero-gap, lap-shear configuration. Two groups of samples including one pass laser welding (OPLW) and two pass laser welding (TPLW) were studied. In the two pass laser welding procedure, the first pass is performed by a defocused laser beam on the top of the two overlapped sheets in order to preheat the faying surface prior to laser welding, while the second pass is applied to melt and eventually weld the samples. Tensile and microhardness tests were used to measure the mechanical properties of the laser welded samples. A spectrometer was also used in real-time to correlate pore formation with calculated electron temperature using the Boltzmann plot method. The results of calculated electron temperature confirmed the previous results in earlier chapter. Magnesium and aluminum are two alloys which are used in different industries mainly due to their light weight. The main use of these two alloys is in automotive industry. Since different parts of the automobiles can be manufactured with each of these two alloys, it is essential to evaluate the joining feasibility of dissimilar metals such as aluminum to magnesium. A 4 kW fiber laser is used to join AZ31B magnesium alloy to AA 6014 using an overlap joint configuration. Two

  16. Experimental study of laser-oxygen cutting of low-carbon steel using fibre and CO{sub 2} lasers under conditions of minimal roughness

    Energy Technology Data Exchange (ETDEWEB)

    Golyshev, A A; Malikov, A G; Orishich, A M; Shulyatyev, V B [S.A. Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2014-10-31

    The results of an experimental study of laser-oxygen cutting of low-carbon steel using fibre and CO{sub 2} lasers are generalised. The dependence of roughness of the cut surface on the cutting parameters is investigated, and the conditions under which the surface roughness is minimal are formulated. It is shown that for both types of lasers these conditions can be expressed in the same way in terms of the dimensionless variables – the Péclet number Pe and the output power Q of laser radiation per unit thickness of the cut sheet – and take the form of the similarity laws: Pe = const, Q = const. The optimal values of Pe and Q are found. We have derived empirical expressions that relate the laser power and cutting speed with the thickness of the cut sheet under the condition of minimal roughness in the case of cutting by means of radiation from fibre and CO{sub 2} lasers. (laser technologies)

  17. A quantum dynamics study of the benzopyran ring opening guided by laser pulses

    Science.gov (United States)

    Saab, Mohamad; Doriol, Loïc Joubert; Lasorne, Benjamin; Guérin, Stéphane; Gatti, Fabien

    2014-10-01

    The ring-opening photoisomerization of benzopyran, which occurs via a photochemical route involving a conical intersection, has been studied with quantum dynamics calculations using the multi-configuration time-dependent Hartree method (MCTDH). We introduce a mechanistic strategy to control the conversion of benzopyran to merocyanine with laser pulses. We use a six-dimensional model developed in a previous work for the potential energy surfaces (PES) based on an extension of the vibronic-coupling Hamiltonian model (diabatization method by ansatz), which depends on the most active degrees of freedom. The main objective of these quantum dynamics simulations is to provide a set of strategies that could help experimentalists to control the photoreactivity vs. photostability ratio (selectivity). In this work we present: (i) a pump-dump technique used to control the photostability, (ii) a two-step strategy to enhance the reactivity of the system: first, a pure vibrational excitation in the electronic ground state that prepares the system and, second, an ultraviolet excitation that brings the system to the first adiabatic electronic state; (iii) finally the effect of a non-resonant pulse (Stark effect) on the dynamics.

  18. Psychological and cognitive effects of laser printer emissions: A controlled exposure study.

    Science.gov (United States)

    Herbig, B; Jörres, R A; Schierl, R; Simon, M; Langner, J; Seeger, S; Nowak, D; Karrasch, S

    2018-01-01

    The possible impact of ultrafine particles from laser printers on human health is controversially discussed although there are persons reporting substantial symptoms in relation to these emissions. A randomized, single-blinded, cross-over experimental design with two exposure conditions (high-level and low-level exposure) was conducted with 23 healthy subjects, 14 subjects with mild asthma, and 15 persons reporting symptoms associated with laser printer emissions. To separate physiological and psychological effects, a secondary physiologically based categorization of susceptibility to particle effects was used. In line with results from physiological and biochemical assessments, we found no coherent, differential, or clinically relevant effects of different exposure conditions on subjective complaints and cognitive performance in terms of attention, short-term memory, and psychomotor performance. However, results regarding the psychological characteristics of participants and their situational perception confirm differences between the participants groups: Subjects reporting symptoms associated with laser printer emissions showed a higher psychological susceptibility for adverse reactions in line with previous results on persons with multiple chemical sensitivity or idiopathic environmental intolerance. In conclusion, acute psychological and cognitive effects of laser printer emissions were small and could be attributed only to different participant groups but not to differences in exposure conditions in terms of particle number concentrations. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Fractional Carbon Dioxide Laser for Keratosis Pilaris: A Single-Blind, Randomized, Comparative Study

    Directory of Open Access Journals (Sweden)

    Vasanop Vachiramon

    2016-01-01

    Full Text Available Objective. Keratosis pilaris (KP is a common condition which can frequently be cosmetically disturbing. Topical treatments can be used with limited efficacy. The objective of this study is to evaluate the effectiveness and safety of fractional carbon dioxide (CO2 laser for the treatment of KP. Patients and Methods. A prospective, randomized, single-blinded, intraindividual comparative study was conducted on adult patients with KP. A single session of fractional CO2 laser was performed to one side of arm whereas the contralateral side served as control. Patients were scheduled for follow-up at 4 and 12 weeks after treatment. Clinical improvement was graded subjectively by blinded dermatologists. Patients rated treatment satisfaction at the end of the study. Results. Twenty patients completed the study. All patients stated that the laser treatment improved KP lesions. At 12-week follow-up, 30% of lesions on the laser-treated side had moderate to good improvement according to physicians’ global assessment (p=0.02. Keratotic papules and hyperpigmentation appeared to respond better than the erythematous component. Four patients with Fitzpatrick skin type V developed transient pigmentary alteration. Conclusions. Fractional CO2 laser treatment may be offered to patients with KP. Dark-skinned patients should be treated with special caution.

  20. Study on the lithium compound clusters using laser ablation

    International Nuclear Information System (INIS)

    Yokoyama, Keiichi

    2001-01-01

    Lithium-rich nonstoichiometric binary clusters including hyperlithiated molecules were found to be produced by a nanosecond laser ablation of lithium metal or compound target. Structural information on Li 3 O was obtained for the first time from experiments by measuring and analyzing photoionization efficiency curves of mass-selected ions. For example, the structure of Li 3 O was concluded to have both D 3h and C 2v symmetry. In other words, the vibrational wavefunction even at the ground state spreads over the C 2v and D 3h minima, which has been predicted as the global minimum in the latest theoretical calculations. Also, this is the first experimental evidence for electronomers'. (author)

  1. Laser beam studies of RPC behaviour in avalanche mode

    Energy Technology Data Exchange (ETDEWEB)

    Golovatyuk, V. E-mail: slava@le.infn.it; Grancagnolo, F.; Perrino, R

    2003-08-01

    Primary ionization is created inside the gas gap of a small size (10x20 cm{sup 2}) RPC, analogous to the RPC of the ATLAS muon detector, by focusing a pulsed (width {<=}0.5 ns) nitrogen laser beam (transverse diameter {approx}15 {mu}m). With this set-up we can characterize the behaviour of the RPC by measuring such parameters as drift velocity and gas amplification. For an ATLAS-like gas mixture (97% C{sub 2}H{sub 2}F{sub 4}, 3% isobutane and a small addition of SF{sub 6}), we have evidence of a space charge influence on RPC rate capability.

  2. Laser-assisted decontamination—A wavelength dependent study

    Science.gov (United States)

    Nilaya, J. Padma; Raote, Pallavi; Kumar, Aniruddha; Biswas, Dhruba J.

    2008-09-01

    We present here the experimental results on cleaning of radioactive dielectric particulates, loosely deposited on stainless steel, by coherent light of 1064 nm wavelength and its three harmonics occurring at 532 nm, 355 nm and 266 nm, derived from an Nd-YAG laser. For the initial few exposures, the decontamination factor has been found to be highest when exposed to 1064 nm radiation. With increasing number of exposures, however, the radiation with reducing wavelength assumes a more important role as a cleaning agent. The observation of almost no cleaning with 1064 nm and much reduced cleaning with its harmonics when the contamination is deposited on a transparent substrate confirms the dominant role played by metal substrate towards expelling the loose particulates from its surface.

  3. The study on force, surface integrity, tool life and chip on laser assisted machining of inconel 718 using Nd:YAG laser source.

    Science.gov (United States)

    Venkatesan, K

    2017-07-01

    Inconel 718, a high-temperature alloy, is a promising material for high-performance aerospace gas turbine engines components. However, the machining of the alloy is difficult owing to immense shear strength, rapid work hardening rate during turning, and less thermal conductivity. Hence, like ceramics and composites, the machining of this alloy is considered as difficult-to-turn materials. Laser assisted turning method has become a promising solution in recent years to lessen cutting stress when materials that are considered difficult-to-turn, such as Inconel 718 is employed. This study investigated the influence of input variables of laser assisted machining on the machinability aspect of the Inconel 718. The comparison of machining characteristics has been carried out to analyze the process benefits with the variation of laser machining variables. The laser assisted machining variables are cutting speeds of 60-150 m/min, feed rates of 0.05-0.125 mm/rev with a laser power between 1200 W and 1300 W. The various output characteristics such as force, roughness, tool life and geometrical characteristic of chip are investigated and compared with conventional machining without application of laser power. From experimental results, at a laser power of 1200 W, laser assisted turning outperforms conventional machining by 2.10 times lessening in cutting force, 46% reduction in surface roughness as well as 66% improvement in tool life when compared that of conventional machining. Compared to conventional machining, with the application of laser, the cutting speed of carbide tool has increased to a cutting condition of 150 m/min, 0.125 mm/rev. Microstructural analysis shows that no damage of the subsurface of the workpiece.

  4. The study on force, surface integrity, tool life and chip on laser assisted machining of inconel 718 using Nd:YAG laser source

    Directory of Open Access Journals (Sweden)

    K. Venkatesan

    2017-07-01

    Full Text Available Inconel 718, a high-temperature alloy, is a promising material for high-performance aerospace gas turbine engines components. However, the machining of the alloy is difficult owing to immense shear strength, rapid work hardening rate during turning, and less thermal conductivity. Hence, like ceramics and composites, the machining of this alloy is considered as difficult-to-turn materials. Laser assisted turning method has become a promising solution in recent years to lessen cutting stress when materials that are considered difficult-to-turn, such as Inconel 718 is employed. This study investigated the influence of input variables of laser assisted machining on the machinability aspect of the Inconel 718. The comparison of machining characteristics has been carried out to analyze the process benefits with the variation of laser machining variables. The laser assisted machining variables are cutting speeds of 60–150 m/min, feed rates of 0.05–0.125 mm/rev with a laser power between 1200 W and 1300 W. The various output characteristics such as force, roughness, tool life and geometrical characteristic of chip are investigated and compared with conventional machining without application of laser power. From experimental results, at a laser power of 1200 W, laser assisted turning outperforms conventional machining by 2.10 times lessening in cutting force, 46% reduction in surface roughness as well as 66% improvement in tool life when compared that of conventional machining. Compared to conventional machining, with the application of laser, the cutting speed of carbide tool has increased to a cutting condition of 150 m/min, 0.125 mm/rev. Microstructural analysis shows that no damage of the subsurface of the workpiece.