Pulse-to-pulse variations in accreting X-ray pulsars

Directory of Open Access Journals (Sweden)

Kretschmar Peter

2014-01-01

Full Text Available In most accreting X-ray pulsars, the periodic signal is very clear and easily shows up as soon as data covering sufficient pulse periods (a few ten are available. The mean pulse profile is often quite typical for a given source and with minor variations repeated and recognisable across observations done years or even decades apart. At the time scale of individual pulses, significant pulse-to-pulse variations are commonly observed. While at low energies some of these variations might be explained by absorption, in the hard X-rays they will reflect changes in the accretion and subsequent emission. The amount of these variations appears to be quite different between sources and contains information about the surrounding material as well ass possibly interactions at the magnetosphere. We investigate such variations for a sample of well-known sources.

Experimental investigation of 1 GW repeatable ultra-wide band pulse radiating source

International Nuclear Information System (INIS)

Meng Fanbao; Ma Hongge; Zhou Chuanming; Yang Zhoubing; Lu Wei; Ju Bingquan; Yu Huilong

2001-01-01

The single cycle pulse of 1.6 GW peak power with 20 Hz repetition-rate was generated. It radiated a peak power of more than 500 MW with a coaxial biconical antenna. The technological problems of the insulation and energy loss during generating and radiating high peak power ultra-wide band (UWB) pulse have been resolved. The experiments show that the material insulation and dispersion in sub-nanosecond pulse should be investigated deeply

Experimental investigation of 1 GW repeatable ultra-wide band pulse radiating source

Energy Technology Data Exchange (ETDEWEB)

Fanbao, Meng; Hongge, Ma; Chuanming, Zhou; Zhoubing, Yang; Wei, Lu; Bingquan, Ju; Huilong, Yu [China Academy of Engineering Physics, Chengdu (China)

2000-11-01

The single cycle pulse of 1.6 GW peak power with 20 Hz repetition-rate was generated. It radiated a peak power of more than 500 MW with a coaxial biconical antenna. The technological problems of the insulation and energy loss during generating and radiating high peak power ultra-wide band (UWB) pulse have been resolved. The experiments show that the material insulation and dispersion in subnanosecond pulse should be investigated deeply.

Proteome Analysis of Human Arterial Tissue Discloses Associations Between the Vascular Content of Small Leucine-Rich Repeat Proteoglycans and Pulse Wave Velocity

DEFF Research Database (Denmark)

Lyck Hansen, Maria; Beck, Hans Christian; Irmukhamedov, Akhmadjon

2015-01-01

OBJECTIVES: We hypothesized that arterial stiffness is associated with changes in the arterial protein profile, particularly of extracellular matrix components. We aimed at determining differentially expressed proteins by quantitative proteome analysis in arterial tissue from patients with differ......OBJECTIVES: We hypothesized that arterial stiffness is associated with changes in the arterial protein profile, particularly of extracellular matrix components. We aimed at determining differentially expressed proteins by quantitative proteome analysis in arterial tissue from patients...... with different degrees of arterial stiffness. APPROACH AND RESULTS: Arterial stiffness, assessed by carotid-femoral pulse wave velocity (PWV), central blood pressure and augmentation index by pulse wave analysis were measured the day before surgery in a group of patients undergoing coronary artery bypass...... grafting. Protein extracts of well-defined, homogenous, nonatherosclerotic individual samples of the left mammary artery from 10 of these patients with high PWV and 9 with low PWV were compared by quantitative proteome analysis, using tandem mass tag labeling and nano-liquid chromatography mass...

Hose-Modulation Instability of Laser Pulses in Plasmas

International Nuclear Information System (INIS)

Sprangle, P.; Krall, J.; Esarey, E.

1994-01-01

A laser pulse propagating in a uniform plasma or a preformed plasma density channel is found to undergo a combination of hose and modulation instabilities, provided the pulse centroid has an initial tilt. Coupled equations for the laser centroid and envelope are derived and solved for a finite-length laser pulse. Significant coupling between the centroid and the envelope, harmonic generation in the envelope, and strong modification of the wake field can occur. Methods to reduce the growth rate of the laser hose instability are demonstrated

CO2-Tea pulse clipping using pulsed high voltage preionization for high spatial resolution I.R. Lidar systems

Directory of Open Access Journals (Sweden)

Gasmi Taieb

2018-01-01

Full Text Available An extra-cavity CO2-TEA laser pulse clipper for high spatial resolution atmospheric monitoring is presented. The clipper uses pulsed high voltageto facilitate the breakdown of the gas within the clipper cell. Complete extinction of the nitrogen tail, that degrades the range resolution of LIDARS, is obtained at pressures from 375 up to 1500 Torr for nitrogen and argon gases whereas an attenuation coefficient of almost 102 is achieved for helium. Excellent energy stability and pulse width repeatability were achieved using high voltage pre-ionized gas technique.

CO2-Tea pulse clipping using pulsed high voltage preionization for high spatial resolution I.R. Lidar systems

Science.gov (United States)

Gasmi, Taieb

2018-04-01

An extra-cavity CO2-TEA laser pulse clipper for high spatial resolution atmospheric monitoring is presented. The clipper uses pulsed high voltageto facilitate the breakdown of the gas within the clipper cell. Complete extinction of the nitrogen tail, that degrades the range resolution of LIDARS, is obtained at pressures from 375 up to 1500 Torr for nitrogen and argon gases whereas an attenuation coefficient of almost 102 is achieved for helium. Excellent energy stability and pulse width repeatability were achieved using high voltage pre-ionized gas technique.

Development of the pulsed muon facility at ISIS

International Nuclear Information System (INIS)

Eaton, G.H.; Scott, C.A.; Williams, W.G.

1994-01-01

The ISIS pulsed surface muon facility at RAL is presently undergoing a major expansion to provide three experimental ports with simultaneous single muon pulses at 50 Hz. This upgrade, funded by the European Community (EC), is described together with recent development results which are relevant to its future scientific programme. These new beam lines are expected to be available for experiments in June 1993. (orig.)

Development and application of sub-nanosecond pulse-repeatable hard X-ray source

International Nuclear Information System (INIS)

Quan Lin; Fan Yajun; Tu Jing

2013-01-01

A multipurpose X-ray source was developed to meet the needs of multitask application such as radiation detection, radiation imaging and so on. The multipurpose X-ray source has characteristic of adjustable width and energy, pulse-repetition operation, ultra-short pulse and fine stability. Its rising time is close to 98.6 ps, the operation voltage reaches 425 kV, and the peak fluence rate exceeds 2.07 × 10 18 cm -2 · s -1 at 10 cm, which provides an ideal radiation environment for relevant application. (authors)

Acute effects of repeated bouts of aerobic exercise on arterial stiffness after glucose ingestion.

Science.gov (United States)

Kobayashi, Ryota; Hashimoto, Yuto; Hatakeyama, Hiroyuki; Okamoto, Takanobu

2018-03-22

The aim of this study was to investigate the acute repeated bouts of aerobic exercise decrease leg arterial stiffness. However, the influence of repeated bouts of aerobic exercise on arterial stiffness after glucose ingestion is unknown. The present study investigates the acute effects of repeated bouts of aerobic exercise on arterial stiffness after the 75-g oral glucose tolerance test (OGTT). Ten healthy young men (age, 23.2 ± 0.9 years) performed repeated bouts of aerobic exercise trial (RE, 65% peak oxygen uptake; two 15 min bouts of cycling performed 20 min apart) and control trial (CON, seated and resting in a quiet room) at 80 min before the 75-g OGTT on separate days in a randomized, controlled crossover fashion. Carotid-femoral (aortic) and femoral-ankle (leg) pulse wave velocity, carotid augmentation index, brachial and ankle blood pressure, heart rate and blood glucose and insulin levels were measured before (baseline) and 30, 60 and 120 min after the 75-g OGTT. Leg pulse wave velocity, ankle systolic blood pressure and blood glucose levels increased from baseline after the 75-g OGTT in the CON trial, but not in the RE trial. The present findings indicate that acute repeated bouts of aerobic exercise before glucose ingestion suppress increases in leg arterial stiffness following glucose ingestion. RE trial repeated bouts of aerobic exercise trial; CON trial control trial; BG blood glucose; VO 2peak peak oxygen uptake; PWV Pulse wave velocity; AIx carotid augmentation index; BP blood pressure; HR heart rate; CVs coefficients of variation; RPE Ratings of perceived exertion; SE standard error.

Quantum key distribution with two-segment quantum repeaters

Energy Technology Data Exchange (ETDEWEB)

Kampermann, Hermann; Abruzzo, Silvestre; Bruss, Dagmar [Theoretische Physik III, Heinrich-Heine-Universitaet Duesseldorf (Germany)

2014-07-01

Quantum repeaters represent one possible way to achieve long-distance quantum key distribution. One way of improving the repeater rate and decreasing the memory coherence time is the usage of multiplexing. Motivated by the experimental fact that long-range connections are practically demanding, we extend the analysis of the quantum repeater multiplexing protocol to the case of short-range connections. We derive formulas for the repeater rate and we show that short-range connections lead to most of the benefits of a full-range multiplexing protocol. A less demanding QKD-protocol without quantum memories was recently introduced by Lo et al. We generalize this measurement-device-independent quantum key Distribution protocol to the scenario where the repeater Station contains also heralded quantum memories. We assume either single-photon sources or weak coherent pulse sources plus decay states. We show that it is possible to significantly outperform the original proposal, even in presence of decoherence of the quantum memory. We give formulas in terms of device imperfections i.e., the quantum bit error rate and the repeater rate.

Polymeric electrochemical element for adaptive networks: Pulse mode

International Nuclear Information System (INIS)

Smerieri, Anteo; Berzina, Tatiana; Erokhin, Victor; Fontana, M. P.

2008-01-01

An electrochemically controlled polymeric heterojunction working as a memristor, i.e., having memory properties, was investigated in pulse mode, mimicking synaptic behavior of signal transmission in biological systems. Influence of parameters such as pulse duration, interval between pulses, and value of potential base level was analyzed. Learning capabilities were shown to be reversible and repeatable for both potentiation and inhibition of signal transmission. The adaptive behavior of the element was investigated and was shown to be more efficient than the dc mode

Large Torque Variations in Two Soft Gamma Repeaters

NARCIS (Netherlands)

Woods, P.M.; Kouveliotou, C.; Göğüş, E.; Finger, M.H.; Swank, J.; Markwardt, C.B.; Hurley, K.; van der Klis, M.

2002-01-01

We have monitored the pulse frequencies of the two soft gamma repeaters SGR 1806-20 and SGR 1900+14 through the beginning of year 2001 using primarily Rossi X-Ray Timing Explorer Proportional Counter Array observations. In both sources, we observe large changes in the spin-down torque up to a factor

Effect of sequential isoproturon pulse exposure on Scenedesmus vacuolatus.

Science.gov (United States)

Vallotton, Nathalie; Eggen, Rik Ilda Lambertus; Chèvre, Nathalie

2009-04-01

Aquatic organisms are typically exposed to fluctuating concentrations of herbicides in streams. To assess the effects on algae of repeated peak exposure to the herbicide isoproturon, we subjected the alga Scenedesmus vacuolatus to two sequential pulse exposure scenarios. Effects on growth and on the inhibition of the effective quantum yield of photosystem II (PSII) were measured. In the first scenario, algae were exposed to short, 5-h pulses at high isoproturon concentrations (400 and 1000 microg/l), each followed by a recovery period of 18 h, while the second scenario consisted of 22.5-h pulses at lower concentrations (60 and 120 microg/l), alternating with short recovery periods (1.5 h). In addition, any changes in the sensitivity of the algae to isoproturon following sequential pulses were examined by determining the growth rate-EC(50) prior to and following exposure. In both exposure scenarios, we found that algal growth and its effective quantum yield were systematically inhibited during the exposures and that these effects were reversible. Sequential pulses to isoproturon could be considered a sequence of independent events. Nevertheless, a consequence of inhibited growth during the repeated exposures is the cumulative decrease in biomass production. Furthermore, in the second scenario, when the sequence of long pulses began to approach a scenario of continuous exposure, a slight increase in the tolerance of the algae to isoproturon was observed. These findings indicated that sequential pulses do affect algae during each pulse exposure, even if algae recover between the exposures. These observations could support an improved risk assessment of fluctuating exposures to reversibly acting herbicides.

Using a pulse oximeter to determine clinical depth of anesthesia-investigation of the utility of the perfusion index.

Science.gov (United States)

Krishnamohan, Anirudh; Siriwardana, Viraj; Skowno, Justin J

2016-11-01

Peripheral vasodilation is a well-recognized side effect of general anesthesia, and induces changes in the amplitude of the pulse plethysmograph (PPG) waveform. This can be continuously quantitaed using the Perfusion Index (PI), a ratio of the pulsatile to nonpulsatile signal amplitude in the PPG waveform. We hypothesized that the perfusion index would rise with the induction of anesthesia in children, and fall with emergence, and performed a prospective, observational study to test this. Our primary aim was to test whether the different clinical stages of anesthesia were associated with changes in the perfusion index, and the secondary aim was to test the correlation between the normalized perfusion index and the MAC value. Twenty-one patients between the ages of 1 and 18 undergoing minor procedures with no anticipated painful stimuli were recruited. Patients with significant illnesses were excluded. Data collection commenced with a preinduction baseline, and data were collected continuously, with event marking, until completion of the anesthesia and removal of the pulse oximeter. Data collected included perfusion index, heart rate, and anesthetic gas concentration values. A normalized perfusion index was calculated by subtracting the initial baseline perfusion index value from all perfusion index values, allowing changes, from a standardized initial baseline value of zero, to be analyzed. During induction, the mean normalized perfusion index rose from 0.0 to 4.2, and then declined to 0.470 when the patients returned to consciousness. P < 0.001 using repeated measures anova test. The normalized perfusion index was correlated with MAC values (r 2 = 0.33, 95% CI 0.18-0.47, P < 0.01). The perfusion index changed significantly during different stages of anesthesia. There is a significant correlation between the perfusion index, measured by pulse oximetry, and the MAC value, in pediatric patients undergoing minor procedures. © 2016 John Wiley & Sons Ltd.

L-band pulsed klystron for the JHP

International Nuclear Information System (INIS)

Fukuda, S.; Takeuchi, Y.; Hisamatsu, H.; Anami, S.; Kihara, M.; Takahashi, A.

1994-01-01

An L-band high-power klystron for the JHP (6 MW output power and 600 μsec pulse width) was designed at KEK. High-power tests of the test diodes were performed up to a beam voltage of 140 kV, a pulse width of 600 μsec and a repetition rate of 50 pps. The capability to meet the specifications of the gun and the collector was confirmed. High-power tests of the rf window were also performed up to rf powers of 4 MW (600 μsec pulse width) and 5 MW (375 μsec pulse width). We obtained good results for an rf window using high-purity alumina (99.7%). The design considerations and manufacturing process are also described. Manufacturing a prototype tube has been completed and the tube is undergoing the high-power tests. (author)

A repeating fast radio burst.

Science.gov (United States)

Spitler, L G; Scholz, P; Hessels, J W T; Bogdanov, S; Brazier, A; Camilo, F; Chatterjee, S; Cordes, J M; Crawford, F; Deneva, J; Ferdman, R D; Freire, P C C; Kaspi, V M; Lazarus, P; Lynch, R; Madsen, E C; McLaughlin, M A; Patel, C; Ransom, S M; Seymour, A; Stairs, I H; Stappers, B W; van Leeuwen, J; Zhu, W W

2016-03-10

Fast radio bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances. Previous follow-up observations have failed to find additional bursts at the same dispersion measure (that is, the integrated column density of free electrons between source and telescope) and sky position as the original detections. The apparent non-repeating nature of these bursts has led to the suggestion that they originate in cataclysmic events. Here we report observations of ten additional bursts from the direction of the fast radio burst FRB 121102. These bursts have dispersion measures and sky positions consistent with the original burst. This unambiguously identifies FRB 121102 as repeating and demonstrates that its source survives the energetic events that cause the bursts. Additionally, the bursts from FRB 121102 show a wide range of spectral shapes that appear to be predominantly intrinsic to the source and which vary on timescales of minutes or less. Although there may be multiple physical origins for the population of fast radio bursts, these repeat bursts with high dispersion measure and variable spectra specifically seen from the direction of FRB 121102 support an origin in a young, highly magnetized, extragalactic neutron star.

Laser pulse number dependent nanostructure evolution by illuminating self-assembled microsphere array

Science.gov (United States)

Feng, Dong; Weng, Ding; Wang, Bao; Wang, Jiadao

2017-12-01

Pulse number dependent evolution from nanodents to nanobumps has been studied on a bearing steel substrate, which was coated with a self-assembled monolayer of silica microspheres and repeatedly irradiated by an 800 nm femtosecond laser. Scanning electron microscope and atomic force microscope were employed to characterize nanopatterns, the dimensions of which were related to the laser pulse number and pulse fluences. The transformation depending on the number of laser pulses could be attributed to the changes of electric field distribution and material property after the impacts of multiple laser pulses, the process of which could be divided into three steps. First, the bottoms of silica microspheres were ablated because of the incubation effects from repeated irradiation. Second, strong plasmonic localization at the edges of the deep nanodents resulted in plasma-chemical reactions between ablated materials, which was confirmed by electromagnetic simulations. Third, recrystallized solid matter from ablated materials deposited in nanodents and then formed nanobumps, which was confirmed by transmission electron microscope and energy dispersive X-ray spectrometer analyses on their longitudinal sections.

Pulse Clarithromycin Therapy In Severe ACNE Vulgaris

Directory of Open Access Journals (Sweden)

Rathi Sanjay K

2002-01-01

Full Text Available Three patients with severe acne vulgaris, not responding with long courses of doxycycline, minocycline and erythromycin were given oral clarithromycin in pulsed regimen. The patients were given 7 days course of clarithromycin 250mg twice daily, which was repeated after a gap of 10 days. Such 3 courses were given. The lesions responded significantly. No significant side effect was noted. Pulse clarithromycin therapy seems to be a good alternative and effective tool in the management of severe acne vulgaris.

Self-focusing and guiding of short laser pulses in ionizing gases and plasmas

International Nuclear Information System (INIS)

Esarey, E.; Sprangle, P.; Krall, J.; Ting, A.

1997-01-01

The propagation of intense laser pulses in gases and plasmas is relevant to a wide range of applications, including laser-driven accelerators, laser-plasma channeling, harmonic generation, supercontinuum generation, X-ray lasers, and laser-fusion schemes. Here, several features of intense, short-pulse (≤1 ps) laser propagation in gases undergoing ionization and in plasmas are reviewed, discussed, and analyzed. The wave equations for laser pulse propagation in a gas undergoing ionization and in a plasma are derived. The source-dependent expansion method is discussed, which is a general method for solving the paraxial wave equation with nonlinear source terms. In gases, the propagation of high-power (near the critical power) laser pulses is considered including the effects of diffraction, nonlinear self-focusing, ionization, and plasma generation. Self-guided solutions and the stability of these solutions are discussed. In plasmas, optical guiding by relativistic effects, ponderomotive effects, and preformed density channels is considered. The self-consistent plasma response is discussed, including plasma wave effects and instabilities such as self-modulation. Recent experiments on the guiding of laser pulses in gases and in plasmas are briefly summarized

Abortion trends from 1996 to 2011 in Estonia: special emphasis on repeat abortion

Science.gov (United States)

2014-01-01

Background The study aimed to describe the overall and age-specific trends of induced abortions from 1996 to 2011 with an emphasis on socio-demographic characteristics and contraceptive use of women having had repeat abortions in Estonia. Methods Data were retrieved from the Estonian Medical Birth and Abortion Registry and Statistics Estonia. Total induced abortion numbers, rates, ratios and age-specific rates are presented for 1996–2011. The percentage change in the number of repeat abortions within selected socio-demographic subgroups, contraception use and distribution of induced abortions among Estonians and non-Estonians for the first, second, third, fourth and subsequent abortions were calculated for the periods 1996–2003 and 2004–2011. Results Observed trends over the 16-year study period indicated a considerable decline in induced abortions with a reduction in abortion rate of 57.1%, which was mainly attributed to younger cohorts. The percentage of women undergoing repeat abortions fell steadily from 63.8% during 1996–2003 to 58.0% during 2004–2011. The percentage of women undergoing repeat abortions significantly decreased over the 16 years within all selected socio-demographic subgroups except among women with low educational attainment and students. Within each time period, a greater percentage of non-Estonians than Estonians underwent repeat abortions and obtained third and subsequent abortions. Most women did not use any contraceptive method prior to their first or subsequent abortion. Conclusion A high percentage of women obtaining repeat abortions reflects a high historical abortion rate. If current trends continue, a rapid decline in repeat abortions may be predicted. To decrease the burden of sexual ill health, routine contraceptive counselling, as standard care in the abortion process, should be seriously addressed with an emphasis on those groups - non-Estonians, women with lower educational attainment, students and women with children

Photoplethysmogram signal quality estimation using repeated Gaussian filters and cross-correlation

International Nuclear Information System (INIS)

Karlen, W; Kobayashi, K; Dumont, G A; Ansermino, J M

2012-01-01

Pulse oximeters are monitors that noninvasively measure heart rate and blood oxygen saturation (SpO 2 ). Unfortunately, pulse oximetry is prone to artifacts which negatively impact the accuracy of the measurement and can cause a significant number of false alarms. We have developed an algorithm to segment pulse oximetry signals into pulses and estimate the signal quality in real time. The algorithm iteratively calculates a signal quality index (SQI) ranging from 0 to 100. In the presence of artifacts and irregular signal morphology, the algorithm outputs a low SQI number. The pulse segmentation algorithm uses the derivative of the signal to find pulse slopes and an adaptive set of repeated Gaussian filters to select the correct slopes. Cross-correlation of consecutive pulse segments is used to estimate signal quality. Experimental results using two different benchmark data sets showed a good pulse detection rate with a sensitivity of 96.21% and a positive predictive value of 99.22%, which was equivalent to the available reference algorithm. The novel SQI algorithm was effective and produced significantly lower SQI values in the presence of artifacts compared to SQI values during clean signals. The SQI algorithm may help to guide untrained pulse oximeter users and also help in the design of advanced algorithms for generating smart alarms. (paper)

Photoplethysmogram signal quality estimation using repeated Gaussian filters and cross-correlation.

Science.gov (United States)

Karlen, W; Kobayashi, K; Ansermino, J M; Dumont, G A

2012-10-01

Pulse oximeters are monitors that noninvasively measure heart rate and blood oxygen saturation (SpO2). Unfortunately, pulse oximetry is prone to artifacts which negatively impact the accuracy of the measurement and can cause a significant number of false alarms. We have developed an algorithm to segment pulse oximetry signals into pulses and estimate the signal quality in real time. The algorithm iteratively calculates a signal quality index (SQI) ranging from 0 to 100. In the presence of artifacts and irregular signal morphology, the algorithm outputs a low SQI number. The pulse segmentation algorithm uses the derivative of the signal to find pulse slopes and an adaptive set of repeated Gaussian filters to select the correct slopes. Cross-correlation of consecutive pulse segments is used to estimate signal quality. Experimental results using two different benchmark data sets showed a good pulse detection rate with a sensitivity of 96.21% and a positive predictive value of 99.22%, which was equivalent to the available reference algorithm. The novel SQI algorithm was effective and produced significantly lower SQI values in the presence of artifacts compared to SQI values during clean signals. The SQI algorithm may help to guide untrained pulse oximeter users and also help in the design of advanced algorithms for generating smart alarms.

Channeling and stability of laser pulses in plasmas

International Nuclear Information System (INIS)

Sprangle, P.; Krall, J.; Esarey, E.

1995-01-01

A laser pulse propagating in a plasma is found to undergo a combination of hose and modulation instabilities. The coupled equations for the laser beam envelope and centroid are derived and solved for a laser pulse of finite length propagating through either a uniform plasma or preformed plasma density channel. The laser envelope equation describes the pulse self-focusing and optical guiding in plasmas and is used to analyze the self-modulation instability. The laser centroid equation describes the transverse motion of the laser pulse (hosing) in plasmas. Significant coupling between the centroid and envelope motion as well as harmonic generation in the envelope can occur. In addition, the transverse profile of the generated wake field is strongly affected by the laser hose instability. Methods to reduce the laser hose instability are demonstrated. copyright 1995 American Institute of Physics

Time moments of the energy flow of optical pulses in highly dispersive media

International Nuclear Information System (INIS)

Nanda, Lipsa; Wanare, Harshawardhan; Ramakrishna, S Anantha

2010-01-01

We use the time moments of the Poynting vector associated with an electromagnetic pulse to characterize the traversal times and temporal pulse widths as the pulse propagates in highly dispersive media. The behaviour of these quantities with the propagation distance is analysed in three canonical cases: Lorentz absorptive medium, a Raman gain doublet amplifying medium and a medium exhibiting electromagnetically induced transparency. We find that superluminal pulse propagation in the first two cases with anomalous dispersion is usually accompanied by pulse compression and eventually the pulse becomes subluminal with increasing distance of propagation. In a medium with electromagnetically induced transparency with large normal dispersion, we identify a range of frequencies for which the pulse undergoes minimal temporal expansion while propagating with ultra-slow speed.

Ultrashort X-ray pulse science

Energy Technology Data Exchange (ETDEWEB)

Chin, Alan Hap [Univ. of California, Berkeley, CA (US). Dept. of Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

1998-05-01

A variety of phenomena involves atomic motion on the femtosecond time-scale. These phenomena have been studied using ultrashort optical pulses, which indirectly probe atomic positions through changes in optical properties. Because x-rays can more directly probe atomic positions, ultrashort x-ray pulses are better suited for the study of ultrafast structural dynamics. One approach towards generating ultrashort x-ray pulses is by 90° Thomson scattering between terawatt laser pulses and relativistic electrons. Using this technique, the author generated ~ 300 fs, 30 keV (0.4 Å) x-ray pulses. These x-ray pulses are absolutely synchronized with ultrashort laser pulses, allowing femtosecond optical pump/x-ray probe experiments to be performed. Using the right-angle Thomson scattering x-ray source, the author performed time-resolved x-ray diffraction studies of laser-perturbated InSb. These experiments revealed a delayed onset of lattice expansion. This delay is due to the energy relaxation from a dense electron-hole plasma to the lattice. The dense electron-hole plasma first undergoes Auger recombination, which reduces the carrier concentration while maintaining energy content. Longitudinal-optic (LO) phonon emission then couples energy to the lattice. LO phonon decay into acoustic phonons, and acoustic phonon propagation then causes the growth of a thermally expanded layer. Source characterization is instrumental in utilizing ultrashort x-ray pulses in time-resolved x-ray spectroscopies. By measurement of the electron beam diameter at the generation point, the pulse duration of the Thomson scattered x-rays is determined. Analysis of the Thomson scattered x-ray beam properties also provides a novel means of electron bunch characterization. Although the pulse duration is inferred for the Thomson scattering x-ray source, direct measurement is required for other x-ray pulse sources. A method based on the laser-assisted photoelectric effect (LAPE) has been demonstrated as a

Ultrashort X-ray pulse science

International Nuclear Information System (INIS)

Chin, A.H.; Lawrence Berkeley National Lab., CA

1998-01-01

A variety of phenomena involves atomic motion on the femtosecond time-scale. These phenomena have been studied using ultrashort optical pulses, which indirectly probe atomic positions through changes in optical properties. Because x-rays can more directly probe atomic positions, ultrashort x-ray pulses are better suited for the study of ultrafast structural dynamics. One approach towards generating ultrashort x-ray pulses is by 90 o Thomson scattering between terawatt laser pulses and relativistic electrons. Using this technique, the author generated ∼ 300 fs, 30 keV (0.4 (angstrom)) x-ray pulses. These x-ray pulses are absolutely synchronized with ultrashort laser pulses, allowing femtosecond optical pump/x-ray probe experiments to be performed. Using the right-angle Thomson scattering x-ray source, the author performed time-resolved x-ray diffraction studies of laser-perturbated InSb. These experiments revealed a delayed onset of lattice expansion. This delay is due to the energy relaxation from a dense electron-hole plasma to the lattice. The dense electron-hole plasma first undergoes Auger recombination, which reduces the carrier concentration while maintaining energy content. Longitudinal-optic (LO) phonon emission then couples energy to the lattice. LO phonon decay into acoustic phonons, and acoustic phonon propagation then causes the growth of a thermally expanded layer. Source characterization is instrumental in utilizing ultrashort x-ray pulses in time-resolved x-ray spectroscopies. By measurement of the electron beam diameter at the generation point, the pulse duration of the Thomson scattered x-rays is determined. Analysis of the Thomson scattered x-ray beam properties also provides a novel means of electron bunch characterization. Although the pulse duration is inferred for the Thomson scattering x-ray source, direct measurement is required for other x-ray pulse sources. A method based on the laser-assisted photoelectric effect (LAPE) has been

On the improvement of signal repeatability in laser-induced air plasmas

Science.gov (United States)

Zhang, Shuai; Sheta, Sahar; Hou, Zong-Yu; Wang, Zhe

2018-04-01

The relatively low repeatability of laser-induced breakdown spectroscopy (LIBS) severely hinders its wide commercialization. In the present work, we investigate the optimization of LIBS system for repeatability improvement for both signal generation (plasma evolution) and signal collection. Timeintegrated spectra and images were obtained under different laser energies and focal lengths to investigate the optimum configuration for stable plasmas and repeatable signals. Using our experimental setup, the optimum conditions were found to be a laser energy of 250 mJ and a focus length of 100 mm. A stable and homogeneous plasma with the largest hot core area in the optimum condition yielded the most stable LIBS signal. Time-resolved images showed that the rebounding processes through the air plasma evolution caused the relative standard deviation (RSD) to increase with laser energies of > 250 mJ. In addition, the emission collection was improved by using a concave spherical mirror. The line intensities doubled as their RSDs decreased by approximately 25%. When the signal generation and collection were optimized simultaneously, the pulse-to-pulse RSDs were reduced to approximately 3% for O(I), N(I), and H(I) lines, which are better than the RSDs reported for solid samples and showed great potential for LIBS quantitative analysis by gasifying the solid or liquid samples.

The Impact of Repeated Freeze-Thaw Cycles on the Quality of Biomolecules in Four Different Tissues.

Science.gov (United States)

Ji, Xiaoli; Wang, Min; Li, Lingling; Chen, Fang; Zhang, Yanyang; Li, Qian; Zhou, Junmei

2017-10-01

High-quality biosamples are valuable resources for biomedical research. However, some tissues are stored without being sectioned into small aliquots and have to undergo repeated freeze-thaw cycles throughout prolonged experimentation. Little is known regarding the effects of repeated freeze-thaw cycles on the quality of biomolecules in tissues. The aim of this study was to evaluate the impact of repeated freeze-thaw (at room temperature or on ice) cycles on biomolecules and gene expression in four different types of tissues. Each fresh tissue was sectioned into seven aliquots and snap-frozen before undergoing repeated freeze-thaw cycles at room temperature or on ice. Biomolecules were extracted and analyzed. Both relative and absolute quantification were used to detect the changes in gene expression. The results indicated that the impact of repeated freeze-thaw cycles on RNA integrity varied by tissue type. Gene expression, including the housekeeping gene, was affected in RNA-degraded samples according to absolute quantification rather than relative quantification. Furthermore, our results suggest that thawing on ice could protect RNA integrity compared with thawing at room temperature. No obvious degradation of protein or DNA was observed with repeated freeze-thaw cycles either at room temperature or on ice. This research provides ample evidence for the necessity of sectioning fresh tissues into small aliquots before snap-freezing, thus avoiding degradation of RNA and alteration of gene expression resulting from repeated freeze-thaw cycles. For frozen tissue samples that were already in storage and had to be used repeatedly during their lifecycle, thawing on ice or sectioned at ultralow temperature is recommended.

Repeat dose of gonadotropin-releasing hormone agonist trigger in polycystic ovarian syndrome undergoing In Vitro fertilization cycles provides a better cycle outcome - a proof-of-concept study

Directory of Open Access Journals (Sweden)

Krishna Deepika

2017-01-01

Full Text Available Objective: Is a single dose of gonadotropin-releasing hormone agonist (GnRHa trigger to induce final oocyte maturation in polycystic ovarian syndrome (PCOS undergoing in vitro fertilization (IVF cycles with GnRH antagonist protocol sufficient to provide optimal oocyte maturity? Design: This is a prospective, randomized, double-blind, proof-of-concept study. Setting: This study was carried out at a tertiary care center. Material and Methods: A total of 125 patients diagnosed with PCOS defined as per the ESHRE/ASRM Rotterdam criteria (2003 undergoing IVF in antagonist protocol were randomized into two groups. Group A: single dose of GnRHa 0.2 mg, 35 h prior to oocyte retrieval, and Group B: 0.2 mg GnRHa 35 h prior to oocyte retrieval + repeat dose of 0.1 mg 12 h following the 1st dose. 12 h post-trigger, luteinizing hormone (LH, progesterone (P4, and follicle-stimulating hormone (FSH values were estimated. Statistical Analysis: Continuous variables were expressed as mean ± standard deviation and categorical variables as proportions where applicable. Independent sample t-test was used for continuous variables which were normally distributed and Mann–Whitney U-test for data not normally distributed. Chi-square test or Fisher's exact test was used for categorical variables where appropriate. Odds ratio (OR with 95% confidence intervals (CIs was calculated. In addition, receiver operating characteristic curve was used to evaluate the post-trigger LH, P4, and FSH values at 12 h as predictors of oocyte maturity. Main Outcome Measures: Primary outcome: maturity rate of the oocytes. Secondary outcomes: oocyte yield, fertilization rate, availability of good quality embryos on day 3, blastocyst conversion, OHSS rates, post-trigger serum LH (IU/L, FSH (IU/L, and P4 (ng/mL levels implantation rate and clinical pregnancy rate. Results: A higher number of mature (metaphase II oocytes were obtained in Group B compared to Group A (OR of 0.47; CI: 0.38–0

Fast quadrupole pulsed power supply in the AGS

International Nuclear Information System (INIS)

Nawrocky, R.J.; Halama, H.J.; Lambiase, R.F.; Montemurro, P.A.

1984-01-01

As part of the Polarized Proton Project at the AGS, a pulsed power supply system has been developed to energize a set of twelve fast quadrupoles which are symmetrically distributed around the 1/2-mile circumference of the machine. During a typical acceleration cycle, which is normally repeated every 2.4 s, these magnets are energized with bursts of triangular current pulses. The rise-time of each pulse is less than 2 μs and the width at the base varies from 1 to 3.5 ms depending on the pulse. Within a burst, pulses alternate in polarity and vary in amplitude from 160 A to 2700 A peak. Pulse separation is on the order of 40 ms. Due to the distributed nature of the load and high di/dt, each magnet is powered by a separate modulator. Magnets are driven via coaxial pulse transmission cables up to 200 ft long. In the modulators, the high power pulses are switched with thyratron/ignitron switch pairs. All modulators are charged in parallel with a common system of programmable high voltage power supplies. The overall system is controlled with a distributed network of microcomputers. This paper describes the development, construction and initial performance of the pulsed power supply system

Letter Report on 500 nA Pulsed Current from Field Ionization Source

International Nuclear Information System (INIS)

Ellsworth, Jennifer L.

2013-01-01

We recently produced a milestone 500 nA of pulsed current using 40 Ir field ionizer electrodes in our ion source. In conclusion, we have produced the milestone pulsed current of 500 nA using 40 electrochemically etched iridium tips in a field ionization source. The pulsed current output is repeatable and scales as expected with gas fill pressure and bias voltage. We expect these current will be sufficient to produce neutral yields of 1 · 10 7 DT n/s.

Initial proto II pulsed power tests

International Nuclear Information System (INIS)

Johnson, D.L.

1976-01-01

The Proto II electron beam accelerator is being developed by Sandia Laboratories to study engineering and physics aspects of electron beam pellet fusion. Currently the Marx generator-water capacitor portion of Proto II is undergoing high voltage testing and timing measurements. Eight 112 kJ Marx generators form the primary energy storage system. Each Marx generator pulse charges two parallel 7.5 nF water capacitors to 3 MV. The water capacitors act as intermediate energy storage elements and will transfer their energy to the water insulated pulse-forming lines in 250 ns by means of eight SF 6 gas insulated, trigatron switches. Test data and design considerations of the trigger systems, Marx generators, water capacitors, and trigatron switches are presented

Repeatability of pulse diagnosis and body constitution diagnosis in traditional Indian Ayurveda medicine

DEFF Research Database (Denmark)

Kurande, Vrinda; Waagepetersen, Rasmus; Toft, Egon

2012-01-01

In Ayurveda, pulse and body constitution diagnosis have a long historical use; still there is lack of quantitative measure on e.g. reliability of this diagnostic method. Reliability means consistency of information. Consistent diagnosis leads to consistent treatment and is important for clinical ...

Pulsed laser manipulation of an optically trapped bead: Averaging thermal noise and measuring the pulsed force amplitude

DEFF Research Database (Denmark)

Lindballe, Thue Bjerring; Kristensen, Martin V. G.; Keiding, Søren Rud

2013-01-01

An experimental strategy for post-eliminating thermal noise on position measurements of optically trapped particles is presented. Using a nanosecond pulsed laser, synchronized to the detection system, to exert a periodic driving force on an optically trapped 10 polystyrene bead, the laser pulse-bead...... interaction is repeated hundreds of times. Traces with the bead position following the prompt displacement from equilibrium, induced by each laser pulse, are averaged and reveal the underlying deterministic motion of the bead, which is not visible in a single trace due to thermal noise. The motion of the bead...... is analyzed from the direct time-dependent position measurements and from the power spectrum. The results show that the bead is on average displaced 208 nm from the trap center and exposed to a force amplitude of 71 nanoNewton, more than five orders of magnitude larger than the trapping forces. Our...

Optimal and safe treatment of spider leg veins measuring less than 1.5 mm on skin type IV patients, using repeated low-fluence Nd:YAG laser pulses after polidocanol injection.

Science.gov (United States)

Moreno-Moraga, Javier; Hernández, Esteban; Royo, Josefina; Alcolea, Justo; Isarría, M Jose; Pascu, Mihail Lucian; Smarandache, Adriana; Trelles, Mario

2013-05-01

Treatment of micro-veins of less than 1.5 mm with laser and with chemical sclerosis is technically challenging because of their difficulty to remedy. Laser treatment is even more difficult when dark phototypes are involved.Three groups of 30 patients each, skin type IV, and vessels measuring less than 1.5 mm in diameter, were enrolled for two treatment sessions 8 weeks apart: group A, polidocanol (POL) micro-foam injection; group B, Nd:YAG laser alone; and group C, laser after POL injection. Repeated 8-Hz low-fluence pulses, moving the hand piece over a 3-cm vein segment with an average of five laser passes maximum and with a total time irradiation of 1 s were used. Sixteen weeks after the second treatment, statistically, degree of clearance after examining photographs and patients satisfaction index, plotted on a visual analogue scale and comparing results of all three groups, results were significantly better for group C (psafe and satisfactory in 96 % of patients using low-fluence laser pulses with a total cumulative energy in the 3 cm venous segment, lower than that of conventional treatment. Very few and transient complications were observed. POL foam injection followed by laser pulses is safe and efficient for vein treatment in dark-skinned patients.

The Influence of Repeat Surgery and Residual Disease on Recurrence After Breast-Conserving Surgery

DEFF Research Database (Denmark)

Bodilsen, Anne; Bjerre, Karsten; Offersen, Birgitte V

2015-01-01

BACKGROUND: A significant proportion of women who have breast-conserving surgery (BCS) subsequently undergo re-excision or proceed to mastectomy. This study aimed to identify factors associated with residual disease after repeat surgery and to determine their effect on ipsilateral breast tumor re...

A compact plasma pre-ionized TEA-CO2 laser pulse clipper for material processing

Science.gov (United States)

Gasmi, Taieb

2017-08-01

An extra-laser cavity CO2-TEA laser pulse clipper using gas breakdown techniques for high spatial resolution material processing and shallow material engraving and drilling processes is presented. Complete extinction of the nitrogen tail, that extends the pulse width, is obtained at pressures from 375 up to 1500 torr for nitrogen and argon gases. Excellent energy stability and pulse repeatability were further enhanced using high voltage assisted preionized plasma gas technique. Experimental data illustrates the direct correlation between laser pulse width and depth of engraving in aluminum and alumina materials.

Influence of Music on Preoperative Anxiety and Physiologic Parameters in Women Undergoing Gynecologic Surgery.

Science.gov (United States)

Labrague, Leodoro J; McEnroe-Petitte, Denise M

2016-04-01

The aim of this study was to determine the influence of music on anxiety levels and physiologic parameters in women undergoing gynecologic surgery. This study employed a pre- and posttest experimental design with nonrandom assignment. Ninety-seven women undergoing gynecologic surgery were included in the study, where 49 were allocated to the control group (nonmusic group) and 48 were assigned to the experimental group (music group). Preoperative anxiety was measured using the State Trait Anxiety Inventory (STAI) while noninvasive instruments were used in measuring the patients' physiologic parameters (blood pressure [BP], pulse [P], and respiration [R]) at two time periods. Women allocated in the experimental group had lower STAI scores (t = 17.41, p music during the preoperative period in reducing anxiety and unpleasant symptoms in women undergoing gynecologic surgery. © The Author(s) 2014.

Polarization dependent nanostructuring of silicon with femtosecond vortex pulse

Directory of Open Access Journals (Sweden)

M. G. Rahimian

2017-08-01

Full Text Available We fabricated conical nanostructures on silicon with a tip dimension of ∼ 70 nm using a single twisted femtosecond light pulse carrying orbital angular momentum (ℓ=±1. The height of the nano-cone, encircled by a smooth rim, increased from ∼ 350 nm to ∼ 1 μm with the pulse energy and number of pulses, whereas the apex angle remained constant. The nano-cone height was independent of the helicity of the twisted light; however, it is reduced for linear polarization compared to circular at higher pulse energies. Fluid dynamics simulations show nano-cones formation when compressive forces arising from the radial inward motion of the molten material push it perpendicular to the surface and undergo re-solidification. Simultaneously, the radial outward motion of the molten material re-solidifies after reaching the cold boundary to form a rim. Overlapping of two irradiated spots conforms to the fluid dynamics model.

Formal education of patients about to undergo laparoscopic cholecystectomy.

Science.gov (United States)

Gurusamy, Kurinchi Selvan; Vaughan, Jessica; Davidson, Brian R

2014-02-28

an effect on patient knowledge (3 trials; 338 participants; SMD 0.19; 95% CI -0.02 to 0.41; very low quality evidence), patient satisfaction (2 trials; 305 patients; SMD 0.48; 95% CI -0.42 to 1.37; very low quality evidence), or patient anxiety (1 trial; 76 participants; SMD -0.37; 95% CI -0.82 to 0.09; very low quality evidence) between the two groups.A total of 173 participants undergoing elective laparoscopic cholecystectomy were randomised to electronic consent with repeat-back (patients repeating back the information provided) (92 participants) versus electronic consent without repeat-back (81 participants) in one trial of high risk of bias. The only outcome reported in this trial was patient knowledge. The effect on patient knowledge between the patient education with repeat-back versus patient education without repeat-back groups was imprecise and based on 1 trial of 173 participants; SMD 0.07; 95% CI -0.22 to 0.37; very low quality evidence). Due to the very low quality of the current evidence, the effects of formal patient education provided in addition to the standard information provided by doctors to patients compared with standard care remain uncertain. Further well-designed randomised clinical trials of low risk of bias are necessary.

The incidence of anticipatory nausea and vomiting after repeat cycle chemotherapy: the effect of granisetron.

Science.gov (United States)

Aapro, M. S.; Kirchner, V.; Terrey, J. P.

1994-01-01

Anticipatory nausea and vomiting (ANV) after repeated cycles of cytotoxic chemotherapy is thought to be a conditioned response to a conditioning stimulus. Good control of acute and delayed emesis may result in a lower incidence of ANV. We have analysed data from 574 chemotherapy patients who received granisetron as their antiemetic treatment during repeat cycle chemotherapy. Per treatment cycle, less than 10% of patients displayed symptoms of anticipatory nausea and 2% or less had symptoms of anticipatory vomiting. It is concluded that the use of granisetron as an antiemetic during the acute phase of chemotherapy may result in a lower incidence of ANV in patients undergoing repeat cycle chemotherapy. PMID:8180031

A pulsed load model and its impact on a synchronous-rectifier system

Science.gov (United States)

Hou, Pengfei; Xu, Ye; Li, Jianke; Wang, Jinquan; Zhang, Haitao; Yan, Jun; Wang, Chunming; Chen, Jingjing

2017-02-01

The pulsed load has become a developing trend of power loading. Unlike traditional loads, pulsed loads with current abrupt and repeated charges will result in unstable Microgrid operations because of their small capacity and inertia. In this paper, an Average Magnitude Sum Function (AMSF) is proposed to calculate the frequency of the grid, and based on AMSF, the Relative Deviation Rate (RDR) that characterises the impact of pulsed load on the AC side of the grid is defined and its calculation process is described in detail. In addition, the system dynamic characteristics under a pulsed load are analysed using an Insulated Gate Bipolar Transistor (IGBT) to control the on/off state of the resistive load for simulating a pulsed load. Finally, the transient characteristics of a synchronous-rectifier system with a pulsed load are studied and validated experimentally.

Assessing the repeatability of terrestrial laser scanning for monitoring gully topography: A case study from Aratula, Queensland, Australia

Science.gov (United States)

Goodwin, Nicholas Robert; Armston, John; Stiller, Isaac; Muir, Jasmine

2016-06-01

Terrestrial laser scanning (TLS) technology is a powerful tool for quantifying gully morphology and monitoring change over time. This is due to the high sampling density, sub-centimetre positional accuracies (x, y, z), flexibility of survey configurations and ability to link multiple TLS scans together. However, to ensure correct interpretation of results, research is needed to test the repeatability of TLS derived products to quantify the accuracy and separate 'false' from 'true' geomorphic change. In this study, we use the RIEGL VZ400 scanner to test the repeatability of TLS datasets for mapping gully morphology. We then quantify change following a rainfall event of approximately 100 mm. Our study site, located in south-east Queensland, Australia was chosen to be challenging from a repeatability perspective with high topographic variability. The TLS data capture involved three sets of linked scans: one survey pre-rainfall, to be compared to two surveys post-rainfall acquired on consecutive days. Change is considered negligible in the two post-rainfall scans to test survey repeatability. To verify TLS accuracy, an independent dataset of gully extent and spot heights were acquired using traditional total station techniques. Results confirm that the TLS datasets can be registered multi-temporally at sub-centimetre levels of accuracy in three dimensions. Total station and TLS elevation samples showed strong agreement with a mean error and standard deviation (SD) of residuals equal to 0.052 and 0.047 m, respectively (n = 889). Significantly, our repeatability tests found that return type and pulse deviation influence the accuracy and repeatability of DEMs in gully environments. Analysis of consecutive day datasets showed that DEMs derived from first return data recorded 40% higher SD of residual error than DEMs using multiple return data. A significant empirical relationship between pulse deviation and the variance of residuals for repeat DEMs is also shown (r2 = 0

Pulsed-laser heating: a tool for studying degradation of materials subjected to repeated high-temperature excursions

International Nuclear Information System (INIS)

Goldberg, A.; Cornell, R.H.

1980-01-01

The use of pulsed-laser heating was evaluated as a means to obtain high cyclic peak temperatures with short rise times. A two-stage neodymium glass laser was used which produces a 600-μs pulse with energy outputs of up to 100 J. Small disk-shaped samples of AISI 4340 steel served as targets. Some of these were coated with a tungsten deposit. The rear face of some of the targets was instrumented for evaluation of temperature, strain, and stress response. Post-shot metallographic evaluations were made on a number of targets. We saw evidence of surface melting, cracking, and phase transformation. Surface damage was related to differences in the number of pulse cycles and input energy level, variables in the target materials, and the extent of strain-induced stresses. These experiments were performed in air at 1 atm and ambient laboratory temperature. 36 figures

Size matters: Associations between the androgen receptor CAG repeat length and the intrafollicular hormone milieu

DEFF Research Database (Denmark)

Borgbo, T; Macek, M; Chrudimska, J

2015-01-01

Granulosa cell (GC) expressed androgen receptors (AR) and intrafollicular androgens are central to fertility. The transactivating domain of the AR contains a polymorphic CAG repeat sequence, which is linked to the transcriptional activity of AR and may influence the GC function. This study aims...... to evaluate the effects of the AR CAG repeat length on the intrafollicular hormone profiles, and the gene expression profiles of GC from human small antral follicles. In total, 190 small antral follicles (3-11 mm in diameter) were collected from 58 women undergoing ovarian cryopreservation for fertility...... expression compared to medium CAG repeat lengths (P = 0.03). In conclusion, long CAG repeat lengths in the AR were associated to significant attenuated levels of androgens and an increased conversion of testosterone into oestradiol, in human small antral follicles....

Diffusion-weighted MR imaging of the abdomen with pulse triggering

International Nuclear Information System (INIS)

Muertz, P.; Pauleit, D.; Traeber, F.; Kreft, B.P.; Schild, H.H.

2000-01-01

Purpose: The aim of this work was to reduce the influence of motion on diffusion-weighted MR images of the abdomen by pulse triggering of single-shot sequences. Methods: Five healthy volunteers were examined both without and with finger pulse-triggering of a diffusion-weighted single-shot echo planar MR imaging sequence at 1.5 T. Series of diffusion-weighted images were acquired at different phases of the cardiac cycle by varying the time delay between finger pulse and sequence acquisition. The measurements were repeated three times. The diffusion weighted images were analysed by measuring the signal intensities and by determining the ADC values within the spleen, kidney and liver. Results: The magnitude of motion artifacts on diffusion weighted images shows a strong dependence on the trigger delay. The optimum trigger delay is found to be between 500 and 600 ms. For these values the abdominal organs appear homogeneous on all diffusion weighted images and the strongest signal intensities are detected. At optimum triggering the accuracy of the apparent diffusion coefficients is up to 10 times better than without triggering. Moreover, the standard deviation of the repeated measurements is smaller than 12% for all volunteers and for all organs. Without triggering the standard deviation is larger by a factor of 4 on average. Conclusion: Pulse triggering of single-shot sequences leads to significant reduction of motion related artifacts on diffusion weighted images of the abdomen and provides more accurate and reproducible ADC values. (orig.) [de

Extending Teach and Repeat to Pivoting Wheelchairs

Directory of Open Access Journals (Sweden)

Guillermo Del Castillo

2003-02-01

Full Text Available The paper extends the teach-and-repeat paradigm that has been successful for the control of holonomic robots to nonholonomic wheelchairs which may undergo pivoting action over the course of their taught movement. Due to the nonholonomic nature of the vehicle kinematics, estimation is required -- in the example given herein, based upon video detection of wall-mounted cues -- both in the teaching and the tracking events. In order to accommodate motion that approaches pivoting action as well as motion that approaches straight-line action, the estimation equations of the Extended Kalman Filter and the control equations are formulated using two different definitions of a nontemporal independent variable. The paper motivates the need for pivoting action in real-life settings by reporting extensively on the abilities and limitations of estimation-based teach-and-repeat action where pivoting and near-pivoting action is disallowed. Following formulation of the equations in the near-pivot mode, the paper reports upon experiments where taught trajectories which entail a seamless mix of near-straight and near-pivot action are tracked.

Role of N2 molecules in pulse discharge production of I atoms for a pulsed chemical oxygen-iodine laser

International Nuclear Information System (INIS)

Kochetov, I V; Napartovich, A P; Vagin, N P; Yuryshev, N N

2011-01-01

A pulsed electric discharge is the most effective means to turn chemical oxygen-iodine laser (COIL) operation into the pulse mode by fast production of iodine atoms. Experimental studies and numerical simulations are performed on a pulsed COIL initiated by an electric discharge in a mixture CF 3 I : N 2 : O 2 ( 3 X) : O 2 (a 1 Δ g ) flowing out of a chemical singlet oxygen generator. A transverse pulsed discharge is realized at various iodide pressures. The model comprises a system of kinetic equations for neutral and charged species, the electric circuit equation, the gas thermal balance equation and the photon balance equation. Reaction rate coefficients for processes involving electrons are repeatedly re-calculated by the electron Boltzmann equation solver when the plasma parameters are changed. The processes accounted for in the Boltzmann equation include direct and stepwise excitation and ionization of atoms and molecules, dissociation of molecules, electron attachment processes, electron-ion recombination, electron-electron collisions and second-kind collisions. The last processes are particularly important because of a high singlet oxygen concentration in gas flow from the singlet oxygen chemical generator. A conclusion is drawn about satisfactory agreement between the theory and the experiment.

CO2 laser pulse shortening by laser ablation of a metal target

International Nuclear Information System (INIS)

Donnelly, T.; Mazoyer, M.; Lynch, A.; O'Sullivan, G.; O'Reilly, F.; Dunne, P.; Cummins, T.

2012-01-01

A repeatable and flexible technique for pulse shortening of laser pulses has been applied to transversely excited atmospheric (TEA) CO 2 laser pulses. The technique involves focusing the laser output onto a highly reflective metal target so that plasma is formed, which then operates as a shutter due to strong laser absorption and scattering. Precise control of the focused laser intensity allows for timing of the shutter so that different temporal portions of the pulse can be reflected from the target surface before plasma formation occurs. This type of shutter enables one to reduce the pulse duration down to ∼2 ns and to remove the low power, long duration tails that are present in TEA CO 2 pulses. The transmitted energy is reduced as the pulse duration is decreased but the reflected power is ∼10 MW for all pulse durations. A simple laser heating model verifies that the pulse shortening depends directly on the plasma formation time, which in turn is dependent on the applied laser intensity. It is envisaged that this plasma shutter will be used as a tool for pulse shaping in the search for laser pulse conditions to optimize conversion efficiency from laser energy to useable extreme ultraviolet (EUV) radiation for EUV source development.

Periodic pulsing of characteristic microearthquakes on the San Andreas fault.

Science.gov (United States)

Nadeau, Robert M; McEvilly, Thomas V

2004-01-09

Deep fault slip information from characteristically repeating microearthquakes reveals previously unrecognized patterns of extensive, large-amplitude, long-duration, quasiperiodic repetition of aseismic events along much of a 175-kilometer segment of the central San Andreas fault. Pulsing occurs both in conjunction with and independent of transient slip from larger earthquakes. It extends to depths of approximately 10 to 11 kilometers but may be deeper, and it may be related to similar phenomena occurring in subduction zones. Over much of the study area, pulse onset periods also show a higher probability of larger earthquakes, which may provide useful information for earthquake forecasting.

Understanding the C-pulse device and its potential to treat heart failure.

Science.gov (United States)

Sales, Virna L; McCarthy, Patrick M

2010-03-01

The Sunshine Heart C-Pulse (C-Pulse; Sunshine Heart Inc., Tustin, CA) device is an extra-aortic implantable counterpulsation pump designed as a non-blood contacting ambulatory heart assist device, which may provide relief from symptoms for class II-III congestive heart failure patients. It has a comparable hemodynamic augmentation to intra-aortic balloon counterpulsation devices. The C-Pulse cuff is implanted through a median sternotomy, secured around the ascending aorta, and pneumatically driven by an external system controller. Pre-clinical studies in the acute pig model, and initial temporary clinical studies in patients undergoing off-pump coronary bypass surgery have shown substantial increase in diastolic perfusion of the coronary vessels, which translated to a favorable improvement in ventricular function. A U.S. prospective multi-center trial to evaluate the safety and efficacy of the C-Pulse in class III patients with moderate heart failure is now in progress.

Repeated pulse feeding induces functional stability in anaerobic digestion.

Science.gov (United States)

De Vrieze, Jo; Verstraete, Willy; Boon, Nico

2013-07-01

Anaerobic digestion is an environmental key technology in the future bio-based economy. To achieve functional stability, a minimal microbial community diversity is required. This microbial community should also have a certain 'elasticity', i.e. the ability to rapidly adapt to suboptimal conditions or stress. In this study it was evaluated whether a higher degree of functional stability could be achieved by changing the feeding pattern, which can change the evenness, dynamics and richness of the bacterial community. The first reactor (CSTR stable ) was fed on daily basis, whereas the second reactor (CSTR dynamic ) was fed every 2 days. Average biogas production was 0.30 l CH4 l(-1) day(-1) in both reactors, although daily variation was up to four times higher in the CSTR dynamic compared with the CSTR stable during the first 50 days. Bacterial analysis revealed that this CSTR dynamic had a two times higher degree of bacterial community dynamics. The CSTR dynamic also appeared to be more tolerant to an organic shock load of 8 g COD l(-1) and ammonium levels up to 8000 mg TAN l(-1). These results suggest that the regular application of a limited pulse of organic material and/or a variation in the substrate composition might promote higher functional stability in anaerobic digestion. © 2013 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Safety and effectiveness of repeat arterial closure using the AngioSeal device in patients with hepatic malignancy.

Science.gov (United States)

Hieb, Robert A; Neisen, Melissa J; Hohenwalter, Eric J; Molnar, Jim A; Rilling, William S

2008-12-01

To retrospectively evaluate the safety and effectiveness of the use of the AngioSeal device for repeat arterial closure in patients with hepatic malignancy. A retrospective analysis of patients with hepatic malignancy who had undergone repeated arterial closure with the AngioSeal device was performed. All charts for patients undergoing transarterial chemoembolization or TheraSphere radioembolization were reviewed for the method of hemostasis and the number of arterial closures. A total of 53 patients (58.5% men, 41.5% women; mean age, 58.7 years) had repeat AngioSeal arterial puncture closure after chemoembolization or TheraSphere treatment. Percutaneous closure of the common femoral artery with the AngioSeal device was performed in accordance with the manufacturer's recommendations. The patients were examined for complications on follow-up. Effectiveness was defined by the ability to obtain satisfactory hemostasis. Safety was assessed by the absence of groin complications and by vessel patency on follow-up angiograms of the puncture site obtained at subsequent liver-directed therapy sessions. Fifty-three patients in this study group had a total of 203 common femoral artery punctures. There were a total of 161 closures with the AngioSeal device (79.3%): 58 (36%) single closures and 103 (64.0%) repeat closures. Of the 161 attempts at AngioSeal closure, there was one closure failure in the single-puncture group, yielding a success rate of 98.3%; and one closure failure in the repeat-puncture group, yielding a success rate of 99%. In these two patients, hemostasis was achieved with traditional manual compression without the need for any other device, and no complications were noted. The overall success rate of AngioSeal device closure was 98.7%. The repeat use of the AngioSeal closure device is safe and effective in patients with hepatic malignancy undergoing regional oncologic interventional procedures.

Stability of high current diode under 100-nanosecond-pulse voltage

International Nuclear Information System (INIS)

Lai Dingguo; Qiu Aici; Zhang Yongmin; Huang Jianjun; Ren Shuqing; Yang Li

2012-01-01

Stability of high current diode under pulse voltage with 80 ns and 34 ns rise time was studied on the flash Ⅱ accelerator. Influence of rise time of diode voltage on startup time and cathode emission uniformity and repeatability of diode impedance was analyzed by comparing the experimental results with numerically simulated results, and the influence mechanism was discussed. The startup time of diode increases with the increasing of rise time of voltage, and the repeatability of diode impedance decreases. Discal plane cathode is prone to emit rays intensely in the center area, the time that plasma covers the surface of the cathode increases and the shielding effect has more impact on cathode emission according to the increase of rise time. Local intense emission on the cathode increases expansion speed of plasma and reduces the effective emission area. The stability of characteristic impedance of diode under a pulse voltage with slow rise time is decreased by the combined action of expansion speed of plasma and the effective emission area. (authors)

Repeatability, number of harvests, and phenotypic stability of dry matter yield and quality traits of Panicum maximum jacq.

Directory of Open Access Journals (Sweden)

Francisco Duarte Fernandes

2017-04-01

Full Text Available Selection of superior forage genotypes is based on agronomic traits assayed in repeated measures. The questions are how repeatable the performance of individual genotypes is and how many harvests are needed to select the best genotypes. The objectives were to estimate repeatability coefficients of dry matter yield (DMY and forage quality, their phenotypic stability and the number of harvests needed for an accurate selection. Two randomized complete block design experiments data with 24 genotypes each, undergoing 12 and 16 harvests, over a period of 2 and 3 years, respectively, were used. The DMY repeatability estimates ranged from 0.42 to 0.55, suggesting a low heritability. The mean numbers of repeated measures were 5 and 7 harvests for 0.80 and 0.85 accuracy, respectively. The inclusion of the first two harvests negatively affects the estimates. Repeatability for quality traits ranged from 0.30 to 0.69, indicating low to moderate heritability.

Design and characterisation of a pulsed neutron interrogation facility

International Nuclear Information System (INIS)

Favalli, A.; Pedersen, B.

2007-01-01

The Joint Research Centre recently obtained a license to operate a new experimental device intended for research in the field of nuclear safeguards. The research projects currently being planned for the new device includes mass determination of fissile materials in matrices and detection of contraband non-nuclear materials. The device incorporates a commercial pulsed neutron generator and a large graphite mantle surrounding the sample cavity. In this configuration, a relatively high thermal neutron flux with a long lifetime is achieved inside the sample cavity. By pulsing the neutron generator, a sample may be interrogated by a pure thermal neutron flux during repeated time periods. The paper reports on the design of the new device and the pulsed fast and thermal neutron source. The thermal neutron flux caused by the neutron generator and the graphite structure has been characterised by foil activation, fission chamber and 3 He proportional counter measurements. (authors)

Somatic mosaicism of androgen receptor CAG repeats in colorectal carcinoma epithelial cells from men.

Science.gov (United States)

Di Fabio, Francesco; Alvarado, Carlos; Gologan, Adrian; Youssef, Emad; Voda, Linda; Mitmaker, Elliot; Beitel, Lenore K; Gordon, Philip H; Trifiro, Mark

2009-06-01

The X-linked human androgen receptor gene (AR) contains an exonic polymorphic trinucleotide CAG. The length of this encoded CAG tract inversely affects AR transcriptional activity. Colorectal carcinoma is known to express the androgen receptor, but data on somatic CAG repeat lengths variations in malignant and normal epithelial cells are still sporadic. Using laser capture microdissection (LCM), epithelial cells from colorectal carcinoma and normal-appearing mucosa were collected from the fresh tissue of eight consecutive male patients undergoing surgery (mean age, 70 y; range, 54-82). DNA isolated from each LCM sample underwent subsequent PCR and DNA sequencing to precisely determine AR CAG repeat lengths and the presence of microsatellite instability (MSI). Different AR CAG repeat lengths were observed in colorectal carcinoma (ranging from 0 to 36 CAG repeats), mainly in the form of multiple shorter repeat lengths. This genetic heterogeneity (somatic mosaicism) was also found in normal-appearing colorectal mucosa. Half of the carcinoma cases examined tended to have a higher number of AR CAG repeat lengths with a wider range of repeat size variation compared to normal mucosa. MSI carcinomas tended to have longer median AR CAG repeat lengths (n = 17) compared to microsatellite stable carcinomas (n = 14), although the difference was not significant (P = 0.31, Mann-Whitney test). Multiple unique somatic mutations of the AR CAG repeats occur in colorectal mucosa and in carcinoma, predominantly resulting in shorter alleles. Colorectal epithelial cells carrying AR alleles with shorter CAG repeat lengths may be more androgen-sensitive and therefore have a growth advantage.

Potentials and limitations of histone repeat sequences for phylogenetic reconstruction of Sophophora.

Science.gov (United States)

Baldo, A M; Les, D H; Strausbaugh, L D

1999-11-01

Simplified DNA sequence acquisition has provided many new data sets that are useful for phylogenetic reconstruction, including single- and multiple-copy nuclear and organellar genes. Although transcribed regions receive much attention, nontranscribed regions have recently been added to the repertoire of sequences suitable for phylogenetic studies, especially for closely related taxa. We evaluated the efficacy of a small portion of the histone repeat for phylogenetic reconstruction among Drosophila species. Histone repeats in invertebrates offer distinct advantages similar to those of widely used ribosomal repeats. First, the units are tandemly repeated and undergo concerted evolution. Second, histone repeats include both highly conserved coding and variable intergenic regions. This composition facilitates application of "universal" primers spanning potentially informative sites. We examined a small region of the histone repeat, including the intergenic spacer segments of coding regions from the divergently transcribed H2A and H2B histone genes. The spacer (about 230 bp) exists as a mosaic with highly conserved functional motifs interspersed with rapidly diverging regions; the former aid in alignment of the spacer. There are no ambiguities in alignment of coding regions. Coding and noncoding regions were analyzed together and separately for phylogenetic information. Parsimony, distance, and maximum-likelihood methods successfully retrieve the corroborated phylogeny for the taxa examined. This study demonstrates the resolving power of a small histone region which may now be added to the growing collection of phylogenetically useful DNA sequences.

Test-retest reliability of pulse amplitude tonometry measures of vascular endothelial function: implications for clinical trial design.

Science.gov (United States)

McCrea, Cindy E; Skulas-Ray, Ann C; Chow, Mosuk; West, Sheila G

2012-02-01

Endothelial dysfunction is an important outcome for assessing vascular health in intervention studies. However, reliability of the standard non-invasive method (flow-mediated dilation) is a significant challenge for clinical applications and multicenter trials. We evaluated the repeatability of pulse amplitude tonometry (PAT) to measure change in pulse wave amplitude during reactive hyperemia (Itamar Medical Ltd, Caesarea, Israel). Twenty healthy adults completed two PAT tests (mean interval = 19.5 days) under standardized conditions. PAT-derived measures of endothelial function (reactive hyperemia index, RHI) and arterial stiffness (augmentation index, AI) showed strong repeatability (intra-class correlations = 0.74 and 0.83, respectively). To guide future research, we also analyzed sample size requirements for a range of effect sizes. A crossover design powered at 0.90 requires 28 participants to detect a 15% change in RHI. Our study is the first to show that PAT measurements are repeatable in adults over an interval greater than 1 week.

Simple Theory of Thermal Fatigue Caused by RF Pulse Heating

CERN Document Server

Kuzikov, S

2004-01-01

The projects of electron-positron linear colliders imply that accelerating structures and other RF components will undergo action of extremely high RF fields. Except for breakdown threat there is an effect of the damage due to multi-pulse mechanical stress caused by Ohmic heating of the skin layer. A new theory of the thermal fatigue is considered. The theory is based on consideration of the quasi-elastic interaction between neighbor grains of metal due to the expansion of the thermal skin-layer. The developed theory predicts a total number of the RF pulses needed for surface degradation in dependence on temperature rise, pulse duration, and average temperature. The unknown coefficients in the final formula were found, using experimental data obtained at 11.4 GHz for the copper. In order to study the thermal fatigue at higher frequencies and to compare experimental and theoretical results, the experimental investigation of degradation of the copper cavity exposed to 30 GHz radiation is carried out now, basing...

Investigation of finger reflectance photoplethysmography in volunteers undergoing a local sympathetic stimulation

International Nuclear Information System (INIS)

Njoum, H; Kyriacou, P A

2013-01-01

Optical sensors used in clinical applications have gained great popularity over the last few decades, especially the photoplethysmographic (PPG) technique used in estimating arterial blood oxygen saturation in the well-known medical devices called pulse oximeters. In this study we investigate the photoplethysmogram further in an effort to understand its origin better, as there is a significant void in the current knowledge on the PPG quantitative measurement. The photoplethysmographic signal provides a heart rhythm pulsating AC component, and a non-pulsating DC component. The signal is commonly believed to originate from tissue volume changes only and hasn't been investigated intensively. This in vivo study examines the source of the PPG signal in relation to pulse amplitude and pulse rhythm while volunteers undergo a right hand ice immersion. It was found that the PPG signal is sensitive in detecting the sympathetic stimulation which corresponds to volumetric and heart rate changes. During the immersion, AC pulse amplitudes (PA) from both hands decreased significantly, while DC levels increased significantly in the right hand and non-significantly in the left hand. Also, a significant decrease in the pulse repetition time (PRT) was observed. Using blood pressure-flow theories, these results suggest that there are possibly other factors in the blood flow regulation that alter the blood optical density which contributes to the detected signal. Further studies need to investigate PPGs in relation to blood optical density and the dynamics of the pulsatile flow effects besides volumetric changes. Such investigations might explore further applications of the PPG in medicine.

Optically isolated, 2 kHz repetition rate, 4 kV solid-state pulse trigger generator.

Science.gov (United States)

Barnett, D H; Parson, J M; Lynn, C F; Kelly, P M; Taylor, M; Calico, S; Scott, M C; Dickens, J C; Neuber, A A; Mankowski, J J

2015-03-01

This paper presents the design and operation characteristics of a solid-state high voltage pulse generator. Its primary utilization is aimed at triggering a gaseous spark gap with high repeatability. Specifically, the trigger generator is designed to achieve a risetime on the order of 0.1 kV/ns to trigger the first stage, trigatron spark gap of a 10-stage, 500 kV Marx generator. The major design components are comprised of a 60 W constant current DC-DC converter for high voltage charging, a single 4 kV thyristor, a step-up pulse transformer, and magnetic switch for pulse steepening. A risetime of <30 ns and pulse magnitude of 4 kV is achieved matching the simulated performance of the design.

Repeat cesarean delivery: what indications are recorded in the medical chart?

Science.gov (United States)

Lydon-Rochelle, Mona T; Gardella, Carolyn; Cárdenas, Vicky; Easterling, Thomas R

2006-03-01

National surveillance estimates reported a troubling 63 percent decline in the rate of vaginal birth after cesarean delivery (VBAC) from 1996 (28.3%) to 2003 (10.6%), with subsequent rising rates of repeat cesarean delivery. The study objective was to examine patterns of documented indications for repeat cesarean delivery in women with and without labor. We conducted a population-based validation study of 19 nonfederal short-stay hospitals in Washington state. Of the 4,541 women who had live births in 2000, 11 percent (n = 493) had repeat cesarean without labor and 3 percent (n = 138) had repeat cesarean with labor. Incidence of medical conditions and pregnancy complications, patterns of documented indications for repeat cesarean delivery, and perioperative complications in relation to repeat cesarean delivery with and without labor were calculated. Of the 493 women who underwent a repeat cesarean delivery without labor, "elective"(36%) and "maternal request"(18%) were the most common indications. Indications for maternal medical conditions (3.0%) were uncommon. Among the 138 women with repeat cesarean delivery with labor, 60.1 percent had failure to progress, 24.6 percent a non-reassuring fetal heart rate, 8.0 percent cephalopelvic disproportion, and 7.2 percent maternal request during labor. Fetal indications were less common (5.8%). Breech, failed vacuum, abruptio placentae, maternal complications, and failed forceps were all indicated less than 5.0 percent. Women's perioperative complications did not vary significantly between women without and with labor. Regardless of a woman's labor status, nearly 10 percent of women with repeat cesarean delivery had no documented indication as to why a cesarean delivery was performed. "Elective" and "maternal request" were common indications among women undergoing repeat cesarean delivery without labor, and nearly 10 percent of women had undocumented indications for repeat cesarean delivery in their medical record

The repeatability and reproducibility of the BioRID IIg in a repeatable laboratory seat based on a production car seat.

Science.gov (United States)

Hynd, David; Depinet, Paul; Lorenz, Bernd

2013-01-01

The United Nations Economic Commission for Europe Informal Group on GTR No. 7 Phase 2 are working to define a build level for the BioRID II rear impact (whiplash) crash test dummy that ensures repeatable and reproducible performance in a test procedure that has been proposed for future legislation. This includes the specification of dummy hardware, as well as the development of comprehensive certification procedures for the dummy. This study evaluated whether the dummy build level and certification procedures deliver the desired level of repeatability and reproducibility. A custom-designed laboratory seat was made using the seat base, back, and head restraint from a production car seat to ensure a representative interface with the dummy. The seat back was reinforced for use in multiple tests and the recliner mechanism was replaced by an external spring-damper mechanism. A total of 65 tests were performed with 6 BioRID IIg dummies using the draft GTR No.7 sled pulse and seating procedure. All dummies were subject to the build, maintenance, and certification procedures defined by the Informal Group. The test condition was highly repeatable, with a very repeatable pulse, a well-controlled seat back response, and minimal observed degradation of seat foams. The results showed qualitatively reasonable repeatability and reproducibility for the upper torso and head accelerations, as well as for T1 Fx and upper neck Fx . However, reproducibility was not acceptable for T1 and upper neck Fz or for T1 and upper neck My . The Informal Group has not selected injury or seat assessment criteria for use with BioRID II, so it is not known whether these channels would be used in the regulation. However, the ramping-up behavior of the dummy showed poor reproducibility, which would be expected to affect the reproducibility of dummy measurements in general. Pelvis and spine characteristics were found to significantly influence the dummy measurements for which poor reproducibility was

Electromagnetic influences and pulsing hardness of integrated circuits

Directory of Open Access Journals (Sweden)

Petr Konstantinovich Skorobogatov

2016-10-01

Full Text Available The results of the single pulsing electrical overstress (EOS series with energy below the threshold of failure for modern submicron IC’s design are presented. The study was conducted on two types of modern sub-micron VLSI. The obtained results confirm the possibility of accumulation of the effects of damage from repeated exposure EOS in modern IC’s and allow you to get the dependence describing the additive nature of damage the IC’s during exposure to subthreshold EOS. The obtained dependence agrees well with the Arrhenius equation, which indicates the thermal nature of the damage when exposed to a series of subthreshold EOS.The method of the IC’s testing is proposed to determine the level of the IC’s EOS hardness to the effects of multiple different pulsing voltages.

Pulse Design in Solid-State Nuclear Magnetic Resonance

DEFF Research Database (Denmark)

Palani, Ravi Shankar

, where the former is the most widely used approach in NMR. AHT and Floquet theory, which use mathematical tools namely, Magnus expansion and Van Vleck transformations respectively, yield the same effective Hamiltonian that is valid for stroboscopic observation. The equivalence between the theories has...... coupling) interactions are referred to as dipolar recoupling pulse sequences and forms the subject of this dissertation. NMR experiments, that involve repeating (periodic) pulse sequences, are generally understood by finding an average or effective Hamiltonian (interaction, in the language of physics...... been discussed in the past in literature. Generalised expressions for the effective Hamiltonian using AHT are derived in the frequency domain in this dissertation, to allow for appreciation of the equivalence with Floquet theory mediated effective Hamiltonian. The derivation relies on the ability...

The effect of G-CSF on infertile women undergoing IVF treatment: A meta-analysis.

Science.gov (United States)

Li, Jie; Mo, Sien; Chen, Yang

2017-08-01

Evidence for the effect of granulocyte colony stimulating factor (G-CSF) on infertile women undergoing in vitro fertilization (IVF) remains inconsistent. This study aimed to evaluate the effectiveness of G-CSF on infertile women undergoing IVF. PubMed and EMBASE databases were searched before August 2016. Comparing the transvaginal perfusion of G-CSF and placebo or no treatment, the available studies were considered. The pooled risk ratio (RR) with 95% confidence intervals (CIs) was used in the analysis and six studies were included. Transvaginal perfusion of G-CSF was significantly associated with a higher clinical pregnancy rate versus the placebo (RR=1.563, 95%CI: 1.122, 2.176), especially for the Asian population. Among patients with a thin endometrium or repeated IVF failure, the implantation and biochemical pregnancy rates were also significantly increased in patients with the use of G-CSF (implantation rate: RR = 1.887, 95% CI: 1.256, 2.833; biochemical pregnancy rate: RR = 2.385, 95% CI: 1.414, 4.023). However, no statistical significance in increasing endometrial thickness was detected. Transvaginal perfusion of G-CSF for infertile women may play a critical role in assisting human reproduction, especially for patients with a thin endometrium or repeated IVF failure in the Asian population.

Blood volume measurement with indocyanine green pulse spectrophotometry: dose and site of dye administration

NARCIS (Netherlands)

Germans, Menno R.; de Witt Hamer, Philip C.; van Boven, Leonard J.; Zwinderman, Koos A. H.; Bouma, Gerrit J.

2010-01-01

(1) To determine the optimal administration site and dose of indocyanine green (ICG) for blood volume measurement using pulse spectrophotometry, (2) to assess the variation in repeated blood volume measurements for patients after subarachnoid hemorrhage and (3) to evaluate the safety and efficacy of

A microNewton thrust stand for average thrust measurement of pulsed microthruster.

Science.gov (United States)

Zhou, Wei-Jing; Hong, Yan-Ji; Chang, Hao

2013-12-01

A torsional thrust stand has been developed for the study of the average thrust for microNewton pulsed thrusters. The main body of the thrust stand mainly consists of a torsional balance, a pair of flexural pivots, a capacitive displacement sensor, a calibration assembly, and an eddy current damper. The behavior of the stand was thoroughly studied. The principle of thrust measurement was analyzed. The average thrust is determined as a function of the average equilibrium angle displacement of the balance and the spring stiffness. The thrust stand has a load capacity up to 10 kg, and it can theoretically measure the force up to 609.6 μN with a resolution of 24.4 nN. The static calibrations were performed based on the calibration assembly composed of the multiturn coil and the permanent magnet. The calibration results demonstrated good repeatability (less than 0.68% FSO) and good linearity (less than 0.88% FSO). The assembly of the multiturn coil and the permanent magnet was also used as an exciter to simulate the microthruster to further research the performance of the thrust stand. Three sets of force pulses at 17, 33.5, and 55 Hz with the same amplitude and pulse width were tested. The repeatability error at each frequency was 7.04%, 1.78%, and 5.08%, respectively.

Storage of multiple single-photon pulses emitted from a quantum dot in a solid-state quantum memory

Science.gov (United States)

Tang, Jian-Shun; Zhou, Zong-Quan; Wang, Yi-Tao; Li, Yu-Long; Liu, Xiao; Hua, Yi-Lin; Zou, Yang; Wang, Shuang; He, De-Yong; Chen, Geng; Sun, Yong-Nan; Yu, Ying; Li, Mi-Feng; Zha, Guo-Wei; Ni, Hai-Qiao; Niu, Zhi-Chuan; Li, Chuan-Feng; Guo, Guang-Can

2015-01-01

Quantum repeaters are critical components for distributing entanglement over long distances in presence of unavoidable optical losses during transmission. Stimulated by the Duan–Lukin–Cirac–Zoller protocol, many improved quantum repeater protocols based on quantum memories have been proposed, which commonly focus on the entanglement-distribution rate. Among these protocols, the elimination of multiple photons (or multiple photon-pairs) and the use of multimode quantum memory are demonstrated to have the ability to greatly improve the entanglement-distribution rate. Here, we demonstrate the storage of deterministic single photons emitted from a quantum dot in a polarization-maintaining solid-state quantum memory; in addition, multi-temporal-mode memory with 1, 20 and 100 narrow single-photon pulses is also demonstrated. Multi-photons are eliminated, and only one photon at most is contained in each pulse. Moreover, the solid-state properties of both sub-systems make this configuration more stable and easier to be scalable. Our work will be helpful in the construction of efficient quantum repeaters based on all-solid-state devices. PMID:26468996

Impact of multimodal preoperative preparation program on children undergoing surgery

Directory of Open Access Journals (Sweden)

Priya Reshma Aranha

2017-01-01

Full Text Available Background: The advanced era of technological development in child health care has resulted in more pediatric procedures being performed in various settings. Millions of children undergo surgery every year which is a stressful event. Many nonpharmacological strategies are being used to manage the preoperative fear and anxiety in children. The current study aims to assess the effectiveness of multimodal preoperative preparation program (MPPP on children undergoing surgery in terms of its effect on the psychophysiological parameters. Objective: The aim of this study is to assess the effectiveness of MPPP on the psychophysiological parameters of children undergoing surgery. Materials and Methods: A quasi-experimental study was conducted in a selected multi-specialty hospital. Using the purposive sampling technique, a total of 110 children aged 8–12 years were assigned to nonintervention (n = 55 and intervention (n = 55 groups, respectively. The MPPP was administered to the intervention group. The children in the nonintervention group received the routine preoperative care. Child's fear and anxiety was assessed on admission, prior to shifting the child to operation theater (OT, 24 and 48 h after surgery, whereas child's pulse, respiration, blood pressure (BP, and oxygen saturation was assessed on admission, prior to shifting the child to OT, 6, 12, 24, and 48 h after surgery and pain was assessed at 24 and 48 h after surgery. Results: The mean fear and anxiety scores of children were significantly lower in the intervention group than that of nonintervention group (P 0.05. This study also found that there is a significant association between the psychophysiological parameters of children with the selected demographic variables (P < 0.05. A positive correlation was found between the psychological and physiological parameters of children undergoing surgery. Conclusion: The MPPP is effective on psychophysiological parameters of children undergoing

Prospective, multi-institutional pain assessment of 150 women undergoing diagnostic cystoscopy.

Science.gov (United States)

Seklehner, Stephan; Saratlija-Novakovic, Zana; Skopek, Matthias; Fajkovic, Harun; Remzi, Mesut; Duvnjak, Mario; Resch, Irene; Hruby, Stephan; lmHÜBNER, Wilhelm; Librenjak, Davor; Breinl, Eckart; Riedl, Claus; Engelhardt, Paul F

2016-10-01

The aim of this study was to prospectively assess women's pain during rigid and flexible diagnostic cystoscopy and afterwards during a one-week follow-up. Prospective, multi-institutional trial analyzing numeric rating scales (NRS) of women undergoing diagnostic cystoscopy. Pain categories: no (0 points), mild (1-3), moderate (4-6) and severe pain (7-10). Assessing of pain before, during cystoscopy, and at day 1, 4 and 7 of follow-up. A total of 150 women undergoing rigid (N.=85) or flexible (N.=65) diagnostic cystoscopy were analyzed. Women undergoing flexible cystoscopy were more frequently pain-free (64.6% vs. 40%, P=0.003) and experienced mild pain less frequently (27.7% vs. 52.9% vs. P=0.002). No significant differences were noted among moderate (6.2% vs. 5.9%, P=0.95) and severe pain (1.5% vs. 1.2%, P=0.85). Patients undergoing their first (P=0.14) and repeat cystoscopy (P=0.08) had similar pain perception. In multivariate logistic regression analyses, women undergoing flexible cystoscopy had a 2.6 increased chance of being pain-free (OR=2.6, CI: 1.28-5.11, P=0.08) and their odds of experiencing mild pain were significantly lower (OR=0.34, CI: 0.17-0.71, P=0.004). The likelihood of experiencing moderate (OR=1.1, CI: 0.28- 4.4, P=0.83) or severe pain (OR=2.42, CI: 0.11-51.79, P=0.57) differed insignificantly. Rigid and flexible cystoscopies were well-tolerated by most women. However, flexible cystoscopy was associated with a higher likelihood of being pain-free and lower chances of experiencing mild pain. Patients' previous experience with cystoscopy did not influence pain perception.

Repeated vertebral augmentation for new vertebral compression fractures of postvertebral augmentation patients: a nationwide cohort study

Directory of Open Access Journals (Sweden)

Liang CL

2015-03-01

Full Text Available Cheng-Loong Liang,1 Hao-Kwan Wang,1 Fei-Kai Syu,2 Kuo-Wei Wang,1 Kang Lu,1 Po-Chou Liliang1 1Department of Neurosurgery, E-Da Hospital, I-Shou University, Kaohsiung City, Taiwan; 2Department of Pharmacy, China Medical University Hospital, Taichung City, Taiwan Purpose: Postvertebral augmentation vertebral compression fractures are common; repeated vertebral augmentation is usually performed for prompt pain relief. This study aimed to evaluate the incidence and risk factors of repeat vertebral augmentation.Methods: We performed a retrospective, nationwide, population-based longitudinal observation study, using the National Health Insurance Research Database (NHIRD of Taiwan. All patients who received vertebral augmentation for vertebral compression fractures were evaluated. The collected data included patient characteristics (demographics, comorbidities, and medication exposure and repeat vertebral augmentation. Kaplan–Meier and stratified Cox proportional hazard regressions were performed for analyses.Results: The overall incidence of repeat vertebral augmentation was 11.3% during the follow-up until 2010. Patients with the following characteristics were at greater risk for repeat vertebral augmentation: female sex (AOR=1.24; 95% confidence interval [CI]: 1.10–2.36, advanced age (AOR=1.60; 95% CI: 1.32–2.08, diabetes mellitus (AOR=4.31; 95% CI: 4.05–5.88, cerebrovascular disease (AOR=4.09; 95% CI: 3.44–5.76, dementia (AOR=1.97; 95% CI: 1.69–2.33, blindness or low vision (AOR=3.72; 95% CI: 2.32–3.95, hypertension (AOR=2.58; 95% CI: 2.35–3.47, and hyperlipidemia (AOR=2.09; 95% CI: 1.67–2.22. Patients taking calcium/ vitamin D (AOR=2.98; 95% CI: 1.83–3.93, bisphosphonates (AOR=2.11; 95% CI: 1.26–2.61, or calcitonin (AOR=4.59; 95% CI: 3.40–5.77 were less likely to undergo repeat vertebral augmentation; however, those taking steroids (AOR=7.28; 95% CI: 6.32–8.08, acetaminophen (AOR=3.54; 95% CI: 2.75–4.83, or nonsteroidal

Towards optimized suppression of dephasing in systems subject to pulse timing constraints

International Nuclear Information System (INIS)

Hodgson, Thomas E.; D'Amico, Irene; Viola, Lorenza

2010-01-01

We investigate the effectiveness of different dynamical decoupling protocols for storage of a single qubit in the presence of a purely dephasing bosonic bath, with emphasis on comparing quantum coherence preservation under uniform versus nonuniform delay times between pulses. In the limit of instantaneous bit-flip pulses, this is accomplished by establishing a different representation of the controlled qubit evolution, where the decoherence behavior after an arbitrary number of pulses is directly expressed in terms of the uncontrolled decoherence function. In particular, analytical expressions are obtained for approximation of the long- and short-term coherence behavior for both Ohmic and supra-Ohmic environments. By focusing on the realistic case of pure dephasing in an excitonic qubit, we quantitatively assess the impact of physical constraints on achievable pulse separations, and show that little advantage of high-level decoupling schemes based on concatenated or optimal design may be expected if pulses cannot be applied sufficiently fast. In such constrained scenarios, we demonstrate how simple modifications of repeated periodic-echo protocols can offer significantly improved coherence preservation in realistic parameter regimes. We expect similar conclusions to be relevant to other constrained qubit devices exposed to quantum or classical phase noise.

Ability of the Masimo pulse CO-Oximeter to detect changes in hemoglobin.

Science.gov (United States)

Colquhoun, Douglas A; Forkin, Katherine T; Durieux, Marcel E; Thiele, Robert H

2012-04-01

The decision to administer blood products is complex and multifactorial. Accurate assessment of the concentration of hemoglobin [Hgb] is a key component of this evaluation. Recently a noninvasive method of continuously measuring hemoglobin (SpHb) has become available with multi-wavelength Pulse CO-Oximetry. The accuracy of this device is well documented, but the trending ability of this monitor has not been previously described. Twenty patients undergoing major thoracic and lumbar spine surgery were recruited. All patients received radial arterial lines. On the contralateral index finger, a R1 25 sensor (Rev E) was applied and connected to a Radical-7 Pulse CO-Oximeter (both Masimo Corp, Irvine, CA). Blood samples were drawn intermittently at the anesthesia provider's discretion and were analyzed by the operating room satellite laboratory CO-Oximeter. The value of Hgb and SpHb at that time point was compared. Trend analysis was performed by the four quadrant plot technique, testing directionality of change, and Critchley's polar plot method testing both directionality and magnitude of the change in values. Eighty-eight samples recorded at times of sufficient signal quality were available for analysis. Four quadrant plot analysis revealed 94% of data within the quadrants associated with the correct direction change, and 90% of data points lay within the analysis bounds proposed by Critchley. Pulse CO-Oximetry offers an acceptable trend monitor in patients undergoing major spine surgery. Future work should explore the ability of this device to detect large changes in hemoglobin, as well as its applicability in additional surgical and non-surgical patient populations.

Pulse pile-up. I: Short pulses

International Nuclear Information System (INIS)

Wilkinson, D.H.

1990-07-01

The search for rare large pulses against an intense background of smaller ones involves consideration of pulse pile-up. Approximate methods are presented, based on ruin theory, by which the probability of such pile-up may be estimated for pulses of arbitrary form and of arbitrary pulse-height distribution. These methods are checked against cases for which exact solutions are available. The present paper is concerned chiefly with short pulses of finite total duration. (Author) (5 refs., 24 figs.)

Heart failure re-admission: measuring the ever shortening gap between repeat heart failure hospitalizations.

Directory of Open Access Journals (Sweden)

Jeffrey A Bakal

Full Text Available Many quality-of-care and risk prediction metrics rely on time to first rehospitalization even though heart failure (HF patients may undergo several repeat hospitalizations. The aim of this study is to compare repeat hospitalization models. Using a population-based cohort of 40,667 patients, we examined both HF and all cause re-hospitalizations using up to five years of follow-up. Two models were examined: the gap-time model which estimates the adjusted time between hospitalizations and a multistate model which considered patients to be in one of four states; community-dwelling, in hospital for HF, in hospital for any reason, or dead. The transition probabilities and times were then modeled using patient characteristics and number of repeat hospitalizations. We found that during the five years of follow-up roughly half of the patients returned for a subsequent hospitalization for each repeat hospitalization. Additionally, we noted that the unadjusted time between hospitalizations was reduced ∼40% between each successive hospitalization. After adjustment each additional hospitalization was associated with a 28 day (95% CI: 22-35 reduction in time spent out of hospital. A similar pattern was seen when considering the four state model. A large proportion of patients had multiple repeat hospitalizations. Extending the gap between hospitalizations should be an important goal of treatment evaluation.

Impaired intracortical transmission in G2019S leucine rich-repeat kinase Parkinson patients.

Science.gov (United States)

Ponzo, Viviana; Di Lorenzo, Francesco; Brusa, Livia; Schirinzi, Tommaso; Battistini, Stefania; Ricci, Claudia; Sambucci, Manolo; Caltagirone, Carlo; Koch, Giacomo

2017-05-01

A mutation in leucine-rich repeat kinase 2 is the most common cause of hereditary Parkinson's disease (PD), yet the neural mechanisms and the circuitry potentially involved are poorly understood. We used different transcranial magnetic stimulation protocols to explore in the primary motor cortex the activity of intracortical circuits and cortical plasticity (long-term potentiation) in patients with the G2019S leucine-rich repeat kinase 2 gene mutation when compared with idiopathic PD patients and age-matched healthy subjects. Paired pulse transcranial magnetic stimulation was used to investigate short intracortical inhibition and facilitation and short afferent inhibition. Intermittent theta burst stimulation, a form of repetitive transcranial magnetic stimulation, was used to test long-term potentiation-like cortical plasticity. Leucine-rich repeat kinase 2 and idiopathic PD were tested both in ON and in OFF l-dopa therapy. When compared with idiopathic PD and healthy subjects, leucine-rich repeat kinase 2 PD patients showed a remarkable reduction of short intracortical inhibition in both ON and in OFF l-dopa therapy. This reduction was paralleled by an increase of intracortical facilitation in OFF l-dopa therapy. Leucine-rich repeat kinase 2 PD showed abnormal long-term potentiation-like cortical plasticity in ON l-dopa therapy. The motor cortex in leucine-rich repeat kinase 2 mutated PD patients is strongly disinhibited and hyperexcitable. These abnormalities could be a result of an impairment of inhibitory (gamma-Aminobutyric acid) transmission eventually related to altered neurotransmitter release. © 2017 International Parkinson and Movement Disorder Society. © 2017 International Parkinson and Movement Disorder Society.

Ultrasonic detection of spall damage nucleation under low-velocity repeated impact

Directory of Open Access Journals (Sweden)

Watanabe T.

2012-08-01

Full Text Available Repeated plate impact testing with impact stress well below the threshold spall-stress (2.6 GPa on medium carbon steel was carried out to the identical target plate by impacting the flyer plate. Occurrence of spall damage under low-velocity repeated impact was evaluated nondestructively with a low frequency scanning acoustic microscope. We observed the spall damage distribution by the B- and C-scan images. In order to initiate the spall damage (voids in a ductile material or cracks in a brittle one the particular value of threshold spall-stress should be exceeded what already belongs to a commonly accepted knowledge. Generally, the spall damage development is dependent on the amplitude and the duration of the stress pulse. If the stress is high and duration is long enough to create tensile failure of material, the voids or cracks nucleate along the spall plane, and consequently, they form macrocracks. Therefore, the spall damage does not create when the first impact stress is less than the threshold spall-stress. However, after the fifth low-velocity repeated impact test, the generation of the spall damage was detected, even if the impact stress (1.1–1.7 GPa was lower than the threshold spall-stress (2.6 GPa.

Effects of pulse duration on magnetostimulation thresholds

International Nuclear Information System (INIS)

Saritas, Emine U.; Goodwill, Patrick W.; Conolly, Steven M.

2015-01-01

Purpose: Medical imaging techniques such as magnetic resonance imaging and magnetic particle imaging (MPI) utilize time-varying magnetic fields that are subject to magnetostimulation limits, which often limit the speed of the imaging process. Various human-subject experiments have studied the amplitude and frequency dependence of these thresholds for gradient or homogeneous magnetic fields. Another contributing factor was shown to be number of cycles in a magnetic pulse, where the thresholds decreased with longer pulses. The latter result was demonstrated on two subjects only, at a single frequency of 1.27 kHz. Hence, whether the observed effect was due to the number of cycles or due to the pulse duration was not specified. In addition, a gradient-type field was utilized; hence, whether the same phenomenon applies to homogeneous magnetic fields remained unknown. Here, the authors investigate the pulse duration dependence of magnetostimulation limits for a 20-fold range of frequencies using homogeneous magnetic fields, such as the ones used for the drive field in MPI. Methods: Magnetostimulation thresholds were measured in the arms of six healthy subjects (age: 27 ± 5 yr). Each experiment comprised testing the thresholds at eight different pulse durations between 2 and 125 ms at a single frequency, which took approximately 30–40 min/subject. A total of 34 experiments were performed at three different frequencies: 1.2, 5.7, and 25.5 kHz. A solenoid coil providing homogeneous magnetic field was used to induce stimulation, and the field amplitude was measured in real time. A pre-emphasis based pulse shaping method was employed to accurately control the pulse durations. Subjects reported stimulation via a mouse click whenever they felt a twitching/tingling sensation. A sigmoid function was fitted to the subject responses to find the threshold at a specific frequency and duration, and the whole procedure was repeated at all relevant frequencies and pulse durations

Realtime aspects of pulse-to-pulse modulation

International Nuclear Information System (INIS)

Steiner, R.; Riedel, C.; Roesch, W.

1992-01-01

The pulse-to-pulse modulation of the SIS-ESR control system is described. Fast response to operator interaction and to changes in process conditions is emphasized as well as the essential part played by the timing system in pulse-to-pulse modulation. (author)

Summary of Altitude Pulse Testing of a 100-lbf L02/LCH4 Reaction Control Engine

Science.gov (United States)

Marshall, William M.; Kleinhenz, Julie E.

2011-01-01

Recently, liquid oxygen-liquid methane (LO2/LCH4) has been considered as a potential "green" propellant alternative for future exploration missions. The Propulsion and Cryogenic Advanced Development (PCAD) project has been tasked by NASA to develop this propulsion combination to enable safe and cost effective exploration missions. To date, limited experience with such combinations exist, and as a result a comprehensive test program is critical to demonstrating the viability of implementing such a system. The NASA Glenn Research Center has conducted a test program of a 100-lbf (445-N) reaction control engine (RCE) at the center s Altitude Combustion Stand (ACS), focusing on altitude testing over a wide variety of operational conditions. The ACS facility includes a unique propellant conditioning feed system (PCFS) which allows precise control of propellant inlet conditions to the engine. Engine performance as a result of these inlet conditions was examined extensively during the test program. This paper is a companion to the previous specific impulse testing paper, and discusses the pulsed mode operation portion of testing, with a focus on minimum impulse bit (I-bit) and repeatable pulse performance. The engine successfully demonstrated target minimum impulse bit performance at all conditions, as well as successful demonstration of repeatable pulse widths. Some anomalous conditions experienced during testing are also discussed, including a double pulse phenomenon which was not noted in previous test programs for this engine.

Radiation therapy for renal transplant rejection refractory to pulse steroids and OKT3

International Nuclear Information System (INIS)

Noyes, William R.; Rodriguez, Rey; Knechtle, Stuart J.; Pirsch, John D.; Sollinger, Hans W.; D'Alessandro, Anthony M.; Chappell, Rick; Belzer, Folkert O.; Kinsella, Timothy J.

1996-01-01

Purpose: To determine the response rate and kidney graft survival following local irradiation to the transplanted renal graft undergoing persistent rejection after medical management including pulse steroids and OKT3. The role of radiation for renal transplant rejection after failure of OKT3 has not been previously reported. Methods and Materials: From July 1, 1988 to July 1, 1994, 72 consecutive patients with kidney graft rejection were treated with local irradiation to the transplanted renal graft following failure of medical management. All patients received pulse steroids and OKT3, an anti-CD3 immunosuppressant. Patients who failed to respond to methylprednisolone and OKT3 therapy were referred for radiation therapy. The median time from the diagnosis of rejection to irradiation was 8 days. All kidney grafts received local graft irradiation to a total of 8 Gy delivered in four daily fractions. Results: Sixty (83%) patients initially responded to radiotherapy at 7 days after completion of radiotherapy, as defined by a decrease in serum creatinine. Thirty-five responding patients have not experienced a second episode of graft rejection. Overall, 43 (60%) patients have renal graft survival, with a median follow-up of 16 months (range of 6-73 months). Conclusion: It is concluded that there is a subgroup of kidney graft patients undergoing graft rejection who are refractory to pulse steroids and OKT3 therapy where irradiation may be an effective modality with high rates of response and a moderate rate of graft survival. However, a prospective, randomized trial in these medically refractory patients is needed to ascertain whether these results are clinically significant

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

Energy Technology Data Exchange (ETDEWEB)

Yee, J.P.

1979-01-01

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

Comparison of pain scores between patients undergoing panretinal photocoagulation using navigated or pattern scan laser systems

Directory of Open Access Journals (Sweden)

Umit Ubeyt Inan

2016-02-01

Full Text Available ABSTRACT Purpose: To compare the pain responses of patients with proliferative diabetic retinopathy (PDR undergoing panretinal photocoagulation (PRP using either pattern scan laser (PASCAL or navigated laser photocoagulation (NAVILAS. Methods: Patients diagnosed with PDR were randomly assigned to undergo either PASCAL or NAVILAS photocoagulation treatment. PRP was performed using the multi-shot mode with a spot size of 200-400 µm and a pulse duration of 30 ms to obtain a white-grayish spot on the retina. Parameters were identical in both procedures. After 30 min of PRP application, patients were asked to verbally describe their pain perception as either "none," "mild," "moderate," "severe," or "very severe" using a verbal rating scale (VRS and visual analog scale (VAS by indicating a score from "0" to "10," representing the severity of pain from "no pain" to "severe pain." Results: A total of 60 eyes of 60 patients (20 females and 40 males diagnosed with PDR were treated. The mean age of patients was 62.22 ± 9.19 years, and the mean diabetes duration was 195.47 ± 94.54 months. The mean number of laser spots delivered during PRP was 389.47 ± 71.52 in the NAVILAS group and 392.70 ± 54.33 in the PASCAL group (p=0.57. The difference in pain responses between patients in the NAVILAS and PASCAL groups was significant with regard to the mean VRS (1.10 ± 0.67 and 1.47 ± 0.69, respectively; p=0.042 and mean VAS (2.13 ± 1.17 and 2.97 ± 1.35, respectively; p=0.034 scores. Conclusions: Pain responses in patients undergoing PRP with a 30-ms pulse duration were significantly milder in the NAVILAS group than in the PASCAL group.

Pulsed rf excited spectrometer having improved pulse width control

International Nuclear Information System (INIS)

1977-01-01

RF excitation for a spectrometer is obtained by pulse width modulating an RF carrier to produce the desired broadband RF exciting spectrum. The RF excitation includes a train of composite RF pulses, each composite pulse having a primary pulse portion of a first RF phase and a second pulse portion of a second RF phase opposite that of the first. In this manner, the finite rise and fall times of the primary pulse portion are compensated for by the corresponding rise and fall times of the secondary pulse portion. The primary pulse portion is lengthened by an amount equal to the secondary pulse portion so that the secondary pulse portion cancels the added primary pulse portion. In a spectrometer, the compensating second pulse component removes certain undesired side bands of the RF excitation caused by the finite rise and fall times of the applied RF pulses. The compensating second pulse component removes certain undesired side bands associated with each of the resonant lines of the excited resonance spectrum of the sample under analysis, particularly for wide band RF excitation

Effects of pulse duration on magnetostimulation thresholds

Energy Technology Data Exchange (ETDEWEB)

Saritas, Emine U., E-mail: saritas@ee.bilkent.edu.tr [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Department of Electrical and Electronics Engineering, Bilkent University, Bilkent, Ankara 06800 (Turkey); National Magnetic Resonance Research Center (UMRAM), Bilkent University, Bilkent, Ankara 06800 (Turkey); Goodwill, Patrick W. [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Conolly, Steven M. [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Department of EECS, University of California, Berkeley, California 94720-1762 (United States)

2015-06-15

Purpose: Medical imaging techniques such as magnetic resonance imaging and magnetic particle imaging (MPI) utilize time-varying magnetic fields that are subject to magnetostimulation limits, which often limit the speed of the imaging process. Various human-subject experiments have studied the amplitude and frequency dependence of these thresholds for gradient or homogeneous magnetic fields. Another contributing factor was shown to be number of cycles in a magnetic pulse, where the thresholds decreased with longer pulses. The latter result was demonstrated on two subjects only, at a single frequency of 1.27 kHz. Hence, whether the observed effect was due to the number of cycles or due to the pulse duration was not specified. In addition, a gradient-type field was utilized; hence, whether the same phenomenon applies to homogeneous magnetic fields remained unknown. Here, the authors investigate the pulse duration dependence of magnetostimulation limits for a 20-fold range of frequencies using homogeneous magnetic fields, such as the ones used for the drive field in MPI. Methods: Magnetostimulation thresholds were measured in the arms of six healthy subjects (age: 27 ± 5 yr). Each experiment comprised testing the thresholds at eight different pulse durations between 2 and 125 ms at a single frequency, which took approximately 30–40 min/subject. A total of 34 experiments were performed at three different frequencies: 1.2, 5.7, and 25.5 kHz. A solenoid coil providing homogeneous magnetic field was used to induce stimulation, and the field amplitude was measured in real time. A pre-emphasis based pulse shaping method was employed to accurately control the pulse durations. Subjects reported stimulation via a mouse click whenever they felt a twitching/tingling sensation. A sigmoid function was fitted to the subject responses to find the threshold at a specific frequency and duration, and the whole procedure was repeated at all relevant frequencies and pulse durations

Process Control of Pre-Sowing Seed Treatment by Pulsed Electric Field

Directory of Open Access Journals (Sweden)

Starodubtseva Galina Petrovna

2018-03-01

Full Text Available Presented paper investigates the application of a line voltage changer to an installation for pre-sowing seed treatment by pulsed electric field (PEF in order to increase the sowing quality of seeds and to suppress pathogenic microflora. The installation comprises an AC voltage regulator, a high voltage source, a voltage inverter, a working chamber for seed treatment, a control unit, and current and voltage sensors. The proposed installation differs from the existing apparatuses as it automatically provides the transformation of the pulsed electric field parameters by constant monitoring of power processes in a layer of treated seeds and feedback sending to the control unit. Seed treatment efficiency depends on the dose being determined by the parameters of electric field, namely, intensity in the seed layer, pulse duration, pulse repetition frequency, and seed treatment time. The parameters of rational treatment were determined, and the minimum treatment dose was calculated on the basis of results from the laboratory tests on the effect of pulsed electric field on sowing qualities of winter wheat seeds. It was experimentally confirmed that the proposed installation provides automatic transformation of electric field parameters depending on the changes taking place in the seed layer on the example of seeds with different moisture content maintaining the necessary treatment dose, ensuring the stability and repeatability of results.

Peripheral i.v. analysis (PIVA) of venous waveforms for volume assessment in patients undergoing haemodialysis.

Science.gov (United States)

Hocking, K M; Alvis, B D; Baudenbacher, F; Boyer, R; Brophy, C M; Beer, I; Eagle, S

2017-12-01

The assessment of intravascular volume status remains a challenge for clinicians. Peripheral i.v. analysis (PIVA) is a method for analysing the peripheral venous waveform that has been used to monitor volume status. We present a proof-of-concept study for evaluating the efficacy of PIVA in detecting changes in fluid volume. We enrolled 37 hospitalized patients undergoing haemodialysis (HD) as a controlled model for intravascular volume loss. Respiratory rate (F0) and pulse rate (F1) frequencies were measured. PIVA signal was obtained by fast Fourier analysis of the venous waveform followed by weighing the magnitude of the amplitude of the pulse rate frequency. PIVA was compared with peripheral venous pressure and standard monitoring of vital signs. Regression analysis showed a linear correlation between volume loss and change in the PIVA signal (R2=0.77). Receiver operator curves demonstrated that the PIVA signal showed an area under the curve of 0.89 for detection of 20 ml kg-1 change in volume. There was no correlation between volume loss and peripheral venous pressure, blood pressure or pulse rate. PIVA-derived pulse rate and respiratory rate were consistent with similar numbers derived from the bio-impedance and electrical signals from the electrocardiogram. PIVA is a minimally invasive, novel modality for detecting changes in fluid volume status, respiratory rate and pulse rate in spontaneously breathing patients with peripheral i.v. cannulas. © The Author 2017. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Bipolar pulse generator for intense pulsed ion beam accelerator

International Nuclear Information System (INIS)

Ito, H.; Igawa, K.; Kitamura, I.; Masugata, K.

2007-01-01

A new type of pulsed ion beam accelerator named ''bipolar pulse accelerator'' (BPA) has been proposed in order to improve the purity of intense pulsed ion beams. To confirm the principle of the BPA, we developed a bipolar pulse generator for the bipolar pulse experiment, which consists of a Marx generator and a pulse forming line (PFL) with a rail gap switch on its end. In this article, we report the first experimental result of the bipolar pulse and evaluate the electrical characteristics of the bipolar pulse generator. When the bipolar pulse generator was operated at 70% of the full charge condition of the PFL, the bipolar pulse with the first (-138 kV, 72 ns) and the second pulse (+130 kV, 70 ns) was successfully obtained. The evaluation of the electrical characteristics indicates that the developed generator can produce the bipolar pulse with fast rise time and sharp reversing time

Sonographic evaluation of intra-abdominal adhesions during the third trimester of pregnancy: a novel technique in women undergoing repeated cesarean section.

Science.gov (United States)

Baron, Joel; Tirosh, Dan; Mastrolia, Salvatore Andrea; Ben-Haroush, Yigal; Schwartz, Shoshana; Kerner, Yoav; Hershkovitz, Reli

2018-03-25

Intra-abdominal adhesions may result in an increased risk of major complications in case of a repeated cesarean section, such as bladder and bowel injury, hemorrhage, infection, and hysterectomy. In an attempt to predict intra-abdominal adhesions before a repeated cesarean delivery, we suggest the use of a novel technique employing a simple and feasible ultrasound imaging technique. The study included pregnant women who underwent one or more cesarean deliveries in their obstetric history and were evaluated during the third trimester of the ongoing pregnancy. In order to diagnose intra-abdominal adhesions, we used a sonographic sliding sign of the uterus under the inner part of the fascia of the abdominal muscles, and considered women 1) at high risk for severe adhesions in the absence of sonographic uterine sliding; or 2) at a low risk for severe adhesions in the presence of an obvious or moderate uterine sliding. A comparison between sonographic findings and intra-abdominal adhesions as evaluated by the surgeons during surgery was performed. We examined 63 patients with one or more previous cesarean delivery. Out of these 63 patients, 59 had completed the study and underwent repeated cesarean section at our Institution. In 16 out of the19 cases assigned to the high risk for severe adhesions group, the suspicion was confirmed at surgery, with a sensitivity of 76.2%. In addition, the suspicion for low risk for adhesions was confirmed in 35 out of 40 patients, with a specificity of 92.1%. The inter and intra-observer correlation using Cohen's Kappa (k) coefficient were 0.52 and 0.77 respectively. Our data show that a simple sonographic sign might predict both high and low risk for intra-abdominal adhesions in patients who underwent previous cesarean delivery. This technique may aid clinical decisions regarding repeated cesarean section approach. This article is protected by copyright. All rights reserved.

Separation and determination of alditols and sugars by high-pH anion-exchange chromatography with pulsed amperometric detection

DEFF Research Database (Denmark)

Andersen, Rikke; Sørensen, A.

2000-01-01

Carbohydrates such as alditols (polyols or sugar alcohols), monosaccharides and disaccharides are separated as anions by anion-exchange chromatography with a sodium hydroxide eluent, MA1 CarboPac column and pulsed amperometric detection. We report a high-pH anion-exchange chromatographic-pulsed a......Carbohydrates such as alditols (polyols or sugar alcohols), monosaccharides and disaccharides are separated as anions by anion-exchange chromatography with a sodium hydroxide eluent, MA1 CarboPac column and pulsed amperometric detection. We report a high-pH anion-exchange chromatographic......-pulsed amperometric detection (HPAEC-PAD) method that determines all the polyols used as food additives in food products and the most commonly found mono- and disaccharides on a routine basis. The linearity, repeatability, internal reproducibility and accuracy are described. The applicability of the method has been...

Imaging Macromolecules with X-ray laser pulses

CERN Multimedia

CERN. Geneva

2017-01-01

The short wavelength of X-rays allows us to resolve atoms, but in practise for biological materials the achievable resolution is limited by the destruction of the sample by the radiation that forms the image.  For over 100 years, the workaround to this problem of radiation damage has been to average signals from repeating copies of the object arranged in a large crystal.  It is now possible to overcome damage limits by using intense X-ray pulses that vaporise the sample, but which are short enough in duration to freeze any motion of the sample on the atomic scale.  With the advent of X-ray FELs we have been able to confirm this principle, and are now applying it to overcoming a major bottleneck for protein crystallography, which is the need for large well-diffracting crystals.  The intense pulses also open up opportunities to help solve the crystallographic phase problem.  In particular we have found that commonly-occurring disordered crystals that are usually not ...

Measurement of Ultra-Short Solitary Electromagnetic Pulses

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Eva Gescheidtova

2004-01-01

Full Text Available In connection with the events of the last few years and with the increased number of terrorist activities, the problem of identification and measurement of electromagnetic weapons or other systems impact occurred. Among these are also microwave sources, which can reach extensive peak power of up to Pmax = 100 MW. Solitary, in some cases several times repeated, impulses lasting from tp E <1, 60>ns, cause the destruction of semiconductor junctions. These days we can find scarcely no human activity, where semiconductor structures are not used. The problem of security support of the air traffic, transportation, computer nets, banks, national strategic data canter’s, and other applications crops up. Several types of system protection from the ultra-short electromagnetic pulses present itself, passive and active protection. The analysis of the possible measuring methods, convenient for the identification and measurement of the ultra-short solitary electromagnetic pulses in presented in this paper; some of the methods were chosen and used for practical measurement. This work is part of Research object MSM262200022 "Research of microelectronic systems".

Effect of second harmonic in pulse-width-modulation-based DAC for feedback of digital fluxgate magnetometer

Science.gov (United States)

Belyayev, Serhiy; Ivchenko, Nickolay

2018-04-01

Digital fluxgate magnetometers employ processing of the measured pickup signal to produce the value of the compensation current. Using pulse-width modulation with filtering for digital to analog conversion is a convenient approach, but it can introduce an intrinsic source of nonlinearity, which we discuss in this design note. A code shift of one least significant bit changes the second harmonic content of the pulse train, which feeds into the pick-up signal chain despite the heavy filtering. This effect produces a code-dependent nonlinearity. This nonlinearity can be overcome by the specific design of the timing of the pulse train signal. The second harmonic is suppressed if the first and third quarters of the excitation period pulse train are repeated in the second and fourth quarters. We demonstrate this principle on a digital magnetometer, achieving a magnetometer noise level corresponding to that of the sensor itself.

UPPER LIMITS ON PULSED RADIO EMISSION FROM THE 6.85 s X-RAY PULSAR XTE J0103-728 IN THE SMALL MAGELLANIC CLOUD

International Nuclear Information System (INIS)

Crawford, Fronefield; Devour, Brian M.; Takacs, Brian P.; Lorimer, Duncan R.; Kondratiev, Vladislav I.

2009-01-01

X-ray pulsations with a 6.85 s period were recently detected in the Small Magellanic Cloud (SMC) and were subsequently identified as originating from the Be/X-ray binary system XTE J0103-728. The recent localization of the source of the X-ray emission has made a targeted search for radio pulsations from this source possible. The detection of pulsed radio emission from XTE J0103-728 would make it only the second system after PSR B1259-63 that is both a Be/X-ray binary and a radio pulsar. We observed XTE J0103-728 in 2008 February with the Parkes 64 m radio telescope soon after the identification of the source of X-ray pulsations was reported in order to search for corresponding radio pulsations. We used a continuous 6.4 hr observation with a 256 MHz bandwidth centered at 1390 MHz using the center beam of the Parkes multibeam receiver. In the subsequent data analysis, which included a folding search, a Fourier search, a fast-folding algorithm search, and a single pulse search, no pulsed signals were found for trial dispersion measures (DMs) between 0 and 800 pc cm -3 . This DM range easily encompasses the expected values for sources in the SMC. We place an upper limit of ∼45 mJy kpc 2 on the luminosity of periodic radio emission from XTE J0103-728 at the epoch of our observation, and we compare this limit to a range of luminosities measured for PSR B1259-63, the only Be/X-ray binary currently known to emit radio pulses. We also compare our limit to the radio luminosities of neutron stars having similarly long spin periods to XTE J0103-728. Since the radio pulses from PSR B1259-63 are eclipsed and undetectable during the portion of the orbit near periastron, repeated additional radio search observations of XTE J0103-728 may be valuable if it is undergoing similar eclipsing and if such observations are able to sample the orbital phase of this system well.

On pulse vaccine strategy in a periodic stochastic SIR epidemic model

International Nuclear Information System (INIS)

Wang, Fengyan; Wang, Xiaoyi; Zhang, Shuwen; Ding, Changming

2014-01-01

A periodic stochastic SIR epidemic model with pulse vaccination is studied. The system has global positive solutions and under some conditions it admits a unique positive periodic disease-free solution, which is globally exponentially stable in mean square. The mathematical expectation and variance of the positive periodic solution are obtained. Two threshold parameters R 1 and R 2 (R 1 >R 2 ) are identified; if R 1 <1, the susceptible will be persistent in the mean and the disease will go to extinction; if R 2 >1, the susceptible and the disease will be weakly persistent in the mean. We show that by repeatedly vaccinating the susceptible population in series of pulses, it is possible to eradicate the infective from the entire model population in the random environment

Pulse on pulse: modulation and signification in Rafael Lozano-Hemmer's Pulse Room

Directory of Open Access Journals (Sweden)

Merete Carlson

2012-06-01

Full Text Available This article investigates the relation between signifying processes and non-signifying material dynamism in the installation Pulse Room (2006 by Mexican Canadian artist Rafael Lozano-Hemmer. In Pulse Room the sense of pulse is ambiguous. Biorhythms are transmitted from the pulsing energy of the visitor's beating heart to the flashing of a fragile light bulb, thereby transforming each light bulb into a register of individual life. But at the same time the flashing light bulbs together produce a chaotically flickering light environment composed by various layers of repetitive rhythms, a vibrant and pulsating “room”. Hence, the visitor in Pulse Room is invited into a complex scenario that continuously oscillates between various aspects of signification (the light bulbs representing individual lives; the pulse itself as the symbolic “rhythm of life” and instants of pure material processuality (flickering light bulbs; polyrhythmic layers. Taking our point of departure in a discussion of Gilles Deleuze's concepts of modulation and signaletic material in relation to electronic media, we examine how the complex orchestration of pulsation between signification and material modulation produces a multilayered sense of time and space that is central to the sensory experience of Pulse Room as a whole. Pulse Room is, at the very same time, a relational subject–object intimacy and an all-encompassing immersive environment modulating continuously in real space-time.

Luteal blood flow in patients undergoing GnRH agonist long protocol

Directory of Open Access Journals (Sweden)

Takasaki Akihisa

2011-01-01

Full Text Available Abstract Background Blood flow in the corpus luteum (CL is closely related to luteal function. It is unclear how luteal blood flow is regulated. Standardized ovarian-stimulation protocol with a gonadotropin-releasing hormone agonist (GnRHa long protocol causes luteal phase defect because it drastically suppresses serum LH levels. Examining luteal blood flow in the patient undergoing GnRHa long protocol may be useful to know whether luteal blood flow is regulated by LH. Methods Twenty-four infertile women undergoing GnRHa long protocol were divided into 3 groups dependent on luteal supports; 9 women were given ethinylestradiol plus norgestrel (Planovar orally throughout the luteal phase (control group; 8 women were given HCG 2,000 IU on days 2 and 4 day after ovulation induction in addition to Planovar (HCG group; 7 women were given vitamin E (600 mg/day orally throughout the luteal phase in addition to Planovar (vitamin E group. Blood flow impedance was measured in each CL during the mid-luteal phase by transvaginal color-pulsed-Doppler-ultrasonography and was expressed as a CL-resistance index (CL-RI. Results Serum LH levels were remarkably suppressed in all the groups. CL-RI in the control group was more than the cutoff value (0.51, and only 2 out of 9 women had CL-RI values Conclusion Patients undergoing GnRHa long protocol had high luteal blood flow impedance with very low serum LH levels. HCG administration improved luteal blood flow impedance. This suggests that luteal blood flow is regulated by LH.

Pulse radiolysis study of the reduction mechanism of an antitumor antibiotic, mitomycin C

International Nuclear Information System (INIS)

Machtalere, G.; Houee-Levin, C.; Gardes-Albert, M.; Ferradini, C.; Hickel, B.

1988-01-01

Mitomycin C is a quinonic antitumor metabolized in vivo by one-electron reduction. We have studied the mechanism of the one-electron reduction of this drug by pulse radiolysis using C00 .- free radicals as reductants. Semiquinonic and hydroquinonic intermediates are formed. The hydroquinonic form undergoes a methanol elimination leading to a transient which can disappear in one of two ways: by either internal redox reaction or hydrolysis of the aziridine. 17 refs [fr

Measurement of Aortic Pulse Wave Velocity With a Connected Bathroom Scale.

Science.gov (United States)

Campo, David; Khettab, Hakim; Yu, Roger; Genain, Nicolas; Edouard, Paul; Buard, Nadine; Boutouyrie, Pierre

2017-09-01

Measurement of arterial stiffness should be more available. Our aim was to show that aortic pulse wave velocity can be reliably measured with a bathroom scale combining the principles of ballistocardiography (BCG) and impedance plethysmography on a single foot. The calibration of the bathroom scale was conducted on a group of 106 individuals. The aortic pulse wave velocity was measured with the SphygmoCor in the supine position. Three consecutive measurements were then performed on the Withings scale in the standing position. This aorta-leg pulse transit time (alPTT) was then converted into a velocity with the additional input of the height of the person. Agreement between the SphygmoCor and the bathroom scale so calibrated is assessed on a separate group of 86 individuals, following the same protocol. The bias is 0.25 m·s-1 and the SE 1.39 m·s-1. This agreement with Sphygmocor is "acceptable" according to the ARTERY classification. The alPTT correlated well with cfPTT with (Spearman) R = 0.73 in pooled population (cal 0.79, val 0.66). The aorta-leg pulse wave velocity correlated with carotid-femoral pulse wave velocity with R = 0.76 (cal 0.80, val 0.70). Estimation of the aortic pulse wave velocity is feasible with a bathroom scale. Further investigations are needed to improve the repeatability of measurements and to test their accuracy in different populations and conditions. © The Author 2017. Published by Oxford University Press on behalf of American Journal of Hypertension.

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

International Nuclear Information System (INIS)

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

1987-01-01

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

A search for optical bursts from the repeating fast radio burst FRB 121102

Science.gov (United States)

Hardy, L. K.; Dhillon, V. S.; Spitler, L. G.; Littlefair, S. P.; Ashley, R. P.; De Cia, A.; Green, M. J.; Jaroenjittichai, P.; Keane, E. F.; Kerry, P.; Kramer, M.; Malesani, D.; Marsh, T. R.; Parsons, S. G.; Possenti, A.; Rattanasoon, S.; Sahman, D. I.

2017-12-01

We present a search for optical bursts from the repeating fast radio burst FRB 121102 using simultaneous observations with the high-speed optical camera ULTRASPEC on the 2.4-m Thai National Telescope and radio observations with the 100-m Effelsberg Radio Telescope. A total of 13 radio bursts were detected, but we found no evidence for corresponding optical bursts in our 70.7-ms frames. The 5σ upper limit to the optical flux density during our observations is 0.33 mJy at 767 nm. This gives an upper limit for the optical burst fluence of 0.046 Jy ms, which constrains the broad-band spectral index of the burst emission to α ≤ -0.2. Two of the radio pulses are separated by just 34 ms, which may represent an upper limit on a possible underlying periodicity (a rotation period typical of pulsars), or these pulses may have come from a single emission window that is a small fraction of a possible period.

Harmonic pulsed excitation and motion detection of a vibrating reflective target.

Science.gov (United States)

Urban, Matthew W; Greenleaf, James F

2008-01-01

Elasticity imaging is an emerging medical imaging modality. Methods involving acoustic radiation force excitation and pulse-echo ultrasound motion detection have been investigated to assess the mechanical response of tissue. In this work new methods for dynamic radiation force excitation and motion detection are presented. The theory and model for harmonic motion detection of a vibrating reflective target are presented. The model incorporates processing of radio frequency data acquired using pulse-echo ultrasound to measure harmonic motion with amplitudes ranging from 100 to 10,000 nm. A numerical study was performed to assess the effects of different parameters on the accuracy and precision of displacement amplitude and phase estimation and showed how estimation errors could be minimized. Harmonic pulsed excitation is introduced as a multifrequency radiation force excitation method that utilizes ultrasound tonebursts repeated at a rate f(r). The radiation force, consisting of frequency components at multiples of f(r), is generated using 3.0 MHz ultrasound, and motion detection is performed simultaneously with 9.0 MHz pulse-echo ultrasound. A parameterized experimental analysis showed that displacement can be measured with small errors for motion with amplitudes as low as 100 nm. The parameterized numerical and experimental analyses provide insight into how to optimize acquisition parameters to minimize measurement errors.

High-Repeatable Data Acquisition Systems for Pulsed Power Converters in Particle Accelerator Structures

CERN Document Server

AUTHOR|(CDS)2087245; Martino, Michele; Zinno, Raffaele

In this Ph.D. thesis, the issues related to the metrological characterization of high-performance pulsed power converters are addressed. Initially, a background and a state of the art on the measurement systems needed to correctly operate a high-performance power converter are presented. As a matter of fact, power converters usually exploits digital control loops to enhance their performance. In this context the final performance of a power converter has to be validated by a reference instrument with higher metrological characteristics. In addition, an on-line measurement systemis also needed to digitize the quantity to be controlled with high accuracy. Then, in industrial applications of power converters metrology, specifications are given in terms of Worst-Case Uncertainty (WCU). Therefore, an analytical model for predicting the Worst-Case Uncertainty (WCU) of a measurement system is discussed and detailed for an instrument affected by Gaussian noise. Furthermore, the study and the design of a Reference Acq...

Suppressing the memory state of floating gate transistors with repeated femtosecond laser backside irradiations

Science.gov (United States)

Chambonneau, Maxime; Souiki-Figuigui, Sarra; Chiquet, Philippe; Della Marca, Vincenzo; Postel-Pellerin, Jérémy; Canet, Pierre; Portal, Jean-Michel; Grojo, David

2017-04-01

We demonstrate that infrared femtosecond laser pulses with intensity above the two-photon ionization threshold of crystalline silicon induce charge transport through the tunnel oxide in floating gate Metal-Oxide-Semiconductor transistor devices. With repeated irradiations of Flash memory cells, we show how the laser-produced free-electrons naturally redistribute on both sides of the tunnel oxide until the electric field of the transistor is suppressed. This ability enables us to determine in a nondestructive, rapid and contactless way the flat band and the neutral threshold voltages of the tested device. The physical mechanisms including nonlinear ionization, quantum tunneling of free-carriers, and flattening of the band diagram are discussed for interpreting the experiments. The possibility to control the carriers in memory transistors with ultrashort pulses holds promises for fast and remote device analyses (reliability, security, and defectivity) and for considerable developments in the growing field of ultrafast microelectronics.

Post-annealing effects on pulsed laser deposition-grown GaN thin films

International Nuclear Information System (INIS)

Cheng, Yu-Wen; Wu, Hao-Yu; Lin, Yu-Zhong; Lee, Cheng-Che; Lin, Ching-Fuh

2015-01-01

In this work, the post-annealing effects on gallium nitride (GaN) thin films grown from pulsed laser deposition (PLD) are investigated. The as-deposited GaN thin films grown from PLD are annealed at different temperatures in nitrogen ambient. Significant changes of the GaN crystal properties are observed. Raman spectroscopy is used to observe the crystallinity, the change of residual stress, and the thermal decomposition of the annealed GaN thin films. X-ray diffraction is also applied to identify the crystal phase of GaN thin films, and the surface morphology of GaN thin films annealed at different temperatures is observed by scanning electron microscopy. Through the above analyses, the GaN thin films grown by PLD undergo three stages: phase transition, stress alteration, and thermal decomposition. At a low annealing temperature, the rock salt GaN in GaN films is transformed into wurtzite. The rock salt GaN diminishes with increasing annealing temperature. At a medium annealing temperature, the residual stress of the film changes significantly from compressive strain to tensile strain. As the annealing temperature further increases, the GaN undergoes thermal decomposition and the surface becomes granular. By investigating the annealing temperature effects and controlling the optimized annealing temperature of the GaN thin films, we are able to obtain highly crystalline and strain-free GaN thin films by PLD. - Highlights: • The GaN thin film is grown on sapphire by pulsed laser deposition. • The GaN film undergoes three stages with increasing annealing temperature. • In the first stage, the film transfers from rock salt to wurtzite phase. • In the second stage, the stress in film changes from compressive to tensile. • In the final stage, the film thermally decomposes and becomes granular

Femtosecond laser pulses for fast 3-D surface profilometry of microelectronic step-structures.

Science.gov (United States)

Joo, Woo-Deok; Kim, Seungman; Park, Jiyong; Lee, Keunwoo; Lee, Joohyung; Kim, Seungchul; Kim, Young-Jin; Kim, Seung-Woo

2013-07-01

Fast, precise 3-D measurement of discontinuous step-structures fabricated on microelectronic products is essential for quality assurance of semiconductor chips, flat panel displays, and photovoltaic cells. Optical surface profilers of low-coherence interferometry have long been used for the purpose, but the vertical scanning range and speed are limited by the micro-actuators available today. Besides, the lateral field-of-view extendable for a single measurement is restricted by the low spatial coherence of broadband light sources. Here, we cope with the limitations of the conventional low-coherence interferometer by exploiting unique characteristics of femtosecond laser pulses, i.e., low temporal but high spatial coherence. By scanning the pulse repetition rate with direct reference to the Rb atomic clock, step heights of ~69.6 μm are determined with a repeatability of 10.3 nm. The spatial coherence of femtosecond pulses provides a large field-of-view with superior visibility, allowing for a high volume measurement rate of ~24,000 mm3/s.

The APPLE Score - A Novel Score for the Prediction of Rhythm Outcomes after Repeat Catheter Ablation of Atrial Fibrillation.

Directory of Open Access Journals (Sweden)

Jelena Kornej

Full Text Available Arrhythmia recurrences after catheter ablation occur in up to 50% within one year but their prediction remains challenging. Recently, we developed a novel score for the prediction of rhythm outcomes after single AF ablation demonstrating superiority to other scores. The current study was performed to 1 prove the predictive value of the APPLE score in patients undergoing repeat AF ablation and 2 compare it with the CHADS2 and CHA2DS2-VASc scores.Rhythm outcome between 3-12 months after AF ablation were documented. The APPLE score (one point for Age >65 years, Persistent AF, imPaired eGFR (<60 ml/min/1.73m2, LA diameter ≥43 mm, EF <50% was calculated in every patient before procedure.379 consecutive patients from The Leipzig Heart Center AF Ablation Registry (60±10 years, 65% male, 70% paroxysmal AF undergoing repeat AF catheter ablation were included. Arrhythmia recurrences were observed in 133 patients (35%. While the CHADS2 (AUC 0.577, p = 0.037 and CHA2DS2-VASc scores (AUC 0.590, p = 0.015 demonstrated low predictive value, the APPLE score showed better prediction of arrhythmia recurrences (AUC 0.617, p = 0.002 than other scores (both p<0.001. Compared to patients with an APPLE score of 0, the risk (OR for arrhythmia recurrences was 2.9, 3.0 and 6.0 (all p<0.01 for APPLE scores 1, 2, or ≥3, respectively.The novel APPLE score is superior to the CHADS2 and CHA2DS2-VASc scores for prediction of rhythm outcomes after repeat AF catheter ablation. It may be helpful to identify patients with low, intermediate or high risk for recurrences after repeat procedure.

Repeating and non-repeating fast radio bursts from binary neutron star mergers

Science.gov (United States)

Yamasaki, Shotaro; Totani, Tomonori; Kiuchi, Kenta

2018-04-01

Most fast radio bursts (FRB) do not show evidence of repetition, and such non-repeating FRBs may be produced at the time of a merger of binary neutron stars (BNS), provided that the BNS merger rate is close to the high end of the currently possible range. However, the merger environment is polluted by dynamical ejecta, which may prohibit the radio signal from propagating. We examine this by using a general-relativistic simulation of a BNS merger, and show that the ejecta appears about 1 ms after the rotation speed of the merged star becomes the maximum. Therefore there is a time window in which an FRB signal can reach outside, and the short duration of non-repeating FRBs can be explained by screening after ejecta formation. A fraction of BNS mergers may leave a rapidly rotating and stable neutron star, and such objects may be the origin of repeating FRBs like FRB 121102. We show that a merger remnant would appear as a repeating FRB on a time scale of ˜1-10 yr, and expected properties are consistent with the observations of FRB 121102. We construct an FRB rate evolution model that includes these two populations of repeating and non-repeating FRBs from BNS mergers, and show that the detection rate of repeating FRBs relative to non-repeating ones rapidly increases with improving search sensitivity. This may explain why only the repeating FRB 121102 was discovered by the most sensitive FRB search with Arecibo. Several predictions are made, including the appearance of a repeating FRB 1-10 yr after a BNS merger that is localized by gravitational waves and subsequent electromagnetic radiation.

Kilohertz and Low-Frequency Electrical Stimulation With the Same Pulse Duration Have Similar Efficiency for Inducing Isometric Knee Extension Torque and Discomfort.

Science.gov (United States)

Medeiros, Flávia Vanessa; Bottaro, Martim; Vieira, Amilton; Lucas, Tiago Pires; Modesto, Karenina Arrais; Bo, Antonio Padilha L; Cipriano, Gerson; Babault, Nicolas; Durigan, João Luiz Quagliotti

2017-06-01

To test the hypotheses that, as compared with pulsed current with the same pulse duration, kilohertz frequency alternating current would not differ in terms of evoked-torque production and perceived discomfort, and as a result, it would show the same current efficiency. A repeated-measures design with 4 stimuli presented in random order was used to test 25 women: (1) 500-microsecond pulse duration, (2) 250-microsecond pulse duration, (3) 500-microsecond pulse duration and low carrier frequency (1 kHz), (4) 250-microsecond pulse duration and high carrier frequency (4 kHz). Isometric peak torque of quadriceps muscle was measured using an isokinetic dynamometer. Discomfort was measured using a visual analog scale. Currents with long pulse durations induced approximately 21% higher evoked torque than short pulse durations. In addition, currents with 500 microseconds delivered greater amounts of charge than stimulation patterns using 250-microsecond pulse durations (P torque and discomfort. However, neuromuscular electrical stimulation (NMES) with longer pulse duration induces higher NMES-evoked torque, regardless of the carrier frequency. Pulse duration is an important variable that should receive more attention for an optimal application of NMES in clinical settings.

Generation of stable Ps, mJ pulses at high repetition rate for ultrafast diagnostic experiments: Final report

International Nuclear Information System (INIS)

Mourou, G.

1986-10-01

Nd:Glass amplifiers have very good energy storage capabilities (5 J/cm 2 ), but, the energy extraction is extremely inefficient for short-pulse amplification. At relatively high peak intensities of ∼ 10 GW/cm 2 , nonlinear phase shifts occur, leading to beam wavefront distortion which can result in filamentation and irreversible damage. In order that the peak intensity in the amplifier remain below this damage level, a picosecond pulse can be amplified only to an energy density of ∼ 10 mJ/cm 2 , two orders of magnitude less than the stored energy level of 5 J/cm 2 . We have developed an amplification system, which uses an optical pulse compression technique to circumvent this peak power limitation. This technique is analogous to a method developed over forty years ago for the amplification of radar pulses. Briefly: a long optical pulse is deliberately produced by stretching a short, low-energy pulse, amplified and then compressed. The frequency chirp and the temporal broadening are produced by propagating a high-intensity pulse along a single-mode fiber. At the beginning of the fiber, the pulse undergoes self-phase modulation which produces a frequncy chirp. The chirp is then linearized by the group-velocity dispersion of the fiber. This long, frequency-chirped, pulse is amplified, and then compressed to a pulsewidth approximately equal to 1/Δf, where Δf is the chirped bandwidth. With this system, short pulses can reach the high saturation energy levels, with moderately low peak power levels being maintained in the amplifying medium

Determination of carbohydrates using pulsed amperometric detection combined with anion exchange separations

Energy Technology Data Exchange (ETDEWEB)

Edwards, W.T.; Pohl, C.A.; Rubin, R.

1987-06-01

Carbohydrates, including the monosaccharides commonly found in wood and wood pulp hydrolyzates, are separated by anion exchange chromatography using hydroxide and acetate eluants and are determined using pulsed amperometric detection. The detection method is based on oxidizing the sugars in a flow-through electrochemical cell equipped with a gold working electrode. A repeating cycle of three potentials is used: the first to oxidize the carbohydrates and measure the current generated, and two subsequent pulses to clean the electrode surface of oxidation products. The method is fast, sensitive, and requires no pre-column derivatization. It is applied to a sample of hydrolyzed wood pulp, which can be analyzed after minimal sample preparation. Detection limits are of the order of 1 mg/kg for monosaccharides in a 50 micro L injection. (Refs. 8).

Effect of vitamin B12 pulse addition on the performance of cobalt deprived anaerobic granular sludge bioreactors

KAUST Repository

Fermoso, Fernando G.

2010-07-01

The effect of a pulse addition of vitamin B12 as cobalt source to restore the performance of cobalt depleted methanol-fed bioreactors was investigated. One upflow anaerobic sludge bed (UASB) reactor was supplied with a pulse of vitamin B12, and its operation was compared to that of another cobalt depleted UASB reactor to which a pulse of CoCl2 was given. The addition of cobalt in the form of CoCl2 supplies enough cobalt to restore methanogenesis and maintain full methanol degradation coupled to methane production during more than 35 days after the CoCl2 pulse. Similar to CoCl2, pulse addition of vitamin B12 supplies enough cobalt to maintain full methanol degradation during more than 35 days after the pulse. However, the specific methanogenic activities (SMAs) of the sludge in the vitamin B12 supplied reactor were around 3 times higher than the SMA of the sludge from the CoCl2 supplied reactor at the same sampling times. An appropriate dosing strategy (repeated pulse dosing) combined with the choice of vitamin B12 as the cobalt species is suggested as a promising dosing strategy for methanol-fed anaerobic bioreactors limited by the micronutrient cobalt. © 2010 Elsevier Ltd. All rights reserved.

Short-pulse optical parametric chirped-pulse amplification for the generation of high-power few-cycle pulses

International Nuclear Information System (INIS)

Major, Zs.; Osterhoff, J.; Hoerlein, R.; Karsch, S.; Fuoloep, J.A.; Krausz, F.; Ludwig-Maximilians Universitaet, Muenchen

2006-01-01

Complete test of publication follows. In the quest for a way to generate ultrashort, high-power, few-cycle laser pulses the discovery of optical parametric amplification (OPA) has opened up to the path towards a completely new regime, well beyond that of conventional laser amplification technology. The main advantage of this parametric amplification process is that it allows for an extremely broad amplification bandwidth compared to any known laser amplifier medium. When combined with the chirped-pulse amplification (CPA) principle (i.e. OPCPA), on one hand pulses of just 10 fs duration and 8 mJ pulse energy have been demonstrated. On the other hand, pulse energies of up to 30 J were also achieved on a different OPCPA system; the pulse duration in this case, however, was 100 fs. In order to combine ultrashort pulse durations (i.e. pulses in the few-cycle regime) with high pulse energies (i.e. in the Joule range) we propose tu pump on OPCPA chain with TW-scale short pulses (100 fs - 1 ps instead of > 100 ps of previous OPCPA systems) delivered by a conventional CPA system. This approach inherently improves the conditions for generating high-power ultrashort pulses using OPCPA in the following ways. Firstly, the short pump pulse duration reduces the necessary stretching factor for the seed pulse, thereby increasing stretching and compression fidelity. Secondly, also due to the shortened pump pulse duration, a much higher contrast is achieved. Finally, the significantly increased pump power makes the use of thinner OPCPA crystals possible, which implies an even broader amplification bandwidth, thereby allowing for even shorter pulses. We carried out theoretical investigations to show the feasibility of such a set-up. Alongside these studies we will also present preliminary experimental results of an OPCPA system pumped by the output of our Ti:Sapphire ATLAS laser, currently delivering 350 mJ in 43 fs. An insight into the planned scaling of this technique to petawatt

Validation of Repeated Endothelial Function Measurements Using EndoPAT in Stroke

DEFF Research Database (Denmark)

Hansen, Aina S; Butt, Jawad H; Holm-Yildiz, Sonja

2017-01-01

BACKGROUND: Decreased endothelial function (EF) may be a prognostic marker for stroke. Measuring pharmacological effects on EF may be of interest in the development of personalized medicine for stroke prevention. In this study, we assessed the reliability of repeated EF measurements using a pulse......%, mean age 35.85 ± 3.47 years) and 21 stroke patients (men 52%, mean age 66.38 ± 2.85 years, and mean NIHSS 4.09 ± 0.53) under standardized conditions. EF was measured as the reactive hyperemia index (RHI), logarithm of RHI (lnRHI), and Framingham RHI (fRHI). Measurements were separated by 1.5 and 24 h...

WD-repeat instability and diversification of the Podospora anserina hnwd non-self recognition gene family.

Science.gov (United States)

Chevanne, Damien; Saupe, Sven J; Clavé, Corinne; Paoletti, Mathieu

2010-05-06

Genes involved in non-self recognition and host defence are typically capable of rapid diversification and exploit specialized genetic mechanism to that end. Fungi display a non-self recognition phenomenon termed heterokaryon incompatibility that operates when cells of unlike genotype fuse and leads to the cell death of the fusion cell. In the fungus Podospora anserina, three genes controlling this allorecognition process het-d, het-e and het-r are paralogs belonging to the same hnwd gene family. HNWD proteins are STAND proteins (signal transduction NTPase with multiple domains) that display a WD-repeat domain controlling recognition specificity. Based on genomic sequence analysis of different P. anserina isolates, it was established that repeat regions of all members of the gene family are extremely polymorphic and undergoing concerted evolution arguing for frequent recombination within and between family members. Herein, we directly analyzed the genetic instability and diversification of this allorecognition gene family. We have constituted a collection of 143 spontaneous mutants of the het-R (HNWD2) and het-E (hnwd5) genes with altered recognition specificities. The vast majority of the mutants present rearrangements in the repeat arrays with deletions, duplications and other modifications as well as creation of novel repeat unit variants. We investigate the extreme genetic instability of these genes and provide a direct illustration of the diversification strategy of this eukaryotic allorecognition gene family.

Pulsed electron beam generation with fast repetitive double pulse system

Energy Technology Data Exchange (ETDEWEB)

Sharma, Surender Kumar; Deb, Pankaj; Shyam, Anurag, E-mail: surender80@gmail.com [Energetics and Electromagnetics Division, Bhabha Atomic Research Centre, Visakhapatnam (India); Sharma, Archana [Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, Mumbai (India)

2014-07-01

Longer duration high voltage pulse (∼ 100 kV, 260 ns) is generated and reported using helical pulse forming line in compact geometry. The transmission line characteristics of the helical pulse forming line are also used to develop fast repetition double pulse system with very short inter pulse interval. It overcomes the limitations caused due to circuit parameters, power supplies and load characteristics for fast repetitive high voltage pulse generation. The high voltage double pulse of 100 kV, 100 ns with an inter pulse repetition interval of 30 ns is applied across the vacuum field emission diode for pulsed electron beam generation. The electron beam is generated from cathode material by application of negative high voltage (> 100 kV) across the diode by explosive electron emission process. The vacuum field emission diode is made of 40 mm diameter graphite cathode and SS mesh anode. The anode cathode gap was 6 mm and the drift tube diameter was 10 cm. The initial experimental results of pulsed electron beam generation with fast repetitive double pulse system are reported and discussed. (author)

Pulse Distortion in Saturated Fiber Optical Parametric Chirped Pulse Amplification

DEFF Research Database (Denmark)

Lali-Dastjerdi, Zohreh; Da Ros, Francesco; Rottwitt, Karsten

2012-01-01

Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation.......Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation....

A Unified Model for Repeating and Non-repeating Fast Radio Bursts

International Nuclear Information System (INIS)

Bagchi, Manjari

2017-01-01

The model that fast radio bursts (FRBs) are caused by plunges of asteroids onto neutron stars can explain both repeating and non-repeating bursts. If a neutron star passes through an asteroid belt around another star, there would be a series of bursts caused by a series of asteroid impacts. Moreover, the neutron star would cross the same belt repetitively if it were in a binary with the star hosting the asteroid belt, leading to a repeated series of bursts. I explore the properties of neutron star binaries that could lead to the only known repeating FRB so far (FRB121102). In this model, the next two epochs of bursts are expected around 2017 February 27 and 2017 December 18. On the other hand, if the asteroid belt is located around the neutron star itself, then a chance fall of an asteroid from that belt onto the neutron star would lead to a non-repeating burst. Even a neutron star grazing an asteroid belt can lead to a non-repeating burst caused by just one asteroid plunge during the grazing. This is possible even when the neutron star is in a binary with the asteroid-hosting star, if the belt and the neutron star orbit are non-coplanar.

A Unified Model for Repeating and Non-repeating Fast Radio Bursts

Energy Technology Data Exchange (ETDEWEB)

Bagchi, Manjari, E-mail: manjari@imsc.res.in [The Institute of Mathematical Sciences (IMSc-HBNI), 4th Cross Road, CIT Campus, Taramani, Chennai 600113 (India)

2017-04-01

The model that fast radio bursts (FRBs) are caused by plunges of asteroids onto neutron stars can explain both repeating and non-repeating bursts. If a neutron star passes through an asteroid belt around another star, there would be a series of bursts caused by a series of asteroid impacts. Moreover, the neutron star would cross the same belt repetitively if it were in a binary with the star hosting the asteroid belt, leading to a repeated series of bursts. I explore the properties of neutron star binaries that could lead to the only known repeating FRB so far (FRB121102). In this model, the next two epochs of bursts are expected around 2017 February 27 and 2017 December 18. On the other hand, if the asteroid belt is located around the neutron star itself, then a chance fall of an asteroid from that belt onto the neutron star would lead to a non-repeating burst. Even a neutron star grazing an asteroid belt can lead to a non-repeating burst caused by just one asteroid plunge during the grazing. This is possible even when the neutron star is in a binary with the asteroid-hosting star, if the belt and the neutron star orbit are non-coplanar.

Pulse superimposition calculational methodology for estimating the subcriticality level of nuclear fuel assemblies

International Nuclear Information System (INIS)

Talamo, Alberto; Gohar, Y.; Rabiti, C.; Aliberti, G.; Kondev, F.; Smith, D.; Zhong, Z.; Kiyavitskaya, H.; Bournos, V.; Fokov, Y.; Routkovskaya, C.; Serafimovich, I.

2009-01-01

One of the most reliable experimental methods for measuring the subcriticality level of a nuclear fuel assembly is the Sjoestrand method applied to the reaction rate generated from a pulsed neutron source. This study developed a new analytical methodology simulating the Sjoestrand method, which allows comparing the experimental and analytical reaction rates and the obtained subcriticality levels. In this methodology, the reaction rate is calculated due to a single neutron pulse using MCNP/MCNPX computer code or any other neutron transport code that explicitly simulates the delayed fission neutrons. The calculation simulates a single neutron pulse over a long time period until the delayed neutron contribution to the reaction rate is vanished. The obtained reaction rate is then superimposed to itself, with respect to the time, to simulate the repeated pulse operation until the asymptotic level of the reaction rate, set by the delayed neutrons, is achieved. The superimposition of the pulse to itself was calculated by a simple C computer program. A parallel version of the C program is used due to the large amount of data being processed, e.g. by the Message Passing Interface (MPI). The analytical results of this new calculation methodology have shown an excellent agreement with the experimental data available from the YALINA-Booster facility of Belarus. This methodology can be used to calculate Bell and Glasstone spatial correction factor.

Pulse superimposition calculational methodology for estimating the subcriticality level of nuclear fuel assemblies

Energy Technology Data Exchange (ETDEWEB)

Talamo, Alberto [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)], E-mail: atalamo@anl.gov; Gohar, Y. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Rabiti, C. [Idaho National Laboratory, P.O. Box 2528, Idaho Falls, ID 83403 (United States); Aliberti, G.; Kondev, F.; Smith, D.; Zhong, Z. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Kiyavitskaya, H.; Bournos, V.; Fokov, Y.; Routkovskaya, C.; Serafimovich, I. [Joint Institute for Power and Nuclear Research-Sosny, National Academy of Sciences (Belarus)

2009-07-21

One of the most reliable experimental methods for measuring the subcriticality level of a nuclear fuel assembly is the Sjoestrand method applied to the reaction rate generated from a pulsed neutron source. This study developed a new analytical methodology simulating the Sjoestrand method, which allows comparing the experimental and analytical reaction rates and the obtained subcriticality levels. In this methodology, the reaction rate is calculated due to a single neutron pulse using MCNP/MCNPX computer code or any other neutron transport code that explicitly simulates the delayed fission neutrons. The calculation simulates a single neutron pulse over a long time period until the delayed neutron contribution to the reaction rate is vanished. The obtained reaction rate is then superimposed to itself, with respect to the time, to simulate the repeated pulse operation until the asymptotic level of the reaction rate, set by the delayed neutrons, is achieved. The superimposition of the pulse to itself was calculated by a simple C computer program. A parallel version of the C program is used due to the large amount of data being processed, e.g. by the Message Passing Interface (MPI). The analytical results of this new calculation methodology have shown an excellent agreement with the experimental data available from the YALINA-Booster facility of Belarus. This methodology can be used to calculate Bell and Glasstone spatial correction factor.

Updating the induction module from single-pulse to double-pulses

International Nuclear Information System (INIS)

Huang Ziping; Wang Huacen; Deng Jianjun

2002-01-01

A double-pulse Linear Induced Accelerator (LIA) module is reconstructed based on a usual simple-pulse LIA module. By changing the length of one of the cables between the inductive cell and the Blumlein pulse forming line, two induction pulses with 90 ns FWHM and 150 kV pulse voltage are generated by the ferrite cores inductive cell. The interval time of the pulses is adjustable by changing the lengths of the cable

Repeatability of Cryogenic Multilayer Insulation

Science.gov (United States)

Johnson, W. L.; Vanderlaan, M.; Wood, J. J.; Rhys, N. O.; Guo, W.; Van Sciver, S.; Chato, D. J.

2017-12-01

Due to the variety of requirements across aerospace platforms, and one off projects, the repeatability of cryogenic multilayer insulation (MLI) has never been fully established. The objective of this test program is to provide a more basic understanding of the thermal performance repeatability of MLI systems that are applicable to large scale tanks. There are several different types of repeatability that can be accounted for: these include repeatability between identical blankets, repeatability of installation of the same blanket, and repeatability of a test apparatus. The focus of the work in this report is on the first two types of repeatability. Statistically, repeatability can mean many different things. In simplest form, it refers to the range of performance that a population exhibits and the average of the population. However, as more and more identical components are made (i.e. the population of concern grows), the simple range morphs into a standard deviation from an average performance. Initial repeatability testing on MLI blankets has been completed at Florida State University. Repeatability of five Glenn Research Center (GRC) provided coupons with 25 layers was shown to be +/- 8.4% whereas repeatability of repeatedly installing a single coupon was shown to be +/- 8.0%. A second group of 10 coupons has been fabricated by Yetispace and tested by Florida State University, the repeatability between coupons has been shown to be +/- 15-25%. Based on detailed statistical analysis, the data has been shown to be statistically significant.

Repeated CT scans in trauma transfers: An analysis of indications, radiation dose exposure, and costs

International Nuclear Information System (INIS)

Hinzpeter, Ricarda; Sprengel, Kai; Wanner, Guido A.; Mildenberger, Peter; Alkadhi, Hatem

2017-01-01

Highlights: • Repetition of CT in trauma patients occurs relatively often. • Repetition of CT is mainly caused by inadequate image data transfer. • Potentially preventable CT examinations add radiation dose to patients. • Repeated CT is associated with excess costs to the health care system. - Abstract: Objectives: To identify the number of CT scans repeated in acute trauma patients receiving imaging before being referred to a trauma center, to define indications, and to assess radiation doses and costs of repeated CT. Methods: This retrospective study included all adult trauma patients transferred from other hospitals to a Level-I trauma center during 2014. Indications for repeated CT scans were categorized into: inadequate CT image data transfer, poor image quality, repetition of head CT after head injury together with completion to whole-body CT (WBCT), and follow-up of injury known from previous CT. Radiation doses from repeated CT were determined; costs were calculated using a nation-wide fee schedule. Results: Within one year, 85/298 (28.5%) trauma patients were transferred from another hospital because of severe head injury (n = 45,53%) and major body trauma (n = 23;27%) not manageable in the referring hospital, repatriation from a foreign country (n = 14;16.5%), and no ICU-capacity (n = 3;3.5%). Of these 85 patients, 74 (87%) had repeated CT in our center because of inadequate CT data transfer (n = 29;39%), repetition of head CT with completion to WBCT (n = 24;32.5%), and follow-up of known injury (n = 21;28.5%). None occurred because of poor image quality. Cumulative dose length product (DLP) and annual costs of potential preventable, repeated CT (inadequate data transfer) was 631mSv (81′304mGy*cm) and 35′233€, respectively. Conclusion: A considerable number of transferred trauma patients undergo potentially preventable, repeated CT, adding radiation dose to patients and costs to the health care system.

Repeated CT scans in trauma transfers: An analysis of indications, radiation dose exposure, and costs

Energy Technology Data Exchange (ETDEWEB)

Hinzpeter, Ricarda, E-mail: Ricarda.Hinzpeter@usz.ch [Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Raemistr. 100, Zurich CH-8091 (Switzerland); Sprengel, Kai, E-mail: Kai.Sprengel@usz.ch [Division of Trauma Surgery, Department of Surgery, University Hospital Zurich, University of Zurich, Raemistr. 100, CH-8091 Zurich (Switzerland); Wanner, Guido A., E-mail: Guido.Wanner@sbk-vs.de [Division of Trauma Surgery, Department of Surgery, University Hospital Zurich, University of Zurich, Raemistr. 100, CH-8091 Zurich (Switzerland); Department of General Surgery, Schwarzwald-Baar Klinikum, University of Freiburg, Klinikstr. 11, D-78052 Villingen-Schwenningen (Germany); Mildenberger, Peter, E-mail: peter.mildenberger@unimedizin-mainz.de [Department of Diagnostic and Interventional Radiology, University Hospital of Mainz, Langenbeckstr. 1, D-55131 Mainz (Germany); Alkadhi, Hatem, E-mail: hatem.alkadhi@usz.ch [Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Raemistr. 100, Zurich CH-8091 (Switzerland)

2017-03-15

Highlights: • Repetition of CT in trauma patients occurs relatively often. • Repetition of CT is mainly caused by inadequate image data transfer. • Potentially preventable CT examinations add radiation dose to patients. • Repeated CT is associated with excess costs to the health care system. - Abstract: Objectives: To identify the number of CT scans repeated in acute trauma patients receiving imaging before being referred to a trauma center, to define indications, and to assess radiation doses and costs of repeated CT. Methods: This retrospective study included all adult trauma patients transferred from other hospitals to a Level-I trauma center during 2014. Indications for repeated CT scans were categorized into: inadequate CT image data transfer, poor image quality, repetition of head CT after head injury together with completion to whole-body CT (WBCT), and follow-up of injury known from previous CT. Radiation doses from repeated CT were determined; costs were calculated using a nation-wide fee schedule. Results: Within one year, 85/298 (28.5%) trauma patients were transferred from another hospital because of severe head injury (n = 45,53%) and major body trauma (n = 23;27%) not manageable in the referring hospital, repatriation from a foreign country (n = 14;16.5%), and no ICU-capacity (n = 3;3.5%). Of these 85 patients, 74 (87%) had repeated CT in our center because of inadequate CT data transfer (n = 29;39%), repetition of head CT with completion to WBCT (n = 24;32.5%), and follow-up of known injury (n = 21;28.5%). None occurred because of poor image quality. Cumulative dose length product (DLP) and annual costs of potential preventable, repeated CT (inadequate data transfer) was 631mSv (81′304mGy*cm) and 35′233€, respectively. Conclusion: A considerable number of transferred trauma patients undergo potentially preventable, repeated CT, adding radiation dose to patients and costs to the health care system.

Evaluation of bipolar pulse generator for high-purity pulsed ion beam

International Nuclear Information System (INIS)

Ito, H.; Kitamura, I.; Masugata, K.

2008-01-01

A new type of pulsed ion beam accelerator named 'bipolar pulse accelerator (BPA)' has been proposed in order to improve the purity of intense pulsed ion beams. To confirm the principle of the BPA, we developed a bipolar pulse generator, which consists of a Marx generator and a pulse forming line (PFL) with a rail gap switch on its end. In this article, we report the experimental results of the bipolar pulse and evaluate the electrical characteristics of the bipolar pulse generator. When the bipolar pulse generator was operated at 70% of the full charge condition of the PEL, the bipolar pulse with the first (-138 kV, 72 ns) and the second pulse (+130 kV, 70 ns) was successfully obtained. The evaluation of the electrical characteristics indicates that the developed generator can produce the bipolar pulse with fast rise time and sharp reversing time. At present the bipolar pulse generator is installed in the B y type magnetically insulated ion diode and we carry out the experiment on the production of an intense pulsed ion beam by the bipolar pulse accelerator. (author)

Intense, pulsed, ion-diode sources and their application to mirror machines

International Nuclear Information System (INIS)

Prono, D.S.; Shearer, J.W.; Briggs, R.J.

1975-01-01

Startup conditions for future mirror fusion experiments require a rapidly formed target plasma of approximately 0.5 coulomb of ions with energy of 50 to 100 keV. Theory suggests that very intense ion-flux emission satisfying these requirements can be extracted from a pulsed ion diode. Developing such sources would be an ideal CTR application of the high-power, single-shot capability of pulsed power technology. Recent experimental results are reviewed in which approximately 2 kA/cm 2 of D + at approximately 50 keV was extracted. In the experiment, an intense relativistic electron beam undergoes many transits through a solid but range-thin anode foil. With each transit the electrons lose energy, causing their trajectories to collapse toward the anode surface. In so doing, the increased space charge extracts an intense ion flux from the anode foil's plasma. Observations are reported on the importance of diode stability. The general agreement between theoretical scaling laws and experimental results are also presented

Influence of pulse electric current on structure and superconducting properties of high temperature superconductor

International Nuclear Information System (INIS)

Rajchenko, A.I.; Flis, A.A.; Chernenko, L.I.; Kryuchkova, N.I.

1998-01-01

The influence of high-density pulse current treatment at room temperature on structure and superconducting properties of HTSC Y Ba 2 Cu 3 O x ceramics is studied. The structures of the samples are found to undergo appreciable changes as the density of pulse current is gradually increased from its minimum value; as a certain threshold value is attained, there occurs a melting-off of coarse grains with a partial destroying of intergrain contact areas followed by superconductivity loss. A further increase in the treatment current density results in a restoration of the superconducting properties probably due to the occurrence of aligned-with-current superconducting bridges between the melted-off grains. The superconducting transition temperature in the samples does not charge but subsequent thermal treatment causes this temperature to increase

Deployment Repeatability

Science.gov (United States)

2016-04-01

evaluating the deployment repeatability builds upon the testing or analysis of deployment kinematics (Chapter 6) and adds repetition. Introduction...material yield or failure during a test. For the purposes of this chapter, zero shift will refer to permanent changes in the structure, while reversible ...the content of other chapters in this book: Gravity Compensation (Chapter 4) and Deployment Kinematics and Dynamics (Chapter 6). Repeating the

Pulse-shaping strategies in short-pulse fiber amplifiers

Energy Technology Data Exchange (ETDEWEB)

Schimpf, Damian Nikolaus

2010-02-09

Ultrashort pulse lasers are an important tool in scientific and industrial applications. However, many applications are demanding higher average powers from these ultrashort pulse sources. This can be achieved by combining direct diode pumping with novel gain media designs. In particular, ultrashort pulse fiber lasers are now delivering average powers in the kW range. However, the design of fiber lasers, producing pulses with high peak-powers, is challenging due to the impact of nonlinear effects. To significantly reduce these detrimental effects in ultrashort pulse fiber amplifers, the combination of chirped pulse amplification (CPA) and large mode area fibers is employed. Using these methods, the pulse energy of fiber lasers has been steadily increasing for the past few years. Recently, a fiber-based CPA-system has been demonstrated which produces pulse energies of around 1 mJ. However, both the stretching and the enlargement of the mode area are limited, and therefore, the impact of nonlinearity is still noticed in systems employing such devices. The aim of this thesis is the analysis of CPA-systems operated beyond the conventional nonlinear limit, which corresponds to accumulated nonlinear phase-shifts around 1 rad. This includes a detailed discussion of the influence of the nonlinear effect self-phase modulation on the output pulse of CPA-systems. An analytical model is presented. Emphasis is placed on the design of novel concepts to control the impact of self-phase modulation. Pulse-shaping is regarded as a powerful tool to accomplish this goal. Novel methods to control the impact of SPM are experimentally demonstrated. The design of these concepts is based on the theoretical findings. Both amplitude- and phase-shaping are studied. Model-based phase-shaping is implemented in a state-of-the-art fiber CPA-system. The influence of the polarization state is also highlighted. Additionally, existing techniques and recent advances are put into context. (orig.)

Pulse-shaping strategies in short-pulse fiber amplifiers

International Nuclear Information System (INIS)

Schimpf, Damian Nikolaus

2010-01-01

Ultrashort pulse lasers are an important tool in scientific and industrial applications. However, many applications are demanding higher average powers from these ultrashort pulse sources. This can be achieved by combining direct diode pumping with novel gain media designs. In particular, ultrashort pulse fiber lasers are now delivering average powers in the kW range. However, the design of fiber lasers, producing pulses with high peak-powers, is challenging due to the impact of nonlinear effects. To significantly reduce these detrimental effects in ultrashort pulse fiber amplifers, the combination of chirped pulse amplification (CPA) and large mode area fibers is employed. Using these methods, the pulse energy of fiber lasers has been steadily increasing for the past few years. Recently, a fiber-based CPA-system has been demonstrated which produces pulse energies of around 1 mJ. However, both the stretching and the enlargement of the mode area are limited, and therefore, the impact of nonlinearity is still noticed in systems employing such devices. The aim of this thesis is the analysis of CPA-systems operated beyond the conventional nonlinear limit, which corresponds to accumulated nonlinear phase-shifts around 1 rad. This includes a detailed discussion of the influence of the nonlinear effect self-phase modulation on the output pulse of CPA-systems. An analytical model is presented. Emphasis is placed on the design of novel concepts to control the impact of self-phase modulation. Pulse-shaping is regarded as a powerful tool to accomplish this goal. Novel methods to control the impact of SPM are experimentally demonstrated. The design of these concepts is based on the theoretical findings. Both amplitude- and phase-shaping are studied. Model-based phase-shaping is implemented in a state-of-the-art fiber CPA-system. The influence of the polarization state is also highlighted. Additionally, existing techniques and recent advances are put into context. (orig.)

Pulse Generator

Science.gov (United States)

Greer, Lawrence (Inventor)

2017-01-01

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

Reconfigurable multiport EPON repeater

Science.gov (United States)

Oishi, Masayuki; Inohara, Ryo; Agata, Akira; Horiuchi, Yukio

2009-11-01

An extended reach EPON repeater is one of the solutions to effectively expand FTTH service areas. In this paper, we propose a reconfigurable multi-port EPON repeater for effective accommodation of multiple ODNs with a single OLT line card. The proposed repeater, which has multi-ports in both OLT and ODN sides, consists of TRs, BTRs with the CDR function and a reconfigurable electrical matrix switch, can accommodate multiple ODNs to a single OLT line card by controlling the connection of the matrix switch. Although conventional EPON repeaters require full OLT line cards to accommodate subscribers from the initial installation stage, the proposed repeater can dramatically reduce the number of required line cards especially when the number of subscribers is less than a half of the maximum registerable users per OLT. Numerical calculation results show that the extended reach EPON system with the proposed EPON repeater can save 17.5% of the initial installation cost compared with a conventional repeater, and can be less expensive than conventional systems up to the maximum subscribers especially when the percentage of ODNs in lightly-populated areas is higher.

Advanced pulse oximeter signal processing technology compared to simple averaging. I. Effect on frequency of alarms in the operating room.

Science.gov (United States)

Rheineck-Leyssius, A T; Kalkman, C J

1999-05-01

To determine the effect of a new signal processing technique (Oxismart, Nellcor, Inc., Pleasanton, CA) on the incidence of false pulse oximeter alarms in the operating room (OR). Prospective observational study. Nonuniversity hospital. 53 ASA physical status I, II, and III consecutive patients undergoing general anesthesia with tracheal intubation. In the OR we compared the number of alarms produced by a recently developed third generation pulse oximeter (Nellcor Symphony N-3000) with Oxismart signal processing technique and a conventional pulse oximeter (Criticare 504). Three pulse oximeters were used simultaneously in each patient: a Nellcor pulse oximeter, a Criticare with the signal averaging time set at 3 seconds (Criticareaverage3s) and a similar unit with the signal averaging time set at 21 seconds (Criticareaverage21s). For each pulse oximeter, the number of false (artifact) alarms was counted. One false alarm was produced by the Nellcor (duration 55 sec) and one false alarm by the Criticareaverage21s monitor (5 sec). The incidence of false alarms was higher in Criticareaverage3s. In eight patients, Criticareaverage3s produced 20 false alarms (p signal processing compared with the Criticare monitor with the longer averaging time of 21 seconds.

Application Of Pulsed Laser Holography To Nondestructive Testing Of Aircraft Structures

Science.gov (United States)

Fagot, Hubert; Smigielski, Paul; Arnaud, Jean-Louis

1983-03-01

Subsequently to laboratory tests, experiments were conducted on an aircraft undergoing maintenance in order to assess the possible uses of holographic interferometry for non-destructive testing of large aircraft structures. A double ruby laser was used delivering two pulses with a duration of 20 ns each. The two pulses are separated by an arbitrary time interval At which is determined as a function of both the amplitude and frequency of the surface displacement. Shocks of the order of 100 mJ cause the structure under investigation to vibrate, the time interval At thereby ranging from 10 to 100 ps for a delay of a few ms after shock initiation. The method used is relatively insensitive to environmental disturbances. Although the laser delivers pulses of light of less than 100 mJ in energy, it is possible to visualize a field of 0.5 x1 m. Some results will be reported which have been obtained at the lower surface of an aerofoil, on a wheel well and on an air-brake. Finally a brief review will be made on the improvements envisaged on both the laser and the recording method in order to obtain an operational system for holographic non-destructive testing.

Pulsed water jet generated by pulse multiplication

Czech Academy of Sciences Publication Activity Database

Dvorský, R.; Sitek, Libor; Sochor, T.

2016-01-01

Roč. 23, č. 4 (2016), s. 959-967 ISSN 1330-3651 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : high- pressure pulses * pulse intensifier * pulsed water jet * water hammer effect Subject RIV: JQ - Machines ; Tools Impact factor: 0.723, year: 2016 http://hrcak.srce.hr/163752?lang=en

EBFA: pulsed power for fusion

International Nuclear Information System (INIS)

Martin, T.H.; VanDevender, J.P.; Barr, G.W.; Johnson, D.L.

1979-01-01

This paper will describe the EBFA I accelerator under construction for inertial confinement fusion studies with particle beams and will update previous publications concerning particle beam fusion accelerators. Previous information included Proto I, a triggered oil insulated 1 TW accelerator; Proto II, a water insulated 10 TW accelerator; and EBFA I, a 30 TW, 1 MJ accelerator. Some modifications to the original design have occurred. A new pulse-forming-line concept has been developed which increases the flexibility of the accelerator. The major problem of vacuum interface flashover has been solved by the use of long, magnetically-insulated, transmission lines. The first production module of EBFA I has been received, assembled, and is now undergoing extensive testing. The technology is extendable to at least a factor of ten above the projected EBFA capabilities of 30 TW and 1 MJ output. Progress on facilities associated with the Sandia Particle Beam fusion program is reported

Design of a bolometer for total-energy measurement of the linear coherent light source pulsed X-ray laser

International Nuclear Information System (INIS)

Friedrich, S.; Li, L.; Ott, L.L.; Kolgani, Rajeswari M.; Yong, G.J.; Ali, Z.A.; Drury, O.B.; Ables, E.; Bionta, R.M.

2006-01-01

We are developing a cryogenic bolometer to measure the total energy of the linear coherent light source (LCLS) free electron X-ray laser to be built at the Stanford Linear Accelerator Center. The laser will produce ultrabright X-ray pulses in the energy range between 0.8 and 8 keV with ∼10 12 photons per ∼200 fs pulse at a repeat interval of 8 ms, and will be accompanied by a halo of spontaneous undulator radiation. The bolometer is designed to determine the total energy of each laser pulse to within (1- x ) Sr x MnO 3 sensor array at the metal-insulator transition, where the composition x is adjusted to produce the desired transition temperature. We discuss design considerations and material choices, and present numerical simulations of the thermal response

Pulsed TRIGA reactor as substitute for long pulse spallation neutron source

International Nuclear Information System (INIS)

Whittemore, W.L.

1999-01-01

TRIGA reactor cores have been used to demonstrate various pulsing applications. The TRIGA reactor fuel (U-ZrH x ) is very robust especially in pulsing applications. The features required to produce 50 pulses per second have been successfully demonstrated individually, including pulse tests with small diameter fuel rods. A partially optimized core has been evaluated for pulses at 50 Hz with peak pulsed power up to 100 MW and an average power up to 10 MW. Depending on the design, the full width at half power of the individual pulses can range between 2000 μsec to 3000 μsec. Until recently, the relatively long pulses (2000 μsec to 3000 μsec) from a pulsed thermal reactor or a long pulse spallation source (LPSS) have been considered unsuitable for time-of-flight measurements of neutron scattering. More recently considerable attention has been devoted to evaluating the performance of long pulse (1000 to 4000 μs) spallation sources for the same type of neutron measurements originally performed only with short pulses from spallation sources (SPSS). Adequate information is available to permit meaningful comparisons between CW, SPSS, and LPSS neutron sources. Except where extremely high resolution is required (fraction of a percent), which does require short pulses, it is demonstrated that the LPSS source with a 1000 msec or longer pulse length and a repetition rate of 50 to 60 Hz gives results comparable to those from the 60 MW ILL (CW) source. For many of these applications the shorter pulse is not necessarily a disadvantage, but it is not an advantage over the long pulse system. In one study, the conclusion is that a 5 MW 2000 μsec LPSS source improves the capability for structural biology studies of macromolecules by at least a factor of 5 over that achievable with a high flux reactor. Recent studies have identified the advantages and usefulness of long pulse neutron sources. It is evident that the multiple pulse TRIGA reactor can produce pulses comparable to

Family-Related Opinions and Stressful Situations Associated with Psychological Distress in Women Undergoing Infertility Treatment

Directory of Open Access Journals (Sweden)

Jiro Takaki

2014-09-01

Full Text Available The purpose of this study is to investigate how family-related opinions and stressful situations are related to psychological distress in women undergoing infertility treatment. The subjects in this cross-sectional study were recruited from female patients undergoing infertility treatment (n = 2540 at 70 infertility treatment institutions in Japan. Because of non-participation or missing data, the number of subjects included in the analysis was 635 (response rate, 25.0%. The family-related opinions and stressful situations were evaluated using the original questions. Psychological distress was assessed using a self-report measure, the Kessler Six-question Psychological Distress Scale (K6. The K6 scores of the following participants were significantly (p < 0.05 and independently high: those with more frequent miscarriage/stillbirth/abortions, those with repeated miscarriages as the cause of infertility, those with infertility of unknown causes, those living with no child, those having a low joint income with their partner, those with the opinion that “women should devote themselves to their household duties” those who had considered stopping treatment, those without the opinion that “married life without children is favorable” and those who had experienced stressful situations such as inadequate explanation by doctors, frustration of multiple failed attempts, differences of opinion with the partner, and lack of knowledge regarding when to stop treatment. Family-related opinions and stressful situations associated with psychological distress in women undergoing infertility treatment are outlined. The results of this study may contribute to the prevention of and care for psychological distress in female patients undergoing infertility treatment.

Method for pulse to pulse dose reproducibility applied to electron linear accelerators

International Nuclear Information System (INIS)

Ighigeanu, D.; Martin, D.; Oproiu, C.; Cirstea, E.; Craciun, G.

2002-01-01

An original method for obtaining programmed beam single shots and pulse trains with programmed pulse number, pulse repetition frequency, pulse duration and pulse dose is presented. It is particularly useful for automatic control of absorbed dose rate level, irradiation process control as well as in pulse radiolysis studies, single pulse dose measurement or for research experiments where pulse-to-pulse dose reproducibility is required. This method is applied to the electron linear accelerators, ALIN-10 of 6.23 MeV and 82 W and ALID-7, of 5.5 MeV and 670 W, built in NILPRP. In order to implement this method, the accelerator triggering system (ATS) consists of two branches: the gun branch and the magnetron branch. ATS, which synchronizes all the system units, delivers trigger pulses at a programmed repetition rate (up to 250 pulses/s) to the gun (80 kV, 10 A and 4 ms) and magnetron (45 kV, 100 A, and 4 ms).The accelerated electron beam existence is determined by the electron gun and magnetron pulses overlapping. The method consists in controlling the overlapping of pulses in order to deliver the beam in the desired sequence. This control is implemented by a discrete pulse position modulation of gun and/or magnetron pulses. The instabilities of the gun and magnetron transient regimes are avoided by operating the accelerator with no accelerated beam for a certain time. At the operator 'beam start' command, the ATS controls electron gun and magnetron pulses overlapping and the linac beam is generated. The pulse-to-pulse absorbed dose variation is thus considerably reduced. Programmed absorbed dose, irradiation time, beam pulse number or other external events may interrupt the coincidence between the gun and magnetron pulses. Slow absorbed dose variation is compensated by the control of the pulse duration and repetition frequency. Two methods are reported in the electron linear accelerators' development for obtaining the pulse to pulse dose reproducibility: the method

Effect of live music therapy for patients undergoing magnetic resonance imaging.

Science.gov (United States)

Walworth, Darcy D

2010-01-01

The purpose of the current study was to identify the effects of live music therapy interventions compared with preferred recorded music for patients undergoing MRI scans. To date, there has not been a published study involving the use of live music therapy during MRI scans. The current study investigated the differences between teenage through adult patients receiving live music therapy intervention during outpatient MRI scans versus the standard protocol of care listening to recorded music (N = 88). Subjects ranged in age from 15 to 93 years old. Results indicated subjects who received the live music therapy protocol reported significantly better perception of the MRI procedure (p music therapy protocol had fewer scans repeated due to movement. Of the repeated images, 26% occurred in the live music group and 73% occurred in the recorded music group. Subjects receiving live music therapy also requested less breaks from the scan. Two percent of the live music subjects requested a break and 17.6% of the control patients requested breaks. When comparing the same type of scan between groups, subjects receiving the live music protocol required less time to complete the scans. For lumbar scans without contrast (N = 14, n = 7, n = 7), live music subjects spent an average of 4.63 less min per scan for a total of 32 less min for 7 subjects. For brain scans (N = 8, n = 4, n = 4), live music subjects spent an average of 5.8 less min per scan for a total of 23 less min for 4 subjects. Results of the current study supports the use of live music therapy intervention for teenage and adult patients undergoing MRI scans to reduce patient anxiety and improve patient perception of the scan experience. Additionally, live music therapy has the potential to shorten the length of time required for patients to complete MRI scans due to decreased patient movements and fewer breaks requested during the scans. The cost savings impact of reduced procedure time can positively impact the

Pulse!!: a model for research and development of virtual-reality learning in military medical education and training.

Science.gov (United States)

Dunne, James R; McDonald, Claudia L

2010-07-01

Pulse!! The Virtual Clinical Learning Lab at Texas A&M University-Corpus Christi, in collaboration with the United States Navy, has developed a model for research and technological development that they believe is an essential element in the future of military and civilian medical education. The Pulse!! project models a strategy for providing cross-disciplinary expertise and resources to educational, governmental, and business entities challenged with meeting looming health care crises. It includes a three-dimensional virtual learning platform that provides unlimited, repeatable, immersive clinical experiences without risk to patients, and is available anywhere there is a computer. Pulse!! utilizes expertise in the fields of medicine, medical education, computer science, software engineering, physics, computer animation, art, and architecture. Lab scientists collaborate with the commercial virtual-reality simulation industry to produce research-based learning platforms based on cutting-edge computer technology.

Narrowband pulse-enhanced upconversion of chirped broadband pulses

International Nuclear Information System (INIS)

Zhao, Kun; Yuan, Peng; Zhong, Haizhe; Zhang, Dongfang; Zhu, Heyuan; Qian, Liejia; Chen, Liezun; Wen, Shuangchun

2010-01-01

We propose and demonstrate an efficient sum-frequency mixing scheme based on narrowband and chirped broadband pulses. It combines the advantages of wider spectral acceptance bandwidth and of alleviating the temporal walk-off, which are both beneficial to higher conversion efficiency. Chirped sum-frequency pulses at 455 nm with energy up to 360 µJ, corresponding to a conversion efficiency of ∼ 40%, are obtained and the pulses can be compressed to ∼ 110 fs. The sum-frequency mixing scheme may provide a promising route to the efficient generation of deep-ultraviolet femtosecond pulses

Pulse energy evolution for high-resolution Lamb wave inspection

International Nuclear Information System (INIS)

Hua, Jiadong; Zeng, Liang; Gao, Fei; Lin, Jing

2015-01-01

Generally, tone burst excitation methods are used to reduce the effect of dispersion in Lamb wave inspection. In addition, algorithms for dispersion compensation are required to simplify responses, especially in long-range inspection. However, the resolution is always limited by the time duration of tone burst excitation. A pulse energy evolution method is established to overcome this limitation. In this method, a broadband signal with a long time (e.g. a chirp, white noise signal, or a pseudo-random sequence) is used as excitation to actuate Lamb waves. First of all, pulse compression is employed to estimate system impulse response with a high signal-to-noise ratio. Then, dispersion compensation is applied repeatedly with systemically varied compensation distances, obtaining a series of compensated signals. In these signals, amplitude (or energy) evolution associated with the change of compensation distance is utilized to estimate the actual propagation distance of the interested wave packet. Finally, the defect position is detected by an imaging algorithm. Several experiments are given to validate the proposed method. (paper)

Repeated cadmium nebulizations induce pulmonary MMP-2 and MMP-9 production and enphysema in rats

International Nuclear Information System (INIS)

Kirschvink, Nathalie; Vincke, Gregoire; Fievez, Laurence; Onclinx, Cecile; Wirth, Delphine; Belleflamme, Michele; Louis, Renaud; Cataldo, Didier; Peck, Michael J.; Gustin, Pascal

2005-01-01

This study describes induction of pulmonary inflammation, production of matrix metalloprotease of type 2 (MMP-2) and type 9 (MMP-9), and emphysema in cadmium (Cd)-exposed rats. Sprague-Dawley rats were randomly distributed into two groups: one placebo-exposed group undergoing saline (NaCl 0.9%) inhalation (n = 30) and one Cd-exposed group undergoing cadmium (CdCl 2 0.1%) inhalation (n = 30). The animals of the placebo- and Cd-exposed groups were divided in five subgroups (n = 6). Subgroups underwent either a single exposure of 1 h or repeated exposures three times weekly for 1 h during 3 weeks (3W), 5 weeks (5W), 5 weeks followed by 2 weeks without exposure (5W + 2) or 5 weeks followed by 4 weeks without exposure (5W + 4). Each animal underwent determination of enhanced pause (Penh) as index of airflow limitation prior to the first exposure as well as before sacrifice. The animals were sacrificed the day after their last exposure. The left lung was fixed for histomorphometric analysis (determination of median interwall distance (MIWD)), whilst bronchoalveolar lavage fluid (BALF) was collected from the right lung. BALF was analyzed cytologically, and MMP-2 and MMP-9 levels were determined by gelatine zymography. Twelve rats previously instilled with pancreatic elastase were used as positive emphysema controls and underwent the same investigations. Cd-exposure induced a significant increase of BALF macrophages, neutrophils and MMP-9 up to 5W + 4, whereas MMP-2 gelatinolytic activity returned to baseline levels within 5W. MIWD was significantly increased in all repeatedly Cd-exposed groups and elastase-treated rats. Penh was increased in Cd-exposed rats after a single exposure and after 3W. MMP gelatinolytic activity was significantly correlated with macrophages, neutrophils and Penh. In repeatedly exposed rats, MIWD was positively and significantly correlated with MMP gelatinolytic activity, suggesting that increased MMP-2 and MMP-9 production favours the development

International Year of Pulses 2016 | 2016 International Year of Pulses

Science.gov (United States)

the Year in collaboration with Governments, relevant organizations, non-governmental organizations and the composition of pulses Image 4 Wrapping up the International Year of Pulses The 5 key messages to food security Infographic Pulses and climate change International Year of Pulses 2016 The 68th UN

Programmable pulse generator

International Nuclear Information System (INIS)

Xue Zhihua; Lou Binqiao; Duan Xiaohui

2002-01-01

The author introduces the design of programmable pulse generator that is based on a micro-controller and controlled by RS232 interface of personal computer. The whole system has good stability. The pulse generator can produce TTL pulse and analog pulse. The pulse frequency can be selected by EPLD. The voltage amplitude and pulse width of analog pulse can be adjusted by analog switches and digitally-controlled potentiometers. The software development tools of computer is National Instruments LabView5.1. The front panel of this virtual instrumentation is intuitive and easy-to-use. Parameters can be selected and changed conveniently by knob and slide

Triage of Women with Low-Grade Cervical Lesions - HPV mRNA Testing versus Repeat Cytology

Science.gov (United States)

Sørbye, Sveinung Wergeland; Arbyn, Marc; Fismen, Silje; Gutteberg, Tore Jarl; Mortensen, Elin Synnøve

2011-01-01

Background In Norway, women with low-grade squamous intraepithelial lesions (LSIL) are followed up after six months in order to decide whether they should undergo further follow-up or be referred back to the screening interval of three years. A high specificity and positive predictive value (PPV) of the triage test is important to avoid unnecessary diagnostic and therapeutic procedures. Materials and Methods At the University Hospital of North Norway, repeat cytology and the HPV mRNA test PreTect HPV-Proofer, detecting E6/E7 mRNA from HPV types 16, 18, 31, 33 and 45, are used in triage of women with ASC-US and LSIL. In this study, women with LSIL cytology in the period 2005–2008 were included (n = 522). Two triage methods were evaluated in two separate groups: repeat cytology only (n = 225) and HPV mRNA testing in addition to repeat cytology (n = 297). Histologically confirmed cervical intraepithelial neoplasia of grade 2 or worse (CIN2+) was used as the study endpoint. Results Of 522 women with LSIL, 207 had biopsies and 125 of them had CIN2+. The sensitivity and specificity of repeat cytology (ASC-US or worse) were 85.7% (95% confidence interval (CI): 72.1, 92.2) and 54.4 % (95% CI: 46.9, 61.9), respectively. The sensitivity and specificity of the HPV mRNA test were 94.2% (95% CI: 88.7, 99.7) and 86.0% (95% CI: 81.5, 90.5), respectively. The PPV of repeat cytology was 38.4% (95% CI: 29.9, 46.9) compared to 67.0% (95% CI: 57.7, 76.4) of the HPV mRNA test. Conclusion HPV mRNA testing was more sensitive and specific than repeat cytology in triage of women with LSIL cytology. In addition, the HPV mRNA test showed higher PPV. These data indicate that the HPV mRNA test is a better triage test for women with LSIL than repeat cytology. PMID:21918682

Self-guiding of high-intensity laser pulses for laser wake field acceleration

International Nuclear Information System (INIS)

Umstader, D.; Liu, X.

1992-01-01

A means of self-guiding an ultrashort and high-intensity laser pulse is demonstrated both experimentally and numerically. Its relevance to the laser wake field accelerator concept is discussed. Self-focusing and multiple foci formation are observed when a high peak power (P>100 GW), 1 μm, subpicosecond laser is focused onto various gases (air or hydrogen). It appears to result from the combined effects of self-focusing by the gas, and de-focusing both by diffraction and the plasma formed in the central high-intensity region. Quasi-stationary computer simulations show the same multiple foci behavior as the experiments. The results suggest much larger nonlinear electronic susceptibilities of a gas near or undergoing ionization in the high field of the laser pulse. Although self-guiding of a laser beam by this mechanism appears to significantly extend its high-intensity focal region, small-scale self-focusing due to beam non-uniformity is currently a limitation

An Automated Inpatient Split-dose Bowel Preparation System Improves Colonoscopy Quality and Reduces Repeat Procedures.

Science.gov (United States)

Yadlapati, Rena; Johnston, Elyse R; Gluskin, Adam B; Gregory, Dyanna L; Cyrus, Rachel; Werth, Lindsay; Ciolino, Jody D; Grande, David P; Keswani, Rajesh N

2017-07-19

Inpatient colonoscopy preparations are often inadequate, compromising patient safety and procedure quality, while resulting in greater hospital costs. The aims of this study were to: (1) design and implement an electronic inpatient split-dose bowel preparation order set; (2) assess the intervention's impact upon preparation adequacy, repeated colonoscopies, hospital days, and costs. We conducted a single center prospective pragmatic quasiexperimental study of hospitalized adults undergoing colonoscopy. The experimental intervention was designed using DMAIC (define, measure, analyze, improve, and control) methodology. Prospective data collected over 12 months were compared with data from a historical preintervention cohort. The primary outcome was bowel preparation quality and secondary outcomes included number of repeated procedures, hospital days, and costs. On the basis of a Delphi method and DMAIC process, we created an electronic inpatient bowel preparation order set inclusive of a split-dose bowel preparation algorithm, automated orders for rescue medications, and nursing bowel preparation checks. The analysis data set included 969 patients, 445 (46%) in the postintervention group. The adequacy of bowel preparation significantly increased following intervention (86% vs. 43%; P<0.01) and proportion of repeated procedures decreased (2.0% vs. 4.6%; P=0.03). Mean hospital days from bowel preparation initiation to discharge decreased from 8.0 to 6.9 days (P=0.02). The intervention resulted in an estimated 1-year cost-savings of $46,076 based on a reduction in excess hospital days associated with repeated and delayed procedures. Our interdisciplinary initiative targeting inpatient colonoscopy preparations significantly improved quality and reduced repeat procedures, and hospital days. Other institutions should consider utilizing this framework to improve inpatient colonoscopy value.

The energy landscapes of repeat-containing proteins: topology, cooperativity, and the folding funnels of one-dimensional architectures.

Directory of Open Access Journals (Sweden)

Diego U Ferreiro

2008-05-01

Full Text Available Repeat-proteins are made up of near repetitions of 20- to 40-amino acid stretches. These polypeptides usually fold up into non-globular, elongated architectures that are stabilized by the interactions within each repeat and those between adjacent repeats, but that lack contacts between residues distant in sequence. The inherent symmetries both in primary sequence and three-dimensional structure are reflected in a folding landscape that may be analyzed as a quasi-one-dimensional problem. We present a general description of repeat-protein energy landscapes based on a formal Ising-like treatment of the elementary interaction energetics in and between foldons, whose collective ensemble are treated as spin variables. The overall folding properties of a complete "domain" (the stability and cooperativity of the repeating array can be derived from this microscopic description. The one-dimensional nature of the model implies there are simple relations for the experimental observables: folding free-energy (DeltaG(water and the cooperativity of denaturation (m-value, which do not ordinarily apply for globular proteins. We show how the parameters for the "coarse-grained" description in terms of foldon spin variables can be extracted from more detailed folding simulations on perfectly funneled landscapes. To illustrate the ideas, we present a case-study of a family of tetratricopeptide (TPR repeat proteins and quantitatively relate the results to the experimentally observed folding transitions. Based on the dramatic effect that single point mutations exert on the experimentally observed folding behavior, we speculate that natural repeat proteins are "poised" at particular ratios of inter- and intra-element interaction energetics that allow them to readily undergo structural transitions in physiologically relevant conditions, which may be intrinsically related to their biological functions.

Expansion of protein domain repeats.

Directory of Open Access Journals (Sweden)

Asa K Björklund

2006-08-01

Full Text Available Many proteins, especially in eukaryotes, contain tandem repeats of several domains from the same family. These repeats have a variety of binding properties and are involved in protein-protein interactions as well as binding to other ligands such as DNA and RNA. The rapid expansion of protein domain repeats is assumed to have evolved through internal tandem duplications. However, the exact mechanisms behind these tandem duplications are not well-understood. Here, we have studied the evolution, function, protein structure, gene structure, and phylogenetic distribution of domain repeats. For this purpose we have assigned Pfam-A domain families to 24 proteomes with more sensitive domain assignments in the repeat regions. These assignments confirmed previous findings that eukaryotes, and in particular vertebrates, contain a much higher fraction of proteins with repeats compared with prokaryotes. The internal sequence similarity in each protein revealed that the domain repeats are often expanded through duplications of several domains at a time, while the duplication of one domain is less common. Many of the repeats appear to have been duplicated in the middle of the repeat region. This is in strong contrast to the evolution of other proteins that mainly works through additions of single domains at either terminus. Further, we found that some domain families show distinct duplication patterns, e.g., nebulin domains have mainly been expanded with a unit of seven domains at a time, while duplications of other domain families involve varying numbers of domains. Finally, no common mechanism for the expansion of all repeats could be detected. We found that the duplication patterns show no dependence on the size of the domains. Further, repeat expansion in some families can possibly be explained by shuffling of exons. However, exon shuffling could not have created all repeats.

The Effects of Hemodynamic Changes on Pulse Wave Velocity in Cardiothoracic Surgical Patients

Directory of Open Access Journals (Sweden)

Yurie Obata

2016-01-01

Full Text Available The effect of blood pressure on pulse wave velocity (PWV is well established. However, PWV variability with acute hemodynamic changes has not been examined in the clinical setting. The aim of the present study is to investigate the effect of hemodynamic changes on PWV in patients who undergo cardiothoracic surgery. Using data from 25 patients, we determined blood pressure (BP, heart rate (HR, and the left ventricular outflow tract (LVOT velocity-time integral. By superimposing the radial arterial waveform on the continuous wave Doppler waveform of the LVOT, obtained by transesophageal echo, we were able to determine pulse transit time and to calculate PWV, stroke volume (SV, cardiac output (CO, and systemic vascular resistance (SVR. Increases in BP, HR, and SVR were associated with higher values for PWV. In contrast increases in SV were associated with decreases in PWV. Changes in CO were not significantly associated with PWV.

Effects of pulse-to-pulse residual species on discharges in repetitively pulsed discharges through packed bed reactors

Science.gov (United States)

Kruszelnicki, Juliusz; Engeling, Kenneth W.; Foster, John E.; Kushner, Mark J.

2016-09-01

Atmospheric pressure dielectric barrier discharges (DBDs) sustained in packed bed reactors (PBRs) are being investigated for conversion of toxic and waste gases, and CO2 removal. These discharges are repetitively pulsed having varying flow rates and internal geometries, which results in species from the prior pulse still being in the discharge zone at the time the following discharge pulse occurs. A non-negligible residual plasma density remains, which effectively acts as preionization. This residual charge changes the discharge properties of subsequent pulses, and may impact important PBR properties such as chemical selectivity. Similarly, the residual neutral reactive species produced during earlier pulses will impact the reaction rates on subsequent pulses. We report on results of a computational investigation of a 2D PBR using the plasma hydrodynamics simulator nonPDPSIM. Results will be discussed for air flowing though an array of dielectric rods at atmospheric pressure. The effects of inter-pulse residual species on PBR discharges will be quantified. Means of controlling the presence of residual species in the reactor through gas flow rate, pulse repetition, pulse width and geometry will be described. Comparisons will be made to experiments. Work supported by US DOE Office of Fusion Energy Science and the National Science Foundation.

Evaluation of Masimo signal extraction technology pulse oximetry in anaesthetized pregnant sheep.

Science.gov (United States)

Quinn, Christopher T; Raisis, Anthea L; Musk, Gabrielle C

2013-03-01

Evaluation of the accuracy of Masimo signal extraction technology (SET) pulse oximetry in anaesthetized late gestational pregnant sheep. Prospective experimental study. Seventeen pregnant Merino ewes. Animals included in study were late gestation ewes undergoing general anaesthesia for Caesarean delivery or foetal surgery in a medical research laboratory. Masimo Radical-7 pulse oximetry (SpO(2) ) measurements were compared to co-oximetry (SaO(2) ) measurements from arterial blood gas analyses. The failure rate of the pulse oximeter was calculated. Accuracy was assessed by Bland & Altman's (2007) limits of agreement method. The effect of mean arterial blood pressure (MAP), perfusion index (PI) and haemoglobin (Hb) concentration on accuracy were assessed by regression analysis. Forty arterial blood samples paired with SpO(2) and blood pressure measurements were obtained. SpO(2) ranged from 42 to 99% and SaO(2) from 43.7 to 99.9%. MAP ranged from 24 to 82 mmHg, PI from 0.1 to 1.56 and Hb concentration from 71 to 114 g L(-1) . Masimo pulse oximetry measurements tended to underestimate oxyhaemoglobin saturation compared to co-oximetry with a bias (mean difference) of -2% and precision (standard deviation of the differences) of 6%. Accuracy appeared to decrease when SpO(2) was oximeter function during extreme hypotension and hypoxaemia. © 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.

Geophysical data collected during the 2014 minute 319 pulse flow on the Colorado River below Morelos Dam, United States and Mexico

Science.gov (United States)

Kennedy, Jeffrey R.; Callegary, James B.; Macy, Jamie P.; Reyes-Lopez, Jaime; Pérez-Flores, Marco

2017-05-09

Geophysical methods were used to monitor infiltration during a water release, referred to as a “pulse flow,” in the Colorado River delta in March and April 2014. The pulse flow was enabled by Minute 319 of the 1944 United States–Mexico Treaty concerning water of the Colorado River. Fieldwork was carried out by the U.S. Geological Survey and the Centro de Investigación Científica y de Educación Superior de Ensenada as part of a binational effort to monitor the hydrologic effects of the pulse flow along the limitrophe (border) reach of the Colorado River and into Mexico. Repeat microgravity measurements were made at 25 locations in the southern limitrophe reach to quantify aquifer storage change during the pulse flow. Observed increases in storage along the river were greater with distance to the south, and the amount of storage change decreased away from the river channel. Gravity data at four monitoring well sites indicate specific yield equal to 0.32±0.05. Electromagnetic induction methods were used at 12 transects in the limitrophe reach of the river along the United States– Mexico border, and farther south into Mexico. These data, which are sensitive to variation in soil texture and water content, suggest relatively homogeneous conditions. Repeat direct-current resistivity measurements were collected at two locations to monitor groundwater elevation. Results indicate rapid groundwater-level rise during the pulse flow in the limitrophe reach and smaller variation at a more southern transect. Together, these data are useful for hydrogeologic characterization and hydrologic model development. Electronic data files are provided in the accompanying data release (Kennedy and others, 2016a).

Picosecond trigger system useful in mode-locked laser pulse measurements

International Nuclear Information System (INIS)

Cunin, B.; Miehe, J.A.; Sipp, B.; Thebault, J.

1976-01-01

A highly sensitive tunnel diode trigger useful in temporal intensity build-up measurements of mode-locked lasers has been developed; the device reduces notably the time walk due to the lack of repeatability in intensity of the laser output. The performance of the trigger have been established by means of a GHz wideband-0.1V/cm sensitive real-time oscilloscope and of an image converter camera having a picosecond resolution: the experimental results show that a variation of the amplitude of the laser pulse train of a factor 5 leads to a time jitter of less than 30 ps (Auth.)

Investigation of carbon cathode surface before and after the passage of combined dc vacuum arc with superimposed high-current arc pulses

International Nuclear Information System (INIS)

Zavaleyev, V.; Walkowicz, J.; Moszynski, D.

2016-01-01

The paper presents the results of studies of carbon cathode surface before and after the passage of the combined DC vacuum-arc with superimposed high-current arc pulses. Investigations of surface morphology of carbon cathode showed, that secondary nuclei of high-density are formed after passing of the combined DC-pulse vacuum-arc, which results in the formation of a globular structures. The phase structure analysis by Raman spectroscopy showed that even at a minimum operation time (5 s) of the combined DC-pulse vacuum-arc broadening of the peaks 1355 and 1583 cm-1 occurs, which means that the carbon cathode surface undergo phase transformation. Results obtained by XPS spectroscopy demonstrate that the globular structures formed on the cathode surface are composed of sp 3 -bonded carbon atoms and carbon-oxygen bonds.

Repeat cesarean section in subsequent gestation of women from a birth cohort in Brazil.

Science.gov (United States)

Mascarello, Keila Cristina; Matijasevich, Alicia; Barros, Aluísio J D; Santos, Iná S; Zandonade, Eliana; Silveira, Mariângela Freitas

2017-08-25

The current literature indicates increasing concern regarding the number of safe cesarean sections which a woman can undergo, mainly in face of the high cesarean section rates, which are growing in Brazil and worldwide. Aimed to describe the prevalence and associated factors of repeat cesarean section in a cohort of Brazilian women who had a cesarean section in the first birth. This is a prospective cohort study using data from the 2004 Pelotas Birth Cohort. The sample included 480 women who had their first delivery in 2004, regardless of the form of delivery, and who had a second delivery identified in the cohort's follow-ups (in 2005, 2006, 2008, and 2010). Descriptive, bivariate and multivariate analyses using Poisson regression with robust error variance were carried out. Among the women who underwent a cesarean section in their first delivery (49.47%), 87.44% had a second surgical delivery. The risk factors for repeat cesarean section included ages 21-34 (PR 1.67, CI 95% 1.07-2.60), not being seen by SUS (Public Healthcare System) in 2004 (PR 2.27, CI 95% 1.44-3.60), and the number of prenatal medical visits, i.e., women with ten or more visits were at 2.33 times higher risk (CI 95% 1.10-4.96) compared to those who had five or fewer visits. The proportion of cesarean sections both in the first and in the subsequent delivery is quite high. This high rate may compromise the reproductive future of the women who undergo consecutive cesarean sections with possible consequent complications and changes in care policies for pregnant women should be implemented.

The leucine-rich repeat structure.

Science.gov (United States)

Bella, J; Hindle, K L; McEwan, P A; Lovell, S C

2008-08-01

The leucine-rich repeat is a widespread structural motif of 20-30 amino acids with a characteristic repetitive sequence pattern rich in leucines. Leucine-rich repeat domains are built from tandems of two or more repeats and form curved solenoid structures that are particularly suitable for protein-protein interactions. Thousands of protein sequences containing leucine-rich repeats have been identified by automatic annotation methods. Three-dimensional structures of leucine-rich repeat domains determined to date reveal a degree of structural variability that translates into the considerable functional versatility of this protein superfamily. As the essential structural principles become well established, the leucine-rich repeat architecture is emerging as an attractive framework for structural prediction and protein engineering. This review presents an update of the current understanding of leucine-rich repeat structure at the primary, secondary, tertiary and quaternary levels and discusses specific examples from recently determined three-dimensional structures.

Effects of Repeated Stress on Age-Dependent GABAergic Regulation of the Lateral Nucleus of the Amygdala.

Science.gov (United States)

Zhang, Wei; Rosenkranz, J Amiel

2016-08-01

The adolescent age is associated with lability of mood and emotion. The onset of depression and anxiety disorders peaks during adolescence and there are differences in symptomology during adolescence. This points to differences in the adolescent neural circuitry that underlies mood and emotion, such as the amygdala. The human adolescent amygdala is more responsive to evocative stimuli, hinting to less local inhibitory regulation of the amygdala, but this has not been explored in adolescents. The amygdala, including the lateral nucleus (LAT) of the basolateral amygdala complex, is sensitive to stress. The amygdala undergoes maturational processes during adolescence, and therefore may be more vulnerable to harmful effects of stress during this time period. However, little is known about the effects of stress on the LAT during adolescence. GABAergic inhibition is a key regulator of LAT activity. Therefore, the purpose of this study was to test whether there are differences in the local GABAergic regulation of the rat adolescent LAT, and differences in its sensitivity to repeated stress. We found that LAT projection neurons are subjected to weaker GABAergic inhibition during adolescence. Repeated stress reduced in vivo endogenous and exogenous GABAergic inhibition of LAT projection neurons in adolescent rats. Furthermore, repeated stress decreased measures of presynaptic GABA function and interneuron activity in adolescent rats. In contrast, repeated stress enhanced glutamatergic drive of LAT projection neurons in adult rats. These results demonstrate age differences in GABAergic regulation of the LAT, and age differences in the mechanism for the effects of repeated stress on LAT neuron activity. These findings provide a substrate for increased mood lability in adolescents, and provide a substrate by which adolescent repeated stress can induce distinct behavioral outcomes and psychiatric symptoms.

Analyzing repeated measures data on individuals nested within groups: accounting for dynamic group effects.

Science.gov (United States)

Bauer, Daniel J; Gottfredson, Nisha C; Dean, Danielle; Zucker, Robert A

2013-03-01

Researchers commonly collect repeated measures on individuals nested within groups such as students within schools, patients within treatment groups, or siblings within families. Often, it is most appropriate to conceptualize such groups as dynamic entities, potentially undergoing stochastic structural and/or functional changes over time. For instance, as a student progresses through school, more senior students matriculate while more junior students enroll, administrators and teachers may turn over, and curricular changes may be introduced. What it means to be a student within that school may thus differ from 1 year to the next. This article demonstrates how to use multilevel linear models to recover time-varying group effects when analyzing repeated measures data on individuals nested within groups that evolve over time. Two examples are provided. The 1st example examines school effects on the science achievement trajectories of students, allowing for changes in school effects over time. The 2nd example concerns dynamic family effects on individual trajectories of externalizing behavior and depression. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Hysteresis of magnetostructural transitions: Repeatable and non-repeatable processes

Science.gov (United States)

Provenzano, Virgil; Della Torre, Edward; Bennett, Lawrence H.; ElBidweihy, Hatem

2014-02-01

The Gd5Ge2Si2 alloy and the off-stoichiometric Ni50Mn35In15 Heusler alloy belong to a special class of metallic materials that exhibit first-order magnetostructural transitions near room temperature. The magnetic properties of this class of materials have been extensively studied due to their interesting magnetic behavior and their potential for a number of technological applications such as refrigerants for near-room-temperature magnetic refrigeration. The thermally driven first-order transitions in these materials can be field-induced in the reverse order by applying a strong enough field. The field-induced transitions are typically accompanied by the presence of large magnetic hysteresis, the characteristics of which are a complicated function of temperature, field, and magneto-thermal history. In this study we show that the virgin curve, the major loop, and sequentially measured MH loops are the results of both repeatable and non-repeatable processes, in which the starting magnetostructural state, prior to the cycling of field, plays a major role. Using the Gd5Ge2Si2 and Ni50Mn35In15 alloys, as model materials, we show that a starting single phase state results in fully repeatable processes and large magnetic hysteresis, whereas a mixed phase starting state results in non-repeatable processes and smaller hysteresis.

Hysteresis of magnetostructural transitions: Repeatable and non-repeatable processes

International Nuclear Information System (INIS)

Provenzano, Virgil; Della Torre, Edward; Bennett, Lawrence H.; ElBidweihy, Hatem

2014-01-01

The Gd 5 Ge 2 Si 2 alloy and the off-stoichiometric Ni 50 Mn 35 In 15 Heusler alloy belong to a special class of metallic materials that exhibit first-order magnetostructural transitions near room temperature. The magnetic properties of this class of materials have been extensively studied due to their interesting magnetic behavior and their potential for a number of technological applications such as refrigerants for near-room-temperature magnetic refrigeration. The thermally driven first-order transitions in these materials can be field-induced in the reverse order by applying a strong enough field. The field-induced transitions are typically accompanied by the presence of large magnetic hysteresis, the characteristics of which are a complicated function of temperature, field, and magneto-thermal history. In this study we show that the virgin curve, the major loop, and sequentially measured MH loops are the results of both repeatable and non-repeatable processes, in which the starting magnetostructural state, prior to the cycling of field, plays a major role. Using the Gd 5 Ge 2 Si 2 and Ni 50 Mn 35 In 15 alloys, as model materials, we show that a starting single phase state results in fully repeatable processes and large magnetic hysteresis, whereas a mixed phase starting state results in non-repeatable processes and smaller hysteresis

Revisiting the TALE repeat.

Science.gov (United States)

Deng, Dong; Yan, Chuangye; Wu, Jianping; Pan, Xiaojing; Yan, Nieng

2014-04-01

Transcription activator-like (TAL) effectors specifically bind to double stranded (ds) DNA through a central domain of tandem repeats. Each TAL effector (TALE) repeat comprises 33-35 amino acids and recognizes one specific DNA base through a highly variable residue at a fixed position in the repeat. Structural studies have revealed the molecular basis of DNA recognition by TALE repeats. Examination of the overall structure reveals that the basic building block of TALE protein, namely a helical hairpin, is one-helix shifted from the previously defined TALE motif. Here we wish to suggest a structure-based re-demarcation of the TALE repeat which starts with the residues that bind to the DNA backbone phosphate and concludes with the base-recognition hyper-variable residue. This new numbering system is consistent with the α-solenoid superfamily to which TALE belongs, and reflects the structural integrity of TAL effectors. In addition, it confers integral number of TALE repeats that matches the number of bound DNA bases. We then present fifteen crystal structures of engineered dHax3 variants in complex with target DNA molecules, which elucidate the structural basis for the recognition of bases adenine (A) and guanine (G) by reported or uncharacterized TALE codes. Finally, we analyzed the sequence-structure correlation of the amino acid residues within a TALE repeat. The structural analyses reported here may advance the mechanistic understanding of TALE proteins and facilitate the design of TALEN with improved affinity and specificity.

Effect of tendon vibration during wide-pulse neuromuscular electrical stimulation (NMES) on muscle force production in people with spinal cord injury (SCI).

Science.gov (United States)

Bochkezanian, Vanesa; Newton, Robert U; Trajano, Gabriel S; Vieira, Amilton; Pulverenti, Timothy S; Blazevich, Anthony J

2018-02-13

Neuromuscular electrical stimulation (NMES) is commonly used in skeletal muscles in people with spinal cord injury (SCI) with the aim of increasing muscle recruitment and thus muscle force production. NMES has been conventionally used in clinical practice as functional electrical stimulation (FES), using low levels of evoked force that cannot optimally stimulate muscular strength and mass improvements, and thus trigger musculoskeletal changes in paralysed muscles. The use of high intensity intermittent NMES training using wide-pulse width and moderate-intensity as a strength training tool could be a promising method to increase muscle force production in people with SCI. However, this type of protocol has not been clinically adopted because it may generate rapid muscle fatigue and thus prevent the performance of repeated high-intensity muscular contractions in paralysed muscles. Moreover, superimposing patellar tendon vibration onto the wide-pulse width NMES has been shown to elicit further increases in impulse or, at least, reduce the rate of fatigue in repeated contractions in able-bodied populations, but there is a lack of evidence to support this argument in people with SCI. Nine people with SCI received two NMES protocols with and without superimposing patellar tendon vibration on different days (i.e. STIM and STIM+vib), which consisted of repeated 30 Hz trains of 58 wide-pulse width (1000 μs) symmetric biphasic pulses (0.033-s inter-pulse interval; 2 s stimulation train; 2-s inter-train interval) being delivered to the dominant quadriceps femoris. Starting torque was 20% of maximal doublet-twitch torque and stimulations continued until torque declined to 50% of the starting torque. Total knee extensor impulse was calculated as the primary outcome variable. Total knee extensor impulse increased in four subjects when patellar tendon vibration was imposed (59.2 ± 15.8%) but decreased in five subjects (- 31.3 ± 25.7%). However, there were no

All-photonic quantum repeaters

Science.gov (United States)

Azuma, Koji; Tamaki, Kiyoshi; Lo, Hoi-Kwong

2015-01-01

Quantum communication holds promise for unconditionally secure transmission of secret messages and faithful transfer of unknown quantum states. Photons appear to be the medium of choice for quantum communication. Owing to photon losses, robust quantum communication over long lossy channels requires quantum repeaters. It is widely believed that a necessary and highly demanding requirement for quantum repeaters is the existence of matter quantum memories. Here we show that such a requirement is, in fact, unnecessary by introducing the concept of all-photonic quantum repeaters based on flying qubits. In particular, we present a protocol based on photonic cluster-state machine guns and a loss-tolerant measurement equipped with local high-speed active feedforwards. We show that, with such all-photonic quantum repeaters, the communication efficiency scales polynomially with the channel distance. Our result paves a new route towards quantum repeaters with efficient single-photon sources rather than matter quantum memories. PMID:25873153

FY 1999 report on the results of the R and D of femtosecond technology. Development of ultra-short pulse optoelectronics technology; 1999 nendo femutobyo technology no kenkyu kaihatsu seika hokokusho. Chotan pulse hikari electronics gijutsu kaihatsu

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-03-01

The paper described the FY 1999 results of the R and D of femtosecond technology. For the purpose of creating new industrial basement technology which supports the highly information-oriented society in the 21st century, the ultra-high speed electronics technology is indispensable which is beyond speed limits of the existing electronics technology and has new functionality. The ultra-high speed electronics basement technology is established through the R and D of the technology to control the state of light and electronics in the femtosecond time domain (10{sup -15} - 10{sup -12} second). Themes of the R and D are technology to generate/transmit femtosecond optical pulse, technology for control/distribution, and ultra-short pulse optoelectronics common basement technology. In FY 1999, a lot of results were obtained in the following: generation of the pulse train highly repeated at 500GHz in semiconductor laser; 139km transmission of 250fs optical pulse; switching movement at ultra-high speed of 150fs-1.2ps in transition among subbands of GaN base and Sb base materials; DEMUXA movement toward 160-10Gb/s in Mach-Zehnder type optical switch. (NEDO)

Risk factors for blood transfusion in patients undergoing high-order Cesarean delivery.

Science.gov (United States)

Spiegelman, Jessica; Mourad, Mirella; Melka, Stephanie; Gupta, Simi; Lam-Rachlin, Jennifer; Rebarber, Andrei; Saltzman, Daniel H; Fox, Nathan S

2017-11-01

The objective was to identify risk factors associated with blood transfusion in patients undergoing high-order Cesarean delivery (CD). This was a retrospective cohort study of patients undergoing third or more CD by a single maternal-fetal medicine practice between 2005 and 2016. We compared risk factors between women who did and did not receive a red blood cell transfusion during the operation or before discharge. Repeat analysis was performed after excluding women with placenta previa. A total of 514 patients were included, 18 of whom (3.5%; 95% confidence interval [CI], 2.2%-5.5%) received a blood transfusion. Placenta previa was the most significant risk factor for transfusion (61.1% of patients who received a transfusion vs. 1% of patients who did not; p blood transfusion. After women who had placenta previa were excluded, the incidence of blood transfusion was seven of 498 (1.4%; 95% CI, 0.7%-2.9%). Risk factors significantly associated with blood transfusion in the absence of previa were prophylactic anticoagulation during pregnancy and having labored. The incidence of transfusion in patients with no placenta previa, no anticoagulation, and no labor was 0.7% (95% CI, 0.3%-2.1%). Placenta previa was the most predictive risk factor for transfusion with a positive predictive value of 68.8% and a negative predictive value of 98.4%. In patients undergoing a third or more CD, only placenta previa, prophylactic anticoagulation during pregnancy, and having labored are independently associated with requiring a blood transfusion. These data can be used to guide physician ordering of prepared blood products preoperatively. © 2017 AABB.

Numerical design of RNnν symmetry-based RF pulse schemes for recoupling and decoupling of nuclear spin interactions at high MAS frequencies

International Nuclear Information System (INIS)

Herbst, Christian; Herbst, Jirada; Leppert, Joerg; Ohlenschlaeger, Oliver; Goerlach, Matthias; Ramachandran, Ramadurai

2009-01-01

An approach for the efficient implementation of RN n ν symmetry-based pulse schemes that are often employed for recoupling and decoupling of nuclear spin interactions in biological solid state NMR investigations is demonstrated at high magic-angle spinning frequencies. RF pulse sequences belonging to the RN n ν symmetry involve the repeated application of the pulse sandwich {R φ R -φ }, corresponding to a propagator U RF = exp(-i4φI z ), where φ = πν/N and R is typically a pulse that rotates the nuclear spins through 180 o about the x-axis. In this study, broadband, phase-modulated 180 o pulses of constant amplitude were employed as the initial 'R' element and the phase-modulation profile of this 'R' element was numerically optimised for generating RN n ν symmetry-based pulse schemes with satisfactory magnetisation transfer characteristics. At representative MAS frequencies, RF pulse sequences were implemented for achieving 13 C- 13 C double-quantum dipolar recoupling and through bond scalar coupling mediated chemical shift correlation and evaluated via numerical simulations and experimental measurements. The results from these investigations are presented here

Characteristics of bipolar-pulse generator for intense pulsed heavy ion beam acceleration

International Nuclear Information System (INIS)

Igawa, K.; Tomita, T.; Kitamura, I.; Ito, H.; Masugata, K.

2006-01-01

Intense pulsed heavy ion beams are expected to be applied to the implantation technology for semiconductor materials. In the application it is very important to purify the ion beam. In order to improve the purity of an intense pulsed ion beams we have proposed a new type of pulsed ion beam accelerator named 'bipolar pulse accelerator (BPA)'. A prototype of the experimental system has been developed to perform proof of principle experiments of the accelerator. A bipolar pulse generator has been designed for the generation of the pulsed ion beam with the high purity via the bipolar pulse acceleration and the electrical characteristics of the generator were evaluated. The production of the bipolar pulse has been confirmed experimentally. (author)

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

Science.gov (United States)

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

2013-04-01

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

Development of the pulse transformer for NLC klystron pulse modulator

International Nuclear Information System (INIS)

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

1997-05-01

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

Dynamic Characterization of Fiber Optical Chirped Pulse Amplification for Sub-ps Pulses

DEFF Research Database (Denmark)

Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Rishøj, Lars Søgaard

2013-01-01

We investigate experimentally the propagation of sub-picosecond pulses in fiber optical parametric chirped pulse amplifiers, showing a significant broadening of the pulses from 450 fs up to 720 fs due to dispersion and self-phase modulation.......We investigate experimentally the propagation of sub-picosecond pulses in fiber optical parametric chirped pulse amplifiers, showing a significant broadening of the pulses from 450 fs up to 720 fs due to dispersion and self-phase modulation....

Petawatt pulsed-power accelerator

Science.gov (United States)

Stygar, William A.; Cuneo, Michael E.; Headley, Daniel I.; Ives, Harry C.; Ives, legal representative; Berry Cottrell; Leeper, Ramon J.; Mazarakis, Michael G.; Olson, Craig L.; Porter, John L.; Wagoner; Tim C.

2010-03-16

A petawatt pulsed-power accelerator can be driven by various types of electrical-pulse generators, including conventional Marx generators and linear-transformer drivers. The pulsed-power accelerator can be configured to drive an electrical load from one- or two-sides. Various types of loads can be driven; for example, the accelerator can be used to drive a high-current z-pinch load. When driven by slow-pulse generators (e.g., conventional Marx generators), the accelerator comprises an oil section comprising at least one pulse-generator level having a plurality of pulse generators; a water section comprising a pulse-forming circuit for each pulse generator and a level of monolithic triplate radial-transmission-line impedance transformers, that have variable impedance profiles, for each pulse-generator level; and a vacuum section comprising triplate magnetically insulated transmission lines that feed an electrical load. When driven by LTD generators or other fast-pulse generators, the need for the pulse-forming circuits in the water section can be eliminated.

What is the best site for measuring the effect of ventilation on the pulse oximeter waveform?

Science.gov (United States)

Shelley, Kirk H; Jablonka, Denis H; Awad, Aymen A; Stout, Robert G; Rezkanna, Hoda; Silverman, David G

2006-08-01

The cardiac pulse is the predominant feature of the pulse oximeter (plethysmographic) waveform. Less obvious is the effect of ventilation on the waveform. There have been efforts to measure the effect of ventilation on the waveform to determine respiratory rate, tidal volume, and blood volume. We measured the relative strength of the effect of ventilation on the reflective plethysmographic waveform at three different sites: the finger, ear, and forehead. The plethysmographic waveforms from 18 patients undergoing positive pressure ventilation during surgery and 10 patients spontaneously breathing during renal dialysis were collected. The respiratory signal was isolated from the waveform using spectral analysis. It was found that the respiratory signal in the pulse oximeter waveform was more than 10 times stronger in the region of the head when compared with the finger. This was true with both controlled positive pressure ventilation and spontaneous breathing. A significant correlation was demonstrated between the estimated blood loss from surgical procedures and the impact of ventilation on ear plethysmographic data (r(s) = 0.624, P = 0.006).

Pulse transformer R and D for NLC klystron pulse modulator

International Nuclear Information System (INIS)

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

1997-07-01

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

Random pulse generator

International Nuclear Information System (INIS)

Guo Ya'nan; Jin Dapeng; Zhao Dixin; Liu Zhen'an; Qiao Qiao; Chinese Academy of Sciences, Beijing

2007-01-01

Due to the randomness of radioactive decay and nuclear reaction, the signals from detectors are random in time. But normal pulse generator generates periodical pulses. To measure the performances of nuclear electronic devices under random inputs, a random generator is necessary. Types of random pulse generator are reviewed, 2 digital random pulse generators are introduced. (authors)

Fiber Optical Parametric Chirped Pulse Amplification of Sub-Picosecond Pulses

DEFF Research Database (Denmark)

Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Da Ros, Francesco

2013-01-01

We demonstrate experimentally, for the first time to our knowledge, fiber optical parametric chirped pulse amplification of 400-fs pulses. The 400-fs signal is stretched, amplified by 26 dB and compressed back to 500 fs.......We demonstrate experimentally, for the first time to our knowledge, fiber optical parametric chirped pulse amplification of 400-fs pulses. The 400-fs signal is stretched, amplified by 26 dB and compressed back to 500 fs....

Pulse to pulse klystron diagnosis system

International Nuclear Information System (INIS)

Nowak, J.; Davidson, V.; Genova, L.; Johnson, R.; Reagan, D.

1981-03-01

This report describes a system used to study the behavior of SLAC high powered klystrons operating with a twice normal pulse width of 5 μs. At present, up to eight of the klystrons installed along the accelerator can be operated with long pulses and monitored by this system. The report will also discuss some of the recent findings and investigations

Efficient chirped-pulse amplification of sub-20 fs laser pulses

Energy Technology Data Exchange (ETDEWEB)

Matsuoka, Shinichi; Yamakawa, Koichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-03-01

We have developed a model for ultrabroadband and ultrashort pulse amplification including the effects of a pulse shaper for regenerative pulse shaping, gain narrowing and gain saturation in the amplifiers. Thin solid etalons are used to control both gain narrowing and gain saturation during amplification. This model has been used to design an optimized Ti:sapphire amplifier system for producing efficiently pulses of < 20-fs duration with approaching peak and average powers of 100 TW and 20 W. (author)

Patterns of digital volume pulse waveform and pulse transit time in ...

African Journals Online (AJOL)

In this study the digital volume pulse wave and the pulse transit time of the thumb and big toe were analyzed in young and older subjects some of whom were hypertensive. We aimed to study the components and patterns of the pulse waveform and the pulse transit time and how they might change. Material and Methods: ...

A three-barrel repeating pneumatic pellet injector for plasma fueling of the Joint European Torus

International Nuclear Information System (INIS)

Combs, S.K.; Milora, S.L.; Baylor, L.R.; Foust, C.R.; Gethers, F.E.; Sparks, D.O.

1987-01-01

Pellet fueling, the injection of frozen hydrogen isotope pellets at high velocity, has been used to improve plasma performance in various tokamak experiments. In one recent experiment, the repeating pneumatic hydrogen pellet injector was used on the Tokamak Fusion Test Reactor (TFTR). This machine gun-like device, which was developed at the Oak Ridge National Laboratory (ORNL) with an objective of steady-state fueling applications, was characterized by a fixed pellet size and a maximum repetition rate of 4 to 6 Hz for several seconds. It was used to deliver deuterium pellets at speeds ranging from 1.0 to 1.5 km/s into TFTR plasma discharges. In the first experiments, injection of single, large (nominal 4-mm-diam) pellets provided high plasma densities in TFTR (1.8 x 10 14 cm -3 on axis). After a conversion to smaller (nominal 2.7-mm-diam) pellets, the pellet injector was operated in the repeating mode to gradually increase the plasma density, injecting up to five pellets on a single machine pulse. This resulted in central plasma densities approaching 4 x 10 14 cm -3 and n tau values of 1.4 x 10 14 cm -3 s. For plasma fueling applications on the Joint European Torus (JET), a pellet injector fashioned after the prototype repeating pneumatic design has been developed. The versatile injector features three repeating guns in a common vacuum enclosure; the guns provide pellets that are 2.7, 4.0, and 6.0 mm in diameter and can operate independently at repetition rates of 5, 2.5, and 1 Hz, respectively. The injector has been installed on JET. A description of the equipment is presented, emphasizing the differences from the original repeating device. Performance characteristics of the three pneumatic guns are also included

78 FR 65594 - Vehicular Repeaters

Science.gov (United States)

2013-11-01

... coordinators estimate the effect on coordination fees? Does the supposed benefit that mobile repeater stations... allow the licensing and operation of vehicular repeater systems and other mobile repeaters by public... email: [email protected] or phone: 202-418- 0530 or TTY: 202-418-0432. For detailed instructions for...

A 350 KV nanosecond pulse voltage generator with adjustable pulsed-width

International Nuclear Information System (INIS)

Wang, X.; Wang, M.; Chen, Y.Q.; Zeng, L.G.; Han, M.

2002-01-01

This paper presents a 350 kV nanosecond pulse voltage generator (NPVG). The voltage pulsed-width can be adjusted from 30 to 160 ns. The generator consists of: Marx generator, pulsed forming line (PFL), main switch and matched impedance. The output voltage of Marx generator is over than nU c (n- the stage number of Marx generator, U c -the charging voltage of capacitor). When the pulse forming line is terminated with an impedance that is over than the characteristic impedance of PFL, the higher voltage pulse was provided for the load

The use of joint time frequency analysis to quantify the effect of ventilation on the pulse oximeter waveform.

Science.gov (United States)

Shelley, Kirk H; Awad, Aymen A; Stout, Robert G; Silverman, David G

2006-04-01

In the process of determining oxygen saturation, the pulse oximeter functions as a photoelectric plethysmograph. By analyzing how the frequency spectrum of the pulse oximeter waveform changes over time, new clinically relevant features can be extracted. Thirty patients undergoing general anesthesia for abdominal surgery had their pulse oximeter, airway pressure and CO(2) waveforms collected (50 Hz). The pulse oximeter waveform was analyzed with a short-time Fourier transform using a moving 4096 point Hann window of 82 seconds duration. The frequency signal created by positive pressure ventilation was extracted using a peak detection algorithm in the frequency range of ventilation (0.08-0.4 Hz = 5-24 breaths/minute). The respiratory rate derived in this manner was compared to the respiratory rate as determined by CO(2) detection. In total, 52 hours of telemetry data were analyzed. The respiratory rate measured from the pulse oximeter waveform was found to have a 0.89 linear correlation when compared to CO(2) detection and airway pressure change. the bias was 0.03 breath/min, SD was 0.557 breath/min and the upper and lower limits of agreement were 1.145 and -1.083 breath/min respectively. The presence of motion artifact proved to be the primary cause of failure of this technique. Joint time frequency analysis of the pulse oximeter waveform can be used to determine the respiratory rate of ventilated patients and to quantify the impact of ventilation on the waveform. In addition, when applied to the pulse oximeter waveform new clinically relevant features were observed.

Tevatron serial data repeater system

International Nuclear Information System (INIS)

Ducar, R.J.

1981-01-01

A ten megabit per second serial data repeater system has been developed for the 6.28km Tevatron accelerator. The repeaters are positioned at each of the thirty service buildings and accommodate control and abort system communications as well as distribution of the Tevatron time and energy clocks. The repeaters are transparent to the particular protocol of the transmissions. Serial data are encoded locally as unipolar two volt signals employing the self-clocking Manchester Bi-Phase code. The repeaters modulate the local signals to low-power bursts of 50 MHz rf carrier for the 260m transmission between service buildings. The repeaters also demodulate the transmission and restructure the data for local utilization. The employment of frequency discrimination techniques yields high immunity to the characteristic noise spectrum

Repeat Customer Success in Extension

Science.gov (United States)

Bess, Melissa M.; Traub, Sarah M.

2013-01-01

Four multi-session research-based programs were offered by two Extension specialist in one rural Missouri county. Eleven participants who came to multiple Extension programs could be called "repeat customers." Based on the total number of participants for all four programs, 25% could be deemed as repeat customers. Repeat customers had…

Film repeats in radiology department

International Nuclear Information System (INIS)

Suwan, A. Z.; Al-Shakharah, A. I

1997-01-01

During a one year period, 4910 radiographs of 55780 films were repeated. The objective of our study was to analyse and to classify the causes in order to minimize the repeats, cut the expenses and to provide optimal radiographs for accurate diagnosis. Analysis of the different factors revealed that, 43.6% of film repeats in our service were due to faults in exposure factors, centering comprises 15.9% of the repeats, while too much collimation was responsible for 7.6% of these repeats. All of which can be decreased by awareness and programmed training of technicians. Film blurring caused by patient motion was also responsible for 4.9% for radiographs reexamination, which can be minimized by detailed explanation to the patient and providing the necessary privacy. Fogging of X-Ray films by improper storage or inadequate handling or processing faults were responsible for 14.5% in repeats in our study. Methods and criteria for proper storage and handling of films were discussed. Recommendation for using modern day-light and laser processor has been high lighted. Artefacts are noticeably high in our cases, due to spinal dresses and frequent usage of precious metals for c osmotic purposes in this part of the world. The repeated films comprise 8.8% of all films We conclude that, the main factor responsible for repeats of up to 81.6% of cases was the technologists, thus emphasizing the importance of adequate training of the technologists. (authors). 15 refs., 9 figs., 1 table

Repeat migration and disappointment.

Science.gov (United States)

Grant, E K; Vanderkamp, J

1986-01-01

This article investigates the determinants of repeat migration among the 44 regions of Canada, using information from a large micro-database which spans the period 1968 to 1971. The explanation of repeat migration probabilities is a difficult task, and this attempt is only partly successful. May of the explanatory variables are not significant, and the overall explanatory power of the equations is not high. In the area of personal characteristics, the variables related to age, sex, and marital status are generally significant and with expected signs. The distance variable has a strongly positive effect on onward move probabilities. Variables related to prior migration experience have an important impact that differs between return and onward probabilities. In particular, the occurrence of prior moves has a striking effect on the probability of onward migration. The variable representing disappointment, or relative success of the initial move, plays a significant role in explaining repeat migration probabilities. The disappointment variable represents the ratio of actural versus expected wage income in the year after the initial move, and its effect on both repeat migration probabilities is always negative and almost always highly significant. The repeat probabilities diminish after a year's stay in the destination region, but disappointment in the most recent year still has a bearing on the delayed repeat probabilities. While the quantitative impact of the disappointment variable is not large, it is difficult to draw comparisons since similar estimates are not available elsewhere.

Quantum repeated games revisited

International Nuclear Information System (INIS)

Frąckiewicz, Piotr

2012-01-01

We present a scheme for playing quantum repeated 2 × 2 games based on Marinatto and Weber’s approach to quantum games. As a potential application, we study the twice repeated Prisoner’s Dilemma game. We show that results not available in the classical game can be obtained when the game is played in the quantum way. Before we present our idea, we comment on the previous scheme of playing quantum repeated games proposed by Iqbal and Toor. We point out the drawbacks that make their results unacceptable. (paper)

Optical pulse compression

International Nuclear Information System (INIS)

Glass, A.J.

1975-01-01

The interest in using large lasers to achieve a very short and intense pulse for generating fusion plasma has provided a strong impetus to reexamine the possibilities of optical pulse compression at high energy. Pulse compression allows one to generate pulses of long duration (minimizing damage problems) and subsequently compress optical pulses to achieve the short pulse duration required for specific applications. The ideal device for carrying out this program has not been developed. Of the two approaches considered, the Gires--Tournois approach is limited by the fact that the bandwidth and compression are intimately related, so that the group delay dispersion times the square of the bandwidth is about unity for all simple Gires--Tournois interferometers. The Treacy grating pair does not suffer from this limitation, but is inefficient because diffraction generally occurs in several orders and is limited by the problem of optical damage to the grating surfaces themselves. Nonlinear and parametric processes were explored. Some pulse compression was achieved by these techniques; however, they are generally difficult to control and are not very efficient. (U.S.)

Pulse induction heating

Energy Technology Data Exchange (ETDEWEB)

Vasiliev, A S; Kachanov, B Y; Kogan, B V

1993-12-31

Induction heating and three types of pulse processes were studied. It was found that in pulse processes the frequency and pulse duration of heat treatments do not remain constant. High frequency pulse heat treatments can be used on sprayed coatings; such treatments will result in stronger surfaces with no cracks. For induction hardening, the rate of specific power was 1 to 1.5 kW/sq.cm, for forging it was 0.2 to 0.3 kW/sq.cm and for melting it was 0.05 to 0.1 kW/sq.cm. The application of pulse heating will result in higher rates of specific power.

Pulse-shaping mechanism in colliding-pulse mode-locked laser diodes

DEFF Research Database (Denmark)

Bischoff, Svend; Sørensen, Mads Peter; Mørk, J.

1995-01-01

The large signal dynamics of passively colliding pulse mode-locked laser diodes is studied. We derive a model which explains modelocking via the interplay of gain and loss dynamics; no bandwidth limiting element is necessary for pulse formation. It is found necessary to have both fast and slow...... absorber dynamics to achieve mode-locking. Significant chirp is predicted for pulses emitted from long lasers, in agreement with experiment. The pulse width shows a strong dependence on both cavity and saturable absorber length. (C) 1995 American Institute of Physics....

A new method for in-situ filter testing using pulses of aerosol and photometric detection with computer control

International Nuclear Information System (INIS)

Marshall, P.R.C.; Bosley, R.B.

1993-01-01

This paper describes a new technique, developed at the Harwell Laboratory, for the in-situ testing of High Efficiency Particulate Air (HEPA) filters using multiple pulses of test aerosol. The pulse test apparatus consists of a modified forward light scattering photometer coupled to a portable micro-computer fitted with an external data acquisition and control card. The micro-computer switches an aerosol generator on and off via an external relay driver unit. Using this apparatus the filter bank is challenged by a small number of equal length, constant concentration, pulses of aerosol at timed intervals. The aerosol concentration data upstream of the filter bank is logged, to disk, by the computer. The process is then repeated for the downstream concentration with the photometer gain increased to give maximum sensitivity. The collected data is analysed using a computer spread-sheet package; the recorded aerosol pulses are combined, integrated and the background data subtracted; the downstream data is then divided by the upstream pulse data to give the filter penetration. Using this technique the sensitivity of the in-situ filter test has been greatly improved, penetrations approaching 10 -5 % can now be measured, allowing HEPA filters mounted in series to be successfully tested. In addition, filter loading is reduced considerably

S100 lathe bed pulse generator applied to pulsed nuclear magnetic resonance

International Nuclear Information System (INIS)

Cernicchiaro, G.R.C.; Rudge, M.G.; Albuquerque, M.P.

1989-01-01

The project and construction of four channel pulse generator in the S100 standard plate and its control software for microcomputer are described. The microcomputer has total control on the pulse generator, which has seven programable parameters, defining the position of four pulses and the width for the three first ones. This pulse generator is controlled by a software developed in c language, and is used in pulsed nuclear magnetic resonance experiences. (M.C.K.) [pt

Onset of Coulomb explosion in small silicon clusters exposed to strong-field laser pulses

Science.gov (United States)

Sayres, S. G.; Ross, M. W.; Castleman, A. W., Jr.

2012-05-01

It is now well established that, under intense laser illumination, clusters undergo enhanced ionization compared to their isolated atomic and molecular counterparts being subjected to the same pulses. This leads to extremely high charge states and concomitant Coulomb explosion. Until now, the cluster size necessary for ionization enhancement has not been quantified. Here, we demonstrate that through the comparison of ion signal from small covalently bound silicon clusters exposed to low intensity laser pulses with semi-classical theory, their ionization potentials (IPs) can be determined. At moderate laser intensities the clusters are not only atomized, but all valence electrons are removed from the cluster, thereby producing up to Si4+. The effective IPs for the production of the high charge states are shown to be ˜40% lower than the expected values for atomic silicon. Finally, the minimum cluster size responsible for the onset of the enhanced ionization is determined utilizing the magnitude of the kinetic energy released from the Coulomb explosion.

N-polar InGaN-based LEDs fabricated on sapphire via pulsed sputtering

OpenAIRE

Kohei Ueno; Eiji Kishikawa; Jitsuo Ohta; Hiroshi Fujioka

2017-01-01

High-quality N-polar GaN epitaxial films with an atomically flat surface were grown on sapphire (0001) via pulsed sputtering deposition, and their structural and electrical properties were investigated. The crystalline quality of N-polar GaN improves with increasing film thickness and the full width at half maximum values of the x-ray rocking curves for 0002 and 101¯2 diffraction were 313 and 394 arcsec, respectively, at the film thickness of 6μm. Repeatable p-type doping in N-polar GaN films...

Serum caffeine levels after 24 hours of caffeine abstention: observations on clinical patients undergoing myocardial perfusion imaging with dipyridamole or adenosine

International Nuclear Information System (INIS)

Jacobson, A.F.; Cerqueira, M.D.; Raisys, V.; Shattuc, S.

1994-01-01

Although caffeine attenuates the vasodilatation produced by dipyridamole and adenosine, and is therefore contraindicated when these agents are used for myocardial perfusion scintigraphy, caffeine levels in clinical patients undergoing standard imaging protocols have not been studied. Eighty-six patients undergoing clinically indicated intravenous dipyridamole (n=75) or adenosine (n=11) thallium-201 myocardial perfusion scintigraphy, all of whom reported abstention from products containing caffeine for 24 h, were studied prospectively. Blood samples were drawn prior to initiation of the pharmacologic infusion, and serum caffeine levels were determined using an enzyme immunoassay technique. Results of these determinations were correlated with maximum pulse and blood pressure changes measured during and immediately after the stressor infusion, and thallium imaging findings. Detectable caffeine levels were found in 34 patients (40%), ranging from 0.1 to 5.0 mg/l. There was no significant difference in mean systolic blood pressure decrease or mean pulse increase between patients with caffeine levels > 1.0 mg/l (20.4 ± 18.2 mmHg, 11.0 ± 8.9 BPM; n=5) and those with lower (0.1 to 0.9 mg/l) (15.4 ± 9.5 mmHg, 14.4 ± 8.2 BPM; n=29) or no detectable caffeine levels (18.0 ± 11.5 mmHg, 16.6 ± 10.1 BPM; n=52). Redistribution on thallium imaging was also identified with a similar frequency in these three groups (2/5, 40%; 8/29, 28%; 22/52, 42% respectively). (orig.)

Serum caffeine levels after 24 hours of caffeine abstention: observations on clinical patients undergoing myocardial perfusion imaging with dipyridamole or adenosine

Energy Technology Data Exchange (ETDEWEB)

Jacobson, A.F. (Nuclear Medicine Section, Dept. of Veterans Affairs Medical Center, Seattle, WA (United States) Univ. of Washington, Seattle, WA (United States)); Cerqueira, M.D. (Nuclear Medicine Section, Dept. of Veterans Affairs Medical Center, Seattle, WA (United States) Univ. of Washington, Seattle, WA (United States)); Raisys, V. (Dept. of Lab. Medicine, Harborview Medical Center, Seattle, WA (United States) Univ. of Washington, Seattle, WA (United States)); Shattuc, S. (Univ. of Washington, Seattle, WA (United States))

1994-01-01

Although caffeine attenuates the vasodilatation produced by dipyridamole and adenosine, and is therefore contraindicated when these agents are used for myocardial perfusion scintigraphy, caffeine levels in clinical patients undergoing standard imaging protocols have not been studied. Eighty-six patients undergoing clinically indicated intravenous dipyridamole (n=75) or adenosine (n=11) thallium-201 myocardial perfusion scintigraphy, all of whom reported abstention from products containing caffeine for 24 h, were studied prospectively. Blood samples were drawn prior to initiation of the pharmacologic infusion, and serum caffeine levels were determined using an enzyme immunoassay technique. Results of these determinations were correlated with maximum pulse and blood pressure changes measured during and immediately after the stressor infusion, and thallium imaging findings. Detectable caffeine levels were found in 34 patients (40%), ranging from 0.1 to 5.0 mg/l. There was no significant difference in mean systolic blood pressure decrease or mean pulse increase between patients with caffeine levels > 1.0 mg/l (20.4 [+-] 18.2 mmHg, 11.0 [+-] 8.9 BPM; n=5) and those with lower (0.1 to 0.9 mg/l) (15.4 [+-] 9.5 mmHg, 14.4 [+-] 8.2 BPM; n=29) or no detectable caffeine levels (18.0 [+-] 11.5 mmHg, 16.6 [+-] 10.1 BPM; n=52). Redistribution on thallium imaging was also identified with a similar frequency in these three groups (2/5, 40%; 8/29, 28%; 22/52, 42% respectively). (orig.)

Laser pulse stacking method

Science.gov (United States)

Moses, E.I.

1992-12-01

A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter. 2 figs.

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

Science.gov (United States)

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

2004-01-01

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

Muscle oxygenation of vastus lateralis and medialis muscles during alternating and pulsed current electrical stimulation.

Science.gov (United States)

Aldayel, Abdulaziz; Muthalib, Makii; Jubeau, Marc; McGuigan, Michael; Nosaka, Kazunori

2011-05-01

This study compared between alternating and pulsed current electrical muscle stimulation (EMS) for muscle oxygenation and blood volume during isometric contractions. Nine healthy men (23-48 years) received alternating current EMS (2500 Hz) modulated at 75 Hz on the knee extensors of one leg, and pulsed current EMS (75 Hz) for the other leg separated by 2 weeks in a randomised, counter-balanced order. Pulse duration (400 μs), on-off ratio (5-15 s) and other stimulation parameters were matched between conditions and 30 isometric contractions were induced at the knee joint angle of 100° (0° full extension). Changes in tissue oxygenation index (∆TOI) and total hemoglobin volume (∆tHb) of vastus lateralis and medialis muscles over 30 contractions were assessed by a near-infrared spectroscopy, and were compared between conditions by a two-way repeated measures ANOVA. Peak torque produced during EMS increased over 30 contractions in response to the increase in the stimulation intensity for pulsed current, but not for the alternating current EMS. The torque during each isometric contraction was less stable in alternating than pulsed current EMS. The changes in ∆TOI amplitude during relaxation phases and ∆tHb amplitude were not significantly different between conditions. However, the decreases in ∆TOI amplitude during contraction phases from baseline were significantly (P < 0.05) greater for the pulsed current than alternating current from the 18th contraction (-15.6 ± 2.3 vs. -8.9 ± 1.8%) to 30th contraction (-10.7 ± 1.8 vs. -4.8 ± 1.5%). These results suggest that the muscles were less activated in the alternating current EMS when compared with the pulsed current EMS.

Development of long life pulse power supply for copper vapor laser. Do joki laser yo chojumyo reiki dengen no kaihatsu. ; Saidai shutsuryoku unten oyobi laser hasshin

Energy Technology Data Exchange (ETDEWEB)

Fujii, T.; Goto, N.; Nemoto, K. (Central Research Inst. of Electric Power Industry, Tokyo (Japan))

1990-04-01

Long life pulse power supply for Cu vapor laser was developed. This is composed of the pulse generation circuit and the pulse compression circuit. Current pulse of 10 mu second pulse width is generated in the pulse generating circuit by switching electric charge on the condensor charged through GTO (gate turn off) thyristors. The pulse compression circuit makes the current pulse fast to 300ms utilizing the difference of inductance at the saturation and the unsaturation on the circuit which uses a reactor having saturable property using a ferromagnetic substance for the core as the magnetic switch. The operation was carried out at the GTO generasting full power. Co base amorphous alloy of low loss was used for the core of saturable inductor and the circuit efficiency of 77% could be obtained by suppressing the heat generation in core even at 4,000Hz operation. The full output power of 8.2kW was possible which corresponds to 100W class laser oscillation. Repeated Cu vapor laser oscillation of 30W succeeded at the condition of 4,000Hz and power supply output of 5.9kW. 7 refs., 21 figs., 8 tabs.

Morphological changes in skin tumors caused by pulsed laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Moskalik, K G; Lipova, V A; Neyshtadt, E L

1979-01-01

Morphological changes induced by treating melanomas, basaloma and flatcell skin cancers with a pulsed neodymium laser at 1060 nm, pulse length 1 msec and energy 250 to 500 J/cm/sup 2/, were studied using impressions and scrapings from the affected area. Nuclear pyknosis, nuclear and cellular elongation, vacuolization, frequent complete loss of cytoplasm, particulaly in the zone of direct irradiation, and loss of cellular structure were seen. These dystrophic changes increased with closeness to the zone of direct irradiation, culminating in necrosis. Formed and decomposed blood elements and melanin accumulated in the intracellular spaces, due to disruption of capillaries and small arteries and veins. Fewer and more aggregated melanoblasts were found after melanoma irradiation. Nuclear chromatin fusion, cytoplasmic changes and altered cell shape were observed. Basaloma cells were clustered and elongated after irradiation, with many fibrous structures and loss of cellular elements. Cytoplasmic vacuolization and lysis, bare nuclei, karyolysis, karyorrhexis and karyopyknosis were seen in corneous flat-cell cancer. In the few cases in which malignant cells were found under the scab from the first treatment the procedure was repeated. The morphological changes induced by pulsed laser irradiation are very similar to electrocoagulation necrosis, but are more localized. The ability of low and middle energy lasers to induce thrombosis and coagulation in vascular walls reduced the probability of hematogenic tumor cell dissemination. Cytological examination is highly effective in determining the degree of radical skin cancer healing due to laser treatment. 12 references, 2 figures.

Controllable pulse parameter transcranial magnetic stimulator with enhanced circuit topology and pulse shaping

Science.gov (United States)

Peterchev, Angel V.; DʼOstilio, Kevin; Rothwell, John C.; Murphy, David L.

2014-10-01

Objective. This work aims at flexible and practical pulse parameter control in transcranial magnetic stimulation (TMS), which is currently very limited in commercial devices. Approach. We present a third generation controllable pulse parameter device (cTMS3) that uses a novel circuit topology with two energy-storage capacitors. It incorporates several implementation and functionality advantages over conventional TMS devices and other devices with advanced pulse shape control. cTMS3 generates lower internal voltage differences and is implemented with transistors with a lower voltage rating than prior cTMS devices. Main results. cTMS3 provides more flexible pulse shaping since the circuit topology allows four coil-voltage levels during a pulse, including approximately zero voltage. The near-zero coil voltage enables snubbing of the ringing at the end of the pulse without the need for a separate active snubber circuit. cTMS3 can generate powerful rapid pulse sequences (\\lt 10 ms inter pulse interval) by increasing the width of each subsequent pulse and utilizing the large capacitor energy storage, allowing the implementation of paradigms such as paired-pulse and quadripulse TMS with a single pulse generation circuit. cTMS3 can also generate theta (50 Hz) burst stimulation with predominantly unidirectional electric field pulses. The cTMS3 device functionality and output strength are illustrated with electrical output measurements as well as a study of the effect of pulse width and polarity on the active motor threshold in ten healthy volunteers. Significance. The cTMS3 features could extend the utility of TMS as a research, diagnostic, and therapeutic tool.

Repeatability of visual acuity measurement.

Science.gov (United States)

Raasch, T W; Bailey, I L; Bullimore, M A

1998-05-01

This study investigates features of visual acuity chart design and acuity testing scoring methods which affect the validity and repeatability of visual acuity measurements. Visual acuity was measured using the Sloan and British Standard letter series, and Landolt rings. Identifiability of the different letters as a function of size was estimated, and expressed in the form of frequency-of-seeing curves. These functions were then used to simulate acuity measurements with a variety of chart designs and scoring criteria. Systematic relationships exist between chart design parameters and acuity score, and acuity score repeatability. In particular, an important feature of a chart, that largely determines the repeatability of visual acuity measurement, is the amount of size change attributed to each letter. The methods used to score visual acuity performance also affect repeatability. It is possible to evaluate acuity score validity and repeatability using the statistical principles discussed here.

Electronic perturbation investigations into excitation and ionization in the millisecond pulsed glow discharge plasma

International Nuclear Information System (INIS)

Li Lei; Robertson-Honecker, Jennifer; Vaghela, Vishal; King, Fred L.

2006-01-01

This study employed a power perturbation method to examine the energy transfer processes at different locations within the afterpeak regime of a millisecond pulsed glow discharge plasma. Brief power perturbation pulses were applied during the afterpeak regime altering the environment of the collapsing plasma. Responses of several transitions to the power perturbations were measured via atomic emission and absorption spectroscopic methods at various distances from the surface of the cathode. The experimental data provide further insight into the energy transfer processes that occur at different spatial locations and in different temporal regimes of these pulsed glow discharge plasmas. Although the enhancement of the large population of metastable argon atoms is again confirmed, the mechanism responsible for this enhancement remains unclear. The most likely possibility involves some form of ion-electron recombination followed by radiative relaxation of the resulting species. The metastable argon atoms subsequently Penning ionize sputtered copper atoms which then appear to undergo a similar ion-electron recombination process yielding variable degrees of observable afterpeak emission for copper atom transitions. The kinetic information of these processes was approximated from the corresponding relaxation time. The electron thermalization time allowing for recombination with ions was found to be ∼25 μs after the discharge power termination

Electromagnetic cascade in high-energy electron, positron, and photon interactions with intense laser pulses

Science.gov (United States)

Bulanov, S. S.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

2013-06-01

The interaction of high-energy electrons, positrons, and photons with intense laser pulses is studied in head-on collision geometry. It is shown that electrons and/or positrons undergo a cascade-type process involving multiple emissions of photons. These photons can consequently convert into electron-positron pairs. As a result charged particles quickly lose their energy developing an exponentially decaying energy distribution, which suppresses the emission of high-energy photons, thus reducing the number of electron-positron pairs being generated. Therefore, this type of interaction suppresses the development of the electromagnetic avalanche-type discharge, i.e., the exponential growth of the number of electrons, positrons, and photons does not occur in the course of interaction. The suppression will occur when three-dimensional effects can be neglected in the transverse particle orbits, i.e., for sufficiently broad laser pulses with intensities that are not too extreme. The final distributions of electrons, positrons, and photons are calculated for the case of a high-energy e-beam interacting with a counterstreaming, short intense laser pulse. The energy loss of the e-beam, which requires a self-consistent quantum description, plays an important role in this process, as well as provides a clear experimental observable for the transition from the classical to quantum regime of interaction.

Discharge characteristics of an ablative pulsed plasma thruster with non-volatile liquid propellant

Science.gov (United States)

Ling, William Yeong Liang; Schönherr, Tony; Koizumi, Hiroyuki

2017-07-01

Pulsed plasma thrusters (PPTs) are a form of electric spacecraft propulsion. They have an extremely simple structure and are highly suitable for nano/micro-spacecraft with weights in the kilogram range. Such small spacecraft have recently experienced increased growth but still lack suitable efficient propulsion systems. PPTs operate in a pulsed mode (one discharge = one shot) and typically use solid polytetrafluoroethylene (PTFE) as a propellant. However, new non-volatile liquids in the perfluoropolyether (PFPE) family have recently been found to be promising alternatives. A recent study presented results on the physical characteristics of PFPE vs. PTFE, showing that PFPE is superior in terms of physical characteristics such as its resistance to carbon deposition. This letter will examine the electrical discharge characteristics of PFPE vs. PTFE. The results demonstrate that PFPE has excellent shot-to-shot repeatability and a lower discharge resistance when compared with PTFE. Taken together with its physical characteristics, PFPE appears to be a strong contender to PTFE as a PPT propellant.

RF Pulsed Heating

Energy Technology Data Exchange (ETDEWEB)

Pritzkau, David P.

2002-01-03

RF pulsed heating is a process by which a metal is heated from magnetic fields on its surface due to high-power pulsed RF. When the thermal stresses induced are larger than the elastic limit, microcracks and surface roughening will occur due to cyclic fatigue. Pulsed heating limits the maximum magnetic field on the surface and through it the maximum achievable accelerating gradient in a normal conducting accelerator structure. An experiment using circularly cylindrical cavities operating in the TE{sub 011} mode at a resonant frequency of 11.424 GHz is designed to study pulsed heating on OFE copper, a material commonly used in normal conducting accelerator structures. The high-power pulsed RF is supplied by an X-band klystron capable of outputting 50 MW, 1.5 {micro}s pulses. The test pieces of the cavity are designed to be removable to allow testing of different materials with different surface preparations. A diagnostic tool is developed to measure the temperature rise in the cavity utilizing the dynamic Q change of the resonant mode due to heating. The diagnostic consists of simultaneously exciting a TE{sub 012} mode to steady-state in the cavity at 18 GHz and measuring the change in reflected power as the cavity is heated from high-power pulsed RF. Two experimental runs were completed. One run was executed at a calculated temperature rise of 120 K for 56 x 10{sup 6} pulses. The second run was executed at a calculated temperature rise of 82 K for 86 x 10{sup 6} pulses. Scanning electron microscope pictures show extensive damage occurring in the region of maximum temperature rise on the surface of the test pieces.

Silicon switch development for optical pulse generation in fusion lasers at Lawrence Livermore National Laboratory

International Nuclear Information System (INIS)

Wilcox, R.B.

1983-01-01

We have been developing a silicon photoconductive switch for use as a Pockels cell driver in the pulse generation systems of the fusion lasers Nova and Novette. The objective has been to make 10 kV switches repeatably and which are reliable on an operating system. We found that nonlinear phenomena in nearly intrinsic silicon caused excessive conduction at high voltage resulting in breakdown. Our experiments with doped material show that this problem can be eliminated, resulting in useful devices

Optimal pulse fishing policy in stage-structured models with birth pulses

International Nuclear Information System (INIS)

Gao Shujing; Chen Lansun; Sun Lihua

2005-01-01

In this paper, we propose exploited models with stage structure for the dynamics in a fish population for which periodic birth pulse and pulse fishing occur at different fixed time. Using the stroboscopic map, we obtain an exact cycle of system, and obtain the threshold conditions for its stability. Bifurcation diagrams are constructed with the birth rate (or pulse fishing time or harvesting effort) as the bifurcation parameter, and these are observed to display complex dynamic behaviors, including chaotic bands with period windows, period-doubling, multi-period-halving and incomplete period-doubling bifurcation, pitch-fork and tangent bifurcation, non-unique dynamics (meaning that several attractors or attractor and chaos coexist) and attractor crisis. This suggests that birth pulse and pulse fishing provide a natural period or cyclicity that make the dynamical behaviors more complex. Moreover, we show that the pulse fishing has a strong impact on the persistence of the fish population, on the volume of mature fish stock and on the maximum annual-sustainable yield. An interesting result is obtained that, after the birth pulse, the population can sustain much higher harvesting effort if the mature fish is removed as early as possible

Evaluation of pulse-oximetry oxygen saturation taken through skin protective covering

Science.gov (United States)

James, Jyotsna; Tiwari, Lokesh; Upadhyay, Pramod; Sreenivas, Vishnubhatla; Bhambhani, Vikas; Puliyel, Jacob M

2006-01-01

Background The hard edges of adult finger clip probes of the pulse oximetry oxygen saturation (POOS) monitor can cause skin damage if used for prolonged periods in a neonate. Covering the skin under the probe with Micropore surgical tape or a gauze piece might prevent such injury. The study was done to see if the protective covering would affect the accuracy of the readings. Methods POOS was studied in 50 full-term neonates in the first week of life. After obtaining consent from their parents the neonates had POOS readings taken directly (standard technique) and through the protective covering. Bland-Altman plots were used to compare the new method with the standard technique. A test of repeatability for each method was also performed. Results The Bland-Altman plots suggest that there is no significant loss of accuracy when readings are taken through the protective covering. The mean difference was 0.06 (SD of 1.39) and 0.04 (SD 1.3) with Micropore and gauze respectively compared to the standard method. The mean difference was 0.22 (SD 0.23) on testing repeatability with the standard method. Conclusion Interposing Micropore or gauze does not significantly affect the accuracy of the POOS reading. The difference between the standard method and the new method was less than the difference seen on testing repeatability of the standard method. PMID:16677394

High field strength magnetic resonance imaging in paediatric brain tumour surgery--its role in prevention of early repeat resections.

Science.gov (United States)

Avula, Shivaram; Pettorini, Benedetta; Abernethy, Laurence; Pizer, Barry; Williams, Dawn; Mallucci, Conor

2013-10-01

The purpose of this study is to compare the surgical and imaging outcome in children who underwent brain tumour surgery with intention of complete tumour resection, prior to and following the start of intra-operative MRI (ioMRI) service. ioMRI service for brain tumour resection commenced in October 2009. A cohort of patients operated between June 2007 and September 2009 with a pre-surgical intention of complete tumour resection were selected (Group A). A similar number of consecutive cases were selected from a prospective database of patients undergoing ioMRI (Group B). The demographics, imaging, pathology and surgical outcome of both groups were compared. Thirty-six of 47 cases from Group A met the inclusion criterion and 36 cases were selected from Group B; 7 of the 36 cases in Group A had unequivocal evidence of residual tumour on the post-operative scan; 5 (14%) of them underwent repeat resection within 6 months post-surgery. In Group B, ioMRI revealed unequivocal evidence of residual tumour in 11 of the 36 cases following initial resection. In 10 of these 11 cases, repeat resections were performed during the same surgical episode and none of these 11 cases required repeat surgery in the following 6 months. Early repeat resection rate was significantly different between both groups (p = 0.003). Following the advent of ioMRI at our institution, the need for repeat resection within 6 months has been prevented in cases where ioMRI revealed unequivocal evidence of residual tumour.

No loss of hippocampal hilar somatostatinergic neurons after repeated electroconvulsive shock

DEFF Research Database (Denmark)

Dalby, Nils Ole; Tønder, N; Wolby, D P

1996-01-01

Electrically induced seizures with anesthesia and muscle relaxation (ECT) is commonly used in the therapy of psychotic depression in humans. Unmodified electroshock (ECS) is used as a model for epilepsy in the rat. In several seizure models of epilepsy, in particular the dentate hilar somatostatin......-containing (SSergic) neurons have been found to undergo degeneration. To assess the potential loss of SSergic hilar neurons after repeated ECS, 10 rats were given 110 ECS, one per day, 5 days a week. One day after the last ECS the rats were anesthesized, perfused, the brains cut on a vibratome and prepared...... for nonradioactive in situ hybridization for somatostatin along with five control rats. Like rats given 10-36 ECS in earlier studies, the ECS-treated rats displayed a markedly increased neuronal hybridization labeling when compared with control rats. The total number of dentate hilar SSergic neurons of each rat...

Intraoperative mapping during repeat awake craniotomy reveals the functional plasticity of adult cortex.

Science.gov (United States)

Southwell, Derek G; Hervey-Jumper, Shawn L; Perry, David W; Berger, Mitchel S

2016-05-01

OBJECT To avoid iatrogenic injury during the removal of intrinsic cerebral neoplasms such as gliomas, direct electrical stimulation (DES) is used to identify cortical and subcortical white matter pathways critical for language, motor, and sensory function. When a patient undergoes more than 1 brain tumor resection as in the case of tumor recurrence, the use of DES provides an unusual opportunity to examine brain plasticity in the setting of neurological disease. METHODS The authors examined 561 consecutive cases in which patients underwent DES mapping during surgery forglioma resection. "Positive" and "negative" sites-discrete cortical regions where electrical stimulation did (positive) or did not (negative) produce transient sensory, motor, or language disturbance-were identified prior to tumor resection and documented by intraoperative photography for categorization into functional maps. In this group of 561 patients, 18 were identified who underwent repeat surgery in which 1 or more stimulation sites overlapped with those tested during the initial surgery. The authors compared intraoperative sensory, motor, or language mapping results between initial and repeat surgeries, and evaluated the clinical outcomes for these patients. RESULTS A total of 117 sites were tested for sensory (7 sites, 6.0%), motor (9 sites, 7.7%), or language (101 sites, 86.3%) function during both initial and repeat surgeries. The mean interval between surgical procedures was 4.1 years. During initial surgeries, 95 (81.2%) of 117 sites were found to be negative and 22 (18.8%) of 117 sites were found to be positive. During repeat surgeries, 103 (88.0%) of 117 sites were negative and 14 (12.0%) of 117 were positive. Of the 95 sites that were negative at the initial surgery, 94 (98.9%) were also negative at the repeat surgery, while 1 (1.1%) site was found to be positive. Of the 22 sites that were initially positive, 13 (59.1%) remained positive at repeat surgery, while 9 (40.9%) had become

Versatile pulse programmer for pulsed nuclear magnetic resonance spectroscopy

International Nuclear Information System (INIS)

Adduci, D.J.

1979-05-01

A description of the sequence of events and the decisions leading to the design of a versatile pulse programmer for pulsed NMR are presented. Background and application information is discussed in order that the reader might better understand the role of the pulse programmer in a NMR spectrometer. Various other design approaches are presented as a basis for comparison. Specifications for this design are proposed, the hardware implementation of the specifications is discussed, and the software operating system is presented

Versatile pulse programmer for pulsed nuclear magnetic resonance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Adduci, D.J.

1979-05-01

A description of the sequence of events and the decisions leading to the design of a versatile pulse programmer for pulsed NMR are presented. Background and application information is discussed in order that the reader might better understand the role of the pulse programmer in a NMR spectrometer. Various other design approaches are presented as a basis for comparison. Specifications for this design are proposed, the hardware implementation of the specifications is discussed, and the software operating system is presented.

A compact bipolar pulse-forming network-Marx generator based on pulse transformers.

Science.gov (United States)

Zhang, Huibo; Yang, Jianhua; Lin, Jiajin; Yang, Xiao

2013-11-01

A compact bipolar pulse-forming network (PFN)-Marx generator based on pulse transformers is presented in this paper. The high-voltage generator consisted of two sets of pulse transformers, 6 stages of PFNs with ceramic capacitors, a switch unit, and a matched load. The design is characterized by the bipolar pulse charging scheme and the compact structure of the PFN-Marx. The scheme of bipolar charging by pulse transformers increased the withstand voltage of the ceramic capacitors in the PFNs and decreased the number of the gas gap switches. The compact structure of the PFN-Marx was aimed at reducing the parasitic inductance in the generator. When the charging voltage on the PFNs was 35 kV, the matched resistive load of 48 Ω could deliver a high-voltage pulse with an amplitude of 100 kV. The full width at half maximum of the load pulse was 173 ns, and its rise time was less than 15 ns.

Development of bipolar pulse accelerator for intense pulsed ion beam acceleration

International Nuclear Information System (INIS)

Fujioka, Y.; Mitsui, C.; Kitamura, I.; Takahashi, T.; Masugata, K.; Tanoue, H.; Arai, K.

2003-01-01

To improve the purity of an intense pulsed ion beams a new type of pulsed ion beam accelerator named 'bipolar pulse accelerator (BPA)' was proposed. In the accelerator purity of the beam is expected. To confirm the principle of the accelerator experimental system was developed. The system utilizes B y type magnetically insulated acceleration gap and operated with single polar negative pulse. A coaxial gas puff plasma gun placed in the grounded anode was used as an ion source, and source plasma (nitrogen) of current density approx. = 25 A/cm 2 , duration approx. = 1.5 μs was injected into the acceleration gap. The ions are successfully accelerated from the grounded anode to the drift tube by applying negative pulse of voltage 180 kV, duration 60 ns to the drift tube. Pulsed ion beam of current density approx. = 40 A/cm 2 , duration approx. 60 ns was obtained at 42 mm downstream from the anode surface. (author)

Producing High Intense Attosecond Pulse Train by Interaction of Three-Color Pulse and Overdense Plasma

Science.gov (United States)

Salehi, M.; Mirzanejad, S.

2017-05-01

Amplifying the attosecond pulse by the chirp pulse amplification method is impossible. Furthermore, the intensity of attosecond pulse is low in the interaction of laser pulse and underdense plasma. This motivates us to propose using a multi-color pulse to produce the high intense attosecond pulse. In the present study, the relativistic interaction of a three-color linearly-polarized laser-pulse with highly overdense plasma is studied. We show that the combination of {{ω }}1, {{ω }}2 and {{ω }}3 frequencies decreases the instance full width at half maximum reflected attosecond pulse train from the overdense plasma surface. Moreover, we show that the three-color pulse increases the intensity of generated harmonics, which is explained by the relativistic oscillating mirror model. The obtained results demonstrate that if the three-color laser pulse interacts with overdense plasma, it will enhance two orders of magnitude of intensity of ultra short attosecond pulses in comparison with monochromatic pulse.

Switching waves dynamics in optical bistable cavity-free system at femtosecond laser pulse propagation in semiconductor under light diffraction

Science.gov (United States)

Trofimov, Vyacheslav A.; Egorenkov, Vladimir A.; Loginova, Maria M.

2018-02-01

We consider a propagation of laser pulse in a semiconductor under the conditions of an occurrence of optical bistability, which appears due to a nonlinear absorption of the semiconductor. As a result, the domains of high concentration of free charged particles (electrons and ionized donors) occur if an intensity of the incident optical pulse is greater than certain intensity. As it is well-known, that an optical beam must undergo a diffraction on (or reflection from) the domains boundaries. Usually, the beam diffraction along a coordinate of the optical pulse propagation does not take into account by using the slowly varying envelope approximation for the laser pulse interaction with optical bistable element. Therefore, a reflection of the beam from the domains with abrupt boundary does not take into account under computer simulation of the laser pulse propagation. However, the optical beams, reflected from nonhomogeneities caused by the domains of high concentration of free-charged particles, can essentially influence on a formation of switching waves in a semiconductor. We illustrate this statement by computer simulation results provided on the base of nonlinear Schrödinger equation and a set of PDEs, which describe an evolution of the semiconductor characteristics (concentrations of free-charged particles and potential of an electric field strength), and taking into account the longitudinal and transverse diffraction effects.

Concave pulse shaping of a circularly polarized laser pulse from non-uniform overdense plasmas

Energy Technology Data Exchange (ETDEWEB)

Hur, Min Sup [School of Natural Science, UNIST, BanYeon-Ri 100, Ulju-gun, Ulsan, 689-798 (Korea, Republic of); Kulagin, Victor V. [Sternberg Astronomical Institute, Moscow State University, Universitetsky prosp. 13, Moscow, 119992 (Russian Federation); Suk, Hyyong, E-mail: hysuk@gist.ac.kr [Department of Physics and Photon Science, GIST, 123 Cheomdan-gwangiro, Buk-gu, Gwangju, 500-712 (Korea, Republic of)

2015-03-20

Pulse shaping of circularly polarized laser pulses in nonuniform overdense plasmas are investigated numerically. Specifically we show by two-dimensional particle-in-cell simulations the generation of a concave pulse front of a circularly polarized, a few tens of petawatt laser pulse from a density-tapered, overdense plasma slab. The concept used for the transverse-directional shaping is the differential transmittance depending on the plasma density, and the laser intensity. For suitable selection of the slab parameters for the concave pulse shaping, we studied numerically the pulse transmittance, which can be used for further parameter design of the pulse shaping. The concavely shaped circularly polarized pulse is expected to add more freedom in controlling the ion-beam characteristics in the RPDA regime. - Highlights: • Laser pulse shaping for a concave front by non-uniform overdense plasma was studied. • Particle-in-cell (PIC) simulations were used for the investigation. • A laser pulse can be shaped by a density-tapered overdense plasma. • The concave and sharp pulse front are useful in many laser–plasma applications. • They are important for ion acceleration, especially in the radiation pressure dominant regime.

Study of plasma wall interactions in the long-pulse NB-heated discharges of JT-60U towards steady-state operation

International Nuclear Information System (INIS)

Takenaga, H.; Asakura, N.; Higashijima, S.; Nakano, T.; Kubo, H.; Konoshima, S.; Oyama, N.; Isayama, A.; Ide, S.; Fujita, T.; Miura, Y.

2005-01-01

Long time scale variation of plasma-wall interactions and its impact on particle balance, main plasma performance and particle behavior have been investigated in ELMy H-mode plasmas by extending the discharge pulse and the neutral beam heating pulse to 65 s and 30 s, respectively. The wall pumping rate starts to decrease in the latter phase by repeating the long-pulse discharges with 60% of Greenwald density sustained by gas-puffing. After several discharges, the wall inventory is saturated in the latter phase and, consequently, the density increases with neutral beam fuelling only. The edge pressure in the main plasma is reduced and ELMs are close to the type III regime under conditions of wall saturation. The intensities of C II emission near the X-point and CD band emission in the inner divertor start to increase before the wall saturates and continue to increase after the wall is saturated

Long-pulse applications of pulse-forming lines for high-power linac application

International Nuclear Information System (INIS)

Hoeberling, R.F.; Tallerico, P.J.

1981-01-01

The ever present demands for high efficiency in the RF power stations for particle accelerators have caused increased interest in longer RF pulses (ten's of microseconds) for linacs such as the Pion Generator for Medical Irradiation (PIGMI) and Free Electron Laser (FEL). For either RF power station, a fundamental decision is whether to use a modulating anode/hard-tube driver or pulsed cathode/line-type pulser configuration. The choices in the extremes of low power for very long pulses or for very-high-power, short pulses are, respectively, a modulated anode/hard tube modulator and pulsed cathode/pulse forming line. However, the demarcation between these two extremes is not clearcut. The criteria (cost, flexibility performance, reliability, efficiency) that resulted in the RF station definition of these two specific systems will be described

Fostering repeat donations in Ghana.

Science.gov (United States)

Owusu-Ofori, S; Asenso-Mensah, K; Boateng, P; Sarkodie, F; Allain, J-P

2010-01-01

Most African countries are challenged in recruiting and retaining voluntary blood donors by cost and other complexities and in establishing and implementing national blood policies. The availability of replacement donors who are a cheaper source of blood has not enhanced repeat voluntary donor initiatives. An overview of activities for recruiting and retaining voluntary blood donors was carried out. Donor records from mobile sessions were reviewed from 2002 to 2008. A total of 71,701 blood donations; 45,515 (63.5%) being voluntary donations with 11,680 (25%) repeat donations were collected during the study period. Donations from schools and colleges contributed a steady 60% of total voluntary whilst radio station blood drives increased contribution from 10 to 27%. Though Muslim population is less than 20%, blood collection was above the 30-donation cost-effectiveness threshold with a repeat donation trend reaching 60%. In contrast Christian worshippers provided donations. Repeat donation trends amongst school donors and radio blood drives were 20% and 70% respectively. Repeat donations rates have been variable amongst different blood donor groups in Kumasi, Ghana. The impact of community leaders in propagating altruism cannot be overemphasized. Programs aiming at motivating replacement donors to be repeat donors should be developed and assessed. Copyright 2009 The International Association for Biologicals. All rights reserved.

NMR Analysis of Amide Hydrogen Exchange Rates in a Pentapeptide-Repeat Protein from A. thaliana.

Science.gov (United States)

Xu, Shenyuan; Ni, Shuisong; Kennedy, Michael A

2017-05-23

At2g44920 from Arabidopsis thaliana is a pentapeptide-repeat protein (PRP) composed of 25 repeats capped by N- and C-terminal α-helices. PRP structures are dominated by four-sided right-handed β-helices typically consisting of mixtures of type II and type IV β-turns. PRPs adopt repeated five-residue (Rfr) folds with an Rfr consensus sequence (STAV)(D/N)(L/F)(S/T/R)(X). Unlike other PRPs, At2g44920 consists exclusively of type II β-turns. At2g44920 is predicted to be located in the thylakoid lumen although its biochemical function remains unknown. Given its unusual structure, we investigated the biophysical properties of At2g44920 as a representative of the β-helix family to determine if it had exceptional global stability, backbone dynamics, or amide hydrogen exchange rates. Circular dichroism measurements yielded a melting point of 62.8°C, indicating unexceptional global thermal stability. Nuclear spin relaxation measurements indicated that the Rfr-fold core was rigid with order parameters ranging from 0.7 to 0.9. At2g44920 exhibited a striking range of amide hydrogen exchange rates spanning 10 orders of magnitude, with lifetimes ranging from minutes to several months. A weak correlation was found among hydrogen exchange rates, hydrogen bonding energies, and amino acid solvent-accessible areas. Analysis of contributions from fast (approximately picosecond to nanosecond) backbone dynamics to amide hydrogen exchange rates revealed that the average order parameter of amides undergoing fast exchange was significantly smaller compared to those undergoing slow exchange. Importantly, the activation energies for amide hydrogen exchange were found to be generally higher for the slowest exchanging amides in the central Rfr coil and decreased toward the terminal coils. This could be explained by assuming that the concerted motions of two preceding or following coils required for hydrogen bond disruption and amide hydrogen exchange have a higher activation energy

Development of bipolar-pulse accelerator for intense pulsed ion beam acceleration

Energy Technology Data Exchange (ETDEWEB)

Masugata, Katsumi [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan)]. E-mail: masugata@eng.toyama-u.ac.jp; Shimizu, Yuichro [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Fujioka, Yuhki [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Kitamura, Iwao [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Tanoue, Hisao [National Institute of Advanced Industry Science and Technology, 1-1-1, Umezono, Tsukuba-shi, Ibaraki 305-8568 (Japan); Arai, Kazuo [National Institute of Advanced Industry Science and Technology, 1-1-1, Umezono, Tsukuba-shi, Ibaraki 305-8568 (Japan)

2004-12-21

To improve the purity of intense pulsed ion beams, a new type of pulsed ion beam accelerator named 'bipolar pulse accelerator' was proposed. To confirm the principle of the accelerator a prototype of the experimental system was developed. The system utilizes By type magnetically insulated acceleration gap and operated with single polar negative pulse. A coaxial gas puff plasma gun was used as an ion source, which was placed inside the grounded anode. Source plasma (nitrogen) of current density {approx}25A/cm2, duration {approx}1.5{mu}s was injected into the acceleration gap by the plasma gun. The ions were successfully accelerated from the grounded anode to the drift tube by applying negative pulse of voltage 240kV, duration 100ns to the drift tube. Pulsed ion beam of current density {approx}40A/cm2, duration {approx}50ns was obtained at 41mm downstream from the anode surface. To evaluate the irradiation effect of the ion beam to solid material, an amorphous silicon thin film of thickness {approx}500nm was used as the target, which was deposited on the glass substrate. The film was found to be poly-crystallized after 4-shots of the pulsed nitrogen ion beam irradiation.

Direct electron-impact mechanism of excitation of mercury monobromide in a double-pulse dielectric-barrier-discharge HgBr lamp

Science.gov (United States)

Datsyuk, V. V.; Izmailov, I. A.; Naumov, V. V.; Kochelap, V. A.

2016-08-01

In a nonequlibrium plasma of a gas-discharge HgBr lamp, the terminal electronic state of the HgBr(B-X) radiative transition with a peak wavelength of 502 nm remains populated for a relatively long time and is repeatedly excited to the B state in collisions with plasma electrons. This transfer of the HgBr molecules from the ground state X to the excited state B is the main mechanism of formation of the light-emitting molecules especially when the lamp is excited by double current pulses. According to our simulations, due to the electron-induced transitions between HgBr(X) and HgBr(B), the output characteristics of the DBD lamp operating in a double-pulse regime are better than those of the lamp operating in a single-pulse regime. In the considered case, the peak power is calculated to increase by a factor of about 2 and the lamp efficiency increases by about 50%.

Directed Acceleration of Electrons from a Solid Surface by Sub-10-fs Laser Pulses

International Nuclear Information System (INIS)

Brandl, F.; Hidding, B.; Osterholz, J.; Hemmers, D.; Pretzler, G.; Karmakar, A.; Pukhov, A.

2009-01-01

Electrons have been accelerated from solid target surfaces by sub-10-fs laser pulses of 120 μJ energy which were focused to an intensity of 2x10 16 W/cm 2 . The electrons have a narrow angular distribution, and their observed energies exceed 150 keV. We show that these energies are not to be attributed to collective plasma effects but are mainly gained directly via repeated acceleration in the transient field pattern created by incident and reflected laser, alternating with phase-shift-generating scattering events in the solid.

Erbium:ytterbium fiber-laser system delivering watt-level femtosecond pulses using divided pulse amplification

Science.gov (United States)

Herda, Robert; Zach, Armin

2015-03-01

We present an Erbium:Ytterbium codoped fiber-amplifer system based on Divided-Pulses-Amplification (DPA) for ultrashort pulses. The output from a saturable-absorber mode-locked polarization-maintaining (PM) fiber oscillator is amplified in a PM normal-dispersion Erbium-doped fiber. After this stage the pulses are positively chirped and have a duration of 2.0 ps at an average power of 93 mW. A stack of 5 birefringent Yttrium-Vanadate crystals divides these pulses 32 times. We amplify these pulses using a double-clad Erbium:Ytterbium codoped fiber pumped through a multimode fiber combiner. The pulses double pass the amplifier and recombine in the crystals using non-reciprocal polarization 90° rotation by a Faraday rotating mirror. Pulses with a duration of 144 fs are obtained after separation from the input beam using a polarizing beam splitter cube. These pulses have an average power of 1.85 W at a repetition rate of 80 MHz. The generation of femtosecond pulses directly from the amplifier was enabled by a positively chirped seed pulse, normally dispersive Yttrium-Vanadate crystals, and anomalously dispersive amplifier fibers. Efficient frequency doubling to 780 nm with an average power of 725 mW and a pulse duration of 156 fs is demonstrated. In summary we show a DPA setup that enables the generation of femtosecond pulses at watt-level at 1560 nm without the need for further external dechirping and demonstrate a good pulse quality by efficient frequency doubling. Due to the use of PM fiber components and a Faraday rotator the setup is environmentally stable.

Repeated DNA sequences in fungi

Energy Technology Data Exchange (ETDEWEB)

Dutta, S K

1974-11-01

Several fungal species, representatives of all broad groups like basidiomycetes, ascomycetes and phycomycetes, were examined for the nature of repeated DNA sequences by DNA:DNA reassociation studies using hydroxyapatite chromatography. All of the fungal species tested contained 10 to 20 percent repeated DNA sequences. There are approximately 100 to 110 copies of repeated DNA sequences of approximately 4 x 10/sup 7/ daltons piece size of each. Repeated DNA sequence homoduplexes showed on average 5/sup 0/C difference of T/sub e/50 (temperature at which 50 percent duplexes dissociate) values from the corresponding homoduplexes of unfractionated whole DNA. It is suggested that a part of repetitive sequences in fungi constitutes mitochondrial DNA and a part of it constitutes nuclear DNA. (auth)

Topological characteristics of helical repeat proteins

NARCIS (Netherlands)

Groves, M R; Barford, D

The recent elucidation of protein structures based upon repeating amino acid motifs, including the armadillo motif, the HEAT motif and tetratricopeptide repeats, reveals that they belong to the class of helical repeat proteins. These proteins share the common property of being assembled from tandem

DogPulse

DEFF Research Database (Denmark)

Skovgaard, Christoffer; Thomsen, Josephine Raun; Verdezoto, Nervo

2015-01-01

This paper presents DogPulse, an ambient awareness system to support the coordination of dog walking among family members at home. DogPulse augments a dog collar and leash set to activate an ambient shape-changing lamp and visualize the last time the dog was taken for a walk. The lamp gradually...... changes its form and pulsates its lights in order to keep the family members aware of the dog walking activity. We report the iterative prototyping of DogPulse, its implementation and its preliminary evaluation. Based on our initial findings, we present the limitations and lessons learned as well...

Stability analysis of ELMs in long-pulse discharges with ELITE code on EAST tokamak

Science.gov (United States)

Wang, Y. F.; Xu, G. S.; Wan, B. N.; Li, G. Q.; Yan, N.; Li, Y. L.; Wang, H. Q.; Peng, Y.-K. Martin; Xia, T. Y.; Ding, S. Y.; Chen, R.; Yang, Q. Q.; Liu, H. Q.; Zang, Q.; Zhang, T.; Lyu, B.; Xu, J. C.; Feng, W.; Wang, L.; Chen, Y. J.; Luo, Z. P.; Hu, G. H.; Zhang, W.; Shao, L. M.; Ye, Y.; Lan, H.; Chen, L.; Li, J.; Zhao, N.; Wang, Q.; Snyder, P. B.; Liang, Y.; Qian, J. P.; Gong, X. Z.; EAST team

2018-05-01

One challenge in long-pulse and high performance tokamak operation is to control the edge localized modes (ELMs) to reduce the transient heat load on plasma facing components. Minute-scale discharges in H-mode have been achieved repeatedly on Experimental Advanced Superconducting Tokamak (EAST) since the 2016 campaign and understanding the characteristics of the ELMs in these discharges can be helpful for effective ELM control in long-pulse discharges. The kinetic profile diagnostics recently developed on EAST make it possible to perform the pedestal stability analysis quantitatively. Pedestal stability calculation of a typical long-pulse discharge with ELITE code is presented. The ideal linear stability results show that the ELM is dominated by toroidal mode number n around 10–15 and the most unstable mode structure is mainly localized in the steep pressure gradient region, which is consistent with experimental results. Compared with a typical type-I ELM discharge with larger total plasma current (I p = 600 kA), pedestal in the long-pulse H-mode discharge (I p = 450 kA) is more stable in peeling-ballooning instability and its critical peak pressure gradient is evaluated to be 65% of the former. Two important features of EAST tokamak in the long-pulse discharge are presented by comparison with other tokamaks, including a wider pedestal correlated with the poloidal pedestal beta and a smaller inverse aspect ratio and their effects on the pedestal stability are discussed. The effects of uncertainties in measurements on the linear stability results are also analyzed, including the edge electron density profile position, the separatrix position and the line-averaged effective ion charge {Z}{{e}{{f}}{{f}}} value.

Elasticity and tumorigenic characteristics of cells in a monolayer after nanosecond pulsed electric field exposure.

Science.gov (United States)

Steuer, A; Wende, K; Babica, P; Kolb, J F

2017-09-01

Nanosecond pulsed electric fields (nsPEFs) applied to cells can induce different biological effects depending on pulse duration and field strength. One known process is the induction of apoptosis whereby nsPEFs are currently investigated as a novel cancer therapy. Another and probably related change is the breakdown of the cytoskeleton. We investigated the elasticity of rat liver epithelial cells WB-F344 in a monolayer using atomic force microscopy (AFM) with respect to the potential of cells to undergo malignant transformation or to develop a potential to metastasize. We found that the elastic modulus of the cells decreased significantly within the first 8 min after treatment with 20 pulses of 100 ns and with a field strength of 20 kV/cm but was still higher than the elasticity of their tumorigenic counterpart WB-ras. AFM measurements and immunofluorescent staining showed that the cellular actin cytoskeleton became reorganized within 5 min. However, both a colony formation assay and a cell migration assay revealed no significant changes after nsPEF treatment, implying that cells seem not to adopt malignant characteristics associated with metastasis formation despite the induced transient changes to elasticity and cytoskeleton that can be observed for up to 1 h.

On random pressure pulses in the turbine draft tube

Science.gov (United States)

Kuibin, P. A.; Shtork, S. I.; Skripkin, S. G.; Tsoy, M. A.

2017-04-01

The flow in the conical part of the hydroturbine draft tube undergoes various instabilities due to deceleration and flow swirling at off-design operation points. In particular, the precessing vortex rope develops at part-load regimes in the draft tube. This rope induces periodical low-frequency pressure oscillations in the draft tube. Interaction of rotational (asynchronous) mode of disturbances with the elbow can bring to strong oscillations in the whole hydrodynamical system. Recent researches on flow structure in the discharge cone in a regime of free runner had revealed that helical-like vortex rope can be unstable itself. Some coils of helix close to each other and reconnection appears with generation of a vortex ring. The vortex ring moves toward the draft tube wall and downstream. The present research is focused on interaction of vortex ring with wall and generation of pressure pulses.

Rapid measurement of indocyanine green retention by pulse spectrophotometry: a validation study in 70 patients with Child-Pugh A cirrhosis before hepatectomy for hepatocellular carcinoma.

Science.gov (United States)

Cheung, Tan To; Chan, See Ching; Chok, Kenneth S H; Chan, Albert C Y; Yu, Wan Ching; Poon, Ronnie T P; Lo, Chung Mau; Fan, Sheung Tat

2012-06-01

The indocyanine green (ICG) retention test is the most popular liver function test for selecting patients for major hepatectomy. Traditionally, it is done using spectrophotometry with serial blood sampling. The newly-developed pulse spectrophotometry is a faster alternative, but its accuracy on Child-Pugh A cirrhotic patients undergoing hepatectomy for hepatocellular carcinoma has not been well documented. This study aimed to assess the accuracy of the LiMON(®), one of the pulse spectrophotometry systems, in measuring preoperative ICG retention in these patients and to devise an easy formula for conversion of the results so that they can be compared with classical literature records where ICG retention was measured by the traditional method. We measured the liver function of 70 Child-Pugh A cirrhotic patients before hepatectomy for hepatocellular carcinoma from September 2008 to January 2009. ICG retention at 15 minutes measured by traditional spectrophotometry (ICGR15) was compared with ICG retention at 15 minutes measured by the LiMON (ICGR15(L)). The median ICGR15 was 14.7% (5.6%-32%) and the median ICGR15(L) was 10.4% (1.2%-28%). The mean difference between them was -4.3606. There was a strong correlation between ICGR15 and ICGR15(L) (correlation coefficient, 0.844; 95% confidence interval, 0.762-0.899). The following formula was devised: ICGR15=1.16XICGR15(L)+2.73. The LiMON provides a fast and repeatable way to measure ICG retention at 15 minutes, but with constant underestimation of the real value. Therefore, when comparing results obtained by traditional spectrophotometry and the LiMON, adjustment of results from the latter is necessary, and this can be done with a simple mathematical calculation using the above formula.

Optimization methods of pulse-to-pulse alignment using femtosecond pulse laser based on temporal coherence function for practical distance measurement

Science.gov (United States)

Liu, Yang; Yang, Linghui; Guo, Yin; Lin, Jiarui; Cui, Pengfei; Zhu, Jigui

2018-02-01

An interferometer technique based on temporal coherence function of femtosecond pulses is demonstrated for practical distance measurement. Here, the pulse-to-pulse alignment is analyzed for large delay distance measurement. Firstly, a temporal coherence function model between two femtosecond pulses is developed in the time domain for the dispersive unbalanced Michelson interferometer. Then, according to this model, the fringes analysis and the envelope extraction process are discussed. Meanwhile, optimization methods of pulse-to-pulse alignment for practical long distance measurement are presented. The order of the curve fitting and the selection of points for envelope extraction are analyzed. Furthermore, an averaging method based on the symmetry of the coherence function is demonstrated. Finally, the performance of the proposed methods is evaluated in the absolute distance measurement of 20 μ m with path length difference of 9 m. The improvement of standard deviation in experimental results shows that these approaches have the potential for practical distance measurement.

Pulse frequency in pulsed brachytherapy based on tissue repair kinetics

International Nuclear Information System (INIS)

Sminia, Peter; Schneider, Christoph J.; Koedooder, Kees; Tienhoven, Geertjan van; Blank, Leo E.C.M.; Gonzalez Gonzalez, Dionisio

1998-01-01

Purpose: Investigation of normal tissue sparing in pulsed brachytherapy (PB) relative to continuous low-dose rate irradiation (CLDR) by adjusting pulse frequency based on tissue repair characteristics. Method: Using the linear quadratic model, the relative effectiveness (RE) of a 20 Gy boost was calculated for tissue with an α/β ratio ranging from 2 to 10 Gy and a half-time of sublethal damage repair between 0.1 and 3 h. The boost dose was considered to be delivered either in a number of pulses varying from 2 to 25, or continuously at a dose rate of 0.50, 0.80, or 1.20 Gy/h. Results: The RE of 20 Gy was found to be identical for PB in 25 pulses of 0.80 Gy each h and CLDR delivered at 0.80 Gy/h for any α/β value and for a repair half-time > 0.75 h. When normal tissue repair half-times are assumed to be longer than tumor repair half-times, normal tissue sparing can be obtained, within the restriction of a fixed overall treatment time, with higher dose per pulse and longer period time (time elapsed between start of pulse n and start of pulse n + 1). An optimum relative normal tissue sparing larger than 10% was found with 4 pulses of 5 Gy every 8 h. Hence, a therapeutic gain might be obtained when changing from CLDR to PB by adjusting the physical dose in such a way that the biological dose on the tumor is maintained. The normal tissue-sparing phenomenon can be explained by an increase in RE with longer period time for tissue with high α/β ratio and fast or intermediate repair half-time, and the RE for tissue with low α/β ratio and long repair half-time remains almost constant. Conclusion: Within the benchmark of the LQ model, advantage in normal tissue-sparing is expected when matching the pulse frequency to the repair kinetics of the normal tissue exposed. A period time longer than 1 h may lead to a reduction of late normal tissue complications. This theoretical advantage emphasizes the need for better knowledge of human tissue-repair kinetics

Methods and Apparatus for Pulsed-DC Dielectric Barrier Discharge Plasma Actuator and Circuit

Science.gov (United States)

Corke, Thomas C. (Inventor); Kaszeta, Richard (Inventor); Gold, Calman (Inventor)

2017-01-01

A plasma generating device intended to induce a flow in a fluid via plasma generation includes a dielectric separating two electrodes and a power supply. The first electrode is exposed to a fluid flow while the second electrode is positioned under the dielectric. The power supply is electrically coupled to a switch and the first and second electrodes. When the power supply is energized by repeated action of the switch, it causes a pulsed DC current between the electrodes which causes the fluid to ionize generating a plasma. The generation of the plasma induces a force with a velocity component in the fluid.

UK 2009-2010 repeat station report

Directory of Open Access Journals (Sweden)

Thomas J.G. Shanahan

2013-03-01

Full Text Available The British Geological Survey is responsible for conducting the UK geomagnetic repeat station programme. Measurements made at the UK repeat station sites are used in conjunction with the three UK magnetic observatories: Hartland, Eskdalemuir and Lerwick, to produce a regional model of the local field each year. The UK network of repeat stations comprises 41 stations which are occupied at approximately 3-4 year intervals. Practices for conducting repeat station measurements continue to evolve as advances are made in survey instrumentation and as the usage of the data continues to change. Here, a summary of the 2009 and 2010 UK repeat station surveys is presented, highlighting the measurement process and techniques, density of network, reduction process and recent results.

Controlling output pulse and prepulse in a resonant microwave pulse compressor

International Nuclear Information System (INIS)

Shlapakovski, A.; Artemenko, S.; Chumerin, P.; Yushkov, Yu.

2013-01-01

A resonant microwave pulse compressor with a waveguide H-plane-tee-based energy extraction unit was studied in terms of its capability to produce output pulses that comprise a low-power long-duration (prepulse) and a high-power short-duration part. The application of such combined pulses with widely variable prepulse and high-power pulse power and energy ratios is of interest in the research area of electronic hardware vulnerability. The characteristics of output radiation pulses are controlled by the variation of the H-plane tee transition attenuation at the stage of microwave energy storage in the compressor cavity. Results of theoretical estimations of the parameters tuning range and experimental investigations of the prototype S-band compressor (1.5 MW, 12 ns output pulse; ∼13.2 dB gain) are presented. The achievable maximum in the prepulse power is found to be about half the power of the primary microwave source. It has been shown that the energy of the prepulse becomes comparable with that of the short-duration (nanosecond) pulse, while the power of the latter decreases insignificantly. The possible range of variation of the prepulse power and energy can be as wide as 40 dB. In the experiments, the prepulse level control within the range of ∼10 dB was demonstrated.

Dynamics of traveling reaction pulses

International Nuclear Information System (INIS)

Dovzhenko, A. Yu.; Rumanov, E. N.

2007-01-01

The growth of activator losses is accompanied by the decay of a traveling reaction pulse. In a ring reactor, this propagation threshold is present simultaneously with a threshold related to the ring diameter. The results of numerical experiments with pulses of an exothermal reaction reveal the transition from pulse propagation to a homogeneous hot regime, established regimes with periodic variations of the pulse velocity, and oscillatory decay of the pulse. When the medium becomes 'bistable' as a result of the variation in parameters, this factor does not prevent the propagation of pulses, but leads to changes in the pulse structure

Discovery of pulsed OH maser emission stimulated by a pulsar.

Science.gov (United States)

Weisberg, Joel M; Johnston, Simon; Koribalski, Bärbel; Stanimirovic, Snezana

2005-07-01

Stimulated emission of radiation has not been directly observed in astrophysical situations up to this time. Here we demonstrate that photons from pulsar B1641-45 stimulate pulses of excess 1720-megahertz line emission in an interstellar hydroxyl (OH) cloud. As this stimulated emission is driven by the pulsar, it varies on a few-millisecond time scale, which is orders of magnitude shorter than the quickest OH maser variations previously detected. Our 1612-megahertz spectra are inverted copies of the 1720-megahertz spectra. This "conjugate line" phenomenon enables us to constrain the properties of the interstellar OH line-producing gas. We also show that pulsar signals undergo significantly deeper OH absorption than do other background sources, which confirms earlier tentative findings that OH clouds are clumpier on small scales than are neutral hydrogen clouds.

Use of short tandem repeat sequences to study Mycobacterium leprae in leprosy patients in Malawi and India.

Directory of Open Access Journals (Sweden)

Saroj K Young

2008-04-01

Full Text Available Inadequate understanding of the transmission of Mycobacterium leprae makes it difficult to predict the impact of leprosy control interventions. Genotypic tests that allow tracking of individual bacterial strains would strengthen epidemiological studies and contribute to our understanding of the disease.Genotyping assays based on variation in the copy number of short tandem repeat sequences were applied to biopsies collected in population-based epidemiological studies of leprosy in northern Malawi, and from members of multi-case households in Hyderabad, India. In the Malawi series, considerable genotypic variability was observed between patients, and also within patients, when isolates were collected at different times or from different tissues. Less within-patient variability was observed when isolates were collected from similar tissues at the same time. Less genotypic variability was noted amongst the closely related Indian patients than in the Malawi series.Lineages of M. leprae undergo changes in their pattern of short tandem repeat sequences over time. Genetic divergence is particularly likely between bacilli inhabiting different (e.g., skin and nerve tissues. Such variability makes short tandem repeat sequences unsuitable as a general tool for population-based strain typing of M. leprae, or for distinguishing relapse from reinfection. Careful use of these markers may provide insights into the development of disease within individuals and for tracking of short transmission chains.

River water remediation using pulsed corona, pulsed spark or ozonation

Energy Technology Data Exchange (ETDEWEB)

Izdebski, T.; Dors, M. [Polish Academy of Sciences, Szewalski Inst. of Fluid Flow Machiney, Fiszera (Poland). Centre for Plasma and Laser Engineering; Mizeraczyk, J. [Polish Academy of Sciences, Szewalski Inst. of Fluid Flow Machiney, Fiszera (Poland). Centre for Plasma and Laser Engineering; Gdynia Maritime Univ., Morska (Poland). Dept. of Marine Electronics

2010-07-01

The most common reason for epidemic formation is the pollution of surface and drinking water by wastewater bacteria. Pathogenic microorganisms that form the largest part of this are fecal bacteria, such as escherichia coli (E. coli). Wastewater treatment plants reduce the amount of the fecal bacteria by 1-3 orders of magnitude, depending on the initial number of bacteria. There is a lack of data on waste and drinking water purification by the electrohydraulic discharges method, which causes the destruction and inactivation of viruses, yeast, and bacteria. This paper investigated river water cleaning from microorganisms using pulsed corona, spark discharge and ozonization. The paper discussed the experimental setup and results. It was concluded that ozonization is the most efficient method of water disinfection as compared with pulsed spark and pulsed corona discharges. The pulsed spark discharge in water was capable of killing all microorganism similarly to ozonization, but with much lower energy efficiency. The pulsed corona discharge was found to be the less effective method of water disinfection. 21 refs., 4 figs.

Physical model of reactor pulse

International Nuclear Information System (INIS)

Petrovic, A.; Ravnik, M.

2004-01-01

Pulse experiments have been performed at J. Stefan Institute TRIGA reactor since 1991. In total, more than 130 pulses have been performed. Extensive experimental information on the pulse physical characteristics has been accumulated. Fuchs-Hansen adiabatic model has been used for predicting and analysing the pulse parameters. The model is based on point kinetics equation, neglecting the delayed neutrons and assuming constant inserted reactivity in form of step function. Deficiencies of the Fuchs-Hansen model and systematic experimental errors have been observed and analysed. Recently, the pulse model was improved by including the delayed neutrons and time dependence of inserted reactivity. The results explain the observed non-linearity of the pulse energy for high pulses due to finite time of pulse rod withdrawal and the contribution of the delayed neutrons after the prompt part of the pulse. The results of the improved model are in good agreement with experimental results. (author)

Monte Carlo modeling and analyses of YALINA- booster subcritical assembly Part II: pulsed neutron source

International Nuclear Information System (INIS)

Talamo, A.; Gohar, M.Y.A.; Rabiti, C.

2008-01-01

One of the most reliable experimental methods for measuring the kinetic parameters of a subcritical assembly is the Sjoestrand method applied to the reaction rate generated from a pulsed neutron source. This study developed a new analytical methodology for characterizing the kinetic parameters of a subcritical assembly using the Sjoestrand method, which allows comparing the analytical and experimental time dependent reaction rates and the reactivity measurements. In this methodology, the reaction rate, detector response, is calculated due to a single neutron pulse using MCNP/MCNPX computer code or any other neutron transport code that explicitly simulates the fission delayed neutrons. The calculation simulates a single neutron pulse over a long time period until the delayed neutron contribution to the reaction is vanished. The obtained reaction rate is superimposed to itself, with respect to the time, to simulate the repeated pulse operation until the asymptotic level of the reaction rate, set by the delayed neutrons, is achieved. The superimposition of the pulse to itself was calculated by a simple C computer program. A parallel version of the C program is used due to the large amount of data being processed, e.g. by the Message Passing Interface (MPI). The new calculation methodology has shown an excellent agreement with the experimental results available from the YALINA-Booster facility of Belarus. The facility has been driven by a Deuterium-Deuterium or Deuterium-Tritium pulsed neutron source and the (n,p) reaction rate has been experimentally measured by a 3 He detector. The MCNP calculation has utilized the weight window and delayed neutron biasing variance reduction techniques since the detector volume is small compared to the assembly volume. Finally, this methodology was used to calculate the IAEA benchmark of the YALINA-Booster experiment

Reject/repeat analysis and the effect prior film viewing has on a department's reject/repeat rate

International Nuclear Information System (INIS)

Clark, P.A.; Hogg, P.

2003-01-01

Purpose: Achieving cost-effectiveness within the NHS is an old initiative but one that has again been highlighted by recent government policies (The New NHS-Modern and Dependable, Stationary Office, London, 1997). It has been reiterated that it is the responsibility of individual Trusts to devise means to provide such a service. Reject/repeat analyses have long been the primary tool used to assess the cost-effectiveness of radiography departments (Quality Assurance in Diagnostic Radiology, WHO, Geneva, 1982). This research paper examines an in-house initiative (viewing patients' previous films) commonly employed in other Health Trusts in order to reduce departmental repeat/reject rates. Method: Three hundred orthopaedic patients with hip, knee and ankle prostheses were included in a reject/repeat analysis. The aim was to investigate whether or not viewing patient's previous relevant radiographs would be advantageous to the practicing radiographer. This was done through an audit cycle consisting of two audit periods each lasting for 3 months. The primary audit period recorded the baseline repeat/reject rate, with the secondary audit period recording the repeat/reject rate under an experimental condition of viewing the relevant radiographs. Results: The baseline audit revealed repeat rates of 33% in orthopaedic patients with hip, knee and ankle prostheses. The availability of prior film viewing to the radiographer reduced this repeat rate to 10.6%. Conclusion: Prior film viewing dramatically reduced the department's repeat/reject rate by 22.4%. This provides scope for significant patient dose reductions as well as reducing departmental film expenses. This is an underestimated initiative and should be used appropriately in routine clinical practice

Dual-Pulse Pulse Position Modulation (DPPM) for Deep-Space Optical Communications: Performance and Practicality Analysis

Science.gov (United States)

Li, Jing; Hylton, Alan; Budinger, James; Nappier, Jennifer; Downey, Joseph; Raible, Daniel

2012-01-01

Due to its simplicity and robustness against wavefront distortion, pulse position modulation (PPM) with photon counting detector has been seriously considered for long-haul optical wireless systems. This paper evaluates the dual-pulse case and compares it with the conventional single-pulse case. Analytical expressions for symbol error rate and bit error rate are first derived and numerically evaluated, for the strong, negative-exponential turbulent atmosphere; and bandwidth efficiency and throughput are subsequently assessed. It is shown that, under a set of practical constraints including pulse width and pulse repetition frequency (PRF), dual-pulse PPM enables a better channel utilization and hence a higher throughput than it single-pulse counterpart. This result is new and different from the previous idealistic studies that showed multi-pulse PPM provided no essential information-theoretic gains than single-pulse PPM.

Controlled generation of a single Trichel pulse and a series of single Trichel pulses in air

Science.gov (United States)

Mizeraczyk, Jerzy; Berendt, Artur; Akishev, Yuri

2018-04-01

In this paper, a simple method for the controlled generation of a single Trichel pulse or a series of single Trichel pulses of a regulated repetition frequency in air is proposed. The concept of triggering a single Trichel pulse or a series of such pulses is based on the precise controlling the voltage inception of the negative corona, which can be accomplished through the use of a ramp voltage pulse or a series of such pulses with properly chosen ramp voltage pulse parameters (rise and fall times, and ramp voltage pulse repetition frequency). The proposal has been tested in experiments using a needle-to-plate electrode arrangement in air, and reproducible Trichel pulses (single or in a series) were obtained by triggering them with an appropriately designed voltage waveform. The proposed method and results obtained have been qualitatively analysed. The analysis provides guidance for designing the voltage ramp pulse in respect of the generation of a single Trichel pulse or a series of single Trichel pulses. The controlled generation of a single Trichel pulse or a series of such pulses would be a helpful research tool for the refined studies of the fundamental processes in a negative corona discharge in a single- (air is an example) and multi-phase gaseous fluids. The controlled generation of a single Trichel pulse or a series of Trichel pulses can also be attractive for those corona treatments which need manipulation of the electric charge and heat portions delivered by the Trichel pulses to the object.

A high pulsed power supply system designed for pulsed high magnetic field

International Nuclear Information System (INIS)

Liu Kefu; Wang Shaorong; Zhong Heqing; Xu Yan; Pan Yuan

2008-01-01

This paper introduces the design of high pulsed power supply system for producing pulsed high magnetic field up to 70 T. This system consists of 58 sets of 55 μF of capacitor bank which provides 1.0 MJ energy storage. A set of vacuum closing switch is chosen as main switch for energy discharge into magnetic coil. A crowbar circuit with high power diodes in series with resistor is used to absorb the redundant energy and adjust pulse width. The resistance of magnetic coil changing with current is deduced by energy balance equations. A capacitor-charging power supply using a series-resonant, constant on-time variable frequency control, and zero-current switching charges the capacitor bank in one minute time with high efficiency. The pulsed power supply provides adjustable current and pulse width with 30 kA peak and 30 ms maximum. The primary experiments demonstrate the system reliability. This work provides an engineering guidance for future development of pulsed high magnetic field. (authors)

CW seeded optical parametric amplifier providing wavelength and pulse duration tunable nearly transform limited pulses.

Science.gov (United States)

Hädrich, S; Gottschall, T; Rothhardt, J; Limpert, J; Tünnermann, A

2010-02-01

An optical parametric amplifier that delivers nearly transform limited pulses is presented. The center wavelength of these pulses can be tuned between 993 nm and 1070 nm and, at the same time, the pulse duration is varied between 206 fs and 650 fs. At the shortest pulse duration the pulse energy was increased up to 7.2 microJ at 50 kHz repetition rate. Variation of the wavelength is achieved by applying a tunable cw seed while the pulse duration can be varied via altering the pump pulse duration. This scheme offers superior flexibility and scaling possibilities.

Nonlinear Pulse Shaping in Fibres for Pulse Generation and Optical Processing

Directory of Open Access Journals (Sweden)

Sonia Boscolo

2012-01-01

Full Text Available The development of new all-optical technologies for data processing and signal manipulation is a field of growing importance with a strong potential for numerous applications in diverse areas of modern science. Nonlinear phenomena occurring in optical fibres have many attractive features and great, but not yet fully explored, potential in signal processing. Here, we review recent progress on the use of fibre nonlinearities for the generation and shaping of optical pulses and on the applications of advanced pulse shapes in all-optical signal processing. Amongst other topics, we will discuss ultrahigh repetition rate pulse sources, the generation of parabolic shaped pulses in active and passive fibres, the generation of pulses with triangular temporal profiles, and coherent supercontinuum sources. The signal processing applications will span optical regeneration, linear distortion compensation, optical decision at the receiver in optical communication systems, spectral and temporal signal doubling, and frequency conversion.

Pulsed neutron generator for use with pulsed neutron activation techniques

International Nuclear Information System (INIS)

Rochau, G.E.

1980-01-01

A high-output, transportable, pulsed neutron generator has been developed by Sandia National Laboratories for use with Pulsed Neutron Activation (PNA) techniques. The PNA neutron generator generates > 10 10 14 MeV D-T neutrons in a 1.2 millisecond pulse. Each operation of the unit will produce a nominal total neutron output of 1.2 x 10 10 neutrons. The generator has been designed to be easily repaired and modified. The unit requires no additional equipment for operation or measurement of output

Effect of laser pulse energies in laser induced breakdown spectroscopy in double-pulse configuration

International Nuclear Information System (INIS)

Benedetti, P.A.; Cristoforetti, G.; Legnaioli, S.; Palleschi, V.; Pardini, L.; Salvetti, A.; Tognoni, E.

2005-01-01

In this paper, the effect of laser pulse energy on double-pulse laser induced breakdown spectroscopy signal is studied. In particular, the energy of the first pulse has been changed, while the second pulse energy is held fixed. A systematic study of the laser induced breakdown spectroscopy signal dependence on the interpulse delay is performed, and the results are compared with the ones obtained with a single laser pulse of energy corresponding to the sum of the two pulses. At the same time, the crater formed at the target surface is studied by video-confocal microscopy, and the variation in crater dimensions is correlated to the enhancement of the laser induced breakdown spectroscopy signal. The results obtained are consistent with the interpretation of the double-pulse laser induced breakdown spectroscopy signal enhancement in terms of the changes in ambient gas pressure produced by the shock wave induced by the first laser pulse

Dose reduction in pulsed fluoroscopy by modifying the high-voltage pulse shape

International Nuclear Information System (INIS)

Sabau, M.N.; Phelps, G.

1988-01-01

This paper presents the dose reduction results in pulsed fluoroscopy by modifying the high-voltage pulse shape (HVPS). Since the HVPS in regular pulsed fluoroscopy has a long tail, the radiation pulse shape (RPS) is similar. Using specially designed circuitry in the high-voltage generator to produce a rectangular HVPS, and consequently a rectangular RPS, it was possible to obtain a reduction of up to 25% of patient exposure. This dose reduction obtained by cutting the long tail of RPS does not damage the image quality

Apparatus for generating nonlinear pulse patterns

Science.gov (United States)

Nakamura, N.M.I.

Apparatus for generating a plurality of nonlinear pulse patterns from a single linear pulse pattern. A first counter counts the pulses of the linear pulse pattern and a second counter counts the pulses of the nonlinear pulse pattern. A comparator compares the counts of both counters, and in response to an equal count, a gate is enabled to gate a pulse of the linear pattern as a pulse of the nonlinear pattern, the latter also resetting the first counter. Presettable dividers divide the pulses of each pattern before they are counted by the respective counters. Apparatus for generating a logarithmic pulse pattern from a linear pulse pattern to any log base is described. In one embodiment, a shift register is used in place of the second counter to be clocked by each pulse of the logarithmic pattern to generate the pattern. In another embodiment, a memory stores the logarithmic pattern and is addressed by the second counter which is clocked by the pulses of the logarithmic pulse pattern.

Pulsed neutron generator for mass flow measurement using the pulsed neutron activation technique

International Nuclear Information System (INIS)

Rochau, G.E.; Hornsby, D.R.; Mareda, J.F.; Riggan, W.C.

1980-01-01

A high-output, transportable neutron generator has been developed to measure mass flow velocities in reactor safety tests using the Pulsed Neutron Activation (PNA) Technique. The PNA generator produces >10 10 14 MeV D-T neutrons in a 1.2 millisecond pulse. The Millisecond Pulse (MSP) Neutron Tube, developed for this application, has an expected operational life of 1000 pulses, and it limits the generator pulse repetition rate to 12 pulses/minute. A semiconductor neutron detector is included in the generator package to monitor the neutron output. The control unit, which can be operated manually or remotely, also contains a digital display with a BCD output for the neutron monitor information. The digital logic of the unit controls the safety interlocks and rejects transient signals which could accidently fire the generator

Repeating Marx

DEFF Research Database (Denmark)

Fuchs, Christian; Monticelli, Lara

2018-01-01

This introduction sets out the context of the special issue “Karl Marx @ 200: Debating Capitalism & Perspectives for the Future of Radical Theory”, which was published on the occasion of Marx’s bicentenary on 5 May 2018. First, we give a brief overview of contemporary capitalism’s development...... and its crises. Second, we argue that it is important to repeat Marx today. Third, we reflect on lessons learned from 200 years of struggles for alternatives to capitalism. Fourth, we give an overview of the contributions in this special issue. Taken together, the contributions in this special issue show...... that Marx’s theory and politics remain key inspirations for understanding exploitation and domination in 21st-century society and for struggles that aim to overcome these phenomena and establishing a just and fair society. We need to repeat Marx today....

Multilocus Variable-Number Tandem-Repeat Analysis, Pulsed-Field Gel Electrophoresis, and Antimicrobial Susceptibility Patterns in Discrimination of Sporadic and Outbreak-Related Strains of Yersinia enterocolitica

Directory of Open Access Journals (Sweden)

Skurnik Mikael

2011-02-01

Full Text Available Abstract Background We assessed the potential of multilocus variable-number tandem-repeat analysis (MLVA, pulsed-field gel electrophoresis (PFGE, and antimicrobial susceptibility testing for discriminating 104 sporadic and outbreak-related Yersinia enterocolitica (YE bio/serotype 3-4/O:3 and 2/O:9 isolates. MLVA using six VNTR markers was performed in two separate multiplex PCRs, and the fluorescently labeled PCR products were accurately sized on an automated DNA sequencer. Results MLVA discriminated 82 sporadic YE 3-4/O:3 and 2/O:9 strains into 77 types, whereas PFGE with the restriction enzyme NotI discriminated the strains into 23 different PFGE pulsotypes. The discriminatory index for a sporadic strain was 0.862 for PFGE and 0.999 for MLVA. MLVA confirmed that a foodborne outbreak in the city of Kotka, Finland in 2003 had been caused by a multiresistant YE 4/O:3 strain that was distinctly different from those of epidemiologically unrelated strains with an identical PFGE pulsotype. The multiresistance of Y. enterocolitica strains (19% of the sporadic strains correlated significantly (p = 0.002 with travel abroad. All of the multiresistant Y. enterocolitica strains belonged to four PFGE pulsotypes that did not contain any susceptible strains. Resistance to nalidixic acid was related to changes in codons 83 or 87 that stemmed from mutations in the gyrA gene. The conjugation experiments demonstrated that resistance to CHL, STR, and SUL was carried by a conjugative plasmid. Conclusions MLVA using six loci had better discriminatory power than PFGE with the NotI enzyme. MLVA was also a less labor-intensive method than PFGE and the results were easier to analyze. The conjugation experiments demonstrated that a resistance plasmid can easily be transferred between Y. enterocolitica strains. Antimicrobial multiresistance of Y. enterocolitica strains was significantly associated with travel abroad.

High current transistor pulse generator

International Nuclear Information System (INIS)

Nesterov, V.; Cassel, R.

1991-05-01

A solid state pulse generator capable of delivering high current trapezoidally shaped pulses into an inductive load has been developed at SLAC. Energy stored in the capacitor bank of the pulse generator is switched to the load through a pair of Darlington transistors. A combination of diodes and Darlington transistors is used to obtain trapezoidal or triangular shaped current pulses into an inductive load and to recover the remaining energy in the same capacitor bank without reversing capacitor voltage. The transistors work in the switch mode, and the power losses are low. The rack mounted pulse generators presently used at SLAC contain a 660 microfarad storage capacitor bank and can deliver 400 amps at 800 volts into inductive loads up to 3 mH. The pulse generators are used in several different power systems, including pulse to pulse bipolar power supplies and in application with current pulses distributed into different inductive loads. The current amplitude and discharge time are controlled by the central computer system through a specially developed multichannel controller. Several years of operation with the pulse generators have proven their consistent performance and reliability. 8 figs

Evaluation of Patients with an Apparent False Positive Stool DNA Test: The Role of Repeat Stool DNA Testing.

Science.gov (United States)

Cooper, Gregory S; Markowitz, Sanford D; Chen, Zhengyi; Tuck, Missy; Willis, Joseph E; Berger, Barry M; Brenner, Dean E; Li, Li

2018-03-07

There is uncertainty as to the appropriate follow-up of patients who test positive on multimarker stool DNA (sDNA) testing and have a colonoscopy without neoplasia. To determine the prevalence of missed colonic or occult upper gastrointestinal neoplasia in patients with an apparent false positive sDNA. We prospectively identified 30 patients who tested positive with a commercially available sDNA followed by colonoscopy without neoplastic lesions. Patients were invited to undergo repeat sDNA at 11-29 months after the initial test followed by repeat colonoscopy and upper endoscopy. We determined the presence of neoplastic lesions on repeat evaluation stratified by results of repeat sDNA. Twelve patients were restudied. Seven patients had a negative second sDNA test and a normal second colonoscopy and upper endoscopy. In contrast, 5 of 12 subjects had a persistently positive second sDNA test, and 3 had positive findings, including a 3-cm sessile transverse colon adenoma with high-grade dysplasia, a 2-cm right colon sessile serrated adenoma with dysplasia, and a nonadvanced colon adenoma (p = 0.045). These corresponded to a positive predictive value of 0.60 (95% CI 0.17-1.00) and a negative predictive value of 1.00 (95% CI 1.00-1.00) for the second sDNA test. In addition, the medical records of all 30 subjects with apparent false positive testing were reviewed and no documented cases of malignant tumors were recorded. Repeat positive sDNA testing may identify a subset of patients with missed or occult colorectal neoplasia after negative colonoscopy for an initially positive sDNA. High-quality colonoscopy with careful attention to the right colon in patients with positive sDNA is critically important and may avoid false negative colonoscopy.

Design of a bolometer for total-energy measurement of the linear coherent light source pulsed X-ray laser

Energy Technology Data Exchange (ETDEWEB)

Friedrich, S. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 (United States)]. E-mail: Friedrich1@llnl.gov; Li, L. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 (United States); Ott, L.L. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 (United States); Kolgani, Rajeswari M. [Department of Physics, Geosciences and Astronomy, Towson University, 8000 York Avenue, Towson MD 21252 (United States); Yong, G.J. [Department of Physics, Geosciences and Astronomy, Towson University, 8000 York Avenue, Towson MD 21252 (United States); Ali, Z.A. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 (United States); Drury, O.B. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 (United States); Ables, E. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 (United States); Bionta, R.M. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 (United States)

2006-04-15

We are developing a cryogenic bolometer to measure the total energy of the linear coherent light source (LCLS) free electron X-ray laser to be built at the Stanford Linear Accelerator Center. The laser will produce ultrabright X-ray pulses in the energy range between 0.8 and 8 keV with {approx}10{sup 12} photons per {approx}200 fs pulse at a repeat interval of 8 ms, and will be accompanied by a halo of spontaneous undulator radiation. The bolometer is designed to determine the total energy of each laser pulse to within <0.1%, taking into account thermal and mechanical stress to prevent melting in the LCLS beam due to its high energy density. We propose to use a magnetoresistive Nd{sub (1-} {sub x} {sub )}Sr {sub x} MnO{sub 3} sensor array at the metal-insulator transition, where the composition x is adjusted to produce the desired transition temperature. We discuss design considerations and material choices, and present numerical simulations of the thermal response.

Pulse power modulators - an overview

International Nuclear Information System (INIS)

Venkatramani, N.

2006-01-01

Pulse power modulators are electronic devices to provide, high voltage, high current, power bursts. Ideally, a modulator, with the means to shape and control the pulses, acts as a switch between a high voltage power supply and its load. This article gives an overview of the pulse power modulators: starting with the basics of pulse and modulation, it covers modulation topologies, different types of modulators, major subsystems and pulse measurement techniques. The various applications of pulse power modulators and the recent trends have been included at the end. (author)

Ultrashort laser pulses and electromagnetic pulse generation in air and on dielectric surfaces

International Nuclear Information System (INIS)

Sprangle, P.; Penano, J.R.; Hafizi, B.; Kapetanakos, C.A.

2004-01-01

Intense, ultrashort laser pulses propagating in the atmosphere have been observed to emit sub-THz electromagnetic pulses (EMPS). The purpose of this paper is to analyze EMP generation from the interaction of ultrashort laser pulses with air and with dielectric surfaces and to determine the efficiency of conversion of laser energy to EMP energy. In our self-consistent model the laser pulse partially ionizes the medium, forms a plasma filament, and through the ponderomotive forces associated with the laser pulse, drives plasma currents which are the source of the EMP. The propagating laser pulse evolves under the influence of diffraction, Kerr focusing, plasma defocusing, and energy depletion due to electron collisions and ionization. Collective effects and recombination processes are also included in the model. The duration of the EMP in air, at a fixed point, is found to be a few hundred femtoseconds, i.e., on the order of the laser pulse duration plus the electron collision time. For steady state laser pulse propagation the flux of EMP energy is nonradiative and axially directed. Radiative EMP energy is present only for nonsteady state or transient laser pulse propagation. The analysis also considers the generation of EMP on the surface of a dielectric on which an ultrashort laser pulse is incident. For typical laser parameters, the power and energy conversion efficiency from laser radiation to EMP radiation in both air and from dielectric surfaces is found to be extremely small, -8 . Results of full-scale, self-consistent, numerical simulations of atmospheric and dielectric surface EMP generation are presented. A recent experiment on atmospheric EMP generation is also simulated

A method to reduce the suppression of relevant pulses in pulse weight discriminators

International Nuclear Information System (INIS)

Schwartz, P.

1975-01-01

The pulse height analyzer is used, for instance, with proportional counters. Pulses are broken down into amplitude ranges in accordance with their maximum amplitudes. In pulse height analyzers with real time analog-digital conversion only one deadtime is needed for the respective range selected. For this purpose, all discriminator thresholds of the amplitude stores connected parallel are actuated as an input pulse arrives. The leading edges of the discriminator signals set the amplitude range flip-flop. Only the flip-flop circuit of the maximum amplitude range reached remains set whilst all the others are erased. The trailing edge of the discriminator signals actuates the evaluation of the information stored by the flip-flop circuit selected. It triggers a pulse extender and resets the flip-flop selected. Therefore, only the amplitude range selected needs a deadtime. The pulse extender in addition reduces the processing time of the analyzer by the output pulse length. The characteristic used for the trailing edge is the backward count of the real time analog-digital converter. (DG/RF) [de

Pulsed corona generation using a diode-based pulsed power generator

Science.gov (United States)

Pemen, A. J. M.; Grekhov, I. V.; van Heesch, E. J. M.; Yan, K.; Nair, S. A.; Korotkov, S. V.

2003-10-01

Pulsed plasma techniques serve a wide range of unconventional processes, such as gas and water processing, hydrogen production, and nanotechnology. Extending research on promising applications, such as pulsed corona processing, depends to a great extent on the availability of reliable, efficient and repetitive high-voltage pulsed power technology. Heavy-duty opening switches are the most critical components in high-voltage pulsed power systems with inductive energy storage. At the Ioffe Institute, an unconventional switching mechanism has been found, based on the fast recovery process in a diode. This article discusses the application of such a "drift-step-recovery-diode" for pulsed corona plasma generation. The principle of the diode-based nanosecond high-voltage generator will be discussed. The generator will be coupled to a corona reactor via a transmission-line transformer. The advantages of this concept, such as easy voltage transformation, load matching, switch protection and easy coupling with a dc bias voltage, will be discussed. The developed circuit is tested at both a resistive load and various corona reactors. Methods to optimize the energy transfer to a corona reactor have been evaluated. The impedance matching between the pulse generator and corona reactor can be significantly improved by using a dc bias voltage. At good matching, the corona energy increases and less energy reflects back to the generator. Matching can also be slightly improved by increasing the temperature in the corona reactor. More effective is to reduce the reactor pressure.

Cascades on a stochastic pulse-coupled network

Science.gov (United States)

Wray, C. M.; Bishop, S. R.

2014-09-01

While much recent research has focused on understanding isolated cascades of networks, less attention has been given to dynamical processes on networks exhibiting repeated cascades of opposing influence. An example of this is the dynamic behaviour of financial markets where cascades of buying and selling can occur, even over short timescales. To model these phenomena, a stochastic pulse-coupled oscillator network with upper and lower thresholds is described and analysed. Numerical confirmation of asynchronous and synchronous regimes of the system is presented, along with analytical identification of the fixed point state vector of the asynchronous mean field system. A lower bound for the finite system mean field critical value of network coupling probability is found that separates the asynchronous and synchronous regimes. For the low-dimensional mean field system, a closed-form equation is found for cascade size, in terms of the network coupling probability. Finally, a description of how this model can be applied to interacting agents in a financial market is provided.

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

KAUST Repository

Cenker, Emre

2017-02-27

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

Clinical Observation on Termination of Early Pregnancy of 213 Cases after Caesarian Section with Repeated Use of Mifepristone and Misoprostol

Institute of Scientific and Technical Information of China (English)

高佩佩; 汪平

1999-01-01

Objective To investigate the efficacy and safety in women after caesarian section for termination of early pregnancies by treatment, or repeated treatment with mifepristone and misoprostot.Subjects and Methods A total of 213 pregnant women with amenorrhea of 34-69d after caesarian section who asked for medical abortion were recruited,including 63 cases undergoing their second medical abortion.A total amount of mi feprisstone of 150 mg given in separate doses(25 mg×4 and 50 mg at the first time)was administered orally within 3d, followed by misoprostot of 0.6 mg orally in the morning of d 3.Results The complete abortion rate was 92.5%,incomplete abortion was 4.7% and failure was 2.8%.Conclusion The sequential use of mifepristone and misoprostol could be successfully and repeatedly used for induced abortion in those women with a caesarian section histo-ry.Its efficacy was similar to that for ordinary population.Its safety and effec-tiveness were satisfactory.

Analysis of repeated measures data

CERN Document Server

Islam, M Ataharul

2017-01-01

This book presents a broad range of statistical techniques to address emerging needs in the field of repeated measures. It also provides a comprehensive overview of extensions of generalized linear models for the bivariate exponential family of distributions, which represent a new development in analysing repeated measures data. The demand for statistical models for correlated outcomes has grown rapidly recently, mainly due to presence of two types of underlying associations: associations between outcomes, and associations between explanatory variables and outcomes. The book systematically addresses key problems arising in the modelling of repeated measures data, bearing in mind those factors that play a major role in estimating the underlying relationships between covariates and outcome variables for correlated outcome data. In addition, it presents new approaches to addressing current challenges in the field of repeated measures and models based on conditional and joint probabilities. Markov models of first...

Pulse-driven micro gas sensor fitted with clustered Pd/SnO2 nanoparticles.

Science.gov (United States)

Suematsu, Koichi; Shin, Yuka; Ma, Nan; Oyama, Tokiharu; Sasaki, Miyuki; Yuasa, Masayoshi; Kida, Tetsuya; Shimanoe, Kengo

2015-08-18

Real-time monitoring of specific gas concentrations with a compact and portable gas sensing device is required to sense potential health risk and danger from toxic gases. For such purposes, we developed an ultrasmall gas sensor device, where a micro sensing film was deposited on a micro heater integrated with electrodes fabricated by the microelectromechanical system (MEMS) technology. The developed device was operated in a pulse-heating mode to significantly reduce the heater power consumption and make the device battery-driven and portable. Using clustered Pd/SnO2 nanoparticles, we succeeded in introducing mesopores ranging from 10 to 30 nm in the micro gas sensing film (area: ϕ 150 μm) to detect large volatile organic compounds (VOCs). The micro sensor showed quick, stable, and high sensor responses to toluene at ppm (parts per million) concentrations at 300 °C even by operating the micro heater in a pulse-heating mode where switch-on and -off cycles were repeated at one-second intervals. The high performance of the micro sensor should result from the creation of efficient diffusion paths decorated with Pd sensitizers by using the clustered Pd/SnO2 nanoparticles. Hence we demonstrate that our pulse-driven micro sensor using nanostructured oxide materials holds promise as a battery-operable, portable gas sensing device.

Laser ablation comparison by picosecond pulses train and nanosecond pulse

Science.gov (United States)

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

2015-12-01

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

Particle acceleration by electromagnetic pulses

International Nuclear Information System (INIS)

Lai, H.M.

1982-01-01

Particle interaction with plane electromagnetic pulses is studied. It is shown that particle acceleration by a wavy pulse, depending on the shape of the pulse, may not be small. Further, a diffusive-type particle acceleration by multiple weak pulses is described and discussed. (author)

Hybrid Pulsed Nd:YAG Laser

Science.gov (United States)

Miller, Sawyer; Trujillo, Skyler; Fort Lewis College Laser Group Team

This work concerns the novel design of an inexpensive pulsed Nd:YAG laser, consisting of a hybrid Kerr Mode Lock (KLM) and Q-switch pulse. The two pulse generation systems work independently, non simultaneously of each other, thus generating the ability for the user to easily switch between ultra-short pulse widths or large energy density pulses. Traditionally, SF57 glass has been used as the Kerr medium. In this work, novel Kerr mode-locking mediums are being investigated including: tellurite compound glass (TeO2), carbon disulfide (CS2), and chalcogenide glass. These materials have a nonlinear index of refraction orders of magnitude,(n2), larger than SF57 glass. The Q-switched pulse will utilize a Pockels cell. As the two pulse generation systems cannot be operated simultaneously, the Pockels cell and Kerr medium are attached to kinematic mounts, allowing for quick interchange between systems. Pulse widths and repetition rates will vary between the two systems. A goal of 100 picosecond pulse widths are desired for the mode-locked system. A goal of 10 nanosecond pulse widths are desired for the Q-switch system, with a desired repetition rate of 50 Hz. As designed, the laser will be useful in imaging applications.

Modeling study on the effects of pulse rise rate in atmospheric pulsed discharges

Science.gov (United States)

Zhang, Yuan-Tao; Wang, Yan-Hui

2018-02-01

In this paper, we present a modeling study on the discharge characteristics driven by short pulsed voltages, focusing on the effects of pulse rise rate based on the fluid description of atmospheric plasmas. The numerical results show that the breakdown voltage of short pulsed discharge is almost linearly dependent on the pulse rise rate, which is also confirmed by the derived equations from the fluid model. In other words, if the pulse rise rate is fixed as a constant, the simulation results clearly suggest that the breakdown voltage is almost unchanged, although the amplitude of pulsed voltage increases significantly. The spatial distribution of the electric field and electron density are given to reveal the underpinning physics. Additionally, the computational data and the analytical expression also indicate that an increased repetition frequency can effectively decrease the breakdown voltage and current density, which is consistent with the experimental observation.

Intense isolated attosecond pulse generation from relativistic laser plasmas using few-cycle laser pulses

International Nuclear Information System (INIS)

Ma, Guangjin; Dallari, William; Borot, Antonin; Tsakiris, George D.; Veisz, Laszlo; Krausz, Ferenc; Yu, Wei

2015-01-01

We have performed a systematic study through particle-in-cell simulations to investigate the generation of attosecond pulse from relativistic laser plasmas when laser pulse duration approaches the few-cycle regime. A significant enhancement of attosecond pulse energy has been found to depend on laser pulse duration, carrier envelope phase, and plasma scale length. Based on the results obtained in this work, the potential of attaining isolated attosecond pulses with ∼100 μJ energy for photons >16 eV using state-of-the-art laser technology appears to be within reach

Two-photon interference of weak coherent laser pulses recalled from separate solid-state quantum memories

Science.gov (United States)

Jin, Jeongwan; Slater, Joshua A.; Saglamyurek, Erhan; Sinclair, Neil; George, Mathew; Ricken, Raimund; Oblak, Daniel; Sohler, Wolfgang; Tittel, Wolfgang

2013-08-01

Quantum memories allowing reversible transfer of quantum states between light and matter are central to quantum repeaters, quantum networks and linear optics quantum computing. Significant progress regarding the faithful transfer of quantum information has been reported in recent years. However, none of these demonstrations confirm that the re-emitted photons remain suitable for two-photon interference measurements, such as C-NOT gates and Bell-state measurements, which constitute another key ingredient for all aforementioned applications. Here, using pairs of laser pulses at the single-photon level, we demonstrate two-photon interference and Bell-state measurements after either none, one or both pulses have been reversibly mapped to separate thulium-doped lithium niobate waveguides. As the interference is always near the theoretical maximum, we conclude that our solid-state quantum memories, in addition to faithfully mapping quantum information, also preserve the entire photonic wavefunction. Hence, our memories are generally suitable for future applications of quantum information processing that require two-photon interference.

Two-photon interference of weak coherent laser pulses recalled from separate solid-state quantum memories.

Science.gov (United States)

Jin, Jeongwan; Slater, Joshua A; Saglamyurek, Erhan; Sinclair, Neil; George, Mathew; Ricken, Raimund; Oblak, Daniel; Sohler, Wolfgang; Tittel, Wolfgang

2013-01-01

Quantum memories allowing reversible transfer of quantum states between light and matter are central to quantum repeaters, quantum networks and linear optics quantum computing. Significant progress regarding the faithful transfer of quantum information has been reported in recent years. However, none of these demonstrations confirm that the re-emitted photons remain suitable for two-photon interference measurements, such as C-NOT gates and Bell-state measurements, which constitute another key ingredient for all aforementioned applications. Here, using pairs of laser pulses at the single-photon level, we demonstrate two-photon interference and Bell-state measurements after either none, one or both pulses have been reversibly mapped to separate thulium-doped lithium niobate waveguides. As the interference is always near the theoretical maximum, we conclude that our solid-state quantum memories, in addition to faithfully mapping quantum information, also preserve the entire photonic wavefunction. Hence, our memories are generally suitable for future applications of quantum information processing that require two-photon interference.

Generalized Ginzburg-Landau equation for self-pulsing instability in a two-photon laser

Energy Technology Data Exchange (ETDEWEB)

Cunzheng, Ning; Haken, H [Inst. fuer Theoretische Physik und Synergetik, Univ. Stuttgart (Germany)

1989-10-01

A nonlinear analysis is made for a degenerate two-photon ring laser near its critical point corresponding to a self-pulsing instability by using the slaving principle and normal form theory. It turns out that the system undergoes two kinds of transitions, a usual Hopf bifurcation to a stable or unstable limit cycle and a co-dimension two Hopf bifurcation where the limit cycles disappear. An analytical criterion is given to distinguish the super - form the sub-critical bifurcation. We have also solved the equations numerically to confirm and to supplement our analytical results. In the case of super-critical bifurcation, a period-doubling bifurcation sequence to chaos is also observed with the decrease in pumping. (orig.).

Electronic system for recording proportional counter rare pulses with the pulse shape analysis

International Nuclear Information System (INIS)

Barabanov, I.R.; Gavrin, V.N.; Zakharov, Yu.I.; Tikhonov, A.A.

1984-01-01

The anutomated system for recording proportional counter rare pulses is described. The proportional counters are aimed at identification of 37 Ar and H7 1 Gr decays in chemical radiation detectors of solar neutrino. Pulse shape recording by means of a storage oscilloscope and a TV display is performed in the system considered besides two-parametric selection of events (measurement of pulse amplitude in a slow channel and the amplitude of pulse differentiated with time constant of about 10 ns in a parallel fast channel). Pulse discrimination by a front rise rate provides background decrease in the 55 Fe range (5.9 keV) by 6 times; the visual analysis of pulse shapes recorded allows to decrease the background additionally by 25-30%. The background counting rate in the 55 Fe range being equal to 1 pulse per 1.5 days, is obtained when using the installation described above, as well as the passive Pb shield 5 cm thick, and the active shield based on the anticoincidence NaI(Tl) detector with the cathode 5.6 mm in-diameter made of Fe fabircated by zone melting. The installation described allows to reach the background level of 0.6 pulse/day (the total coefficient of background attenuation is 400). Further background decrease is supposed to be provided by installation allocation in the low-noise underground laboratory of the Baksan Neutrino Observatory

Pulsed corona generation using a diode-based pulsed power generator

NARCIS (Netherlands)

Pemen, A.J.M.; Grekhov, I.V.; Heesch, van E.J.M.; Yan, K.; Nair, S.A.; Korotkov, S.V.

2003-01-01

Pulsed plasma techniques serve a wide range of unconventional processes, such as gas and water processing, hydrogen production, and nanotechnology. Extending research on promising applications, such as pulsed corona processing, depends to a great extent on the availability of reliable, efficient and

High dose-per-pulse electron beam dosimetry: Commissioning of the Oriatron eRT6 prototype linear accelerator for preclinical use.

Science.gov (United States)

Jaccard, Maud; Durán, Maria Teresa; Petersson, Kristoffer; Germond, Jean-François; Liger, Philippe; Vozenin, Marie-Catherine; Bourhis, Jean; Bochud, François; Bailat, Claude

2018-02-01

The Oriatron eRT6 is an experimental high dose-per-pulse linear accelerator (linac) which was designed to deliver an electron beam with variable dose-rates, ranging from a few Gy/min up to hundreds of Gy/s. It was built to study the radiobiological effects of high dose-per-pulse/dose-rate electron beam irradiation, in the context of preclinical and cognitive studies. In this work, we report on the commissioning and beam monitoring of the Oriatron eRT6 prototype linac. The beam was characterized in different steps. The output stability was studied by performing repeated measurements over a period of 20 months. The relative output variations caused by changing beam parameters, such as the temporal electron pulse width, the pulse repetition frequency and the pulse amplitude were also analyzed. Finally, depth dose curves and field sizes were measured for two different beam settings, resulting in one beam with a conventional radiotherapy dose-rate and one with a much higher dose-rate. Measurements were performed with Gafchromic EBT3 films and with a PTW Advanced Markus ionization chamber. In addition, we developed a beam current monitoring system based on the signals from an induction torus positioned at the beam exit of the waveguide and from a graphite beam collimator. The stability of the output over repeated measurements was found to be good, with a standard deviation smaller than 1%. However, non-negligible day-to-day variations of the beam output were observed. Those output variations showed different trends depending on the dose-rate. The analysis of the relative output variation as a function of various beam parameters showed that in a given configuration, the dose-rate could be reliably varied over three orders of magnitude. Interdependence effects on the output variation between the parameters were also observed. The beam energy and field size were found to be slightly dose-rate-dependent and suitable mainly for small animal irradiation. The beam monitoring

Ultrashort Laser Pulse Phenomena

CERN Document Server

Diels, Jean-Claude

2006-01-01

Ultrashort Laser Pulse Phenomena, 2e serves as an introduction to the phenomena of ultra short laser pulses and describes how this technology can be used to examine problems in areas such as electromagnetism, optics, and quantum mechanics. Ultrashort Laser Pulse Phenomena combines theoretical backgrounds and experimental techniques and will serve as a manual on designing and constructing femtosecond (""faster than electronics"") systems or experiments from scratch. Beyond the simple optical system, the various sources of ultrashort pulses are presented, again with emphasis on the basic

Multimode pulse counter

International Nuclear Information System (INIS)

Natanzon, D.D.

1982-01-01

A pulse counter with code conversion is described. The counter is based on the integrated circuits of direct-counting devices of medium integration. The counter ensures various modes of pulse counting depending on the logical control signals: reversible, two-channel summing, one-channel summing binary, summing with ''storage'' signal code fixation without interrupting pulse counting. Arrangement of the suggested structure as a microcircuit of medium integration might contribute to reduction in the counter type nomenclature in digital families of widely used integrated circuits

Powerful nanosecond pulse train generator

International Nuclear Information System (INIS)

Isakov, I.F.; Logachev, E.I.; Opekunov, M.S.; Pechenkin, S.A.; Remnev, G.E.; Usov, Yu.P.

1987-01-01

A generator permitting to shape on the load pulsed with the repetition frequency of 10 3 -10 6 Hz and more is described. The amplitude of shaped voltage pulses is up to 150 kV at pulse duration equal to 50 ns. The generator comprises connected in-series with the load two shaping and two transmission lines realized on the base of the KVI-300 low-ohmic cable. The shaping lines are supplied from two independently connected pulse voltage generators for obtaining time interval between pulses > 10 -6 s; they may be also supplied from one generator for obtaining time interval -6 s. At the expense of reducing losses in the discharge circuit the amplitude of the second pulse grows with increase of time interval between pulses up to 300 ns, further on the curve flat-topping exists. The described generator is used in high-current accelerators, in which the primary negative pulse results in generation of explosive-emission plasma, and the second positive pulse provides ion beam shaping including ions of heavy metal used for production of a potential electrode. The generator multipulse mode is used for successive ion acceleration in the transport system

Generation of Attosecond x-ray pulse using Coherent Relativistic Nonlinear Thomson Scattering

Energy Technology Data Exchange (ETDEWEB)

Lee, Ki Tae; Park, Seong Hee; Cha, Yong Ho; Jeong, Young Uk; Lee, Byung Cheol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2005-07-01

Relativistic plasma, a new regime in physics, has been opened due to the development in ultra-intense laser technology during the past decade. Not only the fundamental aspect of relativistic plasma are attractive but also its potential application seems to be significant especially in the area of the generation of high energy particles such as electrons, ions, positrons, and {gamma}-rays. The generation of x-ray radiation with a pulse width of sub-femtoseconds presently draws much attention because such a radiation allows one to explore ultra-fast dynamics of electrons and nucleons. Several schemes have been proposed and/or demonstrated to generate an ultra-short x-ray pulse: the relativistic Doppler shift of a backscattered laser pulse by a relativistic electron beam, the harmonic frequency upshift of a laser pulse by relativistic nonlinear motion of electrons, high order harmonic generation in the interaction of intense laser pulse with noble gases and solids The train of a few 100 attosecond pulses has been observed in the case of laser-noble gas interaction. When a low-intensity laser pulse is irradiated on an electron, the electron undergoes a harmonic oscillatory motion and generates a dipole radiation with the same frequency as the incident laser pulse, which is called Thomson scattering. As the laser intensity increases, the oscillatory motion of the electron becomes relativistically nonlinear, which leads to the generation of harmonic radiations, referred to as Relativistic Nonlinear Thomson Scattered (RNTS) radiation. The motion of the electron begins to be relativistic as the following normalized vector potential approaches to unity: a{sub 0}=8.5 x 10{sup -10} {lambda}{iota}{sup 1/2} , (1) where {lambda} is the laser wavelength in {mu}m and I the laser intensity in W/cm{sup 2} The RNTS radiation has been investigated in analytical ways. Recently, indebted to the development of the ultra-intense laser pulse, experiments on RNTS radiation have been carried

RIIM two-pulse injector experiments

International Nuclear Information System (INIS)

Mazarakis, M.G.; Smith, D.L.; Jones, E.E.; Hasti, D.E.; Jojola, J.M.; Lehmann, M.

1987-01-01

The RADLAC-II foilless diode injector was operated under double pulse conditions utilizing the RIIM accelerator as the test bed. The original RIIM accelerator pulse-power network was modified to provide for the generation, transmission, and delivery to the foilless diode of two distinct voltage pulses with variable interpulse separation from 0 to 2 ms. Two pulse-power assemblies were investigated and will be presented in connection with the diode performance. In both cases, the generated plasma and an excessive neutral gas release, following the first pulse, prevented the diode from producing a second beam pulse for interpulse separations larger than ∼1 μs. 4 refs

Coiled transmission line pulse generators

Science.gov (United States)

McDonald, Kenneth Fox

2010-11-09

Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

A 70 kV solid-state high voltage pulse generator based on saturable pulse transformer.

Science.gov (United States)

Fan, Xuliang; Liu, Jinliang

2014-02-01

High voltage pulse generators are widely applied in many fields. In recent years, solid-state and operating at repetitive mode are the most important developing trends of high voltage pulse generators. A solid-state high voltage pulse generator based on saturable pulse transformer is proposed in this paper. The proposed generator is consisted of three parts. They are charging system, triggering system, and the major loop. Saturable pulse transformer is the key component of the whole generator, which acts as a step-up transformer and main switch during working process of this generator. The circuit and working principles of the proposed pulse generator are introduced first in this paper, and the saturable pulse transformer used in this generator is introduced in detail. Circuit of the major loop is simulated to verify the design of the system. Demonstration experiments are carried out, and the results show that when the primary energy storage capacitor is charged to a high voltage, such as 2.5 kV, a voltage with amplitude of 86 kV can be achieved on the secondary winding. The magnetic core of saturable pulse transformer is saturated deeply and the saturable inductance of the secondary windings is very small. The switch function of the saturable pulse transformer can be realized ideally. Therefore, a 71 kV output voltage pulse is formed on the load. Moreover, the magnetic core of the saturable pulse transformer can be reset automatically.

Application of the Ethanol-Chlorobenzene Dosimeter to Electron Beam Dosimetry: Pulsed 10 MeV Electrons

Energy Technology Data Exchange (ETDEWEB)

Dvornik, I.; Razem, D.; Baric, M. [Institute ' ' Ruder Boskovic' ' , Zagreb, Yugoslavia (Croatia)

1969-12-15

With gamma irradiation, the ethanol-chlorobenzene chemical dosimetric systems have shown valuable properties. They are simple to prepare and analyse, the G(HC1) values are not sensitive to normal impurities and are constant within the dose range of interest for processing. This paper describes the experiments performed with 10 MeV pulsed electrons from the linear accelerator of the Research Establishment Riso, Denmark (7 microsecond pulses repeated 300 times per second, 10{sup 9} rad/sec in the pulse). The irradiations were calibrated calorimetrically. The G(HC1) values independent of dose up to 40 Mrad are given as a function of chlorobenzene concentration. The comparison with gamma irradiations shows only insignificant differences in the G-values. Above 10 vol. % chlorobenzene the G-values are approximately constant up to 20 Mrad or more, and are to within 2% equal to those obtained for gamma rays with free access of air. The addition of 0.04% of acetone or benzene to the systems had within the experimental error, no influence upon the G(HC1). The results show the applicability of ethanol-chlorobenzene dosimeters to the dosimetry of electron beam irradiations at dose rates as high as 10{sup 9} rad/sec and dosages up to 6 Mrad. (author)

Morbidity of repeat transsphenoidal surgery assessed in more than 1000 operations.

Science.gov (United States)

Jahangiri, Arman; Wagner, Jeffrey; Han, Sung Won; Zygourakis, Corinna C; Han, Seunggu J; Tran, Mai T; Miller, Liane M; Tom, Maxwell W; Kunwar, Sandeep; Blevins, Lewis S; Aghi, Manish K

2014-07-01

OBJECT.: While transsphenoidal surgery is associated with low morbidity, the degree to which morbidity increases after reoperation remains unclear. The authors determined the morbidity associated with repeat versus initial transsphenoidal surgery after 1015 consecutive operations. The authors conducted a 5-year retrospective review of the first 916 patients undergoing transsphenoidal surgery at their institution after a pituitary center of expertise was established, and they analyzed morbidities. The authors analyzed 907 initial and 108 repeat transsphenoidal surgeries performed in 916 patients (9 initial surgeries performed outside the authors' center were excluded). The most common diagnoses were endocrine inactive (30%) or active (36%) adenomas, Rathke's cleft cysts (10%), and craniopharyngioma (3%). Morbidity of initial surgery versus reoperation included diabetes insipidus ([DI] 16% vs 26%; p = 0.03), postoperative hyponatremia (20% vs 16%; p = 0.3), new postoperative hypopituitarism (5% vs 8%; p = 0.3), CSF leak requiring repair (1% vs 4%; p = 0.04), meningitis (0.4% vs 3%; p = 0.02), and length of stay ([LOS] 2.8 vs 4.5 days; p = 0.006). Of intraoperative parameters and postoperative morbidities, 1) some (use of lumbar drain and new postoperative hypopituitarism) did not increase with second or subsequent reoperations (p = 0.3-0.9); 2) some (DI and meningitis) increased upon second surgery (p = 0.02-0.04) but did not continue to increase for subsequent reoperations (p = 0.3-0.9); 3) some (LOS) increased upon second surgery and increased again for subsequent reoperations (p surgery (p = 0.3) but went on to increase upon subsequent reoperations (p = 0.001-0.02). Multivariate analysis revealed that operation number, but not sex, age, pathology, radiation therapy, or lesion size, increased the risk of CSF leak, meningitis, and increased LOS. Separate analysis of initial versus repeat transsphenoidal surgery on the 2 most common benign pituitary lesions

Management of pain on hallux valgus with percutaneous intra-articular Pulse-Dose Radiofrequency.

Science.gov (United States)

Masala, Salvatore; Fiori, Roberto; Calabria, Eros; Raguso, Mario; de Vivo, Dominique; Cuzzolino, Alessandro; Simonetti, Giovanni

2017-01-01

The purpose of our study was to investigate the role of intra-articular pulse-dose radiofrequency in management of painful hallux valgus refractory to conservative therapies. Between November 2010 and April 2012, 51 patients (15 male, 36 female) with a median age of 71.4 years were included in our clinical trial. Under fluoroscopic guidance we introduced a 22 gauge 10 cm length cannula by a percutaneous access in the first metatarsophalangeal joint and its tip was placed intra-articularly. After removing the spindle, a radiofrequency needle with a 5 mm active tip was introduced. The following parameters were used: 1200 pulses at high voltage (45 V) with 20 msec duration followed by 480 msec silent phases. A great reduction in pain intensity was documented at 1 week, 1 month and 3 months after procedures. Pain intensity increased between 5 and 8 months after treatments, so we performed a second procedure in all patients between 7 months and 9 months since the first treatment. Also in this case we obtained a great reduction of pain intensity in the first 3 months after the procedure. Pain intensity returned at preprocedural values after 9 months after second procedure. No complications were observed. Our experience shows pulse-dose radiofrequency is a safe, repeatable and effective technique for managing patients with symptomatic hallux valgus in the short and medium term. Pulse-dose radiofrequency may improve pain control and quality of life in patients with hallux valgus refractory to conservative therapies. © 2014 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd.

High efficiency, monolithic fiber chirped pulse amplification system for high energy femtosecond pulse generation.

Science.gov (United States)

Peng, Xiang; Kim, Kyungbum; Mielke, Michael; Jennings, Stephen; Masor, Gordon; Stohl, Dave; Chavez-Pirson, Arturo; Nguyen, Dan T; Rhonehouse, Dan; Zong, Jie; Churin, Dmitriy; Peyghambarian, N

2013-10-21

A novel monolithic fiber-optic chirped pulse amplification (CPA) system for high energy, femtosecond pulse generation is proposed and experimentally demonstrated. By employing a high gain amplifier comprising merely 20 cm of high efficiency media (HEM) gain fiber, an optimal balance of output pulse energy, optical efficiency, and B-integral is achieved. The HEM amplifier is fabricated from erbium-doped phosphate glass fiber and yields gain of 1.443 dB/cm with slope efficiency >45%. We experimentally demonstrate near diffraction-limited beam quality and near transform-limited femtosecond pulse quality at 1.55 µm wavelength. With pulse energy >100 µJ and pulse duration of 636 fs (FWHM), the peak power is estimated to be ~160 MW. NAVAIR Public Release Distribution Statement A-"Approved for Public release; distribution is unlimited".

simple sequence repeats (EST-SSR)

African Journals Online (AJOL)

Yomi

2012-01-19

Jan 19, 2012 ... 212 primer pairs selected, based on repeat patterns of n≥8 for di-, tri-, tetra- and penta-nucleotide repeat ... Cluster analysis revealed a high genetic similarity among the sugarcane (Saccharum spp.) breeding lines which could reduce the genetic gain in ..... The multiple allele characteristic of SSR com-.

Nifty Nines and Repeating Decimals

Science.gov (United States)

Brown, Scott A.

2016-01-01

The traditional technique for converting repeating decimals to common fractions can be found in nearly every algebra textbook that has been published, as well as in many precalculus texts. However, students generally encounter repeating decimal numerals earlier than high school when they study rational numbers in prealgebra classes. Therefore, how…

Repeated Prescribed Burning in Aspen

Science.gov (United States)

Donald A. Perala

1974-01-01

Infrequent burning weather, low flammability of the aspen-hardwood association, and prolific sprouting and seeding of shrubs and hardwoods made repeated dormant season burning a poor tool to convert good site aspen to conifers. Repeat fall burns for wildlife habitat maintenance is workable if species composition changes are not important.

Postprandial changes in secretory flow of pancreatic juice in the main pancreatic duct: evaluation with cine-dynamic MRCP with a spatially selective inversion-recovery (IR) pulse

International Nuclear Information System (INIS)

Yasokawa, Kazuya; Ito, Katsuyoshi; Tamada, Tsutomu; Yamamoto, Akira; Hayashida, Minoru; Torigoe, Teruyuki; Tanimoto, Daigo; Higaki, Atsushi; Noda, Yasufumi; Kido, Ayumu

2016-01-01

To evaluate the influence of oral ingestion on the secretory flow dynamics of physiological pancreatic juice within the main pancreatic duct in healthy subjects by using cine-dynamic MRCP with spatially-selective inversion-recovery (IR) pulse non-invasively. Thirty-eight healthy subjects were investigated. MRCP with spatially-selective IR pulse was repeated every 15 s for 5 min to acquire a total of 20 images (cine-dynamic MRCP). A set of 20 MRCP images was repeatedly obtained before and after liquid oral ingestion every 7 min (including 2-min interval) for 40 min (a total of seven sets). Secretion grade of pancreatic juice on cine-dynamic MRCP was compared before and after oral ingestion using the nonparametric Wilcoxon signed-rank test. Median secretion grades of pancreatic juice at 5 min (score = 2.15), 12 min (score = 1.95) and 19 min (score = 2.05) after ingestion were significantly higher than that before ingestion (score = 1.40) (P = 0.004, P = 0.032, P = 0.045, respectively). Secretion grade of pancreatic juice showed a maximum peak of 2.15 at 5 min after ingestion. Thereafter, the secretion grade of pancreatic juice tended to gradually decline. Non-invasive cine-dynamic MRCP using spatially-selective IR pulse showed potential for evaluating postprandial changes in the secretory flow dynamics of pancreatic juice as a physiological reaction. (orig.)

Postprandial changes in secretory flow of pancreatic juice in the main pancreatic duct: evaluation with cine-dynamic MRCP with a spatially selective inversion-recovery (IR) pulse

Energy Technology Data Exchange (ETDEWEB)

Yasokawa, Kazuya; Ito, Katsuyoshi; Tamada, Tsutomu; Yamamoto, Akira; Hayashida, Minoru; Torigoe, Teruyuki; Tanimoto, Daigo; Higaki, Atsushi; Noda, Yasufumi; Kido, Ayumu [Kawasaki Medical School, Department of Diagnostic Radiology, Kurashiki, Okayama (Japan)

2016-12-15

To evaluate the influence of oral ingestion on the secretory flow dynamics of physiological pancreatic juice within the main pancreatic duct in healthy subjects by using cine-dynamic MRCP with spatially-selective inversion-recovery (IR) pulse non-invasively. Thirty-eight healthy subjects were investigated. MRCP with spatially-selective IR pulse was repeated every 15 s for 5 min to acquire a total of 20 images (cine-dynamic MRCP). A set of 20 MRCP images was repeatedly obtained before and after liquid oral ingestion every 7 min (including 2-min interval) for 40 min (a total of seven sets). Secretion grade of pancreatic juice on cine-dynamic MRCP was compared before and after oral ingestion using the nonparametric Wilcoxon signed-rank test. Median secretion grades of pancreatic juice at 5 min (score = 2.15), 12 min (score = 1.95) and 19 min (score = 2.05) after ingestion were significantly higher than that before ingestion (score = 1.40) (P = 0.004, P = 0.032, P = 0.045, respectively). Secretion grade of pancreatic juice showed a maximum peak of 2.15 at 5 min after ingestion. Thereafter, the secretion grade of pancreatic juice tended to gradually decline. Non-invasive cine-dynamic MRCP using spatially-selective IR pulse showed potential for evaluating postprandial changes in the secretory flow dynamics of pancreatic juice as a physiological reaction. (orig.)

Magnetic Alignment of Pulsed Solenoids Using the Pulsed Wire Method

International Nuclear Information System (INIS)

Arbelaez, D.; Madur, A.; Lipton, T.M.; Waldron, W.L.; Kwan, J.W.

2011-01-01

A unique application of the pulsed-wire measurement method has been implemented for alignment of 2.5 T pulsed solenoid magnets. The magnetic axis measurement has been shown to have a resolution of better than 25 (micro)m. The accuracy of the technique allows for the identification of inherent field errors due to, for example, the winding layer transitions and the current leads. The alignment system is developed for the induction accelerator NDCX-II under construction at LBNL, an upgraded Neutralized Drift Compression experiment for research on warm dense matter and heavy ion fusion. Precise alignment is essential for NDCX-II, since the ion beam has a large energy spread associated with the rapid pulse compression such that misalignments lead to corkscrew deformation of the beam and reduced intensity at focus. The ability to align the magnetic axis of the pulsed solenoids to within 100 pm of the induction cell axis has been demonstrated.

Declining trend in the use of repeat computed tomography for trauma patients admitted to a level I trauma center for traffic-related injuries

Energy Technology Data Exchange (ETDEWEB)

Psoter, Kevin J., E-mail: kevinp2@u.washington.edu [Department of Epidemiology, University of Washington, Box 357236, Seattle, WA 98195 (United States); Roudsari, Bahman S., E-mail: roudsari@u.washington.edu [Department of Radiology, Comparative Effectiveness, Cost and Outcomes Research Center, University of Washington, 325 Ninth Avenue, Box 359960, Seattle, WA 98104 (United States); Graves, Janessa M., E-mail: janessa@u.washington.edu [Department of Pediatrics, Harborview Injury Prevention and Research Center, University of Washington, 325 Ninth Avenue, Box 359960, Seattle, WA 98104 (United States); Mack, Christopher, E-mail: cdmack@uw.edu [Harborview Injury Prevention and Research Center, University of Washington, 325 Ninth Avenue, Box 359960, Seattle, WA 98104 (United States); Jarvik, Jeffrey G., E-mail: jarvikj@u.washington.edu [Department of Radiology and Department of Neurological Surgery, Comparative Effectiveness, Cost and Outcomes Research Center, University of Washington, 325 Ninth Avenue, Box 359960, Seattle, WA 98104 (United States)

2013-06-15

Objective: To evaluate the trend in utilization of repeat (i.e. ≥2) computed tomography (CT) and to compare utilization patterns across body regions for trauma patients admitted to a level I trauma center for traffic-related injuries (TRI). Materials and Methods: We linked the Harborview Medical Center trauma registry (1996–2010) to the billing department data. We extracted the following variables: type and frequency of CTs performed, age, gender, race/ethnicity, insurance status, injury mechanism and severity, length of hospitalization, intensive care unit (ICU) admission and final disposition. TRIs were defined as motor vehicle collisions, motorcycle, bicycle and pedestrian-related injuries. Logistic regression was used to evaluate the association between utilization of different body region repeat (i.e. ≥2) CTs and year of admission, adjusting for patient and injury-related characteristics that could influence utilization patterns. Results: A total of 28,431 patients were admitted for TRIs over the study period and 9499 (33%) received repeat CTs. From 1996 to 2010, the proportion of patients receiving repeat CTs decreased by 33%. Relative to 2000 and adjusting for other covariates, patients with TRIs admitted in 2010 had significantly lower odds of undergoing repeat head (OR = 0.61; 95% CI: 0.49–0.76), pelvis (OR = 0.37; 95% CI: 0.27–0.52), cervical spine (OR = 0.23; 95% CI: 0.12–0.43), and maxillofacial CTs (OR = 0.24; 95% CI: 0.10–0.57). However, they had higher odds of receiving repeat thoracic CTs (OR = 1.86; 95% CI: 1.02–3.38). Conclusion: A significant decrease in the utilization of repeat CTs was observed in trauma patients presenting with traffic-related injuries over a 15-year period.

Few-cycle isolated attosecond pulses

International Nuclear Information System (INIS)

Sansone, G.; Benedetti, E.; Calegari, F.; Stagira, S.; Vozzi, C.; Silvestri De, S.; Nisoli, M.

2006-01-01

Complete test of publication follows. In the last few years the field of attosecond science has shown impressive and rapid progress, mainly due to the introduction of novel experimental methods for the characterization of extreme ultraviolet (XUV) pulses and attosecond electron wave packets. This development has been also triggered by significant improvements in the control of the electric field of the driving infrared pulses. Particularly interesting for the applications is the generation of isolated attosecond XUV pulses using few-cycle driving pulses. In this case significant progresses have been achieved thanks to the stabilization of the carrier-envelope phase (CEP) of amplified light pulses. In this work we demonstrate that the polarization gating (PG) method with few-cycle phase-stabilized driving pulses allows one to generate few-cycle isolated attosecond pulses tunable on a very broad spectral region. The PG method is based on temporal modulation of the ellipticity of a light pulse, which confines the XUV emission in the temporal gate where the polarization is close to linear. The time-dependent polarization of phase-stabilized sub-6-fs pulses, generated by the hollow fiber technique, has been obtained using two birefringent plates. It is possible to create a linear polarization gate, whose position is imposed by the intensity profile of the pulse whilst the emission time is linked to the CEP of the electric field. The pulses have been analyzed by using a flat-field spectrometer. Continuous XUV spectra, corresponding to the production of isolated attosecond pulses, have been generated for particular CEP values. Upon changing the rotation of the first plate it was possible to tune the XUV emission in a broad spectra range. We have then achieved a complete temporal characterization of the generated isolated attosecond pulses using frequency-resolved optical gating for complete reconstruction of attosecond bursts (FROG CRAB). The measured parabolic phase

Foundations of pulsed power technology

CERN Document Server

Lehr, Janet

2018-01-01

Pulsed power technologies could be an answer to many cutting-edge applications. The challenge is in how to develop this high-power/high-energy technology to fit current market demands of low-energy consuming applications. This book provides a comprehensive look at pulsed power technology and shows how it can be improved upon for the world of today and tomorrow. Foundations of Pulsed Power Technology focuses on the design and construction of the building blocks as well as their optimum assembly for synergetic high performance of the overall pulsed power system. Filled with numerous design examples throughout, the book offers chapter coverage on various subjects such as: Marx generators and Marx-like circuits; pulse transformers; pulse-forming lines; closing switches; opening switches; multi-gigawatt to multi-terawatt systems; energy storage in capacitor banks; electrical breakdown in gases; electrical breakdown in solids, liquids and vacuum; pulsed voltage and current measurements; electromagnetic interferen...

An 8-GW long-pulse generator based on Tesla transformer and pulse forming network.

Science.gov (United States)

Su, Jiancang; Zhang, Xibo; Li, Rui; Zhao, Liang; Sun, Xu; Wang, Limin; Zeng, Bo; Cheng, Jie; Wang, Ying; Peng, Jianchang; Song, Xiaoxin

2014-06-01

A long-pulse generator TPG700L based on a Tesla transformer and a series pulse forming network (PFN) is constructed to generate intense electron beams for the purpose of high power microwave (HPM) generation. The TPG700L mainly consists of a 12-stage PFN, a built-in Tesla transformer in a pulse forming line, a three-electrode gas switch, a transmission line with a trigger, and a load. The Tesla transformer and the compact PFN are the key technologies for the development of the TPG700L. This generator can output electrical pulses with a width as long as 200 ns at a level of 8 GW and a repetition rate of 50 Hz. When used to drive a relative backward wave oscillator for HPM generation, the electrical pulse width is about 100 ns on a voltage level of 520 kV. Factors affecting the pulse waveform of the TPG700L are also discussed. At present, the TPG700L performs well for long-pulse HPM generation in our laboratory.

An 8-GW long-pulse generator based on Tesla transformer and pulse forming network

Energy Technology Data Exchange (ETDEWEB)

Su, Jiancang; Zhang, Xibo; Li, Rui; Zhao, Liang, E-mail: zhaoliang0526@163.com; Sun, Xu; Wang, Limin; Zeng, Bo; Cheng, Jie; Wang, Ying; Peng, Jianchang; Song, Xiaoxin [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi' an, Shaanxi 710024 (China)

2014-06-15

A long-pulse generator TPG700L based on a Tesla transformer and a series pulse forming network (PFN) is constructed to generate intense electron beams for the purpose of high power microwave (HPM) generation. The TPG700L mainly consists of a 12-stage PFN, a built-in Tesla transformer in a pulse forming line, a three-electrode gas switch, a transmission line with a trigger, and a load. The Tesla transformer and the compact PFN are the key technologies for the development of the TPG700L. This generator can output electrical pulses with a width as long as 200 ns at a level of 8 GW and a repetition rate of 50 Hz. When used to drive a relative backward wave oscillator for HPM generation, the electrical pulse width is about 100 ns on a voltage level of 520 kV. Factors affecting the pulse waveform of the TPG700L are also discussed. At present, the TPG700L performs well for long-pulse HPM generation in our laboratory.

Pulse pile-up IV

International Nuclear Information System (INIS)

Wilkinson, D.H.

1991-05-01

The study of pulse pile-up is extended from the case of unipolar pulses, for which ruin theory is an excellent approximation, to the case of bipolar pulses for which ruin theory is not applicable to the effect of the back-kicks in reducing the pile-up: an appropriate solution is presented. (Author) 3 refs., 11 figs

A critical comparison of constant and pulsed flow systems exploiting gas diffusion.

Science.gov (United States)

Silva, Claudineia Rodrigues; Henriquez, Camelia; Frizzarin, Rejane Mara; Zagatto, Elias Ayres Guidetti; Cerda, Victor

2016-02-01

Considering the beneficial aspects arising from the implementation of pulsed flows in flow analysis, and the relevance of in-line gas diffusion as an analyte separation/concentration step, influence of flow pattern in flow systems with in-line gas diffusion was critically investigated. To this end, constant or pulsed flows delivered by syringe or solenoid pumps were exploited. For each flow pattern, two variants involving different interaction times of the donor with the acceptor streams were studied. In the first one, both the acceptor and donor streams were continuously flowing, whereas in the second one, the acceptor was stopped during the gas diffusion step. Four different volatile species (ammonia, ethanol, carbon dioxide and hydrogen sulfide) were selected as models. For the flow patterns and variants studied, the efficiencies of mass transport in the gas diffusion process were compared, and sensitivity, repeatability, sampling frequency and recorded peak shape were evaluated. Analysis of the results revealed that sensitivity is strongly dependent on the implemented variant, and that flow pattern is an important feature in flow systems with in-line gas diffusion. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of nonlinear pulse shaping of femtosecond pulse generation in a fiber amplifier at 500 MHz repetition rate

Science.gov (United States)

Liu, Yang; Luo, Daping; Wang, Chao; Zhu, Zhiwei; Li, Wenxue

2018-03-01

We numerically and experimentally demonstrate that a nonlinear pulse shaping technique based on pre-chirping management in a short gain fiber can be exploited to improve the quality of a compressed pulse. With prior tuning of the pulse chirp, the amplified pulse express different nonlinear propagating processes. A spectrum with s flat top and more smooth wings, showing a similariton feature, generates with the optimal initial pulse chirp, and the shortest pulses with minimal pulse pedestals are obtained. Experimental results show the ability of nonlinear pulse shaping to enhance the quality of compressed pulses, as theoretically expected.

Nanosecond bipolar pulse generators for bioelectrics.

Science.gov (United States)

Xiao, Shu; Zhou, Chunrong; Yang, Enbo; Rajulapati, Sambasiva R

2018-04-26

Biological effects caused by a nanosecond pulse, such as cell membrane permeabilization, peripheral nerve excitation and cell blebbing, can be reduced or cancelled by applying another pulse of reversed polarity. Depending on the degree of cancellation, the pulse interval of these two pulses can be as long as dozens of microseconds. The cancellation effect diminishes as the pulse duration increases. To study the cancellation effect and potentially utilize it in electrotherapy, nanosecond bipolar pulse generators must be made available. An overview of the generators is given in this paper. A pulse forming line (PFL) that is matched at one end and shorted at the other end allows a bipolar pulse to be produced, but no delay can be inserted between the phases. Another generator employs a combination of a resistor, an inductor and a capacitor to form an RLC resonant circuit so that a bipolar pulse with a decaying magnitude can be generated. A third generator is a converter, which converts an existing unipolar pulse to a bipolar pulse. This is done by inserting an inductor in a transmission line. The first phase of the bipolar pulse is provided by the unipolar pulse's rising phase. The second phase is formed during the fall time of the unipolar pulse, when the inductor, which was previously charged during the flat part of the unipolar pulse, discharges its current to the load. The fourth type of generator uses multiple MOSFET switches stacked to turn on a pre-charged, bipolar RC network. This approach is the most flexible in that it can generate multiphasic pulses that have different amplitudes, delays, and durations. However, it may not be suitable for producing short nanosecond pulses (<100 ns), whereas the PFL approach and the RLC approach with gas switches are used for this range. Thus, each generator has its own advantages and applicable range. Copyright © 2018 Elsevier B.V. All rights reserved.

Industrial Applications of Pulsed Power Technology

Science.gov (United States)

Takaki, Koichi; Katsuki, Sunao

Recent progress of the industrial applications of pulsed power is reviewed in this paper. Repetitively operated pulsed power generators with a moderate peak power have been developed for industrial applications. These generators are reliable and low maintenance. Development of the pulsed power generators helps promote industrial applications of pulsed power for such things as food processing, medical treatment, water treatment, exhaust gas treatment, ozone generation, engine ignition, ion implantation and others. Here, industrial applications of pulsed power are classified by application for biological effects, for pulsed streamer discharges in gases, for pulsed discharges in liquid or liquid-mixture, and for bright radiation sources.

Linear induction accelerators made from pulse-line cavities with external pulse injection

International Nuclear Information System (INIS)

Smith, I.

1979-01-01

Two types of linear induction accelerator have been reported previously. In one, unidirectional voltage pulses are generated outside the accelerator and injected into the accelerator cavity modules, which contain ferromagnetic material to reduce energy losses in the form of currents induced, in parallel with the beam, in the cavity structure. In the other type, the accelerator cavity modules are themselves pulse-forming lines with energy storage and switches; parallel current losses are made zero by the use of circuits that generate bidirectional acceleration waveforms with a zero voltage-time integral. In a third type of design described here, the cavities are externally driven, and 100% efficient coupling of energy to the beam is obtained by designing the external pulse generators to produce bidirectional voltage waveforms with zero voltage-time integral. A design for such a pulse generator is described that is itself one hundred percent efficient and which is well suited to existing pulse power techniques. Two accelerator cavity designs are described that can couple the pulse from such a generator to the beam; one of these designs provides voltage doubling. Comparison is made between the accelerating gradients that can be obtained with this and the preceding types of induction accelerator

The Pentapeptide Repeat Proteins

OpenAIRE

Vetting, Matthew W.; Hegde, Subray S.; Fajardo, J. Eduardo; Fiser, Andras; Roderick, Steven L.; Takiff, Howard E.; Blanchard, John S.

2006-01-01

The Pentapeptide Repeat Protein (PRP) family has over 500 members in the prokaryotic and eukaryotic kingdoms. These proteins are composed of, or contain domains composed of, tandemly repeated amino acid sequences with a consensus sequence of [S,T,A,V][D,N][L,F]-[S,T,R][G]. The biochemical function of the vast majority of PRP family members is unknown. The three-dimensional structure of the first member of the PRP family was determined for the fluoroquinolone resistance protein (MfpA) from Myc...

Optimal filter bandwidth for pulse oximetry

Science.gov (United States)

Stuban, Norbert; Niwayama, Masatsugu

2012-10-01

Pulse oximeters contain one or more signal filtering stages between the photodiode and microcontroller. These filters are responsible for removing the noise while retaining the useful frequency components of the signal, thus improving the signal-to-noise ratio. The corner frequencies of these filters affect not only the noise level, but also the shape of the pulse signal. Narrow filter bandwidth effectively suppresses the noise; however, at the same time, it distorts the useful signal components by decreasing the harmonic content. In this paper, we investigated the influence of the filter bandwidth on the accuracy of pulse oximeters. We used a pulse oximeter tester device to produce stable, repetitive pulse waves with digitally adjustable R ratio and heart rate. We built a pulse oximeter and attached it to the tester device. The pulse oximeter digitized the current of its photodiode directly, without any analog signal conditioning. We varied the corner frequency of the low-pass filter in the pulse oximeter in the range of 0.66-15 Hz by software. For the tester device, the R ratio was set to R = 1.00, and the R ratio deviation measured by the pulse oximeter was monitored as a function of the corner frequency of the low-pass filter. The results revealed that lowering the corner frequency of the low-pass filter did not decrease the accuracy of the oxygen level measurements. The lowest possible value of the corner frequency of the low-pass filter is the fundamental frequency of the pulse signal. We concluded that the harmonics of the pulse signal do not contribute to the accuracy of pulse oximetry. The results achieved by the pulse oximeter tester were verified by human experiments, performed on five healthy subjects. The results of the human measurements confirmed that filtering out the harmonics of the pulse signal does not degrade the accuracy of pulse oximetry.

SLAC pulsed X-ray facility

Science.gov (United States)

Ipe, N. E.; McCall, R. C.; Baker, E. D.

1986-05-01

The Stanford Linear Accelerator Center (SLAC) operates a high energy (up to 33 GeV) linear accelerator delivering pulses up to a few microseconds wide. The pulsed nature of the electron beam creates problems in the detection and measurement of radiation both from the accelerator beam and the klystrons that provide the RF power for the accelerator. Hence, a pulsed X-ray facility has been built at SLAC mainly for the purpose of testing the response of different radiation detection instruments to pulsed radiation fields. The X-ray tube consists of an electron gun with a control grid. This provides a stream of pulsed electrons that can be accelerated towards a confined target-window. The window is made up of aluminum 0.051 cm (20 mils) thick, plated on the vacuum side with a layer of gold 0.0006 cm (1/4 mil) thick. The frequency of electron pulses can be varied by an internal pulser from 60 to 360 pulses per second with pulse widths of 360 ns to 5 ms. The pulse amplitude can be varied over a wide range of currents. An external pulser can be used to obtain other frequencies or special pulse shapes. The voltage across the gun can be varied from 0 to 100 kV. The major part of the X-ray tube is enclosed in a large walk-in-cabinet made of 1.9 cm (3/4 in) plywood and lined with 0.32 cm (1/8 in) lead to make a very versatile facility.

SLAC pulsed x-ray facility

International Nuclear Information System (INIS)

Ipe, N.E.; McCall, R.C.; Baker, E.D.

1986-05-01

The Stanford Linear Accelerator Center (SLAC) operates a high energy (up to 33 GeV) linear accelerator delivering pulses up to a few microseconds wide. The pulsed nature of the electron beam creates problems in the detection and measurement of radiation both from the accelerator beam and the klystrons that provide the rf power for the accelerator. Hence, a pulsed x-ray facility has been built at SLAC mainly for the purpose of testing the response of different radiation detection instruments to pulsed radiation fields. The x-ray tube consists of an electron gun with a control grid. This provides a stream of pulsed electrons that can be accelerated towards a confined target-window. The window is made up of aluminium 0.051 cm (20 mils) thick, plated on the vacuum side with a layer of gold 0.0006 cm (1/4 mil) thick. The frequency of electron pulses can be varied by an internal pulser from 60 to 360 pulses per second with pulse widths of 360 ns to 5 μs. The pulse amplitude can be varied over a wide range of currents. An external pulser can be used to obtain other frequencies or special pulse shapes. The voltage across the gun can be varied from 0 to 100 kV. The major part of the x-ray tube is enclosed in a large walk-in-cabinet made of 1.9 cm (3/4 in) plywood and lined with 0.32 cm (1/8 in) lead to make a very versatile facility. 3 refs., 5 figs

Effects of laser wavelengths and pulse energy ratio on the emission enhancement in dual pulse LIBS

International Nuclear Information System (INIS)

Ahmed, Rizwan; Iqbal, Javed; Baig, M Aslam

2015-01-01

We present new studies on the effects of laser wavelengths, pulse energy ratio and interpulse delay between two laser pulses in the collinear dual pulse configuration of laser-induced breakdown spectroscopy (LIBS) on an iron sample in air using the fundamental (1064 nm) and the second harmonics (532 nm) of Nd:YAG lasers. In the dual pulse LIBS, an optimum value of interpulse delay with an appropriate combination of laser wavelengths, and laser pulse energy ratio, yields a 30 times signal intensity enhancement in the neutral iron lines as compared with single pulse LIBS. A comparison in the spatial variations of electron temperature along the axis of the plume expansion in single and double pulse LIBS has also been studied. (letter)

Thermal neutron measurements on electrolytic cells with deuterated palladium cathodes subjected to a pulsed current

International Nuclear Information System (INIS)

Granada, J.R.; Mayer, R.E.; Guido, G.; Florido, P.C.; Larreteguy, A.; Gillette, V.H.; Patino, N.E.; Converti, J.; Gomez, S.E.

1990-01-01

The present work describes the design of a high efficiency thermal neutron detection system and the measurements performed with it on electrolytic cells containing LiH dissolved in D 2 O with palladium cathodes. A procedure involving the use of a non-stationary (pulsed) current through the cell caused a correlated neutron production to be observed in a repeatable manner. These patterns are strongly dependent on the previous charging history of the cathodes. The technique employed seems to be very useful as a research tool for a systematic study of the different variables governing the phenomenon. (author)

Pulse-width discriminators

International Nuclear Information System (INIS)

Budyashov, Yu.G.; Grebenyuk, V.M.; Zinov, V.G.

1978-01-01

A pulse duration discriminator is described which is intended for processing signals from multilayer scintillators. The basic elements of the scintillator are: an input gate, a current generator, an integrating capacitor, a Schmidt trigger and an anticoincidence circuit. The basic circuit of the discriminator and its time diagrams explaining its operating are given. The discriminator is based on microcircuits. Pulse duration discrimination threshold changes continuously from 20 to 100 ns, while its amplitude threshold changes within 20 to 100 mV. The temperature instability of discrimination thresholds (both in pulse width and in amplitude) is better than 0.1 per cent/deg C

A compact high-voltage pulse generator based on pulse transformer with closed magnetic core.

Science.gov (United States)

Zhang, Yu; Liu, Jinliang; Cheng, Xinbing; Bai, Guoqiang; Zhang, Hongbo; Feng, Jiahuai; Liang, Bo

2010-03-01

A compact high-voltage nanosecond pulse generator, based on a pulse transformer with a closed magnetic core, is presented in this paper. The pulse generator consists of a miniaturized pulse transformer, a curled parallel strip pulse forming line (PFL), a spark gap, and a matched load. The innovative design is characterized by the compact structure of the transformer and the curled strip PFL. A new structure of transformer windings was designed to keep good insulation and decrease distributed capacitance between turns of windings. A three-copper-strip structure was adopted to avoid asymmetric coupling of the curled strip PFL. When the 31 microF primary capacitor is charged to 2 kV, the pulse transformer can charge the PFL to 165 kV, and the 3.5 ohm matched load can deliver a high-voltage pulse with a duration of 9 ns, amplitude of 84 kV, and rise time of 5.1 ns. When the load is changed to 50 ohms, the output peak voltage of the generator can be 165 kV, the full width at half maximum is 68 ns, and the rise time is 6.5 ns.

Enhancement of beam pulse controllability for a single-pulse formation system of a cyclotron

International Nuclear Information System (INIS)

Kurashima, Satoshi; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Okumura, Susumu; Taguchi, Mitsumasa; Fukuda, Mitsuhiro

2015-01-01

The single-pulse formation technique using a beam chopping system consisting of two types of high-voltage beam kickers was improved to enhance the quality and intensity of the single-pulse beam with a pulse interval over 1 μs at the Japan Atomic Energy Agency cyclotron facility. A contamination rate of neighboring beam bunches in the single-pulse beam was reduced to less than 0.1%. Long-term purification of the single pulse beam was guaranteed by the well-controlled magnetic field stabilization system for the cyclotron magnet. Reduction of the multi-turn extraction number for suppressing the neighboring beam bunch contamination was achieved by restriction of a beam phase width and precise optimization of a particle acceleration phase. In addition, the single-pulse beam intensity was increased by a factor of two or more by a combination of two types of beam bunchers using sinusoidal and saw-tooth voltage waveforms. Provision of the high quality intense single-pulse beam contributed to improve the accuracy of experiments for investigation of scintillation light time-profile and for neutron energy measurement by a time-of-flight method

Hyper dispersion pulse compressor for chirped pulse amplification systems

Science.gov (United States)

Barty, Christopher P. J.

2011-11-29

A grating pulse compressor configuration is introduced for increasing the optical dispersion for a given footprint and to make practical the application for chirped pulse amplification (CPA) to quasi-narrow bandwidth materials, such as Nd:YAG. The grating configurations often use cascaded pairs of gratings to increase angular dispersion an order of magnitude or more. Increased angular dispersion allows for decreased grating separation and a smaller compressor footprint.

Pulse duration discriminator

International Nuclear Information System (INIS)

Kosakovskij, L.F.

1980-01-01

Basic circuits of a discriminator for discrimination of pulses with the duration greater than the preset one, and of a multifunctional discriminator allowing to discriminate pulses with the duration greater (tsub(p)>tsub(s)) and lesser (tsub(p) tsub(s) and with the duration tsub(p) [ru

Respiratory variation in peak aortic velocity accurately predicts fluid responsiveness in children undergoing neurosurgery under general anesthesia.

Science.gov (United States)

Morparia, Kavita G; Reddy, Srijaya K; Olivieri, Laura J; Spaeder, Michael C; Schuette, Jennifer J

2018-04-01

The determination of fluid responsiveness in the critically ill child is of vital importance, more so as fluid overload becomes increasingly associated with worse outcomes. Dynamic markers of volume responsiveness have shown some promise in the pediatric population, but more research is needed before they can be adopted for widespread use. Our aim was to investigate effectiveness of respiratory variation in peak aortic velocity and pulse pressure variation to predict fluid responsiveness, and determine their optimal cutoff values. We performed a prospective, observational study at a single tertiary care pediatric center. Twenty-one children with normal cardiorespiratory status undergoing general anesthesia for neurosurgery were enrolled. Respiratory variation in peak aortic velocity (ΔVpeak ao) was measured both before and after volume expansion using a bedside ultrasound device. Pulse pressure variation (PPV) value was obtained from the bedside monitor. All patients received a 10 ml/kg fluid bolus as volume expansion, and were qualified as responders if stroke volume increased >15% as a result. Utility of ΔVpeak ao and PPV and to predict responsiveness to volume expansion was investigated. A baseline ΔVpeak ao value of greater than or equal to 12.3% best predicted a positive response to volume expansion, with a sensitivity of 77%, specificity of 89% and area under receiver operating characteristic curve of 0.90. PPV failed to demonstrate utility in this patient population. Respiratory variation in peak aortic velocity is a promising marker for optimization of perioperative fluid therapy in the pediatric population and can be accurately measured using bedside ultrasonography. More research is needed to evaluate the lack of effectiveness of pulse pressure variation for this purpose.

Effect of rising time of rectangular pulse on inactivation of staphylococcus aureus by pulsed electric field

Science.gov (United States)

Zhang, Ruobing; Liang, Dapeng; Zheng, Nanchen; Xiao, Jianfu; Mo, Mengbin; Li, Jing

2013-03-01

Pulsed electric field (PEF) is a novel non-thermal food processing technology that involves the electric discharge of high voltage short pulses through the food product. In PEF study, rectangular pulses are most commonly used for inactivating microorganisms. However, little information is available on the inactivation effect of rising time of rectangular pulse. In this paper, inactivation effects, electric field strength, treatment time and conductivity on staphylococcus aureus inactivation were investigated when the pulse rising time is reduced from 2.5 μs to 200 ns. Experimental results showed that inactivation effect of PEF increased with electric field strength, solution conductivity and treatment time. Rising time of the rectangular pulse had a significant effect on the inactivation of staphylococcus aureus. Rectangular pulses with a rising time of 200 ns had a better inactivation effect than that with 2 μs. In addition, temperature increase of the solution treated by pulses with 200 ns rising time was lower than that with 2 μs. In order to obtain a given inactivation effect, treatment time required for the rectangular pulse with 200 ns rise time was shorter than that with 2 μs.

Effect of rising time of rectangular pulse on inactivation of staphylococcus aureus by pulsed electric field

International Nuclear Information System (INIS)

Zhang, Ruobing; Liang, Dapeng; Xiao, Jianfu; Mo, Mengbin; Li, Jing; Zheng, Nanchen

2013-01-01

Pulsed electric field (PEF) is a novel non-thermal food processing technology that involves the electric discharge of high voltage short pulses through the food product. In PEF study, rectangular pulses are most commonly used for inactivating microorganisms. However, little information is available on the inactivation effect of rising time of rectangular pulse. In this paper, inactivation effects, electric field strength, treatment time and conductivity on staphylococcus aureus inactivation were investigated when the pulse rising time is reduced from 2.5 μs to 200 ns. Experimental results showed that inactivation effect of PEF increased with electric field strength, solution conductivity and treatment time. Rising time of the rectangular pulse had a significant effect on the inactivation of staphylococcus aureus. Rectangular pulses with a rising time of 200 ns had a better inactivation effect than that with 2 μs. In addition, temperature increase of the solution treated by pulses with 200 ns rising time was lower than that with 2 μs. In order to obtain a given inactivation effect, treatment time required for the rectangular pulse with 200 ns rise time was shorter than that with 2 μs.

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

International Nuclear Information System (INIS)

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

2010-01-01

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

Pile-up and defective pulse rejection by pulse shape discrimination in surface barrier detectors

International Nuclear Information System (INIS)

Sjoeland, K.A.; Kristiansson, P.

1994-01-01

A technique to reject pile-up pulses and defective tail pulses from surface barrier detectors by the use of pulse shape discrimination is demonstrated. The electronic implementation of the pulse shape discrimination is based upon the zero crossing technique and for data reduction multiparameter techniques are used. The characteristic τ value for pile-up rejection is shown to be less than 56 ns. Its effect on detection limits from tail reduction in Particle Elastic Scattering Analysis (PESA) and pile-up peak suppression is discussed. ((orig.))

CAMAC differential pulse discriminator-counter

International Nuclear Information System (INIS)

Tselikov, N.V.

1987-01-01

Differential pulse discriminator-counter for Moessbauer spectrometer is described. Input pulse setting into the channel is performed according to the following algorithm: the pulse is transmitted to the channel depending on the fact whether the preceding pulse has got to the discrimination window or not. The circuit does not contain delay lines, taking into account the delay of a signal from the upper level discriminator in relation to the lower level discriminator signal, which is connected with input pulse rise finite time, which in turn allows one to reduce the discriminator dead time up to the operation time of threshold circuits. The pulse counting rate is 150 MHz, input signal amplitude is ±3 V, dead time is 6 ns, delay time from input to output is 14 ns. The unit is made in CAMAC system

Measuring Aseismic Slip through Characteristically Repeating Earthquakes at the Mendocino Triple Junction, Northern California

Science.gov (United States)

Materna, K.; Taira, T.; Burgmann, R.

2016-12-01

The Mendocino Triple Junction (MTJ), at the transition point between the San Andreas fault system, the Mendocino Transform Fault, and the Cascadia Subduction Zone, undergoes rapid tectonic deformation and produces more large (M>6.0) earthquakes than any region in California. Most of the active faults of the triple junction are located offshore, making it difficult to characterize both seismic slip and aseismic creep. In this work, we study aseismic creep rates near the MTJ using characteristically repeating earthquakes (CREs) as indicators of creep rate. CREs are generally interpreted as repeated failures of the same seismic patch within an otherwise creeping fault zone; as a consequence, the magnitude and recurrence time of the CREs can be used to determine a fault's creep rate through empirically calibrated scaling relations. Using seismic data from 2010-2016, we identify CREs as recorded by an array of eight 100-Hz PBO borehole seismometers deployed in the Cape Mendocino area. For each event pair with epicenters less than 30 km apart, we compute the cross-spectral coherence of 20 seconds of data starting one second before the P-wave arrival. We then select pairs with high coherence in an appropriate frequency band, which is determined uniquely for each event pair based on event magnitude, station distance, and signal-to-noise ratio. The most similar events (with median coherence above 0.95 at two or more stations) are selected as CREs and then grouped into CRE families, and each family is used to infer a local creep rate. On the Mendocino Transform Fault, we find relatively high creep rates of >5 cm/year that increase closer to the Gorda Ridge. Closer to shore and to the MTJ itself, we find many families of repeaters on and off the transform fault with highly variable creep rates, indicative of the complex deformation that takes place there.

In situ detection of tandem DNA repeat length

Energy Technology Data Exchange (ETDEWEB)

Yaar, R.; Szafranski, P.; Cantor, C.R.; Smith, C.L. [Boston Univ., MA (United States)

1996-11-01

A simple method for scoring short tandem DNA repeats is presented. An oligonucleotide target, containing tandem repeats embedded in a unique sequence, was hybridized to a set of complementary probes, containing tandem repeats of known lengths. Single-stranded loop structures formed on duplexes containing a mismatched (different) number of tandem repeats. No loop structure formed on duplexes containing a matched (identical) number of tandem repeats. The matched and mismatched loop structures were enzymatically distinguished and differentially labeled by treatment with S1 nuclease and the Klenow fragment of DNA polymerase. 7 refs., 4 figs.

Automated genotyping of dinucleotide repeat markers

Energy Technology Data Exchange (ETDEWEB)

Perlin, M.W.; Hoffman, E.P. [Carnegie Mellon Univ., Pittsburgh, PA (United States)]|[Univ. of Pittsburgh, PA (United States)

1994-09-01

The dinucleotide repeats (i.e., microsatellites) such as CA-repeats are a highly polymorphic, highly abundant class of PCR-amplifiable markers that have greatly streamlined genetic mapping experimentation. It is expected that over 30,000 such markers (including tri- and tetranucleotide repeats) will be characterized for routine use in the next few years. Since only size determination, and not sequencing, is required to determine alleles, in principle, dinucleotide repeat genotyping is easily performed on electrophoretic gels, and can be automated using DNA sequencers. Unfortunately, PCR stuttering with these markers generates not one band for each allele, but a pattern of bands. Since closely spaced alleles must be disambiguated by human scoring, this poses a key obstacle to full automation. We have developed methods that overcome this obstacle. Our model is that the observed data is generated by arithmetic superposition (i.e., convolution) of multiple allele patterns. By quantitatively measuring the size of each component band, and exploiting the unique stutter pattern associated with each marker, closely spaced alleles can be deconvolved; this unambiguously reconstructs the {open_quotes}true{close_quotes} allele bands, with stutter artifact removed. We used this approach in a system for automated diagnosis of (X-linked) Duchenne muscular dystrophy; four multiplexed CA-repeats within the dystrophin gene were assayed on a DNA sequencer. Our method accurately detected small variations in gel migration that shifted the allele size estimate. In 167 nonmutated alleles, 89% (149/167) showed no size variation, 9% (15/167) showed 1 bp variation, and 2% (3/167) showed 2 bp variation. We are currently developing a library of dinucleotide repeat patterns; together with our deconvolution methods, this library will enable fully automated genotyping of dinucleotide repeats from sizing data.

Sequentially pulsed traveling wave accelerator

Science.gov (United States)

Caporaso, George J [Livermore, CA; Nelson, Scott D [Patterson, CA; Poole, Brian R [Tracy, CA

2009-08-18

A sequentially pulsed traveling wave compact accelerator having two or more pulse forming lines each with a switch for producing a short acceleration pulse along a short length of a beam tube, and a trigger mechanism for sequentially triggering the switches so that a traveling axial electric field is produced along the beam tube in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to the particle beam.

Assessment and mitigation of electromagnetic pulse (EMP) impacts at short-pulse laser facilities

International Nuclear Information System (INIS)

Brown, C G Jr; Bond, E; Clancy, T; Dangi, S; Eder, D C; Ferguson, W; Kimbrough, J; Throop, A

2010-01-01

The National Ignition Facility (NIF) will be impacted by electromagnetic pulse (EMP) during normal long-pulse operation, but the largest impacts are expected during short-pulse operation utilizing the Advanced Radiographic Capability (ARC). Without mitigation these impacts could range from data corruption to hardware damage. We describe our EMP measurement systems on Titan and NIF and present some preliminary results and thoughts on mitigation.

Dose rate effect on micronuclei induction in human blood lymphocytes exposed to single pulse and multiple pulses of electrons.

Science.gov (United States)

Acharya, Santhosh; Bhat, N N; Joseph, Praveen; Sanjeev, Ganesh; Sreedevi, B; Narayana, Y

2011-05-01

The effects of single pulses and multiple pulses of 7 MV electrons on micronuclei (MN) induction in cytokinesis-blocked human peripheral blood lymphocytes (PBLs) were investigated over a wide range of dose rates per pulse (instantaneous dose rate). PBLs were exposed to graded doses of 2, 3, 4, 6, and 8 Gy of single electron pulses of varying pulse widths at different dose rates per pulse, ranging from 1 × 10(6) Gy s(-1) to 3.2 × 10(8) Gy s(-1). Different dose rates per pulse were achieved by changing the dose per electron pulse by adjusting the beam current and pulse width. MN yields per unit absorbed dose after irradiation with single electron pulses were compared with those of multiple pulses of electrons. A significant decrease in the MN yield with increasing dose rates per pulse was observed, when dose was delivered by a single electron pulse. However, no reduction in the MN yield was observed when dose was delivered by multiple pulses of electrons. The decrease in the yield at high dose rates per pulse suggests possible radical recombination, which leads to decreased biological damage. Cellular response to the presence of very large numbers of chromosomal breaks may also alter the damage.

Rapid thermal pulse annealing

International Nuclear Information System (INIS)

Miller, M.G.; Koehn, B.W.; Chaplin, R.L.

1976-01-01

Characteristics of recovery processes have been investigated for cases of heating a sample to successively higher temperatures by means of isochronal annealing or by using a rapid pulse annealing. A recovery spectra shows the same features independent of which annealing procedure is used. In order to determine which technique provides the best resolution, a study was made of how two independent first-order processes are separated for different heating rates and time increments of the annealing pulses. It is shown that the pulse anneal method offers definite advantages over isochronal annealing when annealing for short time increments. Experimental data by means of the pulse anneal techniques are given for the various substages of stage I of aluminium. (author)

An in vivo investigation of photoplethysmographic signals and preliminary pulse oximetry estimation from the bowel using a new fiberoptic sensor.

Science.gov (United States)

Hickey, Michelle; Samuels, Neal; Randive, Nilesh; Langford, Richard M; Kyriacou, Panayiotis A

2011-05-01

The continuous monitoring of splanchnic organ oxygen saturation could make the early detection of inadequate tissue oxygenation feasible, reducing the risk of hypoperfusion, severe ischemia, multiple organ failure, and, ultimately, death. Current methods for assessing splanchnic perfusion have not been widely accepted for use in the clinical care environment. In an attempt to overcome the limitations of the current techniques, a new fiberoptic photoplethysmographic (PPG)/pulse oximetry sensor was developed as a means of assessing splanchnic organ perfusion during surgery in humans. A new fiberoptic splanchnic pulse oximeter and an optically identical fiberoptic finger pulse oximeter have been developed. Simultaneous PPG signals and preliminary estimates of arterial oxygen saturation from the bowel (small and large) and finger were obtained in 17 patients (3 men and 14 women) undergoing open laparotomy. Good quality PPG signals were obtained from the small and large bowel and from the finger in all patients (lower 95% confidence limit for the proportion was 0.64). Comparisons of blood oxygen saturation values acquired when using the splanchnic and the finger fiberoptic sensors and a commercial finger pulse oximeter indicated that there was no statistically significant difference between them (all P>0.454). A Bland and Altman plot of the difference between blood oxygen saturation values from the bowel fiberoptic pulse oximeter and the fiberoptic finger pulse oximeter against their mean showed that the limits of agreement between the 2 pulse oximeters were -3.8% and 4.2% for small bowel measurements, and -3.4% and 4.3% for large bowel measurements. The 95% prediction interval for the difference between the 2 devices was between -4.2% and 4.7%. This study demonstrated that good quality PPG signals can be obtained from the bowel using a new fiberoptic sensor. Further evaluation is required to determine whether fiberoptic pulse oximetry of the bowel may provide a

Linear transformer driver for pulse generation

Science.gov (United States)

Kim, Alexander A; Mazarakis, Michael G; Sinebryukhov, Vadim A; Volkov, Sergey N; Kondratiev, Sergey S; Alexeenko, Vitaly M; Bayol, Frederic; Demol, Gauthier; Stygar, William A

2015-04-07

A linear transformer driver includes at least one ferrite ring positioned to accept a load. The linear transformer driver also includes a first power delivery module that includes a first charge storage devices and a first switch. The first power delivery module sends a first energy in the form of a first pulse to the load. The linear transformer driver also includes a second power delivery module including a second charge storage device and a second switch. The second power delivery module sends a second energy in the form of a second pulse to the load. The second pulse has a frequency that is approximately three times the frequency of the first pulse. The at least one ferrite ring is positioned to force the first pulse and the second pulse to the load by temporarily isolating the first pulse and the second pulse from an electrical ground.

Ultra-intense laser pulse propagation in plasmas: from classic hole-boring to incomplete hole-boring with relativistic transparency

International Nuclear Information System (INIS)

Weng, S M; Murakami, M; Mulser, P; Sheng, Z M

2012-01-01

Relativistic laser pulse propagation into homogeneous plasmas has been investigated as a function of plasma density. At first, the propagation features are compared systematically between relativistic transparency (RT) and hole-boring (HB). Paramountly, a considerably broad intermediate regime, namely the incomplete HB regime, has been found between the RT regime and the HB regime for an extremely intense circularly polarized (CP) pulse. In this regime HB proceeds in collaboration with RT, resulting in a much faster propagation speed and a higher cut-off energy of fast ions than in the classic HB regime. Similarly to the classic HB regime, formulae are presented to model the laser propagation and the ion acceleration according to the modified momentum flux balance in this incomplete HB regime. The simulations give the density boundary between this incomplete HB regime and the classic HB regime for CP pulses, which is crucial for estimating the maximum mean ion energy and the maximum conversion efficiency that can be achieved by the classic HB acceleration at a given laser intensity. For linear polarization (LP) the propagation mechanism apparently undergoes a transition in time between these two regimes. A detailed comparison between LP and circular polarization is made for these phenomena. (paper)

One electron reduction of 1,2 dihydroxy 9,10 anthraquinone and its transition metal complexes in aqueous-isopropanol-acetone mixed solvent: a steady state-state and pulse radiolysis study

International Nuclear Information System (INIS)

Das, Saurabh; Mandal, Parikshit C.; Rath, Madhab C.; Mukherjee, Tulsi

1998-01-01

One electron reduction of 1,2 dihydroxy 9,10 anthraquinone and its Cu(II) and Ni(II) and Fe(III) complexes have been studied in aqueous-isopropanol-acetone solvent. Results indicate that the reducing ketyl radical generated reacts with the ligand forming semiquinones which undergoes a disproportionation reaction. Formation and decay rates of semiquinones was calculated using pulse radiolysis. (author)

Harmonic generation with a dual frequency pulse.

Science.gov (United States)

Keravnou, Christina P; Averkiou, Michalakis A

2014-05-01

Nonlinear imaging was implemented in commercial ultrasound systems over the last 15 years offering major advantages in many clinical applications. In this work, pulsing schemes coupled with a dual frequency pulse are presented. The pulsing schemes considered were pulse inversion, power modulation, and power modulated pulse inversion. The pulse contains a fundamental frequency f and a specified amount of its second harmonic 2f. The advantages and limitations of this method were evaluated with both acoustic measurements of harmonic generation and theoretical simulations based on the KZK equation. The use of two frequencies in a pulse results in the generation of the sum and difference frequency components in addition to the other harmonic components. While with single frequency pulses, only power modulation and power modulated pulse inversion contained odd harmonic components, with the dual frequency pulse, pulse inversion now also contains odd harmonic components.

Motion of the dayside polar cap boundary during substorm cycles: II. Generation of poleward-moving events and polar cap patches by pulses in the magnetopause reconnection rate

Directory of Open Access Journals (Sweden)

M. Lockwood

2005-12-01

Full Text Available Using data from the EISCAT (European Incoherent Scatter VHF and CUTLASS (Co-operative UK Twin-Located Auroral Sounding System HF radars, we study the formation of ionospheric polar cap patches and their relationship to the magnetopause reconnection pulses identified in the companion paper by Lockwood et al. (2005. It is shown that the poleward-moving, high-concentration plasma patches observed in the ionosphere by EISCAT on 23 November 1999, as reported by Davies et al. (2002, were often associated with corresponding reconnection rate pulses. However, not all such pulses generated a patch and only within a limited MLT range (11:00-12:00 MLT did a patch result from a reconnection pulse. Three proposed mechanisms for the production of patches, and of the concentration minima that separate them, are analysed and evaluated: (1 concentration enhancement within the patches by cusp/cleft precipitation; (2 plasma depletion in the minima between the patches by fast plasma flows; and (3 intermittent injection of photoionisation-enhanced plasma into the polar cap. We devise a test to distinguish between the effects of these mechanisms. Some of the events repeat too frequently to apply the test. Others have sufficiently long repeat periods and mechanism (3 is shown to be the only explanation of three of the longer-lived patches seen on this day. However, effect (2 also appears to contribute to some events. We conclude that plasma concentration gradients on the edges of the larger patches arise mainly from local time variations in the subauroral plasma, via the mechanism proposed by Lockwood et al. (2000.

New neutron imaging using pulsed sources. Characteristics of a pulsed neutron source and principle of pulsed neutron imaging

International Nuclear Information System (INIS)

Kiyanagi, Yoshiaki

2012-01-01

Neutron beam is one of important tools to obtain the transmission image of an object. Until now, steady state neutron sources such as reactors are mainly used for this imaging purpose. Recently, it has been demonstrated that pulsed neutron imaging based on accelerator neutron sources can provide a real-space distribution of physical information of materials such as crystallographic structure, element, temperature, hydrogen bound state, magnetic field and so on, by analyzing wavelength dependent transmission spectrum, which information cannot be observed or difficult to obtain with a traditional imaging method using steady state neutrons. Here, characteristics of the pulsed neutron source and principle of the pulsed neutron imaging are explained as a basic concept of the new method. (author)

Development of ultra-short high voltage pulse technology using magnetic pulse compression

Energy Technology Data Exchange (ETDEWEB)

Cha, Byung Heon; Kim, S. G.; Nam, S. M.; Lee, B. C.; Lee, S. M.; Jeong, Y. U.; Cho, S. O.; Jin, J. T.; Choi, H. L

1998-01-01

The control circuit for high voltage switches, the saturable inductor for magnetic assist, and the magnetic pulse compression circuit were designed, constructed, and tested. The core materials of saturable inductors in magnetic pulse compression circuit were amorphous metal and ferrite and total compression stages were 3. By the test, in high repetition rate, high pulse compression were certified. As a result of this test, it became possible to increase life-time of thyratrons and to replace thyratrons by solid-state semiconductor switches. (author). 16 refs., 16 tabs.

Development of ultra-short high voltage pulse technology using magnetic pulse compression

International Nuclear Information System (INIS)

Cha, Byung Heon; Kim, S. G.; Nam, S. M.; Lee, B. C.; Lee, S. M.; Jeong, Y. U.; Cho, S. O.; Jin, J. T.; Choi, H. L.

1998-01-01

The control circuit for high voltage switches, the saturable inductor for magnetic assist, and the magnetic pulse compression circuit were designed, constructed, and tested. The core materials of saturable inductors in magnetic pulse compression circuit were amorphous metal and ferrite and total compression stages were 3. By the test, in high repetition rate, high pulse compression were certified. As a result of this test, it became possible to increase life-time of thyratrons and to replace thyratrons by solid-state semiconductor switches. (author). 16 refs., 16 tabs

<3> OMEGA pulse-forming network

CERN Multimedia

1974-01-01

Adjustement of the 3 W pulse-forming network of the SPS beam dumping system. When charged at 60 kV, this PFN gives 10 kA, 25 ms current pulses, with oscillations, superimposed on the pulse flat top, of an amplitude of +/- 1 Ka.

The effect of music on anxiety and pain in patients undergoing cholecystectomy

Directory of Open Access Journals (Sweden)

Zamanzadeh V

2015-02-01

Full Text Available Background and Objective: Today, the control or reduction of pain and anxiety is considered to be of great importance. Thus, the use of complementary medicine therapies has gained much attention. The present study was performed with the aim to investigate the effect of music on anxiety and pain in patients undergoing cholecystectomy. Materials and Method: This single-blind randomized clinical trial was performed on 60 patients undergoing cholecystectomy in Sina Hospital of Tabriz, Iran, in 2013. Subjects were selected through simple random sampling method and divided into intervention (n = 30 and control groups (n = 30 using a random number table. For the intervention group, 8 and 16 hours after surgery, the music was played for 15-30 minutes. For the control group, routine care was performed. Data collection tools included demographic information form and a visual analogue scales (VAS for anxiety and pain. Data analysis was performed using SPSS software version 13, and chi-square, Students’ independent t-test, and repeated measures ANOVA. Results: Comparison of changes in anxiety and pain in the two groups showed a significant decrease in anxiety 8 hours (6/27 ± 3.23 and 16 hours (5.33 ± 3.03 after surgery (P = 0.001. Moreover, the reduction in pain 8 hours (7.51 ± 1.83 and 16 hours (6.61 ± 1.86 after surgery was greater in the intervention group than the control group (P = 0.001. Conclusion: The results illustrated the positive impact of music on anxiety and pain reduction 8 and 16 hours after cholecystectomy. Therefore, this method can be used as an inexpensive and non-invasive nursing care technique.

Software emulator of nuclear pulse generation with different pulse shapes and pile-up

Energy Technology Data Exchange (ETDEWEB)

Pechousek, Jiri, E-mail: jiri.pechousek@upol.cz [Department of Experimental Physics, Faculty of Science, Palacky University, 17. listopadu 1192/12, 771 46 Olomouc (Czech Republic); Konecny, Daniel [Department of Optics, Faculty of Science, Palacky University, 17. listopadu 1192/12, 77 146 Olomouc (Czech Republic); Novak, Petr; Kouril, Lukas; Kohout, Pavel [Department of Experimental Physics, Faculty of Science, Palacky University, 17. listopadu 1192/12, 771 46 Olomouc (Czech Republic); Celiktas, Cuneyt [Department of Physics, Faculty of Science, Ege University, Bornova, Izmir (Turkey); Vujtek, Milan [Department of Experimental Physics, Faculty of Science, Palacky University, 17. listopadu 1192/12, 771 46 Olomouc (Czech Republic)

2016-08-21

The optimal detection of output signals from nuclear counting devices represents one of the key physical factors that govern accuracy and experimental reproducibility. In this context, the fine calibration of the detector under diverse experimental scenarios, although time costly, is necessary. However this process can be rendered easier with the use of systems that work in lieu of emulators. In this report we describe an innovative programmable pulse generator device capable to emulate the scintillation detector signals, in a way to mimic the detector performances under a variety of experimental conditions. The emulator generates a defined number of pulses, with a given shape and amplitude in the form of a sampled detector signal. The emulator output is then used off-line by a spectrometric system in order to set up its optimal performance. Three types of pulse shapes are produced by our device, with the possibility to add noise and pulse pile-up effects into the signal. The efficiency of the pulse detection, pile-up rejection and/or correction, together with the dead-time of the system, are therein analyzed through the use of some specific algorithms for pulse processing, and the results obtained validate the beneficial use of emulators for the accurate calibration process of spectrometric systems.

Digital repeat analysis; setup and operation.

Science.gov (United States)

Nol, J; Isouard, G; Mirecki, J

2006-06-01

Since the emergence of digital imaging, there have been questions about the necessity of continuing reject analysis programs in imaging departments to evaluate performance and quality. As a marketing strategy, most suppliers of digital technology focus on the supremacy of the technology and its ability to reduce the number of repeats, resulting in less radiation doses given to patients and increased productivity in the department. On the other hand, quality assurance radiographers and radiologists believe that repeats are mainly related to positioning skills, and repeat analysis is the main tool to plan training needs to up-skill radiographers. A comparative study between conventional and digital imaging was undertaken to compare outcomes and evaluate the need for reject analysis. However, digital technology still being at its early development stages, setting a credible reject analysis program became the major task of the study. It took the department, with the help of the suppliers of the computed radiography reader and the picture archiving and communication system, over 2 years of software enhancement to build a reliable digital repeat analysis system. The results were supportive of both philosophies; the number of repeats as a result of exposure factors was reduced dramatically; however, the percentage of repeats as a result of positioning skills was slightly on the increase for the simple reason that some rejects in the conventional system qualifying for both exposure and positioning errors were classified as exposure error. The ability of digitally adjusting dark or light images reclassified some of those images as positioning errors.

Supercoherent phenomena in pulsed power

International Nuclear Information System (INIS)

O'Rourke, R.C.

1983-01-01

This chapter proposes the formulation of programs of basic physics research to transform Pulsed Power Technology (PPT) to Pulsed Power Science and Technology (PPS and T) by formulating the laws of the quantized microscopic electromagnetic field; applying the microscopic electromagnetic field theory to the generation, propagation and deposition of pulses in nonlinear networks; learning more about the basic super coherent ''micro-structure'' in space and time of the many-photon states of pulsed laser beams; learning more about the basic super coherent ''micro-structure'' in space and time of the many-electronstates of pulsed electron and ion laser beams; and learning everything about the ''micro-picture'' of so-called ''dielectric breakdown'' and the associated absolute time delays. Promotes the idea that laser, electron and ion beams are similar kinds of pulses in the microscopic electromagnetic field. Presents expression for the microscopic electromagnetic field in order to show the role of supercoherence in PPS and T

Pulse plating

CERN Document Server

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

2012-01-01

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

[Effect of dexmedetomidine on emergence agitation after general anesthesia in children undergoing odontotherapy in day-surgery operating room].

Science.gov (United States)

Lin, Luo; Yueming, Zhang; Meisheng, Li; Jiexue, Wang; Yang, Ji

2017-12-01

To study the effectiveness of dexmedetomidine used for general anesthesia maintenance in children undergoing odontotherapy in day-surgery operating room in reducing the incidence of emergence agitation (EA). Eighty children undergoing odontotherapy and under general anesthesia in day-surgery operating room were randomized into two groups, group A (n=40) and group B (n=40). Each patient in group A was administered with a bolus dose of dexmedetomidine (1.0 μg·kg⁻¹, saline diluted to 10 mL) pump-infused after intubation and a maintenance dose of 0.1-0.4 mL·(kg·h)⁻¹ followed-up until 45 min before the end of operation. Each patient in group B was administered with a bolus dose of normal saline 10 mL pump-infused after intubation and maintenance dose of 0.1-0.4 mL·(kg·h)⁻¹ followed-up until 45 min before the end of operation. Gender, age, weight, physical status according to the American Society of Anesthesiologists, perioperative heart rate (HR), mean arterial pressure (MAP), pulse oxygen saturation (SpO₂), sufentanil dosage, duration of surgery, time of extubation, time of regaining consciousness, and time to reach modified Aldrete's score≥12 were recorded. Behavior in postanesthesia care unit was rated on the four-point agitation scale. Compared with group B, decreases were observed in HR and MAP at the beginning of operation, in 10 and 30 min, 1 and 2 h after the beginning of operation, and after extubation of group A (Pgeneral anesthesia maintenance in children undergoing odontotherapy in day-surgery operating room, dexmedetomidine results in low incidence of EA during recovery and more stable vital signs.

Laser-pulsed relativistic electron gun

International Nuclear Information System (INIS)

Sherman, N.K.

1986-01-01

A relativistic (β ≅ 0.8) electron gun with good emittance and subnanosecond pulse duration which can be synchronized to picosecond laser pulses is being developed at NRC for use in studies of particle acceleration by lasers. Bursts of electron pulses exceeding 280 keV in energy have been extracted into air form a laser-driven vacuum photodiode. Trains of 5 ps pulses of ultraviolet UV light illuminate a magnesium cathode. Photoelectrons emitted from the cathode are accelerated in a graded electrostatic potential set up by a 360 kV Marx-generator. The UV pulses are obtained by doubling the frequency of a 606 nm dye laser modelocked at 160 MHz. Electron energies were measured by residual range in an echelon of Al foils. Total charge per burst was measured by picoammeter. Time structure of the bursts has been examined with plastic scintillator and a fast photomultiplier. Tests on a low voltage photodiode achieved a current density of 180 A/cm/sup 2/ from an Mg cathode, with quantum efficiency of 2.4 x 10/sup -6/ electron per UV photon. The brevity and intensity of the laser pulses cause the electric charge collected per pulse to increase linearly with bias voltage rather than according to the Langmuir-Child law. Gun emittance is about 150 mm-msr and beam brightness is about 1A/cm/sup 2/-sr. Estimated duration of individual electron pulses of a burst is about 400 ps with instantaneous current of about 0.1 mA. Energy spread within one pulse is expected to be about 15%. This gun has the potential to be a useful source of relativistic electrons for laser acceleration studies

Genus-specific protein binding to the large clusters of DNA repeats (short regularly spaced repeats) present in Sulfolobus genomes

DEFF Research Database (Denmark)

Peng, Xu; Brügger, Kim; Shen, Biao

2003-01-01

terminally modified and corresponds to SSO454, an open reading frame of previously unassigned function. It binds specifically to DNA fragments carrying double and single repeat sequences, binding on one side of the repeat structure, and producing an opening of the opposite side of the DNA structure. It also...... recognizes both main families of repeat sequences in S. solfataricus. The recombinant protein, expressed in Escherichia coli, showed the same binding properties to the SRSR repeat as the native one. The SSO454 protein exhibits a tripartite internal repeat structure which yields a good sequence match...... with a helix-turn-helix DNA-binding motif. Although this putative motif is shared by other archaeal proteins, orthologs of SSO454 were only detected in species within the Sulfolobus genus and in the closely related Acidianus genus. We infer that the genus-specific protein induces an opening of the structure...

Differential Hall-sensor Pulsed Eddy Current Probe for the Detection of Wall thinning in an Insulated Stainless Steel Pipe

International Nuclear Information System (INIS)

Park, D. G.; Angani, Chandra S.; Cheong, Y. M.; Kim, C. G.

2010-01-01

The local wall thinning is one of the most important factors to limit the life-extension of large structures, such as the pipe lines in the NPPs. The pipelines are covered with a thermal insulator for low thermal loss. The PEC testing is the promising technological approach to the NDT, and it has been principally developed for the measurement of surface flaws, subsurface flaws and corrosion. In the pulsed eddy current (PEC) technique, the excitation coil is driven by repeated pulses. According to the skin - depth relationship multiple frequency components penetrate to different depths, hence the PEC technique has the potential for bringing up deeper information about the tested sample. Because of the potential advantages of the PEC, prevalent investigations on this technique have been done. In the present study a differential probe which is used in the Pulsed Eddy Current (PEC) system has been fabricated for the detection of wall thinning of insulated pipelines in a nuclear power plant (NPP). This technique can be used as a potential tool to detect the corrosion or the wall thinning of the pipelines without removing the insulation

System for increasing laser pulse rate

International Nuclear Information System (INIS)

1980-01-01

A technique of static elements is disclosed for combining a plurality of laser beams having time sequenced, pulsed radiation to achieve an augmented pulse rate. The technique may also be applied in a system for combining both time sequenced pulses and frequency distinct pulses for use in a system for isotope enrichment. (author)

Coexistence of 3G repeaters with LTE base stations.

Science.gov (United States)

Yeo, Woon-Young; Lee, Sang-Min; Hwang, Gyung-Ho; Kim, Jae-Hoon

2013-01-01

Repeaters have been an attractive solution for mobile operators to upgrade their wireless networks at low cost and to extend network coverage effectively. Since the first LTE commercial deployment in 2009, many mobile operators have launched LTE networks by upgrading their 3G and legacy networks. Because all 3G frequency bands are shared with the frequency bands for LTE deployment and 3G mobile operators have an enormous number of repeaters, reusing 3G repeaters in LTE networks is definitely a practical and cost-efficient solution. However, 3G repeaters usually do not support spatial multiplexing with multiple antennas, and thus it is difficult to reuse them directly in LTE networks. In order to support spatial multiplexing of LTE, the role of 3G repeaters should be replaced with small LTE base stations or MIMO-capable repeaters. In this paper, a repeater network is proposed to reuse 3G repeaters in LTE deployment while still supporting multilayer transmission of LTE. Interestingly, the proposed network has a higher cluster throughput than an LTE network with MIMO-capable repeaters.

Repeatability & Workability Evaluation of SIGMOD 2009

KAUST Repository

Manegold, Stefan

2010-12-15

SIGMOD 2008 was the first database conference that offered to test submitters\\' programs against their data to verify the repeatability of the experiments published [1]. Given the positive feedback concerning the SIGMOD 2008 repeatability initiative, SIGMOD 2009 modified and expanded the initiative with a workability assessment.

Repeatability & Workability Evaluation of SIGMOD 2009

KAUST Repository

Manegold, Stefan; Manolescu, Ioana; Afanasiev, Loredana; Feng, Jieling; Gou, G.; Hadjieleftheriou, Marios; Harizopoulos, Stavros; Kalnis, Panos; Karanasos, Konstantinos; Laurent, Dominique; Lupu, M.; Onose, N.; Ré , C.; Sans, Virginie; Senellart, Pierre; Wu, T.; Shasha, Dennis E.

2010-01-01

SIGMOD 2008 was the first database conference that offered to test submitters' programs against their data to verify the repeatability of the experiments published [1]. Given the positive feedback concerning the SIGMOD 2008 repeatability initiative, SIGMOD 2009 modified and expanded the initiative with a workability assessment.

Pulsed irradiation of enriched UO{sub 2} in the Annular Core Pulse Reactor (ACPR)

Energy Technology Data Exchange (ETDEWEB)

Schmidt, T R; Lucoff, D M; Reil, K O; Croucher, D W [Sandia Laboratories (United States)

1974-07-01

A series of experiments have been conducted in the Annular Core Pulse Reactor (ACPR) to determine the energy deposition and behavior of enriched UO{sub 2} under pulse conditions. In the experiment single unirradiated pellets with enrichments up to 25 percent were pulse heated to melt temperatures. Temperature and fission product inventory measurements were made and compared with neutron transport calculations. (author)

Modeling seismic stimulation: Enhanced non-aqueous fluid extraction from saturated porous media under pore-pressure pulsing at low frequencies

Science.gov (United States)

Lo, Wei-Cheng; Sposito, Garrison; Huang, Yu-Han

2012-03-01

Seismic stimulation, the application of low-frequency stress-pulsing to the boundary of a porous medium containing water and a non-aqueous fluid to enhance the removal of the latter, shows great promise for both contaminated groundwater remediation and enhanced oil recovery, but theory to elucidate the underlying mechanisms lag significantly behind the progress achieved in experimental research. We address this conceptual lacuna by formulating a boundary-value problem to describe pore-pressure pulsing at seismic frequencies that is based on the continuum theory of poroelasticity for an elastic porous medium permeated by two immiscible fluids. An exact analytical solution is presented that is applied numerically using elasticity parameters and hydraulic data relevant to recent proof-of-principle laboratory experiments investigating the stimulation-induced mobilization of trichloroethene (TCE) in water flowing through a compressed sand core. The numerical results indicated that significant stimulation-induced increases of the TCE concentration in effluent can be expected from pore-pressure pulsing in the frequency range of 25-100 Hz, which is in good agreement with what was observed in the laboratory experiments. Sensitivity analysis of our numerical results revealed that the TCE concentration in the effluent increases with the porous medium framework compressibility and the pulsing pressure. Increasing compressibility also leads to an optimal stimulation response at lower frequencies, whereas changing the pulsing pressure does not affect the optimal stimulation frequency. Within the context of our model, the dominant physical cause for enhancement of non-aqueous fluid mobility by seismic stimulation is the dilatory motion of the porous medium in which the solid and fluid phases undergo opposite displacements, resulting in stress-induced changes of the pore volume.

Pulsed neutron generator

International Nuclear Information System (INIS)

Bespalov, D.F.; Bykovskii, Yu.A.; Vergun, I.I.; Kozlovskii, K.I.; Kozyrev, Yu.P.; Leonov, R.K.; Simagin, B.I.; Tsybin, A.S.; Shikanov, A.Ie.

1986-03-01

The paper describes a new device for generating pulsed neutron fields, utilized in nuclear geophysics for carrying out pulsed neutron logging and activation analysis under field conditions. The invention employs a sealed-off neutron tube with a laser ion source which increases neutron yield to the level of 10 neutrons per second or higher. 2 refs., 1 fig

Coaxial pulse matching transformer

International Nuclear Information System (INIS)

Ledenev, V.V.; Khimenko, L.T.

1986-01-01

This paper describes a coaxial pulse matching transformer with comparatively simple design, increased mechanical strength, and low stray inductance. The transformer design makes it easy to change the turns ratio. The circuit of the device and an expression for the current multiplication factor are presented; experiments confirm the efficiency of the transformer. Apparatus with a coaxial transformer for producing high-power pulsed magnetic fields is designed (current pulses of 1-10 MA into a load and a natural frequency of 100 kHz)

Low power arcjet thruster pulse ignition

Science.gov (United States)

Sarmiento, Charles J.; Gruber, Robert P.

1987-01-01

An investigation of the pulse ignition characteristics of a 1 kW class arcjet using an inductive energy storage pulse generator with a pulse width modulated power converter identified several thruster and pulse generator parameters that influence breakdown voltage including pulse generator rate of voltage rise. This work was conducted with an arcjet tested on hydrogen-nitrogen gas mixtures to simulate fully decomposed hydrazine. Over all ranges of thruster and pulser parameters investigated, the mean breakdown voltages varied from 1.4 to 2.7 kV. Ignition tests at elevated thruster temperatures under certain conditions revealed occasional breakdowns to thruster voltages higher than the power converter output voltage. These post breakdown discharges sometimes failed to transition to the lower voltage arc discharge mode and the thruster would not ignite. Under the same conditions, a transition to the arc mode would occur for a subsequent pulse and the thruster would ignite. An automated 11 600 cycle starting and transition to steady state test demonstrated ignition on the first pulse and required application of a second pulse only two times to initiate breakdown.

Device for flattening statistically distributed pulses

International Nuclear Information System (INIS)

Il'kanaev, G.I.; Iskenderov, V.G.; Rudnev, O.V.; Teller, V.S.

1976-01-01

The description is given of a device that converts the series of statistically distributed pulses into a pseudo-uniform one. The inlet pulses switch over the first counter, and the second one is switched over by the clock pulses each time the uniformity of the counters' states is violated. This violation is recorded by the logic circuit which passes to the output the clock pulses in the amount equal to that of the pulses that reached the device inlet. Losses at the correlation between the light velocity and the sampling rate up to 0.3 do not exceed 0.7 per cent for the memory of pulse counters 3, and 0.035 per cent for memory 7

Simulation of neutrons and gamma pulse signal and research on the pulse shape discrimination technology

International Nuclear Information System (INIS)

Zuo Guangxia; He Bin; Xu Peng; Qiu Xiaolin; Ma Wenyan; Li Sufen

2012-01-01

In neutrons detection, it is important to discriminate the neutron signals from the gamma-ray background. In this article, simulation of neutrons and gamma pulse signals is developed based on the LabVIEW platform. Two digital algorithms of the charge comparison method and the pulse duration time method are realized using 10000 simulation signals. Experimental results show that neutron and gamma pulse signals can be discriminated by the two methods, and the pulse duration time method is better than the charge comparison method. (authors)

IAE pulsed electrostatic accelerator

International Nuclear Information System (INIS)

Afanas'ev, V.P.; Ganzhelyuk, M.L.; Kozlov, L.D.; Koltypin, E.A.; Molchanov, Yu.D.; Otroshchenko, G.A.; Yan'kov, G.B.

1976-01-01

The modernized pulse electrostatic accelerator using the klystron ion grouping and the beam interruption system prior to acceleration is described. The accelerator is modernized in order to improve parameters of a current pulse and to decrease the background in the measurement room. The ion beam of needed dimensions is obtained with the help of a high-frequency source and a beam grouping and deflection system. The general view of the beam grouping and deflection system is shown. The ion beam forming process is considered in detail. The modernized electrostatic accelerator permits to obtain a pulse current with a pulse length of 1.5 ns and an amplitude of 1.5 - 2 μA. With the repetition frequency of 2 MHz, the average target current is about 6 μA

Square pulse linear transformer driver

Directory of Open Access Journals (Sweden)

A. A. Kim

2012-04-01

Full Text Available The linear transformer driver (LTD technological approach can result in relatively compact devices that can deliver fast, high current, and high-voltage pulses straight out of the LTD cavity without any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The usual LTD architecture [A. A. Kim, M. G. Mazarakis, V. A. Sinebryukhov, B. M. Kovalchuk, V. A. Vizir, S. N Volkov, F. Bayol, A. N. Bastrikov, V. G. Durakov, S. V. Frolov, V. M. Alexeenko, D. H. McDaniel, W. E. Fowler, K. LeCheen, C. Olson, W. A. Stygar, K. W. Struve, J. Porter, and R. M. Gilgenbach, Phys. Rev. ST Accel. Beams 12, 050402 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050402; M. G. Mazarakis, W. E. Fowler, A. A. Kim, V. A. Sinebryukhov, S. T. Rogowski, R. A. Sharpe, D. H. McDaniel, C. L. Olson, J. L. Porter, K. W. Struve, W. A. Stygar, and J. R. Woodworth, Phys. Rev. ST Accel. Beams 12, 050401 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050401] provides sine shaped output pulses that may not be well suited for some applications like z-pinch drivers, flash radiography, high power microwaves, etc. A more suitable power pulse would have a flat or trapezoidal (rising or falling top. In this paper, we present the design and first test results of an LTD cavity that generates such a type of output pulse by including within its circular array a number of third harmonic bricks in addition to the main bricks. A voltage adder made out of a square pulse cavity linear array will produce the same shape output pulses provided that the timing of each cavity is synchronized with the propagation of the electromagnetic pulse.

[Music, pulse, heart and sport].

Science.gov (United States)

Gasenzer, E R; Leischik, R

2018-02-01

Music, with its various elements, such as rhythm, sound and melody had the unique ability even in prehistoric, ancient and medieval times to have a special fascination for humans. Nowadays, it is impossible to eliminate music from our daily lives. We are accompanied by music in shopping arcades, on the radio, during sport or leisure time activities and in wellness therapy. Ritualized drumming was used in the medical sense to drive away evil spirits or to undergo holy enlightenment. Today we experience the varied effects of music on all sensory organs and we utilize its impact on cardiovascular and neurological rehabilitation, during invasive cardiovascular procedures or during physical activities, such as training or work. The results of recent studies showed positive effects of music on heart rate and in therapeutic treatment (e. g. music therapy). This article pursues the impact of music on the body and the heart and takes sports medical aspects from the past and the present into consideration; however, not all forms of music and not all types of musical activity are equally suitable and are dependent on the type of intervention, the sports activity or form of movement and also on the underlying disease. This article discusses the influence of music on the body, pulse, on the heart and soul in the past and the present day.

Study of loading/air back-pulse cleaning cycles on the performance of ceramic membrane filters

International Nuclear Information System (INIS)

Waggoner, Charles; Alderman, Steven; Parsons, Michael; Hogoncamp, Kristina; Alderman, Steven

2007-01-01

Available in abstract form only. Full text of publication follows: The most commonly identified threats to conventional glass fiber HEPA filter performance are moisture and rapid blinding of filters by smoke. Regenerable filter media composed of ceramics or sintered metal can be utilized as pre-filters to protect the more vulnerable glass fiber HEPA filters in the event of upset conditions. Additionally, used in a pre-filtering application, the use of these regenerable filters can potentially extend the lifetime of conventional units. A series of tests have been conducted using CeraMem ceramic membrane filters in an effort to evaluate their performance after repeated loading and air back pulse cleaning. This was done in an effort to access filter performance after repeated loading/cleaning cycles. The filters were loaded using a solid potassium chloride aerosol challenge. The filters were evaluated for pressure drop and filtering efficiency changes from one cleaning cycle to the next. Additionally, the particle size distribution of the aerosol penetrating the filters was measured. (authors)

In vitro optical detection of simulated blood pulse in a human tooth pulp model.

Science.gov (United States)

Niklas, A; Hiller, K-A; Jaeger, A; Brandt, M; Putzger, J; Ermer, C; Schulz, I; Monkman, G; Giglberger, S; Hirmer, M; Danilov, S; Ganichev, S; Schmalz, G

2014-01-01

Noninvasive optical methods such as photoplethysmography, established for blood pulse detection in organs, have been proposed for vitality testing of human dental pulp. However, no information is available on the mechanism of action in a closed pulp chamber and on the impairing influence of other than pulpal blood flow sources. Therefore, the aim of the present in vitro study was to develop a device for the optical detection of pulpal blood pulse and to investigate the influence of different parameters (including gingival blood flow [GBF] simulation) on the derived signals. Air, Millipore water, human erythrocyte suspensions (HES), non-particulate hemoglobin suspension (NPHS), and lysed hemoglobin suspension (LHES) were pulsed through a flexible (silicone) or a rigid (glass) tube placed within an extracted human molar in a tooth-gingiva model. HES was additionally pulsed through a rigid tube around the tooth, simulating GBF alone or combined with the flow through the tooth by two separate peristaltic pumps. Light from high-power light-emitting diodes (625 nm (red) and 940 nm (infrared [IR]); Golden Dragon, Osram, Germany) was introduced to the coronal/buccal part of the tooth, and the signal amplitude [∆U, in volts] of transmitted light was detected by a sensor at the opposite side of the tooth. Signal processing was carried out by means of a newly developed blood pulse detector. Finally, experiments were repeated with the application of rubber dam (blue, purple, pink, and black), aluminum foil, and black antistatic plastic foil. Nonparametric statistical analysis was applied (n = 5; α = 0.05). Signals were obtained for HES and LHES, but not with air, Millipore water, or NPHS. Using a flexible tube, signals for HES were higher for IR compared to red light, whereas for the rigid tube, the signals were significantly higher for red light than for IR. In general, significantly less signal amplitude was recorded for HES with the rigid glass tube than with the

Electromagnetic pulses, localized and causal

Science.gov (United States)

Lekner, John

2018-01-01

We show that pulse solutions of the wave equation can be expressed as time Fourier superpositions of scalar monochromatic beam wave functions (solutions of the Helmholtz equation). This formulation is shown to be equivalent to Bateman's integral expression for solutions of the wave equation, for axially symmetric solutions. A closed-form one-parameter solution of the wave equation, containing no backward-propagating parts, is constructed from a beam which is the tight-focus limit of two families of beams. Application is made to transverse electric and transverse magnetic pulses, with evaluation of the energy, momentum and angular momentum for a pulse based on the general localized and causal form. Such pulses can be represented as superpositions of photons. Explicit total energy and total momentum values are given for the one-parameter closed-form pulse.

Twenty-channel high-voltage pulse generators

International Nuclear Information System (INIS)

Anan'in, P.S.; Kashirin, A.P.

1980-01-01

A 20-channel high-voltage pulse generator operating with a mismatched load is described. The generator contains shaping lines 20 m long made of coaxial cable, a trigatron-type discharged, and isolating plates. The channel characteristic impedance is 50 Ohm. The maximum pulse amplitude is up to 15 kV on a high-resistance load and 7.5 kV on a matched one. The pulse duration is 100 ns at a pulse rise time of 12 ns, the delay introduced by the generator is 200 +-2.5 ns. Provision is made in the control circuit for compensation of the shaped pulse and separation of a pulse reflected from the load. The reflected pulse shape and amplitude characterize load parameters. Generator tests proved its high operational reliability (after 10 5 operations no significant changes in generator performances have been observed). The generator is intended for filmless data output from spark chambers

The Pulse Line Ion Accelerator Concept

Energy Technology Data Exchange (ETDEWEB)

Briggs, Richard J.

2006-02-15

The Pulse Line Ion Accelerator concept was motivated by the desire for an inexpensive way to accelerate intense short pulse heavy ion beams to regimes of interest for studies of High Energy Density Physics and Warm Dense Matter. A pulse power driver applied at one end of a helical pulse line creates a traveling wave pulse that accelerates and axially confines the heavy ion beam pulse. Acceleration scenarios with constant parameter helical lines are described which result in output energies of a single stage much larger than the several hundred kilovolt peak voltages on the line, with a goal of 3-5 MeV/meter acceleration gradients. The concept might be described crudely as an ''air core'' induction linac where the PFN is integrated into the beam line so the accelerating voltage pulse can move along with the ions to get voltage multiplication.

Determination of Selenium in infant formula by differential pulse cathodic stripping voltammetry

Directory of Open Access Journals (Sweden)

"Oveisi MR

2002-07-01

Full Text Available Selenium as a nonmetallic chemical element has received high attention of biologists because of its dual role as an essential trace nutrient and a toxic element. This interest has created a need for reliable analytical methods for determination of selenium. In this investigation determination of selenium by differential pulse cathodic stripping voltammetry and the influence of various parameters such as deposition potentials, deposition time. Cu concentration pH, etc. on selenium peak in voltammogram are described. Determination of selenium was accomplished in mixture of acetic acid, hydrochloric acid and sodium chloride buffer (pH=1 with a scan rate of 60 mv/s and a pulse height of 100 my by hanging mercury drop electrode (HMDE as working electrode. The solution was stirred during pre-electrolysis at - 350 mv (vs SCE for 30 s and the potential was scanned between - 350 mv and - 800 mv. The determination limit of the method was 0.005 mg/kg for the sample. The calibration curves were linear in the range of 0-30 μg/L (R2=0.996, p<0.001. Repeatability of the method at concentrations of 30 and 0.5 μg/L were 2.5 and 10.5% respectively.

ENDOR with band-selective shaped inversion pulses

Science.gov (United States)

Tait, Claudia E.; Stoll, Stefan

2017-04-01

Electron Nuclear DOuble Resonance (ENDOR) is based on the measurement of nuclear transition frequencies through detection of changes in the polarization of electron transitions. In Davies ENDOR, the initial polarization is generated by a selective microwave inversion pulse. The rectangular inversion pulses typically used are characterized by a relatively low selectivity, with full inversion achieved only for a limited number of spin packets with small resonance offsets. With the introduction of pulse shaping to EPR, the rectangular inversion pulses can be replaced with shaped pulses with increased selectivity. Band-selective inversion pulses are characterized by almost rectangular inversion profiles, leading to full inversion for spin packets with resonance offsets within the pulse excitation bandwidth and leaving spin packets outside the excitation bandwidth largely unaffected. Here, we explore the consequences of using different band-selective amplitude-modulated pulses designed for NMR as the inversion pulse in ENDOR. We find an increased sensitivity for small hyperfine couplings compared to rectangular pulses of the same bandwidth. In echo-detected Davies-type ENDOR, finite Fourier series inversion pulses combine the advantages of increased absolute ENDOR sensitivity of short rectangular inversion pulses and increased sensitivity for small hyperfine couplings of long rectangular inversion pulses. The use of pulses with an almost rectangular frequency-domain profile also allows for increased control of the hyperfine contrast selectivity. At X-band, acquisition of echo transients as a function of radiofrequency and appropriate selection of integration windows during data processing allows efficient separation of contributions from weakly and strongly coupled nuclei in overlapping ENDOR spectra within a single experiment.

Intraoperative colonic pulse oximetry in left-sided colorectal surgery: can it predict anastomotic leak?

Science.gov (United States)

Salusjärvi, Johannes M; Carpelan-Holmström, Monika A; Louhimo, Johanna M; Kruuna, Olli; Scheinin, Tom M

2018-03-01

An anastomotic leak is a fairly common and a potentially lethal complication in colorectal surgery. Objective methods to assess the viability and blood circulation of the anastomosis could help in preventing leaks. Intraoperative pulse oximetry is a cheap, easy to use, fast, and readily available method to assess tissue viability. Our aim was to study whether intraoperative pulse oximetry can predict the development of an anastomotic leak. The study was a prospective single-arm study conducted between the years 2005 and 2011 in Helsinki University Hospital. Patient material consisted of 422 patients undergoing elective left-sided colorectal surgery. The patients were operated by one of the three surgeons. All of the operations were partial or total resections of the left side of the colon with a colorectal anastomosis. The intraoperative colonic oxygen saturation was measured with pulse oximetry from the colonic wall, and the values were analyzed with respect to post-operative complications. 2.3 times more operated anastomotic leaks occurred when the colonic StO 2 was ≤ 90% (11/129 vs 11/293). The mean colonic StO 2 was 91.1 in patients who developed an operated anastomotic leak and 93.0 in patients who did not. With logistic regression analysis, the risk of operated anastomotic leak was 4.2 times higher with StO 2 values ≤ 90%. Low intraoperative colonic StO 2 values are associated with the occurrence of anastomotic leak. Despite its handicaps, the method seems to be useful in assessing anastomotic viability.

The Toulouse pulsed magnet facility

International Nuclear Information System (INIS)

2006-01-01

The 'Laboratoire National des Champs Magnetiques Pulses' (LNCMP) is an international user facility providing access to pulsed magnetic fields up to and beyond 60 T. The laboratory disposes of 10 magnet stations equipped with long-pulse magnets operating in the 35-60 T range and a short-pulse system reaching magnetic fields in excess of 70 T. The experimental infrastructure includes various high and low-temperature systems ranging from ordinary flow-type cryostats to dilution refrigerators reaching 50 mK, as well as different types of high-pressure cells. Experimental techniques include magnetization, transport, luminescence, IR-spectroscopy and polarimetry. The LNCMP pursues an extensive in-house research program focussing on all technological and scientific aspects of pulsed magnetic fields. Recent technical developments include the implementation of 60 T rapid-cooling coils, an 80 T prototype, a pulsed dipole magnet for optical investigations of dilute matter and a transportable horizontal access magnet for small angle x-ray scattering experiments. Scientific activities cover a variety of domains, including correlated electron systems, magnetism, semiconductors and nanoscience

A 16.3 pJ/pulse low-complexity and energy-efficient transmitter with adjustable pulse parameters

International Nuclear Information System (INIS)

Jiang Jun; Zhao Yi; Shao Ke; Chen Hu; Xia Lingli; Hong Zhiliang

2011-01-01

This paper presents a novel, fully integrated transmitter for 3-5 GHz pulsed UWB. The BPSK modulation transmitter has been implemented in SMIC CMOS 0.13 μm technology with a 1.2-V supply voltage and a die size of 0.8 x 0.95 mm 2 . This transmitter is based on the impulse response filter method, which uses a tunable R paralleled with a LC frequency selection network to realize continuously adjustable pulse parameters, including bandwidth, width and amplitude. Due to the extremely low duty of the pulsed UWB, a proposed output buffer is employed to save power consumption significantly. Finally, measurement results show that the transmitter consumes only 16.3 pJ/pulse to achieve a pulse repetition rate of 100 Mb/s. Generated pulses strictly comply with the FCC spectral mask. The continuously variable pulse width is from 900 to 1.5 ns and the amplitude with the minimum 178 mVpp and the maximum 432 mVpp can be achieved. (semiconductor integrated circuits)

Herophilus on pulse

Directory of Open Access Journals (Sweden)

Afonasin, Eugene

2015-01-01

Full Text Available The first detailed study of the pulse (sphygmology is associated in antiquity with Herophilus (the end of the 4th century BCE, an Alexandrian physician, renowned for his anatomical discoveries. The scholars also attribute to him a discovery of a portable and adjustable water-clock, used for measuring ‘natural’ and ‘unnatural’ pulse and, accordingly, temperature of the patient. In the article we translate the principal ancient evidences and comment upon them. We study both the practical aspects of ancient sphygmology and the theoretical speculations associated with it. Ancient theory of proportion and musical harmony allowed to build a classification of the pulses, but the medical experience did not fit well in the Procrustean bed of this rather simple theory.

Radiobiological response to ultra-short pulsed megavoltage electron beams of ultra-high pulse dose rate.

Science.gov (United States)

Beyreuther, Elke; Karsch, Leonhard; Laschinsky, Lydia; Leßmann, Elisabeth; Naumburger, Doreen; Oppelt, Melanie; Richter, Christian; Schürer, Michael; Woithe, Julia; Pawelke, Jörg

2015-08-01

In line with the long-term aim of establishing the laser-based particle acceleration for future medical application, the radiobiological consequences of the typical ultra-short pulses and ultra-high pulse dose rate can be investigated with electron delivery. The radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance) was used to mimic the quasi-continuous electron beam of a clinical linear accelerator (LINAC) for comparison with electron pulses at the ultra-high pulse dose rate of 10(10) Gy min(-1) either at the low frequency of a laser accelerator or at 13 MHz avoiding effects of prolonged dose delivery. The impact of pulse structure was analyzed by clonogenic survival assay and by the number of residual DNA double-strand breaks remaining 24 h after irradiation of two human squamous cell carcinoma lines of differing radiosensitivity. The radiation response of both cell lines was found to be independent from electron pulse structure for the two endpoints under investigation. The results reveal, that ultra-high pulse dose rates of 10(10) Gy min(-1) and the low repetition rate of laser accelerated electrons have no statistically significant influence (within the 95% confidence intervals) on the radiobiological effectiveness of megavoltage electrons.

Capnography is superior to pulse oximetry for the detection of respiratory depression during colonoscopy La capnografía es superior a la pulsioximetría en la detección de depresión respiratoria durante las colonoscopias

Directory of Open Access Journals (Sweden)

G. Cacho

2010-02-01

Full Text Available Background: pulse oximetry is a widely accepted procedure for ventilatory monitoring during gastrointestinal endoscopy, but this method provides an indirect measurement of the respiratory function. In addition, detection of abnormal ventilatory activity can be delayed, especially if supplemental oxygen is provided. Capnography offers continuous real-time measurement of expiratory carbon dioxide. Objective: we aimed at prospectively examining the advantages of capnography over the standard pulse oximetry monitoring during sedated colonoscopies. Patients and methods:fifty patients undergoing colonoscopy were simultaneously monitored with pulse oximetry and capnography by using two different devices in each patient. Several sedation regimens were administered. Episodes of apnea or hypoventilation detected by capnography were compared with the occurrence of hypoxemia. Results: twenty-nine episodes of disordered respiration occurred in 16 patients (mean duration 54.4 seconds. Only 38% of apnea or hypoventilation episodes were detected by pulse oximetry. A mean delay of 38.6 seconds was observed in the events detected by pulse oximetry (two episodes of disturbed ventilation were simultaneously detected by capnography and pulse oximetry. Conclusions: apnea or hypoventilation commonly occurs during colonoscopy with sedation. Capnography is more reliable than pulse oximetry in early detection of respiratory depression in this setting.

Designs of pulsed power cryogenic transformers

International Nuclear Information System (INIS)

Singh, S.K.; Heyne, C.J.; Hackowrth, D.T.; Shestak, E.J.; Eckels, P.W.; Rogers, J.D.

1988-01-01

The Westinghouse Electric Corporation has completed designs of three pulsed power cryogenic transformers of three pulsed power cryogenic transformers for the Los Alamos National Laboratory. These transformers will be configured to transfer their stored energy sequentially to an electro-magnetic launcher and form a three-stage power supply. The pulse transformers will act as two winding energy storage solenoids which provide a high current and energy pulse compression by transforming a 50 kA power supply into a megamp level power supply more appropriate for the electromagnetic launcher duty. This system differs from more traditional transformer applications in that significant current levels do not exists simultaneously in the two windings of the pulse transformer. This paper describes the designs of the pulsed power cryogenic transformers

Diffusion and Swelling Measurements in Pharmaceutical Powder Compacts Using Terahertz Pulsed Imaging

Science.gov (United States)

Yassin, Samy; Su, Ke; Lin, Hungyen; Gladden, Lynn F; Zeitler, J Axel

2015-01-01

Tablet dissolution is strongly affected by swelling and solvent penetration into its matrix. A terahertz-pulsed imaging (TPI) technique, in reflection mode, is introduced as a new tool to measure one-dimensional swelling and solvent ingress in flat-faced pharmaceutical compacts exposed to dissolution medium from one face of the tablet. The technique was demonstrated on three tableting excipients: hydroxypropylmethyl cellulose (HPMC), Eudragit RSPO, and lactose. Upon contact with water, HPMC initially shrinks to up to 13% of its original thickness before undergoing expansion. HPMC and lactose were shown to expand to up to 20% and 47% of their original size in 24 h and 13 min, respectively, whereas Eudragit does not undergo dimensional change. The TPI technique was used to measure the ingress of water into HPMC tablets over a period of 24 h and it was observed that water penetrates into the tablet by anomalous diffusion. X-ray microtomography was used to measure tablet porosity alongside helium pycnometry and was linked to the results obtained by TPI. Our results highlight a new application area of TPI in the pharmaceutical sciences that could be of interest in the development and quality testing of advanced drug delivery systems as well as immediate release formulations. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:1658–1667, 2015 PMID:25645509

[Improved detection of the pulse oximeter signal with a digital nerve block in patients in poor health status].

Science.gov (United States)

Cordoví de Armas, L; Espinaco Valdés, J; Jiménez Paneque, R E; Costa Hidalgo, T; Vallongo Menéndez, M B

2008-10-01

To demonstrate the efficacy of a digital nerve block for improving pulse oximetry in conditions of low tissue perfusion. A randomized single-blind study of adult patients undergoing surgery under general anesthesia for conditions characterized by hypoperfusion. Patients were assigned to a control group or an experimental group. The experimental group received a digital nerve block in the middle finger of the left hand; a sensor was then placed on the finger for between 120 and 300 minutes. Age, sex, diagnosis, total observation time (TOT), percentage of time with no pulse oximeter signal (NoPO), and percentage of time with an unstable pulse oximeter signal (UnstPO) were recorded. Each patient was questioned between 16 and 24 hours after surgery and was examined for flushing, paresthesia, hypoesthesia, pain, and ecchymosis. The chi2 test was used to compare dichotomized or nominal variables and the t test was used to compare age, TOT, NoPO, and UnstPO. Values of P<.05 were considered statistically significant in both cases. Fifty patients were randomized to each group. A total of 82 patients remained in the study (control group=42, experimental group=40). There were no significant between-group differences in diagnoses or TOT. The mean values for NoPO and UnstPO were higher in the control group than in the experimental group (11.1% vs 4.4% and 35.9% vs 15.7%, respectively; P<.001). A digital nerve block can be used to prevent pulse oximetry failures in conditions of low peripheral perfusion.

Efficacy of long pulse Nd:YAG laser versus fractional Er:YAG laser in the treatment of hand wrinkles.

Science.gov (United States)

Robati, Reza M; Asadi, Elmira; Shafiee, Anoosh; Namazi, Nastaran; Talebi, Atefeh

2018-04-01

There are different modalities for hand rejuvenation. Fractional Er:YAG laser and long pulse Nd:YAG laser were introduced for treating hand wrinkles. We plan to compare fractional Er:YAG laser and long pulse Nd:YAG laser in a randomized controlled double-blind design with multiple sessions and larger sample size in comparison with previous studies. Thirty-three participants with hand wrinkles entered this study. They were randomly allocated to undergo three monthly laser treatments on each hand, one with a fractional Er:YAG laser and the other with a long pulse Nd:YAG laser. The evaluations included assessment of clinical improvement determined by two independent dermatologists not enrolled in the treatment along with measuring skin biomechanical property of hands using a sensitive biometrologic device with the assessment of cutaneous resonance running time (CRRT). Moreover, potential side effects and patients' satisfaction have been documented at baseline, 1 month after each treatment, and 3 months after the final treatment session. Clinical evaluation revealed both modalities significantly reduce hand wrinkles (p value lasers. Mean CRRT values also decreased significantly after the laser treatment compared to those of the baseline in both laser groups. There was no serious persistent side effect after both laser treatments. Both fractional Er:YAG and long pulse Nd:YAG lasers show substantial clinical improvement of hand skin wrinkles with no serious side effects. However, combination treatment by these lasers along with the other modalities such as fat transfer could lead to better outcomes in hand rejuvenation. IRCT2016032020468N4.

Sandia Pulsed Reactor Facility (SPRF) calculator-assisted pulse analysis and display system

International Nuclear Information System (INIS)

Estes, B.F.; Berry, D.T.

1980-02-01

Two solid-metal fast burst type reactors (SPR II and SPR III) are operated at the Sandia Pulsed Reactor Facility. Since startup of the reactors, oscilloscope traces have been used to record (by camera) the pulse (power) shape while log N systems have measured initial reactor period. Virtually no other pulse information is available. A decision was made to build a system that could collect the basic input data available from the reactor - fission chambers, photodiodes, and thermocouples - condition the signals and output the various parameters such as power, energy, temperature, period and lifetime on hard copy that would provide a record for operations personnel as well as the experimenter. Because the reactors operate in short time frames - pulse operation - it is convenient to utilize the classical Nordheim-Fuchs approximation of the diffusion equation to describe reactor behavior. This report describes the work performed to date in developing the calculator system and analytical models for computing the desired parameters

Novel expressed sequence tag- simple sequence repeats (EST ...

African Journals Online (AJOL)

Using different bioinformatic criteria, the SUCEST database was used to mine for simple sequence repeat (SSR) markers. Among 42,189 clusters, 1,425 expressed sequence tag- simple sequence repeats (EST-SSRs) were identified in silico. Trinucleotide repeats were the most abundant SSRs detected. Of 212 primer pairs ...

Reasons for and functional results of repeated hip arthroscopy: A continuous prospective study of 17 revisions out of 295 primary hip arthroscopies at mean 28months' follow-up.

Science.gov (United States)

Tissot, C; Merlini, L; Mercier, M; Bonin, N

2017-09-01

The rate of iterative arthroscopy has been increasing over the last decade as the technique has grown. The results of and reasons for these revision procedures, however, are not exactly known. We therefore conducted a prospective study to shed light on: 1) functional results and patient satisfaction following repeated arthroscopy, and 2) the relevant indications. Functional scores and patient satisfaction increase following repeated arthroscopy. MATERIALS AND METHOD: A single-center continuous prospective study without control group included patients undergoing repeated hip arthroscopy between September 2010 and September 2014, with a mean 28months' follow-up (median, 23.3months; range, 12-62months). Preoperative and follow-up functional assessment used the modified Harris hip, WOMAC and Christensen (NHAS) questionnaires, and a satisfaction scale. On etiological analysis, repeated arthroscopy was indicated if a cause of recurrent or persistent pain accessible to arthroscopic treatment was identified. Seventeen patients were included out of 295 primary arthroscopies (5.7%): 9 male, 8 female; median age, 29.6years (range, 16-48years). Indications for primary arthroscopy comprised 13 cases of femoroacetabular impingement, 3 labrum lesions with instability, 1 chondromatosis and 1 case of osteoarthritis. Eleven of the 17 primary lesions showed persistence, including 9 of the 13 cases of femoroacetabular impingement. There were 3 failures in 17 repeated arthroscopies. All functional scores improved, with a gain of 7 points (P<0.06) on modified Harris hip score, 25 points (P<0.0006) on WOMAC score, and 27 points (P<0.001) on NHAS score. Ten of the 17 patients were satisfied or very satisfied with the repeated arthroscopy (59%). Although less good than on primary arthroscopy, functional results on repeated hip arthroscopy were satisfactory in the short term. The main reason for repeated arthroscopy was persistence of initial abnormality due to insufficient treatment

Pulsed high-power beams

International Nuclear Information System (INIS)

Reginato, L.L.; Birx, D.L.

1988-01-01

The marriage of induction linac technology with nonlinear magnetic modulators has produced some unique capabilities. It is now possible to produce short-pulse electron beams with average currents measured in amperes, at gradients approaching 1-MeV/m, and with power efficiencies exceeding 50%. This paper reports on a 70-MeV, 3-kA induction accelerator (ETA II) constructed at the Lawrence Livermore National Laboratory that incorporates the pulse technology concepts that have evolved over the past several years. The ETA II is a linear induction accelerator and provides a test facility for demonstration of the high-average-power components and high-brightness sources used in such accelerators. The pulse drive of the accelerator is based on state-of-the-art magnetic pulse compressors with very high peak-power capability, repetition rates exceeding 1 kHz, and excellent reliability

Pulse Compression of Phase-matched High Harmonic Pulses from a Time-Delay Compensated Monochromator

Directory of Open Access Journals (Sweden)

Ito Motohiko

2013-03-01

Full Text Available Pulse compression of single 32.6-eV high harmonic pulses from a time-delay compensated monochromator was demonstrated down to 11±3 fs by compensating the pulse front tilt. The photon flux was intensified up to 5.7×109 photons/s on target by implementing high harmonic generation under a phase matching condition in a hollow fiber used for increasing the interaction length.

Experimental Observation of Generation of Superradiance Pulses in the Process of Backscattering of Pump Wave on the Intense Electron Bunch

CERN Document Server

Ginzburg, N S; Denisov, G G; Rozental, R M; Sergeev, A; Zotova, I V

2005-01-01

Recently significant progress was archived in the generation of multimegawatt subnanosecond pulses in millimeter wave band utilizing the cyclotron and Cherenkov mechanisms of superradiance (SR) [1,2]. We study the novel mechanism of SR when the powerful pumping wave undergoes the stimulated back scattering on the intense electron bunch. Due to the Doppler up shift the radiation frequency can significantly exceed the frequency of the pumping wave. With the relativistic microwave generator as a pumping wave source such a mechanism can be used for generation of the powerful pulse radiation in the short millimeter and submillimeter wave bands. Experiments on the observation of the stimulated scattering in the superradiance regime were carried out at Institute of Electrophysics RAS with two synchronized accelerators. The 4 ns electron beam from the first accelerator is used for generation of the 38 GHz 100 MW pumping wave which subsequently scattered on the subnanosecond 250 keV 1 kA electron bunch produced by the...

A digital long pulse integrator

International Nuclear Information System (INIS)

Broesch, J.D.; Strait, E.J.; Snider, R.T.

1996-10-01

A prototype digital integrator with very long integration capabilities has been developed and field tested on an inductive magnetic sensor on the DIII-D Tokamak. The integrator is being developed for use on ITER with a pulse length of 1000 s, and has direct applications for other long pulse Tokamaks. Inductive magnetic sensors are routinely used on existing Tokamaks, are well understood, and are extremely robust, however, they require integration of the signal to determine the magnetic field strength. The next generation of Tokamaks, will have pulse lengths of 1000 s or longer, require integrators with drift and noise characteristics compatible with the very long pulse lengths. This paper will discuss the architecture, algorithms, and programming of the Long Pulse Integrator (LPI). Of particular interest are the noise control and the built-in offset correction techniques used in this application

Dynamic pulse difference circuit

International Nuclear Information System (INIS)

Erickson, G.L.

1978-01-01

A digital electronic circuit of especial use for subtracting background activity pulses in gamma spectrometry is disclosed which comprises an up-down counter connected to count up with signal-channel pulses and to count down with background-channel pulses. A detector responsive to the count position of the up-down counter provides a signal when the up-down counter has completed one scaling sequence cycle of counts in the up direction. In an alternate embodiment, a detector responsive to the count position of the up-down counter provides a signal upon overflow of the counter

Attosecond pulse generation in noble gases in the presence of extreme high intensity THz pulses

International Nuclear Information System (INIS)

Balogh, E.; Varju, K.

2010-01-01

Complete text of publication follows. The shortest - attosecond - light pulses available today are produced by high harmonic generation (HHG) of near-infrared (NIR) laser pulses in noble gas jets, providing a broad spectral plateau of XUV radiation ending in a cutoff. The minimum pulse duration is determined by the achievable bandwidth (i.e. the position of the cutoff), and the chirp of the produced pulses. The extension of the cutoff by increasing the laser intensity is limited by the depletion and phase matching problems of the medium. An alternative method demonstrated to produce higher harmonic orders is by using longer pump pulse wavelength, with the disadvantage of decreased efficiency. Recently it was shown that application of a quasi-DC high strength electric field results in an increase of more than a factor of two in the order of efficiently generated high harmonics. However, the possibility to implement the method proposed in [3] of using a CO 2 laser to create a quasi-DC field for assisting HHG of the NIR laser is questionable, because it's technically very challenging to synchronize pulses from different laser sources. Alternatively, synchronous production of THz pulses with the NIR laser pulse offers a more promising route. The first numerical test of this idea has been reported in [4]. In this contribution we further investigate the method for realistic THz field strengths and short driving pulses, exploring the effect of longer pump laser wavelength on the process. We assume the presence of high intensity THz pulses for supplying the high-strength quasi-DC electric field. The spectrum as well as the chirp of the produced radiation is calculated. We use the non-adiabatic saddle point method to determine the generated radiation described in [6]. We simulate harmonic generation in noble gas atoms, with few cycle NIR pulses of peak intensity at and above 2 x 10 14 W/cm 2 (388 MV/cm) and wavelengths 800 nm and 1560 nm. The THz field strength is varied

Role of memory errors in quantum repeaters

International Nuclear Information System (INIS)

Hartmann, L.; Kraus, B.; Briegel, H.-J.; Duer, W.

2007-01-01

We investigate the influence of memory errors in the quantum repeater scheme for long-range quantum communication. We show that the communication distance is limited in standard operation mode due to memory errors resulting from unavoidable waiting times for classical signals. We show how to overcome these limitations by (i) improving local memory and (ii) introducing two operational modes of the quantum repeater. In both operational modes, the repeater is run blindly, i.e., without waiting for classical signals to arrive. In the first scheme, entanglement purification protocols based on one-way classical communication are used allowing to communicate over arbitrary distances. However, the error thresholds for noise in local control operations are very stringent. The second scheme makes use of entanglement purification protocols with two-way classical communication and inherits the favorable error thresholds of the repeater run in standard mode. One can increase the possible communication distance by an order of magnitude with reasonable overhead in physical resources. We outline the architecture of a quantum repeater that can possibly ensure intercontinental quantum communication

Acousto-optic replication of ultrashort laser pulses

Science.gov (United States)

Yushkov, Konstantin B.; Molchanov, Vladimir Ya.; Ovchinnikov, Andrey V.; Chefonov, Oleg V.

2017-10-01

Precisely controlled sequences of ultrashort laser pulses are required in various scientific and engineering applications. We developed a phase-only acousto-optic pulse shaping method for replication of ultrashort laser pulses in a TW laser system. A sequence of several Fourier-transform-limited pulses is generated from a single femtosecond laser pulse by means of applying a piecewise linear phase modulation over the whole emission spectrum. Analysis demonstrates that the main factor which limits maximum delay between the pulse replicas is spectral resolution of the acousto-optic dispersive delay line used for pulse shaping. In experiments with a Cr:forsterite laser system, we obtained delays from 0.3 to 3.5 ps between two replicas of 190 fs transform-limited pulses at the central wavelength of laser emission, 1230 nm.

Coherent combining pulse bursts in time domain

Science.gov (United States)

Galvanauskas, Almantas

2018-01-09

A beam combining and pulse stacking technique is provided that enhances laser pulse energy by coherent stacking pulse bursts (i.e. non-periodic pulsed signals) in time domain. This energy enhancement is achieved by using various configurations of Fabry-Perot, Gires-Tournois and other types of resonant cavities, so that a multiple-pulse burst incident at either a single input or multiple inputs of the system produces an output with a solitary pulse, which contains the summed energy of the incident multiple pulses from all beams. This disclosure provides a substantial improvement over conventional coherent-combining methods in that it achieves very high pulse energies using a relatively small number of combined laser systems, thus providing with orders of magnitude reduction in system size, complexity, and cost compared to current combining approaches.

Determination of pseudo multi-pulse production rate in GM counters by correlation analysis between signal pulses

International Nuclear Information System (INIS)

Hashimoto, Kengo; Ueda, Taizou

1996-01-01

A technique, based on the correlation analysis of signal pulses in time sequence, is proposed to determine the production rate of the pseudo multi-pulse in Geiger-Mueller (GM) counter. With a multi-channel scaler initiated by a signal pulse, subsequent pulses are recorded in sequence. The production of the multi-pulse increases the counting probability immediately after the initiation. By examining the deviation of the measured probability from the ideal counting probability, the production rate and the average lag time to produce the multi-pulse can be determined. By the use of the present technique, the production rate and the average lag time were obtained for the various GM tubes. These results indicate that the consumption of the quench gas results in a significant increase in the production rate but little variation in the lag time, and that the lag time strongly depends on the tube diameter. (author)

Breaking time-resolution limits in pulse radiolysis

International Nuclear Information System (INIS)

Yang Jinfeng; Kondoh, Takafumi; Norizawa, Kimihiro; Yoshida, Yoichi; Tagawa, Seiichi

2009-01-01

Pulse radiolysis, which is a time-resolved stroboscopic method based on ultrashort electron pulse and ultrashort analyzing light, is widely used for the study of the chemical kinetics and radiation primary processes or reactions. Although it has become possible to use femtosecond-pulse electron beam and femtosecond laser light in pulse radiolysis, the resolution is limited by the difference in group velocities of the electrons and the light in sample. In this contribution, we introduce a concept of equivalent velocity spectroscopy (EVS) into pulse radiolysis and demonstrate the methodology experimentally. In EVS, both the electron and the analyzing light pulses precisely overlap at every point in the sample and throughout the propagation time by rotating the electron pulse. The advance allows us to overcome the resolution degradation due to the different group velocity. We also present a method for measuring the rotated angle of the electron pulse and a technique for rotating the electron pulse with a deflecting cavity.

Early experience with multiparametric magnetic resonance imaging-targeted biopsies under visual transrectal ultrasound guidance in patients suspicious for prostate cancer undergoing repeated biopsy

DEFF Research Database (Denmark)

Boesen, Lars; Noergaard, Nis; Chabanova, Elizaveta

2015-01-01

OBJECTIVES: The purpose of this study was to investigate the detection rate of prostate cancer (PCa) by multiparametric magnetic resonance imaging-targeted biopsies (mp-MRI-bx) in patients with prior negative transrectal ultrasound biopsy (TRUS-bx) sessions without previous experience of this......-RADS) and Likert classification. All underwent repeated TRUS-bx (10 cores) and mp-MRI-bx under visual TRUS guidance of any mp-MRI-suspicious lesion not targeted by systematic TRUS-bx. RESULTS: PCa was found in 39 out of 83 patients (47%) and mp-MRI identified at least one lesion with some degree of suspicion...

Coagulation profile in patients undergoing video-assisted thoracoscopic lobectomy

DEFF Research Database (Denmark)

Christensen, Thomas Decker; Vad, Henrik; Pedersen, Søren

2017-01-01

-, and the first two days postoperatively by standard coagulation blood test, thromboelastometry (ROTEM®) and thrombin generation. Results: Patients undergoing potential curative surgery for lung cancer were not hypercoagulable preoperatively. There was no statistically significant difference in the majority......Background: Knowledge about the impact of Low-Molecular-Weight Heparin (LMWH) on the coagulation system in patients undergoing minimal invasive lung cancer surgery is sparse. The aim of this study was to assess the effect of LMWH on the coagulation system in patients undergoing Video......-Assisted Thoracoscopic Surgery (VATS) lobectomy for primary lung cancer. Methods: Sixty-three patients diagnosed with primary lung cancer undergoing VATS lobectomy were randomized to either subcutaneous injection with dalteparin (Fragmin®) 5000 IE once daily or no intervention. Coagulation was assessed pre-, peri...

Ocular surface sensitivity repeatability with Cochet-Bonnet esthesiometer.

Science.gov (United States)

Chao, Cecilia; Stapleton, Fiona; Badarudin, Ezailina; Golebiowski, Blanka

2015-02-01

To determine the repeatability of ocular surface threshold measurements using the Cochet-Bonnet esthesiometer on the same day and 3 months apart. Two separate studies were conducted to determine the repeatability of ocular surface threshold measurements made on the same day (n = 20 subjects) and 3 months apart (n = 29 subjects). The Cochet-Bonnet esthesiometer was used to measure corneal and inferior conjunctival thresholds using the ascending method of limits. The pressure exerted by the Cochet-Bonnet esthesiometer was determined using an analytical balance, for both the 0.08- and 0.12-mm-diameter filaments. This calibration was then used to convert filament length measurements to pressure. Repeatability was determined using a Bland and Altman analysis. The pressure exerted at each filament length differed between the two filament diameters. The measured pressure also differed from values provided by the manufacturer. Repeatability of threshold measurements at the central cornea was shown to be good, with better repeatability for same-day measurements (coefficient of repeatability [CoR] = ±0.23 g/mm²) than for those 3 months apart (CoR = ±0.52 g/mm²). Threshold measurements at the inferior conjunctiva, in contrast, were poorly repeatable (CoR = ±12.78 g/mm²). Cochet-Bonnet esthesiometry is repeatable when performed on the central cornea on the same day and 3 months apart, but this instrument is not recommended for conjunctival threshold measurements.

Safety of Repeated Yttrium-90 Radioembolization

International Nuclear Information System (INIS)

Lam, Marnix G. E. H.; Louie, John D.; Iagaru, Andrei H.; Goris, Michael L.; Sze, Daniel Y.

2013-01-01

Purpose: Repeated radioembolization (RE) treatments carry theoretically higher risk of radiation-induced hepatic injury because of the liver’s cumulative memory of previous exposure. We performed a retrospective safety analysis on patients who underwent repeated RE. Methods: From 2004 to 2011, a total of 247 patients were treated by RE. Eight patients (5 men, 3 women, age range 51–71 years) underwent repeated treatment of a targeted territory, all with resin microspheres (SIR-Spheres; Sirtex, Lane Cove, Australia). Adverse events were graded during a standardized follow-up. In addition, the correlation between the occurrence of RE-induced liver disease (REILD) and multiple variables was investigated in univariate and multivariate analyses in all 247 patients who received RE. Results: Two patients died shortly after the second treatment (at 84 and 107 days) with signs and symptoms of REILD. Both patients underwent whole liver treatment twice (cumulative doses 3.08 and 2.66 GBq). The other 6 patients demonstrated only minor toxicities after receiving cumulative doses ranging from 2.41 to 3.88 GBq. All patients experienced objective tumor responses. In the whole population, multifactorial analysis identified three risk factors associated with REILD: repeated RE (p = 0.036), baseline serum total bilirubin (p = 0.048), and baseline serum aspartate aminotransferase (p = 0.043). Repeated RE proved to be the only independent risk factor for REILD in multivariate analysis (odds ratio 9.6; p = 0.002). Additionally, the administered activity per target volume (in GBq/L) was found to be an independent risk factor for REILD, but only in whole liver treatments (p = 0.033). Conclusion: The risk of REILD appears to be elevated for repeated RE. Objective tumor responses were observed, but establishment of safety limits will require improvement in dosimetric measurement and prediction

Safety of Repeated Yttrium-90 Radioembolization

Energy Technology Data Exchange (ETDEWEB)

Lam, Marnix G. E. H.; Louie, John D. [Stanford University School of Medicine, Division of Interventional Radiology (United States); Iagaru, Andrei H.; Goris, Michael L. [Stanford University School of Medicine, Division of Nuclear Medicine (United States); Sze, Daniel Y., E-mail: dansze@stanford.edu [Stanford University School of Medicine, Division of Interventional Radiology (United States)

2013-10-15

Purpose: Repeated radioembolization (RE) treatments carry theoretically higher risk of radiation-induced hepatic injury because of the liver's cumulative memory of previous exposure. We performed a retrospective safety analysis on patients who underwent repeated RE. Methods: From 2004 to 2011, a total of 247 patients were treated by RE. Eight patients (5 men, 3 women, age range 51-71 years) underwent repeated treatment of a targeted territory, all with resin microspheres (SIR-Spheres; Sirtex, Lane Cove, Australia). Adverse events were graded during a standardized follow-up. In addition, the correlation between the occurrence of RE-induced liver disease (REILD) and multiple variables was investigated in univariate and multivariate analyses in all 247 patients who received RE. Results: Two patients died shortly after the second treatment (at 84 and 107 days) with signs and symptoms of REILD. Both patients underwent whole liver treatment twice (cumulative doses 3.08 and 2.66 GBq). The other 6 patients demonstrated only minor toxicities after receiving cumulative doses ranging from 2.41 to 3.88 GBq. All patients experienced objective tumor responses. In the whole population, multifactorial analysis identified three risk factors associated with REILD: repeated RE (p = 0.036), baseline serum total bilirubin (p = 0.048), and baseline serum aspartate aminotransferase (p = 0.043). Repeated RE proved to be the only independent risk factor for REILD in multivariate analysis (odds ratio 9.6; p = 0.002). Additionally, the administered activity per target volume (in GBq/L) was found to be an independent risk factor for REILD, but only in whole liver treatments (p = 0.033). Conclusion: The risk of REILD appears to be elevated for repeated RE. Objective tumor responses were observed, but establishment of safety limits will require improvement in dosimetric measurement and prediction.

Custom pulse generator for RPC testing

International Nuclear Information System (INIS)

Gil, A.; Castro, E.; Diaz, J.; Fonte, P.; Garzon, J.A.; Montes, N.; Zapata, M.

2009-01-01

We present a pulse generator able to generate pulses statistically similar to the ones produced by RPC cells. The device generates up to four arrays of fast and narrow random-like pulses. Polarity, maximum amplitudes, widths and pulse rate in each channel may be modified independently in order to simulate different RPC setups and environments. This portable and cost-effective pulse generator is a versatile instrument for testing FE-Electronics and different real detector features related with the signal propagation inside the detector. It has been developed in the framework of the ESTRELA project of the HADES experiment at GSI.

Temporal Airy pulses control cell poration

Directory of Open Access Journals (Sweden)

S. Courvoisier

2016-07-01

Full Text Available We show that spectral phase shaping of fs-laser pulses can be used to optimize laser-cell membrane interactions in water environment. The energy and peak intensity thresholds required for cell poration with single pulse in the nJ range can be significantly reduced (25% reduction in energy and 88% reduction in peak intensity by using temporal Airy pulses, controlled by positive third order dispersion, as compared to bandwidth limited pulses. Temporal Airy pulses are also effective to control the morphology of the induced pores, with prospective applications from cellular to tissue opto-surgery and transfection.

Infrared study of the Crab pulsar: The ''shoulder'' pulse and the 3.45 micron pulse profile

International Nuclear Information System (INIS)

Middleditch, J.; Pennypacker, C.; Burns, M.S.

1983-01-01

Infrared measurements of the Crab pulsar with the NASA IRTF 3.0 m telescope show that the spectrum of the main pulse turns downward for wavelengths longer than 3 μm. The ''shoulder'' pulse discovered by Pennypacker is measured in the 0.9--2.4 μm region, but disappears at 3.5 μm. This pulse rises from 0 to 20% of the height of the main pulse within 1 to 2 ms after the main pulse peak and decays with a 4 to 5 ms time constant. Excess infrared flux also appears after the interpulse. The main peak itself may be narrower at 3.45 μm than in the optical to 2.2 μm band

Control of giant pulse duration in neodymium mini lasers with controllable cavity length and pulsed pumping

International Nuclear Information System (INIS)

Berenberg, Vladimir A.; Cervantes, Miguel A.; Terpugov, Vladimir S.

2006-01-01

In a solid-state laser incident on aLiNdP4O12 crystal, pumped by a short light pulse, giant pulse oscillation without the use of resonator Q switching is realized. Tuning of the oscillation pulse duration from 2 up to 20 ns is achieved by changing the cavity length from 24 to 3 mm, respectively. Our analysis of this mode of laser radiation is made on the basis of the rate equations. The factors influencing oscillation pulse duration a reinvestigated. It is shown that in a limiting case the minimal value of the pulse duration is limited by only the rate of excitation transfer from the pumping band to the metastable level

Laser system using ultra-short laser pulses

Science.gov (United States)

Dantus, Marcos [Okemos, MI; Lozovoy, Vadim V [Okemos, MI; Comstock, Matthew [Milford, MI

2009-10-27

A laser system using ultrashort laser pulses is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and binary pulse shaping (BPS). Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal.

Granulocyte colony-stimulating factor in repeated IVF failure, a randomized trial.

Science.gov (United States)

Aleyasin, Ashraf; Abediasl, Zhila; Nazari, Atefeh; Sheikh, Mahdi

2016-06-01

Recent studies have revealed key roles for granulocyte colony-stimulating factor (GCSF) in embryo implantation process and maintenance of pregnancy, and some studies showed promising results by using local intrauterine infusion of GCSF in patients undergoing in vitro fertilization (IVF). This multicenter, randomized, controlled trial included 112 infertile women with repeated IVF failure to evaluate the efficacy of systemic single-dose subcutaneous GCSF administration on IVF success in these women. In this study, the Long Protocol of ovarian stimulation was used for all participants. Sealed, numbered envelopes assigned 56 patients to receive subcutaneous 300 µg GCSF before implantation and 56 in the control group. The implantation (number of gestational sacs on the total number of transferred embryos), chemical pregnancy (positive serum β-HCG), and clinical pregnancy (gestational sac and fetal heart) rates were compared between the two groups. This trial is registered at www.irct.ir (IRCT201503119568N11). The successful implantation (18% vs 7.2%, P=0.007), chemical pregnancy (44.6% vs 19.6%, P=0.005), and clinical pregnancy (37.5% vs 14.3%, P=0.005) rates were significantly higher in the intervention group than in the control group. After adjustment for participants' age, endometrial thickness, good-quality oocyte counts, number of transferred embryos, and anti-Mullerian hormone levels, GCSF treatment remained significantly associated with successful implantation (OR=2.63, 95% CI=1.09-6.96), having chemical pregnancy (OR= 2.74, 95% CI=1.11-7.38) and clinical pregnancy (OR=2.94, 95% CI=1.23-8.33). In conclusion, administration of single-dose systemic subcutaneous GCSF before implantation significantly increases the IVF success, implantation, and pregnancy rates in infertile women with repeated IVF failure. © 2016 Society for Reproduction and Fertility.

Dental Fear in Children with Repeated Tooth Injuries.

Science.gov (United States)

Negovetić Vranić, Dubravka; Ivančić Jokić, Nataša; Bakarčić, Danko; Carek, Andreja; Rotim, Željko; Verzak, Željko

2016-06-01

Tooth injuries are serious clinical conditions. Some children experience dental trauma only once, while others are more prone to repeated tooth injuries. Repeated dental trauma occurs in 19.4% to 30% of patients. Pain and dental trauma are the most common reasons for fear and anxiety. The main objective of this study was to investigate how dental trauma, as well as repeated dental trauma affects the occurrence and development of dental fear in children. The study was conducted on a random sample of 147 subjects (88 boys and 59 girls) aged 5-8 and 9-12 years. Subjects in both age groups were divided into subroups without dental trauma, with one dental trauma and with repeated dental trauma. The validated Children’s Fear Survey Schedule – Dental Subscale was used on fear assessment. Results showed that only 12.2% of children without trauma, 33.3% with one trauma and 51.7% with repeated trauma were not afraid of injection. Older children had a significantly lower fear of injections, touch of an unknown person, choking, going to the hospital and people in white uniforms. Dentist was not the cause of fear in 65.5% of patients with repeated trauma. With each repeated injury of teeth, the degree of their fear of dental treatment was lower.

Erroneous Memories Arising from Repeated Attempts to Remember

Science.gov (United States)

Henkel, Linda A.

2004-01-01

The impact of repeated and prolonged attempts at remembering on false memory rates was assessed in three experiments. Participants saw and imagined pictures and then made repeated recall attempts before taking a source memory test. Although the number of items recalled increased with repeated tests, the net gains were associated with more source…

Noninvasive investigation of exocrine pancreatic function: Feasibility of cine dynamic MRCP with a spatially selective inversion-recovery pulse.

Science.gov (United States)

Yasokawa, Kazuya; Ito, Katsuyoshi; Tamada, Tsutomu; Yamamoto, Akira; Hayashida, Minoru; Tanimoto, Daigo; Higaki, Atsushi; Noda, Yasufumi; Kido, Ayumu

2015-11-01

To investigate the feasibility of noncontrast-enhanced cine dynamic magnetic resonance cholangiopancreatography (MRCP) with a spatially selective inversion-recovery (IR) pulse for evaluating exocrine pancreatic function in comparison with the N-benzoyl-L-tyrosyl-p-aminobenzoic acid (BT-PABA) test as a pancreatic exocrine function test. Twenty subjects with or without chronic pancreatitis were included. MRCP with a spatially selective IR pulse was repeated every 15 seconds for 5 minutes to acquire a total of 20 images (cine-dynamic MRCP). The median and mean frequency of the observation (the number of times) and the moving distance (mean secretion grading scores) of pancreatic juice inflow on cine-dynamic MRCP were compared with a BT-PABA test. The urinary PABA excretion rate (%) had significant positive correlations with both the mean secretion grade (r = 0.66, P = 0.002) and frequency of secretory inflow (r = 0.62, P = 0.004) in cine dynamic MRCP. Both the mean frequency of observations of pancreatic secretory inflow (1.4 ± 1.6 times vs. 14.3 ± 4.2 times, P Cine dynamic MRCP with a spatially selective IR pulse may have potential for estimating the pancreatic exocrine function noninvasively as a substitute for the BT-PABA test. © 2015 Wiley Periodicals, Inc.

Picoseconds pulse generation and pulse width determination processes of a distributed feedback dye laser

International Nuclear Information System (INIS)

Abdul Ghani, B.; Hammadi, M.

2004-08-01

A mathematical model has been developed to describe the dynamic emission of Nd-glass, distributed feedback dye laser (DFDL), and periodical grating temperature. The suggested model allows the investigation of the time behavior of Nd-glass laser and DFDL pulsed. Moreover, it allows studying the effect of the laser input parameters of Nd-glass laser on the spectral characteristics of the output DFDL pulses such as pulse width, delay time, and time separation

Pulsed Light Accelerated Crosslinking versus Continuous Light Accelerated Crosslinking: One-Year Results

Directory of Open Access Journals (Sweden)

Cosimo Mazzotta

2014-01-01

Full Text Available Purpose. To compare functional results in two cohorts of patients undergoing epithelium-off pulsed (pl-ACXL and continuous light accelerated corneal collagen crosslinking (cl-ACXL with dextran-free riboflavin solution and high-fluence ultraviolet A irradiation. Design. It is a prospective, comparative, and interventional clinical study. Methods. 20 patients affected by progressive keratoconus were enrolled in the study. 10 eyes of 10 patients underwent an epithelium-off pl-ACXL by the KXL UV-A source (Avedro Inc., Waltham, MS, USA with 8 minutes (1 sec. on/1 sec. off of UV-A exposure at 30 mW/cm2 and energy dose of 7.2 J/cm2; 10 eyes of 10 patients underwent an epithelium-off cl-ACXL at 30 mW/cm2 for 4 minutes. Riboflavin 0.1% dextran-free solution was used for a 10-minutes corneal soaking. Patients underwent clinical examination of uncorrected distance visual acuity and corrected distance visual acuity (UDVA and CDVA, corneal topography and aberrometry (CSO EyeTop, Florence, Italy, corneal OCT optical pachymetry (Cirrus OCT, Zeiss Meditec, Jena, Germany, endothelial cells count (I-Conan Non Co Robot, and in vivo scanning laser confocal microscopy (Heidelberg, Germany at 1, 3, 6, and 12 months of follow-up. Results. Functional results one year after cl-ACXL and pl-ACXL demonstrated keratoconus stability in both groups. Functional outcomes were found to be better in epithelium-off pulsed light accelerated treatment together with showing a deeper stromal penetration. No endothelial damage was recorded during the follow-up in both groups. Conclusions. The study confirmed that oxygen represents the main driver of collagen crosslinking reaction. Pulsed light treatment optimized intraoperative oxygen availability improving postoperative functional outcomes compared with continuous light treatment.

A Novel Transcranial Magnetic Stimulator Inducing Near Rectangular Pulses with Controllable Pulse Width (cTMS)

Science.gov (United States)

Jalinous, Reza; Lisanby, Sarah H.

2013-01-01

A novel transcranial magnetic stimulation (TMS) device with controllable pulse width (PW) and near rectangular pulse shape (cTMS) is described. The cTMS device uses an insulated gate bipolar transistor (IGBT) with appropriate snubbers to switch coil currents up to 7 kA, enabling PW control from 5 μs to over 100 μs. The near-rectangular induced electric field pulses use 22–34% less energy and generate 67–72% less coil heating compared to matched conventional cosine pulses. CTMS is used to stimulate rhesus monkey motor cortex in vivo with PWs of 20 to 100 μs, demonstrating the expected decrease of threshold pulse amplitude with increasing PW. The technological solutions used in the cTMS prototype can expand functionality, and reduce power consumption and coil heating in TMS, enhancing its research and therapeutic applications. PMID:18232369

Comparative efficacy of continuous and pulse dose terbinafine regimes in toenail dermatophytosis: A randomized double-blind trial.

Science.gov (United States)

Yadav, Pravesh; Singal, Archana; Pandhi, Deepika; Das, Shukla

2015-01-01

Dermatophytes are the most frequently implicated agents in toenail onychomycosis and oral terbinafine has shown the best cure rates in this condition. The pharmacokinetics of terbinafine favors its efficacy in pulse dosing. To compare the efficacy of terbinafine in continuous and pulse dosing schedules in the treatment of toenail dermatophytosis. Seventy-six patients of potassium hydroxide (KOH) and culture positive dermatophyte toenail onychomycosis were randomly allocated to two treatment groups receiving either continuous terbinafine 250 mg daily for 12 weeks or 3 pulses of terbinafine (each of 500 mg daily for a week) repeated every 4 weeks. Patients were followed up at 4, 8 and 12 weeks during treatment and post-treatment at 24 weeks. At each visit, a KOH mount and culture were performed. In each patient, improvement in a target nail was assessed using a clinical score; total scores for all nails and global assessments by physician and patient were also recorded. Mycological, clinical and complete cure rates, clinical effectivity and treatment failure rates were then compared. The declines in target nail and total scores from baseline were significant at each follow-up visit in both the treatment groups. However, the inter-group difference was statistically insignificant. The same was true for global assessment indices, clinical effectivity as well as clinical, mycological, and complete cure rates. The short follow-up in our study may have led to lower cure rates being recorded. Terbinafine in pulse dosing is as effective as continuous dosing in the treatment of dermatophyte toenail onychomycosis.

Theoretical and Experimental Investigations of Coincidences in Poisson Distributed Pulse Trains and Spectral Distortion Caused by Pulse Pileup.

Science.gov (United States)

Bristow, Quentin

1990-01-01

Part one of this two-part study is concerned with the multiple coincidences in pulse trains from X-ray and gamma radiation detectors which are the cause of pulse pileup. A sequence of pulses with inter-arrival times less than tau, the resolving time of the pulse-height analysis system used to acquire spectra, is called a multiple pulse string. Such strings can be classified on the basis of the number of pulses they contain, or the number of resolving times they cover. The occurrence rates of such strings are derived from theoretical considerations. Logic circuits were devised to make experimental measurements of multiple pulse string occurrence rates in the output from a NaI(Tl) scintillation detector over a wide range of count rates. Markov process theory was used to predict state transition rates in the logic circuits, enabling the experimental data to be checked rigorously for conformity with those predicted for a Poisson distribution. No fundamental discrepancies were observed. Part two of the study is concerned with a theoretical analysis of pulse pileup and the development of a discrete correction algorithm, based on the use of a function to simulate the coincidence spectrum produced by partial sums of pulses. Monte Carlo simulations, incorporating criteria for pulse pileup inherent in the operation of modern ADC's, were used to generate pileup spectra due to coincidences between two pulses, (1st order pileup) and three pulses (2nd order pileup), for different semi-Gaussian pulse shapes. Coincidences between pulses in a single channel produced a basic probability density function spectrum which can be regarded as an impulse response for a particular pulse shape. The use of a flat spectrum (identical count rates in all channels) in the simulations, and in a parallel theoretical analysis, showed the 1st order pileup distorted the spectrum to a linear ramp with a pileup tail. The correction algorithm was successfully applied to correct entire spectra for 1st and