Spontaneous emission from saturated parametric amplifiers
DEFF Research Database (Denmark)
Rottwitt, Karsten; Ott, Johan Raunkjær; Steffensen, Henrik
2009-01-01
Noise performance of parametric amplifiers is typically calculated assuming un-depleted operation. However, in many applications especially when applied as regenerative amplifiers in systems based on phase shift keyed modulation schemes, this assumption is not valid. Here we show the impact...... on accumulated spontaneous emission for a parametric amplifier operated in saturation....
FEL gain optimisation and spontaneous radiation
Energy Technology Data Exchange (ETDEWEB)
Bali, L.M.; Srivastava, A.; Pandya, T.P. [Lucknow Univ. (India)] [and others
1995-12-31
Colson have evaluated FEL gains for small deviations from perfect electron beam injection, with radiation of the same polarisation as that of the wiggler fields. We find that for optimum gain the polarisation of the optical field should be the same as that of the spontaneous emission under these conditions. With a helical wiggler the axial oscillations resulting from small departures from perfect electron beam injection lead to injection dependent unequal amplitudes and phases of the spontaneous radiation in the two transverse directions. Viewed along the axis therefore the spontaneous emission is elliptically polarised. The azimuth of the ellipse varies with the difference of phase of the two transverse components of spontaneous emission but the eccentricity remains the same. With planar wigglers the spontaneous emission viewed in the axial direction is linearly polarised, again with an injection dependent azimuth. For optimum coherent gain of a radiation field its polarisation characteristics must be the same as those of the spontaneous radiation with both types of wiggler. Thus, with a helical wiggler and the data reported earlier, an increase of 10% in the FEL gain at the fundamental frequency and of 11% at the fifth harmonic has been calculated in the small gain per pass limit. Larger enhancements in gain may result from more favourable values of input parameters.
Surface spontaneous parametric down-conversion
Czech Academy of Sciences Publication Activity Database
Peřina ml., Jan; Lukš, A.; Haderka, Ondřej
2009-01-01
Roč. 103, č. 6 (2009), 063902/1-063902/4 ISSN 0031-9007 R&D Projects: GA MŠk(CZ) 1M06002 Institutional research plan: CEZ:AV0Z10100522 Keywords : parametric down-conversion * surface Subject RIV: BH - Optics, Masers, Lasers Impact factor: 7.328, year: 2009
On the unlimited gain of a nonlinear parametric amplifier
DEFF Research Database (Denmark)
Sorokin, Vladislav
2014-01-01
The present paper is concerned with analysis of the response of a nonlinear parametric amplifier in abroad range of system parameters, particularly beyond resonance. Such analysis is of particular interestfor micro- and nanosystems, since many small-scale parametric amplifiers exhibit a distinctly...... nonlinearbehavior when amplitude of their response is sufficiently large. The modified method of direct separa-tion of motions is employed to study the considered system. As the result it is obtained that steady-stateamplitude of the nonlinear parametric amplifier response can reach large values in the case...... of arbitrarilysmall amplitude of external excitation, so that the amplifier gain tends to infinity. Very large amplifiergain can be achieved in a broad range of system parameters, in particular when the amplitude of para-metric excitation is comparatively small. The obtained results clearly demonstrate that very...
Towards spontaneous parametric down-conversion at low temperatures
Directory of Open Access Journals (Sweden)
Akatiev Dmitrii
2017-01-01
Full Text Available The possibility of observing spontaneous parametric down-conversion in doped nonlinear crystals at low temperatures, which would be useful for combining heralded single-photon sources and quantum memories, is studied theoretically. The ordinary refractive index of a lithium niobate crystal doped with magnesium oxide LiNbO3:MgO is measured at liquid nitrogen and helium temperatures. On the basis of the experimental data, the coefficients of the Sellmeier equation are determined for the temperatures from 5 to 300 K. In addition, a poling period of the nonlinear crystal has been calculated for observing type-0 spontaneous parametric down-conversion (ooo-synchronism at the liquid helium temperature under pumping at the wavelength of λp = 532 nm and emission of the signal field at the wavelength of λs = 794 nm, which corresponds to the resonant absorption line of Tm3+ doped ions.
Asymmetric gain-saturated spectrum in fiber optical parametric amplifiers
DEFF Research Database (Denmark)
Lali-Dastjerdi, Zohreh; Rottwitt, Karsten; Galili, Michael
2012-01-01
We demonstrate experimentally and numerically an unexpected spectral asymmetry in the saturated-gain spectrum of single-pump fiber optical parametric amplifiers. The interaction between higher-order four-wave mixing products and dispersive waves radiated as an effect of third-order dispersion...
Spontaneous indices are inconsistent with arterial baroreflex gain.
Lipman, Ruth D; Salisbury, Julie K; Taylor, J Andrew
2003-10-01
Spontaneously occurring, parallel fluctuations in arterial pressure and heart period are frequently used as indices of baroreflex function. Despite the convenience of spontaneous indices, their relation to the arterial baroreflex remains unclear. Therefore, in 97 volunteers, we derived 5 proposed indices (sequence method, alpha-index, transfer function, low-frequency transfer function, and impulse response function), compared them with arterial baroreflex gain (by the modified Oxford pharmacologic technique), and examined their relation to carotid distensibility and respiratory sinus arrhythmia. The subjects comprised men and women (n=41) aged 25 to 86 years, 30% of whom had established coronary artery disease. Generally, the indices were correlated with each other (except alpha-index and low-frequency transfer function) and with baroreflex gain. However, the Bland-Altman method demonstrated that the spontaneous indices had limits of agreement as large as the baroreflex gain itself. Even in individuals within the lowest tertile of baroreflex gain for whom baroreflex gain appears to be the most clinically relevant, spontaneous indices failed to relate to baroreflex gain. In fact, for these individuals, there was no correlation between any index and baroreflex gain. Forward stepwise linear regression showed that all spontaneous indices and baroreflex gain were related to respiratory sinus arrhythmia, but only baroreflex gain was related to carotid distensibility. Therefore, these data suggest that spontaneous indices are inadequate estimates of gain and are inconsistent with arterial baroreflex function.
Quality of polarization entanglement in spontaneous parametric down conversion
Directory of Open Access Journals (Sweden)
Ali N
2017-01-01
Full Text Available We experimentally demonstrated a high degree of polarization entanglement known as entanglement visibility through spontaneous parametric down conversion process pumped by a femtosecond laser. The entangled-photon pair was obtained using two type-I BBO crystal. The down-converted photons from these crystals demonstrates a high visibility of 98.7% (θ2 = 0° and 90% (θ2 = 22.5°. These results are in agreement with the theory which expects high visibility from such arrangement.
Cao, De-Zhong; Li, Zhuan; Zhai, Yan-Hua; Wang, Kaige
2004-01-01
We theoretically discuss one-photon and two-photon double-slit interferences for spontaneous and stimulated parametric down-conversions. We show that the two-photon sub-wavelength interference can exist in a general spontaneous parametric down-conversion (SPDC) for both type I and type II crystals. We propose an alternative way to observe sub-wavelength interference by a joint-intensity measurement which occurs for only type I crystal in a higher gain of SPDC. When a signal beam injects into ...
Spontaneous physical activity protects against fat mass gain.
Teske, J A; Billington, C J; Kuskowski, M A; Kotz, C M
2012-04-01
It is unclear whether elevated spontaneous physical activity (SPA, very low-intensity physical activity) positively influences body composition long term. We determined whether SPA and caloric intake were differentially related to the growth curve trajectories of body weight, fat mass (FM) and fat-free mass (FFM) between obesity resistant and Sprague-Dawley rats at specific age intervals. Body composition, SPA and caloric intake were measured in selectively-bred obesity-resistant and out-bred Sprague-Dawley rats from 1 to 18 months. Data from development throughout maturation were analyzed by longitudinal growth curve modeling to determine the rate and acceleration of body weight, FM- and FFM-gain. Obesity-resistant rats had a lower rate of FM gain overall, a lower acceleration in body weight early in life, significantly greater SPA and lower cumulative caloric intake. Greater SPA in obesity-resistant rats was significantly associated with a lower rate of FM gain overall and lower acceleration in body weight early in life. Obesity resistant rats lost less FFM compared with Sprague-Dawley rats despite that obesity-resistant rats had a lower acceleration in FFM gain early in life. Obesity-resistant rats gained less FM and more FFM per gram body weight and were less energy efficient than Sprague-Dawley rats. Caloric intake was significantly and positively related to body weight, FM and FFM gain in both groups. Circadian patterns of caloric intake were group and age-dependent. Our data demonstrate that elevated and sustained SPA during development and over the lifespan are related to the reduced the rate of FM gain and may preserve FFM. These data support the idea that SPA level is a reproducible marker that reliably predicts propensity for obesity in rats, and that elevated levels of SPA maintained during the lifespan promote a lean phenotype.
Gain characteristics of a saturated fiber optic parametric amplifier
DEFF Research Database (Denmark)
Rottwitt, Karsten; Lorenzen, Michael Rodas; Noordegraaf, Danny
2008-01-01
In this work we discuss saturation performance of a fiber optic parametric amplifier. A simple numerical model is described and applied to specific cases. A system experiment using a saturated amplifier illustrates a 4 dB improvement in required signal to noise ratio for a fixed bit error ratio....
Jumps and bi-stability in the phase-gain characteristics of a nonlinear parametric amplifier
DEFF Research Database (Denmark)
Neumeyer, Stefan; van de Looij, Ruud; Thomsen, Jon Juel
2014-01-01
This work experimentally investigates the impact of nonlinearity on macromechanical parametric amplification. For a strong cubic stiffness nonlinearity we observe jumps in gain (ratio of steady-state vibration amplitude of the externally and parametrically excited system, to vibration amplitude o...
Numerical Modelling of Spontaneous Emission in Optical Parametric Amplifiers
DEFF Research Database (Denmark)
Friis, Søren Michael Mørk; Andersen, Ulrik Lund; Rottwitt, Karsten
2013-01-01
Fiber optical parametric processes offer a wide range of applications including phase sensitive as well as phase insensitive amplification, wavelength conversion and signal regeneration. One of the difficult challenges is any of these applications is to predict their associated noise performance...
Terahertz parametric gain in semiconductor superlattices in the absence of electric domains
Hyart, Timo; Alexeeva, Natalia V.; Leppänen, Ahti; Alekseev, Kirill N.
2006-09-01
The authors theoretically show that conditions for terahertz gain and conditions for formation of destructive electric domains in semiconductor superlattices are fairly different in the case of parametric generation and amplification. Action of an unbiased high-frequency electric field on a superlattice causes a periodic variation of energy and effective mass of miniband electrons. This parametric effect can result in a significant gain at some even harmonic of the pump frequency without the formation of electric domains and corruption from pump harmonics.
Modal spectrum in spontaneous parametric down-conversion with noncollinear phase matching
CSIR Research Space (South Africa)
Zhang, Y
2014-06-01
Full Text Available We investigate the effect of the down-conversion angle between the signal and idler beams in spontaneous parametric down-conversion on the bandwidth of the modal spectrum (Schmidt number) of the down-converted quantum state. For this purpose, we...
Simulating spontaneous parametric down-conversion using classical light: Conference paper
CSIR Research Space (South Africa)
Zhang, Y
2014-08-01
Full Text Available of SPIE Volume 9194, Laser Beam Shaping XV, San Diego USA, August 2014 Simulating spontaneous parametric down-conversion using classical light Yingwen Zhanga, Melanie McLarena,b, Filippus S. Rouxa and Andrew Forbesa,b aCSIR National Laser Centre...
DEFF Research Database (Denmark)
Avenhaus, M.; Chekhova, M. V.; Krivitsky, Leonid
2009-01-01
We study the spectral properties of spontaneous parametric down-conversion (SPDC) in a periodically poled waveguided structure of potassium-titanyl-phosphate (KTP) crystal pumped by ultrashort pulses. Our theoretical analysis reveals a strongly entangled and asymmetric structure of the two...
Impact of Gain Saturation on the Parametric Amplification of 16-QAM Signals
DEFF Research Database (Denmark)
Da Ros, Francesco; Borkowski, Robert; Zibar, Darko
2012-01-01
The effect of gain saturation on parametric amplification of 16-QAM signals is investigated in terms of signal distortion. The relative impact of gain saturation, nonlinear phase rotation and nonlinear phase noise is discussed. Experimental results at 14 GBd confirm the conclusions of the numerical...
International Nuclear Information System (INIS)
Penin, A.N.; Reutova, T.A.; Sergienko, A.V.
1992-01-01
An experiment on one-photon state localization in space using a correlation technique in Spontaneous Parametric Down Conversion (SPDC) process is discussed. Results of measurements demonstrate an idea of the Einstein-Podolsky-Rosen (EPR) paradox for coordinate and momentum variables of photon states. Results of the experiment can be explained with the help of an advanced wave technique. The experiment is based on the idea that two-photon states of optical electromagnetic fields arising in the nonlinear process of the spontaneous parametric down conversion (spontaneous parametric light scattering) can be explained by quantum mechanical theory with the help of a single wave function
MOSFET-Only Mixer/IIR Filter with Gain using Parametric Amplification
DEFF Research Database (Denmark)
Custódio, José R.; Oliveira, J.; Oliveira, L. B.
2010-01-01
This paper describes the design of a discrete-time passive Mixer/IIR filter. The use of an improved MOS Parametric Amplification leads to a moderate gain in the signal path and improved noise performance, instead of the conversion loss inherent to passive mixers. Simulation results demonstrate that...
Angular spectrum characters of high gain non-critical phase match optical parametric oscillators
International Nuclear Information System (INIS)
Liu Jian-Hui; Liu Qiang; Gong Ma-Li
2011-01-01
The angular spectrum gain characters and the power magnification characters of high gain non-walk-off colinear optical parametric oscillators have been studied using the non-colinear phase match method for the first time. The experimental results of the KTiOAsO 4 and the KTiOPO 4 crystals are discussed in detail. At the high energy single resonant condition, low reflective ratio of the output mirror for the signal and long non-linear crystal are beneficial for small divergence angles. This method can also be used for other high gain non-walk-off phase match optical parametric processes. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Spontaneous physical activity protects against fat mass gain
Teske, Jennifer A.; Billington, Charles J.; Kuskowski, Michael A.; Kotz, Catherine M.
2011-01-01
It is unclear whether elevated spontaneous physical activity (SPA, very low-intensity physical activity) positively influences body composition long-term. Objective We determined whether SPA and caloric intake were differentially related to the growth curve trajectories of body weight, FM and FFM between obesity resistant and Sprague-Dawley rats at specific age intervals. Design and Subjects Body composition, SPA and caloric intake were measured in selectively-bred obesity resistant and out-b...
International Nuclear Information System (INIS)
Wang Hanchao; Huang Lirong; Shi Zhongwei
2011-01-01
A two-electrode multi-quantum-well semiconductor optical amplifier is designed and fabricated. The amplified spontaneous emission (ASE) spectrum and gain were measured and analyzed. It is shown that the ASE spectrum and gain characteristic are greatly influencedby the distribution of the injection current density. By changing the injection current density of two electrodes, the full width at half maximum, peak wavelength, peak power of the ASE spectrum and the gain characteristic can be easily controlled. (semiconductor devices)
Czech Academy of Sciences Publication Activity Database
Centini, M.; Peřina ml., Jan; Sciscione, L.; Sibilia, C.; Scalora, M.; Bloemer, M.J.; Bertolotti, M.
2005-01-01
Roč. 72, 03 (2005), 033806/1-033806/11 ISSN 1050-2947 R&D Projects: GA MŠk(CZ) OC P11.003 Institutional research plan: CEZ:AV0Z10100522 Keywords : photon pair * photonic crystals * spontaneous parametric down-conversion Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.997, year: 2005
Czech Academy of Sciences Publication Activity Database
Javůrek, D.; Peřina ml., Jan
2017-01-01
Roč. 95, č. 4 (2017), s. 1-13, č. článku 043828. ISSN 2469-9926 Institutional support: RVO:68378271 Keywords : surface spontaneous * parametric down-conversion * photon pairs * layered media Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 2.925, year: 2016
Czech Academy of Sciences Publication Activity Database
Javůrek, D.; Svozilík, J.; Peřina ml., Jan
2014-01-01
Roč. 90, č. 4 (2014), "043844-1"-"043844-12" ISSN 1050-2947 R&D Projects: GA ČR GAP205/12/0382 Institutional support: RVO:68378271 Keywords : photon pairs * orbital-angular-momentum-entangled * nonlinear ring fiber * spontaneous parametric down-conversion Subject RIV: BH - Optics , Masers, Lasers Impact factor: 2.808, year: 2014
Model-based estimation of loop gain using spontaneous breathing: A validation study
Gederi, Elnaz; Nemati, Shamim; Edwards, Bradley A.; Clifford, Gari D.; Malhotra, Atul; Wellman, Andrew
2014-01-01
Non-invasive assessment of ventilatory control stability or loop gain (which is a key contributor in a number of sleep-related breathing disorders) has proven to be cumbersome. We present a novel multivariate autoregressive model that we hypothesize will enable us to make time-varying measurements of loop gain using nothing more than spontaneous fluctuations in ventilation and CO2. The model is adaptive to changes in the feedback control loop and therefore can account for system non-stationarities (e.g. changes in sleep state) and it is resistant to artifacts by using a signal quality measure. We tested this method by assessing its ability to detect a known increase in loop gain induced by proportional assist ventilation (PAV). Subjects were studied during sleep while breathing on continuous positive airway pressure (CPAP) alone (to stabilize the airway) or on CPAP + PAV. We show that the method tracked the PAV-induced increase in loop gain, demonstrating its time-varying capabilities, and it remained accurate in the face of measurement related artifacts. The model was able to detect a statistically significant increase in loop gain from 0.14 ± 10 on CPAP alone to 0.21 ± 0.13 on CPAP + PAV (p PAV-induced increase in loop gain was predominantly driven by an increase in controller gain. Taken together, these data provide compelling evidence for the validity of this technique. PMID:25038522
Cao, Jingming; Xiaver, Jolly
2017-10-01
We manipulated the simulation and apparatus to generate the entangled quantum photons by the enhanced higher quality factor in waveguide of whispering gallery mode resonator in silica microsphere. As the several nonlinear optics effects have been validated in micro-disk (lithium niobate materials based), others micro-cavity (microfiber and micro ring on the chip) and second harmonic generation (SHG) on the surface of silica microsphere because of the characterization of enhanced higher quality factor Q and smaller volume mode in these resonator. However until now for the second third nonlinearity of spontaneous parametric down conversion (SPDC), third order nonlinearity of spontaneous parametric down conversion (TOSPDC) and spontaneous four wave mixing (SFWM) in whispering gallery mode (WGM) resonator of silica microsphere rarely have not been fully investigated and verified to generate the triple and pair entangled photons where are widely applied on the applications of biosensor, quantum communications and spectroscopy, respectively. Specially, the features of silica microsphere have attracted many applications due to the simple fabrication, simplified materials melted by silica fiber. The work we demonstrated in this paper based on the breaking of the dispersion rules to make perfect phase matching in normal dispersion in silica microsphere depending on the blue laser spectrum in visible spectrum, then manipulated the modified size of microsphere to detune the pump laser of free spectral range (FSR) and both shift the geometrical dispersion are characterized in the variation of FSR given by (see PDF for equation), where n is refractive index, R is the microspheres radius and m is mode numbers in resonator, to compensate the materials dispersion given by (see PDF for equation), where c is the speed of light and λ is pump laser wavelength to fulfill the perfect phase matching in parametric down conversion regimes and the modeling fabrication coupling results also
Spontaneous emission high-gain harmonic generation free-electron laser
Xing, Qingzi; Xu, Xinlu; Feng, Chao; Tang, Chuanxiang
2011-05-01
A scheme, spontaneous emission high-gain harmonic generation (SEHG) free-electron laser (FEL), is proposed and analyzed for generating the X-ray FEL. The SEHG scheme works in a similar mechanism as high-gain harmonic generation (HGHG), but without the need for a seed laser. The scheme requires two undulators. The 1st undulator must be sufficiently long so that the energies of electrons are modulated within the bunch, but still away from saturation. A dispersion section is followed to transfer energy modulation into density modulation. The 2nd undulator simply serves as a radiator. A simple, one-dimensional, analytical estimation of SEHG is given to show the process of energy modulation and optimize the system parameters. The three-dimensional FEL simulation code, GENESIS, has been used to simulate, verify, and optimize the SEHG scheme for the soft X-ray free-electron laser (SXFEL) project in China. The simulation results are presented in comparison with the self-amplified spontaneous emission (SASE) and HGHG schemes. At 9 nm radiation wavelength, up to 120 MW of output power can be achieved by the SEHG scheme, with a total length of 47.3 m long undulators. Though the undulator length is comparable with the SASE scheme, the output bandwidth of the SEHG scheme is smaller. Moreover, it is tunable and does not require a seed laser. The SEHG scheme offers an attractive alternative option for the X-ray FEL.
Arzani, Francesco; Fabre, Claude; Treps, Nicolas
2018-03-01
We study the quantum correlations induced by spontaneous parametric down-conversion of a frequency comb. We derive a theoretical method to find the output state corresponding to a pump with an arbitrary spectral profile. After applying it to the relevant example of a spectrally chirped pump, we run an optimization algorithm to numerically find the pump profiles maximizing some target functions. These include the number of independently squeezed modes and the variances of nullifiers defining cluster states used in many continuous-variable quantum information protocols. To assess the advantages of pump shaping in real experiments, we take into account the physical limitations of the pulse shaper.
International Nuclear Information System (INIS)
Maji, Partha Sona; Roy Chaudhuri, Partha
2016-01-01
In this article, we have presented a new design methodology of obtaining wide band parametric sources based on highly nonlinear chalcogenide material of As 2 S 3 . The dispersion profile of the photonic crystal fiber (PCF) has been engineered wisely by reducing the diameter of the second air-hole ring to have a favorable higher order dispersion parameter. The parametric gain dependence upon fiber length, pump power, and different pumping wavelengths has been investigated in detail. Based upon the nonlinear four wave mixing phenomenon, we are able to achieve a wideband parametric amplifier with peak gain of 29 dB with FWHM of ≈2000 nm around the IR wavelength by proper tailoring of the dispersion profile of the PCF with a continuous wave Erbium (Er 3+ )-doped ZBLAN fiber laser emitting at 2.8 μm as the pump source with an average power of 5 W. The new design methodology will unleash a new dimension to the chalcogenide material based investigation for wavelength translation around IR wavelength band.
DEFF Research Database (Denmark)
Spano, R.; Cuadra, J.; Lingg, C.
2011-01-01
, and a relative large beam area (∅~50 μm) to obtain a true 2D condensate. Its coherence properties are measured with a Michelson interferometer. A finite correlation length is measured at an energy δE=-0.19 meV from the parametric threshold, as shown in Fig. 1(A). Once the threshold is reached, by changing...
Concurrent optical parametric down-conversion in χ(2) nonlinear photonic crystals.
Chen, L; Xu, P; Bai, Y F; Luo, X W; Zhong, M L; Dai, M; Lu, M H; Zhu, S N
2014-06-02
We experimentally investigated concurrent parametric downconversion processes in a two-dimensional hexagonally poled lithium tantalate crystal. The substantial enhancement of parametric gain was observed when concurrent processes shared a common parametric beam. Both degenerate and nondegenerate concurrent parametric downconversion processes were studied. Analyses of the spatial forms and output angles showed a strong dependence on the working temperature, during which a well-defined beamlike parametric output was observed. Our results will stimulate the design for coherent high-gain generation of multiple parametric beams and also shed light on the compact engineering of path-entanglement with specific spatial forms based on concurrent spontaneous parametric downconversion processes.
20 dB net-gain polarization-insensitive fiber optical parametric amplifier with >2 THz bandwidth.
Stephens, M F C; Gordienko, V; Doran, N J
2017-05-01
A black-box polarization insensitive fiber optical parametric amplifier (PI-FOPA) is characterized for the first time using a commercial 127 Gb/s polarization-division multiplexed PDM-QPSK transponder within a multiplex of twenty-two equivalent DWDM signals across a 2.3 THz bandwidth portion of the C-band. The PI-FOPA employs a recently demonstrated diversity loop arrangement comprising two lengths of highly nonlinear fiber (HNLF) with the parametric pump being removed after the first HNLF in both directions about the loop. This arrangement is named the Half-Pass Loop FOPA or HPL-FOPA. In total, a record equivalent 2.3 Tb/s of data is amplified within the HPL-FOPA for three different pump power regimes producing net-gains of 10 dB, 15 dB and 20 dB (averaged over all signals). For the latter two regimes, the gain bandwidth is observed to extend considerably beyond the C-band, illustrating the potential for this design to amplify signals over bandwidths commensurate with the EDFA and beyond. Under the 15 dB gain condition, the average OSNR penalty to achieve 10-3 bit error rate for all twenty three signals was found to be 0.5 ± 0.3 dB. Worst case penalty was 0.8 ± 0.3 dB, verifying the use of the architecture for polarization insensitive operation. The growth of four-wave mixing signal-signal crosstalk is additionally characterized and found to be gain independent for a fixed output power per signal. A simple effective length model is developed which predicts this behavior and suggests a new configuration for significantly reduced crosstalk.
Pump-to-Signal Intensity Modulation Transfer in Saturated- Gain Fiber Optical Parametric Amplifiers
DEFF Research Database (Denmark)
Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke; Rottwitt, Karsten
2011-01-01
The pump-to-signal intensity modulation transfer in saturated degenerate FOPAs is numerically investigated over the whole gain bandwidth. The intensity modulation transfer decreases and the OSNR improves when the amplifier operates in the saturation regime....
Third-order spontaneous parametric down-conversion in thin optical fibers as a photon-triplet source
Energy Technology Data Exchange (ETDEWEB)
Corona, Maria [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, apdo. postal 70-543, DF 04510 Mexico City (Mexico); Departamento de Optica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Apartado Postal 2732, BC 22860 Ensenada (Mexico); Garay-Palmett, Karina; U' Ren, Alfred B. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, apdo. postal 70-543, DF 04510 Mexico City (Mexico)
2011-09-15
We study the third-order spontaneous parametric down-conversion (TOSPDC) process, as a means to generate entangled photon triplets. Specifically, we consider thin optical fibers as the nonlinear medium to be used as the basis for TOSPDC in configurations where phase matching is attained through the use of more than one fiber transverse modes. Our analysis in this paper, which follows from our earlier paper [Opt. Lett. 36, 190-192 (2011)], aims to supply experimentalists with the details required in order to design a TOSPDC photon-triplet source. Specifically, our analysis focuses on the photon triplet state, on the rate of emission, and on the TOSPDC phase-matching characteristics for the cases of frequency-degenerate and frequency nondegenerate TOSPDC.
Third-order spontaneous parametric down-conversion in thin optical fibers as a photon-triplet source
International Nuclear Information System (INIS)
Corona, Maria; Garay-Palmett, Karina; U'Ren, Alfred B.
2011-01-01
We study the third-order spontaneous parametric down-conversion (TOSPDC) process, as a means to generate entangled photon triplets. Specifically, we consider thin optical fibers as the nonlinear medium to be used as the basis for TOSPDC in configurations where phase matching is attained through the use of more than one fiber transverse modes. Our analysis in this paper, which follows from our earlier paper [Opt. Lett. 36, 190-192 (2011)], aims to supply experimentalists with the details required in order to design a TOSPDC photon-triplet source. Specifically, our analysis focuses on the photon triplet state, on the rate of emission, and on the TOSPDC phase-matching characteristics for the cases of frequency-degenerate and frequency nondegenerate TOSPDC.
Zheng, Qiang; Li, Kai
2017-07-01
Amplifier is at the heart of experiments carrying out the precise measurement of a weak signal. An idea quantum amplifier should have a large gain and minimum added noise simultaneously. Here, we consider the quantum measurement properties of the cavity with the OPA medium in the op-amp mode to amplify an input signal. We show that our nonlinear-cavity quantum amplifier has large gain in the single-value stable regime and achieves quantum limit unconditionally. Supported by the National Natural Science Foundation of China under Grant Nos. 11365006, 11364006, and the Natural Science Foundation of Guizhou Province QKHLHZ [2015]7767
International Nuclear Information System (INIS)
Schneeloch, James; Howell, John C
2016-01-01
As a tutorial to the spatial aspects of spontaneous parametric downconversion (SPDC), we present a detailed first-principles derivation of the transverse correlation width of photon pairs in degenerate collinear SPDC. This width defines the size of a biphoton birth zone, the region where the signal and idler photons are likely to be found when conditioning on the position of the destroyed pump photon. Along the way, we discuss the quantum-optical calculation of the amplitude for the SPDC process, as well as its simplified form for nearly collinear degenerate phase matching. Following this, we show how this biphoton amplitude can be approximated with a double-Gaussian wavefunction, and give a brief discussion of the measurement statistics (and subsequent convenience) of such double-Gaussian wavefunctions. Next, we use this approximation to get a simplified estimation of the transverse correlation width, and compare it to more accurate calculations as well as experimental results. We then conclude with a discussion of the concept of a biphoton birth zone, using it to develop intuition for the tradeoff between the first-order spatial coherence and bipohoton correlations in SPDC. (tutorial)
International Nuclear Information System (INIS)
Yokoyama, Shiyoshi; Nakahama, Tatsuo; Mashiko, Shinro
2005-01-01
We measured the amplified spontaneous emission and laser emission from high-gain media of laser-dye encapsulated dendrimers. A highly branched poly(amidoamine) (PAMAM-OH) dendrimer formed a guest-host complex with a conventional laser-dye (DCM), resulting in a high optical-gain. Of particular note was the appearance of a laser threshold, above which a super-narrowed laser spectrum was observed, although laser feedback was caused without any mirror cavity devices. The optical feedback was attributed to spatial confinement of the light due to gain guiding under optical excitation. The laser spectrum clearly indicated a resonant laser-mode with a spectrum linewidth of less than 0.1 nm. This order of spectrum narrowing is comparable to that seen in the laser emission from ordinary laser devices
Maji, Partha Sona; Chaudhuri, Partha Roy
2015-04-10
In this work, we explore the fiber optical parametric amplifiers (FOPAs) gain and bandwidth spectra of near-zero ultra-flattened photonic crystal fibers (PCFs) around the communication wavelength. The parametric gain and spectral bandwidth have been explored for all the three zero-dispersion wavelengths (ZDWs) of the near-zero ultra-flat fiber. Our numerical analysis establishes a dispersion profile with D=0±0.35 ps/nm/km for a bandwidth of 440 nm around the communication wavelength to fully exploit the four-wave mixing effect with three ZDWs for broadband applications. It has been observed that the broader gain spectrum of FOPAs can be achieved with the near-zero and ultra-flattened dispersion curve with proper tuning of the pumping condition. A broader bandwidth with sufficient peak gain value has been achieved with small negative anomalous dispersion (β2≤0) and positive value of fourth-order dispersion parameter (+ve β4) around the pumping wavelength. Wider bandwidth of the parametric amplifier has been observed around the second ZDW with a negative slope of the dispersion curve. A total bandwidth ≈520 nm could be achieved with the ultra-flat dispersion nature of the optimized PCF. The design methodology of achieving wider gain by tuning the pumping wavelength for favorable higher-order dispersion parameters would be very useful for future dispersion engineered devices.
Gain media edge treatment to suppress amplified spontaneous emission in a high power laser
Hackel, Lloyd A [Livermore, CA; Soules, Thomas F [Livermore, CA; Fochs, Scott N [Livermore, CA; Rotter, Mark D [San Ramon, CA; Letts, Stephan A [San Ramon, CA
2011-02-22
A novel method and apparatus for suppressing ASE and/or parasitic oscillation modes in a laser is introduced. By roughening one or more peripheral edges of a solid-state crystal or ceramic laser gain media and by bonding such edges to a predetermined electromagnetic absorbing material arranged adjacent to the entire outer surface of the peripheral edges of the roughened laser gain media, ASE, parasitic oscillation modes and/or residual pump energy can be effectively suppressed.
Hentabli, Kamel
, commande robuste, approche Hinfinity , mu-synthese, systemes lineaires a parametres variants, sequencement de gains, transformation lineaire fractionnelle, inegalite matricielle lineaire.
Geiregat, Pieter; Houtepen, Arjan J; Sagar, Laxmi Kishore; Infante, Ivan; Zapata, Felipe; Grigel, Valeriia; Allan, Guy; Delerue, Christophe; Van Thourhout, Dries; Hens, Zeger
2018-01-01
Colloidal quantum dots (QDs) raise more and more interest as solution-processable and tunable optical gain materials. However, especially for infrared active QDs, optical gain remains inefficient. Since stimulated emission involves multifold degenerate band-edge states, population inversion can be attained only at high pump power and must compete with efficient multi-exciton recombination. Here, we show that mercury telluride (HgTe) QDs exhibit size-tunable stimulated emission throughout the near-infrared telecom window at thresholds unmatched by any QD studied before. We attribute this unique behaviour to surface-localized states in the bandgap that turn HgTe QDs into 4-level systems. The resulting long-lived population inversion induces amplified spontaneous emission under continuous-wave optical pumping at power levels compatible with solar irradiation and direct current electrical pumping. These results introduce an alternative approach for low-threshold QD-based gain media based on intentional trap states that paves the way for solution-processed infrared QD lasers and amplifiers.
Costela, A; García, O; Cerdán, L; García-Moreno, I; Sastre, R
2008-05-12
Amplified spontaneous emission from planar waveguides and quasi-waveguides based on Pyrromethene 567-doped poly(methyl methacrylate) thin films deposited onto quartz and glass substrates is investigated. Films with different thickness were prepared and pumped optically at 532 nm with pulses of up to 8 MW/cm(2). Pump thresholds for the onset of ASE emission, optical gains and losses were assessed. Net gain coefficients were estimated by fitting the data provided by variable stripe length measurements with a theoretical expression which takes into account saturation. In this way, net gain coefficients of up to 56 +/- 9 cm(-1) at a pump intensity of 5.3 MW/cm(2) for quasi-waveguides and up to 20.6 +/- 2.7 cm(-1) at a pump intensity of 3.4 MW/cm2 for waveguides, were obtained. Loss coefficients in the waveguides were estimated to be 3.8 +/- 0.4 cm-1 and 6.1 +/- 1.3 cm(-1) for 15 microm and 5 microm thick films, respectively. The results obtained seem to indicate a stronger self-mode-restriction capability in the quasiwaveguides than in conventional total internal-reflection waveguides.
Geiregat, Pieter; Houtepen, Arjan J.; Sagar, Laxmi Kishore; Infante, Ivan; Zapata, Felipe; Grigel, Valeriia; Allan, Guy; Delerue, Christophe; van Thourhout, Dries; Hens, Zeger
2018-01-01
Colloidal quantum dots (QDs) raise more and more interest as solution-processable and tunable optical gain materials. However, especially for infrared active QDs, optical gain remains inefficient. Since stimulated emission involves multifold degenerate band-edge states, population inversion can be attained only at high pump power and must compete with efficient multi-exciton recombination. Here, we show that mercury telluride (HgTe) QDs exhibit size-tunable stimulated emission throughout the near-infrared telecom window at thresholds unmatched by any QD studied before. We attribute this unique behaviour to surface-localized states in the bandgap that turn HgTe QDs into 4-level systems. The resulting long-lived population inversion induces amplified spontaneous emission under continuous-wave optical pumping at power levels compatible with solar irradiation and direct current electrical pumping. These results introduce an alternative approach for low-threshold QD-based gain media based on intentional trap states that paves the way for solution-processed infrared QD lasers and amplifiers.
DEFF Research Database (Denmark)
Da Ros, Francesco; Rottwitt, Karsten; Peucheret, Christophe
2012-01-01
Combining Al-doped and Ge-doped HNLFs as gain media in FOPAs is proposed and optimized, resulting in efficient SBS mitigation while circumventing the additional loss of the high SBS threshold Al-doped fiber.......Combining Al-doped and Ge-doped HNLFs as gain media in FOPAs is proposed and optimized, resulting in efficient SBS mitigation while circumventing the additional loss of the high SBS threshold Al-doped fiber....
Stephens, M F C; Tan, M; Gordienko, V; Harper, P; Doran, N J
2017-10-02
We demonstrate and characterize polarization-division multiplexed (PDM) DWDM data transmission for the first time in a range of systems incorporating a net-gain polarization-insensitive fiber optical parametric amplifier (PI-FOPA) for loss compensation. The PI-FOPA comprises a modified diversity-loop architecture to achieve 15dB net-gain, and up to 2.3THz (~18nm) bandwidth. Three representative systems are characterized using a 100Gb/s PDM-QPSK signal in conjunction with emulated DWDM neighbouring channels: (a) a 4x75km in-line fiber transmission system incorporating multiple EDFAs and a single PI-FOPA (b) N cascaded PI-FOPA amplification stages in an unlevelled Nx25km recirculating loop arrangement, with no EDFAs used within the loop signal path, and (c) M cascaded PI-FOPA amplification stages as part of an Mx75.6km gain-flattened recirculating loop system with the FOPA compensating for the transmission fiber loss, and EDFA compensation for loop switching and levelling loss. For the 4x75km in-line system (a), we transmit 45x50GHz-spaced signals ('equivalent' data-rate of 4.5Tb/s) with average OSNR penalty of 1.3dB over the band at 10 -3 BER. For the unlevelled 'FOPA-only' 25.2km cascaded system (b), we report a maximum of eight recirculations for all 10x100GHz-spaced signals, and five recirculations for 20x50GHz-spaced signals. For the 75.6km levelled system (c), we achieve eight recirculations for all 20x50GHz signals resulting in a total transmission distance of 604.8km.
DEFF Research Database (Denmark)
Ditlevsen, Susanne; Yip, Kay-Pong; Marsh, Donald J
2006-01-01
Proximal tubular pressure shows periodic self-sustained oscillations in normotensive rats but highly irregular fluctuations in spontaneously hypertensive rats (SHR). Although we have suggested that the irregular fluctuations in SHR represent low-dimensional deterministic chaos in tubuloglomerular...... mechanisms not included explicitly in the model. In its deterministic version, the model can have chaotic dynamics arising from TGF. The model introduces random fluctuations into a parameter that determines the gain of TGF. The model shows a rich variety of dynamics ranging from low-dimensional deterministic...... oscillations and chaos to high-dimensional random fluctuations. To fit the data from normotensive rats, the model must introduce only a small variation in the feedback gain, and its estimates of that gain agree well with experimental values. These results support the use of the deterministic model of nephron...
Geiregat, Pieter; Houtepen, Arjan J.; Sagar, Laxmi Kishore; Infante, Ivan; Zapata, Felipe; Grigel, Valeriia; Allan, Guy; Delerue, Christophe; Van Thourhout, Dries; Hens, Zeger
2017-01-01
Colloidal quantum dots (QDs) raise more and more interest as solution-processable and tunable optical gain materials. However, especially for infrared active QDs, optical gain remains inefficient. Since stimulated emission involves multifold degenerate band-edge states, population inversion can be
DEFF Research Database (Denmark)
Custódio, J. R.; Bastos, I.; Oliveira, L. B.
2013-01-01
This paper describes a fully-passive discrete-time switched-capacitor RF downconverter with an on-chip oscillator, that combines quadrature mixing and harmonic rejection, designed in a 130 nm digital CMOS technology. By using MOS capacitors (varactors) to perform parametric amplification, it is p......This paper describes a fully-passive discrete-time switched-capacitor RF downconverter with an on-chip oscillator, that combines quadrature mixing and harmonic rejection, designed in a 130 nm digital CMOS technology. By using MOS capacitors (varactors) to perform parametric amplification...
DEFF Research Database (Denmark)
Hermund, Anders
2010-01-01
This paper will introduce the PhD research into applied 3d modeling and parametric design outlining the idea of a parametric diagram linked to philosophical and applied examples.......This paper will introduce the PhD research into applied 3d modeling and parametric design outlining the idea of a parametric diagram linked to philosophical and applied examples....
Directory of Open Access Journals (Sweden)
Akatiev Dmitrii
2017-01-01
Full Text Available We report on the realization of a tunable single-photon source compatible with quantum memories based on isotopically pure Y7LiF4 crystals doped with Nd3+ ions. The source is based on spontaneous parametric down-conversion in a PPLN crystal placed in a resonator. The latter is formed by two mirrors which are transparent for the pump (532 nm and idler (1377 nm fields but high reflective for the signal field (867 nm. The width of the second-order cross-correlation function between the signal and idler photons is determined to be 1.5 ns for the cavity length of 8 cm, which corresponds to a cavity bandwidth of 100 MHz.
Pump to signal noise transfer in parametric fiber amplifiers
DEFF Research Database (Denmark)
Lund-Hansen, Toke; Rottwitt, Karsten; Peucheret, Christophe
2010-01-01
Fiber optic parametric amplifiers have been suggested due to their potential low spontaneous emission. However, by nature the parametric amplifier only work in a forward pumped configuration, which result in transfer of relative intensity noise in the pump to the signal.......Fiber optic parametric amplifiers have been suggested due to their potential low spontaneous emission. However, by nature the parametric amplifier only work in a forward pumped configuration, which result in transfer of relative intensity noise in the pump to the signal....
Zhang, Yanbin; Lin, Guanfeng; Wang, Shengru; Zhang, Jianguo; Shen, Jianxiong; Wang, Yipeng; Guo, Jianwei; Yang, Xinyu; Zhao, Lijuan
2016-11-15
Retrospective study. To study the behavior of the unfused thoracic curve in Lenke type 5C during the follow-up and to identify risk factors for its correction loss. Few studies have focused on the spontaneous behaviors of the unfused thoracic curve after selective thoracolumbar or lumbar fusion during the follow-up and the risk factors for spontaneous correction loss. We retrospectively reviewed 45 patients (41 females and 4 males) with AIS who underwent selective TL/L fusion from 2006 to 2012 in a single institution. The follow-up averaged 36 months (range, 24-105 months). Patients were divided into two groups. Thoracic curves in group A improved or maintained their curve magnitude after spontaneous correction, with a negative or no correction loss during the follow-up. Thoracic curves in group B deteriorated after spontaneous correction with a positive correction loss. Univariate analysis and multivariate analysis were built to identify the risk factors for correction loss of the unfused thoracic curves. The minor thoracic curve was 26° preoperatively. It was corrected to 13° immediately with a spontaneous correction of 48.5%. At final follow-up it was 14° with a correction loss of 1°. Thoracic curves did not deteriorate after spontaneous correction in 23 cases in group A, while 22 cases were identified with thoracic curve progressing in group B. In multivariate analysis, two risk factors were independently associated with thoracic correction loss: higher flexibility and better immediate spontaneous correction rate of thoracic curve. Posterior selective TL/L fusion with pedicle screw constructs is an effective treatment for Lenke 5C AIS patients. Nonstructural thoracic curves with higher flexibility or better immediate correction are more likely to progress during the follow-up and close attentions must be paid to these patients in case of decompensation. 4.
Study of three-mode parametric instability
International Nuclear Information System (INIS)
Liang Fengchao; Zhao Chunnong; Gras, Slawomir; Ju Li; Blair, D G
2010-01-01
The effect of parametric instability in advanced interferometric gravitational wave detectors is a potential problem for their proper operation. Great efforts have been made to study the onset of parametric instabilities and to find ways to control them. Here we present an experimental design for studying parametric instability in a 72 m cavity with suspended high quality fused silica mirrors. With 5 W input power and 20 kW circulation power inside the cavity, it is predicted that parametric instability will occur. The resonant condition of parametric instability can be met by thermally tuning the radius of curvature of a test mass. We will present simulation results of parametric gains for different radii of curvature of a test mass. The simulation results will provide the basis for designing the thermal tuning and observation parametric instability experiments. This will provide a test bed for studying parametric instability and its control for next generation detectors.
Macromechanical Parametric Amplification
DEFF Research Database (Denmark)
Neumeyer, Stefan
between the two peaks can be altered. The first experimental bistable amplified steady-state responses are also reported. The derived analytical models and experimental setups can readily be extended to investigate other factors. Some of the results are also applicable to the more general field of systems...... for energy harvesting. Using analytical, numerical, and experimental methods, the thesis focuses on superthreshold pumping (above the systems parametric instability threshold), nonlinear effects, frequency response backbones, and frequency detuning effects for parametric amplifiers. Part one of the thesis...... covers superthreshold pumping and nonlinear effects. Superthresh-old pumping produces some useful characteristics. For instance, strong superthreshold pumping yields a high gain even though nonlinear effects tend to reduce it. In addition, a narrower excitation phase range is realized for which...
Estimating the potential gains from mergers
DEFF Research Database (Denmark)
Bogetoft, Peter; Wang, Dexiang
2005-01-01
We introduce simple production economic models to estimate the potential gains from mergers. We decompose the gains into technical ef¿ciency, size (scale) and harmony (mix) gains, and we discuss alternative ways to capture these gains. We propose to approximate the production processes using...... the non-parametric. Data Envelopment Analysis (DEA) approach, and we use the resulting operational approach to estimate the potential gains from merging agricultural extension of¿ces in Denmark....
Controlling the dynamic range of a Josephson parametric amplifier
International Nuclear Information System (INIS)
Eichler, Christopher; Wallraff, Andreas
2014-01-01
One of the central challenges in the development of parametric amplifiers is the control of the dynamic range relative to its gain and bandwidth, which typically limits quantum limited amplification to signals which contain only a few photons per inverse bandwidth. Here, we discuss the control of the dynamic range of Josephson parametric amplifiers by using Josephson junction arrays. We discuss gain, bandwidth, noise, and dynamic range properties of both a transmission line and a lumped element based parametric amplifier. Based on these investigations we derive useful design criteria, which may find broad application in the development of practical parametric amplifiers. (orig.)
Directory of Open Access Journals (Sweden)
Davari R
1996-07-01
Full Text Available A case with bilateral spontaneous pneumothorax was presented. Etiology, mechanism, and treatment were discussed on the review of literature. Spontaneous Pneumothorax is a clinical entity resulting from a sudden non traumatic rupture of the lung. Biach reported in 1880 that 78% of 916 patients with spontaneous pneumothorax had tuberculosis. Kjergaard emphasized 1932 the primary importance of subpleural bleb disease. Currently the clinical spectrum of spontaneous pneumothorax seems to have entered a third era with the recognition of the interstitial lung disease and AIDS as a significant etiology. Standard treatment is including: observation, thoracocentesis, tube thoracostomy. Chemical pleurodesis, bullectomy or wedge resection of lung with pleural abrasion and occasionally pleurectomy. Little information has been reported regarding the efficacy of such treatment in spontaneous pneumothorax secondary to non bleb disease
Multiple Frequency Parametric Sonar
2015-09-28
300003 1 MULTIPLE FREQUENCY PARAMETRIC SONAR STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and...a method for increasing the bandwidth of a parametric sonar system by using multiple primary frequencies rather than only two primary frequencies...2) Description of Prior Art [0004] Parametric sonar generates narrow beams at low frequencies by projecting sound at two distinct primary
Frequency domain optical parametric amplification.
Schmidt, Bruno E; Thiré, Nicolas; Boivin, Maxime; Laramée, Antoine; Poitras, François; Lebrun, Guy; Ozaki, Tsuneyuki; Ibrahim, Heide; Légaré, François
2014-05-07
Today's ultrafast lasers operate at the physical limits of optical materials to reach extreme performances. Amplification of single-cycle laser pulses with their corresponding octave-spanning spectra still remains a formidable challenge since the universal dilemma of gain narrowing sets limits for both real level pumped amplifiers as well as parametric amplifiers. We demonstrate that employing parametric amplification in the frequency domain rather than in time domain opens up new design opportunities for ultrafast laser science, with the potential to generate single-cycle multi-terawatt pulses. Fundamental restrictions arising from phase mismatch and damage threshold of nonlinear laser crystals are not only circumvented but also exploited to produce a synergy between increased seed spectrum and increased pump energy. This concept was successfully demonstrated by generating carrier envelope phase stable, 1.43 mJ two-cycle pulses at 1.8 μm wavelength.
Parametric amplification in MoS2drum resonator.
Prasad, Parmeshwar; Arora, Nishta; Naik, A K
2017-11-30
Parametric amplification is widely used in diverse areas from optics to electronic circuits to enhance low level signals by varying relevant system parameters. Parametric amplification has also been performed in several micro-nano resonators including nano-electromechanical system (NEMS) resonators based on a two-dimensional (2D) material. Here, we report the enhancement of mechanical response in a MoS 2 drum resonator using degenerate parametric amplification. We use parametric pumping to modulate the spring constant of the MoS 2 resonator and achieve a 10 dB amplitude gain. We also demonstrate quality factor enhancement in the resonator with parametric amplification. We investigate the effect of cubic nonlinearity on parametric amplification and show that it limits the gain of the mechanical resonator. Amplifying ultra-small displacements at room temperature and understanding the limitations of the amplification in these devices is key for using these devices for practical applications.
On Parametric (and Non-Parametric Variation
Directory of Open Access Journals (Sweden)
Neil Smith
2009-11-01
Full Text Available This article raises the issue of the correct characterization of ‘Parametric Variation’ in syntax and phonology. After specifying their theoretical commitments, the authors outline the relevant parts of the Principles–and–Parameters framework, and draw a three-way distinction among Universal Principles, Parameters, and Accidents. The core of the contribution then consists of an attempt to provide identity criteria for parametric, as opposed to non-parametric, variation. Parametric choices must be antecedently known, and it is suggested that they must also satisfy seven individually necessary and jointly sufficient criteria. These are that they be cognitively represented, systematic, dependent on the input, deterministic, discrete, mutually exclusive, and irreversible.
New Logic Circuit with DC Parametric Excitation
Sugahara, Masanori; Kaneda, Hisayoshi
1982-12-01
It is shown that dc parametric excitation is possible in a circuit named JUDO, which is composed of two resistively-connected Josephson junctions. Simulation study proves that the circuit has large gain and properties suitable for the construction of small, high-speed logic circuits.
Parametric Amplifiers for Readout of Low-Temperature Detectors
National Aeronautics and Space Administration — This project aims to make microwave parametric amplifiers with high gain, large bandwidth, ultra-low noise, and low power dissipation. Our amplifiers are designed to...
Edelman, Benjamin; Geradin, Damien
Platform businesses such as Airbnb and Uber have risen to success partly by sidestepping laws and regulations that encumber their traditional competitors. Such rule flouting is what the authors call “spontaneous private deregulation,” and it’s happening in a growing number of industries. The authors
DEFF Research Database (Denmark)
Steinø, Nicolai; Obeling, Esben
2013-01-01
by the “Twitter revolution” and other social media phenomena in recent years – may also form the basis of this approach, adding a different reach to it. While different parametric design tools have different strengths and weaknesses, the CityEngine software programme is dedicated to parametric simulation...
Parametrization of translational surfaces
Perez-Diaz, Sonia; Shen, Liyong
2014-01-01
The algebraic translational surface is a typical modeling surface in computer aided design and architecture industry. In this paper, we give a necessary and sufficient condition for that algebraic surface having a standard parametric representation and our proof is constructive. If the given algebraic surface is translational, then we can compute a standard parametric representation for the surface.
Radial modal dependence of the azimuthal spectrum after parametric down-conversion
CSIR Research Space (South Africa)
Zhang, Y
2014-01-01
Full Text Available The radial degrees of freedom of the biphoton states that are produced in spontaneous parametric down-conversion (SPDC) in the Laguerre-Gaussian (LG) basis are investigated, theoretically and experimentally. We calculated the theoretical azimuthal...
Quantum and Raman Noise in a Depleted Fiber Optical Parametric Amplifier
DEFF Research Database (Denmark)
Friis, Søren Michael Mørk; Rottwitt, Karsten; McKinstrie, Colin J.
2013-01-01
The noise properties of both phase-sensitive and phase-insensitive saturated parametric amplifiers are studied using a semi-classical approach. Vacuum fluctuations as well as spontaneous Raman scattering are included in the analysis....
Quantum interference and diffraction of parametric down-converted ...
Indian Academy of Sciences (India)
This result also represents the non-classical nature of the biphotons generated by spontaneous parametric down-conversion. Acknowledgements. This work was supported by a grant-in-aid for Scientific Research from the Ministry of. Education, Culture, Sports, Science and Technology of Japan, and by the program 'Re-.
Parametric and Non-Parametric System Modelling
DEFF Research Database (Denmark)
Nielsen, Henrik Aalborg
1999-01-01
considered. It is shown that adaptive estimation in conditional parametric models can be performed by combining the well known methods of local polynomial regression and recursive least squares with exponential forgetting. The approach used for estimation in conditional parametric models also highlights how...... of a linear model are estimated as functions of some explanatory variable(s). Also, software for handling the estimation is presented. The software runs under S-PLUS and R and contains also a number of tools useful when doing model diagnostics or interpreting the results. Adaptive estimation is also...... networks is included. In this paper, neural networks are used for predicting the electricity production of a wind farm. The results are compared with results obtained using an adaptively estimated ARX-model. Finally, two papers on stochastic differential equations are included. In the first paper, among...
parametric nonlinear quasivariational inequalities
Directory of Open Access Journals (Sweden)
Zeqing Liu
2005-01-01
uniqueness results and sensitivity analysis of solutions are also established for the system of generalized nonlinear parametric quasivariational inequalities and some convergence results of iterative sequence generated by the algorithm with errors are proved.
Controlling Parametric Resonance
DEFF Research Database (Denmark)
Galeazzi, Roberto; Pettersen, Kristin Ytterstad
2012-01-01
if the system undergoing it could transform the large amplitude motion into, for example, energy. Therefore the development of control strategies to induce parametric resonance into a system can be as valuable as those which aim at stabilizing the resonant oscillations. By means of a mechanical equivalent......Parametric resonance is a resonant phenomenon which takes place in systems characterized by periodic variations of some parameters. While seen as a threatening condition, whose onset can drive a system into instability, this chapter advocates that parametric resonance may become an advantage...... the authors review the conditions for the onset of parametric resonance, and propose a nonlinear control strategy in order to both induce the resonant oscillations and to stabilize the unstable motion. Lagrange’s theory is used to derive the dynamics of the system and input–output feedback linearization...
Implementing calculations of solar gains in parametric models
DEFF Research Database (Denmark)
Petersen, Mads Dines; Knudstrup, Mary-Ann
2009-01-01
Working with environmentally sustainable architecture today is becoming more and more challenging due to the strict energy demands in the building regulations (Hyde et al. 2007). This demands a design process, where parameters affecting the energy demands are considered from the very beginning......, and where relations between the architectural form, the building envelope and the climatic conditions on the site are in focus in order to lower the energy demand in the building during operation. Such a focus on energy consumption is the theme at Architecture & Design's, Aalborg University, 8th semester...... architecture specialization, where the students work with environmental architecture. A basis for understanding this and for working with different parameters related to this topic is the diagram seen in Figure 1 and 2 (Knudstrup et al. 2009) developed through studies of different tools used in the broad field...
Raman-Enhanced Phase-Sensitive Fibre Optical Parametric Amplifier
Fu, Xuelei; Guo, Xiaojie; Shu, Chester
2016-01-01
Phase-sensitive amplification is of great research interest owing to its potential in noiseless amplification. One key feature in a phase-sensitive amplifier is the gain extinction ratio defined as the ratio of the maximum to the minimum gains. It quantifies the capability of the amplifier in performing low-noise amplification for high phase-sensitive gain. Considering a phase-sensitive fibre optical parametric amplifier for linear amplification, the gain extinction ratio increases with the phase-insensitive parametric gain achieved from the same pump. In this work, we use backward Raman amplification to increase the phase-insensitive parametric gain, which in turn improves the phase-sensitive operation. Using a 955 mW Raman pump, the gain extinction ratio is increased by 9.2 dB. The improvement in the maximum phase-sensitive gain is 18.7 dB. This scheme can significantly boost the performance of phase-sensitive amplification in a spectral range where the parametric pump is not sufficiently strong but broadband Raman amplification is available. PMID:26830136
Enhanced Gain in Photonic Crystal Amplifiers
DEFF Research Database (Denmark)
Ek, Sara; Semenova, Elizaveta; Hansen, Per Lunnemann
2012-01-01
We experimentally demonstrate enhanced gain in the slow-light regime of quantum well photonic crystal amplifiers. A strong gain enhancement is observed with the increase of the group refractive index, due to light slow-down. The slow light enhancement is shown in a amplified spontaneous emission...
International Nuclear Information System (INIS)
Horikiri, Tomoyuki; Sasaki, Hideki; Wang, Haibo; Kobayashi, Takayoshi
2005-01-01
We propose a high security quantum key distribution (QKD) scheme utilizing one mode of spontaneous parametric downconversion gated by a photon number resolving detector. This photon number measurement is possible by using single-photon detectors operating at room temperature and optical fibers. By post selection, the multiphoton probability in this scheme can be reduced to lower than that of a scheme using an attenuated coherent light resulting in improvement of security. Furthermore, if distillation protocol (error correction and privacy amplification) is performed, the gain will be increased. Hence a QKD system with higher security and bit rate than the laser-based QKD system can be attained using present available technologies
David, William I. F.; Evans, John S. O.
The rapidity with which powder diffraction data may be collected, not only at neutron and X-ray synchrotron facilities but also in the laboratory, means that the collection of a single diffraction pattern is now the exception rather than the rule. Many experiments involve the collection of hundreds and perhaps many thousands of datasets where a parameter such as temperature or pressure is varied or where time is the variable and life-cycle, synthesis or decomposition processes are monitored or three-dimensional space is scanned and the three-dimensional internal structure of an object is elucidated. In this paper, the origins of parametric diffraction are discussed and the techniques and challenges of parametric powder diffraction analysis are presented. The first parametric measurements were performed around 50 years ago with the development of a modified Guinier camera but it was the automation afforded by neutron diffraction combined with increases in computer speed and memory that established parametric diffraction on a strong footing initially at the ILL, Grenoble in France. The theoretical parameterisation of quantities such as lattice constants and atomic displacement parameters will be discussed and selected examples of parametric diffraction over the past 20 years will be reviewed that highlight the power of the technique.
Parametric Instability in Advanced Laser Interferometer Gravitational Wave Detectors
International Nuclear Information System (INIS)
Ju, L; Grass, S; Zhao, C; Degallaix, J; Blair, D G
2006-01-01
High frequency parametric instabilities in optical cavities are radiation pressure induced interactions between test mass mechanical modes and cavity optical modes. The parametric gain depends on the cavity power and the quality factor of the test mass internal modes (usually in ultrasonic frequency range), as well as the overlap integral for the mechanical and optical modes. In advanced laser interferometers which require high optical power and very low acoustic loss test masses, parametric instabilities could prevent interferometer operation if not suppressed. Here we review the problem of parametric instabilities in advanced detector configurations for different combinations of sapphire and fused silica test masses, and compare three methods for control or suppression of parametric instabilities-thermal tuning, surface damping and active feedback
PARAMETRIC DRAWINGS VS. AUTOLISP
Directory of Open Access Journals (Sweden)
PRUNĂ Liviu
2015-06-01
Full Text Available In this paper the authors make a critical analysis of the advantages offered by the parametric drawing use by comparison with the AutoLISP computer programs used when it comes about the parametric design. Studying and analysing these two work models the authors have got to some ideas and conclusions which should be considered in the moment in that someone must to decide if it is the case to elaborate a software, using the AutoLISP language, or to establish the base rules that must be followed by the drawing, in the idea to construct outlines or blocks which can be used in the projection process.
PARAMETRIC DRAWINGS VS. AUTOLISP
PRUNĂ Liviu; SLONOVSCHI Andrei
2015-01-01
In this paper the authors make a critical analysis of the advantages offered by the parametric drawing use by comparison with the AutoLISP computer programs used when it comes about the parametric design. Studying and analysing these two work models the authors have got to some ideas and conclusions which should be considered in the moment in that someone must to decide if it is the case to elaborate a software, using the AutoLISP language, or to establish the base rules that must be followed...
Controlling noise in plasmonic structures with gain
Vyshnevyy, A. A.; Fedyanin, D. Yu.
2017-09-01
Loss compensation by gain medium gives the possibility to exploit subwavelength confinement of light in plasmonic nanostructures and construct nanoscale plasmonic circuits. However, due to fundamentally unavoidable spontaneous emission from the gain medium, lossless waveguides suffer from strong photonic noise, which limits their practical applications. Here we demonstrate the possibility of significant decrease of the noise level while preserving physical dimensions of lossless plasmonic waveguides with gain. Our findings are aimed at extending the communication capabilities of on-chip plasmonic networks.
DEFF Research Database (Denmark)
Herzog, Dennis
with an investigation of PHMM training methods and structures to utilize the PHMM as a unified representation of parametric primitives, which is adequate for recognition and for synthesis. This is evaluated on a large motion data set. Main contributions of the thesis are the development and evaluation of approaches...
Parametric modal transition systems
DEFF Research Database (Denmark)
Beneš, Nikola; Křetínský, Jan; Larsen, Kim Guldstrand
2011-01-01
in the refinement process like exclusive, conditional and persistent choices. We introduce a new model called parametric modal transition systems (PMTS) together with a general modal refinement notion that overcome many of the limitations and we investigate the computational complexity of modal refinement checking....
Spontaneous Breaking of Spatial and Spin Symmetry in Spinor Condensates
DEFF Research Database (Denmark)
Scherer, M.; Lücke, B.; Gebreyesus, G.
2010-01-01
Parametric amplification of quantum fluctuations constitutes a fundamental mechanism for spontaneous symmetry breaking. In our experiments, a spinor condensate acts as a parametric amplifier of spin modes, resulting in a twofold spontaneous breaking of spatial and spin symmetry in the amplified...... broken, but phase squeezing prevents spin-symmetry breaking. If, however, nondegenerate spin modes contribute to the amplification, quantum interferences lead to spin-dependent density profiles and hence spontaneously formed patterns in the longitudinal magnetization....... clouds. Our experiments permit a precise analysis of the amplification in specific spatial Bessel-like modes, allowing for the detailed understanding of the double symmetry breaking. On resonances that create vortex-antivortex superpositions, we show that the cylindrical spatial symmetry is spontaneously...
Parametric instabilities in advanced gravitational wave detectors
International Nuclear Information System (INIS)
Gras, S; Zhao, C; Blair, D G; Ju, L
2010-01-01
As the LIGO interferometric gravitational wave detectors have finished gathering a large observational data set, an intense effort is underway to upgrade these observatories to improve their sensitivity by a factor of ∼10. High circulating power in the arm cavities is required, which leads to the possibility of parametric instability due to three-mode opto-acoustic resonant interactions between the carrier, transverse optical modes and acoustic modes. Here, we present detailed numerical analysis of parametric instability in a configuration that is similar to Advanced LIGO. After examining parametric instability for a single three-mode interaction in detail, we examine instability for the best and worst cases, as determined by the resonance condition of transverse modes in the power and signal recycling cavities. We find that, in the best case, the dual recycling detector is substantially less susceptible to instability than a single cavity, but its susceptibility is dependent on the signal recycling cavity design, and on tuning for narrow band operation. In all cases considered, the interferometer will experience parametric instability at full power operation, but the gain varies from 3 to 1000, and the number of unstable modes varies between 7 and 30 per test mass. The analysis focuses on understanding the detector complexity in relation to opto-acoustic interactions, on providing insights that can enable predictions of the detector response to transient disturbances, and of variations in thermal compensation conditions.
MEMS digital parametric loudspeaker
Carreno, Armando Arpys Arevalo
2016-03-23
This paper reports on the design and fabrication of MEMS actuator arrays suitable for Digital Sound reconstruction and Parametric Directional Loudspeakers. Two distinct versions of the device were fabricated: one using the electrostatic principle actuation and the other one, the piezoelectric principle. Both versions used similar membrane dimensions, with a diameter of 500 μm. These devices are the smallest Micro-Machined Ultrasound Transducer (MUT) arrays that can be operated for both modes: Digital Sound Reconstruction and Parametric Loudspeaker. The chips consist of an array with 256 transducers, in a footprint of 12 mm by 12 mm. The total single chip size is: 2.3 cm by 2.3 cm, including the contact pads. © 2016 IEEE.
Parametric Explosion Spectral Model
Energy Technology Data Exchange (ETDEWEB)
Ford, S R; Walter, W R
2012-01-19
Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never before occurred. We develop a parametric model of the nuclear explosion seismic source spectrum derived from regional phases that is compatible with earthquake-based geometrical spreading and attenuation. Earthquake spectra are fit with a generalized version of the Brune spectrum, which is a three-parameter model that describes the long-period level, corner-frequency, and spectral slope at high-frequencies. Explosion spectra can be fit with similar spectral models whose parameters are then correlated with near-source geology and containment conditions. We observe a correlation of high gas-porosity (low-strength) with increased spectral slope. The relationship between the parametric equations and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source.
Towards Stabilizing Parametric Active Contours
DEFF Research Database (Denmark)
Liu, Jinchao; Fan, Zhun; Olsen, Søren Ingvor
2014-01-01
to a parametrization that is proportional to the natural parametrization which implies that the control points of the contour are uniformly distributed. We theoretically prove that this tangential diffusion term is bounded and therefore numerically stable. Several experiments were conducted and verified......Numerical instability often occurs in evolving of parametric active contours. This is mainly due to the undesired change of parametrization during evolution. In this paper, we propose a new tangential diffusion term to compensate this undesired change. As a result, the parametrization will converge...
Harding, John E.; Shepherd, Paul
2017-01-01
Parametric modelling software often maintains an explicit history of design development in the form of a graph. However, as the graph increases in complexity it quickly becomes inflexible and unsuitable for exploring a wide design space. By contrast, implicit low-level rule systems can offer wide design exploration due to their lack of structure, but often act as black boxes to human observers with only initial conditions and final designs cognisable. In response to these two extremes, the au...
Parametric amplification by coupled flux qubits
Energy Technology Data Exchange (ETDEWEB)
Rehák, M.; Neilinger, P.; Grajcar, M. [Department of Experimental Physics, Comenius University, SK-84248 Bratislava (Slovakia); Institute of Physics, Slovak Academy of Science, 845 11 Bratislava (Slovakia); Oelsner, G.; Hübner, U.; Meyer, H.-G. [Leibniz Institute of Photonic Technology, P.O. Box 100239, D-07702 Jena (Germany); Il' ichev, E. [Leibniz Institute of Photonic Technology, P.O. Box 100239, D-07702 Jena (Germany); Novosibirsk State Technical University, 20 K. Marx Ave., 630092 Novosibirsk (Russian Federation)
2014-04-21
We report parametric amplification of a microwave signal in a Kerr medium formed from superconducting qubits. Two mutually coupled flux qubits, embedded in the current antinode of a superconducting coplanar waveguide resonator, are used as a nonlinear element. Shared Josephson junctions provide the qubit-resonator coupling, resulting in a device with a tunable Kerr constant (up to 3 × 10{sup −3}) and a measured gain of about 20 dB. This arrangement represents a unit cell which can be straightforwardly extended to a quasi one-dimensional quantum metamaterial with large tunable Kerr nonlinearity, providing a basis for implementation of wide-band travelling wave parametric amplifiers.
Parametric Resonance in Dynamical Systems
Nijmeijer, Henk
2012-01-01
Parametric Resonance in Dynamical Systems discusses the phenomenon of parametric resonance and its occurrence in mechanical systems,vehicles, motorcycles, aircraft and marine craft, and micro-electro-mechanical systems. The contributors provide an introduction to the root causes of this phenomenon and its mathematical equivalent, the Mathieu-Hill equation. Also included is a discussion of how parametric resonance occurs on ships and offshore systems and its frequency in mechanical and electrical systems. This book also: Presents the theory and principles behind parametric resonance Provides a unique collection of the different fields where parametric resonance appears including ships and offshore structures, automotive vehicles and mechanical systems Discusses ways to combat, cope with and prevent parametric resonance including passive design measures and active control methods Parametric Resonance in Dynamical Systems is ideal for researchers and mechanical engineers working in application fields such as MEM...
Two-stage optical parametric amplifier of a low energy nanosecond pulses
Bagdasarov, V. Kh; Bel'kov, S. A.; Garanin, S. G.; Garnov, S. V.; Nikolaev, D. A.; Orlov, S. N.; Polivanov, Y. N.; Sadovskiy, S. P.; Shcherbakov, I. A.; Tsvetkov, V. B.
2017-05-01
A two-stage optical parametric amplifier (OPA) design that provides over -5 × 107 gain at 1053 nm is presented. Noise level of the parametric amplifier in the signal wave propagation direction was 2 × 10-6 from the signal level. The parasitic parametric oscillation under intense pump wave and its contribution to the OPA output was measured to be less than 8%.
Rosu, Grigore (Inventor); Chen, Feng (Inventor); Chen, Guo-fang; Wu, Yamei; Meredith, Patrick O. (Inventor)
2014-01-01
A program trace is obtained and events of the program trace are traversed. For each event identified in traversing the program trace, a trace slice of which the identified event is a part is identified based on the parameter instance of the identified event. For each trace slice of which the identified event is a part, the identified event is added to an end of a record of the trace slice. These parametric trace slices can be used in a variety of different manners, such as for monitoring, mining, and predicting.
Wey, Andrew; Connett, John; Rudser, Kyle
2015-07-01
For estimating conditional survival functions, non-parametric estimators can be preferred to parametric and semi-parametric estimators due to relaxed assumptions that enable robust estimation. Yet, even when misspecified, parametric and semi-parametric estimators can possess better operating characteristics in small sample sizes due to smaller variance than non-parametric estimators. Fundamentally, this is a bias-variance trade-off situation in that the sample size is not large enough to take advantage of the low bias of non-parametric estimation. Stacked survival models estimate an optimally weighted combination of models that can span parametric, semi-parametric, and non-parametric models by minimizing prediction error. An extensive simulation study demonstrates that stacked survival models consistently perform well across a wide range of scenarios by adaptively balancing the strengths and weaknesses of individual candidate survival models. In addition, stacked survival models perform as well as or better than the model selected through cross-validation. Finally, stacked survival models are applied to a well-known German breast cancer study. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Diffusion-induced parametric dispersion and amplification in doped ...
Indian Academy of Sciences (India)
Using the hydrodynamic model of semiconductor plasma, the diffusion-induced nonlinear current density and the consequent second-order effective susceptibility are obtained under off-resonant laser irradiation. The analysis deals with the qualitative behaviour of the anomalous parametric dispersion and the gain profile ...
Parametric urban design : An interactive sketching system for shaping neighborhoods
Beirao, J.N.; Nourian Ghadi Kolaee, P.; Mashhoodi, B.
2011-01-01
In this paper we show the structure of an urban design parametric system. The system is dynamic and builds an interactive relation with the designer updating the layout and related data at each input change. The responsiveness of the system allows the designer to gain awareness on the qualitative
Parametric Linear Dynamic Logic
Directory of Open Access Journals (Sweden)
Peter Faymonville
2014-08-01
Full Text Available We introduce Parametric Linear Dynamic Logic (PLDL, which extends Linear Dynamic Logic (LDL by temporal operators equipped with parameters that bound their scope. LDL was proposed as an extension of Linear Temporal Logic (LTL that is able to express all ω-regular specifications while still maintaining many of LTL's desirable properties like an intuitive syntax and a translation into non-deterministic Büchi automata of exponential size. But LDL lacks capabilities to express timing constraints. By adding parameterized operators to LDL, we obtain a logic that is able to express all ω-regular properties and that subsumes parameterized extensions of LTL like Parametric LTL and PROMPT-LTL. Our main technical contribution is a translation of PLDL formulas into non-deterministic Büchi word automata of exponential size via alternating automata. This yields a PSPACE model checking algorithm and a realizability algorithm with doubly-exponential running time. Furthermore, we give tight upper and lower bounds on optimal parameter values for both problems. These results show that PLDL model checking and realizability are not harder than LTL model checking and realizability.
Kernel bandwidth estimation for non-parametric density estimation: a comparative study
CSIR Research Space (South Africa)
Van der Walt, CM
2013-12-01
Full Text Available We investigate the performance of conventional bandwidth estimators for non-parametric kernel density estimation on a number of representative pattern-recognition tasks, to gain a better understanding of the behaviour of these estimators in high...
A Parametric Oscillator Experiment for Undergraduates
Huff, Alison; Thompson, Johnathon; Pate, Jacob; Kim, Hannah; Chiao, Raymond; Sharping, Jay
We describe an upper-division undergraduate-level analytic mechanics experiment or classroom demonstration of a weakly-damped pendulum driven into parametric resonance. Students can derive the equations of motion from first principles and extract key oscillator features, such as quality factor and parametric gain, from experimental data. The apparatus is compact, portable and easily constructed from inexpensive components. Motion control and data acquisition are accomplished using an Arduino micro-controller incorporating a servo motor, laser sensor, and data logger. We record the passage time of the pendulum through its equilibrium position and obtain the maximum speed per oscillation as a function of time. As examples of the interesting physics which the experiment reveals, we present contour plots depicting the energy of the system as functions of driven frequency and modulation depth. We observe the transition to steady state oscillation and compare the experimental oscillation threshold with theoretical expectations. A thorough understanding of this hands-on laboratory exercise provides a foundation for current research in quantum information and opto-mechanics, where damped harmonic motion, quality factor, and parametric amplification are central.
Management of intractable spontaneous epistaxis
Rudmik, Luke
2012-01-01
Background: Epistaxis is a common otolaryngology emergency and is often controlled with first-line interventions such as cautery, hemostatic agents, or anterior nasal packing. A subset of patients will continue to bleed and require more aggressive therapy. Methods: Intractable spontaneous epistaxis was traditionally managed with posterior nasal packing and prolonged hospital admission. In an effort to reduce patient morbidity and shorten hospital stay, surgical and endovascular techniques have gained popularity. A literature review was conducted. Results: Transnasal endoscopic sphenopalatine artery ligation and arterial embolization provide excellent control rates but the decision to choose one over the other can be challenging. The role of transnasal endoscopic anterior ethmoid artery ligation is unclear but may be considered in certain cases when bleeding localizes to the ethmoid region. Conclusion: This article will focus on the management of intractable spontaneous epistaxis and discuss the role of endoscopic arterial ligation and embolization as it pertains to this challenging clinical scenario. PMID:22391084
Classification rates: non‐parametric verses parametric models using ...
African Journals Online (AJOL)
The local likelihood technique was used to model fit the data sets. The same sets of data were modeled using parametric logit and the abilities of the two models to correctly predict the binary outcome compared. The results obtained showed that non‐parametric estimation gives a better prediction rate (classification ratio) for ...
Use of parametric and non-parametric survival analysis techniques ...
African Journals Online (AJOL)
This paper presents parametric and non-parametric survival analysis procedures that can be used to compare acaricides. The effectiveness of Delta Tick Pour On and Delta Tick Spray in knocking down tsetse flies were determined. The two formulations were supplied by Chemplex. The comparison was based on data ...
RAMAN amplifier gain dynamics with ASE : Numerical analysis and ...
African Journals Online (AJOL)
... understanding the basic properties of the gain medium. So in this work, we demonstrate an analytical formalism and a numerical horizon of the amplified spontaneous emission (ASE) noise power for distributed Raman amplifier (DRA). Keywords: Amplified spontaneous emission (ASE), optical noise, Raman amplification ...
Markovian Dynamics of Josephson Parametric Amplification
Directory of Open Access Journals (Sweden)
W. Kaiser
2017-09-01
Full Text Available In this work, we derive the dynamics of the lossy DC pumped non-degenerate Josephson parametric amplifier (DCPJPA. The main element in a DCPJPA is the superconducting Josephson junction. The DC bias generates the AC Josephson current varying the nonlinear inductance of the junction. By this way the Josephson junction acts as the pump oscillator as well as the time varying reactance of the parametric amplifier. In quantum-limited amplification, losses and noise have an increased impact on the characteristics of an amplifier. We outline the classical model of the lossy DCPJPA and derive the available noise power spectral densities. A classical treatment is not capable of including properties like spontaneous emission which is mandatory in case of amplification at the quantum limit. Thus, we derive a quantum mechanical model of the lossy DCPJPA. Thermal losses are modeled by the quantum Langevin approach, by coupling the quantized system to a photon heat bath in thermodynamic equilibrium. The mode occupation in the bath follows the Bose-Einstein statistics. Based on the second quantization formalism, we derive the Heisenberg equations of motion of both resonator modes. We assume the dynamics of the system to follow the Markovian approximation, i.e. the system only depends on its actual state and is memory-free. We explicitly compute the time evolution of the contributions to the signal mode energy and give numeric examples based on different damping and coupling constants. Our analytic results show, that this model is capable of including thermal noise into the description of the DC pumped non-degenerate Josephson parametric amplifier.
DEFF Research Database (Denmark)
Peucheret, Christophe; Lorenzen, Michael Rodas; Seoane, Jorge
2008-01-01
Input power dynamic range enhancement and amplitude regeneration of highly distorted signals are demonstrated experimentally for 40 Gbit/s RZ-DPSK in a single-pump fibre parametric amplifier with 22 dB smallsignal gain.......Input power dynamic range enhancement and amplitude regeneration of highly distorted signals are demonstrated experimentally for 40 Gbit/s RZ-DPSK in a single-pump fibre parametric amplifier with 22 dB smallsignal gain....
DEFF Research Database (Denmark)
Lorenzen, Michael Rodas; Noordegraaf, Danny; Nielsen, Carsten Vandel
2008-01-01
We demonstrate an increased gain in optical parametric amplier through suppression of stimulated Brillouin scattering by applying a temperature distribution along the fiber resulting in a reduction of the required phase modulation.......We demonstrate an increased gain in optical parametric amplier through suppression of stimulated Brillouin scattering by applying a temperature distribution along the fiber resulting in a reduction of the required phase modulation....
Bokhari, Shahid H.; Crockett, Thomas W.; Nicol, David M.
1993-01-01
Binary dissection is widely used to partition non-uniform domains over parallel computers. This algorithm does not consider the perimeter, surface area, or aspect ratio of the regions being generated and can yield decompositions that have poor communication to computation ratio. Parametric Binary Dissection (PBD) is a new algorithm in which each cut is chosen to minimize load + lambda x(shape). In a 2 (or 3) dimensional problem, load is the amount of computation to be performed in a subregion and shape could refer to the perimeter (respectively surface) of that subregion. Shape is a measure of communication overhead and the parameter permits us to trade off load imbalance against communication overhead. When A is zero, the algorithm reduces to plain binary dissection. This algorithm can be used to partition graphs embedded in 2 or 3-d. Load is the number of nodes in a subregion, shape the number of edges that leave that subregion, and lambda the ratio of time to communicate over an edge to the time to compute at a node. An algorithm is presented that finds the depth d parametric dissection of an embedded graph with n vertices and e edges in O(max(n log n, de)) time, which is an improvement over the O(dn log n) time of plain binary dissection. Parallel versions of this algorithm are also presented; the best of these requires O((n/p) log(sup 3)p) time on a p processor hypercube, assuming graphs of bounded degree. How PBD is applied to 3-d unstructured meshes and yields partitions that are better than those obtained by plain dissection is described. Its application to the color image quantization problem is also discussed, in which samples in a high-resolution color space are mapped onto a lower resolution space in a way that minimizes the color error.
Mechanical Parametric Oscillations and Waves
Dittrich, William; Minkin, Leonid; Shapovalov, Alexander S.
2013-01-01
Usually parametric oscillations are not the topic of general physics courses. Probably it is because the mathematical theory of this phenomenon is relatively complicated, and until quite recently laboratory experiments for students were difficult to implement. However parametric oscillations are good illustrations of the laws of physics and can be…
Spontaneous pneumothorax in weightlifters.
Marnejon, T; Sarac, S; Cropp, A J
1995-06-01
Spontaneous pneumothorax is infrequently caused by strenuous exertion. To our knowledge there has only been one case of spontaneous pneumothorax associated with weightlifting reported in the medical literature. We describe three consecutive cases of spontaneous pneumothorax associated with weightlifting. We postulate that spontaneous pneumothorax in these patients may be secondary to improper breathing techniques. It is important that physicians and weight trainers be aware of the association between weight lifting and spontaneous pneumothorax and assure that proper instruction is given to athletes who work with weights.
730-nm optical parametric conversion from near- to short-wave infrared band
DEFF Research Database (Denmark)
Boggio, J.M.C.; Windmiller, J.R.; Knutzen, M.
2008-01-01
A record 730 nm parametric conversion in silica fiber from the near-infrared to the short-wave infrared band is reported and analyzed. A parametric gain in excess of 30 dB was measured for a signal at 1300 nm (with corresponding idler at 2030 nm). This conversion was performed in a travelling sin...... single-pass one-pump parametric architecture and high efficiency is achieved by a combination of high peak power and a nonlinear fiber with a reduced fourth-order dispersion coefficient.......A record 730 nm parametric conversion in silica fiber from the near-infrared to the short-wave infrared band is reported and analyzed. A parametric gain in excess of 30 dB was measured for a signal at 1300 nm (with corresponding idler at 2030 nm). This conversion was performed in a travelling...
Parametric resonances: from the Mathieu equation to QASER
Chen, Goong; Tian, Jing; Bin-Mohsin, Bandar; Nessler, Reed; Svidzinsky, Anatoly; Scully, Marlan O.
2016-07-01
Combination resonances produced by periodic modulation of parameters can generate substantial gains in new light amplifiers, acronymed QASER (quantum amplification by superradiant emission of radiation). Here we study such gains and investigate their parametric resonance spectral patterns. We use the Floquet theory and develop a projection method that can properly capture gains near the primary resonance and subharmonic frequencies for the Mathieu equation and QASER. We dedicate this paper to the memory of Richard Lewis Arnowitt a pioneer of many-body theory, a pathfinder at the interface of gravity and quantum mechanics, and a true leader in quantum field theory.
Parametric Verification of Weighted Systems
DEFF Research Database (Denmark)
Christoffersen, Peter; Hansen, Mikkel; Mariegaard, Anders
2015-01-01
This paper addresses the problem of parametric model checking for weighted transition systems. We consider transition systems labelled with linear equations over a set of parameters and we use them to provide semantics for a parametric version of weighted CTL where the until and next operators...... are themselves indexed with linear equations. The parameters change the model-checking problem into a problem of computing a linear system of inequalities that characterizes the parameters that guarantee the satisfiability. To address this problem, we use parametric dependency graphs (PDGs) and we propose...
Parametric Mass Reliability Study
Holt, James P.
2014-01-01
The International Space Station (ISS) systems are designed based upon having redundant systems with replaceable orbital replacement units (ORUs). These ORUs are designed to be swapped out fairly quickly, but some are very large, and some are made up of many components. When an ORU fails, it is replaced on orbit with a spare; the failed unit is sometimes returned to Earth to be serviced and re-launched. Such a system is not feasible for a 500+ day long-duration mission beyond low Earth orbit. The components that make up these ORUs have mixed reliabilities. Components that make up the most mass-such as computer housings, pump casings, and the silicon board of PCBs-typically are the most reliable. Meanwhile components that tend to fail the earliest-such as seals or gaskets-typically have a small mass. To better understand the problem, my project is to create a parametric model that relates both the mass of ORUs to reliability, as well as the mass of ORU subcomponents to reliability.
Non-parametric versus parametric methods in environmental sciences
Directory of Open Access Journals (Sweden)
Muhammad Riaz
2017-06-01
Full Text Available This current report intends to highlight the importance of considering background assumptions required for the analysis of real datasets in different disciplines. We will provide comparative discussion of parametric methods (that depends on distributional assumptions (like normality relative to non-parametric methods (that are free from many distributional assumptions. We have chosen a real dataset from environmental sciences (one of the application areas. The findings may be extended to the other disciplines following the same spirit.
Siddiqui, Aleem M; Moses, Jeffrey; Hong, Kyung-Han; Lai, Chien-Jen; Kärtner, Franz X
2010-06-15
We show that an enhancement cavity seeded at the full repetition rate of the pump laser can automatically reshape small-signal gain across the interacting pulses in an optical parametric chirped-pulse amplifier for close-to-optimal operation, significantly increasing both the gain bandwidth and the conversion efficiency, in addition to boosting gain for high-repetition-rate amplification. Applied to a degenerate amplifier, the technique can provide an octave-spanning gain bandwidth.
Azimuthal spectrum after parametric down-convertion with radial degrees of freedom
CSIR Research Space (South Africa)
Zhang, Y
2014-08-01
Full Text Available Considering the quantum state produced in type I spontaneous parametric down-conversion with collinear, degenerate signal and idler beams, and a Gaussian pump, we show that the azimuthal Schmidt number in the Laguerre-Gaussian (LG) basis increases...
Raman and loss induced quantum noise in depleted fiber optical parametric amplifiers
DEFF Research Database (Denmark)
Friis, Søren Michael Mørk; Rottwitt, Karsten; McKinstrie, C. J.
2013-01-01
We present a semi-classical approach for predicting the quantum noise properties of fiber optical parametric amplifiers. The unavoidable contributors of noise, vacuum fluctuations, loss-induced noise, and spontaneous Raman scattering, are included in the analysis of both phase-insensitive and phase...
The parametric resonance—from LEGO Mindstorms to cold atoms
Kawalec, Tomasz; Sierant, Aleksandra
2017-07-01
We show an experimental setup based on a popular LEGO Mindstorms set, allowing us to both observe and investigate the parametric resonance phenomenon. The presented method is simple but covers a variety of student activities like embedded software development, conducting measurements, data collection and analysis. It may be used during science shows, as part of student projects and to illustrate the parametric resonance in mechanics or even quantum physics, during lectures or classes. The parametrically driven LEGO pendulum gains energy in a spectacular way, increasing its amplitude from 10° to about 100° within a few tens of seconds. We provide also a short description of a wireless absolute orientation sensor that may be used in quantitative analysis of driven or free pendulum movement.
Parametric Optimization of Hospital Design
DEFF Research Database (Denmark)
Holst, Malene Kirstine; Kirkegaard, Poul Henning; Christoffersen, L.D.
2013-01-01
Present paper presents a parametric performancebased design model for optimizing hospital design. The design model operates with geometric input parameters defining the functional requirements of the hospital and input parameters in terms of performance objectives defining the design requirements...
Planar Parametrization in Isogeometric Analysis
DEFF Research Database (Denmark)
Gravesen, Jens; Evgrafov, Anton; Nguyen, Dang-Manh
2012-01-01
Before isogeometric analysis can be applied to solving a partial differential equation posed over some physical domain, one needs to construct a valid parametrization of the geometry. The accuracy of the analysis is affected by the quality of the parametrization. The challenge of computing...... and maintaining a valid geometry parametrization is particularly relevant in applications of isogemetric analysis to shape optimization, where the geometry varies from one optimization iteration to another. We propose a general framework for handling the geometry parametrization in isogeometric analysis and shape...... are suitable for our framework. The non-linear methods we consider are based on solving a constrained optimization problem numerically, and are divided into two classes, geometry-oriented methods and analysis-oriented methods. Their performance is illustrated through a few numerical examples....
Self-designing parametric geometries
Sobester, Andras
2015-01-01
The thesis of this paper is that script-based geometry modelling offers the possibility of building `self-designing' intelligence into parametric airframe geometries. We show how sophisticated heuristics (such as optimizers and complex decision structures) can be readily integrated into the parametric geometry model itself using a script-driven modelling architecture. The result is an opportunity for optimization with the scope of conceptual design and the fidelity of preliminary design. Addi...
Parametric Coding of Stereo Audio
Directory of Open Access Journals (Sweden)
Erik Schuijers
2005-06-01
Full Text Available Parametric-stereo coding is a technique to efficiently code a stereo audio signal as a monaural signal plus a small amount of parametric overhead to describe the stereo image. The stereo properties are analyzed, encoded, and reinstated in a decoder according to spatial psychoacoustical principles. The monaural signal can be encoded using any (conventional audio coder. Experiments show that the parameterized description of spatial properties enables a highly efficient, high-quality stereo audio representation.
Experimental investigation of parametric and externally forced motion in resonant MEMS sensors
International Nuclear Information System (INIS)
Harish, K M; Gallacher, B J; Burdess, J S; Neasham, J A
2009-01-01
In this paper an excitation method employing both harmonic forcing and parametric excitation is applied to a resonant MEMS sensor in order to investigate and characterize the phenomena of parametric resonance and parametric amplification. The motivation for this research is that parametric excitation may be used to significantly reduce the total damping in MEMS sensors in a controllable manner. This is extremely pertinent to devices where the Q-factor is a principal factor in determining sensor performance. In this paper it is shown that, by adjusting the parametric excitation parameters (frequency, amplitude and phase) of an electrostatically actuated and sensed device, the gain of the frequency response function of a mode of vibration may be amplified. The amplification is quantified by the gain factor which is characterized experimentally. The instability regions defining the regions for parametric resonance are also characterized experimentally and compared to theoretical predictions. The boundaries of these instability regions define the thresholds for parametric resonance and play a crucial role in the design of the parametric amplifier
PARAMETRIC ROSE AS A SUBJECT OF MATHEMATICS, PROGRAMMING, AESTHETICS.
Directory of Open Access Journals (Sweden)
Yevgeny Gayev
2017-01-01
Full Text Available By using MATLAB we demonstrate a variety of parametric curves of the family "Parametric Rose" (Rhodonea, characterized by four factors. The article is intended to encourage students to study the parametric curves. The values of coefficients affect the shape of the curve and its period. Changes with time one of the curve parameters makes the effect of animation. Different versions of coloring the curve increase the aesthetic impact on results. A beautiful MATLAB-program with Graphical User Interface (GUI is suggested. It allows students to "play" with the curves on the computer screen and demonstrates amazing properties of the "Rose" parametric family depending on the values and the ratio of their coefficients. It may allow and teachers to inspire students by exploring these additional non-school materials. Students can see the beauty of mathematics and gain additional knowledge about parametric functions. From another side, the program provides an exercise example of algorithms and programming accessible for modern students. Animation of curves proposed can also serve as exercises both for mathematics and programming.
African Journals Online (AJOL)
ABSTRACT. Rupture of a gravid uterus is a surgical emergency. Predisposing factors include a scarred uterus. Spontaneous rupture of an unscarred uterus during pregnancy is a rare occurrence. We hereby present the case of a spontaneous complete uterine rupture at a gestational age of 34 weeks in a 35 year old patient ...
Spontaneous intracranial hypotension.
LENUS (Irish Health Repository)
Fullam, L
2012-01-31
INTRODUCTION: Spontaneous\\/primary intracranial hypotension is characterised by orthostatic headache and is associated with characteristic magnetic resonance imaging findings. CASE REPORT: We present a case report of a patient with typical symptoms and classical radiological images. DISCUSSION: Spontaneous intracranial hypotension is an under-recognised cause of headache and can be diagnosed by history of typical orthostatic headache and findings on MRI brain.
International Nuclear Information System (INIS)
Baker, C.
1994-10-01
The Department of Energy's (DOE) Hanford site near Richland, Washington is being cleaned up after 50 years of nuclear materials production. One of the most serious problems at the site is the waste stored in single-shell underground storage tanks. There are 149 of these tanks containing the spent fuel residue remaining after the fuel is dissolved in acid and the desired materials (primarily plutonium and uranium) are separated out. The tanks are upright cylinders 75 ft. in diameter with domed tops. They are made of reinforced concrete, have steel liners, and each tank is buried under 7--12 ft. of overburden. The tanks are up to 40-ft. high, and have capacities of 500,000, 750,000, or 1,000,000 gallons of waste. As many as one-third of these tanks are known or suspected to leak. The waste form contained in the tanks varies in consistency from liquid supernatant to peanut-butter-like gels and sludges to hard salt cake (perhaps as hard as low-grade concrete). The current waste retrieval plan is to insert a large long-reach manipulator through a hole cut in the top of the tank, and use a variety of end-effectors to mobilize the waste and remove it from the tank. PNL has, with the assistance of Deneb robotics employees, developed a means of using the IGRIP code to perform parametric design of mechanical systems. This method requires no modifications to the IGRIP code, and all design data are stored in the IGRIP workcell. The method is presented in the context of development of a passive articulated mechanism that is used to deliver down-arm services to a gantry robot. The method is completely general, however, and could be used to design a fully articulated manipulator. Briefly, the method involves using IGCALC expressions to control manipulator joint angles, and IGCALC variables to allow user control of link lengths and offsets. This paper presents the method in detail, with examples drawn from PNL's experience with the gantry robot service-providing mechanism
Optical parametrically gated microscopy in scattering media.
Zhao, Youbo; Adie, Steven G; Tu, Haohua; Liu, Yuan; Graf, Benedikt W; Chaney, Eric J; Marjanovic, Marina; Boppart, Stephen A
2014-09-22
High-resolution imaging in turbid media has been limited by the intrinsic compromise between the gating efficiency (removal of multiply-scattered light background) and signal strength in the existing optical gating techniques. This leads to shallow depths due to the weak ballistic signal, and/or degraded resolution due to the strong multiply-scattering background--the well-known trade-off between resolution and imaging depth in scattering samples. In this work, we employ a nonlinear optics based optical parametric amplifier (OPA) to address this challenge. We demonstrate that both the imaging depth and the spatial resolution in turbid media can be enhanced simultaneously by the OPA, which provides a high level of signal gain as well as an inherent nonlinear optical gate. This technology shifts the nonlinear interaction to an optical crystal placed in the detection arm (image plane), rather than in the sample, which can be used to exploit the benefits given by the high-order parametric process and the use of an intense laser field. The coherent process makes the OPA potentially useful as a general-purpose optical amplifier applicable to a wide range of optical imaging techniques.
Short-pulse propagation in fiber optical parametric amplifiers
DEFF Research Database (Denmark)
Cristofori, Valentina
Fiber optical parametric amplifiers (FOPAs) are attractive because they can provide large gain over a broad range of central wavelengths, depending only on the availability of a suitable pump laser. In addition, FOPAs are suitable for the realization of all-optical signal processing functionalities...... is implemented to obtain an all-fiber system. The advantages of all fiber-systems are related to their reliability, long-term stability and compactness. Fiber optical parametric chirped pulse amplification is promising for the amplification of such signals thanks to the inherent compatibility of FOPAs with fiber...... optical systems and high gain over broad bandwidths. In particular, the amplification of 400 fs pulses is investigated in a single-pump fiber optical chirped pulse amplification sc heme. First, a dynamic characterization is carried out both in unsaturated and saturated regimes and, then, amplification...
Ionospheric modification and parametric instabilities
International Nuclear Information System (INIS)
Fejer, J.A.
1979-01-01
Thresholds and linear growth rates for stimulated Brillouin and Raman scattering and for the parametric decay instability are derived by using arguments of energy transfer. For this purpose an expression for the ponderomotive force is derived. Conditions under which the partial pressure force due to differential dissipation exceeds the ponderomotive force are also discussed. Stimulated Brillouin and Raman scattering are weakly excited by existing incoherent backscatter radars. The parametric decay instability is strongly excited in ionospheric heating experiments. Saturation theories of the parametric decay instability are therefore described. After a brief discussion of the purely growing instability the effect of using several pumps is discussed as well as the effects of inhomogenicity. Turning to detailed theories of ionospheric heating, artificial spread F is discussed in terms of a purely growing instability where the nonlinearity is due to dissipation. Field-aligned short-scale striations are explained in terms of dissipation of the parametrically excited Langmuir waves (plasma oscillations): they might be further amplified by an explosive instability (except the magnetic equator). Broadband absorption is probably responsible for the 'overshoot' effect: the initially observed level of parametrically excited Langmuir waves is much higher than the steady state level
Parametric functional principal component analysis.
Sang, Peijun; Wang, Liangliang; Cao, Jiguo
2017-09-01
Functional principal component analysis (FPCA) is a popular approach in functional data analysis to explore major sources of variation in a sample of random curves. These major sources of variation are represented by functional principal components (FPCs). Most existing FPCA approaches use a set of flexible basis functions such as B-spline basis to represent the FPCs, and control the smoothness of the FPCs by adding roughness penalties. However, the flexible representations pose difficulties for users to understand and interpret the FPCs. In this article, we consider a variety of applications of FPCA and find that, in many situations, the shapes of top FPCs are simple enough to be approximated using simple parametric functions. We propose a parametric approach to estimate the top FPCs to enhance their interpretability for users. Our parametric approach can also circumvent the smoothing parameter selecting process in conventional nonparametric FPCA methods. In addition, our simulation study shows that the proposed parametric FPCA is more robust when outlier curves exist. The parametric FPCA method is demonstrated by analyzing several datasets from a variety of applications. © 2017, The International Biometric Society.
Antidepressants and Weight Gain
Antidepressants and weight gain: What causes it? Can antidepressants cause weight gain? Answers from Daniel K. Hall- ... is a possible side effect of nearly all antidepressants. However, each person responds to antidepressants differently. Some ...
An extended parametrization of gas amplification in proportional wire chambers
International Nuclear Information System (INIS)
Beingessner, S.P.; Carnegie, R.K.; Hargrove, C.K.
1987-01-01
It is normally assumed that the gas amplification in proportional chambers is a function of Townsend's first ionization coefficient, α, and that α is a function of the anode surface electric field only. Experimental measurements are presented demonstrating the breakdown of the latter assumption for electric fields, X, greater than about 150 V/cm/Torr on the anode wire surface for a gas mixture of 80/20 argon/methane. For larger values of X, the parametrization of the proportional gas gain data requires an additional term related to the gradient of the electric field near the wire. This extended gain parametrization remains valid until the onset of nonproportional contributions such as positive ion space charge saturation effects. Furthermore, deviations of the data from this parametrization are used to measure the onset of these space charge effects. A simple scaling dependence of the gain data on the product of pressure and wire radius over the whole proportional range is also demonstrated. (orig.)
Josephson parametric converter saturation and higher order effects
Liu, G.; Chien, T.-C.; Cao, X.; Lanes, O.; Alpern, E.; Pekker, D.; Hatridge, M.
2017-11-01
Microwave parametric amplifiers based on Josephson junctions have become indispensable components of many quantum information experiments. One key limitation which has not been well predicted by theory is the gain saturation behavior which limits the amplifier's ability to process large amplitude signals. The typical explanation for this behavior in phase-preserving amplifiers based on three-wave mixing, such as the Josephson Parametric Converter, is pump depletion, in which the consumption of pump photons to produce amplification results in a reduction in gain. However, in this work, we present experimental data and theoretical calculations showing that the fourth-order Kerr nonlinearities inherent in Josephson junctions are the dominant factor. The Kerr-based theory has the unusual property of causing saturation to both lower and higher gains, depending on bias conditions. This work presents an efficient methodology for optimizing device performance in the presence of Kerr nonlinearities while retaining device tunability and points to the necessity of controlling higher-order Hamiltonian terms to make further improvements in parametric devices.
Optical parametric amplification and oscillation assisted by low-frequency stimulated emission.
Longhi, Stefano
2016-04-15
Optical parametric amplification and oscillation provide powerful tools for coherent light generation in spectral regions inaccessible to lasers. Parametric gain is based on a frequency down-conversion process and, thus, it cannot be realized for signal waves at a frequency ω3 higher than the frequency of the pump wave ω1. In this Letter, we suggest a route toward the realization of upconversion optical parametric amplification and oscillation, i.e., amplification of the signal wave by a coherent pump wave of lower frequency, assisted by stimulated emission of the auxiliary idler wave. When the signal field is resonated in an optical cavity, parametric oscillation is obtained. Design parameters for the observation of upconversion optical parametric oscillation at λ3=465 nm are given for a periodically poled lithium-niobate (PPLN) crystal doped with Nd(3+) ions.
Ma, Y. B.; Liu, J.; Ma, Y. Q.; Zhao, C.; Ju, L.; Blair, D. G.; Zhu, Z. H.
2017-07-01
Three-mode parametric instability is a threat to attaining design power levels in advanced gravitational wave detectors. The first observation of three-mode parametric instability in a long optical cavity revealed that instabilities could be suppressed by time variation of the mirror radius of curvature. In this paper, we present three dimensional finite element analysis of this thermo-acousto-optics system to determine whether thermal modulation could provide sufficient instability suppression without degrading time averaged optical performance. It is shown that deformations due to the time averaged heating profile on the mirror surface can be compensated by rear surface heating of the test mass. Results show that a heating source with a modulation amplitude of 1 W at 0.01 Hz is sufficient to stabilize an acoustic mode with parametric gain up to 3. The parametric gain suppression factor is linearly proportional to the peak modulation power.
Macromechanical parametric amplification with a base-excited doubly clamped beam
DEFF Research Database (Denmark)
Neumeyer, Stefan; Thomsen, Jon Juel
2013-01-01
Parametric amplification is realized by adding parametric excitation to externally driven near-resonant oscillations. The effect of specific cubic nonlinearities on the parametrically amplified steady-state vibrations and gain is investigated theoretically. Here, gain is defined as the ratio...... of steady-state vibration amplitude of the directly and parametrically excited system, to vibration amplitude of the directly excited only system. The nonlinear effect of midplane stretching is compared to the effects of nonlinear inertia and curvature. An approximate analytical expression for the vibration...... amplitude is derived. For a given small level of transverse displacement for both the cantilever and doubly clamped beam, the effect of midplane stretching is dominant compared to those caused by nonlinear inertia and curvature. It was found that the beam slenderness ratio can be used as an effective design...
Variance in parametric images: direct estimation from parametric projections
International Nuclear Information System (INIS)
Maguire, R.P.; Leenders, K.L.; Spyrou, N.M.
2000-01-01
Recent work has shown that it is possible to apply linear kinetic models to dynamic projection data in PET in order to calculate parameter projections. These can subsequently be back-projected to form parametric images - maps of parameters of physiological interest. Critical to the application of these maps, to test for significant changes between normal and pathophysiology, is an assessment of the statistical uncertainty. In this context, parametric images also include simple integral images from, e.g., [O-15]-water used to calculate statistical parametric maps (SPMs). This paper revisits the concept of parameter projections and presents a more general formulation of the parameter projection derivation as well as a method to estimate parameter variance in projection space, showing which analysis methods (models) can be used. Using simulated pharmacokinetic image data we show that a method based on an analysis in projection space inherently calculates the mathematically rigorous pixel variance. This results in an estimation which is as accurate as either estimating variance in image space during model fitting, or estimation by comparison across sets of parametric images - as might be done between individuals in a group pharmacokinetic PET study. The method based on projections has, however, a higher computational efficiency, and is also shown to be more precise, as reflected in smooth variance distribution images when compared to the other methods. (author)
International Nuclear Information System (INIS)
Gras, S; Zhao, C; Ju, L; Blair, D G
2006-01-01
In this paper, we propose a passive method to suppress parametric instabilities. This method requires the design of a test mass mirror with appropriate loss distribution. We show that localized losses can significantly reduce the parametric gain without degrading the thermal noise for the advanced LIGO configuration. The method can be use individually or in conjunction with other active feed-back methods. We present numerical analysis for both spherical and non-spherical mirrors
730-nm optical parametric conversion from near- to short-wave infrared band.
Chavez Boggio, J M; Windmiller, J R; Knutzen, M; Jiang, R; Bres, C; Alic, N; Stossel, B; Rottwitt, K; Radic, S
2008-04-14
A record 730 nm parametric conversion in silica fiber from the near-infrared to the short-wave infrared band is reported and analyzed. A parametric gain in excess of 30 dB was measured for a signal at 1300 nm (with corresponding idler at 2030 nm). This conversion was performed in a travelling single-pass one-pump parametric architecture and high efficiency is achieved by a combination of high peak power and a nonlinear fiber with a reduced fourth-order dispersion coefficient.
Parametric programming of industrial robots
Directory of Open Access Journals (Sweden)
Szulczyński Paweł
2015-06-01
Full Text Available This article proposes the use of parametric design software, commonly used by architects, in order to obtain complex trajectory and program code for industrial robots. The paper describes the drawbacks of existing solutions and proposes a new script to obtain a correct program. The result of the algorithm was verified experimentally.
Graphical functions in parametric space
Golz, Marcel; Panzer, Erik; Schnetz, Oliver
2017-06-01
Graphical functions are positive functions on the punctured complex plane C{\\setminus }{0,1} which arise in quantum field theory. We generalize a parametric integral representation for graphical functions due to Lam, Lebrun and Nakanishi, which implies the real analyticity of graphical functions. Moreover, we prove a formula that relates graphical functions of planar dual graphs.
PARAMETRIC MODEL OF LUMBAR VERTEBRA
Directory of Open Access Journals (Sweden)
CAPPETTI Nicola
2010-11-01
Full Text Available The present work proposes the realization of a parametric/variational CAD model of a normotype lumbar vertebra, which could be used for improving the effectiveness of actual imaging techniques in informational augmentation of the orthopaedic and traumatological diagnosis. In addition it could be used for ergonomic static and dynamical analysis of the lumbar region and vertebral column.
Parametric instabilities in magnetized plasmas
International Nuclear Information System (INIS)
Sanuki, H.; Schmidt, G.
1976-02-01
A theory is developed for parametric instabilities driven by a finite wavenumber general pump wave. This formalism is applied to describe lower hybrid decay into electromagnetic modes. A separate treatment is given for the all electrostatic wave case using the physically more transparent particle drift equations. In particular, the purely growing mode is studied
Design of parametric software tools
DEFF Research Database (Denmark)
Sabra, Jakob Borrits; Mullins, Michael
2011-01-01
fulfilment of evidence-based design criterion regarding light distribution and location in relation to patient safety in architectural health care design proposals. The study uses 2D/3D CAD modelling software Rhinoceros 3D with plug-in Grasshopper to create parametric tool prototypes to exemplify...
Aircraft Trajectory Optimization Using Parametric Optimization Theory
Valenzuela Romero, Alfonso
2012-01-01
In this thesis, a study of the optimization of aircraft trajectories using parametric optimization theory is presented. To that end, an approach based on the use of predefined trajectory patterns and parametric optimization is proposed. The trajectory pat
Bianchi surfaces: integrability in an arbitrary parametrization
International Nuclear Information System (INIS)
Nieszporski, Maciej; Sym, Antoni
2009-01-01
We discuss integrability of normal field equations of arbitrarily parametrized Bianchi surfaces. A geometric definition of the Bianchi surfaces is presented as well as the Baecklund transformation for the normal field equations in an arbitrarily chosen surface parametrization.
Parametric tools in architecture: a comparative study
Hanna, R
2012-01-01
Parametric tools have recently increased in eminence in\\ud architectural practice with several claims made about their potential as a creative design iteration tool to enhance design decision making and problem solving. This paper carried out a survey of two types of architectural practices: one that predominantly uses non-parametric CAD tools and another that primarily employs parametric CAD. The results from the survey were analysed statistically. The findings show that parametric tools did...
L2-gain and passivity techniques in nonlinear control
van der Schaft, Arjan
2017-01-01
This standard text gives a unified treatment of passivity and L2-gain theory for nonlinear state space systems, preceded by a compact treatment of classical passivity and small-gain theorems for nonlinear input-output maps. The synthesis between passivity and L2-gain theory is provided by the theory of dissipative systems. Specifically, the small-gain and passivity theorems and their implications for nonlinear stability and stabilization are discussed from this standpoint. The connection between L2-gain and passivity via scattering is detailed. Feedback equivalence to a passive system and resulting stabilization strategies are discussed. The passivity concepts are enriched by a generalised Hamiltonian formalism, emphasising the close relations with physical modeling and control by interconnection, and leading to novel control methodologies going beyond passivity. The potential of L2-gain techniques in nonlinear control, including a theory of all-pass factorizations of nonlinear systems, and of parametrization...
Spontaneous Atraumatic Mediastinal Hemorrhage
Directory of Open Access Journals (Sweden)
Morkos Iskander BSc, BMBS, MRCS, PGCertMedEd
2013-04-01
Full Text Available Spontaneous atraumatic mediastinal hematomas are rare. We present a case of a previously fit and well middle-aged lady who presented with acute breathlessness and an increasing neck swelling and spontaneous neck bruising. On plain chest radiograph, widening of the mediastinum was noted. The bruising was later confirmed to be secondary to mediastinal hematoma. This life-threatening diagnostic conundrum was managed conservatively with a multidisciplinary team approach involving upper gastrointestinal and thoracic surgeons, gastroenterologists, radiologists, intensivists, and hematologists along with a variety of diagnostic modalities. A review of literature is also presented to help surgeons manage such challenging and complicated cases.
Interactive Dimensioning of Parametric Models
Kelly, T.
2015-06-22
We propose a solution for the dimensioning of parametric and procedural models. Dimensioning has long been a staple of technical drawings, and we present the first solution for interactive dimensioning: A dimension line positioning system that adapts to the view direction, given behavioral properties. After proposing a set of design principles for interactive dimensioning, we describe our solution consisting of the following major components. First, we describe how an author can specify the desired interactive behavior of a dimension line. Second, we propose a novel algorithm to place dimension lines at interactive speeds. Third, we introduce multiple extensions, including chained dimension lines, controls for different parameter types (e.g. discrete choices, angles), and the use of dimension lines for interactive editing. Our results show the use of dimension lines in an interactive parametric modeling environment for architectural, botanical, and mechanical models.
Parametric Fires for Structural Design
DEFF Research Database (Denmark)
Hertz, Kristian
2012-01-01
The authorities, the construction association, and a number of companies in Denmark have supported the author writing a guide for design of building structures for parametric fires. The guide is published by the ministry as a supplement to the building regulations. However, consultants...... and contractors have asked for a reference in English in order to make the guide-lines and the background for them available internationally. The paper therefore presents recommendations from the design guide especially concerning how to assess parametric design fires based on the opening factor method for large...... compartments. Findings leading to the guide-lines are discussed, and it is indicated what a safe design fire model means for structural design and how it differs from a safe design fire model for evacuation. Furthermore, the paper includes some experiences from the application of the design guide in practise...
Scattering-initiated parametric noise in optical parametric chirped-pulse amplification.
Wang, Jing; Ma, Jingui; Yuan, Peng; Tang, Daolong; Zhou, Binjie; Xie, Guoqiang; Qian, Liejia
2015-07-15
We experimentally study a new kind of parametric noise that is initiated from signal scattering and enhanced through optical parametric amplification. Such scattering-initiated parametric noise behaves similarly to parametric super-fluorescence in the spatial domain, yet is typically much stronger. In the time domain it inherits the chirp of signal pulses and can be well compressed. We demonstrate that scattering-initiated parametric noise has little influence on the pulse contrast but can degrade the energy conversion efficiency substantially.
Parametric decay of the curvaton
International Nuclear Information System (INIS)
Enqvist, K; Nurmi, S; Rigopoulos, G I
2008-01-01
We argue that the curvaton decay takes place most naturally by way of a broad parametric resonance. The mechanism is analogous to resonant inflaton decay but does not require any tuning of the curvaton coupling strength to other scalar fields. For low scale inflation and a correspondingly low mass scale for the curvaton, we speculate on observable consequences including the possibility of stochastic gravitational waves
Parametric characterization of aggregation functions
Czech Academy of Sciences Publication Activity Database
Mesiar, Radko; Kolesárová, A.
2009-01-01
Roč. 160, č. 6 (2009), s. 816-831 ISSN 0165-0114 R&D Projects: GA ČR GA402/08/0618 Institutional research plan: CEZ:AV0Z10750506 Keywords : Aggregation function * Conjunction measure * Disjunction measure * Global/local parametric characterization * Idempotency measure Subject RIV: BA - General Mathematics Impact factor: 2.138, year: 2009 http://library.utia.cas.cz/separaty/2009/E/mesiar-parametriccharacterizationofaggregationfunctions.pdf
Parametric Modeling for Fluid Systems
Pizarro, Yaritzmar Rosario; Martinez, Jonathan
2013-01-01
Fluid Systems involves different projects that require parametric modeling, which is a model that maintains consistent relationships between elements as is manipulated. One of these projects is the Neo Liquid Propellant Testbed, which is part of Rocket U. As part of Rocket U (Rocket University), engineers at NASA's Kennedy Space Center in Florida have the opportunity to develop critical flight skills as they design, build and launch high-powered rockets. To build the Neo testbed; hardware from the Space Shuttle Program was repurposed. Modeling for Neo, included: fittings, valves, frames and tubing, between others. These models help in the review process, to make sure regulations are being followed. Another fluid systems project that required modeling is Plant Habitat's TCUI test project. Plant Habitat is a plan to develop a large growth chamber to learn the effects of long-duration microgravity exposure to plants in space. Work for this project included the design and modeling of a duct vent for flow test. Parametric Modeling for these projects was done using Creo Parametric 2.0.
Parametric instability of a nonuniform plasma near a linear focus
Energy Technology Data Exchange (ETDEWEB)
Arkhipenko, V.I.; Budnikov, V.N.; Gusakov, E.Z.; Romanchuk, I.A.; Simonchik, L.V.
1985-02-01
Parametric instability l ..-->.. l'+s resulting in anomalous reflection of oblique Langmuir waves in a two-dimensionally nonuniform plasma is studied experimentally and theoretically. The experimental results confirm the theoretical prediction that for low input powers, the instability consists in the spatial amplification of ion-sound noise. The scattered signal is found to rise abruptly for spatial gains s> or approx. =10/sup 4/ because the threshold for absolute instability l ..-->.. l'+s is approached. The absolute instability saturates due to depletion of the pump wave, which is almost completely reflected. A mechanism for the generation of cascade parametric turbulence spectra is identified which is specific to nonuniform plasmas.
Tunable single-longitudinal-mode fiber optical parametric oscillator.
Yang, Sigang; Cheung, Kim K Y; Zhou, Yue; Wong, Kenneth K Y
2010-02-15
A tunable single-longitudinal-mode (SLM) fiber optical parametric oscillator (FOPO) is proposed and demonstrated experimentally. A sub-ring cavity with a short cavity length is used to suppress the longitudinal modes and broaden the longitudinal mode spacing. A fiber loop mirror, consisted of an unpumped erbium-doped fiber, acts as an autotracking filter for providing fine mode restriction and ensuring the single-frequency operation. The measurement based on a homodyne method shows that the FOPO provides the SLM output. Furthermore the SLM FOPO can be tunable over 14 nm for each of the signal and the idler, which is limited only by the gain bandwidth of the fiber optical parametric amplifier.
Fonseca, Diogo S; Beda, Alessandro; Miranda de Sá, Antonio M F L; Simpson, David M
2013-11-01
The interaction of respiration and heart-rate variability (HRV), leading to respiratory sinus arrhythmia (RSA) and, in the inverse direction, cardioventilatory coupling has been subject of much study and controversy. A parametric linear feedback model can be used to study these interactions. In order to investigate differences between inspiratory and expiratory periods, we propose that models are estimated separately for each period, by finding least mean square estimates only over the desired signal segments. This approach was tested in simulated data and heart-rate and respiratory air flow signals recorded from 25 young healthy adults (13 men and 12 women), at rest, breathing spontaneously through a face mask for 5 min. The results show significant differences (pinspiration and expiration periods. Simple and causal coherence from respiration to HRV was higher during inspiration than expiration. The estimates of gain also differed significantly in the high frequency (HF) band (0.15-0.5Hz) between those obtained from the whole recording, and the inspiratory and expiratory periods. These results indicate that a single linear model fitted to the whole recording neglects potentially important differences between inspiration and expiration, and the current paper shows how such differences can be estimated, without the need to control breathing. Copyright © 2013 Elsevier B.V. All rights reserved.
Spontaneous Appendicocutaneous Fistula I
African Journals Online (AJOL)
M T0k0de* MB, BS and. Dr 0. A. AWOj0bi+ FMCS (Nig). ABSTRACT. Ruptured appendicitis is not a common cause of spontaneous enterocutaneous ﬁstula. A case of ruptured retrocaecal appendicitis presenting as an enterocutaneous ﬁstula in a Nigerian woman is presented. The literature on this disorder is also reviewed.
[Spontaneous bacterial peritonitis].
Strauss, Edna; Caly, Wanda Regina
2003-01-01
Spontaneous bacterial peritonitis occurs in 30% of patients with ascites due to cirrhosis leading to high morbidity and mortality rates. The pathogenesis of spontaneous bacterial peritonitis is related to altered host defenses observed in end-stage liver disease, overgrowth of microorganisms, and bacterial translocation from the intestinal lumen to mesenteric lymph nodes. Clinical manifestations vary from severe to slight or absent, demanding analysis of the ascitic fluid. The diagnosis is confirmed by a number of neutrophils over 250/mm3 associated or not to bacterial growth in culture of an ascites sample. Enterobacteriae prevail and Escherichia coli has been the most frequent bacterium reported. Mortality rates decreased markedly in the last two decades due to early diagnosis and prompt antibiotic treatment. Third generation intravenous cephalosporins are effective in 70% to 95% of the cases. Recurrence of spontaneous bacterial peritonitis is common and can be prevented by the continuous use of oral norfloxacin. The development of bacterial resistance demands the search for new options in the prophylaxis of spontaneous bacterial peritonitis; probiotics are a promising new approach, but deserve further evaluation. Short-term antibiotic prophylaxis is recommended for patients with cirrhosis and ascites shortly after an acute episode of gastrointestinal bleeding.
Spontaneous Grammar Explanations.
Tjoo, Hong Sing; Lewis, Marilyn
1998-01-01
Describes one New Zealand university language teacher's reflection on her own grammar explanations to university-level students of Bahasa Indonesian. Examines form-focused instruction through the teacher's spontaneous answers to students' questions about the form of the language they are studying. The teacher's experiences show that it takes time…
EDITORIAL SPONTANEOUS BACTERIAL PERITONITIS ...
African Journals Online (AJOL)
hi-tech
Spontaneous bacterial peritonitis (SBP) frequent]y occurs in patients with liver cirrhosis and ascites. It is defined as an infection of previously sterile ascitic fluid without any demonstrable intrabdominal source of infection. It is now internationally agreed that a polymorphonuclear (PMN) cell count in the ascitic fluid of over 250 ...
Spontaneous dimensional reduction?
Carlip, Steven
2012-10-01
Over the past few years, evidence has begun to accumulate suggesting that spacetime may undergo a "spontaneous dimensional reduction" to two dimensions near the Planck scale. I review some of this evidence, and discuss the (still very speculative) proposal that the underlying mechanism may be related to short-distance focusing of light rays by quantum fluctuations.
Parametric amplification and bidirectional invisibility in PT -symmetric time-Floquet systems
Koutserimpas, Theodoros T.; Alù, Andrea; Fleury, Romain
2018-01-01
Parity-time (PT )-symmetric wave devices, which exploit balanced interactions between material gain and loss, exhibit extraordinary properties, including lasing and flux-conserving scattering processes. In a seemingly different research field, periodically driven systems, also known as time-Floquet systems, have been widely studied as a relevant platform for reconfigurable active wave control and manipulation. In this article, we explore the connection between PT -symmetry and parametric time-Floquet systems. Instead of relying on material gain, we use parametric amplification by considering a time-periodic modulation of the refractive index at a frequency equal to twice the incident signal frequency. We show that the scattering from a simple parametric slab, whose dynamics follows the Mathieu equation, can be described by a PT -symmetric scattering matrix, whose PT -breaking threshold corresponds to the Mathieu instability threshold. By combining different parametric slabs modulated out of phase, we create PT -symmetric time-Floquet systems that feature exceptional scattering properties, such as coherent perfect absorption (CPA)-laser operation and bidirectional invisibility. These bidirectional properties, rare for regular PT -symmetric systems, are related to a compensation of parametric amplification due to multiple scattering between two parametric systems modulated with a phase difference.
Digital spectral analysis parametric, non-parametric and advanced methods
Castanié, Francis
2013-01-01
Digital Spectral Analysis provides a single source that offers complete coverage of the spectral analysis domain. This self-contained work includes details on advanced topics that are usually presented in scattered sources throughout the literature.The theoretical principles necessary for the understanding of spectral analysis are discussed in the first four chapters: fundamentals, digital signal processing, estimation in spectral analysis, and time-series models.An entire chapter is devoted to the non-parametric methods most widely used in industry.High resolution methods a
DEFF Research Database (Denmark)
Lorenzen, Michael Rodas; Noordegraaf, Danny; Nielsen, Carsten Vandel
2009-01-01
An increased gain in a fibre-optical parametric amplifier through suppression of stimulated Brillouin scattering is demonstrated by applying a temperature distribution along the fibre for a fixed phase modulation of the pump. The temperature distribution slightly impacts the gain spectrum....
Spontaneous healing of spontaneous coronary artery dissection.
Almafragi, Amar; Convens, Carl; Heuvel, Paul Van Den
2010-01-01
Spontaneous coronary artery dissection (SCAD) is a rare cause of acute coronary syndrome and sudden cardiac death. It should be suspected in every healthy young woman without cardiac risk factors, especially during the peripartum or postpartum periods. It is important to check for a history of drug abuse, collagen vascular disease or blunt trauma of the chest. Coronary angiography is essential for diagnosis and early management. We wonder whether thrombolysis might aggravate coronary dissection. All types of treatment (medical therapy, percutaneous intervention or surgery) improve the prognosis without affecting survival times if used appropriately according to the clinical stability and the angiographic features of the involved coronary arteries. Prompt recognition and targeted treatment improve outcomes. We report a case of SCAD in a young female free of traditional cardiovascular risk factors, who presented six hours after thrombolysis for ST elevation myocardial infarction. Coronary angiography showed a dissection of the left anterior descending and immediate branch. She had successful coronary artery bypass grafting, with complete healing of left anterior descending dissection.
Parametric Thinking in Urban Design
DEFF Research Database (Denmark)
Steinø, Nicolai
2010-01-01
the application of complex and expensive technolo- gies are mostly absent, although they seem appropriate in urban de- sign. A survey of existing approaches confirms the statement, and an example of the application of basic knowledge of geometry and para- metric thinking to urban design forms the argument......The paper states that most applications of parametric mod- elling to architecture and urban design fall into one of two strands of either form for form’s sake, or the negotiation of environmental con- cerns, while approaches which allow scenarios to be easily tested and modified without...
Study of parametric instability in gravitational wave detectors with silicon test masses
International Nuclear Information System (INIS)
Zhang, Jue; Zhao, Chunnong; Ju, Li; Blair, David
2017-01-01
Parametric instability is an intrinsic risk in high power laser interferometer gravitational wave detectors, in which the optical cavity modes interact with the acoustic modes of the mirrors, leading to exponential growth of the acoustic vibration. In this paper, we investigate the potential parametric instability for a proposed next generation gravitational wave detector, the LIGO Voyager blue design, with cooled silicon test masses of size 45 cm in diameter and 55 cm in thickness. It is shown that there would be about two unstable modes per test mass at an arm cavity power of 3 MW, with the highest parametric gain of ∼76. While this is less than the predicted number of unstable modes for Advanced LIGO (∼40 modes with max gain of ∼32 at the designed operating power of 830 kW), the importance of developing suitable instability suppression schemes is emphasized. (paper)
Spontaneous spinal epidural abscess.
LENUS (Irish Health Repository)
Ellanti, P
2011-10-01
Spinal epidural abscess is an uncommon entity, the frequency of which is increasing. They occur spontaneously or as a complication of intervention. The classical triad of fever, back pain and neurological symptoms are not always present. High index of suspicion is key to diagnosis. Any delay in diagnosis and treatment can have significant neurological consequences. We present the case of a previously well man with a one month history of back pain resulting from an epidural abscess.
Parametric nanomechanical amplification at very high frequency.
Karabalin, R B; Feng, X L; Roukes, M L
2009-09-01
Parametric resonance and amplification are important in both fundamental physics and technological applications. Here we report very high frequency (VHF) parametric resonators and mechanical-domain amplifiers based on nanoelectromechanical systems (NEMS). Compound mechanical nanostructures patterned by multilayer, top-down nanofabrication are read out by a novel scheme that parametrically modulates longitudinal stress in doubly clamped beam NEMS resonators. Parametric pumping and signal amplification are demonstrated for VHF resonators up to approximately 130 MHz and provide useful enhancement of both resonance signal amplitude and quality factor. We find that Joule heating and reduced thermal conductance in these nanostructures ultimately impose an upper limit to device performance. We develop a theoretical model to account for both the parametric response and nonequilibrium thermal transport in these composite nanostructures. The results closely conform to our experimental observations, elucidate the frequency and threshold-voltage scaling in parametric VHF NEMS resonators and sensors, and establish the ultimate sensitivity limits of this approach.
Polyaffine parametrization of image registration based on geodesic flows
DEFF Research Database (Denmark)
Hansen, Michael Sass; Thorup, Signe Strann; Warfield, Simon K.
2012-01-01
Image registration based on geodesic flows has gained much popularity in recent years. We describe a novel parametrization of the velocity field in a stationary flow equation. We show that the method offers both precision, flexibility, and simplicity of evaluation. With our representation, which ...... of geodesic shooting for computational anatomy. We avoid to do warp field convolution by interpolation in a dense field, we can easily calculate warp derivatives in a reference frame of choice, and we can consequently avoid interpolation in the image space altogether....
Optimal Operation of a Josephson Parametric Amplifier for Vacuum Squeezing
Malnou, M.; Palken, D. A.; Vale, Leila R.; Hilton, Gene C.; Lehnert, K. W.
2018-04-01
A Josephson parametric amplifier (JPA) can create squeezed states of microwave light, lowering the noise associated with certain quantum measurements. We experimentally study how the JPA's pump influences the phase-sensitive amplification and deamplification of a coherent tone's amplitude when that amplitude is commensurate with vacuum fluctuations. We predict and demonstrate that, by operating the JPA with a single current pump whose power is greater than the value that maximizes gain, the amplifier distortion is reduced and, consequently, squeezing is improved. Optimizing the singly pumped JPA's operation in this fashion, we directly observe 3.87 ±0.03 dB of vacuum squeezing over a bandwidth of 30 MHz.
Externally pumped millimeter-wave Josephson-junction parametric amplifier
DEFF Research Database (Denmark)
Levinsen, M.T; Pedersen, Niels Falsig; Sørensen, Ole
1980-01-01
A unified theory of the singly and doubly degenerate Josephson-junction parametric amplifier is presented. Experiments with single junctions on both amplifier modes at frequencies 10, 35, and 70 GHz are discussed. Low-noise temperature (∼100 K, single sideband (SSB)) and reasonable gain (∼8 d......B) were obtained at 35 GHz in the singly degenerate mode. On the basis of the theory and experiments, a general procedure for optimizing junction parameters is discussed and illustrated by the specific design of a 100-GHz amplifier....
Full and semi-analytic analyses of two-pump parametric amplification with pump depletion
DEFF Research Database (Denmark)
Steffensen, Henrik; Ott, Johan Raunkjær; Rottwitt, Karsten
2011-01-01
This paper solves the four coupled equations describing non-degenerate four-wave mixing, with the focus on amplifying a signal in a fiber optical parametric amplifier (FOPA). Based on the full analytic solution, a simple approximate solution describing the gain is developed. The advantage of this...... gain spectrum with a bandwidth in the 100-nm range, centered on the zero-dispersion wavelength. When running the FOPA in depletion, this range can be slightly increased. © 2011 Optical Society of America....
Gauge and parametrization ambiguity in quantum gravity
Gonçalves, Jeferson D.; Netto, Tibério de Paula; Shapiro, Ilya L.
2018-01-01
The gauge and parametrization dependence is discussed in quantum gravity in an arbitrary dimension D . Explicit one-loop calculations are performed within the most general parametrization of quantum metric with seven arbitrary parameters. On the other hand, some of the gauge fixing parameters are fixed to make the calculations relatively simple. We confirm the general theorem stating that the on shell local terms in the one-loop effective action are independent of the gauge and parametrization ambiguity.
A general approach to optomechanical parametric instabilities
International Nuclear Information System (INIS)
Evans, M.; Barsotti, L.; Fritschel, P.
2010-01-01
We present a simple feedback description of parametric instabilities which can be applied to a variety of optical systems. Parametric instabilities are of particular interest to the field of gravitational-wave interferometry where high mechanical quality factors and a large amount of stored optical power have the potential for instability. In our use of Advanced LIGO as an example application, we find that parametric instabilities, if left unaddressed, present a potential threat to the stability of high-power operation.
Parametric programming of CNC machine tools
Directory of Open Access Journals (Sweden)
Gołębski Rafał
2017-01-01
Full Text Available The article presents the possibilities of parametric programming of CNC machine tools for the SINUMERIK 840D sl control system. The kinds and types of the definition of variables for the control system under discussion described. On the example of the longitudinal cutting cycle, parametric programming possibilities are shown. The program’s code and its implementation in the control system is described in detail. The principle of parametric programming in a high-level language is also explained.
DEFF Research Database (Denmark)
Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Rishøj, Lars Søgaard
2013-01-01
We show a first-time demonstration of amplification of 400 fs pulses in a fiber optical parametric amplifier. The 400 fs signal is stretched in time, amplified by 26 dB and compressed back to 500 fs. A significant broadening of the pulses is experimentally shown due to dispersion and limited gain...
Parametric uncertainty or hydrological changes?
Directory of Open Access Journals (Sweden)
F. Viola
2014-09-01
Full Text Available The model calibration is the way of hydrologists for searching also a physical interpretation of complex interactions acting within a basin. Actually, it can be frequently noticed how model calibration performed on a given time-window may converge to a point in the parameter space that could be distant from another obtainable calibration of the model in the same basin but considering a different time window. Is that again parametric uncertainty or does the trajectory in the parametric space relate about to a slow hydrological basin change? This paper depicts a possible path for detecting changes' signatures in a streamflow time series. In particular, the paper seeks to draw a way to discern the random variability over different time-windows of the calibrated model parameters set from that induced by the variation in time of some boundary conditions and external forcings. To this purpose, we will refer to a conceptual lumped model for simulating daily streamflow, the EHSM (EcoHydrological Streamflow Model, and to a hypothetical case study. The selected hydrological model requires a total of seven parameters, some of which can be easily related to land use, while others rely on climate variables. The calibration of the EHSM parameters with regard to different time-windows and the analysis of potential impacts of the anthropic variation in land use and/or climatic variability on the calibrated parameters set, will support our investigation.
Parametric Study of Sealant Nozzle
Yamamoto, Yoshimi
It has become apparent in recent years the advancement of manufacturing processes in the aerospace industry. Sealant nozzles are a critical device in the use of fuel tank applications for optimal bonds and for ground service support and repair. Sealants has always been a challenging area for optimizing and understanding the flow patterns. A parametric study was conducted to better understand geometric effects of sealant flow and to determine whether the sealant rheology can be numerically modeled. The Star-CCM+ software was used to successfully develop the parametric model, material model, physics continua, and simulate the fluid flow for the sealant nozzle. The simulation results of Semco sealant nozzles showed the geometric effects of fluid flow patterns and the influences from conical area reduction, tip length, inlet diameter, and tip angle parameters. A smaller outlet diameter induced maximum outlet velocity at the exit, and contributed to a high pressure drop. The conical area reduction, tip angle and inlet diameter contributed most to viscosity variation phenomenon. Developing and simulating 2 different flow models (Segregated Flow and Viscous Flow) proved that both can be used to obtain comparable velocity and pressure drop results, however; differences are seen visually in the non-uniformity of the velocity and viscosity fields for the Viscous Flow Model (VFM). A comprehensive simulation setup for sealant nozzles was developed so other analysts can utilize the data.
DEFF Research Database (Denmark)
Lippi, Marco; Jaeger, Manfred; Frasconi, Paolo
2011-01-01
We introduce relational information gain, a refinement scoring function measuring the informativeness of newly introduced variables. The gain can be interpreted as a conditional entropy in a well-defined sense and can be efficiently approximately computed. In conjunction with simple greedy general......-to-specific search algorithms such as FOIL, it yields an efficient and competitive algorithm in terms of predictive accuracy and compactness of the learned theory. In conjunction with the decision tree learner TILDE, it offers a beneficial alternative to lookahead, achieving similar performance while significantly...
Receiver Gain Modulation Circuit
Jones, Hollis; Racette, Paul; Walker, David; Gu, Dazhen
2011-01-01
A receiver gain modulation circuit (RGMC) was developed that modulates the power gain of the output of a radiometer receiver with a test signal. As the radiometer receiver switches between calibration noise references, the test signal is mixed with the calibrated noise and thus produces an ensemble set of measurements from which ensemble statistical analysis can be used to extract statistical information about the test signal. The RGMC is an enabling technology of the ensemble detector. As a key component for achieving ensemble detection and analysis, the RGMC has broad aeronautical and space applications. The RGMC can be used to test and develop new calibration algorithms, for example, to detect gain anomalies, and/or correct for slow drifts that affect climate-quality measurements over an accelerated time scale. A generalized approach to analyzing radiometer system designs yields a mathematical treatment of noise reference measurements in calibration algorithms. By treating the measurements from the different noise references as ensemble samples of the receiver state, i.e. receiver gain, a quantitative description of the non-stationary properties of the underlying receiver fluctuations can be derived. Excellent agreement has been obtained between model calculations and radiometric measurements. The mathematical formulation is equivalent to modulating the gain of a stable receiver with an externally generated signal and is the basis for ensemble detection and analysis (EDA). The concept of generating ensemble data sets using an ensemble detector is similar to the ensemble data sets generated as part of ensemble empirical mode decomposition (EEMD) with exception of a key distinguishing factor. EEMD adds noise to the signal under study whereas EDA mixes the signal with calibrated noise. It is mixing with calibrated noise that permits the measurement of temporal-functional variability of uncertainty in the underlying process. The RGMC permits the evaluation of EDA by
Spontaneous Thigh Compartment Syndrome
Directory of Open Access Journals (Sweden)
Khan, Sameer K
2011-02-01
Full Text Available A young man presented with a painful and swollen thigh, without any history of trauma, illness, coagulopathic medication or recent exertional exercise. Preliminary imaging delineated a haematoma in the anterior thigh, without any fractures or muscle trauma. Emergent fasciotomies were performed. No pathology could be identified intra-operatively, or on follow-up imaging. A review of thigh compartment syndromes described in literature is presented in a table. Emergency physicians and traumatologists should be cognisant of spontaneous atraumatic presentations of thigh compartment syndrome, to ensure prompt referral and definitive management of this limb-threatening condition. [West J Emerg Med. 2011;12(1:134-138].
Parametric instabilities in large plasmas
International Nuclear Information System (INIS)
Brambilla, Marco; Liberman, Bernardo.
1979-01-01
Parametric decay processes in large plasmas are considered as the linear stage of a three wave interaction (pump, sideband and beat wave) in which the amplitude of the externally excited pump is sufficiently large to neglect pump depletion to first order, yet sufficiently small to allow a linearized treatment of the pump propagation to zeroth order. The coupling coefficients are then obtained from an iterative solution of Vlasov equation, and a compact expression is derived, in which the multiple series over Bessel functions is explicitly summed. Even in the limit of a very long wavelength pump, the dispersion relation obtained in this way does not coincide with the one obtained using the well-known ''dipole'' approximation, unless both the sideband and beat wave are resonant modes of the plasma. An analysis of the origin of this discrepancy allows us to conclude that ''quasimodes'' (evanescent waves driven absolutely unstable by the pump) are more correctly described by the iterative approach
Parametric instabilities in inhomogeneous plasma
International Nuclear Information System (INIS)
Nicholson, D.R.
1975-01-01
The nonlinear coupling of three waves in a plasma is considered. One of the waves is assumed large and constant; its amplitude is the parameter of the parametric instability. The spatial-temporal evolution of the other two waves is treated theoretically, in one dimension, by analytic methods and by direct numerical integration of the basic equations. Various monotonic forms of inhomogeneity are considered; agreement with previous work is found and new results are established. Nonmonotonic inhomogeneities are considered, in the form of turbulence and, as a model problem, in the form of a simple sinusoidal modulation. Relatively small amounts of nonmonotonic inhomogeneity, in the presence of a linear density gradient, are found to destabilize the well-known convective saturation, absolute growth occurring instead. (U.S.)
Parametric studies on automotive radiators
International Nuclear Information System (INIS)
Oliet, C.; Oliva, A.; Castro, J.; Perez-Segarra, C.D.
2007-01-01
This paper presents a set of parametric studies performed on automotive radiators by means of a detailed rating and design heat exchanger model developed by the authors. This numerical tool has been previously verified and validated using a wide experimental data bank. A first part of the analysis focuses on the influence of working conditions on both fluids (mass flows, inlet temperatures) and the impact of the selected coolant fluid. Following these studies, the influence of some geometrical parameters is analysed (fin pitch, louver angle) as well as the importance of coolant flow lay-out on the radiator global performance. This work provides an overall behaviour report of automobile radiators working at usual range of operating conditions, while significant knowledge-based design conclusions have also been reported. The results show the utility of this numerical model as a rating and design tool for heat exchangers manufacturers, being a reasonable compromise between classic ε - NTU methods and CFD
CKM matrix exponential parametrization and Euler angles
International Nuclear Information System (INIS)
Dattoli, G.; Sabia, E.; Torre, A.
1997-01-01
They show that the exponential parametrization of the CKM matrix allows to establish exact relations between the Euler weak rotation angles and the entries of the CKM generating matrix, which has already been shown to include the hierarchy features of the Wolfenstein parametrization. The analysis includes CP-violating effects and its usefulness to treat the experimental data is also proved
Observation of Parametric Instability in Advanced LIGO.
Evans, Matthew; Gras, Slawek; Fritschel, Peter; Miller, John; Barsotti, Lisa; Martynov, Denis; Brooks, Aidan; Coyne, Dennis; Abbott, Rich; Adhikari, Rana X; Arai, Koji; Bork, Rolf; Kells, Bill; Rollins, Jameson; Smith-Lefebvre, Nicolas; Vajente, Gabriele; Yamamoto, Hiroaki; Adams, Carl; Aston, Stuart; Betzweiser, Joseph; Frolov, Valera; Mullavey, Adam; Pele, Arnaud; Romie, Janeen; Thomas, Michael; Thorne, Keith; Dwyer, Sheila; Izumi, Kiwamu; Kawabe, Keita; Sigg, Daniel; Derosa, Ryan; Effler, Anamaria; Kokeyama, Keiko; Ballmer, Stefan; Massinger, Thomas J; Staley, Alexa; Heinze, Matthew; Mueller, Chris; Grote, Hartmut; Ward, Robert; King, Eleanor; Blair, David; Ju, Li; Zhao, Chunnong
2015-04-24
Parametric instabilities have long been studied as a potentially limiting effect in high-power interferometric gravitational wave detectors. Until now, however, these instabilities have never been observed in a kilometer-scale interferometer. In this Letter, we describe the first observation of parametric instability in a gravitational wave detector, and the means by which it has been removed as a barrier to progress.
Parametric form of QCD travelling waves
Peschanski, R.
2005-01-01
We derive parametric travelling-wave solutions of non-linear QCD equations. They describe the evolution towards saturation in the geometric scaling region. The method, based on an expansion in the inverse of the wave velocity, leads to a solvable hierarchy of differential equations. A universal parametric form of travelling waves emerges from the first two orders of the expansion.
Why preferring parametric forecasting to nonparametric methods?
Jabot, Franck
2015-05-07
A recent series of papers by Charles T. Perretti and collaborators have shown that nonparametric forecasting methods can outperform parametric methods in noisy nonlinear systems. Such a situation can arise because of two main reasons: the instability of parametric inference procedures in chaotic systems which can lead to biased parameter estimates, and the discrepancy between the real system dynamics and the modeled one, a problem that Perretti and collaborators call "the true model myth". Should ecologists go on using the demanding parametric machinery when trying to forecast the dynamics of complex ecosystems? Or should they rely on the elegant nonparametric approach that appears so promising? It will be here argued that ecological forecasting based on parametric models presents two key comparative advantages over nonparametric approaches. First, the likelihood of parametric forecasting failure can be diagnosed thanks to simple Bayesian model checking procedures. Second, when parametric forecasting is diagnosed to be reliable, forecasting uncertainty can be estimated on virtual data generated with the fitted to data parametric model. In contrast, nonparametric techniques provide forecasts with unknown reliability. This argumentation is illustrated with the simple theta-logistic model that was previously used by Perretti and collaborators to make their point. It should convince ecologists to stick to standard parametric approaches, until methods have been developed to assess the reliability of nonparametric forecasting. Copyright © 2015 Elsevier Ltd. All rights reserved.
Integrable multi parametric SU(N) chain
International Nuclear Information System (INIS)
Foerster, Angela; Roditi, Itzhak; Rodrigues, Ligia M.C.S.
1996-03-01
We analyse integrable models associated to a multi parametric SU(N) R-matrix. We show that the Hamiltonians describe SU(N) chains with twisted boundary conditions and that the underlying algebraic structure is the multi parametric deformation of SU(N) enlarged by the introduction of a central element. (author). 15 refs
Nonlinear parametric instability of wind turbine wings
DEFF Research Database (Denmark)
Larsen, Jesper Winther; Nielsen, Søren R.K.
2006-01-01
Nonlinear rotor dynamic is characterized by parametric excitation of both linear and nonlinear terms caused by centrifugal and Coriolis forces when formulated in a moving frame of reference. Assuming harmonically varying support point motions from the tower, the nonlinear parametric instability...
Parametric resonance in neutrino oscillations in matter
Indian Academy of Sciences (India)
Neutrino oscillations in matter can exhibit a specific resonance enhancement - parametric resonance, which is different from the MSW resonance. Oscillations of atmospheric and solar neutrinos inside the earth can undergo parametric enhancement when neutrino trajectories cross the core of the earth. In this paper we ...
Parametric Study Of Window Frame Geometry
DEFF Research Database (Denmark)
Zajas, Jan Jakub; Heiselberg, Per
2013-01-01
This paper describes a parametric study on window frame geometry with the goal of designing frames with very good thermal properties. Three different parametric frame models are introduced, deseribed by a number of variables. In the first part of the study, a process of sensitivity analysis...
Parametric Methods for Order Tracking Analysis
DEFF Research Database (Denmark)
Nielsen, Jesper Kjær; Jensen, Tobias Lindstrøm
2017-01-01
Order tracking analysis is often used to find the critical speeds at which structural resonances are excited by a rotating machine. Typically, order tracking analysis is performed via non-parametric methods. In this report, however, we demonstrate some of the advantages of using a parametric method...
Centrale parametre til karakterisering af bygningers indeklima
DEFF Research Database (Denmark)
Larsen, Tine Steen; Clausen, Geo; Bekö, Gabriel
Denne rapport omhandler arbejdet med identifikation af de parametre, der i vores indeklima påvirker vores komfort og/eller sundhed. Rapporten skal ses som en afrapportering af de overvejelser og valg, der er truffet forud for identifikationen af de centrale parametre, som kommer til at danne...
Al-Alami, Suhair Eyad Jamal
2013-01-01
Initiating the slogan ""love it, live it"", Learn and Gain includes eight short stories, chosen to illustrate various modes of narration, as well as to provoke reflection and discussion on a range of issues. All texts utilized here illustrate how great writers can, with their insight and gift for words, help us to see the world we live in, in new probing and exciting ways. What characterises the book, the author believes, is the integration of the skills of literary competence, communicative c...
Developing a Parametric Urban Design Tool
DEFF Research Database (Denmark)
Steinø, Nicolai; Obeling, Esben
2014-01-01
Parametric urban design is a potentially powerful tool for collaborative urban design processes. Rather than making one- off designs which need to be redesigned from the ground up in case of changes, parametric design tools make it possible keep the design open while at the same time allowing...... for a level of detailing which is high enough to facilitate an understan- ding of the generic qualities of proposed designs. Starting from a brief overview of parametric design, this paper presents initial findings from the development of a parametric urban design tool with regard to developing a structural...... logic which is flexible and expandable. It then moves on to outline and discuss further development work. Finally, it offers a brief reflection on the potentials and shortcomings of the software – CityEngine – which is used for developing the parametric urban design tool....
Spontaneous Tumor Lysis Syndrome
Directory of Open Access Journals (Sweden)
Alicia C. Weeks MD
2015-08-01
Full Text Available Tumor lysis syndrome (TLS is a known complication of malignancy and its treatment. The incidence varies on malignancy type, but is most common with hematologic neoplasms during cytotoxic treatment. Spontaneous TLS is thought to be rare. This case study is of a 62-year-old female admitted with multisystem organ failure, with subsequent diagnosis of aggressive B cell lymphoma. On admission, laboratory abnormalities included renal failure, elevated uric acid (20.7 mg/dL, and 3+ amorphous urates on urinalysis. Oliguric renal failure persisted despite aggressive hydration and diuretic use, requiring initiation of hemodialysis prior to chemotherapy. Antihyperuricemic therapy and hemodialysis were used to resolve hyperuricemia. However, due to multisystem organ dysfunction syndrome with extremely poor prognosis, the patient ultimately expired in the setting of a terminal ventilator wean. Although our patient did not meet current TLS criteria, she required hemodialysis due to uric acid nephropathy, a complication of TLS. This poses the clinical question of whether adequate diagnostic criteria exist for spontaneous TLS and if the lack of currently accepted guidelines has resulted in the underestimation of its incidence. Allopurinol and rasburicase are commonly used for prevention and treatment of TLS. Although both drugs decrease uric acid levels, allopurinol mechanistically prevents formation of the substrate rasburicase acts to solubilize. These drugs were administered together in our patient, although no established guidelines recommend combined use. This raises the clinical question of whether combined therapy is truly beneficial or, conversely, detrimental to patient outcomes.
Mischkowski, Dorothee; Glöckner, Andreas
2016-01-01
Cooperation is essential for the success of societies and there is an ongoing debate whether individuals have therefore developed a general spontaneous tendency to cooperate or not. Findings that cooperative behavior is related to shorter decision times provide support for the spontaneous cooperation effect, although contrary results have also been reported. We show that cooperative behavior is better described as person × situation interaction, in that there is a spontaneous cooperation effect for prosocial but not for proself persons. In three studies, one involving population representative samples from the US and Germany, we found that cooperation in a public good game is dependent on an interaction between individuals’ social value orientation and decision time. Increasing deliberation about the dilemma situation does not affect persons that are selfish to begin with, but it is related to decreasing cooperation for prosocial persons that gain positive utility from outcomes of others and score high on the related general personality trait honesty/humility. Our results demonstrate that the spontaneous cooperation hypothesis has to be qualified in that it is limited to persons with a specific personality and social values. Furthermore, they allow reconciling conflicting previous findings by identifying an important moderator for the effect. PMID:26876773
Qian, Chunqi; Murphy-Boesch, Joseph; Dodd, Stephen; Koretsky, Alan
2012-09-01
A completely wireless detection coil with an integrated parametric amplifier has been constructed to provide local amplification and transmission of MR signals. The sample coil is one element of a parametric amplifier using a zero-bias diode that mixes the weak MR signal with a strong pump signal that is obtained from an inductively coupled external loop. The NMR sample coil develops current gain via reduction in the effective coil resistance. Higher gain can be obtained by adjusting the level of the pumping power closer to the oscillation threshold, but the gain is ultimately constrained by the bandwidth requirement of MRI experiments. A feasibility study here shows that on a NaCl/D(2) O phantom, (23) Na signals with 20 dB of gain can be readily obtained with a concomitant bandwidth of 144 kHz. This gain is high enough that the integrated coil with parametric amplifier, which is coupled inductively to external loops, can provide sensitivity approaching that of direct wire connection. Copyright © 2012 Wiley Periodicals, Inc.
Microwave parametric amplifiers using externally pumped Josephson junctions
DEFF Research Database (Denmark)
Sørensen, O. H.; Mygind, Jesper; Pedersen, Niels Falsig
1978-01-01
Externally pumped parametric amplifiers are discussed. Theory and experiments on the singly degenerate parametric amplifier based on a Josephson junction are presented. Advantages and limitations of the singly degenerate and doubly degenerate parametric amplifiers are discussed. Some plans and pr...
Intermodal Parametric Frequency Conversion in Optical Fibers
Demas, Jeffrey D.
Lasers are an essential technology enabling countless fields of optics, however, their operation wavelengths are limited to isolated regions across the optical spectrum due to the need for suitable gain media. Parametric frequency conversion (PFC) is an attractive means to convert existing lasers to new colors using nonlinear optical interactions rather than the material properties of the host medium, allowing for the development of high power laser sources across the entire optical spectrum. PFC in bulk chi(2) crystals has led to the development of the optical parametric oscillator, which is currently the standard source for high power light at non-traditional wavelengths in the laboratory setting. Ideally, however, one could implement PFC in an optical fiber, thus leveraging the crucial benefits of a guided-wave geometry: alignment-free, compact, and robust operation. Four-wave mixing (FWM) is a nonlinear effect in optical fibers that can be used to convert frequencies, the major challenge being conservation of momentum, or phase matching, between the interacting light waves. Phase matching can be satisfied through the interaction of different spatial modes in a multi-mode fiber, however, previous demonstrations have been limited by mode stability and narrow-band FWM gain. Alternatively, phase matching within the fundamental mode can be realized in high-confinement waveguides (such as photonic crystal fibers), but achieving the anomalous waveguide dispersion necessary for phase matching at pump wavelengths near ˜1 mum (where the highest power fiber lasers emit) comes at the cost of reducing the effective area of the mode, thus limiting power-handling. Here, we specifically consider the class of Bessel-like LP0,m modes in step-index fibers. It has been shown that these modes can be selectively excited and guided stably for long lengths of fiber, and mode stability increases with mode order 'm'. The effective area of modes in these fibers can be very large (>6000
Low-noise parametric amplification at 35 GHz in a single Josephson tunnel junction
DEFF Research Database (Denmark)
Mygind, Jesper; Pedersen, Niels Falsig; Sørensen, O. H.
1979-01-01
Parametric amplification at 35 GHz has been obtained using a single Josephson tunnel junction as the active element. The amplifier was operated in the singly quasidegenerate mode with a pump frequency at 70 GHz. The noise temperature was measured and found correlated with the gain. At the highest...... gain achieved, 11.6 dB, the noise temperature was 400 K. The noise temperature was reduced considerably by decreasing the gain. At 8 and 4 dB we found 165±25 K and 50±30 K, respectively. Applied Physics Letters is copyrighted by The American Institute of Physics....
Low-noise parametric amplification at 35 GHz in a single Josephson tunnel junction
International Nuclear Information System (INIS)
Mygind, J.; Pedersen, N.F.; Soerensen, O.H.; Dueholm, B.; Levinsen, M.T.
1979-01-01
Parametric amplification at 35 GHz has been obtained using a single Josephson tunnel junction as the active element. The amplifier was operated in the singly quasidegenerate mode with a pump frequency at 70 GHz. The noise temperature was measured and found correlated with the gain. At the highest gain achieved, 11.6 dB, the noise temperature was 400 K. The noise temperature was reduced considerably by decreasing the gain. At 8 and 4 dB we found 165 +- 25 K and 50 +- 30 K, respectively
Gaining Relational Competitive Advantages
DEFF Research Database (Denmark)
Hu, Yimei; Zhang, Si; Li, Jizhen
2015-01-01
Establishing strategic technological partnerships (STPs) with foreign partners is an increasingly studied topic within the innovation management literature. Partnering firms can jointly create sources of relational competitive advantage. Chinese firms often lack research and development (R......&D) capabilities but are increasingly becoming preferred technological partners for transnational corporations. We investigate an STP between a Scandinavian and a Chinese firm and try to explore how to gain relational competitive advantage by focusing on its two essential stages: relational rent generation...... and appropriation. Based on an explorative case study, we develop a conceptual framework that consists of process, organizational alliance factors, and coordination modes that we propose lead to relational competitive advantage....
Ionization Cooling using Parametric Resonances
International Nuclear Information System (INIS)
Johnson, Rolland P.
2008-01-01
Ionization Cooling using Parametric Resonances was an SBIR project begun in July 2004 and ended in January 2008 with Muons, Inc., (Dr. Rolland Johnson, PI), and Thomas Jefferson National Accelerator Facility (JLab) (Dr. Yaroslav Derbenev, Subcontract PI). The project was to develop the theory and simulations of Parametric-resonance Ionization Cooling (PIC) so that it could be used to provide the extra transverse cooling needed for muon colliders in order to relax the requirements on the proton driver, reduce the site boundary radiation, and provide a better environment for experiments. During the course of the project, the theoretical understanding of PIC was developed and a final exposition is ready for publication. Workshops were sponsored by Muons, Inc. in May and September of 2007 that were devoted to the PIC technique. One outcome of the workshops was the interesting and somewhat unexpected realization that the beam emittances using the PIC technique can get small enough that space charge forces can be important. A parallel effort to develop our G4beamline simulation program to include space charge effects was initiated to address this problem. A method of compensating for chromatic aberrations by employing synchrotron motion was developed and simulated. A method of compensating for spherical aberrations using beamline symmetry was also developed and simulated. Different optics designs have been developed using the OptiM program in preparation for applying our G4beamline simulation program, which contains all the power of the Geant4 toolkit. However, no PIC channel design that has been developed has had the desired cooling performance when subjected to the complete G4beamline simulation program. This is believed to be the consequence of the difficulties of correcting the aberrations associated with the naturally large beam angles and beam sizes of the PIC method that are exacerbated by the fringe fields of the rather complicated channel designs that have been
Spontaneous Intracranial Hypotension
International Nuclear Information System (INIS)
Joash, Dr.
2015-01-01
Epidemiology is not only rare but an important cause of new daily persistent headaches among young & middle age individuals. The Etiology & Pathogenesis is generally caused by spinal CSF leak. Precise cause remains largely unknown, underlying structural weakness of spinal meninges is suspected. There are several MR Signs of Intracranial Hypotension that include:- diffuse pachymeningeal (dural) enhancement; bilateral subdural, effusion/hematomas; Downward displacement of brain; enlargement of pituitary gland; Engorgement of dural venous sinuses; prominence of spinal epidural venous plexus and Venous sinus thrombosis & isolated cortical vein thrombosis. The sum of volumes of intracranial blood, CSF & cerebral tissue must remain constant in an intact cranium. Treatment in Many cases can be resolved spontaneously or by use Conservative approach that include bed rest, oral hydration, caffeine intake and use of abdominal binder. Imaging Modalities for Detection of CSF leakage include CT myelography, Radioisotope cisternography, MR myelography, MR imaging and Intrathecal Gd-enhanced MR
Spontaneous wave packet reduction
International Nuclear Information System (INIS)
Ghirardi, G.C.
1994-06-01
There are taken into account the main conceptual difficulties met by standard quantum mechanics in dealing with physical processes involving macroscopic system. It is stressed how J.A.Wheeler's remarks and lucid analysis have been relevant to pinpoint and to bring to its extreme consequences the puzzling aspects of quantum phenomena. It is shown how the recently proposed models of spontaneous dynamical reduction represent a consistent way to overcome the conceptual difficulties of the standard theory. Obviously, many nontrivial problems remain open, the first and more relevant one being that of generalizing the model theories considered to the relativistic case. This is the challenge of the dynamical reduction program. 43 refs, 2 figs
The parametrization invariant and gauge invariant effective actions in quantum field theory
International Nuclear Information System (INIS)
Odintsov, S.D.
1990-01-01
The review of formulation and methods of calculation of the parametrization and gauge invariant effective actions in quantum field theory is given. As an example the Vilkovisky-De Witt Effective action (EA) is studied (this EA is a natural representative of gauge and parametrization invariant EA's). The examples where the use of the standard EA leads to the ambiguity are demonstrated. This happens as the result of dependence of the standard EA upon the choice of gauge condition. These examples are as follows: Coleman-Weinberg potential in the finite theories and symmetry breaking, EA in quantum gravity with matter and d=5 gauged supergravity, the possibility of spontaneous supersymmetry breaking in N=1 supergravity and the spontaneous compactification in the multidimensional R 2 -gravity. In all these cases the one-loop Vilkovisky-De Witt EA is found and therefore the problem of gauge dependence of EA is solved. The dependence of standard EA of composite fields upon the gauge is studied for the general gauge theories. The class of gauge and parametrization invariant EA's of the composite fields is offered. (author)
Sustained mild hypergravity reduces spontaneous cardiac baroreflex sensitivity.
Yanagida, Ryo; Ogawa, Yojiro; Ueda, Kaname; Aoki, Ken; Iwasaki, Ken-ichi
2014-10-01
Head-to-foot gravitational force >1G (+Gz hypergravity) augments venous pooling in the lower body and reduces central blood volume during exposure, compared with 1Gz. Central hypovolemia has been reported to reduce spontaneous cardiac baroreflex sensitivity. However, no investigations have examined spontaneous cardiac baroreflex sensitivity during exposure to sustained mild +Gz hypergravity. We therefore hypothesized that mild +Gz hypergravity would reduce spontaneous cardiac baroreflex sensitivity, compared with 1Gz. To test this hypothesis, we examined spontaneous cardiac baroreflex sensitivity in 16 healthy men during exposure to mild +Gz hypergravity using a short-arm centrifuge. Beat-to-beat arterial blood pressure (tonometry) and R-R interval (electrocardiography) were obtained during 1Gz and 1.5Gz exposures. Spontaneous cardiac baroreflex sensitivity was assessed by sequence slope and transfer function gain. Stroke volume was calculated from the arterial pressure waveform using a three-element model. All indices of spontaneous cardiac baroreflex sensitivity decreased significantly (up slope: 18.6±2.3→12.7±1.6ms/mmHg, Pbaroreflex sensitivity, increasing the risk of cardiovascular disturbance during the exposure. Copyright © 2014 Elsevier B.V. All rights reserved.
Self-seeding ring optical parametric oscillator
Smith, Arlee V [Albuquerque, NM; Armstrong, Darrell J [Albuquerque, NM
2005-12-27
An optical parametric oscillator apparatus utilizing self-seeding with an external nanosecond-duration pump source to generate a seed pulse resulting in increased conversion efficiency. An optical parametric oscillator with a ring configuration are combined with a pump that injection seeds the optical parametric oscillator with a nanosecond duration, mJ pulse in the reverse direction as the main pulse. A retroreflecting means outside the cavity injects the seed pulse back into the cavity in the direction of the main pulse to seed the main pulse, resulting in higher conversion efficiency.
Linear Parametric Model Checking of Timed Automata
DEFF Research Database (Denmark)
Hune, Tohmas Seidelin; Romijn, Judi; Stoelinga, Mariëlle
2001-01-01
We present an extension of the model checker Uppaal capable of synthesize linear parameter constraints for the correctness of parametric timed automata. The symbolic representation of the (parametric) state-space is shown to be correct. A second contribution of this paper is the identication...... of a subclass of parametric timed automata (L/U automata), for which the emptiness problem is decidable, contrary to the full class where it is know to be undecidable. Also we present a number of lemmas enabling the verication eort to be reduced for L/U automata in some cases. We illustrate our approach...
Parametric robustness of the reactor control system
International Nuclear Information System (INIS)
Lee, Yoon Joon; Kim, Sin
1998-01-01
The parametric analysis method is applied to the reactor control system. The mathematical reactor model is discussed in terms of the parametric uncertainties. The Tsyplin-Polyak locus, based on the boundary crossing theorem, shows the reactor plant has an intrinsic stability. A simple controller is incorporated to the plant to configure the overall closed loop system. Then parametric stability margins are obtained for the controller constants. The results show that a new design constraint of the controller robustness with respect to overall system should be considered for the controller design of an uncertain system
Spontaneous compactification to homogeneous spaces
International Nuclear Information System (INIS)
Mourao, J.M.
1988-01-01
The spontaneous compactification of extra dimensions to compact homogeneous spaces is studied. The methods developed within the framework of coset space dimensional reduction scheme and the most general form of invariant metrics are used to find solutions of spontaneous compactification equations
Screening for spontaneous preterm birth
van Os, M.A.; van Dam, A.J.E.M.
2015-01-01
Preterm birth is the most important cause of perinatal morbidity and mortality worldwide. In this thesis studies on spontaneous preterm birth are presented. The main objective was to investigate the predictive capacity of mid-trimester cervical length measurement for spontaneous preterm birth in a
Spontaneous Pneumomediastinum: Hamman Syndrome
Directory of Open Access Journals (Sweden)
Tushank Chadha, BS
2018-04-01
significant fat stranding. The image also showed an intraluminal stent traversing the gastric antrum and gastric pylorus with no indication of obstruction. Circumferential mural thickening of the gastric antrum and body were consistent with the patient’s history of gastric adenocarcinoma. The shotty perigastric lymph nodes with associated fat stranding, along the greater curvature of the distal gastric body suggested local regional nodal metastases and possible peritoneal carcinomatosis. The thoracic CT scans showed extensive pneumomediastinum that tracked into the soft tissues of the neck, which given the history of vomiting also raised concern for esophageal perforation. There was still no evidence of mediastinal abscess or fat stranding. Additionally, a left subclavian vein port catheter, which terminates with tip at the cavoatrial junction of the superior vena cava can also be seen on the image. Discussion: Spontaneous Pneumomediastinum, also known as Hamman syndrome, is defined by the uncommon incidence of free air in the mediastinum due to the bursting of alveoli, as a result of extended spells of shouting, coughing, or vomiting.1,2 The condition is diagnosed when a clear cause (aerodigestive rupture, barotrauma, infection secondary to gas-forming organisms3 for pneumomediastinum cannot be clearly identified on diagnostic studies. Macklin and Macklin were the first to note the pathogenesis of the syndrome and explained that the common denominator to spontaneous pneumomediastinum was that increased alveolar pressure leads to alveolar rupture.3 Common clinical findings for spontaneous pneumomediastinum include: chest pain, dyspnea, cough, and emesis.4 The condition is not always readily recognized on initial presentation in part for its rare incidence, estimated to be approximately 1 in every 44,500 ED patients3and also because of the non-specific presenting symptoms. For this patient, there was no clear singular cause, and therefore she received care for spontaneous
Plug and Play Robust Distributed Control with Ellipsoidal Parametric Uncertainty System
Directory of Open Access Journals (Sweden)
Hong Wang-jian
2016-01-01
Full Text Available We consider a continuous linear time invariant system with ellipsoidal parametric uncertainty structured into subsystems. Since the design of a local controller uses only information on a subsystem and its neighbours, we combine the plug and play idea and robust distributed control to propose one distributed control strategy for linear system with ellipsoidal parametric uncertainty. Firstly for linear system with ellipsoidal parametric uncertainty, a necessary and sufficient condition for robust state feedback control is proposed by means of linear matrix inequality. If this necessary and sufficient condition is satisfied, this robust state feedback gain matrix can be easily derived to guarantee robust stability and prescribed closed loop performance. Secondly the plug and play idea is introduced in the design process. Finally by one example of aircraft flutter model parameter identification, the efficiency of the proposed control strategy can be easily realized.
Design and optimization of fiber optical parametric oscillators for femtosecond pulse generation.
Zhang, Wen Qi; Sharping, Jay E; White, Richard T; Monro, Tanya M; Afshar V, Shahraam
2010-08-02
In this paper, we use a genetic algorithm and pulse-propagation analysis to design and optimize optical parametric oscillators based on soft-glass microstructured optical fibers. The maximum parametric gain, phase-match, walk-off between pump (1560 nm) and signal (880 nm) pulses, signal feedback ratio and signal-pump synchronization of the cavity are optimized. Pulse propagation analysis suggests that one can implement a fiber optical parametric oscillator capable of generating approximately 200-fs pulses at 880 nm with 43% peak-power conversion, high output pulse quality (time-bandwidth product approximately 0.43) and a wavelength tuning range that is limited only by the glass transmission windows.
DEFF Research Database (Denmark)
Petersen, Sidsel Rübner; Lægsgaard, Jesper; Alkeskjold, Thomas Tanggaard
2013-01-01
Intermodal degenerate four wave mixing (FWM) is investigated numerically in large mode area hybrid photonic crystal fibers. The dispersion is controlled independently of core size, and thus allows for power scaling of the FWM process.......Intermodal degenerate four wave mixing (FWM) is investigated numerically in large mode area hybrid photonic crystal fibers. The dispersion is controlled independently of core size, and thus allows for power scaling of the FWM process....
Enhanced parametric processes in binary metamaterials
Gorkunov, Maxim V.; Shadrivov, Ilya V.; Kivshar, Yuri S.
2005-01-01
We suggest double-resonant (binary) metamaterials composed of two types of magnetic resonant elements, and demonstrate that in the nonlinear regime such metamaterials provide unique possibilities for phase-matched parametric interaction and enhanced second-harmonic generation.
A Parametric k-Means Algorithm
Tarpey, Thaddeus
2007-01-01
Summary The k points that optimally represent a distribution (usually in terms of a squared error loss) are called the k principal points. This paper presents a computationally intensive method that automatically determines the principal points of a parametric distribution. Cluster means from the k-means algorithm are nonparametric estimators of principal points. A parametric k-means approach is introduced for estimating principal points by running the k-means algorithm on a very large simulated data set from a distribution whose parameters are estimated using maximum likelihood. Theoretical and simulation results are presented comparing the parametric k-means algorithm to the usual k-means algorithm and an example on determining sizes of gas masks is used to illustrate the parametric k-means algorithm. PMID:17917692
Parametric bases for elliptic boundary value problem
Gusev, A. A.; Vinitsky, S. I.; Chuluunbaatar, O.; Derbov, V. L.; Góźdź, A.; Krassovitskiy, P. M.
2018-02-01
We consider the calculation schemes in the framework of Kantorovich method that consist in the reduction of a 3D elliptic boundary-value problem (BVP) to a set of second-order ordinary differential equations (ODEs) using the parametric basis functions. These functions are solution of the 2D parametric BVP. The coefficients in the ODEs are the parametric eigenvalues and the potential matrix elements expressed by the integrals of the eigenfunctions multiplied by their first derivatives with respect to the parameter. We calculate the parametric basis functions numerically in the general case using the high-accuracy finite element method. The efficiency of the proposed calculation schemes and algorithms is demonstrated by the example of the BVP describing the bound states of helium atom.
Parametrically disciplined operation of a vibratory gyroscope
Shcheglov, Kirill V. (Inventor); Hayworth, Ken J. (Inventor); Challoner, A. Dorian (Inventor); Peay, Chris S. (Inventor)
2008-01-01
Parametrically disciplined operation of a symmetric nearly degenerate mode vibratory gyroscope is disclosed. A parametrically-disciplined inertial wave gyroscope having a natural oscillation frequency in the neighborhood of a sub-harmonic of an external stable clock reference is produced by driving an electrostatic bias electrode at approximately twice this sub-harmonic frequency to achieve disciplined frequency and phase operation of the resonator. A nearly symmetric parametrically-disciplined inertial wave gyroscope that can oscillate in any transverse direction and has more than one bias electrostatic electrode that can be independently driven at twice its oscillation frequency at an amplitude and phase that disciplines its damping to zero in any vibration direction. In addition, operation of a parametrically-disciplined inertial wave gyroscope is taught in which the precession rate of the driven vibration pattern is digitally disciplined to a prescribed non-zero reference value.
Parametric optimization of inverse trapezoid oleophobic surfaces
DEFF Research Database (Denmark)
Cavalli, Andrea; Bøggild, Peter; Okkels, Fridolin
2012-01-01
In this paper, we introduce a comprehensive and versatile approach to the parametric shape optimization of oleophobic surfaces. We evaluate the performance of inverse trapezoid microstructures in terms of three objective parameters: apparent contact angle, maximum sustainable hydrostatic pressure...
Maksoud, Aref
2017-01-01
Complexity and Strategies for parametric design in architecture. An application of practice led research. Nowadays a new specialist design role is emerging in the construction industry. The primary task related to this role is focused on the control, development and sharing of geometric information with members of the design team in order to develop a design solution. Individuals engaged in this role can be described as a parametric designers. Parametric design involves the ...
A Parametric k-Means Algorithm
Tarpey, Thaddeus
2007-01-01
The k points that optimally represent a distribution (usually in terms of a squared error loss) are called the k principal points. This paper presents a computationally intensive method that automatically determines the principal points of a parametric distribution. Cluster means from the k-means algorithm are nonparametric estimators of principal points. A parametric k-means approach is introduced for estimating principal points by running the k-means algorithm on a very large simulated data...
Stochastic Non-Parametric Frontier Analysis
Mohammad Rahmani; Gholamreza Jahanshahloo
2014-01-01
In this paper we develop an approach that synthesizes the best features of the two main methods in the estimation of production eciency. Specically, our approach rst allows for statistical noise, similar to Stochastic frontier analysis , and second, it allows modeling multiple-inputs-multiple-outputs technologies without imposing parametric assumptions on production relationship, similar to what is done in non-parametric methods. The methodology is based on the theory of local maximum likelih...
Parametric Transverse Patterns in Broad Aperture Lasers
DEFF Research Database (Denmark)
Grigorieva, E.V.; Kashchenko, S.A.; Mosekilde, Erik
1998-01-01
Parametrically generated optical patterns are investigated for finite and large-scale transverse aperture lasers. Standing and rotating patterns as well as periodic and chaotic pattern alternations are described in the framework of the amplitude equation formalism. Sensitive dependence on the geo......Parametrically generated optical patterns are investigated for finite and large-scale transverse aperture lasers. Standing and rotating patterns as well as periodic and chaotic pattern alternations are described in the framework of the amplitude equation formalism. Sensitive dependence...
Parametric studies for the fusion engineering device
International Nuclear Information System (INIS)
Reid, R.L.; Steiner, D.
1983-01-01
Parametric studies were conducted using the Fusion Engineering Design Center (FEDC) systems code to investigate the cost, performance, and engineering sensitivity of variations within the fusion engineering device (FED) design space. Candidate FED missions and the associated fusion devices required to achieve the missions are compared. A brief description of the FEDC systems code and the results of the parametric studies that helped to define the FED baseline design are presented
Four-photon parametric amplification in semiconductors
International Nuclear Information System (INIS)
Jain, M.; Gersten, J.; Tzoar, N.
1975-01-01
A theoretical study of four-photon parametric amplification in narrow-band-gap semiconductors is made. It is shown that phase matching is achievable in a linear geometry if a magnetic field is employed. Furthermore, a substantial cyclotron resonance enhancement occurs in the presence of a magnetic field. We calculate the growth rates and threshold fields associated with the parametric amplification and conclude that an efficient laser may be designed based on this process
Parametric instability of shaft with discs
Wahab, A. M. Abdul; Rasid, Z. A.; Abu, A.; Rudin, N. F. Mohd Noor
2017-12-01
The occurrence of resonance is a major criterion to be considered in the design of shaft. While force resonance occurs merely when the natural frequency of the rotor system equals speed of the shaft, parametric resonance or parametric instability can occur at excitation speed that is integral or sub-multiple of the frequency of the rotor. This makes the study on parametric resonance crucial. Parametric instability of a shaft system consisting of a shaft and disks has been investigated in this study. The finite element formulation of the Mathieu-Hill equation that represents the parametric instability problem of the shaft is developed based on Timoshenko’s beam theory and Nelson’s finite element method (FEM) model that considers the effect of torsional motion on such problem. The Bolotin’s method is used to determine the regions of instability and the Strut-Ince diagram. The validation works show that the results of this study are in close agreement to past results. It is found that a larger radius of disk will cause the shaft to become more unstable compared to smaller radius although both weights are similar. Furthermore, the effect of torsional motion on the parametric instability of the shaft is significant at higher rotating speed.
Heuristic Portfolio Trading Rules with Capital Gain Taxes
DEFF Research Database (Denmark)
Fischer, Marcel; Gallmeyer, Michael
strategy is not dominated out-of-sample by a variety of optimizing trading strategies, except the parametric portfolios of Brandt, Santa-Clara, and Valkanov (2009). With dividend and realization-based capital gain taxes, the welfare costs of the taxes are large with the cost being as large as 30% of wealth......We study the out-of-sample performance of portfolio trading strategies when an investor faces capital gain taxation and proportional transaction costs. Under no capital gain taxation and no transaction costs, we show that, consistent with DeMiguel, Garlappi, and Uppal (2009), a simple 1/N trading...... outperform a 1/N trading strategy augmented with a tax heuristic, not even the most tax- and transaction-cost efficient buy-and-hold strategy. Overall, the best strategy is 1/N augmented with a heuristic that allows for a fixed deviation in absolute portfolio weights. Our results show that the best trading...
Spontaneous breaking of supersymmetry
Energy Technology Data Exchange (ETDEWEB)
Zumino, B.
1981-12-01
There has been recently a revival of interest in supersymmetric gauge theories, stimulated by the hope that supersymmetry might help in clarifying some of the questions which remain unanswered in the so called Grand Unified Theories and in particular the gauge hierarchy problem. In a Grand Unified Theory one has two widely different mass scales: the unification mass M approx. = 10/sup 15/GeV at which the unification group (e.g. SU(5)) breaks down to SU(3) x SU(2) x U(1) and the mass ..mu.. approx. = 100 GeV at which SU(2) x U(1) is broken down to the U(1) of electromagnetism. There is at present no theoretical understanding of the extreme smallness of the ratio ..mu../M of these two numbers. This is the gauge hierarchy problem. This lecture attempts to review the various mechanisms for spontaneous supersymmetry breaking in gauge theories. Most of the discussions are concerned with the tree approximation, but what is presently known about radiative correction is also reviewed.
Spontaneous intracranial hypotension
International Nuclear Information System (INIS)
Haritanti, A.; Karacostas, D.; Drevelengas, A.; Kanellopoulos, V.; Paraskevopoulou, E.; Lefkopoulos, A.; Economou, I.; Dimitriadis, A.S.
2009-01-01
Spontaneous intracranial hypotension (SIH) is an uncommon but increasingly recognized syndrome. Orthostatic headache with typical findings on magnetic resonance imaging (MRI) are the key to diagnosis. Delayed diagnosis of this condition may subject patients to unnecessary procedures and prolong morbidity. We describe six patients with SIH and outline the important clinical and neuroimaging findings. They were all relatively young, 20-54 years old, with clearly orthostatic headache, minimal neurological signs (only abducent nerve paresis in two) and diffuse pachymeningeal gadolinium enhancement on brain MRI, while two of them presented subdural hygromas. Spinal MRI was helpful in detecting a cervical cerebrospinal fluid leak in three patients and dilatation of the vertebral venous plexus with extradural fluid collection in another. Conservative management resulted in rapid resolution of symptoms in five patients (10 days-3 weeks) and in one who developed cerebral venous sinus thrombosis, the condition resolved in 2 months. However, this rapid clinical improvement was not accompanied by an analogous regression of the brain MR findings that persisted on a longer follow-up. Along with recent literature data, our patients further point out that SIH, to be correctly diagnosed, necessitates increased alertness by the attending physician, in the evaluation of headaches
Spontaneous lateral temporal encephalocele.
Tuncbilek, Gokhan; Calis, Mert; Akalan, Nejat
2013-01-01
A spontaneous encephalocele is one that develops either because of embryological maldevelopment or from a poorly understood postnatal process that permits brain herniation to occur. We here report a rare case of lateral temporal encephalocele extending to the infratemporal fossa under the zygomatic arch. At birth, the infant was noted to have a large cystic mass in the right side of the face. After being operated on initially in another center in the newborn period, the patient was referred to our clinic with a diagnosis of temporal encephalocele. He was 6 months old at the time of admission. Computerized tomography scan and magnetic resonance imaging studies revealed a 8 × 9 cm fluid-filled, multiloculated cystic mass at the right infratemporal fossa. No intracranial pathology or connection is seen. The patient was operated on to reduce the distortion effect of the growing mass. The histopathological examination of the sac revealed well-differentiated mature glial tissue stained with glial fibrillary acid protein. This rare clinical presentation of encephaloceles should be taken into consideration during the evaluation of the lateral facial masses in the infancy period, and possible intracranial connection should be ruled out before surgery to avoid complications.
General theory of spontaneous emission near exceptional points.
Pick, Adi; Zhen, Bo; Miller, Owen D; Hsu, Chia W; Hernandez, Felipe; Rodriguez, Alejandro W; Soljačić, Marin; Johnson, Steven G
2017-05-29
We present a general theory of spontaneous emission at exceptional points (EPs)-exotic degeneracies in non-Hermitian systems. Our theory extends beyond spontaneous emission to any light-matter interaction described by the local density of states (e.g., absorption, thermal emission, and nonlinear frequency conversion). Whereas traditional spontaneous-emission theories imply infinite enhancement factors at EPs, we derive finite bounds on the enhancement, proving maximum enhancement of 4 in passive systems with second-order EPs and significantly larger enhancements (exceeding 400×) in gain-aided and higher-order EP systems. In contrast to non-degenerate resonances, which are typically associated with Lorentzian emission curves in systems with low losses, EPs are associated with non-Lorentzian lineshapes, leading to enhancements that scale nonlinearly with the resonance quality factor. Our theory can be applied to dispersive media, with proper normalization of the resonant modes.
Operational gain : measuring the capture of genetic gain ...
African Journals Online (AJOL)
Operational gain : measuring the capture of genetic gain : operational deployment of technology. ... The concept of operational gain is more than the weighted average of the genetic quality of planted hectares, and encompasses tree breeding efficiencies, propagation efficiencies, matching of species and genotype to site, ...
On topological structures of fuzzy parametrized soft sets.
Atmaca, Serkan; Zorlutuna, Idris
2014-01-01
We introduce the topological structure of fuzzy parametrized soft sets and fuzzy parametrized soft mappings. We define the notion of quasi-coincidence for fuzzy parametrized soft sets and investigated its basic properties. We study the closure, interior, base, continuity, and compactness and properties of these concepts in fuzzy parametrized soft topological spaces.
Simulating quantum state engineering in spontaneous parametric down-conversion using classical light
CSIR Research Space (South Africa)
Zhang, Y
2014-07-01
Full Text Available the EinsteinPodol- skyRosen experiment, and of demonstrating the complementarity principle,” Sov. Phys. Usp. 31, 74 (1988) 34. R. S. Aspden, D. S. Tasca, A. Forbes, R. W. Boyd and M. J. Padgett, “Experimental demonstration of Klyshkos advanced-wave picture.... The dearth of such experiments is likely due to the prohibitive cost and time, requiring custom optics likely resulting in low count rates. Consequently, quantum state engineering is largely restricted to post selection processes. Inspired by the advanced-wave...
Gao, Jie; Cao, Yongsheng; Chen, Fushen; Sun, Bao; Hu, Zhefeng
2012-02-01
A novel scheme is proposed to obviously improve the amplified gain, gain flatness and bandwidth characteristics of FOPA by applying a cascaded fiber structure. The basic structure of the cascaded fiber optical parametric amplifier (CFOPA) is introduced. Then, the expression of signals pass gain characteristic is obtained by utilizing a set of coupled equations. The gain, bandwidth and gain flatness characteristics of the CFOPA with the different parameters of DCF, such as fiber length l/, dispersion slope dD//dλ, and so on, are theoretical analyzed and optimized. Furthermore, simulation analysis is applied to verify the theoretical results by using Optisystem 7.0 software. Although, there are a few deviations between the simulation and the theoretical results, the simulation results effectively demonstrate the validity and feasibility of the theoretical analysis.
Optimized design of six-wave fiber optical parametric amplifiers by using a genetic algorithm.
Li, Peipei; Zhu, Hongna; Taccheo, Stefano; Gao, Xiaorong; Wang, Zeyong
2017-05-20
A governing equation of the six-wave fiber optical parametric amplifier (FOPA) for the power and phase difference evolution of the six interacting waves is deduced. To optimize the gain of the six-wave FOPA, a multivariate stochastic optimization algorithm, i.e., the genetic algorithm (GA), is applied. The effect of pump depletion on the gain characteristic of the six-wave FOPA is emphasized and the effect of the fiber length, the wavelength, and the power of two pumps on bandwidth, flatness, and magnitude of the gain spectrum has also been studied. A broader and flatter six-wave FOPA gain is obtained by adopting optimum design parameters, which theoretically provide a uniform gain of 65 dB with 0.3 dB uniformity over a 110 nm bandwidth for the six-wave FOPA.
Bilateral spontaneous carotid artery dissection.
Townend, Bradley Scott; Traves, Laura; Crimmins, Denis
2005-06-01
Bilateral internal carotid artery dissections have been reported, but spontaneous bilateral dissections are rare. Internal carotid artery dissection can present with a spectrum of symptoms ranging from headache to completed stroke. Two cases of spontaneous bilateral carotid artery dissection are presented, one with headache and minimal symptoms and the other with a stroke syndrome. No cause could be found in either case, making the dissections completely spontaneous. Bilateral internal carotid artery dissection (ICAD) should be considered in young patients with unexplained head and neck pain with or without focal neurological symptoms and signs. The increasing availability of imaging would sustain the higher index of suspicion.
Non-parametric Tuning of PID Controllers A Modified Relay-Feedback-Test Approach
Boiko, Igor
2013-01-01
The relay feedback test (RFT) has become a popular and efficient tool used in process identification and automatic controller tuning. Non-parametric Tuning of PID Controllers couples new modifications of classical RFT with application-specific optimal tuning rules to form a non-parametric method of test-and-tuning. Test and tuning are coordinated through a set of common parameters so that a PID controller can obtain the desired gain or phase margins in a system exactly, even with unknown process dynamics. The concept of process-specific optimal tuning rules in the nonparametric setup, with corresponding tuning rules for flow, level pressure, and temperature control loops is presented in the text. Common problems of tuning accuracy based on parametric and non-parametric approaches are addressed. In addition, the text treats the parametric approach to tuning based on the modified RFT approach and the exact model of oscillations in the system under test using the locus of a perturbedrelay system (LPRS) meth...
Energy Technology Data Exchange (ETDEWEB)
Wu, J. W. [Ewha Womens Univ., Seoul (Korea); Rhee, B. G. [Sejong Univ., Seoul (Korea); Park, S. W. [Yonsei Univ., Seoul (Korea); Noh, J. W. [Inha Univ., Incheon (Korea)
1998-04-01
A tunable light source is developed by the optical parametric oscillator, which is very useful for a high resolution spectroscopy. The electronic structure of molecules and atoms can be examined by a proper coherent light source. Optical parametric oscillator provides light sources stable and widely tunable. In this work, the characteristics of the parametric optical generation are examined in the LiNbO{sub 3}. The theoretical analysis as well as the experimental measurement is performed. The pump laser is a second harmonic of Nd:YAG laser, and the parametric gain is measured. The characteristics of singly resonant oscillator and doubly resonant oscillator is studied as a function of temperature. It is found that 1mole% MgO:LiNbO{sub 3} crystal provides the tunability from 0.6{mu}m to 3.0{mu}m wavelength. Both the critical and noncritical phase matching are studied. The optical damage occurring in a congruent LiNbO{sub 3} crystal was not observed in 1mole% MgO:LiNbO{sub 3} crystal, opening a possibility for a high power optical parametric oscillation generation. The current work can be extended to an experiment employing the fundamental Nd:YAG as pump to provide a coherent light source for the study of molecular vibrations. 28 refs., 14 figs., 3 tabs. (Author)
Parametric x-ray FEL operating with external Bragg reflectors
International Nuclear Information System (INIS)
Baryshevsky, V.G.; Batrakov, K.G.; Dubovskaya, I.Ya.
1995-01-01
In the crystal X-ray FELs using channeling and parametric quasi-Cherenkov mechanisms of spontaneous radiation were considered as versions of FEL allowing, in principle, to obtain coherent X-ray source. In this case a crystal is both radiator and resonator for X-rays emitted by a particle beam passing through crystal. However, it is well-known that a beam current density required for lasing is extremely high in X-ray spectral range for any radiation mechanisms and it is very important to find a way to lower its magnitude. The application of three-dimensional distributed feedback formed by dynamical diffraction of emitted photons permitted to reduce starting beam current density 10 2 -10 4 times up to 10 9 . One of ways to lower the starting current is the formation of multi-wave distributed feedback the another one is the application of external reflectors. The thing is that lasing regime was shown to be produced at frequencies in the vicinity of degeneration point for roots of dispersion equation describing radiation modes excited in an active medium (crystal plus particle beam). Unfortunately, in case of parametric quasi-Cherenkov FEL this region coincides with the region of strong self-absorption of radiation inside a crystal. That fact, obviously, increases the starting beam current. In this report we have shown that the application of external Bragg reflectors gives the possibility to lower radiation self-absorption inside a crystal by modifying radiation modes excited in the active medium under consideration. The corresponding dispersion equation and the expression for excited modes are derived. The generation equation determining starting conditions for lasing is obtained. Using these expressions we have shown that the application of external Bragg reflectors permits to reduce starting beam current density more than 10 times
Facial Performance Transfer via Deformable Models and Parametric Correspondence.
Asthana, Akshay; de la Hunty, Miles; Dhall, Abhinav; Goecke, Roland
2012-09-01
The issue of transferring facial performance from one person's face to another's has been an area of interest for the movie industry and the computer graphics community for quite some time. In recent years, deformable face models, such as the Active Appearance Model (AAM), have made it possible to track and synthesize faces in real time. Not surprisingly, deformable face model-based approaches for facial performance transfer have gained tremendous interest in the computer vision and graphics community. In this paper, we focus on the problem of real-time facial performance transfer using the AAM framework. We propose a novel approach of learning the mapping between the parameters of two completely independent AAMs, using them to facilitate the facial performance transfer in a more realistic manner than previous approaches. The main advantage of modeling this parametric correspondence is that it allows a "meaningful" transfer of both the nonrigid shape and texture across faces irrespective of the speakers' gender, shape, and size of the faces, and illumination conditions. We explore linear and nonlinear methods for modeling the parametric correspondence between the AAMs and show that the sparse linear regression method performs the best. Moreover, we show the utility of the proposed framework for a cross-language facial performance transfer that is an area of interest for the movie dubbing industry.
Chirp and temperature effects in parametric down conversion from crystals pumped at 800 nm
Sánchez-Lozano, X.; Wiechers, C.; Lucio, J. L.
2018-04-01
We consider spontaneous parametric down conversion from aperiodic poled crystals pumped at 800 nm. Our analyses account the effect of internal and external parameters, where, in the former, we include the crystal chirp and length, while in the latter temperature, also the pump chirp and other beam properties. The typical distribution produced is a pop-tab like structure in frequency-momentum space, and our results show that this system is a versatile light source, appropriated to manipulate the frequency and transverse momentum properties of the light produced. We briefly comment on the potential usefulness of the types of telecom wavelength light produced, in particular for quantum information applications.
Pump Spectral Bandwidth, Birefringence, and Entanglement in Type-II Parametric Down Conversion
Directory of Open Access Journals (Sweden)
Daniel Erenso
2009-01-01
Full Text Available The twin photons produced by a type-II spontaneous parametric down conversion are well know as a potential source of photons for quantum teleportation due to the strong entanglement in polarization. This strong entanglement in polarization, however, depends on the spectral composition of the pump photon and the nature of optical isotropy of the crystal. By exact numerical calculation of the concurrence, we have shown that how pump photons spectral width and the birefringence nature of the crystal directly affect the degree of polarization entanglement of the twin photons.
Parametric down-conversion with optimized spectral properties in nonlinear photonic crystals
International Nuclear Information System (INIS)
Corona, Maria; U'Ren, Alfred B.
2007-01-01
We study the joint spectral properties of photon pairs generated by spontaneous parametric down-conversion in a one-dimensional nonlinear photonic crystal in a collinear, degenerate, type-II geometry. We show that the photonic crystal properties may be exploited to compensate for material dispersion and obtain photon pairs that are nearly factorable, in principle, for arbitrary materials and spectral regions, limited by the ability to fabricate the nonlinear crystal with the required periodic variation in the refractive indices for the ordinary and extraordinary waves
Parametric amplification and phase preserving amplitude regeneration of a 640 Gbit/s RZ-DPSK signal
DEFF Research Database (Denmark)
Lali-Dastjerdi, Zohreh; Galili, Michael; Mulvad, Hans Christian Hansen
2013-01-01
We report the first experimental demonstration of parametric amplification and all-optical phase-preserving amplitude regeneration for a 640 Gbit/s return-to-zero (RZ) differential phase-shift keying (DPSK) optical time division multiplexed (OTDM) signal. In the designed gain-flattened single......-pump fiber optical parametric amplifier (FOPA), 620 fs short optical pulses are successfully amplified with 15 dB gain with error-free performance and less than 1 dB power penalty. Phase-preserving amplitude regeneration based on gain saturation in the FOPA is carried out for optical signals with degraded...... optical signal-to-noise ratio. An improvement of 2.2 dB in receiver sensitivity at a bit-error-ratio of 10−9 has been successfully achieved after regeneration, together with 13.3 dB net gain....
Spontaneous intraorbital hematoma: case report
Directory of Open Access Journals (Sweden)
Vinodan Paramanathan
2010-12-01
Full Text Available Vinodan Paramanathan, Ardalan ZolnourianQueen's Hospital NHS Foundation Trust, Burton on Trent, Staffordshire DE13 0RB, UKAbstract: Spontaneous intraorbital hematoma is an uncommon clinical entity seen in ophthalmology practice. It is poorly represented in the literature. Current evidence attributes it to orbital trauma, neoplasm, vascular malformations, acute sinusitis, and systemic abnormalities. A 65-year-old female presented with spontaneous intraorbital hematoma manifesting as severe ocular pains, eyelid edema, proptosis, and diplopia, without a history of trauma. Computer tomography demonstrated a fairly well defined extraconal lesion with opacification of the paranasal sinuses. The principal differential based on all findings was that of a spreading sinus infection and an extraconal tumor. An unprecedented finding of a spontaneous orbital hematoma was discovered when the patient was taken to theater. We discuss the rarity of this condition and its management.Keywords: hemorrhage, ophthalmology, spontaneous, intra-orbital, hematoma
Directory of Open Access Journals (Sweden)
Xiaoli Luan
2016-01-01
Full Text Available The aim of this paper is to determine the stabilizing PID parametric region for multivariable systems. Firstly, a general equivalent transfer function parameterization method is proposed to construct the multiloop equivalent process for multivariable systems. Then, based on the equivalent single loops, a model-based method is presented to derive the stabilizing PID parametric region by using the generalized Hermite-Biehler theorem. By sweeping over the entire ranges of feasible proportional gains and determining the stabilizing regions in the space of integral and derivative gains, the complete set of stabilizing PID controllers can be determined. The robustness of the design procedure against the approximation in getting the SISO plants is analyzed. Finally, simulation of a practical model is carried out to illustrate the effectiveness of the proposed technique.
Spontaneous and stimulated emission from quasifree electrons
Friedman, A.; Gover, A.; Kurizki, G.; Ruschin, S.; Yariv, A.
1988-04-01
This article presents a unified formulation and review of an extensive class of radiation effects and devices based on free or quasifree electrons. The effects and devices reviewed include slow-wave radiators [such as Čerenkov, Smith-Purcell, and TWT (traveling-wave tube) effects and devices], periodic bremsstrahlung radiators [such as undulator radiation, magnetic bremsstrahlung FEL's (free-electron lasers), and coherent bremsstrahlung in the crystal lattice], and transverse-binding radiators [such as the CRM (cyclotron resonance maser) and channeling radiation]. Starting from a general quantum-electrodynamic model, both quantum and classical effects and operating regimes of these radiation devices are described. The article provides a unified physical description of the interaction kinematics, and presents equations for the characterization of spontaneous and stimulated radiative emission in these various effects and devices. Universal relations between the spontaneous and stimulated emission parameters are revealed and shown to be related (in the quantum limit) to Einstein relations for atomic radiators and (in the classical limit) to the relations derived by Madey for magnetic bremsstrahlung FEL for on-axis radiative emission. Examples for the application of the formulation are given, estimating the feasibility of channeling radiation x-ray laser and optical regime Smith-Purcell FEL, and deriving the gain equations of magnetic bremsstrahlung FEL and CRM for arbitrary electron propagation direction, structure (wiggler) axis, and radiative emission angle.
Parametric Approach to Trajectory Tracking Control of Robot Manipulators
Directory of Open Access Journals (Sweden)
Shijie Zhang
2013-01-01
Full Text Available The mathematic description of the trajectory of robot manipulators with the optimal trajectory tracking problem is formulated as an optimal control problem, and a parametric approach is proposed for the optimal trajectory tracking control problem. The optimal control problem is first solved as an open loop optimal control problem by using a time scaling transform and the control parameterization method. Then, by virtue of the relationship between the optimal open loop control and the optimal closed loop control along the optimal trajectory, a practical method is presented to calculate an approximate optimal feedback gain matrix, without having to solve an optimal control problem involving the complex Riccati-like matrix differential equation coupled with the original system dynamics. Simulation results of 2-link robot manipulator are presented to show the effectiveness of the proposed method.
Compact, high-pulse-energy, picosecond optical parametric oscillator.
Kienle, Florian; Teh, Peh Siong; Alam, Shaif-Ul; Gawith, Corin B E; Hanna, David C; Richardson, David J; Shepherd, David P
2010-11-01
We report a high-energy optical parametric oscillator (OPO) synchronously pumped by a 7.19 MHz, Yb:fiber-amplified, picosecond, gain-switched laser diode. The 42-m-long ring cavity maintains a compact design through the use of an intracavity optical fiber. The periodically poled MgO-doped LiNbO(3) OPO provides output pulse energies as high as 0.49 μJ at 1.5 μm (signal) and 0.19 μJ at 3.6 μm (idler). Tunability from 1.5 to 1.7 μm and from 2.9 to 3.6 μm is demonstrated, and typical M(2) values of 1.5 × 1.3 and 2.8 × 1.9 are measured for the signal and idler, respectively, at high power.
Phase Sensitive Amplification using Parametric Processes in Optical Fibers
DEFF Research Database (Denmark)
Kang, Ning
Phase sensitive amplification using the parametric processes in fiber has the potential of delivering high gain and broadband operation with ultralow noise. It is able to regenerate both amplitude and phase modulated signals, simultaneously, with the appropriate design. This thesis concerns......, in specific, the design and optimization of such phase sensitive amplifiers (PSAs). For phase sensitive amplification in highly nonlinear fibers, optima points of operation have been identified for both the standard and the novel high stimulated Brillouin scattering (SBS) threshold highly nonlinear fiber...... types. The regeneration capability of PSAs on phase encoded signal in an optical link has been optimized. Flat-top phase sensitive profile has been synthesized. It is able to provide simultaneous amplitude and phase noise squeezing, with enhanced phase noise margin compared to conventional designs...
Spontaneous ischaemic stroke in dogs
DEFF Research Database (Denmark)
Gredal, Hanne Birgit; Skerritt, G. C.; Gideon, P.
2013-01-01
Translation of experimental stroke research into the clinical setting is often unsuccessful. Novel approaches are therefore desirable. As humans, pet dogs suffer from spontaneous ischaemic stroke and may hence offer new ways of studying genuine stroke injury mechanisms.......Translation of experimental stroke research into the clinical setting is often unsuccessful. Novel approaches are therefore desirable. As humans, pet dogs suffer from spontaneous ischaemic stroke and may hence offer new ways of studying genuine stroke injury mechanisms....
Spontaneity and international marketing performance
Souchon, Anne L.; Hughes, Paul; Farrell, Andrew M.; Nemkova, Ekaterina; Oliveira, Joao S.
2016-01-01
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. Purpose – The purpose of this paper is to ascertain how today’s international marketers can perform better on the global scene by harnessing spontaneity. Design/methodology/approach – The authors draw on contingency theory to develop a model of the spontaneity – international marketing performance relationship, and identify three potential m...
Assessing pupil and school performance by non-parametric and parametric techniques
de Witte, K.; Thanassoulis, E.; Simpson, G.; Battisti, G.; Charlesworth-May, A.
2010-01-01
This paper discusses the use of the non-parametric free disposal hull (FDH) and the parametric multi-level model (MLM) as alternative methods for measuring pupil and school attainment where hierarchical structured data are available. Using robust FDH estimates, we show how to decompose the overall
Verrelst, Jochem; Rivera, Juan Pablo; Veroustraete, Frank; Muñoz-Marí, Jordi; Clevers, J.G.P.W.; Camps-Valls, Gustau; Moreno, José
2015-01-01
Given the forthcoming availability of Sentinel-2 (S2) images, this paper provides a systematic comparison of retrieval accuracy and processing speed of a multitude of parametric, non-parametric and physically-based retrieval methods using simulated S2 data. An experimental field dataset (SPARC),
X-band singly degenerate parametric amplification in a Josephson tunnel junction
DEFF Research Database (Denmark)
Mygind, Jesper; Pedersen, Niels Falsig; Sørensen, O. H.
1978-01-01
Preliminary measurements on a (quasi-) degenerate parametric amplifier using a single Josephson tunnel junction as the active element is reported. The pump frequency is at 18 GHz and the signal and idler frequencies are both at about 9 GHz. A power gain of 16 dB in a 4-MHz 3-dB bandwidth is achie...... is achieved at the top of the cryostat. Applied Physics Letters is copyrighted by The American Institute of Physics....
Experimental observation of parametric effects near period doubling in a loss-modulated CO2 laser
Chizhevsky, V. N.
1996-01-01
A number of parametric effects, such as suppression of period doubling, shift of the bifurcation point, scaling law relating the shift and the perturbation amplitude, influence of the detuning on the suppression, reaching of the maximum gain between the original and shifted bifurcation points, and scaling law for idler power are experimentally observed near period doubling bifurcation in a loss-driven CO2 laser that is subjected to periodic loss perturbations at a frequency that is close to a...
Parametric Generation of Polygonal Tree Models for Rendering on Tessellation-Enabled Hardware
Nystad, Jørgen
2010-01-01
The main contribution of this thesis is a parametric method for generation of single-mesh polygonal tree models that follow natural rules as indicated by da Vinci in his notebooks. Following these rules allow for a relatively simple scheme of connecting branches to parent branches. Proper branch connection is a requirement for gaining the benefits of subdivision. Techniques for proper texture coordinate generation and subdivision are also explored.The result is a tree model generation scheme ...
Parametric Mapping of Contrasted Ovarian Transvaginal Sonography
Korhonen, Katrina; Moore, Ryan; Lyshchik, Andrej; Fleischer, Arthur C.
2014-01-01
The purpose of this study was to assess the accuracy of parametric analysis of transvaginal contrast-enhanced ultrasound (TV-CEUS) for distinguishing benign versus malignant ovarian masses. A total of 48 ovarian masses (37 benign and 11 borderline/malignant) were examined with TV-CEUS (Definity, Lantheus, North Bilreca, MA; Philips iU22, Bothell, WA). Parametric images were created offline with a quantification software (Bracco Suisse SA, Geneva, Switzerland) with map color scales adjusted such that abnormal hemodynamics were represented by the color red and the presence of any red color could be used to differentiate benign and malignant tumors. Using these map color scales, low values of the perfusion parameter were coded in blue, and intermediate values of the perfusion parameter were coded in yellow. Additionally, for each individual color (red, blue, or yellow), a darker shade of that color indicated a higher intensity value. Our study found that the parametric mapping method was considerably more sensitive than standard ROI analysis for the detection of malignant tumors but was also less specific than standard ROI analysis. Parametric mapping allows for stricter cut-off criteria, as hemodynamics are visualized on a finer scale than ROI analyses, and as such, parametric maps are a useful addition to TV-CEUS analysis by allowing ROIs to be limited to areas of highest malignant potential. PMID:26002525
Parametric resonance in concrete beam-columns
Directory of Open Access Journals (Sweden)
Mamta R. Sharma
Full Text Available A dynamic instability, called parametric resonance, is exhibited by undampedelastic beam-columns when under the action of pulsating axial force. The scope of the existing theory of parametric resonance is restricted to physically linear beam-columns undergoing finite lateral displacements. In this Paper, the dynamic behaviour of physically nonlinear elastic cracked concrete beam-columns under pulsating axial force and constant lateral force is investigated. The constitutive equations derived earlier by Authors in the form of force-displacement relations are employed here to formulate equations of motion of the SDOF cantilever with mass lumped at its free end. The expected phenomenon of parametric resonance is exhibited in the form of regular subharmonic resonance at about the frequency ratio of two. Resonance peaks broaden with increase in pulsating force. Like damping, physical nonlinearity is also predicted to stabilize the dynamic response at resonance frequencies. In some particular statically unstable conditions, the loss of dynamic stability is shown to occur by divergence. Unexpectedly, similar phenomenon of parametric resonance is exhibited by these physically nonlinear beam-columns undergoing even small lateral displacements. The contribution made to the theory of parametric resonance and the potential relevance of the proposed theory to design of concrete beam-columns is discussed.
Sudden gains versus gradual gains in a psychotherapy training clinic.
Greenfield, Michael F; Gunthert, Kathleen C; Haaga, David A F
2011-01-01
Sudden gains are abrupt and substantial improvements in symptoms. This study used the Outcome Questionnaire-45 (OQ-45; Lambert et al., 1996) to characterize sudden gains occurring in a cognitive-behavioral therapy training clinic. Also, gradual gainers were identified and used as a comparison group. Sudden gains were identified in 23% of patients and in 29% of those who entered treatment in the clinical range on the OQ, within the range of prevalence established by previous sudden gain studies in the context of randomized controlled trials (RCT's). As in earlier research, sudden gains tended to occur early in therapy. However, sudden gains were more likely to be reversed than in RCT's. Gradual gains occurred for 54% of nonsudden gainers; they were of similar magnitude to sudden gains but occurred later in therapy. Sudden gainers showed significantly better outcomes at the end of treatment than did gradual gainers. Sudden gains have clear prognostic significance, but more research is needed to determine why they may be more transient in naturalistic studies or studies involving less experienced therapists than they are in RCT's. © 2010 Wiley Periodicals, Inc.
Parametric Conversion Using Custom MOS Varactors
Directory of Open Access Journals (Sweden)
Iniewski Krzysztof (Kris
2006-01-01
Full Text Available The possible role of customized MOS varactors in amplification, mixing, and frequency control of future millimeter wave CMOS RFICs is outlined. First, the parametric conversion concept is revisited and discussed in terms of modern RF communications systems. Second, the modeling, design, and optimization of MOS varactors are reconsidered in the context of their central role in parametric circuits. Third, a balanced varactor structure is proposed for robust oscillator frequency control in the presence of large extrinsic noise expected in tightly integrated wireless communicators. Main points include the proposal of a subharmonic pumping scheme based on the MOS varactor, a nonequilibrium elastance-voltage model, optimal varactor layout suggestions, custom m-CMOS varactor design and measurement, device-level balanced varactor simulations, and parametric circuit evaluation based on measured device characteristics.
Piezoelectric energy harvesting with parametric uncertainty
International Nuclear Information System (INIS)
Ali, S F; Friswell, M I; Adhikari, S
2010-01-01
The design and analysis of energy harvesting devices is becoming increasing important in recent years. Most of the literature has focused on the deterministic analysis of these systems and the problem of uncertain parameters has received less attention. Energy harvesting devices exhibit parametric uncertainty due to errors in measurement, errors in modelling and variability in the parameters during manufacture. This paper investigates the effect of parametric uncertainty in the mechanical system on the harvested power, and derives approximate explicit formulae for the optimal electrical parameters that maximize the mean harvested power. The maximum of the mean harvested power decreases with increasing uncertainty, and the optimal frequency at which the maximum mean power occurs shifts. The effect of the parameter variance on the optimal electrical time constant and optimal coupling coefficient are reported. Monte Carlo based simulation results are used to further analyse the system under parametric uncertainty
Parametric methods for spatial point processes
DEFF Research Database (Denmark)
Møller, Jesper
is studied in Section 4, and Bayesian inference in Section 5. On one hand, as the development in computer technology and computational statistics continues,computationally-intensive simulation-based methods for likelihood inference probably will play a increasing role for statistical analysis of spatial...... inference procedures for parametric spatial point process models. The widespread use of sensible but ad hoc methods based on summary statistics of the kind studied in Chapter 4.3 have through the last two decades been supplied by likelihood based methods for parametric spatial point process models......(This text is submitted for the volume ‘A Handbook of Spatial Statistics' edited by A.E. Gelfand, P. Diggle, M. Fuentes, and P. Guttorp, to be published by Chapmand and Hall/CRC Press, and planned to appear as Chapter 4.4 with the title ‘Parametric methods'.) 1 Introduction This chapter considers...
Parametric analysis of ATM solar array.
Singh, B. K.; Adkisson, W. B.
1973-01-01
The paper discusses the methods used for the calculation of ATM solar array performance characteristics and provides the parametric analysis of solar panels used in SKYLAB. To predict the solar array performance under conditions other than test conditions, a mathematical model has been developed. Four computer programs have been used to convert the solar simulator test data to the parametric curves. The first performs module summations, the second determines average solar cell characteristics which will cause a mathematical model to generate a curve matching the test data, the third is a polynomial fit program which determines the polynomial equations for the solar cell characteristics versus temperature, and the fourth program uses the polynomial coefficients generated by the polynomial curve fit program to generate the parametric data.
Parametric Landau damping of space charge modes
Energy Technology Data Exchange (ETDEWEB)
Macridin, Alexandru [Fermilab; Burov, Alexey [Fermilab; Stern, Eric [Fermilab; Amundson, James [Fermilab; Spentzouris, Panagiotis [Fermilab
2016-09-23
Landau damping is the mechanism of plasma and beam stabilization; it arises through energy transfer from collective modes to the incoherent motion of resonant particles. Normally this resonance requires the resonant particle's frequency to match the collective mode frequency. We have identified an important new damping mechanism, parametric Landau damping, which is driven by the modulation of the mode-particle interaction. This opens new possibilities for stability control through manipulation of both particle and mode-particle coupling spectra. We demonstrate the existence of parametric Landau damping in a simulation of transverse coherent modes of bunched accelerator beams with space charge.
Universal parametrization for quark and lepton substructure
International Nuclear Information System (INIS)
Akama, Keiichi; Terazawa, Hidezumi.
1994-01-01
A universal parametrization for possible quark and lepton substructure is advocated in terms of quark and lepton form factors. It is emphasized that the lower bounds on compositeness scale, Λ c , to be determined experimentally strongly depend on their definitions in composite models. From the recent HERA data, it is estimated to be Λ c > 50 GeV, 0.4 TeV and 10 TeV, depending on the parametrizations with a single-pole form factor, a contact interaction and a logarithmic form factor, respectively. (author)
Analytical modeling of parametrically modulated transmon qubits
Didier, Nicolas; Sete, Eyob A.; da Silva, Marcus P.; Rigetti, Chad
2018-02-01
Building a scalable quantum computer requires developing appropriate models to understand and verify its complex quantum dynamics. We focus on superconducting quantum processors based on transmons for which full numerical simulations are already challenging at the level of qubytes. It is thus highly desirable to develop accurate methods of modeling qubit networks that do not rely solely on numerical computations. Using systematic perturbation theory to large orders in the transmon regime, we derive precise analytic expressions of the transmon parameters. We apply our results to the case of parametrically modulated transmons to study recently implemented, parametrically activated entangling gates.
Parametric frequency conversion in long Josephson junctions
International Nuclear Information System (INIS)
Irie, F.; Ashihara, S.; Yoshida, K.
1976-01-01
Current steps at voltages corresponding to the parametric coupling between an applied r.f. field and junction resonant modes have been observed in long Josephson tunnel junctions in the flux-flow state. The observed periodic variations of the step height due to the applied magnetic field are explained quantitatively by a perturbational analysis using Josephson phase equations. The present study demonstrates that the moving vortex array can serve as a coherent pump wave for signal waves propagating in the barrier region, which indicates, as a result, the possibility of traveling-wave parametric devices with long Josephson tunnel junctions. (author)
Revisiting Parametric Types and Virtual Classes
DEFF Research Database (Denmark)
Madsen, Anders Bach; Ernst, Erik
2010-01-01
This paper presents a conceptually oriented updated view on the relationship between parametric types and virtual classes. The traditional view is that parametric types excel at structurally oriented composition and decomposition, and virtual classes excel at specifying mutually recursive families...... of classes whose relationships are preserved in derived families. Conversely, while class families can be specified using a large number of F-bounded type parameters, this approach is complex and fragile; and it is difficult to use traditional virtual classes to specify object composition in a structural......, it shows how a novel kind of dynamic type check can detect compatibility among entire families of classes....
A Comparison of Parametric and Non-Parametric Methods Applied to a Likert Scale.
Mircioiu, Constantin; Atkinson, Jeffrey
2017-05-10
A trenchant and passionate dispute over the use of parametric versus non-parametric methods for the analysis of Likert scale ordinal data has raged for the past eight decades. The answer is not a simple "yes" or "no" but is related to hypotheses, objectives, risks, and paradigms. In this paper, we took a pragmatic approach. We applied both types of methods to the analysis of actual Likert data on responses from different professional subgroups of European pharmacists regarding competencies for practice. Results obtained show that with "large" (>15) numbers of responses and similar (but clearly not normal) distributions from different subgroups, parametric and non-parametric analyses give in almost all cases the same significant or non-significant results for inter-subgroup comparisons. Parametric methods were more discriminant in the cases of non-similar conclusions. Considering that the largest differences in opinions occurred in the upper part of the 4-point Likert scale (ranks 3 "very important" and 4 "essential"), a "score analysis" based on this part of the data was undertaken. This transformation of the ordinal Likert data into binary scores produced a graphical representation that was visually easier to understand as differences were accentuated. In conclusion, in this case of Likert ordinal data with high response rates, restraining the analysis to non-parametric methods leads to a loss of information. The addition of parametric methods, graphical analysis, analysis of subsets, and transformation of data leads to more in-depth analyses.
Sympathetic baroreflex gain in normotensive pregnant women.
Usselman, Charlotte W; Skow, Rachel J; Matenchuk, Brittany A; Chari, Radha S; Julian, Colleen G; Stickland, Michael K; Davenport, Margie H; Steinback, Craig D
2015-09-01
Muscle sympathetic nerve activity is increased during normotensive pregnancy while mean arterial pressure is maintained or reduced, suggesting baroreflex resetting. We hypothesized spontaneous sympathetic baroreflex gain would be reduced in normotensive pregnant women relative to nonpregnant matched controls. Integrated muscle sympathetic burst incidence and total sympathetic activity (microneurography), blood pressure (Finometer), and R-R interval (ECG) were assessed at rest in 11 pregnant women (33 ± 1 wk gestation, 31 ± 1 yr, prepregnancy BMI: 23.5 ± 0.9 kg/m(2)) and 11 nonpregnant controls (29 ± 1 yr; BMI: 25.2 ± 1.7 kg/m(2)). Pregnant women had elevated baseline sympathetic burst incidence (43 ± 2 vs. 33 ± 2 bursts/100 heart beats, P = 0.01) and total sympathetic activity (1,811 ± 148 vs. 1,140 ± 55 au, P baroreflex set point with pregnancy. Baroreflex gain, calculated as the linear relationship between sympathetic burst incidence and DBP, was reduced in pregnant women relative to controls (-3.7 ± 0.5 vs. -5.4 ± 0.5 bursts·100 heart beats(-1)·mmHg(-1), P = 0.03), as was baroreflex gain calculated with total sympathetic activity (-294 ± 24 vs. -210 ± 24 au·100 heart beats(-1)·mmHg(-1); P = 0.03). Cardiovagal baroreflex gain (sequence method) was not different between nonpregnant controls and pregnant women (49 ± 8 vs. 36 ± 8 ms/mmHg; P = 0.2). However, sympathetic (burst incidence) and cardiovagal gains were negatively correlated in pregnant women (R = -0.7; P = 0.02). Together, these data indicate that the influence of the sympathetic nervous system over arterial blood pressure is reduced in normotensive pregnancy, in terms of both long-term and beat-to-beat regulation of arterial pressure, likely through a baroreceptor-dependent mechanism. Copyright © 2015 the American Physiological Society.
A case of spontaneous ventriculocisternostomy
International Nuclear Information System (INIS)
Yamane, Kanji; Yoshimoto, Hisanori; Harada, Kiyoshi; Uozumi, Tohru; Kuwabara, Satoshi.
1983-01-01
The authors experienced a case of spontaneous ventriculocisternostomy diagnosed by CT scan with metrizamide and Conray. Patient was 23-year-old male who had been in good health until one month before admission, when he began to have headache and tinnitus. He noticed bilateral visual acuity was decreased about one week before admission and vomiting appeared two days before admission. He was admitted to our hospital because of bilateral papilledema and remarkable hydrocephalus diagnosed by CT scan. On admission, no abnormal neurological signs except for bilateral papilledema were noted. Immediately, right ventricular drainage was performed. Pressure of the ventricle was over 300mmH 2 O and CSF was clear. PVG and PEG disclosed an another cavity behind the third ventricle, which was communicated with the third ventricle, and occlusion of aqueduct of Sylvius. Metrizamide CT scan and Conray CT scan showed a communication between this cavity and quadrigeminal and supracerebellar cisterns. On these neuroradiological findings, the diagnosis of obstructive hydrocephalus due to benign aqueduct stenosis accompanied with spontaneous ventriculocisternostomy was obtained. Spontaneous ventriculocisternostomy was noticed to produce arrest of hydrocephalus, but with our case, spontaneous regression of such symptoms did not appeared. By surgical ventriculocisternostomy (method by Torkildsen, Dandy, or Scarff), arrest of hydrocephalus was seen in about 50 to 70 per cent, which was the same results as those of spontaneous ventriculocisternostomy. It is concluded that VP shunt or VA shunt is thought to be better treatment of obstructive hydrocephalus than the various kinds of surgical ventriculocisternostomy. (J.P.N.)
Optical antenna enhanced spontaneous emission.
Eggleston, Michael S; Messer, Kevin; Zhang, Liming; Yablonovitch, Eli; Wu, Ming C
2015-02-10
Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ∼ 200 THz optical frequency show a spontaneous emission intensity enhancement of 35 × corresponding to a spontaneous emission rate speedup ∼ 115 ×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ∼ 2,500 × spontaneous emission speedup at d ∼ 10 nm, proportional to 1/d(2). Unfortunately, at d antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, I(o) = qω|x(o)|/d, feeding the antenna-enhanced spontaneous emission, where q|x(o)| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Moreover, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency.
Spontaneous subcapsular and perirrenal hemorrhage
International Nuclear Information System (INIS)
Fuster, M.J.; Saez, J.; Perez-Paya, F.J.; Fernandez, F.
1997-01-01
To assess the role of CT in the etiologic diagnosis of spontaneous subcapsular and perirrenal hemorrhage. The CT findings are described in 13 patients presenting subcapsular and perirrenal hemorrhage. Those patients in whom the bleeding was not spontaneous were excluded. Surgical confirmation was obtained in nine cases. In 11 of the 13 cases (84.6%), involving five adenocarcinomas, five angiomyolipoma, two complicated cysts and one case of panarterities nodosa, CT disclosed the underlying pathology. In two cases (15.4%), it only revealed the extension of the hematoma, but gave no clue to its origin. CT is the technique of choice when spontaneous subcapsular and perirrenal hemorrhage is suspected since, in most cases, it reveals the underlying pathology. (Author)
Parametric Primitives for Hand Gesture Recognition
DEFF Research Database (Denmark)
Baby, Sanmohan; Krüger, Volker
2009-01-01
Imitation learning is considered to be an effective way of teaching humanoid robots and action recognition is the key step to imitation learning. In this paper an online algorithm to recognize parametric actions with object context is presented. Objects are key instruments in understanding...
Parametric Transverse Patterns in Broad Aperture Lasers
DEFF Research Database (Denmark)
Grigorieva, E.V.; Kashchenko, S.A.; Mosekilde, Erik
1998-01-01
Parametrically generated optical patterns are investigated for finite and large-scale transverse aperture lasers. Standing and rotating patterns as well as periodic and chaotic pattern alternations are described in the framework of the amplitude equation formalism. Sensitive dependence...... on the geometrical size of the system is demonstrated even in the case of large-scale systems....
Consequences of hadron-nucleus multiplicity parametrization
International Nuclear Information System (INIS)
Singh, C.P.; Shyam, M.
1986-01-01
Some interesting consequences are analyzed of a new parametrization for the hadron-nucleus multiplicity distributions and they are compared with the experimental data. Further, it is illustrated how the scaling property for the average multiplicity will be modified and it is found that the experimental data support this behaviour. (orig.)
Simple parametrization of nucleon form factors
International Nuclear Information System (INIS)
Kelly, J.J.
2004-01-01
This Brief Report provides simple parametrizations of the nucleon electromagnetic form factors using functions of Q 2 that are consistent with dimensional scaling at high Q 2 . Good fits require only four parameters each for G Ep , G Mp , and G Mn and only two for G En
Measurement selection for parametric IC fault diagnosis
Wu, A.; Meador, J.
1991-01-01
Experimental results obtained with the use of measurement reduction for statistical IC fault diagnosis are described. The reduction method used involves data pre-processing in a fashion consistent with a specific definition of parametric faults. The effects of this preprocessing are examined.
The parametrized simulation of electromagnetic showers
International Nuclear Information System (INIS)
Peters, S.
1992-09-01
The simulation of electromagnetic showers in calorimeters by detailed tracking of all secondary particles is extremely computer time consuming. Without loosing considerably in precision, the use of parametrizations for global shower properties may reduce the computing time by factors of 10 1 to 10 4 , depending on the energy, the degree of parametrization, and the complexity in the material description and the cut off energies in the detailed simulation. To arrive at a high degree of universality, parametrizations of individual electromagnetic showers in homogeneous media are developed, taking the dependence of the shower development on the material into account. In sampling calorimeters, the inhomogeneous material distribution leads to additional effects which can be taken into account by geometry dependent terms in the parametrization of the longitudinal and radial energy density distributions. Comparisons with detailed simulations of homogeneous and sampling calorimeters show very good agreement in the fluctuations, correlations, and signal averages of spatial energy distributions. Verifications of the algorithms for the simulation of the H1 detector are performed using calorimeter test data for different moduls of the H1 liquid argon calorimeter. Special attention has been paid to electron pion separation, which is of great importance for physics analysis. (orig.) [de
Recursive Delay Calculation Unit for Parametric Beamformer
DEFF Research Database (Denmark)
Nikolov, Svetoslav; Jensen, Jørgen Arendt; Tomov, Borislav Gueorguiev
2006-01-01
This paper presents a recursive approach for parametric delay calculations for a beamformer. The suggested calculation procedure is capable of calculating the delays for any image line defined by an origin and arbitrary direction. It involves only add and shift operations making it suitable...
Statistical prediction of parametric roll using FORM
DEFF Research Database (Denmark)
Jensen, Jørgen Juncher; Choi, Ju-hyuck; Nielsen, Ulrik Dam
2017-01-01
Previous research has shown that the First Order Reliability Method (FORM) can be an efficient method for estimation of outcrossing rates and extreme value statistics for stationary stochastic processes. This is so also for bifurcation type of processes like parametric roll of ships. The present...
Detection of Parametric Roll on Ships
DEFF Research Database (Denmark)
Galeazzi, Roberto; Blanke, Mogens; Poulsen, Niels Kjølstad
2012-01-01
Recent years have shown several incidents with dramatic damage on container vessels caused by parametric resonance. When the resonance starts, the roll oscillation at a sub-harmonic frequency of the wave excitation may be completely unexpected. Timely warning about the onset of the resonance...... on experimental data from towing tank tests and data from a container ship passing an Atlantic storm....
Optical parametric amplification beyond the slowly varying ...
Indian Academy of Sciences (India)
The coupled-wave equations describing optical parametric amplification (OPA) are usually solved in the slowly varying amplitude (SVA) approximation regime, in which the second-order derivatives of the signal and idler amplitudes are ignored and in fact the electromagnetic effects due to exit face of the medium is not ...
Probabilistic Reachability for Parametric Markov Models
DEFF Research Database (Denmark)
Hahn, Ernst Moritz; Hermanns, Holger; Zhang, Lijun
2011-01-01
of states (n(log n)).We therefore proceed differently, by tightly intertwining the regular expression computation with its evaluation. This allows us to arrive at an effective method that avoids this blow up in most practical cases. We give a detailed account of the approach, also extending to parametric...
A parametric reconstruction of the deceleration parameter
Energy Technology Data Exchange (ETDEWEB)
Al Mamon, Abdulla [Manipal University, Manipal Centre for Natural Sciences, Manipal (India); Visva-Bharati, Department of Physics, Santiniketan (India); Das, Sudipta [Visva-Bharati, Department of Physics, Santiniketan (India)
2017-07-15
The present work is based on a parametric reconstruction of the deceleration parameter q(z) in a model for the spatially flat FRW universe filled with dark energy and non-relativistic matter. In cosmology, the parametric reconstruction technique deals with an attempt to build up a model by choosing some specific evolution scenario for a cosmological parameter and then estimate the values of the parameters with the help of different observational datasets. In this paper, we have proposed a logarithmic parametrization of q(z) to probe the evolution history of the universe. Using the type Ia supernova, baryon acoustic oscillation and the cosmic microwave background datasets, the constraints on the arbitrary model parameters q{sub 0} and q{sub 1} are obtained (within 1σ and 2σ confidence limits) by χ{sup 2}-minimization technique. We have then reconstructed the deceleration parameter, the total EoS parameter ω{sub tot}, the jerk parameter and have compared the reconstructed results of q(z) with other well-known parametrizations of q(z). We have also shown that two model selection criteria (namely, the Akaike information criterion and Bayesian information criterion) provide a clear indication that our reconstructed model is well consistent with other popular models. (orig.)
PARAMETRIC RESONANSE IN STATICALLY INDETERMINATE FRAMES
Directory of Open Access Journals (Sweden)
Yu.V. Vorona
2014-12-01
Full Text Available The technique for development and reduction of discrete dynamics models of frames is presented. Construction of the models is carried out using finite element method, generalized coordinates and tools of modern computer software. Parametric resonance in a statically indeterminate frame caused by external excitations is investigated. Main instability domains of the frame are determined.
Parametric diffusion tensor imaging of the breast.
Eyal, Erez; Shapiro-Feinberg, Myra; Furman-Haran, Edna; Grobgeld, Dov; Golan, Talia; Itzchak, Yacov; Catane, Raphael; Papa, Moshe; Degani, Hadassa
2012-05-01
To investigate the ability of parametric diffusion tensor imaging (DTI), applied at 3 Tesla, to dissect breast tissue architecture and evaluate breast lesions. All protocols were approved and a signed informed consent was obtained from all subjects. The study included 21 healthy women, 26 women with 33 malignant lesions, and 14 women with 20 benign lesions. Images were recorded at 3 Tesla with a protocol optimized for breast DTI at a spatial resolution of 1.9 × 1.9 × (2-2.5) mm3. Image processing algorithms and software, applied at pixel resolution, yielded vector maps of prime diffusion direction and parametric maps of the 3 orthogonal diffusion coefficients and of the fractional anisotropy and maximal anisotropy. The DTI-derived vector maps and parametric maps revealed the architecture of the entire mammary fibroglandular tissue and allowed a reliable detection of malignant lesions. Cancer lesions exhibited significantly lower values of the orthogonal diffusion coefficients, λ1, λ2, λ3, and of the maximal anisotropy index λ1-λ3 as compared with normal breast tissue (P architecture. Parametric maps of λ1 and λ1-λ3 facilitate the detection and diagnosis of breast cancer.
Narrow linewidth pulsed optical parametric oscillator
Indian Academy of Sciences (India)
Abstract. Tunable narrow linewidth radiation by optical parametric oscillation has many applications, particularly in spectroscopic investigation. In this paper, different techniques such as injection seeding, use of spectral selecting element like grating, grat- ing and etalon in combination, grazing angle of incidence, entangled ...
A Decomposition Algorithm for Parametric Design
Jauregui Becker, Juan Manuel; Schotborgh, W.O.; van Houten, Frederikus J.A.M.; Culley, T.C.; Hicks, B.J.; McAloone, T.C.; Howard, T.J.; Dong, A.
2011-01-01
This paper presents a recursive division algorithm to decompose an under constraint parametric design problem. The algorithm defines the separation of the problem at the hand of two complexity measures that are calculated for each parameter in the problem, namely, the effort E and the influence Inf.
Exercise in Configurable Products using Creo parametric
DEFF Research Database (Denmark)
Christensen, Georg Kronborg
2017-01-01
Family tables is a long know method with ProEngineer/Creo parametric to make families of products – like families of bolts and roller bearings. Configurable Products expand these possibilities in two major ways: First it makes configurable assemblies possible where one topologically different...
Interdisciplinary parametric design : The XXL experience
Turrin, M.; Sariyildiz, I.S.; Paul, J.C.
2015-01-01
Focusing on large span structures for sport buildings, the paper tackles the role of parametric modelling and performance simulations, to enhance the integration between architectural and engineering design. The general approach contrasts post-engineering processes. In post-engineering, technical
Using Parametrics to Facilitate Collaborative Urban Design
DEFF Research Database (Denmark)
Steinø, Nicolai; Benbih, Karima; Obeling, Esben
2013-01-01
in the context of the urban South which is characterized by high urban growth rates, weak planning systems and modest means. The current state of planning and urban development in Morocco is introduced as a context for discussing collaborative urban design and parametric urban design, and some tentative...
Spontaneous isolated celiac artery dissection
Directory of Open Access Journals (Sweden)
Tuba Cimilli Ozturk
2011-01-01
Full Text Available Dyspepsia with mild, stabbing epigastric discomfort without history of trauma is a very common symptom that emergency physicians see in their daily practice. Vascular emergencies, mostly the aortic dissection and aneurysm, are always described in the differential diagnosis with persistent symptoms. Isolated celiac artery dissection occurring spontaneously is a very rare diagnosis. The involvement of branch vessels is generally observed and patients show various clinical signs and symptoms according to the involved branch vessel. Here we are presenting a case with spontaneous isolated celiac artery dissection, without any branch vessel involvement or visceral damage, detected by computed tomography scans taken on admission.
Spontaneous waves in muscle fibres
Energy Technology Data Exchange (ETDEWEB)
Guenther, Stefan; Kruse, Karsten [Department of Theoretical Physics, Saarland University, 66041 Saarbruecken (Germany); Max Planck Institute for the Physics of Complex Systems, Noethnitzer Street 38, 01187 Dresden (Germany)
2007-11-15
Mechanical oscillations are important for many cellular processes, e.g. the beating of cilia and flagella or the sensation of sound by hair cells. These dynamic states originate from spontaneous oscillations of molecular motors. A particularly clear example of such oscillations has been observed in muscle fibers under non-physiological conditions. In that case, motor oscillations lead to contraction waves along the fiber. By a macroscopic analysis of muscle fiber dynamics we find that the spontaneous waves involve non-hydrodynamic modes. A simple microscopic model of sarcomere dynamics highlights mechanical aspects of the motor dynamics and fits with the experimental observations.
High Gain Advanced GPS Receiver
National Research Council Canada - National Science Library
Brown, Alison; Zhang, Gengsheng
2006-01-01
NAVSYS High Gain Advanced GPS Receiver (HAGR) uses a digital beam-steering antenna array to enable up to eight GPS satellites to be tracked, each with up to 10 dBi of additional antenna gain over a conventional receiver solution...
PARAMETRICAL WORDS IN THE SENTIMENT LEXICON
Directory of Open Access Journals (Sweden)
Elena Brunova
2013-12-01
Full Text Available In this paper, the main features of parametrical words within a sentiment lexicon are determined. The data for the research are client reviews in the Russian language taken from the bank client rating; the domain under study is bank service quality. The lexicon structure and the fragments from the lexicon database are presented. The sentiment lexicon includes two major classes (positive and negative words and three minor classes (increments, polarity modifiers, and polarity anti-modifiers. This lexicon is used as the main tool for the sentiment analysis carried out by two methods: the Naïve Bayes and the REGEX algorithms.Parametrical words are referred to as the words denoting the value of some domain-specific parameter, e.g. a battery life, or time of waiting. To distinguish the main features of parametrical words, the parameters relevant for the bank service quality domain are determined. The results of the research demonstrate that parametrical words can be ranged neither in the positive class, nor in the negative one. The words denoting the increase of a parameter should be ranged in the increment class, as they intensify positive or negative emotions. The words denoting the decrease of a parameter should be ranged in a new class which may be called the decrement class, as they reduce positive or negative emotions. The revised lexicon structure including the decrement class is proposed. The evident progress on the way to the lexicon universalization can be achieved by distinguishing two special classes for lexical increments and decrements. Another helpful idea is to extract bigrams or trigrams which could include parametrical words and the domain attributes they refer to.
Parametric instabilities in magnetized bi-ion and dusty plasmas
Indian Academy of Sciences (India)
-ion or dusty plasma with parametric pumping of the magnetic field is analysed. The equation of motion governing the perturbed plasma is derived and parametrically excited transverse modes propagating along the magnetic field are found.
DEFF Research Database (Denmark)
Ambühl, Lea Maria Margareta; Baandrup, Ulrik; Dybkær, Karen
2016-01-01
, and 10.9% (95% CI; 10.1–11.7) for umbilical cord blood. Summary estimates for HPV prevalence of spontaneous abortions and spontaneous preterm deliveries, in cervix (spontaneous abortions: 24.5%, and pretermdeliveries: 47%, resp.) and placenta (spontaneous abortions: 24.9%, and preterm deliveries: 50......%, resp.), were identified to be higher compared to normal full-term pregnancies (푃 spontaneous abortion, spontaneous preterm...
Fault detection and isolation in systems with parametric faults
DEFF Research Database (Denmark)
Stoustrup, Jakob; Niemann, Hans Henrik
1999-01-01
The problem of fault detection and isolation of parametric faults is considered in this paper. A fault detection problem based on parametric faults are associated with internal parameter variations in the dynamical system. A fault detection and isolation method for parametric faults is formulated...... in a standard setup and a synthesis method for fault detectors is given. Further, fault detection problems with both parametric faults and faults described by external input signals are also shortly considered....
Meta-analysis of candidate gene effects using bayesian parametric and non-parametric approaches.
Wu, Xiao-Lin; Gianola, Daniel; Rosa, Guilherme J M; Weigel, Kent A
2014-01-01
Candidate gene (CG) approaches provide a strategy for identification and characterization of major genes underlying complex phenotypes such as production traits and susceptibility to diseases, but the conclusions tend to be inconsistent across individual studies. Meta-analysis approaches can deal with these situations, e.g., by pooling effect-size estimates or combining P values from multiple studies. In this paper, we evaluated the performance of two types of statistical models, parametric and non-parametric, for meta-analysis of CG effects using simulated data. Both models estimated a "central" effect size while taking into account heterogeneity over individual studies. The empirical distribution of study-specific CG effects was multi-modal. The parametric model assumed a normal distribution for the study-specific CG effects whereas the non-parametric model relaxed this assumption by posing a more general distribution with a Dirichlet process prior (DPP). Results indicated that the meta-analysis approaches could reduce false positive or false negative rates by pooling strengths from multiple studies, as compared to individual studies. In addition, the non-parametric, DPP model captured the variation of the "data" better than its parametric counterpart.
Spontaneous emission by moving atoms
International Nuclear Information System (INIS)
Meystre, P.; Wilkens, M.
1994-01-01
It is well known that spontaneous emission is not an intrinsic atomic property, but rather results from the coupling of the atom to the vacuum modes of the electromagnetic field. As such, it can be modified by tailoring the electromagnetic environment into which the atom can radiate. This was already realized by Purcell, who noted that the spontaneous emission rate can be enhanced if the atom placed inside a cavity is resonant with one of the cavity is resonant with one of the cavity modes, and by Kleppner, who discussed the opposite case of inhibited spontaneous emission. It has also been recognized that spontaneous emission need not be an irreversible process. Indeed, a system consisting of a single atom coupled to a single mode of the electromagnetic field undergoes a periodic exchange of excitation between the atom and the field. This periodic exchange remains dominant as long as the strength of the coupling between the atom and a cavity mode is itself dominant. 23 refs., 6 figs
Spontaneous Development of Moral Concepts
Siegal, M.
1975-01-01
Moral competence is more difficult to attain than scientific competence. Since language comprehension plays a central role in conceptual development, and moral language is difficult to learn, there is a common deficiency in moral conceptual development. This suggests a theory of non-spontaneous solutions to moral problems. (Author/MS)
Shell theorem for spontaneous emission
DEFF Research Database (Denmark)
Kristensen, Philip Trøst; Mortensen, Jakob Egeberg; Lodahl, Peter
2013-01-01
and therefore is given exactly by the dipole approximation theory. This surprising result is a spontaneous emission counterpart to the shell theorems of classical mechanics and electrostatics and provides insights into the physics of mesoscopic emitters as well as great simplifications in practical calculations....
Prediction of Spontaneous Preterm Birth
Dijkstra, Karolien
2002-01-01
Preterm birth is a leading cause of neonatal morbidity and mortality. It is a major goal in obstetrics to lower the incidence of spontaneous preterm birth (SPB) and related neonatal morbidity and mortality. One of the principal objectives is to discover early markers that would allow us to identify
African Journals Online (AJOL)
2008-12-12
Dec 12, 2008 ... surgical abortion at one month gestation without any complication. The second pregnancy which was a year prior resulted in a spontaneous miscarriage at two months followed by evacuation of retained products of conception with no post abortion complications. Antibiotics were taken following both.
Spontaneous fission of superheavy nuclei
Indian Academy of Sciences (India)
the Yukawa-plus-exponential potential. The microscopic shell and pairing corrections are obtained using the Strutinsky and BCS approaches and the cranking formulae yield the inertia tensor. Finally, the WKB method is used to calculate penetrabilities and spontaneous fission half-lives. Calculations are performed for the ...
Spontaneous Ovarian Hyperstimulation Syndrome in a Term Pregnancy
Directory of Open Access Journals (Sweden)
Aytekin Tokmak
2015-09-01
Full Text Available Spontaneous OHSS in a term pregnancy is extremely rare. The aim of this study is to present a case of spontaneous ovarian hyperstimulation syndrome (OHSS in a term pregnancy. A 29-year-old primigravida woman conceived spontaneously and was observed up until 35 weeks of gestation. During this time the patient had a normal pregnancy with normal ovaries. She applied to the current clinic during the 37th week of gestation with complaints of rapid weight gain, abdominal disturbance, and pain. Ultrasound examination showed large bilateral ovaries with multiple follicles and mild ascites. At 39 weeks of gestation, the ovaries were the same as detected previously, and a caesarean section was performed due to fetal macrosomia. A healthy female foetus weighing 4060 gr was delivered. The enlarged bilateral ovaries containing multiple follicles were drilled with electrocautery. The ovaries returned to a near normal state for two weeks after the birth. There are no reported cases of spontaneous OHSS in late pregnancy in the literature. Ovarian drilling may be useful during caesarean section. [Cukurova Med J 2015; 40(3.000: 623-626
Parametric Audio Based Decoder and Music Synthesizer for Mobile Applications
Oomen, A.W.J.; Szczerba, M.Z.; Therssen, D.
2011-01-01
This paper reviews parametric audio coders and discusses novel technologies introduced in a low-complexity, low-power consumption audiodecoder and music synthesizer platform developed by the authors. Thedecoder uses parametric coding scheme based on the MPEG-4 Parametric Audio standard. In order to
Fault detection and isolation in systems with parametric faults
DEFF Research Database (Denmark)
Stoustrup, Jakob; Niemann, Hans Henrik
1999-01-01
The problem of fault detection and isolation of parametric faults is considered in this paper. A fault detection problem based on parametric faults are associated with internal parameter variations in the dynamical system. A fault detection and isolation method for parametric faults is formulated...
Open standard CMO for parametric modelling based on semantic web
Bonsma, P.; Bonsma, I.; Zayakova, T.; Van Delft, A.; Sebastian, R.; Böhms, M.
2015-01-01
The Open Standard Concept Modelling Ontology (CMO) with Extensions makes it possible to store parametric modelling semantics and parametric geometry in a Semantic Web environment. The parametric and geometrical part of CMO with Extensions is developed within the EU project Proficient. The nature of
Timing and amplitude jitter in a gain-switched multimode semiconductor laser
Wada, Kenji; Kitagawa, Naoaki; Matsukura, Satoru; Matsuyama, Tetsuya; Horinaka, Hiromichi
2016-04-01
The differences in timing jitter between a gain-switched single-mode semiconductor laser and a gain-switched multimode semiconductor laser are examined using rate equations that include Langevin noise. The timing jitter in a gain-switched multimode semiconductor laser is found to be effectively suppressed by a decrease in the coherence time of the amplified spontaneous emission (ASE) based on a broad bandwidth of multimode oscillation. Instead, fluctuations in the ASE cause amplitude jitter in the pulse components of the respective modes. A pulse train of gain-switched pulses from a multimode semiconductor laser with timing jitter is equivalently simulated by assuming a high spontaneous emission factor and a short coherence time of the ASE in the single-mode semiconductor laser rate equations.
ADAPTIVE OUTPUT CONTROL OF MULTICHANNEL LINEAR STATIONARY SYSTEMS UNDER PARAMETRIC UNCERTAINTY
Directory of Open Access Journals (Sweden)
Aleksei A. Bobtsov
2014-11-01
Full Text Available The paper deals with the problem of adaptive control for multi-channel linear stationary plants under parametric uncertainty with arbitrary relative degree of each local subsystem. The synthesized regulator provides stabilization of control plant on condition that for each local subsystem only output variables are measured with known relative degrees, but the order of linear differential equations is unknown. We consider the synthesis of control system for two-channel system for simplification of the synthesis method. The "serial compensator" algorithm is chosen as basic approach with A.L. Fradkov's passification theorem and additional filters containing high gain constants in their structure. Durability of the closed system in the group of pointed types of regulators is analyzed and the necessary and sufficient conditions for exponential convergence properties are considered. We suggest adaptive version of the "serial compensator" method from the practical point of view, where customization of the gain constant is based on the integral type algorithm. We show the results of computer simulation for the third and second order subsystems under parametric uncertainty to illustrate the proposed approach workability. It is shown that the proposed technique makes it possible to synthesize control algorithms for multichannel systems under parametric uncertainty with minimal dynamical order as compared to known foreign and domestic counterparts.
Diversity Gain through Antenna Blocking
Directory of Open Access Journals (Sweden)
V. Dehghanian
2012-01-01
Full Text Available As part of the typical usage mode, interaction between a handheld receiver antenna and the operator's RF absorbing body and nearby objects is known to generate variability in antenna radiation characteristics through blocking and pattern changes. It is counterintuitive that random variations in blocking can result in diversity gain of practical applicability. This diversity gain is quantified from a theoretical and experimental perspective. Measurements carried out at 1947.5 MHz verify the theoretical predictions, and a diversity gain of 3.1 dB was measured through antenna blocking and based on the utilized measurement setup. The diversity gain can be exploited to enhance signal detectability of handheld receivers based on a single antenna in indoor multipath environments.
Spontaneous Retropharyngeal Emphysema: A Case Report | Chi ...
African Journals Online (AJOL)
... is a rare clinical condition in pediatric otolaryngology. The predominant symptoms are sore throat, odynophagia, dysphagia, and neck pain. Here, we report a case of spontaneous retropharyngeal emphysema. Keywords: Iatrogenic injury, retropharyngeal emphysema, spontaneous retropharyngeal emphysem, trauma ...
La maladie de Grisel : Spontaneous atlantoaxial subluxation
Meek, MF; Robinson, PH; Hermens, RAEC
Objective: "La maladie de Grisel" (Grisel's syndrome) is a spontaneously occurring atlantoaxial subluxation with torticollis. We present a case of atlantoaxial subluxation occurring in a 20-year period of pharyngoplasty surgery. The occurrence of a "spontaneous" atlantoaxial subluxation after oral
Rayleigh-type parametric chemical oscillation
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Shyamolina; Ray, Deb Shankar, E-mail: pcdsr@iacs.res.in [Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)
2015-09-28
We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions.
Parametric Amplification of a Superconducting Plasma Wave.
Rajasekaran, S; Casandruc, E; Laplace, Y; Nicoletti, D; Gu, G D; Clark, S R; Jaksch, D; Cavalleri, A
2016-11-01
Many applications in photonics require all-optical manipulation of plasma waves1, which can concentrate electromagnetic energy on sub-wavelength length scales. This is difficult in metallic plasmas because of their small optical nonlinearities. Some layered superconductors support Josephson plasma waves (JPWs)2,3, involving oscillatory tunneling of the superfluid between capacitively coupled planes. Josephson plasma waves are also highly nonlinear4, and exhibit striking phenomena like cooperative emission of coherent terahertz radiation5,6, superconductor-metal oscillations7 and soliton formation8. We show here that terahertz JPWs can be parametrically amplified through the cubic tunneling nonlinearity in a cuprate superconductor. Parametric amplification is sensitive to the relative phase between pump and seed waves and may be optimized to achieve squeezing of the order parameter phase fluctuations9 or single terahertz-photon devices.
Rayleigh-type parametric chemical oscillation.
Ghosh, Shyamolina; Ray, Deb Shankar
2015-09-28
We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions.
Universal Stabilization of a Parametrically Coupled Qubit
Lu, Yao; Chakram, S.; Leung, N.; Earnest, N.; Naik, R. K.; Huang, Ziwen; Groszkowski, Peter; Kapit, Eliot; Koch, Jens; Schuster, David I.
2017-10-01
We autonomously stabilize arbitrary states of a qubit through parametric modulation of the coupling between a fixed frequency qubit and resonator. The coupling modulation is achieved with a tunable coupling design, in which the qubit and the resonator are connected in parallel to a superconducting quantum interference device. This allows for quasistatic tuning of the qubit-cavity coupling strength from 12 MHz to more than 300 MHz. Additionally, the coupling can be dynamically modulated, allowing for single-photon exchange in 6 ns. Qubit coherence times exceeding 20 μ s are maintained over the majority of the range of tuning, limited primarily by the Purcell effect. The parametric stabilization technique realized using the tunable coupler involves engineering the qubit bath through a combination of photon nonconserving sideband interactions realized by flux modulation, and direct qubit Rabi driving. We demonstrate that the qubit can be stabilized to arbitrary states on the Bloch sphere with a worst-case fidelity exceeding 80%.
Parametric Design Strategies for Collaborative Urban Design
DEFF Research Database (Denmark)
Steinø, Nicolai; Yıldırım, Miray Baş; Özkar, Mine
2013-01-01
started in 1960’s to increase social responsibility Participation seeks to enable the equality among stakeholders and to constitute the notion of belonging and being part of a community. However, participatory design can be time consuming and too divergent due to the involvement of non...... for collaborative urban design processes. Rather than making one-off designs which need to be redesigned from the ground up in case of changes, parametric design tools make it possible keep the design open while at the same time allowing for a level of detailing which is high enough to facilitate an understanding...... of parametric design tools, stakeholder participation can be conducted with more detail and in less time consuming ways. The workshop which forms the point of departure for this paper was held at Istanbul Technical University on December 14-17, 2012. In the course of the four-day workshop, senior computational...
Stochastic Non-Parametric Frontier Analysis
Directory of Open Access Journals (Sweden)
Mohammad Rahmani
2014-05-01
Full Text Available In this paper we develop an approach that synthesizes the best features of the two main methods in the estimation of production eciency. Specically, our approach rst allows for statistical noise, similar to Stochastic frontier analysis , and second, it allows modeling multiple-inputs-multiple-outputs technologies without imposing parametric assumptions on production relationship, similar to what is done in non-parametric methods. The methodology is based on the theory of local maximum likelihood estimation and extends recent works of Kumbhakar et al. We will use local-spherical coordinate system to transform multi-input multi-output data to more exible system which we can use in our approach. We also illustrate the performance of our approach with simulated example
Debi, Ronen; Mor, Amit; Elbaz, Avi; Segal, Ganit; Lubovsky, Omri; Kahn, Gadi; Peskin, Bezalel; Beer, Yiftah; Atoun, Ehud
2017-05-01
Spontaneous osteonecrosis of the knee is usually verified by magnetic resonance imaging accompanied by clinical questionnaires to assess the level of pain and functional limitation. There is a lack however, in an objective functional test that will reflect the functional severity of spontaneous osteonecrosis of the knee. The purpose of the current study was to examine the correlation between spatiotemporal gait parameters and clinical questionnaires in patients with spontaneous osteonecrosis of the knee. 28 patients (16 females and 12 males) were included in the analysis. Patients had unilateral spontaneous osteonecrosis of the knee of the medial femoral condyle confirmed by magnetic resonance imaging. All patients performed a computerized spatiotemporal gait analysis and completed the Western Ontario and McMaster University Osteoarthritis Index and the Short-Form 36. Relationships between selected spatiotemporal gait measures and self-assessment questionnaires were assessed by Spearman non-parametric correlations. Significant correlations were found between selected spatiotemporal gait parameters and clinical questionnaires (r ranged between 0.28 and 0.79). Single limb support was the gait measure with the strongest correlation to pain (r=0.58), function (r=0.56) and quality of life. Spatiotemporal gait assessment for patients with spontaneous osteonecrosis of the knee correlates with the patient's level of pain and functional limitation there by adding objective information regarding the functional condition of these patients. Copyright © 2017 Elsevier Ltd. All rights reserved.
Gain changes in sensorimotor pathways of the locust leg
BÜSchges; Wolf
1996-01-01
Feedback systems that control the leg joints of animals must be highly flexible in adapting to different behavioural tasks. One manifestation of such flexibility is changes in the gain of joint control networks. The femurtibia (FT) control network of the locust leg is one of the feedback systems most thoroughly studied with regard to its neural circuitry. Despite excellent information concerning network topology, however, actual gain changes and their underlying mechanisms have not yet been examined because of the marked spontaneous variations in the action of the control network for this joint. We describe a behavioural situation and a preparation in which the locust (Locusta migratoria L.) FT control network exhibits reproducible changes in gain, allowing investigation of the neuronal basis of gain control. After ('fictive') flight motor activity, the gain of resistance reflexes in the FT joint of the locust middle leg is significantly decreased, with the flexor tibiae muscles being affected more strongly than the extensor muscles. Immediately after flight motor activity, the gain may be as low as 30 % of pre-flight levels. It returns to pre-flight values in under 150 s. The decrease in gain following flight motor activity is due to a decrease in motoneurone recruitment in the resistance reflex elicited by stimulation of the appropriate mechanoreceptor, the femoral chordotonal organ. Motoneurone recruitment is changed as a result of a drastic decline in the stimulus-related synaptic input to the motoneurones, which appears to be produced exclusively at the level of the pre-motor network. Two factors led to this conclusion: first, we found no indication of changes in membrane potential or membrane conductance of the tibia flexor and extensor motoneurones; second, recording from identified pre-motor nonspiking interneurones demonstrated that these may be involved in the observed gain changes. The putative behavioural relevance is discussed.
Nonscaling parametrization of hadronic spectra and dual parton model
International Nuclear Information System (INIS)
Gaponenko, O.N.
2001-01-01
Using the popular Wdowczyk-Wolfendale parametrization (WW-parametrization) as an example one studies restrictions imposed by a dual parton model for different nonscaling parametrizations of the pulsed hadron spectra in soft hadron-hadron and hadron-nuclear interactions. One derived a new parametrization free from basic drawback of the WW-formulae. In the central range the determined parametrization show agreement with the Wdowczyk-Wolfendale formula, but in contrast to the last-named one it does not result in contradiction with the experiment due to fast reduction of inelastic factor reduction with energy increase [ru
Parametric study of laser photovoltaic energy converters
Walker, G. H.; Heinbockel, J. H.
1987-01-01
Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.
Multidimensional Scaling Visualization Using Parametric Similarity Indices
Machado, J. Tenreiro; Lopes, António; Galhano, Alexandra
2015-01-01
In this paper, we apply multidimensional scaling (MDS) and parametric similarity indices (PSI) in the analysis of complex systems (CS). Each CS is viewed as a dynamical system, exhibiting an output time-series to be interpreted as a manifestation of its behavior. We start by adopting a sliding window to sample the original data into several consecutive time periods. Second, we define a given PSI for tracking pieces of data. We then compare the windows for different values of the parameter, an...
Parametric Integration by Magic Point Empirical Interpolation
Gaß, Maximilian; Glau, Kathrin
2015-01-01
We derive analyticity criteria for explicit error bounds and an exponential rate of convergence of the magic point empirical interpolation method introduced by Barrault et al. (2004). Furthermore, we investigate its application to parametric integration. We find that the method is well-suited to Fourier transforms and has a wide range of applications in such diverse fields as probability and statistics, signal and image processing, physics, chemistry and mathematical finance. To illustrate th...
Parametric Integration by Magic Point Empirical Interpolation
Gaß, M., Glau, K.
2016-01-01
We derive analyticity criteria for explicit error bounds and an exponential rate of convergence of the magic point empirical interpolation method introduced by Barrault et al. (2004). Furthermore, we investigate its application to parametric integration. We find that the method is well-suited to Fourier transforms and has a wide range of applications in such diverse fields as probability and statistics, signal and image processing, physics, chemistry and mathematical finance. To illustrate th...
Bidirectional, synchronously pumped, ring optical parametric oscillator.
Meng, X; Diels, J C; Kuehlke, D; Batchko, R; Byer, R
2001-03-01
We report the operation of a bidirectional femtosecond pulsed ring optical parametric oscillator based on periodically poled lithium niobate, pumped alternately with nonsimultaneous pulses from a Ti:sapphire mode-locked laser. A beat note between the two counterpropagating beams attests to a gyro response without dead band. The sensitivity of the device to differential phase changes is demonstrated by measurement of the nonlinear index of lithium niobate.
On Algebraic Approach for MSD Parametric Estimation
Oueslati , Marouene; Thiery , Stéphane; Gibaru , Olivier; Béarée , Richard; Moraru , George
2011-01-01
This article address the identification problem of the natural frequency and the damping ratio of a second order continuous system where the input is a sinusoidal signal. An algebra based approach for identifying parameters of a Mass Spring Damper (MSD) system is proposed and compared to the Kalman-Bucy filter. The proposed estimator uses the algebraic parametric method in the frequency domain yielding exact formula, when placed in the time domain to identify the unknown parameters. We focus ...
Collaborative design of parametric sustainable architecture
Hubers, H.
2011-01-01
Sustainable architecture is complex. Many aspects, differently important to many stakeholders, are to be optimized. BIM should be used for this. Building Information Modellingis a collaborative process where all stakeholders integrate and optimize their information in a digital 3D model. Sometimes it is called Green BIM. But what exactly is that? Is the International Standard Organization IFC standard useful for this? And is it compatible with new developments in parametric design? Advantages...
Hydrogeologic Characteristic of Arakaevskaya Parametric Well
Directory of Open Access Journals (Sweden)
G. L. Belyaeva
2015-06-01
Full Text Available In the paper, the boundaries and depth of water-bearing units in the Arakaevskaya parametric well are established. The methods of aquifers hydrochemical composition study and its results are described. Due to occurrence of overthrust structures at the observed area, the allochthon and autochthon water-bearing units are defined. Analysis of hydrodynamic regime showed that the interaction between Urals aquifers and those at the area of study is not observed.
Energy Technology Data Exchange (ETDEWEB)
Sen, Tanaji [Fermilab
2016-06-01
We discuss the generation of parametric X-rays (PXR) in the photoinjector at the new FAST facility at Fermilab. Detailed calculations of the intensity spectrum, energy and angular widths and spectral brilliance with a diamond crystal are presented. We also report on expected results with PXR generated while the beam is channeling. The low emittance electron beam makes this facility a promising source for creating brilliant X-rays.
Developmental gains in visuospatial memory predict gains in mathematics achievement.
Directory of Open Access Journals (Sweden)
Yaoran Li
Full Text Available Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4 were larger than gains in the capacity of the central executive (d = 1.6 that in turn were larger than gains in phonological memory span (d = 1.1. First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning.
Developmental gains in visuospatial memory predict gains in mathematics achievement.
Li, Yaoran; Geary, David C
2013-01-01
Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4) were larger than gains in the capacity of the central executive (d = 1.6) that in turn were larger than gains in phonological memory span (d = 1.1). First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning.
Developmental Gains in Visuospatial Memory Predict Gains in Mathematics Achievement
Li, Yaoran; Geary, David C.
2013-01-01
Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d = 2.4) were larger than gains in the capacity of the central executive (d = 1.6) that in turn were larger than gains in phonological memory span (d = 1.1). First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning. PMID:23936154
Parametric Cost Models for Space Telescopes
Stahl, H. Philip; Henrichs, Todd; Dollinger, Courtney
2010-01-01
Multivariable parametric cost models for space telescopes provide several benefits to designers and space system project managers. They identify major architectural cost drivers and allow high-level design trades. They enable cost-benefit analysis for technology development investment. And, they provide a basis for estimating total project cost. A survey of historical models found that there is no definitive space telescope cost model. In fact, published models vary greatly [1]. Thus, there is a need for parametric space telescopes cost models. An effort is underway to develop single variable [2] and multi-variable [3] parametric space telescope cost models based on the latest available data and applying rigorous analytical techniques. Specific cost estimating relationships (CERs) have been developed which show that aperture diameter is the primary cost driver for large space telescopes; technology development as a function of time reduces cost at the rate of 50% per 17 years; it costs less per square meter of collecting aperture to build a large telescope than a small telescope; and increasing mass reduces cost.
Impulsive parametric damping in energy harvesting
International Nuclear Information System (INIS)
Tehrani, Maryam Ghandchi; Pumhoessel, Thomas
2016-01-01
In this paper, an electro-mechanical system with a time-varying damper, which is capable of changing the damping coefficient impulsively, is considered. The effect of the impulsive parametric damping to the modal energy content of the mechanical system is investigated analytically as well as numerically. First, the governing differential equation is presented and then the solution of the system's response is obtained through numerical integration. The energy dissipated by the damper is then calculated to investigate the amount of the energy that can be harvested, and the results are compared with the results from a system without parametric impulses. It is shown, that the amount of the harvested energy can be increased by introducing parametric impulses. Then, an analytical formulation is derived for the system using Dirac-Delta impulses and the analytical results are validated with numerical simulations. The device is subjected to an initial condition and therefore is vibrating freely without any base excitation. This could be used for applications such as harvesting energy from the passage of a train, where the train vibration can introduce an initial velocity to the harvester and the energy can then be extracted from the free vibration of the harvester. (paper)
Parametric Architecture in the Urban Space
Januszkiewicz, Krystyna; Kowalski, Karol G.
2017-10-01
The paper deals with the parametric architecture which is trying to introduce a new spatial language in the context for urban tissue that correspond to the artistic consciousness and the attitude of information and digital technologies era. The first part of the paper defines the main features of parametric architecture (such as: folding, continuity and curvilinearity) which are are characteristic of the new style of named the “parametricism”. This architecture is a strong emphasis on geometry, materiality, feasibility and sustainability, what emerges is an explicit agenda promoting material ornamentation, spatial spectacle and formal theatricality. The second part presents result of case study, especially parametric public use buildings, within the tissue of city. The analyzed objects are: The Sage Gateshead (1998-2004) in Gateshead, Kunsthaus in Graz (2000-2003), the Weltstadthaus (2003-2005) in Cologne, The Golden Terraces in Warsaw (2000-2007), the Metropol Parasol in Seville (2005-2011) the King Cross Station (2005-2012) in London, the headquarters of the Pathé Foundation (2006-2014) in Paris. Each of the enumerated examples shows a diverse approach to designing in the urban space, which reflect the age of digital technologies and the information society. In conclusion emphasizes, that new concept of the spatialization of architecture is the equivalent of the democratization of the political system, the liberalization of the economy, among other examples.
Parametric cost models for space telescopes
Stahl, H. Philip; Henrichs, Todd; Dollinger, Courtnay
2017-11-01
Multivariable parametric cost models for space telescopes provide several benefits to designers and space system project managers. They identify major architectural cost drivers and allow high-level design trades. They enable cost-benefit analysis for technology development investment. And, they provide a basis for estimating total project cost. A survey of historical models found that there is no definitive space telescope cost model. In fact, published models vary greatly [1]. Thus, there is a need for parametric space telescopes cost models. An effort is underway to develop single variable [2] and multi-variable [3] parametric space telescope cost models based on the latest available data and applying rigorous analytical techniques. Specific cost estimating relationships (CERs) have been developed which show that aperture diameter is the primary cost driver for large space telescopes; technology development as a function of time reduces cost at the rate of 50% per 17 years; it costs less per square meter of collecting aperture to build a large telescope than a small telescope; and increasing mass reduces cost.
2.5 TW, two-cycle IR laser pulses via frequency domain optical parametric amplification.
Gruson, V; Ernotte, G; Lassonde, P; Laramée, A; Bionta, M R; Chaker, M; Di Mauro, L; Corkum, P B; Ibrahim, H; Schmidt, B E; Legaré, F
2017-10-30
Broadband optical parametric amplification in the IR region has reached a new milestone through the use of a non-collinear Frequency domain Optical Parametric Amplification system. We report a laser source delivering 11.6 fs pulses with 30 mJ of energy at a central wavelength of 1.8 μm at 10 Hz repetition rate corresponding to a peak power of 2.5 TW. The peak power scaling is accompanied by a pulse shortening of about 20% upon amplification due to the spectral reshaping with higher gain in the spectral wings. This source paves the way for high flux soft X-ray pulses and IR-driven laser wakefield acceleration.
Parametric resonance of intrinsic localized modes in coupled cantilever arrays
Energy Technology Data Exchange (ETDEWEB)
Kimura, Masayuki, E-mail: kimura.masayuki.8c@kyoto-u.ac.jp [Department of Electrical Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan); Matsushita, Yasuo [Advanced Mathematical Institute, Osaka City University, 3-3-138 Sughimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); Hikihara, Takashi [Department of Electrical Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan)
2016-08-19
In this study, the parametric resonances of pinned intrinsic localized modes (ILMs) were investigated by computing the unstable regions in parameter space consisting of parametric excitation amplitude and frequency. In the unstable regions, the pinned ILMs were observed to lose stability and begin to fluctuate. A nonlinear Klein–Gordon, Fermi–Pasta–Ulam-like, and mixed lattices were investigated. The pinned ILMs, particularly in the mixed lattice, were destabilized by parametric resonances, which were determined by comparing the shapes of the unstable regions with those in the Mathieu differential equation. In addition, traveling ILMs could be generated by parametric excitation. - Highlights: • Destabilization of intrinsic localized modes (ILMs) by parametric excitation is investigated for FPU, NKG, and mixed lattices. • Frequency and amplitude of parametric excitation is determined based on characteristic multipliers of ILMs. • Unstable regions for the mixed lattice case show very similar shape to those of the Mathieu equation. • ILMs become unstable by causing parametric resonance.
Gain-clamping techniques in two-stage double-pass L-band EDFA
Indian Academy of Sciences (India)
Two designs of long-wavelength band erbium-doped fiber amplifier (L-band EDFA) for gain clamping in double-pass systems are demonstrated and compared. The first design is based on ring laser technique where a backward amplified spontaneous emission (ASE) from the second stage is routed into the feedback loop ...
High gain L-band erbium-doped fiber amplifier with two-stage ...
Indian Academy of Sciences (India)
stage erbium-doped ﬁber ampliﬁer; ampliﬁed spontaneous emission. Abstract. An experiment on gain enhancement in the long wavelength band erbium-doped ﬁber ampliﬁer (L-band EDFA) is demonstrated using dual forward pumping scheme ...
Obesity, gestational weight gain and preterm birth: a study within the Danish National Birth Cohort
DEFF Research Database (Denmark)
Nøhr, Ellen Aagaard; Bech, Bodil Hammer; Vaeth, Michael
2007-01-01
prepregnancy body mass index (BMI) and gestational weight gain was available. Information about spontaneous preterm birth with or without preterm premature rupture of membranes (PPROM) and about induced preterm deliveries was obtained from national registers. Cox regression analyses were used to examine...
Soft x-ray laser gain measurements in a recombining plasma column
International Nuclear Information System (INIS)
Suckewer, S.; Skinner, C.H.; Milchberg, H.; Keane, C.; Voorhees, D.
1985-03-01
An enhancement of approx. 100 of stimulated emission over spontaneous emission of the CVI 182 A line (one-pass gain approx. = 6.5) was measured in a recombining, magnetically confined plasma column by two independent techniques using intensity calibrated XUV monochromators. Additional confirmation that the enhancement was due to stimulated emission has been obtained with a soft x-ray mirror
Systematics of spontaneous positron lines
International Nuclear Information System (INIS)
Mueller, U.; Reus, T. de; Reinhardt, J.; Mueller, B.; Greiner, W.
1985-08-01
Dynamical and spontaneous positron emission are investigated for heavy-ion collisions with long time delay using a semiclassical description. Numerical results and analytical expressions for the characteristic quantities of the resulting spontaneous positron line, i.e., its position, width, and cross section, are compared. The expected behaviour of the line position and cross section and its visibility against the spectrum of dynamically created positrons is discussed in dependence of the united charge Zsub(u) of projectile and target nucleus in a range of systems from Zsub(u)=180 up to Zsub(u)=188. The results are confronted with presently available experimental data, and possible implications on further experiments are worked out. (orig.)
Spontaneous Rotational Inversion in Phycomyces
Goriely, Alain
2011-03-01
The filamentary fungus Phycomyces blakesleeanus undergoes a series of remarkable transitions during aerial growth. During what is known as the stagea IV growth phase, the fungus extends while rotating in a counterclockwise manner when viewed from above (stagea IVa) and then, while continuing to grow, spontaneously reverses to a clockwise rotation (stagea IVb). This phase lasts for 24-48Ah and is sometimes followed by yet another reversal (stageAIVc) before the overall growth ends. Here, we propose a continuum mechanical model of this entire process using nonlinear, anisotropic, elasticity and show how helical anisotropy associated with the cell wall structure can induce spontaneous rotation and, under appropriate circumstances, the observed reversal of rotational handedness. © 2011 American Physical Society.
Spontaneous regression of colon cancer.
Kihara, Kyoichi; Fujita, Shin; Ohshiro, Taihei; Yamamoto, Seiichiro; Sekine, Shigeki
2015-01-01
A case of spontaneous regression of transverse colon cancer is reported. A 64-year-old man was diagnosed as having cancer of the transverse colon at a local hospital. Initial and second colonoscopy examinations revealed a typical cancer of the transverse colon, which was diagnosed as moderately differentiated adenocarcinoma. The patient underwent right hemicolectomy 6 weeks after the initial colonoscopy. The resected specimen showed only a scar at the tumor site, and no cancerous tissue was proven histologically. The patient is alive with no evidence of recurrence 1 year after surgery. Although an antitumor immune response is the most likely explanation, the exact nature of the phenomenon was unclear. We describe this rare case and review the literature pertaining to spontaneous regression of colorectal cancer. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
A probabilistic strategy for parametric catastrophe insurance
Figueiredo, Rui; Martina, Mario; Stephenson, David; Youngman, Benjamin
2017-04-01
Economic losses due to natural hazards have shown an upward trend since 1980, which is expected to continue. Recent years have seen a growing worldwide commitment towards the reduction of disaster losses. This requires effective management of disaster risk at all levels, a part of which involves reducing financial vulnerability to disasters ex-ante, ensuring that necessary resources will be available following such events. One way to achieve this is through risk transfer instruments. These can be based on different types of triggers, which determine the conditions under which payouts are made after an event. This study focuses on parametric triggers, where payouts are determined by the occurrence of an event exceeding specified physical parameters at a given location, or at multiple locations, or over a region. This type of product offers a number of important advantages, and its adoption is increasing. The main drawback of parametric triggers is their susceptibility to basis risk, which arises when there is a mismatch between triggered payouts and the occurrence of loss events. This is unavoidable in said programmes, as their calibration is based on models containing a number of different sources of uncertainty. Thus, a deterministic definition of the loss event triggering parameters appears flawed. However, often for simplicity, this is the way in which most parametric models tend to be developed. This study therefore presents an innovative probabilistic strategy for parametric catastrophe insurance. It is advantageous as it recognizes uncertainties and minimizes basis risk while maintaining a simple and transparent procedure. A logistic regression model is constructed here to represent the occurrence of loss events based on certain loss index variables, obtained through the transformation of input environmental variables. Flood-related losses due to rainfall are studied. The resulting model is able, for any given day, to issue probabilities of occurrence of loss
Spontaneous baryogenesis in warm inflation
Brandenberger, Robert H.; Yamaguchi, Masahide
2003-01-01
We discuss spontaneous baryogenesis in the warm inflation scenario. In contrast with standard inflation models, radiation always exists in the warm inflation scenario, and the inflaton must be directly coupled to it. Also, the transition to the post-inflationary radiation dominated phase is smooth and the entropy is not significantly increased at the end of the period of inflation. In addition, after the period of warm inflation ends, the inflaton does not oscillate coherently but slowly roll...
Spontaneous Splenic Rupture in Melanoma
Directory of Open Access Journals (Sweden)
Hadi Mirfazaelian
2014-01-01
Full Text Available Spontaneous rupture of spleen due to malignant melanoma is a rare situation, with only a few case reports in the literature. This study reports a previously healthy, 30-year-old man who came with chief complaint of acute abdominal pain to emergency room. On physical examination, abdominal tenderness and guarding were detected to be coincident with hypotension. Ultrasonography revealed mild splenomegaly with moderate free fluid in abdominopelvic cavity. Considering acute abdominal pain and hemodynamic instability, he underwent splenectomy with splenic rupture as the source of bleeding. Histologic examination showed diffuse infiltration by tumor. Immunohistochemical study (positive for S100, HMB45, and vimentin and negative for CK, CD10, CK20, CK7, CD30, LCA, EMA, and chromogranin confirmed metastatic malignant melanoma. On further questioning, there was a past history of a nasal dark skin lesion which was removed two years ago with no pathologic examination. Spontaneous (nontraumatic rupture of spleen is an uncommon situation and it happens very rarely due to neoplastic metastasis. Metastasis of malignant melanoma is one of the rare causes of the spontaneous rupture of spleen.
Directory of Open Access Journals (Sweden)
Gaganpreet Kaur
2016-01-01
Full Text Available We demonstrate improved performance of parametric amplifier cascaded with Raman amplifier for gain of 54.79 dB. We report amplification of L-band using 100 × 10 Gbps Dense Wavelength Division Multiplexed (DWDM system with 25 GHz channel spacing. The gain achieved is the highest reported so far with gain flatness of 3.38 dB without using any gain flattening technique. Hybrid modulated parametric pump is used for suppressing four-wave mixing (FWM around pump region, resulting in improvement of gain flatness by 2.42 dB. The peak to peak variation of gain is achieved less than 1.6 dB. DWDM system with 16-channel, 25 GHz spaced system has been analyzed thoroughly with hybrid modulated parametric pump amplified Raman-FOPA amplifier for gain flatness and improved performance in terms of BER and Q-factor.
Martinez Manzanera, Octavio; Elting, Jan Willem; van der Hoeven, Johannes H; Maurits, Natasha M
2016-01-01
In the clinic, tremor is diagnosed during a time-limited process in which patients are observed and the characteristics of tremor are visually assessed. For some tremor disorders, a more detailed analysis of these characteristics is needed. Accelerometry and electromyography can be used to obtain a better insight into tremor. Typically, routine clinical assessment of accelerometry and electromyography data involves visual inspection by clinicians and occasionally computational analysis to obtain objective characteristics of tremor. However, for some tremor disorders these characteristics may be different during daily activity. This variability in presentation between the clinic and daily life makes a differential diagnosis more difficult. A long-term recording of tremor by accelerometry and/or electromyography in the home environment could help to give a better insight into the tremor disorder. However, an evaluation of such recordings using routine clinical standards would take too much time. We evaluated a range of techniques that automatically detect tremor segments in accelerometer data, as accelerometer data is more easily obtained in the home environment than electromyography data. Time can be saved if clinicians only have to evaluate the tremor characteristics of segments that have been automatically detected in longer daily activity recordings. We tested four non-parametric methods and five parametric methods on clinical accelerometer data from 14 patients with different tremor disorders. The consensus between two clinicians regarding the presence or absence of tremor on 3943 segments of accelerometer data was employed as reference. The nine methods were tested against this reference to identify their optimal parameters. Non-parametric methods generally performed better than parametric methods on our dataset when optimal parameters were used. However, one parametric method, employing the high frequency content of the tremor bandwidth under consideration
Jacobs, Rianne; Bekker, Andriëtte A; van der Voet, Hilko; Ter Braak, Cajo J F
2015-01-01
Estimating the risk, P(X > Y), in probabilistic environmental risk assessment of nanoparticles is a problem when confronted by potentially small risks and small sample sizes of the exposure concentration X and/or the effect concentration Y. This is illustrated in the motivating case study of aquatic risk assessment of nano-Ag. A non-parametric estimator based on data alone is not sufficient as it is limited by sample size. In this paper, we investigate the maximum gain possible when making strong parametric assumptions as opposed to making no parametric assumptions at all. We compare maximum likelihood and Bayesian estimators with the non-parametric estimator and study the influence of sample size and risk on the (interval) estimators via simulation. We found that the parametric estimators enable us to estimate and bound the risk for smaller sample sizes and small risks. Also, the Bayesian estimator outperforms the maximum likelihood estimators in terms of coverage and interval lengths and is, therefore, preferred in our motivating case study.
Bekker, Andriëtte A.; van der Voet, Hilko; ter Braak, Cajo J.F.
2015-01-01
Estimating the risk, P(X > Y), in probabilistic environmental risk assessment of nanoparticles is a problem when confronted by potentially small risks and small sample sizes of the exposure concentration X and/or the effect concentration Y. This is illustrated in the motivating case study of aquatic risk assessment of nano-Ag. A non-parametric estimator based on data alone is not sufficient as it is limited by sample size. In this paper, we investigate the maximum gain possible when making strong parametric assumptions as opposed to making no parametric assumptions at all. We compare maximum likelihood and Bayesian estimators with the non-parametric estimator and study the influence of sample size and risk on the (interval) estimators via simulation. We found that the parametric estimators enable us to estimate and bound the risk for smaller sample sizes and small risks. Also, the Bayesian estimator outperforms the maximum likelihood estimators in terms of coverage and interval lengths and is, therefore, preferred in our motivating case study. PMID:26312175
Directory of Open Access Journals (Sweden)
Rianne Jacobs
2015-08-01
Full Text Available Estimating the risk, P(X > Y, in probabilistic environmental risk assessment of nanoparticles is a problem when confronted by potentially small risks and small sample sizes of the exposure concentration X and/or the effect concentration Y. This is illustrated in the motivating case study of aquatic risk assessment of nano-Ag. A non-parametric estimator based on data alone is not sufficient as it is limited by sample size. In this paper, we investigate the maximum gain possible when making strong parametric assumptions as opposed to making no parametric assumptions at all. We compare maximum likelihood and Bayesian estimators with the non-parametric estimator and study the influence of sample size and risk on the (interval estimators via simulation. We found that the parametric estimators enable us to estimate and bound the risk for smaller sample sizes and small risks. Also, the Bayesian estimator outperforms the maximum likelihood estimators in terms of coverage and interval lengths and is, therefore, preferred in our motivating case study.
Slow-light enhancement of spontaneous emission in active photonic crystal waveguides
DEFF Research Database (Denmark)
Ek, Sara; Chen, Yaohui; Semenova, Elizaveta
2012-01-01
Photonic crystal defect waveguides with embedded active layers containing single or multiple quantum wells or quantum dots have been fabricated. Spontaneous emission spectra are enhanced close to the bandedge, consistently with the enhancement of gain by slow light effects. These are promising...
A Comparison of Parametric and Non-Parametric Methods Applied to a Likert Scale
Mircioiu, Constantin; Atkinson, Jeffrey
2017-01-01
A trenchant and passionate dispute over the use of parametric versus non-parametric methods for the analysis of Likert scale ordinal data has raged for the past eight decades. The answer is not a simple “yes” or “no” but is related to hypotheses, objectives, risks, and paradigms. In this paper, we took a pragmatic approach. We applied both types of methods to the analysis of actual Likert data on responses from different professional subgroups of European pharmacists regarding competencies fo...
Spectral gain investigation of large size OPCPA based on partially deuterated KDP
Galimberti, Marco; Boyle, Alexis; Musgrave, Ian O.; Oliveira, Pedro; Pepler, Dave; Shaikh, Waseem; Winstone, Trevor B.; Wyatt, Adam; Hernandez-Gomez, Cristina
2018-01-01
The Optical Parametric Chirped Pulse Amplification is one of the most promising techniques to deliver 20PW laser system. The already available KD*P in large size is a good candidate as nonlinear crystal. In this article we report the experimental analysis of the spectral small signal gain for KD*P at 70% deuteration level for different phase matching and non-collinear angle. The data is also compared with a theoretical model.
H∞ Loop Shaping Control of Input Saturated Systems with Norm-Bounded Parametric Uncertainty
Directory of Open Access Journals (Sweden)
Renan Lima Pereira
2015-01-01
Full Text Available This paper proposes a gain-scheduling control design strategy for a class of linear systems with the presence of both input saturation constraints and norm-bounded parametric uncertainty. LMI conditions are derived in order to obtain a gain-scheduled controller that ensures the robust stability and performance of the closed loop system. The main steps to obtain such a controller are given. Differently from other gain-scheduled approaches in the literature, this one focuses on the problem of H∞ loop shaping control design with input saturation nonlinearity and norm-bounded uncertainty to reduce the effect of the disturbance input on the controlled outputs. Here, the design problem has been formulated in the four-block H∞ synthesis framework, in which it is possible to describe the parametric uncertainty and the input saturation nonlinearity as perturbations to normalized coprime factors of the shaped plant. As a result, the shaped plant is represented as a linear parameter-varying (LPV system while the norm-bounded uncertainty and input saturation are incorporated. This procedure yields a linear parameter-varying structure for the controller that ensures the stability of the polytopic LPV shaped plant from the vertex property. Finally, the effectiveness of the method is illustrated through application to a physical system: a VTOL “vertical taking-off landing” helicopter.
Heritability of gestational weight gain
DEFF Research Database (Denmark)
Andersson, Elina Scheers; Silventoinen, Karri; Tynelius, Per
2015-01-01
Gestational weight gain (GWG) is a complex trait involving intrauterine environmental, maternal environmental, and genetic factors. However, the extent to which these factors contribute to the total variation in GWG is unclear. We therefore examined the genetic and environmental influences on the...
Yield gains in leafy vegetables
Yield of all crops have increased during the past century through improved cultural practices and plant breeding. We reviewed gains in yield of lettuce and spinach in the U.S., principally California and Arizona. We proposed several genetic models for yield of lettuce based on the market type: whole...
Simulation and parametric optimisation of thermal power plant cycles
Directory of Open Access Journals (Sweden)
P. Ravindra Kumar
2016-09-01
Full Text Available The objective of the paper is to analyse parametric studies and optimum steam extraction pressures of three different (subcritical, supercritical and ultra-supercritical coal fired power plant cycles at a particular main steam temperature of 600 °C by keeping the reheat temperature at 537 °C and condenser pressure at 0.09 bar as constant. In order to maximize the heat rate gain possible with supercritical and ultra-supercritical steam conditions, eight stages of feed water heater arrangement with single reheater is considered. The system is optimized in such a way that the percentage exergetic losses are reduced for the increase of the exergetic efficiency and higher fuel utilization. The plant cycles are simulated and optimized by using Cycle Tempo 5.0 simulation software tool. From the simulation study, it is observed that the thermal efficiency of the three different power plant cycles obtained as 41.40, 42.48 and 43.03%, respectively. The specific coal consumption for three different power plant cycles are 0.56, 0.55 and 0.54 Tonnes/MWh. The improvement in feed water temperatures at the inlet of steam generator of respective cycles are 291, 305 and 316 °C.
Parametric overdispersed frailty models for current status data.
Abrams, Steven; Aerts, Marc; Molenberghs, Geert; Hens, Niel
2017-12-01
Frailty models have a prominent place in survival analysis to model univariate and multivariate time-to-event data, often complicated by the presence of different types of censoring. In recent years, frailty modeling gained popularity in infectious disease epidemiology to quantify unobserved heterogeneity using Type I interval-censored serological data or current status data. In a multivariate setting, frailty models prove useful to assess the association between infection times related to multiple distinct infections acquired by the same individual. In addition to dependence among individual infection times, overdispersion can arise when the observed variability in the data exceeds the one implied by the model. In this article, we discuss parametric overdispersed frailty models for time-to-event data under Type I interval-censoring, building upon the work by Molenberghs et al. (2010) and Hens et al. (2009). The proposed methodology is illustrated using bivariate serological data on hepatitis A and B from Flanders, Belgium anno 1993-1994. Furthermore, the relationship between individual heterogeneity and overdispersion at a stratum-specific level is studied through simulations. Although it is important to account for overdispersion, one should be cautious when modeling both individual heterogeneity and overdispersion based on current status data as model selection is hampered by the loss of information due to censoring. © 2017, The International Biometric Society.
Ultrashort pulse shaping by optical parametric chirped amplification
International Nuclear Information System (INIS)
Nelet, Ambre
2007-01-01
The aim of this work is to propose new laser architectures based on optical parametric chirped pulse amplification (OPCPA). Common goals of OPCPA pre-amplifiers are to reach high energy level while maintaining the spectrum width and to adapt geometry of the amplified beam to the high power laser chain optics. We consider OPCPA as a way to control and to sculpt ultrashort pulses. Our first set-up aims at thwarting possible time recovery default between pump and signal pulses, which lower the energy extraction. A regenerative OPCPA, idler resonant, is a way to produce a high-intensity and high-repetition rate train of amplified signal replicas. Our second laser system pre-compensates the spectral gain narrowing by sculpting pulses directly within the OPCPA section, where a temporal shaping of the pump beam permits a spectro-spectral shaping of the amplified signal. Finally, we propose an OPCPA based on spatial coding and uniform amplification of spectral signal components by using a fan-out periodically poled crystal and a zero dispersion line. (author) [fr
Parametric Portfolio Policies with Common Volatility Dynamics
DEFF Research Database (Denmark)
Ergemen, Yunus Emre; Taamouti, Abderrahim
A parametric portfolio policy function is considered that incorporates common stock volatility dynamics to optimally determine portfolio weights. Reducing dimension of the traditional portfolio selection problem significantly, only a number of policy parameters corresponding to first- and second......-order characteristics are estimated based on a standard method-of-moments technique. The method, allowing for the calculation of portfolio weight and return statistics, is illustrated with an empirical application to 30 U.S. industries to study the economic activity before and after the recent financial crisis....
White-light parametric instabilities in plasmas.
Santos, J E; Silva, L O; Bingham, R
2007-06-08
Parametric instabilities driven by partially coherent radiation in plasmas are described by a generalized statistical Wigner-Moyal set of equations, formally equivalent to the full wave equation, coupled to the plasma fluid equations. A generalized dispersion relation for stimulated Raman scattering driven by a partially coherent pump field is derived, revealing a growth rate dependence, with the coherence width sigma of the radiation field, scaling with 1/sigma for backscattering (three-wave process), and with 1/sigma1/2 for direct forward scattering (four-wave process). Our results demonstrate the possibility to control the growth rates of these instabilities by properly using broadband pump radiation fields.
Parametrization relating the fermionic mass spectra
International Nuclear Information System (INIS)
Kleppe, A.
1993-01-01
When parametrizing the fermionic mass spectra in terms of the unit matrix and a recursive matrix scrR 0 , which corresponds to an underlying scaling pattern in the mass spectra, each fermionic sector is characterized by three parameters: k, α, and R. Using the set of relations displayed by the parameters of the different sectors, it is possible to formulate a ''family Lagrangian'' which for each sector encompasses all the families. Relations between quark masses are furthermore deduced from these ''family Lagrangians.'' Using the relations between the parameters of the different charge sectors, it is also possible to ''derive'' the quark mass spectra from the (charged) leptonic mass spectrum
Bayesian inference and the parametric bootstrap
Efron, Bradley
2013-01-01
The parametric bootstrap can be used for the efficient computation of Bayes posterior distributions. Importance sampling formulas take on an easy form relating to the deviance in exponential families, and are particularly simple starting from Jeffreys invariant prior. Because of the i.i.d. nature of bootstrap sampling, familiar formulas describe the computational accuracy of the Bayes estimates. Besides computational methods, the theory provides a connection between Bayesian and frequentist analysis. Efficient algorithms for the frequentist accuracy of Bayesian inferences are developed and demonstrated in a model selection example. PMID:23843930
A simple parametric model selection test
Susanne M. Schennach; Daniel Wilhelm
2014-01-01
We propose a simple model selection test for choosing among two parametric likelihoods which can be applied in the most general setting without any assumptions on the relation between the candidate models and the true distribution. That is, both, one or neither is allowed to be correctly speci fied or misspeci fied, they may be nested, non-nested, strictly non-nested or overlapping. Unlike in previous testing approaches, no pre-testing is needed, since in each case, the same test statistic to...
Parametric systems analysis for tandem mirror hybrids
International Nuclear Information System (INIS)
Lee, J.D.; Chapin, D.L.; Chi, J.W.H.
1980-09-01
Fusion fission systems, consisting of fissile producing fusion hybrids combining a tandem mirror fusion driver with various blanket types and net fissile consuming LWR's, have been modeled and analyzed parametrically. Analysis to date indicates that hybrids can be competitive with mined uranium when U 3 O 8 cost is about 100 $/lb., adding less than 25% to present day cost of power from LWR's. Of the three blanket types considered, uranium fast fission (UFF), thorium fast fission (ThFF), and thorium fission supressed (ThFS), the ThFS blanket has a modest economic advantage under most conditions but has higher support ratios and potential safety advantages under all conditions
Semiclassical universality of parametric spectral correlations
International Nuclear Information System (INIS)
Kuipers, Jack; Sieber, Martin
2007-01-01
We consider quantum systems with a chaotic classical limit that depends on an external parameter, and study correlations between the spectra at different parameter values. In particular, we consider the parametric spectral form factor K(τ, x) which depends on a scaled parameter difference x. For parameter variations that do not change the symmetry of the system we show by using semiclassical periodic orbit expansions that the small τ expansion of the form factor agrees with random matrix theory for systems with and without time reversal symmetry
Non-Parametric Estimation of Correlation Functions
DEFF Research Database (Denmark)
Brincker, Rune; Rytter, Anders; Krenk, Steen
In this paper three methods of non-parametric correlation function estimation are reviewed and evaluated: the direct method, estimation by the Fast Fourier Transform and finally estimation by the Random Decrement technique. The basic ideas of the techniques are reviewed, sources of bias are point...... out, and methods to prevent bias are presented. The techniques are evaluated by comparing their speed and accuracy on the simple case of estimating auto-correlation functions for the response of a single degree-of-freedom system loaded with white noise....
Noiseless attenuation using an optical parametric amplifier
Brewster, R. A.; Nodurft, I. C.; Pittman, T. B.; Franson, J. D.
2017-10-01
The process of heralded noiseless amplification, and the inverse process of heralded noiseless attenuation, have potential applications in the context of quantum communications. Although several different physical implementations of heralded noiseless amplifiers have now been demonstrated, the research on heralded noiseless attenuators has been largely confined to a beam-splitter based approach. Here we show that an optical parametric amplifier (OPA), combined with appropriate heralding, can also serve as a heralded noiseless attenuator. The counterintuitive use of an optical amplifier as an attenuator is only possible due to the probabilistic nature of the device.
Parametric Architectural Design with Point-clouds
DEFF Research Database (Denmark)
Zwierzycki, Mateusz; Evers, Henrik Leander; Tamke, Martin
2016-01-01
This paper investigates the efforts and benefits of the implementation of point clouds into architectural design processes and tools. Based on a study on the principal work processes of designers with point clouds the prototypical plugin/library - Volvox - was developed for the parametric modelli...... environment Grasshopper in Rhino. The prototype allows us to discuss the necessary technical layer for the task, benchmark the tool, and finally to evaluate the benefits, that this approach has for architectural practice, through a series of use cases....
Fast Parametric Beamformer for Synthetic Aperture Imaging
DEFF Research Database (Denmark)
Nikolov, Svetoslav; Jensen, Jørgen Arendt; Tomov, Borislav Gueorguiev
2008-01-01
This paper describes the design and implementation of a real-time delay-and-sum synthetic aperture beamformer. The beamforming delays and apodization coefficients are described parametrically. The image is viewed as a set of independent lines that are defined in 3-D by their origin, direction....... The implementation of the beamformer is optimized with respect to the architecture of a novel synthetic aperture real-time ultrasound scanner (SARUS), in which 4 channels are processed by the same set of field-programmable gate arrays (FPGA). In synthetic transmit aperture imaging, low-resolution images are formed...
Semi-parametric estimation for ARCH models
Directory of Open Access Journals (Sweden)
Raed Alzghool
2018-03-01
Full Text Available In this paper, we conduct semi-parametric estimation for autoregressive conditional heteroscedasticity (ARCH model with Quasi likelihood (QL and Asymptotic Quasi-likelihood (AQL estimation methods. The QL approach relaxes the distributional assumptions of ARCH processes. The AQL technique is obtained from the QL method when the process conditional variance is unknown. We present an application of the methods to a daily exchange rate series. Keywords: ARCH model, Quasi likelihood (QL, Asymptotic Quasi-likelihood (AQL, Martingale difference, Kernel estimator
Spontaneous oscillations in microfluidic networks
Case, Daniel; Angilella, Jean-Regis; Motter, Adilson
2017-11-01
Precisely controlling flows within microfluidic systems is often difficult which typically results in systems being heavily reliant on numerous external pumps and computers. Here, I present a simple microfluidic network that exhibits flow rate switching, bistablity, and spontaneous oscillations controlled by a single pressure. That is, by solely changing the driving pressure, it is possible to switch between an oscillating and steady flow state. Such functionality does not rely on external hardware and may even serve as an on-chip memory or timing mechanism. I use an analytic model and rigorous fluid dynamics simulations to show these results.
General features of spontaneous baryogenesis
Arbuzova, Elena
2017-04-01
The classical version of spontaneous baryogenesis is studied in details. It is shown that the relation between the time derivative of the (pseudo)goldstone field and the baryonic chemical potential essentially depends upon the representation chosen for the fermionic fields with non-zero baryonic number (quarks). The kinetic equation, used for the calculations of the cosmological baryon asymmetry, is generalized to the case of non-stationary background. The effects of the finite interval of the integration over time are also included into consideration.
Spontaneous osteonecrosis of the knee
Energy Technology Data Exchange (ETDEWEB)
Kattapuram, Taj M. [Department of Radiology, Massachusetts General Hospital (United States); Kattapuram, Susan V. [Department of Radiology, Massachusetts General Hospital (United States)], E-mail: skattapuram@partners.org
2008-07-15
Spontaneous osteonecrosis of the knee presents with acute onset of severe, pain in elderly patients, usually female and usually without a history of trauma. Originally described as idiopathic osteonecrosis, the exact etiology is still debated. Evidence suggests that an acute fracture occurs as a result of chronic stress or minor trauma to a weakened subchondral bone plate. The imaging characteristics on MR reflect the age of the lesion and the symptoms. More appropriate terminology may be ' subchondral insufficiency fracture of the knee' or 'focal subchondral osteonecrosis'.
Parametric amplification on rf-induced steps in a Josephson tunnel junction
DEFF Research Database (Denmark)
Sørensen, O.H.; Pedersen, Niels Falsig; Mygind, Jesper
1979-01-01
Parametric effects including amplification in a singly degenerate mode have been observed in Josephson tunnel junctions at dc bias points on rf-induced steps. Net gain at 9 GHz was achieved with a bias on the fundamental 18-GHz step and subharmonic self-oscillations were seen on 18 and 70-GHz rf-......-induced steps even at voltages approaching the energy gap. A qualitative explanation of the results is presented. Journal of Applied Physics is copyrighted by The American Institute of Physics....
DEFF Research Database (Denmark)
Rishøj, Lars Søgaard; Svane, Ask Sebastian; Lund-Hansen, Toke
2014-01-01
A numerical model for parametric amplifiers, which include stochastic variations of the group velocity dispersion (GVD), is presented. The impact on the gain is investigated, both with respect to the magnitude of the variations and by the effect caused by changing the wavelength of the pump. It i....... It is demonstrated that the described model is able to predict the experimental results and thereby provide a quantitative evaluation of the standard deviation of the GVD. For the investigated fibre, a standard deviation of 0.01 ps/(nm km) was found....
Novel Optical Parametric Amplifier at 1572 nm Wavelength Using KTP Crystal
International Nuclear Information System (INIS)
Li Huan-Huan; Li Shi-Guang; Ma Xiu-Hua; Wang Jun-Tao; Zhu Xiao-Lei
2012-01-01
A novel master oscillator/power amplifier architecture for optical parametric conversion of high pulse energy from 1.064 μm to 1.572 μm in KTiOPO 4 crystal is presented. A high gain of more than 80 at 1.572 μm pumped by a high energy Q-switched pulse laser is realized. With a seeding signal energy of 1 mJ, and 400 mJ pump pulse at 100 Hz, an amplified signal pulse energy of over 80 mJ is obtained. The total optical-optical conversion efficiency reaches 21%
Combined non-parametric and parametric approach for identification of time-variant systems
Dziedziech, Kajetan; Czop, Piotr; Staszewski, Wieslaw J.; Uhl, Tadeusz
2018-03-01
Identification of systems, structures and machines with variable physical parameters is a challenging task especially when time-varying vibration modes are involved. The paper proposes a new combined, two-step - i.e. non-parametric and parametric - modelling approach in order to determine time-varying vibration modes based on input-output measurements. Single-degree-of-freedom (SDOF) vibration modes from multi-degree-of-freedom (MDOF) non-parametric system representation are extracted in the first step with the use of time-frequency wavelet-based filters. The second step involves time-varying parametric representation of extracted modes with the use of recursive linear autoregressive-moving-average with exogenous inputs (ARMAX) models. The combined approach is demonstrated using system identification analysis based on the experimental mass-varying MDOF frame-like structure subjected to random excitation. The results show that the proposed combined method correctly captures the dynamics of the analysed structure, using minimum a priori information on the model.
Chaotic noise in superconducting microbridge 4-photon X-band parametric amplifier
International Nuclear Information System (INIS)
Andresen, J.E.; Christiansen, B.; Levinsen, M.T.
1988-01-01
The anomalous noise rise observed in nearly all types of parametric amplifiers based on Josephson junctions has been an intriguing as well as annoying problem for many years. This phenomenon has been most spectacular in microbridge amplifiers. Here we present measurements on externally pumped single microbridge 4-photon unbiased amplifiers, where the slit with the bridge is used as a slotline resonantly coupled to the waveguide in an exceptionally simple coupling scheme. This scheme may be of interest in itself, particularly if the noise problem can be overcome, but also in other connections. Up to 16 dB gain was obtained at the top of the waveguide. However, the noise rise was observed as usual. An analog computer study on a model including an input/output circiut was performed. The results are in very good agreement with the experiments. The amplification is heralded by a seemingly chaotic noise rise. This noise is then amplified linearly when gain occurs. Amplification is found to take place very close to where the supercurrent is completely suppressed by the pump. This has previously been interpreted as loss of phaselock being the cause of the noise rise. However, the power spectra of the time-derivative of the phase show the still to be locked in the region of positive gain. Furthermore, computations of the Lyapunov exponents show one to be positive in the region where gain occurs reaching a maximum value at the parameters corresponding to maximum gain. We therefore conclude that chaotic noise is indeed present in Josephson junction parametric amplifiers where low-impedance devices like microbridges with negligible capacitance are used as the active elements. (orig.)
Amplification of DWDM channels at 1.28 Tb/s in a bidirectional fiber optical parametric amplifier.
Lei, Gordon K P; Marhic, Michel E
2014-04-07
We experimentally demonstrate amplification of 1.28 Tb/s DWDM channels using a bidirectional fiber optical parametric amplifier. The amplifier can provide more than 13 dB on-off gain on all 32 DWDM channels. Error-free operation has been achieved for all data streams, with an average power penalty of 2.5 dB compared with conventional unidirectional configuration.
Lin, Z. R.; Inomata, K.; Oliver, W. D.; Koshino, K.; Nakamura, Y.; Tsai, J. S.; Yamamoto, T.
2013-09-01
We report single-shot readout of a superconducting flux qubit by using a flux-driven Josephson parametric amplifier (JPA). After optimizing the readout power, gain of the JPA, and timing of the data acquisition, we observe the Rabi oscillations with a contrast of 74%, which is mainly limited by the bandwidth of the JPA and the energy relaxation of the qubit. The observation of quantum jumps between the qubit eigenstates under continuous monitoring indicates the nondestructiveness of the readout scheme.
GHz-rate optical parametric amplifier in hydrogenated amorphous silicon
International Nuclear Information System (INIS)
Wang, Ke-Yao; Foster, Amy C
2015-01-01
We demonstrate optical parametric amplification operating at GHz-rates at telecommunications wavelengths using a hydrogenated amorphous silicon waveguide through the nonlinear optical process of four-wave mixing. We investigate how the parametric amplification scales with repetition rate. The ability to achieve amplification at GHz-repetition rates shows hydrogenated amorphous silicon’s potential for telecommunication applications and a GHz-rate optical parametric oscillator. (paper)
Synchronization of chaos in non-identical parametrically excited systems
International Nuclear Information System (INIS)
Idowu, B.A.; Vincent, U.E.; Njah, A.N.
2009-01-01
In this paper, we investigate the synchronization of chaotic systems consisting of non-identical parametrically excited oscillators. The active control technique is employed to design control functions based on Lyapunov stability theory and Routh-Hurwitz criteria so as to achieve global chaos synchronization between a parametrically excited gyroscope and each of the parametrically excited pendulum and Duffing oscillator. Numerical simulations are implemented to verify the results.
Parametric Design of Outdoor Broadcasting Studio Based on Schema Theory
Zhu Li; Zhang Nan; Qing Xiaoying
2016-01-01
This paper mainly demonstrates that the schema is an important way for the architect to cognize architecture form logic. It connects schema to algorithm of parametric design in order to seek the “algorithm schema” generation in parametric design of architecture. Meanwhile, this paper discusses the generative process and methods of the “algorithm schema” in parametric design of architecture by describing a case of outdoor broadcasting studio of Hunan Economic Radio. It also reveals the importa...
Spontaneous emission effects in optically pumped x-ray FEL
Energy Technology Data Exchange (ETDEWEB)
Smetanin, I.V.; Grigor`ev, S.V. [P.N. Lebedev Physics Institute, Moscow (Russian Federation)
1995-12-31
An effect of spontaneous emission in both quantum and classical regimes of the optically pumped X-ray free electron laser (FEL) in investigated. The quantum properties of an FEL are determined by the ratio of the separation {h_bar} between the absorption and emission lines (i.e. the quanta emitted) and their effective width {Delta}{epsilon} {eta}={h_bar}/{Delta}{epsilon}. In the conventional classical regime {eta} {much_lt} 1 an electron emits and absorbes a great number of shortwavelength photons over the interaction region, the gain in FEL being the result of these competitive processes. In the quantum limit {eta} {much_gt} 1 the emission and absorption lines are completely separated and thus the FEL becomes a two-level quantum oscillator with a completely inverted active medium. Spontaneous emission causes the electron to leave the range of energies where resonant interaction with the laser field occurs, thus effectively reducing the number of particles that take part in generating the induced X-ray signal. This effect is found to be crucial for lasing in optically pumped X-ray FEL. The characteristic relaxation times are calculated for both classical and quantum FEL regimes. It is shown that spontaneous emission results in FEL electron beam threshold current, which is of rather high value. An optimal range of pumping laser intensities is determined.
DEFF Research Database (Denmark)
Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke
2013-01-01
We present an experimental characterization of how signal gain saturation affects the transfer of intensity modulation from the pump to the signal in single-pump, phase-insensitive fiber optic parametric amplifiers (FOPAs). In this work, we demonstrate experimentally for the first time, to our...
Supramodal parametric working memory processing in humans.
Spitzer, Bernhard; Blankenburg, Felix
2012-03-07
Previous studies of delayed-match-to-sample (DMTS) frequency discrimination in animals and humans have succeeded in delineating the neural signature of frequency processing in somatosensory working memory (WM). During retention of vibrotactile frequencies, stimulus-dependent single-cell and population activity in prefrontal cortex was found to reflect the task-relevant memory content, whereas increases in occipital alpha activity signaled the disengagement of areas not relevant for the tactile task. Here, we recorded EEG from human participants to determine the extent to which these mechanisms can be generalized to frequency retention in the visual and auditory domains. Subjects performed analogous variants of a DMTS frequency discrimination task, with the frequency information presented either visually, auditorily, or by vibrotactile stimulation. Examining oscillatory EEG activity during frequency retention, we found characteristic topographical distributions of alpha power over visual, auditory, and somatosensory cortices, indicating systematic patterns of inhibition and engagement of early sensory areas, depending on stimulus modality. The task-relevant frequency information, in contrast, was found to be represented in right prefrontal cortex, independent of presentation mode. In each of the three modality conditions, parametric modulations of prefrontal upper beta activity (20-30 Hz) emerged, in a very similar manner as recently found in vibrotactile tasks. Together, the findings corroborate a view of parametric WM as supramodal internal scaling of abstract quantity information and suggest strong relevance of previous evidence from vibrotactile work for a more general framework of quantity processing in human working memory.
Airborne Methane Measurements using Optical Parametric Amplifiers
Riris, H.; Numata, K.; Li, S.; Wu, S.; Ramanathan, A.; Dawsey, M.; Abshire, J. B.; Kawa, S. R.; Mao, J.
2012-12-01
We report on airborne methane measurements with an active sensing instrument using widely tunable, seeded optical parametric generation (OPG). Methane is a strong greenhouse gas on Earth and it is also a potential biogenic marker on Mars and other planetary bodies. Methane in the Earth's atmosphere survives for a shorter time than CO2 but its impact on climate change can be larger than CO2. Carbon and methane emissions from land are expected to increase as permafrost melts exposing millennial-age carbon stocks to respiration (aerobic-CO2 and anaerobic-CH4) and fires. Methane emissions from clathrates in the Arctic Ocean and on land are also likely to respond to climate warming. However, there is considerable uncertainty in present Arctic flux levels, as well as how fluxes will change with the changing environment and more measurements are needed. In this paper we report on an airborne demonstration of atmospheric methane column optical depth measurements at 1.65 μm using widely tunable, seeded optical parametric amplifier (OPA) and a photon counting detector. Our results show good agreement between the experimentally derived optical depth measurements and theoretical calculations and follow the expected changes for aircraft altitudes from 3 to 11 km. The technique has also been used to measure carbon dioxide and monoxide, water vapor, and other trace gases in the near and mid-infrared spectral regions on the ground.
Parametric uncertainty in optical image modeling
Potzick, James; Marx, Egon; Davidson, Mark
2006-10-01
Optical photomask feature metrology and wafer exposure process simulation both rely on optical image modeling for accurate results. While it is fair to question the accuracies of the available models, model results also depend on several input parameters describing the object and imaging system. Errors in these parameter values can lead to significant errors in the modeled image. These parameters include wavelength, illumination and objective NA's, magnification, focus, etc. for the optical system, and topography, complex index of refraction n and k, etc. for the object. In this paper each input parameter is varied over a range about its nominal value and the corresponding images simulated. Second order parameter interactions are not explored. Using the scenario of the optical measurement of photomask features, these parametric sensitivities are quantified by calculating the apparent change of the measured linewidth for a small change in the relevant parameter. Then, using reasonable values for the estimated uncertainties of these parameters, the parametric linewidth uncertainties can be calculated and combined to give a lower limit to the linewidth measurement uncertainty for those parameter uncertainties.
Parametric amplification and cascaded-nonlinearity processes in common atomic system.
Zheng, Huaibin; Zhang, Xun; Zhang, Zhaoyang; Tian, Yaling; Chen, Haixia; Li, Changbiao; Zhang, Yanpeng
2013-01-01
For the first time, we study the parametric amplification process of multi-wave mixing (PA-MWM) signal and cascaded-nonlinearity process (CNP) in sodium vapors both theoretically and experimentally, based on a conventional phase-conjugate MWM and a self-diffraction four-wave mixing (SD-FWM) processes, which are pumped by laser or amplified spontaneous emission (ASE), respectively. For laser pumping case, SD-FWM process serves as a quantum linear amplifier (a CNP) out (inside) of the resonant absorption region. While for ASE case, only the CNP occurs and the output linewidth is much narrower than that of the MWM signal due to the second selected effect of its electromagnetically induced transparency window. In addition, the phase-sensitive amplifying process seeded by two MWM processes is discussed for the first time. Theoretical fittings agree well with the experiment. The investigations have important potential applications in quantum communication.
Estimation of Parametric Fault in Closed-loop Systems
DEFF Research Database (Denmark)
Niemann, Hans Henrik; Poulsen, Niels Kjølstad
2015-01-01
The aim of this paper is to present a method for estimation of parametric faults in closed-loop systems. The key technology applied in this paper is coprime factorization of both the dynamic system as well as the feedback controller. Using the Youla-Jabr-Bongiorno-Kucera (YJBK) parameterization......, it is shown that a certain matrix transfer function, the fault signature matrix, is an LFT (linear fractional transformation) of the parametric faults. Further, for limit parametric faults, the fault signature matrix transfer function can be approximated with a linear matrix function of the parametric faults....
Radiological evaluation of spontaneous pneumoperitoneum
International Nuclear Information System (INIS)
Kim, H. S.; Kim, J. D.; Rhee, H. S.
1982-01-01
112 cases of spontaneous penumoperitoneum, the causes of which were confirmed by clinical and surgical procedure at Presbyterian Medical Center from January, 1977 to July, 1981 were reviewed radiologically. The results were as follows: 1. Perforation of duodenal ulcer (46/112: 41.1%), stomach ulcer (22/112: 19.6%), and stomach cancer (11/112: 9.8%) were the three most common causes of spontaneous penumoperitoneum. These were 70.5% of all causes. 2. The most common site of free gas was both subdiaphragmatic areas (46: 41.1%). Others were Rt. subdiaphragmatic only (31: 27.7%), both subdiaphragmatic with subhepatic (16: 14.3%), Rt. subdiaphragmatic with subhepatic (7: 6.2%), Rt. subdiaphragmatic only (5: 4.4%), diffuse in abdomen (4: 3.6%), and subhepatic only (3: 2.7%). So 92.0% (103/112) were located in RUQ. 3. The radiological shape of free gas was classified: crescent (52: 46.4%) of small amount; half-moon (21: 18.8%) of moderate amount; large or diffuse (39: 34.8%) of large amount.4. The age between 31 and 60 occupied 69.1% (77/112), and male was predominant (5.2 times). 5. The patient's position showing free air most frequently was erect
A Case of Multiple Spontaneous Keloid Scars
Directory of Open Access Journals (Sweden)
Abdulhadi Jfri
2015-07-01
Full Text Available Keloid scars result from an abnormal healing response to cutaneous injury or inflammation that extends beyond the borders of the original wound. Spontaneous keloid scars forming in the absence of any previous trauma or surgical procedure are rare. Certain syndromes have been associated with this phenomenon, and few reports have discussed the evidence of single spontaneous keloid scar, which raises the question whether they are really spontaneous. Here, we present a 27-year-old mentally retarded single female with orbital hypertelorism, broad nasal bridge, repaired cleft lip and high-arched palate who presented with progressive multiple spontaneous keloid scars in different parts of her body which were confirmed histologically by the presence of typical keloidal collagen. This report supports the fact that keloid scars can appear spontaneously and are possibly linked to a genetic factor. Furthermore, it describes a new presentation of spontaneous keloid scars in the form of multiple large lesions in different sites of the body.
Spontaneity of communication in individuals with autism.
Chiang, Hsu-Min; Carter, Mark
2008-04-01
This article provides an examination of issues related to spontaneity of communication in children with autism. Deficits relating to spontaneity or initiation are frequently reported in individuals with autism, particularly in relation to communication and social behavior. Nevertheless, spontaneity is not necessarily clearly conceptualized or measured. Several approaches to conceptualization of communicative spontaneity are examined with a particular focus on the continuum model and how it might be practically applied. A range of possible explanations for deficits in spontaneity of communication in children with autism is subsequently explored, including external factors (highly structured teaching programs, failure to systematically instruct for spontaneity) and intrinsic characteristics (intellectual disability, stimulus overselectivity, weak central coherence). Possible implications for future research are presented.
The influence of dual-recycling on parametric instabilities at Advanced LIGO
International Nuclear Information System (INIS)
Green, A C; Brown, D D; Dovale-Álvarez, M; Collins, C; Miao, H; Mow-Lowry, C M; Freise, A
2017-01-01
Laser interferometers with high circulating power and suspended optics, such as the LIGO gravitational wave detectors, experience an optomechanical coupling effect known as a parametric instability : the runaway excitation of a mechanical resonance in a mirror driven by the optical field. This can saturate the interferometer sensing and control systems and limit the observation time of the detector. Current mitigation techniques at the LIGO sites are successfully suppressing all observed parametric instabilities, and focus on the behaviour of the instabilities in the Fabry–Perot arm cavities of the interferometer, where the instabilities are first generated. In this paper we model the full dual-recycled Advanced LIGO design with inherent imperfections. We find that the addition of the power- and signal-recycling cavities shapes the interferometer response to mechanical modes, resulting in up to four times as many peaks. Changes to the accumulated phase or Gouy phase in the signal-recycling cavity have a significant impact on the parametric gain, and therefore which modes require suppression. (paper)
Li, Ying; Zhong, Haizhe; Yang, Jianlong; Wang, Shiwei; Fan, Dianyuan
2017-07-15
Conversion efficiency and phase-matching (PM) bandwidth are both critical issues for broadband parametric processes. In some sense, they determine the highest peak power achieved via the optical parametric amplification. In this Letter, a versatile idler-separated quasi-phase matching scheme capable of both backconversion circumvention and ultra-broadband PM is presented. Full-dimensional spatial-temporal simulations for the typical optical parametric chirped pulse amplification processes at 800 nm and 3.4 μm were presented in detail. By virtue of the broad PM bandwidth on account of the non-collinear PM configuration, the backconversion circumvention on account of the idler-separated design, and the walk-off self-compensation on account of the symmetrical tilting grating patterns, significantly improved gain bandwidth, extremely high conversion efficiency, and a well-preserved beam profile are simultaneously achieved. Compared with the collinear configuration, the peak power can be potentially enhanced by 5-10 times under the same operation circumstances.
Improved Gain Microstrip Patch Antenna
2015-08-06
frequency selective structure (FSS) as a layer above a microstrip patch antenna. This is done to filter undesirable frequencies. For this purpose the FSS...is used for isolating the antenna from the filtered frequency, not improving the gain of the antenna. [0008] Thus, there is a need for microstrip...selective surface applied. The passband is generally indicated as the region where the curve passes below a VSWR of 3. These results indicate a
Optical gain in silicon nanocrystals
Czech Academy of Sciences Publication Activity Database
Pelant, Ivan
2011-01-01
Roč. 208, č. 3 (2011), s. 625-630 ISSN 1862-6300 R&D Projects: GA AV ČR KAN400100701; GA AV ČR(CZ) IAA101120804; GA MŠk LC510 Institutional research plan: CEZ:AV0Z10100521 Keywords : experimental approach * luminescence * nanocrystals * optical gain * silicon Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.463, year: 2011
Spontaneous cryptococcal peritonitis in cirrhotic patients.
Directory of Open Access Journals (Sweden)
Sungkanuparph S
2002-07-01
Full Text Available Spontaneous bacterial peritonitis is a common complication in patients with cirrhosis and ascites. However, spontaneous peritonitis caused by Cryptococcus neoformans is uncommon. Delayed diagnosis of cryptococcal peritonitis often results in death. We describe three cases of spontaneous cryptococcal peritonitis in patients with decompensated cirrhosis. One case had associated symptomatic human immunodeficiency virus infection. Clinical awareness of this entity may lead to the early diagnosis and proper treatment.
Spontaneous Intracranial Hypotension without Orthostatic Headache
Directory of Open Access Journals (Sweden)
Tülay Kansu
2009-03-01
Full Text Available We report 2 cases of spontaneous intracranial hypotension that presented with unilateral abducens nerve palsy, without orthostatic headache. While sixth nerve palsies improved without any intervention, subdural hematoma was detected with magnetic resonance imaging. We conclude that headache may be absent in spontaneous intracranial hypotension and spontaneous improvement of sixth nerve palsy can occur, even after the development of a subdural hematoma
Spontaneous renal hematoma - a case report
International Nuclear Information System (INIS)
Obrzut, M.; Obrzut, M.; Homa, J.; Obrzut, B.
2006-01-01
Spontaneous pararenal hematoma is a rare pathology most frequently coexisting with renal tumours, vascular anomalies and inflammatory processes. In some cases one cannot establish its etiology. The paper describes a case of a 58-year-old man with a spontaneous pararenal hematoma and presents a diagnostic algorithm. Ultrasonography and CT play an important role in diagnostics of spontaneous pararenal haemorrhages. These methods enable a precise evaluation of size and location of hematoma and its evolution. (author)
Cao, Nan; Zhu, Hongna; Li, Peipei; Taccheo, Stefano; Zhu, Yuanna; Gao, Xiaorong; Wang, Zeyong
2018-03-01
A two-pump fiber optical parametric amplifier (FOPA) based on the photonic crystal fiber (PCF) in the telecommunication region is investigated numerically. The fiber loss and pump depletion are considered. The influences of the fiber length, input signal power, input pump power, and the center pump wavelength on the gain bandwidth, flatness, and peak gain are discussed. The 6-wave model-based analysis of two-pump FOPA is also achieved and compared with that based on the 4-wave model; furthermore, the gain properties of the FOPA based on the 6-wave model are optimized and investigated. The comparison results show that the PCF-based two-pump FOPA achieves flatter and wider gain spectra with less fiber length and input pump power compared to the two-pump FOPA based on the normal highly nonlinear fiber, where the obtained results show the great potential of the FOPA for the optical communication system.
Biomarkers of spontaneous preterm birth
DEFF Research Database (Denmark)
Polettini, Jossimara; Cobo, Teresa; Kacerovsky, Marian
2017-01-01
predictors of pregnancy outcome. This systematic review was conducted to synthesize the knowledge on PTB biomarkers identified using multiplex analysis. Three electronic databases (PubMed, EMBASE and Web of Science) were searched for studies in any language reporting the use of multiplex assays for maternal......Despite decades of research on risk indicators of spontaneous preterm birth (PTB), reliable biomarkers are still not available to screen or diagnose high-risk pregnancies. Several biomarkers in maternal and fetal compartments have been mechanistically linked to PTB, but none of them are reliable......) followed by MIP-1β, GM-CSF, Eotaxin, and TNF-RI (two studies) were reported more than once in maternal serum. However, results could not be combined due to heterogeneity in type of sample, study population, assay, and analysis methods. By this systematic review, we conclude that multiplex assays...
Spontaneous Strategies in Innovation Networks
DEFF Research Database (Denmark)
Plesner, Ursula; Husted, Emil Krastrup
and a site ontology, we show how physical sites and objects become constitutive of the inside of virtual worlds through innovation processes. This argument is in line with ANT’s perspective on strategy, where sites and objects are considered a strategically relevant resource in the innovation process...... of materiality in relation to the organization and structuring of virtual worlds. We examine various innovation processes in five Danish entrepreneurial companies where actors continuously struggle to stabilize virtual worlds as platforms for professional communication. With inspiration from actor-network theory....... Empirically, the analysis is founded on descriptive accounts from the five entrepreneurs. By highlighting the spontaneous strategies described by actors, we show how sites and objects are actively used as an element in their strategy, and also how the sites and objects end up facilitating new ways of thinking...
Toward a compact fibered squeezing parametric source.
Brieussel, Alexandre; Ott, Konstantin; Joos, Maxime; Treps, Nicolas; Fabre, Claude
2018-03-15
In this work, we investigate three different compact fibered systems generating vacuum squeezing that involve optical cavities limited by the end surface of a fiber and by a curved mirror and containing a thin parametric crystal. These systems have the advantage to couple squeezed states directly to a fiber, allowing the user to benefit from the flexibility of fibers in the use of squeezing. Three types of fibers are investigated: standard single-mode fibers, photonic-crystal large-mode-area single-mode fibers, and short multimode fibers taped to a single-mode fiber. The observed squeezing is modest (-0.56 dB, -0.9 dB, -1 dB), but these experiments open the way for miniaturized squeezing devices that could be a very interesting advantage in scaling up quantum systems for quantum processing, opening new perspectives in the domain of integrated quantum optics.
Normal dispersion femtosecond fiber optical parametric oscillator.
Nguyen, T N; Kieu, K; Maslov, A V; Miyawaki, M; Peyghambarian, N
2013-09-15
We propose and demonstrate a synchronously pumped fiber optical parametric oscillator (FOPO) operating in the normal dispersion regime. The FOPO generates chirped pulses at the output, allowing significant pulse energy scaling potential without pulse breaking. The output average power of the FOPO at 1600 nm was ∼60 mW (corresponding to 1.45 nJ pulse energy and ∼55% slope power conversion efficiency). The output pulses directly from the FOPO were highly chirped (∼3 ps duration), and they could be compressed outside of the cavity to 180 fs by using a standard optical fiber compressor. Detailed numerical simulation was also performed to understand the pulse evolution dynamics around the laser cavity. We believe that the proposed design concept is useful for scaling up the pulse energy in the FOPO using different pumping wavelengths.
Parametric description of the quantum measurement process
Liuzzo-Scorpo, P.; Cuccoli, A.; Verrucchi, P.
2015-08-01
We present a description of the measurement process based on the parametric representation with environmental coherent states. This representation is specifically tailored for studying quantum systems whose environment needs being considered through the quantum-to-classical crossover. Focusing upon projective measures, and exploiting the connection between large-N quantum theories and the classical limit of related ones, we manage to push our description beyond the pre-measurement step. This allows us to show that the outcome production follows from a global-symmetry breaking, entailing the observed system's state reduction, and that the statistical nature of the process is brought about, together with the Born's rule, by the macroscopic character of the measuring apparatus.
Parametric systems analysis for ICF hybrid reactors
International Nuclear Information System (INIS)
Berwald, D.H.; Maniscalco, J.A.; Chapin, D.L.
1981-01-01
Parametric design and systems analysis for inertial confinement fusion-fission hybrids are presented. These results were generated as part of the Electric Power Research Institute (EPRI) sponsored Feasibility Assessment of Fusion-Fission Hybrids, using an Inertial Confinement Fusion (ICF) hybrid power plant design code developed in conjunction with the feasibility assessment. The SYMECON systems analysis code, developed by Westinghouse, was used to generate economic results for symbiotic electricity generation systems consisting of the hybrid and its client Light Water Reactors (LWRs). These results explore the entire fusion parameter space for uranium fast fission blanket hybrids, thorium fast fission blanket hybrids, and thorium suppressed fission blanket types are discussed, and system sensitivities to design uncertainties are explored
Parametric time-frequency domain spatial audio
Delikaris-Manias, Symeon; Politis, Archontis
2018-01-01
This book provides readers with the principles and best practices in spatial audio signal processing. It describes how sound fields and their perceptual attributes are captured and analyzed within the time-frequency domain, how essential representation parameters are coded, and how such signals are efficiently reproduced for practical applications. The book is split into four parts starting with an overview of the fundamentals. It then goes on to explain the reproduction of spatial sound before offering an examination of signal-dependent spatial filtering. The book finishes with coverage of both current and future applications and the direction that spatial audio research is heading in. Parametric Time-frequency Domain Spatial Audio focuses on applications in entertainment audio, including music, home cinema, and gaming--covering the capturing and reproduction of spatial sound as well as its generation, transduction, representation, transmission, and perception. This book will teach readers the tools needed...
Spherical Parametrization of the Higgs Boson Candidate
Gainer, James S; Matchev, Konstantin T; Mrenna, Stephen; Park, Myeonghun
2013-01-01
The latest results from the ATLAS and CMS experiments at the CERN Large Hadron Collider (LHC) unequivocally confirm the existence of a resonance, $X$, with mass near 125 GeV which could be the Higgs boson of the Standard Model. Measuring the properties (quantum numbers and couplings) of this resonance is of paramount importance. Initial analyses by the LHC collaborations disfavor specific alternative benchmark hypotheses, e.g. pure pseudoscalars or gravitons. However, this is just the first step in a long-term program of detailed measurements. We consider the most general set of operators in the decay channels $X \\to ZZ$, $WW$, $Z\\gamma$, $\\gamma\\gamma$ and derive the constraint implied by the measured rate. This allows us to provide a useful parametrization of the orthogonal independent Higgs coupling degrees of freedom as coordinates on a suitably defined sphere.
Parametric design and gridding through relational geometry
Letcher, John S., Jr.; Shook, D. Michael
1995-01-01
Relational Geometric Synthesis (RGS) is a new logical framework for building up precise definitions of complex geometric models from points, curves, surfaces and solids. RGS achieves unprecedented design flexibility by supporting a rich variety of useful curve and surface entities. During the design process, many qualitative and quantitative relationships between elementary objects may be captured and retained in a data structure equivalent to a directed graph, such that they can be utilized for automatically updating the complete model geometry following changes in the shape or location of an underlying object. Capture of relationships enables many new possibilities for parametric variations and optimization. Examples are given of panelization applications for submarines, sailing yachts, offshore structures, and propellers.
The parametric representation of the city
Directory of Open Access Journals (Sweden)
Luisa Bravo
2010-06-01
Full Text Available Representation of the city, according to dictates of classical literature and manuals, takes shape from studies about morphology and expressive language of the urban plot, in a deep connection between spaces, monuments and significant buildings. In the contemporary digital era, city can be described as a linkage of elements converging toward built environment's generation, following gathering procedures detectable by parameters. Present territorial planning can take advantage of these criteria, in order to simulate the evolving of urban realities and reach predictable or desirable development frontiers, using models made by computer software aimed to favour choices in managing and transforming the city. Parametric technologies make possible to embed information into urban digital models, intended as sort of data collectors browsable in real time.
Examples in parametric inference with R
Dixit, Ulhas Jayram
2016-01-01
This book discusses examples in parametric inference with R. Combining basic theory with modern approaches, it presents the latest developments and trends in statistical inference for students who do not have an advanced mathematical and statistical background. The topics discussed in the book are fundamental and common to many fields of statistical inference and thus serve as a point of departure for in-depth study. The book is divided into eight chapters: Chapter 1 provides an overview of topics on sufficiency and completeness, while Chapter 2 briefly discusses unbiased estimation. Chapter 3 focuses on the study of moments and maximum likelihood estimators, and Chapter 4 presents bounds for the variance. In Chapter 5, topics on consistent estimator are discussed. Chapter 6 discusses Bayes, while Chapter 7 studies some more powerful tests. Lastly, Chapter 8 examines unbiased and other tests. Senior undergraduate and graduate students in statistics and mathematics, and those who have taken an introductory cou...
Recurrent spontaneous attacks of dizziness.
Lempert, Thomas
2012-10-01
This article describes the common causes of recurrent vertigo and dizziness that can be diagnosed largely on the basis of history. Ninety percent of spontaneous recurrent vertigo and dizziness can be explained by six disorders: (1) Ménière disease is characterized by vertigo attacks, lasting 20 minutes to several hours, with concomitant hearing loss, tinnitus, and aural fullness. Aural symptoms become permanent during the course of the disease. (2) Attacks of vestibular migraine may last anywhere from minutes to days. Most patients have a previous history of migraine headaches, and many experience migraine symptoms during the attack. (3) Vertebrobasilar TIAs affect older adults with vascular risk factors. Most attacks last less than 1 hour and are accompanied by other symptoms from the posterior circulation territory. (4) Vestibular paroxysmia is caused by vascular compression of the eighth cranial nerve. It manifests itself with brief attacks of vertigo that recur many times per day, sometimes with concomitant cochlear symptoms. (5) Orthostatic hypotension causes brief episodes of dizziness lasting seconds to a few minutes after standing up and is relieved by sitting or lying down. In older adults, it may be accompanied by supine hypertension. (6) Panic attacks usually last minutes, occur in specific situations, and are accompanied by choking, palpitations, tremor, heat, and anxiety. Less common causes of spontaneous recurrent vertigo and dizziness include perilymph fistula, superior canal dehiscence, autoimmune inner ear disease, otosclerosis, cardiac arrhythmia, and medication side effects. Neurologists need to venture into otolaryngology, internal medicine, and psychiatry to master the differential diagnosis of recurrent dizziness.
Crows spontaneously exhibit analogical reasoning.
Smirnova, Anna; Zorina, Zoya; Obozova, Tanya; Wasserman, Edward
2015-01-19
Analogical reasoning is vital to advanced cognition and behavioral adaptation. Many theorists deem analogical thinking to be uniquely human and to be foundational to categorization, creative problem solving, and scientific discovery. Comparative psychologists have long been interested in the species generality of analogical reasoning, but they initially found it difficult to obtain empirical support for such thinking in nonhuman animals (for pioneering efforts, see [2, 3]). Researchers have since mustered considerable evidence and argument that relational matching-to-sample (RMTS) effectively captures the essence of analogy, in which the relevant logical arguments are presented visually. In RMTS, choice of test pair BB would be correct if the sample pair were AA, whereas choice of test pair EF would be correct if the sample pair were CD. Critically, no items in the correct test pair physically match items in the sample pair, thus demanding that only relational sameness or differentness is available to support accurate choice responding. Initial evidence suggested that only humans and apes can successfully learn RMTS with pairs of sample and test items; however, monkeys have subsequently done so. Here, we report that crows too exhibit relational matching behavior. Even more importantly, crows spontaneously display relational responding without ever having been trained on RMTS; they had only been trained on identity matching-to-sample (IMTS). Such robust and uninstructed relational matching behavior represents the most convincing evidence yet of analogical reasoning in a nonprimate species, as apes alone have spontaneously exhibited RMTS behavior after only IMTS training. Copyright © 2015 Elsevier Ltd. All rights reserved.
GAIN Technology Workshops Summary Report
International Nuclear Information System (INIS)
Braase, Lori Ann
2016-01-01
National and global demand for nuclear energy is increasing and United States (U.S.) global leadership is eroding. There is a sense of urgency with respect to the deployment of the innovative nuclear energy technologies. The Gateway for Accelerated Innovation in Nuclear (GAIN) initiative is based on the simultaneous achievement of three strategic goals. The first is maintaining global technology leadership within the U.S. Department of Energy (DOE). The second is enabling global industrial leadership for nuclear vendors and suppliers. The third is focused on utility optimization of nuclear energy within the clean energy portfolio. An effective public-private partnership is required to achieve these goals. DOEs recognizes the recent sense of urgency new developers and investors have in getting their concepts to market. They know that time to market for nuclear technology takes too long and the facilities needed to conduct the necessary research, development and demonstration (RD&D) activities are very expensive to develop and maintain. Early technologies, in the lower technology readiness levels (TRL) need materials testing, analysis, modeling, code development, etc., most of which currently exists in the DOE national laboratory system. However, mature technologies typically need large component testing and demonstration facilities, which are expensive and long-lead efforts. By understanding the needs of advanced nuclear technology developers, GAIN will connect DOE national laboratory capabilities (e.g., facilities, expertise, materials, and data) with industry RD&D needs. In addition, GAIN is working with the Nuclear Regulatory Commission (NRC) to streamline processes and increase understanding of the licensing requirements for advanced reactors.
GAIN Technology Workshops Summary Report
Energy Technology Data Exchange (ETDEWEB)
Braase, Lori Ann [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2016-08-01
National and global demand for nuclear energy is increasing and United States (U.S.) global leadership is eroding. There is a sense of urgency with respect to the deployment of the innovative nuclear energy technologies. The Gateway for Accelerated Innovation in Nuclear (GAIN) initiative is based on the simultaneous achievement of three strategic goals. The first is maintaining global technology leadership within the U.S. Department of Energy (DOE). The second is enabling global industrial leadership for nuclear vendors and suppliers. The third is focused on utility optimization of nuclear energy within the clean energy portfolio. An effective public-private partnership is required to achieve these goals. DOEs recognizes the recent sense of urgency new developers and investors have in getting their concepts to market. They know that time to market for nuclear technology takes too long and the facilities needed to conduct the necessary research, development and demonstration (RD&D) activities are very expensive to develop and maintain. Early technologies, in the lower technology readiness levels (TRL) need materials testing, analysis, modeling, code development, etc., most of which currently exists in the DOE national laboratory system. However, mature technologies typically need large component testing and demonstration facilities, which are expensive and long-lead efforts. By understanding the needs of advanced nuclear technology developers, GAIN will connect DOE national laboratory capabilities (e.g., facilities, expertise, materials, and data) with industry RD&D needs. In addition, GAIN is working with the Nuclear Regulatory Commission (NRC) to streamline processes and increase understanding of the licensing requirements for advanced reactors.
Parametric representation of centrifugal pump homologous curves
International Nuclear Information System (INIS)
Veloso, Marcelo A.; Mattos, Joao R.L. de
2015-01-01
Essential for any mathematical model designed to simulate flow transient events caused by pump operations is the pump performance data. The performance of a centrifugal pump is characterized by four basic quantities: the rotational speed, the volumetric flow rate, the dynamic head, and the hydraulic torque. The curves showing the relationships between these four variables are called the pump characteristic curves. The characteristic curves are empirically developed by the pump manufacturer and uniquely describe head and torque as functions of volumetric flow rate and rotation speed. Because of comprising a large amount of points, this configuration is not suitable for computational purposes. However, it can be converted to a simpler form by the development of the homologous curves, in which dynamic head and hydraulic torque ratios are expressed as functions of volumetric flow and rotation speed ratios. The numerical use of the complete set of homologous curves requires specification of sixteen partial curves, being eight for the dynamic head and eight for the hydraulic torque. As a consequence, the handling of homologous curves is still somewhat complicated. In solving flow transient problems that require the pump characteristic data for all the operation zones, the parametric form appears as the simplest way to deal with the homologous curves. In this approach, the complete characteristics of a pump can be described by only two closed curves, one for the dynamic head and other for the hydraulic torque, both in function of a single angular coordinate defined adequately in terms of the quotient between volumetric flow ratio and rotation speed ratio. The usefulness and advantages of this alternative method are demonstrated through a practical example in which the homologous curves for a pump of the type used in the main coolant loops of a pressurized water reactor (PWR) are transformed to the parametric form. (author)
Parametric representation of centrifugal pump homologous curves
Energy Technology Data Exchange (ETDEWEB)
Veloso, Marcelo A.; Mattos, Joao R.L. de, E-mail: velosom@cdtn.br, E-mail: jrmattos@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)
2015-07-01
Essential for any mathematical model designed to simulate flow transient events caused by pump operations is the pump performance data. The performance of a centrifugal pump is characterized by four basic quantities: the rotational speed, the volumetric flow rate, the dynamic head, and the hydraulic torque. The curves showing the relationships between these four variables are called the pump characteristic curves. The characteristic curves are empirically developed by the pump manufacturer and uniquely describe head and torque as functions of volumetric flow rate and rotation speed. Because of comprising a large amount of points, this configuration is not suitable for computational purposes. However, it can be converted to a simpler form by the development of the homologous curves, in which dynamic head and hydraulic torque ratios are expressed as functions of volumetric flow and rotation speed ratios. The numerical use of the complete set of homologous curves requires specification of sixteen partial curves, being eight for the dynamic head and eight for the hydraulic torque. As a consequence, the handling of homologous curves is still somewhat complicated. In solving flow transient problems that require the pump characteristic data for all the operation zones, the parametric form appears as the simplest way to deal with the homologous curves. In this approach, the complete characteristics of a pump can be described by only two closed curves, one for the dynamic head and other for the hydraulic torque, both in function of a single angular coordinate defined adequately in terms of the quotient between volumetric flow ratio and rotation speed ratio. The usefulness and advantages of this alternative method are demonstrated through a practical example in which the homologous curves for a pump of the type used in the main coolant loops of a pressurized water reactor (PWR) are transformed to the parametric form. (author)
Parametric excitation of plasma oscillations in Josephson Junctions
DEFF Research Database (Denmark)
Pedersen, Niels Falsig; Samuelsen, Mogens Rugholm; Særmark, Knud
1973-01-01
A theory is presented for parametric excitation of plasma oscillations in a Josephson junction biased in the zero voltage mode. A threshold curve for the onset of the parametric excitation is deduced via the stability properties of a Mathieu differential equation obtained by a self...
Parametric excitation of drift waves in a sheared slab geometry
International Nuclear Information System (INIS)
Vranjes, J.; Weiland, J.
1992-01-01
The threshold for parametric excitation of drift waves in a sheared slab geometry is calculated for a pump wave that is a standing wave along the magnetic field, using the Hasegawa-Mima nonlinearity. The shear damping is counteracted by the parametric coupling and the eigenvalue problem is solved analytically using Taylor's strong coupling approximation. (au)
Converting Geometry from Creo Parametric to BRL-CAD
2017-06-28
ARL-SR-0376 ● JUNE 2017 US Army Research Laboratory Converting Geometry from Creo Parametric to BRL- CAD by Clifford W Yapp...to the originator. ARL-SR-0376 ● JUNE 2017 US Army Research Laboratory Converting Geometry from Creo Parametric to BRL- CAD by...
Parametric instabilities in magnetized bi-ion and dusty plasmas
Indian Academy of Sciences (India)
The excitation of low frequency modes of oscillations in a magnetized bi-ion or dusty plasma with parametric pumping of the magnetic ﬁeld is analysed. The equation of motion governing the perturbed plasma is derived and parametrically excited transverse modes propagating along the magnetic ﬁeld are found.
Mechanism for an absolute parametric instability of an inhomogeneous plasma
Arkhipenko, V. I.; Budnikov, V. N.; Gusakov, E. Z.; Romanchuk, I. A.; Simonchik, L. V.
1984-05-01
The structure of plasma oscillations in a region of parametric spatial amplification has been studied experimentally for the first time. A new mechanism for an absolute parametric instability has been observed. This mechanism operates when a pump wave with a spatial structure more complicated than a plane wave propagates through a plasma which is inhomogeneous along more than one dimension.
A PARAMETRIC STUDY OF THE INFLUENCE OF SHORT-TERM ...
African Journals Online (AJOL)
(b). (•). Figure I a) The building embedded in a layered formation; b) The building model with base springs. PARAMETRIC STUDY. 'fhe parametric study carried out in this work aims at investigating the effect of the soil flexibility on the internal force distribution of selected structural systems of buildings that are founded on soil.
Approximate Implicitization of Parametric Curves Using Cubic Algebraic Splines
Directory of Open Access Journals (Sweden)
Xiaolei Zhang
2009-01-01
Full Text Available This paper presents an algorithm to solve the approximate implicitization of planar parametric curves using cubic algebraic splines. It applies piecewise cubic algebraic curves to give a global G2 continuity approximation to planar parametric curves. Approximation error on approximate implicitization of rational curves is given. Several examples are provided to prove that the proposed method is flexible and efficient.
Parametric Hidden Markov Models for Recognition and Synthesis of Movements
DEFF Research Database (Denmark)
Herzog, Dennis; Krüger, Volker; Grest, Daniel
2008-01-01
In humanoid robotics, the recognition and synthesis of parametric movements plays an extraordinary role for robot human interaction. Such a parametric movement is a movement of a particular type (semantic), for example, similar pointing movements performed at different table-top positions. For un...
Schwinger-type parametrization of open string worldsheets
Directory of Open Access Journals (Sweden)
Sam Playle
2017-03-01
Full Text Available A parametrization of (super moduli space near the corners corresponding to bosonic or Neveu–Schwarz open string degenerations is introduced for worldsheets of arbitrary topology. With this parametrization, Feynman graph polynomials arise as the α′→0 limit of objects on moduli space. Furthermore, the integration measures of string theory take on a very simple and elegant form.
Parametric Room Acoustic workflows with real-time acoustic simulation
DEFF Research Database (Denmark)
Parigi, Dario
2017-01-01
The paper investigates and assesses the opportunities that real-time acoustic simulation offer to engage in parametric acoustics workflow and to influence architectural designs from early design stages......The paper investigates and assesses the opportunities that real-time acoustic simulation offer to engage in parametric acoustics workflow and to influence architectural designs from early design stages...
Design and development of a parametrically excited nonlinear energy harvester
International Nuclear Information System (INIS)
Yildirim, Tanju; Ghayesh, Mergen H.; Li, Weihua; Alici, Gursel
2016-01-01
Highlights: • A parametrically broadband energy harvester was fabricated. • Strong softening-type nonlinear behaviour was observed. • Experiments were conducted showing the large bandwidth of the device. - Abstract: An energy harvester has been designed, fabricated and tested based on the nonlinear dynamical response of a parametrically excited clamped-clamped beam with a central point-mass; magnets have been used as the central point-mass which pass through a coil when parametrically excited. Experiments have been conducted for the energy harvester when the system is excited (i) harmonically near the primary resonance; (ii) harmonically near the principal parametric resonance; (iii) by means of a non-smooth periodic excitation. An electrodynamic shaker was used to parametrically excite the system and the corresponding displacement of the magnet and output voltages of the coil were measured. It has been shown that the system displays linear behaviour at the primary resonance; however, at the principal parametric resonance, the motion characteristic of the magnet substantially changed displaying a strong softening-type nonlinearity. Theoretical simulations have also been conducted in order to verify the experimental results; the comparison between theory and experiment were within very good agreement of each other. The energy harvester developed in this paper is capable of harvesting energy close to the primary resonance as well as the principal parametric resonance; the frequency-band has been broadened significantly mainly due to the nonlinear effects as well as the parametric excitation.
Determinant of flexible Parametric Estimation of Mixture Cure ...
African Journals Online (AJOL)
PROF. OLIVER OSUAGWA
2015-12-01
Dec 1, 2015 ... derived from therapy. This study was intended at determining the flexible Parametric Cure Fraction. Model for Gastric cancer Data. Suitability of four parametric mixture cure models were considered namely; Log Normal (LN) cure fraction model, Log Logistic (LL) cure fraction model, Weibull (W) cure fraction ...
Spatiotemporal structures in the internally pumped optical parametric oscillator
DEFF Research Database (Denmark)
Lodahl, Peter; Bache, Morten; Saffman, Mark
2001-01-01
We analyze pattern formation in doubly resonant second-harmonic generation in the presence of a competing parametric process, also named the internally pumped optical parametric oscillator. Different scenarios are established where either the up- or down-conversion processes dominate...
Under what kind of parametric fluctuations is spatiotemporal ...
Indian Academy of Sciences (India)
Keeping the local dynamics always fully chaotic, we focus on parametric noise in the interaction pa- rameters between the nodes in the network. In particular .... where the parameter is kept constant at the mean value (C) give completely similar trends. As observed earlier, the spatial parametric fluctuations (S) give the small-.
Comparative Study of Parametric and Non-parametric Approaches in Fault Detection and Isolation
DEFF Research Database (Denmark)
Katebi, S.D.; Blanke, M.; Katebi, M.R.
This report describes a comparative study between two approaches to fault detection and isolation in dynamic systems. The first approach uses a parametric model of the system. The main components of such techniques are residual and signature generation for processing and analyzing. The second app...... algorithms employed are adopted from the template matching in pattern recognition. Extensive simulation studies are performed to demonstrate satisfactory performance of the proposed techniques. The advantages and disadvantages of each approach are discussed and analyzed....... approach is non-parametric in the sense that the signature analysis is only dependent on the frequency or time domain information extracted directly from the input-output signals. Based on these approaches, two different fault monitoring schemes are developed where the feature extraction and fault decision...
Structures of Ge15Sb x Se85- x chalcogenide glasses affect their Raman gain performance
Peng, Xuefeng; Dai, Shixun; Xu, Dong; Xu, Hang; Li, Xing; Lin, Changgui; Zhang, Peiqing; Xu, Tiefeng
2017-10-01
A series of Ge15Sb x Se85- x ( x = 5, 10, 15, 20, 25, and 30 mol%) chalcogenide glasses were prepared by traditional melt-quenching method. The refractive indexes, infrared transmissions, and spontaneous Raman spectra of the glass samples were measured. Based on the spontaneous Raman scattering theory and considering the measured Raman spectral data, we calculated the Raman gain coefficients of the chalcogenide glasses. The effect of Sb on the structures and Raman gain coefficients of the glass samples was then systematically investigated to understand the role of chemical composition in glass structure and Raman gain coefficient. In the Ge15Sb x Se85- x glasses, the number of heteropolar Ge-Se, Sb-Se bonds increased, whereas that of homopolar Se-Se bonds decreased at increased Sb concentration. The Raman gain coefficients increased until it reached a maximum value (290 × 10-13 m/W at Ge15Sb20Se65) and then decreased when the Sb concentration further increased. These results showed that the Raman gain coefficients of Ge-Sb-Se chalcogenide glasses without poisonous elements were over 300 times of that of commonly fused silica and closely correlated with the structures of the glasses, suggesting that the Raman gain coefficient can be adjusted by modifying the structures of the glasses. This work provides a new possibility for environment-friendly Raman fiber laser and amplifier materials.
Autonomous Supervision and Control of Parametric Roll Resonance
DEFF Research Database (Denmark)
Galeazzi, Roberto
therefore two objectives. The first is to develop methods for detection of the inception of parametric roll resonance. The second is to develop control strategies to stabilize the motion after parametric roll has started. Stabilisation of parametric roll resonance points to two possible courses of action...... strategies are then combined to stabilise parametric roll resonance within few roll cycles. Limitations on the maximum stabilisable roll angle are analysed and linked to the ii slew rate saturation and hydrodynamic stall characteristics of the fin stabilisers. The study on maximum stabilisable roll angle...... leads to the requirements for early detection. Two novel detectors are proposed, which work within a shorttime prediction horizon, and issue early warnings of parametric roll inception within few roll cycles from its onset. The main idea behind these detection schemes is that of exploiting the link...
Non-parametric approach to the study of phenotypic stability.
Ferreira, D F; Fernandes, S B; Bruzi, A T; Ramalho, M A P
2016-02-19
The aim of this study was to undertake the theoretical derivations of non-parametric methods, which use linear regressions based on rank order, for stability analyses. These methods were extension different parametric methods used for stability analyses and the result was compared with a standard non-parametric method. Intensive computational methods (e.g., bootstrap and permutation) were applied, and data from the plant-breeding program of the Biology Department of UFLA (Minas Gerais, Brazil) were used to illustrate and compare the tests. The non-parametric stability methods were effective for the evaluation of phenotypic stability. In the presence of variance heterogeneity, the non-parametric methods exhibited greater power of discrimination when determining the phenotypic stability of genotypes.
A gain-coefficient switched Alexandrite laser
International Nuclear Information System (INIS)
Lee, Chris J; Van der Slot, Peter J M; Boller, Klaus-J
2013-01-01
We report on a gain-coefficient switched Alexandrite laser. An electro-optic modulator is used to switch between high and low gain states by making use of the polarization dependent gain of Alexandrite. In gain-coefficient switched mode, the laser produces 85 ns pulses with a pulse energy of 240 mJ at a repetition rate of 5 Hz.
Estimating the potential gains from mergers
DEFF Research Database (Denmark)
Bogetoft, Peter; Wang, Dexiang
2005-01-01
We introduce simple production economic models to estimate the potential gains from mergers. We decompose the gains into technical ef¿ciency, size (scale) and harmony (mix) gains, and we discuss alternative ways to capture these gains. We propose to approximate the production processes using...
Understanding weight gain at menopause.
Davis, S R; Castelo-Branco, C; Chedraui, P; Lumsden, M A; Nappi, R E; Shah, D; Villaseca, P
2012-10-01
The aim of this review was to summarize the literature regarding the impact of the menopause transition on body weight and body composition. We conducted a search of the literature using Medline (Ovid, 1946-present) and PubMed (1966-2012) for English-language studies that included the following search terms: 'menopause', 'midlife', 'hormone therapy' or 'estrogen' combined with 'obesity', 'body weight' or 'body composition'. Whereas weight gain per se cannot be attributed to the menopause transition, the change in the hormonal milieu at menopause is associated with an increase in total body fat and an increase in abdominal fat. Weight excess at midlife is not only associated with a heightened risk of cardiovascular and metabolic disease, but also impacts adversely on health-related quality of life and sexual function. Animal and human studies indicate that this tendency towards central abdominal fat accumulation is ameliorated by estrogen therapy. Studies mostly indicate a reduction in overall fat mass with estrogen and estrogen-progestin therapy, improved insulin sensitivity and a lower rate of development of type 2 diabetes. The hormonal changes across the perimenopause substantially contribute to increased abdominal obesity which leads to additional physical and psychological morbidity. There is strong evidence that estrogen therapy may partly prevent this menopause-related change in body composition and the associated metabolic sequelae. However, further studies are required to identify the women most likely to gain metabolic benefit from menopausal hormone therapy in order to develop evidence-based clinical recommendations.
PISC II: Parametric studies. Monitoring of PISC-II parametric studies in ultrasonic NDT for PWR
International Nuclear Information System (INIS)
Toft, M.W.
1989-09-01
The CEGB NDT Applications Centre is partipating in the EEC-funded international Programme for the Inspection of Steel Components (PISC) on account of its relevance to the inspection of Sizewell B and future PWRs. This report describes an inspection monitoring exercise undertaken by NDTAC under partial funding from JRC Ispra, at the initiation of the PISC-III Ultrasonic Modelling Group. Experimental studies have been carried out under PISC-II to investigate ultrasonic defect response as a function of various parameters which characterise the inspection situation. Some of these parametric studies are potentially useful for the validation of theoretical models of ultrasonic inspection and are consequently relevant to the work of the PISC-III Modelling Group. The aim of the present exercise was to ensure that data obtained by the various contract organizations participating in the PISC-II Parametric Studies was of high quality, was a complete record of the inspection and would yield valid comparisons with the predictions of theoretical models. The exercise entailed visits by a nominated CEGB observer to 4 European NDT Laboratories at which the parametric studies were in progress; CISE (Milan); UKAEA (Harwell); UKAEA (Risley) and Vincotte (Brussels). This report presents the findings of those visits
Stabiliteit spontane taal bij chronische milde afasie
Wolthuis, Nienke; Mendez Orellana, Carolina; Nouwens, Femke; Jonkers, Roel; Visch-Brink, Evy; Bastiaanse, Roelien
2014-01-01
In aphasia, an analysis of spontaneous speech provides opportunities to establish the linguistic and communicative abilities, to create suitable therapy plans and to measure language progress. The current study investigated the stability of spontaneous speech within an interview of ten mild aphasic
Spontaneously broken abelian gauge invariant supersymmetric model
International Nuclear Information System (INIS)
Mainland, G.B.; Tanaka, K.
A model is presented that is invariant under an Abelian gauge transformation and a modified supersymmetry transformation. This model is broken spontaneously, and the interplay between symmetry breaking, Goldstone particles, and mass breaking is studied. In the present model, spontaneously breaking the Abelian symmetry of the vacuum restores the invariance of the vacuum under a modified supersymmetry transformation. (U.S.)
Spontaneous Achilles tendon rupture in alkaptonuria | Mohammed ...
African Journals Online (AJOL)
Spontaneous Achilles tendon ruptures are uncommon. We present a 46-year-old man with spontaneous Achilles tendon rupture due to ochronosis. To our knowledge, this has not been previously reported in Sudan literature. The tendon of the reported patient healed well after debridement and primary repairs.
Spontaneous rupture of choledochal cyst: case report
Energy Technology Data Exchange (ETDEWEB)
Shin, Ho Seob; Nam, Kyung Jin; Lee, Jin Hwa; Kim, Chan Sung; Choi, Jong Cheol; Oh, Jong Young [Dong-a University College of Medicine, Pusan (Korea, Republic of)
2002-11-01
Spontaneous rupture of a choledochal cyst leading to biliary peritonitis is a rare complication which can be fatal if not promptly diagnosed. The authors report the ultrasound and CT findings of two cases of spontaneous choledochal cystic rupture and the biliary peritonitis which ensued.
Spontaneity and Equilibrium II: Multireaction Systems
Raff, Lionel M.
2014-01-01
The thermodynamic criteria for spontaneity and equilibrium in multireaction systems are developed and discussed. When N reactions are occurring simultaneously, it is shown that G and A will depend upon N independent reaction coordinates, ?a (a = 1,2, ..., N), in addition to T and p for G or T and V for A. The general criteria for spontaneity and…
DEFF Research Database (Denmark)
Pouzet, B; Mow, T; Kreilgaard, Mads
2003-01-01
not inducing weight gain in clinic (haloperidol), on food and water intake and body weight gain in rats. We included both female and male rats in this study. To reduce spontaneous high food intake in rats, and to be able to evaluate the treatment effect on a potential increase of food intake or metabolic......Several clinical reports have demonstrated that most antipsychotics of the new generation, but not the typical antipsychotic haloperidol, induce weight gain in schizophrenic patients. Since weight gain induces serious health complications in humans, it is crucial to test upcoming antipsychotic...... compounds in an animal model of weight gain. With the aim of evaluating whether the rat can be used as a model for antipsychotic-induced weight gain, we have investigated the effect of chronic treatment (3 weeks) with one antipsychotic drug inducing weight gain in clinic (olanzapine) and one antipsychotic...
Early pregnancy angiogenic markers and spontaneous abortion
DEFF Research Database (Denmark)
Andersen, Louise B; Dechend, Ralf; Karumanchi, S Ananth
2016-01-01
BACKGROUND: Spontaneous abortion is the most commonly observed adverse pregnancy outcome. The angiogenic factors soluble Fms-like kinase 1 and placental growth factor are critical for normal pregnancy and may be associated to spontaneous abortion. OBJECTIVE: We investigated the association between...... maternal serum concentrations of soluble Fms-like kinase 1 and placental growth factor, and subsequent spontaneous abortion. STUDY DESIGN: In the prospective observational Odense Child Cohort, 1676 pregnant women donated serum in early pregnancy, gestational week ..., interquartile range 71-103). Concentrations of soluble Fms-like kinase 1 and placental growth factor were determined with novel automated assays. Spontaneous abortion was defined as complete or incomplete spontaneous abortion, missed abortion, or blighted ovum
The (perceived) meaning of spontaneous thoughts.
Morewedge, Carey K; Giblin, Colleen E; Norton, Michael I
2014-08-01
Spontaneous thoughts, the output of a broad category of uncontrolled and inaccessible higher order mental processes, arise frequently in everyday life. The seeming randomness by which spontaneous thoughts arise might give people good reason to dismiss them as meaningless. We suggest that it is precisely the lack of control over and access to the processes by which they arise that leads people to perceive spontaneous thoughts as revealing meaningful self-insight. Consequently, spontaneous thoughts potently influence judgment. A series of experiments provides evidence supporting two hypotheses. First, we hypothesize that the more a thought is perceived to be spontaneous, the more it is perceived to provide meaningful self-insight. Participants perceived more spontaneous kinds of thought (e.g., intuition) to reveal greater self-insight than did more controlled kinds of thought in Study 1 (e.g., deliberation). In Studies 2 and 3, participants perceived thoughts with the same content and target to reveal greater self-insight when spontaneously rather than deliberately generated (i.e., childhood memories and impressions formed). Second, we hypothesize that the greater self-insight attributed to thoughts that are (perceived to be) spontaneous leads those thoughts to more potently influence judgment. Participants felt more sexually attracted to an attractive person whom they thought of spontaneously than deliberately in Study 4, and reported their commitment to a current romantic relationship would be more affected by the spontaneous rather than deliberate recollection of a good or bad experience with their romantic partner in Study 5. PsycINFO Database Record (c) 2014 APA, all rights reserved.
Gain optimization method of a DQW superluminescent diode with broad multi-state emission
Dimas, Clara E.
2010-01-01
Optimizing gain through systematic methods of varying current injection schemes analytically is significant to maximize experimentally device yield and evaluation. Various techniques are used to calculate the amplified spontaneous emission (ASE) gain for light emitting devices consisting of single-section and multiple-sections of even length. Recently double quantum well (DQW) superluminescent diodes (SLD) have shown a broad multi-state emission due to mutlielectrodes of non-equal lengths and at high non-equal current densities. In this study, we adopt an improved method utilizing an ASE intensity ratio to calibrate a gain curve based on the sum of the measured ASE spectra to efficiently estimate the gain. Although the laser gain for GaAs/AlGaAs material is well studied, the ASE gain of SLD devices has not been systematically studied particular to further explain the multiple-state emission observed in fabricated devices. In addition a unique gain estimate was achieved where the excited state gain clamps prior to the ground state due to approaching saturation levels. In our results, high current densities in long sectioned active regions achieved sufficient un-truncated gain that show evidence of excited state emission has been observed.
Hastuti, S.; Harijono; Murtini, E. S.; Fibrianto, K.
2018-03-01
This current study is aimed to investigate the use of parametric and non-parametric approach for sensory RATA (Rate-All-That-Apply) method. Ledre as Bojonegoro unique local food product was used as point of interest, in which 319 panelists were involved in the study. The result showed that ledre is characterized as easy-crushed texture, sticky in mouth, stingy sensation and easy to swallow. It has also strong banana flavour with brown in colour. Compared to eggroll and semprong, ledre has more variances in terms of taste as well the roll length. As RATA questionnaire is designed to collect categorical data, non-parametric approach is the common statistical procedure. However, similar results were also obtained as parametric approach, regardless the fact of non-normal distributed data. Thus, it suggests that parametric approach can be applicable for consumer study with large number of respondents, even though it may not satisfy the assumption of ANOVA (Analysis of Variances).
Gain attenuation of gated framing camera
International Nuclear Information System (INIS)
Xiao Shali; Liu Shenye; Cao Zhurong; Li Hang; Zhang Haiying; Yuan Zheng; Wang Liwei
2009-01-01
The theoretic model of framing camera's gain attenuation is analyzed. The exponential attenuation curve of the gain along the pulse propagation time is simulated. An experiment to measure the coefficient of gain attenuation based on the gain attenuation theory is designed. Experiment result shows that the gain follows an exponential attenuation rule with a quotient of 0.0249 nm -1 , the attenuation coefficient of the pulse is 0.00356 mm -1 . The loss of the pulse propagation along the MCP stripline is the leading reason of gain attenuation. But in the figure of a single stripline, the gain dose not follow the rule of exponential attenuation completely, instead, there is a gain increase at the stripline bottom. That is caused by the reflection of the pulse. The reflectance is about 24.2%. Combining the experiment and theory, which design of the stripline MCP can improved the gain attenuation. (authors)
A soft double regularization approach to parametric blind image deconvolution.
Chen, Li; Yap, Kim-Hui
2005-05-01
This paper proposes a blind image deconvolution scheme based on soft integration of parametric blur structures. Conventional blind image deconvolution methods encounter a difficult dilemma of either imposing stringent and inflexible preconditions on the problem formulation or experiencing poor restoration results due to lack of information. This paper attempts to address this issue by assessing the relevance of parametric blur information, and incorporating the knowledge into the parametric double regularization (PDR) scheme. The PDR method assumes that the actual blur satisfies up to a certain degree of parametric structure, as there are many well-known parametric blurs in practical applications. Further, it can be tailored flexibly to include other blur types if some prior parametric knowledge of the blur is available. A manifold soft parametric modeling technique is proposed to generate the blur manifolds, and estimate the fuzzy blur structure. The PDR scheme involves the development of the meaningful cost function, the estimation of blur support and structure, and the optimization of the cost function. Experimental results show that it is effective in restoring degraded images under different environments.
Spontaneous Metacognition in Rhesus Monkeys.
Rosati, Alexandra G; Santos, Laurie R
2016-09-01
Metacognition is the ability to think about thinking. Although monitoring and controlling one's knowledge is a key feature of human cognition, its evolutionary origins are debated. In the current study, we examined whether rhesus monkeys (Macaca mulatta; N = 120) could make metacognitive inferences in a one-shot decision. Each monkey experienced one of four conditions, observing a human appearing to hide a food reward in an apparatus consisting of either one or two tubes. The monkeys tended to search the correct location when they observed this baiting event, but engaged in information seeking-by peering into a center location where they could check both potential hiding spots-if their view had been occluded and information seeking was possible. The monkeys only occasionally approached the center when information seeking was not possible. These results show that monkeys spontaneously use information about their own knowledge states to solve naturalistic foraging problems, and thus provide the first evidence that nonhumans exhibit information-seeking responses in situations with which they have no prior experience. © The Author(s) 2016.
Spontaneous flocking in human groups.
Belz, Michael; Pyritz, Lennart W; Boos, Margarete
2013-01-01
Flocking behaviour, as a type of self-organised collective behaviour, is described as the spatial formation of groups without global control and explicit inter-individual recruitment signals. It can be observed in many animals, such as bird flocks, shoals or herds of ungulates. Spatial attraction between humans as the central component of flocking behaviour has been simulated in a number of seminal models but it has not been detected experimentally in human groups so far. The two other sub-processes of this self-organised collective movement - collision avoidance and alignment - are excluded or held constant respectively in this study. We created a computer-based, multi-agent game where human players, represented as black dots, moved on a virtual playground. The participants were deprived of social cues about each other and could neither communicate verbally nor nonverbally. They played two games: (1) Single Game, where other players were invisible, and (2) Joint Game, where each player could see players' positions in a local radius around himself/herself. We found that individuals approached their neighbours spontaneously if their positions were visible, leading to less spatial dispersion of the whole group compared to moving alone. We conclude that human groups show the basic component of flocking behaviour without being explicitly instructed or rewarded to do so. Copyright © 2012 Elsevier B.V. All rights reserved.
Simultaneous bilateral primary spontaneous pneumothorax
Directory of Open Access Journals (Sweden)
Arife Zeybek
2014-04-01
Full Text Available Simultaneous bilateral primary pneumothorax is a very rare (1.6 / 100,000 and life-threatening condition. Clinical presentation may vary from mild dyspnea to tension pneumothorax. It may be milder particularly in younger patients, but more severe in patients with advanced age, and tube thoracostomy is a life preserver in the latter group. Since mortality and recurrence rates following tube thoracostomy are high, endoscopic approaches to bilateral hemithorax have been reported in literature. Apical wedge resection and pleural procedures are recommended in video thoracoscopy or mini thoracotomy even if no bulla and/or bleb are detected. Bilateral surgical interventions and additional pleural procedures are associated with increased rate of post-operative complications and longer postoperative hospital-stays. As a first-line approach, the surgical method toward any side of lung with air leakage following a previous tube thoracostomy is considered less invasive, especially in younger patients. Here, we present a case of simultaneous bilateral primary spontaneous pneumothorax (SBPSP in a 21-year old male with no history of smoking and chronic pulmonary disease. A unilateral surgical intervention was performed, and no recurrence was observed during 5-year follow up.
Bilateral spontaneous hemotympanum: Case report
Directory of Open Access Journals (Sweden)
Economou Nicolas C
2006-10-01
Full Text Available Abstract Background The most common causes of hemotympanum are therapeutic nasal packing, epistaxis, blood disorders and blunt trauma to the head. Hemotympanum is characterized as idiopathic, when it is detected in the presence of chronic otitis media. A rare case of spontaneous bilateral hemotympanum in a patient treated with anticoagulants is presented herein. Case presentation A 72-year-old male presented with acute deterioration of hearing. In the patient's medical history aortic valve replacement 1 year before presentation was reported. Since then he had been administered regularly coumarinic anticoagulants, with INR levels maintained between 3.4 and 4.0. Otoscopy revealed the presence of bilateral hemotympanum. The audiogram showed symmetrical moderately severe mixed hearing loss bilaterally, with the conductive component predominating. Tympanograms were flat bilaterally with absent acoustic reflexes. A computerized tomography scan showed the presence of fluid in the mastoid and middle ear bilaterally. Treatment was conservative and consisted of a 10-day course of antibiotics, anticongestants and temporary interruption of the anticoagulant therapy. After 3 weeks, normal tympanic membranes were found and hearing had returned to previous levels. Conclusion Anticoagulant intake should be included in the differential diagnosis of hemotympanum, because its detection and appropriate treatment may lead to resolution of the disorder.
Fares, H.; Piovella, N.; Robb, G. R. M.
2018-01-01
We study the spontaneous emission in high-gain free-electron lasers operating in the quantum regime and its detrimental effect on coherent emission. A quantum model describing the coherent and spontaneous emission in free electron lasers has been recently proposed and investigated [G. R. M. Robb and R. Bonifacio, Phys. Plasmas 19, 073101 (2012)]. The model is based on a Wigner distribution describing the electron beam dynamics, coupled to Maxwell equations for the emitted radiation field. Here, we rephrase the model in a more rigorous way, considering a discrete Wigner distribution defined for a periodic space coordinate for which the electron momentum is discrete. From its numerical solution, we find good agreement with the approximate continuous model. In the quantum regime of the free-electron laser, we obtain a simple density matrix equation for two momentum states, where the role of the spontaneous emission has a clear interpretation in terms of coherence decay and population transfer.
DEFF Research Database (Denmark)
Jedrkiewicz, O.; Brambilla, E.; Bache, Morten
2006-01-01
demonstrate that the peak value of the normalized spatial correlations between signal and idler lies well above the line marking the boundary between the classical and the quantum domain. This effect is equivalent to the apparent violation of the Cauchy-Schwartz inequality, predicted by some of us years ago...
Parametric resonance induced chaos in magnetic damped driven pendulum
Energy Technology Data Exchange (ETDEWEB)
Khomeriki, Giorgi, E-mail: giokhomeriki123@gmail.com
2016-07-15
A damped driven pendulum with a magnetic driving force, appearing from a solenoid, where ac current flows is considered. The solenoid acts on the magnet, which is located at a free end of the pendulum. In this system the existence and interrelation of chaos and parametric resonance is theoretically examined. Derived analytical results are supported by numerical simulations and conducted experiments. - Highlights: • A damped magnetic pendulum is considered driven by off resonant magnetic field. • Our system is chaotic only when the conditions for parametric resonance are fulfilled. • Conducted experiments give a good agreement with theory and numerical simulations. • Calculated Lyapunov exponents are compared with parametric instability growth rates.
Parametric resonance and cooling on an atom chip
International Nuclear Information System (INIS)
Yan Bo; Li Xiaolin; Ke Min; Wang Yuzhu
2008-01-01
This paper observes the parametric excitation on atom chip by measuring the trap loss when applying a parametric modulation. By modulating the current in chip wires, it modulates not only the trap frequency but also the trap position. It shows that the strongest resonance occurs when the modulation frequency equals to the trap frequency. The resonance amplitude increases exponentially with modulation depth. Because the Z-trap is an anharmonic trap, there exists energy selective excitation which would cause parametric cooling. We confirm this effect by observing the temperature of atom cloud dropping
The parametric manifold picture of space-time
International Nuclear Information System (INIS)
Perjes, Z.
1992-03-01
Parametric manifolds are reparametrization-invariant geometric structures describing space-time and internal degrees of freedom in a unified framework. Using the theory of parametric spinors, a decomposition of the space-time in General Relativity is developed with respect to the 3-space of trajectories of a time-like or space-like vector field. The parametric 3+1 decomposition surpasses the ADM formalism in generality since it is possible even in space-times which do not admit a space-like foliation. (author) 33 refs
Nonlinear cross-talk mitigation in polychromatic parametric sampling gate.
Ataie, Vahid; Wiberg, Andreas O J; Alic, Nikola; Radic, Stojan
2013-02-25
New technique for cancellation of nonlinear cross-talk in polychromatic parametric sampling gate is described and quantified. The method relies on a newly derived look-up table method that achieves equalization and suppresses nonlinear response associated with parametric sampling operation. The new cancellation scheme is implemented in a framework of a specific parametric photonics assisted analog-to-digital conversion (ADC) copy-and-sample-all (CaSA) architecture. A 20 dB improvement in total harmonic distortion is demonstrated experimentally.
Parametric Design of Outdoor Broadcasting Studio Based on Schema Theory
Directory of Open Access Journals (Sweden)
Zhu Li
2016-01-01
Full Text Available This paper mainly demonstrates that the schema is an important way for the architect to cognize architecture form logic. It connects schema to algorithm of parametric design in order to seek the “algorithm schema” generation in parametric design of architecture. Meanwhile, this paper discusses the generative process and methods of the “algorithm schema” in parametric design of architecture by describing a case of outdoor broadcasting studio of Hunan Economic Radio. It also reveals the importance of “algorithm schema” for the cognition and architectural form logic generation.
Stochastic parametric resonance in shear flows
Directory of Open Access Journals (Sweden)
F. J. Poulin
2005-01-01
Full Text Available Time-periodic shear flows can give rise to Parametric Instability (PI, as in the case of the Mathieu equation (Stoker, 1950; Nayfeh and Mook, 1995. This mechanism results from a resonance between the oscillatory basic state and waves that are superimposed on it. Farrell and Ioannou (1996a, b explain that PI occurs because the snap-shots of the velocity profile are subject to transient growth. If the flows were purely steady the transient growth would subside and not have any long lasting effect. However, the coupling between transient growth and the time variation of the basic state create PI. Mathematically, transient growth, and therefore PI, are due to the nonorthogonal eigenspace in the linearized system. Poulin et al. (2003 studied a time-periodic barotropic shear flow that exhibited PI, and thereby produced mixing at the interface between Potential Vorticity (PV fronts. The instability led to the formation of vortices that were stretched. A later study of an oscillatory current in the Cape Cod Bay illustrated that PI can occur in realistic shear flows (Poulin and Flierl, 2005. These studies assumed that the basic state was periodic with a constant frequency and amplitude. In this work we study a shear flow similar to that found in Poulin et al. (2003, but now where the magnitude of vorticity is a stochastic variable. We determine that in the case of stochastic shear flows the transient growth of perturbations of the snapshots of the basic state still generate PI.
Multidimensional Scaling Visualization Using Parametric Similarity Indices
Directory of Open Access Journals (Sweden)
J. A. Tenreiro Machado
2015-03-01
Full Text Available In this paper, we apply multidimensional scaling (MDS and parametric similarity indices (PSI in the analysis of complex systems (CS. Each CS is viewed as a dynamical system, exhibiting an output time-series to be interpreted as a manifestation of its behavior. We start by adopting a sliding window to sample the original data into several consecutive time periods. Second, we define a given PSI for tracking pieces of data. We then compare the windows for different values of the parameter, and we generate the corresponding MDS maps of ‘points’. Third, we use Procrustes analysis to linearly transform the MDS charts for maximum superposition and to build a globalMDS map of “shapes”. This final plot captures the time evolution of the phenomena and is sensitive to the PSI adopted. The generalized correlation, theMinkowski distance and four entropy-based indices are tested. The proposed approach is applied to the Dow Jones Industrial Average stock market index and the Europe Brent Spot Price FOB time-series.
Parametric Testing of Launch Vehicle FDDR Models
Schumann, Johann; Bajwa, Anupa; Berg, Peter; Thirumalainambi, Rajkumar
2011-01-01
For the safe operation of a complex system like a (manned) launch vehicle, real-time information about the state of the system and potential faults is extremely important. The on-board FDDR (Failure Detection, Diagnostics, and Response) system is a software system to detect and identify failures, provide real-time diagnostics, and to initiate fault recovery and mitigation. The ERIS (Evaluation of Rocket Integrated Subsystems) failure simulation is a unified Matlab/Simulink model of the Ares I Launch Vehicle with modular, hierarchical subsystems and components. With this model, the nominal flight performance characteristics can be studied. Additionally, failures can be injected to see their effects on vehicle state and on vehicle behavior. A comprehensive test and analysis of such a complicated model is virtually impossible. In this paper, we will describe, how parametric testing (PT) can be used to support testing and analysis of the ERIS failure simulation. PT uses a combination of Monte Carlo techniques with n-factor combinatorial exploration to generate a small, yet comprehensive set of parameters for the test runs. For the analysis of the high-dimensional simulation data, we are using multivariate clustering to automatically find structure in this high-dimensional data space. Our tools can generate detailed HTML reports that facilitate the analysis.
Selected Parametric Effects on Materials Flammability Limits
Hirsch, David B.; Juarez, Alfredo; Peyton, Gary J.; Harper, Susana A.; Olson, Sandra L.
2011-01-01
NASA-STD-(I)-6001B Test 1 is currently used to evaluate the flammability of materials intended for use in habitable environments of U.S. spacecraft. The method is a pass/fail upward flame propagation test conducted in the worst case configuration, which is defined as a combination of a material s thickness, test pressure, oxygen concentration, and temperature that make the material most flammable. Although simple parametric effects may be intuitive (such as increasing oxygen concentrations resulting in increased flammability), combinations of multi-parameter effects could be more complex. In addition, there are a variety of material configurations used in spacecraft. Such configurations could include, for example, exposed free edges where fire propagation may be different when compared to configurations commonly employed in standard testing. Studies involving combined oxygen concentration, pressure, and temperature on flammability limits have been conducted and are summarized in this paper. Additional effects on flammability limits of a material s thickness, mode of ignition, burn-length criteria, and exposed edges are presented. The information obtained will allow proper selection of ground flammability test conditions, support further studies comparing flammability in 1-g with microgravity and reduced gravity environments, and contribute to persuasive scientific cases for rigorous space system fire risk assessments.
Parametric probability distributions for anomalous change detection
Energy Technology Data Exchange (ETDEWEB)
Theiler, James P [Los Alamos National Laboratory; Foy, Bernard R [Los Alamos National Laboratory; Wohlberg, Brendt E [Los Alamos National Laboratory; Scovel, James C [Los Alamos National Laboratory
2010-01-01
The problem of anomalous change detection arises when two (or possibly more) images are taken of the same scene, but at different times. The aim is to discount the 'pervasive differences' that occur thoughout the imagery, due to the inevitably different conditions under which the images were taken (caused, for instance, by differences in illumination, atmospheric conditions, sensor calibration, or misregistration), and to focus instead on the 'anomalous changes' that actually take place in the scene. In general, anomalous change detection algorithms attempt to model these normal or pervasive differences, based on data taken directly from the imagery, and then identify as anomalous those pixels for which the model does not hold. For many algorithms, these models are expressed in terms of probability distributions, and there is a class of such algorithms that assume the distributions are Gaussian. By considering a broader class of distributions, however, a new class of anomalous change detection algorithms can be developed. We consider several parametric families of such distributions, derive the associated change detection algorithms, and compare the performance with standard algorithms that are based on Gaussian distributions. We find that it is often possible to significantly outperform these standard algorithms, even using relatively simple non-Gaussian models.
Supercritical extraction of oleaginous: parametric sensitivity analysis
Directory of Open Access Journals (Sweden)
Santos M.M.
2000-01-01
Full Text Available The economy has become universal and competitive, thus the industries of vegetable oil extraction must advance in the sense of minimising production costs and, at the same time, generating products that obey more rigorous patterns of quality, including solutions that do not damage the environment. The conventional oilseed processing uses hexane as solvent. However, this solvent is toxic and highly flammable. Thus the search of substitutes for hexane in oleaginous extraction process has increased in the last years. The supercritical carbon dioxide is a potential substitute for hexane, but it is necessary more detailed studies to understand the phenomena taking place in such process. Thus, in this work a diffusive model for semi-continuous (batch for the solids and continuous for the solvent isothermal and isobaric extraction process using supercritical carbon dioxide is presented and submitted to a parametric sensitivity analysis by means of a factorial design in two levels. The model parameters were disturbed and their main effects analysed, so that it is possible to propose strategies for high performance operation.
Parametric Design in Timber Gridshell Tectonics
Directory of Open Access Journals (Sweden)
Ismailiyah Al Athas Syarifah
2018-01-01
Full Text Available This paper begins with a simple proposition: rather than mimicking the geometric structures found in nature, perhaps the most effective modes of sustainable fabrication can be found throughunderstanding the nature of materials themselves. The material becomes a design parameter through the constraints of fabrication tools, limitations of material size, and most importantly the productivecapacity of material resistance a given material’s capacity and tendencies to take shape, rather than cutting shape out of material. Gridshell structures provide an intriguing case study to pursue this proposition. Not only is there clear precedent in the form finding experiments of frei Otto and the institute for lightweight structures, but also the very nurbs based tools of current design practices developed from the ability of wood to bend. Taking the bent wood spline quite literally, gridshells provide a means that is at once formally expressive, structurally optimized, materially efficient, and quite simply a delight to experience. The the larger motivation of this work anticipates a parametric system linking the intrinsic material values of the gridshell tectonic with extrinsic criteria such as programmatic needs and environmental response. Through an applied case study of gridshells, the play between form and material is tested out through the author’s own experimentation with gridshells and the pedagogical results of two gridshell studios.The goal of this research is to establish a give and take relationship between top down formal emphasis and a bottom-up material influence.
A scale invariance criterion for LES parametrizations
Directory of Open Access Journals (Sweden)
Urs Schaefer-Rolffs
2015-01-01
Full Text Available Turbulent kinetic energy cascades in fluid dynamical systems are usually characterized by scale invariance. However, representations of subgrid scales in large eddy simulations do not necessarily fulfill this constraint. So far, scale invariance has been considered in the context of isotropic, incompressible, and three-dimensional turbulence. In the present paper, the theory is extended to compressible flows that obey the hydrostatic approximation, as well as to corresponding subgrid-scale parametrizations. A criterion is presented to check if the symmetries of the governing equations are correctly translated into the equations used in numerical models. By applying scaling transformations to the model equations, relations between the scaling factors are obtained by demanding that the mathematical structure of the equations does not change.The criterion is validated by recovering the breakdown of scale invariance in the classical Smagorinsky model and confirming scale invariance for the Dynamic Smagorinsky Model. The criterion also shows that the compressible continuity equation is intrinsically scale-invariant. The criterion also proves that a scale-invariant turbulent kinetic energy equation or a scale-invariant equation of motion for a passive tracer is obtained only with a dynamic mixing length. For large-scale atmospheric flows governed by the hydrostatic balance the energy cascade is due to horizontal advection and the vertical length scale exhibits a scaling behaviour that is different from that derived for horizontal length scales.
Function parametrization by using 4-point transforms
International Nuclear Information System (INIS)
Dikusar, N.D.
1996-01-01
A continuous parametrization of the smooth curve f(x)=f(x;R) is suggested on a basis of four-point transformations. Coordinates of three reference points of the curve are chosen as parameters R. This approach allows to derive a number of advantages in function approximation and fitting of empiric data. The transformations have made possible to derive a new class of polynomials (monosplines) having the better approximation quality than monomials {x n }. A behaviour of an error of the approximation has a uniform character. A three-point model of the cubic spline (TPS) is proposed. The model allows to reduce a number of unknown parameters in twice and to obtain an advantage in a computing aspect. The new approach to the function approximation and fitting are shown on a number of examples. The proposed approach gives a new mathematical tool and a new possibility in both practical applications and theoretical research of numerical and computational methods. 13 refs., 13 figs., 2 tabs
Parametric investigation of scalable tactile sensors
Saadatzi, Mohammad Nasser; Yang, Zhong; Baptist, Joshua R.; Sahasrabuddhe, Ritvij R.; Wijayasinghe, Indika B.; Popa, Dan O.
2017-05-01
In the near future, robots and humans will share the same environment and perform tasks cooperatively. For intuitive, safe, and reliable physical human-robot interaction (pHRI), sensorized robot skins for tactile measurements of contact are necessary. In a previous study, we presented skins consisting of strain gauge arrays encased in silicone encapsulants. Although these structures could measure normal forces applied directly onto the sensing elements, they also exhibited blind spots and response asymmetry to certain loading patterns. This study presents a parametric investigation of piezoresistive polymeric strain gauge that exhibits a symmetric omniaxial response thanks to its novel star-shaped structure. This strain gauge relies on the use of gold micro-patterned star-shaped structures with a thin layer of PEDOT:PSS which is a flexible polymer with piezoresistive properties. In this paper, the sensor is first modeled and comprehensively analyzed in the finite-element simulation environment COMSOL. Simulations include stress-strain loading for a variety of structure parameters such as gauge lengths, widths, and spacing, as well as multiple load locations relative to the gauge. Subsequently, sensors with optimized configurations obtained through simulations were fabricated using cleanroom photolithographic and spin-coating processes, and then experimentally tested. Results show a trend-wise agreement between experiments and simulations.
Temporal Simultons in Optical Parametric Oscillators.
Jankowski, Marc; Marandi, Alireza; Phillips, C R; Hamerly, Ryan; Ingold, Kirk A; Byer, Robert L; Fejer, M M
2018-02-02
We report the first demonstration of a regime of operation in optical parametric oscillators (OPOs), in which the formation of temporal simultons produces stable femtosecond half-harmonic pulses. Simultons are simultaneous bright-dark solitons of a signal field at frequency ω and the pump field at 2ω, which form in a quadratic nonlinear medium. The formation of simultons in an OPO is due to the interplay of nonlinear pulse acceleration with the timing mismatch between the pump repetition period and the cold-cavity round-trip time and is evidenced by sech^{2} spectra with broad instantaneous bandwidths when the resonator is detuned to a slightly longer round-trip time than the pump repetition period. We provide a theoretical description of an OPO operating in a regime dominated by these dynamics, observe the distinct features of simulton formation in an experiment, and verify our results with numerical simulations. These results represent a new regime of operation in nonlinear resonators, which can lead to efficient and scalable sources of few-cycle frequency combs at arbitrary wavelengths.
Parametric approach to linear induction accelerator design
International Nuclear Information System (INIS)
Bresie, D.A.; Andrews, J.A.; Ingram, S.W.
1991-01-01
Past work on the design of linear induction accelerators has centered on the development of computer codes to analyze accelerator designs, using the current filament method. While these filament models are a very valuable tool for evaluating the performance of an induction launcher design, they provide little insight into the selection of dimensions, materials, and operation points for accelerators with interesting performance. Described in this paper is a parametric approach to defining effective accelerator designs. This method uses a computer optimization routine to iteratively seek out effective designs. The optimization routine is forced to search within a parameter space restricted to interesting and realistic parameters such as size, weight, voltage, and temperature rises. A filament model is used as the filter for the optimizer. Several linear induction accelerators have been designed using this method. The accelerators designed all used a switched capacitor power supply. While the run time of this code on The University of Texas' CRAY XMP-24 computer is moderately long, the resulting designs have good predicted performance. With realistic power supplies and materials, accelerator efficiencies in the 20 to 40% range were easily obtained. This paper describes the effect of armature diameter, length-to-diameter ratio, and weight, as well as other parameters, on the optimum accelerator design
Parametric Cost Analysis: A Design Function
Dean, Edwin B.
1989-01-01
Parametric cost analysis uses equations to map measurable system attributes into cost. The measures of the system attributes are called metrics. The equations are called cost estimating relationships (CER's), and are obtained by the analysis of cost and technical metric data of products analogous to those to be estimated. Examples of system metrics include mass, power, failure_rate, mean_time_to_repair, energy _consumed, payload_to_orbit, pointing_accuracy, manufacturing_complexity, number_of_fasteners, and percent_of_electronics_weight. The basic assumption is that a measurable relationship exists between system attributes and the cost of the system. If a function exists, the attributes are cost drivers. Candidates for metrics include system requirement metrics and engineering process metrics. Requirements are constraints on the engineering process. From optimization theory we know that any active constraint generates cost by not permitting full optimization of the objective. Thus, requirements are cost drivers. Engineering processes reflect a projection of the requirements onto the corporate culture, engineering technology, and system technology. Engineering processes are an indirect measure of the requirements and, hence, are cost drivers.
Improvement of Statistical Decisions under Parametric Uncertainty
Nechval, Nicholas A.; Nechval, Konstantin N.; Purgailis, Maris; Berzins, Gundars; Rozevskis, Uldis
2011-10-01
A large number of problems in production planning and scheduling, location, transportation, finance, and engineering design require that decisions be made in the presence of uncertainty. Decision-making under uncertainty is a central problem in statistical inference, and has been formally studied in virtually all approaches to inference. The aim of the present paper is to show how the invariant embedding technique, the idea of which belongs to the authors, may be employed in the particular case of finding the improved statistical decisions under parametric uncertainty. This technique represents a simple and computationally attractive statistical method based on the constructive use of the invariance principle in mathematical statistics. Unlike the Bayesian approach, an invariant embedding technique is independent of the choice of priors. It allows one to eliminate unknown parameters from the problem and to find the best invariant decision rule, which has smaller risk than any of the well-known decision rules. To illustrate the proposed technique, application examples are given.
Circular polarization with crossed-planar undulators in high-gain FELs
Kim, K J K J
2000-01-01
We propose a crossed undulator configuration for a high-gain free-electron laser to allow versatile polarization control. This configuration consists of a long (saturation length) planar undulator, a dispersive section, and a short (a few gain lengths) planar undulator oriented perpendicular to the first one. In the first undulator, a radiation component linearly polarized in the x-direction is amplified to saturation. In the second undulator, the x-polarized component propagates freely, while a new component, polarized in the y-direction, is generated and reaches saturation in a few gain lengths. By adjusting the strength of the dispersive section, the relative phase of two radiation components can be adjusted to obtain a suitable polarization for the total radiation field, including the circular polarization. The operating principle of the high-gain crossed undulator, which is quite different from that of the crossed undulator for spontaneous radiation, is illustrated in terms of 1-D FEL theory.
Clock frequency estimation under spontaneous emission
Qin, Xi-Zhou; Huang, Jia-Hao; Zhong, Hong-Hua; Lee, Chaohong
2018-02-01
We investigate the quantum dynamics of a driven two-level system under spontaneous emission and its application in clock frequency estimation. By using the Lindblad equation to describe the system, we analytically obtain its exact solutions, which show three different regimes: Rabi oscillation, damped oscillation, and overdamped decay. From the analytical solutions, we explore how the spontaneous emission affects the clock frequency estimation. We find that under a moderate spontaneous emission rate, the transition frequency can still be inferred from the Rabi oscillation. Our results enable potential practical applications in frequency measurement and quantum control under decoherence.