WorldWideScience
 
 
1

Time response of fast-gated microchannel plates used as x-ray detectors  

International Nuclear Information System (INIS)

We report measurements of the time response of fast-gated, micro- channel plate (MCP) detectors, using a <10 ps pulsewidth ultra-violet laser and an electronic sampling system to measure time resolutions to better than 25 ps. The results show that framing times of less than 100 ps are attainable with high gain. The data is compared to a Monte Carlo calculation, which shows good agreement. We also measured the relative sensitivity as a function of DC bias, and saturation effects for large signal inputs. In part B, we briefly describe an electrical ''time-of-flight'' technique, which we have used to measure the response time of a fast-gated microchannel plate (MCP). Thinner MCP's than previously used have been tested, and, as expected, show fast gating times and smaller electron multiplication. A preliminary design for an x-ray pinhole camera, using a thin MCP, is presented. 7 refs., 6 figs

2

Wide dynamic range neutron flux monitor having fast time response for the Large Helical Device  

International Nuclear Information System (INIS)

A fast time response, wide dynamic range neutron flux monitor has been developed toward the LHD deuterium operation by using leading-edge signal processing technologies providing maximum counting rate up to ?5 × 109 counts/s. Because a maximum total neutron emission rate over 1 × 1016 n/s is predicted in neutral beam-heated LHD plasmas, fast response and wide dynamic range capabilities of the system are essential. Preliminary tests have demonstrated successful performance as a wide dynamic range monitor along the design

3

Ultra-Fast Flash Observatory: Fast Response Space Missions for Early Time Phase of Gamma Ray Bursts  

DEFF Research Database (Denmark)

One of the unexplored domains in the study of gamma-ray bursts (GRBs) is the early time phase of the optical light curve. We have proposed Ultra-Fast Flash Observatory (UFFO) to address this question through extraordinary opportunities presented by a series of small space missions. The UFFO is equipped with a fast-response Slewing Mirror Telescope that uses a rapidly moving mirror or mirror array to redirect the optical beam rather than slewing the entire spacecraft or telescope to aim the optical instrument at the GRB position. The UFFO will probe the early optical rise of GRBs with sub-second response, for the first time, opening a completely new frontier in GRB and transient studies. Its fast response measurements of the optical emission of dozens of GRB each year will provide unique probes of the burst mechanism and test the prospect of GRB as a new standard candle, potentially opening up the z > 10 universe. We describe the current limit in early photon measurements, the aspects of early photon physics, our soon-to-be-launched UFFO-pathfinder mission, and our next planned mission, the UFFO-100.

Park, I.H.; Ahmad, S.

2013-01-01

4

Timing and position response of a block detector for fast neutron time-of-flight imaging  

Science.gov (United States)

Our research effort seeks to improve the spatial and timing performance of a block detector made of a pixilated plastic scintillator (EJ-200), first demonstrated as part of Oak Ridge National Laboratory's Advanced Portable Neutron Imaging System. Improvement of the position and time response is necessary to achieve better resolution and contrast in the images of shielded special nuclear material. Time-of-flight is used to differentiate between gamma and different sources of neutrons (e.g., transmission and fission neutrons). Factors limiting the timing and position performance of the neutron detector have been revealed through simulations and measurements. Simulations have suggested that the degradation in the ability to resolve pixels in the neutron detector is due to those interactions occurring near the light guide. The energy deposition within the neutron detector is shown to affect position performance and imaging efficiency. This examination details how energy cuts improve the position performance and degrade the imaging efficiency. Measurements have shown the neutron detector to have a timing resolution of ?=238 ps. The majority of this timing uncertainty is from the depth-of-interaction (DOI) of the neutron which is confirmed by simulations and analytical calculations.

Laubach, M. A.; Hayward, J. P.; Zhang, X.; Cates, J. W.

2014-11-01

5

Characterizing a fast-response, low-afterglow liquid scintillator for neutron time-of-flight diagnostics in fast ignition experiments  

Energy Technology Data Exchange (ETDEWEB)

The characteristics of oxygen-enriched liquid scintillators with very low afterglow are investigated and optimized for application to a single-hit neutron spectrometer for fast ignition experiments. It is found that 1,2,4-trimethylbenzene has better characteristics as a liquid scintillator solvent than the conventional solvent, p-xylene. In addition, a benzophenon-doped BBQ liquid scintillator is shown to demonstrate very rapid time response, and therefore has potential for further use in neutron diagnostics with fast time resolution.

Abe, Y., E-mail: abe-y@ile.osaka-u.ac.jp; Hosoda, H.; Arikawa, Y.; Nagai, T.; Kojima, S.; Sakata, S.; Inoue, H.; Iwasa, Y.; Iwano, K.; Yamanoi, K.; Fujioka, S.; Nakai, M.; Sarukura, N.; Shiraga, H.; Norimatsu, T.; Azechi, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan)

2014-11-15

6

Characterizing a fast-response, low-afterglow liquid scintillator for neutron time-of-flight diagnostics in fast ignition experiments.  

Science.gov (United States)

The characteristics of oxygen-enriched liquid scintillators with very low afterglow are investigated and optimized for application to a single-hit neutron spectrometer for fast ignition experiments. It is found that 1,2,4-trimethylbenzene has better characteristics as a liquid scintillator solvent than the conventional solvent, p-xylene. In addition, a benzophenon-doped BBQ liquid scintillator is shown to demonstrate very rapid time response, and therefore has potential for further use in neutron diagnostics with fast time resolution. PMID:25430305

Abe, Y; Hosoda, H; Arikawa, Y; Nagai, T; Kojima, S; Sakata, S; Inoue, H; Iwasa, Y; Iwano, K; Yamanoi, K; Fujioka, S; Nakai, M; Sarukura, N; Shiraga, H; Norimatsu, T; Azechi, H

2014-11-01

7

Characterizing a fast-response, low-afterglow liquid scintillator for neutron time-of-flight diagnostics in fast ignition experimentsa)  

Science.gov (United States)

The characteristics of oxygen-enriched liquid scintillators with very low afterglow are investigated and optimized for application to a single-hit neutron spectrometer for fast ignition experiments. It is found that 1,2,4-trimethylbenzene has better characteristics as a liquid scintillator solvent than the conventional solvent, p-xylene. In addition, a benzophenon-doped BBQ liquid scintillator is shown to demonstrate very rapid time response, and therefore has potential for further use in neutron diagnostics with fast time resolution.

Abe, Y.; Hosoda, H.; Arikawa, Y.; Nagai, T.; Kojima, S.; Sakata, S.; Inoue, H.; Iwasa, Y.; Iwano, K.; Yamanoi, K.; Fujioka, S.; Nakai, M.; Sarukura, N.; Shiraga, H.; Norimatsu, T.; Azechi, H.

2014-11-01

8

Characterizing a fast-response, low-afterglow liquid scintillator for neutron time-of-flight diagnostics in fast ignition experiments  

International Nuclear Information System (INIS)

The characteristics of oxygen-enriched liquid scintillators with very low afterglow are investigated and optimized for application to a single-hit neutron spectrometer for fast ignition experiments. It is found that 1,2,4-trimethylbenzene has better characteristics as a liquid scintillator solvent than the conventional solvent, p-xylene. In addition, a benzophenon-doped BBQ liquid scintillator is shown to demonstrate very rapid time response, and therefore has potential for further use in neutron diagnostics with fast time resolution

9

Fast timing discriminator  

International Nuclear Information System (INIS)

The processing of pulses with very fast risetimes for timing purposes involves many problems because of the large equivalent bandwidths involved. For pulses with risetimes in the 150 ps range (and full widths at half maximum (FWHM) of 400 ps) bandwidths in excess of 1GHz are required. Furthermore, these very narrow pulses with current amplitudes as small as 1 mA carry very small charges (-12 coulomb), therefore, requiring very sensitive trigger circuits. The difficulty increases when timing characteristics in the picosecond range are sought especially when a wide input signal amplitude range causes a time-walk problem. The fast timing discriminator described has a time-walk of approximately +-75 ps over the input signal range from 80 mV to 3V. A schematic of the discriminator is included, and operation and performance are discussed

10

Fast timing discriminator  

Energy Technology Data Exchange (ETDEWEB)

The processing of pulses with very fast risetimes for timing purposes involves many problems because of the large equivalent bandwidths involved. For pulses with risetimes in the 150 ps range (and full widths at half maximum (FWHM) of 400 ps) bandwidths in excess of 1GHz are required. Furthermore, these very narrow pulses with current amplitudes as small as 1 mA carry very small charges (<10/sup -12/ coulomb), therefore, requiring very sensitive trigger circuits. The difficulty increases when timing characteristics in the picosecond range are sought especially when a wide input signal amplitude range causes a time-walk problem. The fast timing discriminator described has a time-walk of approximately +-75 ps over the input signal range from 80 mV to 3V. A schematic of the discriminator is included, and operation and performance are discussed.

Lo, C.C.

1977-07-11

11

Enhanced surface anchoring energy for the photo-alignment layer with reactive mesogens for fast response time of liquid crystal displays  

International Nuclear Information System (INIS)

We propose a method for enhancing the surface anchoring energy in photo-alignment (PA) through a two-step ultraviolet (UV) exposure process using reactive mesogens (RM) for fast response time characteristics of liquid crystal displays. We establish the azimuthal alignment direction through the first linearly polarized UV exposure process, as the conventional PA method does. We then achieve the stable alignment and strong surface anchoring energies of our method through the second unpolarized UV exposure process, which polymerizes the RM monomers within the vertical alignment layer. As a result, the fast response time characteristics are remarkably improved, and thermal stability is obtained. (paper)

12

Enhanced surface anchoring energy for the photo-alignment layer with reactive mesogens for fast response time of liquid crystal displays  

Science.gov (United States)

We propose a method for enhancing the surface anchoring energy in photo-alignment (PA) through a two-step ultraviolet (UV) exposure process using reactive mesogens (RM) for fast response time characteristics of liquid crystal displays. We establish the azimuthal alignment direction through the first linearly polarized UV exposure process, as the conventional PA method does. We then achieve the stable alignment and strong surface anchoring energies of our method through the second unpolarized UV exposure process, which polymerizes the RM monomers within the vertical alignment layer. As a result, the fast response time characteristics are remarkably improved, and thermal stability is obtained.

Lee, You-Jin; Baek, Ji-Ho; Kim, Youngsik; Heo, Jung Uk; Yu, Chang-Jae; Kim, Jae-Hoon

2013-04-01

13

A cryogenic fast response thermometer  

Science.gov (United States)

Multipurpose carbon thin film resistance thermometers have been developed for cryogenic use. Carbon was electron beam evaporated onto polycrystalline alumina substrates with copper films as electrical contacts. The thermometers were coated with thin glass layers. The desired electrical resistance of the sensors was obtained with a final heat treatment. Their sensitivity at 4.2 K is approximately 300 ? K -1. Between 4.2 and 20 K the film resistance can be expressed as a function of temperature by a usual correlation of the form In R = A0 + A1T + A2 ( InT) 2. These sensors have been developed as separate devices to be soldered or glued onto experiments. Nevertheless, their response is fast; at 4.2 K their thermal relaxation time is better than 1 ms and their thermal delay time is of the order of 70 ?s.

Bloem, W. B.

14

A very thin overoxidized polypyrrole membrane as coating for fast time response and selective H2O2 amperometric sensor.  

Science.gov (United States)

Pyrrole electrooxidation in the presence of weak-acidic anions allows one to locally, rapidly and in single step form on the electrode a pinhole-free very thin layer of overoxidized polypyrrole (OPPy). This membrane could be really useful for the design of amperometric biosensor based on oxidation of H(2)O(2) generated by an oxidase. Indeed, using rotation disk electrode, the apparent diffusion coefficient of H(2)O(2) within this OPPy film was found to be 10(-8)cm(2)s(-1), which corresponds to a fast response time of 0.1 ms. Moreover, it is shown that with this system, platinum electrode coated with the very thin OPPy membrane, the H(2)O(2) sensitivity is excellent (700 nA microM(-1)cm(-2)) and the H(2)O(2) selectivity relative to potentially interfering species present in biological fluids, such as ascorbate and dopamine, is very good. Thus, this OPPy membrane which can be locally electrodeposited is ideal for the construction of oxidase-based microbiosensors. PMID:20434323

Debiemme-Chouvy, Catherine

2010-07-15

15

Fast-time-response Zeeman polarimeter for the study of internal magnetic field structures in the JIPP T-IIU tokamak  

International Nuclear Information System (INIS)

A Zeeman polarimeter with a fast time response much faster than the magnetic diffusion time of the plasma is developed to measure the poloidal magnetic field structure of a toroidal plasma. A specially developed Fabry-Perot interferometer has allowed us to measure the poloidal magnetic field with time resolution up to 1.5 ms. High signal-to-noise ratio is achieved by using a correlation technique based on the Fast Fourier Transform, and the minimum detectable poloidal field strength is found to be 0.003T. This polarimeter is successfully applied to fast current ramping experiments in the JIPP T-IIU, and both the clear production of skin current and the penetration of the current are observed. Also, the fact that the penetration of the skin current can be predicted by a model based on neoclassical resistivity is confirmed

16

The time-walk of analog constant fraction discriminators using very fast scintillator detectors with linear and non-linear energy response  

International Nuclear Information System (INIS)

The electronic ?–? fast timing technique allows for direct nuclear lifetime determination down to the few picoseconds region by measuring the time difference between two coincident ?-ray transitions. Using high resolution ultra-fast LaBr3(Ce) scintillator detectors in combination with the recently developed mirror symmetric centroid difference method, nuclear lifetimes are measured with a time resolving power of around 5 ps. The essence of the method is to calibrate the energy dependent position (centroid) of the prompt response function of the setup which is obtained for simultaneously occurring events. This time-walk of the prompt response function induced by the analog constant fraction discriminator has been determined by systematic measurements using different photomultiplier tubes and timing adjustments of the constant fraction discriminator. We propose a universal calibration function which describes the time-walk or the combined ?–? time-walk characteristics, respectively, for either a linear or a non-linear amplitude versus energy dependency of the scintillator detector output pulses.

17

Reducing preoperative fasting time: A trend based on evidence  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Preoperative fasting is mandatory before anesthesia to reduce the risk of aspiration. However, the prescribed 6-8 h of fasting is usually prolonged to 12-16 h for various reasons. Prolonged fasting triggers a metabolic response that precipitates gluconeogenesis and increases the organic response to trauma. Various randomized trials and meta-analyses have consistently shown that is safe to reduce the preoperative fasting time with a carbohydrate-rich drink up to 2 h before surgery. Benefits re...

José Eduardo de Aguilar-Nascimento; Diana Borges Dock-Nascimento

2010-01-01

18

Fast response stainless steel sodium thermocouple  

International Nuclear Information System (INIS)

Thermo electro motive force and transient response characteristics of well-type stainless steel sodium thermocouples have been studied. The experiments were performed with a specially constructed test rig allowing the placement of several couples at various depths of immersion in liquid sodium and at different spacings. The time response was studied by inducing temperature transients in a hot sodium injection and gas injection, and photographing the oscilloscope trace of the output. The possibility of using these thermocouples in transit time flowmeters in sodium circuit was ascertained by observing the response from two thermocouples in flowing sodium, and evaluating the cross-correlation between the response. The application of such thermocouples for fast reactors and sodium circuits is also discussed. (author)

19

Fast, Responsive Decentralised Graph Colouring  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We solve, in a fully decentralised way, the classic problem of colouring a graph. We propose a novel algorithm that is automatically responsive to topology changes, and we prove that it converges to a proper colouring in $O(N\\log{N})$ time with high probability for generic graphs (and in $O(\\log{N})$ time if $\\Delta=o(N)$) when the number of available colours is greater than $\\Delta$, the maximum degree of the graph. Moreover, this algorithm is significantly simpler and ea...

Checco, Alessandro; Leith, Douglas J.

2014-01-01

20

The high contrast ratio and fast response time of a liquid crystal display lit by a carbon nanotube field emission backlight unit  

International Nuclear Information System (INIS)

We report on the fabrication of a carbon nanotube field emission backlight unit (CNT-BLU) and its application for liquid crystal displays (LCD). The CNT-BLU was operated with locally controllable luminance and impulse-type scanning. The local luminance control, which is based on a very small block size of 1 cm2, consisted of local dimming and local brightening. This resulted in the contrast ratio of the LCD-TV to be as high as 300 000:1. A fast response time of ?5.7 ms was also achieved from the LCD-TV lit by CNT-BLU, originating from the impulse-type scanning. In addition, the CNT-BLU showed long-term emission stability and high luminance uniformity

 
 
 
 
21

The high contrast ratio and fast response time of a liquid crystal display lit by a carbon nanotube field emission backlight unit  

Energy Technology Data Exchange (ETDEWEB)

We report on the fabrication of a carbon nanotube field emission backlight unit (CNT-BLU) and its application for liquid crystal displays (LCD). The CNT-BLU was operated with locally controllable luminance and impulse-type scanning. The local luminance control, which is based on a very small block size of 1 cm{sup 2}, consisted of local dimming and local brightening. This resulted in the contrast ratio of the LCD-TV to be as high as 300 000:1. A fast response time of {approx}5.7 ms was also achieved from the LCD-TV lit by CNT-BLU, originating from the impulse-type scanning. In addition, the CNT-BLU showed long-term emission stability and high luminance uniformity.

Choi, Young Chul; Lee, Ji Won; Lee, Su Kyung; Kang, Mun Seok; Lee, Chang Soo; Jung, Kyu Won; Lim, Ji Hong; Moon, Jong Woon; Hwang, Myung Ick; Kim, Il Hwan; Kim, Yun Hee; Lee, Byong Gon; Seon, Hyung Rae; Lee, Sang Jin; Park, Jong Hwan; Kim, Yong C; Kim, Hun Soo [Display Laboratory 3 Group, Corporate R and D Center, Samsung SDI, 428-5, Gongse-dong, Giheung-gu, Yongin, Gyeonggi 446-577 (Korea, Republic of)], E-mail: hs88.kim@samsung.com

2008-06-11

22

Reducing preoperative fasting time: A trend based on evidence.  

Science.gov (United States)

Preoperative fasting is mandatory before anesthesia to reduce the risk of aspiration. However, the prescribed 6-8 h of fasting is usually prolonged to 12-16 h for various reasons. Prolonged fasting triggers a metabolic response that precipitates gluconeogenesis and increases the organic response to trauma. Various randomized trials and meta-analyses have consistently shown that is safe to reduce the preoperative fasting time with a carbohydrate-rich drink up to 2 h before surgery. Benefits related to this shorter preoperative fasting include the reduction of postoperative gastrointestinal discomfort and insulin resistance. New formulas containing amino acids such as glutamine and other peptides are being studied and are promising candidates to be used to reduce preoperative fasting time. PMID:21160851

de Aguilar-Nascimento, José Eduardo; Dock-Nascimento, Diana Borges

2010-03-27

23

Reducing preoperative fasting time: A trend based on evidence  

Directory of Open Access Journals (Sweden)

Full Text Available Preoperative fasting is mandatory before anesthesia to reduce the risk of aspiration. However, the prescribed 6-8 h of fasting is usually prolonged to 12-16 h for various reasons. Prolonged fasting triggers a metabolic response that precipitates gluconeogenesis and increases the organic response to trauma. Various randomized trials and meta-analyses have consistently shown that is safe to reduce the preoperative fasting time with a carbohydrate-rich drink up to 2 h before surgery. Benefits related to this shorter preoperative fasting include the reduction of postoperative gastrointestinal discomfort and insulin resistance. New formulas containing amino acids such as glutamine and other peptides are being studied and are promising candidates to be used to reduce preoperative fasting time.

José Eduardo de Aguilar-Nascimento

2010-03-01

24

Preoperative fasting time in children.  

LENUS (Irish Health Repository)

The aim of preoperative fasting is to prevent regurgitation and pulmonary aspiration while limiting potential problems of thirst, dehydration and hypoglycaemia. The American Society of Anaesthesiologists (ASA) has suggested guidelines for preoperative fasting for children undergoing elective surgery. We did a postal survey to determine the current practice regarding these guidelines amongst all specialist registrars in anaesthesia in Ireland. A questionnaire was sent to all specialist registrars in anaesthesia (90 in total), 60 (67%) were returned and analysed. The question asked was how long children should be kept fasting before elective surgery. The results of our survey suggest that most of the respondents are following the ASA guidelines for clear fluids and solids however there were differing opinion regarding the duration of fasting for formula milk and breast milk. In conclusion, we would recommend greater awareness and collaboration between anaesthetists, nurses and surgeons to ensure that fasting instructions are consistent with the ASA guidelines and that patient and their parents understand these directives as well.

Adeel, S

2012-02-01

25

High reliability - fast response thermocouples  

International Nuclear Information System (INIS)

The primary causes of failure in conventional twin core mineral-insulated thermocouples are briefly reviewed and data are presented on the design and performance of an alternative form. This is a single-core coaxial mineral-insulated cable incorporating several features intended to improve both the reliability and speed of response without increasing the cable diameter. It is proposed for sub-assembly monitoring in LMFBR's. (U.K.)

26

Fast timing with bismuth germanate  

International Nuclear Information System (INIS)

The coupling of An Amperex 2312 photomultiplier to a 7.6 cm x 7.6 cm bismuth germanata (BGO) detector has yielded excellent time resolution for 0.5 MeV gamma-rays (1.40 +- 0.05 ns). Along with the excellent timing this photomultiplier has an energy resolution which is as good as that obtained with slower tubes. (orig.)

27

A fast-response shallow-water tide gauge  

International Nuclear Information System (INIS)

The authors describe the characteristics of a fast-response tide gauge suitable for shallow-water conditions. Its time constant is of the order of minutes. Wind waves are filtered better than 99% in the (0/10) s interval. The tide gauge has now been operative for three years on an oceanographic tower in the open sea. (author)

28

Magnetostrictive actuators with large displacement and fast response  

International Nuclear Information System (INIS)

This paper presents the development of a giant magnetostrictive actuator (GMA) with large displacement and fast response. An elliptical flexure hinge lever amplification structure is designed and applied in the GMA. The finite element method is adopted for analyzing and optimizing flexure hinge geometry. Furthermore, the coil and magnetic circuit are studied to improve the driving system. Static and dynamic performances of the GMA are tested. As a result, displacement output amplification ratio can be 2.68 times in the static test. The dynamic performance testing indicates that the GMA with amplification structure can achieve a steady output on average of 140 µm between 0 and 130 Hz driving by 240 Oe, and the time response is 0.6 ms. These results show that large displacement and fast response are obtained simultaneously. (paper)

29

Fast-response logarithmic electrometer for pulse-reactor experiments  

International Nuclear Information System (INIS)

The response time of a logarithmic electrometer was improved for pulse reactor experiments requiring long detector cables. A new phase-compensation technique was used in the circuit and it is based on the idea that a current variable resistance inserted between a detector cable and the input terminal of the logarithmic electrometer recovers the phase lag caused by the input capacitance. This stable and fast-response logarithmic electrometer was successfully applied to transient power measurements of the one-shot pulse reactor ''YAYOI''

30

Mutagenic response of peanut (arachis hypogaea L.) to fast neutrons  

International Nuclear Information System (INIS)

Dominant seeds of peanut were treated with varying doses of fast neutrons employing efficient pre- and post-irradiation techniques for determination of various plant responses useful in a long range program of mutation breeding. Mean reductions in seedling height and frequency of M1 somatic mutations increased with increasing radiation dose. No reduction in M1 seedset was obtained even in the dose above the LD50 of 1600 rads. The frequency of M2 macromutations ranged from only 3.60 - 5.65 per 100 M2 plants. The genetic basis of each of these radiation responses is briefly discussed. The high sensitivity of M1 peanut seedlings and growing plants to fast neutrons is probably due to the highly differentiated seed embryo at the time of irradiation while the radioresistance exhibited by the matured plant appears to be related to the polyploid genome of the species. (Auth.)

31

Fast floor response spectra generation technique  

International Nuclear Information System (INIS)

A consistent technique is derived for generating floor response spectra for equipment in nuclear reactor systems using response spectral analysis. The use of this technique eliminates the requirement for a time history analysis. The technique is based on the dynamic theory of coupling the supporting building with a very light spring-mass system representing the equipment. The response of the spring-mass system in the coupled systems is the floor respones spectrum at the spring-mass system frequency. Resonant and off-resonant cases are derived separately. 6 refs

32

A proposal for fast neutron personal real time dosimetry in mixed n, ? fields  

International Nuclear Information System (INIS)

A method for fast neutron monitoring has been studied, resulting from computer simulation analysis of fast neutron and gamma interaction responses in silicon counters. A real time personal dosemeter with a response accuracy better than 30% in a mixed n, ? field for neutron energies between 0.75 and 15 MeV is proposed. (author)

33

Quartz Cherenkov Counters for Fast Timing: QUARTIC  

CERN Document Server

We have developed particle detectors based on fused silica (quartz) Cherenkov radiators read out with micro-channel plate photomultipliers (MCP-PMTs) or silicon photomultipliers (SiPMs) for high precision timing (Sigma(t) about 10-15 ps). One application is to measure the times of small angle protons from exclusive reactions, e.g. p + p - p + H + p, at the Large Hadron Collider, LHC. They may also be used to measure directional particle fluxes close to external or stored beams. The detectors have small areas (square cm), but need to be active very close (a few mm) to the intense LHC beam, and so must be radiation hard and nearly edgeless. We present results of tests of detectors with quartz bars inclined at the Cherenkov angle, and with bars in the form of an "L" (with a 90 degree corner). We also describe a possible design for a fast timing hodoscope with elements of a few square mm.

Albrow, M G; Los, S; Ramberg, E; Ronzhin, A; Samoylenko, V; Wenzel, H; Zatserklyaniy, A

2012-01-01

34

The relationship between shock response spectrum and fast Fourier transform  

International Nuclear Information System (INIS)

In this paper the basic relationship between response spectrum and fast Fourier transform is laid down. Since a long time the response spectrum has been used by structural engineers in the seismic domain and nowadays it is going to be used to define transient motions. This way to define the excitation is more general and more real than the use of classical shape pulses for the reproduction of real environment. Nevertheless the response spectrum of a real excitation represents a loss of some information with respect to the Fourier transform. A useful discussion could arise from these observations. Appendix A gives the relationship between the mathematic Fourier transform and the digital Fourier transform given by computers, while Appendix B gives some examples of response spectra and Fourier transforms of simple functions. (author)

35

Estimating optimal time for fast chromatographic separations.  

Science.gov (United States)

The term t(min cc) provides a ready estimate of the shortest time that can be obtained by "column cutting" for baseline resolution of two components showing excess chromatographic resolution. While actual column cutting is impractical, the t(min cc) value is shown to be closely related to the minimum separation time obtainable by adjusting other parameters such as flow rate, mobile phase composition, and temperature, affording scientists interested in the development of fast chromatographic separations a convenient tool for estimating the minimum separation time that can be obtained by modifying a given method development screening result. Furthermore, the relationship between t(min cc) and the minimum separation time obtainable by adjusting other parameters is shown to be dependent on the speed of the screening method, with aggressive screening gradients affording t(min cc) estimates that match the actual minimum separation time, and "lazy" screening gradients affording t(min cc) values that overestimate minimum separation time. Consequently, the analysis of the relationship between t(min cc) and actual minimum separation time may be a useful tool for determining the "fitness" of method development screening methods. PMID:24995384

Welch, Christopher J; Regalado, Erik L

2014-09-01

36

A thermometer for fast response in cryogenic flow  

International Nuclear Information System (INIS)

The measurement of transient temperatures in cryogenic fluid flow requires a highly sensitive, intrinsically fast sensor that is in good thermal contact with the fluid but in poor thermal contact with the solid walls confining the fluid. A resistance thermometer made from a 1 ?m thick silicon layer on a 125 ?m thick sapphire substrate has a calculated intrinsic response time of about 10 ns at 4 K, and its sensitivity is comparable to germanium or carbon thermometers in the range of 1-80 K. This paper describes a novel construction method to mount the small silicon-on-sapphire thermometer in an oscillating fluid flow. The large surface area of the thermometer provides good thermal contact with the fluid, while the suspension ensures poor thermal contact with the holder, maintains its fast response time, and withstands high velocities and frequencies of fluid oscillation. A self-heating response time of 300 ns was measured at 4 K in liquid and gaseous helium. Repeatability of the thermometer is + or - 10 mK at 4 K. Examples of the performance of this thermometer for helium gas oscillations in the frequency range of 1 Hz to 12 kHz are given

37

Time-resolved and time-integrated radiography of fast reactor fuel elements  

International Nuclear Information System (INIS)

The fast-reactor safety program has some unusual requirements in radiography. Applications may be divided into two areas: time-resolved or time-integrated radiography. The fast-neutron hodoscope has supplied all recent time-resolved cineradiographic in-pile fuel-motion data, and various x-ray and photographic techniques have been used for out-of-pile experiments. Thick containers and the large number of radioactive fuel pins involved in safety research have been responsible for some nonconventional applications of time-integrated radiography of stationary objects. Hodoscopes record fuel-motion during transient experiments at the TREAT reactor in the United States and CABRI in France. Other special techniques have been under development for out-of-pile nondestructive radiography of fuel element subassemblies, including fast-neutron and gamma-ray tomographic methods

38

Time-resolved and time-integrated radiography of fast reactor fuel elements  

Energy Technology Data Exchange (ETDEWEB)

The fast-reactor safety program has some unusual requirements in radiography. Applications may be divided into two areas: time-resolved or time-integrated radiography. The fast-neutron hodoscope has supplied all recent time-resolved cineradiographic in-pile fuel-motion data, and various x-ray and photographic techniques have been used for out-of-pile experiments. Thick containers and the large number of radioactive fuel pins involved in safety research have been responsible for some nonconventional applications of time-integrated radiography of stationary objects. Hodoscopes record fuel-motion during transient experiments at the TREAT reactor in the United States and CABRI in France. Other special techniques have been under development for out-of-pile nondestructive radiography of fuel element subassemblies, including fast-neutron and gamma-ray tomographic methods.

De Volpi, A.

1981-01-01

39

Wave-induced hydroelastic response of fast monohull displacement ships  

DEFF Research Database (Denmark)

High-speed ships are weight sensitive structures and high strength steel, aluminium or composites are preferred building materials. It is characteristic for these materials that they result in larger hull flexibility than more conventional materials. Therefore, for large fast ships the lowest natural frequencies of the global hull modes can be relatively low compared to the frequency of wave encounter.In the present paper the effect of hull flexibility on the wave-induced springing and whipping vibrations is investigated in stationary stochastic seaways. The calculations are performed using a quadratic strip theory formulated in the frequency domain and a fully non-linear time-domain strip theory. The hydroelastic response is thereby excited partly by resonance and partly by non-linear excitation. The calculations are carried out for a recent proposal for a fast monohull containership.

Jensen, JØrgen Juncher; Wang, Zhaohui

1998-01-01

40

Fast-Response Liquid Crystal Microlens  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Electrically tunable liquid crystal microlenses have attracted strong research attention due to their advantages of tunable focusing, voltage actuation, low power consumption, simple fabrication, compact structure, and good stability. They are expected to be essential optical devices with widespread applications. However, the slow response time of nematic liquid crystal (LC) microlenses has been a significant technical barrier to practical applications and commercialization. LC/polymer compos...

Su Xu; Yan Li; Yifan Liu; Jie Sun; Hongwen Ren; Shin-Tson Wu

2014-01-01

 
 
 
 
41

Modeling response signal and response time data?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The diffusion model (Ratcliff, 1978) and the leaky competing accumulator model (LCA, Usher & McClelland, 2001) were tested against two-choice data collected from the same subjects with the standard response time procedure and the response signal procedure. In the response signal procedure, a stimulus is presented and then, at one of a number of experimenter-determined times, a signal to respond is presented. The models were fit to the data from the two procedures simultaneously under the assu...

Ratcliff, Roger

2006-01-01

42

Perceptual learning of time-compressed and natural fast speech.  

Science.gov (United States)

Speakers vary their speech rate considerably during a conversation, and listeners are able to quickly adapt to these variations in speech rate. Adaptation to fast speech rates is usually measured using artificially time-compressed speech. This study examined adaptation to two types of fast speech: artificially time-compressed speech and natural fast speech. Listeners performed a speeded sentence verification task on three series of sentences: normal-speed sentences, time-compressed sentences, and natural fast sentences. Listeners were divided into two groups to evaluate the possibility of transfer of learning between the time-compressed and natural fast conditions. The first group verified the natural fast before the time-compressed sentences, while the second verified the time-compressed before the natural fast sentences. The results showed transfer of learning when the time-compressed sentences preceded the natural fast sentences, but not when natural fast sentences preceded the time-compressed sentences. The results are discussed in the framework of theories on perceptual learning. Second, listeners show adaptation to the natural fast sentences, but performance for this type of fast speech does not improve to the level of time-compressed sentences. PMID:19894842

Adank, Patti; Janse, Esther

2009-11-01

43

Fast transfer of crossmodal time interval training.  

Science.gov (United States)

Sub-second time perception is essential for many important sensory and perceptual tasks including speech perception, motion perception, motor coordination, and crossmodal interaction. This study investigates to what extent the ability to discriminate sub-second time intervals acquired in one sensory modality can be transferred to another modality. To this end, we used perceptual classification of visual Ternus display (Ternus in Psychol Forsch 7:81-136, 1926) to implicitly measure participants' interval perception in pre- and posttests and implemented an intra- or crossmodal sub-second interval discrimination training protocol in between the tests. The Ternus display elicited either an "element motion" or a "group motion" percept, depending on the inter-stimulus interval between the two visual frames. The training protocol required participants to explicitly compare the interval length between a pair of visual, auditory, or tactile stimuli with a standard interval or to implicitly perceive the length of visual, auditory, or tactile intervals by completing a non-temporal task (discrimination of auditory pitch or tactile intensity). Results showed that after fast explicit training of interval discrimination (about 15 min), participants improved their ability to categorize the visual apparent motion in Ternus displays, although the training benefits were mild for visual timing training. However, the benefits were absent for implicit interval training protocols. This finding suggests that the timing ability in one modality can be rapidly acquired and used to improve timing-related performance in another modality and that there may exist a central clock for sub-second temporal processing, although modality-specific perceptual properties may constrain the functioning of this clock. PMID:24570386

Chen, Lihan; Zhou, Xiaolin

2014-06-01

44

Fast optical response to electrical activation in peripheral nerves  

Science.gov (United States)

Complex neuronal structures and interactions make studying fast optical signals associated with brain activation difficult, especially in non-invasive measurements that are further complicated by the filtering effect of the scalp and skull. We have chosen to study fast optical signals in the peripheral nervous system to look at a more simplified biological neuronal structure and a system that is more accessible to non-invasive optical studies. In this study, we recorded spatially resolved electrical and optical responses of the human sural nerve to electrical stimulation. A 0.1 ms electrical stimulation was used to activate the sural nerve. Electrical signals were collected by an electromyogram machine and results showed an electrical response spanning a distance of 8 mm across the nerve. Optical signals were collected by a two-wavelength (690 and 830 nm) near-infrared spectrometer and displayed a characteristic decrease in intensity at both wavelengths. Data were taken at multiple positions and then reproduced five times. The average optical data over the five trials showed an optical signal that was spatially consistent with the electrical response to sural nerve stimulation.

Chen, Debbie K.; Tong, Yunjie; Sassaroli, Angelo; Bergethon, Peter R.; Fantini, Sergio

2007-02-01

45

Fast Time-Domain Algorithms for UWB Bistatic SAR Processing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two fast time-domain algorithms are introduced for ultrawideband-ultrawidebeam (UWB) bistatic synthetic aperture radar (SAR) processing; they are bistatic fast backprojection (BiFBP) and bistatic fast factorized backprojection (BiFFBP). Both algorithms process radar echoes on a subaperture and subimage basis in order to minimize processing time. They are shown to work with any configuration of bistatic SAR. They also own time-domain characteristics, which are essential...

Vu, Viet; Sjo?gren, Thomas; Pettersson, Mats

2013-01-01

46

Polycrystalline CVD diamond detector: Fast response and high sensitivity with large area  

Energy Technology Data Exchange (ETDEWEB)

Polycrystalline diamond was successfully used to fabricate a large area (diameter up to 46 mm) radiation detector. It was proven that the developed detector shows a fast pulsed response time and a high sensitivity, therefore its rise time is lower than 5 ns, which is two times faster than that of a Si-PIN detector of the same size. And because of the large sensitive area, this detector shows good dominance in fast pulsed and low density radiation detection.

Liu, Linyue, E-mail: liulinyue@gmail.com; Zhang, Xianpeng; Zhong, Yunhong [Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Ouyang, Xiaoping, E-mail: oyxp@yahoo.com; Zhang, Jianfu [Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Xi' an Jiaotong University, Xi' an 710049 (China)

2014-01-15

47

Polycrystalline CVD diamond detector: Fast response and high sensitivity with large area  

International Nuclear Information System (INIS)

Polycrystalline diamond was successfully used to fabricate a large area (diameter up to 46 mm) radiation detector. It was proven that the developed detector shows a fast pulsed response time and a high sensitivity, therefore its rise time is lower than 5 ns, which is two times faster than that of a Si-PIN detector of the same size. And because of the large sensitive area, this detector shows good dominance in fast pulsed and low density radiation detection

48

High-power fast-response phase shifter  

International Nuclear Information System (INIS)

A design of a high-power fast-response phase changer is considered. The phase changer developed for the system of increasing electron beam energy in a linear accelerator. The phase changer design is based on the use of the trackdecibel bridge. Diode switches are placed in two bridge shoulders at the equal distance from the slit. The phase changer is made of standard rectangular 72x34 mm waveguide. Phase changer tests in the pulse regime at a high power level (up to 10 kWt in the case of pulse duration of 2.5 ?s and beam off duty of 1000) have shown that the 20% increase of time phase changing takes place at this level

49

Uncertainty evaluation of fast reactor core seismic response  

International Nuclear Information System (INIS)

Response Surface Methodology (RSM) has been applied to the evaluation of the uncertainties on the seismic behaviour of a fast reactor core. For this study preliminary data concerning the Italian PEC reactor test facility have been used. The structural dynamic analysis has been performed by means of the SAP IV code for the whole reactor block and CORALIE for the core. Once a certain acceleration time history at the ground has been assumed, the characteristics of the acceleration time-history at the core support grid, related to the vessel-core dynamic interaction, the reactor vessel stiffness, the frequency response, damping and impact coefficients of the core elements, and the number of core element rows assumed in the non-linear core calculations have been identified as the major contributors to the overall uncertainty. For each element type the responses calculated with CORALIE have been approximated by means of polynomial functions, whose adequacy in the variable space investigated has been tested by means of a further set of dynamic calculations. Finally the input uncertainties have been propagated by a Monte Carlo routine (MUP) under different assumptions to assess the sensitivity of the output distribution with respect to the kind of input probability distributions. The aim of this latter analysis step is the proposal of an adequate approach for verifying that the control rods succeed at a high probability to fall inside their guide-tubes in the case of an earth their guide-tubes in the case of an earth-quake, so that the reactor can be safely shut-down. The paper describes the details of the study and demonstrates RSM adequacy for the analysis of the input uncertainty effects on the core seismic response. It also shows that the core element frequencies and damping coefficients, as well as the vessel-core dynamic interaction parameters, are the main variables affecting such response, which therefore need a sufficiently precise definition. (orig.)

50

Analysis of the seismic response of a fast reactor core  

International Nuclear Information System (INIS)

This report deals with the methods to apply for a correct evaluation of the reactor core seismic response. Reference is made to up-to-date design data concerning the PEC core, taking into account the presence of the core-restraint plate located close to the PEC core elements top and applying the optimized iterative procedure between the vessel linear calculation and the non-linear ones limited to the core, which had been described in a previous report. It is demonstrated that the convergence of this procedure is very fast, similar to what obtained in the calculations of the cited report, carried out with preliminary data, and it is shown that the cited methods allow a reliable evaluation of the excitation time histories for the experimental tests in support of the seismic verification of the shutdown system and the core of a fast reactor, as well as relevant data for the experimental, structural and functional, verification of the core elements in the case of seismic loads

51

New charge sensitive preamplifier with a fast timing signal output  

International Nuclear Information System (INIS)

A charge sensitive preamplifier with a fast timing output has been developed. Different from the Sherman's method which uses a low gain fast amplifier and a high gain slow amplifier in parallel as the second stage, the timing output of this preamplifier is extracted from the fast current signal in the collector current of the cascode type amplifier by using a current-voltage convertor. This preamplifier has a good resolution when used with a thin silicon detector which has a large capacitance. (auth.)

52

Fluctuation-Response Relation and modeling in systems with fast and slow dynamics  

Directory of Open Access Journals (Sweden)

Full Text Available We show how a general formulation of the Fluctuation-Response Relation is able to describe in detail the connection between response properties to external perturbations and spontaneous fluctuations in systems with fast and slow variables. The method is tested by using the 360-variable Lorenz-96 model, where slow and fast variables are coupled to one another with reciprocal feedback, and a simplified low dimensional system. In the Fluctuation-Response context, the influence of the fast dynamics on the slow dynamics relies in a non trivial behavior of a suitable quadratic response function. This has important consequences for the modeling of the slow dynamics in terms of a Langevin equation: beyond a certain intrinsic time interval even the optimal model can give just statistical prediction.

G. Lacorata

2007-10-01

53

Actual preoperative fasting time in Brazilian hospitals: the BIGFAST multicenter study  

Directory of Open Access Journals (Sweden)

Full Text Available José E de Aguilar-Nascimento,1 Ana L de Almeida Dias,2 Diana B Dock-Nascimento,3 Maria Isabel TD Correia,4 Antonio CL Campos,5 Pedro Eder Portari-Filho,6 Sergio S Oliveira71Department of Surgery, Julio Muller University Hospital, Cuiaba, Brazil; 2Federal University of Mato Grosso, Cuiaba, Brazil; 3Department of Sciences and Food, Federal University of Mato Grosso, Cuiaba, Brazil; 4Department of Surgery, Federal University of Minas Gerais, Belo Horizonte, Brazil; 5Department of Surgery, Federal University of Parana, Curitiba, Brazil; 6Department of Surgery, Federal University of Rio de Janeiro State, Rio de Janeiro, Brazil; 7Service of Anesthesiology, Julio Muller University Hospital, Cuiaba, Brazil On behalf of the BIGFAST (Brazilian Group for the Study of Preoperative Fasting Time group Background: Prolonged fasting increases organic response to trauma. This multicenter study investigated the gap between the prescribed and the actual preoperative fasting times in Brazilian hospitals and factors associated with this gap. Methods: Patients (18–90-years-old who underwent elective operations between August 2011 and September 2012 were included in the study. The actual and prescribed times for fasting were collected and correlated with sex, age, surgical disease (malignancies or benign disease, operation type, American Society of Anesthesiologists score, type of hospital (public or private, and nutritional status. Results: A total of 3,715 patients (58.1% females with a median age of 49 (18–94 years from 16 Brazilian hospitals entered the study. The median (range preoperative fasting time was 12 (2–216 hours, and fasting time was longer (P<0.001 in hospitals using a traditional fasting protocol (13 [6–216] hours than in others that had adopted new guidelines (8 [2–48] hours. Almost 80% (n=2,962 of the patients were operated on after 8 or more hours of fasting and 46.2% (n=1,718 after more than 12 hours. Prolonged fasting was not associated with physical score, age, sex, type of surgery, or type of hospital. Patients operated on due to a benign disease had an extended duration of preoperative fasting. Conclusion: Actual preoperative fasting time is significantly longer than prescribed fasting time in Brazilian hospitals. Most of these hospitals still adopt traditional rather than modern fasting guidelines. All patients are at risk of long periods of fasting, especially those in hospitals that follow traditional practices. Keywords: preoperative fasting, preoperative care, multicenter study, intraoperative complications, guideline adherence, perioperative risk

Aguilar-Nascimento JE

2014-02-01

54

Response of nuclear surface onto fast proton scattering  

International Nuclear Information System (INIS)

Response of semi-infinite Fermi liquid to a periodical external force acting on its surface is considered on the basis of the semi-classical Landau theory of Fermi liquid. The obtained surface response function coincides with the classical limit of the quantum response function derived in the random-phase approximation. The theory is applied to the description of a response of nuclear surface to fast proton scattering at small momentum and energy transfers. The non-resonance component of the experimental spectrum (a smooth substrate in the region of giant nuclear resonance) is fairly reproduced by the theory

55

Fast timing methods for semiconductor detectors. Revision  

International Nuclear Information System (INIS)

This tutorial paper discusses the basic parameters which determine the accuracy of timing measurements and their effect in a practical application, specifically timing with thin-surface barrier detectors. The discussion focusses on properties of the detector, low-noise amplifiers, trigger circuits and time converters. New material presented in this paper includes bipolar transistor input stages with noise performance superior to currently available FETs, noiseless input terminations in sub-nanosecond preamplifiers and methods using transmission lines to couple the detector to remotely mounted preamplifiers. Trigger circuits are characterized in terms of effective rise time, equivalent input noise and residual jitter

56

Fast-timing methods for semiconductor detectors  

International Nuclear Information System (INIS)

The basic parameters are discussed which determine the accuracy of timing measurements and their effect in a practical application, specifically timing with thin-surface barrier detectors. The discussion focusses on properties of the detector, low-noise amplifiers, trigger circuits and time converters. New material presented in this paper includes bipolar transistor input stages with noise performance superior to currently available FETs, noiseless input terminations in sub-nanosecond preamplifiers and methods using transmission lines to couple the detector to remotely mounted preamplifiers. Trigger circuits are characterized in terms of effective rise time, equivalent input noise and residual jitter

57

Plastic fiber scintillator response to fast neutrons  

International Nuclear Information System (INIS)

The Neutron Imaging System at NIF uses an array of plastic scintillator fibers in conjunction with a time-gated imaging system to form an image of the neutron emission from the imploded capsule. By gating on neutrons that have scattered from the 14.1 MeV DT energy to lower energy ranges, an image of the dense, cold fuel around the hotspot is also obtained. An unmoderated spallation neutron beamline at the Weapons Neutron Research facility at Los Alamos was used in conjunction with a time-gated imaging system to measure the yield of a scintillating fiber array over several energy bands ranging from 1 to 15 MeV. The results and comparison to simulation are presented

58

Fast and Slow Transient Response of WECS with Simultaneous Actions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper details the transient operation of a wind energy conversion system (WECS) used simultaneously as an ac- tive filter and power generator. This study is intended to address the system response to two types of transient phenomena: voltage dips (fast transients) and wind speed variations (slow transients). The system response to voltage dips is governed by the electrical system dynamics and control method and results in the evaluation of the WECS low-voltage ride through capability. Th...

Amarendra, M.; Srikanth, S.; Siva Suteja, G.; Prasanna Lakshmi, B.; Madhavi Latha, K.

2012-01-01

59

Fast Passive Summators for Timing Applications  

CERN Document Server

Our basic present choice for the candidates to the multiplicity counters of ALICE is the Micro Channel Plate based detector (FMD-MCP) [1,2]. The signals from MCP detector are very sharp in time. The signal from a single particle has a leading edge rise time of about 200ps and a width of 1ns.

Kolojvari, A A; CERN. Geneva; Tsimbal, F A; Tulina, T A; Valiev, F F; Vinogradov, L I; Potapov, S V; Novikov, I A

1995-01-01

60

Fast detection of cycles in timed automata  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We propose a new efficient algorithm for detecting if a cycle in a timed automaton can be iterated infinitely often. Existing methods for this problem have a complexity which is exponential in the number of clocks. Our method is polynomial: it essentially does a logarithmic number of zone canonicalizations. This method can be incorporated in algorithms for verifying B\\"uchi properties on timed automata. We report on some experiments that show a significant reduction in searc...

Deshpande, Aakash; Herbreteau, Fre?de?ric; Srivathsan, B.; Tran, Thanh-tung; Walukiewicz, Igor

2014-01-01

 
 
 
 
61

Timing response of CdTe detectors  

International Nuclear Information System (INIS)

Semiconductor CdTe detectors are gaining wide acceptance in many applications where X- and ?-ray measurements are necessary, such as in astrophysical research, medical imaging and industrial radiography. Good timing response is critical both in applications like positron emission tomography, where fast coincidence capabilities are required, and in single photon counting when a high counting rate is needed. The typical configuration employed, where the direction of the impinging radiation beam is parallel to the collecting electric field, has one well known drawback: An increase in active layer, necessary in order to reach a satisfactory absorption efficiency for the detection of high energy photons, leads to a longer transport path for the charge carriers generated. As a consequence, there is a degradation in energy resolution and a broadening in time response. In the present paper, measurements of the timing response for an unusual configuration of CdTe detectors are presented. In this configuration, which we call a PTF (planar transverse field) detector, the collecting electric field and hence the transport length are independent. In this way the absorption layer can be increased without impairing the timing performance. The measurements described herein have been performed using a PTF detector having dimensions of 2.5x2.5x20 mm3, in order to have a good efficiency for annihilation ?-ray photons. (orig.)

62

Fast-response amplitude analyzer in modern nuclear physics and engineering  

International Nuclear Information System (INIS)

Operation and design principles of measuring channels of amplitude analyzers and fast-response spectrometers widely used in experimental nuclear physics and applied measurements of ionizing radiations are considered. A review of the calculational methods of the dead time amplitude analyzer basic parameters, differential nonlinearity, distortions from pulse superpositions, etc. - is given. Technically complex and comparatively rarely used methods, like the method of total separation of superpositions, are presented in detail. Digital methods of spectrometric signal filtration are described. Problems of stabilization and gauging of spectrometric channels are discussed. Recommendations on the development and operation of fast-response analyzers and spectrometers are given

63

Fast method to calculate tsunami arrival times  

Science.gov (United States)

Exact arrival time of tsunami wave at coast or/and sensor is among important parameters for tsunami risk mitigation. Among the existing methods we mention: simulation of synthetic tsunami wave propagation from the given source; permanent data check at sensor system. Both approaches require extended CPU time or data transfer. Here we suggest alternative method based only on kinematics computation. The method is based on kinematic calculation of tsunami wave front line. Precise algorithms to move the points at the front line and, in case of necessity, to add new points, have been proposed. To start with, this method was successfully tested in an area with constant depth. Then the model bathymetry with parabolic and sloping bottom relief, in which cases exact analytical solutions are available, were studied. New algorithm was proved to be precise. The method gives possibility to compute not only tsunami travel times but also the wave rays. Tsunami amplitude can be estimated by wave-ray's divergence and depth change along wave route. The wave amplitude was estimated and then compared to results of numerical tests, obtained within the shallow-water numerical modeling of tsunami propagation using the MOST software package. For the model (slope-like) bathymetry the results differs by only a few percent. The advantage of proposed method is rapidness and low computer resources requirement.

Lavrentyev, Mikhail; Romanenko, Alexey; Marchuk, Andery; Vassilyev, George

2014-05-01

64

Fast time-resolved aerosol collector: proof of concept  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Atmospheric particles can be collected in the field on substrates for subsequent laboratory analysis via chemically sensitive single particle methods such as scanning electron microscopy with energy dispersive x-ray analysis. With moving substrates time resolution of seconds to minutes can be achieved. In this paper, we demonstrate how to increase the time resolution when collecting particles on a substrate to a few milliseconds to provide real-time information. Our fast time-resolved aerosol...

-y Yu, X.; Cowin, J. P.; Iedema, M. J.; Ali, H.

2010-01-01

65

A fast X-ray timing capability on XEUS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Fast X-ray timing can be used to probe strong gravity fields around collapsed objects and constrain the equation of state of dense matter in neutron stars. These studies require extremely good photon statistics. In view of the huge collecting area of its mirrors, XEUS could make a unique contribution to this field. For this reason, we propose to include a fast X-ray timing capability in the focal plane of the XEUS mirrors. We briefly outline the scientific motivation for suc...

Barret, D.; Skinner, G.; Kendziorra, E.; Staubert, R.; Stella, L.; Klis, M.

2002-01-01

66

Fast responsive, optical trace level ammonia sensor for environmental monitoring  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Background Ammonia is a ubiquitous chemical substance which is created in technical and biological processes and harmful to many different organisms. One specific problem is the toxicity of ammonia in fish at levels of 25 ?g/l - a very common issue in today’s aqua culture. In this study we report a development of a fast responsive, optical ammonia sensor for trace concentrations. Results Different hydrogels have been investigated as host polymers for...

Abel Tobias; Ungerböck Birgit; Klimant Ingo; Mayr Torsten

2012-01-01

67

A fast near-field method for calculations of time-harmonic and transient pressures produced by triangular pistons  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Analytical expressions are demonstrated for fast calculations of time-harmonic and transient near-field pressures generated by triangular pistons. These fast expressions remove singularities from the impulse response, thereby reducing the computation time and the peak numerical error with a general formula that describes the near-field pressure produced by any triangular piston geometry. The time-domain expressions are further accelerated by a time-space decomposition approach that analytical...

Chen, Duo; Kelly, James F.; Mcgough, Robert J.

2006-01-01

68

Fast Time-Resolved Aerosol Collector: Proof of Concept  

Energy Technology Data Exchange (ETDEWEB)

Atmospheric particles can be collected in the field on substrates for subsequent laboratory analysis via chemically sensitive single particle methods such as scanning electron microscopy with energy dispersed x-ray analysis. With moving substrates one can achieve time resolution of seconds to minutes. We demonstrate how to increase the time resolution to a few milliseconds to provide real-time information in this paper. Our fast time-resolved aerosol collector (“Fast-TRAC”) microscopically observes the particle collection on substrate and record an on-line video. Particle arrivals are resolved to within a single frame (17 to 4 ms in this setup), and the spatial locations are matched to the subsequent single particle analysis. This approach provides real-time information on particle size and number concentration. Applications are expected in airborne studies of cloud microstructure, pollution plumes, and long term site monitoring.

Yu, Xiao-Ying; Cowin, James P.; Iedema, Martin J.; Ali, Hashim M.

2010-10-12

69

Investigating Two Different Training Time Frames during Ramadan Fasting  

Science.gov (United States)

Purpose Muslim athletes may continue training and competing while they are fasting. There is a concern about negative effects of fasting on sports performance. This study aimed to investigate the influence of two training time frames on athletes’ body composition and performance during Ramadan fasting. Methods An observational study was conducted and thirty four male volunteer athletes from different sports including volleyball, karate, taekwondo and football were assigned in two groups. The first group included 14 elite athletes who during Ramadan voluntarily participated in training sessions at 1 hour before Iftar (BI) and the second group of 20 elite athletes who during Ramadan participated in training sessions at 3 hours after Iftar (AI). Testing was performed one week before; in the first and fourth weeks of Ramadan and one week after Ramadan. Weights, heights and skinfold thickness were assessed at each time point and body mass index was calculated. Each player was assessed for agility and explosive strength as well. Results The mean weight and body mass index of both groups decreased significantly during Ramadan (P<0.001). Performance variables were not negatively affected by fasting in BI or AI group athletes. Conclusions Weight reduction might come with either BI or AI training schedules in Ramadan. Daytime or evening training did not inversely affect the agility and power performances in a group of elite athletes during Ramadan fasting. PMID:22375240

Kordi, Ramin; Abdollahi, Mohammad; Memari, Amir-Hossein; Najafabadi, Mahboubeh Ghayour

2011-01-01

70

Slow and fast magneto-optical response of magnetite nanoparticles suspension  

Digital Repository Infrastructure Vision for European Research (DRIVER)

DC magnetic field applied to Fe?O?; nanoparticle suspension affects its light scattering. Time dependent variations in the light intensity transmitted through a suspension are observed after the magnetic field is switched-on. Two types of variations can be distinguished. Fast response takes less than millisecond while slow variations occur at the time interval from seconds to hundreds of minutes. Possible mechanisms of these variations are discussed.

Dmitruk, N.; Moroz, I.; Malynych, S.

2011-01-01

71

Time-resolved fast neutron imaging: simulation of detector performance  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have analyzed and compared the performance of two novel fast-neutron imaging methods with time-of-flight spectroscopy capability. Using MCNP and GEANT code simulations of neutron and charged-particle transport in the detectors, key parameters such as detection efficiency, the amount of energy deposited in the converter and the spatial resolution of both detector variants have been evaluated.

Vartsky, D.; Mor, I.; Goldberg, M. B.; Mardor, I.; Feldman, G.; Bar, D.; Shor, A.; Dangendorf, V.; Laczko, G.; Breskin, A.; Chechik, R.

2004-01-01

72

Fast response and recovery of hydrogen sensing in Pd-Pt nanoparticle-graphene composite layers  

International Nuclear Information System (INIS)

This study reports the fast response and recovery of hydrogen sensing in nanoparticle-graphene composite layers fabricated using chemical methods and comprising of isolated Pd alloy nanoparticles dispersed onto graphene layers. For 2% hydrogen at 40 0C and 1 atm pressure, a response time of < 2 s and a recovery time of 18 s are observed. The fast response and recovery observed during sensing are due to hydrogen-induced changes in the work function of the Pd alloy and modification in the distribution of defect states in the graphene band gap due to gas adsorption. The results of hydrogen sensing in the new class of Pd-Pt nanoparticle-graphene composite material are important for understanding the effect of gas adsorption on electronic conduction in graphene layers and for developing a new type of gas sensor based on changes in the electronic properties of the interface.

73

Real time face recognition using adaboost improved fast PCA algorithm  

CERN Document Server

This paper presents an automated system for human face recognition in a real time background world for a large homemade dataset of persons face. The task is very difficult as the real time background subtraction in an image is still a challenge. Addition to this there is a huge variation in human face image in terms of size, pose and expression. The system proposed collapses most of this variance. To detect real time human face AdaBoost with Haar cascade is used and a simple fast PCA and LDA is used to recognize the faces detected. The matched face is then used to mark attendance in the laboratory, in our case. This biometric system is a real time attendance system based on the human face recognition with a simple and fast algorithms and gaining a high accuracy rate..

Kumar, K Susheel; Tripathi, R C

2011-01-01

74

Fast time-resolved aerosol collector: proof of concept  

Directory of Open Access Journals (Sweden)

Full Text Available Atmospheric particles can be collected in the field on substrates for subsequent laboratory analysis via chemically sensitive single particle methods such as scanning electron microscopy with energy dispersive x-ray analysis. With moving substrates time resolution of seconds to minutes can be achieved. In this paper, we demonstrate how to increase the time resolution when collecting particles on a substrate to a few milliseconds to provide real-time information. Our fast time-resolved aerosol collector ("Fast-TRAC" microscopically observes the particle collection on a substrate and records an on-line video. Particle arrivals are resolved to within a single frame (4–17 ms in this setup, and the spatial locations are matched to the subsequent single particle analysis. This approach also provides in-situ information on particle size and number concentration. Applications are expected in airborne studies of cloud microstructure, pollution plumes, and surface long-term monitoring.

X.-Y. Yu

2010-06-01

75

Fast time-resolved aerosol collector: proof of concept  

Directory of Open Access Journals (Sweden)

Full Text Available Atmospheric particles can be collected in the field on substrates for subsequent laboratory analysis via chemically sensitive single particle methods such as scanning electron microscopy with energy dispersive x-ray analysis. With moving substrates time resolution of seconds to minutes can be achieved. In this paper, we demonstrate how to increase the time resolution when collecting particles on a substrate to a few milliseconds to provide real-time information. Our fast time-resolved aerosol collector ("Fast-TRAC" microscopically observes the particle collection on a substrate and records an on-line video. Particle arrivals are resolved to within a single frame (4–17 ms in this setup, and the spatial locations are matched to the subsequent single particle analysis. This approach also provides in-situ information on particle size and number concentration. Applications are expected in airborne studies of cloud microstructure, pollution plumes, and surface long-term monitoring.

X.-Y. Yu

2010-10-01

76

pH-sensitivity of fast responsive superporous hydrogels.  

Science.gov (United States)

Stimuli-sensitive hydrogels (or smart hydrogels) are hydrogels that swell or shrink in response to small changes in environmental conditions in which they are placed. While the extent of swelling or shrinking may be large, the kinetics of such changes is slow, since the diffusion of water into and out of the hydrogel is a slow process. To obtain fast responses, we have prepared superporous hydrogels (SPHs) that can swell or shrink extremely fast regardless of their dimensions. The swelling and shrinking are orders of magnitude faster than expected for a nonporous hydrogel of the same dimensions. Water molecules are taken up into the SPHs by capillary forces, and this makes water uptake much faster than diffusion. The swelling ratio of the poly(acrylamide-co-acrylic acid) (p(AM-co-AA)) SPHs was dependent on the pH and ionic strength of the medium. The effect of pH was most pronounced and the effect of ionic strength was observed at all pH values. SPHs made at pH around 5 showed transient maximum swelling when exposed to pH 1.2 medium due to the transient low hydrogen ion concentration inside the swelling SPHs. The p(AM-co-AA) SPHs showed repeated swelling and shrinking by alternating the medium pH between 1.2 and 7.5, and the changes in swelling ratio was quite fast occurring in a matter of a minute. This fast sensitivity may make the stimuli sensitive hydrogels useful in many applications not previously possible. These materials can be used for applications where a single-piece hydrogel is more advantageous than hydrogel microparticulates. PMID:11261878

Gemeinhart, R A; Chen, J; Park, H; Park, K

2000-01-01

77

Fast and Slow Transient Response of WECS with Simultaneous Actions  

Directory of Open Access Journals (Sweden)

Full Text Available This paper details the transient operation of a wind energy conversion system (WECS used simultaneously as an ac- tive filter and power generator. This study is intended to address the system response to two types of transient phenomena: voltage dips (fast transients and wind speed variations (slow transients. The system response to voltage dips is governed by the electrical system dynamics and control method and results in the evaluation of the WECS low-voltage ride through capability. The study of the system response to wind speed variations requires a complete me- chanical model to be included. Simulation results are presented for a typical WECS, and a discussion is carried out dealing with the generalization of the present work to other configurations.

M.Amarendra

2012-03-01

78

Wave-induced Hydroelastic response of fast monohull ships  

DEFF Research Database (Denmark)

High-speed ships are weight sensitive structures and high strength steel, aluminium or composites are preferred building materials. it is characteristic for these materials that they result in larger hull flexibility than more conventional materials. Therefore, for large fast ships the lowest natural frequencies of the global hull modes can be relatively low compared to the frequency of wave encounter. In the present paper the effect of hull flexibility on the wave-induced springing vibrations is investigated in stationary stochastic seaways. The calculations are performed within the framework of a quadratic strip theory formulated in the frequency domain. The springing response is thereby excited partly be resonance and partly by non-linear excitation. Special emphasis is given to the influence of springing on fatigue damage as the extreme responses even for very flexible ships are quite insensitive to the hull flexibility due to the high zero crossing periods associated with the extreme responses.

Jensen, JØrgen Juncher

1996-01-01

79

Another approach to fast neutron response of some thermoluminescent materials  

International Nuclear Information System (INIS)

Experimental data concerning fast neutron response of some thermoluminescent materials were analyzed with the aim of finding an analytical expression for their dependence on neutron energy. Both relative responses and relative thremoluminescent yields were studied, the analysis was performed for sup(nat)LiF, 7LiF, Al2O3, and CaSO4. Fitting was carried out using a non-linear least squares curve fitting program. Analytical functions for both quantities were found, their correspondence to the experimental data is discussed for energies between 0.25 and 20 MeV. The usefulness of the fitted functinons is analyzed, the expressions were used to predict relative responses for some polyenergetic sources, agreement with experimental data is discussed. The predicted dependences of thermoluminescent yields on neutron energy are also analyzed. (author)

80

Fast-response liquid-crystal lens for 3D displays  

Science.gov (United States)

Three-dimensional (3D) display has become an increasingly important technology trend for information display applications. Dozens of different 3D display solutions have been proposed. The autostereoscopic 3D display based on lenticular microlens array is a promising approach, and fast-switching microlens array enables this system to display both 3D and conventional 2D images. Here we report two different fast-response microlens array designs. The first one is a blue phase liquid crystal lens driven by the Pedot: PSS resistive film electrodes. This BPLC lens exhibits several attractive features, such as polarization insensitivity, fast response time, simple driving scheme, and relatively low driving voltage, as compared to other BPLC lens designs. The second lens design has a double-layered structure. The first layer is a polarization dependent polymer microlens array, and the second layer is a thin twisted-nematic (TN) liquid crystal cell. When the TN cell is switched on/off, the traversing light through the polymeric lens array is either focused or defocused, so that 2D/3D images are displayed correspondingly. This lens design has low driving voltage, fast response time, and simple driving scheme. Simulation and experiment demonstrate that the performance of both switchable lenses meet the requirement of 3D display system design.

Liu, Yifan; Ren, Hongwen; Xu, Su; Li, Yan; Wu, Shin-Tson

2014-02-01

 
 
 
 
81

Analog-assisted digital low dropout regulator with fast transient response and low output ripple  

Science.gov (United States)

An analog-assisted digital low dropout regulator (AAD-LDO) is proposed to solve the problems of a slow transient response and a large output ripple in a conventional digital LDO. In the AAD-LDO, a fast-response auxiliary analog LDO is added to the digital LDO in parallel. Compared with the digital LDO, the measured AAD-LDO in 180 nm CMOS reduces the transient response time and the output ripple by 59 and 28%, respectively, at the same current efficiency of 97.1%. The line regulation is 15 mV/V and the load regulation is 0.63 mV/mA.

Mori, Kazuaki; Okuma, Yasuyuki; Zhang, Xin; Fuketa, Hiroshi; Sakurai, Takayasu; Takamiya, Makoto

2014-01-01

82

Fast-response pulsed voltage generator with large capacitance  

International Nuclear Information System (INIS)

Fast-response pulsed voltage generator with a capacity of up to 1200 pF is described. An increase in capacity is ensured through making up the stages of a pre-set number of low-induction capacitors located between two disc electrodes of the stages with spark gap electrodes in the central part. The generator employing electrodes of a 20 pF capacity spark chamber shapes pulses with an amplitude of 100 kv, front of 30 nsec and starting delay of 65+-5 nsec

83

Photoconductive Detectors with Fast Temporal Response for Laser Produced Plasma Experiments  

International Nuclear Information System (INIS)

Processes during laser plasma experiments typically have time scales that are less than 100 ps. The measurement of these processes requires X-ray detectors with fast temporal resolution. We have measured the temporal responses and linearity of several different X-ray sensitive Photoconductive Detectors (PCDs). The active elements of the detectors investigated include both diamond (natural and synthetic) and GaAs crystals. The typical time responses of the GaAs PCDs are approximately 60 ps, respectively. Some characterizations using X-ray light from a synchrotron light source are presented

84

Fast sensors for time-of-flight imaging applications.  

Science.gov (United States)

The development of sensors capable of detecting particles and radiation with both high time and high positional resolution is key to improving our understanding in many areas of science. Example applications of such sensors range from fundamental scattering studies of chemical reaction mechanisms through to imaging mass spectrometry of surfaces, neutron scattering studies aimed at probing the structure of materials, and time-resolved fluorescence measurements to elucidate the structure and function of biomolecules. In addition to improved throughput resulting from parallelisation of data collection - imaging of multiple different fragments in velocity-map imaging studies, for example - fast image sensors also offer a number of fundamentally new capabilities in areas such as coincidence detection. In this Perspective, we review recent developments in fast image sensor technology, provide examples of their implementation in a range of different experimental contexts, and discuss potential future developments and applications. PMID:24002354

Vallance, Claire; Brouard, Mark; Lauer, Alexandra; Slater, Craig S; Halford, Edward; Winter, Benjamin; King, Simon J; Lee, Jason W L; Pooley, Daniel E; Sedgwick, Iain; Turchetta, Renato; Nomerotski, Andrei; John, Jaya John; Hill, Laura

2014-01-14

85

A Space/Fast-Time Adaptive Monopulse Technique  

Directory of Open Access Journals (Sweden)

Full Text Available Mainbeam jamming poses a particularly difficult challenge for conventional monopulse radars. In such cases spatially adaptive processing provides some interference suppression when the target and jammer are not exactly coaligned. However, as the target angle approaches that of the jammer, mitigation performance is increasingly hampered and distortions are introduced into the resulting beam pattern. Both of these factors limit the reliability of a spatially adaptive monopulse processor. The presence of coherent multipath in the form of terrain-scattered interference (TSI, although normally considered a nuisance, can be exploited to suppress mainbeam jamming with space/fast-time processing. A method is presented offering space/fast-time monopulse processing with distortionless spatial array patterns that can achieve improved angle estimation over spatially adaptive monopulse. Performance results for the monopulse processor are obtained for mountaintop data containing a jammer and TSI, which demonstrate a dramatic improvement in performance over conventional monopulse and spatially adaptive monopulse.

Williams Douglas B

2006-01-01

86

Directional Detection of Fast Neutrons Using a Time Projection Chamber  

Energy Technology Data Exchange (ETDEWEB)

Spontaneous fission in Special Nuclear Material (SNM) such as plutonium and highly enriched uranium (HEU) results in the emission of neutrons with energies in the MeV range (hereafter 'fast neutrons'). These fast neutrons are largely unaffected by the few centimeters of intervening high-Z material that would suffice for attenuating most emitted gamma rays, while tens of centimeters of hydrogenous materials are required to achieve substantial attenuation of neutron fluxes from SNM. Neutron detectors are therefore an important complement to gamma-ray detectors in SNM search and monitoring applications. The rate at which SNM emits fast neutrons varies from about 2 per kilogram per second for typical HEU to some 60,000 per kilogram per second for metallic weapons grade plutonium. These rates can be compared with typical sea-level (cosmogenic) neutron backgrounds of roughly 5 per second per square meter per steradian in the relevant energy range [1]. The fact that the backgrounds are largely isotropic makes directional neutron detection especially attractive for SNM detection. The ability to detect, localize, and ultimately identify fast neutron sources at standoff will ultimately be limited by this background rate. Fast neutrons are particularly well suited to standoff detection and localization of SNM or other fast neutrons sources. Fast neutrons have attenuation lengths of about 60 meters in air, and retain considerable information about their source direction even after one or two scatters. Knowledge of the incoming direction of a fast neutron, from SNM or otherwise, has the potential to significantly improve signal to background in a variety of applications, since the background arriving from any one direction is a small fraction of the total background. Imaging or directional information therefore allows for source detection at a larger standoff distance or with shorter dwell times compared to nondirectional detectors, provided high detection efficiency can be maintained. Directional detection of neutrons has been previously considered for applications such as controlled fusion neutron imaging [2], nuclear fuel safety research [3], imaging of solar neutrons and SNM [4], and in nuclear science [5]. The use of scintillating crystals and fibers has been proposed for directional neutron detection [6]. Recently, a neutron scatter camera has been designed, constructed, and tested for imaging of fast neutrons, characteristic for SNM material fission [7]. The neutron scatter camera relies on the measurement of the proton recoil angle and proton energy by time of flight between two segmented solid-state detectors. A single-measurement result from the neutron scatter camera is a ring containing the possible incident neutron direction. Here we describe the development and commissioning of a directional neutron detection system based on a time projection chamber (TPC) detector. The TPC, which has been widely used in particle and nuclear physics research for several decades, provides a convenient means of measuring the full 3D trajectory, specific ionization (i.e particle type) and energy of charged particles. For this application, we observe recoil protons produced by fast neutron scatters on protons in hydrogen or methane gas. Gas pressures of a few ATM provide reasonable neutron interaction/scattering rates.

Bowden, N; Heffner, M; Carosi, G; Carter, D; Foxe, M; Jovanovic, I

2009-06-03

87

Fast computation of recurrences in long time series  

Science.gov (United States)

The quadratic time complexity of calculating basic RQA measures, doubling the size of the input time series leads to a quadrupling in operations, impairs the fast computation of RQA in many application scenarios. As an example, we analyze the Potsdamer Reihe, an ongoing non-interrupted hourly temperature profile since 1893, consisting of 1,043,112 data points. Using an optimized single-threaded CPU implementation this analysis requires about six hours. Our approach conducts RQA for the Potsdamer Reihe in five minutes. We automatically split a long time series into smaller chunks (Divide) and distribute the computation of RQA measures across multiple GPU devices. To guarantee valid RQA results, we employ carryover buffers that allow sharing information between pairs of chunks (Recombine). We demonstrate the capabilities of our Divide and Recombine approach to process long time series by comparing the runtime of our implementation to existing RQA tools. We support a variety of platforms by employing the computing framework OpenCL. Our current implementation supports the computation of standard RQA measures (recurrence rate, determinism, laminarity, ratio, average diagonal line length, trapping time, longest diagonal line, longest vertical line, divergence, entropy, trend) and also calculates recurrence times. To utilize the potential of our approach for a number of applications, we plan to release our implementation under an Open Source software license. It will be available at http://www.gfz-potsdam.de/fast-rqa/. Since our approach allows to compute RQA measures for a long time series fast, we plan to extend our implementation to support multi-scale RQA.

Rawald, Tobias; Sips, Mike; Marwan, Norbert; Dransch, Doris

2014-05-01

88

Metabolomics of Ramadan fasting: an opportunity for the controlled study of physiological responses to food intake  

Science.gov (United States)

High-throughput screening techniques that analyze the metabolic endpoints of biological processes can identify the contributions of genetic predisposition and environmental factors to the development of common diseases. Studies applying controlled physiological challenges can reveal dysregulation in metabolic responses that may be predictive for or associated with these diseases. However, large-scale epidemiological studies with well controlled physiological challenge conditions, such as extended fasting periods and defined food intake, pose logistic challenges. Culturally and religiously motivated behavioral patterns of life style changes provide a natural setting that can be used to enroll a large number of study volunteers. Here we report a proof of principle study conducted within a Muslim community, showing that a metabolomics study during the Holy Month of Ramadan can provide a unique opportunity to explore the pre-prandial and postprandial response of human metabolism to nutritional challenges. Up to five blood samples were obtained from eleven healthy male volunteers, taken directly before and two hours after consumption of a controlled meal in the evening on days 7 and 26 of Ramadan, and after an over-night fast several weeks after Ramadan. The observed increases in glucose, insulin and lactate levels at the postprandial time point confirm the expected physiological response to food intake. Targeted metabolomics further revealed significant and physiologically plausible responses to food intake by an increase in bile acid and amino acid levels and a decrease in long-chain acyl-carnitine and polyamine levels. A decrease in the concentrations of a number of phospholipids between samples taken on days 7 and 26 of Ramadan shows that the long-term response to extended fasting may differ from the response to short-term fasting. The present study design is scalable to larger populations and may be extended to the study of the metabolic response in defined patient groups such as individuals with type 2 diabetes. PMID:24906381

2014-01-01

89

Metabolomics of Ramadan fasting: an opportunity for the controlled study of physiological responses to food intake.  

Science.gov (United States)

High-throughput screening techniques that analyze the metabolic endpoints of biological processes can identify the contributions of genetic predisposition and environmental factors to the development of common diseases. Studies applying controlled physiological challenges can reveal dysregulation in metabolic responses that may be predictive for or associated with these diseases. However, large-scale epidemiological studies with well controlled physiological challenge conditions, such as extended fasting periods and defined food intake, pose logistic challenges. Culturally and religiously motivated behavioral patterns of life style changes provide a natural setting that can be used to enroll a large number of study volunteers. Here we report a proof of principle study conducted within a Muslim community, showing that a metabolomics study during the Holy Month of Ramadan can provide a unique opportunity to explore the pre-prandial and postprandial response of human metabolism to nutritional challenges. Up to five blood samples were obtained from eleven healthy male volunteers, taken directly before and two hours after consumption of a controlled meal in the evening on days 7 and 26 of Ramadan, and after an over-night fast several weeks after Ramadan. The observed increases in glucose, insulin and lactate levels at the postprandial time point confirm the expected physiological response to food intake. Targeted metabolomics further revealed significant and physiologically plausible responses to food intake by an increase in bile acid and amino acid levels and a decrease in long-chain acyl-carnitine and polyamine levels. A decrease in the concentrations of a number of phospholipids between samples taken on days 7 and 26 of Ramadan shows that the long-term response to extended fasting may differ from the response to short-term fasting. The present study design is scalable to larger populations and may be extended to the study of the metabolic response in defined patient groups such as individuals with type 2 diabetes. PMID:24906381

Mathew, Sweety; Krug, Susanne; Skurk, Thomas; Halama, Anna; Stank, Antonia; Artati, Anna; Prehn, Cornelia; Malek, Joel A; Kastenmüller, Gabi; Römisch-Margl, Werner; Adamski, Jerzy; Hauner, Hans; Suhre, Karsten

2014-01-01

90

A CMOS integrated timing discriminator circuit for fast scintillation counters  

Energy Technology Data Exchange (ETDEWEB)

Based on a zero-crossing discriminator using a CR differentiation network for pulse shaping, a new CMOS integrated timing discriminator circuit is proposed for fast (t{sub r} {ge} 2 ns) scintillation counters at the cooler synchrotron COSY-Juelich. By eliminating the input signal`s amplitude information by means of an analog continuous-time divider, a normalized pulse shape at the zero-crossing point is gained over a wide dynamic input amplitude range. In combination with an arming comparator and a monostable multivibrator this yields in a highly precise timing discriminator circuit, that is expected to be useful in different time measurement applications. First measurement results of a CMOS integrated logarithmic amplifier, which is part of the analog continuous-time divider, agree well with the corresponding simulations. Moreover, SPICE simulations of the integrated discriminator circuit promise a time walk well below 200 ps (FWHM) over a 40 dB input amplitude dynamic range.

Jochmann, M.W. [Forschungszentrum Juelich (Germany). Zentrallabor fuer Elektronik

1998-06-01

91

A CMOS integrated timing discriminator circuit for fast scintillation counters  

International Nuclear Information System (INIS)

Based on a zero-crossing discriminator using a CR differentiation network for pulse shaping, a new CMOS integrated timing discriminator circuit is proposed for fast (tr ? 2 ns) scintillation counters at the cooler synchrotron COSY-Juelich. By eliminating the input signal's amplitude information by means of an analog continuous-time divider, a normalized pulse shape at the zero-crossing point is gained over a wide dynamic input amplitude range. In combination with an arming comparator and a monostable multivibrator this yields in a highly precise timing discriminator circuit, that is expected to be useful in different time measurement applications. First measurement results of a CMOS integrated logarithmic amplifier, which is part of the analog continuous-time divider, agree well with the corresponding simulations. Moreover, SPICE simulations of the integrated discriminator circuit promise a time walk well below 200 ps (FWHM) over a 40 dB input amplitude dynamic range

92

Fasting induces a biphasic adaptive metabolic response in murine small intestine  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The gut is a major energy consumer, but a comprehensive overview of the adaptive response to fasting is lacking. Gene-expression profiling, pathway analysis, and immunohistochemistry were therefore carried out on mouse small intestine after 0, 12, 24, and 72 hours of fasting. Results Intestinal weight declined to 50% of control, but this loss of tissue mass was distributed proportionally among the gut's structural components, so that the microarrays' tissue base remained unaffected. Unsupervised hierarchical clustering of the microarrays revealed that the successive time points separated into distinct branches. Pathway analysis depicted a pronounced, but transient early response that peaked at 12 hours, and a late response that became progressively more pronounced with continued fasting. Early changes in gene expression were compatible with a cellular deficiency in glutamine, and metabolic adaptations directed at glutamine conservation, inhibition of pyruvate oxidation, stimulation of glutamate catabolism via aspartate and phosphoenolpyruvate to lactate, and enhanced fatty-acid oxidation and ketone-body synthesis. In addition, the expression of key genes involved in cell cycling and apoptosis was suppressed. At 24 hours of fasting, many of the early adaptive changes abated. Major changes upon continued fasting implied the production of glucose rather than lactate from carbohydrate backbones, a downregulation of fatty-acid oxidation and a very strong downregulation of the electron-transport chain. Cell cycling and apoptosis remained suppressed. Conclusion The changes in gene expression indicate that the small intestine rapidly looses mass during fasting to generate lactate or glucose and ketone bodies. Meanwhile, intestinal architecture is maintained by downregulation of cell turnover.

Evelo Chris TA

2007-10-01

93

Modelling of tokamak discharges with the fast central response to the boundary plasma perturbations  

International Nuclear Information System (INIS)

One of the fundamental phenomena in tokamak plasmas is the fast propagation of electron temperature perturbation from the boundary to the plasma core (faster than the characteristic transport time). This phenomenon has been observed in different tokamak (and stellarator) experiments: fast plasma core response to the L-H mode transition, fast cold pulse propagation after laser impurity ablation or deuterium pellet injection and some others. Standard diffusive model of local turbulent transport fails to describe these phenomena. It was the reason for the conclusion on a non-local nature of transport in tokamaks. Results of detailed simulations of some discharges with the fast central responses to the boundary perturbations of different nature are presented in this work. Role of different transport mechanisms is investigated. modelling was performed by the ASTRA transport code. The model takes into consideration the behavior of the plasma neutral component and neutrals recycling at the wall. It is shown that the effect of fast central response in discharges under consideration can be explained without the assumption on the non-local character of transport processes in tokamaks. This effect may be attributed to the behavior of the neutral plasma component, which propagation time across the plasma column is sufficiently short (less than 100 ? s). A rapid change in the neutral flux into the plasma column may somewhat affect the plasma energy balance in the whole plasma croma energy balance in the whole plasma cross section almost simultaneously. For example, the rapid electron temperature increase in the plasma core after the fast L-H mode transition can be explained by the reduction of the cold electron source caused by the decrease of neutral flux in plasma. An opposite effect of fast drop of the core electron temperature after deuterium pellet injection may be explained by the rise of deuterium atom density in the plasma core with corresponding increase of ionization source of cold electrons. So, the neutral plasma component is responsible for the visible coupling plasma edge and the core in considered experiments in time interval just after events. (author)

94

Equipment for fast neutron time-of-flight experiments  

International Nuclear Information System (INIS)

A 3-MeV-pulsed Van de Graaff has been built for this laboratory by the High Voltage Engineering Corporation of Boston, United States of America. It is designed to give pulses of 1 ns duration at a repetition frequency of 1 MHz and a current in the pulse of 10 mA. This machine is to be used for fast neutron spectroscopy and a system of electronics for this purpose has been devised. The system is intended to record time intervals up to 1?s with a resolution of ?3 ns. The timing cycle is started by a start pulse from the neutron detector. The stop pulse is derived from the beam, and delayed by 1?s. The start and stop pulses are fed to a time expander which expands the time interval between the pulses by a factor of ?250. The expanded time interval is then recorded in digital form on 16-track magnetic tape. (author)

95

Pediatric fasting times before surgical and radiologic procedures: benchmarking institutional practices against national standards.  

Science.gov (United States)

Prolonged preoperative fasting can be associated with adverse outcomes, particularly in children. Our aims were to assess the time pediatric patients fasted prior to surgical or radiologic procedures and evaluate whether fasting (NPO) orders complied with national guidelines. We measured NPO start time, time of last intake, and time test or surgery was scheduled, took place, or was cancelled in 219 pediatric patients. Findings demonstrate that pediatric patients experienced prolonged fasting before procedures and that the majority of NPO orders were non-compliant with national guidelines. We have developed strategies to reduce fasting times and ensure compliance with recommended national fasting standards. PMID:24365219

Williams, Catherine; Johnson, Pat A; Guzzetta, Cathie E; Guzzetta, Philip C; Cohen, Ira Todd; Sill, Anne M; Vezina, Gilbert; Cain, Sherry; Harris, Christine; Murray, Jodi

2014-01-01

96

Verification of the CNGS timing system using fast diamond detectors  

International Nuclear Information System (INIS)

A new fast diagnostic tool was installed in the CNGS facility in 2011 following the neutrino time-of-flight results published by OPERA in September 2011. Among others, four polycrystalline CVD (pCVD) diamond detectors were placed in the secondary beam line about 1200 m downstream of the CNGS target in order to measure the beam structure of the muons which are produced together with the muon neutrinos. Upstream of the CNGS target, a fast beam current transformer measures the proton beam structure. The sub-nanosecond single-pulse time resolution of pCVD diamond for a minimum ionising particle in combination with a GPS system allows the measurement of the GPS timing of individual secondary particle bunches crossing these detectors with a precision of < 1 ns. The complicated structure of the CNGS muon beam in 2011 necessitates the combination of adjacent bunches in order to compare the proton beam structure with the muon beam structure. An analysis of the detector signals was carried out, which provides an independent timing measurement at CERN with a precision of 1.2 ns. Uncertainties from other sources as cable lengths add up to 3.4 ns, resulting in an overall precision of 3.6 ns. The distance between the beam current transformer and the diamond detectors has been measured to (1859.95±0.02) cm. The nominal time-of-flight of (6205.3±1.7) ns for a 17 GeV/c muon, as present in the CNGS muons beam, falls within the uncertainties of the measured time-of-flight of (6205.2±the measured time-of-flight of (6205.2±3.6) ns. Hence, the GPS timing measurements performed at CERN are consistent.

97

PRMT5 modulates the metabolic response to fasting signals.  

Science.gov (United States)

Under fasting conditions, increases in circulating glucagon maintain glucose balance by promoting hepatic gluconeogenesis. Triggering of the cAMP pathway stimulates gluconeogenic gene expression through the PKA-mediated phosphorylation of the cAMP response element binding (CREB) protein and via the dephosphorylation of the latent cytoplasmic CREB regulated transcriptional coactivator 2 (CRTC2). CREB and CRTC2 activities are increased in insulin resistance, in which they promote hyperglycemia because of constitutive induction of the gluconeogenic program. The extent to which CREB and CRTC2 are coordinately up-regulated in response to glucagon, however, remains unclear. Here we show that, following its activation, CRTC2 enhances CREB phosphorylation through an association with the protein arginine methyltransferase 5 (PRMT5). In turn, PRMT5 was found to stimulate CREB phosphorylation via increases in histone H3 Arg2 methylation that enhanced chromatin accessibility at gluconeogenic promoters. Because depletion of PRMT5 lowers hepatic glucose production and gluconeogenic gene expression, these results demonstrate how a chromatin-modifying enzyme regulates a metabolic program through epigenetic changes that impact the phosphorylation of a transcription factor in response to hormonal stimuli. PMID:23671120

Tsai, Wen-Wei; Niessen, Sherry; Goebel, Naomi; Yates, John R; Guccione, Ernesto; Montminy, Marc

2013-05-28

98

Response of fast-reactor core subassemblies to pressure transients  

International Nuclear Information System (INIS)

An Arbitrary Lagrangian-Eulerian (ALE) finite element method for analyzing the transient, nonlinear fluid-structure interaction in fast-reactor core subassemblies is presented. The method combines the basic attributes of the finite element technique-namely, ease in modeling complex geometries and in mixing fluid elements with structural elements - and the flexibility in moving the fluid mesh offered by the ALE description. The result of this combination is a very versatile modeling technique which permits accommodation of large fluid and structure displacements and logically simple, but accurate fluid-structure coupling. Numerical results are presented to illustrate the effectiveness of the proposed method. These include the response of a single hexagonal duct to internal, static or dynamic, pressure loading for which numerical predictions are compared to experimental data, and applications to clustered hexcans. (orig.)

99

Modeling of Responses and Response Times with the Package cirt  

Directory of Open Access Journals (Sweden)

Full Text Available In computerized testing, the test takers’ responses as well as their response times on the items are recorded. The relationship between response times and response accuracies is complex and varies over levels of observation. For example, it takes the form of a tradeoff between speed and accuracy at the level of a fixed person but may become a positive correlation for a population of test takers. In order to explore such relationships and test hypotheses about them, a conjoint model is proposed. Item responses are modeled by a two-parameter normal-ogive IRT model and response times by a lognormal model. The two models are combined using a hierarchical framework based on the fact that response times and responses are nested within individuals. All parameters can be estimated simultaneously using an MCMC estimation approach. A R-package for the MCMC algorithm is presented and explained.

Jean-Paul Fox

2007-02-01

100

The photocurrent response of human cones is fast and monophasic  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The precise form of the light response of human cone photoreceptors in vivo has not been established with certainty. To investigate the response shape we compare the predictions of a recent model of transduction in primate cone photoreceptors with measurements extracted from human cones using the paired-flash electroretinogram method. As a check, we also compare the predictions with previous single-cell measurements of ground squirrel cone responses. Results The predictions of the model provide a good description of the measurements, using values of parameters within the range previously determined for primate retina. The dim-flash response peaks in about 20 ms, and flash responses at all intensities are essentially monophasic. Three time constants in the model are extremely short: the two time constants for inactivation (of visual pigment and of transducin/phosphodiesterase are around 3 and 10 ms, and the time constant for calcium equilibration lies in the same range. Conclusion The close correspondence between experiment and theory, using parameters previously derived for recordings from macaque retina, supports the notion that the electroretinogram approach and the modelling approach both provide an accurate estimate of the cone photoresponse in the living human eye. For reasons that remain unclear, the responses of isolated photoreceptors from the macaque retina, recorded previously using the suction pipette method, are considerably slower than found here, and display biphasic kinetics.

Lamb TD

2006-04-01

 
 
 
 
101

Modeling of Responses and Response Times with the Package CIRT  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In computerized testing, the test takers' responses as well as their response times on the items are recorded. The relationship between response times and response accuracies is complex and varies over levels of observation. For example, it takes the form of a tradeoff between speed and accuracy at the level of a fixed person but may become a positive correlation for a population of test takers. In order to explore such relationships and test hypotheses about them, a conjoint model is propose...

Jean-Paul Fox; Rinke Klein Entink; Wim van der Linden

2007-01-01

102

A fast preamplifier concept for SiPM-based time-of-flight PET detectors  

International Nuclear Information System (INIS)

Silicon photomultipliers (SiPMs) offer high gain and fast response to light, making them interesting for fast timing applications such as time-of-flight (TOF) PET. To fully exploit the potential of these photosensors, dedicated preamplifiers that do not deteriorate the rise time and signal-to-noise ratio are crucial. Challenges include the high sensor capacitance, typically >300 pF for a 3 mm×3 mm SiPM sensor, as well as oscillation issues. Here we present a preamplifier concept based on low noise, high speed transistors, designed for optimum timing performance. The input stage consists of a transimpedance common-base amplifier with a very low input impedance even at high frequencies, which assures a good linearity and avoids that the high detector capacitance affects the amplifier bandwidth. The amplifier has a fast timing output as well as a ‘slow’ energy output optimized for determining the total charge content of the pulse. The rise time of the amplifier is about 300 ps. The measured coincidence resolving time (CRT) for 511 keV photon pairs using the amplifiers in combination with 3 mm×3 mm SiPMs (Hamamatsu MPPC-S10362-33-050C) coupled to 3 mm×3 mm×5 mm LaBr3:Ce and LYSO:Ce crystals equals 95 ps FWHM and 138 ps FWHM, respectively.

103

On fast-decodable space-time block codes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We focus on full-rate, fast-decodable space-time block codes (STBCs) for 2x2 and 4x2 multiple-input multiple-output (MIMO) transmission. We first derive conditions for reduced-complexity maximum-likelihood decoding, and apply them to a unified analysis of two families of 2x2 STBCs that were recently proposed. In particular, we describe a reduced-complexity sphere decoding algorithm suitable for QAM signal constellations. Next, we derive a novel reduced-complexity 4x2 STBC, a...

Biglieri, Ezio; Hong, Yi; Viterbo, Emanuele

2009-01-01

104

A fast rise time high voltage pulse burst generator  

International Nuclear Information System (INIS)

A novel type of pulse generator for kicker magnet excitation is described. Series connected thyratrons and coaxial lines are used to produce a burst of four 20 kv, 800 a, fixed length pulses of fast rise and fall time. Inter-pulse spacing is independently adjustable, typically between 200 ns and 20 ?s. The coaxial lines are simultaneously resonantly charged to 40 kv in 1 ms, and the subsequent triggered discharge of each pulse forming network (PFN) initiates the pulse bursts which may be produced at a repetition frequency of 100 hz. This paper presents some of the results obtained with a prototype pulse generator

105

RISE: a fast-readout imager for exoplanet transit timing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

By the precise timing of the low amplitude (0.005 - 0.02 magnitude) transits of exoplanets around their parent star it should be possible to infer the presence of other planetary bodies in the system down to Earth-like masses. We describe the design and construction of RISE, a fast-readout frame transfer camera for the Liverpool Telescope designed to carry out this experiment. The results of our commissioning tests are described as well as the data reduction procedure necess...

Steele, I. A.; Bates, S. D.; Gibson, N.; Keenan, F.; Meaburn, J.; Mottram, C. J.; Pollacco, D.; Todd, I.

2008-01-01

106

Time response of microencapsulated liquid crystals. 1. Steady state characteristics  

International Nuclear Information System (INIS)

The purpose of this work is to investigate steady state characteristics as a first step to develop fast quantitative thermometer using thermochromic liquid crystals, especially to evaluate inherent response time. Spectral characteristics are measured by means of a spectrometer, and their optical properties are evaluated by CIE 1931 standard colorimetric system, XYZ. Wavelength of maximum intensity and hue value show good correlation between temperature. (author)

107

Repetitive trigger generator with low jitter and fast rise time  

International Nuclear Information System (INIS)

A repetitive trigger generator with low jitter and fast rise time is introduced and the principle of designing and choosing the units in the trigger generator are given. The trigger generator is composed with control unit, charging unit and pulse forming unit. The pulse forming unit is a capacitor-fast-discharging trigger with hydrogen thyratron. The repetitive rate of trigger can reach 100 pps (pulses per second), the delay time is about 225 ns, the jitter is about 1 ns, the rise time is about 26 ns and the FWHM (full-width at half-magnitude) is about 70 ns. The amplitude of electrical pulse on the load with high impedance is about -40 kV at 100 pps, -51 kV at 50 pps, -60 kV at singe shot, respectively. The micro-closing of hydrogen thyratron is discussed. As the anode voltage increases, the duration of micro-closing increases and the resistance of switch decreases. The effect of heating voltage on the breakdown characteristic of hydrogen thyratron is discussed as well. (authors)

108

High stability fast neutron time-of-flight spectrometer  

International Nuclear Information System (INIS)

A fast neutron time-of-flight spectrometer with electronic system of parameter stabilization, in which bench mark signals transmit in the same circuits that the signals of the processes investigated, is described. The time-of-flight spectrometer is developed on the basis of a low-voltage accelerator, tritium target of which serves as a neutron source. As a result a twofold improvement in the instrumental resolution in long-time measurements is achieved, being 1.2 ns. On the flight basis of 7 m the energy width of neutron beam equalling 200 ± 12 keV at the average neutron energy 14.6 MeV has been measured

109

The electro-optic properties of a vertically aligned fast response liquid crystal display with three-electrode driving  

International Nuclear Information System (INIS)

The electro-optic properties of a vertically aligned liquid crystal device with a three-electrode structure for fast response applications have been studied. The fast response is realized by a three-electrode structure that can produce an electric field horizontally and vertically, alternately to turn the liquid crystal cell on and off so that both the turn-on and turn-off processes are driven by the electric field. The response time, transmittance-voltage curve, and the bias effect were characterized for cells with various stripe widths/gaps. A simple theoretical model was used to explain the bias voltage dependence of the transmission with good agreement with the experimental findings. A total response time (rise-time plus fall-time) of 1.88 ms was obtained

110

Response of a single-crystal diamond detector to fast neutrons  

International Nuclear Information System (INIS)

Bi-parametric (neutron time of flight and deposited energy) measurements using a Single-crystal Diamond Detector (4.5 × 4.5 × 0.5 mm3 active volume) were performed at the nTOF neutron facility at CERN. The time structure of the neutron beam combined with the long flight path allowed for measurements of the diamond detector response to quasi monoenergetic neutrons in the energy range up to 40 MeV. Deposited energy spectra were compared to MCNPX simulations using different cross section libraries. The results can be used for the interpretation of Single-crystal Diamond Detector measurements of fast neutrons at spallation neutron sources

111

Response of a fast reactor to a neutron source  

International Nuclear Information System (INIS)

In the multigroup approximation, a fast homogeneous bare reactor has properties which for each spatial harmonic can be summed up by a matrix A. A classification of reactors is made as a function of this structure which varies with the considered medium. The eigenvalues of A are the decay constants obtained with a pulsed neutron source. In the spectrum of these eigenvalues, is often a marked line related to a fundamental. The line is not always single. The neutron spectrum may be calculated from the eigenvectors. A neutron source, according to its spectrum, excites more or less the various energy harmonics. The detector, for its part, does not have the same response to all harmonics. Phenomena are symmetrical. Equations of this problem are written in matrix form and applied to sources which can be pulsed, modulated or controlled by the reactor flux. FORTRAN IV codes computing the behaviour of the detector response are described in the Appendix. For the computation of eigenvalues and eigenvectors, some of these codes use sub-routines more accurate than the usual ones. (author)

112

RISE: a fast-readout imager for exoplanet transit timing  

CERN Document Server

By the precise timing of the low amplitude (0.005 - 0.02 magnitude) transits of exoplanets around their parent star it should be possible to infer the presence of other planetary bodies in the system down to Earth-like masses. We describe the design and construction of RISE, a fast-readout frame transfer camera for the Liverpool Telescope designed to carry out this experiment. The results of our commissioning tests are described as well as the data reduction procedure necessary. We present light curves of two objects, showing that the desired timing and photometric accuracy can be obtained providing that autoguiding is used to keep the target on the same detector pixel for the entire (typically 4 hour) observing run.

Steele, I A; Gibson, N; Keenan, F; Meaburn, J; Mottram, C J; Pollacco, D; Todd, I

2008-01-01

113

Measurement of the dynamic response of differential pressure transmitters using a response time tester  

International Nuclear Information System (INIS)

AECL's response time tester (RTT) for pressure and differential-pressure (DP) transmitters provide a simple, fast and accurate means of measuring pressure transmitter step response time and response time characteristics as defined in ISA Standard ISA-S67.06. The step response method of measuring response time is used by all prominent sensor suppliers and provides a result that is readily understood. The measurement of response time characteristics, which includes the transfer function, provides a complete and sensitive characterization of the dynamic response of the sensor that can be used to predict the response to ramps or any other transient. The AECL Model 200 RTT uses standard instrument air as the source of test pressure, and is suitable for testing transmitters that operate at pressures less than 650 kPa. It can accurately measure step response times in the range of 20 to 2000 ms. It is thus capable of measuring the response times of most of the pressure instruments in the CANDU safety systems. The Model 200 RTT is completely contained in a cabinet that can be easily moved on built-in shock-absorbent wheels, to facilitate testing transmitter while on the bench or mounted on the instrument rack. The RTT comprises pressurized components in the front end, and computerized data acquisition components and analysis software in the back end. Tests are conducted by switching the pressure applied to the transmitter between two values using a long-life, fast acting 3-wayalues using a long-life, fast acting 3-way solenoid valve. The actual pressure applied to the transmitter is measured with a high-frequency reference transducer. Once the operator has connected the air supply and transmitter, and set the test pressures, the actual testing and analysis proceeds automatically. Four sets of tests are conducted. A number of comparisons, as required by ISA-S67.06, are made to verify that: the transmitter is linear with respect to direction and rate of change; and the results are consistent between two diverse test methods. The broadband noise tests are used to find the transfer function (all the significant time constants) of the transmitter. Given the transfer function, the expected response to a step input can be computed and compared to the measured step response, thus verifying both measurements. The results are summarized and printed on the built-in printer. Files are saved to disk for later review. (author)

114

Only signaling modules that discriminate sharply between stimulatory and nonstimulatory inputs require basal signaling for fast cellular responses  

Science.gov (United States)

In many types of cells, binding of molecules to their receptors enables cascades of intracellular chemical reactions to take place (signaling). However, a low level of signaling also occurs in most unstimulated cells. Such basal signaling in resting cells can have many functions, one of which is that it is thought to be required for fast cellular responses to external stimuli. A mechanistic understanding of why this is true and which features of cellular signaling networks make basal signaling necessary for fast responses is unknown. We address this issue by obtaining the time required for activation of common types of cell signaling modules with and without basal signaling. Our results show that the absence of basal signaling does not have any dramatic effects on the response time for signaling modules that exhibit a graded response to increasing stimulus levels. In sharp contrast, signaling modules that exhibit sharp dose-response curves which discriminate sensitively between stimuli to which the cell needs to respond and low-grade inputs (or stochastic noise) require basal signaling for fast cellular responses. In such cases, we find that an optimal level of basal signaling balances the requirements for fast cellular responses while minimizing spurious activation without appropriate stimulation.

Artomov, Mykyta; Kardar, Mehran; Chakraborty, Arup K.

2010-09-01

115

A Race Model for Responses and Response Times in Tests.  

Science.gov (United States)

Latent trait models for responses and response times in tests are often pure statistical models without a close connection to features of the assumed response process. In the present paper, a new model is presented that is more closely related to assumptions about the response process. The model is based on two increasing stochastic processes. Each stochastic process represents the accumulation of knowledge with respect to one of two response options, the correct and incorrect response. Both accumulators compete and the accumulator that first exceeds a critical level determines the response. General assumptions about the accumulators result in a race between two response times that follow a bivariate Birnbaum Saunders distribution. The model can be calibrated with marginal maximum likelihood estimation. Feasibility of the estimation approach is demonstrated in a simulation study. Additionally, a test of model fit is proposed. Finally, the model will be used for the analysis of an empirical data set. PMID:25381198

Ranger, Jochen; Kuhn, Jörg-Tobias; Gaviria, José-Luis

2014-11-01

116

Synchronous timing of multi-energy fast beam extraction  

International Nuclear Information System (INIS)

Synchronous triggering of fast beams is required because the field of Kicker Magnets must rise within the open space between one beam bunch and the next. Within the Brookhaven AGS, Fast Extracted Beam (FEB) triggering2 combines nominal timing, based on beam energy with bunch-to-bunch synchronization, based on the accelerating RF waveform. During beam acceleration, a single bunch is extracted at 22 GeV/c and within the same AGS cycle, the remaining eleven bunches are extracted at 28.4 GeV/c. When the single bunch is extracted, a hole, which is left in the remaining circulating beam, can appear in random locations within the second extraction during successive AGS cycles. To overcome this problem, a synchronous RF/12 counting scheme and logic circuitry are used to keep track of the bunch positions relative to each other, and to place the hole in any desired location within the second extraction. The RF/12 signal is used also to synchronize experimenters triggers

117

Fast Turbo Codes Concatenated With Space-Time Block Codes  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, we investigate a new method for turbo codes which is dividing turbo encoder and decoder into several parallel coding and decoding blocks. These blocks work simultaneously and yield to much faster coding scheme in comparison with classical turbo codes. We compare simulation results of these new turbo codes with classical turbo codes to demonstrate that their performance is comparable with classical turbo codes, albeit they are much faster. Also, we introduce a new system by concatenating this fast turbo coding as outer code with Alamouti`s G2 space-time block coding scheme as inner code to achieve the benefits of both techniques including acceptable diversity and coding gain as well as short coding delay. We consider the performance of this new system in the block Rayleigh fading channel.

Fatemeh Afghah

2008-01-01

118

Fast minute magnetic field coil for time-resolved nanospintronics  

CERN Document Server

Nanospintronic and related research often requires the application of fast rising magnetic field pulses in the plane of the studied planar structure. We have designed and fabricated sub-milimeter-sized coils capable of delivering pulses of the magnetic field up to ~ 500 Oe in the plane of the sample with the rise time of order of 10 ns. The placement of the sample above the coil allows for an easy access to its surface with manipulators or light beams for, e.g., Kerr microscopy. We use the fabricated coil to drive magnetic domain walls in 1 ${\\mu}$ m wide permalloy wires and measure magnetic domain wall velocity as a function of the applied magnetic field.

Pawliszak, ?ukasz; Zgirski, Maciej

2014-01-01

119

Highly sensitive and fast-responsive fluorescent chemosensor for palladium: reversible sensing and visible recovery.  

Science.gov (United States)

The well-known rhodamine spiro-lactam framework offers an ideal model for the development of fluorescence-enhanced chemosensors through simple and convenient syntheses. Herein, we report a new tridentate PNO receptor, which was introduced into a rhodamine spiro-lactam system to develop Pd(2+)-chemosensor RPd4, that displayed significantly improved sensing properties for palladium. Compound RPd4 shows a very fast response time (about 5 s), high sensitivity (5 nM), and excellent specificity for Pd(2+) ions over other PGE ions (Pt(2+), Rh(3+), and Ru(3+)). In addition, RPd4 displays quite different responses to different valence states of the Pd ions, that is, very fast response towards Pd(2+) ions but slow response towards Pd(0), which may provide us with a convenient method for the selective discrimination of Pd species in different valence states. According to proof-of-concept experiments, RPd4 has potential applications in Pd(2+)-analysis in drug compounds, water, soil, and leaf samples. Owing to its good reversibility, RPd4 can also be used as a sensor material for the selective detection and visual recovery of trace Pd(2+) ions in environmental samples. PMID:22968904

Li, Honglin; Fan, Jiangli; Hu, Mingming; Cheng, Guanghui; Zhou, Danhong; Wu, Tong; Song, Fengling; Sun, Shiguo; Duan, Chunying; Peng, Xiaojun

2012-09-24

120

On fast and slow times in models with diffusion  

CERN Document Server

The linear Kelvin{Voigt operator L_\\epsilon is a typical example of wave operator L_0 perturbed by higher-order viscous terms as \\epsilonu_xxt. If P\\epsilon is a prefixed boundary value problem for L_\\epsilon, when \\epsilon = 0, L_\\epsilon turns into L_0 and P_\\epsilon into a problem P_0 with the same initial{boundary conditions of P\\epsilon. Boundary layers are missing and the related control terms depending on the fast time are negligible. In a small time interval, the wave behavior is a realistic approximation of u_\\epsilon when \\epsilon \\rightarrow 0. On the contrary, when t is large, diffusion effects should prevail and the behavior of u_\\epsilon for \\epsilon \\rightarrow 0 and t \\rightarrow 1 should be analyzed. For this, a suitable functional correspondence between the Green functions G_\\epsilon and G_0 of P_epsilon and P_0 is derived and its asymptotic behavior is rigorously examined. As a consequence, the interaction between diffusion effects and pure waves is evaluated by means of the slow time \\epsi...

De Angelis, M; Renno, P

2012-01-01

 
 
 
 
121

Bubble masks for time-encoded imaging of fast neutrons.  

Energy Technology Data Exchange (ETDEWEB)

Time-encoded imaging is an approach to directional radiation detection that is being developed at SNL with a focus on fast neutron directional detection. In this technique, a time modulation of a detected neutron signal is induced-typically, a moving mask that attenuates neutrons with a time structure that depends on the source position. An important challenge in time-encoded imaging is to develop high-resolution two-dimensional imaging capabilities; building a mechanically moving high-resolution mask presents challenges both theoretical and technical. We have investigated an alternative to mechanical masks that replaces the solid mask with a liquid such as mineral oil. Instead of fixed blocks of solid material that move in pre-defined patterns, the oil is contained in tubing structures, and carefully introduced air gaps-bubbles-propagate through the tubing, generating moving patterns of oil mask elements and air apertures. Compared to current moving-mask techniques, the bubble mask is simple, since mechanical motion is replaced by gravity-driven bubble propagation; it is flexible, since arbitrary bubble patterns can be generated by a software-controlled valve actuator; and it is potentially high performance, since the tubing and bubble size can be tuned for high-resolution imaging requirements. We have built and tested various single-tube mask elements, and will present results on bubble introduction and propagation as a function of tubing size and cross-sectional shape; real-time bubble position tracking; neutron source imaging tests; and reconstruction techniques demonstrated on simple test data as well as a simulated full detector system.

Brubaker, Erik; Brennan, James S.; Marleau, Peter; Nowack, Aaron B.; Steele, John; Sweany, Melinda; Throckmorton, Daniel J.

2013-09-01

122

Study on time response of fission gamma-ray detector  

International Nuclear Information System (INIS)

Fission gamma-ray detector using 235U or 238U as detection medium is a new-type detector for pulsed fission neutrons measurement, and it is developed for the first time in our country. Based on its working principle and equivalent circuit, the pulsed current g0(t) delivered from the detector's cathode induced by ? pulsed radiation is obtained with Monte Carlo simulation calculation. On the other hand,the pulsed current gRLC (t) delivered from the detector in output circuit is obtained from some experiments. We finally obtain the time response of the detector: rise time ?0.72 ns, fall time ?3.9 ns, FWHM ?2.08 ns, and the detector's time-response is very fast. The influences of the detector's time-response on the primary waveforms which have different time characteristics are also studied. The results show: the slower the primary waveforms, the smaller influences. If the primary waveform is Gaussian curve which FWHM is 100 ns, the influences of amplitude (A), rise time (tr), fall time(tf), and FWHM (t1/2) are less than 2%. So the fission gamma-ray detector can be used to measure the rapidly changing pulsed fission neutrons, and the measurement results don't need any deconvolution calculations. (authors)

123

EGR Control for Emisson Reduction Using Fast Response Sensors - Phase 1A  

Energy Technology Data Exchange (ETDEWEB)

The overall objective of this project was to develop exhaust gas recirculation (EGR) control strategies using fast-response Particulate Matter (PM) sensors and NOx sensors to improve the quality of particulate and gaseous emissions from diesel engines. This project initially comprised three phases: (1) Phase IA - sensor requirements to meet PM sensor specifications, NOx sensor assessment, and initial model development for EGR control; (2) Phase IB - continue development on PM and NOx sensors, integrate the sensor signals into the control simulations, and finalize model development for control strategies; and (3) Phase II - validation testing of the control strategies. Only Phase 1A was funded by DOE and executed by Honeywell. The major objectives of Phase 1A of the project included: (1) Sensor validation and operation of fast-response PM and NOx sensors; (2) Control system modeling of low-pressure EGR controls, development of control strategies, and initial evaluation of these models and strategies for EGR control in diesel engines; (3) Sensor testing to understand applicability of fast-response PM sensors in determining loading rates of the particle trap; and (4) Model validation and sensor testing under steady-state and transient operational conditions of actual engines. In particular, specific objectives included demonstration of: (1) A PM sensor response time constant (T10 - T90) of better than 100 milliseconds (msec); (2) The ability to detect PM at concentrations from 0.2 to 2 Bosch smoke number (BSN) or equivalent; (3) PM sensor accuracy to within 20% BSN over the entire range of operation; and (4) PM sensor repeatability to within 10% over the PM entire sensor range equivalent to a BSN of 0.2 to 2.

Gravel, Roland; Conley, Jason; Kittelson, David

2008-09-30

124

The generalized centroid difference method for picosecond sensitive determination of lifetimes of nuclear excited states using large fast-timing arrays  

International Nuclear Information System (INIS)

A novel method for direct electronic “fast-timing” lifetime measurements of nuclear excited states via ?–? coincidences using an array equipped with N?N equally shaped very fast high-resolution LaBr3(Ce) scintillator detectors is presented. Analogous to the mirror symmetric centroid difference method, the generalized centroid difference method provides two independent “start” and “stop” time spectra obtained by a superposition of the N(N?1)?–? time difference spectra of the N detector fast-timing system. The two fast-timing array time spectra correspond to a forward and reverse gating of a specific ?–? cascade. Provided that the energy response and the electronic time pick-off of the detectors are almost equal, a mean prompt response difference between start and stop events is calibrated and used as a single correction for lifetime determination. These combined fast-timing arrays mean ?–? time-walk characteristics can be determined for 40keV?152Eu ?-ray source. Due to reduction and cancellation of many possible systematic errors, the lifetime determination limit of the method over the total dynamic range is mainly determined by the statistics. The setup of an N=4 detector fast-timing array delivered an absolute time resolving power of 3 ps for 10 000 ?–? events per total fast timing array start and stop time spectrum. The new method is tested over the total dynamic range by the measurements of known picosecond lifetimes in standard ?-ray sources

125

Validation of the AECL response time tester  

International Nuclear Information System (INIS)

The response time of a nuclear safety (trip) channel is an important safety parameter, and an ISA standard requires nuclear operators to measure the response times of their trip instrumentation. As a major aid to facilitate this measurement, AECL (Chalk River) has designed and built a Response Time Tester (RTT) for pressure and differential-pressure transmitters. The RTT is mostly automated for ease of use, is self-checking, and complies with the requirements of ISA Standard, S67.06. The RTT was first checked for repeatability and self-consistency. Secondly, it was successfully validated against an independent measurement, namely the transfer function as measured using the natural in-service noise. This validation was done using two Bailey transmitters, which had the unfortunate property of having their response times as functions of the testing conditions. In all instances, after correcting for this Bailey nonlinearity, the RTT performance met its accuracy specification of ±(5% + 5 ms). (author)

126

Geosynchronous magnetic field responses to fast solar wind dynamic pressure enhancements: MHD field model  

Directory of Open Access Journals (Sweden)

Full Text Available We performed global MHD simulations of the geosynchronous magnetic field in response to fast solar wind dynamic pressure (Pd enhancements. Taking three Pd enhancement events in 2000 as examples, we found that the main features of the total field B and the dominant component Bz can be efficiently predicted by the MHD model. The predicted B and Bz varies with local time, with the highest level near noon and a slightly lower level around mid-night. However, it is more challenging to accurately predict the responses of the smaller component at the geosynchronous orbit (i.e., Bx and By. In contrast, the limitations of T01 model in predicting responses to fast Pd enhancements are presented.

T. R. Sun

2012-08-01

127

Intrinsic response time of graphene photodetectors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Graphene-based photodetectors are promising new devices for high-speed optoelectronic applications. However, despite recent efforts, it is not clear what determines the ultimate speed limit of these devices. Here, we present measurements of the intrinsic response time of metal-graphene-metal photodetectors with monolayer graphene using an optical correlation technique with ultrashort laser pulses. We obtain a response time of 2.1 ps that is mainly given by the short lifetime...

Urich, Alexander; Unterrainer, Karl; Mueller, Thomas

2011-01-01

128

A sex difference in the response to fasting.  

Science.gov (United States)

We determined whether women and men would alter their pattern of food intake after they had deprived themselves of food. We found that women consumed 12% less food after fasting and that men ate 28% more food after fasting. Serving more food on the test day did not increase food intake of women. Women, who ate at a nearly constant rate (linear eaters), consumed less food than those eating at an initially high speed which decreased over the course of the meal (decelerated eaters). Women decreased their food intake after fasting as their eating pattern became more linear. After fasting, men increased their food intake, and the rate at which they ate became more decelerated. Food intake of both women and men was normalized after fasting by providing feedback that encouraged them to eat according to the pattern they showed in the non-fasted condition. The results support the hypothesis that linear eating, and the dieting that elicits linear eating, are risk factors for the development of the abnormal linear eating pattern that characterizes patients with anorexia nervosa. The data also provide additional support for the use of behavioral feedback to normalize the pattern of eating for individuals who have difficulty maintaining their body weight. PMID:21514312

Zandian, Modjtaba; Ioakimidis, Ioannis; Bergh, Cecilia; Leon, Michael; Södersten, Per

2011-07-01

129

A fast near-field method for calculations of time-harmonic and transient pressures produced by triangular pistons.  

Science.gov (United States)

Analytical expressions are demonstrated for fast calculations of time-harmonic and transient near-field pressures generated by triangular pistons. These fast expressions remove singularities from the impulse response, thereby reducing the computation time and the peak numerical error with a general formula that describes the near-field pressure produced by any triangular piston geometry. The time-domain expressions are further accelerated by a time-space decomposition approach that analytically separates the spatial and temporal components of the numerically computed transient pressure. Applied to a Hanning-weighted input pulse, time-space decomposition converts each spatio-temporal integral into six spatial integral evaluations at each field point. Time-harmonic and transient calculations are evaluated for an equilateral triangle with sides equal to four wavelengths, and the resulting errors are compared to pressures obtained with exact and approximate implementations of the impulse response method. The results show that the fast near-field method achieves smaller maximum errors and is consistently faster than the impulse response and methods that approximate the impulse response. PMID:17139708

Chen, Duo; Kelly, James F; McGough, Robert J

2006-11-01

130

A LaBr3: Ce fast-timing array for DESPEC at FAIR  

Science.gov (United States)

The design of a fast-timing ?-ray detection array aimed at measuring sub-nanosecond half-lives using LaBr3:Ce scintillation crystals is presented. This array will complement novel and existing charged particle and neutron detector arrays at the low-energy branch of a fragment separator (Super-FRS) to be built within the NuSTAR collaboration as part of the future Facility for Anti-proton and Ion Research (FAIR). The array will be used in conjunction with the Advanced Implantation Detector Array (AIDA), to measure implant-decay correlations. Monte-Carlo simulations have been performed to determine the design of the proposed fast-timing array around a localised implantation point. In particular, simulations were used to determine the full-energy peak efficiencies for single cylindrical, conical and 'hybrid' detector geometries, as well as complete array configurations of 'hybrid' and ?1.5 in.×2 in. cylindrical crystals. Timing precision calculations were then used to determine the timing response for each configuration based on its simulated efficiency. An informed decision based on the simulated efficiencies and timing precision calculations allowed the optimum configuration for the array to be determined.

Roberts, Oliver J.; Bruce, Alison M.; Regan, Patrick H.; Podolyák, Zsolt; Townsley, Christopher M.; Smith, John F.; Mulholland, Kieran F.; Smith, Andrew

2014-06-01

131

Fast Intrinsic Mode Decomposition of Time Series Data  

CERN Document Server

A fast convergent iterative method is introduced in this paper to find the intrinsic mode function (IMF) components of time series data, which is faster and more predictable than the Empirical Mode Decomposition method devised by the author of Hilbert Huang Transform. The method iteratively adjust the control points on the data function corresponding to the extrema of the refining IMF, the control points of the residue function are calculated as the median of the straight line segments passing through the data control points, the residue function is then constructed as the cubic spline function of the median points. The initial residue function is simply constructed as the straight line segments passing through the extrema of the differential of the data function. The refining IMF is the difference between the data function and the improved residue function. The IMF found can also reveal the riding waves on the steep edge of the data. The program to demonstrate the method is distributed under BSD license.

Lu, Louis Yu

2008-01-01

132

A fast response variable optical attenuator based on blue phase liquid crystal.  

Science.gov (United States)

Blue phase liquid crystals (BPLCs) are promising candidates for next generation display thanks to their fast response and quasi-isotropic optical properties. By taking these advantages, we propose to introduce the material into fiber-optic applications. As an example, a BPLC based variable optical attenuator (VOA) is demonstrated with a polarization independent design. The device shows normally-off feature when no field is applied. Response time down to submillisecond scale is achieved in switching between two arbitrary attenuation states. The attenuation range is also measured from 1480 to 1550 nm, which cover the whole telecomm S-band and part of the C-band. The overall performances reach the requirements for practical use; while still have room for further improvement. Through this example, the applicability of BPLC in fiber-optic devices is presented, which may impel the development of many other photonic applications from infrared to even microwave regions. PMID:23482104

Zhu, Ge; Wei, Bing-yan; Shi, Liang-yu; Lin, Xiao-wen; Hu, Wei; Huang, Zhang-di; Lu, Yan-qing

2013-03-11

133

Sensor response time monitoring using noise analysis  

International Nuclear Information System (INIS)

Random noise techniques in nuclear power plants have been developed for system surveillance and for analysis of reactor core dynamics. The noise signals also contain information about sensor dynamics, and this can be extracted using frequency, amplitude and time domain analyses. Even though noise analysis has been used for sensor response time testing in some nuclear power plants, an adequate validation of this method has never been carried out. This paper presents the results of limited work recently performed to examine the validity of the noise analysis for sensor response time testing in nuclear power plants. The conclusion is that noise analysis has the potential for detecting gross changes in sensor response but it cannot be used for reliable measurement of response time until more laboratory and field experience is accumulated. The method is more advantageous for testing pressure sensors than it is for temperature sensors. This is because: 1) for temperature sensors, a method called Loop Current Step Response test is available which is quantitatively more exact than noise analysis, 2) no method currently exists for on-line testing of pressure transmitters other than the Power-Interrupt test which is applicable only to force balance pressure transmitters, and 3) pressure sensor response time is affected by sensing line degradation which is inherently taken into account by testing with noise analysis. (author)

134

Hierarchical Bayes Models for Response Time Data  

Science.gov (United States)

Human response time (RT) data are widely used in experimental psychology to evaluate theories of mental processing. Typically, the data constitute the times taken by a subject to react to a succession of stimuli under varying experimental conditions. Because of the sequential nature of the experiments there are trends (due to learning, fatigue,…

Craigmile, Peter F.; Peruggia, Mario; Van Zandt, Trisha

2010-01-01

135

The Soft X-ray real time fast trigger system  

International Nuclear Information System (INIS)

Most current diagnostics are limited to recording data either at fixed times and data rates, or in response to certain predefined events - such as the injection of a pellet. The previous Soft X-Ray trigger system at Joint European Torus Joint Undertaking (JET)(A.W. Edwards et al., Rev Sci Instrum. 57(8), p2142, 1986) improved upon this by using Analogue Signal Processors to monitor the analogue data in real time and to provide 'triggers' to the data acquisition system in response to an event such as a sawtooth collapse. This system was however limited in the type of events that could be detected. It was also incapable of being rapidly re-configured. Advances in digital electronics caused a study to be undertaken to see if this situation could be improved. The system described below is the result of this study and has successfully run at JET since the summer of 1990, providing a greatly increased quality of data as well as recording some new phenomena such as the spontaneous snake. This note has been produced to describe the function and operation of the trigger system. (author)

136

Time history solution program, L225 (TEV126). Volume 2: Supplemental system design and maintenance document. [for airplane dynamic response using frequency response data  

Science.gov (United States)

The time history solution program L225 (TEV126) is described. The program calculates the time responses of a linear system by convoluting the impulsive response functions with the time dependent excitation. The convolution is performed as a multiplication in the frequency domain. Fast Fourier transform techniques are used to transform the product back into the time domain to obtain response time histories. The design and structure of the program is presented.

Tornallyay, A.; Clemmons, R. E.; Kroll, R. I.

1979-01-01

137

Implementation of pipelined FastICA on FPGA for real-time blind source separation.  

Science.gov (United States)

Fast independent component analysis (FastICA) algorithm separates the independent sources from their mixtures by measuring non-Gaussian. FastICA is a common offline method to identify artifact and interference from their mixtures such as electroencephalogram (EEG), magnetoencephalography (MEG), and electrocardiogram (ECG). Therefore, it is valuable to implement FastICA for real-time signal processing. In this paper, the FastICA algorithm is implemented in a field-programmable gate array (FPGA), with the ability of real-time sequential mixed signals processing by the proposed pipelined FastICA architecture. Moreover, in order to increase the numbers precision, the hardware floating-point (FP) arithmetic units had been carried out in the hardware FastICA. In addition, the proposed pipeline FastICA provides the high sampling rate (192 kHz) capability by hand coding the hardware FastICA in hardware description language (HDL). To verify the features of the proposed hardware FastICA, simulations are first performed, then real-time signal processing experimental results are presented using the fabricated platform. Experimental results demonstrate the effectiveness of the presented hardware FastICA as expected. PMID:18541497

Shyu, Kuo-Kai; Lee, Ming-Huan; Wu, Yu-Te; Lee, Po-Lei

2008-06-01

138

Seismic responses of a pool-type fast reactor with different core support designs  

International Nuclear Information System (INIS)

In designing the core support system for a pool-type fast reactor, there are many issues which must be considered in order to achieve an optimum and balanced design. These issues include safety, reliability, as well as costs. Several design options are possible to support the reactor core. Different core support options yield different frequency ranges and responses. Seismic responses of a large pool-type fast reactor incorporated with different core support designs have been investigated. 4 refs., 3 figs

139

A time-gating scintillation detector for the measurement of laser-induced fast neutrons  

International Nuclear Information System (INIS)

A time-gating scintillation detector, in which a fast high voltage switch is used for gating a channel photomultiplier, was developed for a measurement of laser-induced fast neutrons. The x rays generated from the intense femtosecond laser and the solid target interactions were suppressed selectively and a time-of-flight signal of a laser-generated fast neutron was measured effectively. The detector was used successfully to measure the neutron yield of a femtosecond, deuterated, polystyrene plasma.

140

A time-gating scintillation detector for the measurement of laser-induced fast neutrons.  

Science.gov (United States)

A time-gating scintillation detector, in which a fast high voltage switch is used for gating a channel photomultiplier, was developed for a measurement of laser-induced fast neutrons. The x rays generated from the intense femtosecond laser and the solid target interactions were suppressed selectively and a time-of-flight signal of a laser-generated fast neutron was measured effectively. The detector was used successfully to measure the neutron yield of a femtosecond, deuterated, polystyrene plasma. PMID:19566199

Lee, Sungman; Park, Sangsoon; Yea, Kwon-hae; Cha, Hyungki

2009-06-01

 
 
 
 
141

Test item response time and the response likelihood  

CERN Document Server

Test takers do not give equally reliable responses. They take different responding strategies and they do not make the same effort to solve the problem and answer the question correctly. The consequences of differential test takers' behavior are numerous: the test item parameters could be biased, there might emerge differential item functioning for certain subgroups, estimation of test taker's ability might have greater error, etc. All the consequences are becoming more prominent at low-stakes tests where test takers' motivation is additionally decreased. We had analyzed a computer based test in Physics and tried to find and describe relationship between the item response time and the item response likelihood. We have found that magnitude of such relationship depends on the item difficulty parameter. We have also noticed that boys, who respond faster, in average, give responses with greater likelihood than the boys who respond slower. The same trend was not detected for girls.

Verbic, Srdjan

2009-01-01

142

Response of surge protection devices to fast rising pulses  

Science.gov (United States)

Two types of lightning protection modules incorporating leadless (pill type) Zener like devices were evaluated with regard to their ability to suppress EMP induced transients. Two series of tests were performed to evaluate the ability of these modules to react to fast rate of rise ( 1Kv/ns) transients, and the attenuation introduced and the ability to limit damped sinusoid pulses which may be induced due to an EMP resulting from a nuclear detonation.

Mindel, I. N.

1980-01-01

143

Fast Human Brain Magnetic Resonance Responses Associated With Epileptiform Spikes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Neuronal currents produce local electromagnetic fields that can potentially modulate the phase of the magnetic resonance signal and thus provide a contrast mechanism tightly linked to neuronal activity. Previous work has demonstrated the feasibility of direct MRI of neuronal activity in phantoms and cell culture, but in vivo efforts have yielded inconclusive, conflicting results. The likelihood of detecting and validating such signals can be increased with (i) fast gradient-echo echo-planar i...

Sundaram, Padmavathi; Wells, William M.; Mulkern, Robert V.; Bubrick, Ellen J.; Bromfield, Edward B.; Mu?nch, Mirjam; Orbach, Darren B.

2010-01-01

144

A population study of fasting time and serum prostate-specific antigen (PSA level  

Directory of Open Access Journals (Sweden)

Full Text Available Prostate cancer is one of the most common cancers in men. Traditional screening and diagnostic methods include digital rectal examinations (DREs, biopsies and serum prostate-specific antigen (PSA tests, with the latter being the more popular. PSA is a biomarker for prostate cancer; however, it is highly sensitive to external factors as well as other prostate diseases. As such, the reliability of of the serum PSA level as a sole screening and diagnostic tool for prostate cancer is controversial. Recently, it has been shown that fasting extremes can affect concentrations of serum chemistry analytes, thus raising the question of whether or not fasting has an effect on the highly sensitive PSA biomarker. Patients testing for serum PSA levels are often concomitantly submitting to other tests that require fasting, subjecting certain patients to a fasting PSA level while others not. The objective of this study was to investigate whether this discrepancy in fasting state translates into an effect on serum PSA levels. Serum PSA levels and fasting time records for 157 276 men who underwent testing at Calgary Laboratory Services (CLS; Calgary, Alberta, Canada between 01 January 2010 and 31 March 2013 were accessed. Linear regression models of mean PSA levels and fasting times revealed a statistically important relationship at certain fasting times. Applying a dynamic mathematical model to explore the clinical effect of fasting suggests minimal impact on serum PSA result interpretation. Thus, patients can be tested for serum PSA levels regardless of their fasting state.

Cheryl K Lau

2014-10-01

145

The genetic architecture of fasting plasma triglyceride response to fenofibrate treatment  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Metabolic response to the triglyceride (TG)-lowering drug, fenofibrate, is shaped by interactions between genetic and environmental factors, yet knowledge regarding the genetic determinants of this response is primarily limited to single-gene effects. Since very low-density lipoprotein (VLDL) is the central carrier of fasting TG, identifying factors that affect both total TG and VLDL–TG response to fenofibrate is critical for predicting individual fenofibrate response. As part of the Geneti...

Smith, Jennifer A.; Arnett, Donna K.; Kelly, Reagan J.; Ordovas, Jose M.; Sun, Yan V.; Hopkins, Paul N.; Hixson, James E.; Straka, Robert J.; Peacock, James M.; Kardia, Sharon Lr

2008-01-01

146

A Ballistic Model of Choice Response Time  

Science.gov (United States)

Almost all models of response time (RT) use a stochastic accumulation process. To account for the benchmark RT phenomena, researchers have found it necessary to include between-trial variability in the starting point and/or the rate of accumulation, both in linear (R. Ratcliff & J. N. Rouder, 1998) and nonlinear (M. Usher & J. L. McClelland, 2001)…

Brown, Scott; Heathcote, Andrew

2005-01-01

147

Investigation of response time testing requirements  

International Nuclear Information System (INIS)

The purpose of the Response Time Testing (RTT) Program was to determine if requirements for RTT could be eliminated for specific pressure and differential pressure transmitters and switches. This program was initiated when experience and historical data from a significant number of nuclear power plants indicated that, while RTT is both resource and exposure intensive, an insignificant number of pressure sensor failures have been detected through this type of testing. Assessment of plant response time data and performance of Failure Modes and Effects Analysis (FMEA) on sensor hardware were the mechanisms used by the program to determine the redundancy of RTT in conjunction with other required periodic testing (e.g., calibrations, channel checks, surveillance tests). In general, the FMEA results indicated RTT is redundant to other periodic tests. Results of the program identified only two response time failure modes and two manufacturing/handling defects that may not concurrently affect sensor output. The two failure modes affect a limited number of sensor models. Appropriate testing has been identified in cases where response time degradation may not be coincident with significant sensor output change. 14 refs., 19 figs., 39 tabs

148

Waveform Timing Performance of a 5 GS/s Fast Pulse Sampling Module with DRS4  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We first clarify timing issues of non-uniform sampling intervals regarding a 5 GS/s fast pulse sampling module with DRS4. Calibration strategy is proposed, and as a result, the waveform timing performance is improved to be below 10 ps RMS. We then further evaluate waveform timing performance of the module by comparing with a 10 GS/s oscilloscope in a setup with plastic scintillators and fast PMTs. Different waveform timing algorithms are employed for analysis, and the module...

Wang, Jinhong; Liu, Shubin; An, Qi

2015-01-01

149

Excessive fasting times: still an underaddressed challenge for African pediatrics and anesthesia?  

Directory of Open Access Journals (Sweden)

Full Text Available Gregor Pollach,1,2 Rose Kapenda,2 Beauty Anusa,2 Ethel Waluza,2 Felix Namboya1,21Department of Anaesthesia and Intensive Care, College of Medicine, University of Malawi, 2Queen Elizabeth Central Hospital, Blantyre, Malawi, Central AfricaBackground: Children are starved before surgery following international preoperative guidelines. Extreme fasting is still reported, but data for Africa are scarce. Starving in hot climates leads to challenges arising from dehydration, hypotension, metabolic disturbances, and complications during induction of anesthesia. The purpose of this study was to evaluate the scope of the problem, identify possible reasons for this, and propose realistic solutions.Methods: We performed eleven prospective audits between 2008 and 2013 in Malawi to improve our preoperative fasting times. In total, 631 children (aged 3 days to 13 years were monitored. Training was provided, and the results were measured using a visual analog scale.Results: In 2008, the baseline audit showed a mean fasting time (MFT of 13.48 hours (31 patients. Training reduced the MFT to 8.77 hours (73 patients and 3.2 hours (35 patients in 2009. Without training, the MFT increased to 4.6 hours (35 patients in 2010 and to 10.2 hours (50 patients in 2011. A low level of training decreased the MFT to 8.13 hours (139 patients, in spring 2012. Educational activity brought the MFT down further to 7.86 hours (36 patients, in summer 2012. Lack of training in autumn 2012 increased MFT to 9.32 hours (151 patients, which then improved to 8.04 hours (27 patients as a result of renewed educational activity. In 2013, MFT increased to 9.8 hours (37 patients despite training. In June 2013, more education achieved a reduction in MFT to 6.52 hours (17 patients. The MFT across all audits (2008–2013 was 8.48 hours. Education reduces MFT, but only in the short term. Factors responsible for changes in MFT were identified.Conclusion: Excessive preoperative fasting is an underaddressed problem in Africa. Reduction is difficult, so it has to be accepted as an ongoing task.Keywords: child, infant, fluid, education, developing countries, Africa, fasting

Pollach G

2014-04-01

150

Simulation of response functions of fast neutron sensors and development of thin neutron silicon sensor.  

Science.gov (United States)

On radiation detection using silicon sensor, signals are produced from collected charges in a depletion layer; however, for high-energy particles, this depletion layer is extended due to funnelling phenomenon. The lengths of charge collection were experimentally obtained from proton peak energies in measured pulse-heights. The length is extended with increasing proton energy of up to 6 MeV, and then, is constant over 6 MeV. The response functions of fast neutron sensors were simulated for 5- and 15-MeV monoenergetic and (252)Cf neutron sources using the Monte Carlo N-Particle eXtended code. The simulation results agree well with the experimental ones, including the effect of funnelling phenomenon. In addition, a thin silicon sensor was developed for a new real-time personal neutron dosemeter. Photon sensitivity is vanishingly smaller than neutron one by a factor of 5×10(-4). PMID:24516186

Takada, Masashi; Nakamura, Takashi; Matsuda, Mikihiko; Nunomiya, Tomoya

2014-10-01

151

Study of Response Time in Cloud Computing  

Directory of Open Access Journals (Sweden)

Full Text Available Performance of a cloud is a critical issue and dependent on various factors that include load balancing used to distribute the load at data center. Proliferation of the cloud paradigm is profoundly dependent on the performance of the cloud. Therefore, to examine the cloud performance, it is significant to identify the factors that govern cloud performance. This work is focused to identify the factors that may have significant impact on the cloud performance. To identify the performance factors, we have reviewed the major publications of the last five years as well as the major real time cloud performance tools offered. Study revealed that response time is the major factor that has the significant impact on cloud computing performance. Finally, we have conducted an experiment to establish the dependency of response time on various load balancing techniques and number of data center. Experiment revealed that the round robin is directly proportional to the number of data center

Jitendra Singh

2014-10-01

152

Simulation of response functions of fast neutron sensors and development of thin neutron silicon sensor  

International Nuclear Information System (INIS)

On radiation detection using silicon sensor, signals are produced from collected charges in a depletion layer; however, for high-energy particles, this depletion layer is extended due to funnelling phenomenon. The lengths of charge collection were experimentally obtained from proton peak energies in measured pulse-heights. The length is extended with increasing proton energy of up to 6 MeV, and then, is constant over 6 MeV. The response functions of fast neutron sensors were simulated for 5- and 15-MeV monoenergetic and 252Cf neutron sources using the Monte Carlo N-Particle eXtended code. The simulation results agree well with the experimental ones, including the effect of funnelling phenomenon. In addition, a thin silicon sensor was developed for a new real-time personal neutron dosemeter. Photon sensitivity is vanishingly smaller than neutron one by a factor of 5x10-4. The length of the depletion layer is extended due to the effect of funnelling phenomenon. With increasing proton energy, the length of charge collection is increased; and over 6 MeV of proton energy, the length stays constant. The response functions of fast neutron sensors were simulated for 5- and 15-MeV monoenergetic and 252Cf neutron sources. The simulated results agree well with the experimental ones, considering the effect of funnelling phenomenon. Using this simulation, the response functions of >20 MeV can be obtained. The simulation for high-energy neutrons helps one to develop new personal neutron dosemeters for radiation protection of aircrew. The thin silicon sensor operates as a totally depleted silicon detector, confirmed on a basis of the constant proton peak energy with bias voltage. The thin silicon sensor can be used for new personal neutron dosemeters with negligible photon sensitivity. It was vanishingly smaller than the neutron sensitivity by a factor of 5x10-4. (authors)

153

Fast Frequency and Time Domain Integral Equation Modelling for Marine CSEM Applications:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study we developed algorithms for fast frequency and time domain integral equation modelling for marine controlled-source electromagnetic (CSEM) applications. Solutions of integral equations for CSEM applications in a three-layered earth with an assumed reservoirs is examined using the conjugate gradient fast Fourier transformation (CG-FFT) method, which is used as a reference. For 3D configurations fast computational methods are relevant for both forward and inverse modelling stud...

Moradi Tehrani, A.

2012-01-01

154

Fast Mapping Across Time: Memory Processes Support Children’s Retention of Learned Words  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Children’s remarkable ability to map linguistic labels to referents in the world is commonly called fast mapping. The current study examined children’s (N?=?216) and adults’ (N?=?54) retention of fast-mapped words over time (immediately, after a 1-week delay, and after a 1-month delay). The fast mapping literature often characterizes children’s retention of words as consistently high across timescales. However, the current study demonstrates that learners forget word mappings ...

HaleyVlach

2012-01-01

155

The response function of organic scintillators to fast neutrons  

International Nuclear Information System (INIS)

Neutron response functions of cylindrical organic scintillators in the energy range 112C and the contribution of the direct 12C(n, p) channel at high energies have been investigated. The obtained results have been compared with the available experimental response functions in NE102A, NE213 and NE218. (Auth.)

156

Vlasov-Fokker-Planck simulations of fast-electron transport with hydrodynamic plasma response  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report on kinetic simulations of the transport of laser-produced relativistic electron beams (REB) through solid-density plasma, including the hydrodynamic response of the plasma. We consider REBs with parameters relevant to fast-ignition of compressed inertial confinement fusion capsules. We show that over the 10-20ps timescales required for fast-ignition, thermal pressure (from Ohmic heating) can significantly modify the density which in turn strongly affects the propagation of injected ...

Kingham, Rj; Sherlock, M.; Ridgers, Cp; Evans, Rg

2010-01-01

157

Effect of thermocouple time constant on sensing of temperature fluctuations in a fast reactor subassembly  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Knowledge of temperature fluctuations in fast reactor subassembly is very important from a safety point of view. The time constant of thermocouples which are used for measuring coolant temperature in a fast reactor varies owing to various factors. Hence, it becomes necessary to investigate the effect of change in the time constant on sensed fluctuations. This paper investigates the dependence of temperature fluctuations on thermocouple time constants. A Scilab model consisti...

Sharma, P.; Murali, N.; Jayakumar, T.

2014-01-01

158

Fabrication and Characteristics of Fast Photo Response ZnO/Porous Silicon UV Photoconductive Detector  

Directory of Open Access Journals (Sweden)

Full Text Available Fast response time UV photoconductive detector was fabricated based on ZnO film prepared by thermal chemical spray pyrolysis technique. The ZnO nanofilms are grown on the porous silicon (PS nanosurface which has drastically reduced the response time of the ZnO UV detector from few seconds to few hundreds of microseconds. The surface functionalization of the ZnO film deposited on porous silicon (PS layer by polyamide nylon has highly improved the photoresponsivity of the detector to 0.8 A/W. The normalized de-tectivity (D* of the fabricated ZnO UV detector at wavelength of 385 nm is found to be about 2.12 × 1011 cm Hz1/2 W–1. The ZnO film grown on the porous silicon layer was oriented in the c-axis and it is found to be a p-type semiconductor, which is referred to the compensation of the excess charge carriers in the ZnO film by the nanospikes silicon layer.

Hanan A. Thjeel

2011-12-01

159

High temperature fast response pressure probe for use in liquid metal droplet dispensers  

Science.gov (United States)

A miniature fast response high temperature pressure probe, with demonstrated use in liquid metals up to 255 °C (528 K), has been developed. Innovative packaging technologies have been applied to integrate a conventional piezoresistive silicon pressure sensor into the probe, without the need of an auxiliary water-cooling system. In situ static calibrations are used to verify the linearity of the pressure signal and the stability of the pressure sensitivity (0.5% standard deviation over 70 min at 255 °C). Dynamic calibration, completed in an air shock tube facility, yields the probe's natural frequency. This frequency, when corrected for probe operation in liquid tin, is found to be 100 kHz. The reliability and accuracy of the probe is assessed by mounting it in a tin droplet dispenser for use in an extreme ultraviolet light source. Droplet dispensers typically include an excitation mechanism, which can be based on the generation of acoustic pressure waves to impose a desired droplet frequency. The probe accuracy is verified by the comparison of pressure measurements with laser Doppler vibrometry measurements of the pressure generating structure. A reference pressure measurement, conducted at representative conditions, shows a complex frequency response, with peaks distributed over three orders of magnitude and maximum amplitude of 440 mbar. Time variance of the excitation mechanism due to thermal transients is studied by monitoring the pressure response during operation. Finally, the linearity of the excitation system, with respect to the excitation amplitude, is verified by response measurements. In conclusion, the developed probe is capable of characterizing the excitation mechanism of a liquid metal droplet dispenser. Additionally, real-time monitoring of the performance of the excitation system during long-term operation is possible.

Rollinger, B.; Mansour, M.; Abhari, R. S.

2012-06-01

160

Fast ?-ray coincidence timing using a BGO detector array in a nuclear reaction experiment  

International Nuclear Information System (INIS)

The (7Li, 7Be) nuclear charge-exchange reaction has been investigated at E(7Li)=350 MeV. Coincidences were measured between the charged 7Be reaction products in the focal plane of a magnetic spectrometer and 430-keV Doppler-shifted ?-rays from the decay in flight of excited 7Be ejectiles. The latter were detected in a compact BGO detector array. Fast timing was used to optimize the separation between prompt and randoms events. The BGO output signals display the statistical distribution of the arrival times of individual photoelectrons from the photocathode in the photomultiplier tubes. A timing resolution of 6.5 ns relative to the accelerator RF was obtained. A simple model was successfully developed to simulate the BGO output signals with a statistical distribution of a predetermined number of photoelectrons modulated by the light output response of the scintillator and the single-photoelectron gain distribution and transit time through the photomultiplier tube. It is concluded that the timing resolution is primarily limited by the small number of photoelectrons. ((orig.))

 
 
 
 
161

[Influence of tenotomy on posttetanic responses of the rat fast and slow muscle].  

Science.gov (United States)

The effect of two weeks of tenotomy on posttetanic isometric contractile responses of the rat fast: Extensor digitorum longus and slow: soleus muscles was studied in experiments on isolated muscle preparations. Direct tetanic stimulation (100 impulses, 50 Hz) increased the force of contractions by 20-25% (p depression, a decrease in the amplitude of contractile responses. Tenotomized slow muscles did not develop posttetanic depression. Caffeine (4 mM) increased and dandrolene (10 microM) decreased the force of unitary and tetanic contractions of control and tenotomized muscles. Neither drug, however, affected development of posttetanic phenomena in ether fast or slow muscles. The fact that in extensor digitorum longus, posttetanic potentiation is preserved for at least forty days of tenotomy but disappears after only 2 weeks of denervation suggests important role of neurotrophic influences in regulation of posttetanic responses of fast muscles. PMID:21961302

Arutiunian, R S; Zhabko, E P

2011-08-01

162

Development and validation of a two-dimensional fast-response flood estimation model  

Energy Technology Data Exchange (ETDEWEB)

A finite difference formulation of the shallow water equations using an upwind differencing method was developed maintaining computational efficiency and accuracy such that it can be used as a fast-response flood estimation tool. The model was validated using both laboratory controlled experiments and an actual dam breach. Through the laboratory experiments, the model was shown to give good estimations of depth and velocity when compared to the measured data, as well as when compared to a more complex two-dimensional model. Additionally, the model was compared to high water mark data obtained from the failure of the Taum Sauk dam. The simulated inundation extent agreed well with the observed extent, with the most notable differences resulting from the inability to model sediment transport. The results of these validation studies complex two-dimensional model. Additionally, the model was compared to high water mark data obtained from the failure of the Taum Sauk dam. The simulated inundation extent agreed well with the observed extent, with the most notable differences resulting from the inability to model sediment transport. The results of these validation studies show that a relatively numerical scheme used to solve the complete shallow water equations can be used to accurately estimate flood inundation. Future work will focus on further reducing the computation time needed to provide flood inundation estimates for fast-response analyses. This will be accomplished through the efficient use of multi-core, multi-processor computers coupled with an efficient domain-tracking algorithm, as well as an understanding of the impacts of grid resolution on model results.

Judi, David R [Los Alamos National Laboratory; Mcpherson, Timothy N [Los Alamos National Laboratory; Burian, Steven J [UNIV OF UTAK

2009-01-01

163

Picosecond time measurement using ultra fast analog memories  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The currently existing electronics dedicated to precise time measurement is mainly based on the use of constant fraction discriminators (CFD) associated with Time to Digital Converters (TDC). The constant fraction technique minimizes the time walk effect (dependency of timing on the pulse amplitude). Several attempts have been made to integrate CFD in multi-channel ASICs. But the time resolution measured on the most advanced one is of the order of 30 ps rms. Two main techniques are used for t...

Breton, D.; Delagnes, E.; Maalmi, J.

2009-01-01

164

Fast Human Brain Magnetic Resonance Responses Associated With Epileptiform Spikes  

Science.gov (United States)

Neuronal currents produce local electromagnetic fields that can potentially modulate the phase of the magnetic resonance signal and thus provide a contrast mechanism tightly linked to neuronal activity. Previous work has demonstrated the feasibility of direct MRI of neuronal activity in phantoms and cell culture, but in vivo efforts have yielded inconclusive, conflicting results. The likelihood of detecting and validating such signals can be increased with (i) fast gradient-echo echo-planar imaging, with acquisition rates sufficient to resolve neuronal activity, (ii) subjects with epilepsy, who frequently experience stereotypical electromagnetic discharges between seizures, expressed as brief, localized, high-amplitude spikes (interictal discharges), and (iii) concurrent electroencephalography. This work demonstrates that both MR magnitude and phase show large-amplitude changes concurrent with electroencephalography spikes. We found a temporal derivative relationship between MR phase and scalp electroencephalography, suggesting that the MR phase changes may be tightly linked to local cerebral activity. We refer to this manner of MR acquisition, designed explicitly to track the electroencephalography, as encephalographic MRI (eMRI). Potential extension of this technique into a general purpose functional neuroimaging tool requires further study of the MR signal changes accompanying lower amplitude neuronal activity than those discussed here. PMID:20806355

Sundaram, Padmavathi; Wells, William M.; Mulkern, Robert V.; Bubrick, Ellen J.; Bromfield, Edward B.; Münch, Mirjam; Orbach, Darren B.

2012-01-01

165

Flexible palladium-based H2 sensor with fast response and low leakage detection by nanoimprint lithography.  

Science.gov (United States)

Flexible palladium-based H2 sensors have a great potential in advanced sensing applications, as they offer advantages such as light weight, space conservation, and mechanical durability. Despite these advantages, the paucity of such sensors is due to the fact that they are difficult to fabricate while maintaining excellent sensing performance. Here, we demonstrate, using direct nanoimprint lithography of palladium, the fabrication of a flexible, durable, and fast responsive H2 sensor that is capable of detecting H2 gas concentration as low as 50 ppm. High resolution and high throughput patterning of palladium gratings over a 2 cm × 1 cm area on a rigid substrate was achieved by heat-treating nanoimprinted palladium benzyl mercaptide at 250 °C for 1 h. The flexible and robust H2 sensing device was fabricated by subsequent transfer nanoimprinting of these gratings into a polycarbonate film at its glass transition temperature. This technique produces flexible H2 sensors with improved durability, sensitivity, and response time in comparison to palladium thin films. At ambient pressure and temperature, the device showed a fast response time of 18 s at a H2 concentration of 3500 ppm. At 50 ppm concentration, the response time was found to be 57 s. The flexibility of the sensor does not appear to compromise its performance. PMID:23819468

Lim, Su Hui; Radha, Boya; Chan, Jie Yong; Saifullah, Mohammad S M; Kulkarni, Giridhar U; Ho, Ghim Wei

2013-08-14

166

Time-of-flight measurement of fast neutrons with Timepix detectors  

Science.gov (United States)

Timepix pixel detectors have been used to study the response of silicon hybrid pixel detectors to fast neutrons from a pulsed neutron beam at WNR FP30R, a 14 m long flight path, in the Los Alamos Neutron Science Center. Neutrons with kinetic energies up to 600 MeV were available. In order to enhance the conversion of neutrons to energetic charged particles, several converter foils and filters were attached to the 300 ?m thick silicon sensor, i.e. polyethylene, polyethylene with aluminum, 6LiF, 6LiF with aluminum, aluminum. The Time-of-Arrival mode of the Timepix detectors has permitted the application of the Time-of-Flight (TOF) technique for the assignment of the detected interactions in the form of clusters (groups of adjacent pixels) in the pixel matrix, to the kinetic energies of the incident neutrons. It was found that, for lower neutron energies ( ~ MeV range) the cluster rates below the polyethylene and the polyethylene and aluminum region, produced by recoil protons, are a good measure for the mean kinetic energies of neutrons. For energies above 50 MeV nuclear reactions in the silicon dominate the detector response. In this energy range the shape of the clusters indicates the neutron kinetic energy.

Bergmann, B.; Nelson, R. O.; O'Donnell, J. M.; Pospisil, S.; Solc, J.; Takai, H.; Vykydal, Z.

2014-05-01

167

TRANC – a novel fast-response converter to measure total reactive atmospheric nitrogen  

Directory of Open Access Journals (Sweden)

Full Text Available The input and loss of plant available nitrogen (reactive nitrogen: Nr from/to the atmosphere can be an important factor for the productivity of ecosystems and thus for its carbon and greenhouse gas exchange. We present a novel converter for reactive nitrogen (TRANC: Total Reactive Atmospheric Nitrogen Converter, which offers the opportunity to quantify the sum of all airborne reactive nitrogen compounds (?Nr in high time resolution. The basic concept of the TRANC is the full conversion of all Nr to nitrogen monoxide (NO within two reaction steps. Initially, reduced Nr compounds are being oxidised, and oxidised Nr compounds are thermally converted to lower oxidation states. Particulate Nr is being sublimated and oxidised or reduced afterwards. In a second step, remaining higher nitrogen oxides or those generated in the first step are catalytically converted to NO with carbon monoxide used as reduction gas. The converter is combined with a fast response chemiluminescence detector (CLD for NO analysis and its performance was tested for the most relevant gaseous and particulate Nr species under both laboratory and field conditions. Recovery rates during laboratory tests for NH3 and NO2 were found to be 95 and 99%, respectively, and 97% when the two gases were combined. In-field longterm stability over an 11-month period was approved by a value of 91% for NO2. Effective conversion was also found for ammonium and nitrate containing particles. The recovery rate of total ambient Nr was tested against the sum of individual measurements of NH3, HNO3, HONO, NH4+, NO3?, and NOx using a combination of different well-established devices. The results show that the TRANC-CLD system precisely captures fluctuations in ?Nr concentrations and also matches the sum of all individual Nr compounds measured by the different single techniques. The TRANC features a specific design with very short distance between the sample air inlet and the place where the thermal and catalytic conversions to NO occur. This assures a short residence time of the sample air inside the instrument, and minimises wall sorption problems of water soluble compounds. The fast response time (e-folding times of 0.30 to 0.35 s were found during concentration step changes and high accuracy in capturing the dominant Nr species enables the converter to be used in an eddy covariance setup. Although a source attribution of specific Nr compounds is not possible, the TRANC is a new reliable tool for permanent measurements of the net ?Nr flux between ecosystem and atmosphere at a relatively low maintenance and reasonable cost level allowing for diurnal, seasonal and annual investigations.

V. Wolff

2012-05-01

168

Time-resolved fast-neutron imaging with a pulse-counting image intensifier  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new imaging method that combines high-efficiency fast-neutron detection with sub-ns time resolution is presented. This is achieved by exploiting the high neutron detection efficiency of a thick scintillator and the fast timing capability and flexibility of light-pulse detection with a dedicated image intensifier. The neutron converter is a plastic scintillator slab or, alternatively, a scintillating fibre screen. The scintillator is optically coupled to a pulse counting image intensifier wh...

Dangendorf, Volker

2007-01-01

169

Graphene based Supercapacitors with Improved Specific Capacitance and Fast Charging Time at High Current Density  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Graphene is a promising material for energy storage, especially for high performance supercapacitors. For real time high power applications, it is critical to have high specific capacitance with fast charging time at high current density. Using a modified Hummer's method and tip sonication for graphene synthesis, here we show graphene-based supercapacitors with high stability and significantly-improved electrical double layer capacitance and energy density with fast charging...

Kannappan, Santhakumar; Kaliyappan, Karthikeyan; Manian, Rajesh Kumar; Pandian, Amaresh Samuthira; Yang, Hao; Lee, Yun Sung; Jang, Jae-hyung; Lu, Wu

2013-01-01

170

Patterns of Response Times and Response Choices to Science Questions: The Influence of Relative Processing Time.  

Science.gov (United States)

We report on five experiments investigating response choices and response times to simple science questions that evoke student "misconceptions," and we construct a simple model to explain the patterns of response choices. Physics students were asked to compare a physical quantity represented by the slope, such as speed, on simple physics graphs. We found that response times of incorrect answers, resulting from comparing heights, were faster than response times of correct answers comparing slopes. This result alone might be explained by the fact that height was typically processed faster than slope for this kind of task, which we confirmed in a separate experiment. However, we hypothesize that the difference in response time is an indicator of the cause (rather than the result) of the response choice. To support this, we found that imposing a 3-s delay in responding increased the number of students comparing slopes (answering correctly) on the task. Additionally a significant proportion of students recognized the correct written rule (compare slope), but on the graph task they incorrectly compared heights. Finally, training either with repetitive examples or providing a general rule both improved scores, but only repetitive examples had a large effect on response times, thus providing evidence of dual paths or processes to a solution. Considering models of heuristics, information accumulation models, and models relevant to the Stroop effect, we construct a simple relative processing time model that could be viewed as a kind of fluency heuristic. The results suggest that misconception-like patterns of answers to some science questions commonly found on tests may be explained in part by automatic processes that involve the relative processing time of considered dimensions and a priority to answer quickly. PMID:25230833

Heckler, Andrew F; Scaife, Thomas M

2014-09-18

171

Effect of short-term fasting on lipolytic responsiveness in normal and obese human subjects  

International Nuclear Information System (INIS)

In this study the rate of lipolysis (fatty acid and glycerol release into blood) has been quantified in both normal weight and obese volunteers after both 15 and 87 h of fasting. In each study, the basal rate and subsequent response to epinephrine infusion were determined. The rate of appearance (R/sub a/) of free fatty acids (FFA) and glycerol were quantified by infusion of [1-13C]palmitate and D-5-glycerol, respectively. Substrate flux rates per unit of body fat mass and lean body mass were calculated from total body water measurements using H218O dilution. In normal volunteers, the basal R/sub a/ FFA and R/sub a/ glycerol rose markedly with 87 h of fasting, whereas the increases were more modest in the obese subjects. However, the rate of mobilization of fat, in relation to the lean body mass, was higher in the obese subjects than in the normal subjects after 15 h of fasting, and the values were similar in both groups after 87 h of fasting. There was an increased lipolytic response to epinephrine after fasting in both groups. This increased sensitivity may have resulted from the enhancement of fatty acid-triglyceride substrate cycling that occurred after fasting

172

Effect of short-term fasting on lipolytic responsiveness in normal and obese human subjects  

Energy Technology Data Exchange (ETDEWEB)

In this study the rate of lipolysis (fatty acid and glycerol release into blood) has been quantified in both normal weight and obese volunteers after both 15 and 87 h of fasting. In each study, the basal rate and subsequent response to epinephrine infusion were determined. The rate of appearance (R/sub a/) of free fatty acids (FFA) and glycerol were quantified by infusion of (1- TC)palmitate and D-5-glycerol, respectively. Substrate flux rates per unit of body fat mass and lean body mass were calculated from total body water measurements using H2 YO dilution. In normal volunteers, the basal R/sub a/ FFA and R/sub a/ glycerol rose markedly with 87 h of fasting, whereas the increases were more modest in the obese subjects. However, the rate of mobilization of fat, in relation to the lean body mass, was higher in the obese subjects than in the normal subjects after 15 h of fasting, and the values were similar in both groups after 87 h of fasting. There was an increased lipolytic response to epinephrine after fasting in both groups. This increased sensitivity may have resulted from the enhancement of fatty acid-triglyceride substrate cycling that occurred after fasting.

Wolfe, R.R.; Peters, E.J.; Klein, S.; Holland, O.B.; Rosenblatt, J.; Gary, H. Jr.

1987-02-01

173

Fast Response Systems Using Feed Forward Loop for Fuzzy Tuned PID Controllers  

Directory of Open Access Journals (Sweden)

Full Text Available The temperature during heating processes more essential in oil quantity .Many of the research effort they developed new control technique to control and regulate the steam temperature in industries. This seems to be because PID controllers is simple structure, assure acceptable performances for a wide range of industrial plants and their usage (the tuning of their parameters is well known among industrial operators. PID with FLC with combination of this we neglected the steady sate errors. PID controllers are particularly suited for pure first- or second-order processes, while industrial plants often present characteristics such as high order, time delays, nonlinearities and so on challenges during design the PID is to tune the PID parameters gain that suite to the plant. To overcome this problem, feed forward tuning PID using the fuzzy logic controller with self-tuning method is utilized to regulate the steam temperature. It gives good process dynamic characteristic which are process rise time, process settling time, percent overshoot and less steady state error. The ability to track any parameters changes and has fast recovery the output response during disturbance period.

M.Tharangini

2014-08-01

174

Response of gut microbiota to fasting and hibernation in Syrian hamsters.  

Science.gov (United States)

Although hibernating mammals wake occasionally to eat during torpor, this period represents a state of fasting. Fasting is known to alter the gut microbiota in nonhibernating mammals; therefore, hibernation may also affect the gut microbiota. However, there are few reports of gut microbiota in hibernating mammals. The present study aimed to compare the gut microbiota in hibernating torpid Syrian hamsters with that in active counterparts by using culture-independent analyses. Hamsters were allocated to either torpid, fed active, or fasted active groups. Hibernation was successfully induced by maintaining darkness at 4 degrees C. Flow cytometry analysis of cecal bacteria showed that 96-h fasting reduced the total gut bacteria. This period of fasting also reduced the concentrations of short chain fatty acids in the cecal contents. In contrast, total bacterial numbers and concentrations of short chain fatty acids were unaffected by hibernation. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments indicated that fasting and hibernation modulated the cecal microbiota. Analysis of 16S rRNA clone library and species-specific real-time quantitative PCR showed that the class Clostridia predominated in both active and torpid hamsters and that populations of Akkermansia muciniphila, a mucin degrader, were increased by fasting but not by hibernation. From these results, we conclude that the gut microbiota responds differently to fasting and hibernation in Syrian hamsters. PMID:19700553

Sonoyama, Kei; Fujiwara, Reiko; Takemura, Naoki; Ogasawara, Toru; Watanabe, Jun; Ito, Hiroyuki; Morita, Tatsuya

2009-10-01

175

Waveform Timing Performance of a 5 GS/s Fast Pulse Sampling Module with DRS4  

CERN Document Server

We first clarify timing issues of non-uniform sampling intervals regarding a 5 GS/s fast pulse sampling module with DRS4. Calibration strategy is proposed, and as a result, the waveform timing performance is improved to be below 10 ps RMS. We then further evaluate waveform timing performance of the module by comparing with a 10 GS/s oscilloscope in a setup with plastic scintillators and fast PMTs. Different waveform timing algorithms are employed for analysis, and the module shows comparable timing performance with that of the oscilloscope.

Wang, Jinhong; An, Qi

2015-01-01

176

Fast neutron dose response of a commercial polycarbonate  

Science.gov (United States)

A commercial polycarbonate produced in Brazil is being studied to be used as neutron detector material using Solid State Nuclear Track Detection (SSNTD) method replacing the well-known detector materials Makrofol and CR-39. This technique is based on the damage (tracks) registration of charged particles produced by the interaction of neutrons with carbon and oxygen atoms of some dielectric materials. The IPEN dosimeter prototype is composed by 30×10×1.5 mm 3 polycarbonate piece inserted between two Polymethyl Methacralate (PMMA) plates 2 mm thick. The prototypes were irradiated placed on an ISO slab phantom using an isotropic 241AmBe source at LN/LNMRI (Neutrons Laboratory of the National Laboratory of Ionizing Radiation Metrology). To study the dose response groups of five prototypes were irradiated with Hp(10) from 0.5 to 20 mSv with normal incidence and to investigate the angular incidence effect with Hp(10) = 5 mSv with incidence angles of 15°, 45°, 60°, 75°, 85° and 90°. The detectors were revealed by chemical etching with the solution PEW-40 during 3 h. The track density of the detector surface was determined by the average of track counting of five fields ( 20×0.1 mm 2). The track response to equivalent dose Hp(10) showed a good agreement with linear fit in the studied interval. The track density strongly decreases for incidence angles higher than 45°.

Souto, E. B.; Campos, L. L.

2007-09-01

177

Fast neutron dose response of a commercial polycarbonate  

International Nuclear Information System (INIS)

A commercial polycarbonate produced in Brazil is being studied to be used as neutron detector material using Solid State Nuclear Track Detection (SSNTD) method replacing the well-known detector materials Makrofol and CR-39. This technique is based on the damage (tracks) registration of charged particles produced by the interaction of neutrons with carbon and oxygen atoms of some dielectric materials. The IPEN dosimeter prototype is composed by 30x10x1.5 mm3 polycarbonate piece inserted between two Polymethyl Methacralate (PMMA) plates 2 mm thick. The prototypes were irradiated placed on an ISO slab phantom using an isotropic 241AmBe source at LN/LNMRI (Neutrons Laboratory of the National Laboratory of Ionizing Radiation Metrology). To study the dose response groups of five prototypes were irradiated with Hp(10) from 0.5 to 20 mSv with normal incidence and to investigate the angular incidence effect with Hp(10) = 5 mSv with incidence angles of 15o, 45o, 60o, 75o, 85o and 90o. The detectors were revealed by chemical etching with the solution PEW-40 during 3 h. The track density of the detector surface was determined by the average of track counting of five fields (20x0.1 mm2). The track response to equivalent dose Hp(10) showed a good agreement with linear fit in the studied interval. The track density strongly decreases for incidence angles higher than 45 degnce angles higher than 45 deg

178

Fast-response room temperature hydrogen gas sensors using platinum-coated spin-capable carbon nanotubes.  

Science.gov (United States)

We report the properties of a hydrogen (H2) gas sensor based on platinum (Pt)-coated carbon nanotubes (CNTs) in this paper. To fabricate the Pt-CNT composite sensor, a highly aligned CNT sheet was prepared on a glass substrate from a spin-capable CNT forest, followed by electrobeam (e-beam) deposition of Pt layers onto the CNT sheet. To investigate the effect of Pt on the response of the sensor, Pt layers of different thicknesses were deposited on the CNT sheets. A Pt thickness of 6 nm yielded the highest response for H2 detection, whereas Pt layers thinner or thicker than 6 nm led to a reduction of the surface area for gas adsorption and, consequently, decreased response. The Pt-CNT composite sensor detects H2 concentrations of 3-33% at room temperature and shows reproducible behavior with fast response and recovery times. PMID:25619413

Jung, Daewoong; Han, Maeum; Lee, Gil S

2015-02-11

179

Linear Time Lempel-Ziv Factorization: Simple, Fast, Small  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Computing the LZ factorization (or LZ77 parsing) of a string is a computational bottleneck in many diverse applications, including data compression, text indexing, and pattern discovery. We describe new linear time LZ factorization algorithms, some of which require only 2n log n + O(log n) bits of working space to factorize a string of length n. These are the most space efficient linear time algorithms to date, using n log n bits less space than any previous linear time algo...

Ka?rkka?inen, Juha; Kempa, Dominik; Puglisi, Simon J.

2012-01-01

180

A Fast Signal-Dependent Time-Frequency Representation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In last few years, in order to overcome same limitations of the short time Fourier transform (STFT), while avoiding the cross-terms that make the Wigner distribution difficult to interpret, some signal-dependent time-frequency representations (SDTFR) have been proposed. In this paper, the authors introduce a computationally efficient signal-dependent time-frequency method which is suitable for on-line analysis. This SDTFR uses a Gaussian window (GW) similar to STFT, but varies the parameter ?...

Lin, Ym; Chan, Fhy; Lam, Fk

1996-01-01

 
 
 
 
181

Dynamic Response of a fast near infra-red Mueller matrix ellipsometer  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The dynamic response of a near infrared Ferroelectric Liquid Crystal based Mueller matrix ellipsometer (NIR FLC-MME) is presented. A time dependent simulation model, using the measured time response of the individual FLCs, is used to describe the measured temporal response. Furthermore, the impulse response of the detector and the pre-amplifier is characterized and included in the simulation model. The measured time-dependent intensity response of the MME is reproduced in si...

Aas, Lars Martin Sandvik; Ellingsen, Pa?l Gunnar; Kildemo, Morten; Lindgren, Mikael

2010-01-01

182

Rigorous time domain responses of polarizable media  

Directory of Open Access Journals (Sweden)

Full Text Available The scope of this note is to study a model of induced polarization which fits the usually accepted frequency dependent formula of Cole and Cole, but is more general and allows the time domain observations to retrieve the parameters describing the induced polarization phenomena of the medium. By introducing the memory mechanisms, represented by derivatives of fractional order, in the relation between the electric flux density and the electric field and considering the fractional order differential equation which follows, I solve it with mathematically rigorous and closed formulae and compute the responses to a step function, a box, a set of positive boxes and a set of alternating positive and negative boxes. I also introduce a method which retrieves the parameters describing the medium when comparing the theoretical curves with the observed ones. The responses to these signals also allow to estimate the temporary alteration of the medium when repeated positive (negative signals are input; the response increases (decreases in amplitude when the signals are all positive (negative, it decreases when the signals are alternatively positive and negative in agreement with the known attitude of the medium to induced polarization.

M. Caputo

1997-06-01

183

FAST Mast Structural Response to Axial Loading: Modeling and Verification  

Science.gov (United States)

The International Space Station s solar array wing mast shadowing problem is the focus of this paper. A building-block approach to modeling and analysis is pursued for the primary structural components of the solar array wing mast structure. Starting with an ANSYS (Registered Trademark) finite element model, a verified MSC.Nastran (Trademark) model is established for a single longeron. This finite element model translation requires the conversion of several modeling and analysis features for the two structural analysis tools to produce comparable results for the single-longeron configuration. The model is then reconciled using test data. The resulting MSC.Nastran (Trademark) model is then extended to a single-bay configuration and verified using single-bay test data. Conversion of the MSC. Nastran (Trademark) single-bay model to Abaqus (Trademark) is also performed to simulate the elastic-plastic longeron buckling response of the single bay prior to folding.

Knight, Norman F., Jr.; Elliott, Kenny B.; Templeton, Justin D.; Song, Kyongchan; Rayburn, Jeffery T.

2012-01-01

184

Effect of the number of unit elements on the fast response of a multivalued homogeneous structure  

Energy Technology Data Exchange (ETDEWEB)

The way in which the number of unit elements influences the fast response of multivalued tree-like homogeneous structures consisting of n-input and m-output universal multivalued elements is considered. A comparison procedure is suggested. Logic equivalence features are determined for structures operating in the alphabet with a different number of unit elements. 6 references.

Drozdova, G.D.

1983-11-01

185

Fast sensors for time-of-flight imaging applications.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The development of sensors capable of detecting particles and radiation with both high time and high positional resolution is key to improving our understanding in many areas of science. Example applications of such sensors range from fundamental scattering studies of chemical reaction mechanisms through to imaging mass spectrometry of surfaces, neutron scattering studies aimed at probing the structure of materials, and time-resolved fluorescence measurements to elucidate the structure and fu...

Vallance, C.; Brouard, M.; Lauer, A.; Slater, Cs; Halford, E.; Winter, B.; King, Sj; Lee, Jw; Pooley, DE; Sedgwick, I.; Turchetta, R.; Nomerotski, A.; John, Jj; Hill, L.

2014-01-01

186

Ultra-high throughput real-time instruments for capturing fast signals and rare events  

Science.gov (United States)

Wide-band signals play important roles in the most exciting areas of science, engineering, and medicine. To keep up with the demands of exploding internet traffic, modern data centers and communication networks are employing increasingly faster data rates. Wide-band techniques such as pulsed radar jamming and spread spectrum frequency hopping are used on the battlefield to wrestle control of the electromagnetic spectrum. Neurons communicate with each other using transient action potentials that last for only milliseconds at a time. And in the search for rare cells, biologists flow large populations of cells single file down microfluidic channels, interrogating them one-by-one, tens of thousands of times per second. Studying and enabling such high-speed phenomena pose enormous technical challenges. For one, parasitic capacitance inherent in analog electrical components limits their response time. Additionally, converting these fast analog signals to the digital domain requires enormous sampling speeds, which can lead to significant jitter and distortion. State-of-the-art imaging technologies, essential for studying biological dynamics and cells in flow, are limited in speed and sensitivity by finite charge transfer and read rates, and by the small numbers of photo-electrons accumulated in short integration times. And finally, ultra-high throughput real-time digital processing is required at the backend to analyze the streaming data. In this thesis, I discuss my work in developing real-time instruments, employing ultrafast optical techniques, which overcome some of these obstacles. In particular, I use broadband dispersive optics to slow down fast signals to speeds accessible to high-bit depth digitizers and signal processors. I also apply telecommunication multiplexing techniques to boost the speeds of confocal fluorescence microscopy. The photonic time stretcher (TiSER) uses dispersive Fourier transformation to slow down analog signals before digitization and processing. The act of time-stretching effectively boosts the performance of the back-end electronics and digital signal processors. The slowed down signals reach the back-end electronics with reduced bandwidth, and are therefore less affected by high-frequency roll-off and distortion. Time-stretching also increases the effective sampling rate of analog-to-digital converters and reduces aperture jitter, thereby improving resolution. Finally, the instantaneous throughputs of digital signal processors are enhanced by the stretch factor to otherwise unattainable speeds. Leveraging these unique capabilities, TiSER becomes the ideal tool for capturing high-speed signals and characterizing rare phenomena. For this thesis, I have developed techniques to improve the spectral efficiency, bandwidth, and resolution of TiSER using polarization multiplexing, all-optical modulation, and coherent dispersive Fourier transformation. To reduce the latency and improve the data handling capacity, I have also designed and implemented a real-time digital signal processing electronic backend, achieving 1.5 tera-bit per second instantaneous processing throughput. Finally, I will present results from experiments highlighting TiSER's impact in real-world applications. Confocal fluorescence microscopy is the most widely used method for unveiling the molecular composition of biological specimens. However, the weak optical emission of fluorescent probes and the tradeoff between imaging speed and sensitivity is problematic for acquiring blur-free images of fast phenomena and cells flowing at high speed. Here I introduce a new fluorescence imaging modality, which leverages techniques from wireless communication to reach record pixel and frame rates. Termed Fluorescence Imaging using Radio-frequency tagged Emission (FIRE), this new imaging modality is capable of resolving never before seen dynamics in living cells - such as action potentials in neurons and metabolic waves in astrocytes - as well as performing high-content image assays of cells and particles in high-speed flow.

Buckley, Brandon Walter

187

FAST-RESPONSE ISOTOPIC ALPHA CONTINUOUS AIR MONITOR (CAM)  

Energy Technology Data Exchange (ETDEWEB)

The objective of this effort is to develop and test a novel Continuous Air Monitor (CAM) instrument for monitoring alpha-emitting radionuclides, using a technology that can be applied to Continuous Emission Monitoring (CEM) of thermal treatment system off gas streams. The CAM instrument will have very high alpha spectral resolution and provide real-time, on-line monitoring suitable for alerting workers of high concentrations of alpha-emitting radionuclides in the ambient air and for improved control of decontamination, dismantlement, and air emission control equipment. Base Phase I involves the design, development, and preliminary testing of a laboratory-scale instrument. Testing will initially be conducted using naturally-occurring radon progeny in ambient air. In the Optional Phase II, the Base Phase I instrument will be critically evaluated at the Lovelace Respiratory Research Institute (LRRI) with characterized plutonium aerosols; then an improved instrument will be built and field-tested at a suitable DOE site.

Keith D. Patch

2000-04-28

188

Continuous data recording on fast real-time systems  

International Nuclear Information System (INIS)

The PCU-Project enhancement of the vertical stabilisation at JET required a new real-time control system with specifications of 2 Gops and 50 ?s cycle time. A new framework for the real-time has been developed showing to meet the requirements running on RTAI based architecture on an *86 multi-core processor technology. The new real-time multi-platform framework developed at JET has demonstrated with the new Vertical Stabilisation system to be able to reach high performance, maintaining a high level of flexibility and offering a powerful environment for debugging and testing. Linux-RTAI, on a multi-core processor, has been the optimal platform for obtaining the requested performance. Managing the high data flow has been solved via a data streaming architecture that, without compromising the real-time tasks, has shown to have reached a high transfer rate (up to 70 Mb/s). This technology can be exported to a long pulse duration environment like ITER and with minimum effort it can also be used for implementing off-line post-processing during the operation without having to wait for the end of the experiment. This document is a poster. (A.C.)

189

Fast, real-time, DFT instrument based on VMEbus  

Science.gov (United States)

An emerging class of VMEbus-based test and measurement instruments is benchmarked by a recently introduced digital spectrum analyzer. The instrument performs real-time spectrum analysis in the DC-to-10 MHz range at 5000 spectrums per second. Its architecture is based on the VMEbus and is partly adapted for high-speed pipeline processing. The keyboard and color graphic displays suit basic spectrum analysis, as well as advanced analysis of amplitude vs. both frequency and time. The instrument provides a DSP (digital signal processing) programming environment when an RS232 terminal is attached. With addition of an RF spectrum analyzer, downconverter, and software, real-time analysis is extended to 21 GHz and beyond. Postprocessable spectral output makes the instrument suitable for use in a larger signal analysis or test system. This digital spectrum analyzer, which has 17 boards on the bus, is representative of an emerging class of filled-enclosure instruments.

Snell, Jay

190

Mainlobe Jammer Nulling via TSI Finders: A Space Fast-Time Adaptive Processor  

Directory of Open Access Journals (Sweden)

Full Text Available An algorithm based on a space fast-time adaptive processor is presented for nulling the mainlobe jammer when the jammer and the target of interest share the same bearing. The computational load involved in the conventional processor, which blindly looks for the terrain-scattered interference (TSI, is required to stack a large number of consecutive range cell returns to form the space fast-time data snapshot making it almost impossible to implement in real time. This issue is resolved via the introduction of a preprocessor (a TSI finder which detects the presence of the minute levels of multipath components of the mainlobe jammer and associated time delays which directs the STAP processor to select only two desired range returns in order to form the space fast-time data snapshot. The end result is a computationally extremely fast processor. Also a new space fast-time adaptive processor based on the super-resolution approach (eigenvector-based is presented.

Madurasinghe Dan

2006-01-01

191

Signal and Noise Analysis in TRION -Time-Resolved Integrative Optical Fast Neutron Detector  

Digital Repository Infrastructure Vision for European Research (DRIVER)

TRION is a sub-mm spatial resolution fast neutron imaging detector, which employs an integrative optical time-of-flight technique. The detector was developed for fast neutron resonance radiography, a method capable of detecting a broad range of conventional and improvised explosives. In this study we have analyzed in detail, using Monte-Carlo calculations and experimentally determined parameters, all the processes that influence the signal and noise in the TRION detector. In...

Vartsky, D.; Feldman, G.; Mor, I.; Goldberg, M. B.; Bar, D.; Dangendorf, V.

2008-01-01

192

Time-domain fast fixed-point algorithms for convolutive ICA  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This letter presents new blind separation methods for moving average (MA) convolutive mixtures of independent MA processes. They consist of time-domain extensions of the FastICA algorithms developed by Hyvarinen and Oja for instantaneous mixtures. They perform a convolutive sphering in order to use parameter- free fast fixed-point algorithms associated with kurtotic or negentropic non-Gaussianity criteria for estimating the source innovation processes. We prove the relevance of this approach ...

Thomas, J.; Deville, Y.; Hosseini, Shahram

2006-01-01

193

Enhanced response of the regular networks to local signals in presence of a fast impurity  

CERN Document Server

We consider an array of inductively coupled Josephson junctions with a fast impurity (a junction with a smaller value of critical current), and study the consequences of imposing a small amplitude periodic signal at some point in the array. We find that when external signal is imposed at the impurity, the response of the array is boosted and a small amplitude signal can be detected throughout the array. When the signal is imposed elsewhere, minor effects is seen on the dynamics of the array. The same results have been also seen in presence of a single fast spiking neuron in a chain of diffusively coupled FitzHugh-Nagumo neurons.

Valizadeh, Alireza

2012-01-01

194

Method to Calculate Reference Currents to Achieve Fast Torque Response of IPMSM  

Science.gov (United States)

In this paper, a new method to calculate reference currents is proposed; this method can be used to achieve fast torque response of interior permanent magnet synchronous motors (IPMSMs). In the conventional method used to calculate the reference currents of IPMSMs, only the steady state condition is considered; the optimal reference currents under the transient condition are not taken into account. By using our proposed method, the torque response of an IPMSM can be enhanced and can be made twice as fast as the response achieved by using the conventional maximum torque per ampere (MTPA) method. Moreover, a method to ensure smooth transition from the transient condition to the steady state condition is also proposed in this paper. The effectiveness of the proposed methods is confirmed by many experimental results.

Lerdudomsak, Smith; Doki, Shinji; Okuma, Shigeru

195

Association between Cardiac Autonomic Function, Oxidative Stress and Inflammatory Response in Impaired Fasting Glucose Subjects: Cross-Sectional Study  

Science.gov (United States)

Background The worldwide burden of diabetes in 2030 is projected around 552 million. Diabetes leads to higher risk for cardiovascular diseases (CVD). Altered cardiac autonomic function (CAF) measured by heart rate variability (HRV) is observed in early stages of diabetes but the relationship between impaired fasting glucose (IFG) and HRV is still debatable. The aim of the study was to evaluate the association between CAF, oxidative stress, insulin resistance (IR), and inflammatory response in IFG subjects. Subjects and Methods Cross-sectional blinded study. Volunteers recruited from health awareness camps underwent CAF and biochemical tests. Based on fasting plasma glucose (FPG) participants (n?=?123) were divided into two groups, normal fasting glucose (n?=?76) and IFG (n?=?47). The comparison of parameters between the groups was carried out using student t test and Mann-Whitney U test for parametric and non-parametric data respectively. The correlation between the parameters was analyzed by Spearman’s rank correlation using SPSS 13.0. Results The resting cardiovagal modulation parameters, heart rate response to forced timed breathing, and orthostatic stress were reduced in IFG subjects. Fasting plasma lipid profile, coronary atherogenic lipid risk factors, IR, thiobarbituric acid reactive substance (TBARS), high sensitive C-reactive protein, and tumor necrosis factor alpha were increased and total antioxidant capacity (TAC) was decreased significantly in IFG group but no significant alteration was observed in high-density lipoprotein (HDL-c). Cardiovagal modulation parameters were negatively correlated with triglycerides, FPG, insulin, IR, TBARS, and inflammatory markers and positively with TAC. Conclusion There is a continuous interplay between the altered CAF, hyperinsulinemia, IR, oxidative stress parameters, inflammatory response, and IFG in which one factor perpetuates another leading to the progression of disease. PMID:22860025

Thiyagarajan, Ramkumar; Subramanian, Senthil Kumar; Sampath, Nishanth; Madanmohan Trakroo; Pal, Pravati; Bobby, Zachariah; Paneerselvam, Sankar; Das, Ashok Kumar

2012-01-01

196

Continuous data recording on fast real-time systems  

International Nuclear Information System (INIS)

The PCU-Project launched for the enhancement of the vertical stabilisation system at JET required the design of a new real-time control system with the challenging specifications of 2Gops and a cycle time of 50 ?s. The RTAI based architecture running on an x86 multi-core processor technology demonstrated to be the best platform for meeting the high requirements. Moreover, on this architecture thanks to the smart allocation of the interrupts it was possible to demonstrate simultaneous data streaming at 50 MBs on Ethernet while handling a real-time 100 kHz interrupt source with a maximum jitter of just 3 ?s. Because of the memory limitation imposed by 32 bit version Linux running in kernel mode, the RTAI-based new controller allows a maximum practical data storage of 800 MB per pulse. While this amount of data can be accepted for JET normal operation it posed some limitations in the debugging and commissioning of the system. In order to increase the capability of the data acquisition of the system we have designed a mechanism that allows continuous full bandwidth (56 MB/s) data streaming from the real-time task (running in kernel mode) to either a data collector (running in user mode) or an external data acquisition server. The exploited architecture involves a peer to peer mechanisms where the sender running in RTAI kernel mode broadcasts large chunks of data using UDP packets, implemented using the 'fcomm' RTAI extension , to a receiver that will store the data. Thea receiver that will store the data. The paper will present the results of the initial RTAI operating system tests, the design of the streaming architecture and the first experimental results.

197

Count-to-count time interval distribution analysis in a fast reactor  

International Nuclear Information System (INIS)

The most important kinetic parameters have been measured at the zero power fast reactor CORAL-I by means of the reactor noise analysis in the time domain, using measurements of the count-to-count time intervals. (Author) 69 refs

198

Fast Response and High Sensitivity ZnO/glass Surface Acoustic Wave Humidity Sensors Using Graphene Oxide Sensing Layer  

Science.gov (United States)

We report ZnO/glass surface acoustic wave (SAW) humidity sensors with high sensitivity and fast response using graphene oxide sensing layer. The frequency shift of the sensors is exponentially correlated to the humidity change, induced mainly by mass loading effect rather than the complex impedance change of the sensing layer. The SAW sensors show high sensitivity at a broad humidity range from 0.5%RH to 85%RH with < 1 sec rise time. The simple design and excellent stability of our GO-based SAW humidity sensors, complemented with full humidity range measurement, highlights their potential in a wide range of applications. PMID:25425458

Xuan, Weipeng; He, Mei; Meng, Nan; He, Xingli; Wang, Wenbo; Chen, Jinkai; Shi, Tianjin; Hasan, Tawfique; Xu, Zhen; Xu, Yang; Luo, J. K.

2014-01-01

199

Concentration of dilute sewage sludge slurry using EB crosslinked fast response temperature sensitive poly (vinyl methyl ether) hydrogel  

International Nuclear Information System (INIS)

Electron beam (EB) irradiation technique has been utilised to create non-homogeneous fast response temperature sensitive poly (vinyl methyl ether) (PVME) hydrogels. The crosslinked hydrogels were swollen in dilute sewage sludge samples at room temperature and dewatering was achieved by deswelling the hydrogels at 323 K. The results show that 1g gel could remove 9 to 12g of water from 25g of sludge, in ten cycles. The effect of various factors such as swelling/deswelling cycle time, solid content of sludge on the removal efficiency of water removal process has been investigated. (author)

200

An assessment of prompt neutron reproduction time in a reflector dominated fast critical system : ELECTRA  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, an accurate method to evaluate the prompt neutron reproduction time for a reflector dominated fast critical reactor, ELECTRA, is discussed. To adequately handle the problem, explicit time dependent Monte Carlo calculations with MCNP, applying repeated time cut-off technique, is used and compared against the ? ? 1/v time dependent absorber method, applying artificial cross section data in the Monte Carlo code SERPENT. The results show that when a reflector plays a major role ...

Suvdantsetseg, Erdenechimeg; Wallenius, Janne

2014-01-01

 
 
 
 
201

Fast-response temperature-sensitive-paint measurements on a hypersonic transition cone  

Science.gov (United States)

Experiments are performed using a fast-response temperature-sensitive-paint (TSP) technique to measure the heat-flux distribution on a slender cone in a hypersonic shock tunnel under both laminar and transitional conditions. The millisecond-order test duration together with the self-luminosity of shock layers place stringent conditions on the choice of TSP luminophore and the TSP-layer thickness that can be employed. The luminosity and dimming from particulates in the free-stream cause additional problems in interpreting the obtained intensity profiles. Nevertheless, favorable agreement with thermocouple-based measurements show that it is possible to derive quantitatively accurate heat-flux distributions with the TSP technique for temperature rises of up to approximately 40 K above room temperature. The technique accuracy is adversely affected at higher temperatures, which is thought to result from non-constant thermal properties of the insulating base layer. At high unit Reynolds number conditions, time-resolved heat-flux distributions show large-scale unsteadiness in the boundary-layer transition location and reveal transient streamwise streaks developing in the transitional region.

Ozawa, H.; Laurence, S. J.; Schramm, J. Martinez; Wagner, A.; Hannemann, K.

2015-01-01

202

Analysis of the ballistic impact response of a composite material using FAST Infrared Imagery  

Science.gov (United States)

The level of protection offered by a given ballistic material is typically evaluated in terms of a set of projectiles and their associated velocity at which a certain percentage of the projectiles are expected to perforate. (i.e. FSP 17gr : V50 = 500m/s, 9mm FMJ; V0=500m/s). These metrics give little information about the physical phenomena by which energy is dispersed, spread or absorbed in a specific target material. Aside from post-test inspection of the impacted material, additional information on the target response is traditionally obtained during a test from the use of high speed imaging, whether it is from a single camera aimed at the impact surface or the backface, or from a set of camera allowing full 3-D reconstruction of a deformed surface. Again, this kind of data may be difficult to interpret if the interest is in the way energy is managed in the target in real time. Recent technological progress in scientific grade high-speed infrared (IR) camera demonstrated that these phenomena can straightforwardly be measured using IR thermal imaging. This paper presents promising results obtained from Telops FAST-IR 1500 infrared camera on an aramid-based ballistic composite during an impact from a small caliber fragment simulating projectile (FSP).

Marcotte, Frederick; Ouellet, Simon; Farley, Vincent

2013-05-01

203

Observation of very fast response signals from Pb absorber coupled transition edge sensor gamma-ray microcalorimeter  

Energy Technology Data Exchange (ETDEWEB)

We are developing a gamma-ray microcalorimeter for Positron Annihilation Spectroscopy. Our detector composed of a transition edge sensor (TES) thermometer and an epoxy coupled bulk Pb absorber has been reported an energy resolution of 4.7 keV FWHM at 662 keV with a tens of milliseconds long response time. To enhance the detector properties, we designed a new attachment method in the focus of improving the thermal coupling between the absorber and the TES. In the new design, we created epoxy-posts both on the TES film and on the absorber, and then they were connected together using an epoxy-dot put on the epoxy-post on the absorber. Measured current signal of this epoxy-post TES gamma-ray detector showed an ultra fast response with 80 {mu}s fall time.

Damayanthi, R.M.T., E-mail: thushara@sophie.q.t.u-tokyo.ac.jp [Department of Nuclear Engineering and Management, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Ohno, M.; Hatakeyama, S.; Takahashi, H. [Department of Nuclear Engineering and Management, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Maehata, K.; Yasumune, T.; Iyomoto, N. [Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Motooka, Nishi-ku, Fukuoka 819-0395 (Japan)

2012-11-01

204

Ultra Fast Timing Measurements at $^{78}$Ni and $^{132}$Sn  

CERN Multimedia

We propose to measure level lifetimes in the exotic nuclei of $^{81}$Ga and $^{80}$Ga in the vicinity of $^{78}$Ni and of $^{135}$Sb and $^{134}$Sb above $^{132}$Sn by the time-delayed technique. These are relatively simple nuclear systems with a few particles and/or holes outside of the doubly-magic core thus can be treated rather precisely within the shell model. The anticipated new structure information on these nuclei, and in particular the lifetime results will put constrains on the model parameters and will serve to verify their predictions. The selected nuclei are some of the most exotic ones just above $^{78}$Ni or $^{132}$Sn, where the transition rates can be studied at present. Of the strongest interest is the nucleus of $^{81}$Ga, which has only 3 valence protons outside of $^{78}$Ni with the lowest proton orbits being $\\emph{p}_{3/2}$ and $\\emph{f}_{5/2}$. The Ml transition between these states, although allowed by the selection rules, should be $\\emph{l}$-forbidden thus very slow. This should giv...

2002-01-01

205

Bounds of fast decodability of space time block codes, skew-Hermitian matrices, and Azumaya algebras  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study fast lattice decodability of space-time block codes for $n$ transmit and receive antennas, written very generally as a linear combination $\\sum_{i=1}^{2l} s_i A_i$, where the $s_i$ are real information symbols and the $A_i$ are $n\\times n$ $\\mathbb R$-linearly independent complex valued matrices. We show that the mutual orthogonality condition $A_iA_j^* + A_jA_i^*=0$ for distinct basis matrices is not only sufficient but also necessary for fast decodability. We buil...

Berhuy, Gre?gory; Markin, Nadya; Sethuraman, B. A.

2014-01-01

206

Sensitivity Analysis of Reprocessing Cooling Times on Light Water Reactor and Sodium Fast Reactor Fuel Cycles  

International Nuclear Information System (INIS)

The purpose of this study is to quantify the effects of variations of the Light Water Reactor (LWR) Spent Nuclear Fuel (SNF) and fast reactor reprocessing cooling time on a Sodium Fast Reactor (SFR) assuming a single-tier fuel cycle scenario. The results from this study show the effects of different cooling times on the SFR's transuranic (TRU) conversion ratio (CR) and transuranic fuel enrichment. Also, the decay heat, gamma heat and neutron emission of the SFR's fresh fuel charge were evaluated. A 1000 MWth commercial-scale SFR design was selected as the baseline in this study. Both metal and oxide CR=0.50 SFR designs are investigated

207

3-D seismic response of a base-isolated fast reactor  

International Nuclear Information System (INIS)

This paper describes a 3-D response analysis methodology development and its application to a base-isolated fast breeder reactor (FBR) plant. At first, studies on application of a base-isolation system to an FBR plant were performed to identify a range of appropriate characteristics of the system. A response analysis method was developed based on mathematical models for the restoring force characteristics of several types of the systems. A series of shaking table tests using a small scale model was carried out to verify the analysis method. A good agreement was seen between the test and analysis results in terms of the horizontal and vertical responses. Parametric studies were then made to assess the effects of various factors which might be influential to the seismic response of the system. Moreover, the method was applied to evaluate three-dimensional response of the base-isolated FBR. (author)

208

Improving Adaptive Learning Technology through the Use of Response Times  

Science.gov (United States)

Adaptive learning techniques have typically scheduled practice using learners' accuracy and item presentation history. We describe an adaptive learning system (Adaptive Response Time Based Sequencing--ARTS) that uses both accuracy and response time (RT) as direct inputs into sequencing. Response times are used to assess learning strength and…

Mettler, Everett; Massey, Christine M.; Kellman, Philip J.

2011-01-01

209

ALBA timing system - a known architecture with fast interlock system upgrade  

International Nuclear Information System (INIS)

Like most of the newest synchrotron facilities the ALBA Timing System works on event based architecture. Its main particularity is that integrated with the Timing system a Fast Interlock System has been implemented which allows for an automated and synchronous reaction time from any-to-any point of the machine faster than 5 ?s. The list of benefits of combining both systems is large: very high flexibility, reuse of the timing actuators, direct synchronous output in different points of the machine reacting to an interlock, implementation of the Fast Interlock with very low cost increase as the timing optic fiber network is reused or the possibility of combined diagnostic tools implementation for triggers and interlocks. To enhance this last point a global time-stamp of 8 ns accuracy that could be used both for triggers and interlocks has been implemented. The system has been designed, installed and extensively used during the Storage Ring commissioning with very good results. (authors)

210

Fast Response to Infection Spread and Cyber Attacks on Large-Scale Networks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a strategy for designing fast methods of response to cyber attacks and infection spread on complex weighted networks. In these networks, nodes can be interpreted as primitive elements of the system, and weighted edges reflect the strength of interaction among these elements. The proposed strategy belongs to the family of multiscale methods whose goal is to approximate the system at multiple scales of coarseness and to obtain a solution of microscopic scale by comb...

Leyffer, Sven; Safro, Ilya

2012-01-01

211

Analysis of the dynamic response of layered, elastic media by means of the Fast Fourier Transform:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A straightforward method is presented to calculate the three-dimensional response of layered, elastic half-spaces to a dynamic surface loading. The derivation of the method is performed in the wavenumber-frequency domain. Space-frequency domain results are subsequently obtained through the application of the Fast Fourier Transform. The results show good agreements with the static solutions of Boussinesq and the dynamic solutions of Lamb.

Abdelkarim, A. M. A. M.; Vrouwenvelder, A. C. W. M.

1999-01-01

212

Nano-gel containing thermo-responsive microspheres with fast response rate owing to hierarchical phase-transition mechanism.  

Science.gov (United States)

A new strategy is developed in this study to achieve thermo-responsive microspheres with fast response rates by designing a hierarchical phase-transition mechanism. The proposed thermo-responsive microspheres are composed of poly(N-isopropylacrylamide-co-acrylic acid) (PNA) microsphere matrixes and embedded poly(N-isopropylacrylamide) (PNIPAM) nano-gels, which have different volume phase-transition temperatures (VPTTs). The VPTT of PNIPAM nano-gels (VPTT(1)) is lower than that of PNA microsphere matrixes (VPTT(2)). Upon heating-up, the temperature increases across the VPTT(1) first and then the VPTT(2), as a result the PNIPAM nano-gels shrink earlier than the PNA microsphere matrixes. Upon cooling-down, the temperature decreases across the VPTT(2) first and then the VPTT(1), as a result the PNA microsphere matrixes swell earlier than the PNIPAM nano-gels. Consequently, large amounts of voids and channels form around the nano-gels inside the microsphere matrixes when the temperature changes across the range between VPTT(1) and VPTT(2), which are beneficial to the enhancement of water transport rate inside the microsphere matrixes. The experimental results show that, compared with normal homogeneous PNA (N-PNA) microspheres, the nano-gel containing PNA (C-PNA) microspheres exhibit remarkably fast response rate due to the hierarchical phase-transition mechanism attributed to different VPTT values of the embedded nano-gels and the microsphere matrixes. PMID:22542479

Yue, Li-Li; Xie, Rui; Wei, Jie; Ju, Xiao-Jie; Wang, Wei; Chu, Liang-Yin

2012-07-01

213

Preparation and properties of fast temperature-responsive soy protein/PNIPAAm IPN hydrogels  

Directory of Open Access Journals (Sweden)

Full Text Available The interpenetrating polymer network of fast temperature-responsive hydrogels based on soy protein and poly(N-isopropylacrylamide were successfully prepared using the sodium bicarbonate (NaHCO3 solutions as the reaction medium. The structure and properties of the hydrogels were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry and thermal gravimetric analysis. The swelling and deswelling kinetics were also investigated in detail. The results have shown that the proposed hydrogels had high porous structure, good miscibility and thermal stability, and fast temperature responsivity. The presence of NaHCO3 had little effect on the volume phase transition temperature (VPTT of the hydrogels, and the VPTTs were at about 32°C. Compared with the traditional hydrogels, the proposed hydrogels had much faster swelling and deswelling rate. The swelling mechanism of the hydrogels was the non-Fickian diffusion. This fast temperature-responsive hydrogels may have potential applications in the field of biomedical materials.

Liu Yong

2014-01-01

214

Fast response of lake plankton and nutrients to river inundations on floodplain lakes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Key variables in ecosystems tend to operate on widely different time-scales. These time-scales become relevant when a disturbance rocks the ecosystem. Here we try to explain the fast dynamics of plankton and nutrients in the water column of floodplain lakes after disturbances (inundations). We take advantage of natural experiments, that is occasional massive overflow of floodplain lakes with river water. We sampled 10 lakes in two floodplains along the Dutch river Waal monthly for 3 years, ca...

Roozen, F. C. J. M.; Peeters, E. T. H. M.; Roijackers, R. M. M.; Wyngaert, I. J. J.; Wolters, H.; Coninck, H. C.; Ibelings, B. W.; Buijse, A. D.; Scheffer, M.

2008-01-01

215

TRANC – a novel fast-response converter to measure total reactive atmospheric nitrogen  

Directory of Open Access Journals (Sweden)

Full Text Available The input and loss of plant available nitrogen (N from/to the atmosphere can be an important factor for the productivity of ecosystems and thus for its carbon and greenhouse gas exchange. We present a novel converter for the measurement of total reactive nitrogen (TRANC: Total Reactive Atmospheric Nitrogen Converter, which offers the opportunity to quantify the sum of all airborne reactive nitrogen (Nr compounds in high time resolution. The basic concept of the TRANC is the full conversion of total Nr to nitrogen monoxide (NO within two reaction steps. Initially, reduced N compounds are being oxidised, and oxidised N compounds are thermally converted to lower oxidation states. Particulate N is being sublimated and oxidised or reduced afterwards. In a second step, remaining higher N oxides or those originated in the first step are catalytically converted to NO with carbon monoxide used as reduction gas. The converter is combined with a fast response chemiluminescence detector (CLD for NO analysis and its performance was tested for the most relevant gaseous and particulate Nr species under both laboratory and field conditions. Recovery rates during laboratory tests for NH3 and NO2 were found to be 95 and 99%, respectively, and 97% when the two gases were combined. In-field longterm stability over an 11-month period was approved by a value of 91% for NO2. Effective conversion was also found for ammonium and nitrate containing particles. The recovery rate of total ambient Nr was tested against the sum of individual measurements of NH3, HNO3, HONO, NH4+, NO3?, and NOx using a combination of different well-established devices. The results show that the TRANC-CLD system precisely captures fluctuations in Nr concentrations and also matches the sum of all Nr compounds measured by the different single techniques. The TRANC features a specific design with very short distance between the sample air inlet and the place where the thermal and catalytic conversions to NO occur. This assures a short residence time of the sample air inside the instrument, and minimises wall sorption problems of water soluble compounds. The fast response time (half-value periods of 0.30 s were found during concentration step changes and high accuracy in capturing the dominant Nr species enables the converter to be used in an eddy covariance setup. Although a source attribution of specific Nr compounds is not possible, the TRANC is a new reliable tool for permanent measurements of the net Nr flux between ecosystem and atmosphere at a relatively low maintenance and reasonable cost level allowing for diurnal, seasonal and annual investigations.

O. Marx

2011-12-01

216

Response of urinary hydroxyproline to dietary protein and fasting in white-tailed deer  

Science.gov (United States)

The effects of dietary protein, fasting, and refeeding on urinary hydroxyproline of nine captive female white-tailed deer (Odocoileus virginianus) were examined from 23 February to 3 May 1984 in northern Minnesota. In the fasted group, mean hydroxyproline:creatinine (OHP:C) was greater (P less than 0.05) at week 4 compared to baseline at week 0. Between fasted deer and deer fed high protein-high energy (HPHE) and low protein-high energy (LPHE) diets, no difference in OHP:C ratios was detected during the initial 4 wk of the study. Urinary OHP:C ratios were significantly (P less than 0.05) greater in the fasted group during refeeding, concomitant with greater feed consumption and weight gain. There was also a significant (P less than 0.02) time effect in the fasted-refed group; OHP:C ratios increased during these two phases of the study. There was no difference between the HPHE and LPHE fed deer in renal OHP excretion. However, mean OHP:C ratios in yearlings (16.8 +/- 2.2) were greater (P less than 0.001) than in the adults (7.5 +/- 1.2) of those groups, indicating a higher collagen turnover rate. Urinary OHP:C shows potential as an indicator of growth and starvation, and the data presented may serve as reference values.

DelGiudice, G.D.; Seal, U.S.; Mech, L.D.

1988-01-01

217

Long Time Response of Aging Glassy Polymers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Aging amorphous polymeric materials undergo free volume relaxation, which causes slowing down of the relaxation dynamics as a function of time. The resulting time dependency poses difficulties in predicting their long time physical behavior. In this work, we apply effective time domain approach to the experimental data on aging amorphous polymers and demonstrate that it enables prediction of long time behavior over the extraordinary time scales. We demonstrate that, unlike t...

Joshi, Yogesh M.

2014-01-01

218

The time course of glycogen depletion in single fibers of chronically stimulated rabbit fast-twitch muscle.  

Science.gov (United States)

A time course study was conducted to investigate the possibility of a relationship between fiber degeneration and glycogen depletion in chronically nerve-stimulated extensor digitorum longus muscle of the rabbit. Muscles were stimulated 12 h daily at 10 Hz using alternating one-hour periods of stimulation and rest. When measured for the first time after 3 h (1 h stimulation, 1 h rest, 1 h stimulation), microphotometry revealed complete glycogen depletion of all fiber types (fast glycolytic, FG; fast oxidative glycolytic, FOG; slow oxidative, SO). Different responses were noted beginning at day 4. At this time point, all FOG and SO fibers recovered their glycogen stores with some of the FOG population attaining levels higher than the FOG fibers in the unstimulated, contralateral muscle. Approximately 28% of the FG fibers recovered to normal glycogen values, whereas 58% remained depleted and 14% displayed "overshooting glycogen" levels. Fifteen percent of all fibers were glycogen-depleted after 12 days of stimulation. At this time, classic fiber types could no longer be distinguished. Fiber degeneration, which was recognized by the invasion of nonmuscle cells, began after 6 days and was restricted to the glycogen-depleted fibers. By this time, there was also a significant increase in DNA content. Exhaustion of glycogen, the main fuel of the FG fibers, is believed to cause a collapse of energy-supply and ATP-driven ionic pumps. The latter could be the initial step of fiber deterioration. PMID:3588252

Maier, A; Pette, D

1987-04-01

219

Fast rise time, long pulse width, kilohertz repetition rate Q-switch driver  

Science.gov (United States)

We describe a versatile Pockels cell Q-switch driver that can generate high voltage electrical pulses having both fast rise times and long duration, with a repetition rate in excess of 1kHz. The circuit is simple and easily adaptable to most types of Q-switched lasers and regenerative amplifiers.

Rutten, Thomas P.; Wild, Neville; Veitch, Peter J.

2007-07-01

220

A measurement of the fast luminescent decay time of P-15 phosphor.  

Science.gov (United States)

The fast decay time of a 3900-A spectral component of an electron-beam excited P-15 phosphor has been measured using a delayed coincidence technique. The result, 1.04 nsec plus or minus nearly 2%, is in good agreement with previous estimates.

Sutton, J. F.

1972-01-01

 
 
 
 
221

Effects of fractionated doses of fast neutrons or photons on the canine brain: evaluation by computerized tomography and evoked response recording  

International Nuclear Information System (INIS)

The use of fast neutrons in the treatment of cancer necessitates a knowledge of the normal tissue responses. This study was designed to compare the late effects of fractionated doses of fast neutrons with fractionated doses of photons on canine brains by evoked response recording and viewing computerized tomograms (CT). A relative biological effectiveness (RBE) of 4 was obtained for normal brain tissue assessed by mortality and onset of neurologic symptoms. Every three months post-irradiation, visual and sensory evoked responses were recorded. Changes over time appeared to be minimal; however, computerized tomographs showed marked brain shrinkage. A method of quantitating cerebrospinal fluid and parenchymal volumes from scans is described and future use of these CT ratios to generate dose response curves and RBE values is postulated

222

Does short-term fasting lead to stressed-out parents? A study of incubation commitment and the hormonal stress responses and recoveries in snow petrels.  

Science.gov (United States)

The hormonal stress response is flexible and can be modulated by individuals according to its costs and benefits. Therefore, it is predicted that parents in poor body condition should modify their hormonal stress response, and thus, redirect energy allocation processes from parental care to self-maintenance when stressors occur. To test this prediction, most studies on free-living vertebrates have only focused on the stress response while the stress recovery - how quickly hormonal levels return to baseline values - has been neglected. Moreover, most studies have only focused on corticosterone - the primary mediator of allostasis - without paying attention to prolactin despite its major role in mediating parental behaviors. Here, we examined the effect of a short-term fasting event on the corticosterone and prolactin stress responses and recoveries, and we subsequently explored their relationships with parental decision in the snow petrel (Pagodroma nivea). By comparing the hormonal profiles of fasting and non-fasting snow petrels, we showed that parents modulate their corticosterone (but not prolactin) stress response according to their energetic status. We also described for the first time the hormonal stress recoveries in wild birds and found that they did not differ between fasting and non-fasting birds. Importantly, egg neglect was negatively correlated with circulating prolactin but not corticosterone levels in this species, demonstrating therefore a complex link between body condition, parental behavior and circulating corticosterone and prolactin levels. We suggest that both corticosterone and prolactin play a major role in the way parents adjust to stressors. This multiple signaling may allow parents to fine-tune their response to stressors, and especially, to activate specific allostasis-related mechanisms in a timely manner. PMID:25456104

Angelier, Frédéric; Wingfield, John C; Parenteau, Charline; Pellé, Marie; Chastel, Olivier

2015-01-01

223

Response time measurement for a filter- X-ray diode detection system  

International Nuclear Information System (INIS)

The detection system consists of filter, XRD, SUJ-50-10 cable and different band oscillograph. 20 TW laser facility of Shanghai Laser Unite Laboratory with energy about 20J, pulse width about 1ps was used, and Au foil target irradiated by laser pulse produced X-ray emission. Note oscillograph types have TK684C, TK694C and WM8500. The linear fit and comparison analysis of experiment data are proceeded. The response time of a filter-XRD detection system become fast along with based voltage, and become slow along with cable length. Therefore, when fast signal is measured, based voltage of detector must be increased, and cable length shorten, and high band oscillograph selected, in order to reduce system response time and decrease signal distortion. (authors)

224

Digital timing walk correction and its application to a time-dependent fast neutron energy spectrum measurement  

International Nuclear Information System (INIS)

Timing walk is the pulse height dependent shift in the mean time at which a discriminator triggers. If there is any such walk, when a pulse height spectrum is sampled over short time intervals, as is the case in time-dependent fast neutron spectroscopy, severe distortions to the pulse height spectrum can occur. Results are given of measurements of walk and consequent pulse height spectrum distortions. A procedure which uses an on-line computer to compensate for walk is described and its effectiveness evaluated. A study is made of distortions of time-dependent spectra, resulting from noise which broadens time resolution at low pulse amplitudes. The reduction of timing walk to +- 35 ps is illustrated for a time-dependent neutron energy spectrum measurement. (orig.)

225

Fast real-time NMR methods for characterizing short-lived molecular states.  

Science.gov (United States)

The characterization of both the structure and the conformational dynamics of biological macromolecules, namely proteins and nucleic acids, is required for understanding the molecular mechanisms underlying physiological function and disease. Molecular dynamics involves the transient departure from the ground-state structures to populate short-lived excited state conformations that can play important functional roles. Real-time multi-dimensional NMR spectroscopy represents a unique tool for investigating dynamic molecular processes occurring on time scales of seconds or longer, providing atomic-resolution information about short-lived states. In this minireview, we discuss recent progress made in the field of fast real-time multidimensional NMR. The potential of these new methods is illustrated for several biomolecular systems that have recently been studied by fast real-time multidimensional NMR. PMID:23857553

Rennella, Enrico; Brutscher, Bernhard

2013-09-16

226

Realization of fast reversal time for toroidal field in TPE-2M  

Energy Technology Data Exchange (ETDEWEB)

A new idea for capacitor bank system in order to obtain a fast rising of about 1 ms for toroidal field in a SUS vacuum chamber having a skin time of 5.1 ms is described. In reversed field pinch (RFP), the magnetic fields for toroidal and poloidal directions are induced in the vacuum chamber, and the toroidal field is reversed at plasma setting up phase. In TPE-2M the reversal time of coil current was 1 ms, while the reversal time of toroidal magnetic field was 6 ms. This difference comes from mainly the skin effect of SUS chamber. In order to realize the fast set up of RFP phase, we investigated the some methods to quicken the reversal time of magnetic field to the extent of 1 ms. The new method of fitting a operating condition and simple reconstruction of bank system was investigated with computer simulation and was proved to be effective from the experimental result. (author)

Sato, Y.; Kiyama, S.; Hayase, K. [Electrotechnical Lab., Tsukuba-shi, Ibaraki (Japan)

1998-07-01

227

Realization of fast reversal time for toroidal field in TPE-2M  

International Nuclear Information System (INIS)

A new idea for capacitor bank system in order to obtain a fast rising of about 1 ms for toroidal field in a SUS vacuum chamber having a skin time of 5.1 ms is described. In reversed field pinch (RFP), the magnetic fields for toroidal and poloidal directions are induced in the vacuum chamber, and the toroidal field is reversed at plasma setting up phase. In TPE-2M the reversal time of coil current was 1 ms, while the reversal time of toroidal magnetic field was 6 ms. This difference comes from mainly the skin effect of SUS chamber. In order to realize the fast set up of RFP phase, we investigated the some methods to quicken the reversal time of magnetic field to the extent of 1 ms. The new method of fitting a operating condition and simple reconstruction of bank system was investigated with computer simulation and was proved to be effective from the experimental result. (author)

228

A novel fast gas chromatography method for higher time resolution measurements of speciated monoterpenes in air  

Science.gov (United States)

Biogenic emissions supply the largest fraction of non-methane volatile organic compounds (VOC) from the biosphere to the atmospheric boundary layer, and typically comprise a complex mixture of reactive terpenes. Due to this chemical complexity, achieving comprehensive measurements of biogenic VOC (BVOC) in air within a satisfactory time resolution is analytically challenging. To address this, we have developed a novel, fully automated Fast Gas Chromatography (Fast-GC) based technique to provide higher time resolution monitoring of monoterpenes (and selected other C9-C15 terpenes) during plant emission studies and in ambient air. To our knowledge, this is the first study to apply a Fast-GC based separation technique to achieve quantification of terpenes in ambient air. Three chromatography methods have been developed for atmospheric terpene analysis under different sampling scenarios. Each method facilitates chromatographic separation of selected BVOC within a significantly reduced analysis time compared to conventional GC methods, whilst maintaining the ability to quantify individual monoterpene structural isomers. Using this approach, the C9-C15 BVOC composition of single plant emissions may be characterised within a 14.5 min analysis time. Moreover, in-situ quantification of 12 monoterpenes in unpolluted ambient air may be achieved within an 11.7 min chromatographic separation time (increasing to 19.7 min when simultaneous quantification of multiple oxygenated C9-C10 terpenoids is required, and/or when concentrations of anthropogenic VOC are significant). These analysis times potentially allow for a twofold to fivefold increase in measurement frequency compared to conventional GC methods. Here we outline the technical details and analytical capability of this chromatographic approach, and present the first in-situ Fast-GC observations of 6 monoterpenes and the oxygenated BVOC (OBVOC) linalool in ambient air. During this field deployment within a suburban forest ~30 km west of central Tokyo, Japan, the Fast-GC limit of detection with respect to monoterpenes was 4-5 ppt, and the agreement between Fast-GC and PTR-MS derived total monoterpene mixing ratios was consistent with previous GC/PTR-MS comparisons. The measurement uncertainties associated with the Fast-GC quantification of monoterpenes are ? 12%, while larger uncertainties (up to ~25%) are associated with the OBVOC and sesquiterpene measurements.

Jones, C. E.; Kato, S.; Nakashima, Y.; Kajii, Y.

2014-05-01

229

A fasting-induced decrease in plasma glucose concentration does not affect the insulin response to ingested protein in people with type 2 diabetes.  

Science.gov (United States)

We previously have reported that protein, on a weight basis, is just as potent as glucose in increasing the insulin concentration in people with type 2 diabetes. In people without diabetes, protein is only approximately 30% as potent as glucose in this regard. In the present study, we tested the hypothesis that the increased insulin responsiveness to protein in people with type 2 diabetes is due to the elevated plasma glucose concentration in these individuals. Seven male subjects with untreated type 2 diabetes were given 50 g protein in the form of very lean beef at 8 AM after an overnight fast. On another occasion, the same individuals were fasted for an additional 24 hours to lower their plasma glucose concentration to near the normal reference range. They were then given 50 g protein. The 8 AM glucose concentration was lower after 24 hours of additional fasting, as expected. After ingestion of the protein meal, there was an unexpected, modest increase in glucose concentration after an additional 24 hours of fasting that was not observed with only an overnight fast. Despite the approximately 15% lower plasma glucose concentration at the time of the protein meal, the insulin responses were nearly identical. Thus, the greater insulin response to ingested protein is not likely to be due merely to a higher initial glucose concentration. PMID:12145777

Saeed, Asad; Jones, Sidney A; Nuttall, Frank Q; Gannon, Mary C

2002-08-01

230

Response of some French beans (Phaseolus vulgaris L) varieties to fast neutron irradiation  

International Nuclear Information System (INIS)

Response of some French beans (Phaseolus vulgaris L.) varieties to fast neutron irradiation. Seeds of French beans varieties, i.e. Local Bandung (white seed), Local Surakarta and Monel (black seed), and Hawaiian Wonder (brown seed) were irradiated with fast neutrons. Irradiation was carried out in the USIF of the TRIGA MARK II Reactor in the Research Centre for Nuclear Techniques Bandung, with doses of 7,5, 15,0, 22,5, 30,0, 37,5 and 45,0 Gy. Irradiated seeds were planted in plastic pots and grown in the green house. The responses of the seedlings to neutron irradiation were observed by measuring the length of hypocotyl, epicotyl and primary leaf size (length and width). The result of the study showed that epicotyl is the most sensitive to fast neutron irradiation followed by primary leaf size and hypocotyl. The D50 for the four varieties measured were significantly different. It was also shown that the black seed varieties were relatively more radioresistant than the other two. (author). 3 figs, 13 refs

231

Note: A timing micro-channel plate detector with backside fast preamplifier  

International Nuclear Information System (INIS)

A timing micro-channel plate detector with a backside double-channel fast preamplifier was developed to avoid distortion during signal propagation from the anode to the preamplifier. The mechanical and electronic structure is described. The detector including its backside preamplifier is tested by a 241Am ?-source and a rise time of ?2 ns with an output background noise of 4 mVrms was achieved

232

Note: A timing micro-channel plate detector with backside fast preamplifier  

Science.gov (United States)

A timing micro-channel plate detector with a backside double-channel fast preamplifier was developed to avoid distortion during signal propagation from the anode to the preamplifier. The mechanical and electronic structure is described. The detector including its backside preamplifier is tested by a 241Am ?-source and a rise time of ˜2 ns with an output background noise of 4 mVrms was achieved.

Wang, Wei; Yu, Deyang; Lu, Rongchun; Liu, Junliang; Cai, Xiaohong

2014-03-01

233

Studies on fast timing and high precision tracking performance of Resistive Plate Chamber  

CERN Document Server

Resistive plate chambers (RPC), produced in large scales, are widely used as trigger detectors with O(ns) time resolution in high energy and high intensity experiments. To confront the future high experimental frontiers, such as the super-LHC, RPCs equipped with fine-pitch readout strips were tested with 180GeV/c muon at CERN SPS H8 beam line, to assess the viability of using RPCs for both fast timing and high precision tracking trigger.

Han, L; The ATLAS collaboration

2013-01-01

234

Note: A timing micro-channel plate detector with backside fast preamplifier  

Energy Technology Data Exchange (ETDEWEB)

A timing micro-channel plate detector with a backside double-channel fast preamplifier was developed to avoid distortion during signal propagation from the anode to the preamplifier. The mechanical and electronic structure is described. The detector including its backside preamplifier is tested by a {sup 241}Am ?-source and a rise time of ?2 ns with an output background noise of 4 mV{sub rms} was achieved.

Wang, Wei [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Yu, Deyang, E-mail: d.yu@impcas.ac.cn; Lu, Rongchun; Liu, Junliang; Cai, Xiaohong [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2014-03-15

235

A multi-angle detector system for fast neutron time-of-flight spectroscopy  

International Nuclear Information System (INIS)

A multi-angle fast neutron time-of-flight spectrometer operating in the nanosecond range is described. The system consists of eight detectors at angles between 200 and 1600. For all the detectors only one time-to-pulse height converter is used. The pulsed 10 MeV tandem accelerator, the detectors and electronic circuity, the computer coupling and a neutron producing gas target are discussed. Examples of experimental application are given. (orig.)

236

Neutron direct-radiation response of medium-type fast-neutron detector  

International Nuclear Information System (INIS)

The medium-type fast-neutron detector responds to direct neutron irradiation and it has an extreme effect on its design and practical applications. Monte-Carlo simulation programs based on Geant4 toolkit are developed to study the neutron direct radiation response sensitivity of the medium-type fast-neutron detector. The emission of the charged heavy particles of commonly used materials of detector's sensitive unit due to neutron incidence is simulated. The result shows that the selection of the materials of the charge collector, the threshold absorber and the rear isolator directly affect on the response sensitivity of neutron direct radiation. The response sensitivity of neutron direct radiation contributes about 6% to the total neutron sensitivity in the present sensitive unit which uses a graphite sensitive collector and Teflon threshold absorber and rear isolator. An improved structure of sensitive unit using high resistance graphite as the material of the threshold absorber and a rear isolator instead of Teflon is discussed, which can effectively reduce the response sensitivity of neutron direct radiation. (authors)

237

Performance and microbial response during the fast reactivation of Anammox system by hydrodynamic stress control.  

Science.gov (United States)

Anaerobic ammonium oxidation (Anammox) has become a promising method for biological nitrogen removal. However, this biotechnology application is always limited due to the low growth rate and biomass yield of Anammox bacteria. This study investigated the process of fast reactivation of an Anammox consortium idled for 2 years via hydrodynamic stress control. The results showed that the Anammox system was efficiently and quickly reactivated by shortening of the hydraulic retention time (HRT) of the reactor from 12 to 6 hr within 68 days of operation. Moreover, at a 4-hr HRT with an influent total nitrogen loading rate of 1.2kg N/(m(3)·day), the reactor maintained high biological performance with an ammonium removal loading rate of 0.52kg N/(m(3)·day) and a nitrite removal rate of 0.59kg N/(m(3)·day). In the reactivated Anammox reaction, the stoichiometric coefficients of NH4(+)-N to NO2(-)-N and NH4(+)-N to NO3(-)-N were 1:1.04±0.08 and 1:0.31±0.03, respectively. The specific Anammox activity and hydrazine oxidoreductase activity, both of which represent the degree of Anammox bacteria present, increased as the hydrodynamic stress increased and were maximally (125.38±3.01mg N/(g VSS·day) and 339.42±6.83?mol/(min·g VSS), respectively) at 4-hr HRT. Microbial response analysis showed that the dominant microbial community was obviously shifted and the dominance of Anammox bacteria was enhanced during the hydrodynamic selection. PMID:25193835

Li, Yuan; Huang, Zhenxing; Ruan, Wenquan; Ren, Hongyan; Miao, Hengfeng

2014-09-01

238

The reality of the surgical fasting time in the era of the ERAS protocol.  

Science.gov (United States)

Multimodal protocols to optimize perioperative care and to accelerate postoperative recovery include abbreviated pre-and postoperative fasting. The aim of this study was to investigate the pre and postoperative fasting period and the factors that influence it in patients who underwent elective operations. We included patients who underwent surgery of the digestive tract and abdominal wall. Data were collected from the patients and from their personal health records. We included 135 patients between 19 and 89 years old. Most were adults (75.55%), female (60.74%) and the most common procedures were hernioplasty (42.96%) and cholecystectomy (34.81%). The preoperative fasting periods for solids and liquids were similar, median 16.50 (5.50-56.92) and 15.75 (2.50- 56.92) hours, respectively. The preoperative fasting period was influenced by the instruction received and surgery time. Postoperative fasting period was 15.67 (1.67-90.42) hours and was influenced by type of surgery and lack of synchrony between the clinical meeting and the nutrition and dietetics service schedules. PMID:24528365

Cestonaro, Talita; Madalozzo Schieferdecker, Maria Eliana; Thieme, Rubia Daniela; Neto Cardoso, João; Ligocki Campos, Antônio Carlos

2014-01-01

239

Efficient allocation of heterogeneous response times in information spreading process  

CERN Document Server

Recently, the impacts of spatiotemporal heterogeneities of human activities on spreading dynamics have attracted extensive attention. In this paper, to study heterogeneous response times on information spreading, we focus on the susceptible-infected spreading dynamics with adjustable power-law response time distribution based on uncorrelated scale-free networks. We find that the stronger the heterogeneity of response times is, the faster the information spreading is in the early and middle stages. Following a given heterogeneity, the procedure of reducing the correlation between the response times and degrees of individuals can also accelerate the spreading dynamics in the early and middle stages. However, the dynamics in the late stage is slightly more complicated, and there is an optimal value of the full prevalence time changing with the heterogeneity of response times and the response time-degree correlation, respectively. The optimal phenomena results from the efficient allocation of heterogeneous respon...

Cui, Ai-Xiang; Tang, Ming; Fu, Yan; Liang, Xiaoming; Do, Younghae

2014-01-01

240

A fast-response, highly sensitive and selective fluorescent probe for the ratiometric imaging of nitroxyl in living cells.  

Science.gov (United States)

A fast-response, highly sensitive and selective fluorescent probe with the 2-(diphenylphosphino)benzoate moiety as a recognition receptor for the ratiometric imaging of nitroxyl in living cells was first developed. PMID:24770879

Liu, Caiyun; Wu, Huifang; Wang, Zuokai; Shao, Changxiang; Zhu, Baocun; Zhang, Xiaoling

2014-06-01

 
 
 
 
241

Fast time-reversible algorithms for molecular dynamics of rigid-body systems.  

Science.gov (United States)

In this paper, we present time-reversible simulation algorithms for rigid bodies in the quaternion representation. By advancing a time-reversible algorithm [Y. Kajima, M. Hiyama, S. Ogata, and T. Tamura, J. Phys. Soc. Jpn. 80, 114002 (2011)] that requires iterations in calculating the angular velocity at each time step, we propose two kinds of iteration-free fast time-reversible algorithms. They are easily implemented in codes. The codes are compared with that of existing algorithms through demonstrative simulation of a nanometer-sized water droplet to find their stability of the total energy and computation speeds. PMID:22779579

Kajima, Yasuhiro; Hiyama, Miyabi; Ogata, Shuji; Kobayashi, Ryo; Tamura, Tomoyuki

2012-06-21

242

The synthetic scattering function and application to the design of cold moderators for pulsed neutron sources: a fast response methane based array  

Energy Technology Data Exchange (ETDEWEB)

The Synthetic Scattering Function (SSF) allows a simple description of the incoherent interaction of slow neutrons with hydrogenous materials. The main advantages of this model reside in the analytical expressions that it produces for double-differential cross sections, energy-transfer kernels, and total cross sections, which in turn permit the fast evaluation of neutron scattering and transport properties. In this work we briefly discuss basic features of the SSF, review some previous applications to a number of moderating materials, and present new Monte Carlo results for a fast time-response moderator concept based on methane at low temperatures. (auth)

Granada, J. R.; Mayer, R. E.; Gillette, V. H.

1997-09-01

243

High-purity CsI scintillators for fast timing applications  

International Nuclear Information System (INIS)

The basic requirements in fast coincidence measurements are good time resolution, high efficiency, and the highest possible count rate. The two latter requirements can be expressed by the statistical utility rate. These properties of BaF2 and pure CsI scintillators were compared from the viewpoint of positron lifetime spectroscopy. Time resolution, peak-to background ratio (ratio of the true and random coincidences) and statistical utility rate values were determined for fast coincidence systems with BaF2-BaF2 and BaF2-pure CsI scintillators. Although the time resolution was found to be worse, the peak to background ratio and the statistical utility rate were better for BaF2 -pure CsI scintillators thus indicating that pure CsI is competitive with BaF2

244

Electron irradiation for adjusting the reverse recovery time and forward voltage drop characteristics of fast diodes  

Science.gov (United States)

The electron linear accelerator ALIN-10 has been used to irradiate at room temperature and high temperature silicon diodes type BA159, BAX157 and 6DRR1 (manufacturer - Baneasa S.A.-factory 2300, Romania). The influence of 10 MeV electron irradiation upon the main electrical characteristics (reverse recovery time, forward voltage, reverse current) has been examined for different absorbed doses (10-50 kGy) and different irradiation temperatures (25°C, 175°C, 250°C). The dependence of the minority carrier lifetime, reverse recovery time and forward voltage on the radiation dose, and the percentage distribution (%) of the reverse recovery time and of the reverse current for the irradiated diodes are presented. A comparison between the electrical performances of the fast diodes obtained by electron irradiation and the electrical performances of the fast diodes obtained by gold or platinum diffusion has been made.

Iliescu, Elena; Niculescu, Anastase; Banu, Viorel; Nichita, Anca; Sturzu, Nicoleta

1998-04-01

245

Electron irradiation for adjusting the reverse recovery time and forward voltage drop characteristics of fast diodes  

Energy Technology Data Exchange (ETDEWEB)

The electron linear accelerator ALIN-10 has been used to irradiate at room temperature and high temperature silicon diodes type BA159, BAX157 and 6DRRI (manufacturer - Baneasa S.A.-factory 2300, Romania). The influence of 10 MeV electron irradiation upon the main electrical characteristics (reverse recovery time, forward voltage, reverse current) has been examined for different absorbed doses (10-50 kGy) and different irradiation temperatures (25 C, 175 C, 250 C). The dependence of the minority carrier lifetime, reverse recovery time and forward voltage on the radiation dose, and the percentage distribution (%) of the reverse recovery time and of the reverse current for the irradiated diodes are presented. A comparison between the electrical performances of the fast diodes obtained by electron irradiation and the electrical performances of the fast diodes obtained by gold or platinum diffusion has been made. (orig.) 4 refs.

Iliescu, E.; Niculescu, A. [Inst. for Atomic Phys., Bucharest (Romania). Electron Accel. Lab.; Banu, V.; Nichita, A.; Sturzu, N. [Baneasa S.A., Factory 2300, Str. Erou Iancu Nicolae 32, Bucharest (Romania)

1998-04-01

246

Toward a selective, sensitive, fast-responsive, and biocompatible two-photon probe for hydrogen sulfide in live cells.  

Science.gov (United States)

Hydrogen sulfide has emerged as an exciting endogenous gasotransmitter in addition to nitric oxide and carbon dioxide. Noninvasive detection methods for hydrogen sulfide thus become indispensable tools for studying its diverse roles in biological systems. Accordingly, fluorescent probes for hydrogen sulfide have received great attention in recent years. A practically useful fluorescent probe for bioimaging of hydrogen sulfide should be selective, sensitive, fast-responsive, biocompatible, observable in the biological optical window, and capable of deep-tissue imaging. These sensing properties, however, are extremely difficult to achieve at the same time. Disclosed here is the two-photon fluorescent probe that meets all of these criteria. The probe belongs to a Michael acceptor system, which raised a serious selectivity issue over the competing biothiols such as cysteine and glutathione. We have addressed the selectivity issue by optimizing the electronic and steric interactions between biothiols and the probe, in addition to achieving very high sensitivity, fast-response, and biocompatibility. Also, the sensing mechanism suggested in the literature was revised. The probe thus enables us to image the endogenously produced hydrogen sulfide with negligible interference from other biothiols in live cells. The excellent sensing properties of the probe combined with its capability of bioimaging thus make it a practically useful tool for further studying biological roles of hydrogen sulfide. PMID:25495776

Singha, Subhankar; Kim, Dokyoung; Moon, Hyunsoo; Wang, Taejun; Kim, Ki Hean; Shin, Youn Ho; Jung, Junyang; Seo, Eunseok; Lee, Sang-Joon; Ahn, Kyo Han

2015-01-20

247

Response times of operators in a control room  

International Nuclear Information System (INIS)

A statistical analysis was made of operator response times recorded in the control room of a research reactor during the years 1972-1974. A homogeneity test revealed that the data consist of a mixture of populations. A small but statistically significant difference is found between day and night response times. Lognormal distributions are found to provide the best fit of the day and the night response times. (author)

248

Modeling response times with latent variables: Principles and applications  

Directory of Open Access Journals (Sweden)

Full Text Available The introduction of the computer in psychological and educational testing has enabled us to record response times on test items in real time, without any interruption of the response process. This article reviews key principles for probabilistic modeling of these response times and discusses a hierarchical model that follows from the principles. It then shows the potential of the model for improving the current practices of item calibration, adaptive testing, controlling test speededness, and detection of cheating.

2011-09-01

249

Rapid response and wide range neutronic power measuring systems for fast pulsed reactors  

International Nuclear Information System (INIS)

This paper summarizes our investigation on design principles of the rapid, stable and wide range neutronic power measuring system for fast pulsed reactors. The picoammeter, the logarithmic amplifier, the reactivity meter and the neutron current chamber are the items of investigation. In order to get a rapid response, the method of compensation for the stray capacitance of the feedback circuits and the capacitance of signal cables is applied to the picoammeter, the logarithmic amplifier and the reactivity meter with consideration for the stability margin of a whole detecting system. The response of an ionization current chamber and the method for compensating the ion component of the chamber output to get optimum responses high pass filters are investigated. Statistical fluctuations of the current chamber output are also considered in those works. The optimum thickness of the surrounding moderator of the neutron detector is also discussed from the viewpoint of the pulse shape deformation and the neutron sensitivity increase. The experimental results are reported, which were observed in the pulse operations of the one shot fast pulsed reactor ''YAYOI'' and the one shot TRIGA ''NSRR'' with the measuring systems using those principles. (auth.)

250

Dispersion of Response Times Reveals Cognitive Dynamics  

Science.gov (United States)

Trial-to-trial variation in word-pronunciation times exhibits 1/f scaling. One explanation is that human performances are consequent on multiplicative interactions among interdependent processes-interaction dominant dynamics. This article describes simulated distributions of pronunciation times in a further test for multiplicative interactions and…

Holden, John G.; Van Orden, Guy C.; Turvey, Michael T.

2009-01-01

251

Fasting and sampling time affect liver gene expression of high-fat diet-fed mice.  

Science.gov (United States)

Several physiological and biological variables are known to affect peroxisome proliferator-activated receptor (PPAR)-?-dependent signaling pathway and plasma biochemical profiles. However, less is known about the effect of these variables on high-fat diet-fed mice. In a 5-week study, C57BL/6 mice were divided into control (C) and high-fat diet-fed (H) groups, whereby before dissection, each group was subdivided into non-fasted (nC and nH) and a 15-h fasted mice (fC and fH) killed in the early light cycle, and a 15-h fasted mice (eC and eH) killed in the late phase of the light cycle. Liver and blood from the vena cava were collected. Non-fasted nC and nH mice have a marginal difference in their body weight gain, whereas significant differences were found for fasted mice. In nH mice, PPAR-?, acyl-CoA oxidase and insulin-like growth factor-binding protein expressions were significantly elevated, in contrast to fatty acid synthase (Fasn), stearoyl CoA-desaturase (SCD)-1, and elongase (ELOVL)-6 expressions. Fasn was profoundly induced in fH mice, while decreased sterol regulatory-binding protein-1 and SCD-1 were found only in eH mice. Different from the gene expression profiles, plasma total cholesterol level of the eH mice was higher than controls, whereas nH mice have increased plasma non-esterified fatty acids. Only glucose level of the fH mice was higher than that observed for controls. Results showed that fasting and sampling time have significantly affected liver gene expression and plasma biochemical indices of the high-fat diet-treated mice. An overlook in these aspects can cause serious discrepancies in the experimental data and their interpretations. PMID:22444123

Lee, C Y

2010-05-01

252

In-situ response time testing of force-balance pressure transmitters in nuclear power plants  

International Nuclear Information System (INIS)

This paper reports on recommendations for response time testing of safety system pressure transmitters in nuclear power plants that are found in Regulatory Guide 1.118 and requirements are defined in plant technical specifications. The conventional testing method involves simultaneously applying a pressure ramp signal to the process transmitter and to a fast-response reference transmitter. The time delay between the response of the two transmitters, when they obtain a predetermined value, is called the process transmitter response time. This method is referred to as the ramp test. Although the ramp test is an accepted method, large variations in its results are sometimes encountered because of empirical difficulties associated with the test. This test requires access to each transmitter, and it must be performed inside the containment during shutdown. The in-situ test is accomplished by interrupting the power to the transmitter for a few seconds. It is referred to as the Power Interrupt (PI) test, and it can be conducted while the plant is operating. The test includes the entire electromechanical system and the response time is obtained by analyzing the transient response following the restoration of power to the transmitter. Response times obtained from the PI test and the ramp test are in good agreement and usually differ by less than 50 ms

253

Response of multiferroic composites inferred from a fast-Fourier-transform-based numerical scheme  

International Nuclear Information System (INIS)

The effective response and the local fields within periodic magneto-electric multiferroic composites are investigated by means of a numerical scheme based on fast Fourier transforms. This computational framework relies on the iterative resolution of coupled series expansions for the magnetic, electric and strain fields. By using an augmented Lagrangian formulation, a simple and robust procedure which makes use of the uncoupled Green operators for the elastic, electrostatics and magnetostatics problems is proposed. Its accuracy is assessed in the cases of laminated and fibrous two-phase composites for which analytical solutions exist

254

Comparison of aerosol and momentum mixing in dust storms using fast-response instruments  

International Nuclear Information System (INIS)

Fast-response light scattering measurements at two heights during a Texas dust storm are combined with horizontal and vertical wind data to derive and compare aerosol flux estimates using three techniques. The major result of this study is that a relative equivalence exists between the fine-particle (0.1?m< radius<1?m) exchange coefficient and the eddy viscosity of the wind. The data also shed some light on the complex dependence of wind speed threshold for suspension and aerosol flux in high winds for different surface conditions and soil types. These results show the value of the experimental technique to studies of toxic particulat suspension and deposition by wind

255

Joint Carrier Frequency Offset and Fast Time-varying Channel Estimation for MIMO-OFDM Systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, a novel pilot-aided algorithm is developed for MIMO-OFDM systems operating in fast time-varying environment. The algorithm has been designed to work both with parametric L-path channel model (with known path delays) and equivalent discrete-time channel model to jointly estimate the multi-path Rayleigh channel complex amplitudes (CA) and Carrier Frequency Offset (CFO). Each CA time-variation within one OFDM symbol is approximated by a Basis Expansion Model (BEM) representation. ...

Simon, Eric; Ros, Laurent; Hijazi, Hussein; Fang, Jin; Gaillot, Davy Paul; Berbineau, Marion

2011-01-01

256

Thermally actuated tunable liquid microlens with sub-second response time  

Science.gov (United States)

This letter reports a thermally actuated liquid microlens. In this design, a thermoelectric device was brought into direct contact with water to alter the water temperature and drive the lens through the thermal expansion of water. The shape of a pinned water meniscus at an aperture was deformed in response to the net volume change in the water, creating a tunable lens with a fast thermal response time of 0.8 s. Focal length of the microlens varied continuously from -82 mm to -29 mm as the temperature was increased from 20 °C to 30 °C.

Ashtiani, Alireza Ousati; Jiang, Hongrui

2013-09-01

257

A fast readout algorithm for Cluster Counting/Timing drift chambers on a FPGA board  

International Nuclear Information System (INIS)

A fast readout algorithm for Cluster Counting and Timing purposes has been implemented and tested on a Virtex 6 core FPGA board. The algorithm analyses and stores data coming from a Helium based drift tube instrumented by 1 GSPS fADC and represents the outcome of balancing between cluster identification efficiency and high speed performance. The algorithm can be implemented in electronics boards serving multiple fADC channels as an online preprocessing stage for drift chamber signals

258

A fast readout algorithm for Cluster Counting/Timing drift chambers on a FPGA board  

Science.gov (United States)

A fast readout algorithm for Cluster Counting and Timing purposes has been implemented and tested on a Virtex 6 core FPGA board. The algorithm analyses and stores data coming from a Helium based drift tube instrumented by 1 GSPS fADC and represents the outcome of balancing between cluster identification efficiency and high speed performance. The algorithm can be implemented in electronics boards serving multiple fADC channels as an online preprocessing stage for drift chamber signals.

Cappelli, L.; Creti, P.; Grancagnolo, F.; Pepino, A.; Tassielli, G.

2013-08-01

259

Fast input-free observers for LPV discrete-time systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper deals with fast input-free partial state estimation for discrete-time LPV systems through functional observers. The system inputs are assumed to be unknown and then the observers reduce to functions of finite sequences of the output only. The existence of the observer is proved by resorting to both the notion of inverse system and the concept of maximal A-invariant subspaces. A constructive approach to derive the explicit equations of the observer is provided. An example illustrate...

Fiacchini, Mirko; Mille?rioux, Gilles

2012-01-01

260

Development of a fast time-to-digital converter (TDC) using a programmable gate array  

International Nuclear Information System (INIS)

A fast time-to-digital converter with a 5 ns step was designed and tested by utilizing a user-programmable gate array. The stabilities against temperature and supply voltage variation were measured. A module was built with this TDC, and was successfully used in the first-level trigger system of the ZEUS detector to reject proton-beam induced background events. (author)

 
 
 
 
261

Time dependent solutions of the Fokker-Planck equation for fast fusion ions  

International Nuclear Information System (INIS)

Approximate time dependent solutions for the Fokker-Planck equation for fast fusion ions from an isotropic, monoenergetic source are presented, for the problem of D - T - He3 reactions. The equations include the effect of diffusion, which is particularly noticeable in the distribution of particles of lower energy and in the formation of a tail of particles with energy higher than that of the source. (Author)

262

Web Service Response Time Monitoring: Architecture and Validation  

Directory of Open Access Journals (Sweden)

Full Text Available Web services are used in many Web applications in order to save time and cost during software development process. To peruse Web service response time, a suitable tool is needed to automate the measurement of the response time. However, not many suitable tools are available for automatic measurement of response time. This research is carried out in the context of quality of Web services in order to measure and visualize Web service response time. The method proposed in this research for accomplishing this goal is based on creating a proxy for connecting to the required Web service, and then calculating the Web services response time via the proxy. A software tool is designed based on the proposed method in order to guide the implementation that is still in progress. The tool can be validated through empirical validation using three test cases for three different Web service access situations.

Sara Abbaspour Asadollah

2012-09-01

263

Time-Dependent Networks as Models to Achieve Fast Exact Time-Table Queries  

DEFF Research Database (Denmark)

We consider efficient algorithms for exact time-table queries, i.e. algorithms that find optimal itineraries for travelers using a train system. We propose to use time-dependent networks as a model and show advantages of this approach over space-time networks as models.

Brodal, Gert StØlting; Jacob, Rico

2003-01-01

264

Dynamic Response of a fast near infra-red Mueller matrix ellipsometer  

CERN Document Server

The dynamic response of a near infrared Ferroelectric Liquid Crystal based Mueller matrix ellipsometer (NIR FLC-MME) is presented. A time dependent simulation model, using the measured time response of the individual FLCs, is used to describe the measured temporal response. Furthermore, the impulse response of the detector and the pre-amplifier is characterized and included in the simulation model. The measured time-dependent intensity response of the MME is reproduced in simulations, and it is concluded that the switching time of the FLCs is the limiting factor for the Mueller matrix measurement time of the FLC-based MME. Based on measurements and simulations our FLC based NIR-MME system is estimated to operate at the maximum speed of approximately 16 ms per Mueller matrix measurement. The FLC-MME may be operated several times faster, since the switching time of the crystals depends on the individual crystal being switched, and to what state it is switched. As a demonstration, the measured temporal response ...

Aas, Lars Martin Sandvik; Kildemo, Morten; Lindgren, Mikael

2010-01-01

265

Observations of plasma response to RMP using fast movable magnetic probe on TEXTOR  

Energy Technology Data Exchange (ETDEWEB)

Plasma response to resonant magnetic perturbation fields (RMPs) is important for understanding the physical mechanism of instability control using RMP fields in the next generation of fusion devices, i.e. ITER. Such an investigation has been carried out in TEXTOR under different dynamic ergodic divertor (DED) configurations. The perturbed magnetic field is measured by the Fast Movable Magnetic Probe (FMMP) installed at the outer equatorial plane (low-field side). Preliminary results show that the perturbed plasma edge magnetic topology is different from the case simulated with a vacuum assumption. Plasma response to RMP depends strongly on both the location of the resonant rational flux surface and the frequency difference between the drift of the rational surface in the plasma and the external perturbation.

Yang, Yao; Liang, Yunfeng; Sun, Youwen; Zhang, Tao; Assmann, Jochen; Bertschinger, Guenter; Jaegers, Hubert; Koslowski, Hans Rudolf; Pearson, Jonathan; Schweer, Bernd; Wiegmann, Christopher; Xu, Yuhong [Institute of Energy and Climate Research/Plasma Physics, Forschungszentrum Juelich GmbH, Association EURATOM-FZJ, Juelich (Germany)

2011-07-01

266

Observations of plasma response to RMP using fast movable magnetic probe on TEXTOR  

International Nuclear Information System (INIS)

Plasma response to resonant magnetic perturbation fields (RMPs) is important for understanding the physical mechanism of instability control using RMP fields in the next generation of fusion devices, i.e. ITER. Such an investigation has been carried out in TEXTOR under different dynamic ergodic divertor (DED) configurations. The perturbed magnetic field is measured by the Fast Movable Magnetic Probe (FMMP) installed at the outer equatorial plane (low-field side). Preliminary results show that the perturbed plasma edge magnetic topology is different from the case simulated with a vacuum assumption. Plasma response to RMP depends strongly on both the location of the resonant rational flux surface and the frequency difference between the drift of the rational surface in the plasma and the external perturbation.

267

Influence of Time-Dependent Coupling Coefficients and Delay Times on the Kinetics of a Modular Fast Reactor Core  

International Nuclear Information System (INIS)

Previous treatments of kinetics problems in modular and toroidal cores in fast breeder reactors have been based on Avery's coupled kinetics equations for partial integral fission sources. Most of these calculations do not take account of the time dependence of the reactivity coupling coefficients caused by possible flux tilting in an excursion. Furthermore, the effect of time delays for neutrons travelling between the modules, which is expected to be small, is not included in the model itself. The present investigation of the behaviour of two coupled modules is based on our recent derivation of coupled reactor kinetics equations from the Boltzmann equation. The distribution functions of delay times for neutrons are approximated by delta functions. It is shown that in three-group theory an analytical expression for the average delay time between two modules can still be derived. The calculation is based on the three-group leakage fluxes. Cross-sections are condensed from a 26-group set. Step changes in fission cross-sections are considered as perturbations. Coupling coefficients are calculated using the critical flux distribution and, to show the effect of time dependence, using the asymptotic flux distribution. Finally, a numerical method for solving coupled reactor kinetics equations is outlined. Comparing solutions of simple kinetics problems without feed-back but with time-dependent coupling coefficients and delay times to solutions without consideration of these tsolutions without consideration of these two effects, it is found that the influence of neutron delay times is indeed negligible for the usual transients considered in the safety analysis of fast breeder reactors. However, the inclusion of time-dependent coupling coefficients can markedly alter the module power during an excursion. (author)

268

Fast neutron response of 6Li-depleted CLYC detectors up to 20 MeV  

Science.gov (United States)

The response of 6Li-depleted Cs2LiYCl6 (CLYC) to high-energy neutrons has been investigated using a pair of 1 in.×1 in. crystals. These are the first two detectors of their kind, which will comprise a 16-element array for studies in fast neutron spectroscopy. Their thermal neutron response has been compared with standard CLYC crystals with a 6Li enrichment of 95%, demonstrating excellent suppression of the overwhelming thermal neutron background. The response to mono-energetic neutrons over a range of 0.5 to 20 MeV was tested. From this, the response function, energy resolution, and pulse-shape discrimination up to 20 MeV were characterized. Detailed Monte Carlo investigations with MCNPX have been used to show that the dominant reaction mechanisms contributing to the observed response are 35Cl(n,p) and 35Cl(n,?). Preliminary investigations have also demonstrated the possibility for separating events from these two reactions.

D'Olympia, N.; Chowdhury, P.; Jackson, E. G.; Lister, C. J.

2014-11-01

269

Organic scintillators response function modeling for Monte Carlo simulation of Time-of-Flight measurements.  

Science.gov (United States)

In neutron Time-of-Flight (TOF) measurements performed with fast organic scintillation detectors, both pulse arrival time and amplitude are relevant. Monte Carlo simulation can be used to calculate the time-energy dependant neutron flux at the detector position. To convert the flux into a pulse height spectrum, one must calculate the detector response function for mono-energetic neutrons. MCNP can be used to design TOF systems, but standard MCNP versions cannot reliably calculate the energy deposited by fast neutrons in the detector since multiple scattering effects must be taken into account in an analog way, the individual recoil particles energy deposit being summed with the appropriate scintillation efficiency. In this paper, the energy response function of 2?×2? and 5?×5? liquid scintillation BC-501 A (Bicron) detectors to fast neutrons ranging from 20 keV to 5.0 MeV is computed with GEANT4 to be coupled with MCNPX through the "MCNP Output Data Analysis" software developed under ROOT (Carasco, 2010). PMID:22100378

Carasco, C

2012-07-01

270

Psychometric and Information Processing Properties of Selected Response Time Models.  

Science.gov (United States)

The compatibility of some response time models with psychometric and information processing approaches to response times is explored. Current psychometric models satisfy independence of comparisons in some formal senses but are not easily compatible with the serial-additive information processing type of model. (SLD)

Van Breukelen, Gerard J. P.

1995-01-01

271

A 3 A sink/source current fast transient response low-dropout Gm driven linear regulator  

International Nuclear Information System (INIS)

A 3 A sink/source Gm-driven CMOS low-dropout regulator (LDO), specially designed for low input voltage and low cost, is presented by utilizing the structure of a current mirror Gm (transconductance) driving technique, which provides high stability as well as a fast load transient response. The proposed LDO was fabricated by a 0.5 ?m standard CMOS process, and the die size is as small as 1.0 mm2. The proposed LDO dissipates 220 ?A of quiescent current in no-load conditions and is able to deliver up to 3 A of load current. The measured results show that the output voltage can be resumed within 2 ?s with a less than 1 mV overshoot and undershoot in the output current step from -1.8 to 1.8 A with a 0.1 ?s rising and falling time at three 10 ?F ceramic capacitors. (semiconductor integrated circuits)

272

Time-resolved spectroscopy using a chopper wheel as a fast shutter  

Science.gov (United States)

Widely available, small form-factor, fiber-coupled spectrometers typically have a minimum exposure time measured in milliseconds, and thus cannot be used directly for time-resolved measurements at the microsecond level. Spectroscopy at these faster time scales is typically done with an intensified charge coupled device (CCD) system where the image intensifier acts as a "fast" electronic shutter for the slower CCD array. In this paper, we describe simple modifications to a commercially available chopper wheel system to allow it to be used as a "fast" mechanical shutter for gating a fiber-coupled spectrometer to achieve microsecond-scale time-resolved optical measurements of a periodically pulsed light source. With the chopper wheel synchronized to the pulsing of the light source, the time resolution can be set to a small fraction of the pulse period by using a chopper wheel with narrow slots separated by wide spokes. Different methods of synchronizing the chopper wheel and pulsing of the light sources are explored. The capability of the chopper wheel system is illustrated with time-resolved measurements of pulsed plasmas.

Wang, Shicong; Wendt, Amy E.; Boffard, John B.; Lin, Chun C.

2015-01-01

273

Efficient allocation of heterogeneous response times in information spreading process  

Science.gov (United States)

Recently, the impacts of spatiotemporal heterogeneities of human activities on spreading dynamics have attracted extensive attention. In this paper, we intend to understand how the heterogeneous distribution of response times at the individual level influences information spreading. Based on the uncorrelated scale-free networks without degree-degree correlation, we study the susceptible-infected spreading dynamics with adjustable power-law response time distribution, and find that the stronger the heterogeneity of response times is, the faster the information spreading is in the early and middle stages. Following a given heterogeneity, the procedure of reducing the correlation between the response times and degrees of individuals can also accelerate the spreading dynamics in the early and middle stages. However, the dynamics in the late stage is slightly more complicated, and there is an optimal value of the full prevalence time (i.e., the time for full infection on a network) changing with the heterogeneity of response times and the response time-degree correlation, respectively. The optimal phenomena result from the efficient allocation of heterogeneous response times.

Cui, Ai-Xiang; Wang, Wei; Tang, Ming; Fu, Yan; Liang, Xiaoming; Do, Younghae

2014-09-01

274

Changes in energy metabolism in response to 48 h of overfeeding and fasting in Caucasians and Pima Indians  

DEFF Research Database (Denmark)

Differences in the metabolic response to overfeeding and starvation may confer susceptibility or resistance to obesity in humans. To further examine this hypothesis, we assessed the changes in 24 h energy metabolism in response to short-term overfeeding and fasting in Caucasians (C) and Pima Indians (I), a population with a very high propensity for obesity.

Weyer, C; Vozarova, B

2001-01-01

275

Organic scintillators response function modeling for Monte Carlo simulation of Time-of-Flight measurements  

Energy Technology Data Exchange (ETDEWEB)

In neutron Time-of-Flight (TOF) measurements performed with fast organic scintillation detectors, both pulse arrival time and amplitude are relevant. Monte Carlo simulation can be used to calculate the time-energy dependant neutron flux at the detector position. To convert the flux into a pulse height spectrum, one must calculate the detector response function for mono-energetic neutrons. MCNP can be used to design TOF systems, but standard MCNP versions cannot reliably calculate the energy deposited by fast neutrons in the detector since multiple scattering effects must be taken into account in an analog way, the individual recoil particles energy deposit being summed with the appropriate scintillation efficiency. In this paper, the energy response function of 2 Double-Prime Multiplication-Sign 2 Double-Prime and 5 Double-Prime Multiplication-Sign 5 Double-Prime liquid scintillation BC-501 A (Bicron) detectors to fast neutrons ranging from 20 keV to 5.0 MeV is computed with GEANT4 to be coupled with MCNPX through the 'MCNP Output Data Analysis' software developed under ROOT (). - Highlights: Black-Right-Pointing-Pointer GEANT4 has been used to model organic scintillators response to neutrons up to 5 MeV. Black-Right-Pointing-Pointer The response of 2 Double-Prime Multiplication-Sign 2 Double-Prime and 5 Double-Prime Multiplication-Sign 5 Double-Prime BC501A detectors has been parameterized with simple functions. Black-Right-Pointing-Pointer Parameterization will allow the modeling of neutron Time of Flight measurements with MCNP using tools based on CERN's ROOT.

Carasco, C., E-mail: cedric.carasco@cea.fr [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 Saint-Paul-lez-Durance (France)

2012-07-15

276

Application of Time Projection Chambers with GEMs and Pixels to WIMP Searches and Fast Neutron Detection  

Science.gov (United States)

We present work on the detection of neutral particles via nuclear recoils in gas-?lled Time Projection Chambers (TPCs). We employ Gas Electron Multipliers (GEMs) to amplify the signal and silicon pixel electronics to detect the avalanche charge. These technologies allow ionization in the target gas to be detected with low noise, improved position and time resolution, and high efficiency. We review experimental results obtained in previous years, and report on ongoing simulation studies and construction of the ?rst prototype at the University of Hawaii. We also present prospects of using such detectors to perform direction-sensitive searches for WIMP dark matter and fast neutron from ?ssionable material.

Yamaoka, J.; Feng, H.; Garcia-Sciveres, M.; Jaegle, I.; Kadyk, J.; Nguyen, Y.; Rosen, M.; Ross, S.; Thorpe, T.; Vahsen, S.

277

Time Series Technical Analysis via new Fast Estimation Methods: A Preliminary Study in Mathematical Finance  

CERN Document Server

New fast estimation methods stemming from control theory lead to a fresh look at time series, which bears some resemblance to "technical analysis". The results are applied to a typical object of financial engineering, namely the forecast of foreign exchange rates, via a "model-free" setting, i.e., via repeated identifications of low order linear difference equations on sliding short time windows. Several convincing computer simulations, including the prediction of the position and of the volatility with respect to the forecasted trendline, are provided. $\\mathcal{Z}$-transform and differential algebra are the main mathematical tools.

Fliess, Michel

2008-01-01

278

Application of Time Projection Chambers with GEMs and Pixels to WIMP Searches and Fast Neutron Detection  

CERN Document Server

We present work on the detection of neutral particles via nuclear recoils in gas-filled Time Projection Chambers (TPCs). We employ Gas Electron Multipliers (GEMs) to amplify the signal and silicon pixel electronics to detect the avalanche charge. These technologies allow ionization in the target gas to be detected with low noise, improved position and time resolution, and high efficiency. We review experimental results obtained in previous years, and report on ongoing simulation studies and construction of the first prototype at the University of Hawaii. We also present prospects of using such detectors to perform direction-sensitive searches for WIMP dark matter and fast neutron from fissionable material.

Yamaoka, Jared; Garcia-Sciveres, Maurice; Jaegle, Igal; Kadyk, John; Nguyen, Young; Rosen, Marc; Ross, Steven; Thorpe, Thomas; Vahsen, Sven

2012-01-01

279

INFLUENCE OF RAMADAN FASTING ON ANAEROBIC PERFORMANCE AND RECOVERY FOLLOWING SHORT TIME HIGH INTENSITY EXERCISE  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this study was to investigate the effects of Ramadan fasting on anaerobic power and capacity and the removal rate of lactate after short time high intensity exercise in power athletes. Ten male elite power athletes (2 wrestlers, 7 sprinters and 1 thrower, aged 20-24 yr, mean age 22.30 ± 1.25 yr) participated in this study. The subjects were tested three times [3 days before the beginning of Ramadan (Pre-RF), the last 3 days of Ramadan (End-RF) and the last 3 days of the 4th week a...

Umid Karli; Alpay Guvenc; Alper Aslan; Tahir Hazir; Caner Acikada

2007-01-01

280

A Fast Pulsed Neutron Source for Time-of-Flight Detection of Nuclear Materials and Explosives  

International Nuclear Information System (INIS)

AASC has built a fast pulsed neutron source based on the Dense Plasma Focus (DPF). The more current version stores only 100 J but fires at ?10-50 Hz and emits ?106n/pulse at a peak current of 100 kA. Both sources emit 2.45±0.1 MeV(DD) neutron pulses of ?25-40 ns width. Such fast, quasi-monoenergetic pulses allow time-of-flight detection of characteristic emissions from nuclear materials or high explosives. A test is described in which iron targets were placed at different distances from the point neutron source. Detectors such as Stilbene and LaBr3 were used to capture inelastically induced, 847 keV gammas from the iron target. Shielding of the source and detectors eliminated most (but not all) of the source neutrons from the detectors. Gated detection, pulse shape analysis and time-of-flight discrimination enable separation of gamma and neutron signatures and localization of the target. A Monte Carlo simulation allows evaluation of the potential of such a fast pulsed source for a field-portable detection system. The high rep-rate source occupies two 200 liter drums and uses a cooled DPF Head that is 3 in volume.

 
 
 
 
281

Design and evaluation of a device for fast multispectral time-resolved fluorescence spectroscopy and imaging  

Science.gov (United States)

The application of time-resolved fluorescence spectroscopy (TRFS) to in vivo tissue diagnosis requires a method for fast acquisition of fluorescence decay profiles in multiple spectral bands. This study focusses on development of a clinically compatible fiber-optic based multispectral TRFS (ms-TRFS) system together with validation of its accuracy and precision for fluorescence lifetime measurements. It also presents the expansion of this technique into an imaging spectroscopy method. A tandem array of dichroic beamsplitters and filters was used to record TRFS decay profiles at four distinct spectral bands where biological tissue typically presents fluorescence emission maxima, namely, 390, 452, 542, and 629 nm. Each emission channel was temporally separated by using transmission delays through 200 ?m diameter multimode optical fibers of 1, 10, 19, and 28 m lengths. A Laguerre-expansion deconvolution algorithm was used to compensate for modal dispersion inherent to large diameter optical fibers and the finite bandwidth of detectors and digitizers. The system was found to be highly efficient and fast requiring a few nano-Joule of laser pulse energy and fiber probe in a 2D plane to validate the system as an imaging tool. The lifetime measurement variability was measured indicating that the system provides reproducible results with a standard deviation smaller than 50 ps. The ms-TRFS is a compact apparatus that makes possible the fast, accurate, and precise multispectral time-resolved fluorescence lifetime measurements of low quantum efficiency sub-nanosecond fluorophores.

Yankelevich, Diego R.; Ma, Dinglong; Liu, Jing; Sun, Yang; Sun, Yinghua; Bec, Julien; Elson, Daniel S.; Marcu, Laura

2014-03-01

282

A Fast Pulsed Neutron Source for Time-of-Flight Detection of Nuclear Materials and Explosives  

Energy Technology Data Exchange (ETDEWEB)

AASC has built a fast pulsed neutron source based on the Dense Plasma Focus (DPF). The more current version stores only 100 J but fires at {approx}10-50 Hz and emits {approx}10{sup 6}n/pulse at a peak current of 100 kA. Both sources emit 2.45{+-}0.1 MeV(DD) neutron pulses of {approx}25-40 ns width. Such fast, quasi-monoenergetic pulses allow time-of-flight detection of characteristic emissions from nuclear materials or high explosives. A test is described in which iron targets were placed at different distances from the point neutron source. Detectors such as Stilbene and LaBr3 were used to capture inelastically induced, 847 keV gammas from the iron target. Shielding of the source and detectors eliminated most (but not all) of the source neutrons from the detectors. Gated detection, pulse shape analysis and time-of-flight discrimination enable separation of gamma and neutron signatures and localization of the target. A Monte Carlo simulation allows evaluation of the potential of such a fast pulsed source for a field-portable detection system. The high rep-rate source occupies two 200 liter drums and uses a cooled DPF Head that is <500 cm{sup 3} in volume.

Krishnan, Mahadevan; Bures, Brian; James, Colt; Madden, Robert [Alameda Applied Sciences Corporation, 3077 Teagarden Street, San Leandro, CA 94577 (United States); Hennig, Wolfgang; Breus, Dimitry; Asztalos, Stephen; Sabourov, Konstantin [XIA LLC, 31057 Genstar Road, Hayward, CA 94544 (United States); Lane, Stephen [NSF Center for Biophotonics and School of Medicine, University of California Davis, Sacramento CA, 95817 (United States)

2011-12-13

283

Small-time asymptotics for fast mean-reverting stochastic volatility models  

CERN Document Server

In this paper, we study stochastic volatility models in regimes where the maturity is small but large compared to the mean-reversion time of the stochastic volatility factor. The problem falls in the class of averaging/homogenization problems for nonlinear HJB type equations where the "fast variable" lives in a non-compact space. We develop a general argument based on viscosity solutions which we apply to the two regimes studied in the paper. We derive a large deviation principle and we deduce asymptotic prices for Out-of-The-Money call and put options, and their corresponding implied volatilities. The results of this paper generalize the ones obtained in \\cite{FFF} (J. Feng, M. Forde and J.-P. Fouque, {\\it Short maturity asymptotic for a fast mean reverting Heston stochastic volatility model}, SIAM Journal on Financial Mathematics, Vol. 1, 2010) by a moment generating function computation in the particular case of the Heston model.

Feng, Jin; Kumar, Rohini

2010-01-01

284

Time-structure of thermal neutron leakage from fast and slow moderators for spallation neutron sources  

International Nuclear Information System (INIS)

The dwell-times of neutrons slowed down either in small polyethylene moderators or a large D2O volume have been measured. The fast neutrons have been produced by bombarding lead, lead-bismuth, depleted uranium and tungsten targets of slab or cylindrical shape with short pulses of 490 MeV protons. Lead and beryllium reflectors have been employed for the rectangular shaped grooved polyethylene moderators. The geometry-adapted (jagged) polyethylene moderators used with the cylindrical target have been measured only in D2O-reflected configuration. The essential result of the numerical analysis of about 40 target-moderator-reflector configurations tested is that for the fast (light hydrogen) moderators the most intense flux component decays in 100 ?s or less

285

INFLUENCE OF RAMADAN FASTING ON ANAEROBIC PERFORMANCE AND RECOVERY FOLLOWING SHORT TIME HIGH INTENSITY EXERCISE  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study was to investigate the effects of Ramadan fasting on anaerobic power and capacity and the removal rate of lactate after short time high intensity exercise in power athletes. Ten male elite power athletes (2 wrestlers, 7 sprinters and 1 thrower, aged 20-24 yr, mean age 22.30 ± 1.25 yr participated in this study. The subjects were tested three times [3 days before the beginning of Ramadan (Pre-RF, the last 3 days of Ramadan (End-RF and the last 3 days of the 4th week after the end of Ramadan (After-RF]. Anaerobic power and capacity were measured by using the Wingate Anaerobic Test (WAnT at Pre-RF, End-RF and After- RF. Capillary blood samples for lactate analyses and heart rate recordings were taken at rest, immediately after WAnT and throughout the recovery period. Repeated measures of ANOVA indicated that there were no significant changes in body weight, body mass index, fat free mass, percentage of body fat, daily sleeping time and daily caloric intake associated with Ramadan fasting. No significant changes were found in total body water either, but urinary density measured at End-RF was significantly higher than After-RF. Similarity among peak HR and peak LA values at Pre-RF, End- RF and After-RF demonstrated that cardiovascular and metabolic stress caused by WAnT was not affected by Ramadan fasting. In addition, no influence of Ramadan fasting on anaerobic power and capacity and removal rate of LA from blood following high intensity exercise was observed. The results of this study revealed that if strength-power training is performed regularly and daily food intake, body fluid balance and daily sleeping time are maintained as before Ramadan, Ramadan fasting will not have adverse effects on body composition, anaerobic power and capacity, and LA metabolism during and after high intensity exercise in power athletes

Umid Karli

2007-12-01

286

Fast-response magnet coil system for controlling plasma equilibrium in a tokamak with a strong magnetic field  

International Nuclear Information System (INIS)

Two special fast-control coils are used to provide stability of a plasma filament in a horizontal plane of a tokamak with a strong magnetic field. According to the fast-response conditions satisfying the control system, power of the supply system for these coils is to constitute 35 MW (U=2.5 kV, I=14 kA). A basic circuit of the supply system with a capacitor is given, the circuit consists of a capacitor bank with a rectifier providing for a preliminary chage of a capacitor bank, thyristor switches, a shut-down system, circuit breakers, valve devices. A basic circuit of supply system for plasma equilibrium coil built on the base of fast-response and reliability priciples is presented. Fast voltage removal is provided by shorting out a c

287

Effects seen in fast-timing with a surface barrier time-of-flight telescope  

International Nuclear Information System (INIS)

It has been found that the timing resolution between two surface barrier detectors is degraded when they are separated to make a time-of-flight telescope. The degradation consists of a broadening of the peak with an asymmetric tail developing on the 'early' time side of the peak. Measurement has shown that these effects vary progressively with the radial distance from the centre of the back detector. Ions which arrive closer to the edge of the detector produce a time peak which is shifted to earlier time than those which arrive in the centre. A further measurement has shown that only small changes in the pulse shape occur for these different events. The suggestion is made that the observed effect is predominantly due to different delays in the pulses which have to propagate different distances across the detector. The propagation velocity in this case was measured to be 20% that of light. An approximate treatment for the detector in terms of a simple delay line is capable of giving a reasonable description of the observed effects. (Auth.)

288

Event synchronization a simple and fast method to measure synchronicity and time delay patterns  

CERN Document Server

We propose a simple method to measure synchronization and time delay patterns between signals. It is based on the relative timings of events in the time series, defined e.g. as local maxima. The degree of synchronization is obtained from the number of quasi-simultaneous appearances of events, and the delay is calculated from the precedence of events in one signal with respect to the other. Moreover, we can easily visualize the time evolution of the delay and synchronization level with an excellent resolution. We apply the algorithm to short rat EEG signals, some of them containing spikes. We also apply it to an intracranial human EEG recording containing an epileptic seizure, and we propose that the method might be useful for the detection of foci and for seizure prediction. It can be easily extended to other types of data and it is very simple and fast, thus being suitable for on-line implementations.

Quiroga, R Q; Grassberger, Peter

2002-01-01

289

Effect of training in the fasted state on metabolic responses during exercise with carbohydrate intake  

DEFF Research Database (Denmark)

Skeletal muscle gene response to exercise depends on nutritional status during and after exercise, but it is unknown whether muscle adaptations to endurance training are affected by nutritional status during training sessions. Therefore, this study investigated the effect of an endurance training program (6 wk, 3 day/wk, 1-2 h, 75% of peak Vo(2)) in moderately active males. They trained in the fasted (F; n = 10) or carbohydrate-fed state (CHO; n = 10) while receiving a standardized diet [65 percent of total energy intake (En) from carbohydrates, 20%En fat, 15%En protein]. Before and after the training period, substrate use during a 2-h exercise bout was determined. During these experimental sessions, all subjects were in a fed condition and received extra carbohydrates (1 g.kg body wt(-1) .h(-1)). Peak Vo(2) (+7%), succinate dehydrogenase activity, GLUT4, and hexokinase II content were similarly increased between F and CHO. Fatty acid binding protein (FABPm) content increased significantly in F (P = 0.007). Intramyocellular triglyceride content (IMCL) remained unchanged in both groups. After training, pre-exercise glycogen content was higher in CHO (545 +/- 19 mmol/kg dry wt; P = 0.02), but not in F (434 +/- 32 mmol/kg dry wt; P = 0.23). For a given initial glycogen content, F blunted exercise-induced glycogen breakdown when compared with CHO (P = 0.04). Neither IMCL breakdown (P = 0.23) nor fat oxidation rates during exercise were altered by training. Thus short-term training elicits similar adaptations in peak Vo(2) whether carried out in the fasted or carbohydrate-fed state. Although there was a decrease in exercise-induced glycogen breakdown and an increase in proteins involved in fat handling after fasting training, fat oxidation during exercise with carbohydrate intake was not changed.

De Bock, K; Derave, W

2008-01-01

290

Parallelized fast multipole BEM based on the convolution quadrature method for 3-D wave propagation problems in time-domain  

International Nuclear Information System (INIS)

This paper presents a new time-domain boundary element method (BEM) using a convolution quadrature method (CQM) and a fast multipole method (FMM) in 3-D scalar wave propagation. In general, the use of direct time-domain BEM sometimes causes the numerical instability of time-stepping solutions and needs much computational time and memory. To overcome these difficulties, in this paper, the convolution quadrature method developed by Lubich is applied to establish the stability behavior of the time-stepping scheme. Moreover, the fast multipole method and parallelization techniques are adapted to improve the computational efficiency for large size problems. The formulation and numerical implementation of the new boundary element method, and the basic formulas for the fast multipole method such as the multipole expansion, the local expansion, and the translation relations of them in the fast multipole algorithm are presented. The accuracy, the computational efficiency and the applicability are checked by solving 3-D large scale wave scattering problems.

291

Development of a LaBr3(Ce) Fast-timing Array for FAIR  

International Nuclear Information System (INIS)

A ?-ray spectrometer with fast-timing capabilities, constructed of LaBr3(Ce:5%) detectors, is under development for use at the future Facility for Anti-proton and Ion Research (FAIR). The physics aims of this device are to measure the half-lives of excited states in the region of ?50 ps to several ns, in exotic nuclei. Monte-Carlo simulations using the GEANT4 software package have determined the final design of this fast-timing array by calculating the full-energy peak efficiencies of several different detector geometries. The results of the simulated efficiencies for each configuration were used to calculate the timing precision. Consequently, an array of thirty six, section 3.8 x 5.1 cm cylindrical crystals was found to be the optimum configuration. The detectors were purchased and subsequently characterised, with each detector found to have intrinsic energy and timing resolutions of ? 2.8 % (FWHM) and ? 210 ps (FWHM) for the 1173 and 1332 keV decays from 60Co. (authors)

292

Ultra-Fast Timing and the Application of High Energy Physics Technologies to Biomedical Imaging  

Science.gov (United States)

We propose to apply the ultra fast Time Of Flight technique (TOF) developed for High Energy Physics (HEP) particle detectors to biomedical imaging. The similarity of the problem in the two fields as well as the remarkable opportunities in biomedical imaging to use technologies developed in HEP have the potential to make major advances in the medical world, in particular for Positron Emission Tomography (PET). We will describe and present some preliminary results of the development of a new complete read-out chain able to manage signals from various types of modern photo detectors (MCP, APD, SiPM). This innovative architecture is made of a fast front-end electronics ASIC with novel Digital Signal Processing (DSP) concepts able to reach the Pico-second timing resolution, a time-to-digital converter, a pipelined digital readout and an integrated trigger/filter with real-time data treatment and display. In parallel with the hardware development, we have begun a systematic program to simulate system characteristics from the initial particle interaction to the final digital data, including a bit-by-bit mapping of the front end/data acquisition system. The introduction of these techniques and tools, common in HEP, has the potential to make improvement to biomedical imaging systems.

Chen, Chin-Tu; Kao, Chien-Min; Xie, Quigguo; Frisch, Henry; Heinz, Mary; Sanders, Harold; Tang, Fukung; Anderson, John; Byrum, Karen; Drake, Gary; Heartly, Camden; Le Dû, Patrick; Royon, Christophe; Genat, Jean François; Va'Vra, Jerry

2008-06-01

293

Multilevel Spatial Multiplexing -Space Time Trellis Coded Modulation System for Fast Fading MIMO Channel  

Directory of Open Access Journals (Sweden)

Full Text Available Multilevel Space Time Trellis Coded Modulation with antenna grouping, which has been proposed recently, has coding gain and diversity gain, which in turn provide high throughput with considerable low computational complexity. However its performance is limited by predefining the antenna groups per component codes. In this paper Multilevel Spatial Multiplexing-Space Time Trellis Coded Modulation (ML-SM-STTCM has been proposed, in which antenna group selection is made based on spatial modulation based on trellis coding proposed by Ertugrul Basar and team. This idea maximizes the spatial diversity. Since only selected antennas are used to transmit the signal, and also the antennas with less cross correlation are in the selected groups, we could able to achieve improved BER performance even in the fast fading channel. Since the antenna selection is based on the component code in the system, at the decoder without increase in the computational complexity, we could achieve better error performance. The performance of the proposed system is analysed with Viterbi decoding algorithm and sub optimal sequential decoding algorithm. In this system, the antenna groups are non-overlapping, hence, it needs Nt, the number transmitter antennas, more than what is required at time t. The computer simulation reveals that the proposed system gives better BER performance compared to Multilevel Space Time Trellis Coded Modulation (ML STTCM over fast fading channel with the same computational complexity both at the transmitter and receiver.

K.Kavitha

2014-03-01

294

A fast-response production-inventory model for deteriorating seasonal products with learning in set-ups  

Directory of Open Access Journals (Sweden)

Full Text Available The classical production-inventory model assumes that both demand and set-up costs are constant. However, in real manufacturing environment, managers usually embark on continuous improvement programmes that often lead to more effective use of tools and machineries and consequently reduction in set-up costs. In fact, constant emphasis on reduction of set-up costs is usually cited as one of the factors responsible for the efficiency of Japanese manufacturing methods. On the other hand, the demand for seasonal product is often characterized by a mixture of time-dependent patterns over the entire season. This paper investigates the effect of learning-based reduction in set-up costs on the optimal schedules and costs of a production-inventory system for deteriorating seasonal products. The demand pattern is a general three-phase ramp-type demand function that represents the various phases of demand commonly observed in many seasonal products in the market. A two-parameter Weibull-distribution function is used for the deterioration of items in order to make the model more generalized and realistic. The study further presents two different multi-period production strategies that can ensure a fast-response to customers’ demand and compare them with the usual single period strategy. The Numerical example and sensitivity analysis shows that learning-based reduction in set-up costs leads to higher production frequency and shorter production runs which are vital aspects of the just-in-time (JIT philosophy.

Ibraheem Abdul

2011-10-01

295

Fast Time-Varying Volume Rendering Using Time-Space Partition (TSP) Tree  

Science.gov (United States)

We present a new, algorithm for rapid rendering of time-varying volumes. A new hierarchical data structure that is capable of capturing both the temporal and the spatial coherence is proposed. Conventional hierarchical data structures such as octrees are effective in characterizing the homogeneity of the field values existing in the spatial domain. However, when treating time merely as another dimension for a time-varying field, difficulties frequently arise due to the discrepancy between the field's spatial and temporal resolutions. In addition, treating spatial and temporal dimensions equally often prevents the possibility of detecting the coherence that is unique in the temporal domain. Using the proposed data structure, our algorithm can meet the following goals. First, both spatial and temporal coherence are identified and exploited for accelerating the rendering process. Second, our algorithm allows the user to supply the desired error tolerances at run time for the purpose of image-quality/rendering-speed trade-off. Third, the amount of data that are required to be loaded into main memory is reduced, and thus the I/O overhead is minimized. This low I/O overhead makes our algorithm suitable for out-of-core applications.

Shen, Han-Wei; Chiang, Ling-Jen; Ma, Kwan-Liu

1999-01-01

296

Response time testing of pressure transmitters in nuclear power plants  

International Nuclear Information System (INIS)

This paper presents a review of the response time testing practice in the nuclear power industry for the safety-related pressure, level, and flow transmitters. Two methods which have been developed and recently validated for response time testing of these transmitters are described. The advantage of the new methods is that they permit remote testing of installed transmitters from the control room while the plant is operating. Also presented in this paper are experimental data on the contribution of sensing lines to the overall response time of pressure sensing systems, and the delays that can result from blockages or air entrapped in the sensing lines

297

Response of ketone body metabolism to exercise during transition from postabsorptive to fasted state.  

Science.gov (United States)

This study examines the effects of a 2-h exercise of moderate intensity (50% of VO2 max) on the tracer-determined turnover rate of ketone bodies (KB) in 21 normal subjects fasted for 16 h, 5 days, whose basal ketonemia ranged between 0.09 and 6.16 mM. The KB response observed at the end of exercise is a function of the initial degree of ketosis. When basal ketonemia is below 0.6 mM, exercise enhances ketogenesis (Ra), the amplitude of this process being positively correlated with KB level. There is a concomitant acceleration of the metabolic clearance rate (MCR) of KB attaining 40-50%. When ketonemia exceeds 2.5 mM, the stimulatory effects of exercise on Ra and on MCR become less marked as basal ketonemia rises and are completely abolished or even reversed when initial KB level is higher than 3-4 mM. The pattern of changes in the concentration and in the overall disposal rate of KB were similar to that of Ra. It is suggested that the parallel inhibition of the stimulatory effect of work on hepatic ketogenesis and on muscular extraction of ketones associated with increasing degrees of fasting hyperketonemia has two physiological implications: it maintains the preferential utilization of KB by nonmuscular tissues (presumably the brain) and prevents the development of uncontrolled hyperketonemia, despite the intense catabolic situation created by the combination of exercise and starvation. PMID:3518484

Féry, F; Balasse, E O

1986-05-01

298

Effects of Ramadan on physical capacities of North African boys fasting for the first time  

Science.gov (United States)

Introduction Most of the literature related to the effects of Ramadan fasting on physical performance has focused on adults, and only three studies have examined its impact on children’s physical performance. Aims To examine the effects of Ramadan fasting on first-time fasting boys’ performance in short-term explosive exercises [vertical and horizontal jump tests (VJT and HJT), 20-m and 30-m sprints and medicine-ball throw (MBT)], as well as in sub-maximal endurance [6-min walking distance (6MWD) measured during the 6-min walk test (6MWT)]. Methods Eighteen Tunisian boys [mean±standard deviation (SD) of age and body mass (BM): 11.9±0.8 y and 55.4±18.2 kg, respectively] were included. The experimental design comprised four testing phases: 2-weeks before Ramadan (BR), the end of the second week (R2) and the fourth week (R4) of Ramadan, and 10–12 days after the end of Ramadan (AR). At each phase, boys performed two test sessions in the afternoon (15:00–17:00 h) interrupted by 48 h of recovery (first test session: BM, VJT, HJT, and 20-m and 30-m sprint tests; second session: MBT and 6MWT). The study was conducted during the summer of 2012 from July 5 to August 29. Results 6MWDs (m) were significantly shorter during R2 (652±101) and R4 (595±123) compared to BR (697±86) and came back to baseline values AR. BM (kg) mean±SD did not significantly change during R2 (52±15) and during R4 (53±15) compared to BR (55±17), and short-term explosive performances were unchanged throughout the study. Conclusion In non-athletic children, first-ever Ramadan fasting impairs sub-maximal aerobic capacity but has no effect on BM or short-term explosive performance. PMID:25261691

Fenneni, Mohamed A.; Latiri, Imed; Aloui, Asma; Rouatbi, Sonia; Saafi, Mohamed A.; Bougmiza, Iheb; Chamari, Karim; Saad, Helmi Ben

2014-01-01

299

Fast response neutron emission monitor for fusion reactor using stilbene scintillator and Flash-ADC.  

Science.gov (United States)

The stilbene neutron detector which has been used for neutron emission profile monitoring in JT-60U has been improved, to respond to the requirement to observe the high-frequency phenomena in megahertz region such as toroidicity-induced Alfvén Eigen mode in burning plasma as well as the spatial profile and the energy spectrum. This high-frequency phenomenon is of great interest and one of the key issues in plasma physics in recent years. To achieve a fast response in the stilbene detector, a Flash-ADC is applied and the wave form of the anode signal stored directly, and neutron/gamma discrimination was carried out via software with a new scheme for data acquisition mode to extend the count rate limit to MHz region from 1.3 x 10(5) neutron/s in the past, and confirmed the adequacy of the method. PMID:17517674

Itoga, T; Ishikawa, M; Baba, M; Okuji, T; Oishi, T; Nakhostin, M; Nishitani, T

2007-01-01

300

Fast response neutron emission monitor for fusion reactor using Stilbene Scintillator and Flash-ADC  

International Nuclear Information System (INIS)

The stilbene neutron detector which has been used for neutron emission profile monitoring in JT-60U has been improved, to respond to the requirement to observe the high-frequency phenomena in megahertz region such as toroidicity-induced Alfven Eigen mode in burning plasma as well as the spatial profile and the energy spectrum. This high-frequency phenomenon is of great interest and one of the key issues in plasma physics in recent years. To achieve a fast response in the stilbene detector, a Flash-ADC is applied and the wave form of the anode signal stored directly, and neutron/gamma discrimination was carried out via software with a new scheme for data acquisition mode to extend the count rate limit to MHz region from 1.3 x 105 neutron/s in the past, and confirmed the adequacy of the method. (authors)

 
 
 
 
301

Fast-response liquid commutating device with an inductive dynamic drive  

International Nuclear Information System (INIS)

A description is given of a fast-response multiple-operation commutating device with an induction-dynamic drive designed for commutation of high currents in the high-voltage circuits of energy inductive storages. A high-speed flow of a liquid dielectrics, produced when the drive armature is being accelerated, is used for displacing a movable contact and influencing the electric arc. The device ensures commutation of 2 kA direct current in a circuit with a voltage of up to 100 kV during about 1 ms. Experimental studies of the device operation have shown that when breaking a circuit with a current of 100 A a voltage drop across the arc constitutes 1.6 kV, which is sufficient to fire a glow discharge in the gas-discharge current interrupter. With the current increase the voltage drop across the arc also increases

302

Fast Response to Infection Spread and Cyber Attacks on Large-Scale Networks  

CERN Document Server

We present a strategy for designing fast methods of response to cyber attacks and infection spread on complex weighted networks. In these networks, nodes can be interpreted as primitive elements of the system, and weighted edges reflect the strength of interaction among these elements. The proposed strategy belongs to the family of multiscale methods whose goal is to approximate the system at multiple scales of coarseness and to obtain a solution of microscopic scale by combining the information from coarse scales. In recent years these methods have demonstrated their potential for solving optimization and analysis problems on large-scale networks. We consider an optimization problem that is based on the SIS epidemiological model. The objective is to detect the network nodes that have to be immunized in order to keep a low level of infection in the system.

Leyffer, Sven

2012-01-01

303

Fast response methods in the radiation chemistry of lethal damage in intact cells  

International Nuclear Information System (INIS)

The radiation-induced lethal damage in bacteria and mammalian cells involves some important chemical processes which extend up to about 10-2s after the initiating energy deposition. The gas explosion technique, analogous to the use of flash photolysis in photochemistry and pulse radiolysis in radiation chemistry, was applied to examine the kinetics of some of the fast processes within intact cells. The time resolution of this technique is about 100 ?s. Five nanosecond electron pulses and the rapid transition from virtually anoxic (2) to well oxygenated (>105 ppm O2) conditions can be used as the fast probes to determine the time scale of the radiosensitization by oxygen. The apparent differences between the observed intracellular kinetics of the reactions of O2 and of TAN (triacetoneamine-N-oxyl) with target damage and the reactions of these agents with DNA radicals support the view that O2 is not sensitized by reacting directly with DNA damage. In general, the processes described in this review appear to conform to simple bimolecular reaction kinetics. The intracellular reaction rates of the various agents tested are all slower than those expected from the rates of their reactions with radicals in dilute aqueous solution probably due to the complex structure of the cells. (Yamashita, S.)

304

Planck 2013 results. VII. HFI time response and beams  

CERN Document Server

This paper characterizes the effective beams, the effective beam window functions (EBWF) and the associated errors for the Planck High Frequency Instrument (HFI) detectors. The effective beam is the angular response including the effect of the optics, detectors, data processing and the scan strategy. The EBWF is the representation of this beam in the harmonic domain that is required to recover an unbiased measurement of the Cosmic Microwave Background (CMB) angular power spectrum. The HFI is a scanning instrument and its effective beams are the convolution of the optical response of the telescope and feeds, the processing of the time-ordered data and deconvolution of the bolometric and electronic time response, and the merging of several surveys to produce maps. The time response transfer functions are measured with observations of Jupiter and Saturn and by minimizing survey difference residuals. The scanning beam is the post-deconvolution angular response of the instrument, and is characterized with observat...

Ade, P A R

2014-01-01

305

In-beam fast-timing measurements in 103,105,107Cd  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Fast-timing measurements were performed recently in the region of the medium-mass 103,105,107Cd isotopes, produced in fusion evaporation reactions. Emitted gamma-rays were detected by eight HPGe and five LaBr3:Ce detectors working in coincidence. Results on new and re-evaluated half-lives are discussed within a systematic of transition rates. The $7/2_1^+$ states in 103,105,107Cd are interpreted as arising from a single-particle excitation. The half-life analysis of the $11/...

Kisyov, S.; Lalkovski, S.; Marginean, N.; Bucurescu, D.; Atanasova, L.; Balabanski, D. L.; Cata-danil, Gh; Cata-danil, I.; Daugas, J. -m; Deleanu, D.; Detistov, P.; Filipescu, D.; Georgiev, G.; Ghita, D.; Glodariu, T.

2011-01-01

306

A UV LED-based fast-pulsed photoelectron source for time-of-flight studies  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report on spectroscopy and time-of-flight measurements using an 18 keV fast-pulsed photoelectron source of adjustable intensity, ranging from single photoelectrons per pulse to 5 photoelectrons per microsecond at pulse repetition rates of up to 10 kHz. Short pulses between 40 ns and 40 microseconds in length were produced by switching light emitting diodes with central output wavelengths of 265 nm and 257 nm, in the deep ultraviolet (or UV-C) regime, at kHz frequencies. S...

Valerius, K.; Beck, M.; Arlinghaus, H.; Bonn, J.; Hannen, V. M.; Hein, H.; Ostrick, B.; Streubel, S.; Weinheimer, Ch; Zboril, M.

2009-01-01

307

FAST: a three-dimensional time-dependent FEL simulation code  

CERN Document Server

In this report we briefly describe the three-dimensional, time-dependent FEL simulation code FAST. The equations of motion of the particles and Maxwell's equations are solved simultaneously taking into account the slippage effect. Radiation fields are calculated using an integral solution of Maxwell's equations. A special technique has been developed for fast calculations of the radiation field, drastically reducing the required CPU time. As a result, the developed code allows one to use a personal computer for time-dependent simulations. The code allows one to simulate the radiation from the electron bunch of any transverse and longitudinal bunch shape; to simulate simultaneously an external seed with superimposed noise in the electron beam; to take into account energy spread in the electron beam and the space charge fields; and to simulate a high-gain, high-efficiency FEL amplifier with a tapered undulator. It is important to note that there are no significant memory limitations in the developed code and an...

Saldin, E L; Yurkov, M V

1999-01-01

308

Technical Proposal for the ALICE START Fast Timing Detector Based on Fine-Mesh Phototubes  

CERN Document Server

Technical Proposal for the ALICE START Fast Timing Detector Based on Fine-Mesh Phototubes A scintillation detector based on fine-mesh phototubes with good timing proporties ( ~ 50 ps) is proposed as a complementary detector for two existing options of the ALICE Forward Multiplicity Detector. Experimental results show high time resolution (up to 35 ps) and high gain in a magnetic field up to 0.5 T of fine-mesh Russian phototubes FEU-527. The proposed detector consists of two arrays of scintillation (or Cherenkov) counters, 24 counters each. The Monte-Carlo simulations made for the proposed design of the detector for p-p collisions give the average efficiency of the detector about 80%. The physical characteristics of the proposed detector are compared with those expected for the MCP version of the FMD.

Kaplin, V A; CERN. Geneva; Loginov, V A; Strikhanov, M N; Gavrilov, Yu K; Filippov, S N; Kurepin, A B; Mayevskaya, A I

1997-01-01

309

The ITER Fast Plant System Controller ATCA prototype Real-Time Software Architecture  

International Nuclear Information System (INIS)

Highlights: ? High performance ATCA systems for fast control and data acquisition. ? IEEE1588 timing system and synchronization. ? Plasma control algorithms. ? Real-time control software frameworks. ? Targeted for nuclear fusion experiments with long duration discharges. -- Abstract: IPFN is developing a prototype Fast Plant System Controller (FPSC) based in ATCA embedded technologies dedicated to ITER CODAC data acquisition and control tasks in the sub-millisecond range. The main goal is to demonstrate the usability of the ATCA standard and its enhanced specifications for the high speed, very high density parallel data acquisition needs of the most demanding ITER tokamak plasma Instrumentation and Control (I and C) systems. This effort included the in-house development of a new family of high performance ATCA I/O and timing boards. The standard ITER software system CODAC Core System (CCS) v3.1, with the control based in the EPICS system does not cover yet the real-time requirements fulfilled by this hardware, so a new set of software components was developed for this specific platform, attempting to integrate and leverage the new features in CSS, for example the Multithreaded Application Real Time executor (MARTe) software framework, the new Data Archiving Network (DAN) solution, an ATCA IEEE-1588-2008 timing interface, and the Intelligent Platform Management Interface (IPMI) for system monitoring and remote management. This paper presents the overall software architecture for the ATCA FPSC, as well a discussion on the ITER constrains and design choices and finally a detailed description of the software components already developed

310

Peripheral visual response time and visual display layout  

Science.gov (United States)

Experiments were performed on a group of 42 subjects in a study of their peripheral visual response time to visual signals under positive acceleration, during prolonged bedrest, at passive 70 deg headup body lift, under exposures to high air temperatures and high luminance levels, and under normal stress-free laboratory conditions. Diagrams are plotted for mean response times to white, red, yellow, green, and blue stimuli under different conditions.

Haines, R. F.

1974-01-01

311

On-line automatic sensor response time analysis system  

International Nuclear Information System (INIS)

An on-line automatic sensor response time analysis system in Taipower's Maanshan PWR nuclear power plant is presented. The algorithm applied in the system is the noise analysis technique which is an indirect method of determining sensor response time. This technique includes the power spectral density analysis and the autoregressive analysis methods. The system can also be used for long-term surveillance of sensor performance trends and cross-comparison of redundant sensors for predictive maintenance purposes. (author)

312

Speed-Accuracy Response Models: Scoring Rules Based on Response Time and Accuracy  

Science.gov (United States)

Starting from an explicit scoring rule for time limit tasks incorporating both response time and accuracy, and a definite trade-off between speed and accuracy, a response model is derived. Since the scoring rule is interpreted as a sufficient statistic, the model belongs to the exponential family. The various marginal and conditional distributions…

Maris, Gunter; van der Maas, Han

2012-01-01

313

Design and evaluation of a device for fast multispectral time-resolved fluorescence spectroscopy and imaging  

International Nuclear Information System (INIS)

The application of time-resolved fluorescence spectroscopy (TRFS) to in vivo tissue diagnosis requires a method for fast acquisition of fluorescence decay profiles in multiple spectral bands. This study focusses on development of a clinically compatible fiber-optic based multispectral TRFS (ms-TRFS) system together with validation of its accuracy and precision for fluorescence lifetime measurements. It also presents the expansion of this technique into an imaging spectroscopy method. A tandem array of dichroic beamsplitters and filters was used to record TRFS decay profiles at four distinct spectral bands where biological tissue typically presents fluorescence emission maxima, namely, 390, 452, 542, and 629 nm. Each emission channel was temporally separated by using transmission delays through 200 ?m diameter multimode optical fibers of 1, 10, 19, and 28 m lengths. A Laguerre-expansion deconvolution algorithm was used to compensate for modal dispersion inherent to large diameter optical fibers and the finite bandwidth of detectors and digitizers. The system was found to be highly efficient and fast requiring a few nano-Joule of laser pulse energy and <1 ms per point measurement, respectively, for the detection of tissue autofluorescent components. Organic and biological chromophores with lifetimes that spanned a 0.8–7 ns range were used for system validation, and the measured lifetimes from the organic fluorophores deviated by less than 10% from values reported in the literature. Multi-spectral lifetime images of organic dye solutions contained in glass capillary tubes were recorded by raster scanning the single fiber probe in a 2D plane to validate the system as an imaging tool. The lifetime measurement variability was measured indicating that the system provides reproducible results with a standard deviation smaller than 50 ps. The ms-TRFS is a compact apparatus that makes possible the fast, accurate, and precise multispectral time-resolved fluorescence lifetime measurements of low quantum efficiency sub-nanosecond fluorophores

314

A comparison of two procedures for verbal response time fractionation.  

Science.gov (United States)

To describe the mental architecture between stimulus and response, cognitive models often divide the stimulus-response (SR) interval into stages or modules. Predictions derived from such models are typically tested by focusing on the moment of response emission, through the analysis of response time (RT) distributions. To go beyond the single response event, we recently proposed a method to fractionate verbal RTs into two physiologically defined intervals that are assumed to reflect different processing stages. The analysis of the durations of these intervals can be used to study the interaction between cognitive and motor processing during speech production. Our method is inspired by studies on decision making that used manual responses, in which RTs were fractionated into a premotor time (PMT), assumed to reflect cognitive processing, and a motor time (MT), assumed to reflect motor processing. In these studies, surface EMG activity was recorded from participants' response fingers. EMG onsets, reflecting the initiation of a motor response, were used as the point of fractionation. We adapted this method to speech-production research by measuring verbal responses in combination with EMG activity from facial muscles involved in articulation. However, in contrast to button-press tasks, the complex task of producing speech often resulted in multiple EMG bursts within the SR interval. This observation forced us to decide how to operationalize the point of fractionation: as the first EMG burst after stimulus onset (the stimulus-locked approach), or as the EMG burst that is coupled to the vocal response (the response-locked approach). The point of fractionation has direct consequences on how much of the overall task effect is captured by either interval. Therefore, the purpose of the current paper was to compare both onset-detection procedures in order to make an informed decision about which of the two is preferable. We concluded in favor or the response-locked approach. PMID:25386153

van der Linden, Lotje; Riès, Stéphanie K; Legou, Thierry; Burle, Borís; Malfait, Nicole; Alario, F-Xavier

2014-01-01

315

Time response of temperature sensors using neural networks  

International Nuclear Information System (INIS)

Primary coolant RTDs (Resistance Temperature Detector) typically feed the plant's control and safety systems and must, therefore, be very accurate and have good dynamic performance. The response time of RTDs has been characterized by a single parameter called the time constant defined as the time it takes for the sensor output to achieve 63.2 percent of its final value after a step change in temperature. This step change is typically achieved by suddenly immersing the sensor in a rotating tank of water, called Plunge Test. In nuclear reactors, however, plunge testing is inconvenient because nuclear reactor service conditions are difficult to reproduce in the laboratory. An in-situ test method called LCSR - Loop Current Step Response test was developed to measure remotely the response time of RTDs. In the LCSR method, the response time of the sensor is identified by means of the LCSR transformation that involves the dynamic response modal time constants determination using a nodal heat-transfer model. For this reason, this calculation is not simple and requires specialized personnel. This work combines the two methodologies, Plunge test and LCSR test, using neural networks. With the use of neural networks it will not be necessary to use the LCSR transformation to determine sensor's time constant and this leads to more robust results. (author)

316

Time and space resolved interferometry for laser-generated fast electron measurements  

Energy Technology Data Exchange (ETDEWEB)

A technique developed to measure in time and space the dynamics of the electron populations resulting from the irradiation of thin solids by ultraintense lasers is presented. It is a phase reflectometry technique that uses an optical probe beam reflecting off the target rear surface. The phase of the probe beam is sensitive to both laser-produced fast electrons of low-density streaming into vacuum and warm solid density electrons that are heated by the fast electrons. A time and space resolved interferometer allows to recover the phase of the probe beam sampling the target. The entire diagnostic is computationally modeled by calculating the probe beam phase when propagating through plasma density profiles originating from numerical calculations of plasma expansion. Matching the modeling to the experimental measurements allows retrieving the initial electron density and temperature of both populations locally at the target surface with very high temporal and spatial resolution ({approx}4 ps,6 {mu}m). Limitations and approximations of the diagnostic are discussed and analyzed.

Antici, P. [Istituto Nazionale di Fisica Nucleare, Via E. Fermi, Frascati 40-00044 (Italy); ILE-Ecole Polytechnique-CNRS-ENSTA-Iogs-UP Sud, Batterie de l' Yvette, Palaiseau 91761 (France) and Dipartimento di Scienze di Base e Applicate per l' Ingegneria, Sapienza-Universita di Roma, Via A. Scarpa 14, Roma 00161 (Italy); LULI, Ecole Polytechnique, CNRS, CEA, UPMC, route de Saclay, Palaiseau 91128 (France); Chen, S. N. [Livermore National Laboratory, L-209, P.O. Box 808, Livermore, California 94550 (United States); Gremillet, L. [CEA, DAM, DIF, Arpajon, F-91297 (France); Grismayer, T.; Mora, P. [Centre de Physique Theorique, Ecole Polytechnique, CNRS, Palaiseau 91128 (France); Audebert, P.; Fuchs, J. [LULI, Ecole Polytechnique, CNRS, CEA, UPMC, route de Saclay, Palaiseau 91128 (France)

2010-11-15

317

Photovoltaic response time in dual-gated bilayer graphene  

Science.gov (United States)

The intrinsic thermal response timescale of bilayer graphene is sub nanosecond, due to cooling of hot electrons mediated by acoustic phonon emission. We compare the response times of the photovoltaic and bolometric response as a function of temperature and dual-gate voltages in a gapped bilayer graphene device using a pulse coincidence technique at 1.5 ?m. We find that the photovoltaic and bolometric response time are identical and vary from 100 ps to 10 ps for temperatures from 3 K to 100 K. This result shows that the near IR photovoltaic response of bilayer graphene is thermal over this temperature range. This work was supported by IARPA, the ONR MURI program, and the NSF (grants DMR-0804976 and DMR-1105224), and in part by the NSF MRSEC (grant DMR-0520471).

Kim, M.-H.; Yan, J.; Suess, R. J.; Murphy, T.; Fuhrer, M. S.; Drew, H. D.

2013-03-01

318

Time response of temperature sensors using neural networks  

International Nuclear Information System (INIS)

In a PWR nuclear power plant, the primary coolant temperature and feedwater temperature are measured using RTDs (Resistance Temperature Detectors). These RTDs typically feed the plant's control and safety systems and must, therefore, be very accurate and have good dynamic performance. The response time of RTDs is characterized by a single parameter called the Plunge Time Constant defined as the time it takes the sensor output to achieve 63.2 percent of its final value after a step change in temperature. Nuclear reactor service conditions are difficult to reproduce in the laboratory, and an in-situ test method called LCSR (Loop Current Step Response) test was developed to measure remotely the response time of RTDs. >From this test, the time constant of the sensor is identified by means of the LCSR transformation that involves the dynamic response modal time constants determination using a nodal heat-transfer model. This calculation is not simple and requires specialized personnel. For this reason an Artificial Neural Network has been developed to predict the time constant of RTD from LCSR test transient. It eliminates the transformations involved in the LCSR application. A series of LCSR tests on RTDs generates the response transients of the sensors, the input data of the networks. Plunge tests are used to determine the time constants of the RTDs, the desired output of the ANN, trained using these sets of input/output data. This methodology was firstly applied to theoretical data simulating 10 RTDs with different time constant values, resulting in an average error of about 0.74 %. Experimental data from three different RTDs was used to predict time constant resulting in a maximum error of 3,34 %. The time constants values predicted from ANN were compared with those obtained from traditional way resulting in an average error of about 18 % and that shows the network is able to predict accurately the sensor time constant. (author)

319

Satellite monitoring of volcanic SO2 emissions within the Volcano Fast Response System (Exupéry)  

Science.gov (United States)

Volcanic eruptions are a major hazard to the local population near large volcanoes and to aviation. They also play an important role in global climate change. Atmospheric SO2 is an important indicator for volcanic eruptions and volcanic activity like passive degassing. Space based atmospheric sensors such as GOME-2 on MetOp and OMI on EOS-Aura make it possible to detect the emissions of volcanic SO2 in near-real time (NRT) and monitor volcanic activity and eruptions on a global scale. The GOME-2 instrument provides operational measurements of the SO2 columns with a spatial resolution of 80x40 km² and a global coverage within about one day. Volcanic sulfur dioxide emissions are determined from solar backscatter measurements in the ultra-violet spectral range between 315 - 326 nm, applying the Differential Optical Absorption Spectroscopy (DOAS) method. This retrieval technique uses the high spectral resolution of the instrument to determine the total column density of SO2. The ability to monitor changes in volcanic degassing behavior is of great importance for early warning of volcanic activity, as large increases in SO2 fluxes are often an indicator for new episodes of volcanic unrest. Ensembles of backward trajectories using the FLEXTRA model are applied to relate exceptional SO2 values to particular sources or regions and hence attribute them to a volcanic or anthropogenic origin. Trajectory density maps give an overview of the most probable location of the emission source. Additionally, the moment of the eruption as well as the emission and the plume height can be estimated. Hypothetical forward trajectories starting at potentially active volcanoes allow forecasting the dispersion of volcanic SO2 and ash depending on the emission height in case of an eruption. For validation purposes the dispersion model FLEXPART provides a three dimensional forecast of the plume motion and the transport of SO2 for several days. The GOME-2 observations of volcanic SO2 are used in a new Volcano Fast Response System (Exupéry) developed within the framework of the German Geotechnology Program that includes both ground-based and space-based measurements of different volcanic parameters. The daily GOME-2 SO2 data as well as hypothetical trajectories and probability density maps are supplied to a database approximately 7 hours after the measurement and displayed in a GIS system that can be accessed by local authorities and observatories to provide additional information in the case of volcanic unrest. In this contribution we present exemplary results of GOME-2 SO2 observations and the trajectory matching technique for recent volcanic eruptions. Further we will present initial validation results for GOME-2 SO2 data using ground-based measurements in combination with other satellite observations, as well as dispersion modeling. We will focus on the use of the GOME-2 SO2 data and model results within the Exupéry project.

Rix, Meike; Maerker, Cordelia; Valks, Pieter; Erbertseder, Thilo

2010-05-01

320

High performance organic-inorganic perovskite-optocoupler based on low-voltage and fast response perovskite compound photodetector  

Science.gov (United States)

Organic-inorganic hybrid photodetectors attract considerable attention because they can combine the advantages of both organic and inorganic systems. Here, a perovskite compound with a broad absorption spectrum and high power conversion efficiency is used as a photosensitive layer in an organic/inorganic hybrid heterojunction photodetector with a high and fast response. The high sensitivity exceeding 104 is obtained at bias of 0-4 V. Using a tandem organic light-emitting diode (OLED) as the light source, we fabricated an optocoupler device. The optocoupler achieved a maximum photoresponsivity of 1.0 A W-1 at 341.3 ?Wcm-2 at an input voltage of 6 V. The device also exhibits rapid response times of ?rise ~ 20 ?s and ?fall ~ 17 ?s as well as a high current transfer ratio (CTR) of 28.2%. After applying an amplification circuit, the CTR of the optocoupler increases to 263.3%, which is comparable with that of commercial inorganic optocouplers. The developed hybrid optocoupler thus shows great promise for use in photonics.

Li, Dong; Dong, Guifang; Li, Wenzhe; Wang, Liduo

2015-01-01

 
 
 
 
321

High performance organic-inorganic perovskite-optocoupler based on low-voltage and fast response perovskite compound photodetector.  

Science.gov (United States)

Organic-inorganic hybrid photodetectors attract considerable attention because they can combine the advantages of both organic and inorganic systems. Here, a perovskite compound with a broad absorption spectrum and high power conversion efficiency is used as a photosensitive layer in an organic/inorganic hybrid heterojunction photodetector with a high and fast response. The high sensitivity exceeding 10(4) is obtained at bias of 0-4?V. Using a tandem organic light-emitting diode (OLED) as the light source, we fabricated an optocoupler device. The optocoupler achieved a maximum photoresponsivity of 1.0?A W(-1) at 341.3??Wcm(-2) at an input voltage of 6?V. The device also exhibits rapid response times of ?rise ~ 20??s and ?fall ~ 17??s; as well as a high current transfer ratio (CTR) of 28.2%. After applying an amplification circuit, the CTR of the optocoupler increases to 263.3%, which is comparable with that of commercial inorganic optocouplers. The developed hybrid optocoupler thus shows great promise for use in photonics. PMID:25600830

Li, Dong; Dong, Guifang; Li, Wenzhe; Wang, Liduo

2015-01-01

322

Fast magnetosonic wave excitation by an array of wires with time-modulated currents  

Science.gov (United States)

The excitation of Fast Magnetosonic (FMS) waves by a cylindrical array of parallel tethers carrying time-modulated current is discussed. The tethers would fly vertical in the equatorial plane, which is perpendicular to the geomagnetic field when its tilt is ignored, and would be stabilized by the gravity gradient. The tether array would radiate a single FMS wave. In the time-dependent background made of geomagnetic field plus radiated wave, plasma FMS perturbations are excited in the array vicinity through a parametric instability. The growth rate is estimated by truncating the evolution equation for FMS perturbations to the two azimuthal modes of lowest order. Design parameters such as tether length and number, required power and mass are discussed for Low Earth Orbit conditions. The array-attached wave structure would have the radiated wave controlled by the intensity and modulation frequency of the currents, making an active experiment on non-linear low frequency waves possible in real space plasma conditions.

Sanchez-Arriaga, G.; Sanmartin, J. R.

2010-02-01

323

Design and calibration of a fast-time resolution charge exchange analyzer  

International Nuclear Information System (INIS)

A five channel, fast time resolution, scanning charge exchange analyzer has been developed for the Madison Symmetric Torus (MST). The analyzer consists of an iron vacuum vessel, a gas stripping cell, an electrostatic bending field, and five continuous electron multiplier detectors. The incident neutral flux and operation of the detectors in current mode limits the time resolution of the analyzer to 10 ?s. The analyzer was absolutely calibrated over the energy range of interest (500--2000 eV) with an H+ beam, so that the charge exchange power loss could also be measured. The analyzer can be swiveled on a shot-to-shot basis for measurements of Ti(r), where 0.3 < r/a < 0.7. The mechanical design was driven by the need for a low cost, expandable ion temperature diagnostic

324

Target Localization by Resolving the Time Synchronization Problem in Bistatic Radar Systems Using Space Fast-Time Adaptive Processor  

Directory of Open Access Journals (Sweden)

Full Text Available The proposed technique allows the radar receiver to accurately estimate the range of a large number of targets using a transmitter of opportunity as long as the location of the transmitter is known. The technique does not depend on the use of communication satellites or GPS systems, instead it relies on the availability of the direct transmit copy of the signal from the transmitter and the reflected paths off the various targets. An array-based space-fast time adaptive processor is implemented in order to estimate the path difference between the direct signal and the delayed signal, which bounces off the target. This procedure allows us to estimate the target distance as well as bearing.

D. Madurasinghe

2009-01-01

325

Analysis of Shiraz Solar Thermal Power Plant Response Time  

Directory of Open Access Journals (Sweden)

Full Text Available Shiraz pilot solar thermal power plant is the first Iranian solar power plant constructed near the city of Shiraz, Iran. The main purpose of constructing this pilot plant was to acquire the technology of developing parabolic trough solar thermal power plants for future energy production from solar energy. This plant consists of 48 parabolic trough collectors; each one has 25m long and 3.4 m wide. The plant consists of two cycles, oil heat absorbing cycle and steam production cycle. The plant performance and transition period to reach steady state condition or damping some disturbances as well as oil cycle heating and steam generation rate depends on several factors such as oil cycle response time. Response time is a parameter that can be used for efficient control of solar power plant. To study response time, field experimental measurements have been made during the years 2009 to 2010 based on the standard procedure and plant simulation. The experiments include: plant start up, evaluation of oil temperature increase in the field of collectors, solar radiation measurements, temperature and pressure changes in the heat exchangers, weather temperature changes and wind speed and the effect of above changes on the system response time are determined. Two modeling methods (based on the recommended standards of finding response time are employed. Results show that response time of the oil cycle varies from 150 seconds to 400 seconds by measurements, while by modeling simulation it is about 400-500 seconds. Response time is strongly depends on the environmental conditions such as oil temperture, wind and ambient temperature and specially the oil mass flow rate.

K. Azizian

2013-01-01

326

An improved space-time kinetics method for fast and thermal reactor analysis  

International Nuclear Information System (INIS)

An improved space-time kinetics method that can be applied to the analysis of either fast or thermal reactor transients is presented. The method (called quasi-static synthesis - QSS) blends the concepts of formal reduction (i.e., the quasi-static method) and time synthesis into a single unified approach to handle the space-time equations. In particular, the method links the lumped parameter formalism of the quasi-static approach (used to compute the relative amplitude or power in the reactor) with a time synthesis techniques employed in the determination of spatial/spectral shape-functions needed in defining the lumped parameters. A unique feature of the synthesis procedure is that the trial-shapes used in synthesizing shape-functions are computed as the transient progresses, thus obviating the need for precomputed trial-shapes. Preliminary results obtained with the method indicate reduced computer time, while maintaining computational accuracy, when compared to several other kinetics presently in use. In addition to the development of the QSS method, this dissertation also introduces a simple and efficient approach for solving the point kinetics equations. Starting with an integral form of these equations, the only assumption made is that the time-dependent amplitude-function varies linearly between kinetics time steps (being exact at the time steps). The resulting semi-implicit integration algorithms for the amplitude-function and precursor concentrations appear to on and precursor concentrations appear to allow for large kinetics time steps than do most conventional methods. Furthermore, because these algorithms are of such a simple nature, the computing cost per kinetics time step is also greatly reduced

327

Development of a fast response rotating polarimeter for a faraday rotation measurement  

International Nuclear Information System (INIS)

This paper describes a method for using a spindle sustained with active magnetic bearing to make a rotating half waveplate frequency more fast. The time interval of the zero-cross phase measurement is 189 ?sec in this experiment. The magnetic bearing is applicable to increase the rotating waveplate frequency by a factor of 2-3 compared with the conventional one. The waveplate speed as well as the deviation with respect to the stationary laser beam has no influence on the amplitude and phase shift of the rotating polarized beam signal. There is also no influence of the mirror reflections on the phase shift. The overall phase resolution is estimated to be about 0.1 degrees. (author)

328

Complex of electronic equipment for the synchrocyclotron fast-response programmed HF modulator  

International Nuclear Information System (INIS)

To lower down HF-power and beam phase losses while accelerating charged particles in a synchrocyclotron it is proposed to employ a fast programmed modulator of the self-excited oscillator. To correct the amplitude-frequency characteristics of the resonance system it is proposed to use a pulse anode modulator the output stage of which constitutes a parallel-controlled series regulator. Main parameters of the modulator are as follows: the output voltage is 10 kV, the transient time is 2-3 ?s, the output voltage modulation depth is 0-100%, the off-duty factor is 1.3. The modulator is controlled from a source of functional reference voltage developed on the base of a digital-to-analog converter in the CAMAC standard through a direct-current amplifier having a gain of no less than 1000 and an output voltage of 600-0 V

329

The Effect of Holly Fasting Month of Ramadan on the Delayed Type Hypersensitivity Response to Purified Protein Derivative  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Studies during recent decade indicate that low calorie intake has potentiating effect on immune response . So the effect of fasting in holly month of Ramadan on cellular immune was studied. In this study , delayed type hypersensitivity (DTH) to purified protein derivative (PPD) test was selected to evaluate cellular immune response , because this test is not only very simple but also is valuable and reliable. This research studied DTH to PPD in two groups of students b...

Rahmani, M.; Zarei, M.

2003-01-01

330

Planck 2013 results. VII. HFI time response and beams  

DEFF Research Database (Denmark)

This paper characterizes the effective beams, the effective beam window functions (EBWF) and the associated errors for the Planck High Frequency Instrument (HFI) detectors. The effective beam is the angular response including the effect of the optics, detectors, data processing and the scan strategy. The EBWF is the representation of this beam in the harmonic domain that is required to recover an unbiased measurement of the Cosmic Microwave Background (CMB) angular power spectrum. The HFI is a scanning instrument and its effective beams are the convolution of the optical response of the telescope and feeds, the processing of the time-ordered data and deconvolution of the bolometric and electronic time response, and the merging of several surveys to produce maps. The time response transfer functions are measured with observations of Jupiter and Saturn and by minimizing survey difference residuals. The scanning beam is the post-deconvolution angular response of the instrument, and is characterized with observations of Mars. The main beam solid angles are determined to better than 0.5% at each HFI frequency band. Observations of Jupiter and Saturn limit near sidelobes to ~0.1% of the total solid angle. Time response residuals remain as long tails in the scanning beams, but contribute

Planck Collaboration,, no-firstname; Ade, P. A. R.

2013-01-01

331

Fast responsive and highly efficient optical upconverter based on phosphorescent OLED.  

Science.gov (United States)

In this work, an organic-inorganic hybrid optical upconverter that can convert irradiated 980 nm IR light to 510 nm green phosphorescence sensitively was fabricated and studied. fac-Tris(2-phenylpyridine) iridium (Ir(ppy)3) doped 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) was used as emitting layer in the phosphorescent organic light-emitting diode (OLED) unit. The upconverter using a phosphorescent OLED as display unit can achieve a higher upconversion efficiency and a low power consumption when compared with the one using fluorescent. An upconversion efficiency of 4.8% can be achieved for phosphorescent device at 15 V, much higher than that of fluorescent one (2.0%). The upconverter's transient optical and electric response to IR pulse were also investigated for the first time. The response time was found to be influenced by IR intensity and applied voltage. It has a response time as short as 60 ?s. The rapid response property of the upconverter makes it feasible to be applied to high-speed IR imaging systems. PMID:25310022

Chu, Xinbo; Guan, Min; Niu, Litao; Zeng, Yiping; Li, Yiyang; Zhang, Yang; Zhu, Zhanping; Wang, Baoqiang

2014-11-12

332

Effect of the fissile bead's and thermocouple wires’ sizes on the response time of a fission couple  

International Nuclear Information System (INIS)

The fission couple is proposed as a fast response miniature neutron detector in the measurement of time dependent energy depositions within the fissile material based on theoretical analysis, but the response time of a fission couple is relatively slow in practice. The time lag originated from heat transfer process was demonstrated to be the dominating factor by theoretical simulations and experimental verification in this paper. The response of a fission couple as a function of the bead size and the thermocouple wires’ sizes are simulated using ANSYS workbench. The decrease of wires’ diameter results in the decrease of response time, and the increase of bead's diameter leads to a slight increase of response time. During a pulse heating transient in the fuel of Chinese Fast Burst Reactor II with a FWHM of 181?s, the time lag originated from heat transfer process is about tens of microseconds for the peaks of the change rate of temperature, and is of the order of milliseconds to achieve 85% of the temperature rise for a typical fission couple with a ? 1 mm fissile bead and two ? 0.05 mm thermocouple wires. The results obtained provide foundation for the optimization of fission couples

333

Effect of the fissile bead's and thermocouple wires' sizes on the response time of a fission couple  

Science.gov (United States)

The fission couple is proposed as a fast response miniature neutron detector in the measurement of time dependent energy depositions within the fissile material based on theoretical analysis, but the response time of a fission couple is relatively slow in practice. The time lag originated from heat transfer process was demonstrated to be the dominating factor by theoretical simulations and experimental verification in this paper. The response of a fission couple as a function of the bead size and the thermocouple wires' sizes are simulated using ANSYS workbench. The decrease of wires' diameter results in the decrease of response time, and the increase of bead's diameter leads to a slight increase of response time. During a pulse heating transient in the fuel of Chinese Fast Burst Reactor II with a FWHM of 181?s, the time lag originated from heat transfer process is about tens of microseconds for the peaks of the change rate of temperature, and is of the order of milliseconds to achieve 85% of the temperature rise for a typical fission couple with a ? 1 mm fissile bead and two ? 0.05 mm thermocouple wires. The results obtained provide foundation for the optimization of fission couples.

Liang, Wenfeng; Lu, Yi; Li, Meng; Fan, Xiaoqiang; Lu, Wei

2014-05-01

334

Effect of the fissile bead's and thermocouple wires' sizes on the response time of a fission couple.  

Science.gov (United States)

The fission couple is proposed as a fast response miniature neutron detector in the measurement of time dependent energy depositions within the fissile material based on theoretical analysis, but the response time of a fission couple is relatively slow in practice. The time lag originated from heat transfer process was demonstrated to be the dominating factor by theoretical simulations and experimental verification in this paper. The response of a fission couple as a function of the bead size and the thermocouple wires' sizes are simulated using ANSYS workbench. The decrease of wires' diameter results in the decrease of response time, and the increase of bead's diameter leads to a slight increase of response time. During a pulse heating transient in the fuel of Chinese Fast Burst Reactor II with a FWHM of 181 ?s, the time lag originated from heat transfer process is about tens of microseconds for the peaks of the change rate of temperature, and is of the order of milliseconds to achieve 85% of the temperature rise for a typical fission couple with a ? 1 mm fissile bead and two ? 0.05 mm thermocouple wires. The results obtained provide foundation for the optimization of fission couples. PMID:24880361

Liang, Wenfeng; Lu, Yi; Li, Meng; Fan, Xiaoqiang; Lu, Wei

2014-05-01

335

Signal and Noise Analysis in TRION -Time-Resolved Integrative Optical Fast Neutron Detector  

CERN Document Server

TRION is a sub-mm spatial resolution fast neutron imaging detector, which employs an integrative optical time-of-flight technique. The detector was developed for fast neutron resonance radiography, a method capable of detecting a broad range of conventional and improvised explosives. In this study we have analyzed in detail, using Monte-Carlo calculations and experimentally determined parameters, all the processes that influence the signal and noise in the TRION detector. In contrast to event-counting detectors where the signal-to-noise ratio is dependent only on the number of detected events (quantum noise), in an energy-integrating detector additional factors, such as the fluctuations in imparted energy, number of photoelectrons, system gain and other factors will contribute to the noise. The excess noise factor (over the quantum noise) due to these processes was 4.3, 2.7, 2.1, 1.9 and 1.9 for incident neutron energies of 2, 4, 7.5, 10 and 14 MeV, respectively. It is shown that, even under ideal light colle...

Vartsky, D; Mor, I; Goldberg, M B; Bar, D; Dangendorf, V

2009-01-01

336

Synchronous timing of multi-energy fast beam extraction during a single AGS cycle  

International Nuclear Information System (INIS)

Synchronous triggering of fast beams is required because the field of Kicker Magnets must rise within the open space between one beam bunch and the next. Within the Brookhaven AGS, Fast Extracted Beam (FEB) triggering combines nominal timing, based on beam energy with bunch-to-bunch synchronization, based on the accelerating rf waveform. During beam acceleration, a single bunch is extracted at 22 GeV/c and within the same AGS cycle, the remaining eleven bunches are extracted at 28.4 GeV/c. When the single bunch is extracted, a ''hole'', which is left in the remaining circulating beam, can appear in random locations within the second extraction during successive AGS cycles. To overcome this problem, a synchronous rf/12 counting scheme and logic circuitry are used to keep track of the bunch positions relative to each other, and to place the ''hole'' in any desired location within the second extraction. The rf/12 signal is used also to synchronize experimenters triggers

337

Preoperative Management of Surgical Patients by “Shortened Fasting Time”: A Study on the Amount of Total Body Water by Multi-Frequency Impedance Method  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Aim: Preoperative fasting is an established procedure to be practiced for patients before surgery, but optimal preoperative fasting time still remains controversial. The aim of this study was to investigate the effect of “shortened preoperative fasting time” on the change in the amount of total body water (TBW) in elective surgical patients. TBW was measured by multi-frequency impedance method.

Taniguchi, Hideki; Sasaki, Toshio; Fujita, Hisae

2012-01-01

338

4? bismuth germanate (BGO) detector array for heavy ion physics and the prompt response of BGO to fast neutrons  

International Nuclear Information System (INIS)

The properties of a gamma-ray facility proposed for the Chalk River MP tandem superconducting-cyclotron accelerator are described. The target is surrounded by a multi-segmented 4? BGO detector that determines, for each event, the ?-ray multiplicity, the spin orientation, and the total energy of the entry state in a ?-ray cascade. A small fraction of the ?-rays is detected outside the 4? array in up to eleven intrinsic Ge detectors, each of them inside a BGO Compton suppressor. The facility will allow high-resolution spectroscopy of discrete lines, with low Compton background and with strong enhancement of high-multiplicity events. Results of Monte Carlo calculations on the gamma-ray response of the facility are described. We have measured the prompt response of a 7.6 x 7.6 cm BGO detector to fast neutrons in the energy range from 0.4 to 10 MeV, using pulsed proton beams and time-of-flight methods. Both monoenergetic neutrons from the 7Li(p,n) reaction, and continuous neutron energy distributions from the 197Au(p,n) reaction were employed. The observed energy spectra in the BGO detector are dominated by ?-rays from the (n,n'?) reaction from Bi and Ge. Compared with a NaI(Tl) detector of the same volume, the neutron response of BGO is much smaller below E/sub n/ = 2 MeV because of the low density of levels in 209Bi, whereas above 3.5 MeV the neutron efficiencies are roughly the same. These results imply that a 4? detector made ofs imply that a 4? detector made of BGO has a gamma-to-neutron detection ratio much superior to that of NaI(Tl)

339

Metabolic response to 36 hours of fasting in young men born small vs appropriate for gestational age  

DEFF Research Database (Denmark)

AIMS/HYPOTHESIS: Being born small for gestational age (SGA) is associated with an increased risk of type 2 diabetes in an affluent society, but could confer an improved chance of survival during sparse living conditions. We studied whether insulin action and other metabolic responses to prolonged fasting differed between 21 young adults born SGA and 18 matched controls born appropriate for gestational age (AGA). METHODS: A frequently sampled IVGTT and indirect calorimetry measurements were performed after a 36 h fast. Endogenous glucose production, insulin sensitivity (SI), first-phase insulin secretion and glucose effectiveness were estimated by stable isotope tracer techniques and minimal modelling. Muscle and fat biopsies were obtained after 35 h of fasting. RESULTS: During fasting, SGA individuals experienced a more pronounced decrease in serum insulin and lower plasma triacylglycerol levels compared with AGA individuals. In addition, energy expenditure decreased in SGA but increased in AGA individuals.After fasting, SGA individuals displayed lower fat oxidation than AGA individuals. SG was reduced in SGA compared with AGA individuals, whereas hepatic or whole body insulin action (SI) did not differ between groups. SGA individuals had increased muscle PPARGC1A DNA methylation. We found no differences in adipose tissue PPARGC1A DNA methylation, muscle and adipose tissue PPARGC1A mRNA expression, or muscle glycogen levels between the groups. CONCLUSION: Compared with AGA individuals, SGA individuals displayed a more energy-conserving and energy-conserving cardiometabolic response to 36 h fasting. The role of increased muscle PPARGC1A DNA methylation in mediating this response requires further study.

JØrgensen, Sine W; BrØns, Charlotte

2015-01-01

340

System-level Specifications of the Timing and Fast Control system for the LHCb Upgrade  

CERN Document Server

The LHCb experiment has proposed an upgrade towards a full 40 MHz readout system in order to run between five and ten times the initial design luminosity. The various sub-systems in the readout architecture will need to be upgraded in order to cope with higher sub-detector occupancies, higher rate and higher network load. In this paper, we describe the specifications of the new Timing and Fast Control (S- TFC) system. We define the requirements for the new S-TFC, and specify its architecture and the individual components. The system is based on a single new Readout Supervisor (S-ODIN) instantiating several S-TFC masters to allow partitioning. The communication with the readout electronics is ensured by a shared high-speed optical link network for both the distribution of timing and synchronous control information, as well as trigger/throttle communication. An interface board (SOL40) with fan-out capabilities for timing and synchronous information and fan-in capabilities for throttle and rate regulation of the...

Alessio, Federico

2014-01-01

 
 
 
 
341

Reaction-time response of a large commercial aircraft  

International Nuclear Information System (INIS)

The reaction-time response of a large commercial aircraft is defined. The aircraft is examined as a thin-walled tubular missile. The impact is assumed soft, and the target's effect on the reaction-time response is neglected. The reaction-time response is defined assuming a normal impact on a rigid wall. The reaction-time response is defined with the analytical Riera method and with the numerical explicit finite element method. The Riera force history is solved with the finite difference method. For the finite element method, two codes are used: Abaqus/Explicit and LS-DYNA. Focus is on the sensitivity study of the used methods. The outer shell of the aircraft is modeled, and an approximation for the mass-distribution is made. Sensitivity to modeling assumptions is studied in order to get information on the adequacy of modeling. The results indicate relatively small sensitivity to modeling assumptions. The wings should be modeled more accurately in order to obtain the dominant frequency response in global structural analysis. (author)

342

Program for the analysis of time series. [by means of fast Fourier transform algorithm  

Science.gov (United States)

A digital computer program for the Fourier analysis of discrete time data is described. The program was designed to handle multiple channels of digitized data on general purpose computer systems. It is written, primarily, in a version of FORTRAN 2 currently in use on CDC 6000 series computers. Some small portions are written in CDC COMPASS, an assembler level code. However, functional descriptions of these portions are provided so that the program may be adapted for use on any facility possessing a FORTRAN compiler and random-access capability. Properly formatted digital data are windowed and analyzed by means of a fast Fourier transform algorithm to generate the following functions: (1) auto and/or cross power spectra, (2) autocorrelations and/or cross correlations, (3) Fourier coefficients, (4) coherence functions, (5) transfer functions, and (6) histograms.

Brown, T. J.; Brown, C. G.; Hardin, J. C.

1974-01-01

343

Fast Tracker: A Hardware Real Time Track Finder for the ATLAS Trigger System  

CERN Document Server

The Fast Tracker (FTK) is an integral part of the trigger upgrade program for the ATLAS detector at the Large Hadron Collider (LHC). As the LHC luminosity approaches its design level of 10^34cm^?2s^?1, the combinatorial problem posed by charged particle tracking becomes increasingly difficult due to the swelling of multiple interactions per bunch crossing (pile-up). The FTK is a highly-parallel hardware system intended to provide high-quality tracks with transverse momentum above 1 GeV/c in real time for online trigger system. The FTK system’s design, based on a mixture of advanced technologies, and expected physics performance will be presented.

Kimura, N; The ATLAS collaboration

2013-01-01

344

A UV LED-based fast-pulsed photoelectron source for time-of-flight studies  

CERN Document Server

We report on spectroscopy and time-of-flight measurements using an 18 keV fast-pulsed photoelectron source of adjustable intensity, ranging from single photoelectrons per pulse to 5 photoelectrons per microsecond at pulse repetition rates of up to 10 kHz. Short pulses between 40 ns and 40 microseconds in length were produced by switching light emitting diodes with central output wavelengths of 265 nm and 257 nm, in the deep ultraviolet (or UV-C) regime, at kHz frequencies. Such photoelectron sources can be useful calibration devices for testing the properties of high-resolution electrostatic spectrometers, like the ones used in current neutrino mass searches.

Valerius, K; Arlinghaus, H; Bonn, J; Hannen, V M; Hein, H; Ostrick, B; Streubel, S; Weinheimer, Ch; Zboril, M

2009-01-01

345

In-beam fast-timing measurements in 103,105,107Cd  

CERN Document Server

Fast-timing measurements were performed recently in the region of the medium-mass 103,105,107Cd isotopes, produced in fusion evaporation reactions. Emitted gamma-rays were detected by eight HPGe and five LaBr3:Ce detectors working in coincidence. Results on new and re-evaluated half-lives are discussed within a systematic of transition rates. The $7/2_1^+$ states in 103,105,107Cd are interpreted as arising from a single-particle excitation. The half-life analysis of the $11/2_1^-$ states in 103,105,107Cd shows no change in the single-particle transition strength as a function of the neutron number.

Kisyov, S; Marginean, N; Bucurescu, D; Atanasova, L; Balabanski, D L; Cata-Danil, Gh; Cata-Danil, I; Daugas, J -M; Deleanu, D; Detistov, P; Filipescu, D; Georgiev, G; Ghita, D; Glodariu, T; Jolie, J; Judson, D S; Lozeva, R; Marginean, R; Mihai, C; Negret, A; Pascu, S; Radulov, D; Regis, J -M; Rudigier, M; Sava, T; Stroe, L; Suliman, G; Zamfir, N V; Zell, K O; Zhekova, M

2011-01-01

346

Comparison of LMFBR piping response obtained using response spectra and time history methods  

International Nuclear Information System (INIS)

The dynamic response to a seismic event is calculated for a piping system using a response spectrum analysis method and two time history analysis methods. The results from the analytical methods are compared to identify causes for the differences between the sets of analytical results. Comparative methods are also presented which help to gain confidence in the accuracy of the analytical methods in predicting piping system structural response during seismic events. 7 refs

347

Artificial diamonds as radiation-hard detectors for ultra-fast fission-fragment timing  

Energy Technology Data Exchange (ETDEWEB)

In the framework of the construction of the double time-of-flight spectrometer VERDI, where we aim at measuring pre- and post-neutron masses directly and simultaneously, ultra-fast time pick-up detectors based on artificial diamond material were investigated for the first time with fission fragments from {sup 252}Cf (0.5MeV/utiming resolution of a 100?m thick polycrystalline CVD diamond detector with a size of 1×1 cm{sup 2} was determined to ?{sub int}=(283±41)ps by comparison with Monte-Carlo simulations. Using broadband pre-amplifiers, 4-fold segmented detectors of same total size and with a thickness of 180?m show an intrinsic timing resolution of ?{sub int}=(106±21)ps. This is highly competitive with the best micro-channel plate detectors. Due to the limited and batch-dependent charge collection efficiency of poly-crystalline diamond material, the detection efficiency for fission fragments may be smaller than 100%. -- Highlights: ? First use of chemical vapor deposited diamond for heavy ions with kinetic energies below 2 MeV per nucleon. ? Fission-fragment time-of-flight measurements with a timing resolution better than 150 ps. ? Radiation-hard fission event trigger to be used in an intense neutron field.

Oberstedt, S., E-mail: stephan.oberstedt@ec.europa.eu [European Commission, DG Joint Research Centre (IRMM), B-2440 Geel (Belgium); Borcea, R.; Bry?, T.; Gamboni, Th.; Geerts, W.; Hambsch, F.-J. [European Commission, DG Joint Research Centre (IRMM), B-2440 Geel (Belgium); Oberstedt, A. [Fundamental Fysik, Chalmers Tekniska Högskola, S-41296 Göteborg (Sweden); Akademin för Naturvetenskap och Technik, Örebro Universitet, S-70182 Örebro (Sweden); Vidali, M. [European Commission, DG Joint Research Centre (IRMM), B-2440 Geel (Belgium)

2013-06-21

348

Artificial diamonds as radiation-hard detectors for ultra-fast fission-fragment timing  

International Nuclear Information System (INIS)

In the framework of the construction of the double time-of-flight spectrometer VERDI, where we aim at measuring pre- and post-neutron masses directly and simultaneously, ultra-fast time pick-up detectors based on artificial diamond material were investigated for the first time with fission fragments from 252Cf (0.5MeV/u9 fission-fragments/cm2 together with more than 3.5×109 neutrons/cm2 and 3×1010?-particles/cm2. This fluence is characteristic for fission experiments. The pre-requisite for the observed signal stability is the application of priming of the diamond material with a strong ?-source for about 48 h. The intrinsic timing resolution of a 100?m thick polycrystalline CVD diamond detector with a size of 1×1 cm2 was determined to ?int=(283±41)ps by comparison with Monte-Carlo simulations. Using broadband pre-amplifiers, 4-fold segmented detectors of same total size and with a thickness of 180?m show an intrinsic timing resolution of ?int=(106±21)ps. This is highly competitive with the best micro-channel plate detectors. Due to the limited and batch-dependent charge collection efficiency of poly-crystalline diamond material, the detection efficiency for fission fragments may be smaller than 100%. -- Highlights: ? First use of chemical vapor deposited diamond for heavy ions with kinetic energies below 2 MeV per nucleon. ? Fission-fragment time-of-flight measurements with a timing resolution better than 150 ps. ? Radiation-hard fission event trigger to be used in an intense neutron field

349

Time dependent start-up thermal analysis of a Super Fast Reactor  

Energy Technology Data Exchange (ETDEWEB)

Highlights: • Time dependent startup thermal analysis of a Super Fast Reactor is performed. • A recirculation system is used for pressurization and for generating supercritical steam. • MCST satisfies the criterion both during subcritical pressure and during power-raising. • MCST is not sensitive to the change of inlet temperature, gap volume and flow rate because of high flow to power ratio. • CHF is not limiting the MCST during subcritical pressure due to large margin of heat flux. -- Abstract: The startup system of a supercritical pressure light water cooled fast reactor (Super FR) is studied by time dependent thermal-hydraulic analysis. The plant analysis code is developed based on an innovative upward flow pattern in all the assemblies of the Super FR. A recirculation system consisting of a steam drum, a circulation pump, and a heat exchanger is used for the startup. Detailed procedures are performed and the maximum cladding surface temperature (MCST) at rated power, 640 °C, is used as the criterion. Firstly a small constant nuclear power is used for rising the core feed water temperature to be 280 °C through the recirculation system. Secondly, pressurization is done in the recirculation system from atmospheric to operating pressure, 25 MPa, by raising the power. Thirdly, line-switching from recirculation mode to once-through direct-cycle is performed while turbines are started by supercritical steam at supercritical pressure. Finally the power is raised to be 100% of power followed by raising the flow rate. During pressurization the heat flux margin is large due to low power used for pressurization and the MCST is much lower than the criterion. The MCST is not sensitive to the inlet temperature, the flow rate, and the gap volume of the core because of high flow to power ratio. Smaller dimension of steam drum can be used for pressurization stably. The MCST satisfies the criterion both during subcritical pressure and during power-raising.

Sutanto,, E-mail: sutanto@fuji.waseda.jp; Oka, Yoshiaki

2013-10-15

350

Time dependent start-up thermal analysis of a Super Fast Reactor  

International Nuclear Information System (INIS)

Highlights: • Time dependent startup thermal analysis of a Super Fast Reactor is performed. • A recirculation system is used for pressurization and for generating supercritical steam. • MCST satisfies the criterion both during subcritical pressure and during power-raising. • MCST is not sensitive to the change of inlet temperature, gap volume and flow rate because of high flow to power ratio. • CHF is not limiting the MCST during subcritical pressure due to large margin of heat flux. -- Abstract: The startup system of a supercritical pressure light water cooled fast reactor (Super FR) is studied by time dependent thermal-hydraulic analysis. The plant analysis code is developed based on an innovative upward flow pattern in all the assemblies of the Super FR. A recirculation system consisting of a steam drum, a circulation pump, and a heat exchanger is used for the startup. Detailed procedures are performed and the maximum cladding surface temperature (MCST) at rated power, 640 °C, is used as the criterion. Firstly a small constant nuclear power is used for rising the core feed water temperature to be 280 °C through the recirculation system. Secondly, pressurization is done in the recirculation system from atmospheric to operating pressure, 25 MPa, by raising the power. Thirdly, line-switching from recirculation mode to once-through direct-cycle is performed while turbines are started by supercritical steam at supercritical pressure. Finally the power is raised to be 100% of power followed by raising the flow rate. During pressurization the heat flux margin is large due to low power used for pressurization and the MCST is much lower than the criterion. The MCST is not sensitive to the inlet temperature, the flow rate, and the gap volume of the core because of high flow to power ratio. Smaller dimension of steam drum can be used for pressurization stably. The MCST satisfies the criterion both during subcritical pressure and during power-raising

351

Fast and wide-band response infrared detector using porous PZT pyroelectric thick film  

Science.gov (United States)

Porous lead zirconate titanate (PbZr0.3Ti0.7O3, PZT30/70) thick films and detectors for pyroelectric applications have been fabricated on alumina substrates by screen-printing technology. Low temperature sintering of PZT thick films have been achieved at 850 °C by using Li2CO3 and Bi2O3 sintering aids. The microstructure of PZT thick film has been investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The dielectric properties were measured using HP 4284 at 1 kHz under 25 °C. The permittivity and loss tangent of the thick films were 94 and 0.017, respectively. Curie temperature of PZT thick film was 425 °C as revealed by dielectric constant temperature measurement. The pyroelectric coefficient was determined to be 0.9 × 10-8 Ccm-2 K-1 by dynamic current measurement. Infrared detector sensitive element of dual capacitance was fabricated by laser directly write technology. Detectivity of the detectors were measured using mechanically chopped blackbody radiation. Detectivity ranging from 1.23 × 108 to 1.75 × 108 (cm Hz1/2 W-1) was derived at frequency range from 175.5 Hz to 1367 Hz, and D*'s -3 dB cut-off frequency bandwidth was 1.2 kHz. The results indicate that the infrared detectors based on porous thick films have great potential applications in fast and wide-band frequency response conditions.

Wu, C. G.; Sun, X. Y.; Meng, J.; Luo, W. B.; Li, P.; Peng, Q. X.; Luo, Y. S.; Shuai, Y.

2014-03-01

352

Adaptive Responses to Prochloraz Exposure That Alter Dose-Response and Time-Course Behaviors  

Science.gov (United States)

Dose response and time-course (DRTC) are, along with exposure, the major determinants of health risk. Adaptive changes within exposed organisms in response to environmental stress are common, and alter DRTC behaviors to minimize the effects caused by stressors. In this project, ...

353

Modeling the viscoplastic micromechanical response of two-phase materials using fast Fourier transforms  

Energy Technology Data Exchange (ETDEWEB)

A viscoplastic approach using the Fast Fourier Transform (FFT) method for obtaining local mechanical response is utilized to study microstructure-property relationships in composite materials. Specifically, three-dimensional, two-phase digital materials containing isotropically coarsened particles surrounded by a matrix phase, generated through a Kinetic Monte Carlo Potts model for Ostwald ripening, are used as instantiations in order to calculate the stress and strain rate fields under uniaxial tension. The effects of the morphology of the matrix phase, the volume fraction and the contiguity of particles, and the polycrystallinity of matrix phase, on the stress and strain rate fields under uniaxial tension are examined. It is found that the first moments of the stress and strain rate fields have a different dependence on the particle volume fraction and the particle contiguity from their second moments. The average stresses and average strain rates of both phases and of the overall composite have rather simple relationships with the particle volume fraction whereas their standard deviations vary strongly, especially when the particle volume fraction is high, and the contiguity of particles has a noticeable effect on the mechanical response. It is also found that the shape of stress distribution in the BCC hard particle phase evolves as the volume fraction of particles in the composite varies, such that it agrees with the stress field in the BCC polycrystal as the volume of particles approaches unity. Finally, it is observed that the stress and strain rate fields in the microstructures with a polycrystalline matrix are less sensitive to changes in volume fraction and contiguity of particles.

Lebensohn, Ricardo A [Los Alamos National Laboratory; Lee, Sukbin [CMU; Rollett, Anthony D [CMU

2009-01-01

354

Time response of protection in event of vacuum failure based on Nude ionization gauge controller  

Science.gov (United States)

This article describes the design and application of fast-response vacuum protection sensor module, based on the Nude ionization gauge and a homemade controller named GH07X. A simulative test indicated that the controller's response time was less than 200 ?s when 1 atm air rushed into the vacuum system through a pulsed valve with 0.8 mm orifice nozzle and the emitting current of the Nude gauge was 4 mA. The experiment result showed that the response time mainly depended on the gas density as well as the electron emitting current of the Nude gauge filament. Compared with the vacuum protection sensors based on sputter ion pump and cold-cathode gauge, GH07X is faster and reliable besides, GH07X can be used as an ultrahigh-vacuum slow valve interlock controller with response time of 100 ms, which is faster than other gauge controllers. The widely used field-bus interface CAN and common serial interface RS232/RS485 are embedded in GH07X controller system.

Gao, Hui; Wang, Qiuping; Wang, Weibin; Wu, Qinglin; Chen, Wentong; Sheng, Liusi; Zhang, Yunwu

2001-10-01

355

ULTRAFAST DEPHASING TIME MEASUREMENT IN CRESYL FAST VIOLET DOPED CELLULOSE BY PHOTON ECHOES WITH TEMPORALLY INCOHERENT LIGHT  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Photon echoes with broad spectrum nanosecond laser pulses have been used to measure a femtosecond dephasing time (homogeneous transverse relaxation time) T2 of the S0?1 transition of Cresyl Fast Violet molecules in a cellulose film. The measured T2 was much shorter at a shorter wavelength 5940A than that at a longer wavelength 6250A near the band edge.

Nakatsuka, H.; Fujiwara, M.; Kuroda, R.

1985-01-01

356

Time resolved mass flow measurements for a fast gas delivery system  

International Nuclear Information System (INIS)

A technique is demonstrated whereby the delivered mass and flow rate vs. time of a short rise time gas delivery system may be accurately determined. The gas mass M which flows past a point in a gas delivery system by an arbitrary time t may be accurately measured if that point is sealed off within a time interval short compared to the mass flow time scale. If the ejected mass is allowed to equilibrate in a known volume after being cut off from its source, a conventional static pressure measurement before and after injection, and application of the ideal gas law suffices. Assuming reproducibility, a time history M(t) may be generated, allowing the flow rate vs. time dM(t)/dt to be determined. Mass flow measurements are presented for a fast delivery system in which the flow of argon through a 3.2 mm I.D., 0.76 mm thick copper tube is cut off by imploding (? pinching) the tube using a single turn tungsten magnetic field coil. Pinch discharge parameters are 44 ?f, 20 kV, 47 nH, 3.5 m?, 584 kA, and 8.63 ps current period. Optical measurements of the tube's internal area vs. time indicate that the tube is sealed 2 ps from the time the tube is still 90% open (7 ?s from the start of pinch current). The pinch delay is varied from 500--1,500 ps from the valve trigger (0--1,000 ps from the start of gas flow). The mass injected into the test volume is ? 100 ?g during this interval. The leak rate of the sealed tube results in a mass increase of only ? 0.1 ?g by the time se of only ? 0.1 ?g by the time the pressure gauge stabilizes (6 s). Results are correlated with piezoelectric probe measurements of the gas flow and 2-D axisymmetric numerical simulations of the ? pinch process. Simulations of a ? pinch suitable for characterizing an annular supersonic nozzle typical of those used in gas puff z pinches are discussed

357

Study of Fast Pulsars Using Continuous Time Tagged Events from the GBM Detectors  

Science.gov (United States)

The time tagged event (TTE) data from the Gamma-ray Burst Monitor (GBM) onboard the Fermi Gamma-ray Space Telescope have excellent time resolution of 2 usec. Untriggered TTE data from the 12 Sodium Iodide (NaI which operate in the gamma-ray energy range: 10-1000 keV) and 2 Bismuth Germanate (BGO which operate in the gamma-ray energy range: 0.15-40 MeV) detectors have been produced since July 2010. These are being generated only within pre-defined boxes in the Fermi orbit, which are designed for the study of Terrestrial Gamma-ray Flashes (TGF). Using these data we obtain pulse profiles for the Crab pulsar by the well known epoch folding technique. The phasogram exhibits both the main and the inter-pulse as expected. Our sensitivity calculations show that we may be able to produce similar pulse profiles for weaker fast pulsars like the Vela pulsar and Geminga using the continuous TTE data. We need to integrate the data over longer ( 106 s) exposure times in order detect weaker signals from these pulsars. This would entail the production of TTE data continuously through out the orbit. The measurement of pulsed fluxes from these pulsars in the GBM energy range will enhance the Science capability of Fermi. In addition, we can also search for untriggered weak GRBs as well as other galactic transients and investigate their location and spectral information.

Bhat, Narayana P.; Finger, M. H.; Jenke, P. A.; Camero-Arranz, A.; Wilson-Hodge, C. A.; Briggs, M. S.

2012-01-01

358

A real-time fast radio burst: polarization detection and multiwavelength follow-up  

Science.gov (United States)

Fast radio bursts (FRBs) are one of the most tantalizing mysteries of the radio sky; their progenitors and origins remain unknown and until now no rapid multiwavelength follow-up of an FRB has been possible. New instrumentation has decreased the time between observation and discovery from years to seconds, and enables polarimetry to be performed on FRBs for the first time. We have discovered an FRB (FRB 140514) in real-time on 2014 May 14 at 17:14:11.06 UTC at the Parkes radio telescope and triggered follow-up at other wavelengths within hours of the event. FRB 140514 was found with a dispersion measure (DM) of 562.7(6) cm-3 pc, giving an upper limit on source redshift of z ? 0.5. FRB 140514 was found to be 21 ± 7 per cent (3?) circularly polarized on the leading edge with a 1? upper limit on linear polarization radio wavelengths was unable to identify a variable multiwavelength counterpart, allowing us to rule out models in which FRBs originate from nearby (z < 0.3) supernovae and long duration gamma-ray bursts.

Petroff, E.; Bailes, M.; Barr, E. D.; Barsdell, B. R.; Bhat, N. D. R.; Bian, F.; Burke-Spolaor, S.; Caleb, M.; Champion, D.; Chandra, P.; Da Costa, G.; Delvaux, C.; Flynn, C.; Gehrels, N.; Greiner, J.; Jameson, A.; Johnston, S.; Kasliwal, M. M.; Keane, E. F.; Keller, S.; Kocz, J.; Kramer, M.; Leloudas, G.; Malesani, D.; Mulchaey, J. S.; Ng, C.; Ofek, E. O.; Perley, D. A.; Possenti, A.; Schmidt, B. P.; Shen, Yue; Stappers, B.; Tisserand, P.; van Straten, W.; Wolf, C.

2015-02-01

359

A real-time fast radio burst: polarization detection and multiwavelength follow-up  

CERN Document Server

Fast radio bursts (FRBs) are one of the most tantalizing mysteries of the radio sky; their progenitors and origins remain unknown and until now no rapid multiwavelength follow-up of an FRB has been possible. New instrumentation has decreased the time between observation and discovery from years to seconds, and enables polarimetry to be performed on FRBs for the first time. We have discovered an FRB (FRB 140514) in real-time on 14 May, 2014 at 17:14:11.06 UTC at the Parkes radio telescope and triggered follow-up at other wavelengths within hours of the event. FRB 140514 was found with a dispersion measure (DM) of 562.7(6) cm$^{-3}$ pc, giving an upper limit on source redshift of $z \\lesssim 0.5$. FRB 140514 was found to be 21$\\pm$7% (3-$\\sigma$) circularly polarized on the leading edge with a 1-$\\sigma$ upper limit on linear polarization $<10%$. We conclude that this polarization is intrinsic to the FRB. If there was any intrinsic linear polarization, as might be expected from coherent emission, then it may...

Petroff, E; Barr, E D; Barsdell, B R; Bhat, N D R; Bian, F; Burke-Spolaor, S; Caleb, M; Champion, D; Chandra, P; Da Costa, G; Delvaux, C; Flynn, C; Gehrels, N; Greiner, J; Jameson, A; Johnston, S; Kasliwal, M M; Keane, E F; Keller, S; Kocz, J; Kramer, M; Leloudas, G; Malesani, D; Mulchaey, J S; Ng, C; Ofek, E O; Perley, D A; Possenti, A; Schmidt, B P; Shen, Yue; Stappers, B; Tisserand, P; van Straten, W; Wolf, C

2014-01-01

360

Multi-purpose fast neutron spectrum analyzer with real-time signal processing  

International Nuclear Information System (INIS)

Diagnostics of hot ion component of plasma on the products of fusion reactions is widely used on thermonuclear facilities. In case of employment of neutron spectrometers, based on organics scintillators, there is advanced technique developed to eliminate neutron pulses from gamma background—digital pulse shape discrimination. For every DPSD application it is necessary to use the fast (2–5 ns) and precise (12 bit) transient ADC unit with large amount of onboard memory for storing every digitized scintillation pulses during shot time. At present time the duration of hot thermonuclear plasma burning in large tokamaks approximate to 1 min, and this requires very high onboard memory capacity (?100 GB). This paper describes a neutron spectrum analyzer with real-time DPSD algorithm, implemented to ADC unit. This approach saves about two orders of onboard memory capacity, gives the possibility of instant use of outcome to feedback systems. This analyzer was tested and calibrated with help of 60Co and 252Cf radiation sources, and deuterium neutron generator

 
 
 
 
361

Malignant glioma - timing of response to radiation therapy  

International Nuclear Information System (INIS)

The response of malignant gliomas to radiation was examined retrospectively in 71 patients with newly diagnosed supratentorial malignant gliomas. Questions asked included frequency, timing and clinical significance of response. After surgery, all were treated with whole brain plus boost radiotherapy followed 8 weeks later by chemotherapy. The rate, degree, and timing of response to radiation were determined by comparing postoperative, end of radiation, and prechemotherapy CT scans on each patient. Postoperative residual tumor was evident on 63/71 postoperative scans. Twenty-two of 63 tumors (35%) had a partial or complete response to radiation. Twenty (32%) had responded by the end of radiation; 17 maximally. Six to 8 weeks later, three responding tumors had responded further and two previously stable ones had begun to respond. Only three tumors (5%) responded completely. A greater proportion of anaplastic gliomas than glioblastomas responded to radiation (52% vs. 26%). Protracted or delayed responses were only observed in patients with anaplastic glioma. Patients who responded to radiation did not live significantly longer than non-responders. However, tumor progression prior to chemotherapy was associated with significantly shorter survival. This CT scan-based analysis demonstrates that malignant gliomas are only moderately radioresponsive tumors and also demonstrates that response to radiation, if it is going to occur, is usually evident by the end of treatment. 6 sually evident by the end of treatment. 6 refs., 1 fig., 1 tab

362

Fast response organic light-emitting diode for visible optical communication  

Science.gov (United States)

We examined fast response organic light-emitting diodes (OLEDs) for new applications of visible optical communications. For the practical use in this field, the fast transmission speed of OLEDs is required to be used in many applications, but the low carrier mobility of organic materials and the long fluorescence lifetime (FL) organic emitting materials limit the transmission speed of OLEDs. Therefore, we investigated the influence of the FL on transient properties of photoluminescence (PL), which were evaluated by the frequency dependence of PL intensity excited by a modulated violet laser diode. The FLs of several organic emitting materials were also measured, and we found the clear relationship between the FL and the transient properties of PL intensity. The fastest cutoff frequency of PL intensity was achieved 160 MHz utilizing short FL material, 1,4-bis[2-[4-[N,N-di(ptolyl)amino]phenl]vinyl]benzene. We also investigated another way to increase the transmission speed utilizing a semiconductor-organic multilayer structure, of which ZnS was used as an electron transport layer. The maximum cutoff frequency of this device was achieved 20.3 MHz, while that of the organic multilayer structure was 8.7 MHz at a sine wave voltage of 7 V and a bias voltage of 5 V. This result indicates that the high carrier mobility of the ZnS layer causes the increase in the transmission speed of OLEDs. We demonstrated one institutive demonstrator module of visible optical communications, which consisted of the transceiver module with an OLED and the pen-type receiver module with a photo-diode at a point. The movie files was transmitted at a speed of 230 kbps, when the point of a pen-type receiver module approaches the emitting area of an OLED. Furthermore, the pseudo-random signal with 1Mbps was also transmitted with this visible optical communication system. Such a system enables to connect between transceiver and receiver module without precious alignment because of the large emitting area of OLEDs. So, we think that many people, from children to aged people, are easy to get information from OLEDs without being aware of using optical communications. Furthermore, the communication field is limited near the emitting area of an OLED, resulting in a safe data transmission.

Fukuda, Takeshi; Taniguchi, Yoshio

2008-02-01

363

The looks of an odour - Visualising neural odour response patterns in real time  

Science.gov (United States)

Background Calcium imaging in insects reveals the neural response to odours, both at the receptor level on the antenna and in the antennal lobe, the first stage of olfactory information processing in the brain. Changes of intracellular calcium concentration in response to odour presentations can be observed by employing calcium-sensitive, fluorescent dyes. The response pattern across all recorded units is characteristic for the odour. Method Previously, extraction of odour response patterns from calcium imaging movies was performed offline, after the experiment. We developed software to extract and to visualise odour response patterns in real time. An adaptive algorithm in combination with an implementation for the graphics processing unit enables fast processing of movie streams. Relying on correlations between pixels in the temporal domain, the calcium imaging movie can be segmented into regions that correspond to the neural units. Results We applied our software to calcium imaging data recorded from the antennal lobe of the honeybee Apis mellifera and from the antenna of the fruit fly Drosophila melanogaster. Evaluation on reference data showed results comparable to those obtained by previous offline methods while computation time was significantly lower. Demonstrating practical applicability, we employed the software in a real-time experiment, performing segmentation of glomeruli - the functional units of the honeybee antennal lobe - and visualisation of glomerular activity patterns. Conclusions Real-time visualisation of odour response patterns expands the experimental repertoire targeted at understanding information processing in the honeybee antennal lobe. In interactive experiments, glomeruli can be selected for manipulation based on their present or past activity, or based on their anatomical position. Apart from supporting neurobiology, the software allows for utilising the insect antenna as a chemosensor, e.g. to detect or to classify odours. PMID:24564474

2013-01-01

364

A neutron detector with a flat energy response for use in time-of-flight experiments  

International Nuclear Information System (INIS)

Monte-Carlo calculations have been carried out to assess the feasibility of making a neutron detector suitable for time-of-flight work whose efficiency can be accurately predicted (?±2%) ideally over the energy region 100eV ? several MeV. Accurate flux measurements are needed in this region to determine partial neutron cross-sections for use in fast-reactor design. The detector was taken to be a spherical homogeneous mixture of 10B and vaseline with a radial re-entrant hole to allow a parallel neutron beam to fall near the sphere centre. Neutrons are moderated and captured in the 10B to produce 478-keV ?-rays in the reaction 10B(n, ?)7Li*, ?7Li which are detected at the surface of the sphere in Nal scintillation counters. On the basis of the calculations a 12 cm radius counter has been built containing ?1 kg 10B with a re-entrant hole 8 cm deep and 2.5 cm diameter. The counter is predicted to have an efficiency which is flat within 4% between 100 eV and 700 keV. The time response is such that an incident fast neutron has a probability of 0.99 of being captured within 0.67 ?s. Measurements are being carried out on a 300 m flight path of the Harwell 45 MeV electron linac to test the theoretical predictions. If these are successful the flat response detector will be used as a standard for calibrating the counters actually used for flux determination in fast neutron partial cross-section measurem partial cross-section measurements. The measured characteristics of the detector will be presented and compared with the theoretical predictions. (author)

365

In situ response time measurements of RTD temperature sensors  

International Nuclear Information System (INIS)

The loop-current-step-response test provides a mean for determining the time constant of resistence thermometers. The test consist in heating the sensor a few degrees above ambient temperature by causing a step pertubation in the electric current that flows through the sensor leads. The developed mathematical transformation permits to use data collected during the internal heating transient to predict the sensor response to perturbations in fluid temperature. Experimental data obtained show that the time constant determined by method is within 15 percent of true value. The loop-current-step-response test is a remote in situ test, which can be performed with the sensor installed in the process. Consequently it takes account the local heat transfer conditions, and appropriated for nuclear power plants, where sensors are installed in points of difficult access. (author)

366

Pace: An Alternative Measure of Student Question Response Time  

Science.gov (United States)

In some professions, speed and accuracy are as important as acquired requisite knowledge and skills. The availability of computer-based testing now facilitates examination of these two important aspects of student performance. We found that student response times in a conventional non-speeded multiple-choice test, at both the global and individual…

Thompson, James J.; Yang, Tong; Chauvin, Sheila W.

2009-01-01

367

Separability of Item and Person Parameters in Response Time Models.  

Science.gov (United States)

Discusses two forms of separability of item and person parameters in the context of response time models. The first is "separate sufficiency," and the second is "ranking independence." For each form a theorem stating sufficient conditions is proved. The two forms are shown to include several cases of models from psychometric and biometric…

Van Breukelen, Gerard J. P.

1997-01-01

368

Are Unshifted Distributional Models Appropriate for Response Time?  

Science.gov (United States)

Van Breukelen (this issue) provides an approach to using both response time (RT) and accuracy for (1) measuring latent abilities of participants even when they may trade speed for accuracy, and for (2) providing insight into the psychological processes underlying task performance. In this commentary, I focus on the second of these aims and assess…

Rouder, Jeffrey N.

2005-01-01

369

Fast responsive fluorescence turn-on sensor for Cu2+ and its application in live cell imaging  

International Nuclear Information System (INIS)

A new effective fluorescent sensor based on rhodamine was synthesized, which was induced by Cu2+ in aqueous media to produce turn-on fluorescence. The new sensor 1 exhibited good selectivity for Cu2+ over other heavy and transition metal (HTM) ions in H2O/CH3CN(7:3, v/v). Upon addition of Cu2+, a remarkable color change from colorless to pink was easily observed by the naked eye, and the dramatic fluorescence turn-on was corroborated. Furthermore, kinetic assay indicates that sensor 1 could be used for real-time tracking of Cu2+ in cells and organisms. In addition, the turn-on fluorescent change upon the addition of Cu2+ was also applied in bioimaging. - Highlights: ? A new effective fluorescent sensor based on rhodamine was developed to detect Cu2+. ? The sensor exhibited fast response, good selectivity at physiological pH condition. ? The sensor was an effective intracellular Cu2+ ion imaging agent.

370

Fast Direct Injection Mass-Spectrometric Characterization of Stimuli for Insect Electrophysiology by Proton Transfer Reaction-Time of Flight Mass-Spectrometry (PTR-ToF-MS  

Directory of Open Access Journals (Sweden)

Full Text Available Electrophysiological techniques are used in insect neuroscience to measure the response of olfactory neurons to volatile odour stimuli. Widely used systems to deliver an olfactory stimulus to a test insect include airstream guided flow through glass cartridges loaded with a given volatile compound on a sorbent support. Precise measurement of the quantity of compound reaching the sensory organ of the test organism is an urgent task in insect electrophysiology. In this study we evaluated the performances of the recent realised proton transfer reaction-time of flight mass-spectrometry (PTR-ToF-MS as a fast and selective gas sensor. In particular, we characterised the gas emission from cartridges loaded with a set of volatile compounds belonging to different chemical classes and commonly used in electrophysiological experiments. PTR-ToF-MS allowed a fast monitoring of all investigated compounds with sufficient sensitivity and time resolution. The detection and the quantification of air contaminants and solvent or synthetic standards impurities allowed a precise quantification of the stimulus exiting the cartridge. The outcome of this study was twofold: on one hand we showed that PTR-ToF-MS allows monitoring fast processes with high sensitivity by real time detection of a broad number of compounds; on the other hand we provided a tool to solve an important issue in insect electrophysiology.

Franco Biasioli

2012-03-01

371

Surface layer characteristics derived from fast-response micrometeorological observations over a mountain peak in the central Himalayas  

Science.gov (United States)

Diurnal evolution of atmospheric boundary layer over hilly terrains is highly complex and least understood. Fast-response micrometeorological observations carried out at Manora Peak, Nainital (29.2°N, 79.3°E, 1960 m ASL), a hill station located in the Central Himalayas during March-2013 to February-2014 has been used to investigate diurnal variations in the surface layer characteristics, energy budget and atmospheric circulation over complex terrains. This study mainly employs tower-based sonic anemometer observations (25 Hz) carried out at two levels (12 m and 27 m above the ground level) which are used to derive the variations of zonal, meridional and vertical winds, virtual temperature, momentum flux, turbulent kinetic energy, and Monin-Obukhov stability parameter during fair-weather conditions. In general, this station is manifested by warm and dry conditions as well as relatively high wind speed during pre-monsoon season (March-May); while highly moist conditions prevail during the summer monsoon season (June-September). The sensible heat flux (SHF) undergoes a prominent diurnal variation during winter and pre-monsoon seasons with peak values (200 to 400 Wm-2) occurring between 11-15 Local Time (LT) and weakly negative values (typically -20 Wm-2) during night, the latter indicating a downward transfer of heat from atmosphere to surface. The noon-time peak values systematically increases from winter to pre-monsoon season. Remarkably, the large noon-time values of SHF observed during the pre-monsoon season over this station (peak SHF of more than 400 Wm-2 during May) arise from the forced lifting of air masses, caused by the prevailing horizontal winds that blow perpendicular to the mountain. The intricate details of the surface layer parameters and fluxes over this site will assist in investigating how such a complex topography influences the flux generation process.

Solanki, Raman; Dhaka, Surendra; Rajeev, Kunjukrishnapillai; Singh, Narendra; Nadimpally, Kirankumar

372

Using random response input in Ibrahim Time Domain  

DEFF Research Database (Denmark)

In this paper the time domain technique Ibrahim Time Domain (ITD) is used to analyze random time data. ITD is known to be a technique for identification of output only systems. The traditional formulation of ITD is claimed to be limited, when identifying closely spaced modes, because of the technique being Single Input Multiple Output (SIMO). It has earlier been showed that when modifying ITD with Toeplitz matrix averaging. Identification of time data with closely spaced modes is improved. In the traditional formulation of ITD the time data has to be free decays or impulse response functions. In this article it is showed that when using the modified ITD random time data can be analyzed. The application of the technique is displayed by a case study, with simulations and experimental data.

Olsen, Peter; Brincker, R.

2013-01-01

373

Timing and causality in the generation of learned eyelid responses  

Directory of Open Access Journals (Sweden)

Full Text Available The cerebellum-red nucleus-facial motoneuron (Mn pathway has been reported as being involved in the proper timing of classically conditioned eyelid responses. This special type of associative learning serves as a model of event timing for studying the role of the cerebellum in dynamic motor control. Here, we have re-analyzed the firing activities of cerebellar posterior interpositus (IP neurons and orbicularis oculi (OO Mns in alert behaving cats during classical eyeblink conditioning, using a delay paradigm. The aim was to revisit the hypothesis that the IP neurons can be considered a neuronal phase-modulating device supporting OO Mns firing with an emergent timing mechanism and an explicit correlation code during learned eyelid movements. Optimized experimental and computational tools allowed us to determine the different causal relationships (temporal order and correlation code during and between trials. These intra- and inter-trial timing strategies expanding from sub-second range (millisecond timing to longer-lasting ranges (interval timing expanded the functional domain of cerebellar timing beyond motor control. Interestingly, the results supported the above-mentioned hypothesis. The causal inferences were influenced by the precise motor and premotor spike-timing in the cause-effect interval, and, in addition, the timing of the learned responses depended on cerebellar-Mn network causality. Furthermore, the timing of CRs depended upon the probability of simulated causal conditions in the cause-effect interval and not the mere duration of the inter-stimulus interval. In this work, the close relation between timing and causality was verified. It could thus be concluded that the firing activities of IP neurons may be related more to the proper performance of ongoing CRs (i.e., the proper timing as a consequence of the pertinent causality than to their generation and/or initiation.

RaudelSánchez-Campusano

2011-08-01

374

Fast and slow timescales in the tropical low-cloud response to increasing CO{sub 2} in two climate models  

Energy Technology Data Exchange (ETDEWEB)

To obtain physical insights into the response and feedback of low clouds (C{sub l}) to global warming, ensemble 4 x CO{sub 2} experiments were carried out with two climate models, the Model for Interdisciplinary Research on Climate (MIROC) versions 3.2 and 5. For quadrupling CO{sub 2}, tropical-mean C{sub l} decreases, and hence, acts as positive feedback in MIROC3, whereas it increases and serves as negative feedback in MIROC5. Three time scales of tropical-mean C{sub l} change were identified - an initial adjustment without change in the global-mean surface air temperature, a slow response emerging after 10-20 years, and a fast response in between. The two models share common features for the former two changes in which C{sub l} decreases. The slow response reflects the variability of C{sub l} associated with the El Nino-Southern Oscillation in the control integration, and may therefore be constrained by observations. However, the fast response is opposite in the two models and dominates the total response of C{sub l}. Its sign is determined by a subtle residual of the C{sub l} increase and decrease over the ascending and subsidence regions, respectively. The regional C{sub l} increase is consistent with a more frequent occurrence of a stable condition, and vice versa, as measured by lower-tropospheric stability (LTS). The above frequency change in LTS is similarly found in six other climate models despite a large difference in both the mean and the changes in the low-cloud fraction for a given LTS. This suggests that the response of the thermodynamic constraint for C{sub l} to increasing CO{sub 2} concentrations is a robust part of the climate change. (orig.)

Watanabe, Masahiro; Yoshimori, Masakazu; Kimoto, Masahide [The University of Tokyo, Atmosphere and Ocean Research Institute, Chiba (Japan); Shiogama, Hideo; Ogura, Tomoo; Yokohata, Tokuta [National Institute for Environmental Studies, Tsukuba (Japan); Okamoto, Hajime [Kyushu University, Research Institute for Applied Mechanics, Fukuoka (Japan); Emori, Seita [The University of Tokyo, Atmosphere and Ocean Research Institute, Chiba (Japan); National Institute for Environmental Studies, Tsukuba (Japan)

2012-10-15

375

EVALUATION OF A FAST-RESPONSE URBAN WIND MODEL - COMPARISON TO SINGLE-BUILDING WIND TUNNEL DATA  

International Nuclear Information System (INIS)

Prediction of the 3-dimensional flow field around buildings and other obstacles is important for a number of applications, including urban air quality studies, the tracking of plumes from accidental releases of toxic air contaminants, indoor/outdoor air pollution problems, and thermal comfort assessments. Various types of computational fluid dynamics (CFD) models have been used for determining the flow fields around buildings (e.g., Reisner et al., 1998; Eichhorn et al., 1988). Comparisons to measurements show that these models work reasonably well for the most part (e.g., Ehrhard et al., 2 ; Johnson and Hunter, 1998; Murakami, 1997). However, CFD models are computationally intensive and for some applications turn-around time is of the essence. For example, planning and assessment studies in which hundreds of cases must be analyzed or emergency response scenarios in which plume transport must be computed quickly. Several fast-response dispersion models of varying levels of fidelity have been developed to explicitly account for the effects of a single building or groups of buildings (e.g., UDM - Hall et al. (2000), NRC-Ramsdell and Fosmire (1995), CBP-3 - Yamartino and Wiegand (1986), APRAC - Daerdt et al. (1973)). Although a few of these models include the Hotchkiss and Harlow (1973) analytical solution for potential flow in a notch to describe the velocity field within an urban canyon, in general, these models do not explicitly compute the velocity field around grouply compute the velocity field around groups of buildings. The EPA PRIME model (Schulman et al., 2000) has been empirically derived to provide streamlines around a single isolated building

376

Computationally Efficient Partial Crosstalk Cancellation in Fast Time-Varying DSL Crosstalk Environments  

Directory of Open Access Journals (Sweden)

Full Text Available Line selection (LS, tone selection (TS, and joint tone-line selection (JTLS partial crosstalk cancellers have been proposed to reduce the online computational complexity of far-end crosstalk (FEXT cancellers in digital subscriber lines (DSL. However, when the crosstalk profile changes rapidly over time, there is an additional requirement that the partial crosstalk cancellers, particularly the LS and JTLS schemes, should also provide a low preprocessing complexity. This is in contrast to the case for perfect crosstalk cancellers. In this paper, we propose two novel channel matrix inversion methods, the approximate inverse (AI and reduced inverse (RI schemes, which reduce the recurrent complexity of the LS and JTLS schemes. Moreover, we propose two new classes of JTLS algorithms, the subsort and Lagrange JTLS algorithms, with significantly lower computational complexity than the recently proposed optimal greedy JTLS scheme. The computational complexity analysis of our algorithms shows that they provide much lower recurrent complexities than the greedy JTLS algorithm, allowing them to work efficiently in very fast time-varying crosstalk environments. Moreover, the analytical and simulation results demonstrate that our techniques are close to the optimal solution from the crosstalk cancellation point of view. The results also reveal that partial crosstalk cancellation is more beneficial in upstream DSL, particularly for short loops.

Forouzan Amir R

2007-01-01

377

Timing and Fast Control and Readout Electronics Aspects of the LHCb Upgrade  

CERN Document Server

LHCb is considering an upgrade towards a full 40 MHz readout [1], possibly in several stages implying that a rudimentary rate control will still be needed. The rate control could be achieved by either maintaining the current L0 trigger infrastructure since it is already operating at 40MHz, or implementing simple local trigger decisions units in the new Readout Boards and control the rate via an 'intelligent' throttle mechanism. In this paper we make a first investigation of the possibilities for a new Timing and Fast Control (TFC) system based on completely new technologies, and the consequences for the readout electronics. We examine the current TFC, define the requirements for a new TFC, and propose a TFC architecture based on a single new Readout Supervisor 'Super-ODIN' instantiating several TFC masters to allow partitioning, and based on a shared high-speed optical link network for both the distribution of timing and synchronous control information, as well as trigger/throttle communication. The TFC inter...

Alessio, F; Jacobsson, R

2008-01-01

378

Fast Time-Domain Edge-Diffraction Calculations for Interactive Acoustic Simulations  

Directory of Open Access Journals (Sweden)

Full Text Available The inclusion of edge diffraction has long been recognized as an improvement to geometrical-acoustics (GA modeling techniques, particularly for acoustic simulations of complex environments that are represented as collections of finite-sized planar surfaces. One particular benefit of combining edge diffraction with GA components is that the resulting total sound field is continuous when an acoustic source or receiver crosses a specular-zone or shadow-zone boundary, despite the discontinuity experienced by the associated GA component. In interactive acoustic simulations which include only GA components, such discontinuities may be heard as clicks or other undesirable audible artifacts, and thus diffraction calculations are important for high perceptual quality as well as physical realism. While exact diffraction calculations are difficult to compute at interactive rates, approximate calculations are possible and sufficient for situations in which the ultimate goal is a perceptually plausible simulation rather than a numerically exact one. In this paper, we describe an edge-subdivision strategy that allows for fast time-domain edge-diffraction calculations with relatively low error when compared with results from a more numerically accurate solution. The tradeoff between computation time and accuracy can be controlled with a number of parameters, allowing the user to choose the speed that is necessary and the error that is tolerable for a specific modeling scenario.

U. Peter Svensson

2007-01-01

379

Time resolved measurement of FEL micropulses using fast hot electron bolometers  

International Nuclear Information System (INIS)

Radiation at 3THz or light of a 100?m wavelength generated with the THz-FEL at the Institute of Scientific and Industrial Research (ISIR), Osaka University is measured using two superconducting hot-electron bolometers (SHEB); one with a NbN (normal superconductor) detector and the other a YBCO (YBa2Cu3O7, high temperature superconductor) detector. Both detectors are fast enough to separately measure FEL micropulse at interval of 9.2 ns, which comprise four families of independent FEL micropulses. The single-shot time spectra, however, include significant amplitude noises compared to signals and hence it is difficult to analyze these spectra quantitatively. We try some kinds of numerical methods to reduce noises of the spectra measured with the YBCO detector and find the so-called MMSE-STSA (Minimum Mean-Square Error Short-Time Spectral Amplitude Estimator) method can significantly reduce effects of the noises. As a result, it is experimentally shown that four families of FEL micropulses develop independently and differently in the power saturation region. (author)

380

Predicting Aquifer Response Time for Application in Catchment Modeling.  

Science.gov (United States)

It is well established that changes in catchment land use can lead to significant impacts on water resources. Where land-use changes increase evapotranspiration there is a resultant decrease in groundwater recharge, which in turn decreases groundwater discharge to streams. The response time of changes in groundwater discharge to a change in recharge is a key aspect of predicting impacts of land-use change on catchment water yield. Predicting these impacts across the large catchments relevant to water resource planning can require the estimation of groundwater response times from hundreds of aquifers. At this scale, detailed site-specific measured data are often absent, and available spatial data are limited. While numerical models can be applied, there is little advantage if there are no detailed data to parameterize them. Simple analytical methods are useful in this situation, as they allow the variability in groundwater response to be incorporated into catchment hydrological models, with minimal modeling overhead. This paper describes an analytical model which has been developed to capture some of the features of real, sloping aquifer systems. The derived groundwater response timescale can be used to parameterize a groundwater discharge function, allowing groundwater response to be predicted in relation to different broad catchment characteristics at a level of complexity which matches the available data. The results from the analytical model are compared to published field data and numerical model results, and provide an approach with broad application to inform water resource planning in other large, data-scarce catchments. PMID:24842053

Walker, Glen R; Gilfedder, Mat; Dawes, Warrick R; Rassam, David W

2014-05-19

 
 
 
 
381

Response Of TLD-600 to Continue And Discrete Fast Neutron Doses Irradiation  

International Nuclear Information System (INIS)

Irradiation to three groups of TLD-600 with fast neutron dose from AmBe source have been carried out. Each group consist of 20 TLD cards. First and second group were irradiated continually by doses vary from 50, 100, 250, 500 and 750 mrem. For each dose value of each group was irradiated four TLD card. The third group was irradiated by total dose same to the first group, but the dose was delivered discreetly 13 times during three months. TL intensity of first group (A) were read directly after irradiation, and TL intensity of second group (B) and third group (C) were read after irradiation of third group finished. Irradiation of first and second group were same to the condition of irradiation during TLD calibration in Laboratory. The different between those two group are there is not fading of TL. intensity on first group and fading during three months on second group. Irradiation of third group was assumed same to the condition of irradiation when TLD was used for personal dose monitoring. From the calculation of comparison value of TL intensity for several condition of irradiation it was obtained the quotient value of B/A, C/A and C/B were: 0.93, 0.92 and 0.99 respectively. Such data shows the necessity of fading correction of eight percent during neutron dose evaluation using TLD-600

382

High-Voltage Power Supply With Fast Rise and Fall Times  

Science.gov (United States)

A special-purpose high-voltage power supply can be electronically switched on and off with fast rise and fall times, respectively. The output potential is programmable from 20 to 1,250 V. An output current of 50 A can be sustained at 1,250 V. The power supply was designed specifically for electronically shuttering a microchannel plate in an x-ray detector that must operate with exposure times as short as 1 ms. The basic design of the power supply is also adaptable to other applications in which there are requirements for rapid slewing of high voltages. The power-supply circuitry (see figure) includes a preregulator, which is used to program the output at 1/30 of the desired output potential. After the desired voltage has been set, the outputs of a pulse width modulator (PWM) are enabled and used to amplify the preregulator output potential by 30. The amplification is achieved by use of two voltage doublers with a transformer that has two primary and two secondary windings. A resistor is used to limit the current by controlling the drive voltage of two field-effect transistors (FETs) during turn-on of the PWM. A pulse transformer is used to turn on four FETs to short-circuit four output capacitors when the outputs of the PWM have been disabled. The most notable aspects of the performance of the power supply are a rise time of only 80 s and a fall time of only 60 s at a load current of 50 A or less. Another notable aspect is that the application of a 0-to-5-V square wave to a shutdown pin of the PWM causes the production of a 0-to-1,250-V square wave at the output terminals.

Bearden, Douglas B.; Acker, Richard M.; Kapuslka, Robert E.

2007-01-01

383

Modeling fast electron dynamics with real-time time-dependent density functional theory: application to small molecules and chromophores  

Energy Technology Data Exchange (ETDEWEB)

The response of matter to external fields forms the basis for a vast wealth of fundamental physical processes ranging from light harvesting to nanoscale electron transport. Accurately modeling ultrafast electron dynamics in excited systems thus o_ers unparalleled insight, but requires an inherently non-linear time-resolved approach. To this end, an e_cient and massively parallel real-time real-space time-dependent density functional theory (RT-TDDFT) implementation in NWChem is presented. The implementation is first validated against linearresponse TDDFT and experimental results for a series of molecules subjected to small electric field perturbations. Second, non-linear excitation of green fluorescent protein is studied, which shows a blue-shift in the spectrum with increasing perturbation, as well as a saturation in absorption. Next, the charge dynamics of optically excited zinc porphyrin is presented in real-time and real-space, with relevance to charge injection in photovoltaic devices. Finally, intermolecular excitation in an adenine-thymine base pair is studied using the BNL range separated functional [Baer, R.; Neuhauser, D. Phys. Rev. Lett. 2005, 94, 043002], demonstrating the utility of a real-time approach in capturing charge transfer processes.

Lopata, Kenneth A.; Govind, Niranjan

2011-05-10

384

Instrument response standard in time-resolved fluorescence.  

Science.gov (United States)

The fluorescence of LDS 798 dye in aqueous solution has a very short lifetime of 24 ps, independent of excitation wavelength. The time response of common photon counting detectors depends on the wavelength of the registered photon. In lifetime measurements, the instrument response function (IRF) is usually approximated by the temporal profile of the scattered excitation light. Because lambda(Exc) is typically much shorter than lambda(Em), a systematic error may be present in these measurements. We demonstrate that the fluorescence decay of LDS 798 is a better approximation of IRF, in particular, for avalanche photodiodes used in the near infrared spectral region. PMID:19334909

Luchowski, Rafal; Gryczynski, Zygmunt; Sarkar, Pabak; Borejdo, Julian; Szabelski, Mariusz; Kapusta, Peter; Gryczynski, Ignacy

2009-03-01

385

Fast magnetic response in gigahertz-band for columnar-structured Fe nanoparticle assembly  

Science.gov (United States)

High density Fe-based ferromagnetic nanoparticle (NP) assembly is expected to have unique magnetic properties, such as superferromagnetism and super-spin-glass, different from magnetically isolated NP systems due to strong dipole interactions among the NPs. A high dipole interaction field, Hdip, of ˜3.5 kOe can result in a high effective internal field to the magnetic moment of the NP, expecting for ultra-fast magnetic response, that is, a high magnetic resonance frequency, fr, of ˜10 GHz. However, for a simply molded Fe NP assembly, a low fr was observed due to inhomogeneous distribution of the internal field, implying the necessity of a unidirectional state of Hdip for higher fr. In this study, we fabricated a columnar Fe NP assembly for realizing the unidirectional state of Hdip by applying our uniquely developed external field-induced agglomeration method for monodispersed Fe NPs (13 nm in average size) as a function of the field (0-30 kOe) and volume fraction of the Fe NPs (0.5%-51%) in a polymer matrix with dimensions of 4 mm × 4 mm × 0.7 mmt. A columnar-structured Fe NP assembly was successfully achieved along an in-plane direction (defined as the x-axis) under optimized conditions. From static magnetization curves, induced uniaxial magnetic anisotropy was observed according to the shape of the columnar structure of the Fe NP assembly, where easy and hard axes of magnetization were realized along the parallel (x-axis) and normal directions (in-plane y-axis and z-axis in the thickness direction) to the external field during the process, respectively. Interestingly, this fabricated columnar-structured Fe NP assembly exhibited very high fr in the range from 3 to 11 GHz judging from the complex susceptibility spectra obtained. The fr values were well-scaled by a modified Snoek's-limit-law using demagnetization factors quantitatively estimated from the static magnetization curves. Thus, shape-induced anisotropy originating from the unidirectional state of Hdip in the columnar structure of the Fe NP assembly plays an important role for high frequency magnetic response in the GHz-band.

Ogawa, T.; Kura, H.; Tate, R.; Oikawa, T.; Hata, K.

2014-05-01

386

Fast magnetic response in gigahertz-band for columnar-structured Fe nanoparticle assembly  

International Nuclear Information System (INIS)

High density Fe-based ferromagnetic nanoparticle (NP) assembly is expected to have unique magnetic properties, such as superferromagnetism and super-spin-glass, different from magnetically isolated NP systems due to strong dipole interactions among the NPs. A high dipole interaction field, Hdip, of ?3.5 kOe can result in a high effective internal field to the magnetic moment of the NP, expecting for ultra-fast magnetic response, that is, a high magnetic resonance frequency, fr, of ?10 GHz. However, for a simply molded Fe NP assembly, a low fr was observed due to inhomogeneous distribution of the internal field, implying the necessity of a unidirectional state of Hdip for higher fr. In this study, we fabricated a columnar Fe NP assembly for realizing the unidirectional state of Hdip by applying our uniquely developed external field-induced agglomeration method for monodispersed Fe NPs (13 nm in average size) as a function of the field (0–30 kOe) and volume fraction of the Fe NPs (0.5%–51%) in a polymer matrix with dimensions of 4 mm × 4 mm × 0.7 mmt. A columnar-structured Fe NP assembly was successfully achieved along an in-plane direction (defined as the x-axis) under optimized conditions. From static magnetization curves, induced uniaxial magnetic anisotropy was observed according to the shape of the columnar structure of the Fe NP assembly, where easy and hard axes of magnetization were realized along the parallel (x-axis) and normal directions (in-plane y-axis and z-axis in the thickness direction) to the external field during the process, respectively. Interestingly, this fabricated columnar-structured Fe NP assembly exhibited very high fr in the range from 3 to 11 GHz judging from the complex susceptibility spectra obtained. The fr values were well-scaled by a modified Snoek's-limit-law using demagnetization factors quantitatively estimated from the static magnetization curves. Thus, shape-induced anisotropy originating from the unidirectional state of Hdip in the columnar structure of the Fe NP assembly plays an important role for high frequency magnetic response in the GHz-band

387

Fast magnetic response in gigahertz-band for columnar-structured Fe nanoparticle assembly  

Energy Technology Data Exchange (ETDEWEB)

High density Fe-based ferromagnetic nanoparticle (NP) assembly is expected to have unique magnetic properties, such as superferromagnetism and super-spin-glass, different from magnetically isolated NP systems due to strong dipole interactions among the NPs. A high dipole interaction field, H{sub dip}, of ?3.5 kOe can result in a high effective internal field to the magnetic moment of the NP, expecting for ultra-fast magnetic response, that is, a high magnetic resonance frequency, f{sub r}, of ?10 GHz. However, for a simply molded Fe NP assembly, a low f{sub r} was observed due to inhomogeneous distribution of the internal field, implying the necessity of a unidirectional state of H{sub dip} for higher f{sub r}. In this study, we fabricated a columnar Fe NP assembly for realizing the unidirectional state of H{sub dip} by applying our uniquely developed external field-induced agglomeration method for monodispersed Fe NPs (13 nm in average size) as a function of the field (0–30 kOe) and volume fraction of the Fe NPs (0.5%–51%) in a polymer matrix with dimensions of 4 mm × 4 mm × 0.7 mm{sup t}. A columnar-structured Fe NP assembly was successfully achieved along an in-plane direction (defined as the x-axis) under optimized conditions. From static magnetization curves, induced uniaxial magnetic anisotropy was observed according to the shape of the columnar structure of the Fe NP assembly, where easy and hard axes of magnetization were realized along the parallel (x-axis) and normal directions (in-plane y-axis and z-axis in the thickness direction) to the external field during the process, respectively. Interestingly, this fabricated columnar-structured Fe NP assembly exhibited very high f{sub r} in the range from 3 to 11 GHz judging from the complex susceptibility spectra obtained. The f{sub r} values were well-scaled by a modified Snoek's-limit-law using demagnetization factors quantitatively estimated from the static magnetization curves. Thus, shape-induced anisotropy originating from the unidirectional state of H{sub dip} in the columnar structure of the Fe NP assembly plays an important role for high frequency magnetic response in the GHz-band.

Ogawa, T., E-mail: tomoyuki@ecei.tohoku.ac.jp; Tate, R. [Department of Electronic Engineering, Graduate School of Engineering, Tohoku University, 6-6-05 Aza-Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Kura, H. [New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aza-Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Oikawa, T.; Hata, K. [Samsung R and D Institute Japan Co., Ltd., 2-7 Sugasawa-cho, Tsurumi-ku, Yokohama 230-0027 (Japan)

2014-05-07

388

Combined, Time-Resolved ?-Ray and Fast Neutron Radiography for Contraband Detection  

International Nuclear Information System (INIS)

Soreq NRC and PTB are developing dual-probe (gamma-ray and fast neutron) high-spatial-resolution radiography for detection of explosives and special nuclear materials (SNM). The explosives are detected by Fast Neutron Resonance Radiography (FNRR), that exploits the specific energy-dependent cross-section characteristics of several low-Z elements in the neutron energy-range En=1-10 MeV. The neutrons are produced in 1-2 ns bursts using a pulsed beam of 12 MeV deuterons impinging on a thick Be target. Neutron spectroscopy is performed by means of a novel, integral-mode variant of the time of flight (TOF) technique. This method holds promise for detecting a broad range of conventional and improvised explosives, by determining the identity and density distribution of light elements such as C, N and O within an inspected object. It is expected that the high spatial resolution and the capability of operating at very high counting rates particular to this method will ultimately permit a significant improvement in baggage screening capabilities at airports, in terms of enhanced throughput and operator-independent detection of sheet explosives. In addition to neutrons, the d-Be reaction also yields prompt gamma-rays in the 0.5-6 MeV range. These gamma-rays are readily distinguished from neutrons by TOF. By taking the attenuation ratio of neutrons to gamma-rays through the inspected object it is possible to distinguish materials according to their atomic number. For els according to their atomic number. For example, the ratio for tungsten is higher by a factor of 4.2 and 2.3 than that of water and iron, respectively. The method produces high resolution images and also has the potential to detect small quantities of SNM. In this paper we shall describe the time-resolved neutron-gamma ray imaging detector and present studies of various detector parameters, such as spatial and energy resolution, imaging and material discrimination capabilities. (author)

389

Fast-Response, Sensitivitive and Low-Powered Chemosensors by Fusing Nanostructured Porous Thin Film and IDEs-Microheater Chip  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The chemiresistive thin film gas sensors with fast response, high sensitivity, low power consumption and mass-produced potency, have been expected for practical application. It requires both sensitive materials, especially exquisite nanomaterials, and efficient substrate chip for heating and electrical addressing. However, it is challenging to achieve repeatable microstructures across the films and low power consumption of substrate chip. Here we presented a new sensor structure via the fusio...

Zhengfei Dai; Lei Xu; Guotao Duan; Tie Li; Hongwen Zhang; Yue Li; Yi Wang(Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, University of Tokyo (WPI), 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, Japan); Yuelin Wang; Weiping Cai

2013-01-01

390

Development of a fast response detector using Yb:Lu2O3 scintillator for lifetime measurement positron emission tomography  

International Nuclear Information System (INIS)

We propose a three-dimensional imaging measurement method of the defect distribution inside industrial materials by measuring the lifetime of positrons in addition to the imaging technique of positron emission tomography. A compact and fast response detector which uses an Yb3+-doped Lu2O3 scintillator and a photomultiplier tube was developed and tested. We have successfully measured the positron lifetimes of a bulk material using the Yb:Lu2O3 scintillator. (author)

391

Response time of Saguenay fjord sediments to metal contamination  

International Nuclear Information System (INIS)

Dated sediment cores record, with varying degrees of time lag, the recent (1946-1976) history of natural and industrial inputs of Hg and other metals into the Saguenay Fjord, Quebec. This is illustrated in a dated core from an oxic basin near the head of the fjord. The core was analyzed at 1 cm intervals for Hg, Zn, Pb, Cu, Co, Ni, Cr, V, Cd, organic carbon Pb210, and Cs137. Partitioning of the metals between the silicate, organic, and non-detrial phases and factor analyses of the data indicate that terrigenous organic matter is the main scavenging agent and carrier for the transport and deposition of Hg and available Zn, and V to the sediments. Radiometric dating indicates that Hg and other small but significant amounts of Zn, Pb, and V contamination began about 1948 after a chlor-alkali plant began production on the river entering the fjord. Inputs of Hg and other metals to the sediments from the plant and associated industries increased with time and reached maximum rates in the late 1960s and early 1970s before declining in response to pollution controls. Comparison of the variation in Hg fluxes recorded in the core with changes in the calculated industrial inputs shows that the time lag between the two curves is 1 to 2 years at this site, but at other sites the time response varied from a few months at the head of the fjord to 10-15 years at the seaward end. These variations in time response relate to sedimentation rates, residence times in o sedimentation rates, residence times in the water column, distance from source and to changes in the flux of terrigenous organic matter to the fjord sediments.(author)

392

Diurnal Alterations of Refraction, Anterior Segment Biometrics, and Intraocular Pressure in Long-Time Dehydration due to Religious Fasting.  

Science.gov (United States)

Abstract Purpose: To investigate the effects of dehydration due to fasting on diurnal changes of intraocular pressure, anterior segment biometrics, and refraction. Subjects and methods: The intraocular pressures, anterior segment biometrics (axial length: AL; Central corneal thickness: CCT; Lens thickness: LT; Anterior chamber depth: ACD), and refractive measurements of 30 eyes of 15 fasting healthy male volunteers were recorded at 8:00 in the morning and 17:00 in the evening in the Ramadan of 2013 and two months later. The results were compared and the statistical analyses were performed using the Rstudio software version 0.98.501. The variables were investigated using visual (histograms, probability plots) and analytical methods (Kolmogorov-Smirnov/Shapiro-Wilk test) to determine whether or not they were normally distributed. Results: The refractive values remained stable in the fasting as well as in the control period (p?=?0.384). The axial length measured slightly shorter in the fasting period (p?=?0.001). The corneal thickness presented a diurnal variation, in which the cornea measured thinner in the evening. The difference between the fasting and control period was not statistically significant (p?=?0.359). The major differences were observed in the anterior chamber depth and IOP. The ACD was shallower in the evening during the fasting period, where it was deeper in the control period. The diurnal IOP difference was greater in the fasting period than the control period. Both were statistically significant (p?=?0.001). The LT remained unchanged in both periods. Conclusions: The major difference was shown in the anterior chamber shallowing in the evening hours and IOP. Our study contributes the hypothesis that the posterior segment of the eye is more responsible for the axial length alterations and normovolemia has a more dominant influence on diurnal IOP changes. PMID:25409203

Baser, Gonen; Cengiz, Hakan; Uyar, Murat; Seker Un, Emine

2014-11-19

393

A Novel of Hybrid Magnet Engine Valve Actuator Using Shorted Turn for Fast Initial Response  

Directory of Open Access Journals (Sweden)

Full Text Available A variable valve timing (VVT can improve fuel efficiency, reduce CO2 emission and increase torque output. To achieve VVT in internal combustion engine, new devices such as mechanical, hydraulic, motor-driven and electromagnetic actuator have been developed in past years to replace the conventional camshaft valve train system used currently. Among these, the electromagnetic actuator using solenoids is the most advance system to provide the most flexibility to valve timing, but it has critical drawback of high power consumption. This paper presents a novel design of Hybrid Magnet Engine Valve Actuator (HMEVA using shorted turn. A shorted turn is placed into existing design in order to reduce the inductance of coil and improve the initial response. Dynamic finite element analysis using commercial electromagnetic solver “MAXWEL” is performed to simulate the improvement of dynamic characteristic of model.

DucThuan Vu

2013-01-01

394

A Novel of Hybrid Magnet Engine Valve Actuator Using Shorted Turn for Fast Initial Response  

Directory of Open Access Journals (Sweden)

Full Text Available A variable valve timing (VVT can improve fuel efficiency, reduce CO2 emission and increase torque output. To achieve VVT in internal combustion engine, new devices such as mechanical, hydraulic, motor-driven and electromagnetic actuator have been developed in past years to replace the conventional camshaft valve train system used currently. Among these, the electromagnetic actuator using solenoids is the most advance system to provide the most flexibility to valve timing, but it has critical drawback of high power consumption. This paper presents a novel design of Hybrid Magnet Engine Valve Actuator (HMEVA using shorted turn. A shorted turn is placed into existing design in order to reduce the inductance of coil and improve the initial response. Dynamic finite element analysis using commercial electromagnetic solver “MAXWEL” is performed to simulate the improvement of dynamic characteristic of model.

Duc Thuan Vu

2013-05-01

395

Real-time 3D medical structure segmentation using fast evolving active contours  

Science.gov (United States)

Segmentation of 3D medical structures in real-time is an important as well as intractable problem for clinical applications due to the high computation and memory cost. We propose a novel fast evolving active contour model in this paper to reduce the requirements of computation and memory. The basic idea is to evolve the brief represented dynamic contour interface as far as possible per iteration. Our method encodes zero level set via a single unordered list, and evolves the list recursively by adding activated adjacent neighbors to its end, resulting in active parts of the zero level set moves far enough per iteration along with list scanning. To guarantee the robustness of this process, a new approximation of curvature for integer valued level set is proposed as the internal force to penalize the list smoothness and restrain the list continual growth. Besides, list scanning times are also used as an upper hard constraint to control the list growing. Together with the internal force, efficient regional and constrained external forces, whose computations are only performed along the unordered list, are also provided to attract the list toward object boundaries. Specially, our model calculates regional force only in a narrowband outside the zero level set and can efficiently segment multiple regions simultaneously as well as handle the background with multiple components. Compared with state-of-the-art algorithms, our algorithm is one-order of magnitude faster with similar segmentation accuracy and can achieve real-time performance for the segmentation of 3D medical structures on a standard PC.

Wang, Xiaotao; Wang, Qiang; Hao, Zhihui; Xu, Kuanhong; Guo, Ping; Ren, Haibing; Jang, Wooyoung; Kim, Jung-bae

2014-03-01

396

Development of a very fast spectral response measurement system for analysis of hydrogenated amorphous silicon solar cells and modules  

International Nuclear Information System (INIS)

Highlights: ? Spectral response equipment for measuring a-Si:H solar cells in a few seconds. ? Equipment based on 16 LEDs with simultaneous illumination of the solar cell. ? The current generated by each LED is analyzed by a Fast Fourier Transform. ? Cheap equipment without lock-in technology for the current measurement. ? Measurement error vs. conventional measurement less than 1% in Jsc. - Abstract: An important requirement for a very fast spectral response measurement system is the simultaneous illumination of the solar cell at multiple well defined wavelengths. Nowadays this can be done by means of light emitting diodes (LEDs) available for a multitude of wavelengths. For the purpose to measure the spectral response (SR) of amorphous silicon solar cells a detailed characterization of LEDs emitting in the wavelength range from 300 nm to 800 nm was performed. In the here developed equipment the LED illumination is modulated in the frequency range from 100 Hz to 200 Hz and the current generated by each LED is analyzed by a Fast Fourier Transform (FFT) to determine the current component corresponding to each wavelength. The equipment provides a signal to noise ratio of 2–4 orders of magnitude for individual wavelengths resulting in a precise measurement of the SR over the whole wavelength range. The difference of the short circuit current determined from the SR is less than 1% in comparison to a conventional system with monochromator.with monochromator.

397

Response of Gut Microbiota to Fasting and Hibernation in Syrian Hamsters? †  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Although hibernating mammals wake occasionally to eat during torpor, this period represents a state of fasting. Fasting is known to alter the gut microbiota in nonhibernating mammals; therefore, hibernation may also affect the gut microbiota. However, there are few reports of gut microbiota in hibernating mammals. The present study aimed to compare the gut microbiota in hibernating torpid Syrian hamsters with that in active counterparts by using culture-independent analyses. Hamsters were all...

Sonoyama, Kei; Fujiwara, Reiko; Takemura, Naoki; Ogasawara, Toru; Watanabe, Jun; Ito, Hiroyuki; Morita, Tatsuya

2009-01-01

398

GABAB receptor activation attenuates the stimulant but not mesolimbic dopamine response to ethanol in FAST mice  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Neural processes influenced by ?-aminobutyric acid B (GABAB) receptors appear to contribute to acute ethanol sensitivity, including the difference between lines of mice bred for extreme sensitivity (FAST) or insensitivity (SLOW) to the locomotor stimulant effect of ethanol. One goal of the current study was to determine whether selection of the FAST and SLOW lines resulted in changes in GABAB receptor function, since the lines differ in sensitivity to the GABAB receptor agonist baclofen and ...

Holstein, Sarah E.; Li, Na; Eshleman, Amy J.; Phillips, Tamara J.

2012-01-01

399

Object Oriented Query Response Time for UML Models  

Directory of Open Access Journals (Sweden)

Full Text Available Nowadays, the size of database of any business organization is increasing and many of the companies are shifted the old structured database into the object oriented database. Due to increase of size of database complexity of database is increasing therefore, it is necessary to optimize the object oriented query response time from the complex object oriented database. In the present paper, a real case study of Life Insurance Corporation of India is taken and sample object oriented database is designed by the use of SQL Server 2008. A UML model is designed for computing the object oriented query response time. Table and graph are also represented for the computed records in five runs.

Santosh Kumar

2012-07-01

400

Object Oriented Query Response Time for UML Models  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nowadays, the size of database of any business organization is increasing and many of the companies are shifted the old structured database into the object oriented database. Due to increase of size of database complexity of database is increasing therefore, it is necessary to optimize the object oriented query response time from the complex object oriented database. In the present paper, a real case study of Life Insurance Corporation of India is taken and sample object oriented database is ...

Santosh Kumar (Corresponding Author); Vipin Saxena

2012-01-01

 
 
 
 
401

Time-dependent response of filamentary composite spherical pressure vessels  

Science.gov (United States)

A filamentary composite spherical pressure vessel is modeled as a pseudoisotropic (or transversely isotropic) composite shell, with the effects of the liner and fill tubes omitted. Equations of elasticity, macromechanical and micromechanical formulations, and laminate properties are derived for the application of an internally pressured spherical composite vessel. Viscoelastic properties for the composite matrix are used to characterize time-dependent behavior. Using the maximum strain theory of failure, burst pressure and critical strain equations are formulated, solved in the Laplace domain with an associated elastic solution, and inverted back into the time domain using the method of collocation. Viscoelastic properties of HBFR-55 resin are experimentally determined and a Kevlar/HBFR-55 system is evaluated with a FORTRAN program. The computed reduction in burst pressure with respect to time indicates that the analysis employed may be used to predict the time-dependent response of a filamentary composite spherical pressure vessel.

Dozier, J. D.

1983-01-01

402

Time to peak serum antibody response to influenza vaccine.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The time to the appearance of a peak serum antibody response to influenza virus vaccine is not clearly defined. We compared the most commonly used time intervals described in the literature--4 and 6 weeks after vaccination. We studied 118 elderly patients from three different geographic sites. The 1992 to 1993 trivalent inactivated influenza virus vaccine containing influenza virus A/Beijing/353/89 (H3N2), influenza virus A/Texas/36/91 (H1N1), and influenza virus B/Panama/45/90 was used. No s...

Rastogi, S.; Gross, P. A.; Bonelli, J.; Dran, S.; Levandowski, R. A.; Russo, C.; Weksler, M. E.; Kaye, D.; Levison, M.; Abrutyn, E.

1995-01-01

403

Destruction of hazardous air pollutants using a fast rise time pulsed corona reactor  

Science.gov (United States)

Increasingly stringent environmental regulation imposed on both the military and civilian sectors has created a growing demand for alternative abatement methods for a variety of hazardous compounds. One alternative, the nonthermal plasma, shows promise of providing an efficient means for the destruction of dilute concentrations of hazardous air pollutants. The Dahlgren Laboratory of the Naval Surface Warfare Center has extensively investigated one type of nonthermal plasma discharge, the pulsed corona reactor, for the destruction of volatile organic compounds and chemical warfare agents. In this reactor, a fast rise time (˜10 ns), short duration (voltage pulse is repetitively delivered to a wire-cylinder electrode geometry, thereby producing a multitude of streamer discharges along its length. The resulting nonthermal plasma contains highly reactive chemical radicals which can interact with and destroy the hazardous molecules entrained in the ambient atmosphere flowing through the reactor volume. Increased electrical efficiency was obtained using a combination of high efficiency constant-current capacitor-charging, high repetition-rate spark gap switching, and resonant energy transfer to the reactor. Promising results have been obtained for toluene, methylene chloride, and dichlorodifluoromethane in air at concentrations of a few hundred parts per million. The device has been operated at voltages up to 30 kV, pulse repetition rates up to 1.4 kHz, and flow rates up to 60 l/min. Detailed electrical measurements have been made to properly characterize the electrical properties of the pulsed corona reactor and to validate subsequent improvements in the reactor energy efficiency.

Korzekwa, R. A.; Grothaus, M. G.; Hutcherson, R. K.; Roush, R. A.; Brown, R.

1998-04-01

404

Fast time domain reflectometry (TDR) measurement approach for investigating the liquefaction of soils  

International Nuclear Information System (INIS)

Time domain reflectometry (TDR) was used for the spatial observation of transient density changes in a laboratory shake-box apparatus. Shake-box experiments are conducted to investigate the liquefaction of soils due to seismic excitation. As a sensor, a flat ribbon cable was placed within a water saturated sand column two metres in height. In the experiment, the soil column was excited at its base with a sinusoidal signal with low frequencies and moderate amplitudes. During the tests, TDR measurements were conducted with a repetition rate of 30 s?1. Temporal density changes during the liquefaction and reconsolidation process of the quartz sand along the sensor could be shown through signal analysis. The mean porosities calculated from the relative dielectric permittivity using a soil-specific calibration function could be determined with an RMSD-value of 0.02 compared to the porosities determined from the height of the sample. With the metrological set-up for the TDR measurements being used, fast temporal changes in the density profile could be qualitatively visualized indicating the movement of the reconsolidation front during the liquefaction

405

Fast-neutron Induced Reactions at the nELBE Time-of-flight Facility  

Science.gov (United States)

The compact neutron-time-of-flight facility nELBE at the superconducting electron accelerator ELBE of Helmholtz-Zentrum Dresden-Rossendorf is being rebuilt and extended with a low-background experimental hall. The neutron radiator consists of a liquid lead circuit without additional neutron moderators. The useful neutron spectrum extends from some tens of keV to about 10 MeV. nELBE is intended to deliver cross section data of fast-neutron nuclear interactions e.g. for the transmutation of nuclear waste and improvement of neutron physical simulations of innovative nuclear systems. Before the extension of the facility, the photon production cross section of 56Fe was measured with an HPGe detector and the inelastic neutron scattering cross section to the first few excited states in 56Fe was determined. The neutron total cross sections of Au and Ta were determined in the energy from 200 keV to 7 MeV in a transmission experiment.

Junghans, A. R.; Beyer, R.; Elekes, Z.; Grosse, E.; Hannaske, R.; Kögler, T.; Massarczyk, R.; Schwengner, R.; Wagner, A.

2014-05-01

406

An Efficient Approach to Improve Response Time in Multibiometric Patterns Retrieval from Large Database  

Directory of Open Access Journals (Sweden)

Full Text Available Biometric technologies are automated methods of verifying or recognizing the identity of a livingperson based on a physiological or behavioural characteristics. In a biometric identification system, theidentity corresponding to the input data (probe/investigation is typically determined by comparing it againstthe templates of all identities in a database (gallery.Exhaustive/in-depth matching against a large number ofidentities increases the response time of the system and may also reduce the accuracy of identification. Oneway to reduce the response time is by designing biometric templates that allow for rapid matching. Analternative approach is to limit the number of identities against which matching is performed based oncriteria that are fast to evaluate. In the Existing system the search space is reduced by partitioning thedatabase into several bins. Following such binning, the biometric database will be partitioned such that thetemplates in each bin are similar and correspond to some natural or statistical class. In case of the traditional1: N comparisons for identification, the time needed for the system would be to determine the distancebetween the test template and the N templates in database. Thus the total time needed in such a case could begiven as: Q (N. The proposed work focuses on reducing the search space using Gittins index algorithm andalso improves the accuracy of identification.

S. Balgani

2013-05-01

407

A Fast Topological Trigger for Real Time Analysis of Nanosecond Phenomena; Opening the Gamma Ray Window to Our Universe  

Energy Technology Data Exchange (ETDEWEB)

This work was to enable the development of a proof-of-principle nanosecond trigger system that is designed to perform a real time analysis of fast Cherenkov light flashes from air showers. The basic building blocks of the trigger system have been designed and constructed, and a real world system is now operating in the VERITAS experiment.

Krennrich, Frank [Iowa State University

2013-09-24

408

Some Measurements of Fast Reactor Spectra by the Time-of-Flight Technique Using a Pulsed Neutron Source  

International Nuclear Information System (INIS)

The zero-energy fast reactor VERA is equipped with a pulsed neutron source and a 50-m neutron flight path and these facilities have been used for time-of-flight neutron spectrometry in the energy range 100 eV to 50 keV. The results are discussed and are compared with calculated values. (author)

409

Preparation of fast response superabsorbent hydrogels by radiation polymerization and crosslinking of N-isopropylacrylamide in solution  

International Nuclear Information System (INIS)

Macroporous temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm) hydrogels with high equilibrium swelling and fast response rates were obtained by a 60Co ?- and electron beam (EB) irradiation of aqueous N-isopropylacrylamide (NIPAAm) monomer solutions. The effect of irradiation temperatures, the dose, the addition of a pore-forming agent on the swelling ratio, and the kinetics of swelling and shrinking of the PNIPAAm gels was studied. The gels synthesized above the LCST exhibited the highest equilibrium swelling (300-400) and fastest response rate measured by minutes. Scanning electron microscope (SEM) pictures revealed that the gels synthesized above the LCST have larger pores than those prepared at temperatures below the LCST. The gels showed a reversible response to cyclical changes in temperature and might be used in a pulsed drug delivery device. The gels synthesized above the LCST exhibited the highest testosterone propionate release

410

A real-time tritium monitor with an MPC proportional response to airborne mixtures of TH and THO  

International Nuclear Information System (INIS)

A fast response tritium-in-air monitor that can detect airborne HT and HTO in proportion to the occupational maximum permissible concentration (MPC) of either species has been deceloped at Lawrence Livermore Laboratory. The sample gas is selectively filtered through a dimethyl silicon membrane resulting in a throughput that is 400 times greater for HTO than for HT. After filtering, the tritium is detected in a 10 cm3 flow-through proportional counter. A short accumulation time, for a 5 s response to high levels of tritium (>= 1000 MPC), and a longer accumulation time, for a 60 s response to low levels of tritium (>= 10 MPC), are included. To avoid false alarms the short accumulation counter is continuously compared to a pulser set at three standard deviations above background. (orig.)

411

Acetobacter aceti fast identification by Real Time PCR in spoiled wine samples  

Directory of Open Access Journals (Sweden)

Full Text Available Wine is a beverage that made from grape berries. However, without beneficial bacteria, we would not produce good wine. But very often wines contain acetic acid bacteria, which are undesirable in winemaking process. Acetic acid bacteria as known as a vinegar bacteria are Gram-negative, aerobic, rod-shaped and ubiquitous bacteri