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Sample records for single time constant

On the thermal inertia and time constant of single-family houses

Energy Technology Data Exchange (ETDEWEB)

Hedbrant, J.

2001-08-01

Since the 1970s, electricity has become a common heating source in Swedish single-family houses. About one million small houses can use electricity for heating, about 600.000 have electricity as the only heating source, A liberalised European electricity market would most likely raise the Swedish electricity prices during daytime on weekdays and lower it at other times. In the long run, electrical heating of houses would be replaced by fuels, but in the shorter perspective, other strategies may be considered. This report evaluates the use of electricity for heating a dwelling, or part of it, at night when both the demand and the price are low. The stored heat is utilised in the daytime some hours later, when the electricity price is high. Essential for heat storage is the thermal time constant. The report gives a simple theoretical framework for the calculation of the time constant for a single-family house with furniture. Furthermore the comfort time constant, that is, the time for a house to cool down from a maximum to a minimum acceptable temperature, is derived. Two theoretical model houses are calculated, and the results are compared to data from empirical studies in three inhabited test houses. The results show that it was possible to store about 8 kWh/K in a house from the seventies and about 5 kWh/K in a house from the eighties. The time constants were 34 h and 53 h, respectively. During winter conditions with 0 deg C outdoor, the 'comfort' time constants with maximum and minimum indoor temperatures of 23 and 20 deg C were 6 h and 10 h. The results indicate that the maximum load-shifting potential of an average single family house is about 1 kw during 16 daytime hours shifted into 2 kw during 8 night hours. Upscaled to the one million Swedish single-family houses that can use electricity as a heating source, the maximum potential is 1000 MW daytime time-shifted into 2000 MW at night.
Using Constant Time Delay to Teach Braille Word Recognition

Science.gov (United States)

Hooper, Jonathan; Ivy, Sarah; Hatton, Deborah

2014-01-01

Introduction: Constant time delay has been identified as an evidence-based practice to teach print sight words and picture recognition (Browder, Ahlbrim-Delzell, Spooner, Mims, & Baker, 2009). For the study presented here, we tested the effectiveness of constant time delay to teach new braille words. Methods: A single-subject multiple baseline…
Line-focus acoustic microscopy of Ti-6242 α/β single colony: determination of elastic constants

International Nuclear Information System (INIS)

Kim, J.-Y.; Yakovlev, V.; Rokhlin, S.I.

2002-01-01

Time-resolved line-focus acoustic microscopy is performed for determining elastic constants of Ti-6242 α/β-single colony and Ti-6 α-phase single crystal. Surface acoustic wave (SAW) velocities are obtained as a function of the propagation angle from measured time-delays of SAW signals. The propagation of surface waves in a semi-infinite half space formed by anisotropic layers inclined arbitrarily to the sample surface is studied to model a quasi-random lamellar structure of the Ti-6242 α/β-single colony. Effective elastic constants of the multilayered structure are derived and verified through the comparison with exact ones, based on which SAW velocities in non-principal planes are calculated. Effective and constituent elastic constants of the α/β-single colony and the α-phase single crystal are inversely determined from the measured and calculated SAW velocities. The α- and β-phase elastic constants from the α/β-single colony so determined are compared with those from the α-single crystal and data in the literature
Constant resolution of time-dependent Hartree--Fock phase ambiguity

International Nuclear Information System (INIS)

Lichtner, P.C.; Griffin, J.J.; Schultheis, H.; Schultheis, R.; Volkov, A.B.

1978-01-01

The customary time-dependent Hartree--Fock problem is shown to be ambiguous up to an arbitrary function of time additive to H/sub HF/, and, consequently, up to an arbitrary time-dependent phase for the solution, PHI(t). The ''constant'' (H)'' phase is proposed as the best resolution of this ambiguity. It leads to the following attractive features: (a) the time-dependent Hartree--Fock (TDHF) Hamiltonian, H/sub HF/, becomes a quantity whose expectation value is equal to the average energy and, hence, constant in time; (b) eigenstates described exactly by determinants, have time-dependent Hartree--Fock solutions identical with the exact time-dependent solutions; (c) among all possible TDHF solutions this choice minimizes the norm of the quantity (H--i dirac constant delta/delta t) operating on the ket PHI, and guarantees optimal time evolution over an infinitesimal period; (d) this choice corresponds both to the stationary value of the absolute difference between (H) and (i dirac constant delta/delta t) and simultaneously to its absolute minimal value with respect to choice of the time-dependent phase. The source of the ambiguity is discussed. It lies in the time-dependent generalization of the freedom to transform unitarily among the single-particle states of a determinant at the (physically irrelevant for stationary states) cost of altering only a factor of unit magnitude
A time-to-amplitude converter with constant fraction timing discriminators for short time interval measurements

International Nuclear Information System (INIS)

Kostamovaara, J.; Myllylae, R.

1985-01-01

The construction and the performance of a time-to-amplitude converter equipped with constant fraction discriminators is described. The TAC consists of digital and analog parts which are constructed on two printed circuit boards, both of which are located in a single width NIM module. The dead time of the TAC for a start pulse which is not followed by a stop pulse within the time range of the device (proportional100 ns) is only proportional100 ns, which enables one to avoid counting rate saturation even with a high random input signal rate. The differential and integral nonlinearities of the TAC are better than +-1.5% and 0.05%, respectively. The resolution for input timing pulses of constant shape is 20 ps (fwhm), and less than 10 ps (fwhm) with a modification in the digital part. The walk error of the constant fraction timing discriminators is presented and various parameters affecting it are discussed. The effect of the various disturbances in linearity caused by the fast ECL logic and their minimization are also discussed. The time-to-amplitude converter has been used in positron lifetime studies and for laser range finding. (orig.)
Electronic setup for fluorescence emission measurements and long-time constant-temperature maintenance of Single-Walled Carbon Nano-Tubes in water solutions

Directory of Open Access Journals (Sweden)

De Rosa Matteo

2017-03-01

Full Text Available In our previous research we have observed that the fluorescence emission from water solutions of Single-Walled Carbon Nano-Tubes (SWCNT, excited by a laser with a wavelength of 830nm, diminishes with the time. We have already proved that such a fading is a function of the storage time and the storage temperature. In order to study the emission of the SWCNT as a function of these two parameters we have designed and realized a special measurement compartment with a cuvette holder where the SWCNT solutions can be measured and stored at a fixed constant temperature for periods of time as long as several weeks. To maintain the measurement setup under a constant temperature we have designed special experimental setup based on two Peltier cells with electronic temperature control.
A Parallel Priority Queue with Constant Time Operations

DEFF Research Database (Denmark)

Brodal, Gerth Stølting; Träff, Jesper Larsson; Zaroliagis, Christos D.

1998-01-01

We present a parallel priority queue that supports the following operations in constant time:parallel insertionof a sequence of elements ordered according to key,parallel decrease keyfor a sequence of elements ordered according to key,deletion of the minimum key element, anddeletion of an arbitrary...... application is a parallel implementation of Dijkstra's algorithm for the single-source shortest path problem, which runs inO(n) time andO(mlogn) work on a CREW PRAM on graphs withnvertices andmedges. This is a logarithmic factor improvement in the running time compared with previous approaches....
Single-crystal elastic constants of a plutonium-gallium alloy

International Nuclear Information System (INIS)

Moment, R.L.

1976-01-01

The single-crystal elastic constants of a plutonium-1 wt % gallium alloy were determined at room temperature by measuring ultrasonic sound-wave velocities. The three independent elastic constants of this face-centered cubic delta-phase alloy were determined from the longitudinal and the two shear-wave velocities, all along a direction. Their values are C 11 =3.628, C 12 =2.673 and C 44 =3.359 in units of 10 10 N/m 2 ; the respective errors are estimated to be 1%, 1%, and 0.3 %. The Zener anisotropy ratio is 7.03, almost twice that known for any other fcc metal, and falls among the ratios for the body centered cubic alkali metals, which are noted for their high elastic anisotropy. Polycrystalline elastic constants calculated from the single-crystal data are Young's modulus E=4.064, the shear modulus G=1.596 and the bulk modulus (reciprocal compressibility) B=2.991, all in units of 10 10 N/m 2 , and Poisson's ratio γ=0.27. These values of E and G are both lower than those obtained by Taylor, Linford and Dean from measurements on polycrystalline specimens. Within a single crystal, the longitudinal sound velocity varies with direction by a factor of 1.4 and the transverse velocity by a factor of 2.6. The maximum Young's modulus (along ) was 5.4 times larger than the minimum (along ). The Debye temperature was calculated to be 105.7 K at 293 K and estimated to be 114 K at 0.K. (Auth.)
Diffraction and single-crystal elastic constants of Inconel 625 at room and elevated temperatures determined by neutron diffraction

International Nuclear Information System (INIS)

Wang, Zhuqing; Stoica, Alexandru D.; Ma, Dong; Beese, Allison M.

2016-01-01

In this work, diffraction and single-crystal elastic constants of Inconel 625 have been determined by means of in situ loading at room and elevated temperatures using time-of-flight neutron diffraction. Theoretical models proposed by Voigt, Reuss, and Kroner were used to determine single-crystal elastic constants from measured diffraction elastic constants, with the Kroner model having the best ability to capture experimental data. The magnitude of single-crystal elastic moduli, computed from single-crystal elastic constants, decreases and the single crystal anisotropy increases as temperature increases, indicating the importance of texture in affecting macroscopic stress at elevated temperatures. The experimental data reported here are of great importance in understanding additive manufacturing of metallic components as: diffraction elastic constants are required for computing residual stresses from residual lattice strains measured using neutron diffraction, which can be used to validate thermomechanical models of additive manufacturing, while single-crystal elastic constants can be used in crystal plasticity modeling, for example, to understand mechanical deformation behavior of additively manufactured components.
Diffraction and single-crystal elastic constants of Inconel 625 at room and elevated temperatures determined by neutron diffraction

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhuqing [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Stoica, Alexandru D. [Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Ma, Dong, E-mail: dongma@ornl.gov [Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Beese, Allison M., E-mail: amb961@psu.edu [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States)

2016-09-30

In this work, diffraction and single-crystal elastic constants of Inconel 625 have been determined by means of in situ loading at room and elevated temperatures using time-of-flight neutron diffraction. Theoretical models proposed by Voigt, Reuss, and Kroner were used to determine single-crystal elastic constants from measured diffraction elastic constants, with the Kroner model having the best ability to capture experimental data. The magnitude of single-crystal elastic moduli, computed from single-crystal elastic constants, decreases and the single crystal anisotropy increases as temperature increases, indicating the importance of texture in affecting macroscopic stress at elevated temperatures. The experimental data reported here are of great importance in understanding additive manufacturing of metallic components as: diffraction elastic constants are required for computing residual stresses from residual lattice strains measured using neutron diffraction, which can be used to validate thermomechanical models of additive manufacturing, while single-crystal elastic constants can be used in crystal plasticity modeling, for example, to understand mechanical deformation behavior of additively manufactured components.
Synaptic inhibition and excitation estimated via the time constant of membrane potential fluctuations

DEFF Research Database (Denmark)

Berg, Rune W.; Ditlevsen, Susanne

2013-01-01

When recording the membrane potential, V, of a neuron it is desirable to be able to extract the synaptic input. Critically, the synaptic input is stochastic and non-reproducible so one is therefore often restricted to single trial data. Here, we introduce means of estimating the inhibition and ex...... close to soma (recording site). Though our data is in current-clamp, the method also works in V-clamp recordings, with some minor adaptations. All custom made procedures are provided in Matlab....... and excitation and their confidence limits from single sweep trials. The estimates are based on the mean membrane potential, (V) , and the membrane time constant,τ. The time constant provides the total conductance (G = capacitance/τ) and is extracted from the autocorrelation of V. The synaptic conductances can....... The method gives best results if the synaptic input is large compared to other conductances, the intrinsic conductances have little or no time dependence or are comparably small, the ligand gated kinetics is faster than the membrane time constant, and the majority of synaptic contacts are electrotonically...
The time constant of the somatogravic illusion.

Science.gov (United States)

Correia Grácio, B J; de Winkel, K N; Groen, E L; Wentink, M; Bos, J E

2013-02-01

Without visual feedback, humans perceive tilt when experiencing a sustained linear acceleration. This tilt illusion is commonly referred to as the somatogravic illusion. Although the physiological basis of the illusion seems to be well understood, the dynamic behavior is still subject to discussion. In this study, the dynamic behavior of the illusion was measured experimentally for three motion profiles with different frequency content. Subjects were exposed to pure centripetal accelerations in the lateral direction and were asked to indicate their tilt percept by means of a joystick. Variable-radius centrifugation during constant angular rotation was used to generate these motion profiles. Two self-motion perception models were fitted to the experimental data and were used to obtain the time constant of the somatogravic illusion. Results showed that the time constant of the somatogravic illusion was on the order of two seconds, in contrast to the higher time constant found in fixed-radius centrifugation studies. Furthermore, the time constant was significantly affected by the frequency content of the motion profiles. Motion profiles with higher frequency content revealed shorter time constants which cannot be explained by self-motion perception models that assume a fixed time constant. Therefore, these models need to be improved with a mechanism that deals with this variable time constant. Apart from the fundamental importance, these results also have practical consequences for the simulation of sustained accelerations in motion simulators.
Schottky junctions on perovskite single crystals: light-modulated dielectric constant and self-biased photodetection

KAUST Repository

Shaikh, Parvez Abdul Ajij

2016-08-16

Schottky junctions formed between semiconductors and metal contacts are ubiquitous in modern electronic and optoelectronic devices. Here we report on the physical properties of Schottky-junctions formed on hybrid perovskite CH3NH3PbBr3 single crystals. It is found that light illumination can significantly increase the dielectric constant of perovskite junctions by 2300%. Furthermore, such Pt/perovskite junctions are used to fabricate self-biased photodetectors. A photodetectivity of 1.4 × 1010 Jones is obtained at zero bias, which increases to 7.1 × 1011 Jones at a bias of +3 V, and the photodetectivity remains almost constant in a wide range of light intensity. These devices also exhibit fast responses with a rising time of 70 μs and a falling time of 150 μs. As a result of the high crystal quality and low defect density, such single-crystal photodetectors show stable performance after storage in air for over 45 days. Our results suggest that hybrid perovskite single crystals provide a new platform to develop promising optoelectronic applications. © 2016 The Royal Society of Chemistry.
Computing magnetic anisotropy constants of single molecule magnets

Indian Academy of Sciences (India)

We present here a theoretical approach to compute the molecular magnetic anisotropy parameters, and for single molecule magnets in any given spin eigenstate of exchange spin Hamiltonian. We first describe a hybrid constant -valence bond (VB) technique of solving spin Hamiltonians employing full spatial ...
Fundamental Constants in Physics and their Time Dependence

CERN Multimedia

CERN. Geneva

2008-01-01

In the Standard Model of Particle Physics we are dealing with 28 fundamental constants. In the experiments these constants can be measured, but theoretically they are not understood. I will discuss these constants, which are mostly mass parameters. Astrophysical measurements indicate that the finestructure constant is not a real constant, but depends on time. Grand unification then implies also a time variation of the QCD scale. Thus the masses of the atomic nuclei and the magnetic moments of the nuclei will depend on time. I proposed an experiment, which is currently done by Prof. Haensch in Munich and his group. The first results indicate a time dependence of the QCD scale. I will discuss the theoretical implications.
Evaluation of single crystal coefficients from mechanical and x-ray elastic constants of the polycrystal

International Nuclear Information System (INIS)

Hauk, V.; Kockelmann, H.

1979-01-01

Methods of calculation are developed for determination of single crystal elastic compliance or stiffness constants of cubic and hexagonal materials from mechanical and X-ray elastic constants of polycrystals. The calculations are applied to pure, cubic iron and hexagonal WC. There are no single crystal constants in the literature for WC, because no single crystals suitable for measurement are available. (orig.) [de
Estimation of Single-Crystal Elastic Constants of Polycrystalline Materials from Back-Scattered Grain Noise

International Nuclear Information System (INIS)

Haldipur, P.; Margetan, F. J.; Thompson, R. B.

2006-01-01

Single-crystal elastic stiffness constants are important input parameters for many calculations in material science. There are well established methods to measure these constants using single-crystal specimens, but such specimens are not always readily available. The ultrasonic properties of metal polycrystals, such as velocity, attenuation, and backscattered grain noise characteristics, depend in part on the single-crystal elastic constants. In this work we consider the estimation of elastic constants from UT measurements and grain-sizing data. We confine ourselves to a class of particularly simple polycrystalline microstructures, found in some jet-engine Nickel alloys, which are single-phase, cubic, equiaxed, and untextured. In past work we described a method to estimate the single-crystal elastic constants from measured ultrasonic velocity and attenuation data accompanied by metallographic analysis of grain size. However, that methodology assumes that all attenuation is due to grain scattering, and thus is not valid if appreciable absorption is present. In this work we describe an alternative approach which uses backscattered grain noise data in place of attenuation data. Efforts to validate the method using a pure copper specimen are discussed, and new results for two jet-engine Nickel alloys are presented
Long Pulse Integrator of Variable Integral Time Constant

International Nuclear Information System (INIS)

Wang Yong; Ji Zhenshan; Du Xiaoying; Wu Yichun; Li Shi; Luo Jiarong

2010-01-01

A kind of new long pulse integrator was designed based on the method of variable integral time constant and deducting integral drift by drift slope. The integral time constant can be changed by choosing different integral resistors, in order to improve the signal-to-noise ratio, and avoid output saturation; the slope of integral drift of a certain period of time can be calculated by digital signal processing, which can be used to deduct the drift of original integral signal in real time to reduce the integral drift. The tests show that this kind of long pulse integrator is good at reducing integral drift, which also can eliminate the effects of changing integral time constant. According to experiments, the integral time constant can be changed by remote control and manual adjustment of integral drift is avoided, which can improve the experiment efficiency greatly and can be used for electromagnetic measurement in Tokamak experiment. (authors)
The use of filtering methods to compensate for constant attenuation in single-photon emission computed tomography

International Nuclear Information System (INIS)

Gullberg, G.T.; Budinger, T.F.

1981-01-01

A back projection of filtered projection (BKFIL) reconstruction algorithm is presented that is applicable to single-photon emission computed tomography (ECT) in the presence of a constant attenuating medium such as the brain. The filters used in transmission computed tomography (TCT)-comprised of a ramp multiplied by window functions-are modified so that the single-photon ECT filter is a function of the constant attenuation coefficient. The filters give good reconstruction results with sufficient angular and lateral sampling. With continuous samples the BKFIL algorithm has a point spread function that is the Hankel transform of the window function. The resolution and statistical properties of the filters are demonstrated by various simulations which assume an ideal detector response. Statistical formulas for the reconstructed image show that the square of the percent-root-mean-square (percent-rms) uncertainty of the reconstruction is inversely proportional to the total measured counts. The results indicate that constant attenuation can be compensated for by using an attenuation-dependent filter that reconstructs the transverse section reliably. Computer time requirements are two times that of conventional TCT or positron ECT and there is no increase in memory requirements
A Digitally Programmable Differential Integrator with Enlarged Time Constant

Directory of Open Access Journals (Sweden)

S. K. Debroy

1994-12-01

Full Text Available A new Operational Amplifier (OA-RC integrator network is described. The novelties of the design are used of single grounded capacitor, ideal integration function realization with dual-input capability and design flexibility for extremely large time constant involving an enlargement factor (K using product of resistor ratios. The aspect of the digital control of K through a programmable resistor array (PRA controlled by a microprocessor has also been implemented. The effect of the OA-poles has been analyzed which indicates degradation of the integrator-Q at higher frequencies. An appropriate Q-compensation design scheme exhibiting 1 : |A|2 order of Q-improvement has been proposed with supporting experimental observations.

Time variable cosmological constants from the age of universe

International Nuclear Information System (INIS)

Xu Lixin; Lu Jianbo; Li Wenbo

2010-01-01

In this Letter, time variable cosmological constant, dubbed age cosmological constant, is investigated motivated by the fact: any cosmological length scale and time scale can introduce a cosmological constant or vacuum energy density into Einstein's theory. The age cosmological constant takes the form ρ Λ =3c 2 M P 2 /t Λ 2 , where t Λ is the age or conformal age of our universe. The effective equation of state (EoS) of age cosmological constant are w Λ eff =-1+2/3 (√(Ω Λ ))/c and w Λ eff =-1+2/3 (√(Ω Λ ))/c (1+z) when the age and conformal age of universe are taken as the role of cosmological time scales respectively. The EoS are the same as the so-called agegraphic dark energy models. However, the evolution histories are different from the agegraphic ones for their different evolution equations.
Time constant of logarithmic creep and relaxation

CSIR Research Space (South Africa)

Nabarro, FRN

2001-07-15

Full Text Available length and hardness which vary logarithmically with time. For dimensional reasons, a logarithmic variation must involve a time constant tau characteristic of the process, so that the deformation is proportional to ln(t/tau). Two distinct mechanisms...
Automated real time constant-specificity surveillance for disease outbreaks.

Science.gov (United States)

Wieland, Shannon C; Brownstein, John S; Berger, Bonnie; Mandl, Kenneth D

2007-06-13

For real time surveillance, detection of abnormal disease patterns is based on a difference between patterns observed, and those predicted by models of historical data. The usefulness of outbreak detection strategies depends on their specificity; the false alarm rate affects the interpretation of alarms. We evaluate the specificity of five traditional models: autoregressive, Serfling, trimmed seasonal, wavelet-based, and generalized linear. We apply each to 12 years of emergency department visits for respiratory infection syndromes at a pediatric hospital, finding that the specificity of the five models was almost always a non-constant function of the day of the week, month, and year of the study (p accounting for not only the expected number of visits, but also the variance of the number of visits. The expectation-variance model achieves constant specificity on all three time scales, as well as earlier detection and improved sensitivity compared to traditional methods in most circumstances. Modeling the variance of visit patterns enables real-time detection with known, constant specificity at all times. With constant specificity, public health practitioners can better interpret the alarms and better evaluate the cost-effectiveness of surveillance systems.
Numerical counting ratemeter with variable time constant and integrated circuits

International Nuclear Information System (INIS)

Kaiser, J.; Fuan, J.

1967-01-01

We present here the prototype of a numerical counting ratemeter which is a special version of variable time-constant frequency meter (1). The originality of this work lies in the fact that the change in the time constant is carried out automatically. Since the criterion for this change is the accuracy in the annunciated result, the integration time is varied as a function of the frequency. For the prototype described in this report, the time constant varies from 1 sec to 1 millisec. for frequencies in the range 10 Hz to 10 MHz. This prototype is built entirely of MECL-type integrated circuits from Motorola and is thus contained in two relatively small boxes. (authors) [fr
Ventricular fibrillation time constant for swine

International Nuclear Information System (INIS)

Wu, Jiun-Yan; Sun, Hongyu; Nimunkar, Amit J; Webster, John G; O'Rourke, Ann; Huebner, Shane; Will, James A

2008-01-01

The strength–duration curve for cardiac excitation can be modeled by a parallel resistor–capacitor circuit that has a time constant. Experiments on six pigs were performed by delivering current from the X26 Taser dart at a distance from the heart to cause ventricular fibrillation (VF). The X26 Taser is an electromuscular incapacitation device (EMD), which generates about 50 kV and delivers a pulse train of about 15–19 pulses s −1 with a pulse duration of about 150 µs and peak current about 2 A. Similarly a continuous 60 Hz alternating current of the amplitude required to cause VF was delivered from the same distance. The average current and duration of the current pulse were estimated in both sets of experiments. The strength–duration equation was solved to yield an average time constant of 2.87 ms ± 1.90 (SD). Results obtained may help in the development of safety standards for future electromuscular incapacitation devices (EMDs) without requiring additional animal tests
Simple Model with Time-Varying Fine-Structure ``Constant''

Science.gov (United States)

Berman, M. S.

2009-10-01

Extending the original version written in colaboration with L.A. Trevisan, we study the generalisation of Dirac's LNH, so that time-variation of the fine-structure constant, due to varying electrical and magnetic permittivities is included along with other variations (cosmological and gravitational ``constants''), etc. We consider the present Universe, and also an inflationary scenario. Rotation of the Universe is a given possibility in this model.
Automated real time constant-specificity surveillance for disease outbreaks

Directory of Open Access Journals (Sweden)

Brownstein John S

2007-06-01

Full Text Available Abstract Background For real time surveillance, detection of abnormal disease patterns is based on a difference between patterns observed, and those predicted by models of historical data. The usefulness of outbreak detection strategies depends on their specificity; the false alarm rate affects the interpretation of alarms. Results We evaluate the specificity of five traditional models: autoregressive, Serfling, trimmed seasonal, wavelet-based, and generalized linear. We apply each to 12 years of emergency department visits for respiratory infection syndromes at a pediatric hospital, finding that the specificity of the five models was almost always a non-constant function of the day of the week, month, and year of the study (p Conclusion Modeling the variance of visit patterns enables real-time detection with known, constant specificity at all times. With constant specificity, public health practitioners can better interpret the alarms and better evaluate the cost-effectiveness of surveillance systems.
AC loss time constant measurements on Nb3Al and NbTi multifilamentary superconductors

International Nuclear Information System (INIS)

Painter, T.A.

1988-03-01

The AC loss time constant is a previously univestigated property of Nb 3 Al, a superconductor which, with recent technological developments, shows some advantages over the more commonly used superconductors, NbTi and Nb 3 Sn. Four Nb 3 Al samples with varying twist pitches and one NbTi sample are inductively measured for their AC loss time constants. The measured time constants are compared to the theoretical time constant limits imposed by the limits of the transverse resistivity found by Carr [5] and to the theoretical time constants found using the Bean Model as well as to each other. The measured time constants of the Nb 3 Al samples fall approximately halfway between the theoretical time constant limits, and the measured time constants of the NbTi sample is close to the theoretical lower time constant limit. The Bean Model adequately accounts for the variance of the permeability of the Nb 3 Al superconductor in a background magnetic field. Finally, the measured time constant values of the Nb 3 Al samples vary approximately according to the square of their twist pitch. (author)
Single-crystal elastic constants of natural ettringite

KAUST Repository

Speziale, Sergio

2008-07-01

The single-crystal elastic constants of natural ettringite were determined by Brillouin spectroscopy at ambient conditions. The six non-zero elastic constants of this trigonal mineral are: C11 = 35.1 ± 0.1 GPa, C12 = 21.9 ±0.1 GPa, C13 = 20.0 ± 0.5 GPa, C14 = 0.6 ± 0.2 GPa, C33 = 55 ± 1 GPa, C44 = 11.0 ± 0.2 GPa. The Hill average of the aggregate bulk, shear modulus and the polycrystal Young\\'s modulus and Poisson\\'s ratio are 27.3 ± 0.9 GPa, 9.5 ± 0.8 GPa, 25 ± 2 GPa and 0.34 ± 0.02 respectively. The longitudinal and shear elastic anisotropy are C33/C11 = 0.64 ± 0.01 and C66/C44 =0.60 ± 0.01. The elastic anisotropy in ettringite is connected to its crystallographic structure. Stiff chains of [Al(OH)6]3- octahedra alternating with triplets of Ca2+ in eight-fold coordination run parallel to the c-axis leading to higher stiffness along this direction. The determination of the elastic stiffness tensor can help in the prediction of the early age properties of cement paste when ettringite crystals precipitate and in the modeling of both internal and external sulfate attack when secondary ettringite formation leads to expansion of concrete. © 2008 Elsevier Ltd. All rights reserved.
Single-crystal elastic constants of natural ettringite

KAUST Repository

Speziale, Sergio; Jiang, Fuming; Mao, Zhu; Monteiro, Paulo J.M.; Wenk, Hans-Rudolf; Duffy, Thomas S.; Schilling, Frank R.

2008-01-01

The single-crystal elastic constants of natural ettringite were determined by Brillouin spectroscopy at ambient conditions. The six non-zero elastic constants of this trigonal mineral are: C11 = 35.1 ± 0.1 GPa, C12 = 21.9 ±0.1 GPa, C13 = 20.0 ± 0.5 GPa, C14 = 0.6 ± 0.2 GPa, C33 = 55 ± 1 GPa, C44 = 11.0 ± 0.2 GPa. The Hill average of the aggregate bulk, shear modulus and the polycrystal Young's modulus and Poisson's ratio are 27.3 ± 0.9 GPa, 9.5 ± 0.8 GPa, 25 ± 2 GPa and 0.34 ± 0.02 respectively. The longitudinal and shear elastic anisotropy are C33/C11 = 0.64 ± 0.01 and C66/C44 =0.60 ± 0.01. The elastic anisotropy in ettringite is connected to its crystallographic structure. Stiff chains of [Al(OH)6]3- octahedra alternating with triplets of Ca2+ in eight-fold coordination run parallel to the c-axis leading to higher stiffness along this direction. The determination of the elastic stiffness tensor can help in the prediction of the early age properties of cement paste when ettringite crystals precipitate and in the modeling of both internal and external sulfate attack when secondary ettringite formation leads to expansion of concrete. © 2008 Elsevier Ltd. All rights reserved.
Cryptography in constant parallel time

CERN Document Server

Applebaum, Benny

2013-01-01

Locally computable (NC0) functions are 'simple' functions for which every bit of the output can be computed by reading a small number of bits of their input. The study of locally computable cryptography attempts to construct cryptographic functions that achieve this strong notion of simplicity and simultaneously provide a high level of security. Such constructions are highly parallelizable and they can be realized by Boolean circuits of constant depth.This book establishes, for the first time, the possibility of local implementations for many basic cryptographic primitives such as one-way func
Generating k-independent variables in constant time

DEFF Research Database (Denmark)

Christiani, Tobias Lybecker; Pagh, Rasmus

2014-01-01

The generation of pseudorandom elements over finite fields is fundamental to the time, space and randomness complexity of randomized algorithms and data structures. We consider the problem of generating k-independent random values over a finite field F in a word RAM model equipped with constant...
Dynamically Switching among Bundled and Single Tickets with Time-Dependent Demand Rates

Directory of Open Access Journals (Sweden)

Serhan Duran

2012-01-01

Full Text Available The most important market segmentation in sports and entertainment industry is the competition between customers that buy bundled and single tickets. A common selling practice is starting the selling season with bundled ticket sales and switching to selling single tickets later on. The aim of this practice is to increase the number of customers that buy bundles, which in return increases the load factor of the events with low demand. In this paper, we investigate the effect of time dependent demand on dynamic switching times from bundled to single ticket sales and the potential revenue gain over the case where the demand rate of events is assumed to be constant with time.
Helicopter TEM parameters analysis and system optimization based on time constant

Science.gov (United States)

Xiao, Pan; Wu, Xin; Shi, Zongyang; Li, Jutao; Liu, Lihua; Fang, Guangyou

2018-03-01

Helicopter transient electromagnetic (TEM) method is a kind of common geophysical prospecting method, widely used in mineral detection, underground water exploration and environment investigation. In order to develop an efficient helicopter TEM system, it is necessary to analyze and optimize the system parameters. In this paper, a simple and quantitative method is proposed to analyze the system parameters, such as waveform, power, base frequency, measured field and sampling time. A wire loop model is used to define a comprehensive 'time constant domain' that shows a range of time constant, analogous to a range of conductance, after which the characteristics of the system parameters in this domain is obtained. It is found that the distortion caused by the transmitting base frequency is less than 5% when the ratio of the transmitting period to the target time constant is greater than 6. When the sampling time window is less than the target time constant, the distortion caused by the sampling time window is less than 5%. According to this method, a helicopter TEM system, called CASHTEM, is designed, and flight test has been carried out in the known mining area. The test results show that the system has good detection performance, verifying the effectiveness of the method.
Constant scalar curvature hypersurfaces in extended Schwarzschild space-time

International Nuclear Information System (INIS)

Pareja, M. J.; Frauendiener, J.

2006-01-01

We present a class of spherically symmetric hypersurfaces in the Kruskal extension of the Schwarzschild space-time. The hypersurfaces have constant negative scalar curvature, so they are hyperboloidal in the regions of space-time which are asymptotically flat
The time dependence of rate constants of esub(aq)sup(-) reactions

International Nuclear Information System (INIS)

Burcl, R.; Byakov, V.M.; Grafutin, V.I.

1982-01-01

Published data about the time dependence of rate constants k(esub(aq)sup(-)+Ac) of esub(aq)sup(-) reactions with the acceptor Ac are analyzed, using the results of rate constant k(Ps+Ac) measurements for positronium reactions. It is shown that neither esub(aq)sup(-) nor Ps reaction rate constants depend on time in the observable range. Experimentally found concentration dependence of k(esub(aq)sup(-)+Ac) is due to other factors, connected with the existence of electric charge of esub(aq)sup(-), e.g. ionic strength, tunnelling effect etc. (author)
On time variation of fundamental constants in superstring theories

International Nuclear Information System (INIS)

Maeda, K.I.

1988-01-01

Assuming the action from the string theory and taking into account the dynamical freedom of a dilaton and its coupling to matter fluid, the authors show that fundamental 'constants' in string theories are independent of the 'radius' of the internal space. Since the scalar related to the 'constants' is coupled to the 4-dimensional gravity and matter fluid in the same way as in the Jordan-Brans Dicke theory with ω = -1, it must be massive and can get a mass easily through some symmetry breaking mechanism (e.g. the SUSY breaking due to a gluino condensation). Consequently, time variation of fundamental constants is too small to be observed
Single-machine scheduling with release dates, due dates and family setup times

NARCIS (Netherlands)

Schutten, Johannes M.J.; van de Velde, S.L.; van de Velde, S.L.; Zijm, Willem H.M.

1996-01-01

We address the NP-hard problem of scheduling n independent jobs with release dates, due dates, and family setup times on a single machine to minimize the maximum lateness. This problem arises from the constant tug-of-war going on in manufacturing between efficient production and delivery
Single-machine scheduling with release dates, due dates, and family setup times

NARCIS (Netherlands)

J.M.J. Schutten (Marco); S.L. van de Velde (Steef); W.H.M. Zijm

1996-01-01

textabstractWe address the NP-hard problem of scheduling n independent jobs with release dates, due dates, and family setup times on a single machine to minimize the maximum lateness. This problem arises from the constant tug-of-war going on in manufacturing between efficient production and delivery
Anti-control of chaos of single time-scale brushless DC motor.

Science.gov (United States)

Ge, Zheng-Ming; Chang, Ching-Ming; Chen, Yen-Sheng

2006-09-15

Anti-control of chaos of single time-scale brushless DC motors is studied in this paper. In order to analyse a variety of periodic and chaotic phenomena, we employ several numerical techniques such as phase portraits, bifurcation diagrams and Lyapunov exponents. Anti-control of chaos can be achieved by adding an external constant term or an external periodic term.

Characterizing full matrix constants of piezoelectric single crystals with strong anisotropy using two samples

Science.gov (United States)

Tang, Liguo; Zhang, Yang; Cao, Wenwu

2016-10-01

Although the self-consistency of the full matrix material constants of a piezoelectric sample obtained by the resonant ultrasonic spectroscopy technique can be guaranteed because all constants come from the same sample, it is a great challenge to determine the constants of a piezoelectric sample with strong anisotropy because it might not be possible to identify enough resonance modes from the resonance spectrum. To overcome this difficulty, we developed a strategy to use two samples of similar geometries to increase the number of easy identifiable modes. Unlike the IEEE resonance methods, sample-to-sample variation here is negligible because the two samples have almost the same dimensions, cut from the same specimen and poled under the same conditions. Using this method, we have measured the full matrix constants of a [011]c poled 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 single crystal, which has 17 independent constants. The self-consistency of the obtained results is checked by comparing the calculated elastic stiffness constants c33 D , c44 D , and c55 D with those directly measured ones using the ultrasonic pulse-echo method.
Technique for determination of the time constant for relay radioisotope instruments

International Nuclear Information System (INIS)

Gol'din, M.L.; Shestialtynov, V.K.

1981-01-01

A technique for calculating time constant of a gamma relay used in radio isotope automatics is suggested. It is shown that the time constant of a radioisotope relay device (RRD) mainly depends on parameters of the intergrating circuit ratemeter. Considering the ratemeter as a real communication channel with a limited transmission band, the equation for the active front duration at a ratemeter outlet when applying abrupt voltage to its inlet is obtained. From the complex transmission function of a ratemeter the upper boundary cyclic transmission frequency the substitution of which in the equation of the active front durationg ives the RRD time constant is determined. On the example of calculating the ratemeter for the GR-6 gamma relay a satisfactory coincidence of calculational results with the certificate data is shown [ru
Investigation of Relative Time Constant Influence of Inertial Part of Superheater on Quality of Steam Temperature Control Behind Boiler in Broad Band of Loading Variations

Directory of Open Access Journals (Sweden)

G. T. Kulakov

2008-01-01

Full Text Available The paper is devoted to computational investigation of influence relative time constant of an object which changes in broad band on quality of steam temperature control behind a boiler with due account of value of regulating action in the system with PI- and PID- regulator. The simulation has been based on a single-loop automatic control system (ACS. It has been revealed that the less value of the relative time constant of an object leads to more integral control error in system with PID- regulator while operating external ACS perturbation. Decrease of numerical value of relative time constant of an object while operating external perturbation causes decrease of relative time concerning appearance of maximum dynamic control error from common relative control time.
Time constants and feedback transfer functions of EBR-II subassembly types

International Nuclear Information System (INIS)

Grimm, K.N.; Meneghetti, D.

1986-01-01

Time constants, feedback reactivity transfer functions and power coefficients are calculated for stereotypical subassemblies in the EBR-II reactor. These quantities are calculated from nodal reactivities obtained from a reactor kinetic code analysis for a step change in power. Due to the multiplicity of eigenvalues, there are several time constants for each nodal position in a subassembly. Compared with these calculated values are analytically derived values for the initial node of a given channel
Time constants and feedback transfer functions of EBR-II subassembly types

International Nuclear Information System (INIS)

Grimm, K.N.; Meneghetti, D.

1987-01-01

Time constants, feedback reactivity transfer functions and power coefficients are calculated for stereotypical subassemblies in the EBR-II reactor. These quantities are calculated from nodal reactivities obtained from a reactor kinetic code analysis for a step change in power. Due to the multiplicity of eigenvalues, there are several time constants for each nodal position in a subassembly. Compared with these calculated values are analytically derived values for the initial node of a given channel. (author)
Single-Wire Electric-Field Coupling Power Transmission Using Nonlinear Parity-Time-Symmetric Model with Coupled-Mode Theory

Directory of Open Access Journals (Sweden)

Xujian Shu

2018-03-01

Full Text Available The output power and transmission efficiency of the traditional single-wire electric-field coupling power transmission (ECPT system will drop sharply with the increase of the distance between transmitter and receiver, thus, in order to solve the above problem, in this paper, a new nonlinear parity-time (PT-symmetric model for single-wire ECPT system based on coupled-mode theory (CMT is proposed. The proposed model for single-wire ECPT system not only achieves constant output power but also obtains a high constant transmission efficiency against variable distance, and the steady-state characteristics of the single-wire ECPT system are analyzed. Based on the theoretical analysis and circuit simulation, it shows that the transmission efficiency with constant output power remains 60% over a transmission distance of approximately 34 m without the need for any tuning. Furthermore, the application of a nonlinear PT-symmetric circuit based on CMT enables robust electric power transfer to moving devices or vehicles.
Fuzzy logic estimator of rotor time constant in induction motors

Energy Technology Data Exchange (ETDEWEB)

Alminoja, J. [Tampere University of Technology (Finland). Control Engineering Laboratory; Koivo, H. [Helsinki University of Technology, Otaniemi (Finland). Control Engineering Laboratory

1997-12-31

Vector control of AC machines is a well-known and widely used technique in induction machine control. It offers an exact method for speed control of induction motors, but it is also sensitive to the changes in machine parameters. E.g. rotor time constant has a strong dependence on temperature. In this paper a fuzzy logic estimator is developed, with which the rotor time constant can be estimated when the machine has a load. It is more simple than the estimators proposed in the literature. The fuzzy estimator is tested by simulation when step-wise abrupt changes and slow drifting occurs. (orig.) 7 refs.
Dependence of the time-constant of a fuel rod on different design and operational parameters

International Nuclear Information System (INIS)

Elenkov, D.; Lassmann, K.; Schubert, A.; Laar, J. van de

2001-01-01

The temperature response during a reactor shutdown has been measured for many years in the OECD-Halden Project. It has been shown that the complicated shutdown processes can be characterized by a time constant τ which depends on different fuel design and operational parameters, such as fuel geometry, gap size, fill gas pressure and composition, burnup and linear heat rate. In the paper the concept of a time constant is analyzed and the dependence of the time constant on various parameters is investigated analytically. Measured time constants for different designs and conditions are compared with those derived from calculations of the TRANSURANUS code. Employing standard models results in a systematic underprediction of the time constant, i.e. the heat transfer during shutdown is overestimated. (author)
Determination of time constants of reactor pressure and temperature sensors: the dynamic data system method

International Nuclear Information System (INIS)

Wu, S.M.; Hsu, M.C.; Chow, M.C.

1979-01-01

A new modeling technique is introduced for on-line sensor time constant identification, both for the resistance temperature detector (RTD) and for the pressure sensor using power plant operational data. The sensor's time constant is estimated from a real characteristic root of the fitted autoregressive moving average model. The RTD's time constant values were identified to be 8.4 s, with a standard deviation of 1.2 s. The pressure sensor time constant was identified to be 28.6 ms, with a standard deviation of 3.5 ms
Delay of constant light-induced persistent vaginal estrus by 24-hour time cues in rats.

Science.gov (United States)

Weber, A L; Adler, N T

1979-04-20

The normal ovarian cycle of female rats is typically replaced by persistent estrus when these animals are housed under constant light. Evidence presented here shows that the maintenance of periodicity in the environment can at least delay (if not prevent) the photic induction of persistent vaginal estrus. Female rats in constant light were exposed to vaginal smearing at random times or at the same time every day. In another experiment, female rats were exposed to either constant bright light, constant dim light, or a 24-hour photic cycle of bright and dim light. The onset of persistent vaginal estrus was delayed in rats exposed to 24-hour time cues even though the light intensities were the same as or greater than those for the aperiodic control groups. The results suggest that the absence of 24-hour time cues in constant light contributes to the induction of persistent estrus.
Isothermal titration calorimetry in nanoliter droplets with subsecond time constants.

Science.gov (United States)

Lubbers, Brad; Baudenbacher, Franz

2011-10-15

We reduced the reaction volume in microfabricated suspended-membrane titration calorimeters to nanoliter droplets and improved the sensitivities to below a nanowatt with time constants of around 100 ms. The device performance was characterized using exothermic acid-base neutralizations and a detailed numerical model. The finite element based numerical model allowed us to determine the sensitivities within 1% and the temporal dynamics of the temperature rise in neutralization reactions as a function of droplet size. The model was used to determine the optimum calorimeter design (membrane size and thickness, junction area, and thermopile thickness) and sensitivities for sample volumes of 1 nL for silicon nitride and polymer membranes. We obtained a maximum sensitivity of 153 pW/(Hz)(1/2) for a 1 μm SiN membrane and 79 pW/(Hz)(1/2) for a 1 μm polymer membrane. The time constant of the calorimeter system was determined experimentally using a pulsed laser to increase the temperature of nanoliter sample volumes. For a 2.5 nanoliter sample volume, we experimentally determined a noise equivalent power of 500 pW/(Hz)(1/2) and a 1/e time constant of 110 ms for a modified commercially available infrared sensor with a thin-film thermopile. Furthermore, we demonstrated detection of 1.4 nJ reaction energies from injection of 25 pL of 1 mM HCl into a 2.5 nL droplet of 1 mM NaOH. © 2011 American Chemical Society
Estimation of the Plant Time Constant of Current-Controlled Voltage Source Converters

DEFF Research Database (Denmark)

Vidal, Ana; Yepes, Alejandro G.; Malvar, Jano

2014-01-01

Precise knowledge of the plant time constant is essential to perform a thorough analysis of the current control loop in voltage source converters (VSCs). As the loop behavior can be significantly influenced by the VSC working conditions, the effects associated to converter losses should be included...... in the model, through an equivalent series resistance. In a recent work, an algorithm to identify this parameter was developed, considering the inductance value as known and practically constant. Nevertheless, the plant inductance can also present important uncertainties with respect to the inductance...... of the VSC interface filter measured at rated conditions. This paper extends that method so that both parameters of the plant time constant (resistance and inductance) are estimated. Such enhancement is achieved through the evaluation of the closed-loop transient responses of both axes of the synchronous...
Time of flight and range of the motion of a projectile in a constant gravitational field

Directory of Open Access Journals (Sweden)

P. A. Karkantzakos

2009-01-01

Full Text Available In this paper we study the classical problem of the motion of a projectile in a constant gravitational field under the influenceof a retarding force proportional to the velocity. Specifically, we express the time of flight, the time of fall and the range ofthe motion as a function of the constant of resistance per unit mass of the projectile. We also prove that the time of fall isgreater than the time of rise with the exception of the case of zero constant of resistance where we have equality. Finally weprove a formula from which we can compute the constant of resistance per unit mass of the projectile from time of flight andrange of the motion when the acceleration due to gravity and the initial velocity of the projectile are known.
Running vacuum in the Universe and the time variation of the fundamental constants of Nature

Energy Technology Data Exchange (ETDEWEB)

Fritzsch, Harald [Nanyang Technological University, Institute for Advanced Study, Singapore (Singapore); Universitaet Muenchen, Physik-Department, Munich (Germany); Sola, Joan [Nanyang Technological University, Institute for Advanced Study, Singapore (Singapore); Universitat de Barcelona, Departament de Fisica Quantica i Astrofisica, Barcelona, Catalonia (Spain); Universitat de Barcelona (ICCUB), Institute of Cosmos Sciences, Barcelona, Catalonia (Spain); Nunes, Rafael C. [Universidade Federal de Juiz de Fora, Dept. de Fisica, Juiz de Fora, MG (Brazil)

2017-03-15

We compute the time variation of the fundamental constants (such as the ratio of the proton mass to the electron mass, the strong coupling constant, the fine-structure constant and Newton's constant) within the context of the so-called running vacuum models (RVMs) of the cosmic evolution. Recently, compelling evidence has been provided that these models are able to fit the main cosmological data (SNIa+BAO+H(z)+LSS+BBN+CMB) significantly better than the concordance ΛCDM model. Specifically, the vacuum parameters of the RVM (i.e. those responsible for the dynamics of the vacuum energy) prove to be nonzero at a confidence level >or similar 3σ. Here we use such remarkable status of the RVMs to make definite predictions on the cosmic time variation of the fundamental constants. It turns out that the predicted variations are close to the present observational limits. Furthermore, we find that the time evolution of the dark matter particle masses should be crucially involved in the total mass variation of our Universe. A positive measurement of this kind of effects could be interpreted as strong support to the ''micro-macro connection'' (viz. the dynamical feedback between the evolution of the cosmological parameters and the time variation of the fundamental constants of the microscopic world), previously proposed by two of us (HF and JS). (orig.)
Dynamical black rings with a positive cosmological constant

International Nuclear Information System (INIS)

Kimura, Masashi

2009-01-01

We construct dynamical black ring solutions in the five-dimensional Einstein-Maxwell system with a positive cosmological constant and investigate the geometrical structure. The solutions describe the physical process such that a thin black ring at early time shrinks and changes into a single black hole as time increases. We also discuss the multiblack rings and the coalescence of them.
Variable dose rate single-arc IMAT delivered with a constant dose rate and variable angular spacing

International Nuclear Information System (INIS)

Tang, Grace; Earl, Matthew A; Yu, Cedric X

2009-01-01

Single-arc intensity-modulated arc therapy (IMAT) has gained worldwide interest in both research and clinical implementation due to its superior plan quality and delivery efficiency. Single-arc IMAT techniques such as the Varian RapidArc(TM) deliver conformal dose distributions to the target in one single gantry rotation, resulting in a delivery time in the order of 2 min. The segments in these techniques are evenly distributed within an arc and are allowed to have different monitor unit (MU) weightings. Therefore, a variable dose-rate (VDR) is required for delivery. Because the VDR requirement complicates the control hardware and software of the linear accelerators (linacs) and prevents most existing linacs from delivering IMAT, we propose an alternative planning approach for IMAT using constant dose-rate (CDR) delivery with variable angular spacing. We prove the equivalence by converting VDR-optimized RapidArc plans to CDR plans, where the evenly spaced beams in the VDR plan are redistributed to uneven spacing such that the segments with larger MU weighting occupy a greater angular interval. To minimize perturbation in the optimized dose distribution, the angular deviation of the segments was restricted to ≤± 5 deg. This restriction requires the treatment arc to be broken into multiple sectors such that the local MU fluctuation within each sector is reduced, thereby lowering the angular deviation of the segments during redistribution. The converted CDR plans were delivered with a single gantry sweep as in the VDR plans but each sector was delivered with a different value of CDR. For four patient cases, including two head-and-neck, one brain and one prostate, all CDR plans developed with the variable spacing scheme produced similar dose distributions to the original VDR plans. For plans with complex angular MU distributions, the number of sectors increased up to four in the CDR plans in order to maintain the original plan quality. Since each sector was
Chemical exchange effects during refocusing pulses in constant-time CPMG relaxation dispersion experiments

International Nuclear Information System (INIS)

Myint, Wazo; Ishima, Rieko

2009-01-01

In the analysis of the constant-time Carr-Purcell-Meiboom-Gill (CT-CPMG) relaxation dispersion experiment, chemical exchange parameters, such as rate of exchange and population of the exchanging species, are typically optimized using equations that predict experimental relaxation rates recorded as a function of effective field strength. In this process, the effect of chemical exchange during the CPMG pulses is typically assumed to be the same as during the free-precession. This approximation may introduce systematic errors into the analysis of data because the number of CPMG pulses is incremented during the constant-time relaxation period, and the total pulse duration therefore varies as a function of the effective field strength. In order to estimate the size of such errors, we simulate the time-dependence of magnetization during the entire constant time period, explicitly taking into account the effect of the CPMG pulses on the spin relaxation rate. We show that in general the difference in the relaxation dispersion profile calculated using a practical pulse width from that calculated using an extremely short pulse width is small, but under certain circumstances can exceed 1 s -1 . The difference increases significantly when CPMG pulses are miscalibrated
Calculations of single crystal elastic constants for yttria partially stabilised zirconia from powder diffraction data

Science.gov (United States)

Lunt, A. J. G.; Xie, M. Y.; Baimpas, N.; Zhang, S. Y.; Kabra, S.; Kelleher, J.; Neo, T. K.; Korsunsky, A. M.

2014-08-01

Yttria Stabilised Zirconia (YSZ) is a tough, phase-transforming ceramic that finds use in a wide range of commercial applications from dental prostheses to thermal barrier coatings. Micromechanical modelling of phase transformation can deliver reliable predictions in terms of the influence of temperature and stress. However, models must rely on the accurate knowledge of single crystal elastic stiffness constants. Some techniques for elastic stiffness determination are well-established. The most popular of these involve exploiting frequency shifts and phase velocities of acoustic waves. However, the application of these techniques to YSZ can be problematic due to the micro-twinning observed in larger crystals. Here, we propose an alternative approach based on selective elastic strain sampling (e.g., by diffraction) of grain ensembles sharing certain orientation, and the prediction of the same quantities by polycrystalline modelling, for example, the Reuss or Voigt average. The inverse problem arises consisting of adjusting the single crystal stiffness matrix to match the polycrystal predictions to observations. In the present model-matching study, we sought to determine the single crystal stiffness matrix of tetragonal YSZ using the results of time-of-flight neutron diffraction obtained from an in situ compression experiment and Finite Element modelling of the deformation of polycrystalline tetragonal YSZ. The best match between the model predictions and observations was obtained for the optimized stiffness values of C11 = 451, C33 = 302, C44 = 39, C66 = 82, C12 = 240, and C13 = 50 (units: GPa). Considering the significant amount of scatter in the published literature data, our result appears reasonably consistent.
Ultrafast time measurements by time-correlated single photon counting coupled with superconducting single photon detector

Energy Technology Data Exchange (ETDEWEB)

Shcheslavskiy, V., E-mail: vis@becker-hickl.de; Becker, W. [Becker & Hickl GmbH, Nahmitzer Damm 30, 12277 Berlin (Germany); Morozov, P.; Divochiy, A. [Scontel, Rossolimo St., 5/22-1, Moscow 119021 (Russian Federation); Vakhtomin, Yu. [Scontel, Rossolimo St., 5/22-1, Moscow 119021 (Russian Federation); Moscow State Pedagogical University, 1/1 M. Pirogovskaya St., Moscow 119991 (Russian Federation); Smirnov, K. [Scontel, Rossolimo St., 5/22-1, Moscow 119021 (Russian Federation); Moscow State Pedagogical University, 1/1 M. Pirogovskaya St., Moscow 119991 (Russian Federation); National Research University Higher School of Economics, 20 Myasnitskaya St., Moscow 101000 (Russian Federation)

2016-05-15

Time resolution is one of the main characteristics of the single photon detectors besides quantum efficiency and dark count rate. We demonstrate here an ultrafast time-correlated single photon counting (TCSPC) setup consisting of a newly developed single photon counting board SPC-150NX and a superconducting NbN single photon detector with a sensitive area of 7 × 7 μm. The combination delivers a record instrument response function with a full width at half maximum of 17.8 ps and system quantum efficiency ∼15% at wavelength of 1560 nm. A calculation of the root mean square value of the timing jitter for channels with counts more than 1% of the peak value yielded about 7.6 ps. The setup has also good timing stability of the detector–TCSPC board.
Time constants and feedback transfer functions of EBR-II [Experimental Breeder Reactor] subassembly types

International Nuclear Information System (INIS)

Grimm, K.N.; Meneghetti, D.

1986-09-01

Time constants, feedback reactivity transfer functions and power coefficients are calculated for stereotypical subassemblies in the EBR-II reactor. These quantities are calculated from nodal reactivities obtained from a reactor kinetic code analysis for a step change in power. Due to the multiplicity of eigenvalues, there are several time constants for each nodal position in a subassembly. Compared with these calculated values are analytically derived values for the initial node of a given channel

Approach to analysis of single nucleotide polymorphisms by automated constant denaturant capillary electrophoresis

International Nuclear Information System (INIS)

Bjoerheim, Jens; Abrahamsen, Torveig Weum; Kristensen, Annette Torgunrud; Gaudernack, Gustav; Ekstroem, Per O.

2003-01-01

Melting gel techniques have proven to be amenable and powerful tools in point mutation and single nucleotide polymorphism (SNP) analysis. With the introduction of commercially available capillary electrophoresis instruments, a partly automated platform for denaturant capillary electrophoresis with potential for routine screening of selected target sequences has been established. The aim of this article is to demonstrate the use of automated constant denaturant capillary electrophoresis (ACDCE) in single nucleotide polymorphism analysis of various target sequences. Optimal analysis conditions for different single nucleotide polymorphisms on ACDCE are evaluated with the Poland algorithm. Laboratory procedures include only PCR and electrophoresis. For direct genotyping of individual SNPs, the samples are analyzed with an internal standard and the alleles are identified by co-migration of sample and standard peaks. In conclusion, SNPs suitable for melting gel analysis based on theoretical thermodynamics were separated by ACDCE under appropriate conditions. With this instrumentation (ABI 310 Genetic Analyzer), 48 samples could be analyzed without any intervention. Several institutions have capillary instrumentation in-house, thus making this SNP analysis method accessible to large groups of researchers without any need for instrument modification
Near constant-time optimal piecewise LDR to HDR inverse tone mapping

Science.gov (United States)

Chen, Qian; Su, Guan-Ming; Yin, Peng

2015-02-01

In a backward compatible HDR image/video compression, it is a general approach to reconstruct HDR from compressed LDR as a prediction to original HDR, which is referred to as inverse tone mapping. Experimental results show that 2- piecewise 2nd order polynomial has the best mapping accuracy than 1 piece high order or 2-piecewise linear, but it is also the most time-consuming method because to find the optimal pivot point to split LDR range to 2 pieces requires exhaustive search. In this paper, we propose a fast algorithm that completes optimal 2-piecewise 2nd order polynomial inverse tone mapping in near constant time without quality degradation. We observe that in least square solution, each entry in the intermediate matrix can be written as the sum of some basic terms, which can be pre-calculated into look-up tables. Since solving the matrix becomes looking up values in tables, computation time barely differs regardless of the number of points searched. Hence, we can carry out the most thorough pivot point search to find the optimal pivot that minimizes MSE in near constant time. Experiment shows that our proposed method achieves the same PSNR performance while saving 60 times computation time compared to the traditional exhaustive search in 2-piecewise 2nd order polynomial inverse tone mapping with continuous constraint.
Methodology of measurement of thermal neutron time decay constant in Canberra 35+ MCA system

International Nuclear Information System (INIS)

Drozdowicz, K.; Gabanska, B.; Igielski, A.; Krynicka, E.; Woznicka, U.

1993-01-01

A method of the thermal neutron time decay constant measurement in small bounded media is presented. A 14 MeV pulsed neutron generator is the neutron source. The system of recording of a die-away curve of thermal neutrons consists of a 3 He detector and of a multichannel time analyzer based on analyzer Canberra 35+ with multi scaler module MCS 7880 (microsecond range). Optimum parameters for the measuring system are considered. Experimental verification of a dead time of the instrumentation system is made and a count-loss correction is incorporated into the data treatment. An attention is paid to evaluate with a high accuracy the fundamental mode decay constant of the registered decaying curve. A new procedure of the determination of the decay constant by a multiple recording of the die-away curve is presented and results of test measurements are shown. (author). 11 refs, 12 figs, 4 tabs
Methodology of measurement of thermal neutron time decay constant in Canberra 35+ MCA system

Energy Technology Data Exchange (ETDEWEB)

Drozdowicz, K; Gabanska, B; Igielski, A; Krynicka, E; Woznicka, U [Institute of Nuclear Physics, Cracow (Poland)

1994-12-31

A method of the thermal neutron time decay constant measurement in small bounded media is presented. A 14 MeV pulsed neutron generator is the neutron source. The system of recording of a die-away curve of thermal neutrons consists of a {sup 3}He detector and of a multichannel time analyzer based on analyzer Canberra 35+ with multi scaler module MCS 7880 (microsecond range). Optimum parameters for the measuring system are considered. Experimental verification of a dead time of the instrumentation system is made and a count-loss correction is incorporated into the data treatment. An attention is paid to evaluate with a high accuracy the fundamental mode decay constant of the registered decaying curve. A new procedure of the determination of the decay constant by a multiple recording of the die-away curve is presented and results of test measurements are shown. (author). 11 refs, 12 figs, 4 tabs.
Methodology of measurement of thermal neutron time decay constant in Canberra 35+ MCA system

Energy Technology Data Exchange (ETDEWEB)

Drozdowicz, K.; Gabanska, B.; Igielski, A.; Krynicka, E.; Woznicka, U. [Institute of Nuclear Physics, Cracow (Poland)

1993-12-31

A method of the thermal neutron time decay constant measurement in small bounded media is presented. A 14 MeV pulsed neutron generator is the neutron source. The system of recording of a die-away curve of thermal neutrons consists of a {sup 3}He detector and of a multichannel time analyzer based on analyzer Canberra 35+ with multi scaler module MCS 7880 (microsecond range). Optimum parameters for the measuring system are considered. Experimental verification of a dead time of the instrumentation system is made and a count-loss correction is incorporated into the data treatment. An attention is paid to evaluate with a high accuracy the fundamental mode decay constant of the registered decaying curve. A new procedure of the determination of the decay constant by a multiple recording of the die-away curve is presented and results of test measurements are shown. (author). 11 refs, 12 figs, 4 tabs.
Construction of Lines of Constant Density and Constant Refractive Index for Ternary Liquid Mixtures.

Science.gov (United States)

Tasic, Aleksandar Z.; Djordjevic, Bojan D.

1983-01-01

Demonstrates construction of density constant and refractive index constant lines in triangular coordinate system on basis of systematic experimental determinations of density and refractive index for both homogeneous (single-phase) ternary liquid mixtures (of known composition) and the corresponding binary compositions. Background information,…
Probing quantum entanglement in the Schwarzschild space-time beyond the single-mode approximation

Science.gov (United States)

He, Juan; Ding, Zhi-Yong; Ye, Liu

2018-05-01

In this paper, we deduce the vacuum structure for Dirac fields in the background of Schwarzschild space-time beyond the single-mode approximation and discuss the performance of quantum entanglement between particle and antiparticle modes of a Dirac field with Hawking effect. It is shown that Hawking radiation does not always destroy the physically accessible entanglement, and entanglement amplification may happen in some cases. This striking result is different from that of the single-mode approximation, which holds that the Hawking radiation can only destroy entanglement. Lastly, we analyze the physically accessible entanglement relation outside the event horizon and demonstrate that the monogamy inequality is constantly established regardless of the choice of given parameters.
New constraints on time-dependent variations of fundamental constants using Planck data

Science.gov (United States)

Hart, Luke; Chluba, Jens

2018-02-01

Observations of the cosmic microwave background (CMB) today allow us to answer detailed questions about the properties of our Universe, targeting both standard and non-standard physics. In this paper, we study the effects of varying fundamental constants (i.e. the fine-structure constant, αEM, and electron rest mass, me) around last scattering using the recombination codes COSMOREC and RECFAST++. We approach the problem in a pedagogical manner, illustrating the importance of various effects on the free electron fraction, Thomson visibility function and CMB power spectra, highlighting various degeneracies. We demonstrate that the simpler RECFAST++ treatment (based on a three-level atom approach) can be used to accurately represent the full computation of COSMOREC. We also include explicit time-dependent variations using a phenomenological power-law description. We reproduce previous Planck 2013 results in our analysis. Assuming constant variations relative to the standard values, we find the improved constraints αEM/αEM, 0 = 0.9993 ± 0.0025 (CMB only) and me/me, 0 = 1.0039 ± 0.0074 (including BAO) using Planck 2015 data. For a redshift-dependent variation, αEM(z) = αEM(z0) [(1 + z)/1100]p with αEM(z0) ≡ αEM, 0 at z0 = 1100, we obtain p = 0.0008 ± 0.0025. Allowing simultaneous variations of αEM(z0) and p yields αEM(z0)/αEM, 0 = 0.9998 ± 0.0036 and p = 0.0006 ± 0.0036. We also discuss combined limits on αEM and me. Our analysis shows that existing data are not only sensitive to the value of the fundamental constants around recombination but also its first time derivative. This suggests that a wider class of varying fundamental constant models can be probed using the CMB.
Calculations of single crystal elastic constants for yttria partially stabilised zirconia from powder diffraction data

Energy Technology Data Exchange (ETDEWEB)

Lunt, A. J. G., E-mail: alexander.lunt@eng.ox.ac.uk; Xie, M. Y.; Baimpas, N.; Korsunsky, A. M. [Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ (United Kingdom); Zhang, S. Y.; Kabra, S.; Kelleher, J. [ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell, Oxford OX11 0QX (United Kingdom); Neo, T. K. [Specialist Dental Group, Mount Elizabeth Orchard, 3 Mount Elizabeth, #08-03/08-08/08-10, Singapore 228510 (Singapore)

2014-08-07

Yttria Stabilised Zirconia (YSZ) is a tough, phase-transforming ceramic that finds use in a wide range of commercial applications from dental prostheses to thermal barrier coatings. Micromechanical modelling of phase transformation can deliver reliable predictions in terms of the influence of temperature and stress. However, models must rely on the accurate knowledge of single crystal elastic stiffness constants. Some techniques for elastic stiffness determination are well-established. The most popular of these involve exploiting frequency shifts and phase velocities of acoustic waves. However, the application of these techniques to YSZ can be problematic due to the micro-twinning observed in larger crystals. Here, we propose an alternative approach based on selective elastic strain sampling (e.g., by diffraction) of grain ensembles sharing certain orientation, and the prediction of the same quantities by polycrystalline modelling, for example, the Reuss or Voigt average. The inverse problem arises consisting of adjusting the single crystal stiffness matrix to match the polycrystal predictions to observations. In the present model-matching study, we sought to determine the single crystal stiffness matrix of tetragonal YSZ using the results of time-of-flight neutron diffraction obtained from an in situ compression experiment and Finite Element modelling of the deformation of polycrystalline tetragonal YSZ. The best match between the model predictions and observations was obtained for the optimized stiffness values of C11 = 451, C33 = 302, C44 = 39, C66 = 82, C12 = 240, and C13 = 50 (units: GPa). Considering the significant amount of scatter in the published literature data, our result appears reasonably consistent.
Newtonian cosmology with a time-varying constant of gravitation

International Nuclear Information System (INIS)

McVittie, G.C.

1978-01-01

Newtonian cosmology is based on the Eulerian equations of fluid mechanics combined with Poisson's equation modified by the introduction of a time-varying G. Spherically symmetric model universes are worked out with instantaneously uniform densities. They are indeterminate unless instantaneous uniformity of the pressure is imposed. When G varies as an inverse power of the time, the models can in some cases be shown to depend on the solution of a second-order differential equation which also occurs in the Friedmann models of general relativity. In Section 3, a method for 'passing through' a singularity of this equation is proposed which entails making four arbitrary mathematical assumptions. When G varies as (time) -1 , models with initially cycloidal motion are possible, each cycle becoming longer as time progresses. Finally, gravitation becomes so weak that the model expands to infinity. Kinetic and potential energies for the whole model are derived from the basic equations; their sum is not constant. (author)
The relationship between elastic constants and structure of shock waves in a zinc single crystal

Science.gov (United States)

Krivosheina, M. N.; Kobenko, S. V.; Tuch, E. V.

2017-12-01

The paper provides a 3D finite element simulation of shock-loaded anisotropic single crystals on the example of a Zn plate under impact using a mathematical model, which allows for anisotropy in hydrostatic stress and wave velocities in elastic and plastic ranges. The simulation results agree with experimental data, showing the absence of shock wave splitting into an elastic precursor and a plastic wave in Zn single crystals impacted in the [0001] direction. It is assumed that the absence of an elastic precursor under impact loading of a zinc single crystal along the [0001] direction is determined by the anomalously large ratio of the c/a-axes and close values of the propagation velocities of longitudinal and bulk elastic waves. It is shown that an increase in only one elastic constant along the [0001] direction results in shock wave splitting into an elastic precursor and a shock wave of "plastic" compression.
Queueing systems with constant service time and evaluation of M/D/1,k

DEFF Research Database (Denmark)

Iversen, Villy Bæk

1997-01-01

Systems with constant service times have the particular property that the customers leave the servers in the same order in which they areaccepted for service. Probabilitites of integral waiting times can be expressed by the state probabilities, and non-integral waiting timescan be expressed...
McBits: fast constant-time code-based cryptography

NARCIS (Netherlands)

Bernstein, D.J.; Chou, T.; Schwabe, P.

2015-01-01

This paper presents extremely fast algorithms for code-based public-key cryptography, including full protection against timing attacks. For example, at a 2^128 security level, this paper achieves a reciprocal decryption throughput of just 60493 cycles (plus cipher cost etc.) on a single Ivy Bridge
Are fundamental constants really constant

International Nuclear Information System (INIS)

Norman, E.B.

1986-01-01

Reasons for suspecting that fundamental constants might change with time are reviewed. Possible consequences of such variations are examined. The present status of experimental tests of these ideas is discussed
Molecular equilibrium structures from experimental rotational constants and calculated vibration-rotation interaction constants

DEFF Research Database (Denmark)

Pawlowski, F; Jorgensen, P; Olsen, Jeppe

2002-01-01

A detailed study is carried out of the accuracy of molecular equilibrium geometries obtained from least-squares fits involving experimental rotational constants B(0) and sums of ab initio vibration-rotation interaction constants alpha(r)(B). The vibration-rotation interaction constants have been...... calculated for 18 single-configuration dominated molecules containing hydrogen and first-row atoms at various standard levels of ab initio theory. Comparisons with the experimental data and tests for the internal consistency of the calculations show that the equilibrium structures generated using Hartree......-Fock vibration-rotation interaction constants have an accuracy similar to that obtained by a direct minimization of the CCSD(T) energy. The most accurate vibration-rotation interaction constants are those calculated at the CCSD(T)/cc-pVQZ level. The equilibrium bond distances determined from these interaction...
A new variable interval schedule with constant hazard rate and finite time range.

Science.gov (United States)

Bugallo, Mehdi; Machado, Armando; Vasconcelos, Marco

2018-05-27

We propose a new variable interval (VI) schedule that achieves constant probability of reinforcement in time while using a bounded range of intervals. By sampling each trial duration from a uniform distribution ranging from 0 to 2 T seconds, and then applying a reinforcement rule that depends linearly on trial duration, the schedule alternates reinforced and unreinforced trials, each less than 2 T seconds, while preserving a constant hazard function. © 2018 Society for the Experimental Analysis of Behavior.
Consideration of demand rate in overall equipment effetiveness (OEE on equipment with constant process time

Directory of Open Access Journals (Sweden)

Perumal Puvanasvaran

2013-06-01

Full Text Available Purpose: The paper is primarily done on the purpose of introducing new concept in defining the Overall Equipment Effectiveness (OEE with the consideration of both machine utilization and customer demand requested. Previous literature concerning the limitation and difficulty of OEE implementation has been investigated in order to track out the potential opportunities to be improved, since the OEE has been widely accepted by most of the industries regardless their manufacturing environment.Design/methodology/approach: The paper is conducting the study based on literature review and the computerized data collection. In details, the novel definition and method of processing the computerized data are all interpreted based on similar studies performed by others and supported by related journals in proving the validation of the output. Over the things, the computerized data are the product amount and total time elapsed on each production which is automatically recorded by the system at the manufacturing site.Findings: The finding of this paper is firstly the exposure and emphasis of limitation exists in current implementation of OEE, which showing that high utilization of the machine is encouraged regardless of the customer demand and is having conflict with the inventory handling cost. This is certainly obvious with overproduction issue especially during low customer demand period. The second limitation in general implementation of OEE is the difficulty in obtaining the ideal cycle time, especially those equipments with constant process time. The section of this paper afterward comes out with the proposed solution in fixing this problem through the definition of performance ratio and then usage of this definition in measuring the machine utilization from time to time. Before this, the time available for the production is calculated incorporating the availability of OEE, which is then used to get the Takt time.Research limitations/implications: Future
Potential constants and centrifugal distortion constants of octahedral hexafluoride molecules

Energy Technology Data Exchange (ETDEWEB)

Manivannan, G [Government Thirumagal Mill' s Coll., Gudiyattam, Tamil Nadu (India)

1981-04-01

The kinetic constants method outlined by Thirugnanasambandham (1964) based on Wilson's (1955) group theory has been adapted in evaluating the potential constants for SF/sub 6/, SeF/sub 6/, WF/sub 6/, IrF/sub 6/, UF/sub 6/, NpF/sub 6/, and PuF/sub 6/ using the experimentally observed vibrational frequency data. These constants are used to calculate the centrifugal distortion constants for the first time.
Computing magnetic anisotropy constants of single molecule magnets

Indian Academy of Sciences (India)

Administrator

Treating the anisotropy Hamiltonian as perturbation, we compute ... The dependence of DM on the energy gap between the ground and the excited states in both the systems has also been studied by using different sets of exchange constants.
Acceleration-enlarged symmetries in nonrelativistic space-time with a cosmological constant TH1"-->

Science.gov (United States)

Lukierski, J.; Stichel, P. C.; Zakrzewski, W. J.

2008-05-01

By considering the nonrelativistic limit of de Sitter geometry one obtains the nonrelativistic space-time with a cosmological constant and Newton Hooke (NH) symmetries. We show that the NH symmetry algebra can be enlarged by the addition of the constant acceleration generators and endowed with central extensions (one in any dimension (D) and three in D=(2+1)). We present a classical Lagrangian and Hamiltonian framework for constructing models quasi-invariant under enlarged NH symmetries that depend on three parameters described by three nonvanishing central charges. The Hamiltonian dynamics then splits into external and internal sectors with new noncommutative structures of external and internal phase spaces. We show that in the limit of vanishing cosmological constant the system reduces to the one, which possesses acceleration-enlarged Galilean symmetries.

Quantum supremacy in constant-time measurement-based computation: A unified architecture for sampling and verification

Science.gov (United States)

Miller, Jacob; Sanders, Stephen; Miyake, Akimasa

2017-12-01

While quantum speed-up in solving certain decision problems by a fault-tolerant universal quantum computer has been promised, a timely research interest includes how far one can reduce the resource requirement to demonstrate a provable advantage in quantum devices without demanding quantum error correction, which is crucial for prolonging the coherence time of qubits. We propose a model device made of locally interacting multiple qubits, designed such that simultaneous single-qubit measurements on it can output probability distributions whose average-case sampling is classically intractable, under similar assumptions as the sampling of noninteracting bosons and instantaneous quantum circuits. Notably, in contrast to these previous unitary-based realizations, our measurement-based implementation has two distinctive features. (i) Our implementation involves no adaptation of measurement bases, leading output probability distributions to be generated in constant time, independent of the system size. Thus, it could be implemented in principle without quantum error correction. (ii) Verifying the classical intractability of our sampling is done by changing the Pauli measurement bases only at certain output qubits. Our usage of random commuting quantum circuits in place of computationally universal circuits allows a unique unification of sampling and verification, so they require the same physical resource requirements in contrast to the more demanding verification protocols seen elsewhere in the literature.
Experimental Determination of the Avogadro Constant

Indian Academy of Sciences (India)

mental physical constant such as charge of an electron or the. Boltzmann constant ... ideas was that the number of particles or molecules in a gas of given volume could not ... knowledge of at least one property of a single molecule. Loschmidt ...
Procedural Adaptations for Use of Constant Time Delay to Teach Highly Motivating Words to Beginning Braille Readers

Science.gov (United States)

Ivy, Sarah E.; Guerra, Jennifer A.; Hatton, Deborah D.

2017-01-01

Introduction: Constant time delay is an evidence-based practice to teach sight word recognition to students with a variety of disabilities. To date, two studies have documented its effectiveness for teaching braille. Methods: Using a multiple-baseline design, we evaluated the effectiveness of constant time delay to teach highly motivating words to…
Certificateless Public Auditing Protocol with Constant Verification Time

Directory of Open Access Journals (Sweden)

Dongmin Kim

2017-01-01

Full Text Available To provide the integrity of outsourced data in the cloud storage services, many public auditing schemes which allow a user to check the integrity of the outsourced data have been proposed. Since most of the schemes are constructed on Public Key Infrastructure (PKI, they suffer from several concerns like management of certificates. To resolve the problems, certificateless public auditing schemes also have been studied in recent years. In this paper, we propose a certificateless public auditing scheme which has the constant-time verification algorithm. Therefore, our scheme is more efficient than previous certificateless public auditing schemes. To prove the security of our certificateless public auditing scheme, we first define three formal security models and prove the security of our scheme under the three security models.
Method for Determining the Time Constants Characterizing the Intensity of Steel Mixing in Continuous Casting Tundish

Directory of Open Access Journals (Sweden)

Pieprzyca J.

2015-04-01

Full Text Available A common method used in identification of hydrodynamics phenomena occurring in Continuous Casting (CC device's tundish is to determine the RTD curves of time. These curves allows to determine the way of the liquid steel flowing and mixing in the tundish. These can be identified either as the result of numerical simulation or by the experiments - as the result of researching the physical models. Special problem is to objectify it while conducting physical research. It is necessary to precisely determine the time constants which characterize researched phenomena basing on the data acquired in the measured change of the concentration of the tracer in model liquid's volume. The mathematical description of determined curves is based on the approximate differential equations formulated in the theory of fluid mechanics. Solving these equations to calculate the time constants requires a special software and it is very time-consuming. To improve the process a method was created to calculate the time constants with use of automation elements. It allows to solve problems using algebraic method, which improves interpretation of the research results of physical modeling.
On the distribution of estimators of diffusion constants for Brownian motion

International Nuclear Information System (INIS)

Boyer, Denis; Dean, David S

2011-01-01

We discuss the distribution of various estimators for extracting the diffusion constant of single Brownian trajectories obtained by fitting the squared displacement of the trajectory. The analysis of the problem can be framed in terms of quadratic functionals of Brownian motion that correspond to the Euclidean path integral for simple Harmonic oscillators with time dependent frequencies. Explicit analytical results are given for the distribution of the diffusion constant estimator in a number of cases and our results are confirmed by numerical simulations.
Elongational flow of polymer melts at constant strain rate, constant stress and constant force

Science.gov (United States)

Wagner, Manfred H.; Rolón-Garrido, Víctor H.

2013-04-01

Characterization of polymer melts in elongational flow is typically performed at constant elongational rate or rarely at constant tensile stress conditions. One of the disadvantages of these deformation modes is that they are hampered by the onset of "necking" instabilities according to the Considère criterion. Experiments at constant tensile force have been performed even more rarely, in spite of the fact that this deformation mode is free from necking instabilities and is of considerable industrial relevance as it is the correct analogue of steady fiber spinning. It is the objective of the present contribution to present for the first time a full experimental characterization of a long-chain branched polyethylene melt in elongational flow. Experiments were performed at constant elongation rate, constant tensile stress and constant tensile force by use of a Sentmanat Extensional Rheometer (SER) in combination with an Anton Paar MCR301 rotational rheometer. The accessible experimental window and experimental limitations are discussed. The experimental data are modelled by using the Wagner I model. Predictions of the steady-start elongational viscosity in constant strain rate and creep experiments are found to be identical, albeit only by extrapolation of the experimental data to Hencky strains of the order of 6. For constant stress experiments, a minimum in the strain rate and a corresponding maximum in the elongational viscosity is found at a Hencky strain of the order of 3, which, although larger than the steady-state value, follows roughly the general trend of the steady-state elongational viscosity. The constitutive analysis also reveals that constant tensile force experiments indicate a larger strain hardening potential than seen in constant elongation rate or constant tensile stress experiments. This may be indicative of the effect of necking under constant elongation rate or constant tensile stress conditions according to the Considère criterion.
Analytical Solution for Time-drawdown Response to Constant Pumping from a Homogeneous, Confined Horizontal Aquifer with Unidirectional Flow

Science.gov (United States)

Parrish, K. E.; Zhang, J.; Teasdale, E.

2007-12-01

An exact analytical solution to the ordinary one-dimensional partial differential equation is derived for transient groundwater flow in a homogeneous, confined, horizontal aquifer using Laplace transformation. The theoretical analysis is based on the assumption that the aquifer is homogeneous and one-dimensional (horizontal); confined between impermeable formations on top and bottom; and of infinite horizontal extent and constant thickness. It is also assumed that there is only a single pumping well penetrating the entire aquifer; flow is everywhere horizontal within the aquifer to the well; the well is pumping with a constant discharge rate; the well diameter is infinitesimally small; and the hydraulic head is uniform throughout the aquifer before pumping. Similar to the Theis solution, this solution is suited to determine transmissivity and storativity for a two- dimensional, vertically confined aquifer, such as a long vertically fractured zone of high permeability within low permeable rocks or a long, high-permeability trench inside a low-permeability porous media. In addition, it can be used to analyze time-drawdown responses to pumping and injection in similar settings. The solution can also be used to approximate the groundwater flow for unconfined conditions if (1) the variation of transmissivity is negligible (groundwater table variation is small in comparison to the saturated thickness); and (2) the unsaturated flow is negligible. The errors associated with the use of the solution to unconfined conditions depend on the accuracies of the above two assumptions. The solution can also be used to assess the impacts of recharge from a seasonal river or irrigation canal on the groundwater system by assuming uniform, time- constant recharge along the river or canal. This paper presents the details for derivation of the analytical solution. The analytical solution is compared to numerical simulation results with example cases. Its accuracy is also assessed and
Resimulation of noise: a precision estimator for least square error curve-fitting tested for axial strain time constant imaging

Science.gov (United States)

Nair, S. P.; Righetti, R.

2015-05-01

Recent elastography techniques focus on imaging information on properties of materials which can be modeled as viscoelastic or poroelastic. These techniques often require the fitting of temporal strain data, acquired from either a creep or stress-relaxation experiment to a mathematical model using least square error (LSE) parameter estimation. It is known that the strain versus time relationships for tissues undergoing creep compression have a non-linear relationship. In non-linear cases, devising a measure of estimate reliability can be challenging. In this article, we have developed and tested a method to provide non linear LSE parameter estimate reliability: which we called Resimulation of Noise (RoN). RoN provides a measure of reliability by estimating the spread of parameter estimates from a single experiment realization. We have tested RoN specifically for the case of axial strain time constant parameter estimation in poroelastic media. Our tests show that the RoN estimated precision has a linear relationship to the actual precision of the LSE estimator. We have also compared results from the RoN derived measure of reliability against a commonly used reliability measure: the correlation coefficient (CorrCoeff). Our results show that CorrCoeff is a poor measure of estimate reliability for non-linear LSE parameter estimation. While the RoN is specifically tested only for axial strain time constant imaging, a general algorithm is provided for use in all LSE parameter estimation.
Time-dependent leak behavior of flawed Alloy 600 tube specimens at constant pressure

Energy Technology Data Exchange (ETDEWEB)

Bahn, Chi Bum, E-mail: bahn@anl.gov [Argonne National Laboratory, Argonne, IL 60439 (United States); Majumdar, Saurin [Argonne National Laboratory, Argonne, IL 60439 (United States); Harris, Charles [United States Nuclear Regulatory Commission, Rockville, MD 20852 (United States)

2011-10-15

Leak rate testing has been performed using Alloy 600 tube specimens with throughwall flaws. Some specimens have shown time-dependent leak behavior at constant pressure conditions. Fractographic characterization was performed to identify the time-dependent crack growth mechanism. The fracture surface of the specimens showed the typical features of ductile fracture, as well as the distinct crystallographic facets, typical of fatigue crack growth at low {Delta}K level. Structural vibration appears to have been caused by the oscillation of pressure, induced by a high-pressure pump used in a test facility, and by the water jet/tube structure interaction. Analyses of the leak behaviors and crack growth indicated that both the high-pressure pump and the water jet could significantly contribute to fatigue crack growth. To determine whether the fatigue crack growth during the leak testing can occur solely by the water jet effect, leak rate tests at constant pressure without the high-pressure pump need to be performed. - Highlights: > Leak rate of flawed Alloy 600 tubing increased at constant pressure condition. > Fractography revealed two cases: ductile tearing and crystallographic facets. > Crystallographic facets are typical features of fatigue crack growth at low {Delta}K. > Fatigue source could be water jet-induced vibration and/or high-pressure pump pulsation.
Time-resolved single-shot terahertz time-domain spectroscopy for ultrafast irreversible processes

Science.gov (United States)

Zhai, Zhao-Hui; Zhong, Sen-Cheng; Li, Jun; Zhu, Li-Guo; Meng, Kun; Li, Jiang; Liu, Qiao; Peng, Qi-Xian; Li, Ze-Ren; Zhao, Jian-Heng

2016-09-01

Pulsed terahertz spectroscopy is suitable for spectroscopic diagnostics of ultrafast events. However, the study of irreversible or single shot ultrafast events requires ability to record transient properties at multiple time delays, i.e., time resolved at single shot level, which is not available currently. Here by angular multiplexing use of femtosecond laser pulses, we developed and demonstrated a time resolved, transient terahertz time domain spectroscopy technique, where burst mode THz pulses were generated and then detected in a single shot measurement manner. The burst mode THz pulses contain 2 sub-THz pulses, and the time gap between them is adjustable up to 1 ns with picosecond accuracy, thus it can be used to probe the single shot event at two different time delays. The system can detect the sub-THz pulses at 0.1 THz-2.5 THz range with signal to noise ratio (SNR) of ˜400 and spectrum resolution of 0.05 THz. System design was described here, and optimizations of single shot measurement of THz pulses were discussed in detail. Methods to improve SNR were also discussed in detail. A system application was demonstrated where pulsed THz signals at different time delays of the ultrafast process were successfully acquired within single shot measurement. This time resolved transient terahertz time domain spectroscopy technique provides a new diagnostic tool for irreversible or single shot ultrafast events where dynamic information can be extracted at terahertz range within one-shot experiment.
Characteristics of Viscoelastic Crustal Deformation Following a Megathrust Earthquake: Discrepancy Between the Apparent and Intrinsic Relaxation Time Constants

Science.gov (United States)

Fukahata, Yukitoshi; Matsu'ura, Mitsuhiro

2018-02-01

The viscoelastic deformation of an elastic-viscoelastic composite system is significantly different from that of a simple viscoelastic medium. Here, we show that complicated transient deformation due to viscoelastic stress relaxation after a megathrust earthquake can occur even in a very simple situation, in which an elastic surface layer (lithosphere) is underlain by a viscoelastic substratum (asthenosphere) under gravity. Although the overall decay rate of the system is controlled by the intrinsic relaxation time constant of the asthenosphere, the apparent decay time constant at each observation point is significantly different from place to place and generally much longer than the intrinsic relaxation time constant of the asthenosphere. It is also not rare that the sense of displacement rate is reversed during the viscoelastic relaxation. If we do not bear these points in mind, we may draw false conclusions from observed deformation data. Such complicated transient behavior can be explained mathematically from the characteristics of viscoelastic solution: for an elastic-viscoelastic layered half-space, the viscoelastic solution is expressed as superposition of three decaying components with different relaxation time constants that depend on wavelength.
A simplified controller and detailed dynamics of constant off-time peak current control

Science.gov (United States)

Van den Bossche, Alex; Dimitrova, Ekaterina; Valchev, Vencislav; Feradov, Firgan

2017-09-01

A fast and reliable current control is often the base of power electronic converters. The traditional constant frequency peak control is unstable above 50 % duty ratio. In contrast, the constant off-time peak current control (COTCC) is unconditionally stable and fast, so it is worth analyzing it. Another feature of the COTCC is that one can combine a current control together with a current protection. The time dynamics show a zero-transient response, even when the inductor changes in a wide range. It can also be modeled as a special transfer function for all frequencies. The article shows also that it can be implemented in a simple analog circuit using a wide temperature range IC, such as the LM2903, which is compatible with PV conversion and automotive temperature range. Experiments are done using a 3 kW step-up converter. A drawback is still that the principle does not easily fit in usual digital controllers up to now.
A critical oscillation constant as a variable of time scales for half-linear dynamic equations

Czech Academy of Sciences Publication Activity Database

Řehák, Pavel

2010-01-01

Roč. 60, č. 2 (2010), s. 237-256 ISSN 0139-9918 R&D Projects: GA AV ČR KJB100190701 Institutional research plan: CEZ:AV0Z10190503 Keywords : dynamic equation * time scale * half-linear equation * (non)oscillation criteria * Hille-Nehari criteria * Kneser criteria * critical constant * oscillation constant * Hardy inequality Subject RIV: BA - General Mathematics Impact factor: 0.316, year: 2010 http://link.springer.com/article/10.2478%2Fs12175-010-0009-7
A digital, constant-frequency pulsed phase-locked-loop instrument for real-time, absolute ultrasonic phase measurements

Science.gov (United States)

Haldren, H. A.; Perey, D. F.; Yost, W. T.; Cramer, K. E.; Gupta, M. C.

2018-05-01

A digitally controlled instrument for conducting single-frequency and swept-frequency ultrasonic phase measurements has been developed based on a constant-frequency pulsed phase-locked-loop (CFPPLL) design. This instrument uses a pair of direct digital synthesizers to generate an ultrasonically transceived tone-burst and an internal reference wave for phase comparison. Real-time, constant-frequency phase tracking in an interrogated specimen is possible with a resolution of 0.000 38 rad (0.022°), and swept-frequency phase measurements can be obtained. Using phase measurements, an absolute thickness in borosilicate glass is presented to show the instrument's efficacy, and these results are compared to conventional ultrasonic pulse-echo time-of-flight (ToF) measurements. The newly developed instrument predicted the thickness with a mean error of -0.04 μm and a standard deviation of error of 1.35 μm. Additionally, the CFPPLL instrument shows a lower measured phase error in the absence of changing temperature and couplant thickness than high-resolution cross-correlation ToF measurements at a similar signal-to-noise ratio. By showing higher accuracy and precision than conventional pulse-echo ToF measurements and lower phase errors than cross-correlation ToF measurements, the new digitally controlled CFPPLL instrument provides high-resolution absolute ultrasonic velocity or path-length measurements in solids or liquids, as well as tracking of material property changes with high sensitivity. The ability to obtain absolute phase measurements allows for many new applications than possible with previous ultrasonic pulsed phase-locked loop instruments. In addition to improved resolution, swept-frequency phase measurements add useful capability in measuring properties of layered structures, such as bonded joints, or materials which exhibit non-linear frequency-dependent behavior, such as dispersive media.
Single-crossover recombination in discrete time.

Science.gov (United States)

von Wangenheim, Ute; Baake, Ellen; Baake, Michael

2010-05-01

Modelling the process of recombination leads to a large coupled nonlinear dynamical system. Here, we consider a particular case of recombination in discrete time, allowing only for single crossovers. While the analogous dynamics in continuous time admits a closed solution (Baake and Baake in Can J Math 55:3-41, 2003), this no longer works for discrete time. A more general model (i.e. without the restriction to single crossovers) has been studied before (Bennett in Ann Hum Genet 18:311-317, 1954; Dawson in Theor Popul Biol 58:1-20, 2000; Linear Algebra Appl 348:115-137, 2002) and was solved algorithmically by means of Haldane linearisation. Using the special formalism introduced by Baake and Baake (Can J Math 55:3-41, 2003), we obtain further insight into the single-crossover dynamics and the particular difficulties that arise in discrete time. We then transform the equations to a solvable system in a two-step procedure: linearisation followed by diagonalisation. Still, the coefficients of the second step must be determined in a recursive manner, but once this is done for a given system, they allow for an explicit solution valid for all times.
The holographic dictionary for Beta functions of multi-trace coupling constants

Energy Technology Data Exchange (ETDEWEB)

Aharony, Ofer [Department of Particle Physics and Astrophysics,Weizmann Institute of Science, Rehovot 7610001 (Israel); Gur-Ari, Guy [Department of Particle Physics and Astrophysics,Weizmann Institute of Science, Rehovot 7610001 (Israel); Stanford Institute for Theoretical Physics, Stanford University, Stanford, California 94305 (United States); Klinghoffer, Nizan [Department of Particle Physics and Astrophysics,Weizmann Institute of Science, Rehovot 7610001 (Israel)

2015-05-06

Field theories with weakly coupled holographic duals, such as large N gauge theories, have a natural separation of their operators into ‘single-trace operators’ (dual to single-particle states) and ‘multi-trace operators’ (dual to multi-particle states). There are examples of large N gauge theories where the beta functions of single-trace coupling constants all vanish, but marginal multi-trace coupling constants have non-vanishing beta functions that spoil conformal invariance (even when all multi-trace coupling constants vanish). The holographic dual of such theories should be a classical solution in anti-de Sitter space, in which the boundary conditions that correspond to the multi-trace coupling constants depend on the cutoff scale, in a way that spoils conformal invariance. We argue that this is realized through specific bulk coupling constants that lead to a running of the multi-trace coupling constants. This fills a missing entry in the holographic dictionary.
Determination of Peukert's Constant Using Impedance Spectroscopy: Application to Supercapacitors.

Science.gov (United States)

Mills, Edmund Martin; Kim, Sangtae

2016-12-15

Peukert's equation is widely used to model the rate dependence of battery capacity, and has recently attracted attention for application to supercapacitors. Here we present a newly developed method to readily determine Peukert's constant using impedance spectroscopy. Impedance spectroscopy is ideal for this purpose as it has the capability of probing electrical performance of a device over a wide range of time-scales within a single measurement. We demonstrate that the new method yields consistent results with conventional galvanostatic measurements through applying it to commercially available supercapacitors. Additionally, the novel method is much simpler and more precise, making it an attractive alternative for the determination of Peukert's constant.
Testing the time-invariance of fundamental constants using microwave spectroscopy on cold diatomic radicals

NARCIS (Netherlands)

Bethlem, H.L.; Ubachs, W.M.G.

2009-01-01

The recently demonstrated methods to cool and manipulate neutral molecules offer new possibilities for precision tests of fundamental physics theories. We here discuss the possibility of testing the time-invariance of fundamental constants using near degeneracies between rotational levels in the
Measurement of nucleotide exchange rate constants in single rabbit soleus myofibrils during shortening and lengthening using a fluorescent ATP analog.

Science.gov (United States)

Shirakawa, I; Chaen, S; Bagshaw, C R; Sugi, H

2000-02-01

The kinetics of displacement of a fluorescent nucleotide, 2'(3')-O-[N[2-[[Cy3]amido]ethyl]carbamoyl]-adenosine 5'-triphosphate (Cy3-EDA-ATP), bound to rabbit soleus muscle myofibrils were studied using flash photolysis of caged ATP. Use of myofibrils from this slow twitch muscle allowed better resolution of the kinetics of nucleotide exchange than previous studies with psoas muscle myofibrils (, Biophys. J. 73:2033-2042). Soleus myofibrils in the presence of Cy3-EDA-nucleotides (Cy3-EDA-ATP or Cy3-EDA-ADP) showed selective fluorescence staining of the A-band. The K(m) for Cy3-EDA-ATP and the K(d) for Cy3-EDA-ADP binding to the myofibril A-band were 1.9 microM and 3.8 microM, respectively, indicating stronger binding of nucleotide to soleus cross-bridges compared to psoas cross-bridges (2.6 microM and 50 microM, respectively). After flash photolysis of caged ATP, the A-band fluorescence of the myofibril in the Cy3-EDA-ATP solution under isometric conditions decayed exponentially with a rate constant of 0.045 +/- 0.007 s(-1) (n = 32) at 10 degrees C, which was about seven times slower than that for psoas myofibrils. When a myofibril was allowed to shorten with a constant velocity, the nucleotide displacement rate constant increased from 0.066 s(-1) (isometric) to 0.14 s(-1) at 20 degrees C with increasing shortening velocity up to 0.1 myofibril length/s (V(max), the shortening velocity under no load was approximately 0. 2 myofibril lengths/s). The rate constant was not significantly affected by an isovelocity stretch of up to 0.1 myofibril lengths/s. These results suggest that the cross-bridge kinetics are not significantly affected at higher strain during lengthening but depend on the lower strain during shortening. These data also indicate that the interaction distance between a cross-bridge and the actin filament is at least 16 nm for a single cycle of the ATPase.

Benzodiazepine receptor equilibrium constants for flumazenil and midazolam determined in humans with the single photon emission computer tomography tracer [123I]iomazenil

DEFF Research Database (Denmark)

Videbaek, C; Friberg, L; Holm, S

1993-01-01

twice, once without receptor blockade and once with a constant degree of partial blockade of the benzodiazepine receptors by infusion of nonradioactive flumazenil (Lanexat) or midazolam (Dormicum). Single photon emission computer tomography and blood sampling were performed intermittently for 6 h after...
Connecting Fundamental Constants

International Nuclear Information System (INIS)

Di Mario, D.

2008-01-01

A model for a black hole electron is built from three basic constants only: h, c and G. The result is a description of the electron with its mass and charge. The nature of this black hole seems to fit the properties of the Planck particle and new relationships among basic constants are possible. The time dilation factor in a black hole associated with a variable gravitational field would appear to us as a charge; on the other hand the Planck time is acting as a time gap drastically limiting what we are able to measure and its dimension will appear in some quantities. This is why the Planck time is numerically very close to the gravitational/electric force ratio in an electron: its difference, disregarding a π√(2) factor, is only 0.2%. This is not a coincidence, it is always the same particle and the small difference is between a rotating and a non-rotating particle. The determination of its rotational speed yields accurate numbers for many quantities, including the fine structure constant and the electron magnetic moment
Use of thermal time constant concept in the analysis of reactivity induced accidents with feedback

International Nuclear Information System (INIS)

Narain, R.

1981-01-01

A simple heat transfer model based on the thermal time constant concept which leads to significant reduction in fuel temperature computing time and gives a physical insight of the phenomena is presented. The fuel temperatures can be used to estimate the reactivity feedback using the measured or calculated Doppler coefficients. (E.G.) [pt
Advanced time-correlated single photon counting applications

CERN Document Server

Becker, Wolfgang

2015-01-01

This book is an attempt to bridge the gap between the instrumental principles of multi-dimensional time-correlated single photon counting (TCSPC) and typical applications of the technique. Written by an originator of the technique and by sucessful users, it covers the basic principles of the technique, its interaction with optical imaging methods and its application to a wide range of experimental tasks in life sciences and clinical research. The book is recommended for all users of time-resolved detection techniques in biology, bio-chemistry, spectroscopy of live systems, live cell microscopy, clinical imaging, spectroscopy of single molecules, and other applications that require the detection of low-level light signals at single-photon sensitivity and picosecond time resolution.
Surface Brillouin scattering measurement of the elastic constants of single crystal InAs0.91Sb0.09

International Nuclear Information System (INIS)

Kotane, L M; Comins, J D; Every, A G; Botha, J R

2011-01-01

Surface Brillouin scattering of light has been used to measure the angular dependence of the Rayleigh surface acoustic wave (SAW), pseudo surface acoustic wave (PSAW) and longitudinal lateral wave (LLW) speeds in a (100)-oriented single crystal of the ternary semiconductor alloy InAs 0.91 Sb 0.09 . The wave speed measurements have been used to determine the room temperature values of the elastic constants C 11 , C 12 and C 44 of the alloy. A simple and robust fitting procedure has been implemented for recovering the elastic constants, in which the merit function is constructed from explicit secular functions that determine the surface and lateral wave speeds in the [001] and [011] crystallographic directions. In the fitting, relatively larger weighting factors have been assigned to the SAW and PSAW data because of the greater precision with which the surface modes can be measured as compared with the lateral wave.
Rapid and accurate determination of Stern-Volmer quenching constants

International Nuclear Information System (INIS)

Goodpaster, John V.; McGuffin, Victoria L.

1999-01-01

In this work, a novel system has been designed, characterized, and validated for the determination of fluorescence quenching constants. Capillary flow injection methods are used to automate the preparation and mixing of the fluorophore and quencher solutions. Because of the small diameter of the capillary (75-200 μm), fluorescence measurements can be made without corrections for primary and secondary absorbance effects. The fluorescence spectrometer is equipped with a charge-coupled device (CCD) that has a detection limit of 3.0x10 -9 M (2.3 ppb) and a linear dynamic range of 10 5 for integration times of 0.01-10 s. This spectrometer has a 300 nm spectral range with 1 nm resolution, allowing the fluorescence quenching constants to be calculated at single wavelengths or over integrated wavelength ranges. This system was validated by comparison to traditional methods for the determination of Stern-Volmer constants for alternant and nonalternant polycyclic aromatic hydrocarbons with nitromethane and triethylamine. (c) 2000 Society for Applied Spectroscopy
A quadri-constant fraction discriminator

International Nuclear Information System (INIS)

Wang Wei; Gu Zhongdao

1992-01-01

A quad Constant Fraction (Amplitude and Rise Time Compensation) Discriminator Circuit is described, which is based on the ECL high-speed dual comparator AD 9687. The CFD (ARCD) is of the constant fraction timing type (the amplitude and rise time compensation timing type) employing a leading edge discriminator to eliminate error triggers caused by noises. A timing walk measurement indicates a timing walk of less than +- 150 ps from -50 mV to -5 V
Design of Single Stage Axial Turbine with Constant Nozzle Angle Blading for Small Turbojet

Science.gov (United States)

Putra Adnan, F.; Hartono, Firman

2018-04-01

In this paper, an aerodynamic design of a single stage gas generator axial turbine for small turbojet engine is explained. As per design requirement, the turbine should be able to deliver power output of 155 kW at 0.8139 kg/s gas mass flow, inlet total temperature of 1200 K and inlet total pressure of 335330 Pa. The design phase consist of several steps, i.e.: determination of velocity triangles in 2D plane, 2D blading design and 3D flow analysis at design point using Computational Fluid Dynamics method. In the determination of velocity triangles, two conditions are applied: zero inlet swirl (i.e. the gas flow enter the turbine at axial direction) and constant nozzle angle design (i.e. the inlet and outlet angle of the nozzle blade are constant from root to tip). The 2D approach in cascade plane is used to specify airfoil type at root, mean and tip of the blade based on inlet and outlet flow conditions. The 3D approach is done by simulating the turbine in full configuration to evaluate the overall performance of the turbine. The observed parameters including axial gap, stagger angle, and tip clearance affect its output power. Based on analysis results, axial gap and stagger angle are positively correlated with output power up to a certain point at which the power decreases. Tip clearance, however, gives inversely correlation with output power.
Cosmological constants and variations

International Nuclear Information System (INIS)

Barrow, John D

2005-01-01

We review properties of theories for the variation of the gravitation and fine structure 'constants'. We highlight some general features of the cosmological models that exist in these theories with reference to recent quasar data that is consistent with time-variation in the fine structure 'constant' since a redshift of 3.5. The behaviour of a simple class of varying alpha cosmologies is outlined in the light of all the observational constraints. We also discuss some of the consequences of varying 'constants' for oscillating universes and show by means of exact solutions that they appear to evolve monotonically in time even though the scale factor of the universe oscillates
Thermal time constant: optimising the skin temperature predictive modelling in lower limb prostheses using Gaussian processes.

Science.gov (United States)

Mathur, Neha; Glesk, Ivan; Buis, Arjan

2016-06-01

Elevated skin temperature at the body/device interface of lower-limb prostheses is one of the major factors that affect tissue health. The heat dissipation in prosthetic sockets is greatly influenced by the thermal conductive properties of the hard socket and liner material employed. However, monitoring of the interface temperature at skin level in lower-limb prosthesis is notoriously complicated. This is due to the flexible nature of the interface liners used which requires consistent positioning of sensors during donning and doffing. Predicting the residual limb temperature by monitoring the temperature between socket and liner rather than skin and liner could be an important step in alleviating complaints on increased temperature and perspiration in prosthetic sockets. To predict the residual limb temperature, a machine learning algorithm - Gaussian processes is employed, which utilizes the thermal time constant values of commonly used socket and liner materials. This Letter highlights the relevance of thermal time constant of prosthetic materials in Gaussian processes technique which would be useful in addressing the challenge of non-invasively monitoring the residual limb skin temperature. With the introduction of thermal time constant, the model can be optimised and generalised for a given prosthetic setup, thereby making the predictions more reliable.
Interacting universes and the cosmological constant

International Nuclear Information System (INIS)

Alonso-Serrano, A.; Bastos, C.; Bertolami, O.; Robles-Pérez, S.

2013-01-01

In this Letter it is studied the effects that an interaction scheme among universes can have in the values of their cosmological constants. In the case of two interacting universes, the value of the cosmological constant of one of the universes becomes very close to zero at the expense of an increasing value of the cosmological constant of the partner universe. In the more general case of a chain of N interacting universes with periodic boundary conditions, the spectrum of the Hamiltonian splits into a large number of levels, each of them associated with a particular value of the cosmological constant, that can be occupied by single universes revealing a collective behavior that plainly shows that the multiverse is much more than the mere sum of its parts
Interacting universes and the cosmological constant

Energy Technology Data Exchange (ETDEWEB)

Alonso-Serrano, A. [Centro de Física “Miguel Catalán”, Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 121, 28006 Madrid (Spain); Estación Ecológica de Biocosmología, Pedro de Alvarado 14, 06411 Medellín (Spain); Bastos, C. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Bertolami, O. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Robles-Pérez, S., E-mail: salvarp@imaff.cfmac.csic.es [Centro de Física “Miguel Catalán”, Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 121, 28006 Madrid (Spain); Estación Ecológica de Biocosmología, Pedro de Alvarado 14, 06411 Medellín (Spain); Física Teórica, Universidad del País Vasco, Apartado 644, 48080 Bilbao (Spain)

2013-02-12

In this Letter it is studied the effects that an interaction scheme among universes can have in the values of their cosmological constants. In the case of two interacting universes, the value of the cosmological constant of one of the universes becomes very close to zero at the expense of an increasing value of the cosmological constant of the partner universe. In the more general case of a chain of N interacting universes with periodic boundary conditions, the spectrum of the Hamiltonian splits into a large number of levels, each of them associated with a particular value of the cosmological constant, that can be occupied by single universes revealing a collective behavior that plainly shows that the multiverse is much more than the mere sum of its parts.
An optimal policy for deteriorating items with time-proportional deterioration rate and constant and time-dependent linear demand rate

Science.gov (United States)

Singh, Trailokyanath; Mishra, Pandit Jagatananda; Pattanayak, Hadibandhu

2017-12-01

In this paper, an economic order quantity (EOQ) inventory model for a deteriorating item is developed with the following characteristics: (i) The demand rate is deterministic and two-staged, i.e., it is constant in first part of the cycle and linear function of time in the second part. (ii) Deterioration rate is time-proportional. (iii) Shortages are not allowed to occur. The optimal cycle time and the optimal order quantity have been derived by minimizing the total average cost. A simple solution procedure is provided to illustrate the proposed model. The article concludes with a numerical example and sensitivity analysis of various parameters as illustrations of the theoretical results.
Quintessence and the cosmological constant

International Nuclear Information System (INIS)

Doran, M.; Wetterich, C.

2003-01-01

Quintessence -- the energy density of a slowly evolving scalar field -- may constitute a dynamical form of the homogeneous dark energy in the universe. We review the basic idea in the light of the cosmological constant problem. Cosmological observations or a time variation of fundamental 'constants' can distinguish quintessence from a cosmological constant
Learning Read-constant Polynomials of Constant Degree modulo Composites

DEFF Research Database (Denmark)

Chattopadhyay, Arkadev; Gavaldá, Richard; Hansen, Kristoffer Arnsfelt

2011-01-01

Boolean functions that have constant degree polynomial representation over a fixed finite ring form a natural and strict subclass of the complexity class \\textACC0ACC0. They are also precisely the functions computable efficiently by programs over fixed and finite nilpotent groups. This class...... is not known to be learnable in any reasonable learning model. In this paper, we provide a deterministic polynomial time algorithm for learning Boolean functions represented by polynomials of constant degree over arbitrary finite rings from membership queries, with the additional constraint that each variable...
Developmental Times of Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae) at Constant Temperatures and Applications in Forensic Entomology.

Science.gov (United States)

Yang, Yong-Qiang; Li, Xue-Bo; Shao, Ru-Yue; Lyu, Zhou; Li, Hong-Wei; Li, Gen-Ping; Xu, Lyu-Zi; Wan, Li-Hua

2016-09-01

The characteristic life stages of infesting blowflies (Calliphoridae) such as Chrysomya megacephala (Fabricius) are powerful evidence for estimating the death time of a corpse, but an established reference of developmental times for local blowfly species is required. We determined the developmental rates of C. megacephala from southwest China at seven constant temperatures (16-34°C). Isomegalen and isomorphen diagrams were constructed based on the larval length and time for each developmental event (first ecdysis, second ecdysis, wandering, pupariation, and eclosion), at each temperature. A thermal summation model was constructed by estimating the developmental threshold temperature D0 and the thermal summation constant K. The thermal summation model indicated that, for complete development from egg hatching to eclosion, D0 = 9.07 ± 0.54°C and K = 3991.07 ± 187.26 h °C. This reference can increase the accuracy of estimations of postmortem intervals in China by predicting the growth of C. megacephala. © 2016 American Academy of Forensic Sciences.
Constant-roll (quasi-)linear inflation

Science.gov (United States)

Karam, A.; Marzola, L.; Pappas, T.; Racioppi, A.; Tamvakis, K.

2018-05-01

In constant-roll inflation, the scalar field that drives the accelerated expansion of the Universe is rolling down its potential at a constant rate. Within this framework, we highlight the relations between the Hubble slow-roll parameters and the potential ones, studying in detail the case of a single-field Coleman-Weinberg model characterised by a non-minimal coupling of the inflaton to gravity. With respect to the exact constant-roll predictions, we find that assuming an approximate slow-roll behaviour yields a difference of Δ r = 0.001 in the tensor-to-scalar ratio prediction. Such a discrepancy is in principle testable by future satellite missions. As for the scalar spectral index ns, we find that the existing 2-σ bound constrains the value of the non-minimal coupling to ξphi ~ 0.29–0.31 in the model under consideration.
Most Probable Failures in LHC Magnets and Time Constants of their Effects on the Beam.

CERN Document Server

Gomez Alonso, Andres

2006-01-01

During the LHC operation, energies up to 360 MJ will be stored in each proton beam and over 10 GJ in the main electrical circuits. With such high energies, beam losses can quickly lead to important equipment damage. The Machine Protection Systems have been designed to provide reliable protection of the LHC through detection of the failures leading to beam losses and fast dumping of the beams. In order to determine the protection strategies, it is important to know the time constants of the failure effects on the beam. In this report, we give an estimation of the time constants of quenches and powering failures in LHC magnets. The most critical failures are powering failures in certain normal conducting circuits, leading to relevant effects on the beam in ~1 ms. The failures on super conducting magnets leading to fastest losses are quenches. In this case, the effects on the beam can be signficant ~10 ms after the quench occurs.
On single-time reduction in quantum field theory

International Nuclear Information System (INIS)

Arkhipov, A.A.

1984-01-01

It is shown, how the causality and spectrality properties in qUantum field theory may help one to carry out a single-time reduction of the Bethe-Salpeter wave fUnction. The single-time reduction technique is not based on any concrete model of the quantum field theory. Axiomatic formulations underline the quantum field theory
Exponential stability of fuzzy cellular neural networks with constant and time-varying delays

International Nuclear Information System (INIS)

Liu Yanqing; Tang Wansheng

2004-01-01

In this Letter, the global stability of delayed fuzzy cellular neural networks (FCNN) with either constant delays or time varying delays is proposed. Firstly, we give the existence and uniqueness of the equilibrium point by using the theory of topological degree and the properties of nonsingular M-matrix and the sufficient conditions for ascertaining the global exponential stability by constructing a suitable Lyapunov functional. Secondly, the criteria for guaranteeing the global exponential stability of FCNN with time varying delays are given and the estimation of exponential convergence rate with regard to speed of vary of delays is presented by constructing a suitable Lyapunov functional

Sub-Micrometer Zeolite Films on Gold-Coated Silicon Wafers with Single-Crystal-Like Dielectric Constant and Elastic Modulus

Energy Technology Data Exchange (ETDEWEB)

Tiriolo, Raffaele [Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, Viale Europa 88100 Catanzaro Italy; Rangnekar, Neel [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA; Zhang, Han [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA; Shete, Meera [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA; Bai, Peng [Department of Chemistry and Chemistry Theory Center, University of Minnesota, 207 Pleasant St SE Minneapolis MN 55455 USA; Nelson, John [Characterization Facility, University of Minnesota, 12 Shepherd Labs, 100 Union St. S.E. Minneapolis MN 55455 USA; Karapetrova, Evguenia [Surface Scattering and Microdiffraction, X-ray Science Division, Argonne National Laboratory, 9700 S. Cass Ave, Building 438-D002 Argonne IL 60439 USA; Macosko, Christopher W. [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA; Siepmann, Joern Ilja [Department of Chemistry and Chemistry Theory Center, University of Minnesota, 207 Pleasant St SE Minneapolis MN 55455 USA; Lamanna, Ernesto [Department of Health Sciences, University Magna Graecia of Catanzaro, Viale Europa 88100 Catanzaro Italy; Lavano, Angelo [Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, Viale Europa 88100 Catanzaro Italy; Tsapatsis, Michael [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA

2017-05-08

A low-temperature synthesis coupled with mild activation produces zeolite films exhibiting low dielectric constant (low-k) matching the theoretically predicted and experimentally measured values for single crystals. This synthesis and activation method allows for the fabrication of a device consisting of a b-oriented film of the pure-silica zeolite MFI (silicalite-1) supported on a gold-coated silicon wafer. The zeolite seeds are assembled by a manual assembly process and subjected to optimized secondary growth conditions that do not cause corrosion of the gold underlayer, while strongly promoting in-plane growth. The traditional calcination process is replaced with a non-thermal photochemical activation to ensure preservation of an intact gold layer. The dielectric constant (k), obtained through measurement of electrical capacitance in a metal-insulator-metal configuration, highlights the ultralow k approximate to 1.7 of the synthetized films, which is among the lowest values reported for an MFI film. There is large improvement in elastic modulus of the film (E approximate to 54 GPa) over previous reports, potentially allowing for integration into silicon wafer processing technology.
Constant versus variable response signal delays in speed--accuracy trade-offs: effects of advance preparation for processing time.

Science.gov (United States)

Miller, Jeff; Sproesser, Gudrun; Ulrich, Rolf

2008-07-01

In two experiments, we used response signals (RSs) to control processing time and trace out speed--accuracy trade-off(SAT) functions in a difficult perceptual discrimination task. Each experiment compared performance in blocks of trials with constant and, hence, temporally predictable RS lags against performance in blocks with variable, unpredictable RS lags. In both experiments, essentially equivalent SAT functions were observed with constant and variable RS lags. We conclude that there is little effect of advance preparation for a given processing time, suggesting that the discrimination mechanisms underlying SAT functions are driven solely by bottom-up information processing in perceptual discrimination tasks.
Dynamic Characteristics of The DSI-Type Constant-Flow Valves

Science.gov (United States)

Kang, Yuan; Hu, Sheng-Yan; Chou, Hsien-Chin; Lee, Hsing-Han

Constant flow valves have been presented in industrial applications or academic studies, which compensate recess pressures of a hydrostatic bearing to resist load fluctuating. The flow rate of constant-flow valves can be constant in spite of the pressure changes in recesses, however the design parameters must be specified. This paper analyzes the dynamic responses of DSI-type constant-flow valves that is designed as double pistons on both ends of a spool with single feedback of working pressure and regulating restriction at inlet. In this study the static analysis presents the specific relationships among design parameters for constant flow rate and the dynamic analyses give the variations around the constant flow rate as the working pressure fluctuates.
Pricing constant maturity credit default swaps under jumo dynamics

NARCIS (Netherlands)

Jönsson, H.; Schoutens, W.

2009-01-01

In this paper we discuss the pricing of Constant Maturity Credit Default Swaps (CMCDS) under single sided jump models. The CMCDS offers default protection in exchange for a floating premium which is periodically reset and indexed to the market spread on a CDS with constant maturity tenor written on
A novel method for in-situ estimation of time constant for core temperature monitoring thermocouples of operating reactors

International Nuclear Information System (INIS)

Sylvia, J.I.; Chandar, S. Clement Ravi; Velusamy, K.

2014-01-01

Highlights: • Core temperature sensor was mathematically modeled. • Ramp signal generated during reactor operating condition is used. • Procedure and methodology has been demonstrated by applying it to FBTR. • Same technique will be implemented for all fast reactors. - Abstract: Core temperature monitoring system is an important component of reactor protection system in the current generation fast reactors. In this system, multiple thermocouples are housed inside a thermowell of fuel subassemblies. Response time of the thermocouple assembly forms an important input for safety analysis of fast reactor and hence frequent calibration/time constant estimation is essential. In fast reactors the central fuel subassembly is provided with bare fast response thermocouples to detect under cooling events in reactor and take proper safety action. On the other hand, thermocouples in thermowell are mainly used for blockage detection in individual fuel subassemblies. The time constant of thermocouples in thermowell can drift due to creep, vibration and thermal fatigue of the thermowell assembly. A novel method for in-situ estimation of time constant is proposed. This method uses the Safety Control Rod Accelerated Mechanism (SCRAM) or lowering of control Rod (LOR) signals of the reactor along with response of the central subassembly thermocouples as reference data. Validation of the procedure has been demonstrated by applying it to FBTR
Single Motherhood, Living Arrangements, and Time With Children in Japan.

Science.gov (United States)

Raymo, James M; Park, Hyunjoon; Iwasawa, Miho; Zhou, Yanfei

2014-08-01

The authors examined relationships between single parenthood and mothers' time with children in Japan. Using data from the 2011 National Survey of Households with Children (N = 1,926), they first demonstrate that time spent with children and the frequency of shared dinners are significantly lower for single mothers than for their married counterparts. For single mothers living alone, less time with children reflects long work hours and work-related stress. Single mothers coresiding with parents spend less time with children and eat dinner together less frequently than either married mothers or their unmarried counterparts not living with parents, net of (grand)parental support, work hours, income, and stress. The findings suggest that rising divorce rates and associated growth in single-mother families may have a detrimental impact on parents' time with children in Japan and that the relatively high prevalence of intergenerational coresidence among single mothers may do little to temper this impact.
Detecting electroporation by assessing the time constants in the exponential response of human skin to voltage controlled impulse electrical stimulation.

Science.gov (United States)

Bîrlea, Sinziana I; Corley, Gavin J; Bîrlea, Nicolae M; Breen, Paul P; Quondamatteo, Fabio; OLaighin, Gearóid

2009-01-01

We propose a new method for extracting the electrical properties of human skin based on the time constant analysis of its exponential response to impulse stimulation. As a result of this analysis an adjacent finding has arisen. We have found that stratum corneum electroporation can be detected using this analysis method. We have observed that a one time-constant model is appropriate for describing the electrical properties of human skin at low amplitude applied voltages (30V). Higher voltage amplitudes (>30V) have been proven to create pores in the skin's stratum corneum which offer a new, lower resistance, pathway for the passage of current through the skin. Our data shows that when pores are formed in the stratum corneum they can be detected, in-vivo, due to the fact that a second time constant describes current flow through them.
Constant-work-space algorithms for geometric problems

Directory of Open Access Journals (Sweden)

Tetsuo Asano

2011-07-01

Full Text Available Constant-work-space algorithms may use only constantly many cells of storage in addition to their input, which is provided as a read-only array. We show how to construct several geometric structures efficiently in the constant-work-space model. Traditional algorithms process the input into a suitable data structure (like a doubly-connected edge list that allows efficient traversal of the structure at hand. In the constant-work-space setting, however, we cannot afford to do this. Instead, we provide operations that compute the desired features on the fly by accessing the input with no extra space. The whole geometric structure can be obtained by using these operations to enumerate all the features. Of course, we must pay for the space savings by slower running times. While the standard data structure allows us to implement traversal operations in constant time, our schemes typically take linear time to read the input data in each step.We begin with two simple problems: triangulating a planar point set and finding the trapezoidal decomposition of a simple polygon. In both cases adjacent features can be enumerated in linear time per step, resulting in total quadratic running time to output the whole structure. Actually, we show that the former result carries over to the Delaunay triangulation, and hence the Voronoi diagram. This also means that we can compute the largest empty circle of a planar point set in quadratic time and constant work-space. As another application, we demonstrate how to enumerate the features of an Euclidean minimum spanning tree (EMST in quadratic time per step, so that the whole EMST can be found in cubic time using constant work-space.Finally, we describe how to compute a shortest geodesic path between two points in a simple polygon. Although the shortest path problem in general graphs is NL-complete (Jakoby and Tantau 2003, this constrained problem can be solved in quadratic time using only constant work-space.
All-optical differential equation solver with constant-coefficient tunable based on a single microring resonator.

Science.gov (United States)

Yang, Ting; Dong, Jianji; Lu, Liangjun; Zhou, Linjie; Zheng, Aoling; Zhang, Xinliang; Chen, Jianping

2014-07-04

Photonic integrated circuits for photonic computing open up the possibility for the realization of ultrahigh-speed and ultra wide-band signal processing with compact size and low power consumption. Differential equations model and govern fundamental physical phenomena and engineering systems in virtually any field of science and engineering, such as temperature diffusion processes, physical problems of motion subject to acceleration inputs and frictional forces, and the response of different resistor-capacitor circuits, etc. In this study, we experimentally demonstrate a feasible integrated scheme to solve first-order linear ordinary differential equation with constant-coefficient tunable based on a single silicon microring resonator. Besides, we analyze the impact of the chirp and pulse-width of input signals on the computing deviation. This device can be compatible with the electronic technology (typically complementary metal-oxide semiconductor technology), which may motivate the development of integrated photonic circuits for optical computing.
Correlation of retention of lanthanide and actinide complexes with stability constants and their speciation

Energy Technology Data Exchange (ETDEWEB)

Datta, A.; Sivaraman, N.; Viswanathan, K.S.; Ghosh, Suddhasattwa; Srinivasan, T.G.; Vasudeva Rao, P.R. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Chemistry Group

2013-03-01

The present study describes a correlation that is developed from retention of lanthanide and actinide complexes with the stability constant. In these studies, an ion-pairing reagent, camphor-10-sulphonic acid (CSA) was used as the modifier and organic acids such as {alpha}-hydroxy isobutyric acid ({alpha}-HIBA), mandelic acid, lactic acid and tartaric acid were used as complexing reagent for elution. From these studies, a correlation has been established between capacity factor of a metal ion, concentration of ion-pairing reagent and complexing agent with the stability constant of metal complex. Based on these studies, it has been shown that the stability constant of lanthanide and actinide complexes can be estimated using a single lanthanide calibrant. Validation of the method was carried out with the complexing agents such as {alpha}-HIBA and lactic acid. It was also demonstrated that data from a single chromatogram can be used for estimation of stability constant at various ionic strengths. These studies also demonstrated that the method can be applied for estimation of stability constant of actinides with a ligand whose value is not reported yet, e.g., ligands of importance in the lanthanide-actinide separations, chelation therapy etc. The chromatographic separation method is fast and the estimation of stability constant can be done in a very short time, which is a significant advantage especially in dealing with radioactive elements. The stability constant data was used to derive speciation data of plutonium in different oxidation states as well as that of americium with {alpha}-HIBA. The elution behavior of actinides such as Pu and Am from reversed phase chromatographic technique could be explained based on these studies. (orig.)
Calculation of the acid-base equilibrium constants at the alumina/electrolyte interface from the ph dependence of the adsorption of singly charged ions (Na+, Cl-)

Science.gov (United States)

Gololobova, E. G.; Gorichev, I. G.; Lainer, Yu. A.; Skvortsova, I. V.

2011-05-01

A procedure was proposed for the calculation of the acid-base equilibrium constants at an alumina/electrolyte interface from experimental data on the adsorption of singly charged ions (Na+, Cl-) at various pH values. The calculated constants (p K {1/0}= 4.1, p K {2/0}= 11.9, p K {3/0}= 8.3, and p K {4/0}= 7.7) are shown to agree with the values obtained from an experimental pH dependence of the electrokinetic potential and the results of potentiometric titration of Al2O3 suspensions.
Stabilized power constant alimentation; Alimentation regulee a puissance constante

Energy Technology Data Exchange (ETDEWEB)

Roussel, L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-06-01

The study and realization of a stabilized power alimentation variable from 5 to 100 watts are described. In order to realize a constant power drift of Lithium compensated diodes, we have searched a 1 per cent precision of regulation and a response time minus than 1 sec. Recent components like Hall multiplicator and integrated amplifiers give this possibility and it is easy to use permutable circuits. (author) [French] On decrit l'etude et la realisation d'une alimentation a puissance constante reglable dans une gamme de 5 a 100 watts. Prevue pour le drift a puissance constante des diodes compensees au lithium, l'etude a ete menee en vue d'obtenir une precision de regulation de 1 pour cent et un temps de reponse inferieur a la seconde. Des systemes recents tels que multiplicateurs a effet Hall et circuits integres ont permis d'atteindre ce but tout en facilitant l'emploi de modules interchangeables. (auteur)
Stabilized power constant alimentation; Alimentation regulee a puissance constante

Energy Technology Data Exchange (ETDEWEB)

Roussel, L. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-06-01

The study and realization of a stabilized power alimentation variable from 5 to 100 watts are described. In order to realize a constant power drift of Lithium compensated diodes, we have searched a 1 per cent precision of regulation and a response time minus than 1 sec. Recent components like Hall multiplicator and integrated amplifiers give this possibility and it is easy to use permutable circuits. (author) [French] On decrit l'etude et la realisation d'une alimentation a puissance constante reglable dans une gamme de 5 a 100 watts. Prevue pour le drift a puissance constante des diodes compensees au lithium, l'etude a ete menee en vue d'obtenir une precision de regulation de 1 pour cent et un temps de reponse inferieur a la seconde. Des systemes recents tels que multiplicateurs a effet Hall et circuits integres ont permis d'atteindre ce but tout en facilitant l'emploi de modules interchangeables. (auteur)
Using a Constant Time Delay Procedure to Teach Foundational Swimming Skills to Children with Autism

Science.gov (United States)

Rogers, Laura; Hemmeter, Mary Louise; Wolery, Mark

2010-01-01

The purpose of this study was to evaluate the effectiveness of using a constant time delay procedure to teach foundational swimming skills to three children with autism. The skills included flutter kick, front-crawl arm strokes, and head turns to the side. A multiple-probe design across behaviors and replicated across participants was used.…
Constant versus variable response signal delays in speed accuracy trade-offs : Effects of advance preparation for processing time

OpenAIRE

Miller, Jeff; Sproesser, Gudrun; Ulrich, Rolf

2008-01-01

In two experiments, we used response signals (RSs) to control processing time and trace out speed accuracy trade-off (SAT) functions in a difficult perceptual discrimination task. Each experiment compared performance in blocks of trials with constant and, hence, temporally predictable RS lags against performance in blocks with variable, unpredictable RS lags. In both experiments, essentially equivalent SAT functions were observed with constant and variable RS lags. We conclude that there is l...
Varying Constants, Gravitation and Cosmology

Directory of Open Access Journals (Sweden)

Jean-Philippe Uzan

2011-03-01

Full Text Available Fundamental constants are a cornerstone of our physical laws. Any constant varying in space and/or time would reflect the existence of an almost massless field that couples to matter. This will induce a violation of the universality of free fall. Thus, it is of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We detail the relations between the constants, the tests of the local position invariance and of the universality of free fall. We then review the main experimental and observational constraints that have been obtained from atomic clocks, the Oklo phenomenon, solar system observations, meteorite dating, quasar absorption spectra, stellar physics, pulsar timing, the cosmic microwave background and big bang nucleosynthesis. At each step we describe the basics of each system, its dependence with respect to the constants, the known systematic effects and the most recent constraints that have been obtained. We then describe the main theoretical frameworks in which the low-energy constants may actually be varying and we focus on the unification mechanisms and the relations between the variation of different constants. To finish, we discuss the more speculative possibility of understanding their numerical values and the apparent fine-tuning that they confront us with.
Strain fluctuations and elastic constants

Energy Technology Data Exchange (ETDEWEB)

Parrinello, M.; Rahman, A.

1982-03-01

It is shown that the elastic strain fluctuations are a direct measure of elastic compliances in a general anisotropic medium; depending on the ensemble in which the fluctuation is measured either the isothermal or the adiabatic compliances are obtained. These fluctuations can now be calculated in a constant enthalpy and pressure, and hence, constant entropy, ensemble due to recent develpments in the molecular dynamics techniques. A calculation for a Ni single crystal under uniform uniaxial 100 tensile or compressive load is presented as an illustration of the relationships derived between various strain fluctuations and the elastic modulii. The Born stability criteria and the behavior of strain fluctuations are shown to be related.
Derivation of the optical constants of anisotropic

Science.gov (United States)

Aronson, J. R.; Emslie, A. G.; Smith, E. M.; Strong, P. F.

1985-07-01

This report concerns the development of methods for obtaining the optical constants of anisotropic crystals of the triclinic and monoclinic systems. The principal method used, classical dispersion theory, is adapted to these crystal systems by extending the Lorentz line parameters to include the angles characterizing the individual resonances, and by replacing the dielectric constant by a dielectric tensor. The sample crystals are gypsium, orthoclase and chalcanthite. The derived optical constants are shown to be suitable for modeling the optical properties of particulate media in the infrared spectral region. For those materials where suitable size single crystals are not available, an extension of a previously used method is applied to alabaster, a polycrystalline material of the monoclinic crystal system.
Analysis of discrete and continuous distributions of ventilatory time constants from dynamic computed tomography

International Nuclear Information System (INIS)

Doebrich, Marcus; Markstaller, Klaus; Karmrodt, Jens; Kauczor, Hans-Ulrich; Eberle, Balthasar; Weiler, Norbert; Thelen, Manfred; Schreiber, Wolfgang G

2005-01-01

In this study, an algorithm was developed to measure the distribution of pulmonary time constants (TCs) from dynamic computed tomography (CT) data sets during a sudden airway pressure step up. Simulations with synthetic data were performed to test the methodology as well as the influence of experimental noise. Furthermore the algorithm was applied to in vivo data. In five pigs sudden changes in airway pressure were imposed during dynamic CT acquisition in healthy lungs and in a saline lavage ARDS model. The fractional gas content in the imaged slice (FGC) was calculated by density measurements for each CT image. Temporal variations of the FGC were analysed assuming a model with a continuous distribution of exponentially decaying time constants. The simulations proved the feasibility of the method. The influence of experimental noise could be well evaluated. Analysis of the in vivo data showed that in healthy lungs ventilation processes can be more likely characterized by discrete TCs whereas in ARDS lungs continuous distributions of TCs are observed. The temporal behaviour of lung inflation and deflation can be characterized objectively using the described new methodology. This study indicates that continuous distributions of TCs reflect lung ventilation mechanics more accurately compared to discrete TCs
The ruin probability of a discrete time risk model under constant interest rate with heavy tails

NARCIS (Netherlands)

Tang, Q.

2004-01-01

This paper investigates the ultimate ruin probability of a discrete time risk model with a positive constant interest rate. Under the assumption that the gross loss of the company within one year is subexponentially distributed, a simple asymptotic relation for the ruin probability is derived and

Surface Brillouin scattering measurement of the elastic constants of single crystal InAs{sub 0.91}Sb{sub 0.09}

Energy Technology Data Exchange (ETDEWEB)

Kotane, L M; Comins, J D; Every, A G [Materials Physics Research Institute, School of Physics, University of the Witwatersrand, Johannesburg, Wits 2050 (South Africa); Botha, J R, E-mail: Lesias.Kotane@wits.ac.z [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

2011-01-01

Surface Brillouin scattering of light has been used to measure the angular dependence of the Rayleigh surface acoustic wave (SAW), pseudo surface acoustic wave (PSAW) and longitudinal lateral wave (LLW) speeds in a (100)-oriented single crystal of the ternary semiconductor alloy InAs{sub 0.91}Sb{sub 0.09}. The wave speed measurements have been used to determine the room temperature values of the elastic constants C{sub 11}, C{sub 12} and C{sub 44} of the alloy. A simple and robust fitting procedure has been implemented for recovering the elastic constants, in which the merit function is constructed from explicit secular functions that determine the surface and lateral wave speeds in the [001] and [011] crystallographic directions. In the fitting, relatively larger weighting factors have been assigned to the SAW and PSAW data because of the greater precision with which the surface modes can be measured as compared with the lateral wave.
Determination of the optical constants of polymer light-emitting diode films from single reflection measurements

International Nuclear Information System (INIS)

Zhu Dexi; Shen Weidong; Ye Hui; Liu Xu; Zhen Hongyu

2008-01-01

We present a simple and fast method to determine the optical constant and physical thickness of polymer films from a single reflectivity measurement. A self-consistent dispersion formula of the Forouhi-Bloomer model was introduced to fit the measured spectral curves by a modified 'Downhill' simplex algorithm. Four widely used polymer light-emitting diodes materials: poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene], poly(9,9-dioctylfluoreny-2,7-diyl) (PFO), poly(N-vinyl carbazole) and poly(3,4-ethylene dioxythiophene) : poly(styrenesulfonate) were investigated by this technique. The refractive indices over the whole visible region as well as the optical band gap extracted by this method agree well with those reported in the literature. The determined physical thicknesses present a deviation less than 4% compared with the experimental values measured by the stylus profiler. The influence of scattering loss on the fitted results is discussed to demonstrate the applicability of this technology for polymer films.
Bilateral control of master-slave manipulators with constant time delay.

Science.gov (United States)

Forouzantabar, A; Talebi, H A; Sedigh, A K

2012-01-01

This paper presents a novel teleoperation controller for a nonlinear master-slave robotic system with constant time delay in communication channel. The proposed controller enables the teleoperation system to compensate human and environmental disturbances, while achieving master and slave position coordination in both free motion and contact situation. The current work basically extends the passivity based architecture upon the earlier work of Lee and Spong (2006) [14] to improve position tracking and consequently transparency in the face of disturbances and environmental contacts. The proposed controller employs a PID controller in each side to overcome some limitations of a PD controller and guarantee an improved performance. Moreover, by using Fourier transform and Parseval's identity in the frequency domain, we demonstrate that this new PID controller preserves the passivity of the system. Simulation and semi-experimental results show that the PID controller tracking performance is superior to that of the PD controller tracking performance in slave/environmental contacts. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.
Search for time modulations in the decay constant of 40K and 226Ra at the underground Gran Sasso Laboratory

Science.gov (United States)

Bellotti, E.; Broggini, C.; Di Carlo, G.; Laubenstein, M.; Menegazzo, R.

2018-05-01

Time modulations at per mil level have been reported to take place in the decay constant of several nuclei with period of one year (most cases) but also of about one month or one day. On the other hand, experiments with similar or better sensitivity have been unable to detect any modulation. In this letter we give the results of the activity study of two different sources: 40K and 226Ra. The two gamma spectrometry experiments have been performed underground at the Gran Sasso Laboratory, this way suppressing the time dependent cosmic ray background. Briefly, our measurements reached the sensitivity of 3.4 and 3.5 parts over 106 for 40K and 226Ra, respectively (1 sigma) and they do not show any statistically significant evidence of time dependence in the decay constant. We also give the results of the activity measurement at the time of the two strong X-class solar flares which took place in September 2017. Our data do not show any unexpected time dependence in the decay rate of 40K in correspondence with the two flares. To the best of our knowledge, these are the most precise and accurate results on the stability of the decay constant as function of time.
Time constants and transfer functions for a homogeneous 900 MWt metallic fueled LMR

International Nuclear Information System (INIS)

Grimm, K.N.; Meneghetti, D.

1988-01-01

Nodal transfer functions are calculated for a 900 MWt U10Zr-fueled sodium cooled reactor. From the transfer functions the time constants, feedback reactivity transfer function coefficients, and power coefficients can be determined. These quantities are calculated for core fuel, upper and lower axial reflector steel, radial blanket fuel, radial reflector steel, and B 4 C rod shaft expansion effect. The quantities are compared to the analogous quantities of a 60 MWt metallic-fueled sodium cooled Experimental Breeder Reactor II configuration. 8 refs., 2 figs., 6 tabs
NVU dynamics. I. Geodesic motion on the constant-potential-energy hypersurface

DEFF Research Database (Denmark)

Ingebrigtsen, Trond; Toxværd, Søren; Heilmann, Ole

2011-01-01

that ensures potential-energy and step-length conservation; center-of-mass drift is also eliminated. Analytical arguments confirmed by simulations demonstrate that the modified NVU algorithm is absolutely stable. Finally, we present simulations showing that the NVU algorithm and the standard leap-frog NVE......An algorithm is derived for computer simulation of geodesics on the constant-potential-energy hypersurface of a system of N classical particles. First, a basic time-reversible geodesic algorithm is derived by discretizing the geodesic stationarity condition and implementing the constant......-potential-energy constraint via standard Lagrangian multipliers. The basic NVU algorithm is tested by single-precision computer simulations of the Lennard-Jones liquid. Excellent numerical stability is obtained if the force cutoff is smoothed and the two initial configurations have identical potential energy within machine...
Constant envelope OFDM scheme for 6PolSK-QPSK

Science.gov (United States)

Li, Yupeng; Ding, Ding

2018-03-01

A constant envelope OFDM scheme with phase modulator (PM-CE-OFDM) for 6PolSK-QPSK modulation was demonstrated. Performance under large fiber launch power is measured to check its advantages in counteracting fiber nonlinear impairments. In our simulation, PM-CE-OFDM, RF-assisted constant envelope OFDM (RF-CE-OFDM) and conventional OFDM (Con-OFDM) are transmitted through 80 km standard single mode fiber (SSMF) single channel and WDM system. Simulation results confirm that PM-CE-OFDM has best performance in resisting fiber nonlinearity. In addition, benefiting from the simple system structure, the complexity and cost of PM-CE-OFDM system could be reduced effectively.
Evolution of the solar constant

International Nuclear Information System (INIS)

Newman, M.J.

1978-01-01

The ultimate source of the energy utilized by life on Earth is the Sun, and the behavior of the Sun determines to a large extent the conditions under which life originated and continues to thrive. What can be said about the history of the Sun. Has the solar constant, the rate at which energy is received by the Earth from the Sun per unit area per unit time, been constant at its present level since Archean times. Three mechanisms by which it has been suggested that the solar energy output can vary with time are discussed, characterized by long (approx. 10 9 years), intermediate (approx. 10 8 years), and short (approx. years to decades) time scales
Optimization of time-correlated single photon counting spectrometer

International Nuclear Information System (INIS)

Zhang Xiufeng; Du Haiying; Sun Jinsheng

2011-01-01

The paper proposes a performance improving scheme for the conventional time-correlated single photon counting spectrometer and develops a high speed data acquisition card based on PCI bus and FPGA technologies. The card is used to replace the multi-channel analyzer to improve the capability and decrease the volume of the spectrometer. The process of operation is introduced along with the integration of the spectrometer system. Many standard samples are measured. The experimental results show that the sensitivity of the spectrometer is single photon counting, and the time resolution of fluorescence lifetime measurement can be picosecond level. The instrument could measure the time-resolved spectroscopy. (authors)
Equilibrium constants in aqueous lanthanide and actinide chemistry from time-resolved fluorescence spectroscopy: The role of ground and excited state reactions

International Nuclear Information System (INIS)

Billard, I.; Luetzenkirchen, K.

2003-01-01

Equilibrium constants for aqueous reactions between lanthanide or actinide ions and (in-) organic ligands contain important information for various radiochemical problems, such as nuclear reprocessing or the migration of radioelements in the geosphere. We study the conditions required to determine equilibrium constants by time-resolved fluorescence spectroscopy measurements. Based on a simulation study it is shown that the possibility to determine equilibrium constants depends upon the reaction rates in the photoexcited states of the lanthanide or actinide ions. (orig.)
The fundamental constants a mystery of physics

CERN Document Server

Fritzsch, Harald

2009-01-01

The speed of light, the fine structure constant, and Newton's constant of gravity — these are just three among the many physical constants that define our picture of the world. Where do they come from? Are they constant in time and across space? In this book, physicist and author Harald Fritzsch invites the reader to explore the mystery of the fundamental constants of physics in the company of Isaac Newton, Albert Einstein, and a modern-day physicist
Off-line correction for excessive constant-fraction-discriminator walk in neutron time-of-flight experiments

International Nuclear Information System (INIS)

Heilbronn, Lawrence; Iwata, Yoshiyuki; Iwase, H.

2003-01-01

A method for reducing excessive constant-fraction-discriminator walk that utilizes experimental data in the off-line analysis stage is introduced. Excessive walk is defined here as any walk that leads to an overall timing resolution that is much greater than the intrinsic timing resolution of the detection system. The method is able to reduce the contribution to the overall timing resolution from the walk that is equal to or less than the intrinsic timing resolution of the detectors. Although the method is explained in the context of a neutron time-of-flight experiment, it is applicable to any data set that satisfies two conditions. (1) A measure of the signal amplitude for each event must be recorded on an event-by-event basis; and (2) There must be a distinguishable class of events present where the timing information is known a priori
Elastic constants and internal friction of fiber-reinforced composites

International Nuclear Information System (INIS)

Ledbetter, H.M.

1982-01-01

We review recent experimental studies at NBS on the anisotropic elastic constants and internal friction of fiber-reinforced composites. Materials that were studied include: boron-aluminum, boron-epoxy, graphite-epoxy, glass-epoxy, and aramid-epoxy. In all cases, elastic-constant direction dependence could be described by relationships developed for single crystals of homogeneous materials. Elastic stiffness and internal friction were found to vary inversely
Elastic constants of a Laves phase compound: C15 NbCr2

International Nuclear Information System (INIS)

Ormeci, A.; Chu, F.; Wills, J.M.; Chen, S.P.; Albers, R.C.; Thoma, D.J.; Mitchell, T.E.

1997-01-01

The single-crystal elastic constants of C15 NbCr 2 have been computed by using a first-principles, self-consistent, full-potential total energy method. From these single-crystal elastic constants the isotropic elastic moduli are calculated using the Voigt and Reuss averages. The calculated values are in fair agreement with the experimental values. The implications of the results are discussed with regards to Poisson's ratio and the direction dependence of Young's modulus
The time-walk of analog constant fraction discriminators using very fast scintillator detectors with linear and non-linear energy response

Energy Technology Data Exchange (ETDEWEB)

Regis, J.-M., E-mail: regis@ikp.uni-koeln.de [Institut fuer Kernphysik der Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany); Rudigier, M.; Jolie, J.; Blazhev, A.; Fransen, C.; Pascovici, G.; Warr, N. [Institut fuer Kernphysik der Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany)

2012-08-21

The electronic {gamma}-{gamma} fast timing technique allows for direct nuclear lifetime determination down to the few picoseconds region by measuring the time difference between two coincident {gamma}-ray transitions. Using high resolution ultra-fast LaBr{sub 3}(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 {gamma}-{gamma} time-walk characteristics, respectively, for either a linear or a non-linear amplitude versus energy dependency of the scintillator detector output pulses.
Single start multiple stop time digitizer

International Nuclear Information System (INIS)

Deshpande, P.A.; Mukhopadhyay, P.K.; Gopalakrishnan, K.R.

1997-01-01

A single start multiple stop time digitizer has been developed which can digitize the time between a start pulse and multiple stop pulses. The system has been designed as a PC add on card. The resolution of the instrument is 10 nSecs and the maximum length of time that it can measure is 1.28 milliseconds. Apart from time digitization, it can also resolve the height of the incoming pulses into 64 levels. After each input pulse the system dead time is less than 300 nSecs. The driver software for this card has been developed on DOS platform. It uses graphical user interface to provide a user friendly environment. The system is intended to be used in time of flight mass spectroscopy experiments. It can also be used for time of flight experiments in nuclear physics. (author). 2 figs
Implementation of a two-qubit controlled-rotation gate based on unconventional geometric phase with a constant gating time

International Nuclear Information System (INIS)

Yabu-uti, B.F.C.; Roversi, J.A.

2011-01-01

We propose an alternative scheme to implement a two-qubit controlled-R (rotation) gate in the hybrid atom-CCA (coupled cavities array) system. Our scheme results in a constant gating time and, with an adjustable qubit-bus coupling (atom-resonator), one can specify a particular rotation R on the target qubit. We believe that this proposal may open promising perspectives for networking quantum information processors and implementing distributed and scalable quantum computation. -- Highlights: → We propose an alternative two-qubit controlled-rotation gate implementation. → Our gate is realized in a constant gating time for any rotation. → A particular rotation on the target qubit can be specified by an adjustable qubit-bus coupling. → Our proposal may open promising perspectives for implementing distributed and scalable quantum computation.
Building evolutionary architectures support constant change

CERN Document Server

Ford, Neal; Kua, Patrick

2017-01-01

The software development ecosystem is constantly changing, providing a constant stream of new tools, frameworks, techniques, and paradigms. Over the past few years, incremental developments in core engineering practices for software development have created the foundations for rethinking how architecture changes over time, along with ways to protect important architectural characteristics as it evolves. This practical guide ties those parts together with a new way to think about architecture and time.
Dynamics of the cosmological and Newton’s constant

International Nuclear Information System (INIS)

Smolin, Lee

2016-01-01

A modification of general relativity is presented in which Newton’s constant, G, and the cosmological constant, Λ, become a conjugate pair of dynamical variables. These are functions of a global time, hence the theory is presented in the framework of shape dynamics, which trades many-fingered time for a local scale invariance and an overall reparametrization of the global time. As a result, due to the fact that these global dynamical variables are canonically conjugate, the field equations are consistent. The theory predicts a relationship with no free parameters between the rates of change of Newton’s constant and the cosmological constant, in terms of the spatial average of the matter Lagrangian density. (paper)
Off-line correction for excessive constant-fraction-discriminator walk in neutron time-of-flight experiments

International Nuclear Information System (INIS)

Heilbronn, L.; Iwata, Y.; Iwase, H.

2004-01-01

A method for reducing excessive constant-fraction-discriminator walk that utilizes experimental data in the off-line analysis stage is introduced. Excessive walk is defined here as any walk that leads to an overall timing resolution that is much greater than the intrinsic timing resolution of the detection system. The method is able to reduce the contribution to the overall timing resolution from the walk to a value that is equal to or less than the intrinsic timing resolution of the detectors. Although the method is explained in the context of a neutron time-of-flight experiment, it is applicable to any data set that satisfies two conditions: (1) a measure of the signal amplitude for each event must be recorded on an event-by-event basis; and (2) there must be a distinguishable class of events present where the timing information is known a priori

Influence of the Gilbert damping constant on the flux rise time of write head fields

International Nuclear Information System (INIS)

Ertl, Othmar; Schrefl, Thomas; Suess, Dieter; Schabes, Manfred E.

2005-01-01

Magnetic recording at fast data rates requires write heads with rapid rise times of the magnetic flux during the write process. We present three-dimensional (3D) micromagnetic finite element calculations of an entire ring head including 3D coil geometry during the writing of magnetic bits in granular media. The simulations demonstrate how input current profiles translate into magnetization processes in the head and which in turn generate the write head field. The flux rise time significantly depends on the Gilbert damping constant of the head material. Low damping causes incoherent magnetization processes, leading to long rise times and low head fields. High damping leads to coherent reversal of the magnetization in the head. As a consequence, the gap region can be quickly saturated which causes high head fields with short rise times
Derivation of the fine-structure constant

International Nuclear Information System (INIS)

Samec, A.

1980-01-01

The fine-structure constant is derived as a dynamical property of quantum electrodynamics. Single-particle solutions of the coupled Maxwell and Dirac equations have a physical charge spectrum. The solutions are used to construct lepton-and quark-like particles. The strong, weak, electromagnetic, and gravitational forces are described as the interactions of complex charges in multiple combinations
Gendered Expectations? Reconsidering Single Fathers' Child-Care Time

Science.gov (United States)

Hook, Jennifer L.; Chalasani, Satvika

2008-01-01

We take a fresh look at an important question in the sociology of gender and family: Do single fathers "mother"? We add to the theoretical debate by proposing that single fathers face competing interactional pressures, to simultaneously act like mothers and men. Using nationally representative data from the American Time Use Survey 2003-2006 (N =…
Nature of tracing dimension, imaginary order of freedom and our observed time passing at constant speed

International Nuclear Information System (INIS)

Nagao, S

2009-01-01

Nature of the time and requirements to work as a time dimension are investigated. A potential scenario of the development of the universe is conceptually investigated starting from energy as vibration in multiple dimensions. A model is proposed, in which the Big Bang is a phase transition of energy from vibration in 4-dimensional space to energy distribution in 3-D surface of a 4-D sphere. The Time which we observe passing at a constant speed is not such a reference frame which we unintentionally believe to be the time, but the radius dimension of the 4-D sphere. The feature of the Dark Matter and the mystery of the Dark Energy are naturally explained from the model.
Nature of tracing dimension, imaginary order of freedom and our observed time passing at constant speed

Energy Technology Data Exchange (ETDEWEB)

Nagao, S, E-mail: snagao@lilac.plala.or.j [Business Development and Licensing Department, Nippon Boehringer Ingelheim Co., Ltd., ThinkPark Tower, 2-1-1, Osaki, Shinagawa, Tokyo 141-6017 (Japan)

2009-06-01

Nature of the time and requirements to work as a time dimension are investigated. A potential scenario of the development of the universe is conceptually investigated starting from energy as vibration in multiple dimensions. A model is proposed, in which the Big Bang is a phase transition of energy from vibration in 4-dimensional space to energy distribution in 3-D surface of a 4-D sphere. The Time which we observe passing at a constant speed is not such a reference frame which we unintentionally believe to be the time, but the radius dimension of the 4-D sphere. The feature of the Dark Matter and the mystery of the Dark Energy are naturally explained from the model.
EVALUTION OF THE SINGLE INTERCITY FREIGHT TRANSPORTATION WAITING TIME

Directory of Open Access Journals (Sweden)

N. Ponomariova

2015-07-01

Full Text Available The example of vechicle operation on the pendulum intercity route during single freightages processing is considered. Two approaches to the definition of the single freightage waiting time by the carrier are proposed. These approaches allow to take into account the probability of the single freightage obtaining by the carrier during the different load level of the transport enterprise capacity.
Can a quantum state over time resemble a quantum state at a single time?

Science.gov (United States)

Horsman, Dominic; Heunen, Chris; Pusey, Matthew F; Barrett, Jonathan; Spekkens, Robert W

2017-09-01

The standard formalism of quantum theory treats space and time in fundamentally different ways. In particular, a composite system at a given time is represented by a joint state, but the formalism does not prescribe a joint state for a composite of systems at different times. If there were a way of defining such a joint state, this would potentially permit a more even-handed treatment of space and time, and would strengthen the existing analogy between quantum states and classical probability distributions. Under the assumption that the joint state over time is an operator on the tensor product of single-time Hilbert spaces, we analyse various proposals for such a joint state, including one due to Leifer and Spekkens, one due to Fitzsimons, Jones and Vedral, and another based on discrete Wigner functions. Finding various problems with each, we identify five criteria for a quantum joint state over time to satisfy if it is to play a role similar to the standard joint state for a composite system: that it is a Hermitian operator on the tensor product of the single-time Hilbert spaces; that it represents probabilistic mixing appropriately; that it has the appropriate classical limit; that it has the appropriate single-time marginals; that composing over multiple time steps is associative. We show that no construction satisfies all these requirements. If Hermiticity is dropped, then there is an essentially unique construction that satisfies the remaining four criteria.
Optimize Etching Based Single Mode Fiber Optic Temperature Sensor

OpenAIRE

Ajay Kumar; Dr. Pramod Kumar

2014-01-01

This paper presents a description of etching process for fabrication single mode optical fiber sensors. The process of fabrication demonstrates an optimized etching based method to fabricate single mode fiber (SMF) optic sensors in specified constant time and temperature. We propose a single mode optical fiber based temperature sensor, where the temperature sensing region is obtained by etching its cladding diameter over small length to a critical value. It is observed that th...
A versatile optical microscope for time-dependent single-molecule and single-particle spectroscopy

Science.gov (United States)

Li, Hao; Yang, Haw

2018-03-01

This work reports the design and implementation of a multi-function optical microscope for time-dependent spectroscopy on single molecules and single nanoparticles. It integrates the now-routine single-object measurements into one standalone platform so that no reconfiguration is needed when switching between different types of sample or spectroscopy modes. The illumination modes include evanescent field through total internal reflection, dark-field illumination, and epi-excitation onto a diffraction-limited spot suitable for confocal detection. The detection modes include spectrally resolved line imaging, wide-field imaging with dual-color capability, and two-color single-element photon-counting detection. The switch between different spectroscopy and data acquisition modes is fully automated and executed through computer programming. The capability of this microscope is demonstrated through selected proof-of-principle experiments.
A versatile optical microscope for time-dependent single-molecule and single-particle spectroscopy.

Science.gov (United States)

Li, Hao; Yang, Haw

2018-03-28

This work reports the design and implementation of a multi-function optical microscope for time-dependent spectroscopy on single molecules and single nanoparticles. It integrates the now-routine single-object measurements into one standalone platform so that no reconfiguration is needed when switching between different types of sample or spectroscopy modes. The illumination modes include evanescent field through total internal reflection, dark-field illumination, and epi-excitation onto a diffraction-limited spot suitable for confocal detection. The detection modes include spectrally resolved line imaging, wide-field imaging with dual-color capability, and two-color single-element photon-counting detection. The switch between different spectroscopy and data acquisition modes is fully automated and executed through computer programming. The capability of this microscope is demonstrated through selected proof-of-principle experiments.
Appropriate control time constant in relation to characteristics of the baroreflex vascular system in 1/R control of the total artificial heart.

Science.gov (United States)

Mizuta, Sora; Saito, Itsuro; Isoyama, Takashi; Hara, Shintaro; Yurimoto, Terumi; Li, Xinyang; Murakami, Haruka; Ono, Toshiya; Mabuchi, Kunihiko; Abe, Yusuke

2017-09-01

1/R control is a physiological control method of the total artificial heart (TAH) with which long-term survival was obtained with animal experiments. However, 1/R control occasionally diverged in the undulation pump TAH (UPTAH) animal experiment. To improve the control stability of the 1/R control, appropriate control time constant in relation to characteristics of the baroreflex vascular system was investigated with frequency analysis and numerical simulation. In the frequency analysis, data of five goats in which the UPTAH was implanted were analyzed with first Fourier transform technique to examine the vasomotion frequency. The numerical simulation was carried out repeatedly changing baroreflex parameters and control time constant using the elements-expanded Windkessel model. Results of the frequency analysis showed that the 1/R control tended to diverge when very low frequency band that was an indication of the vasomotion frequency was relative high. In numerical simulation, divergence of the 1/R control could be reproduced and the boundary curves between the divergence and convergence of the 1/R control varied depending on the control time constant. These results suggested that the 1/R control tended to be unstable when the TAH recipient had high reflex speed in the baroreflex vascular system. Therefore, the control time constant should be adjusted appropriately with the individual vasomotion frequency.
The Hubble constant estimation using 18 gravitational lensing time delays

Science.gov (United States)

Jaelani, Anton T.; Premadi, Premana W.

2014-03-01

Gravitational lens time delay method has been used to estimate the rate of cosmological expansion, called the Hubble constant, H0, independently of the standard candle method. This gravitational lensing method requires a good knowledge of the lens mass distribution, reconstructed using the lens image properties. The observed positions of the images, and the redshifts of the lens and the images serve as strong constraints to the lens equations, which are then solved as a set of simultaneous linear equations. Here we made use of a non-parametric technique to reconstruct the lens mass distribution, which is manifested in a linear equations solver named PixeLens. Input for the calculation is chosen based on prior known parameters obtained from analyzed result of the lens case observations, including time-delay, position angles of the images and the lens, and their redshifts. In this project, 18 fairly well studied lens cases are further grouped according to a number of common properties to examine how each property affects the character of the data, and therefore affects the calculation of H0. The considered lens case properties are lens morphology, number of image, completeness of time delays, and symmetry of lens mass distribution. Analysis of simulation shows that paucity of constraints on mass distribution of a lens yields wide range value of H0, which reflects the uniqueness of each lens system. Nonetheless, gravitational lens method still yields H0 within an acceptable range of value when compared to those determined by many other methods. Grouping the cases in the above manner allowed us to assess the robustness of PixeLens and thereby use it selectively. In addition, we use glafic, a parametric mass reconstruction solver, to refine the mass distribution of one lens case, as a comparison.
Constant physics and characteristics of fundamental constant

International Nuclear Information System (INIS)

Tarrach, R.

1998-01-01

We present some evidence which supports a surprising physical interpretation of the fundamental constants. First, we relate two of them through the renormalization group. This leaves as many fundamental constants as base units. Second, we introduce and a dimensional system of units without fundamental constants. Third, and most important, we find, while interpreting the units of the a dimensional system, that is all cases accessible to experimentation the fundamental constants indicate either discretization at small values or boundedness at large values of the corresponding physical quantity. (Author) 12 refs
Study of the Bulk Charge Carrier Dynamics in Anatase and Rutile TiO2 Single Crystals by Femtosecond Time Resolved Spectroscopy

KAUST Repository

Maity, Partha

2018-04-02

Understanding of the fundamentals behind charge carriers of photo-catalytic materials are still illusive hindering progress in our quest for renewable energy. TiO2 anatase and rutile are the most understood phases in photo-catalysis and serve as the best model for fundamental studies. Their ultrafast charge carrier dynamics especially on TiO2 anatase single crystal (the most active phase) are unresolved. Here femtosecond time resolved spectroscopy (TRS) was carried out to explore the dynamics of photo-excited charge carriers’ recombination in anatase single crystal, for the first time using pump fluence effects, and compares it to that of the rutile single crystal. A significant difference in charge carrier recombination rates between both crystals is observed. We found that the time constants for carrier recombination are two orders of magnitude slower for anatase (101) when compared to those of rutile (110). Moreover, bulk defects introduced by reduction of the samples via annealing in ultra-high vacuum resulted in faster recombination rates for both polymorphs. Both states (fresh and reduced) probed by pump fluence dependence measurements revealed that the major recombination channel in fresh and reduced anatase and reduced rutile is the first-order Shockley–Reed mediated. However, for fresh rutile, third-body Auger recombination was observed, attributed to the presence of higher density of intrinsic charge carriers. At all excitation wavelengths and fluence investigated, anatase (101) single crystal show longer charge carrier lifetime when compared to rutile (110) single. This may explain the superiority of the anatase phase for the electron transfer H+ reduction to molecular hydrogen.
Time expansion chamber and single ionization cluster measurement

International Nuclear Information System (INIS)

Walenta, A.H.

1978-10-01

The time expansion chamber (TEC), a new type of drift chamber, allows the measurement of microscopic details of ionization. The mean drift time interval from subsequent sngle ionization clusters of a relativistic particle in the TEC can be made large enough compared to the width of a anode signal to allow the recording of the clusters separately. Since single primary electrons can be detected, the cluster counting would allow an improved particle separation using the relativistic rise of primary ionization. In another application, very high position accuracy for track detectors or improved energy resolution may be obtained. Basic ionization phenomena and drift properties can be measured at the single electron level
Single-time reduction of bethe-salpeter formalism for two-fermion system

International Nuclear Information System (INIS)

Arkhipov, A.A.

1988-01-01

The single-time reduction method proposed in other refs. for the system of two scalar particles is generalized for the case of two-fermion system. A self-consistent procedure of single-time reduction has been constructed both in terms of the Bethe-Salpeter wave function and in terms of the Green's function of two-fermion system. Three-dimensional dynamic equations have been obtained for single-time wave functions and two-time Green's functions of a two-fermion system and the Schroedinger structure of the equations obtained is shown to be a consequence of the causality structure of the local QFT. 32 refs
Tachyon constant-roll inflation

Science.gov (United States)

Mohammadi, A.; Saaidi, Kh.; Golanbari, T.

2018-04-01

The constant-roll inflation is studied where the inflaton is taken as a tachyon field. Based on this approach, the second slow-roll parameter is taken as a constant which leads to a differential equation for the Hubble parameter. Finding an exact solution for the Hubble parameter is difficult and leads us to a numerical solution for the Hubble parameter. On the other hand, since in this formalism the slow-roll parameter η is constant and could not be assumed to be necessarily small, the perturbation parameters should be reconsidered again which, in turn, results in new terms appearing in the amplitude of scalar perturbations and the scalar spectral index. Utilizing the numerical solution for the Hubble parameter, we estimate the perturbation parameter at the horizon exit time and compare it with observational data. The results show that, for specific values of the constant parameter η , we could have an almost scale-invariant amplitude of scalar perturbations. Finally, the attractor behavior for the solution of the model is presented, and we determine that the feature could be properly satisfied.
Path integration of head direction: updating a packet of neural activity at the correct speed using neuronal time constants.

Science.gov (United States)

Walters, D M; Stringer, S M

2010-07-01

A key question in understanding the neural basis of path integration is how individual, spatially responsive, neurons may self-organize into networks that can, through learning, integrate velocity signals to update a continuous representation of location within an environment. It is of vital importance that this internal representation of position is updated at the correct speed, and in real time, to accurately reflect the motion of the animal. In this article, we present a biologically plausible model of velocity path integration of head direction that can solve this problem using neuronal time constants to effect natural time delays, over which associations can be learned through associative Hebbian learning rules. The model comprises a linked continuous attractor network and competitive network. In simulation, we show that the same model is able to learn two different speeds of rotation when implemented with two different values for the time constant, and without the need to alter any other model parameters. The proposed model could be extended to path integration of place in the environment, and path integration of spatial view.
Comparison of Cole-Cole and Constant Phase Angle modeling in time-domain induced polarization

DEFF Research Database (Denmark)

Lajaunie, Myriam; Maurya, Pradip Kumar; Fiandaca, Gianluca

The Cole-Cole model and the constant phase angle (CPA) model are two prevailing phenomenological descriptions of the induced polarization (IP), used for both frequency domain (FD) and time domain (TD) modeling. The former one is a 4-parameter description, while the latest one involves only two......, forward modeling of quadrupolar sequences on 1D and 2D heterogeneous CPA models shows that the CPA decays differ among each other only by a multiplication factor. Consequently, the inspection of field data in log-log plots gives insight on the modeling needed for fitting them: the CPA inversion cannot...... is reflected in TDIP data, and therefore, at identifying (1) if and when it is possible to distinguish, in time domain, between a Cole-Cole description and a CPA one, and (2) if features of time domain data exist in order to know, from a simple data inspection, which model will be the most adapted to the data...
Elastic constants of a Laves phase compound: C15 NbCr{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Ormeci, A. [Koc Univ., Istanbul (Turkey)]|[Los Alamos National Lab., NM (United States); Chu, F.; Wills, J.M.; Chen, S.P.; Albers, R.C.; Thoma, D.J.; Mitchell, T.E. [Los Alamos National Lab., NM (United States)

1997-04-01

The single-crystal elastic constants of C15 NbCr{sub 2} have been computed by using a first-principles, self-consistent, full-potential total energy method. From these single-crystal elastic constants the isotropic elastic moduli are calculated using the Voigt and Reuss averages. The calculated values are in fair agreement with the experimental values. The implications of the results are discussed with regards to Poisson`s ratio and the direction dependence of Young`s modulus.

Analysis of single-photon time resolution of FBK silicon photomultipliers

International Nuclear Information System (INIS)

Acerbi, Fabio; Ferri, Alessandro; Gola, Alberto; Zorzi, Nicola; Piemonte, Claudio

2015-01-01

We characterized and analyzed an important feature of silicon photomultipliers: the single-photon time resolution (SPTR). We characterized the SPTR of new RGB (Red–Green–Blue) type Silicon Photomultipliers and SPADs produced at FBK (Trento, Italy), studying its main limiting factors. We compared time resolution of 1×1 mm 2 and 3×3 mm 2 SiPMs and a single SiPM cell (i.e. a SPAD with integrated passive-quenching), employing a mode-locked pulsed laser with 2-ps wide pulses. We estimated the contribution of front-end electronic-noise, of cell-to-cell uniformity, and intrinsic cell time-resolution. At a single-cell level, we compared the results obtained with different layouts. With a circular cell with a top metallization covering part of the edge and enhancing the signal extraction, we reached ~20 ps FWHM of time resolution
Time-resolved luminescent spectroscopy of YAG:Ce single crystal and single crystalline films

International Nuclear Information System (INIS)

Zorenko, Yu.; Gorbenko, V.; Savchyn, V.; Vozniak, T.; Puzikov, V.; Danko, A.; Nizhankovski, S.

2010-01-01

The peculiarities of the luminescence and energy transfer from YAG host to the emission centers formed by the Y Al antisite defects and Ce 3+ ions have been studied in YAG:Ce single crystals, grown from the melt by modified Bridgman method in Ar and CO 2 + H 2 atmospheres, and YAG:Ce single crystalline film, grown by liquid phase epitaxy method, using the comparative time-resolved luminescent spectroscopy under excitation by synchrotron radiation in the range of fundamental adsorption of this garnet.
Experimental determination of third-order elastic constants of diamond.

Science.gov (United States)

Lang, J M; Gupta, Y M

2011-03-25

To determine the nonlinear elastic response of diamond, single crystals were shock compressed along the [100], [110], and [111] orientations to 120 GPa peak elastic stresses. Particle velocity histories and elastic wave velocities were measured by using laser interferometry. The measured elastic wave profiles were used, in combination with published acoustic measurements, to determine the complete set of third-order elastic constants. These constants represent the first experimental determination, and several differ significantly from those calculated by using theoretical models.
Analysis of single-photon time resolution of FBK silicon photomultipliers

Energy Technology Data Exchange (ETDEWEB)

Acerbi, Fabio, E-mail: acerbi@fbk.eu; Ferri, Alessandro; Gola, Alberto; Zorzi, Nicola; Piemonte, Claudio

2015-07-01

We characterized and analyzed an important feature of silicon photomultipliers: the single-photon time resolution (SPTR). We characterized the SPTR of new RGB (Red–Green–Blue) type Silicon Photomultipliers and SPADs produced at FBK (Trento, Italy), studying its main limiting factors. We compared time resolution of 1×1 mm{sup 2} and 3×3 mm{sup 2} SiPMs and a single SiPM cell (i.e. a SPAD with integrated passive-quenching), employing a mode-locked pulsed laser with 2-ps wide pulses. We estimated the contribution of front-end electronic-noise, of cell-to-cell uniformity, and intrinsic cell time-resolution. At a single-cell level, we compared the results obtained with different layouts. With a circular cell with a top metallization covering part of the edge and enhancing the signal extraction, we reached ~20 ps FWHM of time resolution.
Type Ia Supernovae Progenitor Problem and the Variation of Fundamental Constants

Directory of Open Access Journals (Sweden)

Rybicki M.

2016-01-01

Full Text Available Cosmological observations strongly suggest our universe is the interior of an expanding black hole. If the constant mass of the universe is assumed then from the equation for Schwarzschild radius: r S = 2 Gmc it follows that proportionality constant Gc depends linearly on the universe’s radius R u , identified with r S , i.e. Gc Because the Chandrasekhar limit M Ch relates to the speed of light and to the Newton’s constant as M Ch ( c = G 3 = 2 so expansion involves gradual decrease of M Ch . In result, a single white dwarf can alone become the Type Ia supernova progenitor, which provides a complementary solution to single-degenerate and double-degenerate models for SNe Ia. Both alternative scenarios: G R u and c R are analyzed in regard of their consistence with observations, and their consequences to cosmology.
Zero cosmological constant from normalized general relativity

International Nuclear Information System (INIS)

Davidson, Aharon; Rubin, Shimon

2009-01-01

Normalizing the Einstein-Hilbert action by the volume functional makes the theory invariant under constant shifts in the Lagrangian. The associated field equations then resemble unimodular gravity whose otherwise arbitrary cosmological constant is now determined as a Machian universal average. We prove that an empty space-time is necessarily Ricci tensor flat, and demonstrate the vanishing of the cosmological constant within the scalar field paradigm. The cosmological analysis, carried out at the mini-superspace level, reveals a vanishing cosmological constant for a universe which cannot be closed as long as gravity is attractive. Finally, we give an example of a normalized theory of gravity which does give rise to a non-zero cosmological constant.
EFFECT OF STRAIN HARDENING ON FATIGUE CRACK CLOSURE IN ALUMINUM ALLOY UNDER CONSTANT AMPLITUDE WITH SINGLE OVERLOAD

Directory of Open Access Journals (Sweden)

Nirpesh Vikram

2015-12-01

Full Text Available In this study effect of strain hardening on crack closure has been examined with the help of experiments and finite element method on the side edge notched specimen of five different Aluminum alloy (3003 Al, 5052 Al, 6061 T6, 6063 T6, 6351 in mode I under constant amplitude fatigue loading with single overload using Abaqus® 6.10 which is very well accepted FEM application in research. Extended Finite Element Method Module has been used to determine effective stress intensity factor at the crack tip while propagation takes place. FEM results have given good agreement with experimental results. Regression analysis has also been done with SPSS® 16 and dependency of strain hardening coefficient on crack closure has analyzed. A generalized empirical formula has been developed based on strain hardening to calculate effective stress intensity range ratio and a modified Paris law has also been formulated for these aluminum alloy.
Fourth-order constants of motion for time independent classical and quantum systems in three dimensions

International Nuclear Information System (INIS)

Chand, F.

2010-01-01

Exact fourth-order constants of motion are investigated for three-dimensional classical and quantum Hamiltonian systems. The rationalization method is utilized to obtain constants of motion for classical systems. Constants of motion for quantum systems are obtained by adding quantum correction terms, computed using Moyal's bracket, to the corresponding classical counterparts. (author)
[Compared Markov with fractal models by using single-channel experimental and simulation data].

Science.gov (United States)

Lan, Tonghan; Wu, Hongxiu; Lin, Jiarui

2006-10-01

The gating mechanical kinetical of ion channels has been modeled as a Markov process. In these models it is assumed that the channel protein has a small number of discrete conformational states and kinetic rate constants connecting these states are constant, the transition rate constants among the states is independent both of time and of the previous channel activity. It is assumed in Liebovitch's fractal model that the channel exists in an infinite number of energy states, consequently, transitions from one conductance state to another would be governed by a continuum of rate constants. In this paper, a statistical comparison is presented of Markov and fractal models of ion channel gating, the analysis is based on single-channel data from ion channel voltage-dependence K+ single channel of neuron cell and simulation data from three-states Markov model.
Fine-structure constant: Is it really a constant

International Nuclear Information System (INIS)

Bekenstein, J.D.

1982-01-01

It is often claimed that the fine-structure ''constant'' α is shown to be strictly constant in time by a variety of astronomical and geophysical results. These constrain its fractional rate of change alpha-dot/α to at least some orders of magnitude below the Hubble rate H 0 . We argue that the conclusion is not as straightforward as claimed since there are good physical reasons to expect alpha-dot/α 0 . We propose to decide the issue by constructing a framework for a variability based on very general assumptions: covariance, gauge invariance, causality, and time-reversal invariance of electromagnetism, as well as the idea that the Planck-Wheeler length (10 -33 cm) is the shortest scale allowable in any theory. The framework endows α with well-defined dynamics, and entails a modification of Maxwell electrodynamics. It proves very difficult to rule it out with purely electromagnetic experiments. In a cosmological setting, the framework predicts an alpha-dot/α which can be compatible with the astronomical constraints; hence, these are too insensitive to rule out α variability. There is marginal conflict with the geophysical constraints: however, no firm decision is possible because of uncertainty about various cosmological parameters. By contrast the framework's predictions for spatial gradients of α are in fatal conflict with the results of the Eoetvoes-Dicke-Braginsky experiments. Hence these tests of the equivalence principle rule out with confidence spacetime variability of α at any level
CODATA recommended values of the fundamental constants

International Nuclear Information System (INIS)

Mohr, Peter J.; Taylor, Barry N.

2000-01-01

A review is given of the latest Committee on Data for Science and Technology (CODATA) adjustment of the values of the fundamental constants. The new set of constants, referred to as the 1998 values, replaces the values recommended for international use by CODATA in 1986. The values of the constants, and particularly the Rydberg constant, are of relevance to the calculation of precise atomic spectra. The standard uncertainty (estimated standard deviation) of the new recommended value of the Rydberg constant, which is based on precision frequency metrology and a detailed analysis of the theory, is approximately 1/160 times the uncertainty of the 1986 value. The new set of recommended values as well as a searchable bibliographic database that gives citations to the relevant literature is available on the World Wide Web at physics.nist.gov/constants and physics.nist.gov/constantsbib, respectively
Larson-Miller Constant of Heat-Resistant Steel

Science.gov (United States)

Tamura, Manabu; Abe, Fujio; Shiba, Kiyoyuki; Sakasegawa, Hideo; Tanigawa, Hiroyasu

2013-06-01

Long-term rupture data for 79 types of heat-resistant steels including carbon steel, low-alloy steel, high-alloy steel, austenitic stainless steel, and superalloy were analyzed, and a constant for the Larson-Miller (LM) parameter was obtained in the current study for each material. The calculated LM constant, C, is approximately 20 for heat-resistant steels and alloys except for high-alloy martensitic steels with high creep resistance, for which C ≈ 30 . The apparent activation energy was also calculated, and the LM constant was found to be proportional to the apparent activation energy with a high correlation coefficient, which suggests that the LM constant is a material constant possessing intrinsic physical meaning. The contribution of the entropy change to the LM constant is not small, especially for several martensitic steels with large values of C. Deformation of such martensitic steels should accompany a large entropy change of 10 times the gas constant at least, besides the entropy change due to self-diffusion.
Cosmological Hubble constant and nuclear Hubble constant

International Nuclear Information System (INIS)

Horbuniev, Amelia; Besliu, Calin; Jipa, Alexandru

2005-01-01

The evolution of the Universe after the Big Bang and the evolution of the dense and highly excited nuclear matter formed by relativistic nuclear collisions are investigated and compared. Values of the Hubble constants for cosmological and nuclear processes are obtained. For nucleus-nucleus collisions at high energies the nuclear Hubble constant is obtained in the frame of different models involving the hydrodynamic flow of the nuclear matter. Significant difference in the values of the two Hubble constant - cosmological and nuclear - is observed
Measurements of natural frequency and damping constant of single steam bubble oscillating in water

International Nuclear Information System (INIS)

Morioka, Mikio

1983-01-01

The natural frequency fsub(n) and damping constant delta of a bubble in liquid have been determined by observing the resonance of the bubble to forced oscillation. The bubble was retained under a rigid plate horizontal disk, and the oscillation was applied by underwater speaker. The applied frequency f was kept constant while letting the bubble increase its volume and vary its radius R. Bubble resonance was detected by observing wrinkles appearing on the bubble due to surface waves. Resonance curves relating the amplitude of bubble radius variation to the intensity of applied oscillation is derived theoretically. Good agreement was seen between the data obtained from experiment and the theoretically derived resonance curves at test to the validity of the method proposed of determining fsub(n) and delta from bubble resonance. The values of delta and of the resonant bubble radius R 0 of large steam bubbles (8.5mm< R<11.5mm) in water were determined at f=270, 290 and 358 Hz. The results support the assumption that for large bubbles the value of fsub(n) is little influenced by the exchange of mass between liquid and gaseous phases through evaporation and condensation accompanying bubble pressure oscillation. On the other hand, delta is found to be one order of magnitude higher than calculated for steam bubbles without taking into evaporation and condensation the interphase exchange of mass. The effect brought on delta by the interphase mass exchange can be taken into account by adding a new constant deltasub(ph) to the terms constituting the total damping constant. (author)
Teaching Generalized Reading of Product Warning Labels to Young Adults with Autism Using the Constant Time Delay Procedure

Science.gov (United States)

Dogoe, Maud S.; Banda, Devender R.; Lock, Robin H.; Feinstein, Rita

2011-01-01

This study examined the effectiveness of the constant timed delay procedure for teaching two young adults with autism to read, define, and state the contextual meaning of keywords on product warning labels of common household products. Training sessions were conducted in the dyad format using flash cards. Results indicated that both participants…
Computing the Gromov hyperbolicity constant of a discrete metric space

KAUST Repository

Ismail, Anas

2012-07-01

Although it was invented by Mikhail Gromov, in 1987, to describe some family of groups[1], the notion of Gromov hyperbolicity has many applications and interpretations in different fields. It has applications in Biology, Networking, Graph Theory, and many other areas of research. The Gromov hyperbolicity constant of several families of graphs and geometric spaces has been determined. However, so far, the only known algorithm for calculating the Gromov hyperbolicity constant δ of a discrete metric space is the brute force algorithm with running time O (n4) using the four-point condition. In this thesis, we first introduce an approximation algorithm which calculates a O (log n)-approximation of the hyperbolicity constant δ, based on a layering approach, in time O(n2), where n is the number of points in the metric space. We also calculate the fixed base point hyperbolicity constant δr for a fixed point r using a (max, min)−matrix multiplication algorithm by Duan in time O(n2.688)[2]. We use this result to present a 2-approximation algorithm for calculating the hyper-bolicity constant in time O(n2.688). We also provide an exact algorithm to compute the hyperbolicity constant δ in time O(n3.688) for a discrete metric space. We then present some partial results we obtained for designing some approximation algorithms to compute the hyperbolicity constant δ.
Sensitivity of molecular vibrational dynamics to energy exchange rate constants

International Nuclear Information System (INIS)

Billing, G D; Coletti, C; Kurnosov, A K; Napartovich, A P

2003-01-01

The sensitivity of molecular vibrational population dynamics, governing the CO laser operated in fundamental and overtone transitions, to vibration-to-vibration rate constants is investigated. With this aim, three rate constant sets have been used, differing in their completeness (i.e. accounting for single-quantum exchange only, or for multi-quantum exchange with a limited number of rate constants obtained by semiclassical calculations, and, finally, with an exhaustive set of rate constants including asymmetric exchange processes, as well) and in the employed interaction potential. The most complete set among these three is introduced in this paper. An existing earlier kinetic model was updated to include the latter new data. Comparison of data produced by kinetic modelling with the above mentioned sets of rate constants shows that the vibrational distribution function, and, in particular, the CO overtone laser characteristics, are very sensitive to the choice of the model. The most complete model predicts slower evolution of the vibrational distribution, in qualitative agreement with experiments
A new generation of 99.999% enriched 28Si single crystals for the determination of Avogadro’s constant

Science.gov (United States)

Abrosimov, N. V.; Aref'ev, D. G.; Becker, P.; Bettin, H.; Bulanov, A. D.; Churbanov, M. F.; Filimonov, S. V.; Gavva, V. A.; Godisov, O. N.; Gusev, A. V.; Kotereva, T. V.; Nietzold, D.; Peters, M.; Potapov, A. M.; Pohl, H.-J.; Pramann, A.; Riemann, H.; Scheel, P.-T.; Stosch, R.; Wundrack, S.; Zakel, S.

2017-08-01

A metrological challenge is currently underway to replace the present definition of the kilogram. One prerequisite for this is that the Avogadro constant, N A, which defines the number of atoms in a mole, needs to be determined with a relative uncertainty of better than 2 × 10-8. The method applied in this case is based on the x-ray crystal density experiment using silicon crystals. The first attempt, in which silicon of natural isotopic composition was used, failed. The solution chosen subsequently was the usage of silicon highly enriched in 28Si from Russia. First, this paper reviews previous efforts from the very first beginnings to an international collaboration with the goal of producing a 28Si single crystal with a mass of 5 kg, an enrichment greater than 0.9999 and of sufficient chemical purity. Then the paper describes the activities of a follow-up project, conducted by PTB, to produce a new generation of highly enriched silicon in order to demonstrate the quasi-industrial and reliable production of more than 12 kg of the 28Si material with enrichments of five nines. The intention of this project is also to show the availability of 28Si single crystals as a guarantee for the future realisation of the redefined kilogram.
More on non-supersymmetric asymmetric orbifolds with vanishing cosmological constant

International Nuclear Information System (INIS)

Sugawara, Yuji; Wada, Taiki

2016-01-01

We explore various non-supersymmetric type II string vacua constructed based on asymmetric orbifolds of tori with vanishing cosmological constant at the one loop. The string vacua we present are modifications of the models studied in http://dx.doi.org/10.1007/JHEP02(2016)184, of which orbifold group is just generated by a single element. We especially focus on two types of modifications: (i) the orbifold twists include different types of chiral reflections not necessarily removing massless Rarita-Schwinger fields in the 4-dimensional space-time, (ii) the orbifold twists do not include the shift operator. We further discuss the unitarity and stability of constructed non-supersymmetric string vacua, with emphasizing the common features of them.
Large numbers hypothesis. IV - The cosmological constant and quantum physics

Science.gov (United States)

Adams, P. J.

1983-01-01

In standard physics quantum field theory is based on a flat vacuum space-time. This quantum field theory predicts a nonzero cosmological constant. Hence the gravitational field equations do not admit a flat vacuum space-time. This dilemma is resolved using the units covariant gravitational field equations. This paper shows that the field equations admit a flat vacuum space-time with nonzero cosmological constant if and only if the canonical LNH is valid. This allows an interpretation of the LNH phenomena in terms of a time-dependent vacuum state. If this is correct then the cosmological constant must be positive.

Gauge theories, time-dependence of the gravitational constant and antigravity in the early universe

International Nuclear Information System (INIS)

Linde, A.D.

1980-01-01

It is shown that the interaction of the gravitational field with matter leads to a strong modification of the effective gravitational constant in the early universe. In certain cases this leads even to the change of sign of the gravitational constant, i.e. to antigravity in the early universe. (orig.)
SmB6 electron-phonon coupling constant from time- and angle-resolved photoelectron spectroscopy

Science.gov (United States)

Sterzi, A.; Crepaldi, A.; Cilento, F.; Manzoni, G.; Frantzeskakis, E.; Zacchigna, M.; van Heumen, E.; Huang, Y. K.; Golden, M. S.; Parmigiani, F.

2016-08-01

SmB6 is a mixed valence Kondo system resulting from the hybridization between localized f electrons and delocalized d electrons. We have investigated its out-of-equilibrium electron dynamics by means of time- and angle-resolved photoelectron spectroscopy. The transient electronic population above the Fermi level can be described by a time-dependent Fermi-Dirac distribution. By solving a two-temperature model that well reproduces the relaxation dynamics of the effective electronic temperature, we estimate the electron-phonon coupling constant λ to range from 0.13 ±0.03 to 0.04 ±0.01 . These extremes are obtained assuming a coupling of the electrons with either a phonon mode at 10 or 19 meV. A realistic value of the average phonon energy will give an actual value of λ within this range. Our results provide an experimental report on the material electron-phonon coupling, contributing to both the electronic transport and the macroscopic thermodynamic properties of SmB6.
Time since death and decay rate constants of Norway spruce and European larch deadwood in subalpine forests determined using dendrochronology and radiocarbon dating

Science.gov (United States)

Petrillo, M.; Cherubini, P.; Fravolini, G.; Ascher, J.; Schärer, M.; Synal, H.-A.; Bertoldi, D.; Camin, F.; Larcher, R.; Egli, M.

2015-09-01

Due to the large size and highly heterogeneous spatial distribution of deadwood, the time scales involved in the coarse woody debris (CWD) decay of Picea abies (L.) Karst. and Larix decidua Mill. in Alpine forests have been poorly investigated and are largely unknown. We investigated the CWD decay dynamics in an Alpine valley in Italy using the five-decay class system commonly employed for forest surveys, based on a macromorphological and visual assessment. For the decay classes 1 to 3, most of the dendrochronological samples were cross-dated to assess the time that had elapsed since tree death, but for decay classes 4 and 5 (poorly preserved tree rings) and some others not having enough tree rings, radiocarbon dating was used. In addition, density, cellulose and lignin data were measured for the dated CWD. The decay rate constants for spruce and larch were estimated on the basis of the density loss using a single negative exponential model. In the decay classes 1 to 3, the ages of the CWD were similar varying between 1 and 54 years for spruce and 3 and 40 years for larch with no significant differences between the classes; classes 1-3 are therefore not indicative for deadwood age. We found, however, distinct tree species-specific differences in decay classes 4 and 5, with larch CWD reaching an average age of 210 years in class 5 and spruce only 77 years. The mean CWD rate constants were 0.012 to 0.018 yr-1 for spruce and 0.005 to 0.012 yr-1 for larch. Cellulose and lignin time trends half-lives (using a multiple-exponential model) could be derived on the basis of the ages of the CWD. The half-lives for cellulose were 21 yr for spruce and 50 yr for larch. The half-life of lignin is considerably higher and may be more than 100 years in larch CWD.
Heat release determination in a constant volume combustion chamber from the instantaneous cylinder pressure

International Nuclear Information System (INIS)

Lapuerta, Magín; Sanz-Argent, Josep; Raine, Robert

2014-01-01

A diagnostic method has been developed to interpret the results of basic combustion studies with diesel-like fuels performed in a constant volume reactor originally conceived for cetane number measurements. The main target of the method is to calculate the instantaneous heat release over time from the chamber pressure experimental signal. The method incorporates filtering of the raw data to eliminate the oscillations recorded as a consequence of the location of the pressure sensor. It considers homogeneity of the gaseous mixture (single zone model) and change in its composition due to the combustion process. A semi-empirical heat transfer model was also proposed and its coefficients were fitted from experimental results obtained in the constant volume chamber using diesel fuel. -- Highlights: • A diagnostic model for constant volume reactors has been developed and tested. • Updating the gas composition after combustion improves accuracy of the method. • Heat transfer coefficients are used for the fulfillment of boundary conditions. • The model provides a deeper insight than the apparent heat release analysis
Single-Index Additive Vector Autoregressive Time Series Models

KAUST Repository

LI, YEHUA; GENTON, MARC G.

2009-01-01

We study a new class of nonlinear autoregressive models for vector time series, where the current vector depends on single-indexes defined on the past lags and the effects of different lags have an additive form. A sufficient condition is provided
New representation of water activity based on a single solute specific constant to parameterize the hygroscopic growth of aerosols in atmospheric models

Directory of Open Access Journals (Sweden)

S. Metzger

2012-06-01

Full Text Available Water activity is a key factor in aerosol thermodynamics and hygroscopic growth. We introduce a new representation of water activity (a_w, which is empirically related to the solute molality (μ_s through a single solute specific constant, ν_i. Our approach is widely applicable, considers the Kelvin effect and covers ideal solutions at high relative humidity (RH, including cloud condensation nuclei (CCN activation. It also encompasses concentrated solutions with high ionic strength at low RH such as the relative humidity of deliquescence (RHD. The constant ν_i can thus be used to parameterize the aerosol hygroscopic growth over a wide range of particle sizes, from nanometer nucleation mode to micrometer coarse mode particles. In contrast to other a_w-representations, our ν_i factor corrects the solute molality both linearly and in exponent form x · a^x. We present four representations of our basic a_w-parameterization at different levels of complexity for different a_w-ranges, e.g. up to 0.95, 0.98 or 1. ν_i is constant over the selected a_w-range, and in its most comprehensive form, the parameterization describes the entire a_w range (0–1. In this work we focus on single solute solutions. ν_i can be pre-determined with a root-finding method from our water activity representation using an a_w−μ_s data pair, e.g. at solute saturation using RHD and solubility measurements. Our a_w and supersaturation (Köhler-theory results compare well with the thermodynamic reference model E-AIM for the key compounds NaCl and (NH₄₂SO₄ relevant for CCN modeling and calibration studies. Envisaged applications include regional and global atmospheric chemistry and
Memory effects in single-molecule spectroscopy

International Nuclear Information System (INIS)

Schmitt, Daniel T.; Schulz, Michael; Reineker, Peter

2007-01-01

From the time series of LH2 optical single-molecule fluorescence excitation spectra of Rhodospirillum molischianum the memory function of the Mori-Zwanzig equation for the optical intensity is derived numerically. We show that the time dependence of the excited states is determined by at least three different non-Markovian stochastic processes with decay constants for the Mori-Zwanzig kernel on the order of 1-5min -1 . We suggest that this decay stems from the conformational motion of the protein scaffold of LH2
Twinning processes in Cu-Al-Ni martensite single crystals investigated by neutron single crystal diffraction method

International Nuclear Information System (INIS)

Molnar, P.; Sittner, P.; Novak, V.; Lukas, P.

2008-01-01

A neutron single crystal diffraction method for inspecting the quality of martensite single crystals is introduced. True interface-free martensite single crystals are indispensable for, e.g. measurement of elastic constants of phases by ultrasonic techniques. The neutron diffraction method was used to detect and distinguish the presence of individual lattice correspondence variants of the 2H orthorhombic martensite phase in Cu-Al-Ni as well as to follow the activity of twinning processes during the deformation test on the martensite variant single crystals. When preparing the martensite single variant prism-shaped crystals by compression deformation method, typically a small fraction of second unwanted martensitic variant (compound twin) remains in the prism samples. Due to the very low stress (∼1 MPa) for the compound twinning in many shape memory alloys, it is quite difficult not only to deplete the martensite prisms of all internal interfaces but mainly to keep them in the martensite single variant state for a long time needed for further investigations
Real-time Avatar Animation from a Single Image.

Science.gov (United States)

Saragih, Jason M; Lucey, Simon; Cohn, Jeffrey F

2011-01-01

A real time facial puppetry system is presented. Compared with existing systems, the proposed method requires no special hardware, runs in real time (23 frames-per-second), and requires only a single image of the avatar and user. The user's facial expression is captured through a real-time 3D non-rigid tracking system. Expression transfer is achieved by combining a generic expression model with synthetically generated examples that better capture person specific characteristics. Performance of the system is evaluated on avatars of real people as well as masks and cartoon characters.
Cosmological constant in the quantum multiverse

International Nuclear Information System (INIS)

Larsen, Grant; Nomura, Yasunori; Roberts, Hannes L. L.

2011-01-01

Recently, a new framework for describing the multiverse has been proposed which is based on the principles of quantum mechanics. The framework allows for well-defined predictions, both regarding global properties of the universe and outcomes of particular experiments, according to a single probability formula. This provides complete unification of the eternally inflating multiverse and many worlds in quantum mechanics. In this paper, we elucidate how cosmological parameters can be calculated in this framework, and study the probability distribution for the value of the cosmological constant. We consider both positive and negative values, and find that the observed value is consistent with the calculated distribution at an order of magnitude level. In particular, in contrast to the case of earlier measure proposals, our framework prefers a positive cosmological constant over a negative one. These results depend only moderately on how we model galaxy formation and life evolution therein.
Study on the stability of adrenaline and on the determination of its acidity constants

Science.gov (United States)

Corona-Avendaño, S.; Alarcón-Angeles, G.; Rojas-Hernández, A.; Romero-Romo, M. A.; Ramírez-Silva, M. T.

2005-01-01

In this work, the results are presented concerning the influence of time on the spectral behaviour of adrenaline (C 9H 13NO 3) (AD) and of the determination of its acidity constants by means of spectrophotometry titrations and point-by-point analysis, using for the latter freshly prepared samples for each analysis at every single pH. As the catecholamines are sensitive to light, all samples were protected against it during the course of the experiments. Each method rendered four acidity constants corresponding each to the four acid protons belonging to the functional groups present in the molecule; for the point-by-point analysis the values found were: log β 1=38.25±0.21 , log β 2=29.65±0.17 , log β 3=21.01±0.14 , log β 4=11.34±0.071 .
Near-optimality of special periodic protocols for fluid models of single server switched networks with switchover times

Science.gov (United States)

Matveev, A. S.; Ishchenko, R.

2017-11-01

We consider a generic deterministic time-invariant fluid model of a single server switched network, which consists of finitely many infinite size buffers (queues) and receives constant rate inflows of jobs from the outside. Any flow undergoes a multi-phase service, entering a specific buffer after every phase, and ultimately leaves the network; the route of the flow over the buffers is pre-specified, and flows may merge inside the network. They share a common source of service, which can serve at most one buffer at a time and has to switch among buffers from time to time; any switch consumes a nonzero switchover period. With respect to the long-run maximal scaled wip (work in progress) performance metric, near-optimality of periodic scheduling and service protocols is established: the deepest optimum (that is over all feasible processes in the network, irrespective of the initial state) is furnished by such a protocol up to as small error as desired. Moreover, this can be achieved with a special periodic protocol introduced in the paper. It is also shown that the exhaustive policy is optimal for any buffer whose service at the maximal rate does not cause growth of the scaled wip.
Time response of temperature sensors using neural networks

International Nuclear Information System (INIS)

Santos, Roberto Carlos dos

2010-01-01

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)
Lepton Collider Operation with Constant Currents

CERN Document Server

Wienands, Ulrich

2005-01-01

Traditionally, electron-positron colliders have been operating in a top-off-and-coast fashion with a cycle time depending on the beam life time, typically on the order of an hour. Each top-off involves ramping detector systems in addition to the actual filling time. The loss in accumulated luminosity is typically 20-50%. During the last year, both B-Factories have commissioned a continuous-injection mode of operation in which beam is injected without ramping the detector, thus raising luminosity integration by constant operation at peak luminosity. Constant beam currents reduce thermal drift and trips caused by change in beam loading. To achieve this level of operation, special efforts were made to reduce the injection losses and also to implement special gating procedures in the detectors, minimizing dead time. Bunch-injection control decides which bunch to inject into next while maintaining small charge variation between bunches. Beam collimation can reduce injection noise but also cause an increase in back...
Is the sun constant

International Nuclear Information System (INIS)

Blake, J.B.; Dearborn, D.S.P.

1979-01-01

Small fluctuations in the solar constant can occur on timescales much shorter than the Kelvin time. Changes in the ability of convection to transmit energy through the superadiabatic and transition regions of the convection zone cause structure adjustments which can occur on a time scale of days. The bulk of the convection zone reacts to maintain hydrostatic equilibrium (though not thermal equilibrium) and causes a luminosity change. While small radius variations will occur, most of the change will be seen in temperature
A study of group constant generation method in fast reactor analysis

International Nuclear Information System (INIS)

Takano, Hideki

1983-05-01

The methods of generating group constants have been studied to predict accurately the nuclear characteristics of fast reactors. In resonance energy region, the accuracy of the group constants was investigated, which were calculated by the approximate weighting spectrum used for a conventional standards group constant set such as ABBN. It was shown that the basic assumption of constant collision density for group constant calculation was not always satisfactory. Moreover, a multilevel formula was derived without losing the useful characteristics of the Breit-Wigner single level formula. Using this formula, the interference effect between resonances was examined. In addition, the mutual interference between different resonant nuclides was calculated. The cause of a systematic dependence of effective multiplication factors on U-238 concentration ratio was studied, and the cross section adjustment was performed. In the unresolved resonance region, the average resonance parameters were searched. As a result, the JFS-2 set was generated, and several studies were performed to advance the concept of the group constant set JFS-2. (Kako, I.)
Calibration of the fine-structure constant of graphene by time-dependent density-functional theory

Science.gov (United States)

Sindona, A.; Pisarra, M.; Vacacela Gomez, C.; Riccardi, P.; Falcone, G.; Bellucci, S.

2017-11-01

One of the amazing properties of graphene is the ultrarelativistic behavior of its loosely bound electrons, mimicking massless fermions that move with a constant velocity, inversely proportional to a fine-structure constant αg of the order of unity. The effective interaction between these quasiparticles is, however, better controlled by the coupling parameter αg*=αg/ɛ , which accounts for the dynamic screening due to the complex permittivity ɛ of the many-valence electron system. This concept was introduced in a couple of previous studies [Reed et al., Science 330, 805 (2010) and Gan et al., Phys. Rev. B 93, 195150 (2016)], where inelastic x-ray scattering measurements on crystal graphite were converted into an experimentally derived form of αg* for graphene, over an energy-momentum region on the eV Å -1 scale. Here, an accurate theoretical framework is provided for αg*, using time-dependent density-functional theory in the random-phase approximation, with a cutoff in the interaction between excited electrons in graphene, which translates to an effective interlayer interaction in graphite. The predictions of the approach are in excellent agreement with the above-mentioned measurements, suggesting a calibration method to substantially improve the experimental derivation of αg*, which tends to a static limiting value of ˜0.14 . Thus, the ab initio calibration procedure outlined demonstrates the accuracy of perturbation expansion treatments for the two-dimensional gas of massless Dirac fermions in graphene, in parallel with quantum electrodynamics.
Multipurpose discriminator with accurate time coupling

International Nuclear Information System (INIS)

Baldin, B.Yu.; Krumshtejn, Z.V.; Ronzhin, A.I.

1977-01-01

The principle diagram of a multipurpose discriminator is described, designed on the basis of a wide-band differential amplifier. The discriminator has three independent channels: the timing channel, the lower level discriminator and the control channel. The timing channel and the lower level discriminator are connected to a coincidence circuit. Three methods of timing are used: a single threshold, a double threshold with timing on the pulse front, and a constant fraction timing. The lower level discriminator is a wide-band amplifier with an adjustable threshold. The investigation of compensation characteristics of the discriminator has shown that the time shift of the discriminator output in the constant fraction timing regime does not exceed +-75 ns for the input signal range of 1:85. The time resolution was found to be 20 ns in the 20% energy range near the photo-peak maximum of 60 Co γ source
Two-Agent Single-Machine Scheduling of Jobs with Time-Dependent Processing Times and Ready Times

Directory of Open Access Journals (Sweden)

Jan-Yee Kung

2013-01-01

Full Text Available Scheduling involving jobs with time-dependent processing times has recently attracted much research attention. However, multiagent scheduling with simultaneous considerations of jobs with time-dependent processing times and ready times is relatively unexplored. Inspired by this observation, we study a two-agent single-machine scheduling problem in which the jobs have both time-dependent processing times and ready times. We consider the model in which the actual processing time of a job of the first agent is a decreasing function of its scheduled position while the actual processing time of a job of the second agent is an increasing function of its scheduled position. In addition, each job has a different ready time. The objective is to minimize the total completion time of the jobs of the first agent with the restriction that no tardy job is allowed for the second agent. We propose a branch-and-bound and several genetic algorithms to obtain optimal and near-optimal solutions for the problem, respectively. We also conduct extensive computational results to test the proposed algorithms and examine the impacts of different problem parameters on their performance.
Feasibility of a single-parameter description of equilibrium viscous liquid dynamics

DEFF Research Database (Denmark)

Pedersen, Ulf Rørbæk; Christensen, Tage Emil; Schrøder, Thomas

2008-01-01

Molecular dynamics results for the dynamic Prigogine-Defay ratio are presented for two glass-forming liquids, thus evaluating the experimentally relevant quantity for testing whether metastable-equilibrium liquid dynamics is described by a single parameter to a good approximation. For the Kob......-Andersen binary Lennard-Jones mixture as well as for an asymmetric dumbbell model liquid, a single-parameter description works quite well. This is confirmed by time-domain results where it is found that energy and pressure fluctuations are strongly correlated on the alpha time scale in the constant...

A single-vendor and a single-buyer integrated inventory model with ordering cost reduction dependent on lead time

Science.gov (United States)

Vijayashree, M.; Uthayakumar, R.

2017-09-01

Lead time is one of the major limits that affect planning at every stage of the supply chain system. In this paper, we study a continuous review inventory model. This paper investigates the ordering cost reductions are dependent on lead time. This study addressed two-echelon supply chain problem consisting of a single vendor and a single buyer. The main contribution of this study is that the integrated total cost of the single vendor and the single buyer integrated system is analyzed by adopting two different (linear and logarithmic) types ordering cost reductions act dependent on lead time. In both cases, we develop effective solution procedures for finding the optimal solution and then illustrative numerical examples are given to illustrate the results. The solution procedure is to determine the optimal solutions of order quantity, ordering cost, lead time and the number of deliveries from the single vendor and the single buyer in one production run, so that the integrated total cost incurred has the minimum value. Ordering cost reduction is the main aspect of the proposed model. A numerical example is given to validate the model. Numerical example solved by using Matlab software. The mathematical model is solved analytically by minimizing the integrated total cost. Furthermore, the sensitivity analysis is included and the numerical examples are given to illustrate the results. The results obtained in this paper are illustrated with the help of numerical examples. The sensitivity of the proposed model has been checked with respect to the various major parameters of the system. Results reveal that the proposed integrated inventory model is more applicable for the supply chain manufacturing system. For each case, an algorithm procedure of finding the optimal solution is developed. Finally, the graphical representation is presented to illustrate the proposed model and also include the computer flowchart in each model.
Online feedback-controlled renal constant infusion clearances in rats.

Science.gov (United States)

Schock-Kusch, Daniel; Shulhevich, Yury; Xie, Qing; Hesser, Juergen; Stsepankou, Dzmitry; Neudecker, Sabine; Friedemann, Jochen; Koenig, Stefan; Heinrich, Ralf; Hoecklin, Friederike; Pill, Johannes; Gretz, Norbert

2012-08-01

Constant infusion clearance techniques using exogenous renal markers are considered the gold standard for assessing the glomerular filtration rate. Here we describe a constant infusion clearance method in rats allowing the real-time monitoring of steady-state conditions using an automated closed-loop approach based on the transcutaneous measurement of the renal marker FITC-sinistrin. In order to optimize parameters to reach steady-state conditions as fast as possible, a Matlab-based simulation tool was established. Based on this, a real-time feedback-regulated approach for constant infusion clearance monitoring was developed. This was validated by determining hourly FITC-sinistrin plasma concentrations and the glomerular filtration rate in healthy and unilaterally nephrectomized rats. The transcutaneously assessed FITC-sinistrin fluorescence signal was found to reflect the plasma concentration. Our method allows the precise determination of the onset of steady-state marker concentration. Moreover, the steady state can be monitored and controlled in real time for several hours. This procedure is simple to perform since no urine samples and only one blood sample are required. Thus, we developed a real-time feedback-based system for optimal regulation and monitoring of a constant infusion clearance technique.
Electronic measurement of the Boltzmann constant with a quantum-voltage-calibrated Johnson-noise thermometer

NARCIS (Netherlands)

Benz, Samuel; White, D. Rod; Qu, JiFeng; Rogalla, Horst; Tew, Weston

2010-01-01

Currently, the CODATA value of the Boltzmann constant is dominated by a single gas-based thermometry measurement with a relative standard uncertainty of 1.8×10−6 [P.J. Mohr, B.N. Taylor, D.B. Newell, CODATA recommended values of the fundamental physical constants: 2006, Rev. Mod. Phys. 80 (2008)
Strategies for real-time position control of a single atom in cavity QED

International Nuclear Information System (INIS)

Lynn, T W; Birnbaum, K; Kimble, H J

2005-01-01

Recent realizations of single-atom trapping and tracking in cavity QED open the door for feedback schemes which actively stabilize the motion of a single atom in real time. We present feedback algorithms for cooling the radial component of motion for a single atom trapped by strong coupling to single-photon fields in an optical cavity. Performance of various algorithms is studied through simulations of single-atom trajectories, with full dynamical and measurement noise included. Closed loop feedback algorithms compare favourably to open loop 'switching' analogues, demonstrating the importance of applying actual position information in real time. The high optical information rate in current experiments enables real-time tracking that approaches the standard quantum limit for broadband position measurements, suggesting that realistic active feedback schemes may reach a regime where measurement backaction appreciably alters the motional dynamics
Mineral dielectric constants and the oxide additivity rule

International Nuclear Information System (INIS)

Shannon, R.D.; Subramanian, M.A.; Mariano, A.N.; Rossman, G.R.

1989-01-01

The 1 MHz dielectric constants of a variety of synthetic aluminate garnets: Y 3 Al 5 O 12 , Ho 3 Al 5 O 12 , Y 2.93 Nd .07 Sc 2 Al 3 O 12 and Gd 2.95 Nd .05 Sc 1.98 Cr .02 Al 3 O 12 and several silicates: CaB 2 Si 2 O 8 (danburite), Ca 3 Al 2 Si 3 O 12 (grossular) and Mg 2 Al 4 Si 5 O 18 (cordierite) were determined using the two-terminal method with edge corrections. These data and polarizabilities derived from the published single crystal dielectric constants of simple oxides were used to compare compound polarizabilities obtained from the Clausius-Mosotti equation and the oxide additivity rule
Bi-dimensional arrays of SPAD for time-resolved single photon imaging

International Nuclear Information System (INIS)

Tudisco, S.; Lanzano, L.; Musumeci, F.; Neri, L.; Privitera, S.; Scordino, A.; Condorelli, G.; Fallica, G.; Mazzillo, M.; Sanfilippo, D.; Valvo, G.

2009-01-01

Many scientific areas like astronomy, biophysics, biomedicine, nuclear and plasma science, etc. are interested in the development of a new time-resolved single photon imaging device. Such a device represents today one of the most challenging goals in the field of photonics. In collaboration with Catania R and D staff of ST-Microelectronics (STM) we created, during the last few years, a new avalanche photosensor-Single Photon Avalanche Diode (SPAD) able to detect and count, with excellent performance, single photons. Further we will discuss the possible realization of a single photon imaging device through the many elements integration (bi-dimensional arrays) of SPADs. In order to achieve the goal, it is also important to develop an appropriate readout strategy able to address the time information of each individual sensor and in order to read a great number of elements easily. First prototypes were designed and manufactured by STM and the results are reported here. In the paper we will discuss in particular: (i) sensor performance (gain, photodetection efficiency, timing, after-pulsing, etc.); (ii) array performance (layout, cross-talk, etc.); (iii) readout strategy (quenching, electronics), and (iv) first imaging results (general performance).
The Nature of the Cosmological Constant Problem

Science.gov (United States)

Maia, M. D.; Capistrano, A. J. S.; Monte, E. M.

General relativity postulates the Minkowski space-time as the standard (flat) geometry against which we compare all curved space-times and also as the gravitational ground state where particles, quantum fields and their vacua are defined. On the other hand, experimental evidences tell that there exists a non-zero cosmological constant, which implies in a deSitter ground state, which not compatible with the assumed Minkowski structure. Such inconsistency is an evidence of the missing standard of curvature in Riemann's geometry, which in general relativity manifests itself in the form of the cosmological constant problem. We show how the lack of a curvature standard in Riemann's geometry can be fixed by Nash's theorem on metric perturbations. The resulting higher dimensional gravitational theory is more general than general relativity, similar to brane-world gravity, but where the propagation of the gravitational field along the extra dimensions is a mathematical necessity, rather than a postulate. After a brief introduction to Nash's theorem, we show that the vacuum energy density must remain confined to four-dimensional space-times, but the cosmological constant resulting from the contracted Bianchi identity represents a gravitational term which is not confined. In this case, the comparison between the vacuum energy and the cosmological constant in general relativity does not make sense. Instead, the geometrical fix provided by Nash's theorem suggests that the vacuum energy density contributes to the perturbations of the gravitational field.
GRUCAL, a computer program for calculating macroscopic group constants

International Nuclear Information System (INIS)

Woll, D.

1975-06-01

Nuclear reactor calculations require material- and composition-dependent, energy averaged nuclear data to describe the interaction of neutrons with individual isotopes in material compositions of reactor zones. The code GRUCAL calculates these macroscopic group constants for given compositions from the material-dependent data of the group constant library GRUBA. The instructions for calculating group constants are not fixed in the program, but will be read at the actual execution time from a separate instruction file. This allows to accomodate GRUCAL to various problems or different group constant concepts. (orig.) [de
Multiple linear regression to estimate time-frequency electrophysiological responses in single trials.

Science.gov (United States)

Hu, L; Zhang, Z G; Mouraux, A; Iannetti, G D

2015-05-01

Transient sensory, motor or cognitive event elicit not only phase-locked event-related potentials (ERPs) in the ongoing electroencephalogram (EEG), but also induce non-phase-locked modulations of ongoing EEG oscillations. These modulations can be detected when single-trial waveforms are analysed in the time-frequency domain, and consist in stimulus-induced decreases (event-related desynchronization, ERD) or increases (event-related synchronization, ERS) of synchrony in the activity of the underlying neuronal populations. ERD and ERS reflect changes in the parameters that control oscillations in neuronal networks and, depending on the frequency at which they occur, represent neuronal mechanisms involved in cortical activation, inhibition and binding. ERD and ERS are commonly estimated by averaging the time-frequency decomposition of single trials. However, their trial-to-trial variability that can reflect physiologically-important information is lost by across-trial averaging. Here, we aim to (1) develop novel approaches to explore single-trial parameters (including latency, frequency and magnitude) of ERP/ERD/ERS; (2) disclose the relationship between estimated single-trial parameters and other experimental factors (e.g., perceived intensity). We found that (1) stimulus-elicited ERP/ERD/ERS can be correctly separated using principal component analysis (PCA) decomposition with Varimax rotation on the single-trial time-frequency distributions; (2) time-frequency multiple linear regression with dispersion term (TF-MLRd) enhances the signal-to-noise ratio of ERP/ERD/ERS in single trials, and provides an unbiased estimation of their latency, frequency, and magnitude at single-trial level; (3) these estimates can be meaningfully correlated with each other and with other experimental factors at single-trial level (e.g., perceived stimulus intensity and ERP magnitude). The methods described in this article allow exploring fully non-phase-locked stimulus-induced cortical
Multiuser underwater acoustic communication using single-element virtual time reversal mirror

Institute of Scientific and Technical Information of China (English)

YIN JingWei; WANG YiLin; WANG Lei; HUI JunYing

2009-01-01

Pattern time delay shift coding (PDS) scheme is introduced and combined with spread spectrum tech-nique called SS-PDS for short which is power-saving and competent for long-range underwater acous-tic networks.Single-element virtual time reversal mirror (VTRM) is presented in this paper and validated by the lake trial results.Employing single-element VTRM in multiuser communication system based on SS-PDS can separate different users' information simultaneously at master node as indicated in the simulation results.
Classically exact surface diffusion constants at arbitrary temperature

International Nuclear Information System (INIS)

Voter, A.F.; Cohen, J.M.

1989-01-01

An expression is presented for computing the classical diffusion constant of a point defect (e.g., an adatom) in an infinite lattice of binding sites at arbitrary temperature. The transition state theory diffusion constant is simply multiplied by a dynamical correction factor that is computed from short-time classical trajectories initiated at the site boundaries. The time scale limitations of direct molecular dynamics are thus avoided in the low- and middle-temperature regimes. The expression results from taking the time derivative of the particle mean-square displacement in the lattice-discretized coordinate system. Applications are presented for surface diffusion on fcc(100) and fcc(111) Lennard-Jones crystal faces
Investigation of optical and magneto-optical constants and their surface-oxide-layer effects of single-crystalline GdCo2

International Nuclear Information System (INIS)

Lee, S.J.; Kim, K.J.; Canfield, P.C.; Lynch, D.W.

2000-01-01

We investigated the optical and magneto-optical properties of single-crystalline GdCo 2 by spectroscopic ellipsometry (SE) and magneto-optical Kerr spectrometry (MOKS). The diagonal component of the optical conductivity tensor of the compound was obtained by SE in the 1.5-5.5 eV region and the off-diagonal component by using the measured magneto-optical parameters (Kerr rotation and ellipticity) by MOKS and the SE data. The measured spectra were corrected for the surface oxide layer by employing a three-phase model treating the oxide layer as nonmagnetic with constant refractive index. The magnitude of the diagonal component becomes enhanced and the optical transition structures of the off-diagonal component become more pronounced by the oxide correction. The overall optical and magneto-optical data are discussed in terms of the calculated spin-polarized band structure and optical absorption of the compound and the effect of the surface oxide layer
Planck intermediate results. XXIV. Constraints on variation of fundamental constants

CERN Document Server

Ade, P A R; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Battaner, E.; Benabed, K.; Benoit-Levy, A.; Bernard, J.P.; Bersanelli, M.; Bielewicz, P.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Burigana, C.; Butler, R.C.; Calabrese, E.; Chamballu, A.; Chiang, H.C.; Christensen, P.R.; Clements, D.L.; Colombo, L.P.L.; Couchot, F.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; Davis, R.J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Diego, J.M.; Dole, H.; Dore, O.; Dupac, X.; Ensslin, T.A.; Eriksen, H.K.; Fabre, O.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Gonzalez-Nuevo, J.; Gorski, K.M.; Gregorio, A.; Gruppuso, A.; Hansen, F.K.; Hanson, D.; Harrison, D.L.; Henrot-Versille, S.; Hernandez-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huffenberger, K.M.; Jaffe, A.H.; Jones, W.C.; Keihanen, E.; Keskitalo, R.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lamarre, J.M.; Lasenby, A.; Lawrence, C.R.; Leonardi, R.; Lesgourgues, J.; Liguori, M.; Lilje, P.B.; Linden-Vornle, M.; Lopez-Caniego, M.; Lubin, P.M.; Macias-Perez, J.F.; Mandolesi, N.; Maris, M.; Martin, P.G.; Martinez-Gonzalez, E.; Masi, S.; Matarrese, S.; Mazzotta, P.; Meinhold, P.R.; Melchiorri, A.; Mendes, L.; Menegoni, E.; Mennella, A.; Migliaccio, M.; Miville-Deschenes, M.A.; Moneti, A.; Montier, L.; Morgante, G.; Moss, A.; Munshi, D.; Murphy, J.A.; Naselsky, P.; Nati, F.; Natoli, P.; Norgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C.A.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Pratt, G.W.; Prunet, S.; Rachen, J.P.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Ristorcelli, I.; Rocha, G.; Roudier, G.; Rusholme, B.; Sandri, M.; Savini, G.; Scott, D.; Spencer, L.D.; Stolyarov, V.; Sudiwala, R.; Sutton, D.; Suur-Uski, A.S.; Sygnet, J.F.; Tauber, J.A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Uzan, J.P.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L.A.; Yvon, D.; Zacchei, A.; Zonca, A.

2015-01-01

Any variation of the fundamental physical constants, and more particularly of the fine structure constant, $\\alpha$, or of the mass of the electron, $m_e$, would affect the recombination history of the Universe and cause an imprint on the cosmic microwave background angular power spectra. We show that the Planck data allow one to improve the constraint on the time variation of the fine structure constant at redshift $z\\sim 10^3$ by about a factor of 5 compared to WMAP data, as well as to break the degeneracy with the Hubble constant, $H_0$. In addition to $\\alpha$, we can set a constraint on the variation of the mass of the electron, $m_{\\rm e}$, and on the simultaneous variation of the two constants. We examine in detail the degeneracies between fundamental constants and the cosmological parameters, in order to compare the limits obtained from Planck and WMAP and to determine the constraining power gained by including other cosmological probes. We conclude that independent time variations of the fine structu...
Vestibular Compensation in Unilateral Patients Often Causes Both Gain and Time Constant Asymmetries in The VOR

Directory of Open Access Journals (Sweden)

Mina eRanjbaran

2016-03-01

Full Text Available The vestibulo-ocular reflex (VOR is essential in our daily life to stabilize retinal images during head movements. Balanced vestibular functionality secures optimal reflex performance which can be distorted in case of peripheral vestibular lesions. Luckily, vestibular compensation in different neuronal sites restores VOR function to some extent over time. Studying vestibular compensation gives insight into the possible mechanisms for plasticity in the brain.In this work, novel experimental analysis tools are employed to reevaluate the VOR characteristics following unilateral vestibular lesions and compensation. Our results suggest that following vestibular lesions, asymmetric performance of the VOR is not only limited to its gain. Vestibular compensation also causes asymmetric dynamics, i.e. different time constants for the VOR during leftward or rightward passive head rotation. Potential mechanisms for these experimental observations are provided using simulation studies.
Time-resolved energy transfer from single chloride-terminated nanocrystals to graphene

International Nuclear Information System (INIS)

Ajayi, O. A.; Wong, C. W.; Anderson, N. C.; Wolcott, A.; Owen, J. S.; Cotlet, M.; Petrone, N.; Hone, J.; Gu, T.; Gesuele, F.

2014-01-01

We examine the time-resolved resonance energy transfer of excitons from single n-butyl amine-bound, chloride-terminated nanocrystals to two-dimensional graphene through time-correlated single photon counting. The radiative biexponential lifetime kinetics and blinking statistics of the individual surface-modified nanocrystal elucidate the non-radiative decay channels. Blinking modification as well as a 4× reduction in spontaneous emission were observed with the short chloride and n-butylamine ligands, probing the energy transfer pathways for the development of graphene-nanocrystal nanophotonic devices
Time-resolved energy transfer from single chloride-terminated nanocrystals to graphene

Energy Technology Data Exchange (ETDEWEB)

Ajayi, O. A., E-mail: oaa2114@columbia.edu, E-mail: cww2104@columbia.edu; Wong, C. W., E-mail: oaa2114@columbia.edu, E-mail: cww2104@columbia.edu [Optical Nanostructures Laboratory, Center for Integrated Science and Engineering, Solid-State Science and Engineering, Columbia University, New York, New York 10027 (United States); Department of Mechanical Engineering, Columbia University, New York, New York 10027 (United States); Anderson, N. C.; Wolcott, A.; Owen, J. S. [Department of Chemistry, Columbia University, New York, New York 10027 (United States); Cotlet, M. [Brookhaven National Laboratory, Upton, New York, New York 11973 (United States); Petrone, N.; Hone, J. [Department of Mechanical Engineering, Columbia University, New York, New York 10027 (United States); Gu, T.; Gesuele, F. [Optical Nanostructures Laboratory, Center for Integrated Science and Engineering, Solid-State Science and Engineering, Columbia University, New York, New York 10027 (United States)

2014-04-28

We examine the time-resolved resonance energy transfer of excitons from single n-butyl amine-bound, chloride-terminated nanocrystals to two-dimensional graphene through time-correlated single photon counting. The radiative biexponential lifetime kinetics and blinking statistics of the individual surface-modified nanocrystal elucidate the non-radiative decay channels. Blinking modification as well as a 4× reduction in spontaneous emission were observed with the short chloride and n-butylamine ligands, probing the energy transfer pathways for the development of graphene-nanocrystal nanophotonic devices.
Single sources in the low-frequency gravitational wave sky: properties and time to detection by pulsar timing arrays

Science.gov (United States)

Kelley, Luke Zoltan; Blecha, Laura; Hernquist, Lars; Sesana, Alberto; Taylor, Stephen R.

2018-06-01

We calculate the properties, occurrence rates and detection prospects of individually resolvable `single sources' in the low-frequency gravitational wave (GW) spectrum. Our simulations use the population of galaxies and massive black hole binaries from the Illustris cosmological hydrodynamic simulations, coupled to comprehensive semi-analytic models of the binary merger process. Using mock pulsar timing arrays (PTA) with, for the first time, varying red-noise models, we calculate plausible detection prospects for GW single sources and the stochastic GW background (GWB). Contrary to previous results, we find that single sources are at least as detectable as the GW background. Using mock PTA, we find that these `foreground' sources (also `deterministic'/`continuous') are likely to be detected with ˜20 yr total observing baselines. Detection prospects, and indeed the overall properties of single sources, are only moderately sensitive to binary evolution parameters - namely eccentricity and environmental coupling, which can lead to differences of ˜5 yr in times to detection. Red noise has a stronger effect, roughly doubling the time to detection of the foreground between a white-noise only model (˜10-15 yr) and severe red noise (˜20-30 yr). The effect of red noise on the GWB is even stronger, suggesting that single source detections may be more robust. We find that typical signal-to-noise ratios for the foreground peak near f = 0.1 yr-1, and are much less sensitive to the continued addition of new pulsars to PTA.
Diffusional falsification of kinetic constants on Lineweaver-Burk plots.

Science.gov (United States)

Ghim, Y S; Chang, H N

1983-11-07

The effect of mass transfer resistances on the Lineweaver-Burk plots in immobilized enzyme systems has been investigated numerically and with analytical approximate solutions. While Hamilton, Gardner & Colton (1974) studied the effect of internal diffusion resistances in planar geometry, our study was extended to the combined effect of internal and external diffusion in cylindrical and spherical geometries as well. The variation of Lineweaver-Burk plots with respect to the geometries was minimized by modifying the Thiele modulus and the Biot number with the shape factor. Especially for a small Biot number all the three Lineweaver-Burk plots fell on a single line. As was discussed by Hamilton et al. (1974), the curvature of the line for large external diffusion resistances was small enough to be assumed linear, which was confirmed from the two approximate solutions for large and small substrate concentrations. Two methods for obtaining intrinsic kinetic constants were proposed: First, we obtained both maximum reaction rate and Michaelis constant by fitting experimental data to a straight line where external diffusion resistance was relatively large, and second, we obtained Michaelis constant from apparent Michaelis constant from the figure in case we knew maximum reaction rate a priori.
Scaling behaviour of leptonic decay constants for heavy quarkonia and heavy mesons

International Nuclear Information System (INIS)

Kiselev, V.V.

1994-01-01

In the framework of QCD sum rules one uses a scheme, allowing one to apply the conditions of both nonrelativistic heavy quark motion inside mesons and the heavy quark flavour independence of nonsplitting nS-state density. In the leading order an analitic expression is derived for leptonic constants of both heavy quarkonia and heavy mesons with a single heavy quark. The expression allows one explicitly to determine scaling properties of the constants. 24 refs., 2 tabs
Dielectric constant of atomic fluids with variable polarizability

OpenAIRE

Alder, B. J.; Beers, J. C.; Strauss, H. L.; Weis, J. J.

1980-01-01

The Clausius-Mossotti function for the dielectric constant is expanded in terms of single atom and pair polarizabilities, leading to contributions that depend on both the trace and the anisotropy of the pair-polarizability tensor. The short-range contribution of the anisotropic part to the pair polarizabilities has previously been obtained empirically from light scattering experiments, whereas the trace contribution is now empirically determined by comparison to dielectric experiments. For he...

An elevated neutrophil-lymphocyte ratio is associated with adverse outcomes following single time-point paracetamol (acetaminophen) overdose: a time-course analysis.

Science.gov (United States)

Craig, Darren G; Kitto, Laura; Zafar, Sara; Reid, Thomas W D J; Martin, Kirsty G; Davidson, Janice S; Hayes, Peter C; Simpson, Kenneth J

2014-09-01

The innate immune system is profoundly dysregulated in paracetamol (acetaminophen)-induced liver injury. The neutrophil-lymphocyte ratio (NLR) is a simple bedside index with prognostic value in a number of inflammatory conditions. To evaluate the prognostic accuracy of the NLR in patients with significant liver injury following single time-point and staggered paracetamol overdoses. Time-course analysis of 100 single time-point and 50 staggered paracetamol overdoses admitted to a tertiary liver centre. Timed laboratory samples were correlated with time elapsed after overdose or admission, respectively, and the NLR was calculated. A total of 49/100 single time-point patients developed hepatic encephalopathy (HE). Median NLRs were higher at both 72 (P=0.0047) and 96 h after overdose (P=0.0041) in single time-point patients who died or were transplanted. Maximum NLR values by 96 h were associated with increasing HE grade (P=0.0005). An NLR of more than 16.7 during the first 96 h following overdose was independently associated with the development of HE [odds ratio 5.65 (95% confidence interval 1.67-19.13), P=0.005]. Maximum NLR values by 96 h were strongly associated with the requirement for intracranial pressure monitoring (Pparacetamol overdoses. Future studies should assess the value of incorporating the NLR into existing prognostic and triage indices of single time-point paracetamol overdose.
Simultaneous measurement of the maximum oscillation amplitude and the transient decay time constant of the QCM reveals stiffness changes of the adlayer.

Science.gov (United States)

Marxer, C Galli; Coen, M Collaud; Bissig, H; Greber, U F; Schlapbach, L

2003-10-01

Interpretation of adsorption kinetics measured with a quartz crystal microbalance (QCM) can be difficult for adlayers undergoing modification of their mechanical properties. We have studied the behavior of the oscillation amplitude, A(0), and the decay time constant, tau, of quartz during adsorption of proteins and cells, by use of a home-made QCM. We are able to measure simultaneously the frequency, f, the dissipation factor, D, the maximum amplitude, A(0), and the transient decay time constant, tau, every 300 ms in liquid, gaseous, or vacuum environments. This analysis enables adsorption and modification of liquid/mass properties to be distinguished. Moreover the surface coverage and the stiffness of the adlayer can be estimated. These improvements promise to increase the appeal of QCM methodology for any applications measuring intimate contact of a dynamic material with a solid surface.
A fluctuation method to calculate the third order elastic constants in crystalline solids

Energy Technology Data Exchange (ETDEWEB)

Chen, Zimu [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Qu, Jianmin, E-mail: j-qu@northwestern.edu [Department of Civil and Environmental Engineering, Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208 (United States)

2015-05-28

This paper derives exact expressions of the isothermal third order elastic constants (TOE) in crystalline solids in terms of the kinetic and potential energies of the system. These expressions reveal that the TOE constants consist of a Born component and a relaxation component. The Born component is simply the third derivative of the system's potential energy with respect to the deformation, while the relaxation component is related to the non-uniform rearrangements of the atoms when the system is subject to a macroscopic deformation. Further, based on the general expressions derived here, a direct (fluctuation) method of computing the isothermal TOE constants is developed. Numerical examples of using this fluctuation method are given to compute the TOE constants of single crystal iron.
Stabilized power constant alimentation

International Nuclear Information System (INIS)

Roussel, L.

1968-06-01

The study and realization of a stabilized power alimentation variable from 5 to 100 watts are described. In order to realize a constant power drift of Lithium compensated diodes, we have searched a 1 per cent precision of regulation and a response time minus than 1 sec. Recent components like Hall multiplicator and integrated amplifiers give this possibility and it is easy to use permutable circuits. (author) [fr
Memory effect in silicon time-gated single-photon avalanche diodes

International Nuclear Information System (INIS)

Dalla Mora, A.; Contini, D.; Di Sieno, L.; Tosi, A.; Boso, G.; Villa, F.; Pifferi, A.

2015-01-01

We present a comprehensive characterization of the memory effect arising in thin-junction silicon Single-Photon Avalanche Diodes (SPADs) when exposed to strong illumination. This partially unknown afterpulsing-like noise represents the main limiting factor when time-gated acquisitions are exploited to increase the measurement dynamic range of very fast (picosecond scale) and faint (single-photon) optical signals following a strong stray one. We report the dependences of this unwelcome signal-related noise on photon wavelength, detector temperature, and biasing conditions. Our results suggest that this so-called “memory effect” is generated in the deep regions of the detector, well below the depleted region, and its contribution on detector response is visible only when time-gated SPADs are exploited to reject a strong burst of photons
Memory effect in silicon time-gated single-photon avalanche diodes

Energy Technology Data Exchange (ETDEWEB)

Dalla Mora, A.; Contini, D., E-mail: davide.contini@polimi.it; Di Sieno, L. [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Tosi, A.; Boso, G.; Villa, F. [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Pifferi, A. [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); CNR, Istituto di Fotonica e Nanotecnologie, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy)

2015-03-21

We present a comprehensive characterization of the memory effect arising in thin-junction silicon Single-Photon Avalanche Diodes (SPADs) when exposed to strong illumination. This partially unknown afterpulsing-like noise represents the main limiting factor when time-gated acquisitions are exploited to increase the measurement dynamic range of very fast (picosecond scale) and faint (single-photon) optical signals following a strong stray one. We report the dependences of this unwelcome signal-related noise on photon wavelength, detector temperature, and biasing conditions. Our results suggest that this so-called “memory effect” is generated in the deep regions of the detector, well below the depleted region, and its contribution on detector response is visible only when time-gated SPADs are exploited to reject a strong burst of photons.
Time-resolved single-photon detection module based on silicon photomultiplier: A novel building block for time-correlated measurement systems

Energy Technology Data Exchange (ETDEWEB)

Martinenghi, E., E-mail: edoardo.martinenghi@polimi.it; Di Sieno, L.; Contini, D.; Dalla Mora, A. [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Sanzaro, M. [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Pifferi, A. [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

2016-07-15

We present the design and preliminary characterization of the first detection module based on Silicon Photomultiplier (SiPM) tailored for single-photon timing applications. The aim of this work is to demonstrate, thanks to the design of a suitable module, the possibility to easily exploit SiPM in many applications as an interesting detector featuring large active area, similarly to photomultipliers tubes, but keeping the advantages of solid state detectors (high quantum efficiency, low cost, compactness, robustness, low bias voltage, and insensitiveness to magnetic field). The module integrates a cooled SiPM with a total photosensitive area of 1 mm{sup 2} together with the suitable avalanche signal read-out circuit, the signal conditioning, the biasing electronics, and a Peltier cooler driver for thermal stabilization. It is able to extract the single-photon timing information with resolution better than 100 ps full-width at half maximum. We verified the effective stabilization in response to external thermal perturbations, thus proving the complete insensitivity of the module to environment temperature variations, which represents a fundamental parameter to profitably use the instrument for real-field applications. We also characterized the single-photon timing resolution, the background noise due to both primary dark count generation and afterpulsing, the single-photon detection efficiency, and the instrument response function shape. The proposed module can become a reliable and cost-effective building block for time-correlated single-photon counting instruments in applications requiring high collection capability of isotropic light and detection efficiency (e.g., fluorescence decay measurements or time-domain diffuse optics systems).
Time-resolved single-photon detection module based on silicon photomultiplier: A novel building block for time-correlated measurement systems

International Nuclear Information System (INIS)

Martinenghi, E.; Di Sieno, L.; Contini, D.; Dalla Mora, A.; Sanzaro, M.; Pifferi, A.

2016-01-01

We present the design and preliminary characterization of the first detection module based on Silicon Photomultiplier (SiPM) tailored for single-photon timing applications. The aim of this work is to demonstrate, thanks to the design of a suitable module, the possibility to easily exploit SiPM in many applications as an interesting detector featuring large active area, similarly to photomultipliers tubes, but keeping the advantages of solid state detectors (high quantum efficiency, low cost, compactness, robustness, low bias voltage, and insensitiveness to magnetic field). The module integrates a cooled SiPM with a total photosensitive area of 1 mm"2 together with the suitable avalanche signal read-out circuit, the signal conditioning, the biasing electronics, and a Peltier cooler driver for thermal stabilization. It is able to extract the single-photon timing information with resolution better than 100 ps full-width at half maximum. We verified the effective stabilization in response to external thermal perturbations, thus proving the complete insensitivity of the module to environment temperature variations, which represents a fundamental parameter to profitably use the instrument for real-field applications. We also characterized the single-photon timing resolution, the background noise due to both primary dark count generation and afterpulsing, the single-photon detection efficiency, and the instrument response function shape. The proposed module can become a reliable and cost-effective building block for time-correlated single-photon counting instruments in applications requiring high collection capability of isotropic light and detection efficiency (e.g., fluorescence decay measurements or time-domain diffuse optics systems).
The effect of solvent relaxation time constants on free energy gap law for ultrafast charge recombination following photoinduced charge separation.

Science.gov (United States)

Mikhailova, Valentina A; Malykhin, Roman E; Ivanov, Anatoly I

2018-05-16

To elucidate the regularities inherent in the kinetics of ultrafast charge recombination following photoinduced charge separation in donor-acceptor dyads in solutions, the simulations of the kinetics have been performed within the stochastic multichannel point-transition model. Increasing the solvent relaxation time scales has been shown to strongly vary the dependence of the charge recombination rate constant on the free energy gap. In slow relaxing solvents the non-equilibrium charge recombination occurring in parallel with solvent relaxation is very effective so that the charge recombination terminates at the non-equilibrium stage. This results in a crucial difference between the free energy gap laws for the ultrafast charge recombination and the thermal charge transfer. For the thermal reactions the well-known Marcus bell-shaped dependence of the rate constant on the free energy gap is realized while for the ultrafast charge recombination only a descending branch is predicted in the whole area of the free energy gap exceeding 0.2 eV. From the available experimental data on the population kinetics of the second and first excited states for a series of Zn-porphyrin-imide dyads in toluene and tetrahydrofuran solutions, an effective rate constant of the charge recombination into the first excited state has been calculated. The obtained rate constant being very high is nearly invariable in the area of the charge recombination free energy gap from 0.2 to 0.6 eV that supports the theoretical prediction.
Description of an identification method of thermocouple time constant based on application of recursive numerical filtering to temperature fluctuation

International Nuclear Information System (INIS)

Bernardin, B.; Le Guillou, G.; Parcy, JP.

1981-04-01

Usual spectral methods, based on temperature fluctuation analysis, aiming at thermocouple time constant identification are using an equipment too much sophisticated for on-line application. It is shown that numerical filtering is optimal for this application, the equipment is simpler than for spectral methods and less samples of signals are needed for the same accuracy. The method is described and a parametric study was performed using a temperature noise simulator [fr
Improving the counting efficiency in time-correlated single photon counting experiments by dead-time optimization

Energy Technology Data Exchange (ETDEWEB)

Peronio, P.; Acconcia, G.; Rech, I.; Ghioni, M. [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

2015-11-15

Time-Correlated Single Photon Counting (TCSPC) has been long recognized as the most sensitive method for fluorescence lifetime measurements, but often requiring “long” data acquisition times. This drawback is related to the limited counting capability of the TCSPC technique, due to pile-up and counting loss effects. In recent years, multi-module TCSPC systems have been introduced to overcome this issue. Splitting the light into several detectors connected to independent TCSPC modules proportionally increases the counting capability. Of course, multi-module operation also increases the system cost and can cause space and power supply problems. In this paper, we propose an alternative approach based on a new detector and processing electronics designed to reduce the overall system dead time, thus enabling efficient photon collection at high excitation rate. We present a fast active quenching circuit for single-photon avalanche diodes which features a minimum dead time of 12.4 ns. We also introduce a new Time-to-Amplitude Converter (TAC) able to attain extra-short dead time thanks to the combination of a scalable array of monolithically integrated TACs and a sequential router. The fast TAC (F-TAC) makes it possible to operate the system towards the upper limit of detector count rate capability (∼80 Mcps) with reduced pile-up losses, addressing one of the historic criticisms of TCSPC. Preliminary measurements on the F-TAC are presented and discussed.
A study of pile-up in integrated time-correlated single photon counting systems.

Science.gov (United States)

Arlt, Jochen; Tyndall, David; Rae, Bruce R; Li, David D-U; Richardson, Justin A; Henderson, Robert K

2013-10-01

Recent demonstration of highly integrated, solid-state, time-correlated single photon counting (TCSPC) systems in CMOS technology is set to provide significant increases in performance over existing bulky, expensive hardware. Arrays of single photon single photon avalanche diode (SPAD) detectors, timing channels, and signal processing can be integrated on a single silicon chip with a degree of parallelism and computational speed that is unattainable by discrete photomultiplier tube and photon counting card solutions. New multi-channel, multi-detector TCSPC sensor architectures with greatly enhanced throughput due to minimal detector transit (dead) time or timing channel dead time are now feasible. In this paper, we study the potential for future integrated, solid-state TCSPC sensors to exceed the photon pile-up limit through analytic formula and simulation. The results are validated using a 10% fill factor SPAD array and an 8-channel, 52 ps resolution time-to-digital conversion architecture with embedded lifetime estimation. It is demonstrated that pile-up insensitive acquisition is attainable at greater than 10 times the pulse repetition rate providing over 60 dB of extended dynamic range to the TCSPC technique. Our results predict future CMOS TCSPC sensors capable of live-cell transient observations in confocal scanning microscopy, improved resolution of near-infrared optical tomography systems, and fluorescence lifetime activated cell sorting.
Understanding fine structure constants and three generations

International Nuclear Information System (INIS)

Bennett, D.L.; Nielsen, H.B.

1988-02-01

We put forward a model inspired by random dynamics that relates the smallness of the gauge coupling constants to the number of generations being 'large'. The new element in the present version of our model is the appearance of a free parameter χ that is a measure of the (presumably relatively minor) importance of a term in the plaquette action proportional to the trace in the (1/6, 2, 3) representation of the Standard Model. Calling N gen the number of generations, the sets of allowed (N gen , χN gen )-pairs obtained by imposing the three measured coupling constant values of the Standard Model form three lines. In addition to finding that these lines cross at a single point (as needed for a consistent fit), the intersection occurs with surprising accuracy at the integer N gen = 3 (thereby predicting exactly three generations). It is also encouraging that the parameter χ turns out to be small and positive as expected. (orig.)
Inflation with a smooth constant-roll to constant-roll era transition

Science.gov (United States)

Odintsov, S. D.; Oikonomou, V. K.

2017-07-01

In this paper, we study canonical scalar field models, with a varying second slow-roll parameter, that allow transitions between constant-roll eras. In the models with two constant-roll eras, it is possible to avoid fine-tunings in the initial conditions of the scalar field. We mainly focus on the stability of the resulting solutions, and we also investigate if these solutions are attractors of the cosmological system. We shall calculate the resulting scalar potential and, by using a numerical approach, we examine the stability and attractor properties of the solutions. As we show, the first constant-roll era is dynamically unstable towards linear perturbations, and the cosmological system is driven by the attractor solution to the final constant-roll era. As we demonstrate, it is possible to have a nearly scale-invariant power spectrum of primordial curvature perturbations in some cases; however, this is strongly model dependent and depends on the rate of the final constant-roll era. Finally, we present, in brief, the essential features of a model that allows oscillations between constant-roll eras.
Elastic constants of diamond from molecular dynamics simulations

International Nuclear Information System (INIS)

Gao Guangtu; Van Workum, Kevin; Schall, J David; Harrison, Judith A

2006-01-01

The elastic constants of diamond between 100 and 1100 K have been calculated for the first time using molecular dynamics and the second-generation, reactive empirical bond-order potential (REBO). This version of the REBO potential was used because it was redesigned to be able to model the elastic properties of diamond and graphite at 0 K while maintaining its original capabilities. The independent elastic constants of diamond, C 11 , C 12 , and C 44 , and the bulk modulus were all calculated as a function of temperature, and the results from the three different methods are in excellent agreement. By extrapolating the elastic constant data to 0 K, it is clear that the values obtained here agree with the previously calculated 0 K elastic constants. Because the second-generation REBO potential was fit to obtain better solid-state force constants for diamond and graphite, the agreement with the 0 K elastic constants is not surprising. In addition, the functional form of the second-generation REBO potential is able to qualitatively model the functional dependence of the elastic constants and bulk modulus of diamond at non-zero temperatures. In contrast, reactive potentials based on other functional forms do not reproduce the correct temperature dependence of the elastic constants. The second-generation REBO potential also correctly predicts that diamond has a negative Cauchy pressure in the temperature range examined
On the gravitational constant change

International Nuclear Information System (INIS)

Milyukov, V.K.

1986-01-01

The nowadays viewpoint on the problem of G gravitational constant invariability is presented in brief. The methods and results of checking of the G dependence on the nature of substance (checking of the equivalence principle), G dependepce on distance (checking of Newton gravity law) and time (cosmological experiments) are presented. It is pointed out that all performed experiments don't give any reasons to have doubts in G constancy in space and time and G independence on the nature of the substance
Note: Time-gated 3D single quantum dot tracking with simultaneous spinning disk imaging

International Nuclear Information System (INIS)

DeVore, M. S.; Stich, D. G.; Keller, A. M.; Phipps, M. E.; Hollingsworth, J. A.; Goodwin, P. M.; Werner, J. H.; Cleyrat, C.; Lidke, D. S.; Wilson, B. S.

2015-01-01

We describe recent upgrades to a 3D tracking microscope to include simultaneous Nipkow spinning disk imaging and time-gated single-particle tracking (SPT). Simultaneous 3D molecular tracking and spinning disk imaging enable the visualization of cellular structures and proteins around a given fluorescently labeled target molecule. The addition of photon time-gating to the SPT hardware improves signal to noise by discriminating against Raman scattering and short-lived fluorescence. In contrast to camera-based SPT, single-photon arrival times are recorded, enabling time-resolved spectroscopy (e.g., measurement of fluorescence lifetimes and photon correlations) to be performed during single molecule/particle tracking experiments
Note: Time-gated 3D single quantum dot tracking with simultaneous spinning disk imaging

Energy Technology Data Exchange (ETDEWEB)

DeVore, M. S.; Stich, D. G.; Keller, A. M.; Phipps, M. E.; Hollingsworth, J. A.; Goodwin, P. M.; Werner, J. H., E-mail: jwerner@lanl.gov [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Mail Stop G755, Los Alamos, New Mexico 87545 (United States); Cleyrat, C.; Lidke, D. S.; Wilson, B. S. [Department of Pathology and Cancer Research and Treatment Center, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

2015-12-15

We describe recent upgrades to a 3D tracking microscope to include simultaneous Nipkow spinning disk imaging and time-gated single-particle tracking (SPT). Simultaneous 3D molecular tracking and spinning disk imaging enable the visualization of cellular structures and proteins around a given fluorescently labeled target molecule. The addition of photon time-gating to the SPT hardware improves signal to noise by discriminating against Raman scattering and short-lived fluorescence. In contrast to camera-based SPT, single-photon arrival times are recorded, enabling time-resolved spectroscopy (e.g., measurement of fluorescence lifetimes and photon correlations) to be performed during single molecule/particle tracking experiments.
Time-domain single-source integral equations for analyzing scattering from homogeneous penetrable objects

KAUST Repository

Valdés, Felipe

2013-03-01

Single-source time-domain electric-and magnetic-field integral equations for analyzing scattering from homogeneous penetrable objects are presented. Their temporal discretization is effected by using shifted piecewise polynomial temporal basis functions and a collocation testing procedure, thus allowing for a marching-on-in-time (MOT) solution scheme. Unlike dual-source formulations, single-source equations involve space-time domain operator products, for which spatial discretization techniques developed for standalone operators do not apply. Here, the spatial discretization of the single-source time-domain integral equations is achieved by using the high-order divergence-conforming basis functions developed by Graglia alongside the high-order divergence-and quasi curl-conforming (DQCC) basis functions of Valdés The combination of these two sets allows for a well-conditioned mapping from div-to curl-conforming function spaces that fully respects the space-mapping properties of the space-time operators involved. Numerical results corroborate the fact that the proposed procedure guarantees accuracy and stability of the MOT scheme. © 2012 IEEE.
Estimating reaction rate constants: comparison between traditional curve fitting and curve resolution

NARCIS (Netherlands)

Bijlsma, S.; Boelens, H. F. M.; Hoefsloot, H. C. J.; Smilde, A. K.

2000-01-01

A traditional curve fitting (TCF) algorithm is compared with a classical curve resolution (CCR) approach for estimating reaction rate constants from spectral data obtained in time of a chemical reaction. In the TCF algorithm, reaction rate constants an estimated from the absorbance versus time data

From the Rydberg constant to the fundamental constants metrology; De la constante de Rydberg a la metrologie des constantes fondamentales

Energy Technology Data Exchange (ETDEWEB)

Nez, F

2005-06-15

This document reviews the theoretical and experimental achievements of the author since the beginning of his scientific career. This document is dedicated to the spectroscopy of hydrogen, deuterium and helium atoms. The first part is divided into 6 sub-sections: 1) the principles of hydrogen spectroscopy, 2) the measurement of the 2S-nS/nD transitions, 3) other optical frequency measurements, 4) our contribution to the determination of the Rydberg constant, 5) our current experiment on the 1S-3S transition, 6) the spectroscopy of the muonic hydrogen. Our experiments have improved the accuracy of the Rydberg Constant by a factor 25 in 15 years and we have achieved the first absolute optical frequency measurement of a transition in hydrogen. The second part is dedicated to the measurement of the fine structure constant and the last part deals with helium spectroscopy and the search for optical references in the near infrared range. (A.C.)
Energy scavenging based on a single-crystal PMN-PT nanobelt

Science.gov (United States)

Wu, Fan; Cai, Wei; Yeh, Yao-Wen; Xu, Shiyou; Yao, Nan

2016-03-01

Self-powered nanodevices scavenging mechanical energy require piezoelectric nanostructures with high piezoelectric coefficients. Here we report the fabrication of a single-crystal (1 - x)Pb(Mg1/3Nb2/3)O3 - xPbTiO3 (PMN-PT) nanobelt with a superior piezoelectric constant (d33 = ~550 pm/V), which is approximately ~150%, 430%, and 2100% of the largest reported values for previous PMN-PT, PZT and ZnO nanostructures, respectively. The high d33 of the single-crystalline PMN-PT nanobelt results from the precise orientation control during its fabrication. As a demonstration of its application in energy scavenging, a piezoelectric nanogenerator (PNG) is built on the single PMN-PT nanobelt, generating a maximum output voltage of ~1.2 V. This value is ~4 times higher than that of a single-CdTe PNG, ~13 times higher than that of a single-ZnSnO3 PNG, and ~26 times higher than that of a single-ZnO PNG. The profoundly increased output voltage of a lateral PNG built on a single PMN-PT nanobelt demonstrates the potential application of PMN-PT nanostructures in energy harvesting, thus enriching the material choices for PNGs.
Revealing time bunching effect in single-molecule enzyme conformational dynamics.

Science.gov (United States)

Lu, H Peter

2011-04-21

In this perspective, we focus our discussion on how the single-molecule spectroscopy and statistical analysis are able to reveal enzyme hidden properties, taking the study of T4 lysozyme as an example. Protein conformational fluctuations and dynamics play a crucial role in biomolecular functions, such as in enzymatic reactions. Single-molecule spectroscopy is a powerful approach to analyze protein conformational dynamics under physiological conditions, providing dynamic perspectives on a molecular-level understanding of protein structure-function mechanisms. Using single-molecule fluorescence spectroscopy, we have probed T4 lysozyme conformational motions under the hydrolysis reaction of a polysaccharide of E. coli B cell walls by monitoring the fluorescence resonant energy transfer (FRET) between a donor-acceptor probe pair tethered to T4 lysozyme domains involving open-close hinge-bending motions. Based on the single-molecule spectroscopic results, molecular dynamics simulation, a random walk model analysis, and a novel 2D statistical correlation analysis, we have revealed a time bunching effect in protein conformational motion dynamics that is critical to enzymatic functions. Bunching effect implies that conformational motion times tend to bunch in a finite and narrow time window. We show that convoluted multiple Poisson rate processes give rise to the bunching effect in the enzymatic reaction dynamics. Evidently, the bunching effect is likely common in protein conformational dynamics involving in conformation-gated protein functions. In this perspective, we will also discuss a new approach of 2D regional correlation analysis capable of analyzing fluctuation dynamics of complex multiple correlated and anti-correlated fluctuations under a non-correlated noise background. Using this new method, we are able to map out any defined segments along the fluctuation trajectories and determine whether they are correlated, anti-correlated, or non-correlated; after which, a
Field and polarity dependence of time-to-resistance increase in Fe-O films studied by constant voltage stress method

International Nuclear Information System (INIS)

Eriguchi, Koji; Ohta, Hiroaki; Ono, Kouichi; Wei Zhiqiang; Takagi, Takeshi

2009-01-01

Constant voltage stress (CVS) was applied to Fe-O films prepared by a sputtering process to investigate a stress-induced resistance increase leading to a fundamental mechanism for switching behaviors. Under the CVS, an abrupt resistance increase was found for both stress polarities. A conduction mechanism after the resistance increase exhibited non-Ohmic transport. The time-to-resistance increase (t r ) under the CVS was revealed to strongly depend on stress voltage as well as the polarity. From a polarity-dependent resistance increase determined by a time-zero measurement, the voltage and polarity-dependent t r were discussed on the basis of field- and structure-enhanced thermochemical reaction mechanisms
Simulated annealing with constant thermodynamic speed

International Nuclear Information System (INIS)

Salamon, P.; Ruppeiner, G.; Liao, L.; Pedersen, J.

1987-01-01

Arguments are presented to the effect that the optimal annealing schedule for simulated annealing proceeds with constant thermodynamic speed, i.e., with dT/dt = -(v T)/(ε-√C), where T is the temperature, ε- is the relaxation time, C ist the heat capacity, t is the time, and v is the thermodynamic speed. Experimental results consistent with this conjecture are presented from simulated annealing on graph partitioning problems. (orig.)
Light deflection, lensing, and time delays from gravitational potentials and Fermat's principle in the presence of a cosmological constant

International Nuclear Information System (INIS)

Ishak, Mustapha

2008-01-01

The contributions of the cosmological constant to the deflection angle and the time delays are derived from the integration of the gravitational potential as well as from Fermat's principle. The findings are in agreement with recent results using exact solutions to Einstein's equations and reproduce precisely the new Λ term in the bending angle and the lens equation. The consequences on time-delay expressions are explored. While it is known that Λ contributes to the gravitational time delay, it is shown here that a new Λ term appears in the geometrical time delay as well. Although these newly derived terms are perhaps small for current observations, they do not cancel out as previously claimed. Moreover, as shown before, at galaxy cluster scale, the Λ contribution can be larger than the second-order term in the Einstein deflection angle for several cluster lens systems.
Wide-field time-correlated single photon counting (TCSPC) microscopy with time resolution below the frame exposure time

Energy Technology Data Exchange (ETDEWEB)

Hirvonen, Liisa M. [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Petrášek, Zdeněk [Max Planck Institute of Biochemistry, Department of Cellular and Molecular Biophysics, Am Klopferspitz 18, D-82152 Martinsried (Germany); Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom)

2015-07-01

Fast frame rate CMOS cameras in combination with photon counting intensifiers can be used for fluorescence imaging with single photon sensitivity at kHz frame rates. We show here how the phosphor decay of the image intensifier can be exploited for accurate timing of photon arrival well below the camera exposure time. This is achieved by taking ratios of the intensity of the photon events in two subsequent frames, and effectively allows wide-field TCSPC. This technique was used for measuring decays of ruthenium compound Ru(dpp) with lifetimes as low as 1 μs with 18.5 μs frame exposure time, including in living HeLa cells, using around 0.1 μW excitation power. We speculate that by using an image intensifier with a faster phosphor decay to match a higher camera frame rate, photon arrival time measurements on the nanosecond time scale could well be possible.
Approximation for the Finite-Time Ruin Probability of a General Risk Model with Constant Interest Rate and Extended Negatively Dependent Heavy-Tailed Claims

Directory of Open Access Journals (Sweden)

Yang Yang

2011-01-01

Full Text Available We propose a general continuous-time risk model with a constant interest rate. In this model, claims arrive according to an arbitrary counting process, while their sizes have dominantly varying tails and fulfill an extended negative dependence structure. We obtain an asymptotic formula for the finite-time ruin probability, which extends a corresponding result of Wang (2008.
Pulsed single-photon spectrometer by frequency-to-time mapping using chirped fiber Bragg gratings.

Science.gov (United States)

Davis, Alex O C; Saulnier, Paul M; Karpiński, Michał; Smith, Brian J

2017-05-29

A fiber-integrated spectrometer for single-photon pulses outside the telecommunications wavelength range based upon frequency-to-time mapping, implemented by chromatic group delay dispersion (GDD), and precise temporally-resolved single-photon counting, is presented. A chirped fiber Bragg grating provides low-loss GDD, mapping the frequency distribution of an input pulse onto the temporal envelope of the output pulse. Time-resolved detection with fast single-photon-counting modules enables monitoring of a wavelength range from 825 nm to 835 nm with nearly uniform efficiency at 55 pm resolution (24 GHz at 830 nm). To demonstrate the versatility of this technique, spectral interference of heralded single photons and the joint spectral intensity distribution of a photon-pair source are measured. This approach to single-photon-level spectral measurements provides a route to realize applications of time-frequency quantum optics at visible and near-infrared wavelengths, where multiple spectral channels must be simultaneously monitored.
Increasing the collection efficiency of time-correlated single-photon counting with single-photon avalanche diodes using immersion lenses.

Science.gov (United States)

Pichette, Charles; Giudice, Andrea; Thibault, Simon; Bérubé-Lauzière, Yves

2016-11-20

Single-photon avalanche diodes (SPADs) achieving high timing resolution (≈20-50 ps) developed for time-correlated single-photon counting (TCSPC) generally have very small photosensitive areas (25-100 μm in diameter). This limits the achievable photon counting rate and signal-to-noise ratio and may lead to long counting times. This is detrimental in applications requiring several measurements, such as fluorescence lifetime imaging (FLIM) microscopy, which requires scanning, and time-domain diffuse optical tomography (TD-DOT). We show in this work that the use of an immersion lens directly affixed onto the photosensitive area of the SPAD helps alleviate this problem by allowing more light to be concentrated onto the detector. Following careful optical design and simulations, our experimental results show that it is actually possible to achieve the predicted theoretical increase in the photon counting rate (we achieve a factor of ≈4 here). This work is of high relevance in high timing resolution TCSPC with small photosensitive area detectors and should find widespread interest in FLIM and TD-DOT with SPADs.
Preliminary Planck constant measurements via UME oscillating magnet Kibble balance

Science.gov (United States)

Ahmedov, H.; Babayiğit Aşkın, N.; Korutlu, B.; Orhan, R.

2018-06-01

The UME Kibble balance project was initiated in the second half of 2014. During this period we have studied the theoretical aspects of Kibble balances, in which an oscillating magnet generates AC Faraday’s voltage in a stationary coil, and constructed a trial version to implement this idea. The remarkable feature of this approach is that it can establish the link between the Planck constant and a macroscopic mass by one single experiment in the most natural way. Weak dependences on variations of environmental and experimental conditions, small size, and other useful features offered by this novel approach reduce the complexity of the experimental set-up. This paper describes the principles of the oscillating magnet Kibble balance and gives details of the preliminary Planck constant measurements. The value of the Planck constant determined with our apparatus is \\boldsymbol{h}/{{\\boldsymbol{h}}\\boldsymbol 90}={1}{.000} {004}~ , with a relative standard uncertainty of 6 ppm.
Development of $Mathematica$ Package 'StandardPhysicalConstants'

CERN Document Server

Ezhela, Vladimir V

2003-01-01

Here we report on the further development of the 'StandardPhysicalConstants' package which was presented for the first time at the last IMS 2001 conference. We would like to dwell on the following issues: the package structure; current status of the physical constant database; data sourses, current data collection and data structure; the main modules of data management system; the first version of "error propagator"; usage examples of one in calculations for high precision tests of physics theories. The outlook of the future development of the package is also given.
Sequential metabolic phases as a means to optimize cellular output in a constant environment.

Science.gov (United States)

Palinkas, Aljoscha; Bulik, Sascha; Bockmayr, Alexander; Holzhütter, Hermann-Georg

2015-01-01

Temporal changes of gene expression are a well-known regulatory feature of all cells, which is commonly perceived as a strategy to adapt the proteome to varying external conditions. However, temporal (rhythmic and non-rhythmic) changes of gene expression are also observed under virtually constant external conditions. Here we hypothesize that such changes are a means to render the synthesis of the metabolic output more efficient than under conditions of constant gene activities. In order to substantiate this hypothesis, we used a flux-balance model of the cellular metabolism. The total time span spent on the production of a given set of target metabolites was split into a series of shorter time intervals (metabolic phases) during which only selected groups of metabolic genes are active. The related flux distributions were calculated under the constraint that genes can be either active or inactive whereby the amount of protein related to an active gene is only controlled by the number of active genes: the lower the number of active genes the more protein can be allocated to the enzymes carrying non-zero fluxes. This concept of a predominantly protein-limited efficiency of gene expression clearly differs from other concepts resting on the assumption of an optimal gene regulation capable of allocating to all enzymes and transporters just that fraction of protein necessary to prevent rate limitation. Applying this concept to a simplified metabolic network of the central carbon metabolism with glucose or lactate as alternative substrates, we demonstrate that switching between optimally chosen stationary flux modes comprising different sets of active genes allows producing a demanded amount of target metabolites in a significantly shorter time than by a single optimal flux mode at fixed gene activities. Our model-based findings suggest that temporal expression of metabolic genes can be advantageous even under conditions of constant external substrate supply.
Constant scalar curvature hypersurfaces in (3 + 1) -dimensional GHMC Minkowski spacetimes

Science.gov (United States)

Smith, Graham

2018-06-01

We prove that every (3 + 1) -dimensional flat GHMC Minkowski spacetime which is not a translation spacetime or a Misner spacetime carries a unique foliation by spacelike hypersurfaces of constant scalar curvature. In other words, we prove that every such spacetime carries a unique time function with isochrones of constant scalar curvature. Furthermore, this time function is a smooth submersion.
Field and polarity dependence of time-to-resistance increase in Fe–O films studied by constant voltage stress method

OpenAIRE

Eriguchi, Koji; Wei, Zhiqiang; Takagi, Takeshi; Ohta, Hiroaki; Ono, Kouichi

2009-01-01

Constant voltage stress (CVS) was applied to Fe–O films prepared by a sputtering process to investigate a stress-induced resistance increase leading to a fundamental mechanism for switching behaviors. Under the CVS, an abrupt resistance increase was found for both stress polarities. A conduction mechanism after the resistance increase exhibited non-Ohmic transport. The time-to-resistance increase (tr) under the CVS was revealed to strongly depend on stress voltage as well as the polarity. Fro...
A General Constant Power Generation Algorithm for Photovoltaic Systems

DEFF Research Database (Denmark)

Tafti, Hossein Dehghani; Maswood, Ali Iftekhar; Konstantinou, Georgios

2018-01-01

Photovoltaic power plants (PVPPs) typically operate by tracking the maximum power point in order to maximize conversion efficiency. However, with the continuous increase of installed grid-connected PVPPs, power system operators have been experiencing new challenges, like overloading, overvoltages...... on a hysteresis band controller in order to obtain fast dynamic response under transients and low power oscillation during steady-state operation. The performance of the proposed algorithm for both single- and two-stage PVPPs is examined on a 50-kVA simulation setup of these topologies. Moreover, experimental...... and operation during grid voltage disturbances. Consequently, constant power generation (CPG) is imposed by grid codes. An algorithm for the calculation of the photovoltaic panel voltage reference, which generates a constant power from the PVPP, is introduced in this paper. The key novelty of the proposed...
Determination of the fine-structure constant {alpha} by measuring the quotient of the Planck constant and the neutron mass

Energy Technology Data Exchange (ETDEWEB)

Krueger, E; Nistler, W; Weirauch, W [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

1997-04-01

Using a special high-precision apparatus at ILL the quotient h/m{sub n} (h Planck constant, m{sub n} neutron mass) has been measured. The value measured for h/m{sub n} leads to {alpha}{sup -1} = 137.03601082(524) (relative uncertainty: 3.9{center_dot}10{sup -8}) It was the first time that this fundamental constant has been determined by means of neutrons. The experiment, which had been running since 1981 in a preliminary version and since 1987 in the final version, which was finished in December 1996, is described. (author).
Ground State of the Universe and the Cosmological Constant. A Nonperturbative Analysis.

Science.gov (United States)

Husain, Viqar; Qureshi, Babar

2016-02-12

The physical Hamiltonian of a gravity-matter system depends on the choice of time, with the vacuum naturally identified as its ground state. We study the expanding Universe with scalar field in the volume time gauge. We show that the vacuum energy density computed from the resulting Hamiltonian is a nonlinear function of the cosmological constant and time. This result provides a new perspective on the relation between time, the cosmological constant, and vacuum energy.
Temperature dependence of grain boundary free energy and elastic constants

International Nuclear Information System (INIS)

Foiles, Stephen M.

2010-01-01

This work explores the suggestion that the temperature dependence of the grain boundary free energy can be estimated from the temperature dependence of the elastic constants. The temperature-dependent elastic constants and free energy of a symmetric Σ79 tilt boundary are computed for an embedded atom method model of Ni. The grain boundary free energy scales with the product of the shear modulus times the lattice constant for temperatures up to about 0.75 the melting temperature.
Union-Find with Constant Time Deletions

DEFF Research Database (Denmark)

Alstrup, Stephen; Thorup, Mikkel; Gørtz, Inge Li

2014-01-01

operations performed, and α_M/N_(n) is a functional inverse of Ackermann’s function. They left open the question whether delete operations can be implemented more efficiently than find operations, for example, in o(log n) worst-case time. We resolve this open problem by presenting a relatively simple...

Time since death and decay rate constants of Norway spruce and European larch deadwood in subalpine forests determined using dendrochronology and radiocarbon dating

Science.gov (United States)

Petrillo, Marta; Cherubini, Paolo; Fravolini, Giulia; Marchetti, Marco; Ascher-Jenull, Judith; Schärer, Michael; Synal, Hans-Arno; Bertoldi, Daniela; Camin, Federica; Larcher, Roberto; Egli, Markus

2016-03-01

Due to the large size (e.g. sections of tree trunks) and highly heterogeneous spatial distribution of deadwood, the timescales involved in the coarse woody debris (CWD) decay of Picea abies (L.) Karst. and Larix decidua Mill. in Alpine forests are largely unknown. We investigated the CWD decay dynamics in an Alpine valley in Italy using the chronosequence approach and the five-decay class system that is based on a macromorphological assessment. For the decay classes 1-3, most of the dendrochronological samples were cross-dated to assess the time that had elapsed since tree death, but for decay classes 4 and 5 (poorly preserved tree rings) radiocarbon dating was used. In addition, density, cellulose, and lignin data were measured for the dated CWD. The decay rate constants for spruce and larch were estimated on the basis of the density loss using a single negative exponential model, a regression approach, and the stage-based matrix model. In the decay classes 1-3, the ages of the CWD were similar and varied between 1 and 54 years for spruce and 3 and 40 years for larch, with no significant differences between the classes; classes 1-3 are therefore not indicative of deadwood age. This seems to be due to a time lag between the death of a standing tree and its contact with the soil. We found distinct tree-species-specific differences in decay classes 4 and 5, with larch CWD reaching an average age of 210 years in class 5 and spruce only 77 years. The mean CWD rate constants were estimated to be in the range 0.018 to 0.022 y-1 for spruce and to about 0.012 y-1 for larch. Snapshot sampling (chronosequences) may overestimate the age and mean residence time of CWD. No sampling bias was, however, detectable using the stage-based matrix model. Cellulose and lignin time trends could be derived on the basis of the ages of the CWD. The half-lives for cellulose were 21 years for spruce and 50 years for larch. The half-life of lignin is considerably higher and may be more than
Fast optimization algorithms and the cosmological constant

Science.gov (United States)

Bao, Ning; Bousso, Raphael; Jordan, Stephen; Lackey, Brad

2017-11-01

Denef and Douglas have observed that in certain landscape models the problem of finding small values of the cosmological constant is a large instance of a problem that is hard for the complexity class NP (Nondeterministic Polynomial-time). The number of elementary operations (quantum gates) needed to solve this problem by brute force search exceeds the estimated computational capacity of the observable Universe. Here we describe a way out of this puzzling circumstance: despite being NP-hard, the problem of finding a small cosmological constant can be attacked by more sophisticated algorithms whose performance vastly exceeds brute force search. In fact, in some parameter regimes the average-case complexity is polynomial. We demonstrate this by explicitly finding a cosmological constant of order 10-120 in a randomly generated 1 09-dimensional Arkani-Hamed-Dimopoulos-Kachru landscape.
Effects of Constant Flow vs. Constant Pressure Perfusion on Fluid Filtration in Severe Hypothermic Isolated Blood-Perfused Rat Lungs.

Science.gov (United States)

Halsøy, Kathrine; Kondratiev, Timofey; Tveita, Torkjel; Bjertnaes, Lars J

2016-01-01

Victims of severe accidental hypothermia are prone to fluid extravasation but rarely develop lung edema. We hypothesize that combined hypothermia-induced increase in pulmonary vascular resistance (PVR) and a concomitant fall in cardiac output protect the lungs against edema development. Our aim was to explore in hypothermic-isolated blood-perfused rat lungs whether perfusion at constant pressure influences fluid filtration differently from perfusion at constant flow. Isolated blood-perfused rat lungs were hanging freely in a weight transducer for measuring weight changes (ΔW). Fluid filtration coefficient (Kfc), was determined by transiently elevating left atrial pressure (Pla) by 5.8 mmHg two times each during normothermia (37°C) and during hypothermia (15°C). The lung preparations were randomized to two groups. One group was perfused with constant flow (Constant flow group) and the other group with constant pulmonary artery pressure (Constant PPA group). Microvascular pressure (Pmv) was determined before and during elevation of Pla (ΔPmv) by means of the double occlusion technique. Kfc was calculated with the formula Kfc = ΔW/ΔPmv/min. All Kfc values were normalized to predicted lung weight (P LW ), which was based on body weight (BW) according to the formula: P LW = 0.0053 BW - 0.48 and presented as Kfc PLW in mg/min/mmHg/g. At cessation, bronchoalveolar lavage (BAL) fluid/perfusate protein concentration (B/P) ratio was determined photometrically. Data were analyzed with parametric or non-parametric tests as appropriate. p Kfc PLW and B/P ratio increased significantly by more than 10-fold during hypothermia concerted by visible signs of edema in the trachea. Hemoglobin and hematocrit increased within the Constant flow group and between the groups at cessation of the experiments. In hypothermic rat lungs perfused at constant flow, fluid filtration coefficient per gram P LW and B/P ratio increased more than 10-fold concerted by increased
Statistical universalities in fragmentation under scaling symmetry with a constant frequency of fragmentation

International Nuclear Information System (INIS)

Gorokhovski, M A; Saveliev, V L

2008-01-01

This paper analyses statistical universalities that arise over time during constant frequency fragmentation under scaling symmetry. The explicit expression of particle-size distribution obtained from the evolution kinetic equation shows that, with increasing time, the initial distribution tends to the ultimate steady-state delta function through at least two intermediate universal asymptotics. The earlier asymptotic is the well-known log-normal distribution of Kolmogorov (1941 Dokl. Akad. Nauk. SSSR 31 99-101). This distribution is the first universality and has two parameters: the first and the second logarithmic moments of the fragmentation intensity spectrum. The later asymptotic is a power function (stronger universality) with a single parameter that is given by the ratio of the first two logarithmic moments. At large times, the first universality implies that the evolution equation can be reduced exactly to the Fokker-Planck equation instead of making the widely used but inconsistent assumption about the smallness of higher than second order moments. At even larger times, the second universality shows evolution towards a fractal state with dimension identified as a measure of the fracture resistance of the medium
Ion exchange equilibrium constants

CERN Document Server

Marcus, Y

2013-01-01

Ion Exchange Equilibrium Constants focuses on the test-compilation of equilibrium constants for ion exchange reactions. The book first underscores the scope of the compilation, equilibrium constants, symbols used, and arrangement of the table. The manuscript then presents the table of equilibrium constants, including polystyrene sulfonate cation exchanger, polyacrylate cation exchanger, polymethacrylate cation exchanger, polysterene phosphate cation exchanger, and zirconium phosphate cation exchanger. The text highlights zirconium oxide anion exchanger, zeolite type 13Y cation exchanger, and
Time structure of ns duration bunches with single crystal diamond detector

Energy Technology Data Exchange (ETDEWEB)

Duenas, J.A., E-mail: jose.duenas@dfa.uhu.es [Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Campus de El Carmen, 21071 Huelva (Spain); Ausset, P. [Institut de Physique Nucleaire d' Orsay (IPNO), Universite Paris-Sub 11, CNRS/IN2P3, 91406 Orsay Cedex (France); Berjillos, R. [Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Campus de El Carmen, 21071 Huelva (Spain); Gardes, D.; Junquera, T.; Lavergne, L. [Institut de Physique Nucleaire d' Orsay (IPNO), Universite Paris-Sub 11, CNRS/IN2P3, 91406 Orsay Cedex (France); Martel, I. [Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Campus de El Carmen, 21071 Huelva (Spain); Martinet, G.; Rauly, E.; Said, A. [Institut de Physique Nucleaire d' Orsay (IPNO), Universite Paris-Sub 11, CNRS/IN2P3, 91406 Orsay Cedex (France); Sanchez Benitez, A.M. [Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Campus de El Carmen, 21071 Huelva (Spain); Semsoun, A.; Waast, B. [Institut de Physique Nucleaire d' Orsay (IPNO), Universite Paris-Sub 11, CNRS/IN2P3, 91406 Orsay Cedex (France)

2011-06-11

A single crystal diamond detector (SC-DD) has been used to obtain the time structure of bunches with lengths between 4 and 88 ns. This was achieved by setting an electronic chain based on a time-to-amplitude converter (TAC), which used the output of the diamond detector as the start of the time interval, and the accelerator RF as the stop. Moreover, the SC-DD not only provided the time information, but also the energy of the beam.
LETTER TO THE EDITOR: Constant-time solution to the global optimization problem using Brüschweiler's ensemble search algorithm

Science.gov (United States)

Protopopescu, V.; D'Helon, C.; Barhen, J.

2003-06-01

A constant-time solution of the continuous global optimization problem (GOP) is obtained by using an ensemble algorithm. We show that under certain assumptions, the solution can be guaranteed by mapping the GOP onto a discrete unsorted search problem, whereupon Brüschweiler's ensemble search algorithm is applied. For adequate sensitivities of the measurement technique, the query complexity of the ensemble search algorithm depends linearly on the size of the function's domain. Advantages and limitations of an eventual NMR implementation are discussed.
High-efficiency dynamic routing architecture for the readout of single photon avalanche diode arrays in time-correlated measurements

Science.gov (United States)

Cominelli, A.; Acconcia, G.; Peronio, P.; Rech, I.; Ghioni, M.

2017-05-01

In recent years, the Time-Correlated Single Photon Counting (TCSPC) technique has gained a prominent role in many fields, where the analysis of extremely fast and faint luminous signals is required. In the life science, for instance, the estimation of fluorescence time-constants with picosecond accuracy has been leading to a deeper insight into many biological processes. Although the many advantages provided by TCSPC-based techniques, their intrinsically repetitive nature leads to a relatively long acquisition time, especially when time-resolved images are obtained by means of a single detector, along with a scanning point system. In the last decade, TCSPC acquisition systems have been subjected to a fast trend towards the parallelization of many independent channels, in order to speed up the measure. On one hand, some high-performance multi-module systems have been already made commercially available, but high area and power consumption of each module have limited the number of channels to only some units. On the other hand, many compact systems based on Single Photon Avalanche Diodes (SPAD) have been proposed in literature, featuring thousands of independent acquisition chains on a single chip. The integration of both detectors and conversion electronic in the same pixel area, though, has imposed tight constraints on power dissipation and area occupation of the electronics, resulting in a tradeoff with performance, both in terms of differential nonlinearity and timing jitter. Furthermore, in the ideal case of simultaneous readout of a huge number of channels, the overall data rate can be as high as 100 Gbit/s, which is nowadays too high to be easily processed in real time by a PC. Typical adopted solutions involve an arbitrary dwell time, followed by a sequential readout of the converters, thus limiting the maximum operating frequency of each channel and impairing the measurement speed, which still lies well below the limit imposed by the saturation of the
Chlorination of irradiated polyethylene single crystals

International Nuclear Information System (INIS)

Grimm, H.J.

1978-01-01

The chlorination of electron beam-irradiation polyethylene (PE) single crystals was studied for a range of irradiation doses, temperatures, and chlorine interaction times. The results presented show that PE chlorination was quite extensive, even in unirradiated PE single crystals at 25 0 C in the dark. Electron Spin Resonance (ESR, EPR) was used in this study in order to determine the alkyl radical concentration, decay constant, and diffusivity for (unchlorinated) specimens. An alkyl radical diffusivity D/sub a/ = 1.6 x 10 -17 cm 2 /sec at 25 0 C was estimated from ESR data and alkyl radical migration as one-dimensional unsteady-state diffusion process. In irradiated PE, chlorination occurred mainly via chain reactions which were initiated by the irradiation-produced free radicals. Chlorine content values were determined by X-ray Energy Spectroscopy (XES). It was found that the magnitude of the chlorine uptake increased with increasing dose, and decreased with decreasing temperature at constant dose. Otherwise the observed PE chlorination phenomena was quite similar for all of the doses and temperatures studied here, consisting of a two step mechanism: a fast uptake which occurred between time tCl 2 = 0 - 5 minutes and a slower, approximately first-order rate of uptake which occurred between times tCl 2 = 5 - 120 minutes. Chlorination was essentially complete by time tCl 2 = 120 minutes. The rapid uptake probably occurred in the amorphous surface zones where Cl 2 is relatively high and the second, slower step was probably attributable to Cl 2 diffusion into the crystalline regions and subsequent chlorination there. Inasmuch as the PE density decreases with increasing dose (for 1-600 Mrad), Cl 2 diffusivity was enhanced, resulting in higher chlorine uptake values at higher doses
Time variation of the fine structure constant driven by quintessence

International Nuclear Information System (INIS)

Anchordoqui, Luis; Goldberg, Haim

2003-01-01

There are indications from the study of quasar absorption spectra that the fine structure constant α may have been measurably smaller for redshifts z>2. Analyses of other data ( 149 Sm fission rate for the Oklo natural reactor, variation of 187 Re β-decay rate in meteorite studies, atomic clock measurements) which probe variations of α in the more recent past imply much smaller deviations from its present value. In this work we tie the variation of α to the evolution of the quintessence field proposed by Albrecht and Skordis, and show that agreement with all these data, as well as consistency with Wilkinson Microwave Anisotropy Probe observations, can be achieved for a range of parameters. Some definite predictions follow for upcoming space missions searching for violations of the equivalence principle
Simultaneous Determination of Binding Constants for Multiple Carbohydrate Hosts in Complex Mixtures

DEFF Research Database (Denmark)

Meier, Sebastian; Beeren, Sophie

2014-01-01

We describe a simple method for the simultaneous determination of association constants for a guest binding to seven different hosts in a mixture of more than 20 different oligosaccharides. If the binding parameters are known for one component in the mixture, a single NMR titration suffices...
MonoSLAM: real-time single camera SLAM.

Science.gov (United States)

Davison, Andrew J; Reid, Ian D; Molton, Nicholas D; Stasse, Olivier

2007-06-01

We present a real-time algorithm which can recover the 3D trajectory of a monocular camera, moving rapidly through a previously unknown scene. Our system, which we dub MonoSLAM, is the first successful application of the SLAM methodology from mobile robotics to the "pure vision" domain of a single uncontrolled camera, achieving real time but drift-free performance inaccessible to Structure from Motion approaches. The core of the approach is the online creation of a sparse but persistent map of natural landmarks within a probabilistic framework. Our key novel contributions include an active approach to mapping and measurement, the use of a general motion model for smooth camera movement, and solutions for monocular feature initialization and feature orientation estimation. Together, these add up to an extremely efficient and robust algorithm which runs at 30 Hz with standard PC and camera hardware. This work extends the range of robotic systems in which SLAM can be usefully applied, but also opens up new areas. We present applications of MonoSLAM to real-time 3D localization and mapping for a high-performance full-size humanoid robot and live augmented reality with a hand-held camera.
Preparation of small group constants for calculation of shielding

International Nuclear Information System (INIS)

Khokhlov, V.F.; Shejno, I.N.; Tkachev, V.D.

1979-01-01

Studied is the effect of the shielding calculation error connected with neglect of the angular and spatial neutron flux dependences while determining the small-group constants on the basis of the many-group ones. The economical method allowing for dependences is proposed. The spatial dependence is substituted by the average value according to the zones singled out in the limits of the zones of the same content; the angular cross section dependence is substituted by the average values in the half-ranges of the angular variable. To solve the transfer equation the ALGOL-ROSA-M program using the method of characteristic interpolation and trial run method is developed. The program regards correctly for nonscattered and single scattered radiations. Compared are the calculation results of neutron transmission (10.5 MeV-0.01 eV) in the 21-group approximation with the 3-group calculations for water (the layer thickness is 30 cm) and 5-group calculations for heterogeneous shielding of alternating stainless steel layers (3 layers, each of the 16 cm thickness) and graphite layers (2 layers, each of the 20 cm thickness). The analysis shows that the method proposed permits to obtain rather accurate results in the course of preparation of the small-group cross sections, decreasing considerably the number of the groups (from 21 to 3-5) and saving the machine time
IPNS time-of-flight single crystal diffractometer

International Nuclear Information System (INIS)

Schultz, A.J.; Teller, R.G.; Williams, J.M.

1983-01-01

The single crystal diffractometer (SCD) at the Argonne Intense Pulsed Neutron Source (IPNS) utilizes the time-of-flight (TOF) Laue technique to provide a three-dimensional sampling of reciprocal space during each pulse. The instrument contains a unique neutron position-sensitive 6 Li-glass scintillation detector with an active area of 30 x 30 cm. The three-dimensional nature of the data is very useful for fast, efficient measurement of Bragg intensities and for the studies of superlattice and diffuse scattering. The instrument was designed to achieve a resolution of 2% or better (R = δQ/Q) with 2 THETA > 60 0 and lambda > 0.7A
The Sun-Earth connect 2: Modelling patterns of a fractal Sun in time and space using the fine structure constant

Science.gov (United States)

Baker, Robert G. V.

2017-02-01

Self-similar matrices of the fine structure constant of solar electromagnetic force and its inverse, multiplied by the Carrington synodic rotation, have been previously shown to account for at least 98% of the top one hundred significant frequencies and periodicities observed in the ACRIM composite irradiance satellite measurement and the terrestrial 10.7cm Penticton Adjusted Daily Flux data sets. This self-similarity allows for the development of a time-space differential equation (DE) where the solutions define a solar model for transmissions through the core, radiative, tachocline, convective and coronal zones with some encouraging empirical and theoretical results. The DE assumes a fundamental complex oscillation in the solar core and that time at the tachocline is smeared with real and imaginary constructs. The resulting solutions simulate for tachocline transmission, the solar cycle where time-line trajectories either 'loop' as Hermite polynomials for an active Sun or 'tail' as complementary error functions for a passive Sun. Further, a mechanism that allows for the stable energy transmission through the tachocline is explored and the model predicts the initial exponential coronal heating from nanoflare supercharging. The twisting of the field at the tachocline is then described as a quaternion within which neutrinos can oscillate. The resulting fractal bubbles are simulated as a Julia Set which can then aggregate from nanoflares into solar flares and prominences. Empirical examples demonstrate that time and space fractals are important constructs in understanding the behaviour of the Sun, from the impact on climate and biological histories on Earth, to the fractal influence on the spatial distributions of the solar system. The research suggests that there is a fractal clock underpinning solar frequencies in packages defined by the fine structure constant, where magnetic flipping and irradiance fluctuations at phase changes, have periodically impacted on the
Statistical orientation fluctuations: constant angular momentum versus constant rotational frequency constraints

Energy Technology Data Exchange (ETDEWEB)

Goodman, A L [Tulane Univ., New Orleans, LA (United States)

1992-08-01

Statistical orientation fluctuations are calculated with two alternative assumptions: the rotational frequency remains constant as the shape orientation fluctuates; and, the average angular momentum remains constant as the shape orientation fluctuates. (author). 2 refs., 3 figs.
Structure and properties of barium tin boro-phosphate glass systems with very low photoelastic constant

Science.gov (United States)

Itadani, M.; Tricot, G.; Doumert, B.; Takebe, H.; Saitoh, A.

2017-08-01

Glasses in the BaO-SnO-P2O5-B2O3 system were prepared and evaluated in order to formulate preform glasses suitable for the fabrication of fiber cores with a very low photoelastic constant. A first glass system (I: xBaO-(60-x)SnO-40P2O5) was designed with a constant P2O5 content and various BaO contents (0-40 mol. %). Introduction of 3 mol. % of B2O3 to enhance the glass stability leads to the second glass system (II: x'BaO-(57-x')SnO-40P2O5-3B2O3) with 33-38 mol. % BaO. The structure of both systems was investigated by 1D/2D magic-angle spinning nuclear magnetic resonance, Raman, and Fourier transform infrared spectroscopic techniques. 31P NMR showed the presence of Q2 and Q1 units in the first system and correlation 11B/31P NMR indicated that boron enters into the network as B(OP)4 structural units. The photoelastic constant was determined and the stability of the best formulations as well as their refractive index dispersion was established. The drawing temperature and isothermal heating time (without crystal precipitation) parameters were also accurately measured by using experimental time-temperature-transition. Considering that the refractive indices of the core and the cladding materials must match, detailed core and cladding compositions for a fiber enabling single-mode waveguide transmission were proposed.
Constant Current versus Constant Voltage Subthalamic Nucleus Deep Brain Stimulation in Parkinson's Disease.

Science.gov (United States)

Ramirez de Noriega, Fernando; Eitan, Renana; Marmor, Odeya; Lavi, Adi; Linetzky, Eduard; Bergman, Hagai; Israel, Zvi

2015-02-18

Background: Subthalamic nucleus (STN) deep brain stimulation (DBS) is an established therapy for advanced Parkinson's disease (PD). Motor efficacy and safety have been established for constant voltage (CV) devices and more recently for constant current (CC) devices. CC devices adjust output voltage to provide CC stimulation irrespective of impedance fluctuation, while the current applied by CV stimulation depends on the impedance that may change over time. No study has directly compared the clinical effects of these two stimulation modalities. Objective: To compare the safety and clinical impact of CC STN DBS to CV STN DBS in patients with advanced PD 2 years after surgery. Methods: Patients were eligible for inclusion if they had undergone STN DBS surgery for idiopathic PD, had been implanted with a Medtronic Activa PC and if their stimulation program and medication had been stable for at least 1 year. This single-center trial was designed as a double-blind, randomized, prospective study with crossover after 2 weeks. Motor equivalence of the 2 modalities was confirmed utilizing part III of the Unified Parkinson's Disease Rating Scale (UPDRS). PD diaries and multiple subjective and objective evaluations of quality of life, depression, cognition and emotional processing were evaluated on both CV and on CC stimulation. Analysis using the paired t test with Bonferroni correction for multiple comparisons was performed to identify any significant difference between the stimulation modalities. Results: 8 patients were recruited (6 men, 2 women); 1 patient did not complete the study. The average age at surgery was 56.7 years (range 47-63). Disease duration at the time of surgery was 7.5 years (range 3-12). Patients were recruited 23.8 months (range 22.5-24) after surgery. At the postoperative study baseline, this patient group showed an average motor improvement of 69% (range 51-97) as measured by the change in UPDRS part III with stimulation alone. Levodopa equivalent
Hardware solution for continuous time-resolved burst detection of single molecules in flow

Science.gov (United States)

Wahl, Michael; Erdmann, Rainer; Lauritsen, Kristian; Rahn, Hans-Juergen

1998-04-01

Time Correlated Single Photon Counting (TCSPC) is a valuable tool for Single Molecule Detection (SMD). However, existing TCSPC systems did not support continuous data collection and processing as is desirable for applications such as SMD for e.g. DNA-sequencing in a liquid flow. First attempts at using existing instrumentation in this kind of operation mode required additional routing hardware to switch between several memory banks and were not truly continuous. We have designed a hard- and software system to perform continuous real-time TCSPC based upon a modern solid state Time to Digital Converter (TDC). Short dead times of the fully digital TDC design combined with fast Field Programmable Gay Array logic permit a continuous data throughput as high as 3 Mcounts/sec. The histogramming time may be set as short as 100 microsecond(s) . Every histogram or every single fluorescence photon can be real-time tagged at 200 ns resolution in addition to recording its arrival time relative to the excitation pulse. Continuous switching between memory banks permits concurrent histogramming and data read-out. The instrument provides a time resolution of 60 ps and up to 4096 histogram channels. The overall instrument response function in combination with a low cost picosecond diode laser and an inexpensive photomultiplier tube was found to be 180 ps and well sufficient to measure sub-nanosecond fluorescence lifetimes.
Single-Molecule Kinetics Reveal Cation-Promoted DNA Duplex Formation Through Ordering of Single-Stranded Helices

Science.gov (United States)

Dupuis, Nicholas F.; Holmstrom, Erik D.; Nesbitt, David J.

2013-01-01

In this work, the kinetics of short, fully complementary oligonucleotides are investigated at the single-molecule level. Constructs 6–9 bp in length exhibit single exponential kinetics over 2 orders of magnitude time for both forward (kon, association) and reverse (koff, dissociation) processes. Bimolecular rate constants for association are weakly sensitive to the number of basepairs in the duplex, with a 2.5-fold increase between 9 bp (k′on = 2.1(1) × 106 M−1 s−1) and 6 bp (k′on = 5.0(1) × 106 M−1 s−1) sequences. In sharp contrast, however, dissociation rate constants prove to be exponentially sensitive to sequence length, varying by nearly 600-fold over the same 9 bp (koff = 0.024 s−1) to 6 bp (koff = 14 s−1) range. The 8 bp sequence is explored in more detail, and the NaCl dependence of kon and koff is measured. Interestingly, konincreases by >40-fold (kon = 0.10(1) s−1 to 4.0(4) s−1 between [NaCl] = 25 mM and 1 M), whereas in contrast, koffdecreases by fourfold (0.72(3) s−1 to 0.17(7) s−1) over the same range of conditions. Thus, the equilibrium constant (Keq) increases by ≈160, largely due to changes in the association rate, kon. Finally, temperature-dependent measurements reveal that increased [NaCl] reduces the overall exothermicity (ΔΔH° > 0) of duplex formation, albeit by an amount smaller than the reduction in entropic penalty (−TΔΔS° duplex formation. PMID:23931323

Time delay between singly and doubly ionizing wavepackets in laser-driven helium

International Nuclear Information System (INIS)

Parker, J S; Doherty, B J S; Meharg, K J; Taylor, K T

2003-01-01

We present calculations of the time delay between single and double ionization of helium, obtained from full-dimensionality numerical integrations of the helium-laser Schroedinger equation. The notion of a quantum mechanical time delay is defined in terms of the interval between correlated bursts of single and double ionization. Calculations are performed at 390 and 780 nm in laser intensities that range from 2 x 10 14 to 14 x 10 14 Wcm -2 . We find results consistent with the rescattering model of double ionization but supporting its classical interpretation only at 780 nm. (letter to the editor)
Dielectric properties of single wall carbon nanotubes-based gelatin phantoms

Science.gov (United States)

Altarawneh, M. M.; Alharazneh, G. A.; Al-Madanat, O. Y.

In this work, we report the dielectric properties of Single wall Carbon Nanotubes (SWCNTs)-based phantom that is mainly composed of gelatin and water. The fabricated gelatin-based phantom with desired dielectric properties was fabricated and doped with different concentrations of SWCNTs (e.g., 0%, 0.05%, 0.10%, 0.15%, 0.2%, 0.4% and 0.6%). The dielectric constants (real ɛ‧ and imaginary ɛ‧‧) were measured at different positions for each sample as a function of frequency (0.5-20GHz) and concentrations of SWCNTs and their averages were found. The Cole-Cole plot (ɛ‧ versus ɛ‧‧) was obtained for each concentration of SWCNTs and was used to obtain the static dielectric constant ɛs, the dielectric constant at the high limit of frequency ɛ∞ and the average relaxation time τ. The measurements showed that the fabricated samples are in good homogeneity and the SWCNTs are dispersed well in the samples as an acceptable standard deviation is achieved. The study showed a linear increase in the static dielectric constant ɛs and invariance of the average relaxation time τ and the value of ɛ∞ at room temperature for the investigated concentrations of SWCNTs.
Time-gated single-photon detection module with 110 ps transition time and up to 80 MHz repetition rate

Energy Technology Data Exchange (ETDEWEB)

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

2014-08-15

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

International Nuclear Information System (INIS)

Buttafava, Mauro; Boso, Gianluca; Ruggeri, Alessandro; Tosi, Alberto; Dalla Mora, Alberto

2014-01-01

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

Science.gov (United States)

Bian, Q.; Niewczas, M.

2018-03-01

Transverse magnetoresistance of copper single crystals has been measured in the orientation of open-orbit from 2 K to 20 K for fields up to 9 T. The experimental Kohler's plots display deviation between individual curves below 16 K and overlap in the range of 16 K-20 K. The violation of the Kohler's rule below 16 K indicates that the magnetotransport can not be described by the classical theory of electron transport on spherical Fermi surface with a single relaxation time. A theoretical model incorporating two energy bands, spherical and cylindrical, with different relaxation times has been developed to describe the magnetoresistance data. The calculations show that the electron-phonon scattering rates at belly and neck regions of the Fermi surface have different temperature dependencies, and in general, they do not follow T3 law. The ratio of the relaxation times in belly and neck regions decreases parabolically with temperature as A - CT2 , with A and C being constants.
Neural Computations in a Dynamical System with Multiple Time Scales.

Science.gov (United States)

Mi, Yuanyuan; Lin, Xiaohan; Wu, Si

2016-01-01

Neural systems display rich short-term dynamics at various levels, e.g., spike-frequency adaptation (SFA) at the single-neuron level, and short-term facilitation (STF) and depression (STD) at the synapse level. These dynamical features typically cover a broad range of time scales and exhibit large diversity in different brain regions. It remains unclear what is the computational benefit for the brain to have such variability in short-term dynamics. In this study, we propose that the brain can exploit such dynamical features to implement multiple seemingly contradictory computations in a single neural circuit. To demonstrate this idea, we use continuous attractor neural network (CANN) as a working model and include STF, SFA and STD with increasing time constants in its dynamics. Three computational tasks are considered, which are persistent activity, adaptation, and anticipative tracking. These tasks require conflicting neural mechanisms, and hence cannot be implemented by a single dynamical feature or any combination with similar time constants. However, with properly coordinated STF, SFA and STD, we show that the network is able to implement the three computational tasks concurrently. We hope this study will shed light on the understanding of how the brain orchestrates its rich dynamics at various levels to realize diverse cognitive functions.
TCP, quantum gravity, the cosmological constant and all that .

International Nuclear Information System (INIS)

Banks, T.

1985-01-01

We study cosmology from the point of view of quantum gravity. Some light is thrown on the nature of time, and it is suggested that the cosmological arrow of time is generated by a spontaneous breakdown of TCP. Conventional cosmological models in which quantum fields interact with a time-dependent gravitational field are shown to describe an approximation to the quantum gravitational wave function which is valid in the long-wavelength limit. Two problems with initial conditions are resolved in models in which a negative bare cosmological constant is cancelled by the classical excitation of a Bose field eta with a very flat potential. These models can also give a natural explanation for the observed value of the cosmological constant. (orig.)
Shifting from constant-voltage to constant-current in Parkinson's disease patients with chronic stimulation.

Science.gov (United States)

Amami, P; Mascia, M M; Franzini, A; Saba, F; Albanese, A

2017-08-01

The study aimed to evaluate safety and efficacy of shifting stimulation settings from constant-voltage (CV) to constant-current (CC) programming in patients with Parkinson's disease (PD) and chronic subthalamic nucleus deep brain stimulation (STN DBS). Twenty PD patients with chronic STN DBS set in CV programming were shifted to CC and followed for 3 months; the other stimulation settings and the medication regimen remained unchanged. Side effects, motor, non-motor, executive functions, and impedance were assessed at baseline and during follow-up. No adverse events were observed at time of shifting or during CC stimulation. Motor and non-motor measures remained unchanged at follow-up despite impedance decreased. Compared to baseline, inhibition processes improved at follow-up. The shifting strategy was well tolerated and the clinical outcome was maintained with no need to adjust stimulation settings or medications notwithstanding a decrease of impedance. Improvement of inhibition processes is a finding which needed further investigation.
Auto-correlation of velocity-fluctuations and frequency-dependent diffusion constant for hot electrons

International Nuclear Information System (INIS)

Roy, M.D.; Nag, B.R.

1981-01-01

A method has been developed for determining the auto-correlation functions of the fluctuations in the transverse and the parallel components of hot carrier-velocity in a semiconductor by Monte Carlo simulation. The functions for electrons in InSb are determined by this method for applied electric fields of 50 V/cm, 75 V/cm, and 100 V/cm. With increasing value of the time interval the transverse auto-correlation function fall nearly exponentially to zero, but the parallel function falls sharply to a negative peak, then rises to positive values and finally becomes zero. The interval beyond which the auto-correlation function is zero and the correlation time are also evaluated. The correlation time is found to be approximately 1.6 times the relaxation time calculated from the chord mobility. The effect of the flight sampling time on the value of variance of the displacement, is investigated in terms of the low frequency diffusion constants, determined from the variation of the correlation functions. It is found that the diffusion constants become independent of the sampling time if it is of the order of one hundred times the relaxation time. The frequency-dependent diffusion constants are calculated from the correlation functions. The transverse diffusion constant falls monotonically with frequency for all the field strengths studied. The parallel diffusion constant has similar variation for the lower fields (50 V/cm and 75 V/cm) but it has a peak at about 44 GHz for the field of 100 V/cm. (orig.)
Real time hybridization studies by resonant waveguide gratings using nanopattern imaging for Single Nucleotide Polymorphism detection

KAUST Repository

Bougot-Robin, Kristelle

2013-12-20

2D imaging of biochips is particularly interesting for multiplex biosensing. Resonant properties allow label-free detection using the change of refractive index at the chip surface. We demonstrate a new principle of Scanning Of Resonance on Chip by Imaging (SORCI) based on spatial profiles of nanopatterns of resonant waveguide gratings (RWGs) and its embodiment in a fluidic chip for real-time biological studies. This scheme allows multiplexing of the resonance itself by providing nanopattern sensing areas in a bioarray format. Through several chip designs we discuss resonance spatial profiles, dispersion and electric field distribution for optimal light-matter interaction with biological species of different sizes. Fluidic integration is carried out with a black anodized aluminum chamber, advantageous in term of mechanical stability, multiple uses of the chip, temperature control and low optical background. Real-time hybridization experiments are illustrated by SNP (Single Nucleotide Polymorphism) detection in gyrase A of E. coli K12, observed in evolution studies of resistance to the antibiotic ciprofloxacin. We choose a 100 base pairs (bp) DNA target (∼30 kDa) including the codon of interest and demonstrate the high specificity of our technique for probes and targets with close affinity constants. This work validates the safe applicability of our unique combination of RWGs and simple instrumentation for real-time biosensing with sensitivity in buffer solution of ∼10 pg/mm2. Paralleling the success of RWGs sensing for cells sensing, our work opens new avenues for a large number of biological studies. © 2013 Springer Science+Business Media.
Online evolution reconstruction from a single measurement record with random time intervals for quantum communication

Science.gov (United States)

Zhou, Hua; Su, Yang; Wang, Rong; Zhu, Yong; Shen, Huiping; Pu, Tao; Wu, Chuanxin; Zhao, Jiyong; Zhang, Baofu; Xu, Zhiyong

2017-10-01

Online reconstruction of a time-variant quantum state from the encoding/decoding results of quantum communication is addressed by developing a method of evolution reconstruction from a single measurement record with random time intervals. A time-variant two-dimensional state is reconstructed on the basis of recovering its expectation value functions of three nonorthogonal projectors from a random single measurement record, which is composed from the discarded qubits of the six-state protocol. The simulated results prove that our method is robust to typical metro quantum channels. Our work extends the Fourier-based method of evolution reconstruction from the version for a regular single measurement record with equal time intervals to a unified one, which can be applied to arbitrary single measurement records. The proposed protocol of evolution reconstruction runs concurrently with the one of quantum communication, which can facilitate the online quantum tomography.
Real-time single-molecule observation of rolling-circle DNA replication

NARCIS (Netherlands)

Tanner, Nathan A.; Loparo, Joseph J.; Hamdan, Samir M.; Jergic, Slobodan; Dixon, Nicholas E.; Oijen, Antoine M. van

2009-01-01

We present a simple technique for visualizing replication of individual DNA molecules in real time. By attaching a rolling-circle substrate to a TIRF microscope-mounted flow chamber, we are able to monitor the progression of single-DNA synthesis events and accurately measure rates and processivities
New Approach for Finding Basic Performance Measures of Single Server Queue

Directory of Open Access Journals (Sweden)

Siew Khew Koh

2014-01-01

Full Text Available Consider the single server queue in which the system capacity is infinite and the customers are served on a first come, first served basis. Suppose the probability density function f(t and the cumulative distribution function F(t of the interarrival time are such that the rate f(t/1-F(t tends to a constant as t→∞, and the rate computed from the distribution of the service time tends to another constant. When the queue is in a stationary state, we derive a set of equations for the probabilities of the queue length and the states of the arrival and service processes. Solving the equations, we obtain approximate results for the stationary probabilities which can be used to obtain the stationary queue length distribution and waiting time distribution of a customer who arrives when the queue is in the stationary state.
Single-mode Laser by Parity-time Symmetry Breaking

Science.gov (United States)

2014-11-21

solenoid -like Pds5B that reside in direct proximity to Wapl and the Smc3-Scc1 in- teraction interface (fig. S13), implying that Wapl and Pds5 control the...accepted 26 September 2014 10.1126/science.1256904 REPORTS ◥ OPTICS Single-mode laser by parity-time symmetry breaking Liang Feng,1* Zi Jing Wong,1...Ren-Min Ma,1* Yuan Wang,1,2 Xiang Zhang1,2† Effective manipulation of cavity resonant modes is crucial for emission control in laser physics and
Quantum black holes and Planck's constant

International Nuclear Information System (INIS)

Ross, D.K.

1987-01-01

It is shown that the Planck-scale black holes of quantum gravity must obey a consistency condition relating Planck's constant to the integral of the mass of the black holes over time, if the usual path integral formulation of quantum mechanics is to make sense on physical spacetime. It is also shown, using time-dependent perturbation theory in ordinary quantum mechanics, that a massless particle will not propagate on physical spacetime with the black holes present unless the same condition is met. (author)
Relaxing a large cosmological constant

International Nuclear Information System (INIS)

Bauer, Florian; Sola, Joan; Stefancic, Hrvoje

2009-01-01

The cosmological constant (CC) problem is the biggest enigma of theoretical physics ever. In recent times, it has been rephrased as the dark energy (DE) problem in order to encompass a wider spectrum of possibilities. It is, in any case, a polyhedric puzzle with many faces, including the cosmic coincidence problem, i.e. why the density of matter ρ m is presently so close to the CC density ρ Λ . However, the oldest, toughest and most intriguing face of this polyhedron is the big CC problem, namely why the measured value of ρ Λ at present is so small as compared to any typical density scale existing in high energy physics, especially taking into account the many phase transitions that our Universe has undergone since the early times, including inflation. In this Letter, we propose to extend the field equations of General Relativity by including a class of invariant terms that automatically relax the value of the CC irrespective of the initial size of the vacuum energy in the early epochs. We show that, at late times, the Universe enters an eternal de Sitter stage mimicking a tiny positive cosmological constant. Thus, these models could be able to solve the big CC problem without fine-tuning and have also a bearing on the cosmic coincidence problem. Remarkably, they mimic the ΛCDM model to a large extent, but they still leave some characteristic imprints that should be testable in the next generation of experiments.
Development of a non-delay-line constant-fraction discriminator

International Nuclear Information System (INIS)

Yang Tao; Zhao Bo; Zhang Chi

2002-01-01

A Non-Delay-Line Constant-Fraction Discriminator (CFD) timing circuit is introduced. The delay line in the CFD is replaced with a low pass filter in this simplified circuit. The timing resolution of the CFD is better than 150 ps
A Kalman-filter estimate of the tidal harmonic constants

International Nuclear Information System (INIS)

Morsetti, R.

1983-01-01

A Kalman-filter estimate of the tidal harmonic constants is proposed in order to take into account their stochastic behaviour. The filter algorithm has been applied to a state-space model of a stochastic system in which the state is defined by the harmonic constants themselves. The results, analysing Trieste sea-level data, have demonstrated that this approach is very suitable for such a purpose, since good estimates and excellent resolution capabilities have been obtained. Furthermore, this method can be very useful also from a practical point of view because real-time computation of the harmonic constants can be developed where an opportune sea-level data acquisition system is available. In conclusion, this paper has emphasized that tidal harmonic constants have to be treated like random variables and, in consequence, new method of analysis can be used
Anisotropic constant-roll inflation

Energy Technology Data Exchange (ETDEWEB)

Ito, Asuka; Soda, Jiro [Kobe University, Department of Physics, Kobe (Japan)

2018-01-15

We study constant-roll inflation in the presence of a gauge field coupled to an inflaton. By imposing the constant anisotropy condition, we find new exact anisotropic constant-roll inflationary solutions which include anisotropic power-law inflation as a special case. We also numerically show that the new anisotropic solutions are attractors in the phase space. (orig.)
Effects of an applied low frequency field on the dynamics of a two-level atom interacting with a single-mode field

International Nuclear Information System (INIS)

Xun-Wei, Xu; Nian-Hua, Liu

2010-01-01

The effects of an applied low frequency field on the dynamics of a two-level atom interacting with a single-mode field are investigated. It is shown that the time evolution of the atomic population is mainly controlled by the coupling constants and the frequency of the low frequency field, which leads to a low frequency modulation function for the time evolution of the upper state population. The amplitude of the modulation function becomes larger as the coupling constants increase. The frequency of the modulation function is proportional to the frequency of the low frequency field, and decreases with increasing coupling constant. (classical areas of phenomenology)

Mimicking the cosmological constant: Constant curvature spherical solutions in a nonminimally coupled model

International Nuclear Information System (INIS)

Bertolami, Orfeu; Paramos, Jorge

2011-01-01

The purpose of this study is to describe a perfect fluid matter distribution that leads to a constant curvature region, thanks to the effect of a nonminimal coupling. This distribution exhibits a density profile within the range found in the interstellar medium and an adequate matching of the metric components at its boundary. By identifying this constant curvature with the value of the cosmological constant and superimposing the spherical distributions arising from different matter sources throughout the universe, one is able to mimic a large-scale homogeneous cosmological constant solution.
Invariant operator theory for the single-photon energy in time-varying media

International Nuclear Information System (INIS)

Jeong-Ryeol, Choi

2010-01-01

After the birth of quantum mechanics, the notion in physics that the frequency of light is the only factor that determines the energy of a single photon has played a fundamental role. However, under the assumption that the theory of Lewis–Riesenfeld invariants is applicable in quantum optics, it is shown in the present work that this widely accepted notion is valid only for light described by a time-independent Hamiltonian, i.e., for light in media satisfying the conditions, ε(i) = ε(0), μ(t) = μ(0), and σ(t) = 0 simultaneously. The use of the Lewis–Riesenfeld invariant operator method in quantum optics leads to a marvelous result: the energy of a single photon propagating through time-varying linear media exhibits nontrivial time dependence without a change of frequency. (general)
Can we calculate the fundamental dimensionless constants of physics

International Nuclear Information System (INIS)

Barut, A.O.

1987-07-01

We review some dynamical models to calculate the dimensionless constants α=e 2 /4πε 0 (h/2π)c, β=M p /m e (or β'=m μ /m e ), γ=G Fermi m e 2 /c(h/2π) 3 and δ=G Newton m e 2 /(e 2 /4πε 0 ) which are associated with the four different manifestations (electromagnetic, strong, weak and gravitational) of a possible single interaction. (author). 15 refs
Real-time single-molecule co-immunoprecipitation analyses reveal cancer-specific Ras signalling dynamics

Science.gov (United States)

Lee, Hong-Won; Kyung, Taeyoon; Yoo, Janghyun; Kim, Tackhoon; Chung, Chaeuk; Ryu, Ji Young; Lee, Hanki; Park, Kihyun; Lee, Sangkyu; Jones, Walton D.; Lim, Dae-Sik; Hyeon, Changbong; Do Heo, Won; Yoon, Tae-Young

2013-01-01

Co-immunoprecipitation (co-IP) has become a standard technique, but its protein-band output provides only static, qualitative information about protein–protein interactions. Here we demonstrate a real-time single-molecule co-IP technique that generates real-time videos of individual protein–protein interactions as they occur in unpurified cell extracts. By analysing single Ras–Raf interactions with a 50-ms time resolution, we have observed transient intermediates of the protein–protein interaction and determined all the essential kinetic rates. Using this technique, we have quantified the active fraction of native Ras proteins in xenograft tumours, normal tissue and cancer cell lines. We demonstrate that the oncogenic Ras mutations selectively increase the active-Ras fraction by one order of magnitude, without affecting total Ras levels or single-molecule signalling kinetics. Our approach allows us to probe the previously hidden, dynamic aspects of weak protein–protein interactions. It also suggests a path forward towards precision molecular diagnostics at the protein–protein interaction level. PMID:23422673
New determination of the gravitational constant G with time-of-swing method

International Nuclear Information System (INIS)

Tu Liangcheng; Li Qing; Wang Qinglan; Shao Chenggang; Yang Shanqing; Liu Linxia; Liu Qi; Luo Jun

2010-01-01

A new determination of the Newtonian gravitational constant G is presented by using a torsion pendulum with the time-of-swing method. Compared with our previous measurement with the same method, several improvements greatly reduced the uncertainties as follows: (i) two stainless steel spheres with more homogeneous density are used as the source masses instead of the cylinders used in the previous experiment, and the offset of the mass center from the geometric center is measured and found to be much smaller than that of the cylinders; (ii) a rectangular glass block is used as the main body of the pendulum, which has fewer vibration modes and hence improves the stability of the period and reduces the uncertainty of the moment of inertia; (iii) both the pendulum and source masses are placed in the same vacuum chamber to reduce the error of measuring the relative positions; (iv) changing the configurations between the ''near'' and ''far'' positions is remotely operated by using a stepper motor to lower the environmental disturbances; and (v) the anelastic effect of the torsion fiber is first measured directly by using two disk pendulums with the help of a high-Q quartz fiber. We have performed two independent G measurements, and the two G values differ by only 9 ppm. The combined value of G is (6.673 49±0.000 18)x10 -11 m 3 kg -1 s -2 with a relative uncertainty of 26 ppm.
Dielectric constant of atomic fluids with variable polarizability.

Science.gov (United States)

Alder, B J; Beers, J C; Strauss, H L; Weis, J J

1980-06-01

The Clausius-Mossotti function for the dielectric constant is expanded in terms of single atom and pair polarizabilities, leading to contributions that depend on both the trace and the anisotropy of the pair-polarizability tensor. The short-range contribution of the anisotropic part to the pair polarizabilities has previously been obtained empirically from light scattering experiments, whereas the trace contribution is now empirically determined by comparison to dielectric experiments. For helium, the short-range trace part agrees well with electronic structure calculations, whereas for argon qualitative agreement is achieved.
Sensitivity and response time improvements in millimeter-wave spectrometers

International Nuclear Information System (INIS)

Kolbe, W.F.; Leskovar, B.

1980-09-01

A new version of a microwave spectrometer for the detection of gaseous pollutants and other atmospheric constituents is described. The spectrometer, which operates in the vicinity of 70 GHz, employs a Fabry-Perot resonator as a sample cell and uses superhetrodyne detection for high sensitivity. The spectrometer has been modified to incorporate a frequency doubler modulated at 30 MHz to permit operation with a single Gunn oscillator source. As a result, faster response time and somewhat greater sensitivity are obtained. The spectrometer is capable of detecting a minimum concentration of 1 ppM of SO 2 diluted in air with a 1 second time constant. For OCS diluted in air, the minimum detectable concentration is 800 ppB and with a 10 second time constant 300 ppB
Maximal hypersurfaces and foliations of constant mean curvature in general relativity

International Nuclear Information System (INIS)

Marsden, J.E.; Tipler, F.J.; Texas Univ., Austin

1980-01-01

We prove theorems on existence, uniqueness and smoothness of maximal and constant mean curvature compact spacelike hypersurfaces in globally hyperbolic spacetimes. The uniqueness theorem for maximal hypersurfaces of Brill and Flaherty, which assumed matter everywhere, is extended to specetimes that are vacuum and non-flat or that satisfy a generic-type condition. In this connection we show that under general hypotheses, a spatially closed universe with a maximal hypersurface must be Wheeler universe; i.e. be closed in time as well. The existence of Lipschitz achronal maximal volume hypersurfaces under the hypothesis that candidate hypersurfaces are bounded away from the singularity is proved. This hypothesis is shown to be valid in two cases of interest: when the singularities are of strong curvature type, and when the singularity is a single ideal point. Some properties of these maximal volume hypersurfaces and difficulties with Avez' original arguments are discussed. The difficulties involve the possibility that the maximal volume hypersurface can be null on certain portions; we present an incomplete argument which suggests that these hypersurfaces are always smooth, but prove that an a priori bound on the second fundamental form does imply smoothness. An extension of the perturbation theorem of Choquet-Bruhat, Fischer and Marsden is given and conditions under which local foliantions by constant mean curvature hypersurfaces can be extended to global ones is obtained. (orig.)
From the Rydberg constant to the fundamental constants metrology

International Nuclear Information System (INIS)

Nez, F.

2005-06-01

This document reviews the theoretical and experimental achievements of the author since the beginning of his scientific career. This document is dedicated to the spectroscopy of hydrogen, deuterium and helium atoms. The first part is divided into 6 sub-sections: 1) the principles of hydrogen spectroscopy, 2) the measurement of the 2S-nS/nD transitions, 3) other optical frequency measurements, 4) our contribution to the determination of the Rydberg constant, 5) our current experiment on the 1S-3S transition, 6) the spectroscopy of the muonic hydrogen. Our experiments have improved the accuracy of the Rydberg Constant by a factor 25 in 15 years and we have achieved the first absolute optical frequency measurement of a transition in hydrogen. The second part is dedicated to the measurement of the fine structure constant and the last part deals with helium spectroscopy and the search for optical references in the near infrared range. (A.C.)
Asympotics with positive cosmological constant

Science.gov (United States)

Bonga, Beatrice; Ashtekar, Abhay; Kesavan, Aruna

2014-03-01

Since observations to date imply that our universe has a positive cosmological constant, one needs an extension of the theory of isolated systems and gravitational radiation in full general relativity from the asymptotically flat to asymptotically de Sitter space-times. In current definitions, one mimics the boundary conditions used in asymptotically AdS context to conclude that the asymptotic symmetry group is the de Sitter group. However, these conditions severely restricts radiation and in fact rules out non-zero flux of energy, momentum and angular momentum carried by gravitational waves. Therefore, these formulations of asymptotically de Sitter space-times are uninteresting beyond non-radiative spacetimes. The situation is compared and contrasted with conserved charges and fluxes at null infinity in asymptotically flat space-times.
CONSTANT LEVERAGE AND CONSTANT COST OF CAPITAL: A COMMON KNOWLEDGE HALF-TRUTH

Directory of Open Access Journals (Sweden)

IGNACIO VÉLEZ-PAREJA

2008-01-01

Full Text Available Un enfoque típico para valorar flujos de caja finitos es suponer que el endeudamiento es constante (generalmente como un endeudamiento objetivo o deseado y que por tanto, el costo del patrimonio, Ke y el costo promedio ponderado de capital CPPC, también son constantes. Para los flujos de caja perpetuos, y con el costo de la deuda, Kd como la tasa de descuento para el ahorro en impuestos o escudo fiscal, Ke y el CPPC aplicado al flujo de caja libre FCL son constantes si el endeudamiento es constante. Sin embargo esto no es verdad para los flujos de caja finitos. En este documento mostramos que para flujos de caja finitos, Ke y por lo tanto el CPPC dependen de la tasa de descuento que se utiliza para valorar el ahorro en impuestos, AI y según lo esperado, Ke y el CPPC no son constantes con Kd como la tasa de descuento para el ahorro en impuestos, aunque el endeudamiento sea constante. Ilustramos esta situación con un ejemplo simple. Analizamos cinco métodos: el flujo de caja descontado, FCD, usando APV, el FCD y la formulación tradicional y general del CPPC, el valor presente del flujo de caja del accionista, FCA más deuda y el flujo de caja de capital, FCC.
Measurement of the Rise-Time in a Single Sided Ladder Detector

International Nuclear Information System (INIS)

Gerber, C.E.

1997-01-01

In this note we report on the measurement of the preamplifier output rise time for a SVXII chip mounted on a D0 single sided ladder. The measurements were performed on the ladder 001-883-L, using the laser test stand of Lab D. The rise time was measured for different values of the response (or bandwidth) of the preamplifier. As a bigger bandwidth results in longer rise times and therefore in less noise, the largest possible bandwidth consistent with the time between bunch crossings should be chosen to operate the detectors. The rise time is defined as the time elapsed between 10% and 90% of the charge is collected. It is also interesting to measure the time for full charge collection and the percentage of charge collected in 132 ns and 396 ns. The results are shown in table 1, for bandwidths between 2 and 63 (binary numbers). The uncertainty on the time measurement is considered to be ∼ 10 ns. Figure 1 schematically defines the four quantities measured: rise time, time of full charge collection, and percentage of charge collected in 132 ns and 396 ns. Figures 2 to 8 are the actual measurements for bandwidths of 2, 4, 8, 12, 24, 32 and 63. Figure 9 is a second measurement for BW=24, used as a consistency check of the system and the time measurement performed on the plots. The data indicate that the single sided ladders can be operated at BW=63 for 396 ns and BW=12 for 132 ns, achieving full charge collection. This will result in smaller noise than originally anticipated.
Real-time Bacterial Detection by Single Cell Based Sensors UsingSynchrotron FTIR Spectromicroscopy

Energy Technology Data Exchange (ETDEWEB)

Veiseh, Mandana; Veiseh, Omid; Martin, Michael C.; Bertozzi,Carolyn; Zhang, Miqin

2005-08-10

Microarrays of single macrophage cell based sensors weredeveloped and demonstrated for real time bacterium detection bysynchrotron FTIR microscopy. The cells were patterned on gold-SiO2substrates via a surface engineering technique by which the goldelectrodes were immobilized with fibronectin to mediate cell adhesion andthe silicon oxide background were passivated with PEG to resist proteinadsorption and cell adhesion. Cellular morphology and IR spectra ofsingle, double, and triple cells on gold electrodes exposed tolipopolysaccharide (LPS) of different concentrations were compared toreveal the detection capabilities of these biosensors. The single-cellbased sensors were found to generate the most significant IR wave numbervariation and thus provide the highest detection sensitivity. Changes inmorphology and IR spectrum for single cells exposed to LPS were found tobe time- and concentration-dependent and correlated with each other verywell. FTIR spectra from single cell arrays of gold electrodes withsurface area of 25 mu-m2, 100 mu-m2, and 400 mu-m2 were acquired usingboth synchrotron and conventional FTIR spectromicroscopes to study thesensitivity of detection. The results indicated that the developedsingle-cell platform can be used with conventional FTIRspectromicroscopy. This technique provides real-time, label-free, andrapid bacterial detection, and may allow for statistic and highthroughput analyses, and portability.
Experimental determination of magnetocrystalline anisotropy constants and saturation magnetostriction constants of NiZn and NiZnCo ferrites intended to be used for antennas miniaturization

International Nuclear Information System (INIS)

Mattei, Jean-Luc; Le Guen, Emmanuel; Chevalier, Alexis; Tarot, Anne-Claude

2015-01-01

This study investigates the magnetocrystalline anisotropy constants (K 1 ) and the saturation magnetostriction constants (λ S ) of Ni 1−x Zn x Fe 2 O 4 (NiZn) and Ni 0.8−x Zn x Co 0.2 Fe 1.98 O 4−δ (NiZnCo) ferrites intended to be used for antenna downsizing. Composite materials constituted of soft ferrite nanosized particles (NiZn or NiZnCo ferrites) embedded in an epoxy matrix are realized. Measurements of their magnetic permeability in the frequency range of 200 MHz–6 GHz are performed. The influence of compressive stress (in the range of 32–96 MPa) on their Ferrimagnetic Resonance (FMR) is demonstrated. An analytical modeling of stress-induced FMR changes is proposed that allows simultaneous determinations of the Natural Ferrimagnetic Resonance (NFMR, F 0 ), K 1 and λ S of Ni 1−x Zn x Fe 2 O 4 and Ni 0.8−x Zn x Co 0.2 Fe 1.98 O 4−δ ferrites. The obtained results for NiZn ferrites are in agreement with literature data, validating both the experimental process and the proposed modeling of the stress-induced FMR changes. Regarding NiZnCo ferrites, extended data on K 1 and λ S are presented for the first time. Increasing zinc content (x) induces a spin disorder that reduces in a same time K 1 and the magnetization at saturation M S . The rapid variation of K 1 (x) is related to that of the magnetization M S (x) through a power law. The single-ion anisotropy model allows a satisfactory interpretation of K 1 dependence on zinc content. The unexpected low values of λ S got for NiZnCo ferrites, compared to those got for NiZn ferrites, are also discussed. Application of compressive stress lowers noticeably magnetic losses of Ni 0.6 Zn 0.2 Co 0.2 Fe 1.98 O 4−δ at given frequency, thereby enhancing the ability of this spinel ferrite to be used as a substrate in the aim of antenna miniaturization. - Highlights: • We measure permeability of ferrite-based composites from 0.1 GHz to 6 GHz. • The influence of compressive stress on the FMR of
Modified large number theory with constant G

International Nuclear Information System (INIS)

Recami, E.

1983-01-01

The inspiring ''numerology'' uncovered by Dirac, Eddington, Weyl, et al. can be explained and derived when it is slightly modified so to connect the ''gravitational world'' (cosmos) with the ''strong world'' (hadron), rather than with the electromagnetic one. The aim of this note is to show the following. In the present approach to the ''Large Number Theory,'' cosmos and hadrons are considered to be (finite) similar systems, so that the ratio R-bar/r-bar of the cosmos typical length R-bar to the hadron typical length r-bar is constant in time (for instance, if both cosmos and hadrons undergo an expansion/contraction cycle: according to the ''cyclical big-bang'' hypothesis: then R-bar and r-bar can be chosen to be the maximum radii, or the average radii). As a consequence, then gravitational constant G results to be independent of time. The present note is based on work done in collaboration with P.Caldirola, G. D. Maccarrone, and M. Pavsic
Acute changes in motor cortical excitability during slow oscillatory and constant anodal transcranial direct current stimulation

DEFF Research Database (Denmark)

Bergmann, Til Ole; Groppa, Sergiu; Seeger, Markus

2009-01-01

Transcranial oscillatory current stimulation has recently emerged as a noninvasive technique that can interact with ongoing endogenous rhythms of the human brain. Yet, there is still little knowledge on how time-varied exogenous currents acutely modulate cortical excitability. In ten healthy...... individuals we used on-line single-pulse transcranial magnetic stimulation (TMS) to search for systematic shifts in corticospinal excitability during anodal sleeplike 0.8-Hz slow oscillatory transcranial direct current stimulation (so-tDCS). In separate sessions, we repeatedly applied 30-s trials (two blocks...... at 20 min) of either anodal so-tDCS or constant tDCS (c-tDCS) to the primary motor hand area during quiet wakefulness. Simultaneously and time-locked to different phase angles of the slow oscillation, motor-evoked potentials (MEPs) as an index of corticospinal excitability were obtained...
Time-Dependent Quantum Wave Packet Study of the Si + OH → SiO + H Reaction: Cross Sections and Rate Constants.

Science.gov (United States)

Rivero Santamaría, Alejandro; Dayou, Fabrice; Rubayo-Soneira, Jesus; Monnerville, Maurice

2017-03-02

The dynamics of the Si( 3 P) + OH(X 2 Π) → SiO(X 1 Σ + ) + H( 2 S) reaction is investigated by means of the time-dependent wave packet (TDWP) approach using an ab initio potential energy surface recently developed by Dayou et al. ( J. Chem. Phys. 2013 , 139 , 204305 ) for the ground X 2 A' electronic state. Total reaction probabilities have been calculated for the first 15 rotational states j = 0-14 of OH(v=0,j) at a total angular momentum J = 0 up to a collision energy of 1 eV. Integral cross sections and state-selected rate constants for the temperature range 10-500 K were obtained within the J-shifting approximation. The reaction probabilities display highly oscillatory structures indicating the contribution of long-lived quasibound states supported by the deep SiOH/HSiO wells. The cross sections behave with collision energies as expected for a barrierless reaction and are slightly sensitive to the initial rotational excitation of OH. The thermal rate constants show a marked temperature dependence below 200 K with a maximum value around 15 K. The TDWP results globally agree with the results of earlier quasi-classical trajectory (QCT) calculations carried out by Rivero-Santamaria et al. ( Chem. Phys. Lett. 2014 , 610-611 , 335 - 340 ) with the same potential energy surface. In particular, the thermal rate constants display a similar temperature dependence, with TDWP values smaller than the QCT ones over the whole temperature range.
A natural-color mapping for single-band night-time image based on FPGA

Science.gov (United States)

Wang, Yilun; Qian, Yunsheng

2018-01-01

A natural-color mapping for single-band night-time image method based on FPGA can transmit the color of the reference image to single-band night-time image, which is consistent with human visual habits and can help observers identify the target. This paper introduces the processing of the natural-color mapping algorithm based on FPGA. Firstly, the image can be transformed based on histogram equalization, and the intensity features and standard deviation features of reference image are stored in SRAM. Then, the real-time digital images' intensity features and standard deviation features are calculated by FPGA. At last, FPGA completes the color mapping through matching pixels between images using the features in luminance channel.
The development of the time-keeping clock with TS-1 single chip microcomputer.

Science.gov (United States)

Zhou, Jiguang; Li, Yongan

The authors have developed a time-keeping clock with Intel 8751 single chip microcomputer that has been successfully used in time-keeping station. The hard-soft ware design and performance of the clock are introduced.
Analysis of the dual phase lag bio-heat transfer equation with constant and time-dependent heat flux conditions on skin surface

Directory of Open Access Journals (Sweden)

Ziaei Poor Hamed

2016-01-01

Full Text Available This article focuses on temperature response of skin tissue due to time-dependent surface heat fluxes. Analytical solution is constructed for DPL bio-heat transfer equation with constant, periodic and pulse train heat flux conditions on skin surface. Separation of variables and Duhamel’s theorem for a skin tissue as a finite domain are employed. The transient temperature responses for constant and time-dependent boundary conditions are obtained and discussed. The results show that there is major discrepancy between the predicted temperature of parabolic (Pennes bio-heat transfer, hyperbolic (thermal wave and DPL bio-heat transfer models when high heat flux accidents on the skin surface with a short duration or propagation speed of thermal wave is finite. The results illustrate that the DPL model reduces to the hyperbolic model when τT approaches zero and the classic Fourier model when both thermal relaxations approach zero. However for τq = τT the DPL model anticipates different temperature distribution with that predicted by the Pennes model. Such discrepancy is due to the blood perfusion term in energy equation. It is in contrast to results from the literature for pure conduction material, where the DPL model approaches the Fourier heat conduction model when τq = τT . The burn injury is also investigated.

Finite-field evaluation of the Lennard-Jones atom-wall interaction constant C3 for alkali-metal atoms

International Nuclear Information System (INIS)

Johnson, W.R.; Dzuba, V.A.; Safronova, U.I.; Safronova, M.S.

2004-01-01

A finite-field scaling method is applied to evaluate the Lennard-Jones interaction constant C 3 for alkali-metal atoms. The calculations are based on the relativistic single-double approximation in which single and double excitations of Dirac-Hartree-Fock wave functions are included to all orders in perturbation theory
Single machine total completion time minimization scheduling with a time-dependent learning effect and deteriorating jobs

Science.gov (United States)

Wang, Ji-Bo; Wang, Ming-Zheng; Ji, Ping

2012-05-01

In this article, we consider a single machine scheduling problem with a time-dependent learning effect and deteriorating jobs. By the effects of time-dependent learning and deterioration, we mean that the job processing time is defined by a function of its starting time and total normal processing time of jobs in front of it in the sequence. The objective is to determine an optimal schedule so as to minimize the total completion time. This problem remains open for the case of -1 < a < 0, where a denotes the learning index; we show that an optimal schedule of the problem is V-shaped with respect to job normal processing times. Three heuristic algorithms utilising the V-shaped property are proposed, and computational experiments show that the last heuristic algorithm performs effectively and efficiently in obtaining near-optimal solutions.
Asymmetric modes and complex time eigenvalues of the one-speed neutron transport equation in a homogeneous sphere

International Nuclear Information System (INIS)

Paranjape, S.D.; Kumar, V.; Sahni, D.C.

1993-01-01

The one-speed, time-dependent, isotropically scattering, integral transport equation in a homogeneous sphere has been converted into a criticality-like problem by considering exponential time behaviour of the scalar flux. This criticality problem has been converted into a matrix eigenvalue problem using the Fourier transform technique. The time eigenvalues λ, which are complex in general, have been determined for spherically symmetric as well as asymmetric modes. For the former case, the real decay constants and the real parts of complex decay constants decrease monotonically with increasing system size and form two distinct families of single-valued functions. For the spherically asymmetric modes, certain new features emerge. The real decay constants are found to be multi-valued functions of system size and they do not always decrease monotonically with increasing system size. As the system size increases from zero onwards, the decay constants alternate between complex and real values and the real and complex decay constant curves interlace. (Author)
Biodegradation testing of chemicals with high Henry’s constants – separating mass and effective concentration reveals higher rate constants

DEFF Research Database (Denmark)

Birch, Heidi; Andersen, Henrik Rasmus; Comber, Mike

Microextraction (HS-SPME) was applied directly on the test systems to measure substrate depletion by biodegradation relative to abiotic controls. HS-SPME was also applied to determine air to water partitioning ratios. Water phase biodegradation rate constants, kwater, were up to 72 times higher than test system...
Time Spent in Home Production Activities by Married Couples and Single Adults with Children.

Science.gov (United States)

Douthitt, Robin A.

1988-01-01

A study found that, over time, married women employed full time have not decreased the time spent working in the home. Married men with young children have increased the time spent on home work. Single parents' time most closely resembled that of married women. (JOW)
Research of digital constant fraction discriminator in PET system

International Nuclear Information System (INIS)

Du Yaoyao; Hu Xuanhou; Wu Jianping; Wang Peilin; Li Xiaohui; Li Daowu; Li Ke; Wei Long

2012-01-01

The research on digital constant fraction discriminator of spike pulse signal in PET detector is introduced. Based on FPGA technique, rapid signal's time information is extracted via DCFD algorithm after a high-speed ADC digitization. Experiment results show that time resolution of DCFD is 772 ps, which meets the requirement of time measurement in PET system well. (authors)
Time resolution studies using digital constant fraction discrimination

International Nuclear Information System (INIS)

Fallu-Labruyere, A.; Tan, H.; Hennig, W.; Warburton, W.K.

2007-01-01

Digital Pulse Processing (DPP) modules are being increasingly considered to replace modular analog electronics in medium-scale nuclear physics experiments (100-1000s of channels). One major area remains, however, where it has not been convincingly demonstrated that DPP modules are competitive with their analog predecessors-time-of-arrival measurement. While analog discriminators and time-to-amplitude converters can readily achieve coincidence time resolutions in the 300-500 ps range with suitably fast scintillators and Photomultiplier Tubes (PMTs), this capability has not been widely demonstrated with DPPs. Some concern has been expressed, in fact, that such time resolutions are attainable with the 10 ns sampling times that are presently commonly available. In this work, we present time-coincidence measurements taken using a commercially available DPP (the Pixie-4 from XIA LLC) directly coupled to pairs of fast PMTs mated with either LSO or LaBr 3 scintillator crystals and excited by 22 Na γ-ray emissions. Our results, 886 ps for LSO and 576 ps for LaBr 3 , while not matching the best literature results using analog electronics, are already well below 1 ns and fully adequate for a wide variety of experiments. These results are shown not to be limited by the DPPs themselves, which achieved 57 ps time resolution using a pulser, but are degraded in part both by the somewhat limited number of photoelectrons we collected and by a sub-optimum choice of PMT. Analysis further suggests that increasing the sampling speed would further improve performance. We therefore conclude that DPP time-of-arrival resolution is already adequate to supplant analog processing in many applications and that further improvements could be achieved with only modest efforts
Accuracy of single photoelectron time spread measurement of fast photomultipliers

International Nuclear Information System (INIS)

Leskovar, B.

1975-01-01

The accuracy of time spread measurements of fast photomultipliers was investigated, using single photoelectrons. The effect of the finite light pulse width on the measurement accuracy was determined and discussed. Experimental data were obtained on a special measuring system for light pulse widths ranging from 200 psec to 10 nsec, using fast photomultipliers 8850 and C31024 with optimized operating conditions for minimum transit time spread. A modified exponential function expression and curve-fitting parameters are given, which fit closely the experimentally obtained data over a wide dynamic range of light pulse widths. (U.S.)
Constant leverage and constant cost of capital : A common knowledge half-truth

OpenAIRE

Vélez Pareja, Ignacio; Ibragimov, Rauf; Tham , Joseph

2008-01-01

Un enfoque típico para valorar flujos de caja finitos es suponer que el endeudamiento es constante (generalmente como un endeudamiento objetivo o deseado) y que por tanto, el costo del patrimonio, Ke y el costo promedio ponderado de capital CPPC, también son constantes. Para los flujos de caja perpetuos, y con el costo de la deuda, Kd como la tasa de descuento para el ahorro en impuestos o escudo fiscal, Ke y el CPPC aplicado al flujo de caja libre FCL son constantes si el endeudamiento es co...
Proceedings of the specialists' meeting on reactor group constants

Energy Technology Data Exchange (ETDEWEB)

Katakura, Jun-ichi (ed.) [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2001-08-01

This report is the Proceedings of the Specialists' Meeting on Reactor Group Constants. The meeting was held on February 22-23, 2001 at Tokai Research Establishment of Japan Atomic Energy Research Institute with the participation of 59 specialists. The evaluation work for JENDL-3.3 is going on for the publication in a short time. The processing JENDL-3.3 file to make reactor group constants is needed when it is used in application fields. In the meeting, the present status of the reactor group constants was reviewed and the issues relating to them were discussed in such fields as thermal reactor, criticality safety, fast reactor, high energy region, burn-up calculation and radiation shielding. At the final session in the meeting, standardization of reactor group constants was discussed and the need of the reference group constants was confirmed by the participants. The 11 of the presented papers are indexed individually. (J.P.N.)
Using machine learning to identify structural breaks in single-group interrupted time series designs.

Science.gov (United States)

Linden, Ariel; Yarnold, Paul R

2016-12-01

Single-group interrupted time series analysis (ITSA) is a popular evaluation methodology in which a single unit of observation is being studied, the outcome variable is serially ordered as a time series and the intervention is expected to 'interrupt' the level and/or trend of the time series, subsequent to its introduction. Given that the internal validity of the design rests on the premise that the interruption in the time series is associated with the introduction of the treatment, treatment effects may seem less plausible if a parallel trend already exists in the time series prior to the actual intervention. Thus, sensitivity analyses should focus on detecting structural breaks in the time series before the intervention. In this paper, we introduce a machine-learning algorithm called optimal discriminant analysis (ODA) as an approach to determine if structural breaks can be identified in years prior to the initiation of the intervention, using data from California's 1988 voter-initiated Proposition 99 to reduce smoking rates. The ODA analysis indicates that numerous structural breaks occurred prior to the actual initiation of Proposition 99 in 1989, including perfect structural breaks in 1983 and 1985, thereby casting doubt on the validity of treatment effects estimated for the actual intervention when using a single-group ITSA design. Given the widespread use of ITSA for evaluating observational data and the increasing use of machine-learning techniques in traditional research, we recommend that structural break sensitivity analysis is routinely incorporated in all research using the single-group ITSA design. © 2016 John Wiley & Sons, Ltd.
Real-time monitoring of Lévy flights in a single quantum system

Science.gov (United States)

Issler, M.; Höller, J.; Imamoǧlu, A.

2016-02-01

Lévy flights are random walks where the dynamics is dominated by rare events. Even though they have been studied in vastly different physical systems, their observation in a single quantum system has remained elusive. Here we analyze a periodically driven open central spin system and demonstrate theoretically that the dynamics of the spin environment exhibits Lévy flights. For the particular realization in a single-electron charged quantum dot driven by periodic resonant laser pulses, we use Monte Carlo simulations to confirm that the long waiting times between successive nuclear spin-flip events are governed by a power-law distribution; the corresponding exponent η =-3 /2 can be directly measured in real time by observing the waiting time distribution of successive photon emission events. Remarkably, the dominant intrinsic limitation of the scheme arising from nuclear quadrupole coupling can be minimized by adjusting the magnetic field or by implementing spin echo.
MCFT: a program for calculating fast and thermal neutron multigroup constants

International Nuclear Information System (INIS)

Yang Shunhai; Sang Xinzeng

1993-01-01

MCFT is a program for calculating the fast and thermal neutron multigroup constants, which is redesigned from some codes for generation of thermal neutron multigroup constants and for fast neutron multigroup constants adapted on CYBER 825 computer. It uses indifferently as basic input with the evaluated nuclear data contained in the ENDF/B (US), KEDAK (Germany) and UK (United Kingdom) libraries. The code includes a section devoted to the generation of resonant Doppler broadened cross section in the framework of single-or multi-level Breit-Wigner formalism. The program can compute the thermal neutron scattering law S (α, β, T) as the input data in tabular, free gas or diffusion motion form. It can treat up to 200 energy groups and Legendre moments up to P 5 . The output consists of various reaction multigroup constants in all neutron energy range desired in the nuclear reactor design and calculation. Three options in input file can be used by the user. The output format is arbitrary and defined by user with a minimum of program modification. The program includes about 15,000 cards and 184 subroutines. FORTRAN 5 computer language is used. The operation system is under NOS 2 on computer CYBER 825
Perspectives on Constraining a Cosmological Constant-Type Parameter with Pulsar Timing in the Galactic Center

Directory of Open Access Journals (Sweden)

Lorenzo Iorio

2018-03-01

Full Text Available Independent tests aiming to constrain the value of the cosmological constant Λ are usually difficult because of its extreme smallness ( Λ ≃ 1 × 10 - 52 m - 2 , or 2 . 89 × 10 - 122 in Planck units . Bounds on it from Solar System orbital motions determined with spacecraft tracking are currently at the ≃ 10 - 43 – 10 - 44 m - 2 ( 5 – 1 × 10 - 113 in Planck units level, but they may turn out to be optimistic since Λ has not yet been explicitly modeled in the planetary data reductions. Accurate ( σ τ p ≃ 1 – 10 μ s timing of expected pulsars orbiting the Black Hole at the Galactic Center, preferably along highly eccentric and wide orbits, might, at least in principle, improve the planetary constraints by several orders of magnitude. By looking at the average time shift per orbit Δ δ τ ¯ p Λ , an S2-like orbital configuration with e = 0 . 8839 , P b = 16 yr would permit a preliminarily upper bound of the order of Λ ≲ 9 × 10 - 47 m - 2 ≲ 2 × 10 - 116 in Planck units if only σ τ p were to be considered. Our results can be easily extended to modified models of gravity using Λ -type parameters.
Constant time distance queries in planar unweighted graphs with subquadratic preprocessing time

DEFF Research Database (Denmark)

Wulff-Nilsen, C.

2013-01-01

Let G be an n-vertex planar, undirected, and unweighted graph. It was stated as open problems whether the Wiener index, defined as the sum of all-pairs shortest path distances, and the diameter of G can be computed in o(n(2)) time. We show that both problems can be solved in O(n(2) log log n/log n......) time with O(n) space. The techniques that we apply allow us to build, within the same time bound, an oracle for exact distance queries in G. More generally, for any parameter S is an element of [(log n/log log n)(2), n(2/5)], distance queries can be answered in O (root S log S/log n) time per query...... with O(n(2)/root S) preprocessing time and space requirement. With respect to running time, this is better than previous algorithms when log S = o(log n). All algorithms have linear space requirement. Our results generalize to a larger class of graphs including those with a fixed excluded minor. (C) 2012...
New definitions of pointing stability - ac and dc effects. [constant and time-dependent pointing error effects on image sensor performance

Science.gov (United States)

Lucke, Robert L.; Sirlin, Samuel W.; San Martin, A. M.

1992-01-01

For most imaging sensors, a constant (dc) pointing error is unimportant (unless large), but time-dependent (ac) errors degrade performance by either distorting or smearing the image. When properly quantified, the separation of the root-mean-square effects of random line-of-sight motions into dc and ac components can be used to obtain the minimum necessary line-of-sight stability specifications. The relation between stability requirements and sensor resolution is discussed, with a view to improving communication between the data analyst and the control systems engineer.
A 30 ps Timing Resolution for Single Photons with Multi-pixel Burle MCP-PMT

Energy Technology Data Exchange (ETDEWEB)

Va' vra, J.; Benitez, J.; Coleman, J.; Leith, D.W.G.S.; Mazaheri, G.; Ratcliff, B.; Schwiening, J.; /SLAC

2006-07-05

We have achieved {approx}30 psec single-photoelectron and {approx}12ps for multi-photoelectron timing resolution with a new 64 pixel Burle MCP-PMT with 10 micron microchannel holes. We have also demonstrated that this detector works in a magnetic field of 15kG, and achieved a single-photoelectron timing resolution of better than 60 psec. The study is relevant for a new focusing DIRC RICH detector for particle identification at future Colliders such as the super B-factory or ILC, and for future TOF techniques. This study shows that a highly pixilated MCP-PMT can deliver excellent timing resolution.
Arrhenius Rate: constant volume burn

Energy Technology Data Exchange (ETDEWEB)

Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-12-06

A constant volume burn occurs for an idealized initial state in which a large volume of reactants at rest is suddenly raised to a high temperature and begins to burn. Due to the uniform spatial state, there is no fluid motion and no heat conduction. This reduces the time evolu tion to an ODE for the reaction progress variable. With an Arrhenius reaction rate, two characteristics of thermal ignition are illustrated: induction time and thermal runaway. The Frank-Kamenetskii approximation then leads to a simple expression for the adiabatic induction time. For a first order reaction, the analytic solution is derived and used to illustrate the effect of varying the activation temperature; in particular, on the induction time. In general, the ODE can be solved numerically. This is used to illustrate the effect of varying the reaction order. We note that for a first order reaction, the time evolution of the reaction progress variable has an exponential tail. In contrast, for a reaction order less than one, the reaction completes in a nite time. The reaction order also affects the induction time.
Teichmueller motion of (2+1)-dimensional gravity with the cosmological constant

International Nuclear Information System (INIS)

Fujiwara, Yoshihisa; Soda, Jiro.

1989-08-01

The (2+1)-dimensional Einstein gravity with a cosmological constant is studied in the ADM canonical formalism. Adopting the York's time slice, we completely solve the initial-value problem and the time evolution equations with an initial spacelike 2-surface being a closed Riemann surface of genus zero and one. The result in a torus case is that the Teichmueller parameters for the torus follow a geodesic in the Teichmueller space but its motion asymptotically stops due to the presence of the cosmological constant. (author)
Intermittent flow under constant forcing: Acoustic emission from creep avalanches

Science.gov (United States)

Salje, Ekhard K. H.; Liu, Hanlong; Jin, Linsen; Jiang, Deyi; Xiao, Yang; Jiang, Xiang

2018-01-01

While avalanches in field driven ferroic systems (e.g., Barkhausen noise), domain switching of martensitic nanostructures, and the collapse of porous materials are well documented, creep avalanches (avalanches under constant forcing) were never observed. Collapse avalanches generate particularly large acoustic emission (AE) signals and were hence chosen to investigate crackling noise under creep conditions. Piezoelectric SiO2 has a strong piezoelectric response even at the nanoscale so that we chose weakly bound SiO2 spheres in natural sandstone as a representative for the study of avalanches under time-independent, constant force. We found highly non-stationary crackling noise with four activity periods, each with power law distributed AE emission. Only the period before the final collapse shows the mean field behavior (ɛ near 1.39), in agreement with previous dynamic measurements at a constant stress rate. All earlier event periods show collapse with larger exponents (ɛ = 1.65). The waiting time exponents are classic with τ near 2.2 and 1.32. Creep data generate power law mixing with "effective" exponents for the full dataset with combinations of mean field and non-mean field regimes. We find close agreement with the predicted time-dependent fiber bound simulations, including events and waiting time distributions. Båth's law holds under creep conditions.

Reduction of the jitter of single-flux-quantum time-to-digital converters for time-of-flight mass spectrometry

International Nuclear Information System (INIS)

Sano, K.; Muramatsu, Y.; Yamanashi, Y.; Yoshikawa, N.; Zen, N.; Ohkubo, M.

2014-01-01

Highlights: • We proposed single-flux-quantum (SFQ) time-to-digital converters (TDCs) for TOF-MS. • SFQ TDC can measure time intervals between multiple signals with high-resolution. • SFQ TDC can directly convert the time intervals into binary data. • We designed two types of SFQ TDCs to reduce the jitter. • The jitter is reduced to less than 100 ps. - Abstract: We have been developing a high-resolution superconducting time-of-flight mass spectrometry (TOF-MS) system, which utilizes a superconducting strip ion detector (SSID) and a single-flux-quantum (SFQ) time-to-digital converter (TDC). The SFQ TDC can measure time intervals between multiple input signals and directly convert them into binary data. In our previous study, 24-bit SFQ TDC with a 3 × 24-bit First-In First-Out (FIFO) buffer was designed and implemented using the AIST Nb standard process 2 (STP2), whose time resolution and dynamic range are 100 ps and 1.6 ms, respectively. In this study we reduce the jitter of the TDC by using two different approaches: one uses an on-chip clock generator with an on-chip low-pass filter for reducing the noise in the bias current, and the other uses a low-jitter external clock source at room temperature. We confirmed that the jitter is reduced to less than 100 ps in the latter approach
Reduction of the jitter of single-flux-quantum time-to-digital converters for time-of-flight mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Sano, K., E-mail: sano-kyosuke-cw@ynu.jp [Department Electrical and Computer Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan); Muramatsu, Y.; Yamanashi, Y.; Yoshikawa, N. [Department Electrical and Computer Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan); Zen, N.; Ohkubo, M. [Research Institute of Instrumentation Frontier, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba 305-8568 (Japan)

2014-09-15

Highlights: • We proposed single-flux-quantum (SFQ) time-to-digital converters (TDCs) for TOF-MS. • SFQ TDC can measure time intervals between multiple signals with high-resolution. • SFQ TDC can directly convert the time intervals into binary data. • We designed two types of SFQ TDCs to reduce the jitter. • The jitter is reduced to less than 100 ps. - Abstract: We have been developing a high-resolution superconducting time-of-flight mass spectrometry (TOF-MS) system, which utilizes a superconducting strip ion detector (SSID) and a single-flux-quantum (SFQ) time-to-digital converter (TDC). The SFQ TDC can measure time intervals between multiple input signals and directly convert them into binary data. In our previous study, 24-bit SFQ TDC with a 3 × 24-bit First-In First-Out (FIFO) buffer was designed and implemented using the AIST Nb standard process 2 (STP2), whose time resolution and dynamic range are 100 ps and 1.6 ms, respectively. In this study we reduce the jitter of the TDC by using two different approaches: one uses an on-chip clock generator with an on-chip low-pass filter for reducing the noise in the bias current, and the other uses a low-jitter external clock source at room temperature. We confirmed that the jitter is reduced to less than 100 ps in the latter approach.
Directional effects in transitional resonance spectra and group constants

International Nuclear Information System (INIS)

Hill, R.N.; Oh, K.O.; Rhodes, J.D.

1989-01-01

Analytical exploratory investigations indicate that transition effects such as streaming cause a considerable spatial variation in the neutron spectra across resonances; streaming leads to opposite effects in the forward and backward directions. The neglect of this coupled spatial/angular variations of the transitory resonance spectra is an approximation that is common to all current group constant generation methodologies. This paper presents a description of the spatial/angular coupling of the neutron flux across isolated resonances. It appears to be necessary to differentiate between forward-and backward-directed neutron flux components or even to consider components in narrower angular cones. The effects are illustrated for an isolated actinide resonance in a simplified fast reactor blanket problem. The resonance spectra of the directional flux components φ + and φ - , and even more so the 90-deg cone components, are shown to deviate significantly from the infinite medium approximation, and the differences increase with penetration. The charges in φ + lead to a decreasing scattering group constant that enhances neutron transmission; the changes in φ - lead to an increasing group constant inhibiting backward scattering. Therefore, the changes in the forward-and backward-directed spectra both lead to increased neutron transmission. Conversely, the flux (φ = φ + +φ - ) is shown to agree closely with the infinite medium approximation both in the analytical formulas and in the numerical solution. The directional effect cancel in the summation. The forward-and backward-directed flux components are used as weighting spectra to illustrate the group constant changes for a single resonance
Ab initio calculation of hyperfine splitting constants of molecules

Science.gov (United States)

Ohta, K.; Nakatsuji, H.; Hirao, K.; Yonezawa, T.

1980-08-01

Hyperfine splitting (hfs) constants of molecules, methyl, ethyl, vinyl, allyl, cyclopropyl, formyl, O3-, NH2, NO2, and NF2 radicals have been calculated by the pseudo-orbital (PO) theory, the unrestricted HF (UHF), projected UHF (PUHF) and single excitation (SE) CI theories. The pseudo-orbital (PO) theory is based on the symmetry-adapted-cluster (SAC) expansion proposed previously. Several contractions of the Gaussian basis sets of double-zeta accuracy have been examined. The UHF results were consistently too large to compare with experiments and the PUHF results were too small. For molecules studied here, the PO theory and SECI theory gave relatively close results. They were in fair agreement with experiments. The first-order spin-polarization self-consistency effect, which was shown to be important for atoms, is relatively small for the molecules. The present result also shows an importance of eliminating orbital-transformation dependence from conventional first-order perturbation calculations. The present calculations have explained well several important variations in the experimental hfs constants.
Formation of low time-bandwidth product, single-sided exponential optical pulses in free-electron laser oscillators

NARCIS (Netherlands)

MacLeod, A. M.; Yan, X.; Gillespie, W. A.; Knippels, G.M.H.; Oepts, D.; van der Meer, A. F. G.; Rella, C. W.; Smith, T. J.; Schwettman, H. A.

2000-01-01

The detailed shape of picosecond optical pulses from a free-electron laser (FEL) oscillator has been studied for various cavity detunings. For large values of the cavity detuning the optical pulse develops an exponential leading edge, with a time constant proportional to the applied cavity detuning
How universe evolves with cosmological and gravitational constants

Directory of Open Access Journals (Sweden)

She-Sheng Xue

2015-08-01

Full Text Available With a basic varying space–time cutoff ℓ˜, we study a regularized and quantized Einstein–Cartan gravitational field theory and its domains of ultraviolet-unstable fixed point gir≳0 and ultraviolet-stable fixed point guv≈4/3 of the gravitational gauge coupling g=(4/3G/GNewton. Because the fundamental operators of quantum gravitational field theory are dimension-2 area operators, the cosmological constant is inversely proportional to the squared correlation length Λ∝ξ−2. The correlation length ξ characterizes an infrared size of a causally correlate patch of the universe. The cosmological constant Λ and the gravitational constant G are related by a generalized Bianchi identity. As the basic space–time cutoff ℓ˜ decreases and approaches to the Planck length ℓpl, the universe undergoes inflation in the domain of the ultraviolet-unstable fixed point gir, then evolves to the low-redshift universe in the domain of ultraviolet-stable fixed point guv. We give the quantitative description of the low-redshift universe in the scaling-invariant domain of the ultraviolet-stable fixed point guv, and its deviation from the ΛCDM can be examined by low-redshift (z≲1 cosmological observations, such as supernova Type Ia.
A Multichannel Calorimetric Simultaneous Assay Platform Using a Microampere Constant-Current Looped Enthalpy Sensor Array

Directory of Open Access Journals (Sweden)

Hsien-Chin Wei

2017-02-01

Full Text Available Calorimetric biochemical measurements offer various advantages such as low waste, low cost, low sample consumption, short operating time, and labor-savings. Multichannel calorimeters can enhance the possibility of performing higher-throughput biochemical measurements. An enthalpy sensor (ES array is a key device in multichannel calorimeters. Most ES arrays use Wheatstone bridge amplifiers to condition the sensor signals, but such an approach is only suitable for null detection and low resistance sensors. To overcome these limitations, we have developed a multichannel calorimetric simultaneous assay (MCSA platform. An adjustable microampere constant-current (AMCC source was designed for exciting the ES array using a microampere current loop measurement circuit topology. The MCSA platform comprises a measurement unit, which contains a multichannel calorimeter and an automatic simultaneous injector, and a signal processing unit, which contains multiple ES signal conditioners and a data processor. This study focused on the construction of the MCSA platform; in particular, construction of the measurement circuit and calorimeter array in a single block. The performance of the platform, including current stability, temperature sensitivity and heat sensitivity, was evaluated. The sensor response time and calorimeter constants were given. The capability of the platform to detect relative enzyme activity was also demonstrated. The experimental results show that the proposed MCSA is a flexible and powerful biochemical measurement device with higher throughput than existing alternatives.
Optimal trace inequality constants for interior penalty discontinuous Galerkin discretisations of elliptic operators using arbitrary elements with non-constant Jacobians

Science.gov (United States)

Owens, A. R.; Kópházi, J.; Eaton, M. D.

2017-12-01

In this paper, a new method to numerically calculate the trace inequality constants, which arise in the calculation of penalty parameters for interior penalty discretisations of elliptic operators, is presented. These constants are provably optimal for the inequality of interest. As their calculation is based on the solution of a generalised eigenvalue problem involving the volumetric and face stiffness matrices, the method is applicable to any element type for which these matrices can be calculated, including standard finite elements and the non-uniform rational B-splines of isogeometric analysis. In particular, the presented method does not require the Jacobian of the element to be constant, and so can be applied to a much wider variety of element shapes than are currently available in the literature. Numerical results are presented for a variety of finite element and isogeometric cases. When the Jacobian is constant, it is demonstrated that the new method produces lower penalty parameters than existing methods in the literature in all cases, which translates directly into savings in the solution time of the resulting linear system. When the Jacobian is not constant, it is shown that the naive application of existing approaches can result in penalty parameters that do not guarantee coercivity of the bilinear form, and by extension, the stability of the solution. The method of manufactured solutions is applied to a model reaction-diffusion equation with a range of parameters, and it is found that using penalty parameters based on the new trace inequality constants result in better conditioned linear systems, which can be solved approximately 11% faster than those produced by the methods from the literature.
Fluorescence detection of single molecules using pulsed near-field optical excitation and time correlated photon counting

International Nuclear Information System (INIS)

Ambrose, W.P.; Goodwin, P.M.; Martin, J.C.; Keller, R.A.

1994-01-01

Pulsed excitation, time correlated single photon counting and time gated detection are used in near-field optical microscopy to enhance fluorescence images and measure the fluorescence lifetimes of single molecules of Rhodamine 6G on silica surfaces. Time gated detection is used to reject prompt scattered background and to improve the image signal to noise ratio. The excited state lifetime of a single Rhodamine 6G molecule is found to depend on the position of the near-field probe. We attribute the lifetime variations to spontaneous emission rate alterations by the fluorescence reflected from and quenching by the aluminum coated probe
FORMATION CONSTANTS AND THERMODYNAMIC ...

African Journals Online (AJOL)

KEY WORDS: Metal complexes, Schiff base ligand, Formation constant, DFT calculation ... best values for the formation constants of the proposed equilibrium model by .... to its positive charge distribution and the ligand deformation geometry.
Constrained least squares methods for estimating reaction rate constants from spectroscopic data

NARCIS (Netherlands)

Bijlsma, S.; Boelens, H.F.M.; Hoefsloot, H.C.J.; Smilde, A.K.

2002-01-01

Model errors, experimental errors and instrumental noise influence the accuracy of reaction rate constant estimates obtained from spectral data recorded in time during a chemical reaction. In order to improve the accuracy, which can be divided into the precision and bias of reaction rate constant
On renormalisation of lambda phi4 field theory in curved space-time

International Nuclear Information System (INIS)

Bunch, T.S.; Panangaden, P.

1980-01-01

An explicit renormalisation of all second-order physical processes occurring in lambdaphi 4 field theory in conformally flat space-time, including vacuum-to-vacuum processes, is performed. Although divergences dependent on the definition of the vacuum state appear in some Feynman diagrams, physical amplitudes obtained by summing all diagrams which contribute to a single physical process are independent of these divergences. Consequently, the theory remains renormalisable in curved space-time, at least to second order in lambda. Renormalisations of the mass m, the coupling constant lambda and the constant xi which couples the field to the Ricci scalar are required to make two- and four-particle creation amplitudes finite. (author)
Association constants of telluronium salts

International Nuclear Information System (INIS)

Kovach, N.A.; Rivkin, B.B.; Sadekov, T.D.; Shvajka, O.P.

1996-01-01

Association constants in acetonitrile of triphenyl telluronium salts, which are dilute electrolytes, are determined through the conductometry method. Satisfactory correlation dependence of constants of interion association and threshold molar electroconductivity on the Litvinenko-Popov constants for depositing groups is identified. 6 refs
Single-label kinase and phosphatase assays for tyrosine phosphorylation using nanosecond time-resolved fluorescence detection.

Science.gov (United States)

Sahoo, Harekrushna; Hennig, Andreas; Florea, Mara; Roth, Doris; Enderle, Thilo; Nau, Werner M

2007-12-26

The collision-induced fluorescence quenching of a 2,3-diazabicyclo[2.2.2]oct-2-ene-labeled asparagine (Dbo) by hydrogen atom abstraction from the tyrosine residue in peptide substrates was introduced as a single-labeling strategy to assay the activity of tyrosine kinases and phosphatases. The assays were tested for 12 different combinations of Dbo-labeled substrates and with the enzymes p60c-Src Src kinase, EGFR kinase, YOP protein tyrosine phosphatase, as well as acid and alkaline phosphatases, thereby demonstrating a broad application potential. The steady-state fluorescence changed by a factor of up to 7 in the course of the enzymatic reaction, which allowed for a sufficient sensitivity of continuous monitoring in steady-state experiments. The fluorescence lifetimes (and intensities) were found to be rather constant for the phosphotyrosine peptides (ca. 300 ns in aerated water), while those of the unphosphorylated peptides were as short as 40 ns (at pH 7) and 7 ns (at pH 13) as a result of intramolecular quenching. Owing to the exceptionally long fluorescence lifetime of Dbo, the assays were alternatively performed by using nanosecond time-resolved fluorescence (Nano-TRF) detection, which leads to an improved discrimination of background fluorescence and an increased sensitivity. The potential for inhibitor screening was demonstrated through the inhibition of acid and alkaline phosphatases by molybdate.
Fit of experimental points to the sum of two (or one) exponentials with background. Program for ODRA 1305 computer. Part 2: for time analysers with constant dead time after each registered pulse (AC-256 type)

International Nuclear Information System (INIS)

Drozdowicz, K.; Krynicka-Drozdowicz, E.

1979-01-01

The LAMA program (in FORTRAN 1900 language), which fits the set of decaying experimental values to the sum of the two (or one) exponentials with background, is described. The method of calculation and its accuracy and the interpretation of the program results are given. The changes and the extensions of the calculation, referred to the dead time effect taken into account for time analysers having the constant dead time after each registered pulse, are described. (author)
Optimal Rules for Single Machine Scheduling with Stochastic Breakdowns

Directory of Open Access Journals (Sweden)

Jinwei Gu

2014-01-01

Full Text Available This paper studies the problem of scheduling a set of jobs on a single machine subject to stochastic breakdowns, where jobs have to be restarted if preemptions occur because of breakdowns. The breakdown process of the machine is independent of the jobs processed on the machine. The processing times required to complete the jobs are constants if no breakdown occurs. The machine uptimes are independently and identically distributed (i.i.d. and are subject to a uniform distribution. It is proved that the Longest Processing Time first (LPT rule minimizes the expected makespan. For the large-scale problem, it is also showed that the Shortest Processing Time first (SPT rule is optimal to minimize the expected total completion times of all jobs.
High temperature elastic constant measurements: application to plutonium; Mesure des constantes elastiques a haute temperature application au plutonium

Energy Technology Data Exchange (ETDEWEB)

Bouchet, J M [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1969-03-01

We present an apparatus with which we have measured the Young's modulus and the Poisson's ratio of several compounds from the resonance frequency of cylinders in the temperature range 0 deg. C-700 deg. C. We especially studied the elastic constants of plutonium and measured for the first time to our knowledge the Young's modulus of Pu{sub {delta}} and Pu{sub {epsilon}}. E{sub {delta}} 360 deg. C = 1.6 10{sup 11} dy/cm{sup 2}; E{sub {epsilon}} 490 deg. C = 1.1 10{sup 11} dy/cm{sup 2}, {sigma}{sub {epsilon}} = 0.25 {+-} 0.03 Using our results, we have calculated the compressibility, the Debye temperature, the Grueneisen constant and the electronic specific heat of Pu{sub {epsilon}}. (author) [French] Nous decrivons un appareil qui permet de mesurer les constantes elastiques (module de Young et module de Poisson) jusqu'a 700 deg. C a partir des frequences de resonance de barreaux cylindriques. Nous avons plus specialement etudie le plutonium et determine pour la premiere fois a notre connaissance le module de Young des phases {delta} et {epsilon}: E{sub {delta}} 360 deg. C = 1.6 10{sup 11} dy/cm{sup 2}; E{sub {epsilon}} 490 deg. C = 1.1 10{sup 11} dy/cm{sup 2}, {sigma}{sub {epsilon}} = 0.25 {+-} 0.03 Nos mesures nous ont permis de calculer la compressibilite, la temperature de Debye, la constante de Gruneisen et la chaleur specifique electronique de Pu{sub {epsilon}}. (auteur)
The Newton constant and gravitational waves in some vector field adjusting mechanisms

Energy Technology Data Exchange (ETDEWEB)

Santillán, Osvaldo P. [IMAS (UBA-CONICET), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires 1428 (Argentina); Scornavacche, Marina, E-mail: firenzecita@hotmail.com, E-mail: marina.scorna@hotmail.com [Departamento de Física, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires 1428 (Argentina)

2017-10-01

At the present, there exist some Lorentz breaking scenarios which explain the smallness of the cosmological constant at the present era [1]–[2]. An important aspect to analyze is the propagation of gravitational waves and the screening or enhancement of the Newton constant G {sub N} in these models. The problem is that the Lorentz symmetry breaking terms may induce an unacceptable value of the Newton constant G {sub N} or introduce longitudinal modes in the gravitational wave propagation. Furthermore this breaking may spoil the standard dispersion relation ω= ck . In [3] the authors have presented a model suggesting that the behavior of the gravitational constant is correct for asymptotic times. In the present work, an explicit checking is made and we finally agree with these claims. Furthermore, it is suggested that the gravitational waves are also well behaved for large times. In the process, some new models with the same behavior are obtained, thus enlarging the list of possible adjustment mechanisms.
On the Luminosity Distance and the Hubble Constant

OpenAIRE

Yuri Heymann

2013-01-01

By differentiating luminosity distance with respect to time using its standard formula we ﬁnd that the peculiar velocity is a time varying velocity of light. Therefore, a new deﬁnition of the luminosity distance is provided such that the peculiar velocity is equal to c. Using this deﬁnition a Hubble constant H0 = 67.3 km s−1 Mpc−1 is obtained from supernovae data.
Statistical analysis of error rate of large-scale single flux quantum logic circuit by considering fluctuation of timing parameters

International Nuclear Information System (INIS)

Yamanashi, Yuki; Masubuchi, Kota; Yoshikawa, Nobuyuki

2016-01-01

The relationship between the timing margin and the error rate of the large-scale single flux quantum logic circuits is quantitatively investigated to establish a timing design guideline. We observed that the fluctuation in the set-up/hold time of single flux quantum logic gates caused by thermal noises is the most probable origin of the logical error of the large-scale single flux quantum circuit. The appropriate timing margin for stable operation of the large-scale logic circuit is discussed by taking the fluctuation of setup/hold time and the timing jitter in the single flux quantum circuits. As a case study, the dependence of the error rate of the 1-million-bit single flux quantum shift register on the timing margin is statistically analyzed. The result indicates that adjustment of timing margin and the bias voltage is important for stable operation of a large-scale SFQ logic circuit.

Statistical analysis of error rate of large-scale single flux quantum logic circuit by considering fluctuation of timing parameters

Energy Technology Data Exchange (ETDEWEB)

Yamanashi, Yuki, E-mail: yamanasi@ynu.ac.jp [Department of Electrical and Computer Engineering, Yokohama National University, Tokiwadai 79-5, Hodogaya-ku, Yokohama 240-8501 (Japan); Masubuchi, Kota; Yoshikawa, Nobuyuki [Department of Electrical and Computer Engineering, Yokohama National University, Tokiwadai 79-5, Hodogaya-ku, Yokohama 240-8501 (Japan)

2016-11-15

The relationship between the timing margin and the error rate of the large-scale single flux quantum logic circuits is quantitatively investigated to establish a timing design guideline. We observed that the fluctuation in the set-up/hold time of single flux quantum logic gates caused by thermal noises is the most probable origin of the logical error of the large-scale single flux quantum circuit. The appropriate timing margin for stable operation of the large-scale logic circuit is discussed by taking the fluctuation of setup/hold time and the timing jitter in the single flux quantum circuits. As a case study, the dependence of the error rate of the 1-million-bit single flux quantum shift register on the timing margin is statistically analyzed. The result indicates that adjustment of timing margin and the bias voltage is important for stable operation of a large-scale SFQ logic circuit.
8-Channel acquisition system for Time-Correlated Single-Photon Counting.

Science.gov (United States)

Antonioli, S; Miari, L; Cuccato, A; Crotti, M; Rech, I; Ghioni, M

2013-06-01

Nowadays, an increasing number of applications require high-performance analytical instruments capable to detect the temporal trend of weak and fast light signals with picosecond time resolution. The Time-Correlated Single-Photon Counting (TCSPC) technique is currently one of the preferable solutions when such critical optical signals have to be analyzed and it is fully exploited in biomedical and chemical research fields, as well as in security and space applications. Recent progress in the field of single-photon detector arrays is pushing research towards the development of high performance multichannel TCSPC systems, opening the way to modern time-resolved multi-dimensional optical analysis. In this paper we describe a new 8-channel high-performance TCSPC acquisition system, designed to be compact and versatile, to be used in modern TCSPC measurement setups. We designed a novel integrated circuit including a multichannel Time-to-Amplitude Converter with variable full-scale range, a D∕A converter, and a parallel adder stage. The latter is used to adapt each converter output to the input dynamic range of a commercial 8-channel Analog-to-Digital Converter, while the integrated DAC implements the dithering technique with as small as possible area occupation. The use of this monolithic circuit made the design of a scalable system of very small dimensions (95 × 40 mm) and low power consumption (6 W) possible. Data acquired from the TCSPC measurement are digitally processed and stored inside an FPGA (Field-Programmable Gate Array), while a USB transceiver allows real-time transmission of up to eight TCSPC histograms to a remote PC. Eventually, the experimental results demonstrate that the acquisition system performs TCSPC measurements with high conversion rate (up to 5 MHz/channel), extremely low differential nonlinearity (<0.04 peak-to-peak of the time bin width), high time resolution (down to 20 ps Full-Width Half-Maximum), and very low crosstalk between channels.
Single-molecule three-color FRET with both negligible spectral overlap and long observation time.

Directory of Open Access Journals (Sweden)

Sanghwa Lee

Full Text Available Full understanding of complex biological interactions frequently requires multi-color detection capability in doing single-molecule fluorescence resonance energy transfer (FRET experiments. Existing single-molecule three-color FRET techniques, however, suffer from severe photobleaching of Alexa 488, or its alternative dyes, and have been limitedly used for kinetics studies. In this work, we developed a single-molecule three-color FRET technique based on the Cy3-Cy5-Cy7 dye trio, thus providing enhanced observation time and improved data quality. Because the absorption spectra of three fluorophores are well separated, real-time monitoring of three FRET efficiencies was possible by incorporating the alternating laser excitation (ALEX technique both in confocal microscopy and in total-internal-reflection fluorescence (TIRF microscopy.
Varying constants, black holes, and quantum gravity

International Nuclear Information System (INIS)

Carlip, S.

2003-01-01

Tentative observations and theoretical considerations have recently led to renewed interest in models of fundamental physics in which certain 'constants' vary in time. Assuming fixed black hole mass and the standard form of the Bekenstein-Hawking entropy, Davies, Davis and Lineweaver have argued that the laws of black hole thermodynamics disfavor models in which the fundamental electric charge e changes. I show that with these assumptions, similar considerations severely constrain 'varying speed of light' models, unless we are prepared to abandon cherished assumptions about quantum gravity. Relaxation of these assumptions permits sensible theories of quantum gravity with ''varying constants,'' but also eliminates the thermodynamic constraints, though the black hole mass spectrum may still provide some restrictions on the range of allowable models
Single-Use Energy Sources and Operating Room Time for Laparoscopic Hysterectomy: A Randomized Controlled Trial.

Science.gov (United States)

Holloran-Schwartz, M Brigid; Gavard, Jeffrey A; Martin, Jared C; Blaskiewicz, Robert J; Yeung, Patrick P

2016-01-01

To compare the intraoperative direct costs of a single-use energy device with reusable energy devices during laparoscopic hysterectomy. A randomized controlled trial (Canadian Task Force Classification I). An academic hospital. Forty-six women who underwent laparoscopic hysterectomy from March 2013 to September 2013. Each patient served as her own control. One side of the uterine attachments was desiccated and transected with the single-use device (Ligasure 5-mm Blunt Tip LF1537 with the Force Triad generator). The other side was desiccated and transected with reusable bipolar forceps (RoBi 5 mm), and transected with monopolar scissors using the same Covidien Force Triad generator. The instrument approach used was randomized to the attending physician who was always on the patient's left side. Resident physicians always operated on the patient's right side and used the converse instruments of the attending physician. Start time was recorded at the utero-ovarian pedicle and end time was recorded after transection of the uterine artery on the same side. Costs included the single-use device; amortized costs of the generator, reusable instruments, and cords; cleaning and packaging of reusable instruments; and disposal of the single-use device. Operating room time was $94.14/min. We estimated that our single use-device cost $630.14 and had a total time savings of 6.7 min per case, or 3.35 min per side, which could justify the expense of the device. The single-use energy device had significant median time savings (-4.7 min per side, p energy device that both desiccates and cuts significantly reduced operating room time to justify its own cost, and it also reduced total intraoperative direct costs during laparoscopic hysterectomy in our institution. Operating room cost per minute varies between institutions and must be considered before generalizing our results. Copyright © 2016 AAGL. Published by Elsevier Inc. All rights reserved.
Effective conductivity, dielectric constant, and diffusion coefficient of digitized composite media via first-passage-time equations

International Nuclear Information System (INIS)

Torquato, S.; Kim, I.C.; Cule, D.

1999-01-01

We generalize the Brownian motion simulation method of Kim and Torquato [J. Appl. Phys. 68, 3892 (1990)] to compute the effective conductivity, dielectric constant and diffusion coefficient of digitized composite media. This is accomplished by first generalizing the first-passage-time equations to treat first-passage regions of arbitrary shape. We then develop the appropriate first-passage-time equations for digitized media: first-passage squares in two dimensions and first-passage cubes in three dimensions. A severe test case to prove the accuracy of the method is the two-phase periodic checkerboard in which conduction, for sufficiently large phase contrasts, is dominated by corners that join two conducting-phase pixels. Conventional numerical techniques (such as finite differences or elements) do not accurately capture the local fields here for reasonable grid resolution and hence lead to inaccurate estimates of the effective conductivity. By contrast, we show that our algorithm yields accurate estimates of the effective conductivity of the periodic checkerboard for widely different phase conductivities. Finally, we illustrate our method by computing the effective conductivity of the random checkerboard for a wide range of volume fractions and several phase contrast ratios. These results always lie within rigorous four-point bounds on the effective conductivity. copyright 1999 American Institute of Physics
An adaptive-binning method for generating constant-uncertainty/constant-significance light curves with Fermi-LAT data

International Nuclear Information System (INIS)

Lott, B.; Escande, L.; Larsson, S.; Ballet, J.

2012-01-01

Here, we present a method enabling the creation of constant-uncertainty/constant-significance light curves with the data of the Fermi-Large Area Telescope (LAT). The adaptive-binning method enables more information to be encapsulated within the light curve than with the fixed-binning method. Although primarily developed for blazar studies, it can be applied to any sources. Furthermore, this method allows the starting and ending times of each interval to be calculated in a simple and quick way during a first step. The reported mean flux and spectral index (assuming the spectrum is a power-law distribution) in the interval are calculated via the standard LAT analysis during a second step. In the absence of major caveats associated with this method Monte-Carlo simulations have been established. We present the performance of this method in determining duty cycles as well as power-density spectra relative to the traditional fixed-binning method.
Stable single helical C- and I-chains inside single-walled carbon nanotubes

International Nuclear Information System (INIS)

Yao Z; Li Y; Jing X D; Meng F S; Zhao X; Li J H; Qiu Z Y; Yuan Q; Wang W X; Bi L; Liu H; Zhang Y P; Liu C J; Zheng S P; Liu B B

2016-01-01

The helicity of stable single helical carbon chains and iodine chains inside single-walled carbon nanotubes (SWCNTs) is studied by calculating the systematic van der Waals interaction energy. The results show that the optimal helical radius increases linearly with increasing tube radius, which produces a constant separation between the chain structure and the tube wall. The helical angle exhibits a ladder-like decrease with increasing tube radius, indicating that a large tube can produce a small helicity in the helical structures. (paper)
Nonadiabatic dynamics of electron transfer in solution: Explicit and implicit solvent treatments that include multiple relaxation time scales

International Nuclear Information System (INIS)

Schwerdtfeger, Christine A.; Soudackov, Alexander V.; Hammes-Schiffer, Sharon

2014-01-01

The development of efficient theoretical methods for describing electron transfer (ET) reactions in condensed phases is important for a variety of chemical and biological applications. Previously, dynamical dielectric continuum theory was used to derive Langevin equations for a single collective solvent coordinate describing ET in a polar solvent. In this theory, the parameters are directly related to the physical properties of the system and can be determined from experimental data or explicit molecular dynamics simulations. Herein, we combine these Langevin equations with surface hopping nonadiabatic dynamics methods to calculate the rate constants for thermal ET reactions in polar solvents for a wide range of electronic couplings and reaction free energies. Comparison of explicit and implicit solvent calculations illustrates that the mapping from explicit to implicit solvent models is valid even for solvents exhibiting complex relaxation behavior with multiple relaxation time scales and a short-time inertial response. The rate constants calculated for implicit solvent models with a single solvent relaxation time scale corresponding to water, acetonitrile, and methanol agree well with analytical theories in the Golden rule and solvent-controlled regimes, as well as in the intermediate regime. The implicit solvent models with two relaxation time scales are in qualitative agreement with the analytical theories but quantitatively overestimate the rate constants compared to these theories. Analysis of these simulations elucidates the importance of multiple relaxation time scales and the inertial component of the solvent response, as well as potential shortcomings of the analytical theories based on single time scale solvent relaxation models. This implicit solvent approach will enable the simulation of a wide range of ET reactions via the stochastic dynamics of a single collective solvent coordinate with parameters that are relevant to experimentally accessible
The Turning Point for the Recent Acceleration of the Universe with a Cosmological Constant

Directory of Open Access Journals (Sweden)

Zhang T. X.

2012-04-01

Full Text Available The turning point and acceleration expansion of the universe are investigated according to the standard cosmological theory with a non-zero cosmological constant. Choosing the Hubble constant H 0 , the radius of the present universe R 0 , and the density parameter in matter Ω M , 0 as three independent parameters, we have analytically examined the other properties of the universe such as the density parameter in dark energy, the cosmologi- cal constant, the mass of the universe, the turning point redshift, the age of the present universe, and the time-dependent radius, expansion rate, velocity, and acceleration pa- rameter of the universe. It is shown that the turning point redshift is only dependent of the density parameter in matter, not explicitly on the Hubble constant and the radius of the present universe. The universe turned its expansion from past deceleration to recent acceleration at the moment when its size was about 3 / 5 of the present size if the density parameter in matter is about 0.3 (or the turning point redshift is 0.67. The expansion rate is very large in the early period and decreases with time to approach the Hubble constant at the present time. The expansion velocity exceeds the light speed in the early period. It decreases to the minimum at the turning point and then increases with time. The minimum and present expansion velocities are determined with the independent parameters. The solution of time-dependent radius shows the universe expands all the time. The universe with a larger present radius, smaller Hubble constant, and / or smaller density parameter in matter is elder. The universe with smaller density parameter in matter accelerates recently in a larger rate but less than unity.
Reusable single-port access device shortens operative time and reduces operative costs.

Science.gov (United States)

Shussman, Noam; Kedar, Asaf; Elazary, Ram; Abu Gazala, Mahmoud; Rivkind, Avraham I; Mintz, Yoav

2014-06-01

In recent years, single-port laparoscopy (SPL) has become an attractive approach for performing surgical procedures. The pitfalls of this approach are technical and financial. Financial concerns are due to the increased cost of dedicated devices and prolonged operating room time. Our aim was to calculate the cost of SPL using a reusable port and instruments in order to evaluate the cost difference between this approach to SPL using the available disposable ports and standard laparoscopy. We performed 22 laparoscopic procedures via the SPL approach using a reusable single-port access system and reusable laparoscopic instruments. These included 17 cholecystectomies and five other procedures. Operative time, postoperative length of stay (LOS) and complications were prospectively recorded and were compared with similar data from our SPL database. Student's t test was used for statistical analysis. SPL was successfully performed in all cases. Mean operative time for cholecystectomy was 72 min (range 40-116). Postoperative LOS was not changed from our standard protocols and was 1.1 days for cholecystectomy. The postoperative course was within normal limits for all patients and perioperative morbidity was recorded. Both operative time and length of hospital stay were shorter for the 17 patients who underwent cholecystectomy using a reusable port than for the matched previous 17 SPL cholecystectomies we performed (p cost difference. Operating with a reusable port ended up with an average cost savings of US$388 compared with using disposable ports, and US$240 compared with standard laparoscopy. Single-port laparoscopic surgery is a technically challenging and expensive surgical approach. Financial concerns among others have been advocated against this approach; however, we demonstrate herein that using a reusable port and instruments reduces operative time and overall operative costs, even beyond the cost of standard laparoscopy.
In-depth study of single photon time resolution for the Philips digital silicon photomultiplier

International Nuclear Information System (INIS)

Liu, Z.; Pizzichemi, M.; Ghezzi, A.; Paganoni, M.; Gundacker, S.; Auffray, E.; Lecoq, P.

2016-01-01

The digital silicon photomultiplier (SiPM) has been commercialised by Philips as an innovative technology compared to analog silicon photomultiplier devices. The Philips digital SiPM, has a pair of time to digital converters (TDCs) connected to 12800 single photon avalanche diodes (SPADs). Detailed measurements were performed to understand the low photon time response of the Philips digital SiPM. The single photon time resolution (SPTR) of every single SPAD in a pixel consisting of 3200 SPADs was measured and an average value of 85 ps full width at half maximum (FWHM) was observed. Each SPAD sends the signal to the TDC with different signal propagation time, resulting in a so called trigger network skew. This distribution of the trigger network skew for a pixel (3200 SPADs) has been measured and a variation of 50 ps FWHM was extracted. The SPTR of the whole pixel is the combination of SPAD jitter, trigger network skew, and the SPAD non-uniformity. The SPTR of a complete pixel was 103 ps FWHM at 3.3 V above breakdown voltage. Further, the effect of the crosstalk at a low photon level has been studied, with the two photon time resolution degrading if the events are a combination of detected (true) photons and crosstalk events. Finally, the time response to multiple photons was investigated.
QSARs for phenols and phenolates: oxidation potential as a predictor of reaction rate constants with photochemically produced oxidants.

Science.gov (United States)

Arnold, William A; Oueis, Yan; O'Connor, Meghan; Rinaman, Johanna E; Taggart, Miranda G; McCarthy, Rachel E; Foster, Kimberley A; Latch, Douglas E

2017-03-22

Quantitative structure-activity relationships (QSARs) for prediction of the reaction rate constants of phenols and phenolates with three photochemically produced oxidants, singlet oxygen, carbonate radical, and triplet excited state sensitizers/organic matter, are developed. The predictive variable is the one-electron oxidation potential (E 1 ), which is calculated for each species using density functional theory. The reaction rate constants are obtained from the literature, and for singlet oxygen, are augmented with new experimental data. Calculated E 1 values have a mean unsigned error compared to literature values of 0.04-0.06 V. For singlet oxygen, a single linear QSAR that includes both phenols and phenolates is developed that predicts experimental rate constants, on average, to within a factor of three. Predictions for only 6 out of 87 compounds are off by more than a factor of 10. A more limited data set for carbonate radical reactions with phenols and phenolates also gives a single linear QSAR with prediction of rate constant being accurate to within a factor of three. The data for the reactions of phenols with triplet state sensitizers demonstrate that two sensitizers, 2-acetonaphthone and methylene blue, most closely predict the reactivity trend of triplet excited state organic matter with phenols. Using sensitizers with stronger reduction potentials could lead to overestimation of rate constants and thus underestimation of phenolic pollutant persistence.
1.28 Tbit/s/channel single-polarization DQPSK transmission over 525 km using ultrafast time-domain optical Fourier transformation

DEFF Research Database (Denmark)

Guan, P.; Mulvad, Hans Christian Hansen; Tomiyama, Y.

2010-01-01

A single-channel 1.28 Tbit/s transmission over 525 km is demonstrated for the first time with a single-polarization DQPSK signal. Ultrafast time-domain optical Fourier transformation is successfully applied to DQPSK signals and results in improved performance and increased system margin.......A single-channel 1.28 Tbit/s transmission over 525 km is demonstrated for the first time with a single-polarization DQPSK signal. Ultrafast time-domain optical Fourier transformation is successfully applied to DQPSK signals and results in improved performance and increased system margin....
Experimental determination of magnetocrystalline anisotropy constants and saturation magnetostriction constants of NiZn and NiZnCo ferrites intended to be used for antennas miniaturization

Energy Technology Data Exchange (ETDEWEB)

Mattei, Jean-Luc, E-mail: mattei@univ-brest.fr [Lab-STICC, Université de Bretagne Occidentale, CS 93837, 6 Avenue Le Gorgeu, 29238 Brest Cedex 3 (France); Le Guen, Emmanuel, E-mail: emmanuel.leguen@hotmail.fr [Lab-STICC, Université de Bretagne Occidentale, CS 93837, 6 Avenue Le Gorgeu, 29238 Brest Cedex 3 (France); IETR, Université de Rennes 1, 263 Avenue General Leclerc, 35042 Rennes Cedex (France); Chevalier, Alexis, E-mail: alexis.chevalier@univ-brest.fr [Lab-STICC, Université de Bretagne Occidentale, CS 93837, 6 Avenue Le Gorgeu, 29238 Brest Cedex 3 (France); Tarot, Anne-Claude, E-mail: anne-claude.tarot@univ-rennes1.fr [IETR, Université de Rennes 1, 263 Avenue General Leclerc, 35042 Rennes Cedex (France)

2015-01-15

This study investigates the magnetocrystalline anisotropy constants (K{sub 1}) and the saturation magnetostriction constants (λ{sub S}) of Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (NiZn) and Ni{sub 0.8−x}Zn{sub x}Co{sub 0.2}Fe{sub 1.98}O{sub 4−δ} (NiZnCo) ferrites intended to be used for antenna downsizing. Composite materials constituted of soft ferrite nanosized particles (NiZn or NiZnCo ferrites) embedded in an epoxy matrix are realized. Measurements of their magnetic permeability in the frequency range of 200 MHz–6 GHz are performed. The influence of compressive stress (in the range of 32–96 MPa) on their Ferrimagnetic Resonance (FMR) is demonstrated. An analytical modeling of stress-induced FMR changes is proposed that allows simultaneous determinations of the Natural Ferrimagnetic Resonance (NFMR, F{sub 0}), K{sub 1} and λ{sub S} of Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} and Ni{sub 0.8−x}Zn{sub x}Co{sub 0.2}Fe{sub 1.98}O{sub 4−δ} ferrites. The obtained results for NiZn ferrites are in agreement with literature data, validating both the experimental process and the proposed modeling of the stress-induced FMR changes. Regarding NiZnCo ferrites, extended data on K{sub 1} and λ{sub S} are presented for the first time. Increasing zinc content (x) induces a spin disorder that reduces in a same time K{sub 1} and the magnetization at saturation M{sub S}. The rapid variation of K{sub 1}(x) is related to that of the magnetization M{sub S}(x) through a power law. The single-ion anisotropy model allows a satisfactory interpretation of K{sub 1} dependence on zinc content. The unexpected low values of λ{sub S} got for NiZnCo ferrites, compared to those got for NiZn ferrites, are also discussed. Application of compressive stress lowers noticeably magnetic losses of Ni{sub 0.6}Zn{sub 0.2}Co{sub 0.2}Fe{sub 1.98}O{sub 4−δ} at given frequency, thereby enhancing the ability of this spinel ferrite to be used as a substrate in the aim of antenna
Constant rate natural gas production from a well in a hydrate reservoir

International Nuclear Information System (INIS)

Ji Chuang; Ahmadi, Goodarz; Smith, Duane H.

2003-01-01

Using a computational model, production of natural gas at a constant rate from a well that is drilled into a confined methane hydrate reservoir is studied. It is assumed that the pores in the reservoir are partially saturated with hydrate. A linearized model for an axisymmetric condition with a fixed well output is used in the analysis. For different reservoir temperatures and various well outputs, time evolutions of temperature and pressure profiles, as well as the gas flow rate in the hydrate zone and the gas region, are evaluated. The distance of the decomposition front from the well as a function of time is also computed. It is shown that to maintain a constant natural gas production rate, the well pressure must be decreased with time. A constant low production rate can be sustained for a long duration of time, but a high production rate demands unrealistically low pressure at the well after a relatively short production time. The simulation results show that the process of natural gas production in a hydrate reservoir is a sensitive function of reservoir temperature and hydrate zone permeability
Superalgebras with Grassmann algebra-valued structure constants from superfields

International Nuclear Information System (INIS)

Azcarraga, J.A. de; Lukierski, J.

1987-05-01

We introduce generalized Lie algebras and superalgebras with generators and structure constants taking values in a Grassmann algebra. Such algebraic structures describe the equal time algebras in the superfield formalism. As an example we consider the equal time commutators and anticommutators among bilinears made out of the D=1 quantum superfields describing the supersymmetric harmonic oscillator. (author). 10 refs
Plasmon resonance in single- and double-layer CVD graphene nanoribbons

DEFF Research Database (Denmark)

Wang, Di; Emani, Naresh K.; Chung, Ting Fung

2015-01-01

Dynamic tunability of the plasmonic resonance in graphene nanoribbons is desirable in the near-infrared. We demonstrated a constant blue shift of plasmonic resonances in double-layer graphene nanoribbons with respect to single-layer graphene nanoribbons. © OSA 2015.......Dynamic tunability of the plasmonic resonance in graphene nanoribbons is desirable in the near-infrared. We demonstrated a constant blue shift of plasmonic resonances in double-layer graphene nanoribbons with respect to single-layer graphene nanoribbons. © OSA 2015....
Influence of Poisson's ratio variation on lateral spring constant of atomic force microscopy cantilevers

International Nuclear Information System (INIS)

Yeh, M.-K.; Tai, N.-Ha; Chen, B.-Y.

2008-01-01

Atomic force microscopy (AFM) can be used to measure the surface morphologies and the mechanical properties of nanostructures. The force acting on the AFM cantilever can be obtained by multiplying the spring constant of AFM cantilever and the corresponding deformation. To improve the accuracy of force experiments, the spring constant of AFM cantilever must be calibrated carefully. Many methods, such as theoretical equations, the finite element method, and the use of reference cantilever, were reported to obtain the spring constant of AFM cantilevers. For the cantilever made of single crystal, the Poisson's ratio varies with different cantilever-crystal angles. In this paper, the influences of Poisson's ratio variation on the lateral spring constant and axial spring constant of rectangular and V-shaped AFM cantilevers, with different tilt angles and normal forces, were investigated by the finite element analysis. When the cantilever's tilt angle is 20 deg. and the Poisson's ratio varies from 0.02 to 0.4, the finite element results show that the lateral spring constants decrease 11.75% for the rectangular cantilever with 1 μN landing force and decrease 18.60% for the V-shaped cantilever with 50 nN landing force, respectively. The influence of Poisson's ratio variation on axial spring constant is less than 3% for both rectangular and V-shaped cantilevers. As the tilt angle increases, the axial spring constants for rectangular and V-shaped cantilevers decrease substantially. The results obtained can be used to improve the accuracy of the lateral force measurement when using atomic force microscopy
Influence of the cosmological constant on gravitational lensing in small systems

International Nuclear Information System (INIS)

Sereno, Mauro

2008-01-01

The cosmological constant Λ affects gravitational lensing phenomena. The contribution of Λ to the observable angular positions of multiple images and to their amplification and time delay is here computed through a study of the weak deflection limit of the equations of motion in the Schwarzschild-de Sitter metric. Because of Λ the unresolved images are slightly demagnified, the radius of the Einstein ring decreases, and the time delay increases. The effect is however negligible for near lenses. In the case of a null cosmological constant, we provide some updated results on lensing by a Schwarzschild black hole

Digital Generation of Noise-Signals with Arbitrary Constant or Time-Varying Spectra (A noise generation software package and its application)

CERN Document Server

Tückmantel, Joachim

2008-01-01

Artificial creation of arbitrary noise signals is used in accelerator physics to reproduce a measured perturbation spectrum for simulations but also to generate real-time shaped noise spectra for controlled emittance blow-up giving tailored properties to the final bunch shape. It is demonstrated here how one can produce numerically what is, for all practical purposes, an unlimited quantity of non-periodic noise data having any predefined spectral density. This spectral density may be constant or varying with time. The noise output never repeats and has excellent statistical properties, important for very long-term applications. It is difficult to obtain such flexibility and spectral cleanliness using analogue techniques. This algorithm was applied both in computer simulations of bunch behaviour in the presence of RF noise in the PS, SPS and LHC and also to generate real-time noise, tracking the synchrotron frequency change during the energy ramp of the SPS and producing controlled longitudinal emittance blow-...
Change of the equivalent circuit constants accompanied by the degradation and recovery of efficiency on a-Si solar cells; A-Si taiyo denchi no koritsu no rekka to kaifuku ni tomonau toka kairo teisu no henka

Energy Technology Data Exchange (ETDEWEB)

Takahisa, K; Kojima, T; Nakamura, K; Koyanagi, T; Yanagisawa, T [Electrotechnical Laboratory, Tsukuba (Japan)

1997-11-25

Investigations were given on how the equivalent circuit constants change when efficiency of amorphous silicon solar cells changes with time in light degradation and temperature recovery. In the experiment, light irradiation tests under a constant temperature and light intensity condition, followed by recovery tests under a constant temperature and constant weak light intensity or constant temperature condition were repeated continuously. According to the result of an experiment on single layer type cells, the change in each equivalent circuit constant in association with degradation in efficiency and file factor and variation in recovery is reversible mostly. However, a slightly irreversible component was recognized only in the initial degradation process in series resistance and diode factor values. With regard to stacked cells, it was suggested that the main players to determine cell characteristics during the processes of deterioration and recovery take turns among the three layers as follows: the shape of the time-based change in the efficiency comes different and is not saturating; as the efficiency decreases, the extent of the change increases in the diode factor and series resistance; and the path the deterioration takes differs from that the recovery takes. 2 refs., 12 figs.
Single molecule diffusion and the solution of the spherically symmetric residence time equation.

Science.gov (United States)

Agmon, Noam

2011-06-16

The residence time of a single dye molecule diffusing within a laser spot is propotional to the total number of photons emitted by it. With this application in mind, we solve the spherically symmetric "residence time equation" (RTE) to obtain the solution for the Laplace transform of the mean residence time (MRT) within a d-dimensional ball, as a function of the initial location of the particle and the observation time. The solutions for initial conditions of potential experimental interest, starting in the center, on the surface or uniformly within the ball, are explicitly presented. Special cases for dimensions 1, 2, and 3 are obtained, which can be Laplace inverted analytically for d = 1 and 3. In addition, the analytic short- and long-time asymptotic behaviors of the MRT are derived and compared with the exact solutions for d = 1, 2, and 3. As a demonstration of the simplification afforded by the RTE, the Appendix obtains the residence time distribution by solving the Feynman-Kac equation, from which the MRT is obtained by differentiation. Single-molecule diffusion experiments could be devised to test the results for the MRT presented in this work. © 2011 American Chemical Society
Reduction in the ionospheric error for a single-frequency GPS timing solution using tomography

Directory of Open Access Journals (Sweden)

Cathryn N. Mitchell

2009-06-01

Full Text Available
Times;">Abstract

Times;">Single-frequency Global Positioning System (GPS receivers do not accurately compensate for the ionospheric delay imposed upon a GPS signal. They rely upon models to compensate for the ionosphere. This delay compensation can be improved by measuring it directly with a dual-frequency receiver, or by monitoring the ionosphere using real-time maps. This investigation uses a 4D tomographic algorithm, Multi Instrument Data Analysis System (MIDAS, to correct for the ionospheric delay and compares the results to existing single and dualfrequency techniques. Maps of the ionospheric electron density, across Europe, are produced by using data collected from a fixed network of dual-frequency GPS receivers. Single-frequency pseudorange observations are corrected by using the maps to find the excess propagation delay on the GPS L1 signals. Days during the solar maximum year 2002 and the October 2003 storm have been chosen to display results when the ionospheric delays are large and variable. Results that improve upon the use of existing ionospheric models are achieved by applying MIDAS to fixed and mobile single-frequency GPS timing solutions. The approach offers the potential for corrections to be broadcast over a local region, or provided via the internet and allows timing accuracies to within 10 ns to be achieved.
Fixation times in evolutionary games under weak selection

International Nuclear Information System (INIS)

Altrock, Philipp M; Traulsen, Arne

2009-01-01

In evolutionary game dynamics, reproductive success increases with the performance in an evolutionary game. If strategy A performs better than strategy B, strategy A will spread in the population. Under stochastic dynamics, a single mutant will sooner or later take over the entire population or go extinct. We analyze the mean exit times (or average fixation times) associated with this process. We show analytically that these times depend on the payoff matrix of the game in an amazingly simple way under weak selection, i.e. strong stochasticity: the payoff difference Δπ is a linear function of the number of A individuals i, Δπ=u i+v. The unconditional mean exit time depends only on the constant term v. Given that a single A mutant takes over the population, the corresponding conditional mean exit time depends only on the density dependent term u. We demonstrate this finding for two commonly applied microscopic evolutionary processes.
Timing Solution and Single-pulse Properties for Eight Rotating Radio Transients

Energy Technology Data Exchange (ETDEWEB)

Cui, B.-Y.; McLaughlin, M. A. [Department of Physics and Astronomy West Virginia University Morgantown, WV 26506 (United States); Boyles, J. [Department of Physics and Astronomy West Kentucky University Bowling Green, KY 42101 (United States); Palliyaguru, N. [Physics and Astronomy Department Texas Tech University Lubbock, TX 79409-1051 (United States)

2017-05-01

Rotating radio transients (RRATs), loosely defined as objects that are discovered through only their single pulses, are sporadic pulsars that have a wide range of emission properties. For many of them, we must measure their periods and determine timing solutions relying on the timing of their individual pulses, while some of the less sporadic RRATs can be timed by using folding techniques as we do for other pulsars. Here, based on Parkes and Green Bank Telescope (GBT) observations, we introduce our results on eight RRATs including their timing-derived rotation parameters, positions, and dispersion measures (DMs), along with a comparison of the spin-down properties of RRATs and normal pulsars. Using data for 24 RRATs, we find that their period derivatives are generally larger than those of normal pulsars, independent of any intrinsic correlation with period, indicating that RRATs’ highly sporadic emission may be associated with intrinsically larger magnetic fields. We carry out Lomb–Scargle tests to search for periodicities in RRATs’ pulse detection times with long timescales. Periodicities are detected for all targets, with significant candidates of roughly 3.4 hr for PSR J1623−0841 and 0.7 hr for PSR J1839−0141. We also analyze their single-pulse amplitude distributions, finding that log-normal distributions provide the best fits, as is the case for most pulsars. However, several RRATs exhibit power-law tails, as seen for pulsars emitting giant pulses. This, along with consideration of the selection effects against the detection of weak pulses, imply that RRAT pulses generally represent the tail of a normal intensity distribution.
Timing Solution and Single-pulse Properties for Eight Rotating Radio Transients

Science.gov (United States)

Cui, B.-Y.; Boyles, J.; McLaughlin, M. A.; Palliyaguru, N.

2017-05-01

Rotating radio transients (RRATs), loosely defined as objects that are discovered through only their single pulses, are sporadic pulsars that have a wide range of emission properties. For many of them, we must measure their periods and determine timing solutions relying on the timing of their individual pulses, while some of the less sporadic RRATs can be timed by using folding techniques as we do for other pulsars. Here, based on Parkes and Green Bank Telescope (GBT) observations, we introduce our results on eight RRATs including their timing-derived rotation parameters, positions, and dispersion measures (DMs), along with a comparison of the spin-down properties of RRATs and normal pulsars. Using data for 24 RRATs, we find that their period derivatives are generally larger than those of normal pulsars, independent of any intrinsic correlation with period, indicating that RRATs’ highly sporadic emission may be associated with intrinsically larger magnetic fields. We carry out Lomb-Scargle tests to search for periodicities in RRATs’ pulse detection times with long timescales. Periodicities are detected for all targets, with significant candidates of roughly 3.4 hr for PSR J1623-0841 and 0.7 hr for PSR J1839-0141. We also analyze their single-pulse amplitude distributions, finding that log-normal distributions provide the best fits, as is the case for most pulsars. However, several RRATs exhibit power-law tails, as seen for pulsars emitting giant pulses. This, along with consideration of the selection effects against the detection of weak pulses, imply that RRAT pulses generally represent the tail of a normal intensity distribution.
Time-Darts: A Data Structure for Verification of Closed Timed Automata

Directory of Open Access Journals (Sweden)

Jiří Srba

2012-11-01

Full Text Available Symbolic data structures for model checking timed systems have been subject to a significant research, with Difference Bound Matrices (DBMs still being the preferred data structure in several mature verification tools. In comparison, discretization offers an easy alternative, with all operations having linear-time complexity in the number of clocks, and yet valid for a large class of closed systems. Unfortunately, fine-grained discretization causes itself a state-space explosion. We introduce a new data structure called time-darts for the symbolic representation of state-spaces of timed automata. Compared with the complete discretization, a single time-dart allows to represent an arbitrary large set of states, yet the time complexity of operations on time-darts remain linear in the number of clocks. We prove the correctness of the suggested reachability algorithm and perform several experiments in order to compare the performance of time-darts and the complete discretization. The main conclusion is that in all our experiments the time-dart method outperforms the complete discretization and it scales significantly better for models with larger constants.
Optical constants of anodic aluminum oxide films formed in oxalic acid solution

Energy Technology Data Exchange (ETDEWEB)

Wang Jian [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Wang Chengwei [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)], E-mail: cwwang@nwnu.edu.cn; Li Yan [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Liu Weimin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2008-09-01

The anodic aluminum oxide (AAO) films with highly ordered nanopore arrays were prepared in oxalic acid solution under different anodizing voltage and time, its surface and cross section appearances were characterized by using field emission scanning electron microscopy, the transmission spectra with the interference fringes were measured at normal incidence over the wavelength range 200 to 2500 nm. Then the modified Swanepoel method was used for the determination of the optical constants and thickness of the free standing AAO films. The results indicate that the refractive index increases with the increase of anodizing voltage and the decrease of anodizing time, which is mainly due to the content of Al{sub 2}O{sub 3} with octahedron increases in the AAO films. The dispersion of the refractive index is discussed in terms of the single-oscillator Wemple-DiDomenico model, and the energy dependence of the absorption coefficient can be described using the direct transition model proposed by Tauc. Likewise, the optical energy gap E{sub g} is derived from Tauc's extrapolation, and E{sub g} increases from 4.178 to 4.256 eV with the anodizing voltage, but is weakly dependent on anodizing time. All the results are self-consistent in the paper.
Convergence analysis of Chauvin's PCA learning algorithm with a constant learning rate

International Nuclear Information System (INIS)

Lv Jiancheng; Yi Zhang

2007-01-01

The convergence of Chauvin's PCA learning algorithm with a constant learning rate is studied in this paper by using a DDT method (deterministic discrete-time system method). Different from the DCT method (deterministic continuous-time system method), the DDT method does not require that the learning rate converges to zero. An invariant set of Chauvin's algorithm with a constant learning rate is obtained so that the non-divergence of this algorithm can be guaranteed. Rigorous mathematic proofs are provided to prove the local convergence of this algorithm
The thermal response of a homogeneous slab to a constant heat flux

Energy Technology Data Exchange (ETDEWEB)

Bunn, J.P.

1983-01-01

An approximate solution of the one-dimensional heat flow equation for a homogeneous slab subject to a constant heat flux at its inner face and bounded at its outer face by a surface resistance to a medium at constant temperature is presented. This solution is used to find the temperature of the inner face as a function of time. It is also used to investigate the approach to steady state enabling the time required to reach a given percentage of the steady state temperature to be calculated.
A consistent set of thermodynamic constants for americium (III) species with hydroxyl and carbonate

International Nuclear Information System (INIS)

Kerrisk, J.F.; Silva, R.J.

1986-01-01

A consistent set of thermodynamic constants for aqueous species, and compounds of Am(III) with hydroxyl and carbonate ligands has been developed. The procedure used to develop these constants involved establishing a value for one formation constant at a time in a sequential order, starting with the hydrolysis products and hydroxide solids, and then proceeding to carbonate species. The EQ3NR chemical-equilibrium model was used to test the constants developed. These constants are consistent with most of the experimental data that form their basis; however, considerable uncertainty still exists in some aspects of the Am(III) data
Advances in constant-velocity Moessbauer instrumentation

International Nuclear Information System (INIS)

Veiga, A.; Martinez, N.; Zelis, P. Mendoza; Pasquevich, G. A.; Sanchez, F. H.

2006-01-01

A prototype of a programmable constant-velocity scaler is presented. This instrument allows the acquisition of partial Moessbauer spectra in selected energy regions using standard drivers and transducers. It can be fully operated by a remote application, thus data acquisition can be automated. The instrument consists of a programmable counter and a constant-velocity reference. The reference waveform generator is amplitude modulated with 13-bit resolution, and is programmable in a wide range of frequencies and waveforms in order to optimize the performance of the transducer. The counter is compatible with most standard SCA, and is configured as a rate-meter that provides counts per selectable time slice at the programmed velocity. As a demonstration of the instrument applications, a partial Moessbauer spectrum of a natural iron foil was taken. Only positive energies were studied in 512 channels, accumulating 20 s per channel. A line width of 0.20 mm/s was achieved, performing with an efficiency of 80%.
Highly polarized single-c-domain single-crystal Pb(Mn,Nb)O(3)-PZT thin films.

Science.gov (United States)

Wasa, Kiyotaka; Adachi, Hideaki; Nishida, Ken; Yamamoto, Takashi; Matsushima, Tomoaki; Kanno, Isaku; Kotera, Hidetoshi

2012-01-01

In-plane unstrained single-c-domain/single-crystal thin films of PZT-based ternary ferroelectric perovskite, ξPb(Mn,Nb)O3-(1 - ξ)PZT, were grown on SrRuO(3)/Pt/MgO substrates using magnetron sputtering followed by quenching. The sputtered unstrained thin films exhibit unique ferroelectric properties: high coercive field, Ec > 180 kV/cm, large remanent polarization, P(r) = 100 μC/cm(2), small relative dielectric constants, ε* = 100 to 150, high Curie temperature, Tc = ~600 °C, and bulk-like large transverse piezoelectric constants, e31,f = -12.0 C/m(2) for PZT(48/52) at ξ = 0.06. The unstrained thin films are an ideal structure to extract the bulk ferroelectric properties. Their micro-structures and ferroelectric properties are discussed in relation to the potential applications for piezoelectric MEMS. © 2012 IEEE
Constant curvature algebras and higher spin action generating functions

International Nuclear Information System (INIS)

Hallowell, K.; Waldron, A.

2005-01-01

The algebra of differential geometry operations on symmetric tensors over constant curvature manifolds forms a novel deformation of the sl(2,R)-bar R 2 Lie algebra. We present a simple calculus for calculations in its universal enveloping algebra. As an application, we derive generating functions for the actions and gauge invariances of massive, partially massless and massless (for both Bose and Fermi statistics) higher spins on constant curvature backgrounds. These are formulated in terms of a minimal set of covariant, unconstrained, fields rather than towers of auxiliary fields. Partially massless gauge transformations are shown to arise as degeneracies of the flat, massless gauge transformation in one dimension higher. Moreover, our results and calculus offer a considerable simplification over existing techniques for handling higher spins. In particular, we show how theories of arbitrary spin in dimension d can be rewritten in terms of a single scalar field in dimension 2d where the d additional dimensions correspond to coordinate differentials. We also develop an analogous framework for spinor-tensor fields in terms of the corresponding superalgebra
Induced cosmological constant in braneworlds with warped internal spaces

International Nuclear Information System (INIS)

Saharian, Aram A.

2006-01-01

We investigate the vacuum energy density induced by quantum fluctuations of a bulk scalar field with general curvature coupling parameter on two codimension one parallel branes in a (D + 1)-dimensional background spacetime AdS D1+1 x Σ with a warped internal space Σ. It is assumed that on the branes the field obeys Robin boundary conditions. Using the generalized zeta function technique in combination with contour integral representations, the surface energies on the branes are presented in the form of the sums of single brane and second brane induced parts. For the geometry of a single brane both regions, on the left (L-region) and on the right (R-region), of the brane are considered. The surface densities for separate L- and R-regions contain pole and finite contributions. For an infinitely thin brane taking these regions together, in odd spatial dimensions the pole parts cancel and the total surface energy is finite. The parts in the surface densities generated by the presence of the second brane are finite for all nonzero values of the interbrane separation. The contribution of the Kaluza-Klein modes along Σ is investigated in various limiting cases. It is shown that for large distances between the branes the induced surface densities give rise to an exponentially suppressed cosmological constant on the brane. In the higher dimensional generalization of the Randall-Sundrum braneworld model, for the interbrane distances solving the hierarchy problem, the cosmological constant generated on the visible brane is of the right order of magnitude with the value suggested by the cosmological observations. (author)
Constant displacement rate testing at elevated temperatures

International Nuclear Information System (INIS)

Pepe, J.J.; Gonyea, D.C.

1989-01-01

A short time test has been developed which is capable of determining the long time notch sensitivity tendencies of CrMoV rotor forging materials. This test is based on Constant Displacement Rate (CDR) testing of a specific notch bar specimen at 1200 0 F at 2 mils/in/hour displacement rate. These data were correlated to conventional smooth and notch bar rupture behavior for a series of CrMoV materials with varying long time ductility tendencies. The purpose of this paper is to describe the details of this new test procedure and some of the relevant mechanics of material information generated during its development
Proceedings of the workshop: the solar constant and the Earth's atmosphere

International Nuclear Information System (INIS)

Zirin, H.; Moore, R.L.; Walter, J.

1976-01-01

The solar constant has long been a fundamental quantity in astrophysics, but as with many fundamental quantities, interest in its exact value or its variation has not been great over the last decade. This was particularly due to the fact that most models of stars indicated that their luminosity should be quite constant, varying only over nuclear burning times of hundreds of millions of years. Thus, after the pioneering work of Abbott, it has been more a subject of interest for atmospheric scientists who needed to know the exact inputs to the Earth's atmosphere. In recent years however, the celebrated problem of the missing solar neutrinos has brought into question the theories of stellar structure, and the solar constant is again being thought about. Standard solar models predict a lower solar constant in the past, 75% of the present, 4x10 9 years ago and a virtually constant value over short time scales (10 7 years). However, the lack of observed neutrinos predicted by this model suggests that the interior of the Sun is not really understood, which means that solar constant variations cannot be ruled out on the basis of the theory of stellar interiors. Measurement of the planets, the old Smithsonian measurements, and other data suggest that the Sun cannot have varied more than a few percent over the past hundred years, but some of the measurements even suggest small variation of the order of a percent. On the other hand, in the important near ultraviolet region, there is evidence for some variation in the 2700-3100 A region and up to 50% variation below 1600 A, dependent on solar activity. (Auth.)
Study on the ratio of signal to noise for single photon resolution time spectrometer

International Nuclear Information System (INIS)

Wang Zhaomin; Huang Shengli; Xu Zizong; Wu Chong

2001-01-01

The ratio of signal to noise for single photon resolution time spectrometer and their influence factors were studied. A method to depress the background, to shorten the measurement time and to increase the ratio of signal to noise was discussed. Results show that ratio of signal to noise is proportional to solid angle of detector to source and detection efficiency, and inverse proportional to electronics noise. Choose the activity of the source was important for decreasing of random coincidence counting. To use a coincidence gate and a discriminator of single photon were an effective way of increasing measurement accuracy and detection efficiency
The Fine Structure Constant

Indian Academy of Sciences (India)

IAS Admin

The article discusses the importance of the fine structure constant in quantum mechanics, along with the brief history of how it emerged. Al- though Sommerfelds idea of elliptical orbits has been replaced by wave mechanics, the fine struc- ture constant he introduced has remained as an important parameter in the field of ...

Frontend electronics for high-precision single photo-electron timing using FPGA-TDCs

Energy Technology Data Exchange (ETDEWEB)

Cardinali, M., E-mail: cardinal@kph.uni-mainz.de [Institut für Kernphysik, Johannes Gutenberg-University Mainz, Mainz (Germany); Helmholtz Institut Mainz, Mainz (Germany); Dzyhgadlo, R.; Gerhardt, A.; Götzen, K.; Hohler, R.; Kalicy, G.; Kumawat, H.; Lehmann, D.; Lewandowski, B.; Patsyuk, M.; Peters, K.; Schepers, G.; Schmitt, L.; Schwarz, C.; Schwiening, J.; Traxler, M.; Ugur, C.; Zühlsdorf, M. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany); Dodokhov, V.Kh. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Britting, A. [Friedrich Alexander-University of Erlangen-Nuremberg, Erlangen (Germany); and others

2014-12-01

The next generation of high-luminosity experiments requires excellent particle identification detectors which calls for Imaging Cherenkov counters with fast electronics to cope with the expected hit rates. A Barrel DIRC will be used in the central region of the Target Spectrometer of the planned PANDA experiment at FAIR. A single photo-electron timing resolution of better than 100 ps is required by the Barrel DIRC to disentangle the complicated patterns created on the image plane. R and D studies have been performed to provide a design based on the TRB3 readout using FPGA-TDCs with a precision better than 20 ps RMS and custom frontend electronics with high-bandwidth pre-amplifiers and fast discriminators. The discriminators also provide time-over-threshold information thus enabling walk corrections to improve the timing resolution. Two types of frontend electronics cards optimised for reading out 64-channel PHOTONIS Planacon MCP-PMTs were tested: one based on the NINO ASIC and the other, called PADIWA, on FPGA discriminators. Promising results were obtained in a full characterisation using a fast laser setup and in a test experiment at MAMI, Mainz, with a small scale DIRC prototype. - Highlights: • Frontend electronics for Cherenkov detectors have been developed. • FPGA-TDCs have been used for high precision timing. • Time over threshold has been utilised for walk correction. • Single photo-electron timing resolution less than 100 ps has been achieved.
Filament instability under constant loads

Science.gov (United States)

Monastra, A. G.; Carusela, M. F.; D’Angelo, M. V.; Bruno, L.

2018-04-01

Buckling of semi-flexible filaments appears in different systems and scales. Some examples are: fibers in geophysical applications, microtubules in the cytoplasm of eukaryotic cells and deformation of polymers freely suspended in a flow. In these examples, instabilities arise when a system’s parameter exceeds a critical value, being the Euler force the most known. However, the complete time evolution and wavelength of buckling processes are not fully understood. In this work we solve analytically the time evolution of a filament under a constant compressive force in the small amplitude approximation. This gives an insight into the variable force scenario in terms of normal modes. The evolution is highly sensitive to the initial configuration and to the magnitude of the compressive load. This model can be a suitable approach to many different real situations.
Real-time GPS seismology using a single receiver: method comparison, error analysis and precision validation

Science.gov (United States)

Li, Xingxing

2014-05-01

Earthquake monitoring and early warning system for hazard assessment and mitigation has traditional been based on seismic instruments. However, for large seismic events, it is difficult for traditional seismic instruments to produce accurate and reliable displacements because of the saturation of broadband seismometers and problematic integration of strong-motion data. Compared with the traditional seismic instruments, GPS can measure arbitrarily large dynamic displacements without saturation, making them particularly valuable in case of large earthquakes and tsunamis. GPS relative positioning approach is usually adopted to estimate seismic displacements since centimeter-level accuracy can be achieved in real-time by processing double-differenced carrier-phase observables. However, relative positioning method requires a local reference station, which might itself be displaced during a large seismic event, resulting in misleading GPS analysis results. Meanwhile, the relative/network approach is time-consuming, particularly difficult for the simultaneous and real-time analysis of GPS data from hundreds or thousands of ground stations. In recent years, several single-receiver approaches for real-time GPS seismology, which can overcome the reference station problem of the relative positioning approach, have been successfully developed and applied to GPS seismology. One available method is real-time precise point positioning (PPP) relied on precise satellite orbit and clock products. However, real-time PPP needs a long (re)convergence period, of about thirty minutes, to resolve integer phase ambiguities and achieve centimeter-level accuracy. In comparison with PPP, Colosimo et al. (2011) proposed a variometric approach to determine the change of position between two adjacent epochs, and then displacements are obtained by a single integration of the delta positions. This approach does not suffer from convergence process, but the single integration from delta positions to
Slab-diffusion approximation from time-constant-like calculations

International Nuclear Information System (INIS)

Johnson, R.W.

1976-12-01

Two equations were derived which describe the quantity and any fluid diffused from a slab as a function of time. One equation is applicable to the initial stage of the process; the other to the final stage. Accuracy is 0.2 percent at the one point where both approximations apply and where accuracy of either approximation is the poorest. Characterizing other rate processes might be facilitated by the use of the concept of NOLOR (normal of the logarithm of the rate) and its time dependence
Optical characteristics of Tl0.995Cu0.005InS2 single crystals

Science.gov (United States)

El-Nahass, M. M.; Ali, H. A. M.; Abu-Samaha, F. S. H.

2013-04-01

Optical properties of Tl0.995Cu0.005InS2 single crystals were studied using transmittance and reflectance measurements in the spectral wavelength range of 300-2500 nm. The optical constants (n and k) were calculated at room temperature. The analysis of the spectral behavior of the absorption coefficient in the absorption region revealed indirect transition. The refractive index dispersion data were analyzed in terms of the single oscillator model. Dispersion parameters such as the single oscillator energy (Eo), the dispersion energy (Ed), the high frequency dielectric constant (ε∞), the lattice dielectric constant (εL) and the ratio of free charge carrier concentration to the effective mass (N/m*) were estimated. The third order nonlinear susceptibility (χ(3)) was calculated according to the generalized Miller's rule. Also, the real and imaginary parts of the complex dielectric constant were determined.
Detecting Single-Nucleotides by Tunneling Current Measurements at Sub-MHz Temporal Resolution.

Science.gov (United States)

Morikawa, Takanori; Yokota, Kazumichi; Tanimoto, Sachie; Tsutsui, Makusu; Taniguchi, Masateru

2017-04-18

Label-free detection of single-nucleotides was performed by fast tunneling current measurements in a polar solvent at 1 MHz sampling rate using SiO₂-protected Au nanoprobes. Short current spikes were observed, suggestive of trapping/detrapping of individual nucleotides between the nanoelectrodes. The fall and rise features of the electrical signatures indicated signal retardation by capacitance effects with a time constant of about 10 microseconds. The high temporal resolution revealed current fluctuations, reflecting the molecular conformation degrees of freedom in the electrode gap. The method presented in this work may enable direct characterizations of dynamic changes in single-molecule conformations in an electrode gap in liquid.
An Optogenetic Platform for Real-Time, Single-Cell Interrogation of Stochastic Transcriptional Regulation.

Science.gov (United States)

Rullan, Marc; Benzinger, Dirk; Schmidt, Gregor W; Milias-Argeitis, Andreas; Khammash, Mustafa

2018-05-17

Transcription is a highly regulated and inherently stochastic process. The complexity of signal transduction and gene regulation makes it challenging to analyze how the dynamic activity of transcriptional regulators affects stochastic transcription. By combining a fast-acting, photo-regulatable transcription factor with nascent RNA quantification in live cells and an experimental setup for precise spatiotemporal delivery of light inputs, we constructed a platform for the real-time, single-cell interrogation of transcription in Saccharomyces cerevisiae. We show that transcriptional activation and deactivation are fast and memoryless. By analyzing the temporal activity of individual cells, we found that transcription occurs in bursts, whose duration and timing are modulated by transcription factor activity. Using our platform, we regulated transcription via light-driven feedback loops at the single-cell level. Feedback markedly reduced cell-to-cell variability and led to qualitative differences in cellular transcriptional dynamics. Our platform establishes a flexible method for studying transcriptional dynamics in single cells. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.
Reduction In Setup Time By Single Minute Exchange Of Dies SMED Methodology

Directory of Open Access Journals (Sweden)

Pallavi A. Gade

2015-08-01

Full Text Available Life is a race if you dont chase it someone is definitely chase you and will go ahead. Hence to survive in todays business world every manufacturer has to have some idea and plans for their betterment. Market scenario has nearly change after 1990s that every manufacturer must go through the global competition demand for short lead time demand for variety small lot sizes and also proliferation of OEMs. If we have to increase the frequency of delivery without compromising the quality Single Minute Exchange of Dies is the answer. Single Minute Exchange of Dies is not only apply to bottleneck machines it is to be implemented company wide and aim must be to bring all setup time to less than ten minutes in this paper some techniques basic procedure problems faced by companies are discussed and solution for them are suggested.
Propagator with positive cosmological constant in the 3D Euclidean quantum gravity toy model

International Nuclear Information System (INIS)

Bunting, William E; Rovelli, Carlo

2014-01-01

We study the propagator on a single tetrahedron in a three-dimensional toy model of quantum gravity with positive cosmological constant. The cosmological constant is included in the model via q-deformation of the spatial symmetry algebra, that is, we use the Turaev–Viro amplitude. The expected repulsive effect of dark energy is recovered in numerical and analytic calculations of the propagator at large scales comparable to the infrared cutoff. However, due to the simplicity of the model, we do not obtain the exact Newton limit of the propagator. This is a first step toward the similar calculation in the full 3+1 dimensional theory with larger numbers of simplicies. (paper)
Effect of the dielectric constant of mesoscopic particle on the exciton binding energy

International Nuclear Information System (INIS)

Lai Zuyou; Gu Shiwei

1991-09-01

For materials with big exciton reduced mass and big dielectric constant, such as TiO 2 , the variation of dielectric constant with the radius of an ultrafine particle (UFP) is important for determining the exciton binding energy. For the first time a phenomenological formula of the dielectric constant of a UFP with its radius in mesoscopic range is put forward in order to explain the optical properties of TiO 2 UFP. (author). 22 refs, 3 figs, 1 tab
Behavioral changes induced by single and multiple electron beam pulses

International Nuclear Information System (INIS)

Pease, V.P.; McNulty, P.J.

1985-01-01

The effects of single, and low-dose, high-dose-rate and multiple electron beam pulses on passive avoidance behavior in mice were studied. Passive avoidance was measured by recording the time that an animal took to enter a chamber from a narrow platform. There were four conditions in the experiment: (1) no shock no radiation-control, (2) radiation only, (3) shock only, and (4) radiation plus shock. Forty animals were run for each data point. Dose rate was held constant at 9 x 10/sup 7/ rads/sec. Average doses for the two single pulses were 7.18 and 8.72 rads. The average total dose for a 25 pulse per second condition was 324.0 rads. The differences between the single versus multiple pulse radiation-only conditions were significant with longer avoidance latencies in the multiple pulse condition. Avoidance latencies were also significantly longer in the shock plus radiation condition for the multiple beam pulse than the single pulse. It is concluded that single and multiple electron beam pulses significantly effect behavior, in this case producing avoidance
Nuclear constants

International Nuclear Information System (INIS)

Foos, J.

1999-01-01

This paper is written in two tables. The first one describes the different particles (bosons and fermions). The second one gives the isotopes nuclear constants of the different elements, for Z = 1 to 56. (A.L.B.)
Nuclear constants

International Nuclear Information System (INIS)

Foos, J.

2000-01-01

This paper is written in two tables. The first one describes the different particles (bosons and fermions). The second one gives the isotopes nuclear constants of the different elements, for Z = 56 to 68. (A.L.B.)
Nuclear constants

International Nuclear Information System (INIS)

Foos, J.

1999-01-01

This paper is written in two tables. The first one describes the different particles (bosons and fermions). The second one gives the isotopes nuclear constants of the different elements, for Z = 56 to 68. (A.L.B.)
Single view reflectance capture using multiplexed scattering and time-of-flight imaging

OpenAIRE

Zhao, Shuang; Velten, Andreas; Raskar, Ramesh; Bala, Kavita; Naik, Nikhil Deepak

2011-01-01

This paper introduces the concept of time-of-flight reflectance estimation, and demonstrates a new technique that allows a camera to rapidly acquire reflectance properties of objects from a single view-point, over relatively long distances and without encircling equipment. We measure material properties by indirectly illuminating an object by a laser source, and observing its reflected light indirectly using a time-of-flight camera. The configuration collectively acquires dense angular, but l...
Time-domain single-source integral equations for analyzing scattering from homogeneous penetrable objects

KAUST Repository

Valdé s, Felipe; Andriulli, Francesco P.; Bagci, Hakan; Michielssen, Eric

2013-01-01

Single-source time-domain electric-and magnetic-field integral equations for analyzing scattering from homogeneous penetrable objects are presented. Their temporal discretization is effected by using shifted piecewise polynomial temporal basis
Improving Estimated Optical Constants With MSTM and DDSCAT Modeling

Science.gov (United States)

Pitman, K. M.; Wolff, M. J.

2015-12-01

We present numerical experiments to determine quantitatively the effects of mineral particle clustering on Mars spacecraft spectral signatures and to improve upon the values of refractive indices (optical constants n, k) derived from Mars dust laboratory analog spectra such as those from RELAB and MRO CRISM libraries. Whereas spectral properties for Mars analog minerals and actual Mars soil are dominated by aggregates of particles smaller than the size of martian atmospheric dust, the analytic radiative transfer (RT) solutions used to interpret planetary surfaces assume that individual, well-separated particles dominate the spectral signature. Both in RT models and in the refractive index derivation methods that include analytic RT approximations, spheres are also over-used to represent nonspherical particles. Part of the motivation is that the integrated effect over randomly oriented particles on quantities such as single scattering albedo and phase function are relatively less than for single particles. However, we have seen in previous numerical experiments that when varying the shape and size of individual grains within a cluster, the phase function changes in both magnitude and slope, thus the "relatively less" effect is more significant than one might think. Here we examine the wavelength dependence of the forward scattering parameter with multisphere T-matrix (MSTM) and discrete dipole approximation (DDSCAT) codes that compute light scattering by layers of particles on planetary surfaces to see how albedo is affected and integrate our model results into refractive index calculations to remove uncertainties in approximations and parameters that can lower the accuracy of optical constants. By correcting the single scattering albedo and phase function terms in the refractive index determinations, our data will help to improve the understanding of Mars in identifying, mapping the distributions, and quantifying abundances for these minerals and will address long
Optical properties of Sulfur doped InP single crystals

Science.gov (United States)

El-Nahass, M. M.; Youssef, S. B.; Ali, H. A. M.

2014-05-01

Optical properties of InP:S single crystals were investigated using spectrophotometric measurements in the spectral range of 200-2500 nm. The absorption coefficient and refractive index were calculated. It was found that InP:S crystals exhibit allowed and forbidden direct transitions with energy gaps of 1.578 and 1.528 eV, respectively. Analysis of the refractive index in the normal dispersion region was discussed in terms of the single oscillator model. Some optical dispersion parameters namely: the dispersion energy (Ed), single oscillator energy (Eo), high frequency dielectric constant (ɛ∞), and lattice dielectric constant (ɛL) were determined. The volume and the surface energy loss functions (VELF & SELF) were estimated. Also, the real and imaginary parts of the complex conductivity were calculated.
Real-Time, Single-Shot Temporal Measurements of Short Electron Bunches, Terahertz CSR and FEL Radiation

CERN Document Server

Berden, G; Van der Meer, A F G

2005-01-01

Electro-optic detection of the Coulomb field of electron bunches is a promising technique for single-shot measurements of the bunch length and shape in the sub-picosecond time domain. This technique has been applied to the measurement of 50 MeV electron bunches in the FELIX free electron laser, showing the longitudinal profile of single bunches of around 650 fs FWHM [Phys. Rev. Lett. 93, 114802 (2004)]. The method is non-destructive and real-time, and therefore ideal for online monitoring of the longitudinal shape of single electron bunches. At FELIX we have used it for real-time optimization of sub-picosecond electron bunches. Electro-optic detection has also been used to measure the electric field profiles of far-infrared (or terahertz) optical pulses generated by the relativistic electrons. We have characterised the far-infrared output of the free electron laser, and more recently, we have measured the temporal profile of terahertz optical pulses generated at one of the bending magnets.
Determination of protonation constants of hydroquinone and stability constants of Th(IV) hydroquinone complex

International Nuclear Information System (INIS)

Sawant, R.M.; Ramakumar, K.L.; Sharma, R.S.

2003-01-01

Protonation constants of hydroquinone and stability constants of thorium hydroquinone complexes were determined in 1 M NaClO 4 medium at 25 ± 0.5 degC, by varying concentration of thorium, using pH titration technique. Protonation constants of hydroquinone (β 1H = [HQ]/[H][Q] and β 2H = [H 2 Q]/[H] 2 [Q]) were found to be β 1H = 11.404 ± 0.014 and β 2H = 21.402 ± 0.012. The analysis of titration data of thorium-hydroquinone system appears to indicate the formation of species Th(H 2 Q) 3 (OH) and Th(H 2 O) 4 (OH). Equilibrium constants obtained for these species are -log β 13-I = 48.51 ± 0.67 and -log β 14-1 64.86 ± 1.25 respectively which are not reported in the literature. (author)

Nuclear constants

International Nuclear Information System (INIS)

Foos, J.

1998-01-01

This paper is made of two tables. The first table describes the different particles (bosons and fermions) while the second one gives the nuclear constants of isotopes from the different elements with Z = 1 to 25. (J.S.)
Comparison of dual-time-constant and fast-acting automatic gain control (AGC) systems in cochlear implants.

Science.gov (United States)

Boyle, Patrick J; Büchner, Andreas; Stone, Michael A; Lenarz, Thomas; Moore, Brian C J

2009-04-01

Cochlear implants usually employ an automatic gain control (AGC) system as a first stage of processing. AGC1 was a fast-acting (syllabic) compressor. AGC2 was a dual-time-constant system; it usually performed as a slow-acting compressor, but incorporated an additional fast-acting system to provide protection from sudden increases in sound level. Six experienced cochlear-implant users were tested in a counterbalanced order, receiving one-month of experience with a given AGC type before switching to the other type. Performance was evaluated shortly after provision of a given AGC type and after one-month of experience with that AGC type. Questionnaires, mainly relating to listening in quiet situations, did not reveal significant differences between the two AGC types. However, fixed-level and roving-level tests of sentence identification in noise both revealed significantly better performance for AGC2. It is suggested that the poorer performance for AGC1 occurred because AGC1 introduced cross-modulation between the target speech and background noise, which made perceptual separation of the target and background more difficult.
Tailoring the optical constants in single-crystal silicon with embedded silver nanostructures for advanced silicon photonics applications

International Nuclear Information System (INIS)

Akhter, Perveen; Huang, Mengbing; Spratt, William; Kadakia, Nirag; Amir, Faisal

2015-01-01

Plasmonic effects associated with metal nanostructures are expected to hold the key to tailoring light emission/propagation and harvesting solar energy in materials including single crystal silicon which remains the backbone in the microelectronics and photovoltaics industries but unfortunately, lacks many functionalities needed for construction of advanced photonic and optoelectronics devices. Currently, silicon plasmonic structures are practically possible only in the configuration with metal nanoparticles or thin film arrays on a silicon surface. This does not enable one to exploit the full potential of plasmonics for optical engineering in silicon, because the plasmonic effects are dominant over a length of ∼50 nm, and the active device region typically lies below the surface much beyond this range. Here, we report on a novel method for the formation of silver nanoparticles embedded within a silicon crystal through metal gettering from a silver thin film deposited at the surface to nanocavities within the Si created by hydrogen ion implantation. The refractive index of the Ag-nanostructured layer is found to be 3–10% lower or higher than that of silicon for wavelengths below or beyond ∼815–900 nm, respectively. Around this wavelength range, the optical extinction values increase by a factor of 10–100 as opposed to the pure silicon case. Increasing the amount of gettered silver leads to an increased extinction as well as a redshift in wavelength position for the resonance. This resonance is attributed to the surface plasmon excitation of the resultant silver nanoparticles in silicon. Additionally, we show that the profiles for optical constants in silicon can be tailored by varying the position and number of nanocavity layers. Such silicon crystals with embedded metal nanostructures would offer novel functional base structures for applications in silicon photonics, optoelectronics, photovoltaics, and plasmonics
Effective constants for wave propagation through partially saturated porous media

International Nuclear Information System (INIS)

Berryman, J.G.; Thigpen, L.

1985-01-01

The multipole scattering coefficients for elastic wave scattering from a spherical inhomogeneity in a fluid-saturated porous medium have been calculated. These coefficients may be used to obtain estimates of the effective macroscopic constants for long-wavelength propagation of elastic waves through partially saturated media. If the volume average of the single scattering from spherical bubbles of gas and liquid is required to vanish, the resulting equations determine the effective bulk modulus, density, and viscosity of the multiphase fluid filling the pores. The formula for the effective viscosity during compressional wave excitation is apparently new
Constant load and constant displacement stress corrosion in simulated water reactor environments

International Nuclear Information System (INIS)

Lloyd, G.J.

1987-02-01

The stress corrosion behaviour of selected water reactor constructional materials, as determined by constant load or constant displacement test techniques, is reviewed. Experimental results obtained using a very wide range of conditions have been collected in a form for easy reference. A discussion is given of some apparent trends in these data. The possible reasons for these trends are considered together with a discussion of how the observed discrepancies may be resolved. (author)
Subcooled boiling heat transfer and dryout on a constant temperature microheater

International Nuclear Information System (INIS)

Chen Tailian; Klausner, James F.; Chung, Jacob N.

2004-01-01

An experimental study of single-bubble subcooled boiling heat transfer (ΔT sub =31.5 K) on a small heater with constant wall temperature has been performed to better understand the boiling heat transfer associated with this unique configuration. The heater of 0.27 mm x 0.27 mm is set at different superheats to generate vapor bubbles on the microheater surface. For each superheat, the heater temperature is maintained constant by an electronic feedback control circuit while its power dissipation is measured at a frequency of 4.5 kHz. The single-bubble boiling is characterized by a transient bubble nucleation-departure period and a slow growth period. For the superheat range of 34-114 K in this study, at wall superheats below 84 K, the heater remains partially wetted following bubble departure and subsequent nucleation, and this period is characterized by a heat flux spike. At wall superheats above 90 K, the heater is blanketed with vapor following bubble departure and the heat flux experiences a dip during this period. At all superheats, the slow growth period is characterized by an almost uniform heat flux, and it has been observed that the heater surface is mostly covered by vapor. The unique heat transfer processes associated with boiling on this microheater are considerably different than those typically observed during boiling on a large heater
Digital atom interferometer with single particle control on a discretized space-time geometry.

Science.gov (United States)

Steffen, Andreas; Alberti, Andrea; Alt, Wolfgang; Belmechri, Noomen; Hild, Sebastian; Karski, Michał; Widera, Artur; Meschede, Dieter

2012-06-19

Engineering quantum particle systems, such as quantum simulators and quantum cellular automata, relies on full coherent control of quantum paths at the single particle level. Here we present an atom interferometer operating with single trapped atoms, where single particle wave packets are controlled through spin-dependent potentials. The interferometer is constructed from a sequence of discrete operations based on a set of elementary building blocks, which permit composing arbitrary interferometer geometries in a digital manner. We use this modularity to devise a space-time analogue of the well-known spin echo technique, yielding insight into decoherence mechanisms. We also demonstrate mesoscopic delocalization of single atoms with a separation-to-localization ratio exceeding 500; this result suggests their utilization beyond quantum logic applications as nano-resolution quantum probes in precision measurements, being able to measure potential gradients with precision 5 x 10(-4) in units of gravitational acceleration g.
Time-of-flight camera via a single-pixel correlation image sensor

Science.gov (United States)

Mao, Tianyi; Chen, Qian; He, Weiji; Dai, Huidong; Ye, Ling; Gu, Guohua

2018-04-01

A time-of-flight imager based on single-pixel correlation image sensors is proposed for noise-free depth map acquisition in presence of ambient light. Digital micro-mirror device and time-modulated IR-laser provide spatial and temporal illumination on the unknown object. Compressed sensing and ‘four bucket principle’ method are combined to reconstruct the depth map from a sequence of measurements at a low sampling rate. Second-order correlation transform is also introduced to reduce the noise from the detector itself and direct ambient light. Computer simulations are presented to validate the computational models and improvement of reconstructions.
Long-Term Efficacy of Constant Current Deep Brain Stimulation in Essential Tremor.

Science.gov (United States)

Rezaei Haddad, Ali; Samuel, Michael; Hulse, Natasha; Lin, Hsin-Ying; Ashkan, Keyoumars

2017-07-01

Ventralis intermedius deep brain stimulation is an established intervention for medication-refractory essential tremor. Newer constant current stimulation technology offers theoretical advantage over the traditional constant voltage systems in terms of delivering a more biologically stable therapy. There are no previous reports on the outcomes of constant current deep brain stimulation in the treatment of essential tremor. This study aimed to evaluate the long-term efficacy of ventralis intermedius constant current deep brain stimulation in patients diagnosed with essential tremor. Essential tremor patients implanted with constant current deep brain stimulation for a minimum of three years were evaluated. Clinical outcomes were assessed using the Fahn-Tolosa-Marin tremor rating scale at baseline and postoperatively at the time of evaluation. The quality of life in the patients was assessed using the Quality of Life in Essential Tremor questionnaire. Ten patients were evaluated with a median age at evaluation of 74 years (range 66-79) and a mean follow up time of 49.7 (range 36-78) months since starting stimulation. Constant current ventralis intermedius deep brain stimulation was well tolerated and effective in all patients with a mean score improvement from 50.7 ± 5.9 to 17.4 ± 5.7 (p = 0.0020) in the total Fahn-Tolosa-Marin rating scale score (65.6%). Furthermore, the total combined mean Quality of Life in Essential Tremor score was improved from 56.2 ± 4.9 to 16.8 ± 3.5 (p value = 0.0059) (70.1%). This report shows that long-term constant current ventralis intermedius deep brain stimulation is a safe and effective intervention for essential tremor patients. © 2017 International Neuromodulation Society.
Comparative study of transparent ceramic and single crystal Ce doped LuAG scintillators

International Nuclear Information System (INIS)

Yanagida, Takayuki; Fujimoto, Yutaka; Yokota, Yuui; Kamada, Kei; Yanagida, Satoko; Yoshikawa, Akira; Yagi, Hideki; Yanagitani, Takagimi

2011-01-01

Transparent ceramic Ce 0.5% doped Lu 3 Al 5 O 12 (LuAG) scintillator grown by the sintering method and single crystalline Ce doped LuAG grown by the Czochralski method are prepared. They are cut to the physical dimensions 4 × 4 × 2 mm 3 . Their transmittance and radio luminescence spectra are evaluated. They are both transmissive in wavelength longer than 500 nm and intense Ce 3+ 5d–4f emission appears around 520 nm. When 137 Cs γ-ray is irradiated, 662 keV photo-absorption peaks are clearly observed in each sample. The transparent ceramic one shows higher light yield than that of the single crystalline one. The absolute light yield of the ceramic sample is turned out to be 14800 ± 1500 ph/MeV. The decay time constants are evaluated under pulse X-ray excitation. The main component of the decay time of ceramic and single crystalline one are determined as 37 and 46 ns, respectively.
Variation in Pockels constants of silicate glass-ceramics prepared by perfect surface crystallization

Science.gov (United States)

Takano, Kazuya; Takahashi, Yoshihiro; Miyazaki, Takamichi; Terakado, Nobuaki; Fujiwara, Takumi

2018-01-01

We investigated the Pockels effect in polycrystalline materials consisting of highly oriented polar fresnoite-type Sr2TiSi2O8 fabricated using perfectly surface-crystallized glass-ceramics (PSC-GCs). The chemical composition of the precursor glass was shown to significantly affect the crystallized texture, e.g., the crystal orientation and appearance of amorphous nanoparasites in the domains, resulting in variations in the Pockels constants. Single crystals exhibiting spontaneous polarization possessed large structural anisotropy, leading to a strong dependence of the nonlinear-optical properties on the direction of polarized light. This study suggests that variations in the Pockels constants (r13 and r33) and tuning of the r13/r33 ratio can be realized in PSC-GC materials.
A modified large number theory with constant G

Science.gov (United States)

Recami, Erasmo

1983-03-01

The inspiring “numerology” uncovered by Dirac, Eddington, Weyl, et al. can be explained and derived when it is slightly modified so to connect the “gravitational world” (cosmos) with the “strong world” (hadron), rather than with the electromagnetic one. The aim of this note is to show the following. In the present approach to the “Large Number Theory,” cosmos and hadrons are considered to be (finite) similar systems, so that the ratio{{bar R} / {{bar R} {bar r}} of the cosmos typical lengthbar R to the hadron typical lengthbar r is constant in time (for instance, if both cosmos and hadrons undergo an expansion/contraction cycle—according to the “cyclical bigbang” hypothesis—thenbar R andbar r can be chosen to be the maximum radii, or the average radii). As a consequence, then gravitational constant G results to be independent of time. The present note is based on work done in collaboration with P. Caldirola, G. D. Maccarrone, and M. Pavšič.
Time dependent temperature distribution in pulsed Ti:sapphire lasers

Science.gov (United States)

Buoncristiani, A. Martin; Byvik, Charles E.; Farrukh, Usamah O.

1988-01-01

An expression is derived for the time dependent temperature distribution in a finite solid state laser rod for an end-pumped beam of arbitrary shape. The specific case of end pumping by circular (constant) or Gaussian beam is described. The temperature profile for a single pump pulse and for repetitive pulse operation is discussed. The particular case of the temperature distribution in a pulsed titanium:sapphire rod is considered.
Single-row versus double-row arthroscopic rotator cuff repair in small- to medium-sized tears.

Science.gov (United States)

Aydin, Nuri; Kocaoglu, Baris; Guven, Osman

2010-07-01

Double-row rotator cuff repair leads to superior cuff integrity and clinical results compared with single-row repair. The study enrolled 68 patients with a full-thickness rotator cuff tear who were divided into 2 groups of 34 patients according to repair technique. The patients were followed-up for at least 2 years. The results were evaluated by Constant score. Despite the biomechanical studies and cadaver studies that proved the superiority of double-row fixation over single-row fixation, our clinical results show no difference in functional outcome between the two methods. It is evident that double-row repair is more technically demanding, expensive, and time-consuming than single-row repair, without providing a significant improvement in clinical results. Comparison between groups did not show significant differences. At the final follow-up, the Constant score was 82.2 in the single-row group and 78.8 in the double-row group. Functional outcome was improved in both groups after surgery, but the difference between the 2 groups was not significant. At long-term follow-up, arthroscopic rotator cuff repair with the double-row technique showed no significant difference in clinical outcome compared with single-row repair in small to medium tears. 2010 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.
Large Dielectric Constant Enhancement in MXene Percolative Polymer Composites

KAUST Repository

Tu, Shao Bo

2018-04-06

near the percolation limit of about 15.0 wt % MXene loading, which surpasses all previously reported composites made of carbon-based fillers in the same polymer. With up to 10 wt % MXene loading, the dielectric loss of the MXene/P(VDF-TrFE-CFE) composite indicates only an approximately 5-fold increase (from 0.06 to 0.35), while the dielectric constant increased by 25 times over the same composition range. Furthermore, the ratio of permittivity to loss factor of the MXene-polymer composite is superior to that of all previously reported fillers in this same polymer. The dielectric constant enhancement effect is demonstrated to exist in other polymers as well when loaded with MXene. We show that the dielectric constant enhancement is largely due to the charge accumulation caused by the formation of microscopic dipoles at the surfaces between the MXene sheets and the polymer matrix under an external applied electric field.
Accurate and approximate thermal rate constants for polyatomic chemical reactions

International Nuclear Information System (INIS)

Nyman, Gunnar

2007-01-01

In favourable cases it is possible to calculate thermal rate constants for polyatomic reactions to high accuracy from first principles. Here, we discuss the use of flux correlation functions combined with the multi-configurational time-dependent Hartree (MCTDH) approach to efficiently calculate cumulative reaction probabilities and thermal rate constants for polyatomic chemical reactions. Three isotopic variants of the H 2 + CH 3 → CH 4 + H reaction are used to illustrate the theory. There is good agreement with experimental results although the experimental rates generally are larger than the calculated ones, which are believed to be at least as accurate as the experimental rates. Approximations allowing evaluation of the thermal rate constant above 400 K are treated. It is also noted that for the treated reactions, transition state theory (TST) gives accurate rate constants above 500 K. TST theory also gives accurate results for kinetic isotope effects in cases where the mass of the transfered atom is unchanged. Due to neglect of tunnelling, TST however fails below 400 K if the mass of the transferred atom changes between the isotopic reactions
Nonadiabatic Dynamics in Single-Electron Tunneling Devices with Time-Dependent Density-Functional Theory

Science.gov (United States)

Dittmann, Niklas; Splettstoesser, Janine; Helbig, Nicole

2018-04-01

We simulate the dynamics of a single-electron source, modeled as a quantum dot with on-site Coulomb interaction and tunnel coupling to an adjacent lead in time-dependent density-functional theory. Based on this system, we develop a time-nonlocal exchange-correlation potential by exploiting analogies with quantum-transport theory. The time nonlocality manifests itself in a dynamical potential step. We explicitly link the time evolution of the dynamical step to physical relaxation timescales of the electron dynamics. Finally, we discuss prospects for simulations of larger mesoscopic systems.
Time-over-threshold readout to enhance the high flux capabilities of single-photon-counting detectors

International Nuclear Information System (INIS)

Bergamaschi, Anna; Dinapoli, Roberto; Greiffenberg, Dominic; Henrich, Beat; Johnson, Ian; Mozzanica, Aldo; Radicci, Valeria; Schmitt, Bernd; Shi, Xintian; Stoppani, Laura

2011-01-01

The MYTHEN photon-counting ASIC operated in time-over-threshold mode shows an innovative approach towards the development of a detector operating with very high photon intensities while maintaining the single-photon sensitivity for synchrotron radiation experiments. The MYTHEN single-photon-counting (SPC) detector has been characterized using the time-over-threshold (ToT) readout method, i.e. measuring the time that the signal produced by the detected X-rays remains above the comparator threshold. In the following it is shown that the ToT readout preserves the sensitivity, dynamic range and capability of background suppression of the SPC mode, while enhancing the count-rate capability, which is the main limitation of state-of-the-art SPC systems
Time-over-threshold readout to enhance the high flux capabilities of single-photon-counting detectors

Energy Technology Data Exchange (ETDEWEB)

Bergamaschi, Anna, E-mail: anna.bergamaschi@psi.ch; Dinapoli, Roberto; Greiffenberg, Dominic; Henrich, Beat; Johnson, Ian; Mozzanica, Aldo; Radicci, Valeria; Schmitt, Bernd; Shi, Xintian; Stoppani, Laura [Paul Scherrer Institut, CH-5232 Villigen (Switzerland)

2011-11-01

The MYTHEN photon-counting ASIC operated in time-over-threshold mode shows an innovative approach towards the development of a detector operating with very high photon intensities while maintaining the single-photon sensitivity for synchrotron radiation experiments. The MYTHEN single-photon-counting (SPC) detector has been characterized using the time-over-threshold (ToT) readout method, i.e. measuring the time that the signal produced by the detected X-rays remains above the comparator threshold. In the following it is shown that the ToT readout preserves the sensitivity, dynamic range and capability of background suppression of the SPC mode, while enhancing the count-rate capability, which is the main limitation of state-of-the-art SPC systems.
RNA structure and scalar coupling constants

Energy Technology Data Exchange (ETDEWEB)

Tinoco, I. Jr.; Cai, Z.; Hines, J.V.; Landry, S.M.; SantaLucia, J. Jr.; Shen, L.X.; Varani, G. [Univ. of California, Berkeley, CA (United States)

1994-12-01

Signs and magnitudes of scalar coupling constants-spin-spin splittings-comprise a very large amount of data that can be used to establish the conformations of RNA molecules. Proton-proton and proton-phosphorus splittings have been used the most, but the availability of {sup 13}C-and {sup 15}N-labeled molecules allow many more coupling constants to be used for determining conformation. We will systematically consider the torsion angles that characterize a nucleotide unit and the coupling constants that depend on the values of these torsion angles. Karplus-type equations have been established relating many three-bond coupling constants to torsion angles. However, one- and two-bond coupling constants can also depend on conformation. Serianni and coworkers measured carbon-proton coupling constants in ribonucleosides and have calculated their values as a function of conformation. The signs of two-bond coupling can be very useful because it is easier to measure a sign than an accurate magnitude.

Single-Index Additive Vector Autoregressive Time Series Models

KAUST Repository

LI, YEHUA

2009-09-01

We study a new class of nonlinear autoregressive models for vector time series, where the current vector depends on single-indexes defined on the past lags and the effects of different lags have an additive form. A sufficient condition is provided for stationarity of such models. We also study estimation of the proposed model using P-splines, hypothesis testing, asymptotics, selection of the order of the autoregression and of the smoothing parameters and nonlinear forecasting. We perform simulation experiments to evaluate our model in various settings. We illustrate our methodology on a climate data set and show that our model provides more accurate yearly forecasts of the El Niño phenomenon, the unusual warming of water in the Pacific Ocean. © 2009 Board of the Foundation of the Scandinavian Journal of Statistics.
The Locus of the apices of projectile trajectories under constant drag

OpenAIRE

Hernández-Saldaña, H.

2017-01-01

We present an analytical solution for the projectile coplanar motion under constant drag parametrised by the velocity angle. We found the locus formed by the apices of the projectile trajectories. The range and time of flight are obtained numerically and we find that the optimal launching angle is smaller than in the free drag case. This is a good example of problems with constant dissipation of energy that includes curvature, and it is proper for intermediate courses of mechanics.
Recursion Formulae for Obtaining Surfaces with Constant Mean Curvature in R2,1

International Nuclear Information System (INIS)

Tian Yongbo; Nan Zhijie; Tian Chou

2007-01-01

Though the Baecklund transformation on time-like surfaces with constant mean curvature surfaces in R 2,1 has been obtained, it is not easy to obtain corresponding surfaces because the procedure of solving the related integrable system cannot be avoided when the Baecklund transformation is used. For sake of this, in this article, some special work is done to reform the Baecklund transformation to a recursion formula, by which we can construct time-like surfaces with constant mean curvature form known ones just by quadrature procedure.
Covariant single-time equations for a system of N spinor particles

International Nuclear Information System (INIS)

Dej, E.A.; Kapshaj, V.N.; Skachkov, N.B.

1993-01-01

Based on the field-theoretical Green functions that describe a system of N fermions in terms of a single-time variables we have derived covariant equations for the wave function of a bound state. The interaction operators in these equations and normalization conditions for the wave function are determined. As an example, the baryon is considered as a bound state of three quarks. 19 refs.; 1 fig
Relativity theory and time perception: single or multiple clocks?

Science.gov (United States)

Buhusi, Catalin V; Meck, Warren H

2009-07-22

Current theories of interval timing assume that humans and other animals time as if using a single, absolute stopwatch that can be stopped or reset on command. Here we evaluate the alternative view that psychological time is represented by multiple clocks, and that these clocks create separate temporal contexts by which duration is judged in a relative manner. Two predictions of the multiple-clock hypothesis were tested. First, that the multiple clocks can be manipulated (stopped and/or reset) independently. Second, that an event of a given physical duration would be perceived as having different durations in different temporal contexts, i.e., would be judged differently by each clock. Rats were trained to time three durations (e.g., 10, 30, and 90 s). When timing was interrupted by an unexpected gap in the signal, rats reset the clock used to time the "short" duration, stopped the "medium" duration clock, and continued to run the "long" duration clock. When the duration of the gap was manipulated, the rats reset these clocks in a hierarchical order, first the "short", then the "medium", and finally the "long" clock. Quantitative modeling assuming re-allocation of cognitive resources in proportion to the relative duration of the gap to the multiple, simultaneously timed event durations was used to account for the results. These results indicate that the three event durations were effectively timed by separate clocks operated independently, and that the same gap duration was judged relative to these three temporal contexts. Results suggest that the brain processes the duration of an event in a manner similar to Einstein's special relativity theory: A given time interval is registered differently by independent clocks dependent upon the context.
Relativity theory and time perception: single or multiple clocks?

Directory of Open Access Journals (Sweden)

Catalin V Buhusi

2009-07-01

Full Text Available Current theories of interval timing assume that humans and other animals time as if using a single, absolute stopwatch that can be stopped or reset on command. Here we evaluate the alternative view that psychological time is represented by multiple clocks, and that these clocks create separate temporal contexts by which duration is judged in a relative manner. Two predictions of the multiple-clock hypothesis were tested. First, that the multiple clocks can be manipulated (stopped and/or reset independently. Second, that an event of a given physical duration would be perceived as having different durations in different temporal contexts, i.e., would be judged differently by each clock.Rats were trained to time three durations (e.g., 10, 30, and 90 s. When timing was interrupted by an unexpected gap in the signal, rats reset the clock used to time the "short" duration, stopped the "medium" duration clock, and continued to run the "long" duration clock. When the duration of the gap was manipulated, the rats reset these clocks in a hierarchical order, first the "short", then the "medium", and finally the "long" clock. Quantitative modeling assuming re-allocation of cognitive resources in proportion to the relative duration of the gap to the multiple, simultaneously timed event durations was used to account for the results.These results indicate that the three event durations were effectively timed by separate clocks operated independently, and that the same gap duration was judged relative to these three temporal contexts. Results suggest that the brain processes the duration of an event in a manner similar to Einstein's special relativity theory: A given time interval is registered differently by independent clocks dependent upon the context.
Radiation balances and the solar constant

Science.gov (United States)

Crommelynck, D.

1981-01-01

The radiometric concepts are defined in order to consider various types of radiation balances and relate them to the diabetic form of the energy balance. Variability in space and time of the components of the radiation field are presented. A specific concept for sweeping which is tailored to the requirements is proposed. Finally, after establishing the truncated character of the present knowledge of the radiation balance. The results of the last observations of the solar constant are given. Ground and satellite measurement techniques are discussed.
The Boltzmann constant from a snifter

International Nuclear Information System (INIS)

Tyukodi, B; Sárközi, Zs; Néda, Z; Tunyagi, A; Györke, E

2012-01-01

Evaporation of a small glass of ethylic alcohol is studied both experimentally and through an elementary thermal physics approach. For a cylindrical beaker and no air flow in the room, a simple quadratic relation is found between the evaporation time and the mass of evaporated liquid. This problem and the obtained results offer excellent possibilities for simple student experiments and for testing basic principles of thermal physics. As an example, we use the obtained results for estimating the value of the Boltzmann constant from evaporation experiments. (paper)
Lepton Collider Operation With Constant Currents

International Nuclear Information System (INIS)

Wienands, U.

2006-01-01

Electron-positron colliders have been operating in a top-up-and-coast fashion with a cycle time depending on the beam life time, typically one or more hours. Each top-up involves ramping detector systems in addition to the actual filling time. The loss in accumulated luminosity may be 20-50%. During the last year, both B-Factories have commissioned a continuous-injection mode of operation in which beam is injected without ramping the detector, thus raising luminosity integration by always operating at peak luminosity. Constant beam currents also reduce thermal drift and trips caused by change in beam loading. To achieve this level of operation, special efforts were made to reduce the injection losses and also to implement gating procedures in the detectors, minimizing dead time. Beam collimation can reduce injection noise but also cause an increase in background rates. A challenge can be determining beam lifetime, important to maintain tuning of the beams
The inductively coupled plasma as a source for the measurement of fundamental spectroscopic constants

International Nuclear Information System (INIS)

Farnsworth, P.B.

1993-01-01

Inductively coupled plasmas (ICPs) are stable, robust sources for the generation of spectra from neutral and singly ionized atoms. They are used extensively for analytical spectrometry, but have seen limited use for the measurement of fundamental spectroscopic constants. Several properties of the ICP affect its suitability for such fundamental measurements. They include: spatial structure, spectral background, noise characteristics, electron densities and temperatures, and the state of equilibrium in the plasma. These properties are particularly sensitive to the means by which foreign atoms are introduced into the plasma. With some departures from the operating procedures normally used in analytical measurements, the ICP promise to be a useful source for the measurement of fundamental atomic constants. (orig.)
Constant DC-Capacitor Voltage-Control-Based Harmonics Compensation Strategy of Smart Charger for Electric Vehicles in Single-Phase Three-Wire Distribution Feeders

Directory of Open Access Journals (Sweden)

Fuka Ikeda

2017-06-01

Full Text Available This paper discusses harmonic current compensation of the constant DC-capacitor voltage-control (CDCVC-based strategy of smart chargers for electric vehicles (EVs in single-phase three-wire distribution feeders (SPTWDFs under nonlinear load conditions. The basic principle of the CDCVC-based harmonics compensation strategy under nonlinear load conditions is discussed in detail. The instantaneous power flowing into the three-leg pulse-width modulated (PWM rectifier, which performs as a smart charger, shows that the CDCVC-based strategy achieves balanced and sinusoidal source currents with a unity power factor. The CDCVC-based harmonics compensation strategy does not require any calculation blocks of fundamental reactive, unbalanced active, and harmonic currents. Thus, the authors propose a simplified algorithm to compensate for reactive, unbalanced active, and harmonic currents. A digital computer simulation is implemented to confirm the validity and high practicability of the CDCVC-based harmonics compensation strategy using PSIM software. Simulation results demonstrate that balanced and sinusoidal source currents with a unity power factor in SPTWDFs are obtained on the secondary side of the pole-mounted distribution transformer (PMDT during both the battery-charging and discharging operations in EVs, compensating for the reactive, unbalanced active, and harmonic currents.
Single particle distributions, ch.2

International Nuclear Information System (INIS)

Blokzijl, R.

1977-01-01

A survey of inclusive single particle distributions is given for various particles. A comparison of particle cross-sections measured in K - p experiments at different center of mass energies shows that some of these cross-sections remain almost constant over a wide range of incoming K - momenta
Stability Constants of Some Biologically Important Pyrazoles and Their Ni2+ Complexes in Different Dielectric Constant of Medium

Directory of Open Access Journals (Sweden)

S. D. Deosarkar

2012-01-01

Full Text Available The proton-ligand stability constants of some biologically important new pyrazoles and formation constants of their complexes with Ni(II were determined at 0.1 mol dm-3 ionic strength and at 303.15 K in different dielectric constant of dioxane-water mixture by potentiometric method. The Calvin-Bjerrum's pH-titration technique as used by Irving and Rossotti was used for determination of stability constants. The results enabled to study the electrostatic forces of attraction between metal ion and ligand with changes in dielectric constant of the medium.
Improving performance of single-path code through a time-predictable memory hierarchy

DEFF Research Database (Denmark)

Cilku, Bekim; Puffitsch, Wolfgang; Prokesch, Daniel

2017-01-01

-predictable memory hierarchy with a prefetcher that exploits the predictability of execution traces in single-path code to speed up code execution. The new memory hierarchy reduces both the cache-miss penalty time and the cache-miss rate on the instruction cache. The benefit of the approach is demonstrated through...
Real-time single-molecule imaging of quantum interference.

Science.gov (United States)

Juffmann, Thomas; Milic, Adriana; Müllneritsch, Michael; Asenbaum, Peter; Tsukernik, Alexander; Tüxen, Jens; Mayor, Marcel; Cheshnovsky, Ori; Arndt, Markus

2012-03-25

The observation of interference patterns in double-slit experiments with massive particles is generally regarded as the ultimate demonstration of the quantum nature of these objects. Such matter-wave interference has been observed for electrons, neutrons, atoms and molecules and, in contrast to classical physics, quantum interference can be observed when single particles arrive at the detector one by one. The build-up of such patterns in experiments with electrons has been described as the "most beautiful experiment in physics". Here, we show how a combination of nanofabrication and nano-imaging allows us to record the full two-dimensional build-up of quantum interference patterns in real time for phthalocyanine molecules and for derivatives of phthalocyanine molecules, which have masses of 514 AMU and 1,298 AMU respectively. A laser-controlled micro-evaporation source was used to produce a beam of molecules with the required intensity and coherence, and the gratings were machined in 10-nm-thick silicon nitride membranes to reduce the effect of van der Waals forces. Wide-field fluorescence microscopy detected the position of each molecule with an accuracy of 10 nm and revealed the build-up of a deterministic ensemble interference pattern from single molecules that arrived stochastically at the detector. In addition to providing this particularly clear demonstration of wave-particle duality, our approach could also be used to study larger molecules and explore the boundary between quantum and classical physics.
Dielectric constant of ionic solutions: a field-theory approach.

Science.gov (United States)

Levy, Amir; Andelman, David; Orland, Henri

2012-06-01

We study the variation of the dielectric response of a dielectric liquid (e.g. water) when a salt is added to the solution. Employing field-theoretical methods, we expand the Gibbs free energy to first order in a loop expansion and calculate self-consistently the dielectric constant. We predict analytically the dielectric decrement which depends on the ionic strength in a complex way. Furthermore, a qualitative description of the hydration shell is found and is characterized by a single length scale. Our prediction fits rather well a large range of concentrations for different salts using only one fit parameter related to the size of ions and dipoles.
A natural cosmological constant from chameleons

International Nuclear Information System (INIS)

Nastase, Horatiu; Weltman, Amanda

2015-01-01

We present a simple model where the effective cosmological constant appears from chameleon scalar fields. For a Kachru–Kallosh–Linde–Trivedi (KKLT)-inspired form of the potential and a particular chameleon coupling to the local density, patches of approximately constant scalar field potential cluster around regions of matter with density above a certain value, generating the effect of a cosmological constant on large scales. This construction addresses both the cosmological constant problem (why Λ is so small, yet nonzero) and the coincidence problem (why Λ is comparable to the matter density now)
A natural cosmological constant from chameleons

Directory of Open Access Journals (Sweden)

Horatiu Nastase

2015-07-01

Full Text Available We present a simple model where the effective cosmological constant appears from chameleon scalar fields. For a Kachru–Kallosh–Linde–Trivedi (KKLT-inspired form of the potential and a particular chameleon coupling to the local density, patches of approximately constant scalar field potential cluster around regions of matter with density above a certain value, generating the effect of a cosmological constant on large scales. This construction addresses both the cosmological constant problem (why Λ is so small, yet nonzero and the coincidence problem (why Λ is comparable to the matter density now.
A natural cosmological constant from chameleons

Energy Technology Data Exchange (ETDEWEB)

Nastase, Horatiu, E-mail: nastase@ift.unesp.br [Instituto de Física Teórica, UNESP-Universidade Estadual Paulista, R. Dr. Bento T. Ferraz 271, Bl. II, Sao Paulo 01140-070, SP (Brazil); Weltman, Amanda, E-mail: amanda.weltman@uct.ac.za [Astrophysics, Cosmology & Gravity Center, Department of Mathematics and Applied Mathematics, University of Cape Town, Private Bag, Rondebosch 7700 (South Africa)

2015-07-30

We present a simple model where the effective cosmological constant appears from chameleon scalar fields. For a Kachru–Kallosh–Linde–Trivedi (KKLT)-inspired form of the potential and a particular chameleon coupling to the local density, patches of approximately constant scalar field potential cluster around regions of matter with density above a certain value, generating the effect of a cosmological constant on large scales. This construction addresses both the cosmological constant problem (why Λ is so small, yet nonzero) and the coincidence problem (why Λ is comparable to the matter density now)
On the constant-roll inflation

Science.gov (United States)

Yi, Zhu; Gong, Yungui

2018-03-01

The primordial power spectra of scalar and tensor perturbations during slow-roll inflation are usually calculated with the method of Bessel function approximation. For constant-roll or ultra slow-roll inflation, the method of Bessel function approximation may be invalid. We compare the numerical results with the analytical results derived from the Bessel function approximation, and we find that they differ significantly on super-horizon scales if the constant slow-roll parameter ηH is not small. More accurate method is needed for calculating the primordial power spectrum for constant-roll inflation.

Optical constants of CH3NH3PbBr3 perovskite thin films measured by spectroscopic ellipsometry

KAUST Repository

Alias, Mohd Sharizal

2016-07-14

The lack of optical constants information for hybrid perovskite of CH3NH3PbBr3 in thin films form can delay the progress of efficient LED or laser demonstration. Here, we report on the optical constants (complex refractive index and dielectric function) of CH3NH3PbBr3 perovskite thin films using spectroscopic ellipsometry. Due to the existence of voids, the refractive index of the thin films is around 8% less than the single crystals counterpart. The energy bandgap is around 2.309 eV as obtained from photoluminescence and spectrophotometry spectra, and calculated from the SE analysis. The precise measurement of optical constants will be useful in designing optical devices using CH3NH3PbBr3 thin films.
Measurement of elastic constants by simultaneously sensing longitudinal and shear waves as an overlapped signal

Energy Technology Data Exchange (ETDEWEB)

Seo, Ho Geon; Song, Dong Gi; Jhang, Kyoung Young [Hanyang University, Seoul (Korea, Republic of)

2016-04-15

Measurement of elastic constants is crucial for engineering aspects of predicting the behavior of materials under load as well as structural health monitoring of material degradation. Ultrasonic velocity measurement for material properties has been broadly used as a nondestructive evaluation method for material characterization. In particular, pulse-echo method has been extensively utilized as it is not only simple but also effective when only one side of the inspected objects is accessible. However, the conventional technique in this approach measures longitudinal and shear waves individually to obtain their velocities. This produces a set of two data for each measurement. This paper proposes a simultaneous sensing system of longitudinal waves and shear waves for elastic constant measurement. The proposed system senses both these waves simultaneously as a single overlapped signal, which is then analyzed to calculate both the ultrasonic velocities for obtaining elastic constants. Therefore, this system requires just half the number of data to obtain elastic constants compared to the conventional individual measurement. The results of the proposed simultaneous measurement had smaller standard deviations than those in the individual measurement. These results validate that the proposed approach improves the efficiency and reliability of ultrasonic elastic constant measurement by reducing the complexity of the measurement system, its operating procedures, and the number of data.
Measurement of elastic constants by simultaneously sensing longitudinal and shear waves as an overlapped signal

International Nuclear Information System (INIS)

Seo, Ho Geon; Song, Dong Gi; Jhang, Kyoung Young

2016-01-01

Measurement of elastic constants is crucial for engineering aspects of predicting the behavior of materials under load as well as structural health monitoring of material degradation. Ultrasonic velocity measurement for material properties has been broadly used as a nondestructive evaluation method for material characterization. In particular, pulse-echo method has been extensively utilized as it is not only simple but also effective when only one side of the inspected objects is accessible. However, the conventional technique in this approach measures longitudinal and shear waves individually to obtain their velocities. This produces a set of two data for each measurement. This paper proposes a simultaneous sensing system of longitudinal waves and shear waves for elastic constant measurement. The proposed system senses both these waves simultaneously as a single overlapped signal, which is then analyzed to calculate both the ultrasonic velocities for obtaining elastic constants. Therefore, this system requires just half the number of data to obtain elastic constants compared to the conventional individual measurement. The results of the proposed simultaneous measurement had smaller standard deviations than those in the individual measurement. These results validate that the proposed approach improves the efficiency and reliability of ultrasonic elastic constant measurement by reducing the complexity of the measurement system, its operating procedures, and the number of data
Translation of selected papers published in Nuclear Constants 5(59), 1984

International Nuclear Information System (INIS)

1987-06-01

The papers selected for this issue of the publication deal with the following topics: The Neutron Physics Constants Bank of the I.V. Kurchatov Institute of Atomic Energy - its structure and contents such as libraries, programs and data preparation codes for reactor calculations. A new version of the unified constant system package (called OKS) has been developed for access to constant systems, such as ARAMAKO-2F, in calculating radiation transport. Input language and performance are described. The group neutron data library GNDL is described in terms of structure, organization and basic data representation formats. The ARMAN'YAK code is described. Its calculation time, special features, and present state are briefly mentioned. Use of the code (for the preparation of constants for calculations and for compiling a library of files of nuclear concentrations) is indicated. A library of neutron data for calculating group constants - the FOND library - is described. The computerized library includes data on the 67 most important nuclear reactor and radiation shielding materials. Under the title ''The INDEhkS program and machine system'' a set of programs for the comparative analysis of calculated and experimental data from integral and macroscopic experiments is presented. The present status of the ARAMAKO multigroup constant calculation system for solving neutron and gamma quantum transport equations is reviewed. A method and a program for automatic preparation of few-group constants for reactor calculations in three-dimensional hexagonal geometry is proposed. A program (GRUKON) for calculating group constants on the basis of libraries of evaluated neutron data is presented. Evaluation of the methodical error in 26-group approximation is discussed. The accuracy of calculation of linear and bilinear functionals using a 26-group approximation is evaluated. A description is given of a five-group system of constants along with a status report on its development
The pulsed neutron method applied to the determination of the nuclear constants of graphite (1961); La methode des neutrons pulses appliquee a la determination des constantes nucleaires du graphite (1961)

Energy Technology Data Exchange (ETDEWEB)

Lalande, J [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1961-07-01

A method for determining the nuclear constants {sigma}{sub a} and {lambda}{sub t} of a moderator is described. The disappearance of a burst of neutrons introduced into a finite medium is studied as a function of time. This decrease in the thermal neutron density is the product of two exponentials; one representing the absorption, the other the leakage. By varying one or other of these factors, the constants of the factor left unvaried can be determined, and from this the nuclear constant values are deduced. (author) [French] On decrit une methode permettant de determiner les constantes nucleaires {sigma}{sub a} et {lambda}{sub t} d'un moderateur. On etudie la decroissance dans le temps d'une bouffee de neutrons introduite dans un milieu fini. Cette decroissance de la densite en neutrons thermiques est le produit de deux exponentielles; l'une represente l'absorption, l'autre les fuites. Par variation de l'un ou l'autre de ces facteurs, on determine les constantes du facteur laisse invariant dont on deduit les valeurs des constantes nucleaires. (auteur)
Single Machine Scheduling and Due Date Assignment with Past-Sequence-Dependent Setup Time and Position-Dependent Processing Time

Directory of Open Access Journals (Sweden)

Chuan-Li Zhao

2014-01-01

Full Text Available This paper considers single machine scheduling and due date assignment with setup time. The setup time is proportional to the length of the already processed jobs; that is, the setup time is past-sequence-dependent (p-s-d. It is assumed that a job's processing time depends on its position in a sequence. The objective functions include total earliness, the weighted number of tardy jobs, and the cost of due date assignment. We analyze these problems with two different due date assignment methods. We first consider the model with job-dependent position effects. For each case, by converting the problem to a series of assignment problems, we proved that the problems can be solved in On4 time. For the model with job-independent position effects, we proved that the problems can be solved in On3 time by providing a dynamic programming algorithm.
Constant Leverage And Constant Cost Of Capital: A Common Knowledge Half-Truth

Directory of Open Access Journals (Sweden)

Ignacio Vélez–Pareja

2008-04-01

In this document we show that for finite cash flows, Ke and hence WACC depend on the discount rate that is used to value the tax shield, TS and as expected, Ke and WACC are not constant with Kd as the discount rate for the tax shield, even if the leverage is constant. We illustrate this situation with a simple example. We analyze five methods: DCF using APV, FCF and traditional and general formulation for WACC, present value of CFE plus debt and Capital Cash Flow, CCF.
Time and amplitude dependent damping in a single crystal of zirconium

International Nuclear Information System (INIS)

Atrens, A.; Ritchie, I.G.; Sprungmann, K.W.; CEA Centre d'Etudes Nucleaires de Grenoble, 38

1977-01-01

The amplitude dependent and time dependent damping in a single crystal of zirconium has been investigated in the temperature range ambient to 400 0 C. The results are attributed to a combination of dislocation unpinning and pin rearrangement. After stabilization of the pin distribution by vibration conditioning, followed by a sudden large increase in amplitude, it is shown that the specimen retains a memory of the stabilized state
Asymptotic structure of space-time with a positive cosmological constant

Science.gov (United States)

Kesavan, Aruna

In general relativity a satisfactory framework for describing isolated systems exists when the cosmological constant Lambda is zero. The detailed analysis of the asymptotic structure of the gravitational field, which constitutes the framework of asymptotic flatness, lays the foundation for research in diverse areas in gravitational science. However, the framework is incomplete in two respects. First, asymptotic flatness provides well-defined expressions for physical observables such as energy and momentum as 'charges' of asymptotic symmetries at null infinity, [special character omitted] +. But the asymptotic symmetry group, called the Bondi-Metzner-Sachs group is infinite-dimensional and a tensorial expression for the 'charge' integral of an arbitrary BMS element is missing. We address this issue by providing a charge formula which is a 2-sphere integral over fields local to the 2-sphere and refers to no extraneous structure. The second, and more significant shortcoming is that observations have established that Lambda is not zero but positive in our universe. Can the framework describing isolated systems and their gravitational radiation be extended to incorporate this fact? In this dissertation we show that, unfortunately, the standard framework does not extend from the Lambda = 0 case to the Lambda > 0 case in a physically useful manner. In particular, we do not have an invariant notion of gravitational waves in the non-linear regime, nor an analog of the Bondi 'news tensor', nor positive energy theorems. In addition, we argue that the stronger boundary condition of conformal flatness of intrinsic metric on [special character omitted]+, which reduces the asymptotic symmetry group from Diff([special character omitted]) to the de Sitter group, is insufficient to characterize gravitational fluxes and is physically unreasonable. To obtain guidance for the full non-linear theory with Lambda > 0, linearized gravitational waves in de Sitter space-time are analyzed in
CMOS SPAD-based image sensor for single photon counting and time of flight imaging

OpenAIRE

Dutton, Neale Arthur William

2016-01-01

The facility to capture the arrival of a single photon, is the fundamental limit to the detection of quantised electromagnetic radiation. An image sensor capable of capturing a picture with this ultimate optical and temporal precision is the pinnacle of photo-sensing. The creation of high spatial resolution, single photon sensitive, and time-resolved image sensors in complementary metal oxide semiconductor (CMOS) technology offers numerous benefits in a wide field of applications....
Experimental measure of arm stiffness during single reaching movements with a time-frequency analysis

OpenAIRE

Piovesan, Davide; Pierobon, Alberto; DiZio, Paul; Lackner, James R.

2013-01-01

We tested an innovative method to estimate joint stiffness and damping during multijoint unfettered arm movements. The technique employs impulsive perturbations and a time-frequency analysis to estimate the arm's mechanical properties along a reaching trajectory. Each single impulsive perturbation provides a continuous estimation on a single-reach basis, making our method ideal to investigate motor adaptation in the presence of force fields and to study the control of movement in impaired ind...
New method for evaluating effective recovery time and single photoelectron response in silicon photomultipliers

Energy Technology Data Exchange (ETDEWEB)

Grodzicka, Martyna, E-mail: m.grodzicka@ncbj.gov.pl; Szczęśniak, Tomasz; Moszyński, Marek; Szawłowski, Marek; Grodzicki, Krystian

2015-05-21

The linearity of a silicon photomultiplier (SiPM) response depends on the number of APD cells and its effective recovery time and it is related to the intensity and duration of the detected light pulses. The aim of this study was to determine the effective recovery time on the basis of the measured SiPM response to light pulses of different durations. A closer analysis of the SiPM response to the light pulses shorter than the effective recovery time of APD cells led to a method for the evaluation of the single photoelectron response of the devices where the single photoelectron peak cannot be clearly measured. This is necessary in the evaluation of the number of fired APD cells (or the number of photoelectrons) in measurements with light pulses of various durations. Measurements were done with SiPMs manufactured by two companies: Hamamatsu and SensL.
Single-machine common/slack due window assignment problems with linear decreasing processing times

Science.gov (United States)

Zhang, Xingong; Lin, Win-Chin; Wu, Wen-Hsiang; Wu, Chin-Chia

2017-08-01

This paper studies linear non-increasing processing times and the common/slack due window assignment problems on a single machine, where the actual processing time of a job is a linear non-increasing function of its starting time. The aim is to minimize the sum of the earliness cost, tardiness cost, due window location and due window size. Some optimality results are discussed for the common/slack due window assignment problems and two O(n log n) time algorithms are presented to solve the two problems. Finally, two examples are provided to illustrate the correctness of the corresponding algorithms.
Difference equation approach to two-thermocouple sensor characterization in constant velocity flow environments

International Nuclear Information System (INIS)

Hung, P.C.; Irwin, G.; Kee, R.; McLoone, S.

2005-01-01

Thermocouples are one of the most popular devices for temperature measurement due to their robustness, ease of manufacture and installation, and low cost. However, when used in certain harsh environments, for example, in combustion systems and engine exhausts, large wire diameters are required, and consequently the measurement bandwidth is reduced. This article discusses a software compensation technique to address the loss of high frequency fluctuations based on measurements from two thermocouples. In particular, a difference equation (DE) approach is proposed and compared with existing methods both in simulation and on experimental test rig data with constant flow velocity. It is found that the DE algorithm, combined with the use of generalized total least squares for parameter identification, provides better performance in terms of time constant estimation without any a priori assumption on the time constant ratios of the thermocouples
Locus of the apices of projectile trajectories under constant drag

Science.gov (United States)

Hernández-Saldaña, H.

2017-11-01

Using the hodograph method, we present an analytical solution for projectile coplanar motion under constant drag, parametrised by the velocity angle. We find the locus formed by the apices of the projectile trajectories, and discuss its implementation for the motion of a particle on an inclined plane in presence of Coulomb friction. The range and time of flight are obtained numerically, and we find that the optimal launching angle is smaller than in the drag-free case. This is a good example of a problem with constant dissipation of energy that includes curvature; it is appropriate for intermediate courses of mechanics.
Equilibrium dialysis-ligand exchange: adaptation of the method for determination of conditional stability constants of radionuclide-fulvic acid complexes

International Nuclear Information System (INIS)

Glaus, M.A.; Hummel, W.; Van Loon, L.R.

1995-01-01

The equilibrium dialysis-ligand exchange technique (EDLE) is used to determine conditional stability constants for the complexation of metal ions with humic acid, particularly in high pH solutions. Here, this technique has been adapted to measure conditional stability constants with fulvic acid. Fulvic acid permeates across all membranes during the experiment. The quantities involved therefore have to be determined analytically and taken into account when calculating the conditional stability constants. Co(II) and Laurentian Soil fulvic (LFA) acid were selected as a test system in order to investigate the time scale required to establish chemical and diffusion equilibria. After an incubation time of approximately two days, the conditional stability constants measured for the formation of Co-LFA-complexes are not time dependent, although across the whole time period investigated, LFA was still diffusing in increasing amounts across the dialysis membrane. This work demonstrates that the modified EDLE technique can be used in the determination of conditional metal stability constants of fulvic acid. (authors)
Single determinantal reaction theory as a Schroedinger analog: the time-dependent S-matrix Hartree-Fock method

International Nuclear Information System (INIS)

Griffin, J.J.; Lichtner, P.C.; Dworzecka, M.; Kan, K.K.

1979-01-01

It is suggested that the TDHF method be viewed, not as an approximation to but as a model of the exact Schroedinger system; that is, as a gedanken many-body experiment whose analysis with digital computers provides data worthy in itself of theoretical study. From such a viewpoint attention is focused on the structural analogies of the TDHF system with the exact theory rather than upon its quantitative equivalence, and the TDHF many-body system is studied as a challenge of its own which, although much simpler than the realistic problem, may still offer complexity enough to educate theorists in the present state of knowledge. In this spirit, the TDHF description of continuum reactions can be restructured from an initial-value problem into a form analogous to the S-matrix version of the Schroedinger theory. The resulting TD-S-HF theory involves only self-consistent single determinantal solutions of the TDHF equations and invokes time averaging to obtain a consistent interpretation of the TDHF analogs of quantities which are constant in the exact theory, such as the S-matrix and the asymptotic reaction channel characteristics. Periodic solutions then play the role of stationary eigenstates in the construction of suitable asymptotic reaction channels. If these periodic channel states occur only at discrete energies, then the resulting channels are mutually orthogonal (on the time average) and the theory exhibits a structure fully analogous to the exact theory. In certain special cases where the periodic solutions are known to occur as an energy continuum, the requirement that the periodicity of the channel solutions be gauge invariant provides a natural requantization condition which (suggestively) turns out to be identical with the Bohr-Sommerfeld quantization rule. 11 references
The yield drop at or below 423 K in Zr single crystals and in Ti

International Nuclear Information System (INIS)

Ferron, A.; Malik, L.M.; Dickson, J.I.

1979-01-01

Yield drops were obtained in interrupted tensile and compression tests performed on zirconium single crystals between 262 and 362 K. Near 295 K, where most tests were performed, a minimum yield drop was obtained for an aging performed near the internal stress. For positive stress relaxations and a constant aging time, this yield drop increased linearly with the stress relaxed during aging. This result indicates a significant portion of the yield drop is caused by dislocations gliding to pinning points, which are most probably forest dislocations. A similar behaviour was observed for polycrystalline titanium at 423 K. The yield drops observed in the single crystals at 295 K, after aging at zero stress, increased linearly with the logarithm of the aging time in contrast to the time-independent Haasen-Kelly effect observed in polycrystalline material. (auth)
Spectrophotometric determination of association constant

DEFF Research Database (Denmark)

2016-01-01

Least-squares 'Systematic Trial-and-Error Procedure' (STEP) for spectrophotometric evaluation of association constant (equilibrium constant) K and molar absorption coefficient E for a 1:1 molecular complex, A + B = C, with error analysis according to Conrow et al. (1964). An analysis of the Charge...
Constant strength fuel-fuel cell

International Nuclear Information System (INIS)

Vaseen, V.A.

1980-01-01

A fuel cell is an electrochemical apparatus composed of both a nonconsumable anode and cathode; and electrolyte, fuel oxidant and controls. This invention guarantees the constant transfer of hydrogen atoms and their respective electrons, thus a constant flow of power by submergence of the negative electrode in a constant strength hydrogen furnishing fuel; when said fuel is an aqueous absorbed hydrocarbon, such as and similar to ethanol or methnol. The objective is accomplished by recirculation of the liquid fuel, as depleted in the cell through specific type membranes which pass water molecules and reject the fuel molecules; thus concentrating them for recycle use

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