Mutual Delay Research Articles

Probing exciton dynamics with spectral selectivity through the use of quantum entangled photons.

Quantum light is increasingly recognized as a promising resource for developing optical measurement techniques. Particular attention has been paid to enhancing the precision of the measurements beyond classical techniques by using nonclassical correlations between quantum entangled photons. Recent advances in the quantum optics technology have made it possible to manipulate spectral and temporal properties of entangled photons, and photon correlations can facilitate the extraction of matter information with relatively simple optical systems compared to conventional schemes. In these respects, the applications of entangled photons to time-resolved spectroscopy can open new avenues for unambiguously extracting information on dynamical processes in complex molecular and materials systems. Here, we propose time-resolved spectroscopy in which specific signal contributions are selectively enhanced by harnessing nonclassical correlations of entangled photons. The entanglement time characterizes the mutual delay between an entangled twin and determines the spectral distribution of photon correlations. The entanglement time plays a dual role as the knob for controlling the accessible time region of dynamical processes and the degrees of spectral selectivity. In this sense, the role of the entanglement time is substantially equivalent to the temporal width of the classical laser pulse. The results demonstrate that the application of quantum entangled photons to time-resolved spectroscopy leads to monitoring dynamical processes in complex molecular and materials systems by selectively extracting desired signal contributions from congested spectra. We anticipate that more elaborately engineered photon states would broaden the availability of quantum light spectroscopy.

Torsional Wave-Packet Dynamics in 2-Fluorobiphenyl Investigated by State-Selective Ionization-Detected Impulsive Stimulated Raman Spectroscopy.

We report the creation and observation of vibrational wave packets pertinent to torsional motion in a biphenyl derivative in its electronic ground-state manifold. Adiabatically cooled molecular samples of 2-fluorobiphenyl were irradiated by intense nonresonant ultrashort laser pulses to drive impulsive stimulated Raman excitation of torsional motion. Spectral change due to the nonadiabatic vibrational excitation is probed in a state-selective manner using resonance-enhanced two-photon ionization through the S1 ← S0 electronic transition. The coherent nature of the excitation was exemplified by adopting irradiation with a pair of pump pulses: observed signals for excited torsional levels exhibit oscillatory variations against the mutual delay between the pump pulses due to wave-packet interference. By taking the Fourier transform of the time course of the signals, energy intervals among torsional levels with v = 0-3 were determined and utilized to calibrate a density functional theory (DFT)-calculated torsional potential-energy function. Time variation of populations in the excited torsional levels was assessed experimentally by measuring integrated intensities of the corresponding transitions while scanning the delay. Early time enhancement of the population (up to ∼2 ps) and gradual degradation of coherence (within ∼20 ps) appears. To explain the observed distinctive features, we developed a four-dimensional (4D) dynamical calculation in which one-dimensional (1D) quantum-mechanical propagation of the torsional motion was followed by solving the time-dependent Schrödinger equation, whereas three-dimensional (3D) molecular rotation was tracked by classical trajectory calculations. This hybrid approach enabled us to reproduce experimental results at a reasonable computational cost and provided a deeper insight into rotational effects on vibrational wave-packet dynamics.

Objective Supervised Machine Learning-Based Classification and Inference of Biological Neuronal Networks.

The classification of biological neuron types and networks poses challenges to the full understanding of the human brain’s organisation and functioning. In this paper, we develop a novel objective classification model of biological neuronal morphology and electrical types and their networks, based on the attributes of neuronal communication using supervised machine learning solutions. This presents advantages compared to the existing approaches in neuroinformatics since the data related to mutual information or delay between neurons obtained from spike trains are more abundant than conventional morphological data. We constructed two open-access computational platforms of various neuronal circuits from the Blue Brain Project realistic models, named Neurpy and Neurgen. Then, we investigated how we could perform network tomography with cortical neuronal circuits for the morphological, topological and electrical classification of neurons. We extracted the simulated data of 10,000 network topology combinations with five layers, 25 morphological type (m-type) cells, and 14 electrical type (e-type) cells. We applied the data to several different classifiers (including Support Vector Machine (SVM), Decision Trees, Random Forest, and Artificial Neural Networks). We achieved accuracies of up to 70%, and the inference of biological network structures using network tomography reached up to 65% of accuracy. Objective classification of biological networks can be achieved with cascaded machine learning methods using neuron communication data. SVM methods seem to perform better amongst used techniques. Our research not only contributes to existing classification efforts but sets the road-map for future usage of brain–machine interfaces towards an in vivo objective classification of neurons as a sensing mechanism of the brain’s structure.

On a Discrete SEIR Epidemic Model with Two-Doses Delayed Feedback Vaccination Control on the Susceptible.

A new discrete susceptible-exposed-infectious-recovered (SEIR) epidemic model is presented subject to a feedback vaccination effort involving two doses. Both vaccination doses, which are subject to a non-necessarily identical effectiveness, are administrated by respecting a certain mutual delay interval, and their immunity effect is registered after a certain delay since the second dose. The delays and the efficacies of the doses are parameters, which can be fixed in the model for each concrete experimentation. The disease-free equilibrium point is characterized as well as its stability properties, while it is seen that no endemic equilibrium point exists. The exposed subpopulation is supposed to be infective eventually, under a distinct transmission rate of that of the infectious subpopulation. Some simulation examples are presented by using disease parameterizations of the COVID-19 pandemic under vaccination efforts requiring two doses.

Multiple Filamentation Effects on THz Radiation Pattern from Laser Plasma in Air

An experimental study of few filaments interaction impact on the terahertz radiation pattern has demonstrated that interaction of two close propagating beams leads to formation of a superfilament-like structure with on-axis terahertz yield. Mutual delay between two beamlets tilts the output intensity front of THz emission.

Delay Partial Synchronization of Mutual Delay Coupled Boolean Networks

This paper studies the delay partial synchronization for mutual delay-coupled Boolean networks. First, the mutual delay-coupled Boolean network model is presented. Second, some necessary and sufficient conditions are derived to ensure the delay partial synchronization of the mutual delay-coupled Boolean networks. The upper bound of synchronization time is obtained. Finally, an example is provided to illustrate the efficiency of the theoretical analysis.

Using of microwave photonic transversal filter for broadband signal direction estimation in microwave photonic beamforming system for linear phased array antennas

An approach is considered to estimate direction of arrival of broadband microwave signals in linear phased array antenna with photonic beamforming system by using additional subsystem – microwave photonic filter. The frequencies of the notches in the spectrum of broadband signal at the microwave photonic transversal filter output allow to measure mutual delay between signals from two antenna array elements, and thus providing estimation of the signal arrival angle . Architecture of the constructed transversal filter is based on the components of two analog fiber-optic links being a part of antenna array photonic beamforming system. Some shown results of test measurements of microwave photonic transversal filter characteristics prove out an operability of the technique.

Differential Ranging Method of Locating Satellite Communication System Earth Stations using Repeater on an Unmanned Aerial Vehicle

The article presents the differential ranging method of locating modern earth stations with narrow radiation patterns. Earth station position data is proposed to be calculated using maximum-likelihood procedure system solution from three differential equations using one of numerical methods. In this case supplementary assessment parameter of location, calculated by measuring a mutual signal delay of an earth station, relayed through a spacecraft on geostationary orbit and a mobile repeater on the unmanned aerial vehicle, can improve the accuracy of coordinate estimation earth station.
 For the developed method the analytical expressions of potential accuracy of calculation of coordinates of the earth station on the basis of the Cramer–Rao lower bound are developed.
 To measure the positioning accuracy of located emitters it is suggested to use the errors ellipsoid corresponding to the provision of a source of a radio emission in space.
 The analysis of standard routes of the movement of a repeater on the unmanned aerial vehicle is carried out and the conclusion is drawn that the best accuracy and the shortest route simultaneously are achieved, if the unmanned aerial vehicle follows a circular trajectory along the control area.
 Calculation of potential accuracy of positioning of the terrestrial station for the area of 50 by 50 km is executed.It is shown that the error of the estimates, received as a result of statistical tests, doesn’t surpass the size of a big half shaft of the error ellipsoid calculated with application of analytical expressions.
 The application of the developed method is possible in the implementation of the software of electronic control systems to counteract illegitimate use of frequency resource of space vehicles-satellite repeaters communication system.

In Vivo Antimalarial Activity of Adansonia digitata Stem Bark Extract and Some Fractions

Background: Malaria is one of the most common major health problems responsible for the death of millions of children, pregnant women and adults. Antimalarial drug resistance has emerged as one of the greatest challenges facing malaria control today. Plant resources that either treat or prevent parasite invasion desirable in developing countries are potential targets for research and development of alternative malaria drugs. Objective: This study investigated the suppressive and prophylactic potentials of extracts and some fractions of Adansonia digitata stem bark in Plasmodium berghei infected mice. Methodology: The albino mice were administered with two different doses (200mg/kg body weight and 400mg/kg body weight) of aqueous extract (AQ), methanolic extract (ME), chloroform fraction (CF) and ethylacetate fraction (EF) of Adansonia digitata stem bark for five consecutive days. 5mg/kg body weight dose per day of artemether-lumefantrine and 5mg/kg body weight dose per day of chloroquine was used as positive control while the negative control mice received only the vehicle (5% v/v tween 80). In the prophylactic groups, the mice were pretreated daily for five days before they were challenged with inoculums of 1 x 107 chloroquine-sensitive P. berghei infected erythrocyte intraperitoneally. Results: The results showed a dose dependent chemosupression in the fractions and the extract treated groups. The 400mg/kg body weight was more effective with respect to the parasite clearance than the 200mg/kg body weight in all the groups. Both the 200mg/kg and 400mg/kg body weight dose of ethylacetate fraction (EF) exhibited the highest chemosupression. The chemosupression caused by Artemether-lumefantrine (AL) and Chloroquine (CQ) treated groups were significantly (P> 0.05) higher than the fractions and extract treated groups. The percentage parasitemia also decreased in this manner. There was a mutual delay in parasitemia with EF and ME. The packed cell volume (PCV) increased significantly (P> 0.05) in the AL and CQ, and 400mg/kg body weight dose EF and ME respectively and increased for the other fraction and extract used at 400mg/kg body weight dose compared with the control. Conclusion: This study showed that EF of Adansonia digitata stem bark has potent antimalarial property which could be of future importance in malaria management.

Dynamics of lossless polarization attraction

We study a nonlinear lossless polarizer (NLP), a fiber-based device able to control the polarization of an optical signal while preserving its energy. The NLP exploits the lossless polarization attraction (LPA) generated by the Kerr interactions between the signal and a fully polarized continuous wave (CW) pump. By employing a copropagating pump, we show that the effectiveness of LPA depends on the joint action of the Kerr nonlinearity and the mutual delay between signal and pump. We find the optimal pump wavelength placement and demonstrate that true LPA occurs only within a limited range of delay values. Thus, we explain why the copropagating NLP is more flexible and power efficient compared with the traditional counterpropagating NLP.

Ultrafast laser pump X-ray probe experiments by means of asynchronous sampling

A high time resolution in the picosecond range is required for the time-domain investigation of phonon dynamics in crystalline systems. Following a recently developed scheme in the visible spectrum, this resolution can be achieved by a method called asynchronous optical x-ray sampling (ASOXS). A pulsed femtosecond laser with high repetition rate is synchronized to the electron bunches in a storage ring. A slight frequency detuning changes the mutual delay continuously, resulting in a time-domain x-ray sampling of the laser-excited system. At the synchrotron radiation source ANKA a machine mode with low momentum compaction factor αc is available, which delivers ultra-short x-ray pulses in the picosecond range.

Pengaruh Total Aktiva, Jumlah Sekuritas, Perputaran Portofolio, Laba/Rugi Operasi Dan Opini Akuntan Terhadap Audit Delay Pada Produk Reksa Dana Di Indonesia

AbstrackThis study empirically examined the effect of several company & audit characteristics on audit report lag or audit delay. Determinants of audit delay in mutual funds were chosen as an object of investigation. The purpose of this study to reveal that those variables have significant effect on audit delay simultaneously or partially. Samples are selected by purposive sampling method. The results of multiple linear regressions show that all of the explanatory variables influences audit delay simultaneously. The rest of variables do not appear to have any bearing on mutual fund audit delay. This Result is suggested for auditor to perform the audit more efficient and effective to get audit report timely, for BAPEPAM-LK as regulator to review again the deadline of audited financial statements delivery of mutual funds, for the future researcher to be reference in developing investigation.

Zero-lag synchronization and multiple time delays in two coupled chaotic systems

Zero-lag synchronization (ZLS) between two chaotic systems coupled by a portion of their signal is achieved for restricted ratios between the delays of the self-feedback and the mutual coupling. We extend this scenario to the case of a set of multiple self-feedbacks {Ndi} and a set of multiple mutual couplings {Ncj}. We demonstrate both analytically and numerically that ZLS can be achieved when SigmaliNdi+igmamjNcj=0, where li,mj(epsilon)Z. Results which were mainly derived for Bernoulli maps and exemplified with simulations of the Lang-Kobayashi differential equations, indicate that ZLS can be achieved for a continuous range of mutual coupling delay. This phenomenon has an important implication in the possible use of ZLS in communication networks.

Zero Lag Synchronization of Chaotic Systems with Time Delayed Couplings

Zero-lag synchronization (ZLS) between chaotic units, which do not have self-feedback or a relay unit connecting them, is experimentally demonstrated for two mutually coupled chaotic semiconductor lasers. The mechanism is based on two mutual coupling delay times with certain allowed integer ratios, whereas for a single mutual delay time ZLS cannot be achieved. This mechanism is also found numerically for mutually coupled chaotic maps where its stability is analyzed using the Schur-Cohn theorem for the roots of polynomials. The symmetry of the polynomials allows only specific integer ratios for ZLS. In addition, we present a general argument for ZLS when several mutual coupling delay times are present.

Coherent noise compensation in Spectral-Domain optical coherence tomography

An efficient technique for the separation of and compensation for coherent noise in spectral optical coherence tomography with parallel spectrum detection is proposed and validated. The coherent noise is separated during one exposure by modulating the mutual delay of the signal and reference waves by a certain law. It is shown that the influence of internal motions in an object on the quality of the coherent noise separation can be reduced by the modulation frequency increasing. The technique has been numerically and experimentally validated with the help of an optical coherence tomography (OCT) setup with a radiation source operating at a wavelength of 1277 nm and a width of the recorded spectrum of about 100 nm.

Distributed optical fibre sensing of temperature using time-correlated two-photon excited fluorescence: theoretical overview

The general theory of a distributed temperature sensor based on time-correlated two-photon excited fluorescence in doped optical fibre is presented. Counter-propagating excitation pulses generate a two-photon excited fluorescence flash at their overlap which can be scanned along the length of the fibre by means of a variable mutual delay. The temperature at the sensed location is obtained using the decay time of the fluorescence from this position. As the power of the fluorescence flash is shown to be completely independent of excitation pulse duration and temporal profile, the sensor does not require a picosecond or femtosecond excitation source for operation. Background fluorescence may be reduced by optimising pulse shape and duration, or eliminated entirely by suitable combinations of the pulse wavelengths and the absorption spectrum of the doped medium.

Imaging by Means of an Immobile Antenna Array, Noise Signals and SAR Method

It is developed a new method of SAR imaging through the use of noise/random signals and a fixed and non-switching antenna array as suggested in [1]. The main idea of the method consists in the separation from the total signal of the single-channel receiver of that its portion, which is radiated by a separate element of the array. Such extraction is performed using correlation reception of the noise/random signals transmitted and received by the antenna array with mutual delay between the antenna elements, which is exceeding the correlation time of the transmitted signal. The advantage of the suggested method for SAR imaging consists in the non-necessity of either mechanical moving or electronic switching of the antenna array elements, which simplifies its design and cuts the costs. The SAR imaging algorithm is described and the results of PC modeling of SAR using the proposed antenna array are presented.

Application of correlation techniques in the analysis of corpus cavernosum electromyographic signals

To establish an objective, easy-to-use and comprehensive method to analyze corpus cavernosum electromyographic signals (CC-potentials). CC-potentials were recorded during flaccidity in 23 young healthy volunteers, with surface electrodes placed on the penile shaft bilaterally. Based on the correlation function of Matlab software, an application program for the analysis of CC-potentials was developed. Individual CC-potentials and their autocorrelation function were evaluated, yielding parameters amplitude (A), duration (D), and dominant frequency (DF). The cross-correlation function of both longitudinal and bilateral pairs of adjacent electrodes was calculated to assess the similarity and mutual delay of CC-potentials recorded simultaneously from different parts of the CC. The parameters derived were squared maximum cross-correlation coefficient (Rmax) and delay (tau). Based on the absolute value of tau and the corresponding inter-electrode distance, propagation velocity (PV) was calculated. The values of the parameters were determined automatically. No significant difference related to the locations of the electrodes for parameters A, D, and DF was detected. The cross-correlation showed that both longitudinal and bilateral CC-potential pairs had highly similar waveforms (the absolute values of Rmax were 0.80 +/- 0.05 and 0.87 +/- 0.06, respectively). PV of longitudinal pairs was estimated as 6.15 +/- 3.98 cm/s. The application program for correlation analysis of CC-potentials is a comprehensive and versatile method to analyze corpus cavernosum electromyographic recordings. Its objectiveness makes multi-center application possible.

Use of nonlinear spectral estimation in the problem of determining the mutual delay of signals

We consider an algorithm of nonlinear spectral estimation based on the maximum-entropy method using the procedure of explicit obtaining of the Lagrange multipliers with reference to the problem of determining the time and frequency shifts of radio signals of communication systems. Modification of a method for constructing the uncertainty function on the basis of a nonlinear algorithm of spectral estimation with a fixed body of computations is proposed.

Model of a multiple-line distributed-feedback dye laser.

The theoretical basis for simultaneous oscillation of 2N - 3 laser lines is due to interference of N (for all even N > or = 2) pump beams in a distributed-feedback dye laser is described. Multiple gratings are produced in a dye solution by interference patterns of N/2 pairs of a frequency-doubled Nd:YAG laser. N/2 pairs of mutually time-delayed pulses induce multiple gratings of different periodicities, of which 2N - 3 gratings support oscillation of 2N - 3 lines and the remaining gratings, because of their larger periods, cannot support Bragg scattering. The maximum number of laser lines depends on the mutual delay between adjacent pairs of beams, coherence, states of polarization, pulse lengths, and of course the number of pulses. For three pairs of excitation beams derived from the same source through wave-front or amplitude phase division techniques, the output lasing lines varied from a minimum of three to a maximum of nine. This research was carried out by pumping of a dye solution with two, four, and six pulses, but the principle may be extended to multiple output lines, depending on the number of pump pulses and on the gain of the dye solution.