Pulse Fluctuations Research Articles

Mind-enlightenment and observation: Analysis of ancient and modern weird pulse diagrams in " Guidelines for Disease Detection "

<p>脈診，是中醫重要的診斷方法。醫者手觸脈動引發主觀的判讀，因抽象體會難以言說，故歷來做了許多努力。早期以文字譬喻為主描述脈象，至宋代施發《察病指南》增見具象的脈象圖示。文章以七怪脈為主，比對古脈圖與現代脈儀圖，尋其特點與限制，或能為新世代的診斷尋找更合宜的時代範式。研究發現，古脈圖是傳統脈診心象運思的表徵，有輔助文字的重要作用。科技脈儀圖，則以心臟或血液動力學為基礎，如實記錄脈搏的波動訊號，從時域到高低頻譜以揭露生理病理的訊息。比較兩者，可各見特點與限制：古圖提供他人藉以揣摩，難以盡言的脈覺體會，其譬喻文圖的運用所載意義更為豐富固是優勢所在；然也因非邏輯性的傳訊而形成多樣的表達，這非客觀化的限制，正是當代醫家的修正努力與科診儀器強調的優處。另一方面，儀器診察雖有客觀、標準化的特點，但其測值是否能涵蓋生命的整體現象亦有質疑聲音。故兩者該並行析究：在傳統理論與現代儀器之間，嘗試建構一套能銜接古今的替代理論，或許能為新世代的脈診量測，提供一個較為周全的診斷依據。而中醫的脈圖分析能進入當代，參與W.J.T.Mitchell圖像轉向中，生物圖像研究的子題是無疑的。</p> <p> </p><p>This article mainly focuses on the seven weird pulses, compares ancient pulse diagrams and modern pulse diagrams, and seeks out their characteristics and limitations, hoping to find a more suitable paradigm for the diagnosis of the new generation. Research has found that ancient pulse diagrams are representations of mental images and thoughts in traditional pulse diagnosis, and play an important role in supporting text. The technological pulse chart is based on heart or hemodynamics and faithfully records pulse fluctuation signals from time domain to high and low frequency spectrum to reveal physiological and pathological information. Comparing the two, we can see the characteristics and limitations of each: the ancient pictures provide others with an indescribable pulse-sensing experience, and the use of metaphors and pictures contains richer meanings, which is an advantage; however, it is also illogical Forming diverse expressions through communication, this non-objectification limitation is exactly the advantage emphasized by the revision efforts of contemporary doctors and medical diagnostic equipment. On the other hand, although instrumental diagnosis has the characteristics of being objective and standardized, there are also doubts about whether its measured values can cover the overall phenomenon of life. Therefore, the two should be analyzed in parallel: between traditional theory and modern instruments, trying to construct an alternative theory that can connect ancient and modern times may provide a more comprehensive diagnostic basis for pulse diagnosis and measurement in the new generation. The pulse diagram analysis of TCM can enter the contemporary era and participate in W.J.T. Mitchell’s pictorial turn. There is no doubt that it is a sub-topic of biological image research.</p> <p> </p>

Flickering pulsations in bright X-ray pulsars: the evidence of gravitationally lensed and eclipsed accretion column

ABSTRACT It is expected that the extreme mass accretion rate onto strongly magnetized neutron stars results in the appearance of accretion columns above the stellar surface. For a distant observer, rotation of a star results in periodic variations of X-ray flux. Because the mass accretion rate fluctuates around the average value, the pulse profiles are not stable and demonstrate fluctuations as well. In the case of bright X-ray pulsars, however, pulse fluctuations are not solely attributed to variations in the mass accretion rate. They are also influenced by the variable height of the columns, which is dependent on the mass accretion rate. This study delves into the process of pulse profile formation in bright X-ray pulsars, taking into account stochastic fluctuations in the mass accretion rate, the corresponding variations in accretion column geometry, and gravitational bending. Our analysis reveals that potential eclipses of accretion columns by a neutron star during their spin period should manifest specific features in pulse profile variability. Applying a novel pulse profile analysis technique, we successfully detect these features in the bright X-ray transient V 0332+53 at luminosities $\gtrsim 2\times 10^{38}\, {\rm erg\ \rm s^{-1}}$. This detection serves as compelling evidence for the eclipse of an accretion column by a neutron star. Detection of the eclipse places constraints on the relation between neutron star mass, radius, and accretion column height. Specifically, we can establish an upper limit on the accretion column height, which is crucial for refining theoretical models of extreme accretion.

A randomized measurement toolbox for an interacting Rydberg-atom quantum simulator

We present a toolbox to probe quantum many-body states implemented on Rydberg-atoms quantum hardware via randomized measurements. We illustrate the efficacy of this measurement toolbox in the context of probing entanglement, via the estimation of the purity, and of verifying a ground-state preparation using measurements of the Hamiltonian variance. To achieve this goal, we develop and discuss in detail a protocol to realize independent, local unitary rotations. We benchmark the protocol by investigating the ground state of the one-dimensional Su–Schrieffer–Heeger model, recently realized on a chain of Rydberg atom, and the state resulting after a sudden quench in a staggered XY chain. We probe the robustness of our toolbox by taking into account experimental imperfections, such as pulse fluctuations and measurement errors.

Combined Method of Intensification of Borehole Uranium Mining in Ores with Low Filtration Characteristics

The purpose of this study is to develop an effective method for increasing the filtration characteristics of ores during borehole uranium mining, depending on the geological characteristics of ores and host rocks. At the same time, it is planned to increase the productivity of production and the pick-up rate of injection wells, increase the period of uninterrupted operation of equipment and reduce operating costs for production. The geotechnological parameters of borehole uranium mining on technological blocks of various mining and geological conditions are investigated and evaluated. Core material samples were taken and the structures and compositions of the host rocks of the Santonian, Maastrichtian and Campanian ore intervals were determined by microscopic method. Based on a comparative analysis of the methods used to intensify borehole production, a combined method for restoring the permeability of the productive horizon was developed. The effective parameters of the combined well regeneration method combining fluctuations of compressed air pulses with chemical reagents – solvents are calculated and justified. The possibility of reducing the processing time of wells by a new method and increasing the productivity of wells is discussed. The method of calculation and application of the combined method of intensification of borehole production of uranium in ores with low filtration characteristics has been developed.

Study of physiological and pathological information mining with biological information similarity analysis

Chronic diseases, such as sleep apnea and Parkinson's disease, are characterized by insidious onset, complex etiology, slow course, and easy-to-cause other complications, which seriously affect life quality of the patients. Real-time monitoring of biological information can effectively reveal the occurrence and development of chronic diseases. It also helps in aspects of early diagnosis and treating options. In current study, the dynamic change rules of biological signals caused by chronic diseases have been explored, from which one can realize the auxiliary diagnosis and evaluation of these diseases. Attention has been focused on physiological fluctuation and coordination of biological information similarity, including pulse fluctuation detection in patients with sleep apnea and plantar pressure coordination assessment in patients with Parkinson's disease. In the biological similarity study, the heart rate from sleep apnea patients has been recorded two minutes before and after breath pulse. Information of the average plantar pressure from both foot of Parkinson patients has also been recorded and analyzed. Results show that: for sleep apnea patients, their heart rate fluctuation level has significantly reduced. That is because the human body enhances its sympathetic nerve activity to open the airway. The heart rate starts to change periodically, resulting in its fluctuations tending to be consistent. Compared with ordinary people, PD patients have weaker biological information similarities of plantar pressure on one foot. Also, information similarity between left and right feet of PD patients was more diversified. It revealed that the left and right foot plantar pressure fluctuated more and tended to be more consistent together with gait disorder and weakened balance. Such results show that the similarity of biological information can effectively excavate the fluctuation and coordination of physiological signals, and effectively contribute to the recognition and auxiliary diagnosis of chronic diseases. Data mining methods applied here helps to explore the physiological and pathological mechanism of the studied chronic diseases and sheds light on early diagnosis and severity assessment. It becomes more promising to develop algorithms, software, and hardware systems that is helpful for patients and facilitate promotion of human life quality and health cause.

Analysis of the Heart Rate of Operators of Forwarding Machines during Work Activities

The aim of this work was to determine the dependence of the heart rate of operators of forwarding machines on the activities performed during the working day within the framework of timber forwarding and to compare individual activities in terms of the level of physical workload. For this purpose, the work shift of operators carrying out timber forwarding was divided into individual activities: driving, maintenance, forwarding, and break. During these work activities, the heart rate of each operator was taken for subsequent evaluation. A portable device, a Garmin smartwatch, was used to measure their heart rate. The results show that the highest pulse rates of the operators occurred during the maintenance of the entrusted machine, while the highest pulse fluctuations were recorded during forwarding. During this activity, the highest heart rate of the entire measurement process was recorded (132.0000 bpm), but also the lowest (42.0000 bpm). Furthermore, it was proven that both the operator and the activity he performs affect the pulse rate. The activities themselves did not differ from each other in only one of the six cases of comparison, specifically, between driving and forwarding.

Free electron laser stochastic spectroscopy revealing silicon bond softening dynamics

Time-resolved x-ray emission/absorption spectroscopy (Tr-XES/XAS) is an informative experimental tool sensitive to electronic dynamics in materials, widely exploited in diverse research fields. Typically, Tr-XES/XAS requires x-ray pulses with both a narrow bandwidth and subpicosecond pulse duration, a combination that in principle finds its optimum with Fourier transform-limited pulses. In this work, we explore an alternative experimental approach, capable of simultaneously retrieving information about unoccupied (XAS) and occupied (XES) states from the stochastic fluctuations of broadband extreme ultraviolet pulses of a free electron laser. We used this method, in combination with singular-value decomposition and Tikhonov regularization procedures, to determine the XAS/XES response from a crystalline silicon sample at the ${L}_{2,3}$ edge, with an energy resolution of a few tens of meV. Finally, we combined this spectroscopic method with a pump-probe approach to measure structural and electronic dynamics of a silicon membrane. Tr-XAS/XES data obtained after photoexcitation with an optical laser pulse at 390 nm allowed us to observe perturbations of the band structure, which are compatible with the formation of the predicted precursor state of a nonthermal solid-liquid phase transition associated with a bond softening phenomenon.

A Fuzzy Controller for PFN Trigger Time Sequence in Electromagnetic Railgun System

For the electromagnetic launch system, how to realize the wide pulse, fast rise, and small fluctuation of pulse forming network output current is a core problem. A trigger time sequence control method based on fuzzy theory for the pulse forming network is proposed in this paper. First, circuit models of pulse forming unit, pulse forming network, and electromagnetic rail launcher is established. Second, a fuzzy trigger time sequence controller model for pulse forming network is designed by using Simulink. Third, fixed time sequence discharge tests consisting of 20 pulsed forming units on the linear simulation load are carried out to verify the accuracy of the simulation model. Finally, discharge tests on the linear simulation load and launch tests on the electromagnetic railgun are carried out to verify the precision of the fuzzy controller output respectively. The results show that the designed fuzzy trigger time sequence controller can obtain the ideal trigger time sequence, which demonstrates the pragmatic and reliability of fuzzy control algorithm.

Numerical investigation on inherent pulse-energy fluctuations in the noise-like pulse mode-locked fiber laser

The pulse-energy fluctuations of noise-like pulses (NLPs) are investigated by numerical simulations for modeling the all-normal dispersion Yb-doped fiber lasers. The intracavity distributions of the pulse-energy fluctuations are presented for the fiber lasers based on the Gaussian filter and saturable absorbers (SAs) with monotonic or sinusoidal transmission curves. The results show that the pulse-energy fluctuations in the cavity are at the minimum after the gain fibers due the gain saturation effect, especially when the pulse energy is close to the saturation energy in the gain fiber. Moreover, in the case of the sinusoidal SA, the pulse-energy fluctuations can be effectively decreased by properly choosing the spectral bandwidth and transmission profile of the filter and the modulation depth of the SA.

The role of instrumental markers in assessment of microcirculation of type 2 diabetes mellitus patients

Introduction. The development of diagnostic techniques of diabetes mellitus microvascular complications is an urgent task. One such method is laser Doppler flowmetry (LDF). Purpose was to analyze the correlations of clinical and laboratory parameters and LDF spectral parameters in patients with type 2 diabetes mellitus. Materials and methods. The study involved 50 patients with type 2 diabetes and diabetic foot syndrome. Microcirculation was assessed using the BIOPAC LDF 100C system. In parallel, monitoring of transcutaneous oximetry in the probed area was carried out using the TCM400 device. For correlation analysis, the Spearman correlation coefficient was used. Results. While studying, a positive correlation was noted between the contribution of pulse fluctuations and the duration of diabetes (p<0.05). For the level of glycosylated hemoglobin, it was positively correlated with the value of the contribution of pulsed fluxmotions and negatively correlated with the contribution of low-frequency fluxmotions and the fluxmotion index (p<0.05). When assessing transcutaneous oxygen tension, a negative correlation was found with the value of the contribution of pulse fluxmotions (p<0.05). These correlations can be explained in the light of modern concepts of the pathogenesis of type 2 diabetes mellitus microvascular complications. Conclusion. In the course of the work, spectral parameters of LDF were found correlated with clinical, laboratory, and instrumental parameters. The dynamics of changes in LDF parameters corresponds to the ideas about the pathogenesis of diabetic microangiopathy. A promising direction for further research is the study of the progressive development of diabetic microangiopathy and the role of individual pathogenetic factors in this process.

Transient absorption microscopy setup with multi-ten-kilohertz shot-to-shot subtraction and discrete Fourier analysis.

Recording of transient absorption microscopy images requires fast detection of minute optical density changes, which is typically achieved with high-repetition-rate laser sources and lock-in detection. Here, we present a highly flexible and cost-efficient detection scheme based on a conventional photodiode and an USB oscilloscope with MHz bandwidth, that deviates from the commonly used lock-in setup and achieves benchmark sensitivity. Our scheme combines shot-to-shot evaluation of pump-probe and probe-only measurements, a home-built photodetector circuit optimized for low pulse energies applying low-pass amplification, and a custom evaluation algorithm based on Fourier transformation. Advantages of this approach include abilities to simultaneously monitor multiple pulse modulation frequencies, implement the detection of additional pulse sequences (e.g., pump-only), and expand to multiple parallel detection channels for wavelength-dispersive probing. With a 40 kHz repetition-rate laser system powering two non-collinear optical parametric amplifiers for wide tuneability, we find that laser pulse fluctuations limit the sensitivity of the setup, while the detection scheme has negligible contribution. We demonstrate the 2-D imaging performance of our transient absorption microscope with studies on micro-crystalline molecular thin films.

1 μm few-cycle pulse generation in a single-stage gas-filled hollow core fiber

We demonstrate a simple and compact spectral broadening system, which is based on a single-stage gas-filled hollow core fiber (HCF). In our experiment, the pulse duration of pulses from an ytterbium doped amplifier is compressed from 170 fs down to 7.7 fs by using a 3-m-long gas-filled HCF with a core diameter of 500 μm. The pulse energy before and after HCF is 2 mJ and 0.92 mJ respectively, corresponding to a transmission efficiency of 46%, resulting in peak power of near 0.1 TW. In addition, the energy fluctuation of the output pulse is about 0.5%(RMS) measured in one hour. Such ultrafast light source can provide high stable few-cycle near-infrared driving pulses for strong field physics experiments.

Geoelectric field response characteristics analysis of floor roadway surrounding rock fracture caused due to coal seam mining

The fracture of rocks surrounding the floor roadway during the mining of the working face of a coal mine is a complicated spatiotemporal process due to the superimposed action of multiple stress fields on the surrounding rock mass. Using the surrounding rock of a floor roadway in the working face of the Huainan Pan’er Mine as the research subject, we conducted real-time monitoring using geoelectric field monitoring technology, and found the spatiotemporal response law of the geoelectric field in the process of regional rupture and damage of engineering rock masses under a complex stress field environment. The results show that (1) the time series response characteristics and spatial distribution of the geoelectric field signal are closely related to the stress distribution and damage evolution of the surrounding rock mass; (2) the rupture and damage degree of the goaf floor significantly increased when the working face was pushed through the monitoring area for 20–40 m. During this process, the excitation current dropped by 4–12 mA, and the self-potential pulse fluctuation amplitude was greater than 400 mV; (3) from the beginning of the monitoring process to the end of the monitoring, the self-potential in the damaged area decreased by 250 mV, and the self-potential in the mudstone layer below the damaged area increased by 140 mV. The electrons released into the environment around the damaged rock mass during the severe impact phase of mining did not flow back to the damaged area, and the positive charge in the damaged rock mass gradually accumulated in the complete rock mass in units of rock strata; (4) when superimposed and supported by anchor rod and cables, the bearing capacity of the shallow bearing circle of the roadway was enhanced, and the excitation current presented a step-like overall increase during mining of the working face with a small drop after every significant increase. This result is of significance in monitoring the evolutionary process of real-time failure of rock masses under complex stress environments using geoelectric field information and in improving the quality of geoelectric field monitoring technology testing applications in the future.

Pulse regulation by additional attenuation in a random erbium-doped fiber laser utilizing EOM and stimulated Brillouin scattering

In this paper, pulse regulation by the combination of actively Q-switched and passively Q-switched mechanisms in a random erbium-doped fiber laser is demonstrated. Pulse shape is regulated from square wave to quasi passively Q-switched pulse by changing pump power and loss in laser cavity. Pulse shape similar to external modulation signal on electro-optic modulator (EOM) is achieved when the pump power is low. When the pump power is increased and an additional attenuation is inserted, a regular and stable output pulse is generated by the combination of EOM and stimulated Brillouin scattering (SBS) in fiber. The frequency irregular and intensity fluctuation of pulse shown in passively Q-switched random fiber lasers reported previously are greatly eliminated. Not only pulse amplitude and pulse width are controlled by pump power and additional attenuation in the cavity, but also the repetition rate of output pulse is controlled by the external modulation signal on EOM, which has great potential applications in high-resolution imaging, and next-generation laser medical treatment.

High-Fidelity Geometric Gates with Single Ions Doped in CrystalsSupported by the National Natural Science Foundation of China (Grant No. 11974336), and the National Key Research and Development Program of China (Grant No. 2017YFA0304100).

Single rare-earth ions doped in solids are one kind of the promising candidates for quantum nodes towards a scalable quantum network. Realizing a universal set of high-fidelity gate operations is a central requirement for functional quantum nodes. Here we propose geometric gate operations using the hybridized states of electron spin and nuclear spin of an ion embedded in a crystal. The fidelities of these geometric gates achieve 0.98 in the realistic experimental situations. We also show the robustness of geometric gates to pulse fluctuations and to environment decoherence. These results provide insights for geometric phases in dissipative systems and show a potential application of high fidelity manipulations for future quantum internet nodes.

Flexible ptychography platform to expand the potential of imaging at free electron lasers.

Ptychography, a scanning coherent diffraction imaging method, can produce a high-resolution reconstruction of a sample and, at the same time, of the illuminating beam. The emergence of vacuum ultraviolet and X-ray free electron lasers (FELs) has brought sources with unprecedented characteristics that enable X-ray ptychography with highly intense and ultra-fast short-wavelength pulses. However, the shot-to-shot pulse fluctuations typical for FEL pulses and particularly the partial spatial coherence of self-amplified spontaneous emission (SASE) FELs lead to numerical complexities in the ptychographic algorithms and ultimately restrict the application of ptychography at FELs. We present a general adaptive forward model for ptychography based on automatic differentiation, which is able to perform reconstructions even under these conditions. We applied this model to the first ptychography experiment at FLASH, the Free electron LASer in Hamburg, and obtained a high-resolution reconstruction of the sample as well as the complex wavefronts of individual FLASH pulses together with their coherence properties. This is not possible with more common ptychography algorithms.

Development of an optimization method for measuring the Doppler frequency of a packet taking into account the fluctuations of the initial phases of its radio pulses

The necessity of estimating the decrease in the accuracy of measuring the informative parameters of a radar signal in real conditions of its propagation and reflection has been substantiated. The results of the estimation determine the requirements for optimizing this measurement to achieve the required efficiency. A numerical analysis of the decrease in the accuracy of measuring the Doppler frequency of a coherent packet is presented, depending on the statistical characteristics of fluctuations of the initial phases of its radio pulses. Expressions are given for calculating the fluctuation component of the measurement error of radio pulse packet frequency for various coefficients of interpulse correlation of phase fluctuations. An assessment is made of the possibility of increasing the accuracy of Doppler frequency measurement, which can be ensured by statistical optimization of the algorithm for time-frequency processing of a given radar signal by taking into account its phase fluctuations. The conditions for the multiplicative influence of phase fluctuations of radio pulses of the received packet are substantiated, which determine the efficiency of optimization of Doppler frequency measurement. Based on the results of the study, an optimization method for measuring the Doppler frequency of the packet taking into account fluctuations in the initial phases of its radio pulses is proposed. The accuracy of Doppler frequency measurement under the influence of both the internal noise of the radar receiver and the correlated phase fluctuations of its radio pulses is estimated. The efficiency of optimization of measuring the Doppler frequency of the packet is estimated taking into account fluctuations of the initial phases of its radio pulses by means of computer simulation. It is proved that, under the influence of phase fluctuations, the accuracy of Doppler frequency measurement can be increased due to the performed optimization from 1.86 to 6.29 times. This opens the way to improving the existing algorithms for measuring the higher time range derivatives to improve the quality of tracking complex maneuvering aerodynamic objects. This explains the importance and usefulness of the work for the radar theory.

Quantifying the impact of pump noise on fiber-optic nonlinear processes

The impact of pump pulse fluctuations on ultrafast nonlinear frequency conversion processes in optical fibers is investigated. A simple measure of the sensitivity of a particular process to pump technical noise is introduced and tested against numerical ensemble simulations for normal-dispersion continuum generation and dispersive-wave generation. The proposed measure is found to adequately describe the impact of technical noise at the per mill or percent level.

Study of temporal, spectral, arrival time and energy fluctuations of SASE FEL pulses.

Self-amplified spontaneous emission (SASE) pulses delivered by free electron lasers (FELs) are inherently fluctuating sources; each pulse varies in energy, duration, arrival time and spectral shape. Therefore, there is strong demand for a full characterization of the properties of SASE radiation, which will facilitate more precise interpretation of the experimental data taken at SASE FELs. In this paper, we present an investigation into the fluctuations of pulse duration, spectral distribution, arrival time and pulse energy of SASE XUV pulses at FLASH, both on a shot-to-shot basis and on average over many pulses. With the aid of simulations, we derived scaling laws for these parameters and disentangled the statistical SASE fluctuations from accelerator-based fluctuations and measurement uncertainties.

Broadband femtosecond spectroscopic ellipsometry.

We present a setup for time-resolved spectroscopic ellipsometry in a pump-probe scheme using femtosecond laser pulses. As a probe, the system deploys supercontinuum white light pulses that are delayed with respect to single-wavelength pump pulses. A polarizer-sample-compensator-analyzer configuration allows ellipsometric measurements by scanning the compensator azimuthal angle. The transient ellipsometric parameters are obtained from a series of reflectance-difference spectra that are measured for various pump-probe delays and polarization (compensator) settings. The setup is capable of performing time-resolved spectroscopic ellipsometry from the near-infrared through the visible to the near-ultraviolet spectral range at 1.3 eV-3.6 eV. The temporal resolution is on the order of 100 fs within a delay range of more than 5 ns. We analyze and discuss critical aspects such as fluctuations of the probe pulses and imperfections of the polarization optics and present strategies deployed for circumventing related issues.