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structure function in photoplethysmographic signal dynamics for physiological assessment

Scientific Reports 2025年第1期15卷 1-16页

作者： de Pedro-Carracedo, Javier Fuentes-Jimenez, David Cabrera-Umpiérrez, María Fernanda González-Marcos, Ana Pilar Life Supporting Technologies (LifeSTech) ETSI Telecomunicación Universidad Politécnica de Madrid (UPM) Madrid E-28040 Spain Escuela Politécnica Superior Departamento de Automática Universidad de Alcalá (UAH) Alcalá de Henares (Madrid) E-28871 Spain Escuela Politécnica Superior Departamento de Electrónica Universidad de Alcalá (UAH) Alcalá de Henares (Madrid) E-28871 Spain

Physiological systems are inherently complex, driven by non-linear interactions among various subsystems that govern their function across diverse spatiotemporal scales. Understanding this interconnectedness is crucial;in this sense, the structure function enables us to dissect the dynamic intricacies of biological responses. By examining amplitude fluctuations across different timescales, we can gain valuable insights into the variability and adaptability of these vital systems. A structure function serves as an essential tool for uncovering long-term correlations that highlight self-organizing behavior. Additionally, it effectively examines the fractal characteristics of short-term signals influenced by the measurement noise often present in biological data. This paper presents a novel investigation into how various parameters of the structure function of the PhotoPlethysmoGraphic (PPG) signal can serve as reliable physiological biomarkers indicative of an individual’s cardiorespiratory activity level. Preliminary tests on 40 students from the Universidad Politécnica de Madrid (UPM), all young and healthy individuals aged between 19 and 30, yielded promising results. These findings enhance our understanding of PPG signal dynamics from a physiological standpoint and provide a procedural framework for real-time patient monitoring and health assessment in clinical environments. © The Author(s) 2025.

关键词： Complexity Physiological biomarkers PPG signal structure function

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structure function of the nucleus in the perturbative QCD with N_c → ∞ (BFKL pomeron fan diagrams)

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EUROPEAN PHYSICAL JOURNAL C 2000年第2期16卷 337-347页

作者： Braun, M St Petersburg State Univ Dept High Energy Phys St Petersburg 198904 Russia

The equation for the sum of BFKL pomeron fan diagrams is rederived by a direct summation and solved numerically for rapidities y less than or equal to 50. At high rapidities, y > 20, the resulting cross-sections for the scattering of a longitudinally polarized q (q) over bar pair on the nucleus cease to depend on its transverse dimension and tend to a constant limit of 0.1768R(A)(2), which corresponds to scattering of a color dipole on a black disk. Thus the unitarity is restored and the singularity in the j plane is reduced to a simple pole at j = 1. The nuclear structure function at small x behaves as Q(2)1n(1/x). The gluon density found has a soliton-like form in the log k space: its form is close to Gaussian, independent of rapidity, the center moving towards higher log k with a nearly constant velocity as the rapidity, increases.

关键词： structure function High Rapidity Constant Velocity Nuclear structure Simple Pole

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structure function for aliasing patterns in 2^l-n design with multiple groups of factors

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ANNALS OF STATISTICS 2003年第3期31卷 995-1011页

作者： Zhu, Y Purdue Univ Dept Stat W Lafayette IN 47907 USA

A general approach to studying fractional factorial designs with multiple groups of factors is proposed. A structure function is generated by the defining contrasts among different groups of factors and the remaining columns. The structure function satisfies a first-order partial differential equation. By solving this equation, general results about the structures and properties of the designs are obtained. As an important application, practical rules for the selection of "optimal" single arrays for robust parameter design experiments are derived.

关键词： fractional factorial design complementary designs wordtype pattern structure index structure function

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structure function Estimated From Histological Tissue Sections

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IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL 2016年第9期63卷 1296-1305页

作者： Han, Aiguo O'Brien, William D., Jr. Univ Illinois Dept Elect & Comp Engn Bioacoust Res Lab 1406 W Green St Urbana IL 61801 USA

Ultrasonic scattering is determined by not only the properties of individual scatterers but also the correlation among scatterer positions. The role of scatterer spatial correlation is significant for dense medium, but has not been fully understood. The effect of scatterer spatial correlation may be modeled by the structure function as a frequency-dependent factor in the backscatter coefficient (BSC) expression. The structure function has been previously estimated from the BSC data. The aim of this study is to estimate the structure function from histology to test if the acoustically estimated structure function is indeed caused by the scatterer spatial distribution. Hematoxylin and eosin stained histological sections from dense cell pellet biophantoms were digitized. The scatterer positions were determined manually from the histological images. The structure function was calculated from the extracted scatterer positions. The structure function obtained from histology showed reasonable agreement in the shape but not in the amplitude, compared with the structure function previously estimated from the backscattered data. Fitting a polydisperse structure function model to the histologically estimated structure function yielded relatively accurate cell radius estimates (error < 15%). Furthermore, two types of mouse tumors that have similar cell size and shape but distinct cell spatial distributions were studied, where the backscattered data were shown to be related to the cell spatial distribution through the structure function estimated from histology. In conclusion, the agreement between acoustically estimated and histologically estimated structure functions suggests that the acoustically estimated structure function is related to the scatterer spatial distribution.

关键词： Acoustic scattering backscatter coefficient histology quantitative ultrasound structure function

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structure function representation of multidirectional heat-flows

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IEEE TRANSACTIONS ON COMPONENTS AND PACKAGING TECHNOLOGIES 2007年第4期30卷 643-652页

作者： Codecasa, Lorenzo Politecn Milan Dipartimento Elettron & Informaz I-20133 Milan Italy

The relation between the structure function of a one-port dynamic thermal network and the spatial distribution of thermal properties in a heat diffusion problem with applied boundary conditions is generalized from 1-D heat flows to multidirectional heat flows. A strategy for exploiting this relation is derived which allows an accurate localization of defects and measurement of thermal properties in components and packages not only when the heat diffusion problem is I-D but also 3-D.

关键词： multidirectional heat flow one-port passive dynamic thermal network structure function

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structure function AS A CHARACTERISTIC OF GEOPHYSICAL FIELDS

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STUDIA GEOPHYSICA ET GEODAETICA 1973年第4期17卷 295-299页

作者： VYSKOCIL, V CZECHOSLOVAK ACAD SCI GEOPHYS INST BOCNI 2 141 31 PRAGUE 4 CZECHOSLOVAKIA

Facts about the statistical properties of random fields may be obtained by analysing their increments (i.e. the differences of values at two points). The properties of structure functions are described and the possibi... 详细信息

关键词： structure function Random Field Structural Geology Statistical Homogeneity Geophysical Field

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structure function: Theory, Ultrasonic Measurement, and Histology

Structure Function: Theory, Ultrasonic Measurement, and Hist...

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IEEE International Ultrasonics Symposium (IUS)

作者： Han, Aiguo O'Brien, William D., Jr. Univ Illinois Dept Elect & Comp Engn Urbana IL 61801 USA

ISBN: (纸本)9781479981823

Ultrasonic scattering is determined by not only the properties of individual scatterers, but also the correlation among scatterer positions. The role of scatterer spatial correlation is significant for dense medium, but has not been fully understood. The effect of scatterer spatial correlation may be modeled by a structure function (three-dimensional Fourier transform of the scatterer positions) as a frequency-dependent factor in the backscatter coefficient (BSC) expression. To study the structure function, we have performed three steps: 1) we developed theoretical structure function models that take into account the polydispersity of spherical scatterers;2) we developed the cell pellet biophantom technique to estimate the structure function from ultrasound backscattered data (11 - 105 MHz);3) we developed algorithms for estimating the structure function from histology, independent of the acoustic measurements. The acoustically estimated and histologically estimated structure functions show consistent frequency dependency, which demonstrates the correlation between acoustically estimated structure function and scatterer position distribution observed in histology. Furthermore, fitting the theoretical polydisperse structure function model to the experimental structure functions yielded relatively accurate cell radius estimates (error < 16%). Our results suggest that the structure function is required for accurately modeling the acoustic scattering in dense medium.

关键词： structure function acoustic scattering dense medium histology quantitative ultrasound

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structure function Based Methods in Evaluation of Availability of Healthcare system 10

Structure Function Based Methods in Evaluation of Availabili...

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10th International Conference on Dependable Systems, Services and Technologies (DESSERT)

作者： Rusnak, Patrik Sedlacek, Peter Forgac, Andrej Illiashenko, Oleg Kharchenko, Vyacheslav Univ Zilina Fac Management Sci & Informat Zilina Slovakia Natl Aerosp Univ KhAI Dept Comp Syst Networks & CyberSecur Kharkov Ukraine

ISBN: (纸本)9781728117331

Reliability analysis is important properties of any system and healthcare system too. The healthcare system has some specifics in reliability analysis. One of them is the heterogeneity, because this system includes components with different background, kind and properties (for example, equipment and human factor). Other specific of healthcare system is great influence of human factor. Typically, the influence of human factor is evaluated by special methods from special part of reliability engineering that is known as Human Reliability Analysis (HRA). But these methods can not be used for evaluation of technical part (components) of healthcare system. In this paper new method for healthcare system evaluation is developed. This method is proposed for the quantitative analysis of healthcare system and, in particular, for Importance Analysis of this system. It is based on the application of mathematical representation that is named Multi-State System (MSS) to indicate some (more than only two) performance levels in investigated system for more details analysis. In this paper the representation of healthcare system in form of Multi-Valued Decision Diagram is used, that typically used for the system of large dimension.

关键词： reliability analysis reliability structure function reliability function structure measure human reliability analysis healthcare system

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structure function evaluation of stacked dies

Structure function evaluation of stacked dies

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20th Annual IEEE Semiconductor Thermal Measurement and Management Symposium

作者： Rencz, M Szekely, V MicReD Ltd. Hungary Budapest Univ. of Technol./Economics Hungary

ISBN: (纸本)078038363X

In this paper simulation experiments demonstrate, that the structure function evaluation of the thermal transient testing is capable to locate die attach failure(s) of stacked die packages. The strength and the location of the die attach failure may be determined with the methodology of a fast thermal transient measurement and the subsequent computer evaluation. The special advantage of the methodology is that normally it does not require any additional circuit elements on any of the dies of the stacked die structure. The paper demonstrates the feasibility of the method both for stacked die structures of the same die size, and for pyramidal stacked die packages.

关键词： thermal transient testing die attach quality structure function reliability testing

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A Kolmogorov-Brutsaert structure function model for evaporation into a turbulent atmosphere

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WATER RESOURCES RESEARCH 2017年第5期53卷 3635-3644页

作者： Katul, Gabriel Liu, Heping Duke Univ Nicholas Sch Environm Durham NC 27708 USA Duke Univ Dept Civil & Environm Engn Durham NC 27706 USA Washington State Univ Dept Civil & Environm Engn Pullman WA 99164 USA

In 1965, Brutsaert proposed a model that predicted mean evaporation rate E from rough surfaces to scale with the 3/4 power law of the friction velocity (u ) and the square- root of molecular diffusivity (Dm) for water vapor. In arriving at these results, a number of assumptions were made regarding the surface renewal rate describing the contact durations between eddies and the evaporating surface, the diffusional mass process from the surface into eddies, and the cascade of turbulent kinetic energy sustaining the eddy renewal process itself. The working hypothesis explored here is that E ffiffiffiffiffiffiffi Dm p u 3= 4 is a direct outcome of the Kolmogorov scaling for inertial subrange eddies modified to include viscous cutoff thereby bypassing the need for a surface renewal assumption. It is demonstrated that Brutsaert's model for E may be more general than its original derivation implied. Plain Language Summary The movement of water vapor molecules from rough surfaces such as soils by eddies into the atmosphere is of primary significance to a plethora of applications including hydrological and meteorological forecasting, irrigation planning, energy partitioning, and subsequent growth of the atmospheric boundary layer, to name a few. In 1965, W. Brutsaert proposed a general model that links the movement of water vapor molecules from the surface to the molecular diffusivity of water vapor in air and the wind- induced shear stress at the surface. The derivation considered air packets sweeping down and coming in contact with the wet surface. When in contact with the surface, these packets become enriched with water vapor molecules during a finite contact duration, after which these packets are ejected from the surface. Brutsaert made key restrictive assumptions about the statistical properties of the contact duration of these packets with the surface to arrive at the final form of the evaporation equation. The work here demonstrates that the same result can be deriv

关键词： evaporation turbulent atmosphere surface renewal Kolmogorov structure function

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