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1
Zhdanov, V., i O. Stashko. "Hubble parameter in f(R)-gravity". Bulletin of Taras Shevchenko National University of Kyiv. Astronomy, nr 61 (2020): 22–25. http://dx.doi.org/10.17721/btsnua.2020.61.22-25.
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In view of the famous problem with the “Hubble constant tension” there is a number of approaches to modify the cosmological equations and correspondingly modify Hubble parameter H(z) in order to to relieve the tension between the “early” and “late” Hubble constants. f(R)– gravity is one of such possible modifications. We discuss how to choose the Lagrangian in the f(R)– gravity on account of observational data within the homogeneous isotropic cosmology. The equation is obtained that enable us to derive f(R) for given Hubble parameter H(z). This yields a second order differential equation with corresponding degrees of freedom. If H(z) corresponds to that obtained from usual Friedmann equations, this equation yields a condition for f(R) to mimic the observable quantities of the standard ΛCDM with the above-mentioned freedom. To reduce this freedom on needs additional considerations, which involve the other observable quantities, such as those which appear in considerations of cosmological perturbations on the isotropic and homogeneous background. Also, we consider the reverse problem to find for given f(R). This is fulfilled within an approximation in case of small deviation of f(R) from the General Relativity value.
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Csuka, Barna, i Zsolt Kollár. "R–DFT-based Parameter Estimation for WiGig". Periodica Polytechnica Electrical Engineering and Computer Science 61, nr 2 (23.05.2017): 224. http://dx.doi.org/10.3311/ppee.9737.
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In this paper we present parameter estimation methods for IEEE 802.11ad transmission to estimate the frequency offset value and channel impulse response. Furthermore a less known low complexity signal processing architecture – the Recursive Discrete Fourier Transform (R-DFT) – is applied which may improve the estimation results. The paper also discusses the R-DFT and its advantages compared to the conventional Fast Fourier Transform.
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Sabol, George V. "Clark Unit Hydrograph and R‐Parameter Estimation". Journal of Hydraulic Engineering 114, nr 1 (styczeń 1988): 103–11. http://dx.doi.org/10.1061/(asce)0733-9429(1988)114:1(103).
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Hoppe, Jens. "r-Functions with quasi-dynamical spectral parameter". Letters in Mathematical Physics 31, nr 4 (sierpień 1994): 255–59. http://dx.doi.org/10.1007/bf00762787.
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Wang, Zikun. "Multi-parameter infinitedimensional (r, δ)-OU process". Chinese Science Bulletin 44, nr 5 (marzec 1999): 418–23. http://dx.doi.org/10.1007/bf02977878.
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Chen, Jiao, Liang Huang i Guozhen Lu. "Hörmander Fourier multiplier theorems with optimal Besov regularity on multi-parameter Hardy spaces". Forum Mathematicum 33, nr 6 (21.10.2021): 1605–27. http://dx.doi.org/10.1515/forum-2021-0201.
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Abstract We will establish the boundedness of the Fourier multiplier operator T m f T_{m}f on multi-parameter Hardy spaces H p ( R n 1 × ⋯ × R n r ) H^{p}(\mathbb{R}^{n_{1}}\times\cdots\times\mathbb{R}^{n_{r}}) ( 0 < p ≤ 1 0<p\leq 1 ) when the multiplier 𝑚 is of optimal smoothness in multi-parameter Besov spaces B 2 , q ( s 1 , … , s r ) ( R n 1 × ⋯ × R n r ) B^{{(s_{1},\ldots,s_{r})}}_{2,q}(\mathbb{R}^{n_{1}}\times\cdots\times\mathbb{R}^{n_{r}}) , where T m f ( x ) = ∫ R n 1 × ⋯ × R n r m ( ξ ) f ^ ( ξ ) e 2 π i x ⋅ ξ d ξ T_{m}f(x)=\int_{\mathbb{R}^{n_{1}}\times\cdots\times\mathbb{R}^{n_{r}}}m(\xi)\hat{f}(\xi)e^{2\pi ix\cdot\xi}\,d\xi for x ∈ R n 1 × ⋯ × R n r x\in{\mathbb{R}^{n_{1}}\times\cdots\times\mathbb{R}^{n_{r}}} . We will show ∥ T m ∥ H p → H p ≲ sup j 1 , … , j r ∈ Z ∥ m j 1 , … , j r ∥ B 2 , q ( s 1 , … , s r ) , \lVert T_{m}\rVert_{H^{p}\to H^{p}}\lesssim\sup_{j_{1},\ldots,j_{r}\in\mathbb{Z}}\lVert m_{j_{1},\ldots,j_{r}}\rVert_{B^{{(s_{1},\ldots,s_{r})}}_{2,q}}, where 0 < q < ∞ 0<q<\infty and s i > n i ( 1 p - 1 2 ) s_{i}>n_{i}\bigl{(}\frac{1}{p}-\frac{1}{2}\bigr{)} . Here we have used the notation m j 1 , … , j r ( ξ ) = m ( 2 j 1 ξ 1 , … , 2 j r ξ r ) ψ ( 1 ) ( ξ 1 ) ⋯ ψ ( r ) ( ξ r ) , m_{j_{1},\ldots,j_{r}}(\xi)=m(2^{j_{1}}\xi_{1},\ldots,2^{j_{r}}\xi_{r})\psi^{(1)}(\xi_{1})\cdots\psi^{(r)}(\xi_{r}), and ψ ( i ) ( ξ i ) \psi^{(i)}(\xi_{i}) is a suitable cut-off function on R n i \mathbb{R}^{n_{i}} for 1 ≤ i ≤ r 1\leq i\leq r . This multi-parameter Hörmander multiplier theorem is in the spirit of the earlier work of Baernstein and Sawyer in the one-parameter setting and sharpens our recent result of Hörmander multiplier theorem in the bi-parameter case which was established using R. Fefferman’s boundedness criterion. Because R. Fefferman’s boundedness criterion fails in the cases of three or more parameters, it is substantially more difficult to establish such Hörmander multiplier theorems in three or more parameters than in the bi-parameter case. To assume only the optimal smoothness on the multipliers, delicate and hard analysis on the sharp estimates of the square functions on arbitrary atoms are required. Our main theorems give the boundedness on the multi-parameter Hardy spaces under the smoothness assumption of the multipliers in multi-parameter Besov spaces and show the regularity conditions to be sharp.
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Arnold, Manuel, Andreas M. Brandmaier i Manuel C. Voelkle. "Predicting Differences in Model Parameters with Individual Parameter Contribution Regression Using the R Package ipcr". Psych 3, nr 3 (6.08.2021): 360–85. http://dx.doi.org/10.3390/psych3030027.
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Unmodeled differences between individuals or groups can bias parameter estimates and may lead to false-positive or false-negative findings. Such instances of heterogeneity can often be detected and predicted with additional covariates. However, predicting differences with covariates can be challenging or even infeasible, depending on the modeling framework and type of parameter. Here, we demonstrate how the individual parameter contribution (IPC) regression framework, as implemented in the R package ipcr, can be leveraged to predict differences in any parameter across a wide range of parametric models. First and foremost, IPC regression is an exploratory analysis technique to determine if and how the parameters of a fitted model vary as a linear function of covariates. After introducing the theoretical foundation of IPC regression, we use an empirical data set to demonstrate how parameter differences in a structural equation model can be predicted with the ipcr package. Then, we analyze the performance of IPC regression in comparison to alternative methods for modeling parameter heterogeneity in a Monte Carlo simulation.
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Волков, Сергій Леонідович. "Binomial parameter R estimation in Clopper-Pearson method". Technology audit and production reserves 6, nr 3(8) (12.12.2012): 23–24. http://dx.doi.org/10.15587/2312-8372.2012.5519.
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Popławski, Nikodem J. "The cosmic snap parameter in f ( R ) gravity". Classical and Quantum Gravity 24, nr 11 (22.05.2007): 3013–20. http://dx.doi.org/10.1088/0264-9381/24/11/014.
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Jhang, Jhy‐Ping, i Shi‐Hao Lin. "The Optimal Parameter Design of CD‐R Substrate". Asian Journal on Quality 6, nr 2 (21.08.2005): 105–15. http://dx.doi.org/10.1108/15982688200500016.
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Bracken, Anthony J., Mark D. Gould i Yao-Zhong Zhang. "Quantised affine algebras and parameter-dependent R-matrices". Bulletin of the Australian Mathematical Society 51, nr 2 (kwiecień 1995): 177–94. http://dx.doi.org/10.1017/s0004972700014040.
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Let Uq(G(1)) be a quantised non-twisted affine Lie algebra with Uq(G) the corresponding quantised simple Lie algebra. Using the previously obtained universal R-matrices for and , explicitly spectral-dependent universal R-matrices for Uq(A1) and Uq(A2) are determined. These spectral-dependent universal R-matrices are evaluated in some concrete representations; well-known results for the fundamental representations are reproduced, and an explicit formula for the spectral-dependent R-matrix associated with the V(3) ⊗ V(6) module is derived, where V(3) and V(6) carry the 3- and 6-dimensional representations of Uq(A2), respectively.
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Asgarani, Somayeh, i Behrouz Mirza. "Two-parameter entropies, Sk,r, and their dualities". Physica A: Statistical Mechanics and its Applications 417 (styczeń 2015): 185–92. http://dx.doi.org/10.1016/j.physa.2014.09.045.
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Popławski, Nikodem J. "The cosmic jerk parameter in f(R) gravity". Physics Letters B 640, nr 4 (wrzesień 2006): 135–37. http://dx.doi.org/10.1016/j.physletb.2006.07.056.
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K, Dr Gnanaprasunamba. "EFFECT OF BROWNIAN MOTION AND THERMOPHORESIS ON NANOFLUID PAST A STRETCHING SURFACE WITH VARIABLE VISCOSITY AND NEWTONIAN COOLING INSPIRED BY THERMAL RADIATION". YMER Digital 21, nr 04 (4.04.2022): 21–34. http://dx.doi.org/10.37896/ymer21.04/03.
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We analyze the combined influence of Brownian motion, thermophopresis, with past a stretching surface with variable viscosity and thermal radiation. The governing equations have been solved by employing fifth-order Runge-Kutta-Fehlberg method along with shooting technique. The effects of various parameters on the velocity, temperature and concentration as well as on the local skin-friction coefficient, local Nusselt number and local Sherwood number are presented graphically and discussed. It is observed that a velocities component increases with Hall parameter(m), Brownian motion parameter (Nb), Radiation parameter (Rd), Viscosity parameter (r), Convective heat transfer constant(h1), reduces with thermophoresis parameter (Nt). Nusselt number increase in r and reduces Nu and Sh, increase in r/h1 reduces rate of heat transfer and enhances mass transfer.
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Geng, Chao-Qiang, Yan-Ting Hsu i Jhih-Rong Lu. "Constraints on Non-Flat Starobinsky f(R) Dark Energy Model". Entropy 23, nr 10 (10.10.2021): 1320. http://dx.doi.org/10.3390/e23101320.
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We study the viable Starobinsky f(R) dark energy model in spatially non-flat FLRW backgrounds, where f(R)=R−λRch[1−(1+R2/Rch2)−1] with Rch and λ representing the characteristic curvature scale and model parameter, respectively. We modify CAMB and CosmoMC packages with the recent observational data to constrain Starobinsky f(R) gravity and the density parameter of curvature ΩK. In particular, we find the model and density parameters to be λ−1<0.283 at 68% C.L. and ΩK=−0.00099−0.0042+0.0044 at 95% C.L., respectively. The best χ2 fitting result shows that χf(R)2≲χΛCDM2, indicating that the viable f(R) gravity model is consistent with ΛCDM when ΩK is set as a free parameter. We also evaluate the values of AIC, BIC and DIC for the best fitting results of f(R) and ΛCDM models in the non-flat universe.
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Sharif, M., i M. Zubair. "Analysis off(R)Theory Corresponding to NADE and NHDE". Advances in High Energy Physics 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/790967.
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We develop the connection off(R)theory with new agegraphic and holographic dark energy models. The functionf(R)is reconstructed regarding thef(R)theory as an effective description for these dark energy models. We show the future evolution offand conclude that these functions represent distinct pictures of cosmological eras. The cosmological parameters such as equation of state parameter, deceleration parameter, statefinder diagnostic, andw−w′analysis are investigated which assure the evolutionary paradigm off.
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Jing, Naihuan, i Ming Liu. "$$R$$ R -Matrix Realization of Two-Parameter Quantum Group $$U_{r,s}(\mathfrak {gl}_n)$$ U r , s ( gl n )". Communications in Mathematics and Statistics 2, nr 3-4 (grudzień 2014): 211–30. http://dx.doi.org/10.1007/s40304-014-0037-7.
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Elbashbeshy, E. MA. "Radiation effect on heat transfer over a stretching surface". Canadian Journal of Physics 78, nr 12 (1.12.2000): 1107–12. http://dx.doi.org/10.1139/p00-085.
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We determine the effect of radiation on the forced convection flow of an optically dense incompressible fluid along a heated horizontal stretching surface. The boundary-layer equations are transformed to ordinary differential equations containing a radiation parameter R*, velocity exponent parameter M, Prandtl number P r, and surface temperature parameter θ ω. The effect of these parameters are studied. Graphical results for the velocity and temperature are presented and discussed. PACS Nos.: 44.40+a, 47.27-i
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Zhao, Lina, Jianqing Li, Xiangkui Wan, Shoushui Wei i Chengyu Liu. "Determination of Parameters for an Entropy-Based Atrial Fibrillation Detector". Entropy 23, nr 9 (11.09.2021): 1199. http://dx.doi.org/10.3390/e23091199.
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Entropy algorithm is an important nonlinear method for cardiovascular disease detection due to its power in analyzing short-term time series. In previous a study, we proposed a new entropy-based atrial fibrillation (AF) detector, i.e., EntropyAF, which showed a high classification accuracy in identifying AF and non-AF rhythms. As a variation of entropy measures, EntropyAF has two parameters that need to be initialized before the calculation: (1) tolerance threshold r and (2) similarity weight n. In this study, a comprehensive analysis for the two parameters determination was presented, aiming to achieve a high detection accuracy for AF events. Data were from the MIT-BIH AF database. RR interval recordings were segmented using a 30-beat time window. The parameters r and n were initialized from a relatively small value, then gradually increased, and finally the best parameter combination was determined using grid searching. AUC (area under curve) values from the receiver operator characteristic curve (ROC) were compared under different parameter combinations of parameters r and n, and the results demonstrated that the selection of these two parameters plays an important role in AF/non-AF classification. Small values of parameters r and n can lead to a better detection accuracy than other selections. The best AUC value for AF detection was 98.15%, and the corresponding parameter combinations for EntropyAF were as follows: r = 0.01, n = 0.0625, 0.125, 0.25, or 0.5; r = 0.05 and n = 0.0625, 0.125, or 0.25; and r = 0.10 and n = 0.0625 or 0.125.
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Jiang, Ying, Zhongxu Han, Qian Zhang, Weiqiang Yang, Yabo Wu, Jinyang Li, Han Lou, Chenchen Zhao i Yan Wang. "Model Independent Diagnostics in Interacting Dark Energy Models". Universe 6, nr 4 (30.03.2020): 49. http://dx.doi.org/10.3390/universe6040049.
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In this paper, we have explored non-gravitational interaction dark energy model between dark energy and cold dark matter (CDM). The main purpose of this work is to explore the deviations from Λ C D M and to distinguish the evolution trajectory of the interaction dark energy model with different parameters. Six forms of interaction were focused on. We have analyzed the deceleration parameters of the coupled model and explored the theoretical models through s t a t e f i n d e r h i e r a r c h y and the O m diagnostic. We have considered that the Equation of State (EoS) parameter w and parameter ξ take different values on the interaction dark energy model respectively and keep another parameter unchanged. It was found that q ( z ) is the worst of the four diagnoses. O m , S 3 ( 1 ) and S 4 ( 1 ) are good tools to distinguish the interaction dark energy model from Λ C D M . S 3 ( 1 ) is a better diagnostic tool when the state parameter w changes and the coupling parameter ξ is fixed, while S 4 ( 1 ) works better when the coupling parameter ξ changes and the state parameter w is fixed.
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Bhaduri, S. B. "An interpretation of thermal shock resistance parameter R⁗ in light of R-curve behaviour". Journal of Materials Science Letters 12, nr 8 (styczeń 1993): 594–95. http://dx.doi.org/10.1007/bf00278335.
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Almeida, Sara Regina Meira, Luciano Bruno C. Silva, Carlos Alberto M. Guerreiro i Anamarli Nucci. "Amyotrophic lateral sclerosis: prospective study on respiratory parameters". Arquivos de Neuro-Psiquiatria 68, nr 2 (kwiecień 2010): 258–62. http://dx.doi.org/10.1590/s0004-282x2010000200020.
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OBJECTIVE: To verify how efficient respiratory parameters are in the follow-up of subjects with amyotrophic lateral sclerosis (ALS) and to observe possible correlations between respiratory and nutritional functions. METHOD: Sixteen patients with probable or defined ALS were selected and evaluated over eight months using the following respiratory parameters: spirometry, maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), arterial gasometry and pulse oximetry; and nutritional parameters such as body mass index (BMI) and percentage weight loss. RESULTS: PaCO2 was a significant parameter to follow up disease evolution (p=0.051). There was significant correlation between MIP and MEP (r: 0.83); BMI and MIP (r: 0.70); BMI and MEP (r: 0.72); pulse oximetry and forced vital capacity (r: 0.57). CONCLUSION: PaCO2 was shown to be an efficient and significant parameter in the measurement of respiratory impairment; the correlations among MIP, MEP and BMI indicated that these are significant parameters for periodic clinical evaluation.
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Wang, Chunguang, Yangyang Cui, Shiquan Ge, Mingyu Sun i Zhirong Jia. "Experimental Study on Vortex-Induced Vibration of Risers Considering the Effects of Different Design Parameters". Applied Sciences 8, nr 12 (28.11.2018): 2411. http://dx.doi.org/10.3390/app8122411.
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Risers are an indispensable component of offshore oil and gas exploitation structures, and they are vulnerable to vortex-induced vibration (VIV). Although many studies have been conducted to investigate the VIV characteristics of risers, the effects of combination of multiple parameters and the relative significance of each parameter on the risers’ VIV characteristics have rarely been considered. In this paper, 36 experimental cases were investigated to study the risers’ VIV characteristics due to the combination of multiple parameters. The natural frequencies, response microstrains and frequencies of VIV for the risers were obtained. Meanwhile, the effect of each parameter and the relative significance of these parameters on the amplitude of VIV in risers were calculated using grey relational analysis (GRA). The results show that all the parameters considered—i.e., material property (modulus and density), end condition, top tension force and flow velocity—affect risers’ VIV response, and the grey relational grade of these parameters are: r 02 ( velocity ) > r 04 ( constraints ) > r 05 ( density ) > r 03 ( tension ) > r 01 ( modulus ) .
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Tiwari, Rishi Kumar, i Değer Sofuoğlu. "Quadratically varying deceleration parameter in f(R,T) gravity". International Journal of Geometric Methods in Modern Physics 17, nr 10 (26.08.2020): 2030003. http://dx.doi.org/10.1142/s0219887820300032.
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In this paper, we have proposed a new form for the varying deceleration parameter that is a generalization of the form of Ö. Akarsu and T. Dereli [Cosmological models with linearly varying deceleration parameter, Int. J. Theor. Phys. 51(2012) 612]. LRS Bianchi type-I cosmological model filled with a perfect fluid source in [Formula: see text] gravity theory, where [Formula: see text] is the Ricci scalar and [Formula: see text] is the trace of the stress energy–momentum tensor, has been studied in order to investigate early time deceleration and late time acceleration of the universe by using this new form of time-varying deceleration parameter. The time evolution of physical and dynamical parameters have been analyzed and shown by graphs. Moreover, the deceleration parameter has been considered in terms of redshift. It has been shown that the model starts with a big bang and ends with a big rip. It is filled by a quintessence like fluid at the early time and by a phantom like fluid at the late time.
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Carvalho, F. C., E. M. Santos, J. S. Alcaniz i J. Santos. "Cosmological constraints from the Hubble parameter onf(R) cosmologies". Journal of Cosmology and Astroparticle Physics 2008, nr 09 (17.09.2008): 008. http://dx.doi.org/10.1088/1475-7516/2008/09/008.
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Sahoo, P. K., S. K. Tripathy i Parbati Sahoo. "A periodic varying deceleration parameter in f(R, T) gravity". Modern Physics Letters A 33, nr 33 (29.10.2018): 1850193. http://dx.doi.org/10.1142/s0217732318501936.
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The phenomenon of accelerated expansion of the present universe and a cosmic transit aspect is explored in the framework of a modified gravity theory known as f(R, T) gravity (where R is the Ricci scalar and T is the trace of the energy–momentum tensor of the matter content). The cosmic transit phenomenon signifies a signature flipping behavior of the deceleration parameter. We employ a periodic varying deceleration parameter and obtained the exact solution of field equations. The dynamical features of the model including the oscillatory behavior of the EOS parameter are studied. We have also explored the obvious violation of energy–momentum conservation in f(R, T) gravity. The periodic behavior of energy conditions for the model are also discussed with a wide range of the free parameters.
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MATHEW, TITUS K., JISHNU SURESH i DIVYA DIVAKARAN. "MODIFIED HOLOGRAPHIC RICCI DARK ENERGY MODEL AND STATEFINDER DIAGNOSIS IN FLAT UNIVERSE". International Journal of Modern Physics D 22, nr 09 (26.06.2013): 1350056. http://dx.doi.org/10.1142/s0218271813500569.
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Evolution of the universe with modified holographic Ricci dark energy model is considered. Dependency of the equation of state parameter and deceleration parameter on the redshift and model parameters are obtained. It is shown that the density evolution of both the nonrelativistic matter and dark energy are same until recent times. The evolutionary trajectories of the model for different model parameters are obtained in the statefinder planes, r – s and r – q planes. The present statefinder parameters are obtained for different model parameter values, using that the model is differentiated from other standard models like the ΛCDM model. We have also shown that the evolutionary trajectories are depending on the model parameters, and at past times the dark energy is behaving like cold dark matter, with equation of state equal to zero.
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Widyaningrum, Rini, Sri Lestari i Ferry Jie. "Image Analysis of Periapical Radiograph for Bone Mineral Density Prediction". International Journal of Electrical and Computer Engineering (IJECE) 8, nr 4 (1.08.2018): 2083. http://dx.doi.org/10.11591/ijece.v8i4.pp2083-2090.
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<span>Osteoporosis is a systemic skeletal disease. Parameter from any bone site in the body has possibility to be developed as a predictor of osteoporosis. The alteration in the mandible trabecular bone is visible in periapical radiographs. The aim of this study was to correlate the area parameter and the integrated density of periapical radiograph with bone mineral density. Image analysis of periapical radiograph i.e. measurement of area parameter and integrated density was done on Region of Interest (ROI) by using canny edge detection method. Result of this study showed that the area parameter has asignificant (α<0.05) negative correlation with the bone mass density (BMD) of the lumbar spine (r = -0.371) and T-score of the lumbar spine (r = -0.383). The linear regression test showed that the area parameter only can be used to predict T-score of the lumbar spine (F=5.822, α<0.05). The integrated density showed a significant (α < 0.05) negative correlation with T-score of hip (r = -0.332) and T-score of lumbar spine (r = -0.377). It can be concluded that the area parameter can be used as one of input parameters for computer-aided system of osteoporosis early detection by using periapical radiograph.</span>
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Wojciechowski, Kazimierz F. "Electron Density Parameters". Modern Physics Letters B 12, nr 17 (20.07.1998): 685–91. http://dx.doi.org/10.1142/s0217984998000809.
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An analysis of the density parameters r m , of the mobile part of the electron gas in metals and r b , related to the "bonding valence" together with r B , fitted to the bulk modulus and r f , fitted to the Fermi energy is given. It is shown that the ground state properties of the simple metals may be approximately described by one parameter, while those of transition metals by two different density parameters.
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Huang, Jiang-Wei, i Kunchuan Wang. "The Convergence of Calderón Reproducing Formulae of Two Parameters in $L^p$, in $\mathscr S$ and in $\mathscr S'$". Journal of Mathematics Research 9, nr 4 (13.07.2017): 87. http://dx.doi.org/10.5539/jmr.v9n4p87.
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The Calderón reproducing formula is the most important in the study of harmonic analysis, which has the same property as the one of approximate identity in many special function spaces. In this note, we use the idea of separation variables and atomic decomposition to extend single parameter to two-parameters and discuss the convergence of Calderón reproducing formulae of two-parameters in $L^p(\mathbb R^{n_1} \times \mathbb R^{n_2})$, in $\mathscr S(\mathbb R^{n_1} \times \mathbb R^{n_2})$ and in $\mathscr S'(\mathbb R^{n_1} \times \mathbb R^{n_2})$.
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Marsh, Derek. "Spin-label Order Parameter Calibrations for Slow Motion". Applied Magnetic Resonance 49, nr 1 (9.09.2017): 97–106. http://dx.doi.org/10.1007/s00723-017-0940-7.
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Abstract Calibrations are given to extract orientation order parameters from pseudo-powder electron paramagnetic resonance line shapes of 14N-nitroxide spin labels undergoing slow rotational diffusion. The nitroxide z-axis is assumed parallel to the long molecular axis. Stochastic-Liouville simulations of slow-motion 9.4-GHz spectra for molecular ordering with a Maier–Saupe orientation potential reveal a linear dependence of the splittings, $$2A_{\hbox{max} }$$ 2 A max and $$2A_{\hbox{min} }$$ 2 A min , of the outer and inner peaks on order parameter $$S_{zz}$$ S z z that depends on the diffusion coefficient $$D_{{{\text{R}} \bot }}$$ D R ⊥ which characterizes fluctuations of the long molecular axis. This results in empirical expressions for order parameter and isotropic hyperfine coupling: $$S_{zz} = s_{1} \times \left( {A_{\hbox{max} } - A_{\hbox{min} } } \right) - s_{o}$$ S z z = s 1 × A max - A min - s o and $$a_{o}^{{}} = \tfrac{1}{3}\left( {f_{\hbox{max} } A_{\hbox{max} } + f_{\hbox{min} } A_{\hbox{min} } } \right) + \delta a_{o}$$ a o = 1 3 f max A max + f min A min + δ a o , respectively. Values of the calibration constants $$s_{1}$$ s 1 , $$s_{\text{o}}$$ s o , $$f_{\hbox{max} }$$ f max , $$f_{\hbox{min} }$$ f min and $$\delta a_{o}$$ δ a o are given for different values of $$D_{{{\text{R}} \bot }}$$ D R ⊥ in fast and slow motional regimes. The calibrations are relatively insensitive to anisotropy of rotational diffusion $$(D_{{{\text{R}}//}} \ge D_{{{\text{R}} \bot }} )$$ ( D R / / ≥ D R ⊥ ) , and corrections are less significant for the isotropic hyperfine coupling than for the order parameter.
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Zhang, Zhuang, Xiangtao Zeng, Zhiyuan Pei, Hubing Xiao, Xuhong Ye i Junhui Fan. "Two-component TeV Emissions for Blazars". Publications of the Astronomical Society of the Pacific 134, nr 1036 (1.06.2022): 064101. http://dx.doi.org/10.1088/1538-3873/ac76de.
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Abstract For blazars, its radio emissions are composed of two components. In the high energy bands, Tera-electronvolts (TeV; 1012electronvolts) emissions were detected from some blazars. Does the TeV emission also consist of two components? To investigate the TeV emission component, we compiled a sample of 51 TeV blazars with available radio core dominance parameters and applied a two-component (the beamed and the unbeamed) model to study the composition of blazar TeV emission. We obtained the core-dominance parameter at the TeV band through applying a relativistic beaming model, and found that the average TeV core-dominance parameter is log R TeV BL = 〈 3.12 ± 2.83 〉 for 46 BL Lacs, and that is log R TeV FSRQ = 〈 4.80 ± 1.76 〉 for 5 FSRQs, which shows an indication that the core dominance parameter in BL Lacs is smaller than that in FSRQs. For the three subclasses of BL Lacs—high synchrotron peaked BL Lacs(HBLs), intermediate synchrotron peaked BL Lacs(IBLs) and low synchrotron peaked(LBLs), log R TeV HBL is smaller than log R TeV IBL and log R TeV LBL . Our results suggest that the blazar TeV emission from the core is thousands times stronger than from the extended region and the TeV emission is more core-dominated for the lower synchrotron peaked sources. In addition, a significant correlation between the TeV core-dominance parameter ( log R TeV ) and the radio one ( log R radio ) log R TeV = ( 2.56 ± 0.08 ) log R radio + 0.99 , is obtained suggesting that the TeV emission is beamed and the TeV core-dominance parameter is an indicator of beaming effect at the TeV bands, and that the TeV emission has stronger beaming effect than the radio emission.
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DELIUS, GUSTAV W., MARK D. GOULD, JON R. LINKS i YAO-ZHONG ZHANG. "ON TYPE I QUANTUM AFFINE SUPERALGEBRAS". International Journal of Modern Physics A 10, nr 23 (20.09.1995): 3259–81. http://dx.doi.org/10.1142/s0217751x95001571.
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The type I simple Lie superalgebras are sl(m|n) and osp(2|2n). We study the quantum deformations of their untwisted affine extensions Uq[sl(m|n)(1)] and Uq[osp(2|2n)(1)]. We identify additional relations between the simple generators (“extra q Serre relations”) which need to be imposed in order to properly define Uq[sl(m|n)(1)] and Uq[osp(2|2n)(1)]. We present a general technique for deriving the spectral-parameter-dependent R matrices from quantum affine superalgebras. We determine the R matrices for the type I affine superalgebra Uq[sl(m|n)(1)] in various representations, thereby deriving new solutions of the spectral-parameter-dependent Yang-Baxter equation. In particular, because this algebra possesses one-parameter families of finite-dimensional irreps, we are able to construct R matrices depending on two additional spectral-parameter-like parameters, providing generalizations of the free fermion model.
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Paul, B. C., A. Chanda, A. Beesham i S. D. Maharaj. "Late time cosmology in f(R,G) -gravity with interacting fluids". Classical and Quantum Gravity 39, nr 6 (1.03.2022): 065006. http://dx.doi.org/10.1088/1361-6382/ac4b97.
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Abstract Cosmological models are obtained in a f(R) modified gravity with a coupled Gauss–Bonnet (GB) terms in the gravitational action. The dynamical role of the GB terms is explored with a coupled dilaton field in two different cases (I) f ( R ) = R + γ R 2 − λ R 3 m s 2 δ where γ, λ and δ are arbitrary constants and (II) f(R) = R and estimate the constraints on the model parameters. In the first case we choose GB terms coupled with a free scalar field in the presence of interacting fluid and in the second case GB terms coupled with scalar field in a self interacting potential to compare the observed Universe. The evolutionary scenario of the Universe is obtained adopting a numerical technique as the field equations are highly non-linear. Defining a new density parameter Ω H , a ratio of the dark energy (DE) density to the present energy density of the non-relativistic matter, we look for a late accelerating Universe. The state finder parameters Ω H , deceleration parameter (q), jerk parameter (j) are plotted. It is noted that a non-singular Universe with oscillating cosmological parameters for a given strength of interactions is admitted in model-I. The gravitational coupling constant λ is playing an important role. The Lagrangian density of f(R) is found to dominate over the GB terms when oscillating phase of DE arises. In model-II, we do not find oscillation of the cosmological parameters as the Universe evolves. In the presence of interaction the energy from radiation sector of matter cannot flow to the other two sectors of fluid. The range of values of the strengths of interaction of the fluids are estimated for a stable Universe assuming the primordial gravitational wave speed equal to unity.
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Chen, Jiao, Wei Ding i Guozhen Lu. "Boundedness of multi-parameter pseudo-differential operators on multi-parameter local Hardy spaces". Forum Mathematicum 32, nr 4 (1.07.2020): 919–36. http://dx.doi.org/10.1515/forum-2019-0319.
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AbstractAfter the celebrated work of L. Hörmander on the one-parameter pseudo-differential operators, the applications of pseudo-differential operators have played an important role in partial differential equations, geometric analysis, harmonic analysis, theory of several complex variables and other branches of modern analysis. For instance, they are used to construct parametrices and establish the regularity of solutions to PDEs such as the {\overline{\partial}} problem. The study of Fourier multipliers, pseudo-differential operators and Fourier integral operators has stimulated further such applications. It is well known that the one-parameter pseudo-differential operators are {L^{p}({\mathbb{R}^{n}})} bounded for {1<p<\infty}, but only bounded on local Hardy spaces {h^{p}({\mathbb{R}^{n}})} introduced by Goldberg in [D. Goldberg, A local version of real Hardy spaces, Duke Math. J. 46 1979, 1, 27–42] for {0<p\leq 1}. Though much work has been done on the {L^{p}(\mathbb{R}^{n_{1}}\times\mathbb{R}^{n_{2}})} boundedness for {1<p<\infty} and Hardy {H^{p}(\mathbb{R}^{n_{1}}\times\mathbb{R}^{n_{2}})} boundedness for {0<p\leq 1} for multi-parameter Fourier multipliers and singular integral operators, not much has been done yet for the boundedness of multi-parameter pseudo-differential operators in the range of {0<p\leq 1}. The main purpose of this paper is to establish the boundedness of multi-parameter pseudo-differential operators on multi-parameter local Hardy spaces {h^{p}(\mathbb{R}^{n_{1}}\times\mathbb{R}^{n_{2}})} for {0<p\leq 1} recently introduced by Ding, Lu and Zhu in [W. Ding, G. Lu and Y. Zhu, Multi-parameter local Hardy spaces, Nonlinear Anal. 184 2019, 352–380].
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Nill, Florian. "Scaling Symmetries and Parameter Reduction in Epidemic SI(R)S Models". Symmetry 15, nr 7 (10.07.2023): 1390. http://dx.doi.org/10.3390/sym15071390.
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Symmetry concepts in parametrized dynamical systems may reduce the number of external parameters by a suitable normalization prescription. If, under the action of a symmetry group G, parameter space A becomes a (locally) trivial principal bundle, A≅A/G×G, then the normalized dynamics only depends on the quotient A/G. In this way, the dynamics of fractional variables in homogeneous epidemic SI(R)S models, with standard incidence, absence of R-susceptibility and compartment independent birth and death rates, turns out to be isomorphic to (a marginally extended version of) Hethcote’s classic endemic model, first presented in 1973. The paper studies a 10-parameter master model with constant and I-linear vaccination rates, vertical transmission and a vaccination rate for susceptible newborns. As recently shown by the author, all demographic parameters are redundant. After adjusting time scale, the remaining 5-parameter model admits a 3-dimensional abelian scaling symmetry. By normalization we end up with Hethcote’s extended 2-parameter model. Thus, in view of symmetry concepts, reproving theorems on endemic bifurcation and stability in such models becomes needless.
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Simic-Krstic, Jovana, A. Kalauzi, S. Ribar, G. Lazovic i R. Radojicic. "Electrical characteristics of female and male human skin". Archives of Biological Sciences 64, nr 3 (2012): 1165–71. http://dx.doi.org/10.2298/abs1203165s.
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Bioimpedance spectroscopy (BIS) is a popular method for characterizing the electrical properties of biological tissues. In this study, BIS measurement data of female and male human skin were analyzed and compared. The electrical characteristics of tissue were followed according to four-parameters of the Cole-Cole model: low frequency resistance R0; high frequency resistance R?; relaxation time t and parameter a. Individual electrical characteristics of human skin were determined for 30 women and 30 men. The distribution and one-way analysis of variance (one-way ANOVA) of the Cole-Cole parameters R0, R?, t, a within the human population indicated their different dependence on gender. Parameter a, which is higher in the female subjects (a =0.83?0.03) than in the male subjects (a=0.7?0.05), is strongly dependent on gender (p=0). Parameter R? also significantly depends on gender (p=0.002), while t and R0 seem to be slightly related to gender (p>0.05).
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Gogoi, Dhruba Jyoti, i Umananda Dev Goswami. "Tideless traversable wormholes surrounded by cloud of strings in f(R) gravity". Journal of Cosmology and Astroparticle Physics 2023, nr 02 (1.02.2023): 027. http://dx.doi.org/10.1088/1475-7516/2023/02/027.
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Abstract We study the tideless traversable wormholes in the f(R) gravity metric formalism. First we consider three shape functions of wormholes and study their viabilities and structures. The connection between the f(R) gravity model and wormhole shape function has been studied and the dependency of the f(R) gravity model with the shape function is shown. We also obtain a wormhole solution in the f(R) gravity Starobinsky model surrounded by a cloud of strings. In this case, the wormhole shape function depends on both the Starobinsky model parameter and the cloud of strings parameter. The structure and height of the wormhole is highly affected by the cloud of strings parameter, while it is less sensitive to the Starobinsky model parameter. The energy conditions have been studied and we found the ranges of the null energy condition violation for all wormhole structures. The quasinormal modes from these wormhole structures for the scalar and Dirac perturbations are studied using higher order WKB approximation methods. The quasinormal modes for the toy shape functions depend highly on the model parameters. In case of the Starobinsky model's wormhole the quasinormal frequencies and the damping rate increase with an increase in the Starobinsky model parameter in scalar perturbation. Whereas in Dirac perturbation, with an increase in the Starobinsky model parameter the quasinormal frequencies decrease and the damping rate increases. The cloud of strings parameter also impacts prominently and differently the quasinormal modes from the wormhole in the Starobinsky model.
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Aryana, Suka, AA Wiradewi Lestari, I. B. Putrawan, Ni Ketut Rai Purnami, I. Nyoman Astika i R. A. Tuty Kuswardhani. "The The relationship between IL-6 and CRP with Sarcopenia in indigenous elderly population at Pedawa Village, Buleleng, Bali, Indonesia". Health Science Journal of Indonesia 9, nr 1 (15.10.2018): 37–44. http://dx.doi.org/10.22435/hsji.v9i1.467.
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Abstrak
Latar belakang: Sarkopenia adalah sindrom yang ditandai dengan penurunan massa otot disertai penurunan kekuatan otot dan atau fungsi otot. Stres oksidatif dan proses inflamasi dikenal sebagai faktor pemicu untuk sarkopenia dengan melepaskan rangsangan katabolik interleukin-6 (IL-6) dan protein C-reaktif (CRP). Penelitian ini bertujuan untuk menentukan hubungan antara IL-6 dan kadar CRP terhadap parameter sarkopenia seperti massa otot, kekuatan pegangan, dan kecepatan berjalan.
Metode: Penelitian ini menggunakan desain cross-sectional analitik yang dilakukan di Desa Pedawa, Kabupaten Buleleng, Bali pada bulan Agustus 2016. Sekitar 79 responden berusia ≥ 60 tahun menggunakan teknik sampling acak stratifikasi. Variabel yang dinilai yaitu parameter sarkopenia (massa otot, kekuatan pegangan, dan kecepatan berjalan) termasuk IMT, serta IL-6 dan pemeriksaan tingkat CRP. Uji korelasi spearman dan parsial digunakan untuk menilai korelasi antara parameter IL-6, CRP, dan sarkopenia.
Hasil: Kadar IL-6 dan CRP tidak berkorelasi signifikan dengan tiga parameter sarkopenia. Kadar CRP berkorelasi dengan IL-6 (r = 0.37; p = 0.001) dan IMT (r = 0.29; p = 0.009). Pada kelompok pria, IL-6 hanya berkorelasi dengan CRP (r = 0.40; p = 0.011). Sedangkan pada kelompok wanita, IL-6 berkolerasi dengan CRP (r = 0.38; p = 0.017), kecepatan berjalan (r = 0.33; p = 0.037) serta CRP berkorelasi dengan IMT (r = 0.32; p = 0.049) dan massa otot total (r = -0.32; p = 0.043). Setelah penyesuaian untuk variabel IMT, IL-6 berkorelasi dengan CRP (r = 0.43; p = 0,001) dan massa otot total (r = -0.25; p = 0.026) serta secara signifikan berkorelasi pada kelompok kurus (IMT<18.5 kg/m2) (r = -0.50; p = 0.026). CRP tidak berkorelasi secara signifikan dengan tiga parameter sarkopenia pada uji spearman, korelasi parsial, dan uji korelasi spesifik spearman berdasarkan pada kelompok IMT.
Kesimpulan: Kadar IL-6 berhubungan dengan penurunan massa otot total pada keseluruhan lansia desa Pedawa setelah penyesuaian variabel IMT.
Kata kunci: IL-6, Protein C-Reaktif (CRP), Sarkopenia, Lanjut usia, Desa Pedawa.
Abstract
Background: Sarcopenia is a syndrome characterized by decreased muscle mass with decreased muscle strength and or muscle function. Oxidative stress and inflammatory processes are known as triggering factors for sarcopenia by releasing catabolic stimuli of interleukin-6 (IL-6) and C-reactive protein (CRP).This study aims to determine the relationship between IL-6 and CRP levels to sarcopenia parameter such as muscle mass, grip strength, and walking speed.
Methods: This study was an analytic cross-sectional design conducted at Pedawa Village, Buleleng District, Bali in August 2016. About 79 respondents aged ≥ 60 years using stratified random sampling technique. The assessed variables were sarcopenia parameter (muscle mass, grip strength, and walking speed) including BMI, as well as IL-6 and CRP levels examination. Spearman and partial correlation test were used to assess the correlation among IL-6, CRP, and sarcopenia parameters.
Results: IL-6 levels and CRP were not significantly correlated with the three parameters of sarcopenia. CRP levels correlated with IL-6 (r = 0.37; p = 0.001) and BMI (r = 0.29; p = 0.009). In the male group, IL-6 was only correlated with CRP (r = 0.40; p = 0.011). While in the women group, IL-6 correlated with CRP (r = 0.38; p = 0.017), walking speed (r = 0.33; p = 0.037) and CRP correlated with BMI (r = 0.32; p = 0.049) and total muscle mass (r = -0.32; p = 0.043). After adjustment to BMI variable, IL-6 was correlated with CRP (r = 0,43; p = 0,001) and total muscle mass (r = -0.25; p = 0.026) and significantly correlated in underweight groups (BMI<18.5 kg/m2) (r=-0.50; p=0.026). CRP was not significantly correlated with the three parameters of sarcopenia on Spearman, partial correlation, and Spearman's specific correlation test based on BMI group.
Conclusion: IL-6 levels were associated with total muscle mass loss after BMI adjustmentin Pedawa village’s elderly as a whole.
Keywords: IL-6, C-Reactive Protein (CRP), Sarcopenia, Elderly, Pedawa village.
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Pasqua, Antonio, Surajit Chattopadhyay i Ratbay Myrzakulov. "A Dark Energy Model with Higher Order Derivatives of H in the f(R,T) Modified Gravity Model". ISRN High Energy Physics 2014 (29.01.2014): 1–11. http://dx.doi.org/10.1155/2014/535010.
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We consider a model of dark energy (DE) which contains three terms (one proportional to the squared Hubble parameter, one to the first derivative, and one to the second derivative with respect to the cosmic time of the Hubble parameter) in the light of the f(R,T)=μR+νT modified gravity model, with μ and ν being two constant parameters. R and T represent the curvature and torsion scalars, respectively. We found that the Hubble parameter exhibits a decaying behavior until redshifts z≈-0.5 (when it starts to increase) and the time derivative of the Hubble parameter goes from negative to positive values for different redshifts. The equation of state (EoS) parameter of DE and the effective EoS parameter exhibit a transition from ω<-1 to ω>-1 (showing a quintom-like behavior). We also found that the model considered can attain the late-time accelerated phase of the universe. Using the statefinder parameters r and s, we derived that the studied model can attain the ΛCDM phase of the universe and can interpolate between dust and ΛCDM phase of the universe. Finally, studying the squared speed of sound vs2, we found that the considered model is classically stable in the earlier stage of the universe but classically unstable in the current stage.
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Hunt, Brian E., i William B. Farquhar. "Nonlinearities and asymmetries of the human cardiovagal baroreflex". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 288, nr 5 (maj 2005): R1339—R1346. http://dx.doi.org/10.1152/ajpregu.00038.2004.
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To determine whether an approach such as the modified Oxford technique can consistently produce data that reveal the nonlinear nature of the cardiovagal baroreflex and to ascertain whether the model parameters provide unique insight into baroreflex function, we retrospectively examined 91 baroreflex trials (38 subjects, 27 men and 11 women, ages 22–72 yr). The modified Oxford technique (bolus sodium nitroprusside followed by bolus phenylephrine) was used to perturb blood pressure, and the resulting systolic blood pressure-R-R interval responses were plotted and modeled using a linear, a four-parameter symmetric, and a five-parameter asymmetric model. Several issues, such as the effect of data averaging, various approaches to gain estimation, and the predictive value of model parameters, were examined during reflex modeling. Sigmoid models accounted for a greater amount of the variance than did the linear model: linear r2 = 0.81 ± 0.01, four-parameter r2 = 0.90 ± 0.08, and five-parameter r2 = 0.90 ± 0.08 ( P < 0.05, linear vs. sigmoid models). Data averaging did not affect model fits. Although the four gain estimates (linear remodel, 1st derivative, peak, and set point) were statistically related, the set point gain was significantly lower than other estimates ( P < 0.05). Subgroup comparisons between young and older healthy subjects revealed differences in all indexes of cardiovagal baroreflex gain, as well as R-R interval operating range and curvature parameters. In conclusion, the modified Oxford technique consistently reveals the nonlinear nature of the human cardiovagal baroreflex. Moreover, of the parameters produced by the symmetric sigmoid model, only the response range provides unique information beyond that of reflex gain.
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Goldberger, Jeffrey J. "Sympathovagal balance: how should we measure it?" American Journal of Physiology-Heart and Circulatory Physiology 276, nr 4 (1.04.1999): H1273—H1280. http://dx.doi.org/10.1152/ajpheart.1999.276.4.h1273.
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There are complex interactions between the sympathetic and parasympathetic nervous system inputs to the sinus node. The concept of “sympathovagal balance” reflects the autonomic state resulting from the sympathetic and parasympathetic influences. Despite widespread usage of a variety of heart rate (HR) variability parameters as indexes of sympathovagal balance, no index has been validated as a measure of sympathovagal balance. This study evaluated the utility of HR, HR variability, and a new parameter termed the vagal-sympathetic effect (VSE) as indexes of sympathovagal balance. The ideal parameter had to satisfy the following criteria: 1) the index should vary similarly among subjects in response to different autonomic conditions; 2) the variability in the index among subjects exposed to the same autonomic conditions should be small; and 3) the response of the index to various autonomic conditions should reflect the underlying changes in physiological state and have a meaningful interpretation. Volunteers [8 men, 6 women; mean age 28.5 ± 4.8 (SD) yr] were evaluated for the effects of sympathetic and parasympathetic stimulation and blockade on HR and HR variability. VSE was defined as the ratio of the R-R interval to the intrinsic R-R interval. VSE and R-R interval consistently changed in the expected directions with parasympathetic and sympathetic stimulation and blockade. A general linearized model was used to evaluate the response of each parameter. VSE and R-R interval had r 2 values of 0.847 and 0.852, respectively. Natural logarithm of the low-frequency power had an r 2value of 0.781 with lower r 2 values for all the other HR variability parameters. The coefficient of variation was also lowest for each condition tested for the VSE and the R-R interval. VSE and R-R interval best satisfy the criteria for the ideal index of sympathovagal balance. Because it is impractical under most conditions to measure the VSE as the index of sympathovagal balance, the most suitable index is the R-R interval.
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Noori Gashti, S., J. Sadeghi, S. Upadhyay i M. R. Alipour. "Swampland dS conjecture in mimetic f(R, T) gravity". Communications in Theoretical Physics 74, nr 8 (1.08.2022): 085402. http://dx.doi.org/10.1088/1572-9494/ac7a1f.
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Abstract In this paper, we study a theory of gravity called mimetic f(R, T) in the presence of swampland dS conjecture. For this purpose, we introduce several inflation solutions of the Hubble parameter H(N) from f(R, T) = R + δ T gravity model, in which R is Ricci scalar, and T denotes the trace of the energy–momentum tensor. Also, δ and N are the free parameter and a number of e-fold, respectively. Then we calculate quantities such as potential, Lagrange multiplier, slow-roll, and some cosmological parameters such as n s and r. Then we challenge the mentioned inflationary model from the swampland dS conjecture. We discuss the stability of the model and investigate the compatibility or incompatibility of this inflationary scenario with the latest Planck observable data.
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Popescu, Dorin. "General Néron desingularization". Nagoya Mathematical Journal 100 (grudzień 1985): 97–126. http://dx.doi.org/10.1017/s0027763000000246.
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Let R⊂ R′ be an “unramified” extension of discrete valuation rings in the sense that a local parameter p of R is also a local parameter in R⊂. Suppose that the inclusion R→R⊂ induces separable extensions on fraction and residue fields.
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Sahoo, Rakesh Ranjan, Kamal Lochan Mahanta i Saibal Ray. "Nonsingular Phantom Cosmology in Five-Dimensional f(R,T) Gravity". Universe 8, nr 11 (30.10.2022): 573. http://dx.doi.org/10.3390/universe8110573.
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We obtain exact solutions to the field equations for five-dimensional locally rotationally symmetric (LRS) Bianchi type-I spacetime in the f(R,T) theory of gravity, where specifically, the following three cases are considered: (i) f(R,T)=μ(R+T), (ii) f(R,T)=Rμ+RTμ2, and (iii) f(R,T)=R+μR2+μT, where R and T, respectively, are the Ricci scalar and trace of the energy–momentum tensor. It is found that the equation of state (EOS) parameter w is governed by the parameter μ involved in the f(R,T) expressions. We fine-tune the parameter μ to obtain the effect of phantom energy in the model. However, we also restrict this parameter to obtain a stable model of the universe.
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Eiben, Eduard, Robert Ganian, Iyad Kanj, Sebastian Ordyniak i Stefan Szeider. "The Parameterized Complexity of Clustering Incomplete Data". Proceedings of the AAAI Conference on Artificial Intelligence 35, nr 8 (18.05.2021): 7296–304. http://dx.doi.org/10.1609/aaai.v35i8.16896.
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We study fundamental clustering problems for incomplete data. Specifically, given a set of incomplete d-dimensional vectors (representing rows of a matrix), the goal is to complete the missing vector entries in a way that admits a partitioning of the vectors into at most k clusters with radius or diameter at most r. We give tight characterizations of the parameterized complexity of these problems with respect to the parameters k, r, and the minimum number of rows and columns needed to cover all the missing entries. We show that the considered problems are fixed-parameter tractable when parameterized by the three parameters combined, and that dropping any of the three parameters results in parameterized intractability. A byproduct of our results is that, for the complete data setting, all problems under consideration are fixed-parameter tractable parameterized by k+r.
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Paris, Mark, i Gerald Hale. "Covariances and parameter confidence intervals from light-element R-matrix evaluations". EPJ Web of Conferences 281 (2023): 00020. http://dx.doi.org/10.1051/epjconf/202328100020.
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R-matrix parameter covariances for light elements with A 16 are calculated within the Wigner-Eisenbud multichannel unitary R-matrix theory. We review the theoretical foundation, numerical approach, and determination of the parameter covariances within this approach. We derive the relation between the parameter variance, as the diagonal elements of the covariance matrix, and the parameter confidence interval based upon the chi-squared distribution. Cross section covariances computed from the parameter confidence intervals are calculated for several compound systems and discussed.
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Sandomirski, S. G. "Analysis of Requirements and the Feasible Limit for Error Reduction in Two-Parameter Magnetic Determination of Steels’ Hardness". Devices and Methods of Measurements 11, nr 3 (22.09.2020): 236–44. http://dx.doi.org/10.21122/2220-9506-2020-11-3-236-244.
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All measurements of mechanical properties of materials in the magnetic structural analysis are indirect and relationships between the measured parameters are correlated. An important physical parameter of steel is hardness. An increase in the correlation coefficient R and a reduction in the standard deviation (SD) are achieved when controlling the hardness of steels with two-parameter magnetic methods compared to methods that use a single measured parameter. However, the specific conditions and requirements for application of the two-parameter methods remain unclear. The purpose of this article was to analyze conditions and the achievable error reduction limit for two-parameter indirect determination of steels hardness and to compare those with one-parameter methods.In particular, we considered the mean Square Deviation (SD), σF , of indirect calculation of the physical quantity F using two measured parameters x1 and x2 that are correlated with F. It was found that reduction of σF is most pronounced when x1 and x2 are inversely correlated with the maximum modulus |R| of the correlation coefficient R between them. The most significant reduction in σF occurs at similar values of the SDs σ1 and σ2 between the true value of F and the values calculated based on the results of indirect measurements of F usingeach of the parameters x1 and x2 . The Results of the analysis are confirmed by an example of reduction in SD when determining the hardness of carbon steels by measuring their remanent magnetization and coercive force compared to use any one of these parameters.This result can be applied to measurements in non-destructive testing and in related fields of physics and technology. The Results of the analysis allow us to compare different parameters for indirect two-parameter determination of a physical quantity, to select the optimal parameters, and to evaluate the minimum achievable measurement error of a physical quantity by a two-parameter method before performing the measurements.
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Abubakar Shehu, Ibrahim Danjuma Yale i Abdulazeez Mohammed Tanko Uchiri. "Unsteady Magnetohydrodynamic (MHD) flow past an accelerated vertical plate in the presence of thermal radiation and chemical reaction". World Journal of Advanced Engineering Technology and Sciences 6, nr 2 (30.08.2022): 081–97. http://dx.doi.org/10.30574/wjaets.2022.6.2.0084.
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A study on Magnetohydrodynamic (MHD) flow past an accelerated vertical plate with the effects of thermal radiation and chemical reaction has been carried out. The dimensionless governing equations are solved using Laplace transform technique. The solution for the velocity, temperature and concentration field are obtained and analyzed for the different physical parameters like thermal Grashof Number, Modified Grashof Number, permeability parameter, Prandtl Number, Radiation parameter, Schmidt Number, chemical reaction parameter and time. It is observed that the velocity profile increases with increasing parameters like, Sc, Gc, M, R and t and also decrease with the decreases Pr and Gr. the temperature profile shows the decrease with the decreasing in Pr and t. and increase in R. While the concentration profile shows the increase in alpha and decrease in Sc and t.
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Mohapatra, Alivarani, Byamakesh Nayak i K. B. Mohanty. "Parameter Extraction of PV Module using NLS Algorithm with Experimental Validation". International Journal of Electrical and Computer Engineering (IJECE) 7, nr 5 (1.10.2017): 2392. http://dx.doi.org/10.11591/ijece.v7i5.pp2392-2400.
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Photovoltaic (PV) module parameters act an important task in PV system design and simulation. Most popularly used single diode R<sub>sh</sub> model has five unknown electrical parameters such as series resistance (R<sub>se</sub>), shunt resistance (R<sub>sh</sub>), diode quality factor (a), photo-generated current (I<sub>pg</sub>) and dark saturation current (I<sub>s</sub>) in the mathematical model of PV module. The PV module output voltage and current relationship is represented by a transcendental equation and is not possible to solve analytically. This paper proposes nonlinear least square (NLS) technique to extract five unknown parameters. The proposed technique is compared with other two popular techniques available in the literature such as Villalva’s comprehensive technique and modified Newton-Raphson (N-R) technique. Only two parameters R<sub>se</sub> and R<sub>sh</sub> are estimated by Villalva’s technique, but all single diode unknown electrical parameters can be estimated by the NLS technique. The accuracy of different estimation techniques is compared in terms of absolute percentage errors at MPP and is found the minimum for the proposed technique. The elapsed time for parameter estimation for NLS technique is minimum and much less compared to other two techniques. Extracted parameters of polycrystalline ELDORA-40 PV panel by the proposed technique have been validated through simulation and experimental current-voltage (I-V) and power-voltage (P-V) characteristics.