Miracle-dz/UniFAR-FTUs huggingface dataset:
Novel algorithm for segmentation of brain MR images using fuzzy Markov random field

In this paper,a fuzzy Markov Random Field(MRF) model is developed based on the conventional MRF model.By analyzing the fuzzy MRF model,the formula of determining the membership values for each voxel to indicate the partial volume degree is derived.We also propose an efficient and unsupervised algorithm to realize the accurate segmentation for MR brain images.The simulated brain images and real clinical images are selected to test the proposed algorithm.The experimental results show that the proposed algorithm can segment the brain images more accurately than the conventional model-based algorithms and the fuzzy C-mean do as well.
The Impact of the First and Second Waves of COVID‐19 Pandemic in Nigeria

In recent times, the COVID‐19 pandemic has been the subject of global concern. It has so far claimed over 5.4 million lives globally, with over 291 million cases recorded worldwide as of 5 January 2022. It is known to have different waves and variants, thus making it difficult to handle/manage. This study investigates the impact of the first and second waves of COVID‐19 in Nigeria, West Africa. The data used is for the 36 states of Nigeria archived at the National Centre for Disease Control from February 2020 to April 2021. Results from the study reveal that the highest number of COVID‐19 cases during the first/second wave was recorded at Lagos (23,238/34,616), followed by the Federal Capital Territory (FCT) (6,770/12,911) and alternates between Plateau (3,858/5,170) and Kaduna (3,064/5,908). Similarly, the highest number of deaths (during the first/second wave) was also recorded in Lagos (220/219), followed by Edo (112/73), and then FCT (83/81). The Case Fatality Ratio (CFR) was observed to be higher mostly in northern Nigeria during the first wave and the southeast during the second wave of the pandemic. On the average, the number of cases/deaths recorded during the second wave was higher than those of the first wave, but a decrease in the CFR values was observed during the second wave. Higher values of COVID‐19 cases/death were mostly recorded in Nigeria during; maximum relative humidity (RH) (>70%) with minimum Temperatures (<25°C), Low temperatures, and low RH which is mostly observed during the cold/dusty periods.
Numerical Procedure for Calibration of Volatility with American Options

In finance, the price of an American option is obtained from the price of the underlying asset by solving a parabolic variational inequality. The calibration of volatility from the prices of a family of American options yields an inverse problem involving the solution of the previously mentioned parabolic variational inequality. In this paper, the discretization of the variational inequality by finite elements is studied in detail. Then, a calibration procedure, where the volatility belongs to a finite‐dimensional space (finite element or bicubic splines) is described. A least square method, with suitable regularization terms is used. Necessary optimality conditions involving adjoint states are given and the differentiability of the cost function is studied. A parallel algorithm is proposed and numerical experiments, on both academic and realistic cases, are presented.
Criteria of Exponential Growth for the Numbers of Particles in Models of Branching Random Walks

We consider two models of continuous-time branching random walk on ${\bf Z}^d$ with one source of branching. The first model assumes that the random walk is symmetric over the entire lattice. In the second model, an additional parameter is introduced for “artificial” strengthening of the degree of dominance of branching or walk at the source, which violates the walk symmetry. Necessary and sufficient conditions are established under which the exponential growth in the numbers of particles is observed in the models both at an arbitrary lattice point and on the entire lattice. General methods for studying the models in the supercritical case are proposed.
A fast method for a class of one-stage bounded variables and single constrained linear programming problems

Abstract In this paper, an efficient and effective method is developed for solving a class of onestage single constrained linear programming problems with a finite number of right hand side scenarios and bounded variables. We compare our proposed method with two general purpose methods. The first general purpose method uses CPLEX interactive optimizer. The second general purpose uses command “linprog” of MATLAB software. Both CPLEX and “linprog” can solve linear programming problems efficiently. For various m and n, by using elapsed time as the criteria, our procedure outperformed general purpose methods as the problem size grew.
Comparative analysis of damage functions for soft tissues: Properties at damage initialization

In this paper several damage equations are analysed with respect to their properties at damage initialization. This is particularly important for soft biological tissues since two different loading regimes have to be clearly distinguished: the physiological domain where no damage evolution should be considered and the supra-physiological domain where damage evolves. At the transition between these two domains the behaviour of different damage models may influence the convergence of the Newton iteration when solving, for example, nonlinear finite element problems. It is shown that the model proposed by Balzani et al. (Comput Meth Appl Mech Eng 2012; 213–216: 139–151) a priori ensures smooth tangent moduli. In addition to that, a new damage function is proposed able to describe a slow damage evolution at damage initialization also providing smooth tangent moduli. Using this new damage function the approach given by Balzani et al. (Acta Biomater 2006; 2(6): 609–618) can also be modified such that smooth tangent moduli are guaranteed. Numerical analyses of a circumferentially overstretched artery are performed and show that no convergence problems are observed at the transition from the undamaged to the damaged domain, even when a model is used that has non-smooth tangent moduli.
Second‐Order Noncausality in Multivariate GARCH Processes

Typical multivariate economic time series may exhibit co‐behavior patterns not only in the conditional means, but also in the conditional variances. In this paper we give two new definitions of variance noncausality in a multivariate setting a Granger‐type noncausality and a linear Granger noncausality through projections on Hilbert spaces. Both definitions are related to a previous second‐order noncausality concept defined by Granger et al. in a bivariate setting. The implications of second‐order noncausality on multivariate ARMA processes with GARCH‐type errors are investigated. We derive exact testable restrictions on the parameters of the processes considered, implied by this type of noncausality. Conditions for the finiteness of the fourth‐order moment of the multivariate GARCH process are derived and related to earlier results in the univariate framework. We include an illustration of second‐order noncausality in a trivariate model of daily financial returns.
THE WGNE ASSESSMENT OF SHORT-TERM QUANTITATIVE PRECIPITATION FORECASTS

Abstract Twenty-four-hour and 48-h quantitative precipitation forecasts (QPFs) from 11 operational numerical weather prediction models have been verified for a 4-yr period against rain gauge observations over the United States, Germany, and Australia to assess their skill in predicting the occurrence and amount of daily precipitation. Model QPFs had greater skill in winter than in summer, and greater skill in midlatitudes than in Tropics, where they performed only marginally better than “ persistence. ” The best agreement among models, as well as the best ability to discriminate raining areas, occurred for a low rain threshold of 1–2 mm d−1. In contrast, the skill for forecasts of rain greater than 20 mm d−1 was generally quite low, reflecting the difficulty in predicting precisely when and where heavy rain will fall. The location errors for rain systems, determined using pattern matching with the observations, were typically about 100 km for 24-h forecasts, with smaller errors occurring for the heaviest r.
Image compression and magnification using fractal technique

New techniques for image compression and image magnification using the theory of fractals is proposed. The fractal codes are designed assuming the self similarity property of images. In particular, to generate the fractal codes, the genetic algorithm is used which greatly decreases the search for finding self similarities in the given image. The obtained fractal codes are stored instead of the given image in the compression algorithm. Moreover the magnification task is performed using the obtained fractal codes of the image instead of the original one resulting in a reduction in memory requirement. The article presents both theory and implementation of the proposed methods. A simple distortion measure scheme is also proposed to judge the image quality of the magnified image.
Interfacial mixing in stratified flows

In this paper the phenomenon of turbulent mixing at a density interface is studied. Based on a unified view of the mixing processes, quantitative laws are sought, which would be generally valid in flows with mean motion in at least one of the layers. Re-examination of available experimental data from four types of stratified flow, supplemented by theoretical considerations, leads to the identification of four such governing laws, all of a power form, applicable in different ranges of the overall Richardson number, Ri 0. Two of these laws refer to supercritical and subcritical conditions and are considered as fundamental, being related to qualitatively different mechanisms of interfacial mixing. An intermediate law applies around the critical Ri 0 value of unity, while an asymptotic law corresponds to the limit of homogeneous flow as Ri 0 tends to zero. All the above laws are given by simple expressions in terms of the mean flow characteristics, allowing their straightforward application for the quantifica.
Infinite models for ciliary propulsion

This paper discusses two infinite length models (planar and cylindrical) for ciliary propulsion of microscopic organisms. Through the concept of an extensible envelope (instantaneous surface covering the numerous cilia) over the organism, we consider a small amplitude analysis for the velocity of propulsion. A comparison of the velocities of propulsion for the infinite models reveals that they are just over twice that obtained for the finite spherical model (Blake 1971). This indicates that planeness is more important than finiteness, as the solution for typical micro-organisms (e.g. disk-shaped) should occur somewhere between these two models. The maximum velocity of propulsion obtained is one quarter of the wave velocity; that inferred for Opalina, the organism modelled, is nearly one fifth of the wave velocity. Associated shapes of the surface and paths of movement of the tips of the cilia are illustrated.
Two-photon 3D high-density optical storage media: optical properties, temperature, radiation, and fatigue studies

We have employed new molecular media for volumetric data storage by means of two photon absorption. The optical and spectroscopic characteristics of the materials that are relevant to volumetric optical storage are described. In addition, fatigue characteristics of the photochromic media and substrates used in the fabrication of the storage devices are presented. These include temperature, read/write/erase cycles and space environments such as heavy ion and proton radiation, and heat under vacuum.
Pseudo-maximum-likelihood speech pitch extraction

The pitch of a voiced speech segment may be estimated by minimizing the squared error in approximating the segment by the repeated weighted average of successive assumed pitch periods, after a "maximum-likelihood" solution originally due to Slepian. A modification is proposed which allows use of an arbitrary window function and corrects two faults of the "likelihood" function noted by Noll: a linear baseline rise and ambiguous identification of the proper peak. Computationally, the entire formulation is in the time domain. Results are presented for speech both before and after bandpass filtering to simulate telephone transmission. Comparison of these two cases implies that the algorithm is effective for speech in which the fundamental frequency itself is missing.
The social media diet: A scoping review to investigate the association between social media, body image and eating disorders amongst young people

Background Eating disorders are a group of heterogenous, disabling and deadly psychiatric illnesses with a plethora of associated health consequences. Exploratory research suggests that social media usage may be triggering body image concerns and heightening eating disorder pathology amongst young people, but the topic is under-researched as a global public health issue. Aim To systematically map out and critically review the existing global literature on the relationship between social media usage, body image and eating disorders in young people aged 10–24 years. Methods A systematic search of MEDLINE, PyscINFO and Web of Science for research on social media use and body image concerns / disordered eating outcomes published between January 2016 and July 2021. Results on exposures (social media usage), outcomes (body image, eating disorders, disordered eating), mediators and moderators were synthesised using an integrated theoretical framework of the influence of internet use on body image concerns and eating pathology. Results Evidence from 50 studies in 17 countries indicates that social media usage leads to body image concerns, eating disorders/disordered eating and poor mental health via the mediating pathways of social comparison, thin / fit ideal internalisation, and self-objectification. Specific exposures (social media trends, pro-eating disorder content, appearance focused platforms and investment in photos) and moderators (high BMI, female gender, and pre-existing body image concerns) strengthen the relationship, while other moderators (high social media literacy and body appreciation) are protective, hinting at a ‘self-perpetuating cycle of risk’. Conclusion Social media usage is a plausible risk factor for the development of eating disorders. Research from Asia suggests that the association is not unique to traditionally western cultures. Based on scale of social media usage amongst young people, this issue is worthy of attention as an emerging global public health issue.
Critical diameter for III-V nanowires grown on lattice-mismatched substrates

The authors report the experimental observation of a critical diameter (CD) of III-V compound semiconductor epitaxial nanowires (NWs) grown on lattice-mismatched substrates using Au-catalyzed vapor-liquid-solid growth. The CD is found to be inversely proportional to the lattice mismatch. NWs with well-aligned orientation are synthesized with catalysts smaller than the CD. Well-aligned InP NWs grown on a Si substrate exhibit a record low photoluminescence linewidth (5.1meV) and a large blueshift (173meV) from the InP band gap energy due to quantization. Well-aligned InAs NWs grown on a Si substrate are also demonstrated.
A perspective on 3D surface-related multiple elimination

Surface-related multiple elimination (SRME) is an algorithm that predicts all surface multiples by a convolutional process applied to seismic field data. Only minimal preprocessing is required. Once predicted, the multiples are removed from the data by adaptive subtraction. Unlike other methods of multiple attenuation, SRME does not rely on assumptions or knowledge about the subsurface, nor does it use event properties to discriminate between multiples and primaries. In exchange for this “freedom from the subsurface,” SRME requires knowledge of the acquisition wavelet and a dense spatial distribution of sources and receivers. Although a 2D version of SRME sometimes suffices, most field data sets require 3D SRME for accurate multiple prediction. All implementations of 3D SRME face a serious challenge: The sparse spatial distribution of sources and receivers available in typical seismic field data sets does not conform to the algorithmic requirements. There are several approaches to implementing 3D SRME that address the data sparseness problem. Among those approaches are pre-SRME data interpolation, on-the-fly data interpolation, zero-azimuth SRME, and true-azimuth SRME. Field data examples confirm that (1) multiples predicted using true-azimuth 3D SRME are more accurate than those using zero-azimuth 3D SRME and (2) on-the-fly interpolation produces excellent results.
In-line high efficient fiber polarizer based on surface plasmon

An in-line high efficient polarizer, composed of tapered fiber on the Au thin film, is theoretically proposed and experimentally demonstrated. The protocol is based on the high efficient adiabatic conversion of transverse magnetic mode from tapered fiber into surface plasmon (SP) and attenuates quickly in metal film. On the contrary, the transverse electric polarized light is influenced hardly in the whole process. The polarization extinction ratio higher than 500:1 (≈27 dB) is obtained in our experiment. Our demonstration offers a potential way to manipulate the polarization of light in integrated circuit and may inspirit more attention to surface plasmon based devices for polarization controlling.
Penetration of electromagnetic fields through an elliptical hole in a wall of finite thickness

The penetration of electromagnetic fields through an elliptical hole of variable eccentricity in a wall of finite thickness is analyzed. Six cases are considered: p/spl ap/0, 0.2, 0.4, 0.6, 0.8, 1, where p=(a-b)/(a+b), a and b being semimajor and semiminor axes of the ellipse. Polarizabilities and susceptibilities are calculated. Results for zero-thickness wall are compared to known analytical expressions. >
Distribution-Free Statistical Tests

As a result of an extensive survey of the literature, a large number of distribution-free statistical tests are examined. Tests are grouped together primarily according to general type of mathematical derivation or type of statistical "information" used in'conducting the test. Each of the more important tests is treated under the headings: Rationale, Null Hypothesis, Assumptions, Treatment of Ties, Efficiency, Application, Discussion, Tables, and Sources. Derivations are given and mathematical interrelationships among the tests are indicated. Strengths and weaknesses of individual tests, and of distribution-free tests as a class compared to parametric tests, are discussed.
Antenna array pattern synthesis in the presence of near-zone scatterers : Three-dimensional vector case

A method for the array pattern synthesis in the presence of near-zone scatterers in the three-dimensional vector case is presented. The synthesis is based on the minimization of an objective function using the simulated annealing technique. In order to take into account the effects of the scatterers, the physical optics approximation is used. The polarization in both the incident and the scattered fields is also taken into account. Examples for a 10 x 10-element planar array of dipoles in the presence of a perfectly electric conducting cylinder are presented.
Influence of Turbulence Modeling on Predictions of Turbulent Combustion

Computations of an axisymmetric bluff-body stabilized turbulent diffusion flame are presented. The effects of turbulence modeling on turbulent combustion predictions are studied. The test case is simulated using κ-e and Reynolds-stress-equation turbulence models with and without extensions for low Reynolds numbers. Turbulent combustion is modeled by two different combustion models with fast chemistry. Effects of chemical kinetics are studied by including detailed chemistry in one combustion model. The combustion predictions are considerably affected by the choice of turbulence model. The nonpremixed flame is stabilized by a recirculation zone behind the bluff body. In isothermal, nonreacting flow, the predictions of the recirculation zone are quite similar for the four models. With combustion, a Reynolds-stress-equation closure predicts a significantly weaker recirculation compared with the κ-e results. This allows a larger spreading of the fuel and better mixing in the bluff-body wake. When finite-rate chemistry is introduced, the κ-e model predicts blow out, whereas the Reynolds-stress-equation model does not. This is due to the larger spreading and mixing by the latter model. The low-Reynolds-number extensions gave a much too strong recirculation, which reduced the spreading of the fuel jet.
The Characteristics of Electrocardiography Findings in Left Ventricular Remodeling Patterns of Hypertensive Patients

The exact diagnosis of left ventricular hypertrophy (LVH) is very important in the treatment of hypertension. The purpose of our study is to determine the relationship between left ventricular remodeling patterns and electrocardiography (ECG) findings in hypertensive patients. We divided 137 patients into four groups according to left ventricular mass index (LVMI) and the relative wall thickness: normal, concentric remodeling, concentric hypertrophy, eccentric hypertrophy. LVH on the ECG was defined by three ECG criteria: Sokolow-Lyon voltage criteria, Cornell voltage criteria and Romhilt-Estes point score. LVH on the echocardiography was defined by LVMI. The prevalence of ECG LVH was increased in concentric hypertrophy and eccentric hypertrophy group. The QRS voltages by Sokolow-Lyon voltage criteria (r = 0.494, P = 0.002) and Cornell voltage criteria (r = 0.628, P < 0.001), and Romhilt-Estes point score (r = 0.689, P < 0.001) were positively correlated with LVMI. Also, the QRS voltages and point scores were significantly increased in the concentric hypertrophy and eccentric hypertrophy group with increased LVMI. The QRS voltage and Romhilt-Estes point scores were positively correlated with LVMI. The QRS voltages and Romhilt-Estes point scores were also increased in the left ventricular remodeling groups with increased LVMI.
Interchannel interference cancellation in wireless OFDM systems via Gauss-Seidel method

In a mobile fading environment, the time variation of the wireless channels is a dominating factor that leads to the system performance loss. Multipath delay spread also lead to a loss of subchannel orthogonality in orthogonal frequency division multiplexing (OFDM) system, known as interchannel interference (ICI). In this paper, we first analyze the influences of ICI in mobile OFDM system. It is shown that ICI is only a function of the symbol energy (E/sub s/), the subchannel number (N) and the Doppler frequency (f/sub D/) in OFDM system, and is independent of signal constellation. To eliminate ICI, an equalization algorithm based on Gauss-Seidel method is then proposed. The main advantage of the iterative algorithm is to update the data vector x/sup (k)/ in each iterative step as soon as the part of the new data vector x/sup (k+1)/ have been calculated, therefore, the convergence of the algorithm can be accelerated effectively. The symbol error rate for a 16-QAM system is presented by means of simulation results to confirm the effectiveness of the proposed algorithm.