Miracle-dz/UniFAR-FTUs huggingface dataset:
Efficient iterative solvers for elliptic finite element problems on nonmatching grids

A new approach to the construction of iterative methods for solving systems of linear algebraic equations in the saddle-point form arising from finite element discretizations with nonmatching grids for elliptic boundary value problems is considered. The elliptic problem is presented in the macro-hybrid form based on domain decomposition with Lagrange multipliers at the interfaces between subdomains. A block diagonal preconditioner is proposed which is spectrally equivalent to the original saddle-point matrix and has the optimal order of arithmetical complexity. The preconditioner includes blocks for preconditioning subdomain and interface problems. It is shown that constants of spectral equivalence are independent of values of coefficients, grid step sizes, and diameters of subdomains. In this paper we propose a new approach to the construction of iterative methods for solving systems of linear algebraic equations which arise under a finite element approximation of elliptic differential problems with symmetric positive definite operators on nonmatching grids. More precisely we shall deal with the mortar finite element method which has been proposed recently. These algebraic systems have the form of an algebraic saddle-point problem. The original elliptic problem is posed as a problem with Lagrange multipliers at interfaces between subdomains, into which the original domain is decomposed, and with the continuity conditions of the solution (in a weak form) at the same interfaces. The Dirichlet boundary conditions, if any, are also given by Lagrange multipliers. Each of the subdomains has its own grid (a triangular one for two dimensional equations and a tetrahedral one for three dimensional equations) and the corresponding piecewise linear finite element subspace. A mortar finite element subspace is constructed in the space of Lagrange multipliers. The accuracy of these finite element approximations is not the topic of this paper. At present there are several approaches to the iterative solution of finite element systems on nonmatching grids, presented, for example, in [1,2,33]. At the same time there is a great number of works on the iterative methods for solving algebraic systems in the saddle-point form [4,7,12,19,31]. It is obvious that these methods, when appropriately modified, may be employed for solving the above finite element systems. In this paper we propose a new approach to the construction of block diagonal preconditioned for the algebraic systems that occur in using the mortar finite element method. This approach combines the ideas of the domain decomposition method (the substructure method) [6,16,20,32,36] with the algorithms of multilevel and algebraic multigrid methods [3,13,22,26,36]. The outline of this paper is as follows. In Section 1 we pose the problem, give its finite element discretization, and propose a new approach to the construction of a * Institute of Numerical Mathematics, Russian Academy of Sciences, Moscow 117334, Russia
Anatomical constraints for neuromagnetic source models

The localization of neural electromagnetic sources from measurements at the head surface requires the solution of an inverse problem; that is, the determination of the number, location, spatial configuration, strength, and time-course of the neuronal currents that give rise to the magnetic field or potential distribution. In most general form, the neuromagnetic and electrical inverse problems are ill-posed and have no unique solution; however, approximate solutions are possible if assumptions are made regarding the shape and conductivity of the head and the number and configuration of neuronal currents responsible for the surface distributions. To help resolve ambiguities and to reduce the number and range of free parameters required to model complex neuromagnetic sources, the authors are investigating strategies to constrain the locations of allowable sources, based on a knowledge of individual anatomy. The key assumption, justified by both physiological evidence and theoretical considerations, is that the dominant neuromagnetic sources which contribute to surface field distributions reside within the cortex. It is demonstrated that anatomically constrained source modeling strategies can produce significant improvements in source localization; however, the conclusion is that additional improvements in model fitting or source reconstruction procedures are required.
How the Culture in School Counseling Programs Shapes College-Going Outcomes: Do the Effects Vary by Race?

This study examined how the culture in school counseling programs or departments shapes the college-related outcomes of high school students including students of color. With data from the High School Longitudinal Study 2009, we investigated two major steps in the college-going process: (a) whether students see the counselor for financial aid counseling and (b) whether they seek college admissions counseling in 12th grade. We discuss the literature on the role of school counselors in college access, especially support for students of color, and how school counseling contextual variables and school counselor mindsets, which we term school counseling college-going culture (SCCGC), affect students’ college-going decisions. We conducted logistic regression analyses by racial/ethnic groups among 9170 high school students from the High School Longitudinal Study 2009–2016 dataset. The results indicated that counselor expectations, priorities, student–counselor contact prior to 12th grade, college and career readiness activities, and constraints affect students’ college outcomes differently across racial and ethnic backgrounds. This study has implications regarding what interventions, mindsets, and practices school counselors need in order to improve college-going outcomes (e.g., student–counselor contact for college admissions and financial aid counseling) for students from diverse racial and ethnic backgrounds.
Muscle innervation zone estimation from monopolar high-density M-waves using principal component analysis and radon transform

This study examined methods for estimating the innervation zone (IZ) of a muscle using recorded monopolar high density M waves. Two IZ estimation methods based on principal component analysis (PCA) and Radon transform (RT) were examined. Experimental M waves, acquired from the biceps brachii muscles of nine healthy subjects were used as testing data sets. The performance of the two methods was evaluated by comparing their IZ estimations with manual IZ detection by experienced human operators. Compared with manual detection, the agreement rate of the estimated IZs was 83% and 63% for PCA and RT based methods, respectively, both using monopolar high density M waves. In contrast, the agreement rate was 56% for cross correlation analysis using bipolar high density M waves. The mean difference in estimated IZ location between manual detection and the tested method was 0.12 ± 0.28 inter-electrode-distance (IED) for PCA, 0.33 ± 0.41 IED for RT and 0.39 ± 0.74 IED for cross correlation-based methods. The results indicate that the PCA based method was able to automatically detect muscle IZs from monopolar M waves. Thus, PCA provides an alternative approach to estimate IZ location of voluntary or electrically-evoked muscle contractions, and may have particular value for IZ detection in patients with impaired voluntary muscle activation.
Nadir creatinine as a predictor of renal outcomes in PUVs: A systematic review and meta-analysis

Background Posterior urethral valves (PUVs) represent the most severe pediatric obstructive uropathy, responsible for chronic renal failure in up to 65% of cases and progression to end-stage kidney disease (ESKD) in about 8%–21% of patients. Unfortunately, renal outcomes have poorly improved over time. The key point is to identify patients at risk; thus, several prenatal and postnatal prognostic factors have been analyzed to improve clinical outcomes. Postnatal nadir creatinine seems to accurately predict long-term renal prognosis, but there is no definitive evidence to support this finding. Objective We performed a systematic review with meta-analysis to analyze the predictive value of nadir creatinine on long-term renal function in infants with PUVs. Methods We conducted this systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed and Cochrane Library were systematically searched for studies published from January 2008 to June 2022. All the articles were checked independently by two reviewers in two steps. Results A total of 24 articles were screened, and 13 were included for data extraction. Data from 1,731 patients with PUVs were analyzed, with a mean follow-up of 5.5 years; of these, on average, 37.9% developed chronic kidney disease (CKD) and 13.6% developed ESKD. All the articles evaluated nadir creatinine as a predictor of CKD, most using a level of 1 mg/dL, with statistical significance at the 5% level. The relative risk of developing CKD in patients with creatinine values higher than the nadir cutoff considered was 7.69 (95% CI: 2.35–25.17, I2 = 92.20%, p < 0.001). Conclusions Nadir creatinine is the best prognostic factor for long-term renal function in patients affected by PUV. A value above the cutoff of 1 mg/dL should be considered a significant predictor for the risk of CKD and ESKD. Further studies are needed to define different nadir creatinine cutoffs for better stratification of the different CKD stages and for the development of reliable scores, which include the association of several variables.
Direct measurements of slip in sheared polymer solutions

We report direct measurements of slip flow during and after plane-Couette shearing of poly(styrene) solutions between glass surfaces. Slip is studied by visualizing the microscopic motions of micron-sized silica spheres suspended in the solutions. Slip velocities as large as 4 μm s−1 are observed during shear, and recoil displacements of as much as 80 μm are observed at the glass surfaces after the driving surface stops moving. Significant slip is observed when the Weissenberg number $\lambda\dot{\gamma}$ exceeds 0.5 or so, where λ is the relaxation time and $\dot{\gamma}$ the shear rate. The magnitude of the slip correlates strongly with the fluid's birefringence, indicating that slip is induced by polymer stress or orientation. Away from the centre of the sample, toward the free edges, a secondary flow is observed, which appears to be driven by a normal-stress imbalance at these edges.
Physical and thermal modification of selected lignocellulosic raw materials

The impact of the modification of the plasticizing system of the TS-45 single-screw extruder (by ZMCh Metalchem, Gliwice, Poland) with L/D = 12 is discussed in the article. The modification involved the reconfiguration of the extruder screw to achieve certain selected physical characteristics of the lignocellulosic raw materials which are not commonly used in biogas facilities. Shredded lignocellulosic raw materials (corn straw, wheat straw, and hay) were moistened to achieve a 25% water content and extruded at three rotational speeds of the extruder screw: 70, 90, and 110 rpm. During extrusion-cooking, the process efficiency and energy intensity were determined. The obtained extrudates were studied in order to establish selected physical properties (water solubility index, water absorption index and bulk density). In addition, the research included an analysis of microscopic images and the efficiency of cumulative methane and biogas production per fresh mass, dry mass, and dry organic mass. In addition, an analysis of the FTIR infrared spectra of the studied extruded samples was performed, these contained lignocellulose structures, and revealed explicit changes at the molecular level. The use of the extrusion technique as a pretreatment of the plant biomass allowed for the lignocellulosic bonds to be broken, which loosened the structure of the material and thus changed its physical properties and biogas efficiency.
Higher order nonlinear effects on wave structures in a four-component dusty plasma with nonisothermal electrons

The higher order solutions of dust acoustic wave in dusty plasma consisting of positively charged warm adiabatic dust, negatively charged cold dust, and nonisothermally distributed electrons are studied. The Schamel–KdV equation is derived using reductive perturbation method (RPM). RPM is further extended to include the contributions of higher order terms and a generalized KdV equation is derived to observe the deviation from isothermality. Effects of nonisothermal parameter, mass and charge ratio, ratio of ion to electron temperatures, and ratio of dust to ion temperatures have been thoroughly studied. By using the renormalization method of Kodama and Taniuti [J. Phys. Soc. Jpn. 45, 298 (1978)], authors have also discussed characteristics of the dressed solitons.
Juggling Masculinities: Being a Middle-Class Young Man in Dhaka

To date, South Asian masculinity studies have largely investigated the construction of masculinities at the structural level, while subjective experiences have received little attention. This paper analyses data gathered from ethnographic research conducted among 40 adolescent boys living in Dhaka, Bangladesh, and asks: how do middle-class adolescent boys in Dhaka construct different ideals of masculinity and negotiate those in their everyday life at home and among peers? Which ideas about sexuality are involved? This analysis provides in-depth insights into the ways in which different models of masculinity are (re)constructed and embraced or resisted at the subjective level by adolescents in their everyday negotiations of sexuality. We will argue that this younger generation of men encounter unique gendered vulnerabilities in the contexts of fast urbanisation, an increasingly uncertain labour market and a lack of support in negotiating their emotional and social wellbeing.
A comparison of numerical and asymptotic mega solutions of the αω-dynamo problem

Abstract The Maximally Efficient Generation Approach (MEGA) is a method to find approximate solutions in a region where strong differential rotation (ω-effect) and helicity (α-effect) coexist (Ruzmaikin et al., 1990). In this paper, new general MEGA-type solutions were obtained in the form of simple analytical formulas. It is shown that MEGA gives a WKBJ type solution to αω-dynamo problem with turning point at the maximum of the product of α- and ω-effects. MEGA attains a higher accuracy if there is a clear maximum of this product in real space far from the boundaries, which is the most usual case in real situations. The approximated eigenvalue depends crucially on the distribution of the product of α- and ω-effects, but not much on the particular distributions of the individual effects. The predicted eigenvalues and eigenfunctions were compared with the solutions from numerical analysis. It was found that the critical Reynolds numbers and oscillation frequencies predicted by the MEGA method are very clos.
PROOF OF UNIQUENESS OF THE KERR-NEWMAN BLACK HOLE SOLUTION

The electrovacuum Ernst equations are formulated as a nonlinear sigma -model on the symmetric (Kahler) space SU(1,2)/S(U(1)*U(2)). It is shown, using this formulation, that a generalised Robinson-type identity for the electrovacuum Ernst equations may be derived. A special role played in the derivation of this identity by the hidden symmetry group SU(1,2) is established. A theorem is proven that the only possible exterior solution for a (pseudo-) stationary, rotating, electrovacuum black hole with non-degenerate event horizon is the Kerr-Newman solution with m2-a2-P2-Q2>0.
How does static stretching decrease the dielectric constant of VHB 4910 elastomer?

Subject to a voltage, dielectric elastomers deform by the effect of Maxwell stress which is depended directly on the dielectric constant of the material. The combination of large strain, soft elastic response and good dielectric properties has established VHB 4910 elastomer as the most used material for dielectric elastomer actuators. However, the effect of stretch on the dielectric constant for this elastomer is much debated topic while controversy results are demonstrated in the literature. The dielectric constant of this material is studied and demonstrated that it decreases slightly or hugely among the stretch but any pertinent response and any physic explications are validated by the scientific community. In this paper, we presented a detail study about dielectric behavior of VHB 4910 elastomer versus a broadband of stretch and temperature. We found that the dielectric constant of this material depends strongly on the stretch following a polynomial law. Among all the explanations of stretch dependence of the dielectric constant of VHB 4910 in the literature: the crystallization, the change of glass transition temperature, the decrease of dipole orientation, the electrostriction effect under stress; and based on our experimental result, we conclude that the decrease of dipole orientation seems the main reason to the drop of dielectric constant of VHB 4910 elastomer versus the stretch. We proposed also an accurate model describing the dielectric constant of this material for a large range of stretch and temperature.
Implicit integration algorithm for elastoplasticity in plane stress analysis

An implicit integration algorithm for elastoplastic constitutive equations in plane stress analysis is presented. The error associated with this algorithm is of the same order as the one reached in three‐dimensional analysis with the radial return algorithm. No subincrementation is needed. Moreover, the exact elastoplastic stress—strain matrix related to this algorithm is derived.
Effects of stress on school bullying behavior among secondary school students: Moderating effects of gender and grade level

This study investigated the effects of stress on school bullying behaviors among middle school students, and the moderating role of gender and grade level in this relationship. To this end, the Olweus Child Bullying Questionnaire (OBVQ) secondary school version of the child bullying questionnaire and the stressor scale for secondary school students were used to survey 3,566 secondary school students in Guizhou Province, and the data were statistically analyzed. Results showed that stress was significantly and positively associated with school bullying among secondary school students. Furthermore, both gender and grade moderated the relationship between stress and school bullying, showing that boys and middle school children are more likely to engage in bullying than girls and high school students, respectively. The results of the study provide a theoretical basis for the prevention and intervention of school bullying behaviors among middle school students.
Tracking Epidemiological Characteristics and Risk Factors of Multi-Drug Resistant Bacteria in Intensive Care Units

Objectives Multi-drug resistance (MDR) emerged as a serious threat in intensive care unit (ICU) settings. Our study aimed to investigate the major pathogens in ICU and identify the risk factors for MDR infection. Methods We performed a retrospective analysis of patients admitted to the ICU. Multivariate logistic regression was applied to identify the independent predictors, and then a nomogram to predict the probability of MDR infection. Results A total of 278 patients with 483 positive cultures were included. 249 (51.55%) had at least one MDR pathogen, including extensively drug-resistant (XDR) 77 (30.92%) and pan drug-resistant (PDR) 39 (15.66%), respectively. Klebsiella pneumonia was the most frequently isolated pathogen. We identified the number of bacteria (OR 2.91, 95% CI 1.97–4.29, P < 0.001), multiple invasive procedures (OR 2.23, 95% CI 1.37–3.63, P = 0.001), length of stay (LOS) (OR 1.01, 95% CI 1.00–1.02, P = 0.007), Hemoglobin (Hb) (OR 0.99, 95% CI 0.98–1.00, P = 0.01) were independent risk factors for MDR infection. Our nomogram displayed good discrimination with curve AUC was 0.75 (95% CI: 0.70–0.81). The decision curves also indicate the clinical utility of our nomogram. Additionally, the in-hospital mortality with MDR pathogens was independently associated with XDR (HR, 2.60; 95% CI: 1.08–6.25; P = 0.03) and total protein (TP) (HR, 0.95; 95% CI: 0.91–0.99; P = 0.03). Conclusion The number of bacteria, multiple invasive procedures, LOS, and Hb were the independent predictors associated with MDR pathogens. Our nomogram is potentially useful for predicting the occurrence of MDR infection. Besides, we also identify XDR and TP as the independent risk factors for in-hospital mortality with MDR infection. The current prevalence of MDR strains was also described. The results will contribute to the identification and preventive management of patients at increased risk of infection.
Harmonic Solution of Unsteady Flow Around Blades with Separation

Conventional time-linearized harmonic methods using a pseudo-time-marching technique often exhibit solution divergence behavior for highly loaded conditions with flow separation. This is attributed to the growth of linear instabilities associated with small-scale limit-cycle oscillations of the base-flow state. In the present work, an alternative harmonic formulation is adopted for modeling harmonic disturbances with an intention to harness nonlinearity as a means of stabilization while achieving the same computational efficiency as a conventional time-linearized model. One unsteady complex-number harmonic solution is made equivalent to two real-number steady-flow solutions with simple source terms, whereas nonlinearity is retained in the convective fluxes of discretized flow equations. The validity and effectiveness of the method has been demonstrated in comparisons with semi-analytical results for a flat plate cascade and experimental data for low- and high-speed turbine cascades. The computational results show that the present harmonic solver is robust with much improved convergence over the conventional time-linearized model. It is shown that converged solutions can be effectively obtained using the present method for unsteady flows with large-scale separation.
Smooth Transition of Safety Controllers Filtered by Control Barrier Functions

Recently, control barrier functions (CBFs), are becoming popular and widely used as a safety-filter of the controller through quadratic programming(QP) optimization framework to ensure the forward invariance of the dynamic systems. However, for sequential safety tasks, the transitions of CBFs are required. To avoid control input discontinuities, firstly, a smooth and speed adjustable transition mechanism by adding a time-varying coefficient of different CBFs is proposed. Moreover, the value of the previous CBF constraint is fixed to reduce the change of the combined CBF constraint. Secondly, a method to integrate different sequential CBFs into a synthetic new one is presented. Through these methods, the smoothness of optimized control inputs can be ensured compared with existing formulations. Simulation results demonstrate that our algorithm provides a smoother transition mechanism to switch different CBFs, and improves the control performance consequently.