Miracle-dz/UniFAR-FTUs huggingface dataset:
Students' epistemological beliefs, expectations, and learning physics: An international comparison

It has been established by physics education researchers that there is a correlation between the learner's behavior, their epistemological beliefs with which they come to the classrooms, and their success in a course. This study of Indian students and teachers explores expectations and beliefs in learning physics at the secondary and tertiary levels by making use of the Maryland Physics Expectation (MPEX) survey, which has been tested for both its validity and its reliability. The MPEX was administered to a sample of 265 Indian students at three different levels of study: (i) XII standard (high school), (ii) undergraduate (Bachelor of Science), and (iii) master's degree (Master of Science in Physics, MS). In India, a pre-post instruction difference between the attitudes of class XII, undergraduate, and master's students is observed with favorable improvement in master's students as compared to deterioration in both class XII and undergraduate students. A comparison of these results with those reported in similar studies conducted in four other countries (U.S., Turkey, Philippines, and Thailand) indicates that there is a difference between the U.S. students and those of the other three countries and also between U.S. experts and Indian teachers. In all countries (U.S., India, Turkey, Thailand, and Philippines) the basic trend of expectation from pre to post test remained the same---there was a deterioration observed in all levels of students. Indian MS students were an exception. A significant difference was observed in the expectations of U.S. experts and Indian teachers. The score of favorable views of Indian class XII and undergraduate students was observed to be less than U.S. students in many clusters. No significant difference was found between Indian male and female students' expectations at any level of study. This study shows that most Indian students have nowhere near an expert's expectations even after instruction, which might affect their motivation and success in physics courses and may have long-term implications on the quality of physics education in schools, colleges. and universities and the scientific research aspirations of the country.
BESO échelle spectroscopy of solar-type stars at Cerro Armazones

The Bochum Echelle Spectroscopic Observer BESO is a fibre-fed high-resolution spectrograph for the 1.5-m Hexapod Telescope at the Cerro Armazones Observatory in the Atacama desert in Chile. Here we report on the first BESO observations and model atmosphere analyses of solar-type stars secured in 2010 April. The quality of the data is first tested with a reflected sunlight spectrum as well as the standard G-type subgiant 70 Vir. We then investigate the bright and supposedly single F-type star ξ Gem and present the spectroscopic evidence that instead favours an equal-mass binary. We present also the first composite synthetic modelling of the G-type visual binary HR 3430 and discuss the spectroscopic observations that identify this as a triple system. We conclude with another triple, the famous and very nearby α Cen, and the basic stellar parameters of its inner, solar-type visual binary.
Competence in mathematics–more than mathematical skills?

Research with first year engineering students on an extended programme at the University of Pretoria indicates that competence in mathematics can be enhanced through academic support that combines the development of mathematical and non-mathematical skills. This paper investigates the effect of this approach on students' performance in mathematics and their tertiary academic success. Longitudinal data based on student feedback and the performance of the 2000 and 2001 group of first entrant students who enrolled for the extended programme is presented. The achievement in mathematics and the graduation of students are compared. Results indicate that the achievement in mathematics of at-risk students who received developmental support compares favourably with that of students on the standard study programme in engineering. Analysis of student feedback indicates that support given at first year level can be regarded as an important contributor to both competence in mathematics as well as the successful completion of engineering study.
Modeling of the stabilization of neoclassical tearing modes by localized radio frequency current drive

Numerical modeling of the stabilization of neoclassical tearing modes by localized radio frequency (rf) current drive is presented. The bootstrap current is self-consistently calculated from the pressure evolution equation, the rf current source is obtained from the ray-tracing code and the Fokker–Planck code, and the change of the driven current profile due to the change of the magnetic island width has also been taken into account by modeling the two-dimensional transport of the fast electrons induced by the rf wave. It is found that both parallel and the perpendicular transport of the fast electrons play important roles in the stabilization, and modulated and nonmodulated rf current drive have approximately the same stabilizing effect. The neoclassical tearing modes is shown to be stabilized by a continuous rf current drive. The simulation results essentially agree with experimental observations.
1994-1996 OPTICAL OUTBURSTS OF THE BL LAC OBJECT OJ 287

VRI bands CCD photometric observations of the BL Lac object OJ 287 have been carried out during the period from 1994 October to 1196 May, with a mean interval of about a week. OJ 287 underwent two major outbursts during our observations. The first peak (V = 14.0 mag) occurred in the first half of 1994 November and faded out to 16.5 mag within 150 days. The second peak (V = 14.0 mag) was observed in the second half of 1995 December. The latter peak continued at nearly the same brightness until 1996 May. Such a long lasting outburst has never been reported for OJ 287. Color indices (V - R and V - I) remained nearly constant during the interval.
Mixed convection heat transfer in rotating vertical elliptic ducts

This paper presents an investigation into the solution of laminar mixed convective heat transfer in vertical elliptic ducts containing an upward flowing fluid rotating about a parallel axis. The coupled system of normalized conservation equations are solved using a power series expansion in ascending powers of rotational Rayleigh Number, Rat - a measure of the rate of heating and rotation as the perturbation parameter. The results show the influence of rotational Rayleigh number, Rat and modified Reynolds number, Rem on the temperature and axial velocity fields. The effect of Prandtl number, Pr, in the range 1 to 5, and eccentricity, e on the peripheral local Nusselt number are also reported. The mean Nusselt number is observed to be highest at duct eccentricity, e=0 for a given Prandtl number. However, results indicate insensitivity of peripheral local Nusselt number to Prandtl number at eccentricity, e=0.866, which is an important result to a designer of rotating vertical heat exchanger. The effect of eccentricity on the friction coefficient is also presented. The parameter space for the overall validity of the results presented is Rat RemPr<820.
The periodic instability of thermocapillary convection in cylindrical liquid bridges

Thermocapillary convection (TC) in cylindrical liquid bridges (floating zones) of liquids with Prandtl numbers Pr=1, 7, and 49 is investigated experimentally. The zones have been heated from above or from below to study the influence of buoyant forces. Fourier analyses of temperature signals from zones covering systematically wide ranges of aspect ratios A and Marangoni numbers Ma have shown the existence of various forms of periodic and nonperiodic TC. This paper reports on periodic TC existing under certain conditions between the onset of time‐dependent TC at the critical Marangoni number Mac and 7×Mac. From the measurements of the onset of periodic TC the dependence is reported for the threshold Mac and the period near the threshold τc on the aspect ratio. The development of periodic TC when further increasing Ma is shown by typical examples from measurements of the frequency and the amplitude of the oscillations. By correlation analyses from three temperature signals, different structures of periodic .
Feature reconstruction in inverse problems

A strategy for the derivation of fast, accurate and stable algorithms for combining the reconstruction and the feature extraction step for solving linear ill-posed problems in just one method is presented. The precomputation of special reconstruction kernels with optimized parameters for the combination of the two tasks allows for fast implementations and better results than separate realizations. The concept of order optimality is generalized to the solution of feature reconstruction and to Banach spaces in order to find criteria for the selection of suitable mollifiers. Results from real data in different tomographic modalities and scanning geometries are presented with the direct calculation of derivatives, as in Canny edge detectors, and the Laplacian of the solution used in many segmentation algorithms. The method works also when the searched-for solution is not smooth or when the data are very noisy. This shows the versatility of the approach.
Fine-Structure Transitions of Si II with Interest in Astrophysics

Oscillator strengths of the dipole-allowed fine-structure transitions in Si II between the terms belonging to the 3s2 nl (n = 3-10) and l = 0-3 configurations have been calculated in the LS-coupling scheme using the Relativistic Quantum Defect Orbital method, with and without accounting explicitly for the core-valence correlation. The present f-values are compared with other available results for this astrophysically important ion, and good agreement has been found.
Partial regularity and everywhere continuity for a model problem from non-linear elasticity

Abstract We prove a new energy or Caccioppoli type estimate for minimisers of the model functional ∫Ω|Du|2 + (det Du)2, where Ω ⊂ 2 and u: Ω → 2. We apply this to establish C∞ regularity for minimisers except on a closed set of measure zero. We also prove a maximum principle and use this to establish everywhere continuity of minimisers.
Dispersion characteristics of diffused channel waveguides

A variational method is used to calculate dispersion curves for channel waveguides fabricated by masked diffusion. Composition profiles for the waveguides are obtained by numerical solution of the diffusion equation, assuming that the diffusant concentration in the unmasked region of the substrate surface is constant during the diffusion process. A linear dependence of refractive index change on diffusant concentration is assumed. The dependence of the number of guided modes on mask gap width and diffusion depth is determined as an aid to the design of modulators and switches for integrated optics.
A note on certain subrings and ideals of prime rings

Let R be a noncommutative prime ring with symmetric ring of quotients Q,with extended centroid C and with derivation D, let n be a positive integer.Given x,y ϵ R, we set Suppose that D≠ad(a) for any a ϵQ such that (a + c) 2= 0 for some c ϵC, and either char(R ≥ n+1 ≥ 3, or char(R) = 0.We show that the subring of R generated by , contains a nonzero ideal of R.
An order-of-magnitude approximation for the hybrid terms in the compressible hybrid RANS/LES governing equations

The present work follows up our previous development in the compressible hybrid Reynolds-averaged Navier–Stokes (RANS)/large eddy simulation (LES) methodology (M. Sánchez-Rocha and S. Menon, The compressible hybrid RANS/LES formulation using an additive operator, J. Comput. Phys. 228 (2009), pp. 2037–2062). In that original work, the exact compressible hybrid RANS/LES (HRL) equations were formally derived revealing the existence of additional hybrid terms (HT) that depend explicitly on the LES and RANS variables. The importance of the exact equations was established in flat-plate turbulent boundary layers, demonstrating that the law-of-the-wall could not be accurately reproduced if the HT were not included. Unfortunately, the new HT could not be directly computed since it is required to reconstruct the LES variables from the hybrid field—a task that is equivalent to an inverse filtering operation that in general is ill-conditioned. Therefore, in our original work, parallel LES simulations were conducted to provide the LES field to close the HRL equations. In the present work, a simple model is proposed to reconstruct the LES field from the hybrid variables to close the exact hybrid equations. The model is obtained by manipulating the HRL operator and by order-of-magnitude estimations. Here it is stressed that the approximated LES field is used only to compute the HT and not to compute flow statistics. Numerical calculations for a flat-plate turbulent boundary layer at Re θ=1400 are conducted to evaluate the performance of the approach proposed against previous hybrid studies. Simulations using the approximated HT are compared against hybrid calculations without the HT, simulations using the exact HT, and LES simulations. Overall, the results obtained with the approximated HT favorably compare with LES and experimental data. The sensitivity of the new approach to the blending function implemented is also addressed, and it is found that with the modeled HT, the mean velocity profile is correctly predicted independently of the blending function used. Finally, the effect of the grid resolution on the model proposed is evaluated by increasing the Reynolds number (Re θ=3330); results for this case are found in reasonable agreement with experimental data and LES calculations.
Stabilization of linear parameter-dependent systems using eigenvalue expansion with application to two time-scale systems

An eigenvalue expansion method is applied to the stability analysis and stabilization of linear parameter-dependent systems in the neighborhood of a specified system parameter. The system, at the parameter of interest, is assumed to possess distinct eigenvalues on the imaginary axis. The asymptotic stability conditions, which rely on Taylor series expansions of the continuous extensions of the critical eigenvalues with respect to system parameters, are algebraic and are given in terms of the system dynamics and the critical eigenvectors. Asymptotically stabilizing control laws are designed for the case in which the system at the specified parameter has uncontrollable eigenvalues on the imaginary axis. Application of these results yields computational algorithms for the stability analysis and stabilization design of two-time scale linear systems. <<ETX>>
Responses of the open–closed field line boundary in the evening sector to IMF changes: A source mechanism for Sun‐aligned arcs

[1] Simultaneous measurements from the Polar satellite and by ground-based optical sensors suggest that brief variations of the poleward auroral boundary on the nightside correlate with changes in the interplanetary magnetic field (IMF) about an hour after a structure has propagated in the solar wind past the Earth. Short-lived Sun-aligned arcs may emerge along the open–closed magnetic field line boundary (OCB) and then disappear after ∼10 min. The arcs are fueled by energetic particles whose spectral characteristics are similar to those of the of boundary plasma sheet (BPS). Polar measurements confirm that these auroral protrusions into the polar cap occur on nearly isolated closed magnetic flux. Optical emissions from these arcs appear strongest at their intersection with the poleward boundary of the auroral oval. Detailed magnetohydrodynamic (MHD) simulations of dayside interactions, when the dominant IMF component BY changes sign, indicate that near the polarity reversal merging can occur between interplanetary field line segments within the magnetosheath [Maynard et al., 2001b]. Newly formed loops of interplanetary flux sweep past the Earth without interacting with the magnetosphere. Here, we consider some consequences within the distant magnetotail as the loops of disconnected flux propagate to XGSM ≈ −200 RE. The MHD simulations indicate that about an hour after intra-IMF merging events fingers of closed field lines protrude from the OCB into the polar cap. Like the observed Sun-aligned arc, these simulated auroral features grow and decay on scales of ∼10 min and have ionospheric footprints that are nearly surrounded by open magnetic flux. The simulated auroral fingers are conjugate to high-pressure channels in the distant plasma sheet. We suggest that the short-lived Sun-aligned arcs are created via an interchange process similar to that proposed by Kan and Burke [1985] to explain one class of theta auroral forms. The continuity of magnetotail currents across a high-pressure channel requires the development of field-aligned currents carried by obliquely propagating Alfven waves. Plasma drifts associated with the dusk-to-dawn electric fields of the Alfven waves are away from the Earth in the magnetotail and poleward in the nightside ionosphere. The correlation of phenomena at the nightside OCB with variations in the IMF indicate that processes other than substorms can influence boundary dynamics. Effects of self-interactions of the IMF within the dayside magnetosheath may be felt along the OCB as much as 1 hour later.
Stochastic optimization of conventional and holey double-clad fibres

Stochastic optimization is proposed for the pump absorption enhancement in double-clad fibres (DCFs). Monte Carlo forms of the Nelder–Mead (NM) method are proposed and benchmarked against a genetic algorithm (GA) and generalized pattern search (GPS) and mesh adaptive direct search (MADS) methods. A simple sampling NM variant offered the highest efficiency while MADS achieved global convergence with the highest probability in low dimensions. All algorithms examined are described within the pattern search frame while detailed pseudocode descriptions are given in structured functions. Smoothly perturbed patterns are proposed for implicitly constrained optimization in high dimensions. An improved Monte Carlo NM method, based on importance sampling and stochastically perturbed patterns, exhibited global convergence with higher efficiency than MADS in high dimensions. Many polymer and air outer cladding designs are optimized. A circular holey DCF with an optimally offset core and a single large solid-state hole with optimum offset, size and ellipticity offered 180% absorption enhancement over a conventional circular DCF with centred core.
Evaluation of the Relative Weight (Wr ) Index, with New Applications to Walleye

Abstract Relative weight (Wr ) is 100 × W/Ws , W being the weight of an individual fish and W the “standard” weight of a fish of the same length. The widespread application of relative weight in fisheries management has been hindered by the slow development of standard weights at length for many important fish species. We found the conventional approach to Ws development to be limited by data availability and improperly influenced by sample weighting. We designed and tested a method of Ws development that addresses these shortcomings. Our method treats log10weight-log10length regression equations for a series of a species' populations as the statistical population to be modeled. First, we predict mean fish weight in 1-cm total length intervals for each population. Then we find the 75th percentile of the mean weights in each interval, and regress these on length to determine the parameters for the Ws equation. Standard-weight equations determined by our regression-line-percentile (RLP) technique were funct.
Numerical simulations of eccentricity and end effects in falling ball rheometry

Finite element calculations, theoretical predictions, and experimental observations are combined to analyze wall and end effects for a wide range of ball sizes in falling ball rheometry. We find that reflection solutions, finite element calculations, and experimental data are indistinguishable for small balls approaching the cylinder bottom. For larger falling balls, finite element modeling predicts a significant increase in drag in comparison with the reflection solution. Our experimental measurements are in very good agreement with the predictions of the finite element calculations and confirm the relative drag increase. For balls falling off the centerline of the cylinder, analytical solutions are restricted to the limiting cases of very small balls and large balls only slightly smaller than the containing cylinder. In this report, intermediate ball sizes are studied with three‐dimensional finite element codes. The finite element predictions for the intermediate ball sizes are qualitatively similar to .
On the state of the emitter of the 3.3 micron unidentified infrared band - Absorption spectroscopy of polycyclic aromatic hydrocarbon species

Results of absorption measurements indicate that the PAH species responsible for the UIR (unidentified infrared) emission probably exist in a condensed form rather than as isolated molecules. It is shown that the peak absorption of the C-H stretch feature of vapor-phase PAHs occurs at a higher frequency than that of the condensed-phase PAHs and does not match the 3.289-micron interstellar feature. The vapor-phase experiments duplicate the phenomenon of the 3.3-micron profile simplification of PAH in KBr at elevated temperature. This confirms that the change of the profile with temperature is an intrinsic molecular effect, and is not a consequence of matrix (KBr) or condensed state interactions.
A nonparametric approach to the analysis of two-stage mark-recapture experiments

We present a new approach to the analysis of two-stage mark recapture experiments where individual covariates are available which describe the detectability of individuals in the population. Central to the theory is a single quantity α, which we call the heterogeneity index and which measures the variability in the detectability of individuals. This theory also has implications for the analysis of independent observer line transect surveys. An estimator of α is provided by combining kernel density estimates of the underlying densities of the covariate, conditional on capture histories. We derive expressions for the asymptotic bias and variance and show that our new estimator is as efficient as the Petersen estimator when individuals all have the sames detectability. We also report the results of a simulation study of the new estimator for a range of mark-recapture conditions.
Nonlinear thermodynamic quantum master equation: Properties and examples

The quantum master equation obtained from two different thermodynamic arguments is seriously nonlinear. We argue that, for quantum systems, nonlinearity occurs naturally in the step from reversible to irreversible equations and we analyze the nature and consequences of the nonlinear contribution. The thermodynamic nonlinearity naturally leads to canonical equilibrium solutions and extends the range of validity to lower temperatures. We discuss the Markovian character of the thermodynamic quantum master equation and introduce a solution strategy based on coupled evolution equations for the eigenstates and eigenvalues of the density matrix. The general ideas are illustrated for the two-level system and for the damped harmonic oscillator. Several conceptual implications of the nonlinearity of the thermodynamic quantum master equation are pointed out, including the absence of a Heisenberg picture and the resulting difficulties with defining multitime correlations.