Miracle-dz/UniFAR-FTUs huggingface dataset:
Collapse of magnetized molecular cloud cores. I: Semianalytical solution

In this paper we follow the evolution of an unstable magnetized cloud core modeled with the density distribution of a singular isothermal sphere and threaded by a uniform magnetic field. We include neutral-ion slip, and we solve the equations by an expansion about the known self-similar problem without magnetism. We find that the magnetic field does not significantly modify the standard rate of mass infall because of two offsetting effects: the Lorentz force that impedes gravitational collapse, and the increased characteristic speed that causes the initiation of infall to travel outward faster (as a fast magnetohydrodynamic wave rather than an acoustic wave)
On-the-fly scans for X-ray ptychography

With the increasing importance of nanotechnology, the need for reliable real-time imaging of mesoscopic objects with nanometer resolution is rising. For X-ray ptychography, a scanning microscopy technique that provides nanometric resolution on extended fields of view, and the settling time of the scanning system is one of the bottlenecks for fast imaging. Here, we demonstrate that ptychographic on-the-fly scans, i.e., collecting diffraction patterns while the sample is scanned with constant velocity, can be modelled as a state mixture of the probing radiation and allow for reliable image recovery. Characteristics of the probe modes are discussed for various scan parameters, and the application to significantly reducing the scanning time is considered.
On the Possibility of the Nonexplosive Core Contraction of Massive Stars. II. General Relativistic Analysis

We have investigated the possibility of nonexplosive core contraction of massive stars in the framework of general relativity by constructing equilibrium sequences of rapidly rotating compact stars with phenomenological equations of state for the high-density region. Since there are no satisfactory equations of state for the high-temperature/high-density region, we have devised a simplified equation of state that can be considered as representing an extremely soft equation of state for the high-density region. By analyzing the stabilities of equilibrium sequences with constant total angular momentum, we have shown that there is a chance of nonexplosive core contraction in from white dwarf to neutron star density regions. It is important to note that the pressure due to a high electron fraction and/or high temperature plays an essential role in making rapidly rotating stars dynamically stable against axisymmetric collapse. In general, both a very soft equation of state and general relativity tend to make the formation of "fizzlers" more difficult. Nevertheless, since there are parameter regions that allow for fizzlers even from general relativistic computations, the possibility of their existence becomes greater than ever in spite of our oversimplified equation of state.
Assessment, correction and impact of the dry bias in radiosonde humidity data during the MAP SOP

This study reports on the characteristics of humidity measurements in the Mesoscale Alpine Programme (MAP) radiosonde dataset. During the Special Observing Period (SOP) of MAP from 9 September 1999 to 15 November 1999, about 10 100 soundings from 51 sites were collected in the so‐called ‘high‐resolution data domain’. Of these, 39 used Vaisala RS80A radiosondes, which delivered 81% of all soundings. Additionally, five sites providing about 10% of all soundings used either Meteolabor SRS‐400, Graw or VIZ sondes equipped with carbon hygristors for humidity measurements, six sites (8% of all soundings) used Meteolabor temperature sondes without humidity measurement, and one site used Vaisala RS90 sondes. Quality control and careful analysis of the MAP upper‐air dataset revealed several characteristics including the dry bias in Vaisala RS80 radiosondes. Since about two thirds of the stations are part of the routine synoptic network and were operated during the MAP SOP without major procedural changes, this evaluation also allows us to characterize the backbone of the operational upper‐air observations.
A near-infrared spectroscopic study of the starburst core of M82

Near-IR spectroscopy of the M82 starburst core is presented, including complete J, H, and K band spectra with a resolution of 0.0035-micron for the inner 60 pc of the galaxy. Also, spatial profiles along the starburst ridge are presented for Br-gamma, molecular hydrogen, and forbidden Fe II line fluxes. Emission from shocked molecular hydrogen is detected from the core of M82. The distribution of features across the starburst disk are mapped to study the relationships between spectral diagnostics. The observations are used to test the appropriateness of single-beam, aggregate models for studying the physical conditions in starbursts. 68 refs.
Improved Inversion of Scanning Electrical Mobility Spectrometer Data Using a New Multiscale Expectation Maximization Algorithm

The accuracy of particle size distributions obtained from scanning electrical mobility spectrometer (SEMS) measurements is strongly dependent on the accurate consideration of the instrument characteristics in the formulation of the SEMS problem and the effective inversion of the resulting SEMS equation. The estimation of size distributions from SEMS measurements requires a solution of the discretized form of the Fredholm integral equation of the first kind. The often ill-conditioned nature of the linear inverse problem coupled with the possible presence of measurement noise complicates these calculations. The use of standard inversion approaches, such as nonnegative least squares (NNLS) or regularization-based algorithms, requires SEMS measurements with significant signal-to-noise ratio or some a priori knowledge of the shape of the sampled size distribution. These severe constraints for SEMS measurements can be relaxed with the new multiscale expectation-maximization SEMS inversion method introduced here. Performance testing with a broad range of sample size distributions and SEMS operating conditions suggests that the multiscale approach is generally more accurate than both the NNLS and regularization approaches. Copyright 2013 American Association for Aerosol Research
ON THE EFFICIENCY OF THE SAMPLE MEAN IN LONG‐MEMORY NOISE

When estimating the unknown mean of a stationary time series, the best linear unbiased estimator is often a significantly better estimator than the ordinary least squares estimates Xn. The relative efficiency of these two estimators is investigated for time series whose spectrum behaves like a power at the origin (e.g., fractional Gaussian noise and fractional ARIMA).
Dynamic Transition in a Two-Component Fluid in the Supercooled State

A mode-coupling model has been proposed to study the dynamics of a dense binary fluid. The present model includes a correct set of slow variables, which are consistent with the corresponding conservation laws. From the equations of fluctuating hydrodynamics for slow variables, a coupled set of nonlinear equations for various time-dependent correlations of density fluctuations are obtained. In the long-time limit, a self-consistent solution of these equations shows a dynamic transition, which occurs at a much higher density than predicted by the other existing models for the same systems. Our model brings the theoretical prediction for dynamic transition in better agreement with the simulation results for these systems. We have considered a hard sphere binary mixture to make a direct comparison of our results with the predictions of models studied in earlier works.
On the periodically excited plane turbulent mixing layer, emanating from a jagged partition

The flow in a turbulent mixing layer resulting from two parallel different velocity streams, that were brought together downstream of a jagged partition was investigated experimentally. The trailing edge of the partition had a short triangular ‘chevron’ shape that could also oscillate up and down at a prescribed frequency, because it was hinged to the stationary part of the partition to form a flap (fliperon). The results obtained from this excitation were compared to the traditional results obtained by oscillating a two-dimensional fliperon. Detailed measurements of the mean flow and the coherent structures, in the periodically excited and spatially developing mixing layer, and its random constituents were carried out using hot-wire anemometry and stereo particle image velocimetry. The prescribed spanwise wavelength of the chevron trailing edge generated coherent streamwise vortices while the periodic oscillation of this fliperon locked in-phase the large spanwise Kelvin–Helmholtz (K-H) rolls, therefore enabling the study of the inter- action between the two. The two-dimensional periodic excitation increases the strength of the spanwise rolls by increasing their size and their circulation, which depends on the input amplitude and frequency. The streamwise vortices generated by the jagged trailing edge distort and bend the primary K-H rolls. The present investigation endeavours to study the distortions of each mode as a consequence of their mutual interaction. Even the mean flow provides evidence for the local bulging of the large spanwise rolls because the integral width (the momentum thickness, θ), undulates along the span. The lateral location of the centre of the ensuing mixing layer (the location where the mean velocity is the arithmetic average of the two streams, y0), also suggests that these vortices are bent. Phase-locked and ensemble-averaged measurements provide more detailed information about the bending and bulging of the large eddies that ensue downstream of the oscillating chevron fliperon. The experiments were carried out at low speeds, but at sufficiently high Reynolds number to ensure naturally turbulent flow.
Neutral atomic carbon in dense molecular clouds

The 370 micron 3P2-3P1 fine-structure line of neutral carbon was detected in seven sources: OMC 1, NGC 2024, S140, W3, DR 21, M17, and W51. Simultaneous analysis of J = 2-1 data and available observations of the J = 1-0 line make it possible to deduce optical depths and excitation temperatures for these lines. These data indicate that both C I lines are likely to be optically thin, and that the ratio of C I to CO column densities in these clouds is typically about 0.1. 54 references.
Spatial Scalings for Randomly Initialized Heat and Burgers Equations with Quadratic Potentials

A general functional class of spatial scalings is introduced, jointly with the logarithmic transformation of the temporal component, to get the convergence to the Gaussian limit distribution of the solution to the heat and Burgers equations with quadratic external potentials, considering weakly dependent Gaussian random initial conditions. The results derived extend the ones obtained in Leonenko and Ruiz-Medina [31] to a more general spatial scaling setting.
A note on the leapfrogging between two coaxial vortex rings at low Reynolds numbers

In the early 1970s, Maxworthy [J. Fluid. Mech. 51, 15 (1972)] and Oshima et al. [J. Phys. Soc. Jpn. 38, 1159 (1975)] attempted to produce leapfrogging between two coaxial vortex rings at low Reynolds numbers in their laboratories. However, the rings failed to undergo the classical leapfrogging behavior and merged to form a single ring. In a recent numerical study, Shariff et al. (NASA Tech. Memo. 102257, 1989) attributed the failure partly to the effect of core distortion. They pointed out that vortex cores at low Reynolds numbers are thicker and therefore more susceptible to distortion during the leapfrogging. In this Brief Communication, it is shown through a systematic investigation that the initial generating condition also plays an important role in determining the success or failure of leapfrogging. The common belief that leapfrogging can be achieved simply by generating two vortex rings in quick succession may not be true for all flow conditions, especially when the Reynolds number is low. This finding may help to explain the results of Maxworthy and Oshima et al.
Efficient evaluation of macro‐basis‐function reaction terms in the subdomain multilevel approach

This paper presents an improved subdomain multilevel approach (SMA), a technique efficiently used for solving large complex‐shaped antennas printed in multilayered media structure. In a large electromagnetic problem, where the memory occupation and computational time have been already significantly reduced using the SMA, the calculation of the macro basis function (MBF) reaction terms remains the most time‐consuming part of the procedure. In this paper, we present an efficient way of computing MBF reaction terms and reducing them to equivalent moments. The numerical results are compared with brute‐force computations, the SMA, and the measurements. They demonstrate conclusively the efficiency and power of the new proposed technique. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 138–143, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20232
Duality for multiobjective variational problems with invexity

Wolfe and Mond-Weir type duals for multiobjective variational problems are formulated. Under invexity assumptions on the functions involved weak and converse duality theorems are proved to relate efficient solutions/properly efficient solutions of the primal and dual problems. A close relationship between these variational problems and nonlinear multiobjective programming problems is also indicated
Combining CPP-ACP with fluoride: a synergistic remineralization potential of artificially demineralized enamel or not?

Background and objective: Minimal intervention dentistry (MID) calls for early detection and remineralization of initial demineralization. Laser fluorescence is efficient in detecting changes in mineral tooth content. Recaldent is a product of casein phosphopeptide-amorphous calcium phosphate (CPP- ACP) which delivers calcium and phosphate ions to enamel. A new product which also contains fluoride is launched in United States. The remineralizing potential of CPP- ACP per se, or when combined with 0.22% Fl supplied in an oral care gel on artificially demineralised enamel using laser fluorescence was investigated. Methods: Fifteen sound human molars were selected. Mesial surfaces were tested using He-Cd laser beam at 441.5nm with 18mW power as excitation source on a suitable set-up based on Spex 750 M monochromator provided with PMT for detection of collected auto-fluorescence from sound enamel. Mesial surfaces were subjected to demineralization for ten days. The spectra from demineralized enamel were measured. Teeth were then divided according to the remineralizing regimen into three groups: group I recaldent per se, group II recaldent combined with fluoride gel and group III artificial saliva as a positive control. After following these protocols for three weeks, the spectra from remineralized enamel from the three groups were measured. The spectra of enamel auto-fluorescence were recorded and normalized to peak intensity at about 540 nm to compare between spectra from sound, demineralized and remineralized enamel surfaces. Results: A slight red shift was noticed in spectra from demineralized enamel, while a blue shift may occur in remineralized enamel. Group II showed the highest remineralizing potential. Conclusions: Combining fluoride with CPP-ACP had a synergistic effect on enamel remineralization. In addition, laser auto-fluorescence is an accurate technique for assessment of changes in tooth enamel minerals.
Conditional Optimal Design in Three- and Four-Level Experiments

The precision of estimates of treatment effects in multilevel experiments depends on the sample sizes chosen at each level. It is often desirable to choose sample sizes at each level to obtain the smallest variance for a fixed total cost, that is, to obtain optimal sample allocation. This article extends previous results on optimal allocation to four-level cluster randomized designs and randomized block designs. It also introduces the idea of constrained optimal allocation, where the sample size at one or more levels is fixed by considerations other than cost or sampling variation. Explicit formulas are given for constrained optimal allocation in three- and four-level designs.
Reflection grating photogrammetry: a technique for absolute shape measurement of specular free-form surfaces

While for non-reflecting surfaces a variety of optical techniques is available that allow the flexible geometric measurement of free-form surfaces, established approaches for the testing of specular surfaces are limited to basic geometries or slight deviations from an assumed reference geometry. As not only the intensified use of aspheric optics but also the increasing quality standards for technical surfaces call for an enhanced measurement range, the authors have developed two related techniques for the direct three-dimensional measurement of specular reflecting surfaces. These techniques are based on the observation of the mirror image of a grid-like reference structure and apply principles that are well-known from measurement systems for non-reflecting surfaces, such as photogrammetry and structured illumination, to the evaluation of specular surfaces. While the first of these approaches works with an active triangulation process based on one camera and a pseudo three-dimensional reference structure, the second one utilises a stereo-photogrammetric camera system in conjunction with a merely two-dimensional reference structure. Both systems allow the unambiguous measurement of reflecting free-form surfaces and may, by the use of multiple wavelength and photogrammetric stitching techniques, be extended to the measurement of rather complex geometries. Besides the fundamental mode of operation of this so-called reflection grating photogrammetry, the properties of a suitable reference structure will be presented in this contribution. Furthermore the photogrammetric calibration procedure and the used calibration models will be discussed. Finally the measurement uncertainty is evaluated based on both, experimental and theoretical considerations.
A survey of CCS, HC3N, HC5N, and NH3 toward dark cloud cores and their production chemistry

Survey observations of CCS (J N = 4 3 -3 2 , J N = 2 1 -1 0 ), HC 3 N (J = 5-4), HC 5 N (J = 9-8, J = 17-16), and NH 3 (J, K = 1, 1) were carried out toward 49 dark cloud cores to examine the existence of a systematic relation between the chemical evolution and the physical evolution of dark clouds. The J N = 3 3 -2 2 and J N = 3 4 -2 3 lines of CCS and the J = 4-3 line of C 3 S were also observed in several cores
THE CHEMICAL COMPOSITION OF ρ PUPPIS AND THE SIGNS OF ACCRETION IN THE ATMOSPHERES OF B–F-TYPE STARS

We investigated the chemical composition of ρ Pup using high-resolution spectral observations taken from the Very Large Telescope and the IUE archives and also spectra obtained at the 1.8 m telescope of the Bohyunsan observatory in Korea. The abundances of 56 chemical elements and the upper limits of Li and Be abundances were determined. The abundance pattern of ρ Pup was found to be similar to that of Am-type stars. The possibility of the influence of the accretion of interstellar gas and dust on the abundance patterns of B–F-type stars is discussed. The plots of the relative abundances of chemical elements in the atmospheres of ρ Pup and δ Sct versus the second ionization potentials of these elements show the correlations. The discontinuities at 13.6 and 24.6 eV—the ionization potentials of hydrogen and helium, respectively, are also exhibited in these plots. These discontinuities can be explained by interaction of the atoms of interstellar gas, mainly hydrogen and helium atoms, with the atoms of stellar photospheres (so-called charge-exchange reactions). Note that only the jumps near 13.6 and 24.6 eV were pointed out in previous investigations of relative abundances versus the second ionization potentials for Am-type stars. The dependencies of the relative abundances of chemical elements on the second ionization potentials of these elements were investigated using the published abundance patterns of B–F-type stars. The correlations of relative and absolute abundances of chemical elements, second ionization potentials, and projected rotational velocities are clearly detected for stars with effective temperatures between 7,000 and 12,000 K. If the correlation of relative abundances and second ionization potentials can be explained by the accretion of interstellar gas on the stellar surfaces, the investigation of these correlations can provide valuable information on the density and velocities of interstellar gas in different regions of the Galaxy and also on the influence of this phenomenon on stellar evolution. The dependencies of the relative abundances of chemical elements on the condensation temperatures of these elements were also found in the atmospheres of ρ Pup, δ Sct, and other B–F-type stars. Ten possible λ Boo-type stars were detected. The effective temperatures of these objects are between 10,900 and 14,000 K.
On the solution of multislab atmospheric radiation problems with an arbitrary number and type of stationary layers

We report here a computer implementation of a recently developed discrete ordinates methodology for efficiently solving a set of multislab atmospheric radiation problems with an arbitrary number and type of stationary layers. Numerical results are presented for a set of typical problems for a multislab model atmosphere in the shortwave. Copyright © 2006 Royal Meteorological Society
The optimal design of ripple-free filter based on three-mirror Gires-Tournois resonator

Optical bandpass filters with ripple-free spectral response are highly desirable for dense wavelength-division-multiplexed (DWDM) systems. We study and analyze the transmission characteristics of an optical bandpass filter, based on a three-mirror Gires-Tournois resonator (GTR) in a Michelson interferometer (MI). The three-mirror GTR (R1, R2, R3) is actually an all-pass filter with the reflectivity of the end mirror R3 being unity. In this paper, we present an analytical expression for the optimum design which has a ripple-free spectral response. The results show that flattop spectra can be obtained by suitably choosing the reflectivities R1, R2 of the two mirrors. Whereas a two-mirror GTR-based bandpass filter has only one unique optimum reflectivity, a three-mirror GTR-based filter has many sets of optimum values, making it easier to be designed to give much better performance. The effects of the reflective coefficients of the mirrors on the optical performance were also discussed.
Micro-sphere layered targets efficiency in laser driven proton acceleration

Proton acceleration from the interaction of high contrast, 25 fs laser pulses at >1019 W/cm2 intensity with plastic foils covered with a single layer of regularly packed micro-spheres has been investigated experimentally. The proton cut-off energy has been measured as a function of the micro-sphere size and laser incidence angle for different substrate thickness, and for both P and S polarization. The presence of micro-spheres with a size comparable to the laser wavelength allows to increase the proton cut-off energy for both polarizations at small angles of incidence (10∘). For large angles of incidence, however, proton energy enhancement with respect to flat targets is absent. Analysis of electron trajectories in particle-in-cell simulations highlights the role of the surface geometry in the heating of electrons.