Miracle-dz/UniFAR-FTUs huggingface dataset:
Is there another coincidence problem at the reionization epoch

The cosmological coincidences between the matter and radiation energy densities at recombination as well as between the densities of matter and the cosmological constant at present time are well known. We point out that moreover the third intersection between the energy densities of radiation and the cosmological constant coincides with the reionization epoch. To quantify the statistical relevance of this concurrence, we compute the Bayes factor between the concordance cosmology with free Thomson scattering optical depth and a model for which this parameter is inferred from imposing a match between the time of density equality and the epoch of reionization. This is to characterize the potential explanatory gain if one were to find a parameter-free physical connection. We find a very strong preference for such a concurrence on the Jeffreys scale from current cosmological observations. We furthermore discuss the effect of choice of priors, changes in reionization history, and free sum of neutrino masses. We also estimate the impact of adding intermediate polarization data from the Planck High Frequency Instrument and prospects for future 21 cm surveys. In the first case, preference for the correlation remains substantial, whereas future data may give results more decisive in pro or substantial in contra. Finally, we provide a discussion on different interpretations of these findings. In particular, we show how a connection between the star-formation history and the cosmological background dynamics can give rise to this concurrence.
Nebular Spectra of SN 1998bw Revisited: Detailed Study by One- and Two-dimensional Models

Refined one- and two-dimensional models for the nebular spectra of the hyperenergetic Type Ic supernova (SN) 1998bw, associated with the gamma-ray burst GRB 980425, from 125 to 376 days after B-band maximum are presented. One-dimensional, spherically symmetric spectrum synthesis calculations show that reproducing features in the observed spectra, i.e., the sharply peaked [O I] λ6300 doublet and Mg I] λ4570 emission and the broad [Fe II] blend around 5200 Å, requires the existence of a high-density O-rich core expanding at low velocities (≲8000 km s-1) and of Fe-rich material moving faster than the O-rich material. Synthetic spectra at late phases from aspherical (bipolar) explosion models are also computed with a two-dimensional spectrum synthesis code. The above features are naturally explained by the aspherical model if the explosion is viewed from a direction close to the axis of symmetry (~30°), since the aspherical model yields a high-density O-rich region confined along the equatorial axis. By examining a large parameter space (in energy and mass), our best model gives the following physical quantities: the kinetic energy E51 ≡ EK/1051 ergs ≳8-12 and the main-sequence mass of the progenitor star Mms ≳ 30-35 M☉. The temporal spectral evolution of SN 1998bw also indicates mixing among Fe-, O-, and C-rich regions, and highly clumpy structure.
A surgical navigation system for non-contact diffuse optical tomography and intraoperative cone-beam CT

A freehand, non-contact diffuse optical tomography (DOT) system has been developed for multimodal imaging with intraoperative cone-beam CT (CBCT) during minimally-invasive cancer surgery. The DOT system is configured for near-infrared fluorescence imaging with indocyanine green (ICG) using a collimated 780 nm laser diode and a nearinfrared CCD camera (PCO Pixelfly USB). Depending on the intended surgical application, the camera is coupled to either a rigid 10 mm diameter endoscope (Karl Storz) or a 25 mm focal length lens (Edmund Optics). A prototype flatpanel CBCT C-Arm (Siemens Healthcare) acquires low-dose 3D images with sub-mm spatial resolution. A 3D mesh is extracted from CBCT for finite-element DOT implementation in NIRFAST (Dartmouth College), with the capability for soft/hard imaging priors (e.g., segmented lymph nodes). A stereoscopic optical camera (NDI Polaris) provides real-time 6D localization of reflective spheres mounted to the laser and camera. Camera calibration combined with tracking data is used to estimate intrinsic (focal length, principal point, non-linear distortion) and extrinsic (translation, rotation) lens parameters. Source/detector boundary data is computed from the tracked laser/camera positions using radiometry models. Target registration errors (TRE) between real and projected boundary points are ~1-2 mm for typical acquisition geometries. Pre-clinical studies using tissue phantoms are presented to characterize 3D imaging performance. This translational research system is under investigation for clinical applications in head-and-neck surgery including oral cavity tumour resection, lymph node mapping, and free-flap perforator assessment.
Defect-induced one-phonon absorption in type Ia diamonds

The defect-induced one-phonon infrared absorption in type Ia diamonds may be synthesised by a six-component admixture. In addition to the well established A and B spectra and the recently reported D spectrum, three additional spectra components referred to as the G, H and I spectra are required. The spectral forms of all six components are given in the range 300-1332 cm-1. It is confirmed that the H3 and H4 vibronic bands produced by the annealing of electron-irradiated type Ia diamonds are associated respectively with A and B defects which have trapped a vacancy.
Singular Isothermal Disks. I. Linear Stability Analysis

As part of a larger effort to understand how binary and single stars form from the collapse of magnetized molecular cloud cores, we perform a global stability analysis of isopedically magnetized, singular isothermal disks (SIDs). The work described here has precedents in earlier studies of disturbances in power-law disks by Zang in 1976, Toomre in 1977, Lynden-Bell & Lemos in 1993, Syer & Tremaine in 1996, and Goodman & Evans in 1999. We find the analytic criteria for the bifurcation of axisymmetric disks into nonaxisymmetric forms with azimuthal periodicities m = 1 (eccentric displacements), 2 (oval distortions), 3 (triangular distortions), etc. These bifurcations, which occur at zero frequency, are the compressible and differentially rotating analogs of how the classical sequence of incompressible and uniformly rotating Maclaurin spheroids bifurcate (secularly, under dissipative forces) to become Dedekind ellipsoids with figure axes that remain fixed in space. Like Syer & Tremaine and Lynden-Bell & Lemos, we also find that zero-frequency logarithmic spirals are possible scale-free disturbances, but our interpretation of the existence of such steadily propagating wavetrains is different. We give a dynamical instability interpretation based on the onset of swing amplification by overreflection at the corotation circle of prograde spiral density waves the pattern speeds of which have nonzero and positive values. Our analysis yields identical instability criteria as the global normal-modes treatment of Goodman & Evans, and we tentatively also identify dynamical barred-spiral instabilities as the "breathing mode" limit of two-armed ordinary-spiral instabilities. We prove a general "reciprocity theorem," which states that the overreflection factors are identical for spiral density waves launched from cavities interior or exterior to Q-barriers that straddle the corotation circle. This globally valid result supports a unifying interpretation, advocated for many years by C. C. Lin and his colleagues (see, e.g., work by Bertin & Lin): the coexistence of spiral structure in galaxies arising from the instability of internal normal modes in the combined star/gas disk or from driving by external tidal influences associated with the chance passages of companion bodies.
All-pole phase-locked loops: calculating lock-in range by using Evan's root-locus

The dynamics of a phase-locked loop (PLL), an essential component for the electronic synchronization processes, is described by an ordinary nonlinear differential equation with an order equal to 1 plus the order of its internal linear low-pass filter. Literature contains several results mainly concerned to the second-order loops giving expressions for lock-in range and transient response specifying a linear equivalent second-order system. However, in some applications, more accurate transient responses are necessary and the PLL performance can be improved by considering the higher-order filters resulting in the nonlinear loops with order greater than 2. Such systems, due to high order and nonlinear terms, depending on the parameters combination can present some undesirable behaviors, resulting from bifurcations, as error oscillation and chaos, decreasing the synchronization ranges. Implication to engineering design is that some regions of the parameter space become forbidden limiting the circuit options. This work is a contribution on establishing the lock-in range for a PLL of generic order n + 1, considering that the filter is all-pole linear stable low-pass of order n. Analysis is performed by detecting a Hopf bifurcation on the synchronous state by using the root-locus method combined with the dynamical system theory. The lock-in range is calculated by applying the classical control tools defining an equivalent feedback control system.
PT-symmetric coherent perfect absorber with graphene

We investigate PT-symmetric coherent perfect absorbers (CPAs) in the TE mode solution of a linear homogeneous optical system surrounded by graphene sheets. It is revealed that the presence of graphene sheets plays a role to adjust the enhancement of absorption in a CPA. We derive exact analytic expressions and work through their possible impacts on lasing threshold and CPA conditions. We point out the roles of each parameter governing an optical system with graphene, and we show that optimal conditions of these parameters give rise to enhancement and possible experimental realization of a CPA laser. The presence of graphene leads the required gain amount to reduce considerably based on its chemical potential and temperature. We obtain that the relationship among system parameters decides the measure of CPA conditions. We find that graphene features that contribute to the resonance effect in graphene sheets are rather preferable to build a better CPA.
Crystal-field splittings in rare-earth-based hard magnets: An ab initio approach

We apply the first-principles density functional theory + dynamical mean-field theory framework to evaluate the crystal-field splitting on rare-earth sites in hard magnetic intermetallics. An atomic (Hubbard-I) approximation is employed for local correlations on the rare-earth $4f$ shell and self-consistency in the charge density is implemented. We reduce the density functional theory self-interaction contribution to the crystal-field splitting by properly averaging the $4f$ charge density before recalculating the one-electron Kohn-Sham potential. Our approach is shown to reproduce the experimental crystal-field splitting in the prototypical rare-earth hard magnet ${\mathrm{SmCo}}_{5}$. Applying it to $R{\mathrm{Fe}}_{12}$ and $R{\mathrm{Fe}}_{12}X$ hard magnets ($R=\mathrm{Nd}$, Sm and $X=\mathrm{N}$, Li), we obtain in particular a large positive value of the crystal-field parameter ${A}_{2}^{0}\ensuremath{\langle}{r}^{2}\ensuremath{\rangle}$ in ${\mathrm{NdFe}}_{12}\mathrm{N}$ resulting in a strong out-of-plane anisotropy observed experimentally. The sign of ${A}_{2}^{0}\ensuremath{\langle}{r}^{2}\ensuremath{\rangle}$ is predicted to be reversed by substituting N with Li, leading to a strong out-of-plane anisotropy in ${\mathrm{SmFe}}_{12}\mathrm{Li}$. We discuss the origin of this strong impact of N and Li interstitials on the crystal-field splitting on rare-earth sites.
NON-LINEAR VIBRATION OF A HINGED ORTHOTROPIC CIRCULAR PLATE WITH A CONCENTRIC RIGID MASS

Abstract Non-linear free vibration of hinged orthotropic circular plates with a concentric rigid mass at the centre is studied by using the finite element method. Hamilton's principle is applied to derive the basic non-linear partial differential equations and associated boundary conditions for the problem of large amplitude of an orthotropic circular plate. The applications of the finite element method to the dynamic problem rely on the use of a variation principle to derive the necessary element property's equations. The assembled equations for the plate are formed by summing each of the element equations obtained in consideration of a single element. Then, the boundary conditions are imposed on the vector of nodal field variables, so that the appropriate boundary conditions are satisfied. The assembled equations form an eigenvalue problem and are solved for the unknown field variables. The relations between the fundamental frequencies and the amplitudes of non-linear vibrations of the circular orthotropic elastic plate with a rigid core are obtained. The results show that the frequency responses of the plate varies with changes of boundary conditions and the ratio between tangential and radial elastic constant.
Error suppression for Hamiltonian quantum computing in Markovian environments

Hamiltonian quantum computing, such as the adiabatic and holonomic models, can be protected against decoherence using an encoding into stabilizer subspace codes for error detection and the addition of energy penalty terms. This method has been widely studied since it was first introduced by Jordan, Farhi, and Shor (JFS) in the context of adiabatic quantum computing. Here we extend the original result to general Markovian environments, not necessarily in Lindblad form. We show that the main conclusion of the original JFS study holds under these general circumstances: assuming a physically reasonable bath model, it is possible to suppress the initial decay out of the encoded ground state with an energy penalty strength that grows only logarithmically in the system size, at a fixed temperature.
Classical corrections to black hole entropy in $d$ dimensions: a rear window to quantum gravity?

We provide a simple derivation of the corrections for Schwarzschild and Schwarzschild-Tangherlini black hole entropy without knowing the details of quantum gravity. We will follow Bekenstein, Wheeler and Jaynes ideas, using summations techniques without calculus approximations, to directly find logarithmic corrections to well-known entropy formula for black holes. Our approach is free from pathological behaviour giving negative entropy for small values of black hole mass $M$. With the aid of Universality principle we will argue that this purely classical approach could open a window for exploring properties of quantum gravity.
Dynamical theory of x-ray diffraction

This chapter presents the dynamical theory of the diffraction of X-rays by perfect crystals. The most important part is devoted to the case of plane waves (Section 5.1.2). The solutions of the propagation equation of plane waves in crystals are given in Section 5.1. 3 using the concept of wavefields introduced by Ewald for X-rays in 1913 and by Bloch for electrons in 1928 (known in solid-state physics as Bloch waves). They are applied to the interpretation of the main properties of dynamical diffraction: anomalous transmission, standing waves and Pendellosung. The expressions for the diffracted intensity are given in both the transmission (Section 5.1.6) and the reflection (Section 5.1.7) cases. The last part (Section 5.1.8) concerns the diffraction of real and spherical waves, which is described in a qualitative way.
Micro-optics packaging and integration for high-power diode laser beam combining

High power diode laser beam combining using micro-optics components is emerging as a cost-effective technique for producing high power laser output from small-sized laser packages. Packaging of micro-optics lenses and lens arrays that are matched to lithographically fabricated diode laser waveguides provides a practical approach for combining multiple field distributions into a single high output power beam. Beam combining is often associated with additional output beam shaping that is tailored to a specific photonics application which the laser is intended for, such as surface treatment or micro-fabrication, photomedicine, laser pumping, or remote spectroscopy. It is shown that packaging imperfections and components' misalignments during the packaging phase influence the output laser beam spatial characteristics and produce specific beam distortions. Micro-optics design optimized for packaging and integration reduces the beam distortions caused by packaging imperfections, such as post-bonding shifts and lens-induced aberrations. Another role of optical design optimization and tolerance analysis is in providing a deterministic approach for distinguishing specific misalignment effects based on the observed distortions of the beam distributions. This, in turn, is used to develop appropriate compensation techniques that can be applied to improve the quality of the combined beam output during the fabrication process.
A new approach to optimization of viscoelastic beams: minimization of the input/output transfer function H ∞ -norm

A new approach to structural optimization in dynamic regime is presented that is based on the minimization of the H ∞ norm of the transfer function between the external loads and the structural response. The method is successfully applied to the sizing optimization of viscoelastic beams as shown by extensive numerical investigations that are presented in much detail. The abstract nature of the proposed approach makes it applicable to a wide class of dynamical systems including 2D and 3D systems within general topology optimization frameworks that are object of ongoing analysis.
Reduction in Power Consumption for Full-Color Active Matrix Organic Light-Emitting Devices

The active matrix organic light-emitting diode (AMOLED) is expected to serve as next generation flat panels display with the outstanding features of wide viewing angle, vivid images, and quick response. For practical use of full-color AMOLEDs in mobile devices, it is essential to reduce the power consumption, which is generally higher than that of liquid crystal displays (LCDs). For this aim, a red, green, blue, and white (RGBW) pixel format combined with an RGB color filter array (RGBW format) with a common white emission layer (EML) has been developed. We find that the RGBW format can successfully reduce the power consumption of a full-color AMOLED by nearly half that of a conventionally filtered RGB pixel format. This improved power consumption is almost equal to the power consumption of a same-sized LCD. The RGBW format is a promising technique for the further reduction of the power consumption of a full-color AMOLED.
Uniform discretizations: a quantization procedure for totally constrained systems including gravity

We present a new method for the quantization of totally constrained systems including general relativity. The method consists in constructing discretized theories that have a well defined and controlled continuum limit. The discrete theories are constraint-free and can be readily quantized. This provides a framework where one can introduce a relational notion of time and that nevertheless approximates in a well defined fashion the theory of interest. The method is equivalent to the group averaging procedure for many systems where the latter makes sense and provides a generalization otherwise. In the continuum limit it can be shown to contain, under certain assumptions, the "master constraint" of the "Phoenix project". It also provides a correspondence principle with the classical theory that does not require to consider the semiclassical limit.
A SCHEME FOR COMPUTING SOLUTIONS AND INTERFACE CURVES FOR A DOUBLY-DEGENERATE PARABOLIC EQUATION*

In this paper we present and analyze a finite difference scheme for computing approximate solutions and interface curves for the Cauchy problem for the doubly-degenerate parabolic equation $u_t = (u(1 - u)u_x )_x $. Our scheme requires only that linear, tridiagonal systems of equations be solved at each time step. We derive error bounds, not only for the approximate solutions, but also for the approximate interface curves, under the rather mild mesh condition ${{\Delta t} / {\Delta x \leqslant {\text{constant}}}}$.
H12CN and H13CN excitation analysis in the circumstellar outflow of R Sculptoris

The (CO)-C-12/(CO)-C-13 isotopologue ratio in the circumstellar envelope (CSE) of asymptotic giant branch (AGB) stars has been extensively used as the tracer of the photospheric C-12/C-13 ratio. However, spatially-resolved ALMA observations of R Scl, a carbon rich AGB star, have shown that the (CO)-C-12/(CO)-C-13 ratio is not consistent over the entire CSE. Hence, it can not necessarily be used as a tracer of the C-12/C-13 ratio. The most likely hypothesis to explain the observed discrepancy between the (CO)-C-12/(CO)-C-13 and C-12/C-13 ratios is CO isotopologue selective photodissociation by UV radiation. Unlike the CO isotopologue ratio, the HCN isotopologue ratio is not a ff ected by UV radiation. Therefore, HCN isotopologue ratios can be used as the tracer of the atomic C ratio in UV irradiated regions. Aims. We aim to present ALMA observations of (HCN)-C-13(4-3) and APEX observations of (HCN)-C-12(2-1), (HCN)-C-13(2-1, 3-2) towards R Scl. These new data, combined with previously published observations, are used to determine abundances, ratio, and the sizes of line-emitting regions of the aforementioned HCN isotopologues. Methods. We have performed a detailed non-LTE excitation analysis of circumstellar (HCN)-C-12(J = 1-0, 2-1, 3-2, 4-3) and (HCN)-C-13(J = 2-1, 3-2, 4-3) line emission around R Scl using a radiative transfer code based on the accelerated lambda iteration (ALI) method. The spatial extent of the molecular distribution for both isotopologues is constrained based on the spatially resolved (HCN)-C-13(4-3) ALMA observations. Results. We find fractional abundances of (HCN)-C-12/H2 = (5.0 +/- 2.0) x 10(-5) and (HCN)-C-13/H-2 = (1.9 +/- 0.4) x 10(-6) in the inner wind (r <= (2.0 +/- 0.25) x 10(15) cm) of R Scl. The derived circumstellar isotopologue ratio of (HCN)-C-12/(HCN)-C-13 = 26.3 +/- 11.9 is consistent with the photospheric ratio of C-12/C-13 similar to 19 +/- 6. Conclusions. We show that the circumstellar (HCN)-C-12/(HCN)-C-13 ratio traces the photospheric C-12/C-13 ratio. Hence, contrary to the (CO)-C-12/(CO)-C-13 ratio, the (HCN)-C-12/(HCN)-C-13 ratio is not a ff ected by UV radiation. These results support the previously proposed explanation that CO isotopologue selective-shielding is the main factor responsible for the observed discrepancy between (CO)-C-12/(CO)-C-13 and (CO)-C-12/(CO)-C-13 ratios in the inner CSE of R Scl. This indicates that UV radiation impacts on the CO isotopologue ratio. This study shows how important is to have high-resolution data on molecular line brightness distribution in order to perform a proper radiative transfer modelling.