Miracle-dz/UniFAR-FTUs huggingface dataset:
The Thermodynamical Behaviors of Kerr—Newman AdS Black Holes

We reconsider the study of critical behaviors of Kerr—Newman Anti-de Sitter (AdS) black holes in four dimensions. The study is made in terms of the moduli space parameterized by the charge Q and the rotation parameter a, relating the mass M of the black hole and its angular momentum J via the relation a = J/M. Specifically, we discuss such thermodynamical behaviors in the presence of a positive cosmological constant considered as a thermodynamic pressure and its conjugate quantity as a thermodynamic volume. The equation of state for a charged Reissner—Nordstrom AdS black hole predicts a critical universal number depending on the (Q, a) moduli space. In the vanishing limit of the a parameter, this prediction recovers the usual universal number in four dimensions. Then, we find the bounded region of the moduli space allowing the consistency of the model with real thermodynamical variables.
Low-temperature magnetic characterization of optimum and etch-damaged in-plane magnetic tunnel junctions

We describe low-temperature characterization of magnetic tunnel junctions (MTJs) patterned by reactive ion etching for spin-transfer-torque magnetic random access memory. Magnetotransport measurements of typical MTJs show increasing tunneling magnetoresistance (TMR) and larger coercive fields as temperature is decreased down to 10 K. However, MTJs selected from the high-resistance population of an MTJ array exhibit stable intermediate magnetic states when measured at low temperature and show TMR roll-off below 100 K. These non-ideal low-temperature behaviors arise from edge damage during the etch process and can have negative impacts on thermal stability of the MTJs.
SU(N) meander determinants

We propose a generalization of meanders, i.e., configurations of non-self-intersecting loops crossing a line through a given number of points, to SU(N). This uses the reformulation of meanders as pairs of reduced elements of the Temperley–Lieb algebra, a SU(2)-related quotient of the Hecke algebra, with a natural generalization to SU(N). We also derive explicit formulas for SU(N) meander determinants, defined as the Gram determinants of the corresponding bases of the Hecke algebra.
q‐Euclidean space and quantum Wick rotation by twisting

The quantum matrix algebra R21x1x2=x2x1R is studied and proposed for the standard 2×2 case as the coordinates of q‐deformed Euclidean space. The algebra in this simplest case is isomorphic to the usual quantum matrices Mq(2) but in a form which is naturally covariant under the Euclidean rotations SUq(2)⊗SUq(2). A quantum Wick rotation is introduced that twists this system precisely into the approach to q‐Minkowski space based on braided matrices and their associated spinorial q‐Lorentz group.
Proton radiation effects in nitride lasers and light emitting diodes

Nitride laser diodes and light emitting diodes were irradiated with 200‐, 80‐ and 10‐MeV protons. The threshold current of violet laser diodes increased with increasing proton fluence to 1 × 1014 p/cm2. The increase in threshold current is considerably small compared with that of AlGaAs laser diodes. Proton energy dependence of the change of threshold current was a little bit different from that of GaN NIEL. Oscillation wavelength did not change before and after irradiation. The defect levels made by proton irradiation do not seem to be radiative recombination centers. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiscale Finite Element Methods for Advection-Dominated Problems in Perforated Domains

We consider an advection-diffusion equation that is advection-dominated and posed on a perforated domain. On the boundary of the perforations, we set either homogeneous Dirichlet or homogeneous Neumann conditions. The purpose of this work is to investigate the behavior of several variants of Multiscale Finite Element type methods, all of them based upon local functions satisfying weak continuity conditions in the Crouzeix-Raviart sense on the boundary of mesh elements. In the spirit of our previous works [Le Bris, Legoll and Lozinski, CAM 2013 and MMS 2014] introducing such multiscale basis functions, and of [Le Bris, Legoll and Madiot, M2AN 2017] assessing their interest for advection-diffusion problems, we present, study and compare various options in terms of choice of basis elements, adjunction of bubble functions and stabilized formulations.
Chromatic polynomials of planar triangulations, the Tutte upper bound and chromatic zeros

Tutte proved that if Gpt is a planar triangulation and P(Gpt, q) is its chromatic polynomial, then |P(Gpt, τ + 1)| ⩽ (τ − 1)n − 5, where and n is the number of vertices in Gpt. Here we study the ratio r(Gpt) = |P(Gpt, τ + 1)|/(τ − 1)n − 5 for a variety of planar triangulations. We construct infinite recursive families of planar triangulations Gpt, m depending on a parameter m linearly related to n and show that if P(Gpt, m, q) only involves a single power of a polynomial, then r(Gpt, m) approaches zero exponentially fast as n → ∞. We also construct infinite recursive families for which P(Gpt, m, q) is a sum of powers of certain functions and show that for these, r(Gpt, m) may approach a finite nonzero constant as n → ∞. The connection between the Tutte upper bound and the observed chromatic zero(s) near to τ + 1 is investigated. We report the first known graph for which the zero(s) closest to τ + 1 is not real, but instead is a complex-conjugate pair. Finally, we discuss connections with the nonzero ground-state entropy of the Potts antiferromagnet on these families of graphs.
Coronal Radio Bursts: A Signature of Nanoflares?

Coronal heating may be a result of frequent microscopic energy releases, which Parker has termed “nanoflares. ” Since solar radio type I bursts, which are frequently observed at meter wavelengths, involve extremely small amount of energy, we have determined the frequency distribution of the peak flux density of these bursts. The study has been performed on 11 noise storm events observed by the Nançay Radioheliograph at 164, 237, and 327 MHz. At each frequency, and for the 11 noise storms, the peak flux density distribution of type I bursts can be well represented by a power law. The index α of the distribution, ~3, is nearly independent of the observing frequency and does not vary much from one noise storm to the other, i.e., from one active region to the other. This index is significantly steeper than that measured for various other flare phenomena (<2). There are noise storm theories and various spectral and imaging radio observations that suggest that type I bursts may be a nonthermal signature of energy release fragments. If this is the case, such a steep power-law distribution is consistent with the prediction of “avalanche” models developed for small energy release events reminiscent of nanoflares, as well as the idea that small energy release events may contribute to the heating of an active coronal region.
The context behind the context: A Pacific leadership research tok stori

This article takes a relational approach to Pacific leadership by presenting three layers of discussion. First, we provide findings from our research team members about the relationships between the Pacific community and school leaders’ understandings of leadership. We include accounts of how leaders negotiate in context between forms of leadership from different domains. Second, we reflexively probe ideas of relationality, distance and closeness in leadership research by considering researchers’ experiences of the research process. Third, we show how Indigenous oracies such as tok stori can provide space and opportunity to rethink leadership as the ethical negotiation of positionality tensions. The overall findings centre relationships as a key concern of leadership practice and research, and discussion of Pacific-origin ideas of leadership, activities where the relational context behind the context is ignored at one’s peril. ancestors, the land and the people we have come from . as well as linking to the future, our children.
Static and low-frequency magnetic field effects: health risks and therapies

Many biological processes are affected by electromagnetic fields. Hence incremental internal fields generated by external magnetic fields can be expected to affect that biology. With some exceptions, most of the present interest in the effects of exogenous static and low-frequency magnetic fields centres on three intensity regions. (1) There are concerns that 50-60 Hz power distribution fields as small as 0.2 µT, may affect the health of populations. (2) ac fields that are larger than 1 mT (and usually smaller than 100 mT) with frequencies of a few kHz or less may have therapeutic value with respect to the healing of bone fractures and soft-tissue injuries. (3) The very large slowly varying fields of the order of 2 T used in magnetic resonance imaging might affect the physiology of the patients. Magnetic fields interact with biological systems through forces on the electrical currents associated with physiological functions and through the torques exerted on the magnetic moments of biologically important molecules and the electrons that play a role in the binding of geminate radicals. The torques that the Earth's magnetic field applies to the ferrimagnetic domains of biologically formed magnetite affects the biology of species in several different phyla and may have consequences in humans. Low-frequency magnetic fields also induce electric fields through the Faraday effect that may have biological consequences. For either the direct magnetic fields or the magnetically induced electric fields to affect the biology of living systems, the interactions with such systems must generally be larger then the interactions with endogenous physiological and thermal noise. This constraint seems to exclude the possibility that the environmental fields less than 1 µT from the electric power distribution system affect health and places important constraints on the minimal fields that can be expected to have therapeutic value.
Evolution of maximal coherence and nonlinear mixing in an ionizing three-level medium

We have carried out a numerical investigation of the influence of photoionization, causing neutral atom depletion and accompanying electron impact dephasing, on a stimulated Raman adiabatic passage (STIRAP) scheme in a dense medium of three-level atoms. The nonlinear mixing from the large (maximal) coherence generated during the population transfer is calculated within the framework of a time-dependent model for a single atom with simplified propagation appropriate to a thin slab of material. For definiteness and consistency of the atomic parameters employed we have treated a scheme in atomic calcium. For generation of intense vacuum ultraviolet fields, laser intensities in the range from 100 ${\mathrm{k}\mathrm{W}/\mathrm{c}\mathrm{m}}^{2}$ to 1 ${\mathrm{M}\mathrm{W}/\mathrm{c}\mathrm{m}}^{2}$ are required, and these are found to cause significant ionization of the atom. We find that at atomic densities $g{10}^{16}/{\mathrm{cm}}^{3}$ the effects of electron impact dephasing on the coherence evolution is very significant and will dominate over other dephasing mechanisms. In contrast at lower densities $\ensuremath{\sim}{10}^{14}/{\mathrm{cm}}^{3}$ (compatible with a sealed vapor cell) the conversion efficiency is relatively unaffected by electron impact dephasing. We conclude that in general photoionization depletion and electron impact dephasing will be significant in maximal coherence wave mixing and STIRAP population transfer schemes operated at high density.
The spectroscopic characteristics of intermediate‐aged pre‐main‐sequence stars: the η Chamaeleontis cluster

We present a study of calibrated low-resolution spectra of the 18 known primaries of the 9-Myr-old η Chamaeleontis (η Cha) pre-main-sequence (PMS) star cluster. Using synthetic broad-band colours and narrow-band continuum-sensitive, temperature-sensitive and gravity-sensitive indices derived from the spectra, we compare the η Cha stars to standard dwarfs. We find that the VRI colours of the PMS stars are indistinguishable from those of main-sequence stars, but that a B-band excess attaining 0.2 mag for late-M cluster stars is present, which might be an indicator of gravity, metallicity and/or activity differences between the two samples of stars. The narrow-band spectral indices for the η Cha stars possibly indicate higher metallicity and strongly indicate lower surface gravity than the dwarf indices, consistent with the elevated location of the cluster in the Hertzsprung-Russell evolutionary diagram. Using the derived synthetic colours and indices, we adopt spectral types for the late-type η Cha stars. We then produce a table of absolute optical magnitudes and colours representing the cluster isochrone for comparison with PMS evolutionary models. From our results we also conclude that the η Cha stars are unreddened, consistent with the group being a sample of older PMS stars distant from obscuring molecular clouds, except for the A1 member HD 75505 for which we confirm A v = 0.4 mag likely due to the presence of circumstellar material.
Mermin pentagrams arising from Veldkamp lines for three qubits

We study the geometry of the space of Mermin pentagrams, objects that are used to rule out the existence of noncontextual hidden variable theories as alternatives to quantum theory. It is shown that this space of 12 096 possible pentagrams is organized into 1008 families, with each family containing a ‘double-six’ of pentagrams. The 1008 families are connected to a special set of Veldkamp lines in the Veldkamp space for three-qubits an object well-known to finite geometers but has only been introduced to physics recently. Due to the transitive action of the symplectic group on this set of Veldkamp lines it is enough to study only one ‘canonical’ double-six configuration of pentagrams. We prove that the geometry of this double-six configuration is encapsulated in the weight diagram of the 20 dimensional irreducible representation of the group SU(6). As an interesting by-product of our approach we show that Mermin pentagrams and a class of Mermin squares labelled by three-qubit Pauli operators are inherently related. We conjecture that by studying the representation theoretic content of other Veldkamp lines of the Veldkamp space for N-qubits makes it possible to find new contextual configurations in a systematic manner.
Ideal convergent subsequences and rearrangements for divergent sequences of functions

Abstract Let 𝓙 be an ideal on ℕ which is analytic or coanalytic. Assume that (fn) is a sequence of functions with the Baire property from a Polish space X into a Polish space Z, which is divergent on a comeager set. We investigate the Baire category of 𝓙-convergent subsequences and rearrangements of (fn). Our result generalizes a theorem of Kallman. A similar theorem for subsequences is obtained if (X,μ) is a σ-finite complete measure space and a sequence (fn) of measurable functions from X to Z is 𝓙-divergent μ-almost everywhere. Then the set of subsequences of (fn), 𝓙-divergent μ-almost everywhere, is of full product measure on {0,1}ℕ. Here we assume additionally that 𝓙 has property (G).
A DISPERSION MINIMIZED MIMETIC METHOD FOR A COLD PLASMA MODEL

In this paper we consider the lowest edge-based mimetic finite difference (MFD) discretization in space for Maxwell's equations in cold plasma on rectangular meshes. The method uses a generalized form of mass lumping that, on one hand, eliminates a need for linear solves at every iteration while, on the other hand, retains a set of free parameters of the MFD discretization. We perform an optimization procedure, called m-adaptation, that identified a set of free parameters that lead to the smallest numerical dispersion. The choice of the time stepping proved to be critical for successful optimization. Using exponential time differencing we were able to reduce the numerical dispersion error from second to fourth order of accuracy in mesh size. It was not possible to achieve this order of magnitude reduction in numerical dispersion error using the standard leapfrog time stepping. Numerical simulations independently verify our theoretical findings.
On searches for pulsed emission with application to four globular cluster X-ray sources - NGC 1851, 6441, 6624, and 6712

We present the results of searches for periodic pulsations in the X-ray emission from four globular cluster sources, NGC 1851, NGC 6441, NGC 6624, and NGC 6712. The data were obtained by the Monitor Proportional Counter aboard HEAO 2 (Einstein Observatory). The methods of analysis are presented in some detail because we have correctly accounted for several effects which have been routinely overlooked by others. The periods searched cover the range from approx.1 ms to approx.500 s. No pulsed emission was detected, and the (90% confidence) upper limits for the pulsed fraction are presented.
Evidence for the direct impact excitation of Mn centers in electroluminescent ZnS:Mn films

In order to clarify the excitation mechanism of Mn luminescent centers in ZnS:Mn electroluminescent thin films, time‐resolved emission spectra in photoluminescence and electroluminescence were measured. In photoluminescence, both emissions arising from ZnS host and Mn centers were observed. For the emission arising from Mn centers, the time delay showing energy transfer from ZnS host to Mn centers was recognized. In electroluminescence, contrary to this, the emission from the ZnS host was hardly observed, and the emission from Mn centers was observed immediately after excitation. These experimental results strongly suggest that the excitation mechanism of Mn centers in electroluminescence is due to the direct impact excitation of Mn centers by hot electrons accelerated in the high electric field in the Zns host. These results are also supported by efficiency measurements.
A globally convergent and locally quadratically convergent modified B-semismooth Newton method for $\ell_1$-penalized minimization

We consider the efficient minimization of a nonlinear, strictly convex functional with $\ell_1$-penalty term. Such minimization problems appear in a wide range of applications like Tikhonov regularization of (non)linear inverse problems with sparsity constraints. In (2015 Inverse Problems (31) 025005), a globalized Bouligand-semismooth Newton method was presented for $\ell_1$-Tikhonov regularization of linear inverse problems. Nevertheless, a technical assumption on the accumulation point of the sequence of iterates was necessary to prove global convergence. Here, we generalize this method to general nonlinear problems and present a modified semismooth Newton method for which global convergence is proven without any additional requirements. Moreover, under a technical assumption, full Newton steps are eventually accepted and locally quadratic convergence is achieved. Numerical examples from image deblurring and robust regression demonstrate the performance of the method.
A relativistic version of a two-level atom in the rest-frame instant form of dynamics

We define a relativistic version of a two-level atom, in which an extended atom is replaced by a point particle carrying suitable Grassmann variables for the description of the two-level structure and that of the electric dipole. After studying the isolated system ‘atom plus the electro-magnetic field’ in the electric-dipole representation as a parameterized Minkowski theory, we give its restriction to the inertial rest frame and the explicit form of the Poincaré generators. After quantization, we get a two-level atom with a spin-1/2 electric dipole and the relativistic generalization of the Hamiltonians of the Rabi and Jaynes–Cummings models.
Dedekind completions, neat embeddings and omitting types

Let n be finite >2. We show that any class between S\Nr_n\CA_{n+3} and RCA_n is not atom canonical, and any class containing the class of completely representable algebras and contained in S_c\Nr_n\CA_{n+3} is not elementary. We show that there is no finite variable universal axiomatization of many diagonal free reducts of representable cylindric algebras of dimension n, like the varieties of representable diagonal-free cylindric algebras and Halmos' polyadic algebras (without equality). We apply our hitherto obtained algebraic results to show that the omitting types theorem fails for finite variable fragments of first order logic with and without equality, having n variables, even if we count in severely relativized models as candidates for omitting single non-principle types. Finally, we show that for many cylindric-like algebras, like diagonal free cylindric algebras and Halmos' polyadic algebras with and without equality the class of strongly representable atom structures of finite dimension >2 is not elementary.
Solvable normal subgroups of 2-knot groups

If $X$ is an orientable, strongly minimal $PD_4$-complex and $\pi_1(X)$ has one end then it has no nontrivial locally-finite normal subgroup. Hence if $\pi$ is a 2-knot group then (a) if $\pi$ is virtually solvable then either $\pi$ has two ends or $\pi\cong\Phi$, with presentation $\langle{a,t}|ta=a^2t\rangle$, or $\pi$ is torsion-free and polycyclic of Hirsch length 4; (b) either $\pi$ has two ends, or $\pi$ has one end and the centre $\zeta\pi$ is torsion-free, or $\pi$ has infinitely many ends and $\zeta\pi$ is finite; and (c) the Hirsch-Plotkin radical $\sqrt\pi$ is nilpotent.
A conditional limit theorem for high-dimensional $\ell^{p}$ spheres

The study of high-dimensional distributions is of interest in probability theory, statistics and asymptotic convex geometry, where the object of interest is the uniform distribution on a convex set in high dimensions. The $\ell^p$ spaces and norms are of particular interest in this setting. In this paper, we establish a limit theorem for distributions on $\ell^p$ spheres, conditioned on a rare event, in a high-dimensional geometric setting. As part of our proof, we establish a certain large deviation principle that is also relevant to the study of the tail behavior of random projections of $\ell^p$ balls in a high-dimensional Euclidean space.
On the integrable magnetic geodesic flow on a 2-torus

In this paper the magnetic geodesic flow on a 2-torus is considered. We study a semi-hamiltonian quasi-linear PDEs which is equivalent to the existence of polynomial in momenta first integral of magnetic geodesic flow on fixed energy level. It is known that diagonal metric associated with this system is Egorov one if degree of the first integral is equal to 2 or 3. In this paper we prove this fact in the case of existence of the first integral of any degree.
Limiting spectral distribution for non-Hermitian random matrices with a variance profile

For each $n$, let $A_n=(\sigma_{ij})$ be an $n\times n$ deterministic matrix and let $X_n=(X_{ij})$ be an $n\times n$ random matrix with i.i. d. centered entries of unit variance. We are interested in the asymptotic behavior of the empirical spectral distribution $\mu_n^Y$ of the rescaled entry-wise product \[ Y_n = \left(\frac1{\sqrt{n}} \sigma_{ij}X_{ij}\right). \] For our main result, we provide a deterministic sequence of probability measures $\mu_n$, each described by a family of Master Equations, such that the difference $\mu^Y_n - \mu_n$ converges weakly in probability to the zero measure. A key feature of our results is to allow some of the entries $\sigma_{ij}$ to vanish, provided that the standard deviation profiles $A_n$ satisfy a certain quantitative irreducibility property. Examples are also provided where $\mu_n^Y$ converges to a genuine limit. As an application, we extend the circular law to a class of random matrices whose variance profile is doubly stochastic.