Miracle-dz/UniFAR-FTUs huggingface dataset:
Multifrequency observations of Polar Mesosphere Summer Echoes using Alaskan radar facilities: Comparisons and scattering calculations

We present polar mesospheric radar observations at three frequency bands (MF/HF/VHF) and eight radar frequencies: 2.43, 3.3, 4.53, 4.9, 7.6, 28, 50, and 139 MHz, in order to better understand the well known but still not fully understood Polar Mesosphere Summer Echoes (PMSE). The echo morphology at the different frequencies is described by means of case studies where PMSE events were observed concurrently using at least two radar systems deployed over the Alaskan central region. The identity of MF and HF radar echoes as PMSE is resolved for the first time by means of simultaneous measurements made with VHF radars, the reference sensors employed traditionally for PMSE studies. On the basis of echo duration and radar reflectivity estimates, we suggest that low‐power HF radars would be more appropriate for PMSE monitoring. This is confirmed by a radar target analysis of turbulent scattering mechanisms in the polar summer mesosphere. MF radars show highly organized PMSE layers quite often but are more susceptible to ionospheric absorption and higher‐altitude returns associated with geomagnetic activity. Both phenomena produce a blanking effect in MF PMSE, which at times can persist for hours. HF and VHF radars are less affected by absorption events, but the PMSE echoes become weaker as the radar frequency increases.
PHYTOCHEMICAL SCREENING AND ANTIMICROBIAL ACTIVITIES OF CRUDE METHANOLIC EXTRACT OF PTELEOPSIS HABEENSIS (AUBREV EX KEAY) STEM BARK AGAINST DRUG RESISTANT BACTERIA AND FUNGI

- Herbal medicines have been in use since ancient times for many age related diseases for which no modern medicine or only palliative therapy is available. The screening of plants extracts has been of great interest to scientists for the discovery of new drugs effective in the treatment of several diseases. The leaves, fruits and stem barks of Pteleopsis habeensis were collected from Yankari Game Reserve Bauchi, Nigeria in June, 2012. The plant was authenticated at the Department of Biological sciences, Ahmadu Bello University,Zaria, Nigeria. Phytochemical screening of crude aqueous stem bark extract of Pteleopsis habeensis revealed the presence of steroid, triterpenes, cardiac glycoside, saponins, tannins, alkaloids and flavonoids. Crude extract exhibited antimicrobial activities against drug resistant Escherichia coli and Methicillin resistant Staphylococcus aureus using agar well diffusion and broth dilution methods. The MIC of the extract against the test organism was 3.125 and its MBC was 1.562mg/ml. However, the extract had no activity against drug resistant Candida albicans. This study has therefore showed that Pteleopsis habeensis aqueous stem bark extract has only antimicrobial activity and hence a potential source of a candidate drug for the treatment of infection(s) associated with drug resistant bacteria.
A Continuous Field Theory of Matter and Electromagnetism

A continuous field theory of matter and electromagnetism is developed. The starting point of the theory is the classical Maxwell equations which are directly tied to the Riemann-Christoffel curvature tensor. This is done through the derivatives of the Maxwell tensor which are equated to a vector field contracted with the curvature tensor. The electromagnetic portion of the theory is shown to be equivalent to the classical Maxwell equations with the addition of a hidden variable. Because the proposed equations describing electromagnetism and matter differ from the classical Maxwell-Einstein equations, their ability to describe classical physics is shown for several situations by direct calculation. The inclusion of antimatter and the possibility of particle-like solutions exhibiting both quantized charge and mass are discussed.
Averages of Continuous Functions on Countable Spaces

Introduction. Let X = j } be a countably infinite topological space; then the space C*(X) of all bounded real-valued continuous functions ƒ may be regarded as a space of sequences (ƒ(#1)i ƒ(#2), • • • ). I t is well known [7, p. 54] that no regular (Toeplitz) matrix can sum all bounded sequences. On the other hand, if (xi, #2, • • • ) converges in X (to xm), then every regular matrix sums all ƒ in C*(X) (to ƒ(**)). The main result of this paper is that if a regular matrix sums all ƒ in C*(X) then it sums ƒ to X/*nƒ(#»), ^ or s o m e absolutely convergent series J^an. We use this to show that no regular matrix can sum all of C*(X) if X is extremally disconnected (the closure of every open set is open). This extends a theorem of W. Rudin [ó], which has an equivalent hypothesis (X is embeddable in the Stone-Cech compactification fiN of a discrete space) and concludes that not all ƒ in C*(X) are Cesàro summable. For any continuous linear functional 4> on C*(X) one has a ("Riesz") representation <ƒ>(ƒ) =ffdfi, where /x is a Radon measure on jSX. Our main result is just that X supports /*; /x is forced to be atomic since X is countable. We show further that X has a subset T, the set of heavy points, such that the functionals we are concerned with correspond exactly to measures /x supported by T with JJL(T) = 1. Our knowledge of T is limited ; it will be summarized elsewhere.
Products of idempotents in certain semigroups of transformations

In an earlier paper (5) a description was given in set-theoretic terms of the semigroup generated by the idempotents of a full transformation semigroup , one of the results being that if X is finite then every element of that is not bijective is expressible as a product of idempotents. In view of this it was natural to ask whether by analogy every singular square matrix is expressibleas a product of idempotent matrices. This is indeed the case, as was shown by J. A. Erdos (2). Magill (6) has considered products of idempotents in thesemigroup of all continuous self-maps of a topological space X, but a comparable characterization of products of idempotents in this case appears to be extremelydifficult, and no solution is available yet.
Eigenvalues and eigenfunctions of metric measure manifolds

In this paper we study the eigenvalues and eigenfunctions of metric measure manifolds. We prove that any eigenfunction is C1, α at its critical points and C∞ elsewhere. Moreover, the eigenfunction corresponding to the first eigenvalue in the Dirichlet problem does not change sign. We also discuss the first eigenvalue, the Sobolev constants and their relationship with the isoperimetric constants. 2000 Mathematics Subject Classification: 47J05, 47J10, 53C60, 58E05, 58C40.
The Upper Semi-Lattice of Degrees of Recursive Unsolvability

The concept 'degree of recursive unsolvability' was introduced briefly in Post [16]. In his abstract [17] the concept was formulated precisely via an extension of [15], and a resulting partial scale of degrees of recursive unsolvability was applied to strengthen Theorem II of Kleene [8]. In the present paper our interest is in the abstract structure of the system of the degrees of recursive unsolvability. The concept 'degree of recursive unsolvability' is based on that of reducibility of decision problems. Three precise formulations of the latter concept have appeared, more or less completely, in the literature. In 'Turing reducibility' [19] ? 4, the concept of a Turing machine [18] is generalized to that of a Turing reducibility machine. A Turing reducibility machine 9) reduces the decision problem for a set S to that for a set T, if for each positive integer n, the machine 9M applied to n terminates in the correct answer to the question whether n is in S, via ordinary Turing machine acts and the hypothetically correct answering of such questions of the form "Is m in T? " as may arise in the process (finite in number). In 'general recursive reducibility', the representing function of S is general recursive in that of T in the sense of Kleene [8]. 1 In Post's 'canonical reducibility' [17], his canonical sets [15] are generalized to T-canonical sets by hypothetically adding primitive assertions expressing the membership or non-membership of 1, 2, 3, . in T. Then S is canonically reducible to T, if both S and its complement S with respect to the set of all positive integers are T-canonical sets. Although an infinite collection of hypothetical primitive assertions are added to an otherwise ordinary canonical system, in any derivation of an assertion in the T-canonical system but a finite number of them enter. Turing reducibility was proved equivalent to canonical reducibility by Post (unpublished), and canonical reducibility to general recursive reducibility by Martin Davis in his typed thesis [5]. A direct proof of the equivalence of Turing reducibility to general recursive reducibility was published (independently) by Kleene in his book [10] end ? 68, 69. Theoretically, no increase in generality is obtained by the use of Kleene's concept of a function general recursive in other functions (as may be seen from [10] pp. 307, 291); and by talking about just sets S and T a greater simplicity of concept results. Practically, when it comes to giving rigorous demonstrations under one or another of the equivalent concepts of reducibility, there are advantages in using
Design of acoustic devices with isotropic material via conformal transformation

The known realization of transformation acoustic devices requires exotic material parameters and has been hampered by limited available materials. By merging the conformal mapping and the embedded coordinate transformation method, we demonstrate that transformation-based acoustic devices can be made from isotropic materials, which greatly facilitates their implementation. The acoustic directional antenna based on such approach is presented and validated by full-wave simulations using the finite element method.
A generalized G‐function for the Quantum Rabi Model

The analytical solution of the quantum Rabi model is based on a transcendental function G(x) , the zeros of which determine the eigenenergies. G(x) is generalized here to a function G(x;z) , which allows a much better numerical control of the high‐energy part of the spectrum by an appropriate choice of the complex parameter z. Additionally, it is shown that all zeros of G(x) correspond to eigenvalues of the Hamiltonian as well as the zeros of G(x;z) for imaginary z.
STRUCTURAL DAMAGE DETECTION USING EMPIRICAL MODE DECOMPOSITION: EXPERIMENTAL INVESTIGATION

This paper presents an experimental investigation on the applicability of the empirical mode decomposition (EMD) for identifying structural damage caused by a sudden change of structural stiffness. A three-story shear building model was constructed and installed on a shaking table with two springs horizontally connected to the first floor of the building to provide additional structural stiffness. Structural damage was simulated by suddenly releasing two pretensioned springs either simultaneously or successively. Various damage severities were produced using springs of different stiffness. A series of free vibration, random vibration, and earthquake simulation tests were performed on the building with sudden stiffness changes. Dynamic responses including floor accelerations and displacements, column strains, and spring releasing time instants were measured. The EMD was then applied to measured time histories to identify damage time instant and damage location for various test cases. The comparison of identified results with measured ones showed that damage time instants could be accurately detected in terms of damage spikes extracted directly from the measurement data by EMD. The damage location could be determined by the spatial distribution of the spikes along the building. The influence of damage severity, sampling frequency, and measured quantities on the performance of EMD for damage detection was also discussed.
Bounds on the Spreading Radius in Droplet Impact: The Inviscid Case

We consider the classical problem of droplet impact and droplet spread on a smooth surface in the case of an ideal inviscid fluid. We revisit the rim-lamella model of Roisman et al. [\textit{Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences}, 458(2022), pp.1411-1430. ]. This model comprises a system of ordinary differential equations (ODEs); we present a rigorous theoretical analysis of these ODEs, and derive upper and lower bounds for the maximum spreading radius. Both bounds possess a $\mathrm{We}^{1/2}$ scaling behaviour, and by a sandwich result, the spreading radius itself also possesses this scaling. We demonstrate rigorously that the rim-lamella model is self-consistent: once a rim forms, its height will invariably exceed that of the lamella. We introduce a rational procedure to obtain initial conditions for the rim-lamella model. Our approach to solving the rim-lamella model gives predictions for the maximum droplet spread that are in close agreement with existing experimental studies and direct numerical simulations.
An Optimization Criterion for Linear Inverse Estimation

Integrated mean square error is proposed as an optimizing criterion for the linear inverse estimation problem. Results are compared with the classical and inverse procedures. A generalization allowing for several predictor variables is considered. Under certain conditions both the classical and the inverse methods may tend towards the optimal estimator. Also, the sample inverse estimator is shown to be optimal for a realistic situation
Electron diffraction and microscopy of nanotubes

Carbon nanotubes were discovered by electron microscopy in the carbon soot produced in an electric arc between graphite electrodes, as used in the production of fullerenes. Details of this microstructure have been studied mainly by the combined use of electron microscopic imaging and electron diffraction. Due to the small size of the tubes, diffraction patterns of single tubes, which are the most informative ones, can only be obtained by electron diffraction. For a complete interpretation of the observed diffraction effects a detailed theory is required. Successively more refined approximations of the theory allow us to understand the origin of the different features of the diffraction patterns. The most complete kinematical theory for the diffraction by single shell chiral straight tubes is obtained by the direct summation of the complex amplitudes of the waves scattered by the carbon atoms arranged on a helically wound graphene network. The closed form analytical expressions deduced in this way make it possible to compute the geometry and the intensity distribution of diffraction space. Diffraction patterns are computed as planar sections of this diffraction space. High-resolution electron microscopic images reveal the geometry of individual graphene sheets and their defects in multishell tubes. As well as the characteristic features of straight nanotubes those of helix shaped tubes are also discussed. It is shown how the combined use of electron diffraction and electron microscopy makes it possible to completely characterize the geometry of carbon nanotubes.
Stability analysis of genetic regulatory network with time delays and parameter uncertainties

The effect of parameter uncertainties on stability of delayed genetic regulatory networks is investigated. With the presence of parameter uncertainties, the delayed coupled genetic regulatory network is a parameter-dependent non-linear system, in which not only the dynamics are indefinite but also its equilibrium point is unknown. The authors first derive a sufficient condition to guarantee robust stability of uncertain genetic regulatory networks by introducing convergence region. Then, the estimation of convergence region bound is obtained by using Lyapunov stability theory and linear matrix inequality. It is worth noting that these results are derived in the case that the equilibrium point of parameter-dependent non-linear system is unknown. Finally, two examples are given to illustrate the effectiveness of the proposed results.
Determination of GPS receiver differential biases by neural network parameter estimation method

The dual‐frequency signals of GPS can be used to measure the total electron content (TEC). The differential instrumental biases inherent in GPS satellite and receivers are considered as the main sources of error, and they must be removed for an accurate estimation of TEC. We aim at developing an effective method to solve the difficulties involved in the TEC measurement; there are only a few usable ground receivers, especially in lower‐latitude areas near the geomagnetic equator where large ionospheric variability exists. For this purpose a new parameter estimation method based on a residual minimization training neural network is applied to determination of the GPS receiver biases. The alternative method is realized by making use of the excellent features of neural networks to approximate a wide range of mapping functions, for which the network training is carried out by minimizing squared residuals of integral equation. To determine receiver biases (unknown parameters), we used additional “neural networks,” each of which consists of only one neuron without an input channel. It is assumed that satellite biases have already been determined by applying the least squares method to the GEONET data gathered by a large number of receivers. Various cases of observation data for different seasons, different local times, and different geographic locations of the receiver as well as the cases of model data are analyzed, and it is confirmed that the method is very effective for a small number of receivers located in the lower‐latitude areas.
Resonant light scattering from metal nanoparticles: Practical analysis beyond Rayleigh approximation

We propose a simple analytical formula that can quantitatively predict resonant light scattering from metal nanoparticles of arbitrary shape, whose sizes are too large for Rayleigh approximation to be applicable. The formula has been derived as an empirical extension of Mie’s rigorous calculation for light scattering from spheres. It can very well reproduce the experimental characteristics of light scattering from Au nanorods.
The asymptotic behaviour of subcritical dissipative quasi-geostrophic equations

In this work, we give a complete description of the asymptotic behaviour of quasi-geostrophic equations in the subcritical range . We first show that its solutions simplify asymptotically as t → ∞. More precisely, solutions behave as a particular self-similar solution normalized by the mass as t → ∞ and when the initial data belong to . On the other hand, we show that solutions with initial data in decay towards zero as t → ∞ in this space. All results are obtained regardless of the size of the initial condition.
Error Estimates for Retrieval of Cloud-Top Pressure Using Absorption in the A Band of Oxygen

Abstract This paper examines the feasibility of remotely sensing cloud-top pressure from observations of reflected sunlight at frequencies in the A band of absorption of oxygen (13 070 cm−1, 765 nm). The data are assumed to consist of several channels within the A band and one reference channel outside the A band. The principal difficulty is that the reflected radiance is attenuated by absorption by O2 not only in the atmosphere above the cloud, but also along photon trajectories within the cloud. The extent of the extra absorption is unknown a priori because the microphysics structure of the cloud is unknown. This paper investigates the possibility of simultaneously retrieving both cloud-top pressure and parameters that determine the distribution of photon pathlength within the cloud. Estimates are derived for the errors in the retrieved parameters induced by instrumental noise and uncertainties in the profiles of temperature and aerosol extinction. The study investigates the sensitivity of the errors to.
Fabrication of p-channel heterostructure field effect transistors with polarization-induced two-dimensional hole gases at metal–polar GaN/AlInGaN interfaces

Novel nitride-based heterostructures have been fabricated demonstrating two-dimensional hole gases as the basis for p-channel transistors. The carrier density in the 2DHG is adjusted between very high values of 2 × 1013 cm−2 and low values of 6 × 1011 cm−2 by the polarization difference, ΔP, between quaternary AlInGaN backbarriers and a GaN channel on top. Record mobilities for holes in GaN of 43 cm2 V−1 s−1 (median 30 cm2 V−1 s−1) are observed for a moderate 2DHG density of 1.3 × 1012 cm−2 (median 2.2 × 1012 cm−2). Heterostructures with different backbarrier compositions are processed to field effect transistors and show a systematic threshold voltage shift from positive to negative values according to the corresponding 2DHG density. It is shown for the first time that by appropriate polarization-engineering through changing the AlInGaN composition, both depletion and enhancement mode behaviour can be achieved for p-channel devices. Drain current densities |Id| above 40 mA mm−1 at a drain source voltage Vds of −10 V are achieved for heterostructures with high polarization differences, ΔP, between AlInGaN backbarrier and GaN channel. Reducing ΔP leads to decreasing on-state drain currents |Id| with a simultaneous reduction in off-state current. This results in very large on/off ratios of up to 108 for enhancement mode devices, demonstrating record performances and great potential for future applications.
Black Box Classical Groups

Introduction Preliminaries Special linear groups: $\mathrm {PSL} (d,q)$ Orthogonal groups: $\mathrm{P}\Omega^\varepsilon(d,q)$ Symplectic groups: $\mathrm{PSp}(2m,q)$ Unitary groups: $\mathrm{PSU}(d,q)$ Proofs of Theorems 1.1 and 1.1, and of corollaries 1.2-1.4 Permutation group algorithms Concluding remarks References.
Shock gaseous cylinder interactions: Dynamically validated initial conditions provide excellent agreement between experiments and numerical simulations to late–intermediate time

We present numerical simulations of a planar shock interacting with a two-dimensional sulfur hexafluoride (SF6) cylinder. We have excellent agreement with experiments at two Mach numbers M=1.095 [Jacobs, Phys. Fluids A 5, 2239 (1993)] and M=1.2 [Zoldi, Ph.D. thesis, SUNY Stony Brook, 2002]. This includes intermediate scale features and quantities such as bounding box dimensions of coherent structures and velocity magnitude distribution function. Our simulations use a validated viscous FLASH [ASCI FLASH Center, “FLASH User’s Guide,” University of Chicago, 2002] environment initialized with a cylinder bounded by a finite-thickness interfacial transition layer of specific shape. The shape parameters are determined through iteration, beginning with the uncertain experimental images and optimizing to obtain maximal agreement with early to intermediate time evolving structures. The visiometric approach and the vortex paradigm [Hawley and Zabusky, Phys. Rev. Lett. 63, 1241 (1989)] are essential to obtain insight.
Korn inequality for a thin rod with rounded ends

We consider an elastic rod with rounded ends and diameter proportional to a small parameter h > 0. The roundness of the ends is described by an exponent m ∈ (0,1). We derive for the rod an asymptotically sharp Korn inequality with a special weighted anisotropic norm. Weight factors with m‐dependent powers of h appear both in the anisotropic norm and the Korn inequality itself, and we discover three critical values m = 1 ∕ 4, m = 1 ∕ 2 and m = 3 ∕ 4 at which these exponents are crucially changed. Copyright © 2014 John Wiley & Sons, Ltd.