Miracle-dz/UniFAR-FTUs huggingface dataset:
Van Hove singularities, chemical pressure and phonons: an angle-resolved photoemission study of KFe$_2$As$_2$ and CsFe$_2$As$_2$

We report an angle-resolved photoemission spectroscopy (ARPES) study of KFe$_2$As$_2$ and CsFe$_2$As$_2$, revealing the existence of a van Hove singularity affecting the electronic properties. As a result of chemical pressure, we find a stronger three-dimensionality in KFe$_2$As$_2$ than in CsFe$_2$As$_2$, notably for the 3$d_{z^2}$ states responsible for the small three-dimensional hole-like Fermi surface pocket reported by quantum oscillations. Supported by first-principles calculations, our ARPES study shows that the van Hove singularity previously reported in KFe$_2$As$_2$ moves closer to the Fermi level under negative chemical pressure. This observation, which suggests that the large density-of-states accompanying the van Hove singularity contributes to the large Sommerfeld coefficient reported for the AFe$_2$As$_2$ (A = K, Rb, Cs) series, is also consistent with the evolution of the inelastic scattering revealed by transport under external pressure, thus offering a possible interpretation for the origin of the apparent change in the superconducting order parameter under pressure. We find that the coherent spectral weight decreases exponentially upon increasing temperature with a characteristic temperature $T^*$. We speculate how the low-energy location of the van Hove singularity and the presence of a low-energy peak in the phonon density-of-states can relate to the high-temperature crossover observed in various electronic and thermodynamic quantities.
A modular version of the Erdõs-Szekeres theorem

Bialostocki, Dierker, and Voxman proved that for any n = p +2, there is an integer B(n; p) with the following property. Every set of B(n; p) points in general position in the plane has n points in convex position such that the number of points in the interior of their convex hull is 0 mod p. They conjectured that the same is true for all pairs n = 3, p =2. In this note, we show that every suﬃciently large point set determining no triangle with more than one point in its interior has n elements that form the vertex set of an empty convex n-gon. As a consequence, we show that the above conjecture is true for all n =5p=6+O(1).
Beyond subhalos: Probing the collective effect of the Universe’s small-scale structure with gravitational lensing

Gravitational lensing has emerged as a powerful probe of the matter distribution on subgalactic scales, which itself may contain important clues about the fundamental origins and properties of dark matter. Broadly speaking, two different approaches have been taken in the literature to map the small-scale structure of the Universe using strong lensing, with one focused on measuring the position and mass of a small number of discrete massive subhalos appearing close in projection to lensed images, and the other focused on detecting the collective effect of all the small-scale structure between the lensed source and the observer. In this paper, we follow the latter approach and perform a detailed study of the sensitivity of galaxy-scale gravitational lenses to the ensemble properties of small-scale structure. As in some previous studies, we adopt the language of the substructure power spectrum to characterize the statistical properties of the small-scale density field. We present a comprehensive theory that treats lenses with extended sources as well as those with time-dependent compact sources (such as quasars) in a unified framework for the first time. Our approach uses mode functions to provide both computational advantages and insights about couplings between the lens and source. The goal of this paper is to develop the theory and gain the intuition necessary to understand how the sensitivity to the substructure power spectrum depends on the source and lens properties, with the eventual aim of identifying the most promising targets for such studies.
Lecture notes on Diagrammatic Monte Carlo for the Fröhlich polaron

These notes are intended as a detailed discussion on how to implement the diagrammatic Monte Carlo method for a physical system which is technically simple and where it works extremely well, namely the Fröhlich polaron problem. Sampling schemes for the Green function as well as the self-energy in the bare and skeleton (bold) expansion are disclosed in full detail. We discuss the Monte Carlo updates, possible implementations in terms of common data structures, as well as techniques on how to perform the Fourier transforms for functions with discontinuities. Control over the variety of parameters, especially in the bold scheme, is demonstrated. Sample codes are made available online along with extensive documentation. Towards the end, we discuss various extensions of the method and their applications. After working through these notes, the reader will be well equipped to explore the richness of the diagrammatic Monte Carlo method for quantum many-body systems.
Direct control of the skyrmion phase stability by electric field in a magnetoelectric insulator

Magnetic skyrmions are topologically protected spin-whirl quasiparticles currently considered as promising components for ultra-dense memory devices. In the bulk they form lattices that are stable over just a few Kelvin below the ordering temperature. This narrow stability range presents a key challenge for applications, and finding ways to tune the SkL stability over a wider phase space is a pressing issue. Here we show experimentally that the skyrmion phase in the magnetoelectric insulator ${\text{Cu}_2 \text{O} \text{Se} \text{O}_3}$ can either expand or shrink substantially depending on the polarity of a moderate applied electric field. The data are well-described by an expanded mean-field model with fluctuations that show how the electric field provides a direct control of the free energy difference between the skyrmion and the surrounding conical phase. Our finding of the direct electric field control of the skyrmion phase stability offers enormous potential for skyrmionic applications based on a magnetoelectric coupling.
Optical Measurement of Wide Bandwidth Ultrasound Fields

A technique for measuring instantaneous three‐dimensional pressure in a wideband ultrasound pulse is presented. A collimated laser pulse impinges on the ultrasound field, and the optical intensity in a diffraction plane subsequent to this scattering event is imaged onto a CCD camera and stored. Timing is controlled precisely, allowing the acousto‐optic interaction to occur at the same point in the temporal evolution of the sound field each time the experiment is performed. After interaction with the ultrasound pulse, the optical phase is approximately proportional to the ray sum of instantaneous pressure in the pulse (taken in the direction of optical propagation). Optical phase immediately subsequent to passage through the ultrasound pulse is computed from recorded optical intensity via a phase retrieval algorithm. The experiment is performed at several angles as the ultrasound transducer is rotated about an axis normal to the optical axis of the imaging system. Tomographic reconstruction algorithms are .
Analysis of the transport process providing spin injection through an Fe/AlGaAs Schottky barrier

Electron-spin polarizations of 32% are obtained in a GaAs quantum well via electrical injection through a reverse-biased Fe/AlGaAs Schottky contact. An analysis of the transport data using the Rowell criteria demonstrates that single-step tunneling is the dominant transport mechanism. The current–voltage data show a clear zero-bias anomaly and phonon signatures corresponding to the GaAs-like and AlAs-like LO phonon modes of the AlGaAs barrier, providing further evidence for tunneling. These results provide experimental confirmation of several theoretical analyses, indicating that tunneling enables significant spin injection from a metal into a semiconductor.
Studies on high electronic energy deposition in transparent conducting indium tin oxide thin films

We have examined the effect of swift heavy ions using 100 MeV Au8+ ions on the electrical properties of transparent, conducting indium tin oxide polycrystalline films with resistivity of 0.58 × 10−4 Ω cm and optical transmission greater than 78% (pristine). We report on the modifications occurring after high electronic energy deposition. With the increase in fluency, x-ray line intensity of the peaks corresponding to the planes (1 1 0), (4 0 0), (4 4 1) increased, while (3 3 1) remained constant. Surface morphological studies showed a pomegranate structure of pristine samples, which was highly disturbed with a high dose of irradiation. For the high dose, there was a formation of small spherical domes uniformly distributed over the entire surface. The transmittance was seen to be decreasing with the increase in ion fluency. At higher doses, the resistivity and photoluminescence intensity was seen to be decreased. In addition, the carrier concentration was seen to be increased, which was in accordance with the decrease in resistivity. The observed modifications after high electronic energy deposition in these films may lead to fruitful device applications.
Existence and uniqueness for a degenerate parabolic equation with L1-data

In this paper we study existence and uniqueness of solutions for the boundary-value problem, with initial datum in L1(Ω), ut = div a(x, Du) in (0,∞)×Ω, − ∂u ∂ηa ∈ β(u) on (0,∞)× ∂Ω, u(x, 0) = u0(x) in Ω, where a is a Caratheodory function satisfying the classical Leray-Lions hypothesis, ∂/∂ηa is the Neumann boundary operator associated to a, Du the gradient of u and β is a maximal monotone graph in R× R with 0 ∈ β(0).
Reciclagem de ABS proveniente de resíduos de eletroeletrônicos modificados com TiO>sub<2>/sub<-OPM

The growing concern about plastic disposal and its impact on the environment has led to a necessity to reuse those materials, completing its life cycle within the circular economy mentality – production, use, recycling and reuse. The reintroduction of a recycled material back into the market requires some type of modifications, as the recycling process lightly alters the general properties of those materials. As a major constituent of the electronic waste, the plastic used in the electronic equipment industry demands special attention; it is mainly used as an enclosure for this class of equipment and such type of utilisation requires that the plastic abide to certain specifications, especially the ability to prevent an electrostatic discharge event. Thus, this imply that the polymer must undergo a modification in its electrical properties, as it is known that these materials are inherently unable to provide a path where the electrical charges could be dissipated. In such manner, the enhancement of the electrical conductivity is required to adapt the plastic enclosure, ensuring an antistatic characteristic and making it suitable for the desired applications. The production of composites, by inserting particles into a polymer matrix can lead to such modifications, based on the fact that the properties presented by the particles alone can be passed to the newly produced composite. So, by using particles that have good electrical properties it is possible to improve the composite’s own electrical conductivity, as desired. The improvement of properties can be achieved by inserting TiO2 particles (both commercial and OPM-modified) on an ABS polymer matrix. To use of this material on the electronical industry a way to modify its inherently insulating properties is studied, allowing the polymer to dissipate the electrostatic charges in a controlled and safe manner. This type of materials, called extrinsically conductive composites, are created mixing a polymeric matrix with an ideal concentration of particles that have adequate electric conductivity properties, creating a path that allow the electrical charges to flow through the material. The classification regarding the electrical properties of a material is divided in insulating, antistatic, dissipative and conductive. The understanding of the Electrical Percolation Threshold Theory helps to explain the electrical behaviour of a material and to control the quantity of particles to be inserted into the matrix in the making of a composite, modifying the polymer just enough so it can show the desired properties. Regarding this, this study is focused on the modification of the electrical properties of a composite so it may begin to exhibit dissipative properties.
Komparasi Performansi Antara Proportional Integral Derivative Controller (PID) Dan Fuzzy Logic Controller (FLC) Pada Penjejak Cahaya Dengan Tiga Sensor

The technology of light tracking monitors the solar panels to track the sun with full efficiency, and the solar panels can be upright to the sunlight in order to maximize the absorption of solar energy, so this system has a higher efficiency than non-tracking systems. This study aimed to obtain a controller that works accurately between the Proportional, Integral, and Derivative Controller (PID) and the Fuzzy Logic Controller (FLC) Algorithm by comparing the performance of the two algorithms in regulating the direction of the light tracker to detect the presence of sunlight. This solar prototype uses nine lamps as a simulation to determine the accuracy and precision of the angles of the two light trackers. The parameters compared in this test were the aspects of angular velocity and angle accuracy. The mean value of angular velocity obtained from the PID light tracking test results was 0.16 rad/s and the average linear velocity was 0.092 m/s whereas in the FLC light tracker, the average angular velocity value was 0.207 rad/s. Tests using a PID light tracker resulted in an X-axis accuracy of 45% and a Y-axis accuracy of 30%. The FLC light tracker, on the other hand, had an X-axis accuracy of 80% and a Y-axis accuracy of 30%. The precision value obtained by the PID light tracker on the X axis was 45% and the Y axis was 38%, while the precision value obtained by the FLC light tracker on the X axis was 71% and the Y axis was 33%. Based on the overall calculations, it can be concluded that the FLC light tracker has an increase in the speed value of 29% and an increase in the value of accuracy in the accuracy aspect by 35% and the precision aspect by 26% compared to the PID light tracker in previous studies.
EVALUASI USABILITY SISTEM BORDER CONTROL MANAGEMENT DENGAN METODE SYSTEM USABILITY SCALE DI TEMPAT PEMERIKSAAN KEIMIGRASIAN MOTAAIN

Sistem Border Control Management (BCM) merupakan sistem manajemen berbasis teknologi yang mengawasi wilayah perbatasan negara dan berfungsi menangani kegiatan pemeriksaan keimigrasian terhadap orang yang akan keluar maupun masuk Negara Republik Indonesia melalui Tempat Pemeriksaan Keimigrasian. Namun apabila sistem ini tidak berfungsi dengan optimal, maka akan mengganggu penyelenggaraan tugas keimigrasian. Oleh sebab itu, perlu adanya pengukuran usability terhadap Sistem BCM. Usability adalah suatu ukuran kualitas yang mampu menilai mudahnya suatu tampilan antarmuka sistem atau situs web yang dipakai pengguna dengan mempertimbangkan kriteria-kriteria tertentu. Salah satu jenis pengukuran usability adalah System Usability Scale (SUS) yang dilaksanakan dengan memakai serangkaian kuesioner. Penelitian ini bertujuan mengetahui hasil usability dari Sistem BCM dengan menggunakan metode SUS. Jenis data yang didapat dari penelitian ini adalah data primer yakni jawaban responden terhadap kuesioner yang diberikan. Dalam penentuan sampel, teknik yang digunakan adalah teknik sampling jenuh yaitu teknik penentuan sampel dengan semua anggota populasi digunakan sebagai sampel. Hasil dari penelitian ini menunjukan bahwa nilai usability dari Sistem BCM yang diperoleh menggunakan System Usability Scale adalah 76,67. Hal ini menunjukkan bahwa tingkat penerimaan penggunaan Sistem BCM termasuk kategori “Acceptable” yang berarti Sistem BCM dapat diterima oleh pengguna. Selanjutnya adjective rating usability dari Sistem BCM termasuk dalam kategori “Good” dan skala kegunaannya termasuk kategori “B”.
Magnetic Cannonball Model for Gamma-Ray Bursts

We propose a new magnetic-driven mechanism for gamma-ray bursts. The collapse of a magnetosphere onto a black hole can generate a strong outward Poynting flux that drives a baryon-free fireball called the magnetic cannonball. The relativistic outflow of the cannonball interacts with interstellar matter and forms a shock with the help of its magnetic field. The magnetic field of ≃104 G at the shock can induce synchrotron radiation with peaks observed at ≃102 keV. This magnetic field in the cannonball can also confine high-energy protons (γp > 30), which are required for delayed high-energy photons (>25 GeV), which were observed following a burst on 1994 February 17. Accretion-induced collapse of a white dwarf with a magnetic field of greater than 109 G, merger of a close binary, and failed Type Ib supernovae are possible creation scenarios, even without the rotation of the central object. This mechanism induces another burst event at the final phase of gravitational collapse even after a neutrino-driven fireball induces a burst event. In this scenario, the bursts consist of a primary neutrino-driven fireball and a secondary magnetic cannonball. This suggests that the magnetic cannonball works in some populations of gamma-ray bursts and in delayed or multiple burst events. The final remnant in the model should be a black hole. This implies that gamma-ray bursts cannot have an optical counterpart like a single star if they do not have a companion in a binary.
On the upper bound of classical correlations in a bipartite quantum system

For a bipartite quantum system consisting of subsystems A and B it was shown by Zhang et al (2012 Phys. Lett. A 376 3588–92) that the amount of classical correlations, which is used to define the quantum discord, is known to be bounded from above by the minimum of the von Neumann entropies of the subsystems A and B. We provide an alternative proof that is shorter and more transparent as it works without defining correlation matrices.
Study on the Mechanism of Electroacupuncture in the Treatment of Neuropathic Pain Based on Vesicular Glutamate Transporter 2/Toll Like Receptor 4 Signal Pathway

To explore the analgesic effect of electro-acupuncture on neuropathic pain model rats and to clarify the mechanism of electro-acupuncture analgesia from the perspective of vesicular glutamate transporter 2/ toll like receptor 4 signal pathway. A total of 30 specific pathogen free grade adult male Sprague-Dawley rats were selected. The rats were randomly divided into model group (chronic constriction injury), sham operation group, electro-acupuncture group, non-electro-acupuncture group (sham electro-acupuncture), Chicago sky blue 6B group and lipopolysaccharide group, with 5 rats in each group. The neuropathic pain model of chronic constriction injury of sciatic nerve was established. The “Huantiao” and “Yanglingquan” points were selected for electroacupuncture stimulation for 14 d. The mechanical foot contraction threshold, thermal pain, vesicular glutamate transporter 2/toll like receptor 4 signal pathway protein levels and inflammatory factor level of rats in each group were compared and analyzed. Compared with the sham operation group, the mechanical pain and thermal pain thresholds of the model group decreased significantly (p<0.01), the unilateral levels of vesicular glutamate transporter 2 and toll like receptor 4 and the release of interalukin-6 in the spinal cord increased significantly (p<0.01), while interalukin-10 decreased significantly (p<0.01); compared with the model group, electroacupuncture and intrathecal injection of Chicago sky blue 6B could significantly increase the pain threshold of neuropathic pain rats (p<0.01), reduce the release of interalukin-6 and the level of vesicular glutamate transporter 2 protein in the spinal cord and increase the level of interlukin-10; intrathecal injection of lipopolysaccharide decreased the pain threshold in rats (p<0.01). Electro-acupuncture can alleviate the pain sensitivity of neuropathic pain rats and its occurrence and development is closely related to the activation of vesicular glutamate transporter 2/toll like receptor 4 signal pathway in the spinal dorsal horn.
Entanglement entropy and Fisher information metric for closed bosonic strings in homogeneous plane wave background

We derive the extended renormalized entanglement entropy (EREE) and the Fisher information metric in the case of closed bosonic strings in homogeneous plane wave background. Our investigations are conducted within the framework of Thermo Field Dynamics (TFD). The formalism is also illustrated on the example of some particular models in condensed matter physics and the non-equilibrium case for system with dissipations.
Denjoy systems and dimension groups

Abstract We construct an adic model for the Denjoy system (X,T) of finite double orbit number. It is based on the dual Ostrowski numeration system. By using this construction, we can determine the K-theory of $C(X)\rtimes _T \mathbb {Z}$ associated with (X,T) in an effective way.
Comment on "Long Range Ordering in Magnetite below the Verwey Transition"

In a recent letter, J. P. Wright et al [Phys. Rev. Lett. 87,266401 (2001) and cond-mat/0111119] have investigated the crystal structure of magnetite below the Verwey transition temperature (TV) by means of X-ray and neutron powder diffraction. We show that the interpretation given by J. P. Wright et al. is unsupported by their own crystallographic data which demonstrate, instead, the lack of atomic long-range CO in magnetite below the Verwey transition.
Coherent radio pulses from showers in different media: A unified parametrization

We study the frequency and angular dependences of Cherenkov radio pulses originated by the excess of electrons in electromagnetic showers in different dense media that are being given consideration as targets for ultra high energy neutrino detection such as ice, salt and the lunar regolith. By means of a simple model of shower development we rederive the scaling of the electric field spectrum with the properties of the media such as density, radiation length, Moli\`ere radius, critical energy and refraction index. We compare the predictions of the scaling relations to the numerical results obtained in our own developed GEANT4-based Monte Carlo simulation, and address in a quantitative manner the predictive power of the scaling relations. We also give a unified parametrization of the frequency spectrum and angular distribution of the electric field in ice, salt, and the lunar regolith, in terms of the relevant properties of the media to be used in practical applications. We establish the applicability of our parametrizations. Our formulas are useful for estimates of the acceptance of current and future neutrino detectors using the radio technique, and for many other practical applications.