Miracle-dz/UniFAR-FTUs huggingface dataset:
A temperature-mapping system for multi-cell SRF accelerating cavities

A Temperature mapping (T-map) system for Superconducting Radio Frequency (SRF) cavities consists of a thermometer array positioned precisely on an exterior cavity wall, capable of detecting small increases in temperature; therefore it is a powerful tool for research on the quality factor ( Q 0 ) of SRF cavities. A new multi-cell T-mapping system is has been developed at Cornell University. The system has nearly two thousand thermometers to cover 7-cell SRF cavities for Cornell’s ERL project. A new multiplexing scheme was adopted to reduce number of wires. A 1mK resolution of the temperature increase Δ(cid:1846) is achieved. A 9-cell cavity of TESLA geometry was tested with the T-map system. By converting Δ(cid:1846) to power loss and quality factor, it has been found that for this cavity, most surface losses were generated by the first cell when the accelerating gradient is increased above 15MV/m. The comparison of Q-value between with and without hotspots shows the heating on cavity wall degraded cavity Q 0 about 1.65 times. The power loss on the hotspots is about 40% of the total power. Effective and intuitive ways of displaying surface properties of the cavity interior, e.g. the residual resistivity, will be shown.
Identification of New Taxa of Portulaca oleracea L. Aggregate From Poland Based on Seed Coat Micromorphological Characteristics

This paper presents the results of micromorphological studies of Portulaca oleracea aggregate seeds deposited at the Herbarium of the Department of Systematic and Environmental Botany (POZ), Adam Mickiewicz University in Poznań, Poland, based on scanning electron microscopy. The seed surface ultrastructure was studied and the following seven morphotypes (species) were noted: P. daninii , P. granulatostellulata , P. macrantha , P. nitida , P. oleracea s. str. , P. papillatostellulata , and P. trituberculata . New alien taxa for the flora of Poland, P. daninii , P. macrantha , and P. papillatostellulata , were recorded. The original photos of the seed surface ultrastructure of the studied morphotypes are included.
Horizon energy as the boost boundary term in general relativity and loop gravity

We show that the near-horizon energy introduced by Frodden, Ghosh and Perez arises from the action for general relativity as a horizon boundary term. Spin foam variables are used in the analysis. The result provides a derivation of the horizon boost Hamiltonian introduced by one of us to define the dynamics of the horizon degrees of freedom, and shows that loop gravity provides a realization of the horizon Schrodinger equation proposed by Carlip and Teitelboim.
ESTIMATING THE ARRIVAL TIME OF EARTH-DIRECTED CORONAL MASS EJECTIONS AT IN SITU SPACECRAFT USING COR AND HI OBSERVATIONS FROM STEREO

Predicting the arrival time and transit speed of coronal mass ejections (CMEs) near the Earth is critical to understanding the solar-terrestrial relationship. Even though STEREO observations now provide multiple views of CMEs in the heliosphere, the true speeds derived from stereoscopic reconstruction of SECCHI coronagraph data are not quite sufficient for accurate forecasting of the arrival time at Earth of a majority of CMEs. This uncertainty is due to many factors that change CME kinematics, such as the interaction of two or more CMEs or the interaction of CMEs with the pervading solar wind. In order to understand the propagation of CMEs, we have used the three-dimensional triangulation method on SECCHI coronagraph (COR2) images and geometric triangulation on the J-maps constructed from Heliospheric Imagers HI1 and HI2 data for eight Earth-directed CMEs observed during 2008–2010. Based on the reconstruction, and implementing the drag-based model for the distance where the CMEs could not be tracked unambiguously in the interplanetary (IP) medium, the arrival time of these CMEs have been estimated. These arrival times have also been compared with the actual arrival times as observed by in situ instruments. The analysis reveals the importance of heliospheric imaging for improved forecasting of the arrival time and direction of propagation of CMEs in the IP medium.
A new method to estimate annual solar wind parameters and contributions of different solar wind structures to geomagnetic activity

In this paper, we study two sets of local geomagnetic indices from 26 stations using the principal component and the independent component (IC) analysis methods. We demonstrate that the annually averaged indices can be accurately represented as linear combinations of two first components with weights systematically depending on latitude. We show that the annual contributions of coronal mass ejections (CMEs) and high‐speed streams (HSSs) to geomagnetic activity are highly correlated with the first and second IC. The first and second ICs are also found to be very highly correlated with the strength of the interplanetary magnetic field (IMF) and the solar wind speed, respectively, because solar wind speed is the most important parameter driving geomagnetic activity during HSSs while IMF strength dominates during CMEs. These results help in better understanding the long‐term driving of geomagnetic activity and in gaining information about the long‐term evolution of solar wind parameters and the different solar wind structures.
High-resolution simulations of the head-on collision of white dwarfs

The direct impact of white dwarfs has been suggested as a plausible channel for type Ia supernovae. In spite of their (a priori) rareness, in highly populated globular clusters and in galactic centers, where the amount of white dwarfs is considerable, the rate of violent collisions between two of them might be non-negligible. Even more, there are indications that binary white dwarf systems orbited by a third stellar-mass body have an important chance to induce a clean head-on collision. Therefore, this scenario represents a source of contamination for the supernova light-curves sample that it is used as standard candles in cosmology, and it deserves further investigation. Some groups have conducted numerical simulations of this scenario, but their results show several differences. In this paper we address some of the possible sources of these differences, presenting the results of high resolution hydrodynamical simulations jointly with a detailed nuclear post-processing of the nuclear abundances, to check the viability of white dwarf collisions to produce significant amounts of 56Ni. To that purpose, we use a 2D-axial symmetric smoothed particle hydrodynamic code to obtain a resolution considerably higher than in previous studies. In this work, we also study how the initial mass and nuclear composition affect the results. The gravitational wave emission is also calculated, as this is a unique signature of this kind of events. All calculated models produce a significant amount of 56Ni, ranging from 0.1 Msun to 1.1 Msun, compatible not only with normal-Branch type Ia supernova but also with the subluminous and super-Chandrasekhar subset. Nevertheless, the distribution mass-function of white dwarfs favors collisions among 0.6-0.7 Msun objects, leading to subluminous events.
Electronic Wavefunction in Empirical Tight-Binding Theory

A procedure to obtain single-electron wave functions within the tight-binding formalism is proposed. It is based on linear combinations of Slater-type orbitals whose screening coefficients are extracted from the optical matrix elements of the tight-binding Hamiltonian. Bloch functions obtained for zinc-blende semiconductors in the extended-basis spds∗ tight-binding model demonstrate very good agreement with first-principles wave functions. We apply this method to the calculation of the electron-hole exchange interaction, and obtain the dispersion of excitonic fine structure in bulk GaAs. Beyond semiconductor nanostructures, this work is a fundamental step toward modeling many-body effects from post-processing single-particle wave functions within the tight-binding theory.
Testing of an Adaptive Algorithm for Estimating the Parameters of a Synchronous Generator Based on the Approximation of Electrical State Time Series

The results of testing the algorithms of the adaptive model of a synchronous generator using theoretical and real physical data are presented in this study. The adaptive model of a synchronous machine is an equations system, which describes both the static and transient operation of a generator. Parameters of the adaptive model are found using measurements of a generator’s operational parameters. The single-machine model was created in Matlab/Simulink software to test the theoretical data. This single-machine model consists of a synchronous generator, a step-up transformer, and a transmission line. The test model also includes models of the automatic voltage regulator and steam turbine governor. The real electrodynamic model was used to verify the adaptive model of a synchronous machine. It consisted of four synchronous generators, with values of power capacity of 5 kW and 15 kW. The data logger with a sampling rate of 57.8 kHz was developed and installed to measure the operating parameters of each generator. As a result of testing on both models, the following values were estimated: inertia moment, d-axis and q-axis reactance, and load angle. These values were compared with the reference values. The adaptive model of a synchronous machine can be used in systems of emergency control and assessment of generator state.
Hybrid Wi-Fi and BLE Fingerprinting Dataset for Multi-Floor Indoor Environments with Different Layouts

Indoor positioning has garnered significant interest over the last decade due to the rapidly growing demand for location-based services. As a result, a multitude of techniques has been proposed to localize objects and devices in indoor environments. Wireless fingerprinting, which leverages machine learning, has emerged as one of the most popular positioning approaches due to its low implementation cost. The prevailing fingerprinting-based positioning mainly utilizes wireless fidelity (Wi-Fi) and Bluetooth low energy (BLE) signals. However, the RSS of Wi-Fi and BLE signals are very sensitive to the layout of the indoor environment. Thus, any change in the indoor layout could potentially lead to severe degradation in terms of localization performance. To foster the development of new positioning methods, several open-source location fingerprinting datasets have been made available to the research community. Unfortunately, none of these public datasets provides the received signal strength (RSS) measurements for indoor environments with different layouts. To fill this gap, this paper presents a new hybrid Wi-Fi and BLE fingerprinting dataset for multi-floor indoor environments with different layouts to facilitate the future development of new fingerprinting-based positioning systems that can provide adaptive positioning performance in dynamic indoor environments. Additionally, the effects of indoor layout change on the location fingerprint and localization performance are also investigated.
Offsets of Masers with Respect to the Middle of the Perseus Arm and the Corotation Radius in the Milky Way

The radial distance to the corotation radius R coro (where the angular speed of the gas and stars, Ω gas , in orbit around the Galactic center (GC) is equal to the angular speed of the spiral arm pattern, Ω sp ) has often been predicted (at various places), but not measured with high precision. Here we test the locations of masers with respect to the Perseus arm (Table ). Our analysis of the masers and H ii regions near the Perseus arm (mostly located on the inner arm side, by about 0.4 ± 0.1 kpc from the cold CO mid-arm) shows that the corotation R coro must be >10.8 kpc from the GC (Figure ). This implies that the angular rotation speed of the spiral pattern Ω sp < 21.3 km s−1 kpc−1. Another test in Galactic quadrant II shows that the radial velocity of the masers is generally more negative than that of the CO mid-arm (Figure ), indicating a deceleration with respect to the CO mid-arm, by about 9 ± 3 km s−1. This implies that Ω sp < 20.7 km s−1 kpc−1, and thus R coro > 11.1 kpc. Finally, comparing our results with other published results (Table ), we find a statistical mean corotation radius R coro predicted to be near 12 ± 1 kpc from the GC (beyond the Perseus arm; before the Cygnus arm), and a mean angular spiral pattern speed, Ω sp , predicted to be near 19 ± 2 km s−1 kpc−1.
Hot molecular hydrogen in the central parsec of the Galaxy through near-infrared 3D fitting

Aims. We have investigated neutral gas in the central cavity of the circumnuclear disk (CND) at the Galactic Center, where the ionized minispiral lies, to describe the H2 distribution and properties in this ionized environment. Methods. This study was carried out through a spectro-imaging data cube of the central cavity obtained with SPIFFI on the VLT. The observed field of view is 36"x 29" , with a spectral resolution R = 1 300 in the near-infrared. These observations cover several H2 lines. To preserve the spatial resolution and avoid edge effects, we applied a new line-fitting method that consists of a regularized 3D fitting. We also applied a more classical 1D fitting to compare the relative strength of the H2 lines. Results. We present high spatial and spectral resolution maps of the intensity, velocity, and width of five H2 lines and an extinction map derived from H2. Molecular gas is detected everywhere in the field. In particular, in addition to the known CND features, we detected an emission from the northern arm cloud and from the minicavity. The excitation diagrams allow us to estimate the temperature, mass, and density of these features. Conclusions. We interpret the CND emission as coming from a hot, thermalized, thin layer at the surface of the clouds. The observed H2 corresponds only to a small fraction of the total H2 mass. The emission remains fairly strong in the whole central cavity, but it is not thermalized. A strong deviation from thermal equilibrium is detected near the minicavity. We suggest that this emission is caused by constantly forming H2 that is destroyed again before it reaches ortho/para equilibrium.
A new investigation of the possible X-ray counterparts of the magnetar candidate AX J1845−0258

AX J1845-0258 is a transient X-ray pulsar, with spin period of 6.97s, discovered with the ASCA satellite in 1993. Its soft spectrum and the possible association with a supernova remnant suggest that AX J1845-0258 might be a magnetar, but this has not been confirmed yet. A possible counterpart one order of magnitude fainter, AX J184453-025640, has been found in later X-ray observations, but no pulsations have been detected. In addition, some other X-ray sources are compatible with the pulsar location, which is in a crowded region of the Galactic plane. We have carried out a new investigation of all the X-ray sources in the ASCA error region of AX J1845-0258, using archival data obtained with Chandra in 2007 and 2010, and with XMM-Newton in 2010. We set an upper limit of 6% on the pulsed fraction of AX J184453-025640 and confirmed its rather hard spectrum (power law photon index of 1.2 +\- 0.3). In addition to the other two fainter sources already reported in the literature, we found other X-ray sources positionally consistent with AX J1845-0258. Although many of them are possibly foreground stars likely unrelated to the pulsar, at least another new source, CXOU J184457.5-025823, could be a plausible counterpart of AX J1845-0258. It has a flux of 6x10^{-14} erg cm^{-2} s^{-1} and a spectrum well fit by a power law with photon index ~1.3 and Nh ~ 10^{22} cm^{-2}.
Rayleigh waves, surface disorder, and phonon localization in nanostructures

We introduce a technique to calculate thermal conductivity in disordered nanostructures: a finite-difference time-domain (FDTD) solution of the elastic wave equation combined with the Green-Kubo formula. The technique captures phonon wave behavior and scales well to nanostructures that are too large or too surface disordered to simulate with many other techniques. We investigate the role of Rayleigh waves and surface disorder on thermal transport by studying graphenelike nanoribbons with free edges (allowing Rayleigh waves) and fixed edges (prohibiting Rayleigh waves). We find that free edges result in a significantly lower thermal conductivity than fixed ones. Free edges both introduce Rayleigh waves and cause all low-frequency modes (bulk and surface) to become more localized. Increasing surface disorder on free edges draws energy away from the center of the ribbon and toward the disordered edges, where it gets trapped in localized surface modes. These effects are not seen in ribbons with fixed boundary conditions and illustrate the importance of phonon surface modes in nanostructures.
Fully-Stripped Beryllium-Ion Collisions with 2ℓm States of Atomic Hydrogen: Target Excitation and Ionisation cross Sections

The wave-packet convergent close-coupling approach is used to calculate integrated target excitation and ionisation cross sections in bare beryllium-ion collisions with the 2ℓm states of atomic hydrogen (where n, ℓ and m are the principal, orbital angular momentum and magnetic quantum numbers, respectively). The calculations are performed at representative projectile energies between 10 keV/u to 1 MeV/u. The calculated cross sections for collisions with H(2s) are compared with recent theoretical results. Generally, good agreement is observed for the n-partial excitation and total ionisation cross sections. However, a significant discrepancy is found for excitation into the dominant n=3 states at 100 keV/u, where the target excitation cross-section peaks. We also present the first calculations of the excitation and ionisation cross sections for Be4+ collisions with H(2p0) and H(2p±1).
Corner contribution to the entanglement entropy of an O(3) quantum critical point in 2 + 1 dimensions

The entanglement entropy for a quantum critical system across a boundary with a corner exhibits a subleading logarithmic scaling term with a scale-invariant coefficient. Using a Numerical Linked Cluster Expansion, we calculate this universal quantity for a square-lattice bilayer Heisenberg model at its quantum critical point. We find, for this 2 + 1 dimensional O(3) universality class, that it is thrice the value calculated previously for the Ising universality class. This relation gives substantial evidence that this coefficient provides a measure of the number of degrees of freedom of the theory, analogous to the central charge in a 1 + 1 dimensional conformal field theory.
Rapidly rotating neutron stars in R-squared gravity

$f(R)$ theories of gravity are one of the most popular alternative explanations for dark energy, and therefore studying the possible astrophysical implications of these theories is an important task. In the present paper we make a substantial advance in this direction by considering rapidly rotating neutron stars in ${R}^{2}$ gravity. The results are obtained numerically, and the method we use is nonperturbative and self-consistent. The neutron star properties, such as mass, radius, and moment of inertia, are studied in detail. The results show that rotation magnifies the deviations from general relativity, and the maximum mass and moment of inertia can reach very high values. This observation is similar to the previous studies of rapidly rotating neutron stars in other alternative theories of gravity, such as scalar-tensor theories, and it can potentially lead to strong astrophysical manifestations.
High spatial frequency laser induced periodic surface structure formation in germanium by mid-IR femtosecond pulses

Formation of high spatial frequency laser induced periodic surface structures (HSFL) in germanium by femtosecond mid-IR pulses with wavelengths between $\lambda=2.0$ and $3.6 \; \mathrm{\mu m}$ was studied with varying angle of incidence and polarization. The period of these structures varied from $\lambda/3$ to $\lambda/8$. A modified surface-scattering model including Drude excitation and the optical Kerr effect explains spatial period scaling of HSFL across the mid-IR wavelengths. Transmission electron microscopy (TEM) shows the presence of a $30 \; \mathrm{n m}$ amorphous layer above the structure of crystalline germanium. Various mechanisms including two photon absorption and defect-induced amorphization are discussed as probable causes for the formation of this layer.
Bisectors of the HARPS cross-correlation function - The dependence on stellar atmospheric parameters

Context. Bisectors of the HARPS cross-correlation function (CCF) can discern between planetary radial-velocity (RV) signals and spurious RV signals from stellar magnetic activity variations. However, little is known about the effects of the stellar atmosphere on CCF bisectors or how these effects vary with spectral type and luminosity class. Aims. Here we investigate the variations in the shapes of HARPS CCF bisectors across the HR diagram in order to relate these to the basic stellar parameters, surface gravity and temperature. Methods. We use archive spectra of 67 well studied stars observed with HARPS and extract mean CCF bisectors. We derive previously defined bisector measures (BIS, vbot, cb) and we define and derive a new measure called the CCF bisector span (CBS) from the minimum radius of curvature on direct fits to the CCF bisector. Results. We show that the bisector measures correlate differently, and non-linearly with log g and Teff. The resulting correlations allow for the estimation of log g and Teff from the bisector measures. We compare our results with 3D stellar atmosphere models and show that we can reproduce the shape of the CCF bisector for the Sun.
Thresholded Graphical Lasso Adjusts for Latent Variables

Structural learning of Gaussian graphical models in the presence of latent variables has long been a challenging problem. Chandrasekaran et al. (2012) proposed a convex program to estimate a sparse graph plus low-rank term that adjusts for latent variables; but, this approach poses challenges from both a computational and statistical perspective. We propose an alternative and incredibly simple solution: apply a hard thresholding operator to existing graph selection methods. Conceptually simple and computationally attractive, we show that thresholding the graphical lasso is graph selection consistent in the presence of latent variables under a simpler minimum edge strength condition and at an improved statistical rate. We also extend results to thresholded neighbourhood selection and CLIME estimators as well. We show that our simple thresholded graph estimators enjoy stronger empirical results than existing approaches for the latent variable graphical model problem and conclude with a neuroscience case study to estimate functional neural connections.
Origin and evolution of structure and nucleosynthesis for galaxies in the local group

The Milky Way is the product of a complex evolution of generations of mergers, collapse, star formation, supernova and collisional heating, radiative and collisional cooling, and ejected nucleosynthesis. Moreover, all of this occurs in the context of the cosmic expansion, the formation of cosmic filaments, dark matter halos, spiral density waves, and emerging dark energy. In this review we summarize observational evidence and discuss recent calculations concerning the formation, evolution nucleosynthesis in the galaxies of the Local Group (LG). In particular, we will briefly summarize observations and simulations for the dwarf galaxies and the two large spirals of the LG. We discuss how galactic halos form within the dark matter filaments that define a super-galactic plane. Gravitational interaction along this structure leads to streaming flows toward the two dominant galaxies in the cluster. These simulations and observations also suggest that a significant fraction of the Galactic halo formed as at large distances and then arrived later along these streaming flows. We also consider the insight provided by observations and simulations of nucleosynthesis both within the galactic halo and dwarf galaxies in the LG.