Miracle-dz/UniFAR-FTUs huggingface dataset:
EFFECT OF FIELD DIRECTION AND FIELD INTENSITY ON DIRECTED SPIRAL PERCOLATION

Directed spiral percolation (DSP) is a new percolation model with crossed external bias fields. Since percolation is a model of disorder, the effect of external bias fields on the properties of disordered systems can be studied numerically using DSP. In DSP, the bias fields are an in-plane directional field (E) and a field of rotational nature (B) applied perpendicular to the plane of the lattice. The critical properties of DSP clusters are studied here varying the direction of E field and intensities of both E and B fields in two-dimensions. The system shows interesting and unusual critical behavior at the percolation threshold. Not only the DSP model is found to belong in a new universality class compared to that of other percolation models but also the universality class remains invariant under the variation of E field direction. Varying the intensities of the E and B fields, a crossover from DSP to other percolation models has been studied. A phase diagram of the percolation models is obtained as a function of intensities of the bias fields E and B.
Versatile waveguide polarizer incorporating an ultrathin discontinuous silver film

We demonstrate the first transverse magnetic (TM) pass waveguide polarizer suitable for integrated optic or fiber optic geometries. The polarizing properties of waveguides incorporating an ultrathin discontinuous silver film are due to excitation of a localized surface plasmon mode. The polarizers have a large bandwidth (≳100 nm), high extinction ratios, and do not rely on sensitive phase matching conditions. We illustrate these novel polarizing properties on ion‐exchanged planar waveguides overlayed with a 5‐nm‐mass thick silver film. The measured extinction ratio was 35 dB/mm at 836 nm with 2 dB/mm loss for the TM polarization. The theoretical analysis of the film properties and waveguide propagation losses is compared with the experiments.
Criteria for the formation of Population III objects in the ultraviolet background radiation

We explore possibilities of collapse and star formation in Population III objects exposed to the external ultraviolet background (UVB) radiation. Assuming spherical symmetry, we solve self-consistently radiative transfer of photons, non-equilibrium H2 chemistry and gas hydrodynamics. Although the UVB does suppress the formation of low-mass objects, the negative feedback turns out to be weaker than previously suggested. In particular, the cut-off scale of collapse drops significantly below the virial temperature Tvir∼104 K at weak UV intensities (J21≲10−2), owing to both self-shielding of the gas and H2 cooling. Clouds above this cut-off tend to contract highly dynamically, further promoting self-shielding and H2 formation. For plausible radiation intensities and spectra, the collapsing gas can cool efficiently to temperatures well below 104 K before rotationally supported and the final H2 fraction reaches ∼ 10−3. Our results imply that star formation can take place in low-mass objects collapsing in the UVB. The threshold baryon mass for star formation is ∼ 109 M⊙ for clouds collapsing at redshifts z≲3, but drops significantly at higher redshifts. In a conventional cold dark matter universe, the latter coincides roughly with that of the 1σ density fluctuations. Objects near and above this threshold can thus constitute ‘building blocks’ of luminous structures, and we discuss their links to dwarf spheroidal/elliptical galaxies and faint blue objects. These results suggest that the UVB can play a key role in regulating the star formation history of the Universe.
A relational solution to the problem of time in quantum mechanics and quantum gravity: a fundamental mechanism for quantum decoherence

The use of a relational time in quantum mechanics is a framework in which one promotes to quantum operators all variables in a system, and later chooses one of the variables to operate like a ‘clock’. Conditional probabilities are computed for variables of the system to take certain values when the ‘clock’ specifies a certain time. This framework is attractive in contexts where the assumption of usual quantum mechanics of the existence of an external, perfectly classical clock, appears unnatural, as in quantum cosmology. Until recently, there were problems with such constructions in ordinary quantum mechanics with additional difficulties in the context of constrained theories like general relativity. A scheme we recently introduced to consistently discretize general relativity removed such obstacles. Since the clock is now an object subject to quantum fluctuations, the resulting evolution in time is not exactly unitary and pure states decohere into mixed states. Here we work out in detail the type of decoherence generated, and we find it to be of Lindblad type. This is attractive since it implies that one can have loss of coherence without violating the conservation of energy. We apply the framework to a simple cosmological model to illustrate how a quantitative estimate of the effect could be computed. For most quantum systems it appears to be too small to be observed, although certain macroscopic quantum systems could in the future provide a testing ground for experimental observation.
“You Have to Prove that You’re Homeless”: Vulnerability and Gatekeeping in Public Housing Prioritization Policies

Building on theories of symbolic boundaries, this article explores the role of the state as gatekeeper to social programs, such as public housing. Using interviews with 75 randomly sampled households living in public housing in Honolulu County, we link contemporary research on gatekeeping with decades of work on how housing policy drives residential outcomes for marginalized groups. In particular, we consider the largely unexamined case of “local preferences,” which fast-track certain individuals into social programs based on locally established criteria. Our data suggest that these prioritization categories have evolved over time and are now largely focused on providing housing to those experiencing homelessness and victims of domestic violence. Ultimately, this apparently mundane bureaucratic process mediates relationships between social service agencies, individual needs, and overwhelming housing demand, all collaborating to construct symbolic boundaries across which deservingness is defined and adjudicated. We find that waitlist prioritization criteria cannot be reduced to a basic assessment of need as it necessarily instigates issues of definition (e.g., what is homelessness? ) and legibility (e.g., how does one prove homelessness? ). These collateral issues amplify the importance of institutional social capital and, in some cases, generate conflict between and within eligible communities.
Pseudogap, superconducting energy scale, and Fermi arcs of underdoped cuprate superconductors

Through the measurements of magnetic field dependence of specific heat in La2-xSrxCuO4 in zero temperature limit, we determined the nodal slope v(Delta) of the quasiparticle gap. It is found that v(Delta) has a very similar doping dependence of the pseudogap temperature T-* or value Delta(p). Meanwhile the virtual maximum gap at (pi,0) derived from v(Delta) is found to follow the simple relation Delta(q)=0.46k(B)T(*) upon changing the doping concentration. This strongly suggests a close relationship between the pseudogap and superconductivity. It is further found that the superconducting transition temperature is determined by both the residual density of states of the pseudogap phase and the nodal gap slope in the zero temperature limit, namely, T(c)approximate to beta v(Delta)gamma(n)(0), where gamma(n)(0) is the extracted zero temperature value of the normal state specific heat coefficient which is proportional to the size of the residual Fermi arc k(arc). This shows that the superconductivity may be formed by forming a new gap on the Fermi arcs near nodes below T-c. These observations mimic the key predictions of the SU(2) slave boson theory based on the general resonating-valence-bond picture.
High-resolution imaging of the radio continuum and neutral gas in the inner kiloparsec of the radio galaxy 3C 293

Using a combination of observations involving the Very Large Array (VLA), MERLIN and global Very Long Baseline Interferometry (VLBI) networks we have made a detailed study of the radio continuum and the neutral hydrogen (H i) kinematics and distribution within the central kiloparsec of the radio galaxy 3C 293. These observations trace the complex jet structure and identify the position of the steeply inverted radio core at 1.3 GHz. Strong H i absorption is detected against the majority of the inner kiloparsec of 3C 293. This absorption is separated into two dynamically different and spatially resolved systems. Against the eastern part of the inner radio jet, narrow H i absorption is detected and shown to have higher optical depths in areas cospatial with a central dust lane. Additionally, this narrow line is shown to follow a velocity gradient of ∼50 km s−1 arcsec−1, consistent with the velocity gradient observed in optical spectroscopy of ionized gas. We conclude that the narrow H i absorption, dust and ionized gas are physically associated and situated several kiloparsecs from the centre of the host galaxy. Against the western jet emission and core component, broad and complex H i absorption is detected. This broad and complex absorption structure is discussed in terms of two possible interpretations for the gas kinematics observed. We explore the possibility that these broad, double absorption spectra are the result of two gas layers at different velocities and distances along these lines of sight. A second plausible explanation for this absorbing structure is that the H i is situated in rotation about the core of this radio galaxy with some velocity dispersion resulting from infall and outflow of gas from the core region. If the latter explanation were correct, then the mass enclosed by the rotating disc would be at least 1.7 × 109 solar masses within a radius of 400 pc.
Emergence of quantum-classical dynamics in an open quantum environment

The conditions under which an open quantum-mechanical system may be described by mixed quantum-classical dynamics are investigated. Decoherence is studied using influence functional methods in a model composite quantum system comprising two coupled systems, A and C, interacting with a harmonic bath with Ohmic and super-Ohmic spectral densities. Subsystem A is directly coupled to subsystem C, while C is coupled directly to the bath. Calculations are presented for a model where subsystem A is taken to be a two-level system which is bilinearly coupled to a single harmonic oscillator C subsystem. The loss of quantum coherence in each subsystem is discussed in the extreme nonadiabatic regime where the intrinsic dynamics of subsystem A is essentially frozen. Subsystem C is shown to lose its coherence rapidly, while subsystem A maintains coherence for longer time periods since C modulates the influence of the bath on A. Thus, one may identify situations where the coupled AC system evolution effectively obeys mixed quantum-classical dynamics.
Non-equilibrium vortex annealing of structural disorder in Berezinskii-Kosterlitz-Thouless dynamics of the two-dimensional XY-model

The non-equilibrium annealing of structural disorder in a two-dimensional XY-model leads to coarsening of defects clusters in cores of spin vortices. We revealed the effect of “inertial” growth of the clusters in coarsening dynamic regime. The calculated transverse stiffness as a function of temperature T and spin concentration p of the system in the high-temperature phase T_{\text{BKT}}(p)$ ? > becomes negative and it is described by a power law with temperature-independent exponent . The dynamical scaling leads to the dynamic dependence of the correlation length which can be explained by a shift of the spin vortices friction constant γ induced by annealed disorder.
Anomalous sign inversion of spin-orbit torque in ferromagnetic/nonmagnetic bilayer systems due to self-induced spin-orbit torque

Self-induced spin-orbit torques (SI-SOTs) in ferromagnetic (FM) layers have been overlooked when estimating the spin Hall angle (SHA) of adjacent nonmagnetic (NM) layers. In this work, we observe anomalous sign inversion of the total SOT in the spin-torque ferromagnetic resonance due to the enhanced SI-SOT, and successfully rationalize the sign inversion through a theoretical calculation considering the SHE in both the NM and FM layers. The findings show that using an FM layer whose SHA sign is the same as that of the NM achieves efficient SOT-magnetization switching with the assistance of the SI-SOT. The contribution of the SI-SOT becomes salient for a weakly conductive NM layer, and conventional analyses that do not consider the SI-SOT can overestimate the SHA of the NM layer by a factor of more than 150. model including the SHE of Co calculated using the spin-diffusion equation well reproduced the experimental results. This model shows that investigating the SHE in various kinds of NM/FM bilayers and choosing an FM layer with the same signs for  FM as  NM achieves efficient SOT action in an NM/FM bilayer. In addition, we found that neglecting the SI-SOT causes overestimation of  NM by two orders for weakly conductive NM layers. The findings in this study enable more reliable SOT estimation, which contributes to development of spin-orbitronics using SOT materials. Furthermore, the significant effect of SI-SOT requires revisiting previous studies claiming high SHAs.
Lamb‐wave delay lines with interdigital electrodes

Propagation characteristics and the equivalent circuit model of delay lines using Lamb waves excited by interdigital transducers on unpolarized PZT ceramic plates have been studied. Dispersive characteristics of phase velocities of Lamb waves excited by the interdigital transducers are in good agreement with the numerical solution from the dispersive equation of phase velocities developed by Worlton. When the product of frequency times plate thickness is below 1.3×106 Hz mm, the zeroth symmetric Lamb wave is strongly excited. The Lamb waves are excited most effectively when the half‐period of interdigital electrode is equal to the wavelength of the Lamb wave. Also, the values of the attenuation coefficient and the reflection coefficient from the edge of the specimen are given. It is shown that the generation of symmetrical‐mode Lamb waves by our transducer is equivalently represented by a thickness mode transducer of half‐wavelength inserted perpendicular to the plate.
Secondary scintillation yield in pure xenon

The xenon secondary scintillation yield was studied as a function of the electric field in the scintillation region, in a gas proportional scintillation counter operated at room temperature. A large area avalanche photodiode was used for the readout of the VUV secondary scintillation produced in the gas, together with the 5.9 keV x-rays directly absorbed in the photodiode. The latter was used as a reference for the determination of the number of charge carriers produced by the scintillation pulse and, thus, the number of VUV photons impinging the photodiode. A value of 140 photons/kV was obtained for the scintillation amplification parameter. The attained results are in good agreement with those predicted, for room temperature, by Monte Carlo simulation and Boltzmann calculations, as well as with those obtained for saturated xenon vapour, at cryogenic temperatures, and are about a factor of two higher than former results measured at room temperature.
Making Terrestrial Planets: High Temperatures, FU Orionis Outbursts, Earth, and Planetary System Architectures

Current protoplanetary dust coagulation theory does not predict dry silicate planetesimals, in tension with the Earth. While remedies to this predicament have been proposed, they have generally failed numerical studies, or are in tension with the Earth’s (low, volatility dependent) volatile and moderately volatile elemental abundances. Expanding on the work of Boley et al., we examine the implications of molten grain collisions and find that they may provide a solution to the dry silicate planetesimal problem. Furthermore, the source of the heating, whether it be a hot inner disk or an FU Orionis scale accretion event, would dictate the location of the resulting planetesimals, potentially controlling subsequent planetary system architectures. We hypothesize that systems that did undergo FU Orionis scale accretion events host planetary systems similar to our own, while ones that did not undergo such an accretion event instead host very close in, tightly packed planets such as those seen by Kepler.
A priori method for propensity rules for inelastic electron tunneling spectroscopy of single-molecule conduction

An a priori computational method for determining intensities in inelastic electron tunneling spectroscopy (IETS) is developed that allows simple, chemically intuitive propensity rules to be obtained for arbitrary applications. The molecule is shown to scatter charges between quite specific eigenchannels of lead-coupling-weighted molecular density of states. This allows mode-specific scattering sites to be identified within the molecule, indicating how external chemical or other perturbations could be used to control IETS intensities.
Lidar-based door and stair detection from a mobile robot

We present an on-the-move LIDAR-based object detection system for autonomous and semi-autonomous unmanned vehicle systems. In this paper we make several contributions: (i) we describe an algorithm for real-time detection of objects such as doors and stairs in indoor environments; (ii) we describe efficient data structures and algorithms for processing 3D point clouds acquired by laser scanners in a streaming manner, which minimize the memory copying and access. We show qualitative results demonstrating the effectiveness of our approach on runs in an indoor office environment.
Entropies of Mixing and the Lorenz Order

Entropies of mixing can be derived directly from the parent distributions of extreme value theory. They correspond to pseudo-additive entropies in the case of Pareto and power function distributions, while to the Shannon entropy in the case of the exponential distribution.The former tend to the latter when their shape parameters tend to infinity and zero, respectively. Hence processes whose entropies of mixing are pseudo-additive entropies majorize, in the Lorenz order sense, those whose entropy is the Shannon entropy. In the case of the arcsine distribution, maximal properties of regular polygons correspond to maximum entropy of mixing.
Impact of 3D Antenna Radiation Pattern on Heterogeneous Cellular Networks

Heterogeneous cellular networks (HCNs) play a significant role in 5G networks, but have mainly been modeled and analyzed on a two-dimensional (2D) plane. In this paper, we model a three-dimensional (3D) two-tier HCN consisting of macro-cells and small-cells via a stochastic geometry approach, where the base stations (BSs) in each tier are assigned an appropriate antenna downtilt to enhance the downlink signal and suppress the inter-cell interference. Based on the 3D HCN model, we derive the downlink spatially-averaged coverage probability and area spectral efficiency (ASE) as functions of the BS antenna downtilts, BS heights, BS densities and cell-association bias. To facilitate fast numerical evaluation, we propose accurate approximations for the integral parts in the coverage probability expression. We then obtain the optimal BS antenna downtilts for both tiers that maximize the downlink spatially-averaged coverage probability by using partial derivative and the bisection method. Analytical and simulation results show that for given BS heights, densities of small-cell BSs (SBSs) and cell-association biases of SBSs, our optimized BS antenna downtilts of both tiers can significantly enhance the downlink spatially-averaged coverage probability and ASE in comparison with the fixed BS antenna downtilts network. Useful insights into the 3D deployment of HCNs considering BS antenna downtilts are obtained based on the analytical and simulation results.
Effect of intrinsic spin relaxation on the spin-dependent cotunneling transport through quantum dots

Spin-polarized transport through quantum dots is analyzed theoretically in the cotunneling regime. It is shown that the zero-bias anomaly, found recently in the antiparallel configuration, can also exist in the case when one electrode is magnetic while the other one is nonmagnetic. Physical mechanism of the anomaly is also discussed. It is demonstrated that intrinsic spin relaxation in the dot has a significant influence on the zero-bias maximum in the differential conductance -- the anomaly becomes enhanced by weak spin-flip scattering in the dot and then disappears in the limit of fast spin relaxation. Apart from this, inverse tunnel magnetoresistance has been found in the limit of fast intrinsic spin relaxation in the dot. The diode-like behavior of transport characteristics in the cotunneling regime has been found in the case of quantum dots asymmetrically coupled to the leads. This behavior may be enhanced by the spin-flip relaxation processes.
Depth-concentration profile of hydrogen in niobium

Hydrogen concentration profiles near the surface of hydrogen-charged Nb samples have been measured by utilizing the /sup 1/H(/sup 15/N, .cap alpha gamma.)/sup 12/C reaction. The Nb foils were charged under various ambient conditions to concentrations corresponding to the single-phase . cap alpha. ' region in the phase diagram. Each sample exhibited a strong H surface peak followed by a sharp dip and a gradual increase in H concentration to a plateau. The rate at which the hydrogen concentration increases towards the bulk as well as the height of the plateau is related to the method of sample preparation, the higher the oxygen content, the lower the hydrogen concentration near the surface. These observations suggest that the H concentration near the surface of . cap alpha. '-Nb--55 at. % H is lower than that in the bulk because of the presence of oxides and dissolved oxygen. They also indicate that samples charged with hydrogen after heating to over approx.250 /sup 0/C in a pressure of >1 x 10/sup -6/ Torr will develop an oxygen-enriched and hydrogen-depleted zone near the surface.