Miracle-dz/UniFAR-FTUs huggingface dataset:
Evading Weinberg's no-go theorem to construct mass dimension one fermions: Constructing darkness

Recent theoretical work reporting the construction of a new quantum field of spin one half fermions with mass dimension one requires that Weinberg's no go theorem must be evaded. Here we show how this comes about. The essence of the argument is to first define a quantum field with due care being taken in fixing the locality phases attached to each of the expansion coefficients. The second ingredient is to systematically construct the adjoint/dual of the field. The Feynman-Dyson propagator constructed from the vacuum expectation value of the field and its adjoint then yields the mass dimensionality of the field. For a quantum field constructed from a complete set of eigenspinors of the charge conjugation operator, with locality phases judiciously chosen, the Feynman-Dyson propagator has mass dimension one. The Lorentz symmetry is preserved, locality anticommutators are satisfied, without violating fermionic statistics as needed for the spin one half field.
Primordial star formation under the influence of far ultraviolet radiation: 1540 cosmological haloes and the stellar mass distribution

We perform a large set of cosmological simulations of early structure formation and follow the formation and evolution of 1540 star-forming gas clouds to derive the mass distribution of primordial stars. The star formation in our cosmological simulations is characterized by two distinct populations, the so-called Population III.1 stars and primordial stars formed under the influence of far ultraviolet (FUV) radiation (Population III.2D stars). In this work, we determine the stellar masses by using the dependences on the physical properties of star-forming cloud and/or the external photodissociating intensity from nearby primordial stars, which are derived from the results of two-dimensional radiation hydrodynamic simulations of protostellar feedback. The characteristic mass of the Pop III stars is found to be a few hundred solar masses at z ~ 25, and it gradually shifts to lower masses with decreasing redshift. At high redshifts z > 20, about half of the star-forming gas clouds are exposed to intense FUV radiation and thus give birth to massive Pop III.2D stars. However, the local FUV radiation by nearby Pop III stars becomes weaker at lower redshifts, when typical Pop III stars have smaller masses and the mean physical separation between the stars becomes large owing to cosmic expansion. Therefore, at z < 20, a large fraction of the primordial gas clouds host Pop III.1 stars. At z =< 15, the Pop III.1 stars are formed in relatively cool gas clouds due to efficient radiative cooling by H_2 and HD molecules; such stars have masses of a few x 10 Msun. Since the stellar evolution and the final fate are determined by the stellar mass, Pop III stars formed at different epochs play different roles in the early universe.
On the nature of periodically pulsating radiation sources

A change in the character of maser generation in a two-level system is found when the initial population inversion exceeds some threshold value proportional to the square root of the total number of atoms. Above this threshold, the number of photons begins to grow exponentially with time and the pulse with short leading edge and broadened trailing edge is generated. In this work, we attempt to explain the nature of this threshold. Coherent pulse duration estimated by its half-width increases significantly with increasing inversion, if all other parameters are fixed and the absorption is neglected. The inclusion of the energy loss of photons leads to the fact that the duration of coherent pulse is almost constant with increasing inversion, at least well away from the threshold. If there is exist a recovery mechanism for the population inversion, the pulsating mode of stimulated emission generation becomes possible. The integral radiation intensity at this may be increased several times. This approach can be used for analysis of the cosmic radiation that might help explain a great variety of pulsating radiation sources in space.
Quantum state estimation with informationally overcomplete measurements

We study informationally overcomplete measurements for quantum state estimation so as to clarify their tomographic significance as compared with minimal informationally complete measurements. We show that informationally overcomplete measurements can improve the tomographic efficiency significantly over minimal measurements when the states of interest have high purities. Nevertheless, the efficiency is still too limited to be satisfactory with respect to figures of merit based on monotone Riemannian metrics, such as the Bures metric and quantum Chernoff metric. In this way, we also pinpoint the limitation of nonadaptive measurements and motivate the study of more sophisticated measurement schemes. In the course of our study, we introduce the best linear unbiased estimator and show that it is equally efficient as the maximum likelihood estimator in the large sample limit. This estimator may significantly outperform the canonical linear estimator for states with high purities. It is expected to play an important role in experimental designs and adaptive quantum state tomography besides its significance to the current study.
Crystallography of ice

Why is it interesting to study ice? The book reviewed in this issue 4 of Volume 28 of Crystallography Reviews boosts the reader’s amazement, enthusiasm and curiosity about the wonder and science of ice and snowflakes. While the review article gives a comprehensive overview of all the known twenty polymorphic forms of ice with an outlook to further predictable forms. Hydrogen is the most common element in the Universe, around 75% of all atoms in our galaxy is hydrogen. Oxygen is the third most common element in space, making up about 1% of all the atoms. Water, made of these two elements, plays a key role in the formation and evolution of our planetary system and it is essential in the life on Earth. The planet Earth is formed in the warm part of the sun’s protoplanetary disk, at a location well within the ‘snow line’. The presence of water is vital in the search for extraterrestrial life. Brighter regions observed by an optical telescope could indicate reflections of frozen water. Landers and rovers can collect samples from the surface of a planet to be placed in an analysis chamber. There is water-ice on the surface of the moon near the poles [1]. A subglacial lake on Mars, 1.5 km below the southern polar ice cap was detected [2]. Asteroids in the asteroid belt also contain large amounts of water-ice that could be harvested if humans ever regularly travel beyond the inner Solar System. Europa, a moon of Jupiter, and Enceladus, a moon of Saturn, have huge subsurface oceans with a layer of tens or hundreds of kilometres of ice covering their surfaces. Other moons of Jupiter and Saturn such as Ganymede and Titan may have subsurface oceans as well. There are very likely still millions of other icy bodies out there, just waiting to be explored. The varying conditions on the myriads of planets, moons, asteroids in space provide the opportunity of the probable formation of different ice polymorphs. Although ice may be one of the most studied crystalline solids in human history, new discoveries on ice are still being reported on a regular basis. The full review article ‘Neutrons meet ice polymorphs’ by Kazuki Komatsu from the Geochemical Research Center, Graduate School of Science, The University of Tokyo, Japan, gives an extensive review of the discovery and crystallographic characterization of ice polymorphs formed in different conditions. The presented historical background elucidates the experimental difficulties in ice research. The current epoch described by the author is the ‘age of ice-rush’, as the rate of discovery of ice polymorphs has accelerated in the last two decades owing to the advances in neutron diffraction studies of ice under pressure. The most extreme conditions, of both high-temperature and high-pressure, led to a new ice polymorph being created (namely XVIII) at 100GPa and 2000K. The transition between hydrogen-ordered and hydrogen-disordered phases is a common problem for many ice polymorphs. Ice polymorphs may exist in fully ordered and fully disordered states, but also they can be in partially-ordered states in between. The review by Kazuki Komatsu consists of three
POWER SPECTRUM ANALYSIS OF POLARIZED EMISSION FROM THE CANADIAN GALACTIC PLANE SURVEY

Angular power spectra are calculated and presented for the entirety of the Canadian Galactic Plane Survey polarization data set at 1.4 GHz covering an area of 1060 deg2. The data analyzed are a combination of data from the 100 m Effelsberg Telescope, the 26 m Telescope at the Dominion Radio Astrophysical Observatory, and the Synthesis Telescope at the Dominion Radio Astrophysical Observatory, allowing all scales to be sampled down to arcminute resolution. The resulting power spectra cover multipoles from ℓ ≈ 60 to ℓ ≈ 104 and display both a power-law component at low multipoles and a flattening at high multipoles from point sources. We fit the power spectrum with a model that accounts for these components and instrumental effects. The resulting power-law indices are found to have a mode of 2.3, similar to previous results. However, there are significant regional variations in the index, defying attempts to characterize the emission with a single value. The power-law index is found to increase away from the Galactic plane. A transition from small-scale to large-scale structure is evident at b = 9°, associated with the disk-halo transition in a 15° region around l = 108°. Localized variations in the index are found toward H ii regions and supernova remnants, but the interpretation of these variations is inconclusive. The power in the polarized emission is anticorrelated with bright thermal emission (traced by Hα emission) indicating that the thermal emission depolarizes background synchrotron emission.
Attraction, with boundaries

We study the basin of attraction of static extremal black holes, in the concrete setting of the STU model. By finding a connection to a decoupled Toda-like system and solving it exactly, we find a simple way to characterize the attraction basin via competing behaviors of certain parameters. The boundaries of attraction arise in the various limits where these parameters degenerate to zero. We find that these boundaries are generalizations of the recently introduced (extremal) subtracted geometry: the warp factors still exhibit asymptotic integer power law behaviors, but the powers can be different from one. As we cross over one of these boundaries (‘generalized subttractors’), the solutions turn unstable and start blowing up at finite radius and lose their asymptotic region. Our results are fully analytic, but we also solve a simpler theory where the attraction basin is lower dimensional and easy to visualize, and present a simple picture that illustrates many of the basic ideas.
Proximity-Based Educational Recommendations: A Multi-Objective Framework

Personalized learning and educational recommender systems are integral parts of modern online education systems. In this context, the problem of recommending the best learning material to students is a perfect example of sequential multi-objective recommendation. Learning material recommenders need to optimize for and balance between multiple goals, such as adapting to student ability, adjusting the learning material difficulty, increasing student knowledge, and serving student interest, at every step of the student learning sequence. However, the obscurity and incompatibility of these objectives pose additional challenges for learning material recommenders. To address these challenges, we propose Proximity-based Educational Recommendation (PEAR), a recommendation framework that suggests a ranked list of problems by approximating and balancing between problem difficulty and student ability. To achieve an accurate approximation of these objectives, PEAR can integrate with any state-of-the-art student and domain knowledge model. As an example of such student and domain knowledge model, we introduce Deep Q-matrix based Knowledge Tracing model (DQKT), and integrate PEAR with it. Rather than static recommendations, this framework dynamically suggests new problems at each step by tracking student knowledge level over time. We use an offline evaluation framework, Robust Evaluation Matrix (REM), to compare PEAR with various baseline recommendation policies under three different student simulators and demonstrate the effectiveness of our proposed model. We experiment with different student trajectory lengths and show that while PEAR can perform better than the baseline policies with fewer data, it is also robust with longer sequence lengths.
Deterministic and Robust Generation of Single Photons On a Chip with 99.5% Indistinguishability Using Rapid Adiabatic Passage

We demonstrate deterministic and robust generation of pulsed resonance fluorescence single photons from a single InGaAs quantum dot using the method of rapid adiabatic passage. Comparative study is performed with transform-limited, negatively chirped and positively chi rped pulses, identifying the last one to be the most robust against fluctuation of driving strength. The generated sing le photons are background free, have a vanishing twophoton emission probability of 0.3% and a raw (corrected) two-photon Hong-Ou-Mandel interference visibility of 97.9% (99.5%), reaching a precision that places single photons at the threshold for fault-tolerant surface-code quantum computing. The single-photon source can be readily scaled up to multi-photon entanglement and used for quantum metrology, boson sampling and linear optical quantum computing.
Determining Inclinations of Active Galactic Nuclei Via Their Narrow-Line Region Kinematics

Active galactic nuclei (AGNs) are axisymmetric systems to first order; their observed properties are likely strong functions of inclination with respect to our line of sight, yet the specific inclinations of all but a few AGNs are generally unknown. By determining the inclinations and geometries of nearby Seyfert galaxies using the kinematics of their narrow-line regions (NLRs) and comparing them with observed properties, we find strong correlations between inclination and total hydrogen column density, infrared color, and Hβ FWHM. These correlations provide evidence that the orientation of AGNs with respect to our line of sight affects how we perceive them beyond the Seyfert 1/2 dichotomy. They can also be used to constrain three-dimensional models of AGN components such as the broad-line region and torus. Additionally, we find weak correlations between AGN luminosity and several modeled NLR parameters, which suggests that the NLR geometry and kinematics are dependent to some degree on the AGN's radiation field.
Proceedings of the 2022 Truth and Trust Online Conference (TTO 2022), Virtual Event and Boston, MA, USA, October 12-14, 2022

While most social media companies have attempted to address the challenge of COVID-19 misinformation, the success of those policies is difficult to assess, especially when focusing on individual platforms. This study explores the relationship between Twitter and YouTube in spreading COVID-19 vaccine-related misinformation through a mixed-methods approach to analyzing a collection of tweets in 2021 sharing YouTube videos where those Twitter accounts had also linked to deleted YouTube videos. Principal components, cluster and network analyses are used to group the videos and tweets into interpretable groups by shared tweet dates, terms and sharing patterns; content analysis is employed to assess the orientation of tweets and videos to COVID19 messages. From this we observe that a preponderance of anti-vaccine messaging remains among users who previously shared suspect information, in which a dissident political framing dominates, and which suggests moderation policy inefficacy where the platforms interact.
Effect of turbulence on collisions of dust particles with planetesimals in protoplanetary disks

Planetesimals in gaseous protoplanetary disks may grow by collecting dust particles. Hydrodynamical studies show that small particles generally avoid collisions with the planetesimals because they are entrained by the flow around them. This occurs when $St$, the Stokes number, defined as the ratio of the dust stopping time to the planetesimal crossing time, becomes much smaller than unity. However, these studies have been limited to the laminar case, whereas these disks are believed to be turbulent. We want to estimate the influence of gas turbulence on the dust-planetesimal collision rate and on the impact speeds. We used three-dimensional direct numerical simulations of a fixed sphere (planetesimal) facing a laminar and turbulent flow seeded with small inertial particles (dust) subject to a Stokes drag. A no-slip boundary condition on the planetesimal surface is modeled via a penalty method. We find that turbulence can significantly increase the collision rate of dust particles with planetesimals. For a high turbulence case (when the amplitude of turbulent fluctuations is similar to the headwind velocity), we find that the collision probability remains equal to the geometrical rate or even higher for $St\geq 0.1$, i.e., for dust sizes an order of magnitude smaller than in the laminar case. We derive expressions to calculate impact probabilities as a function of dust and planetesimal size and turbulent intensity.
Drifting asteroid fragments around WD 1145+017

We have obtained extensive photometric observations of the polluted white dwarf WD 1145+017 which has been reported to be transited by at least one, and perhaps several, large asteroids (or, planetesimals) with dust emission. We have carried out 53 observation sessions on 37 nights, totaling 192 hours, of this 17th magnitude star with small to modest size telescopes covering the interval 2015 November 1 to 2016 January 21. In all, we have detected some 237 significant dips in flux. Periodograms of the data reveal a significant periodicity of 4.5004 hours that is consistent with the dominant ("A") period detected with K2. The folded light curve at this period shows there is an hour-long depression in flux with a mean depth of nearly 10%. This depression is comprised of a series of shorter and sometimes deeper dips that do not always occur at exactly the same orbital phase, and which would be unresolvable with K2. In fact, we find numerous dips in flux at other orbital phases. Nearly all of the dips associated with this activity appear to drift systematically in phase with respect to the "A" period by about 2.5 minutes per day with a dispersion of ~0.5 min/d, corresponding to a mean drift period of 4.4928 hours. In all, we can track approximately 15 of these drifting features. There is no detection of the "B"-"F" periods found with K2, but if they remain at the K2 levels we would not expect to have seen them. We explain the drifting motion as that of smaller bodies (`fragments') that break off from the asteroid and go into a slightly smaller orbit than that of the asteroid. If our interpretation is correct, we can use the drift rate to determine the mass of the asteroid. Under that scenario, we find that the mass of the asteroid is M_a ~ = 10^23 grams, or about 1/10th the mass of Ceres, with an uncertainty of about a factor of 2.
A 3D investigation of delocalised oxygen two-level defects in Josephson junctions

Environmental two-level systems (TLS) have been identified as significant decoherence sources in Josephson junction (JJ) based circuits. For such quantum devices to be functional, the removal or control of the TLS is a necessity. Understanding the microscopic origins of the 'strongly coupled' TLS type is one current path of investigation to that end. The delocalized oxygen model suggests the atomic position of an oxygen atom is spatially delocalized in the oxide forming the JJ barrier. In this report we extend this model from its previous 2+1D construction to a complete 3D description using a Wick-rotated time-dependent Schrodinger equation to solve for time-independent solutions in three dimensions. We compute experimentally observable parameters for phase qubits and compare the results to the 2+1D framework. We devise a Voronoi classification scheme to investigate oxygen atoms delocalizing within strained and non-strained crystalline lattices, as well as realistic atomic positions a JJ amorphous tunnel barrier constructed in previous density functional studies.
THE POSTERIOR DISTRIBUTION OF sin(i) VALUES FOR EXOPLANETS WITH MT sin(i) DETERMINED FROM RADIAL VELOCITY DATA

Radial velocity (RV) observations of an exoplanet system giving a value of MT sin(i) condition (i.e., give information about) not only the planet's true mass MT but also the value of sin(i) for that system (where i is the orbital inclination angle). Thus, the value of sin(i) for a system with any particular observed value of MT sin(i) cannot be assumed to be drawn randomly from a distribution corresponding to an isotropic i distribution, i.e., the presumptive prior distribution. Rather, the posterior distribution from which it is drawn depends on the intrinsic distribution of MT for the exoplanet population being studied. We give a simple Bayesian derivation of this relationship and apply it to several “toy models” for the intrinsic distribution of MT, on which we have significant information from available RV data in some mass ranges but little or none in others. The results show that the effect can be an important one. For example, even for simple power-law distributions of MT, the median value of sin(i) in an observed RV sample can vary between 0.860 and 0.023 (as compared to the 0.866 value for an isotropic i distribution) for indices of the power law in the range between −2 and +1, respectively. Over the same range of indices, the 95% confidence interval on MT varies from 1.0001–2.405 (α = −2) to 1.13–94.34 (α = +2) times larger than MT sin(i) due to sin(i) uncertainty alone. More complex, but still simple and plausible, distributions of MT yield more complicated and somewhat unintuitive posterior sin(i) distributions. In particular, if the MT distribution contains any characteristic mass scale Mc, the posterior sin(i) distribution will depend on the ratio of MT sin(i) to Mc, often in a non-trivial way. Our qualitative conclusion is that RV studies of exoplanets, both individual objects and statistical samples, should regard the sin(i) factor as more than a “numerical constant of order unity” with simple and well-understood statistical properties. We argue that reports of MT sin(i) determinations should be accompanied by a statement of the corresponding confidence bounds on MT at, say, the 95% level based on an explicitly stated assumed form of the true MT distribution in order to reflect more accurately the mass uncertainties associated with RV studies.