cssi/SciSciGPT-SciSciNet huggingface dataset:
On the three-dimensional magnetohydrodynamics system in scaling-invariant spaces

Abstract We study the criterion for the velocity and magnetic vector fields that solve the three-dimensional magnetohydrodynamics system, given any initial data sufficiently smooth, to experience a finite-time blowup. Following the work of Chemin and Zhang [12] and making use of the structure of the system, we obtain a criterion that is imposed on the magnetic vector field and only one of the three components of the velocity vector field, both in scaling-invariant spaces.
paper2repo: GitHub Repository Recommendation for Academic Papers

GitHub has become a popular social application platform, where a large number of users post their open source projects. In particular, an increasing number of researchers release repositories of source code related to their research papers in order to attract more people to follow their work. Motivated by this trend, we describe a novel item-item cross-platform recommender system, paper2repo, that recommends relevant repositories on GitHub that match a given paper in an academic search system such as Microsoft Academic. The key challenge is to identify the similarity between an input paper and its related repositories across the two platforms, without the benefit of human labeling. Towards that end, paper2repo integrates text encoding and constrained graph convolutional networks (GCN) to automatically learn and map the embeddings of papers and repositories into the same space, where proximity offers the basis for recommendation. To make our method more practical in real life systems, labels used for model training are computed automatically from features of user actions on GitHub. In machine learning, such automatic labeling is often called distant supervision. To the authors’ knowledge, this is the first distant-supervised cross-platform (paper to repository) matching system. We evaluate the performance of paper2repo on real-world data sets collected from GitHub and Microsoft Academic. Results demonstrate that it outperforms other state of the art recommendation methods.
Polynomial-Time Computation of Optimal Correlated Equilibria in Two-Player Extensive-Form Games with Public Chance Moves and Beyond

Unlike normal-form games, where correlated equilibria have been studied for more than 45 years, extensive-form correlation is still generally not well understood. Part of the reason for this gap is that the sequential nature of extensive-form games allows for a richness of behaviors and incentives that are not possible in normal-form settings. This richness translates to a significantly different complexity landscape surrounding extensive-form correlated equilibria. As of today, it is known that finding an optimal extensive-form correlated equilibrium (EFCE), extensive-form coarse correlated equilibrium (EFCCE), or normal-form coarse correlated equilibrium (NFCCE) in a two-player extensive-form game is computationally tractable when the game does not include chance moves, and intractable when the game involves chance moves. In this paper we significantly refine this complexity threshold by showing that, in two-player games, an optimal correlated equilibrium can be computed in polynomial time, provided that a certain condition is satisfied. We show that the condition holds, for example, when all chance moves are public, that is, both players observe all chance moves. This implies that an optimal EFCE, EFCCE and NFCCE can be computed in polynomial time in the game size in two-player games with public chance moves, providing the biggest positive complexity result surrounding extensive-form correlation in more than a decade.
Formal Verification of Nonlinear Inequalities with Taylor Interval Approximations

We present a formal tool for verification of multivariate nonlinear inequalities. Our verification method is based on interval arithmetic with Taylor approximations. Our tool is implemented in the HOL Light proof assistant and it is capable to verify multivariate nonlinear polynomial and non-polynomial inequalities on rectangular domains. One of the main features of our work is an efficient implementation of the verification procedure which can prove non-trivial high-dimensional inequalities in several seconds. We developed the verification tool as a part of the Flyspeck project (a formal proof of the Kepler conjecture). The Flyspeck project includes about 1000 nonlinear inequalities. We successfully tested our method on more than 100 Flyspeck inequalities and estimated that the formal verification procedure is about 3000 times slower than an informal verification method implemented in C++. We also describe future work and prospective optimizations for our method.
Finding White Dwarfs with Transit Searches

We make predictions for the rate of discovery of eclipsing white dwarf-main-sequence (WD-MS) binaries in terrestrial-planet transit searches, taking the planned Kepler and Eddington missions as examples. We use a population synthesis model to characterize the Galactic WD-MS population, and we find that, despite increased noise due to stellar variability compared with the typical planetary case, discovery of 102 nonaccreting, eclipsing WD-MS systems is likely using Kepler and Eddington, with periods of 2-20 days and transit amplitudes of |Δm| ~ 10-4±0.5 mag. Follow-up observations of these systems could accurately test the theoretical white dwarf mass-radius relation or theories of binary star evolution.
``Background field integration-by-parts'' and the connection between one-loop and two-loop Heisenberg-Euler effective actions

We develop integration-by-parts rules for diagrams involving massive scalar propagators in a constant background electromagnetic field, and use these to show that there is a simple diagrammatic interpretation of mass renormalization in the two-loop scalar QED Heisenberg-Euler effective action for a general constant background field. This explains why the square of a one-loop term appears in the renormalized two-loop Heisenberg-Euler effective action. No integrals need be evaluated, and the explicit form of the background field propagators is not needed. This dramatically simplifies the computation of the renormalized two-loop effective action for scalar QED, and generalizes a previous result obtained for self-dual background fields.
Three Proofs of the Makeenko–Migdal Equation for Yang–Mills Theory on the Plane

We give three short proofs of the Makeenko–Migdal equation for the Yang–Mills measure on the plane, two using the edge variables and one using the loop or lasso variables. Our proofs are significantly simpler than the earlier pioneering rigorous proofs given by Levy and by Dahlqvist. In particular, our proofs are “local” in nature, in that they involve only derivatives with respect to variables adjacent to the crossing in question. In an accompanying paper with Gabriel, we show that two of our proofs can be adapted to the case of Yang–Mills theory on any compact surface.
Four-genera of links and Heegaard Floer homology

For links with vanishing pairwise linking numbers, the link components bound pairwise disjoint oriented surfaces in B 4 . We use the h –function which is a link invariant from the Heegaard Floer homology to give lower bounds for the 4 –genus of the link. For L –space links, the h –function is explicitly determined by the Alexander polynomials of the link and its sublinks. We show some L –space links where the lower bounds are sharp, and also describe all possible genera of disjoint oriented surfaces bounded by such links.
STRING WEBS AND THE DECAY OF SUPERSYMMETRIC PARTICLES

The spectrum of stable electrically and magnetically charged supersymmetric particles can change discontinously due to the decay of these particles as the vacuum on the Coulomb branch is varied. We show that this decay process is well described by semiclassical field configurations even when it occurs at strong coupling. the resulting picture of the stable supersymmetric spectrum is a generalization of the "string web" picture of these states found in string constructions.
Feasibility Study for Implementing an Optical Thomson Scattering System for Studying Photoionized Plasmas on Z

Many astrophysical environments, such as X-ray binaries, active galactic nuclei, and accretion disks of compact objects, have photoionized plasmas. The strong photoionizing environment found near these bright X-ray sources can be produced in a scaled laboratory experiment, and direct measurements can form a testbed for spectroscopic models and photoionization codes used in the analysis of these astrophysical objects. Such scaled experiments are currently being conducted using Ne-filled gas cells on the Z-facility as part of the Z astrophysical plasma properties collaboration. The plasma is diagnosed using a pressure sensor for density and X-ray absorption spectroscopy for charge-state distribution. The electron temperature is presently inferred from a Li-like ion-level population ratio, but it is necessary to obtain an independent temperature measurement, as photoionization alters the charge state distribution and can therefore cause errors in temperatures obtained via line-ratio techniques. Optical Thomson scattering is a fitting diagnostic, because it directly probes the distribution of plasma particle velocities with respect to a central probe frequency. It is a powerful diagnostic, which can produce time- and space-resolved measurements of electron temperature as well as electron density, ion temperature, and average ionization. In this paper, we explore a possible design for an optical Thomson scattering system to supplement X-ray spectroscopic measurements. The proposed design will use equipment that is available, though not yet assembled, on Z. Both the feasibility and impact of this new diagnostic are assessed by simulating expected spectra for a range of plasma parameters, thereby demonstrating the sensitivity of this diagnostic.
Above and beyond: holographic tracking of axial displacements in holographic optical tweezers

How far a particle moves along the optical axis in a holographic optical trap is not simply dictated by the programmed motion of the trap, but rather depends on an interplay of the trap’s changing shape and the particle’s material properties. For the particular case of colloidal spheres in optical tweezers, holographic video microscopy reveals that trapped particles tend to move farther along the axial direction than the traps that are moving them and that different kinds of particles move by different amounts. These surprising and sizeable variations in axial placement can be explained by a dipole-order theory for optical forces. Their discovery highlights the need for real-time feedback to achieve precise control of colloidal assemblies in three dimensions and demonstrates that holographic microscopy can meet that need.
Sound propagation and force chains in granular materials

Granular materials are inherently heterogeneous, leading to challenges in formulating accurate models of sound propagation. In order to quantify acoustic responses in space and time, we perform experiments in a photoelastic granular material in which the internal stress pattern (in the form of force chains) is visible. We utilize two complementary methods, high-speed imaging and piezoelectric transduction, to provide particle-scale measurements of both the amplitude and speed of an acoustic wave in the near-field regime. We observe that the wave amplitude is on average largest within particles experiencing the largest forces, particularly in those chains radiating away from the source, with the force-dependence of this amplitude in qualitative agreement with a simple Hertzian-like model of particle contact area. In addition, we are able to directly observe rare transiently strong force chains formed by the opening and closing of contacts during propagation. The speed of the leading edge of the pulse is in agreement with the speed of a one-dimensional chain, while the slower speed of the peak response suggests that it contains waves which have travelled over multiple paths even within just this near-field region. These effects highlight the importance of particle-scale behaviors in determining the acoustical properties of granular materials.
Destriping cosmic microwave background polarimeter data

Abstract Destriping is a well-established technique for removing low-frequency correlated noise from Cosmic Microwave Background (CMB) survey data. In this paper we present a destriping algorithm tailored to data from a polarimeter, i.e. an instrument where each channel independently measures the polarization of the input signal. We also describe a fully parallel implementation in Python released as Open Source software and analyze its results and performance on simulated datasets, both the design case of signal and correlated noise, and also with the addition of other systematic effects. Finally we apply the algorithm to 30 days of 37.5 GHz polarized microwave data gathered from the B-Machine experiment, developed at UCSB. The B-Machine data and destriped maps are publicly available. The purpose is the development of a scalable software tool to be applied to the upcoming 12 months of temperature and polarization data from LATTE (Low frequency All sky TemperaTure Experiment) at 8 GHz and to even larger datasets.
BAGEL: Brilliantly Advanced General Electronic-structure Library

On behalf of the development team, I review the capabilities of the Brilliantly Advanced General Electronic-structure Library (BAGEL) program package in this article. BAGEL is a newly developed full-fledged program package for electronic-structure computation in quantum chemistry, which is released under the GNU General Public License with many contributions from the developers. The unique features include analytical CASPT2 nuclear energy gradients and derivative couplings, relativistic multireference wave functions based on the Dirac equation, and implementations of novel electronic structure theories. All of the programs are efficiently parallelized using both threads and MPI processes. We also discuss the code generator SMITH3, which has been used to implement some of the programs in BAGEL. The developers’ contributions are listed at the end of the main text. For further resources related to this article, please visit the WIREs website.
Transport, Aharonov−Bohm, and Topological Effects in Graphene Molecular Junctions and Graphene Nanorings

The unique ultrarelativistic, massless, nature of electron states in two-dimensional extended graphene sheets, brought about by the honeycomb lattice arrangement of carbon atoms in two dimensions, provides ingress to explorations of fundamental physical phenomena in graphene nanostructures. Here, we explore the emergence of new behavior of electrons in atomically precise segmented graphene nanoribbons (GNRs) and graphene rings with the use of tight-binding calculations, nonequilibrium Green's function transport theory, and a newly developed Dirac continuum model that absorbs the valence-to-conductance energy gaps as position-dependent masses, including topological-in-origin mass barriers at the contacts between segments. Through transport investigations in variable-width segmented GNRs with armchair, zigzag, and mixed edge terminations, we uncover development of new Fabry−Peinterference patterns in segmented GNRs, a crossover from the ultrarelativistic massless regime, characteristic of extended graphene systems, to a massive relativistic behavior in narrow armchair GNRs, and the emergence of nonrelativistic behavior in zigzag-terminated GNRs. Evaluation of the electronic states in a polygonal graphene nanoring under the influence of an applied magnetic field in the Aharonov−Bohm regime and their analysis with the use of a relativistic quantum field theoretical model unveils development of a topological-in-origin zero-energy soliton state and charge fractionization. These results provide a unifying framework for analysis of electronic states, coherent transport phenomena, and the interpretation of forthcoming experiments in segmented GNRs and polygonal rings.
Certifiably optimal sparse inverse covariance estimation

We consider the maximum likelihood estimation of sparse inverse covariance matrices. We demonstrate that current heuristic approaches primarily encourage robustness, instead of the desired sparsity. We give a novel approach that solves the cardinality constrained likelihood problem to certifiable optimality. The approach uses techniques from mixed-integer optimization and convex optimization, and provides a high-quality solution with a guarantee on its suboptimality, even if the algorithm is terminated early. Using a variety of synthetic and real datasets, we demonstrate that our approach can solve problems where the dimension of the inverse covariance matrix is up to 1000 s. We also demonstrate that our approach produces significantly sparser solutions than Glasso and other popular learning procedures, makes less false discoveries, while still maintaining state-of-the-art accuracy.
The complexity of the topological conjugacy problem for Toeplitz subshifts

In this paper, we analyze the Borel complexity of the topological conjugacy relation on Toeplitz subshifts. More specifically, we prove that topological conjugacy of Toeplitz subshifts with separated holes is hyperfinite. Indeed, we show that the topological conjugacy relation is hyperfinite on a larger class of Toeplitz subshifts which we call Toeplitz subshifts with growing blocks. This result provides a partial answer to a question asked by Sabok and Tsankov.
A high-energy nuclear database proposal

We propose to develop a high-energy heavy-ion experimental database and make it accessible to the scientific community through an on-line interface. This database will be searchable and cross-indexed with relevant publications, including published detector descriptions. Since this database will be a community resource, it requires the high-energy nuclear physics community’s financial and manpower support. This database should eventually contain all published data from the Bevalac, AGS and SPS to RHIC and LHC energies, proton-proton to nucleus-nucleus collisions as well as other relevant systems, and all measured observables. Such a database would have tremendous scientific payoff as it makes systematic studies easier and allows simpler benchmarking of theoretical models to a broad range of old and new experiments. Furthermore, there is a growing need for compilations of high-energy nuclear data for applications including stockpile stewardship, technology development for inertial confinement fusion and target and source development for upcoming facilities such as the Next Linear Collider. To enhance the utility of this database, we propose periodically performing evaluations of the data and summarizing the results in topical reviews.
Chromospheric Activity of HAT-P-11: An Unusually Active Planet-hosting K Star

Kepler photometry of the hot Neptune host star HAT-P-11 suggests that its spot latitude distribution is comparable to the Sun's near solar maximum. We search for evidence of an activity cycle in the Ca ii H & K chromospheric emission S-index with archival Keck/HIRES spectra and observations from the echelle spectrograph on the Astrophysical Research Consortium 3.5 m Telescope at Apache Point Observatory. The chromospheric emission of HAT-P-11 is consistent with an ≳ 10 year activity cycle, which plateaued near maximum during the Kepler mission. In the cycle that we observed, the star seemed to spend more time near active maximum than minimum. We compare the log R_(HK)^′ normalized chromospheric emission index of HAT-P-11 with other stars. HAT-P-11 has unusually strong chromospheric emission compared to planet-hosting stars of similar effective temperature and rotation period, perhaps due to tides raised by its planet.
A Rigorous Derivation of Haff’s Law for a Periodic Two-Disk Fluid

We derive Haff’s cooling law for a periodic fluid consisting of two hard disks per unit cell by reducing it to a point particle moving inside a Sinai billiard with finite horizon with an inelastic collision rule. Indeed, our results also apply to general dispersing billiards with piece-wise smooth boundary with finite horizon and no cusps.
UKIRT-2017-BLG-001Lb: A Giant Planet Detected through the Dust

We report the discovery of a giant planet in event UKIRT-2017-BLG-001, detected by the United Kingdom Infrared Telescope (UKIRT) microlensing survey. The mass ratio between the planet and its host is q = 1.50^(+0.17)_(-0.14) x 10^(-3), about 1.5 times the Jupiter/Sun mass ratio. The event lies 0.°35 from the Galactic center and suffers from high extinction of A_K = 1.68. Therefore, it could be detected only by a near-infrared (NIR) survey. The field also suffers from large spatial differential extinction, which makes it difficult to estimate the source properties required to derive the angular Einstein radius. Nevertheless, we find evidence suggesting that the source is located in the far disk. If correct, this would be the first source star of a microlensing event to be identified as belonging to the far disk. We estimate the lens mass and distance using a Bayesian analysis to find that the planet's mass is 1.28^(+0.37)_(-0.44) M_J, and it orbits a 0.81^(+0.21)_(-0.27) M⊙ star at an instantaneous projected separation of 4.18^(+0.96)_(-0.88) au. The system is at a distance of 6.3^(+1.6)_(-2.1) kpc, and so likely resides in the Galactic bulge. In addition, we find a non-standard extinction curve in this field, in agreement with previous results toward high-extinction fields near the Galactic center.
A power series identity and Bessel-type integrals over unitary groups

In 2008, Lehner, Wettig, Guhr, and Wei conjectured a power series identity and showed that it implied a determinantal formula for a Bessel-type integral over the unitary supergroup. The integral is the supersymmetric extension of Bessel-type integrals over the unitary group appearing as partition functions in quantum chromodynamics. The identity is proved by interpreting both sides as the same unitary integral, which can be computed using the Cartan decomposition. An equivalent identity of Schur functions is also given and interpreted probabilistically in terms of random partitions.
Dialog without Dialog Data: Learning Visual Dialog Agents from VQA Data.

Can we develop visually grounded dialog agents that can efficiently adapt to new tasks without forgetting how to talk to people? Such agents could leverage a larger variety of existing data to generalize to new tasks, minimizing expensive data collection and annotation. In this work, we study a setting we call "Dialog without Dialog", which requires agents to develop visually grounded dialog models that can adapt to new tasks without language level supervision. By factorizing intention and language, our model minimizes linguistic drift after fine-tuning for new tasks. We present qualitative results, automated metrics, and human studies that all show our model can adapt to new tasks and maintain language quality. Baselines either fail to perform well at new tasks or experience language drift, becoming unintelligible to humans. Code has been made available at this https URL
Phase structure of non-commutative scalar field theories

Abstract We investigate the phase structure of non-commutative scalar field theories and find evidence for ordered phases which break translation invariance. A self-consistent one-loop analysis indicates that the transition into these ordered phases is first order. The phase structure and the existence of scaling limits provides an alternative to the structure of counter-terms in determining the renormalizability of non-commutative field theories. On the basis of the existence of a critical point in the closely related planar theory, we argue that there are renormalizable interacting non-commutative scalar field theories in dimensions two and above. We exhibit this renormalization explicitly in the large N limit of a non-commutative O ( N ) vector model.
Understanding the Quantum Computational Speed-up via De-quantisation

While it seems possible that quantum computers may allow for algorithms offering a computational speed-up over classical algorithms for some problems, the issue is poorly understood. We explore this computational speed-up by investigating the ability to de-quantise quantum algorithms into classical simulations of the algorithms which are as efficient in both time and space as the original quantum algorithms. The process of de-quantisation helps formulate conditions to determine if a quantum algorithm provides a real speed-up over classical algorithms. These conditions can be used to develop new quantum algorithms more effectively (by avoiding features that could allow the algorithm to be efficiently classically simulated) and to create new classical algorithms (by using features which have proved valuable for quantum algorithms). Results on many different methods of de-quantisations are presented, as well as a general formal definition of de-quantisation. De-quantisations employing higher-dimensional classical bits, as well as those using matrix-simulations, put emphasis on entanglement in quantum algorithms; a key result is that any algorithm in which the entanglement is bounded is de-quantisable. These methods are contrasted with the stabiliser formalism de-quantisations due to the Gottesman-Knill Theorem, as well as those which take advantage of the topology of the circuit for a quantum algorithm. The benefits and limits of the different methods are discussed, and the importance of utilising a range of techniques is emphasised. We further discuss some features of quantum algorithms which current de-quantisation methods do not cover and highlight several important open questions in the area.
TRACING WATER VAPOR and ICE during DUST GROWTH

The processes that govern the evolution of dust and water (in the form of vapor or ice) in protoplanetary disks are intimately connected. We have developed a model that simulates dust coagulation, dust dynamics (settling, turbulent mixing), vapor diffusion, and condensation/sublimation of volatiles onto grains in a vertical column of a protoplanetary disk. We employ the model to study how dust growth and dynamics influence the vertical distribution of water vapor and water ice in the region just outside the radial snowline. Our main finding is that coagulation (boosted by the enhanced stickiness of icy grains) and the ensuing vertical settling of solids results in water vapor being depleted, but not totally removed, from the region above the snowline on a timescale commensurate with the vertical turbulent mixing timescale. Depending on the strength of the turbulence and the temperature, the depletion can reach factors of up to ${\sim}50$ in the disk atmosphere. In our isothermal column, this vapor depletion results in the vertical snowline moving closer to the midplane (by up to 2 gas scale heights) and the gas-phase C/O ratio above the vertical snowline increasing. Our findings illustrate the importance of dynamical effects and the need for understanding coevolutionary dynamics of gas and solids in planet-forming environments.
Jupiter's Composition Suggests its Core Assembled Exterior to the N2 Snowline

Jupiter's atmosphere is enriched in C, N, S, P, Ar, Kr and Xe with respect to solar abundances by a factor of ~3. Gas Giant envelopes are mainly enriched through the dissolution of solids in the atmosphere, and this constant enrichment factor is puzzling since several of the above elements are not expected to have been in the solid phase in Jupiter's feeding zone; most seriously, Ar and the main carrier of N, N2, only condense at the very low temperatures, 21-26 K, associated with the outer solar nebula. We propose that a plausible solution to the enigma of Jupiter's uniform enrichment pattern is that Jupiter's core formed exterior to the N2 and Ar snowlines, beyond 30 au, resulting in a Solar composition core in all volatiles heavier than Ne. During envelope accretion and planetesimal bombardment, some of the core mixed in with the envelope causing the observed enrichment pattern. We show that this scenario naturally produces the observed atmosphere composition, even with substantial pollution from N-poor pebble and planetesimal accretion in Jupiter's final feeding zone. We note that giant core formation at large nebular radii is consistent with recent models of gas giant core formation through pebble accretion, which requires the core to form exterior to Jupiter's current location to counter rapid inward migration during the core and envelope formation process. If this scenario is common, gas giant core formation may account for many of the gaps observed in protoplanetary disks between 10s and 100 au.
Extended Depth of Field for High-Resolution Scanning Transmission Electron Microscopy

Aberration-corrected scanning transmission electron microscopes (STEMs) provide sub-Angstrom lateral resolution; however, the large convergence angle greatly reduces the depth of field. For microscopes with a small depth of field, information outside of the focal plane quickly becomes blurred and less defined. It may not be possible to image some samples entirely in focus. Extended depth-of-field techniques, however, allow a single image, with all areas in focus, to be extracted from a series of images focused at a range of depths. In recent years, a variety of algorithmic approaches have been employed for bright-field optical microscopy. Here, we demonstrate that some established optical microscopy methods can also be applied to extend the ∼ 6 nm depth of focus of a 100 kV 5th-order aberration-corrected STEM (α max = 33 mrad) to image Pt-Co nanoparticles on a thick vulcanized carbon support. These techniques allow us to automatically obtain a single image with all the particles in focus as well as a complimentary topography map.
THE DROP DURING LESS THAN 300 DAYS OF A DUSTY WHITE DWARF'S INFRARED LUMINOSITY

We report Spitzer/Infrared Array Camera photometry of WD J0959?0200, a white dwarf that displays excess infrared radiation from a disk, likely produced by a tidally disrupted planetesimal. We find that in 2010, the fluxes in both 3.6??m and 4.5??m decreased by ~35% in less than 300?days. The drop in the infrared luminosity is likely due to an increase of the inner disk radius from one of two scenarios: (1) a recent planetesimal impact; (2) instability in the circumstellar disk. The current situation is tantalizing; high-sensitivity, high-cadence infrared studies will be a new tool to study the interplay between a disk and its host white dwarf star.
Constraints on atmospheric charmed-meson production from IceCube

At very-high energies (100 TeV - 1 PeV), the small value of Bjorken-x (≤ 10 −3 − 10 −7 ) at which the parton distribution functions are evaluated makes the calculation of charm quark production very difficult. The charm quark has mass (~1.5±0.2 GeV) significantly above the Λ QCD scale (~200 MeV), and therefore its production is perturbatively calculable. However, the uncertainty in the data and the calculations cannot exclude some smaller non-perturbative contribution. To evaluate the prompt neutrino flux, one needs to know the charm production cross-section in pN -> c c X, and hadronization of charm particles. This contribution briefly discusses computation of prompt neutrino flux and presents the strongest limit on prompt neutrino flux from IceCube.
Investigation of nitrogen polar p-type doped GaN/AlxGa(1-x)N superlattices for applications in wide-bandgap p-type field effect transistors

In this study, the metal-organic chemical vapor deposition growth and electrical properties of N-polar modulation doped p-AlGaN/GaN superlattices (SLs) were investigated. Hole sheet charge density and mobility were studied as a function of the concentration of the p-type dopant Mg in the SL and the number of SL periods. Room temperature Hall measurements were carried out to determine the hole mobility and the sheet charge density. While the hole density increased with the increasing number of SL periods, the hole mobility was largely unaffected. Hole mobilities as high as 18 cm2/V s at a simultaneously high hole density of 6.5 × 1013 cm−2 were observed for N-polar SLs with a Mg modulation doping of 7.5 × 1018 cm−3. For comparable uniformly doped Ga-polar SL samples, a mobility of 11 cm2/V s was measured. These results confirm the presence of abrupt Mg doping profiles in N-polar p-type GaN/AlxGa(1−x)N SL, allowing the demonstration of SLs with properties comparable to those of state-of-the-art Ga-polar modulation doped AlGaN/GaN SLs grown using molecular beam epitaxy. The lowest sheet resistance in the GaN/AlGaN material system of 5 kΩ/◻ is also reported. Test-structure transistors were also fabricated to investigate the applicability of these SL structures, with the planar device resulting in a current of 5 mA/mm and a FinFET structure resulting in a current of over 100 mA/mm.In this study, the metal-organic chemical vapor deposition growth and electrical properties of N-polar modulation doped p-AlGaN/GaN superlattices (SLs) were investigated. Hole sheet charge density and mobility were studied as a function of the concentration of the p-type dopant Mg in the SL and the number of SL periods. Room temperature Hall measurements were carried out to determine the hole mobility and the sheet charge density. While the hole density increased with the increasing number of SL periods, the hole mobility was largely unaffected. Hole mobilities as high as 18 cm2/V s at a simultaneously high hole density of 6.5 × 1013 cm−2 were observed for N-polar SLs with a Mg modulation doping of 7.5 × 1018 cm−3. For comparable uniformly doped Ga-polar SL samples, a mobility of 11 cm2/V s was measured. These results confirm the presence of abrupt Mg doping profiles in N-polar p-type GaN/AlxGa(1−x)N SL, allowing the demonstration of SLs with properties comparable to those of state-of-the-art Ga-polar mod...
Weighted Local Estimates for Fractional Type Operators

In this note we prove the estimate \(M^{\sharp }_{0,s}(Tf)(x) \le c\,M_{\gamma } f(x)\) for general fractional type operators T, where \(M^{\sharp }_{0,s}\) is the local sharp maximal function and Mγ the fractional maximal function, as well as a local version of this estimate. This allows us to express the local weighted control of Tf by Mγf. Similar estimates hold for T replaced by fractional type operators with kernels satisfying Hormander-type conditions or integral operators with homogeneous kernels, and Mγ replaced by an appropriate maximal function MT. We also prove two-weight, \({L^{p}_{\text {\textit {v}}}}\)-\({L^{q}_{\text {\textit {w}}}}\) estimates for the fractional type operators described above for 1 < p < q < ∞ and a range of q. The local nature of the estimates leads to results involving generalized Orlicz-Campanato and Orlicz-Morrey spaces.
Deformed Hamiltonian Floer theory, capacity estimates and Calabi quasimorphisms

We develop a family of deformations of the differential and of the pair-of-pants product on the Hamiltonian Floer complex of a symplectic manifold .M;!/ which upon passing to homology yields ring isomorphisms with the big quantum homology of M . By studying the properties of the resulting deformed version of the Oh‐ Schwarz spectral invariants, we obtain a Floer-theoretic interpretation of a result of Lu which bounds the Hofer‐Zehnder capacity of M when M has a nonzero Gromov‐ Witten invariant with two point constraints, and we produce a new algebraic criterion for .M;!/ to admit a Calabi quasimorphism and a symplectic quasistate. This latter criterion is found to hold whenever M has generically semisimple quantum homology in the sense considered by Dubrovin and Manin (this includes all compact toric M ), and also whenever M is a point blowup of an arbitrary closed symplectic manifold.
Stability in the homology of congruence subgroups

The homology groups of many natural sequences of groups $$\{G_n\}_{n=1}^{\infty }$$ (e.g. general linear groups, mapping class groups, etc.) stabilize as $$n \rightarrow \infty $$ . Indeed, there is a well-known machine for proving such results that goes back to early work of Quillen. Church and Farb discovered that many sequences of groups whose homology groups do not stabilize in the classical sense actually stabilize in some sense as representations. They called this phenomena representation stability. We prove that the homology groups of congruence subgroups of $${{\mathrm{GL}}}_n(R)$$ (for almost any reasonable ring $$R$$ ) satisfy a strong version of representation stability that we call central stability. The definition of central stability is very different from Church-Farb’s definition of representation stability (it is defined via a universal property), but we prove that it implies representation stability. Our main tool is a new machine for proving central stability that is analogous to the classical homological stability machine.
Beyond minimal lepton-flavored Dark Matter

We consider a class of flavored dark matter (DM) theories where dark matter interacts with the Standard Model lepton fields at the renormalizable level. We allow for a general coupling matrix between the dark matter and leptons whose structure is beyond the one permitted by the minimal flavor violation (MFV) assumption. It is assumed that this is the only new source of flavor violation in addition to the Standard Model (SM) Yukawa interactions. The setup can be described by augmenting the SM flavor symmetry by an additional SU(3) χ , under which the dark matter χ transforms. This framework is especially phenomenologically rich, due to possible novel flavor-changing interactions which are not present within the more restrictive MFV framework. As a representative case study of this setting, which we call “beyond MFV” (BMFV), we consider Dirac fermion dark matter which transforms as a singlet under the SM gauge group and a triplet under SU(3) χ . The DM fermion couples to the SM lepton sector through a scalar mediator ϕ. Unlike the case of quark-flavored DM, we show that there is no $$ {\mathrm{\mathbb{Z}}}_3 $$ symmetry within either the MFV or BMFV settings which automatically stabilizes the lepton-flavored DM. We discuss constraints on this setup from flavor-changing processes, DM relic abundance as well as direct and indirect detections. We find that relatively large flavor-changing couplings are possible, while the dark matter mass is still within the phenomenologically interesting region below the TeV scale. Collider signatures which can be potentially searched for at the lepton and hadron colliders are discussed. Finally, we discuss the implications for decaying dark matter, which can appear if an additional stabilizing symmetry is not imposed.
Dynamics in stationary, non-globally hyperbolic spacetimes

Classically, the dynamics of a scalar field in a non-globally hyperbolic spacetime is ill-posed. Previously, a prescription was given for defining dynamics in static spacetimes in terms of a second-order operator acting on a Hilbert space defined on static slices. The present work extends this result by giving a similar prescription for defining dynamics in stationary spacetimes obeying certain mild assumptions. The prescription is defined in terms of a first-order operator acting on a different Hilbert space from that used in the static prescription. It preserves the important properties of the earlier prescription: the formal solution agrees with the Cauchy evolution within the domain of dependence, and smooth data of compact support always give rise to smooth solutions. In the static case, the first-order formalism agrees with the second-order formalism (using specifically the Friedrichs extension). Applications to field quantization are also discussed.
The Lerch zeta function II. Analytic continuation

This is the second of four papers that study algebraic and analytic structures associated with the Lerch zeta function. In this paper we analytically continue it as a function of three complex variables. We that it is well defined as a multivalued function on the manifold M equal to C^3 with the hyperplanes corresponding to integer values of the two variables a and c removed. We show that it becomes single valued on the maximal abelian cover of M. We compute the monodromy functions describing the multivalued nature of this function on M, and determine various of their properties.
A Product Formula for the Normalized Volume of Free Sums of Lattice Polytopes

The free sum is a basic geometric operation among convex polytopes. This note focuses on the relationship between the normalized volume of the free sum and that of the summands. In particular, we show that the normalized volume of the free sum of full-dimensional polytopes is precisely the product of the normalized volumes of the summands.
Coherent nonhelical shear dynamos driven by magnetic fluctuations at low Reynolds numbers

Nonhelical shear dynamos are studied with a particular focus on the possibility of coherent dynamo action. The primary results—serving as a follow up to the results of Squire & Bhattacharjee—pertain to the "magnetic shear-current effect" as a viable mechanism to drive large-scale magnetic field generation. This effect raises the interesting possibility that the saturated state of the small-scale dynamo could drive large-scale dynamo action, and is likely to be important in the unstratified regions of accretion disk turbulence. In this paper, the effect is studied at low Reynolds numbers, removing the complications of small-scale dynamo excitation and aiding analysis by enabling the use of quasi-linear statistical simulation methods. In addition to the magnetically driven dynamo, new results on the kinematic nonhelical shear dynamo are presented. These illustrate the relationship between coherent and incoherent driving in such dynamos, demonstrating the importance of rotation in determining the relative dominance of each mechanism.
Theoretical Prediction of Enhanced Thermopower in n-Doped Si/Ge Superlattices Using Effective Mass Approximation

We analyze the cross-plane miniband transport in n-doped [001] silicon (Si)/germanium (Ge) superlattices using an effective mass approximation (EMA) approach that correctly accounts for the indirect nature of the Si and Ge band gaps. Direct-gap based EMA has been employed to investigate the electronic properties of these superlattices; however, that does not accurately predict transport properties. We use the Boltzmann transport equation framework in combination with the EMA band analysis, and predict that significant improvement in the thermopower (S) of n-doped Si/Ge superlattices can be achieved by controlling the lattice strain environment in these heterostructured materials. We illustrate that a remarkable degree of tunability in the Seebeck coefficient (S) can be attained by growing the superlattices on various substrates and/or varying the periods and the composition of the superlattices. Our calculations show up to $$\sim 3.2$$ -fold Seebeck enhancement in Si/Ge [001] superlattices over bulk silicon in the high-doping regime, breaking the Pisarenko relation. And the thermopower modulations lead to an increase in the power factor, $$S^2\sigma $$ , by up to 20%, where $$\sigma $$ is the electronic conductivity. Our approach is generally applicable to other superlattice systems, such as to investigate the electronic transport properties of two-dimensional nanowire and three-dimensional nanodot superlattices. A material with high S potentially improves the energy conversion efficiency of thermoelectric applications, and additionally is highly valuable in various Seebeck metrology techniques including thermal, flow, radiation, and chemical sensing applications. We anticipate that the ideas presented here will have a strong impact in controlling electronic transport in various thermoelectric, optoelectronic, and quantum-enhanced heterostructured materials applications.
Crustal Heating and Quiescent Emission from Transiently Accreting Neutron Stars

Nuclear reactions occurring at densities ≈ 1012 g cm-3 in the crust of a transiently accreting neutron star efficiently maintain the core at a temperature ≈ (5-10)×107 K. When accretion halts, the envelope relaxes to a thermal equilibrium set by the flux from the hot core, as if the neutron star were newly born. For the time-averaged accretion rates (10-10 M☉ yr-1) typical of low-mass X-ray transients, standard neutrino cooling is unimportant and the core thermally reradiates the deposited heat. The resulting luminosity is ~5×1032-5×1033 ergs s-1 and agrees with many observations of transient neutron stars in quiescence. Confirmation of this mechanism would strongly constrain rapid neutrino cooling mechanisms for neutron stars (e.g., a pion condensate). Thermal emission had previously been dismissed as a predominant source of quiescent emission since blackbody spectral fits implied an emitting area much smaller than a neutron star's surface. However, as with thermal emission from radio pulsars, fits with realistic emergent spectra will imply a substantially larger emitting area. Other emission mechanisms, such as accretion or a pulsar shock, can also operate in quiescence and generate intensity and spectral variations over short timescales. Indeed, quiescent accretion may produce gravitationally redshifted metal photoionization edges in the quiescent spectra (detectable with AXAF and XMM). We discuss past observations of Aql X-1 and note that the low-luminosity (less than 1034 ergs s-1) X-ray sources in globular clusters and the Be star/X-ray transients are excellent candidates for future study.
Karl Pearson’s Theoretical Errors and the Advances They Inspired

Karl Pearson played an enormous role in determining the content and organization of statistical research in his day, through his research, his teaching, his establishment of laboratories, and his initiation of a vast publishing program. His technical contributions had initially and continue today to have a profound impact upon the work of both applied and theoretical statisticians, partly through their inadequately acknowledged influence upon Ronald A. Fisher. Particular attention is drawn to two of Pearson’s major errors that nonetheless have left a positive and lasting impression upon the statistical world.
Scheduling and calibration strategy for continuous radio monitoring of 1700 sources every three days

The Owens Valley Radio Observatory 40 meter telescope is currently monitoring a sample of about 1700 blazars every three days at 15 GHz, with the main scientific goal of determining the relation between the variability of blazars at radio and gamma-rays as observed with the Fermi Gamma-ray Space Telescope. The time domain relation between radio and gamma-ray emission, in particular its correlation and time lag, can help us determine the location of the high-energy emission site in blazars, a current open question in blazar research. To achieve this goal, continuous observation of a large sample of blazars in a time scale of less than a week is indispensable. Since we only look at bright targets, the time available for target observations is mostly limited by source observability, calibration requirements and slewing of the telescope. Here I describe the implementation of a practical solution to this scheduling, calibration, and slewing time minimization problem. This solution combines ideas from optimization, in particular the traveling salesman problem, with astronomical and instrumental constraints. A heuristic solution using well established optimization techniques and astronomical insights particular to this situation, allow us to observe all the sources in the required three days cadence while obtaining reliable calibration of the radio flux densities. Problems of this nature will only be more common in the future and the ideas presented here can be relevant for other observing programs.