cssi/SciSciGPT-SciSciNet huggingface dataset:
The Complete Spectral Catalog of Bright BATSE Gamma-Ray Bursts

We present a systematic spectral analysis of 350 bright gamma-ray bursts (GRBs) observed with the Burst and Transient Source Experiment (BATSE; ~30 keV-2 MeV) with high temporal and spectral resolution. Our sample was selected from the complete set of 2704 BATSE GRBs based on their energy fluence or peak photon flux values to assure good statistics and included 17 short GRBs. To obtain well-constrained spectral parameters, several photon models were used to fit each spectrum. We compared spectral parameters resulting from the fits using different models, and the spectral parameters that best represent each spectrum were statistically determined, taking into account the parameterization differences among the models. A thorough analysis was performed on 350 time-integrated and 8459 time-resolved burst spectra, and the effects of integration times in determining the spectral parameters were explored. Using the results, we studied correlations among spectral parameters and their evolution pattern within each burst. The resulting spectral catalog is the most comprehensive study of spectral properties of GRB prompt emission to date and is available electronically from the High-Energy Astrophysics Science Archive Research Center (HEASARC). The catalog provides reliable constraints on particle acceleration and emission mechanisms in GRBs.
Resonant tunneling in a system with correlated pure point spectrum

We consider resonant tunneling between disorder localized states in a potential energy displaying perfect correlations over large distances. The phenomenon described here may be of relevance to models exhibiting many-body localization. Furthermore, in the context of single particle operators, our examples demonstrate that exponential resolvent localization does not imply exponential dynamical localization for random Schrodinger operators with correlated potentials.We consider resonant tunneling between disorder localized states in a potential energy displaying perfect correlations over large distances. The phenomenon described here may be of relevance to models exhibiting many-body localization. Furthermore, in the context of single particle operators, our examples demonstrate that exponential resolvent localization does not imply exponential dynamical localization for random Schrodinger operators with correlated potentials.
A Khintchine-type theorem for affine subspaces

We show that affine subspaces of Euclidean space are of Khintchine type for divergence under certain multiplicative Diophantine conditions on the parameterizing matrix. This provides evidence towar...
The Feasibility of Using Black Widow Pulsars in Pulsar Timing Arrays for Gravitational Wave Detection

In the past five years, approximately one-third of the 65 pulsars discovered by radio observations of Fermi unassociated sources are black widow pulsars (BWPs). BWPs are binary millisecond pulsars with companion masses ranging from 0.01 to 0.1 which often exhibit radio eclipses. The bloated companions in BWP systems exert small torques on the system causing the orbit to change on small but measurable timescales. Because adding parameters to a timing model reduces sensitivity to a gravitational wave (GW) signal, the need to fit many orbital frequency derivatives (OFDs) to the timing data is potentially problematic for using BWPs to detect GWs with pulsar timing arrays (PTAs). Using simulated data with up to four OFDs, we show that fitting for OFDs absorbs less than 5% of the low frequency spectrum expected from a stochastic GW background signal. Furthermore, this result does not change with orbital period. Therefore, we suggest that if timing systematics can be accounted for by modeling OFDs and is not caused by spin frequency noise, PTA experiments should include BWPs in their arrays.
Distinguishing dark matter from unresolved point sources in the Inner Galaxy with photon statistics

Data from the Fermi Large Area Telescope suggests that there is an extended excess of GeV gamma-ray photons in the Inner Galaxy. Identifying potential astrophysical sources that contribute to this excess is an important step in verifying whether the signal originates from annihilating dark matter. In this paper, we focus on the potential contribution of unresolved point sources, such as millisecond pulsars (MSPs). We propose that the statistics of the photons—in particular, the flux probability density function (PDF) of the photon counts below the point-source detection threshold—can potentially distinguish between the dark-matter and point-source interpretations. We calculate the flux PDF via the method of generating functions for these two models of the excess. Working in the framework of Bayesian model comparison, we then demonstrate that the flux PDF can potentially provide evidence for an unresolved MSP-like point-source population.
LEPTON PHOTON SYMPOSIUM 2005: SUMMARY AND OUTLOOK

Lepton Photon 2005 told the saga of the Standard Model which is still exhilarating because it leaves all questions of consequence unanswered.
A Late-type L Dwarf at 11 pc Hiding in the Galactic Plane Characterized Using Gaia DR2

We report on the characterization of a nearby (d = 11.2 pc) ultracool L dwarf (WISE J192512.78+070038.8; hereafter W1925) identified as a faint (G = 20.0) high proper motion (0.22"/yr) object in the Gaia Data Releases 1 and 2. A Palomar/TripleSpec near-infrared spectrum of W1925 confirms a previously estimated photometric L7 spectral type by Scholz et al. 2018, and its infrared colors and absolute magnitudes are consistent with a single object of this type. We constructed a spectral energy distribution using the Gaia parallax, literature photometry and near infrared spectrum and find a luminosity log(Lbol/LSun) = -4.443+/-0.008. Applying evolutionary models, we infer that W1925 is likely a 53+/-18 MJup brown dwarf with Teff=1404+/-71 K and log g =5.1+/-0.4 dex (cgs). While W1925 was detected in both the 2MASS and WISE infrared sky surveys, it was not detected in photographic plate sky surveys. Its combination of extreme optical-infrared colors, high proper motion, and location near the crowded Galactic plane (b = -4.2 deg) likely contributed to it having evaded detection in pre-Gaia surveys.
Understanding and Controlling the Work Function of Perovskite Oxides Using Density Functional Theory

Perovskite oxides containing transition metals are promising materials in a wide range of electronic and electrochemical applications. However, neither their work function values nor an understanding of their work function physics have been established. Here, the work function trends of a series of perovskite (ABO3 formula) materials using density functional theory are predicted, and show that the work functions of (001)-terminated AO- and BO2-oriented surfaces can be described using concepts of electronic band filling, bond hybridization, and surface dipoles. The calculated range of AO (BO2) work functions are 1.60–3.57 eV (2.99–6.87 eV). An approximately linear correlation (R2 between 0.77 and 0.86 is found, depending on surface termination) between work function and position of the oxygen 2p band center, which correlation enables both understanding and rapid prediction of work function trends. Furthermore, SrVO3 is identified as a stable, low work function, highly conductive material. Undoped (Ba-doped) SrVO3 has an intrinsically low AO-terminated work function of 1.86 eV (1.07 eV). These properties make SrVO3 a promising candidate material for a new electron emission cathode for application in high power microwave devices, and as a potential electron emissive material for thermionic energy conversion technologies.
Meson Electro-/Photo-Production from QCD

I present the calculation of the $$\pi ^+\gamma ^\star \rightarrow \pi ^+\pi ^0$$ transition amplitude from quantum chromodynamics performed by the Hadron Spectrum Collaboration. The amplitude is determined for a range of values of the photon virtuality and the final state energy. One observes a clear dynamical enhancement due to the presence of the $$\rho $$ resonance. By fitting the transition amplitude and analytically continuing it onto the $$\rho $$ -pole, the $$\rho \rightarrow \pi \gamma ^\star $$ form factor is obtained. This exploratory calculation, performed using lattice quantum chromodynamics, constitutes the very first determination of an electroweak decay of a hadronic resonance directly from the fundamental theory of quarks and gluons. In this talk, I highlight some of the necessary steps that made this calculation possible, placing emphasis on recently developed formalism. Finally, I discuss the status and outlook of the field for the study of $$N\gamma ^\star \rightarrow N^\star \rightarrow N\pi $$ transitions.
Cuprates and center vortices: A QCD confinement mechanism in a high-Tc context

Abstract It is suggested that the center vortex confinement mechanism, familiar in hadronic physics, may have some relevance to high-T c phenomena. We focus specifically on the transition from the superconducting phase to the pseudogap phase. There is evidence of a vortex liquid in the latter phase, in which the pairing responsible for superconductivity still exists, but superconductivity itself does not. An analogy, drawn from particle physics, may be the Higgs to confinement phase transition in an SU(N) gauge theory, where the confined phase is a vortex liquid, and the Higgs phase is a phase of a broken global Z N symmetry. We illustrate this idea with numerical simulations of a spatially asymmetric U(1) gauge-Higgs model, with lattice artifact monopoles suppressed. We show the existence of a Higgs (superconductor) to confinement (vortex liquid) phase, explicitly identifying vortices in lattice configurations generated in the confined phase, and showing that they produce an area-law falloff in planar Wilson loops, which may be measurable experimentally. The superconducting phase is a phase of broken global Z 2 symmetry.
BenchPress: Analyzing Android App Vulnerability Benchmark Suites

In recent years, various benchmark suites have been developed to evaluate the efficacy of Android security analysis tools. Tool developers often choose such suites based on the availability and popularity of suites and not on their characteristics and relevance due to the lack of information about them. In this context, based on a recent effort, we empirically evaluated four Android-specific benchmark suites: DroidBench, Ghera, ICCBench, and UBCBench. For each benchmark suite, we identified the APIs used by the suite that were discussed on Stack Overflow in the context of Android app development and measured the usage of these APIs in a sample of 227K real-world apps (coverage). We also identified security-related APIs used in real-world apps but not in any of the above benchmark suites to assess the opportunities to extend benchmark suites (gaps).
SO(3)-DONALDSON INVARIANTS OF CP 2 AND MOCK THETA FUNCTIONS

We compute the Moore‐Witten regularized u‐plane integral on CP 2 , and we confirm the conjecture that it is the generating function for the SO.3/‐Donaldson invariants of CP 2 . We also derive generating functions for the SO.3/‐Donaldson invariants with 2Nf massless monopoles using the geometry of certain rational elliptic surfaces (Nf 2f0;2;3;4g), and we show that the partition function for Nf D 4 is nearly modular. Our results rely heavily on the theory of mock theta functions and harmonic Maass forms (for example, see Ono [40]). 57R57
Cohomology rings for quantized enveloping algebras

We compute the structure of the cohomology ring for the quantized enveloping algebra (quantum group) $U_q$ associated to a finite-dimensional simple complex Lie algebra $\mathfrak{g}$. We show that the cohomology ring is generated as an exterior algebra by homogeneous elements in the same odd degrees as generate the cohomology ring for the Lie algebra $\mathfrak{g}$. Partial results are also obtained for the cohomology rings of the non-restricted quantum groups obtained from $U_q$ by specializing the parameter $q$ to a non-zero value $\epsilon \in \mathbb{C}$.
Geometry of the set of synchronous quantum correlations

We provide a complete geometric description of the set of synchronous quantum correlations for the three-experiment two-outcome scenario. We show that these correlations form a closed set. Moreover, every correlation in this set can be realized using projection valued measures on a Hilbert space of dimension no more than 16.
On the Perturbations of Viscous Rotating Newtonian Fluids

The perturbations of weakly viscous, barotropic, non-self-gravitating Newtonian rotating fluids are analyzed via a single partial differential equation. The results are then used to find an expression for the viscosity-induced normal-mode complex eigenfrequency shift, with respect to the case of adiabatic perturbations. However, the effects of viscosity are assumed to have been incorporated in the unperturbed (equilibrium) model. This paper is an extension of the normal-mode formalism developed by Ipser & Lindblom for adiabatic pulsations of purely rotating perfect fluids. The formulae derived are readily applicable to the perturbations of thin and thick accretion disks. We provide explicit expressions for thin disks, employing results from previous relativistic analyses of adiabatic normal modes of oscillation. In this case, we find that viscosity causes the fundamental p- and g-modes to grow, while the fundamental c-mode could have either sign of the damping rate.
Thermal theory of aluminum particle ignition in continuum, free-molecular, and transition heat transfer regimes

Most studies on nano- and micro- sized aluminum particle ignition have been focused on the processes occurring inside particles. In the current paper, thermal ignition of an aluminum particle in the air is simulated with different heat transfer models: continuum, free-molecular, and Fuchs model. A single parabolic oxidation law is assumed in the particle size range from nano- to millimeter diameters. A particle is considered ignited when it reaches the oxide melting point. The criterion defining the limits of validity for each model is the ratio of continuum and free-molecular heat transfer rates. The dependence of ignition temperature Ti on the particle size is in qualitative agreement with the experimental trends: Ti can have values in the range of 700–1500 K for nanoparticles due to the dominating contribution of a free-molecular heat transfer, and sharp growth of Ti with the particle size in the range of 1–100 μm diameter is due to the transitional character of heat transfer. For small values of the accommodation coefficient, ignition may occur in the critical ignition mode with the thermal runaway. The results suggest the importance of non-continuous heat transfer and, in particular, energy accommodation in ignition of nano- and micro- sized particles.Most studies on nano- and micro- sized aluminum particle ignition have been focused on the processes occurring inside particles. In the current paper, thermal ignition of an aluminum particle in the air is simulated with different heat transfer models: continuum, free-molecular, and Fuchs model. A single parabolic oxidation law is assumed in the particle size range from nano- to millimeter diameters. A particle is considered ignited when it reaches the oxide melting point. The criterion defining the limits of validity for each model is the ratio of continuum and free-molecular heat transfer rates. The dependence of ignition temperature Ti on the particle size is in qualitative agreement with the experimental trends: Ti can have values in the range of 700–1500 K for nanoparticles due to the dominating contribution of a free-molecular heat transfer, and sharp growth of Ti with the particle size in the range of 1–100 μm diameter is due to the transitional character of heat transfer. For small values of the a...
PyCDFT: A Python package for constrained density functional theory

We present PyCDFT, a Python package to compute diabatic states using constrained density functional theory (CDFT). PyCDFT provides an object-oriented, customizable implementation of CDFT, and allows for both single-point self-consistent-field calculations and geometry optimizations. PyCDFT is designed to interface with existing density functional theory (DFT) codes to perform CDFT calculations where constraint potentials are added to the Kohn-Sham Hamiltonian. Here, we demonstrate the use of PyCDFT by performing calculations with a massively parallel first-principles molecular dynamics code, Qbox, and we benchmark its accuracy by computing the electronic coupling between diabatic states for a set of organic molecules. We show that PyCDFT yields results in agreement with existing implementations and is a robust and flexible package for performing CDFT calculations. The program is available at https://dx.doi.org/10.5281/zenodo.3821097.
High-speed imaging of transition from fluid breakup to phase explosion in electric explosion of tungsten wires in air

High-speed visible imaging of sub-microsecond electric explosion of wires at the low specific energy deposition threshold reveals three distinct modes of wire failure as capacitor charge voltage and energy deposition are increased. For 100 μm diameter gold-plated tungsten wires of 2 cm length, deposited energies of 1.9 eV/atom produce a liquid column that undergoes hydrodynamic breakup into droplets with radii of the order of wire diameter on timescales of 200 μs. Instability growth, column breakup, and droplet coalescence follow classical Rayleigh–Plateau predictions for instability of the viscous fluid column. Above a deposited energy of 3.2 eV/atom, wires are seen to abruptly transition to an expanding mixture of micrometer scale liquid-droplets and vapor within one frame (less than 3.33 μs), which has been termed “phase explosion” in the literature. Between these two limits, at a deposited energy of 2.5 eV/atom, the wire radius remains unchanged for the first 10 μs before the onset of a rapid expansion and disintegration that resembles homogenous nucleation of mechanically unstable bubbles. Thermodynamic calculations are presented, which separate cases by temperature obtained during heating: below the boiling point, near the boiling point, and exceeding the boiling point.
Hubble Space Telescope Proper Motions along the Sagittarius Stream. I. Observations and Results for Stars in Four Fields

We present a multi-epoch Hubble Space Telescope (HST) study of stellar proper motions (PMs) for four fields spanning 200° along the Sagittarius (Sgr) stream: one trailing arm field, one field near the Sgr dwarf spheroidal tidal radius, and two leading arm fields. We determine absolute PMs of dozens of individual stars per field, using established techniques that use distant background galaxies as the stationary reference frame. Stream stars are identified based on combined color–magnitude diagram and PM information. The results are broadly consistent with the few existing PM measurements for the Sgr galaxy and the trailing arm. However, our new results provide the highest PM accuracy for the stream to date, the first PM measurements for the leading arm, and the first PM measurements for individual stream stars; we also serendipitously determine the PM of the globular cluster NGC 6652. In the trailing-arm field, the individual PMs allow us to kinematically separate trailing-arm stars from leading-arm stars that are 360° further ahead in their orbit. Also, in three of our fields we find indications that two distinct kinematical components may exist within the same arm and wrap of the stream. Qualitative comparison of the HST data to the predictions of the Law & Majewski and Penarrubia et al. N-body models show that the PM measurements closely follow the predicted trend with Sgr longitude. This provides a successful consistency check on the PM measurements, as well as on these N-body approaches (which were not tailored to fit any PM data).
In the Crosshair: Astrometric Exoplanet Detection with WFIRST's Diffraction Spikes

WFIRST will conduct a coronagraphic program of characterizing the atmospheres of planets around bright nearby stars. When observed with the WFIRST Wide Field Camera, these stars will saturate the detector and produce very strong diffraction spikes. In this paper, we forecast the astrometric precision that WFIRST can achieve by centering on the diffraction spikes of highly saturated stars. This measurement principle is strongly facilitated by the WFIRST H4RG detectors, which confine excess charges within the potential well of saturated pixels. By adopting a simplified analytical model of the diffraction spike caused by a single support strut obscuring the telescope aperture, integrated over the WFIRST pixel size, we predict the performance of this approach with the Fisher-matrix formalism. We discuss the validity of the model and find that 10 ${\mu}$as astrometric precision is achievable with a single 100 s exposure of a R = 6 or a J = 5 star. We discuss observational limitations from the optical distortion correction and pixel-level artifacts, which need to be calibrated at the level of 10 - 20 ${\mu}$as so as to not dominate the error budget. To suppress those systematics, we suggest a series of short exposures, dithered by at least several hundred pixels, to reach an effective per-visit astrometric precision of better than 10 ${\mu}$as. If this can be achieved, a dedicated WFIRST GO program will be able to detect Earth-mass exoplanets with orbital periods of 1 yr around stars within a few pc as well as Neptune-like planets with shorter periods or around more massive or distant stars. Such a program will also enable mass measurements of many anticipated direct-imaging exoplanet targets of the WFIRST coronagraph and a "starshade" occulter.
FURTHER INVESTIGATION OF THE TIME DELAY, MAGNIFICATION RATIOS, AND VARIABILITY IN THE GRAVITATIONAL LENS 0218+357

High-precision VLA flux density measurements for the lensed images of 0218+357 yield a time delay of 10.1 days (95% confidence). This is consistent with independent measurements carried out at the same epoch by Biggs and colleagues in 1999, lending confidence to the robustness of the time delay measurement. However, since both measurements make use of the same features in the light curves, it is possible that the effects of unmodeled processes, such as scintillation or microlensing, are biasing both time delay measurements in the same way. Our time delay estimates result in confidence intervals that are somewhat larger than those of Biggs et al., probably because we adopt a more general model of the source variability, allowing for constant and variable components. When considered in relation to the lens mass model of Biggs et al., our best-fit time delay implies a Hubble constant of H0 = 71 km s-1 Mpc-1 for ?0 = 1 and ?0 = 0 (95% confidence; filled beam). This confidence interval for H0 does not reflect systematic error, which may be substantial, as a result of uncertainty in the position of the lens galaxy. We also measure the flux ratio of the variable components of 0218+357, a measurement of a small region that should more closely represent the true lens magnification ratio. We find ratios of 3.2 (95% confidence; 8 GHz) and 4.3 (15 GHz). Unlike the reported flux ratios on scales of 01, these ratios are not significantly different. We investigate the significance of apparent differences in the variability properties of the two images of the background active galactic nucleus. We conclude that the differences are not significant and that time series much longer than our 100 day time series will be required to investigate propagation effects in this way.
THE TIES THAT BIND? GALACTIC MAGNETIC FIELDS AND RAM PRESSURE STRIPPING

One process affecting gas-rich cluster galaxies is ram pressure stripping (RPS), i.e., the removal of galactic gas through direct interaction with the intracluster medium (ICM). Galactic magnetic fields may have an important impact on the stripping rate and tail structure. We run the first magnetohydrodynamic (MHD) simulations of RPS that include a galactic magnetic field, using 159 pc resolution throughout our entire domain in order to resolve mixing throughout the tail. We find very little difference in the total amount of gas removed from the unmagnetized and magnetized galaxies, although a magnetic field with a radial component will initially accelerate stripped gas more quickly. In general, we find that magnetic fields in the disk lead to slower velocities in the stripped gas near the disk and faster velocities farther from the disk. We also find that magnetic fields in the galactic gas lead to larger unmixed structures in the tail. Finally, we discuss whether ram pressure stripped tails can magnetize the ICM. We find that the total magnetic energy density grows as the tail lengthens, likely through turbulence. There are μG-strength fields in the tail in all of our MHD runs, which survive to at least 100 kpc from themore » disk (the edge of our simulated region), indicating that the area-filling factor of magnetized tails in a cluster could be large.« less
On notions of determinism in topological dynamics

We examine the relations between topological entropy, invertibility, and prediction in topological dynamics. We show that topological determinism in the sense of Kaminsky, Siemaszko, and Szymanski imposes no restriction on invariant measures except zero entropy. Also, we develop a new method for relating topological determinism and zero entropy, and apply it to obtain a multidimensional analog of this theory. We examine prediction in symbolic dynamics and show that while the condition that each past admits a unique future only occurs in finite systems, the condition that each past has a bounded number of futures imposes no restriction on invariant measures except zero entropy. Finally, we give a negative answer to a question of Eli Glasner by constructing a zero-entropy system with a globally supported ergodic measure in which every point has multiple preimages.
$(SL(N),q)$-opers, the $q$-Langlands correspondence, and quantum/classical duality

A special case of the geometric Langlands correspondence is given by the relationship between solutions of the Bethe ansatz equations for the Gaudin model and opers-connections on the projective line with extra structure. In this paper, we describe a deformation of this correspondence for $${{\,\mathrm{\mathrm {SL}}\,}}(N)$$ . We introduce a difference equation version of opers called q-opers and prove a q-Langlands correspondence between nondegenerate solutions of the Bethe ansatz equations for the XXZ model and nondegenerate twisted q-opers with regular singularities on the projective line. We show that the quantum/classical duality between the XXZ spin chain and the trigonometric Ruijsenaars–Schneider model may be viewed as a special case of the q-Langlands correspondence. We also describe an application of q-opers to the equivariant quantum K-theory of the cotangent bundles to partial flag varieties.
Jamming Based on an Ephemeral Key to Obtain Everlasting Security in Wireless Environments

Secure communication over a wiretap channel is considered in the disadvantaged wireless environment, where the eavesdropper channel is (possibly much) better than the main channel. We present a method to exploit inherent vulnerabilities of the eavesdroppers receiver to obtain everlasting secrecy. Based on an ephemeral cryptographic key pre-shared between the transmitter Alice and the intended recipient Bob, a random jamming signal is added to each symbol. Bob can subtract the jamming signal before recording the signal, while the eavesdropper Eve is forced to perform these non-commutative operations in the opposite order. Thus, information-theoretic secrecy can be obtained, hence achieving the goal of converting the vulnerable “cheap” cryptographic secret key bits into “valuable” information-theoretic (i.e., everlasting) secure bits. We evaluate the achievable secrecy rates for different settings, and show that, even when the eavesdropper has perfect access to the output of the transmitter (albeit through an imperfect analog-to-digital converter), the method can still achieve a positive secrecy rate. Next we consider a wideband system, where Alice and Bob perform frequency hopping in addition to adding the random jamming to the signal, and we show the utility of such an approach even in the face of substantial eavesdropper hardware capabilities.
The Dependence of Subhalo Abundance on Halo Concentration

Hierarchical structure formation implies that the number of subhalos within a dark matter halo depends not only on halo mass, but also on the formation history of the halo. This dependence on the formation history, which is highly correlated with halo concentration, can account for the super-Poissonian scatter in subhalo occupation at a fixed halo mass that has been previously measured in simulations. Here we propose a model to predict the subhalo abundance function for individual host halos that incorporates both halo mass and concentration. We combine results of cosmological simulations with a new suite of zoom-in simulations of Milky Way-mass halos to calibrate our model. We show that the model can successfully reproduce the mean and the scatter of subhalo occupation in these simulations. The implications of this correlation between subhalo abundance and halo concentration are further investigated. We also discuss cases in which inferences about halo properties can be affected if this correlation between subhalo abundance and halo concentration is ignored; in these cases, our model would give a more accurate inference. We propose that with future deep surveys, satellite occupation in the low-mass regime can be used to verify the existence of halo assembly bias.
Supermassive black holes in spiral galaxies

We have embarked in an HST program to determine the masses of black holes in spiral galaxies directly by measuring the line emission arising from an extended accretion disk. For each of the galaxies in our sample we have measured the rotation curve and determined the mass distribution within the inner 5-50 pc. We have modeled the stellar mass component using the photometric data from existing HST images and using both data sets we have derived the masses of the black holes in each galaxy. These results will be very important in clarifying the role of the black hole in powering the AGN, will shed light into the effectiveness of the accretion mechanisms and finally will be important in addressing the fundamental issue of unification for Seyfert 1 and Seyfert 2 galaxies.
Evolution profiles and functional equations

Time evolution is formulated and discussed in the framework of Schroder's functional equation. The proposed method yields smooth, continuous dynamics without the prior need for local propagation equations.
Dynamical Evidence for a Late Formation of Saturn's Moons

We explore the past evolution of Saturn's moons using direct numerical integrations. We find that the past Tethys–Dione 3:2 orbital resonance predicted in standard models likely did not occur, implying that the system is less evolved than previously thought. On the other hand, the orbital inclinations of Tethys, Dione, and Rhea suggest that the system did cross the Dione–Rhea 5:3 resonance, which is closely followed by a Tethys–Dione secular resonance. A clear implication is that either the moons are significantly younger than the planet or their tidal evolution must be extremely slow (Q > 80,000). As an extremely slow evolving system is incompatible with intense tidal heating of Enceladus, we conclude that the moons interior to Titan are not primordial, and we present a plausible scenario for the system's recent formation. We propose that the midsized moons re-accreted from a disk about 100 Myr ago, during which time Titan acquired its significant orbital eccentricity. We speculate that this disk has formed through orbital instability and massive collisions involving the previous generation of Saturn's midsized moons. We identify the solar evection resonance perturbing a pair of midsized moons as the most likely trigger of such an instability. This scenario implies that most craters on the moons interior to Titan must have been formed by planetocentric impactors.
THE VERY FAINT END OF THE UV LUMINOSITY FUNCTION OVER COSMIC TIME: CONSTRAINTS FROM THE LOCAL GROUP FOSSIL RECORD

We present a new technique to estimate the evolution of the very faint end of the UV luminosity function (LF) out to z ∼ 5. Measured star formation histories (SFHs) from the fossil record of Local Group (LG) galaxies are used to reconstruct the LF down to M {sub UV} ∼–5 at z ∼ 5 and M {sub UV} ∼–1.5 at z < 1. Such faint limits are well beyond the current observational limits and are likely to remain beyond the limits of next-generation facilities. The reconstructed LFs, when combined with direct measurements of the LFs at higher luminosity, are well-fit by a standard Schechter function with no evidence of a break to the faintest limits probed by this technique. The derived faint-end slope, α, steepens from ≈ – 1.2 at z < 1 to ≈ – 1.6 at 4 < z < 5. We test the effects of burstiness in the SFHs and find the recovered LFs to be only modestly affected. Incompleteness corrections for the faintest LG galaxies and the (unlikely) possibility of significant luminosity-dependent destruction of dwarf galaxies between high redshift and the present epoch are important uncertainties. These and other uncertainties can be mitigated with moremore » detailed modeling and future observations. The reconstructed faint end LF from the fossil record can therefore be a powerful and complementary probe of the high-redshift faint galaxies believed to play a key role in the reionization of the universe.« less
The Poles of Igusa Zeta Integrals and the Unextendability of Semi-invariant Distributions

We investigate the relationship between the poles of Igusa zeta integrals and the unextendability of semi-invariant distributions. Under some algebraic conditions, we obtain an upper bound for the order of the poles of Igusa zeta integral, and by using the order of the poles we give a criterion on the unextendability of semi-invariant distributions. A key ingredient of our method is the idea of generalized semi-invariant distributions.
EXTENSIONS OF JOHNSON'S AND MORITA'S HOMOMORPHISMS THAT MAP TO FINITELY GENERATED ABELIAN GROUPS

We extend each higher Johnson homomorphism to a crossed homomorphism from the automorphism group of a finite-rank free group to a finite-rank abelian group. We also extend each Morita homomorphism to a crossed homomorphism from the mapping class group of once-bounded surface to a finite-rank abelian group. This improves on the author's previous results [5]. To prove the first result, we express the higher Johnson homomorphisms as coboundary maps in group cohomology. Our methods involve the topology of nilpotent homogeneous spaces and lattices in nilpotent Lie algebras. In particular, we develop a notion of the "polynomial straightening" of a singular homology chain in a nilpotent homogeneous space.
Towards digital engineering: the advent of digital systems engineering

Digital engineering, the digital transformation of engineering to leverage digital technologies, is coming globally. This paper explores digital systems engineering, which aims at developing theory, methods, models, and tools to support digital engineering practice. A critical task is to digitalise engineering artefacts, thus enabling information and model sharing, traceability, and accountability across platforms, across lifecycle, and across domains. We identify challenges and enabling digital technologies; analyse the transition from traditional engineering to digital engineering; define core concepts, including digitalisation, unique identification, digitalised artefacts, digital augmentation, and others; present a big picture of digital systems engineering in four levels: vision, strategy, action, and foundation; briefly discuss each of main areas of research. Digitalisation enables fast infusing and leveraging novel digital technologies; unique identification enables information traceability and accountability in lifecycle; provenance enables tracing dependency relations among engineering artefacts, supporting model reproducibility and replicability, and helping with trustworthiness evaluation of digital artefacts.
BATSE Gamma-Ray Burst Line Search. V. Probability of Detecting a Line in a Burst

The physical importance of the apparent discrepancy between the detections by pre-BATSE missions of absorption lines in gamma-ray burst spectra and the absence of a BATSE line detection necessitates a statistical analysis of this discrepancy. This analysis requires a calculation of the probability that a line, if present, will be detected in a given burst. However, the connection between the detectability of a line in a spectrum and in a burst requires a model for the occurrence of a line within a burst. We have developed the necessary weighting for the line detection probability for each spectrum spanning the burst. The resulting calculations require a description of each spectrum in the BATSE database. With these tools, we identify the bursts in which lines are most likely to be detected. Also, by assuming a small frequency with which lines occur, we calculate the approximate number of BATSE bursts in which lines of various types could be detected. Lines similar to the Ginga detections can be detected in relatively few BATSE bursts; for example, in only ~20 bursts are lines similar to the GB 880205 pair of lines detectable. Ginga reported lines at ~20 and ~40 keV, whereas the low-energy cutoff of the BATSE spectra is typically above 20 keV; hence BATSE's sensitivity to lines is less than that of Ginga below 40 keV, and greater above. Therefore, the probability that the GB 880205 lines would be detected in a Ginga burst rather than a BATSE burst is ~0.2. Finally, we adopt a more appropriate test of the significance of a line feature.
Wick Rotations, Eichler Integrals, and Multi-Loop Feynman Diagrams

Using contour deformations and integrations over modular forms, we compute certain Bessel moments arising from diagrammatic expansions in two-dimensional quantum field theory. We evaluate these Feynman integrals as either explicit constants or critical values of modular $L$-series, and verify several recent conjectures of Broadhurst.
Strongly local p-norm-cut algorithms for semi-supervised learning and local graph clustering

Graph based semi-supervised learning is the problem of learning a labeling function for the graph nodes given a few example nodes, often called seeds, usually under the assumption that the graph's edges indicate similarity of labels. This is closely related to the local graph clustering or community detection problem of finding a cluster or community of nodes around a given seed. For this problem, we propose a novel generalization of random walk, diffusion, or smooth function methods in the literature to a convex p-norm cut function. The need for our p-norm methods is that, in our study of existing methods, we find those principled methods based on eigenvector, spectral, random walk, or linear system often have difficulty capturing the correct boundary of a target label or target cluster. In contrast, 1-norm or maxflow-mincut based methods capture the boundary, but cannot grow from small seed set; hybrid procedures that use both have many hard to set parameters. In this paper, we propose a generalization of the objective function behind these methods involving p-norms. To solve the p-norm cut problem we give a strongly local algorithm -- one whose runtime depends on the size of the output rather than the size of the graph. Our method can be thought as a nonlinear generalization of the Anderson-Chung-Lang push procedure to approximate a personalized PageRank vector efficiently. Our procedure is general and can solve other types of nonlinear objective functions, such as p-norm variants of Huber losses. We provide a theoretical analysis of finding planted target clusters with our method and show that the p-norm cut functions improve on the standard Cheeger inequalities for random walk and spectral methods. Finally, we demonstrate the speed and accuracy of our new method in synthetic and real world datasets. Our code is available at this http URL.
Large Extra Dimensions from a Small Extra Dimension

Models with extra dimensions have changed our understanding of the hierarchy problem. In general, these models explain the weakness of gravity by diluting gravity in a large bulk volume, or by localizing the graviton away from the standard model. In this paper, we show that the warped geometries necessary for the latter scenario can naturally induce the large volumes necessary for the former. We present a model in which a large volume is stabilized without supersymmetry. We comment on the phenomenology of this scenario and generalizations to additional dimensions.
Superradiance initiated inside the ergoregion

We consider the stationary metrics that have both the black hole and the ergoregion. The class of such metric contains, in particular, the Kerr metric. We study the Cauchy problem with highly oscillatory initial data supported in a neighborhood inside the ergoregion with some initial energy E0. We prove that when the time variable x0 increases this solution splits into two parts: one with the negative energy − E1 ending at the event horizon in a finite time, and the second part, with the energy E2 = E0 + E1 > E0, escaping, under some conditions, to the infinity when x0 → +∞. Thus we get the superradiance phenomenon. In the case of the Kerr metric the superradiance phenomenon is “short-lived”, since both the solutions with positive and negative energies cross the outer event horizon in a finite time (modulo O(1 k)) where k is a large parameter. We show that these solutions end on the singularity ring in a finite time. We study also the case of naked singularity.
Would Two Dimensions be World Enough for Spacetime

We consider various curious features of general relativity, and relativistic field theory, in two spacetime dimensions. In particular, we discuss: the vanishing of the Einstein tensor; the failure of an initial-value formulation for vacuum spacetimes; the status of singularity theorems; the non-existence of a Newtonian limit; the status of the cosmological constant; and the character of matter fields, including perfect fluids and electromagnetic fields. We conclude with a discussion of what constrains our understanding of physics in different dimensions.
ChipNet: Real-Time LiDAR Processing for Drivable Region Segmentation on an FPGA

This paper presents a field-programmable gate array (FPGA) design of a segmentation algorithm based on convolutional neural network (CNN) that can process light detection and ranging (LiDAR) data in real-time. For autonomous vehicles, drivable region segmentation is an essential step that sets up the static constraints for planning tasks. Traditional drivable region segmentation algorithms are mostly developed on camera data, so their performance is susceptible to the light conditions and the qualities of road markings. LiDAR sensors can obtain the 3D geometry information of the vehicle surroundings with high precision. However, it is a computational challenge to process a large amount of LiDAR data in real-time. In this paper, a CNN model is proposed and trained to perform semantic segmentation using data from the LiDAR sensor. An efficient hardware architecture is proposed and implemented on an FPGA that can process each LiDAR scan in 17.59 ms, which is much faster than the previous works. Evaluated using Ford and KITTI road detection benchmarks, the proposed solution achieves both high accuracy in performance and real-time processing in speed.
Global disorder transition in the community structure of large-q Potts systems

We examine a global disorder transition when identifying community structure in an arbitrary complex network. Earlier, we illustrated (Hu D. et al., Philos. Mag., 92 (2012) 406) that “community detection” (CD) generally exhibits disordered (or unsolvable) and ordered (solvable) phases of both high and low computational complexity along with corresponding transitions from regular to chaotic dynamics in derived systems. Using an exact generalized dimensional reduction inequality, multivariate Tutte polynomials, and other considerations, we illustrate how increasing the number of communities q emulates increasing the heat bath temperature T for a general weighted Potts model, leading to global disorder in the community structure of arbitrary large graphs. Dimensional reduction bounds lead to results similar to those suggested by mean-field–type approaches. Large systems tend toward global insolvability in the limit of large q above a crossover temperature where |Je| is a typical interaction strength, L is the number of edges, and N is the number of nodes. For practical system sizes, a solvable phase is generally accessible at low T. The global nature of the disorder transition does not preclude solutions by local CD algorithms (even those that employ global cost function parameters) as long as community evaluations are locally determined.
USING CLOSE WHITE DWARF + M DWARF STELLAR PAIRS TO CONSTRAIN THE FLARE RATES IN CLOSE STELLAR BINARIES

We present a study of the statistical flare rates of M dwarfs (dMs) with close white dwarf (WD) companions (WD+dM; typical separations < 1 au). Our previous analysis demonstrated that dMs with close WD companions are more magnetically active than their field counterparts. One likely implication of having a close binary companion is increased stellar rotation through disk-disruption, tidal effects, and/or angular momentum exchange; increased stellar rotation has long been associated with an increase in stellar activity. Previous studies show a strong correlation between dMs that are magnetically active (showing H{\alpha} in emission) and the frequency of stellar flare rates. We examine the difference between the flare rates observed in close WD+dM binary systems and field dMs. Our sample consists of a subset of 181 close WD+dM pairs from Morgan et al. (2012) observed in the Sloan Digital Sky Survey Stripe 82, where we obtain multi-epoch observations in the Sloan ugriz-bands. We find an increase in the overall flaring fraction in the close WD+dM pairs (0.09$\pm$0.03%) compared to the field dMs (0.0108$\pm$0.0007%; Kowalski et al. 2009) and a lower flaring fraction for active WD+dMs (0.05$\pm$0.03%) compared to active dMs (0.28$\pm$0.05%; Kowalski et al. 2009). We discuss how our results constrain both the single and binary dM flare rates. Our results also constrain dM multiplicity, our knowledge of the Galactic transient background, and may be important for the habitability of attending planets around dMs with close companions.
Spinning particles, braid groups and solitons

Abstract We develop general techniques for computing the fundamental group of the configuration space of n identical particles, possessing a generic internal structure, moving on a manifold M. This group generalizes the n -string braid group of M which is the relevant object for structureless particles. In particular, we compute these generalized braid groups for particles with an internal spin degree of freedom on an arbitrary M. A study of their unitary representations allows us to determine the available spectrum of spin and statistics on M in a certain class of quantum theories. One interesting result is that half-integral spin quantizations are obtained on certain manifolds having an obstruction to an ordinary spin structure. We also compare our results to corresponding ones for topological solitons in O( d + 1)-invariant nonlinear sigma models in d + 1 dimensions, generalizing recent studies in two spatial dimensions. Finally, we prove that there exists a general scalar quantum theory yielding half-integral spin for particles (or O( d + 1) solitons) on a closed, orientable manifold M if and only if M possesses a spin c structure.