cssi/SciSciGPT-SciSciNet huggingface dataset:
Null distance on a spacetime

Given a time function τ on a spacetime M, we define a null distance function, , built from and closely related to the causal structure of M. In basic models with timelike , we show that (1) is a definite distance function, which induces the manifold topology, (2) the causal structure of M is completely encoded in and τ. In general, is a conformally invariant pseudometric, which may be indefinite. We give an 'anti-Lipschitz' condition on τ, which ensures that is definite, and show this condition to be satisfied whenever τ has gradient vectors almost everywhere, with locally 'bounded away from the light cones'. As a consequence, we show that the cosmological time function of Andersson et al (1998 Class. Quantum Grav. 15 309–22) is anti-Lipschitz when 'regular', and hence induces a definite null distance function. This provides what may be interpreted as a canonical metric space structure on spacetimes which emanate from a common initial singularity, e.g. a 'big bang'.
Experimental Study of Hong–Ou–Mandel Interference Using Independent Phase Randomized Weak Coherent States

Hong–Ou–Mandel interferometers are valuable tools in many Quantum Information and Quantum Optics applications that require photon indistinguishability. The theoretical limit for the Hong–Ou–Mandel visibility is 0.5 for indistinguishable weak coherent photon states, but several device imperfections may hinder achieving this value experimentally. In this work, we examine the dependence of the interference visibility on various factors, including 1) detector side imperfections due to after-pulses, 2) mismatches in the intensities and states of polarization of the input signals, and 3) the overall intensity of the input signals. We model all imperfections and show that theoretical modeling is in good agreement with the experimental results.
SPECTRAL ENERGY DISTRIBUTIONS OF WEAK ACTIVE GALACTIC NUCLEI ASSOCIATED WITH LOW-IONIZATION NUCLEAR EMISSION REGIONS

We present a compilation of spectral energy distributions (SEDs) of 35 weak active galactic nuclei (AGNs) in low-ionization nuclear emission regions (LINERs) using recent data from the published literature. We make use of previously published compilations of data, after complementing and extending them with more recent data. The main improvement in the recent data is afforded by high-spatial-resolution observations with the Chandra X-Ray Observatory and high-spatial-resolution radio observations utilizing a number of facilities. In addition, a considerable number of objects have been observed with the Hubble Space Telescope in the near-IR through near-UV bands since the earlier compilations were published. The data include upper limits resulting from either non-detections or observations at low spatial resolution that do not isolate the AGN. For the sake of completeness, we also compute and present a number of quantities from the data, such as optical-to-X-ray spectral indices (αox), bolometric corrections, bolometric luminosities, Eddington ratios, and the average SED. We anticipate that these data will be useful for a number of applications. In a companion paper, we use a subset of these data ourselves to assess the energy budgets of LINERs.
A Broadband Micro-machined Far-Infrared Absorber

The experimental investigation of a broadband far-infrared meta-material absorber is described. The observed absorptance is >0.95 from 1 to 20 THz (300–15 μm) over a temperature range spanning 5–300 K. The meta-material, realized from an array of tapers ≈100 μm in length, is largely insensitive to the detailed geometry of these elements and is cryogenically compatible with silicon-based micro-machined technologies. The electromagnetic response is in general agreement with a physically motivated transmission line model.
Cold Exponential Disks from Interstellar Fountains

We present the results of a simple numerical model with phenomenological cloud growth and explosive disruption processes, and with fountain launched ballistic motions of disrupted cloud fragments out of the disk. These processes generate an effective scattering of gas elements over much larger distances than noncircular impulses in the plane, which are quickly damped. The result is evolution of the global cloud density profile to an exponential form on a roughly Gyr timescale. This is consistent with our previous results on the effects of star scattering o? massive clumps in young disks, and gas holes in dwarf galaxies. However, in those cases the scattering processes generated thick, warm/hot stellar disks. Here we find that the exponential gas disks remain cold. Star formation in this gas would produce a thin exponential stellar disk.
Individual Alpha Elements, C, N, and Ba in Early-type Galaxies

Spectral data on early-type galaxies are analyzed for chemical abundance with an emphasis on obtaining detailed abundances for the elements O and Si in addition to C, N, Na, Mg, Ca, Fe, and Ba. The abundance trends with velocity dispersion fit preconceptions based upon previous Mg conclusions, namely, that larger galaxies have a higher alpha element to iron peak ratio indicative of a higher ratio of Type II to Type Ia supernova products. The heaviest alpha elements, Ca and Ti, do not participate in this trend, although this fact does not necessarily alter the basic picture given the uncertainties in nucleosynthetic yields. Elements that likely have significant contributions from intermediate-mass stars, namely, C, N, and Ba, also gain ground relative to Fe in massive galaxies at a modest level, with the Ba conclusion uncertain from our data alone. After the velocity dispersion trend is subtracted, [M/H], [N/Fe], [Na/Fe], [Mg/Fe], and [Ca/Fe] probably have cosmic scatter, and no quantity can be shown to not have cosmic scatter.
Stellar oscillations induced by the passage of a fast stellar object

In this paper, we investigate induced oscillations by the gravitational field of a fast stellar object, such as a neutron star or a black-hole in a near miss collision with another star. Nonadiabatic collision conditions may lead to large amplitude oscillations in the star. We show that for a solar-type star a resonant condition can be achieved by a fast moving stellar object with velocity in the range of 100 to 1000 km/s, passing at a distance of a few multiples of the star radius. Although such collisions are rare, they are more frequent than head-on collisions, and their effects could be observed through a visible change of the star luminosity occurring within a few hours.
D3-brane potentials from fluxes in AdS/CFT

We give a comprehensive treatment of the scalar potential for a D3-brane in a warped conifold region of a compactification with stabilized moduli. By studying general ultraviolet perturbations in supergravity, we systematically incorporate ‘compactification effects’ sourced by supersymmetry breaking in the compact space. Significant contributions to the D3-brane potential, including the leading term in the infrared, arise from imaginary anti-self-dual (IASD) fluxes. For an arbitrary Calabi-Yau cone, we determine the most general IASD fluxes in terms of scalar harmonics, then compute the resulting D3-brane potential. Specializing to the conifold, we identify the operator dual to each mode of flux, and for chiral operators we confirm that the potential computed in the gauge theory matches the gravity result. The effects of four-dimensional curvature, including the leading D3-brane mass term, arise directly from the ten-dimensional equations of motion. Furthermore, we show that gaugino condensation on D7-branes provides a local source for IASD flux. This flux automatically and precisely encodes the nonperturbative contributions to the D3-brane potential, yielding a promising ten-dimensional representation of four-dimensional nonperturbative effects. Our result encompasses all significant contributions to the D3-brane potential discussed in the literature, and does so in the single coherent framework of ten-dimensional supergravity. Moreover, we identify new terms with irrational scaling dimensions that were inaccessible in prior works. By decoupling gravity in a noncompact configuration, then systematically reincorporating compactification effects as ultraviolet perturbations, we have provided an approach in which Planck-suppressed contributions to the D3-brane effective action can be computed. This is the companion paper to [1].
The S-matrix for surface boundary states: An application to photoemission for Weyl semimetals

Abstract We present a new theory of photoemission for Weyl semimetals. We derive this theory using a model with a boundary surface at z = 0 . Due to the boundary, the self adjoint condition needs to be verified in order to ensure physical solutions. The solutions are given by two chiral zero modes which propagate on the boundary. Due to the Coulomb interaction, the chiral boundary model is in the same universality class as interacting graphene. The interactions cause a temperature dependence of the velocity and life time. Using the principle of minimal coupling, we identify the electron–photon Hamiltonian. The photoemission intensity is computed using the S -matrix formalism. The S -matrix is derived using the initial photon state, the final state of a photoelectron and a hole in the valence band. The photoemission reveals the final valence band dispersion ħ v ( ± k y − k 0 ) + ħ Ω after absorbing a photon of frequency Ω ( k 0 represents the shift in the momentum due to the crystal potential). The momentum in the z direction is not conserved, and is integrated out. As a result, the scattering matrix is a function of the parallel momentum . We observe two dimensional contours, representing the “Fermi arcs”, which for opposite spin polarization have opposite curvature. This theory is in agreement with previous experimental observations.
DynaMo: Dynamic Community Detection by Incrementally Maximizing Modularity

Community detection is of great importance for online social network analysis. The volume, variety and velocity of data generated by today's online social networks are advancing the way researchers analyze those networks. For instance, real-world networks, such as Facebook, LinkedIn and Twitter, are inherently growing rapidly and expanding aggressively over time. However, most of the studies so far have been focusing on detecting communities on the static networks. It is computationally expensive to directly employ a well-studied static algorithm repeatedly on the network snapshots of the dynamic networks. We propose DynaMo, a novel modularity-based dynamic community detection algorithm, aiming to detect communities of dynamic networks as effective as repeatedly applying static algorithms but in a more efficient way. DynaMo is an adaptive and incremental algorithm, which is designed for incrementally maximizing the modularity gain while updating the community structure of dynamic networks. In the experimental evaluation, a comprehensive comparison has been made among DynaMo, Louvain (static) and 5 other dynamic algorithms. Extensive experiments have been conducted on 6 real-world networks and 10,000 synthetic networks. Our results show that DynaMo outperforms all the other 5 dynamic algorithms in terms of the effectiveness, and is 2 to 5 times (by average) faster than Louvain algorithm.
Resource Allocation and Outage Analysis for an Adaptive Cognitive Two-Way Relay Network

In this paper, an adaptive two-way relay cooperation scheme is studied for multiple-relay cognitive radio networks to improve the performance of secondary transmissions. The power allocation and relay selection schemes are derived to minimize the secondary outage probability where only statistical channel information is needed. Exact closed-form expressions for secondary outage probability are derived under a constraint on the quality of service of primary transmissions in terms of the required primary outage probability. To better understand the impact of primary user interference on secondary transmissions, we further investigate the asymptotic behaviors of the secondary relay network, including power allocation and outage probability, when the primary signal-to-noise ratio goes to infinity. Simulation results are provided to illustrate the performance of the proposed schemes.
Circuit analysis in metal-optics

Abstract We provide electrical circuit descriptions for bulk plasmons, single surface plasmons, and parallel-plate plasmons. Simple circuits can reproduce the exactly known frequency versus wave-vector dispersion relations for all these cases, with reasonable accuracy. The circuit paradigm directly provides a characteristic wave-impedance, Z o , that is rarely discussed in the context of plasmonics. The case of a single-surface-plasmon is particularly interesting since it can be modeled as a transmission line, even though there is no return current conductor. The capacitance/unit length and the Faraday inductance/unit length, of a flat metal surface, are C ′ = 2 ɛ o kW , and L ′ = μ o /2 kW , respectively (where k is the wave-vector, and W is the width of the flat metal surface). We believe that many other metal-optic geometries can be described within the circuit paradigm, with the prerequisite that the distributed capacitance and inductance must be calculated for each particular geometry.
Characterization of protonated and deuterated tetra-phenyl butadiene film in a polystyrene matrix

We study the effect of deuteration and annealing on the fluorescence spectrum shape and VUV to visible conversion efficiency of TPB films in a polystyrene matrix with input light from 120 to 220 nm. We observed no discernible difference in the fluorescence spectrum shape between any of the films. The deuterated film performed equally well compared to the standard one in terms of conversion efficiency, but annealing seems to degrade this efficiency to roughly 75% of its non annealed value at all wavelengths studied.
A Nonlocal Biharmonic Operator and its Connection with the Classical Analogue

We consider a singular integral operator as a natural generalization to the biharmonic operator that arises in thin plate theory. The operator is built in the nonlocal calculus framework defined in (Math Models Methods Appl Sci 23(03):493–540, 2013) and connects with the recent theory of peridynamics. This framework enables us to consider non-smooth approximations to fourth-order elliptic boundary-value problems. For these systems we introduce nonlocal formulations of the clamped and hinged boundary conditions that are well-defined even for irregular domains. We demonstrate the existence and uniqueness of solutions to these nonlocal problems and demonstrate their L 2-strong convergence to functions in W 2,2 as the nonlocal interaction horizon goes to zero. For regular domains we identify these limits as the weak solutions of the corresponding classical elliptic boundary-value problems. As a part of our proof we also establish that the nonlocal Laplacian of a smooth function is Lipschitz continuous.
Collinear expansion for color singlet cross sections

We demonstrate how to efficiently expand cross sections for color-singlet production at hadron colliders around the kinematic limit of all final state radiation being collinear to one of the incoming hadrons. This expansion is systematically improvable and applicable to a large class of physical observables. We demonstrate the viability of this technique by obtaining the first two terms in the collinear expansion of the rapidity distribution of the gluon fusion Higgs boson production cross section at next-to-next-to leading order (NNLO) in QCD perturbation theory. Furthermore, we illustrate how this technique is used to extract universal building blocks of scattering cross section like the N-jettiness and transverse momentum beam function at NNLO.
Resonance production in heavy-ion collisions

Recent results of resonance production from RHIC at √s NN = 200 GeV and from SPS at √s NN = 17 GeV are presented and discussed in terms of the evolution and freeze-out conditions of a hot and dense fireball medium. Yields and spectra are compared with thermal model predictions at chemical freeze-out. Deviations in the low transverse momentum region of the resonance spectrum of the hadronic decay channel suggest a strongly interaction hadronic phase between chemical and kinetic freeze-out. Microscopic models including resonance rescattering and regeneration are able to describe the trend of the data. The magnitude of the regeneration cross sections for different inverse decay channels is discussed. Model calculations which include elastic hadronic interactions between chemical freeze-out and thermal freeze-out based on the K(892)/K and A(1520)/A ratios suggest a time between two freeze-outs surfaces of AT >4 fm/c. The difference in momentum distributions and yields for the Φ(1020) resonance reconstructed from the leptonic and hadronic decay channels at SPS energy are discussed taking into account the impact of a hadronic phase and possible medium modifications.
A Second-order Godunov Method for Multi-dimensional Relativistic Magnetohydrodynamics

We describe a new Godunov algorithm for relativistic magnetohydrodynamics (RMHD) that combines a simple, unsplit second-order accurate integrator with the constrained transport (CT) method for enforcing the solenoidal constraint on the magnetic field. A variety of approximate Riemann solvers are implemented to compute the fluxes of the conserved variables. The methods are tested with a comprehensive suite of multi-dimensional problems. These tests have helped us develop a hierarchy of correction steps that are applied when the integration algorithm predicts unphysical states due to errors in the fluxes, or errors in the inversion between conserved and primitive variables. Although used exceedingly rarely, these corrections dramatically improve the stability of the algorithm. We present preliminary results from the application of these algorithms to two problems in RMHD: the propagation of supersonic magnetized jets and the amplification of magnetic field by turbulence driven by the relativistic Kelvin-Helmholtz instability (KHI). Both of these applications reveal important differences between the results computed with Riemann solvers that adopt different approximations for the fluxes. For example, we show that the use of Riemann solvers that include both contact and rotational discontinuities can increase the strength of the magnetic field within the cocoon by a factor of 10 in simulations of RMHD jets and can increase the spectral resolution of three-dimensional RMHD turbulence driven by the KHI by a factor of two. This increase in accuracy far outweighs the associated increase in computational cost. Our RMHD scheme is publicly available as part of the Athena code.
A binned likelihood for stochastic models

Metrics of model goodness-of-fit, model comparison, and model parameter estimation are the main categories of statistical problems in science. Bayesian and frequentist methods that address these questions often rely on a likelihood function, which is the key ingredient in order to assess the plausibility of model parameters given observed data. In some complex systems or experimental setups, predicting the outcome of a model cannot be done analytically, and Monte Carlo techniques are used. In this paper, we present a new analytic likelihood that takes into account Monte Carlo uncertainties, appropriate for use in the large and small sample size limits. Our formulation performs better than semi-analytic methods, prevents strong claims on biased statements, and provides improved coverage properties compared to available methods.
Interdependent Strategic Security Risk Management With Bounded Rationality in the Internet of Things

With the increasing connectivity enabled by the Internet of Things (IoT), security becomes a critical concern, and users should invest to secure their IoT applications. Due to the massive devices in the IoT network, users cannot be aware of the security policies taken by all its connected neighbors. Instead, a user makes security decisions based on the cyber risks that he perceives by observing a selected number of nodes. To this end, we propose a model which incorporates the limited attention or bounded rationality nature of players in the IoT. Specifically, each individual builds a sparse cognitive network of nodes to respond to. Based on this simplified cognitive network representation, each user then determines his security management policy by minimizing his own real-world security cost. The bounded rational decision-makings of players and their cognitive network formations are interdependent and thus should be addressed in a holistic manner. We establish a games-in-games framework and propose a Gestalt Nash equilibrium (GNE) solution concept to characterize the decisions of agents and quantify their risk of bounded perception due to the limited attention. In addition, we design a proximal-based iterative algorithm to compute the GNE. With case studies of smart communities, the designed algorithm can successfully identify the critical users whose decisions need to be taken into account by the other users during the security management.
Fractonic Chern-Simons and BF theories

This work proposes a fraction version of the Chern-Simons theory in higher dimension whose electromagnetic excitation has constraint mobilities.
Hi-C Observations of Sunspot Penumbral Bright Dots

We report observations of bright dots (BDs) in a sunspot penumbra using High Resolution Coronal Imager (Hi-C) data in 193 A and examine their sizes, lifetimes, speeds, and intensities. The sizes of the BDs are on the order of 1'' and are therefore hard to identify in the Atmospheric Imaging Assembly (AIA) 193 A images, which have a 12 spatial resolution, but become readily apparent with Hi-C's spatial resolution, which is five times better. We supplement Hi-C data with data from AIA's 193 A passband to see the complete lifetime of the BDs that appeared before and/or lasted longer than Hi-C's three-minute observation period. Most Hi-C BDs show clear lateral movement along penumbral striations, either toward or away from the sunspot umbra. Single BDs often interact with other BDs, combining to fade away or brighten. The BDs that do not interact with other BDs tend to have smaller displacements. These BDs are about as numerous but move slower on average than Interface Region Imaging Spectrograph (IRIS) BDs, which was recently reported by Tian et al., and the sizes and lifetimes are on the higher end of the distribution of IRIS BDs. Using additional AIA passbands, we compare the light curves of the BDs to test whether the Hi-C BDs have transition region (TR) temperatures like those of the IRIS BDs. The light curves of most Hi-C BDs peak together in different AIA channels, indicating that their temperatures are likely in the range of the cooler TR (1−4 × 105 K).
INTERSTELLAR PICKUP ION PRODUCTION IN THE GLOBAL HELIOSPHERE AND HELIOSHEATH

Interstellar pickup ions (PUIs) play a significant part in mediating the solar wind (SW) interaction with the interstellar medium. In this paper, we examine the details of spatial variation of the PUI velocity distribution function (VDF) in the SW by solving the PUI transport equation. We assume the PUI distribution is isotropic resulting from strong pitch-angle scattering by wave–particle interaction. A three-dimensional model combining the MHD treatment of the background SW and neutrals with a kinetic treatment of PUIs throughout the heliosphere and the surrounding local interstellar medium has been developed. The model generates PUI power-law tails via second-order Fermi process. We analyze how PUIs transform across the heliospheric termination shock and obtain the PUI phase space distribution in the inner heliosheath including continuing velocity diffusion. Our simulated PUI spectra are compared with observations made by New Horizons, Ulysses, Voyager 1, 2, and Cassini, and a satisfactory agreement is demonstrated. Some specific features in the observations, for example, a cutoff of PUI VDF at v = V SW and a f ∝ v −5 tail in the reference frame of the SW, are well represented by the model.
Expanded solar-system limits on violations of the equivalence principle

Most attempts to unify general relativity with the standard model of particle physics predict violations of the equivalence principle associated in some way with the composition of the test masses. We test this idea by using observational uncertainties in the positions and motions of solar-system bodies to set upper limits on the relative difference Δ between gravitational and inertial mass for each body. For suitable pairs of objects, it is possible to constrain three different linear combinations of Δ using Kepler's third law, the migration of stable Lagrange points, and orbital polarization (the Nordtvedt effect). Limits of order 10−10–10−6 on Δ for individual bodies can then be derived from planetary and lunar ephemerides, Cassini observations of the Saturn system, and observations of Jupiter's Trojan asteroids as well as recently discovered Trojan companions around the Earth, Mars, Neptune, and Saturnian moons. These results can be combined with models for elemental abundances in each body to test for composition-dependent violations of the universality of free fall in the solar system. The resulting limits are weaker than those from laboratory experiments, but span a larger volume in composition space.
Grand Canonical Ensembles in General Relativity

We develop a formalism for general relativistic, grand canonical ensembles in space-times with timelike Killing fields. Using that, we derive ideal gas laws, and show how they depend on the geometry of the particular space-times. A systematic method for calculating Newtonian limits is given for a class of these space-times, which is illustrated for Kerr space-time. In addition, we prove uniqueness of the infinite volume Gibbs measure, and absence of phase transitions for a class of interaction potentials in anti-de Sitter space.
Large bipolarons and oxide superconductivity

Large-bipolaron superconductivity is plausible with carrier densities well below those of conventional metals. Bipolarons form when carriers self-trap in pairs. Coherently moving large-bipolarons require extremely large ratios of static to optical dielectric-constants. The mutual Coulomb repulsion of a planar large-bipolaron’s paired carriers drives it to a four-lobed shape. A phonon-mediated attraction among large-bipolarons propels their condensation into a liquid. This liquid’s excitations move slowly with a huge effective mass. Excitations’ concomitant weak scattering by phonons produces a moderate low-temperature dc resistivity that increases linearly with rising temperature. With falling temperature an energy gap opens between large-bipolarons’ excitations and those of their self-trapped electronic carriers.
RedMaPPer: Evolution and Mass Dependence of the Conditional Luminosity Functions of Red Galaxies in Galaxy Clusters

We characterize the luminosity distribution, halo-mass dependence, and redshift evolution of red galaxies in galaxy clusters using the SDSS Data Release 8 redMaPPer cluster sample. We propose a simple prescription for the relationship between the luminosity of both red central and red satellite galaxies and the mass of their host halos, and show that this model is well fit by the data. Using a larger galaxy cluster sample than previously employed in the literature, we find that the luminosities of red central galaxies scale as , with A L = 0.39 ± 0.04, and that the scatter of the red central galaxy luminosity at fixed M 200b () is dex, with the error bar including systematics due to mis-centering of the cluster finder, photometry, and photometric redshift estimation. Our data prefers a positive correlation between the luminosity of red central galaxies and the observed richness of clusters at a fixed halo mass, with an effective correlation coefficient . The characteristic luminosity of red satellites becomes dimmer from z = 0.3 to z = 0.1 by ∼20% after accounting for passive evolution. We estimate the fraction of galaxy clusters where the brightest red galaxy is not the central to be P BNC ∼ 20%. We discuss implications of these findings in the context of galaxy evolution and the galaxy–halo connection.
How Well Does AdS/QCD Describe QCD?

AdS/QCD is an extra-dimensional approach to modeling hadronic physics, motivated by the AdS/CFT correspondence in string theory. AdS/QCD models are often more accurate than would have been expected at energies below a few GeV. We address the question of why these models are so successful, and respond to some of the criticisms that have been waged against these models.
Development of magnetic liquid metal suspensions for magnetohydrodynamics

Magnetic and nonmagnetic particles are suspended in liquid metals to obtain a fluid with high magnetic susceptibility, high electrical conductivity, and tunable viscosity. These properties will allow magnetohydrodynamic experiments over a wider parameter range than liquid metals alone.
Coupled-cluster theory of a gas of strongly-interacting fermions in the dilute limit

We study the ground-state properties of a dilute gas of strongly-interacting fermions in the framework of the coupled-cluster expansion (CCE). We demonstrate that properties such as universality, opening of a gap in the excitation spectrum and applicability of s-wave approximations appear naturally in the CCE approach. In the zero-density limit, we show that the ground-state energy density depends on only one parameter, which in turn may depend at most on the spatial dimensionality of the system.
Rigid local systems and finite general linear groups

We use hypergeometric sheaves on $${{\mathbb {G}}}_m/{{\mathbb {F}}}_q$$ , which are particular sorts of rigid local systems, to construct explicit local systems whose arithmetic and geometric monodromy groups are the finite general linear groups $$\mathrm {GL}_n(q)$$ for any $$n \ge 2$$ and any prime power q, so long as $$q > 3$$ when $$n=2$$ . This paper continues a program of finding simple (in the sense of simple to remember) families of exponential sums whose monodromy groups are certain finite groups of Lie type, cf. Gross (Adv Math 224:2531–2543, 2010), Katz (Mathematika 64:785–846, 2018) and Katz and Tiep (Finite Fields Appl 59:134–174, 2019; Adv Math 358:106859, 2019; Proc Lond Math Soc, 2020) for (certain) finite symplectic and unitary groups, or certain sporadic groups, cf. Katz and Rojas-Leon (Finite Fields Appl 57:276–286, 2019) and Katz et al. (J Number Theory 206:1–23, 2020; Int J Number Theory 16:341–360, 2020; Trans Am Math Soc 373:2007–2044, 2020). The novelty of this paper is obtaining $$\mathrm {GL}_n(q)$$ in this hypergeometric way. A pullback construction then yields local systems on $${{\mathbb {A}}}^1/{{\mathbb {F}}}_q$$ whose geometric monodromy groups are $$\mathrm {SL}_n(q)$$ . These turn out to recover a construction of Abhyankar.
Turbulence, feedback, and slow star formation

One of the outstanding puzzles about star formation is why it proceeds so slowly. Giant molecular clouds convert only a few percent of their gas into stars per free-fall time, and recent observations show that this low star formation rate is essentially constant over a range of scales from individual cluster-forming molecular clumps in the Milky Way to entire starburst galaxies. This striking result is perhaps the most basic fact that any theory of star formation must explain. I argue that a model in which star formation occurs in virialized structures at a rate regulated by supersonic turbulence can explain this observation. The turbulence in turn is driven by star formation feedback, which injects energy to offset radiation from isothermal shocks and keeps star-forming structures from wandering too far from virial balance. This model is able to reproduce observational results covering a wide range of scales, from the formation times of young clusters to the extragalactic IR-HCN correlation, and makes additional quantitative predictions that will be testable in the next few years.
Nilpotent networks and 4D RG flows

Starting from a general $$ \mathcal{N}=2 $$ SCFT, we study the network of $$ \mathcal{N}=1 $$ SCFTs obtained from relevant deformations by nilpotent mass parameters. We also study the case of flipper field deformations where the mass parameters are promoted to a chiral superfield, with nilpotent vev. Nilpotent elements of semi-simple algebras admit a partial ordering connected by a corresponding directed graph. We find strong evidence that the resulting fixed points are connected by a similar network of 4D RG flows. To illustrate these general concepts, we also present a full list of nilpotent deformations in the case of explicit $$ \mathcal{N}=2 $$ SCFTs, including the case of a single D3-brane probing a D- or E-type F-theory 7-brane, and 6D (G, G) conformal matter compactified on a T2, as described by a single M5-brane probing a D- or E-type singularity. We also observe a number of numerical coincidences of independent interest, including a collection of theories with rational values for their conformal anomalies, as well as a surprisingly nearly constant value for the ratio aIR/cIR for the entire network of flows associated with a given UV $$ \mathcal{N}=2 $$ SCFT. The arXiv submission also includes the full dataset of theories which can be accessed with a companion Mathematica script.
Demystifying the characteristics of 3D-stacked memories: A case study for Hybrid Memory Cube

Three-dimensional (3D)-stacking technology, which enables the integration of DRAM and logic dies, offers high bandwidth and low energy consumption. This technology also empowers new memory designs for executing tasks not traditionally associated with memories. A practical 3D-stacked memory is Hybrid Memory Cube (HMC), which provides significant access bandwidth and low power consumption in a small area. Although several studies have taken advantage of the novel architecture of HMC, its characteristics in terms of latency and bandwidth or their correlation with temperature and power consumption have not been fully explored. This paper is the first, to the best of our knowledge, to characterize the thermal behavior of HMC in a real environment using the AC-510 accelerator and to identify temperature as a new limitation for this state-of-the-art design space. Moreover, besides bandwidth studies, we deconstruct factors that contribute to latency and reveal their sources for high- and low-load accesses. The results of this paper demonstrates essential behaviors and performance bottlenecks for future explorations of packet-switched and 3D-stacked memories.
Constraining New Models with Precision Electroweak Data

Electroweak precision data have been extensively used to constrain models containing physics beyond that of the Standard Model (SM). When the model contains Higgs scalars in representations other than singlets or doublets, and hence ρ≠1 at tree-level, a correct renormalization scheme requires more inputs than the three commonly used for the SM case. In such cases, the one-loop electroweak results cannot be split into a SM contribution plus a piece which vanishes as the scale of new physics becomes much larger than MW. We illustrate our results by presenting the dependence of MW on the top-quark mass in a model with a Higgs triplet and in the SU(2)L × SU(2)R left–right symmetric model. In these models, the allowed range for the lightest neutral Higgs mass can be as large as a few TeV.
Thermodynamic Scaling of Diffusion in Supercooled Lennard-Jones Liquids

Establishing a quantitative connection between the relaxation properties of a liquid and the interactions among its constituent molecules is the sine qua non for fundamental understanding and prediction of the dynamical properties. The supercooled regime is of particular interest, since both intermolecular forces and steric constraints (excluded volume) exert significant effects on the dynamics. This makes temperature, pressure, and volume essential experimental variables to characterize the relaxation properties. One successful approach to at least categorize dynamic properties of supercooled liquids and polymers is by expressing them as a function of the ratio of mass density F to temperature T, with the former raised to a material specific constant A, namely,
Health Care Versus Illness Care: How Nurses Can Change It

<p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;mso-mirror-indents:yes"> Abstract <p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;mso-mirror-indents:yes"> Statement of the Problem: Our nation has been trying to solve the “Health care crisis” for decades. Part of this drive is to address the ever rising cost of American “Health Care”. An examination of our “Health Care” reveals it is actually illness care. Even with the current “Preventative Care” mandate of the Affordable Health Care Act it is not preventative care. Essentially the preventative care clause only provides for screenings to find signs of potential problems. The current system does very little for prevention. The screening is a step in the right direction to prevent complications, but really is not preventing the disease. Another system must be employed to truly provide preventative care and curb the rising cost of health care in America. <p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;mso-mirror-indents:yes"> Purpose of Study: To explore the diseases that can be prevented with lifestyle changes, and find methods to assist patients in self-care to prevent disease. It will explore real “Health Care” that can result in decreased “Health Care” costs and a healthier nation. <p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;mso-mirror-indents:yes"> Methodology: A search using CINAHL, alt Health Watch, Health Source: Nursing/Academic Edition databases using keywords obesity, preventable disease, motivating the unmotivated, and health care costs. A literature review of these articles then conducted. <p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;text-align: justify;line-height:normal;mso-mirror-indents:yes"> Findings: <span style="font-size: 10.0pt;font-family:" times="" new="" roman",serif;color:black;mso-themecolor:text1"=""> Most diseases, including cancer, heart disease, diabetes, hypertension, hyperlipidemia, strokes, gallbladder disease, osteoarthritis, sleep apnea and breathing problems, mental illness, fatty liver, kidney disease, and obesity are largely preventable with simple lifestyle changes. The interventions that prevent these diseases are well known, but not employed in our current “Health Care” system. <span style="font-size:10.0pt; line-height:107%;font-family:" times="" new="" roman",serif;mso-fareast-font-family:="" calibri;mso-fareast-theme-font:minor-latin;color:black;mso-themecolor:text1;="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">Conclusion: Our current “Illness care system” needs to be replaced by a true “Health Care” system to prevent disease instead of treat disease. Nurses need have the training and knowledge to effect that change and improve the health care of our nation.
Photoacoustic Vision for Surgical Guidance

Photoacoustic imaging offers “x-ray vision” to see beyond tool tips and underneath tissue during surgical procedures, without requiring ionizing x-rays. Instead, optical fibers and acoustic receivers enable photoacoustic sensing of major structures – like blood vessels and nerves – that are otherwise hidden from view. Laser pulses are transmitted through the optical fibers to illuminate regions of interest, causing an acoustic response that is detectable with ultrasound transducers. This invited contribution highlights a few applications of photoacoustic imaging for surgical guidance and connects novel light delivery systems introduced by the Photoacoustic & Ultrasonic Systems Engineering (PULSE) Lab to our newly developed coherence-based beamforming theory. The paper concludes with a vision statement describing possibilities for the usage of photoacoustic imaging in operating rooms and interventional suites.
A Herschel (C II) Galactic plane survey II. CO-dark H2 in clouds

Context. H i and CO large scale surveys of the Milky Way trace the diffuse atomic clouds and the dense shielded regions of molecular hydrogen clouds, respectively. However, until recently, we have not had spectrally resolved C + surveys in sufficient lines of sight to characterize the ionized and photon dominated components of the interstellar medium, in particular, the H2 gas without CO, referred to as CO-dark H2, in a large sample of interstellar clouds. Aims. We use a sparse Galactic plane survey of the 1.9 THz (158 μm) [C ii] spectral line from the Herschel open time key programme, Galactic Observations of Terahertz C+ (GOT C+), to characterize the H2 gas without CO in a statistically significant sample of interstellar clouds. Methods. We identify individual clouds in the inner Galaxy by fitting the [C ii] and CO isotopologue spectra along each line of sight. We then combine these spectra with those of H i and use them along with excitation models and cloud models of C + to determine the column densities and fractional mass of CO-dark H2 clouds. Results. We identify1804 narrow velocity [C ii] components corresponding to interstellar clouds in different categories and evolutionary states. About 840 are diffuse molecular clouds with no CO, ∼510 are transition clouds containing [C ii ]a nd 12 CO, but no 13 CO, and the remainder are dense molecular clouds containing 13 CO emission. The CO-dark H2 clouds are concentrated between Galactic radii of ∼3.5 to 7.5 kpc and the column density of the CO-dark H2 layer varies significantly from cloud to cloud with a global average of 9 × 10 20 cm −2 . These clouds contain a significant fraction by mass of CO-dark H2, that varies from ∼75% for diffuse molecular clouds to ∼20% for dense molecular clouds. Conclusions. We find a significant fraction of the warm molecular ISM gas is invisible in H i and CO, but is detected in [C ii]. The fraction of CO-dark H2 is greatest in the diffuse clouds and decreases with increasing total column density, and is lowest in the massive clouds. The column densities and mass fraction of CO-dark H2 are less than predicted by models of diffuse molecular clouds using solar metallicity, which is not surprising as most of our detections are in Galactic regions where the metallicity is larger and shielding more effective. There is an overall trend towards a higher fraction of CO-dark H2 in clouds with increasing Galactic radius, consistent with lower metallicity there.
Differential geometric analysis of radiation--particle interaction

On the basis of the Lorentz equations of motion, the orbit of a charge driven by a generic EM field with planar symmetry is formulated and analyzed within the framework of a Lorentzian geometry with a curvature whose order of magnitude is parametrized by the radiation intensity and frequency. This reformulation leads to (i) a demonstration of the integrability of the particle motion in a plane-wave field as a result of the vanishing of the curvature, (ii) a manifestation of the parametric dependence of the dynamical response of the particle orbit to the EM field on the impulse factor in terms of local stability and the occurrence of parametric resonance, and (iii) a mathematically precise meaning to the ponderomotive oscillation center of the charge executing oscillatory motion in a sufficiently low impulsive EM field, which is subsequently used to raise (iv) a discussion of the domain of applicability of the ponderomotive approximation.
The missing angular momentum of superconductors.

We point out that the Meissner effect, the process by which a superconductor expels magnetic field from its interior, represents an unsolved puzzle within the London–Bardeen–Cooper–Schrieffer theoretical framework used to describe the physics of conventional superconductors, because it appears to give rise to non-conservation of angular momentum. Possible ways to avoid this inconsistency within the conventional theory of superconductivity are argued to be far-fetched. Consequently, we argue that unless/until a consistent explanation is put forth, the existence of the Meissner effect represents an anomaly that casts doubt on the validity of the conventional framework. Instead, we point out that three elements of the unconventional theory of hole superconductivity (that are not part of the conventional theory) allow for a consistent explanation of the Meissner effect, namely: (i) that the charge distribution in superconductors is macroscopically inhomogeneous, (ii) that superconducting electrons reside in mesoscopic orbits of radius 2λL (λL = London penetration depth), and (iii) that spin–orbit coupling plays an essential role in superconductivity.
Selective unsupervised feature learning with Convolutional Neural Network (S-CNN)

Supervised learning of convolutional neural networks (CNNs) can require very large amounts of labeled data. Labeling thousands or millions of training examples can be extremely time consuming and costly. One direction towards addressing this problem is to create features from unlabeled data. In this paper we propose a new method for training a CNN, with no need for labeled instances. This method for unsupervised feature learning is then successfully applied to a challenging object recognition task. The proposed algorithm is relatively simple, but attains accuracy comparable to that of more sophisticated methods. The proposed method is significantly easier to train, compared to existing CNN methods, making fewer requirements on manually labeled training data. It is also shown to be resistant to overfitting. We provide results on some well-known datasets, namely STL-10, CIFAR-10, and CIFAR-100. The results show that our method provides competitive performance compared with existing alternative methods. Selective Convolutional Neural Network (S-CNN) is a simple and fast algorithm, it introduces a new way to do unsupervised feature learning, and it provides discriminative features which generalize well.
Modeling dense stellar systems: background

I provide some background about recent efforts made in modeling dense stellar systems, within the context of the MODEST initiative. During the last four years, we have seen more than fifteen MODEST workshops, with an attendance between twenty and a hundred participants, and topics ranging from very specialized discussions to rather general overviews.