cssi/SciSciGPT-SciSciNet huggingface dataset:
Numerical accuracy comparison of two boundary conditions commonly used to approximate shear stress distributions in tissue engineering scaffolds cultured under flow perfusion

Introduction Flow-induced shear stresses have been found to be a stimulatory factor in pre-osteoblastic cells seeded in 3D porous scaffolds and cultured under continuous flow perfusion. However, due to the complex internal structure of the scaffolds, whole scaffold calculations of the local shear forces are computationally intensive. Instead, representative volume elements (RVEs), which are obtained by extracting smaller portions of the scaffold, are commonly used in literature without a numerical accuracy standard. Objective Hence, the goal of this study is to examine how closely the whole scaffold simulations are approximated by the two types of boundary conditions used to enable the RVEs: "wall boundary condition" (WBC) and "periodic boundary condition" (PBC). Method To that end, lattice Boltzmann method fluid dynamics simulations were used to model the surface shear stresses in 3D scaffold reconstructions, obtained from high-resolution microcomputed tomography images. Results It was found that despite the RVEs being sufficiently larger than 6 times the scaffold pore size (which is the only accuracy guideline found in literature), the stresses were still significantly under-predicted by both types of boundary conditions: between 20% and 80% average error, depending on the scaffold's porosity. Moreover, it was found that the error grew with higher porosity. This is likely due to the small pores dominating the flow field, and thereby negating the effects of the unrealistic boundary conditions, when the scaffold porosity is small. Finally, it was found that the PBC was always more accurate and computationally efficient than the WBC. Therefore, it is the recommended type of RVE.
Uniform first-order definitions in finitely generated fields

We prove that there is a first-order sentence in the language of rings that is true for all finitely generated fields of characteristic 0 and false for all fields of characteristic >0. We also prove that for each n in N, there is a first-order formula psi_n(x_1,...,x_n) that when interpreted in a finitely generated field K is true for elements x_1,...,x_n in K if and only if the elements are algebraically dependent over the prime field in K.
Improved Planetary Rover Inertial Navigation and Wheel Odometry Performance through Periodic Use of Zero-Type Constraints

We present an approach to enhance wheeled planetary rover dead-reckoning localization performance by leveraging the use of zero-type constraint equations in the navigation filter. Without external aiding, inertial navigation solutions inherently exhibit cubic error growth. Furthermore, for planetary rovers that are traversing diverse types of terrain, wheel odometry is often unreliable for use in localization, due to wheel slippage. For current Mars rovers, computer vision-based approaches are generally used whenever there is a high possibility of positioning error; however, these strategies require additional computational power, energy resources, adequate features in the environment, and significantly slow down the rover traverse speed. To this end, we propose a navigation approach that compensates for the high likelihood of odometry errors by providing a reliable navigation solution that leverages non-holonomic vehicle constraints as well as state-aware pseudo-measurements (e.g., zero velocity and zero angular rate) updates during periodic stops. By using this, computationally expensive visual-based corrections could be performed less often. Experimental tests that compare against GPS-based localization are used to demonstrate the accuracy of the proposed approach. The source code, post-processing scripts, and example datasets associated with the paper are published in a public repository.
FLOWS AND MOTIONS IN MOSS IN THE CORE OF A FLARING ACTIVE REGION: EVIDENCE FOR STEADY HEATING

We present new measurements of the time variability of intensity, Doppler, and nonthermal velocities in moss in an active region core observed by the EUV Imaging Spectrometer on Hinode in 2007 June. The measurements are derived from spectral profiles of the Fe XII 195 A line. Using the 2'' slit, we repeatedly scanned 150'' by 150'' in a few minutes. This is the first time it has been possible to make such velocity measurements in the moss, and the data presented are the highest cadence spatially resolved maps of moss Doppler and nonthermal velocities ever obtained in the corona. The observed region produced numerous C- and M-class flares with several occurring in the core close to the moss. The magnetic field was therefore clearly changing in the active region core, so we ought to be able to detect dynamic signatures in the moss if they exist. Our measurements of moss intensities agree with previous studies in that a less than 15% variability is seen over a period of 16 hr. Our new measurements of Doppler and nonthermal velocities reveal no strong flows or motions in the moss, nor any significant variability in these quantities. The results confirm that moss atmore » the bases of high temperature coronal loops is heated quasi-steadily. They also show that quasi-steady heating can contribute significantly even in the core of a flare productive active region. Such heating may be impulsive at high frequency, but if so it does not give rise to large flows or motions.« less
Validity of the Einstein Hole Argument

Arguing from his "hole" thought experiment, Einstein became convinced that, in cases in which the energy-momentum-tensor source vanishes in a spacetime hole, a solution to his general relativistic field equation cannot be uniquely determined by that source. After reviewing the definition of active diffeomorphisms, this paper uses them to outline a mathematical proof of Einstein's result. The relativistic field equation is shown to have multiple solutions, just as Einstein thought. But these multiple solutions can be distinguished by the different physical meaning that each metric solution attaches to the local coordinates used to write it. Thus the hole argument, while formally correct, does not prohibit the subsequent rejection of spurious solutions and the selection of a physically unique metric. This conclusion is illustrated using the Schwarzschild metric. It is suggested that the Einstein hole argument therefore cannot be used to argue against substantivalism.
PruneTrain: fast neural network training by dynamic sparse model reconfiguration

State-of-the-art convolutional neural networks (CNNs) used in vision applications have large models with numerous weights. Training these models is very compute- and memory-resource intensive. Much research has been done on pruning or compressing these models to reduce the cost of inference, but little work has addressed the costs of training. We focus precisely on accelerating training. We propose PruneTrain, a cost-efficient mechanism that gradually reduces the training cost during training. PruneTrain uses a structured group-lasso regularization approach that drives the training optimization toward both high accuracy and small weight values. Small weights can then be periodically removed by reconfiguring the network model to a smaller one. By using a structured-pruning approach and additional reconfiguration techniques we introduce, the pruned model can still be efficiently processed on a GPU accelerator. Overall, PruneTrain achieves a reduction of 39% in the end-to-end training time of ResNet50 for ImageNet by reducing computation cost by 40% in FLOPs, memory accesses by 37% for memory bandwidth bound layers, and the inter-accelerator communication by 55%.
A data-scalable randomized misfit approach for solving large-scale PDE-constrained inverse problems

A randomized misfit approach is presented for the efficient solution of large-scale PDE-constrained inverse problems with high-dimensional data. The purpose of this paper is to offer a theory-based framework for random projections in this inverse problem setting. The stochastic approximation to the misfit is analyzed using random projection theory. By expanding beyond mean estimator convergence, a practical characterization of randomized misfit convergence can be achieved. The theoretical results developed hold with any valid random projection in the literature. The class of feasible distributions is broad yet simple to characterize compared to previous stochastic misfit methods. This class includes very sparse random projections which provide additional computational benefit. A different proof for a variant of the Johnson-Lindenstrauss lemma is also provided. This leads to a different intuition for the $O(\epsilon^{-2})$ factor in bounds for Johnson-Lindenstrauss results. The main contribution of this paper is a theoretical result showing the method guarantees a valid solution for small reduced misfit dimensions. The interplay between Johnson-Lindenstrauss theory and Morozov's discrepancy principle is shown to be essential to the result. The computational cost savings for large-scale PDE-constrained problems with high- dimensional data is discussed. Numerical verification of the developed theory is presented for model problems of estimating a distributed parameter in an elliptic partial differential equation. Results with different random projections are presented to demonstrate the viability and accuracy of the proposed approach.
Correcting for the effects of pupil discontinuities with the ACAD method

The current generation of ground-based coronagraphic instruments uses deformable mirrors to correct for phase errors and to improve contrast levels at small angular separations. Improving these techniques, several space and ground based instruments are currently developed using two deformable mirrors to correct for both phase and amplitude errors. However, as wavefront control techniques improve, more complex telescope pupil geometries (support structures, segmentation) will soon be a limiting factor for these next generation coronagraphic instruments. The technique presented in this proceeding, the Active Correction of Aperture Discontinuities method, is taking advantage of the fact that most future coronagraphic instruments will include two deformable mirrors, and is proposing to find the shapes and actuator movements to correct for the effect introduced by these complex pupil geometries. For any coronagraph previously designed for continuous apertures, this technique allow to obtain similar performance in contrast with a complex aperture (with segmented and secondary mirror support structures), with high throughput and flexibility to adapt to changing pupil geometry (e.g. in case of segment failure or maintenance of the segments). We here present the results of the parametric analysis realized on the WFIRST pupil for which we obtained high contrast levels with several deformable mirror setups (size, separation between them), coronagraphs (Vortex charge 2, vortex charge 4, APLC) and spectral bandwidths. However, because contrast levels and separation are not the only metrics to maximize the scientific return of an instrument, we also included in this study the influence of these deformable mirror shapes on the throughput of the instrument and sensitivity to pointing jitters. Finally, we present results obtained on another potential space based telescope segmented aperture. The main result of this proceeding is that we now obtain comparable performance than the coronagraphs previously designed for WFIRST. First result from the parametric analysis strongly suggest that the 2 deformable mirror set up (size and distance between them) have a important impact on the performance in contrast and throughput of the final instrument.
All-optical three-dimensional electron pulse compression

We propose an all-optical, three-dimensional electron pulse compression scheme in which Hermite?Gaussian optical modes are used to fashion a three-dimensional optical trap in the electron pulse?s rest frame. We show that the correct choices of optical incidence angles are necessary for optimal compression. We obtain analytical expressions for the net impulse imparted by Hermite?Gaussian free-space modes of arbitrary order. Although we focus on electrons, our theory applies to any charged particle and any particle with non-zero polarizability in the Rayleigh regime. We verify our theory numerically using exact solutions to Maxwell?s equations for first-order Hermite?Gaussian beams, demonstrating single-electron pulse compression factors of in both longitudinal and transverse dimensions with experimentally realizable optical pulses. The proposed scheme is useful in ultrafast electron imaging for both single- and multi-electron pulse compression, and as a means of circumventing temporal distortions in magnetic lenses when focusing ultrashort electron pulses. Other applications include the creation of flat electron beams and ultrashort electron bunches for coherent terahertz emission.
Numerical modeling of nonohmic percolation conduction and Poole–Frenkel laws

We present a numerical model that simulates the current–voltage (I–V) characteristics of materials exhibiting percolation conduction. The model consists of a two dimensional grid of exponentially different resistors in the presence of an external electric field. We obtained exponentially nonohmic I–V characteristics validating earlier analytical predictions and consistent with multiple experimental observations of the Poole–Frenkel laws in noncrystalline materials. The exponents are linear in voltage for samples smaller than the correlation length of percolation cluster L and square root in voltage for samples larger than L.
CHANGES IN THE SUBSURFACE STRATIFICATION OF THE SUN WITH THE 11-YEAR ACTIVITY CYCLE

We report on changes in the Sun's subsurface stratification inferred from helioseismology data. Using data from the Solar and Heliospheric Observatory (SOHO) Michelson Doppler Imager (MDI) for the last 9 years and, more precisely, the temporal variation of f-mode frequencies, we have computed the variation in the radius of subsurface layers of the Sun by applying helioseismic inversions. We have found a variability of the "helioseismic" radius in antiphase with the solar activity, with the strongest variations of the stratification being just below the surface, around 0.995 R☉. In addition, the radius of the deeper layers of the Sun, between 0.975 and 0.99 R☉, changes in phase with the 11-year cycle.
The thermodynamic uncertainty relation in biochemical oscillations.

Living systems regulate many aspects of their behaviour through periodic oscillations of molecular concentrations, which function as ‘biochemical clocks.’ The chemical reactions that drive these cl...
Gravitational Lensing by Cold Dark Matter Catastrophes

Intrinsically cold particle dark matter inevitably creates halos with sharp discontinuities in projected surface density caused by the projection of fold catastrophes onto the sky. In principle, these imperfections can be detected and measured with gravitational lensing through discontinuities in image magnification and image structure. Lens solutions are discussed for the most common universal classes of discontinuities. Edges caused by cold particles—such as condensed axions and thermal weakly interacting, massive particles (WIMPs)—are very sharp, respectively about 10-12 and 10-7 of the halo scale. Their structure can be resolved by stellar and quasi-stellar sources that show sudden changes in brightness or even sudden disappearances (sometimes within hours) as edges are crossed. Images of extended objects such as edge-on galaxies or jets can show sudden bends at an edge, or stretched, parity-inverted reflection symmetry around a sharp line. Observational strategies and prospects are briefly discussed.
X-RAY MONITORING OF GRAVITATIONAL LENSES WITH CHANDRA

We present Chandra monitoring data for six gravitationally lensed quasars: QJ 0158-4325, HE 0435-1223, SDSS 0924+0219, SDSS 1004+4112, HE 1104-1805, and Q 2237+0305. X-ray microlensing variability is detected in all six lenses with high confidence. We furthermore detect energy-dependent microlensing in HE 0435-1223, SDSS 0924+0219, SDSS 1004+4112, and Q 2237+0305. Through a detailed spectral analysis for each lens we find that simple power-law models plus Gaussian emission lines give good fits to the spectra. We detect intrinsic spectral variability in two epochs of Q 2237+0305, and differential absorption between images in QJ 0158-4325 and Q2237+0305. We also detect the Fe K{alpha} emission line in all six lenses, and the Ni XXVII K{alpha} line in two images of Q 2237+0305. The rest-frame equivalent widths of the Fe K{alpha} lines are measured to be 0.4-1.2 keV, significantly higher than those measured in typical active galactic nuclei of similar X-ray luminosities. This suggests that the Fe K{alpha} emission region is more compact or centrally concentrated than the continuum emission region.
Revisiting the Formation of HeH+ in the Planetary Nebula NGC 7027

From four independent calculations using three different theoretical approaches, rate coefficients for the formation of HeH$^+$ via the radiative association of He$^+$ and H were computed. Good agreement is found between our new calculations and prior results obtained two decades ago for kinetic temperatures between $\sim$800 and 20,000 K. This finding is inconsistent with a recent claim in the literature of a wide variation in published values and establishes the robustness of our knowledge of this process for the formation of HeH$^+$. The implications of the current results to the first detection of HeH$^+$ and its modeled abundance in the planetary nebula NGC 7027 are discussed.
Quantum symmetric pairs and representations of double affine Hecke algebras of type $${C^\vee C_n}$$

We build representations of the affine and double affine braid groups and Hecke algebras of type $${C^\vee C_n}$$ based upon the theory of quantum symmetric pairs (U, B). In the case $${{\bf U}=\mathcal{U}_{\rm q}(\mathfrak{gl}_N)}$$ , our constructions provide a quantization of the representations constructed by Etingof, Freund, and Ma in [15], and also a type $${C^\vee C_n}$$ generalization of the results in [19].
The Energy Measure for the Euler and Navier–Stokes Equations

The potential failure of energy equality for a solution u of the Euler or Navier–Stokes equations can be quantified using a so-called ‘energy measure’: the weak- $$*$$ limit of the measures $${|u(t)|^2{\rm d}x}$$ as t approaches the first possible blowup time. We show that membership of u in certain (weak or strong) $${L^q L^p}$$ classes gives a uniform lower bound on the lower local dimension of $${\mathcal{E}}$$ ; more precisely, it implies uniform boundedness of a certain upper s-density of $${\mathcal{E}}$$ . We also define and give lower bounds on the ‘concentration dimension’ associated to $${\mathcal{E}}$$ , which is the Hausdorff dimension of the smallest set on which energy can concentrate. Both the lower local dimension and the concentration dimension of $${\mathcal{E}}$$ measure the departure from energy equality. As an application of our estimates, we prove that any solution to the 3-dimensional Navier–Stokes Equations which is Type-I in time must satisfy the energy equality at the first blowup time.
Efficient eigenvalue determination for arbitrary Pauli products based on generalized spin-spin interactions

Effective spin-spin interactions between N+1 qubits enable the determination of the eigenvalue of an arbitrary Pauli product of dimension N with a constant, small number of multi-qubit gates that i...
An All-sky Sample of Intermediate-mass Star-forming Regions

We present an all-sky sample of 984 candidate intermediate-mass Galactic star-forming regions that are color selected from the Infrared Astronomical Satellite (IRAS) Point Source Catalog and morphologically classify each object using mid-infrared Wide-field Infrared Survey Explorer (WISE) images. Of the 984 candidates, 616 are probable star-forming regions (62.6%), 128 are filamentary structures (13.0%), 39 are point-like objects of unknown nature (4.0%), and 201 are galaxies (20.4%). We conduct a study of four of these regions, IRAS 00259+5625, IRAS 00420+5530, IRAS 01080+5717, and IRAS 05380+2020, at Galactic latitudes |b| > 5° using optical spectroscopy from the Wyoming Infrared Observatory, along with near-infrared photometry from the Two-Micron All Sky Survey, to investigate their stellar content. New optical spectra, color-magnitude diagrams, and color-color diagrams reveal their extinctions, spectrophotometric distances, and the presence of small stellar clusters containing 20-78 M ☉ of stars. These low-mass diffuse star clusters contain ~65-250 stars for a typical initial mass function, including one or more mid-B stars as their most massive constituents. Using infrared spectral energy distributions we identify young stellar objects near each region and assign probable masses and evolutionary stages to the protostars. The total infrared luminosity lies in the range 190-960 L ☉, consistent with the sum of the luminosities of the individually identified young stellar objects.
Classical states, quantum field measurement

Classical Koopman--von Neumann Hilbert spaces of states are constructed here by the action of classical random fields on a vacuum state in ways that support an action of the quantized electromagnetic field and of the $U(1)$--invariant observables of the quantized Dirac spinor field, allowing a manifestly Lorentz invariant classical understanding of the state spaces of the two field theories, generalizing the Quantum--Mechanics--Free Systems of Tsang&Caves and Quantum Non-Demolition measurements. The algebra of functions on a classical phase space is commutative but the algebra of classical observables associated with coordinate transformations is noncommutative, so that, for example, we can as much ask whether a classical state is an eigenstate of a rotation as we can in quantum mechanics and so that entangled states can be distinguished from mixed states, making classical random fields as weird as quantum fields.
Hybrid real- and reciprocal-space full-field imaging with coherent illumination

We present a novel diffractive imaging method that harnesses a low-resolution real-space image to guide the phase retrieval. A computational algorithm is developed to utilize such prior knowledge as a real-space constraint in the iterative phase retrieval procedure. Numerical simulations and proof-of-concept experiments are carried out, demonstrating our method's capability of reconstructing high-resolution details that are otherwise inaccessible with traditional phasing algorithms. With the present method, we formulate a conceptual design for the coherent imaging experiments at a next-generation X-ray light source.
On Traffic Flow with Nonlocal Flux: A Relaxation Representation

We consider a conservation law model of traffic flow, where the velocity of each car depends on a weighted average of the traffic density $$\rho $$ ahead. The averaging kernel is of exponential type: $$w_\varepsilon (s)=\varepsilon ^{-1} e^{-s/\varepsilon }$$. By a transformation of coordinates, the problem can be reformulated as a $$2\times 2$$ hyperbolic system with relaxation. Uniform BV bounds on the solution are thus obtained, independent of the scaling parameter $$\varepsilon $$. Letting $$\varepsilon \rightarrow 0$$, the limit yields a weak solution to the corresponding conservation law $$\rho _t + ( \rho v(\rho ))_x=0$$. In the case where the velocity $$v(\rho )= a-b\rho $$ is affine, using the Hardy–Littlewood rearrangement inequality we prove that the limit is the unique entropy-admissible solution to the scalar conservation law.
Further Representations of the Canonical Commutation Relations

We construct a new class of representations of the canonical commutation relations, which generalizes previously known classes. We perturb the infinitesimal generator of the initial Fock representation (i.e. the free quantum field) by a function of the field which is square-integrable with respect to the associated Gaussian measure. We characterize which such perturbations lead to representations of the canonical commutation relations. We provide conditions entailing the irreducibility of such representations, show explicitly that our class of representations subsumes previously studied classes, and give necessary and sufficient conditions for our representations to be unitarily equivalent, resp. quasi-equivalent, with Fock, coherent or quasifree representations.
Algebraic varieties with semialgebraic universal cover

We study projective varieties whose universal cover is biholomorphic to a semialgebraic open subset of a projective variety.
Hybrid Low-Power Wide-Area Mesh Network for IoT Applications

The recent advancement of the Internet of Things (IoT) enables the possibility of data collection from diverse environments using IoT devices. However, despite the rapid advancement of low-power communication technologies, the deployment of IoT networks still faces many challenges. In this article, we propose a hybrid, low-power, wide-area network (LPWAN) structure that can achieve wide-area communication coverage and low-power consumption on IoT devices by utilizing both sub-GHz long-range radio and 2.4-GHz short-range radio. Specifically, we constructed a low-power mesh network with LoRa, a physical-layer standard that can provide long-range (kilometers) point-to-point communication using custom time-division multiple access (TDMA). Furthermore, we extended the capabilities of the mesh network by enabling ANT, an ultralow-power, short-range communication protocol to satisfy data collection in dense device deployments. Third, we demonstrate the performance of the hybrid network with two real-world deployments at the Purdue University campus and at the university-owned farm. The results suggest that both networks have superior advantages in terms of cost, coverage, and power consumption vis-a-vis other IoT solutions, like LoRaWAN.
Unitary Fermi Gas, $$\epsilon$$ Expansion, and Nonrelativistic Conformal Field Theories

We review theoretical aspects of unitary Fermi gas (UFG), which has been realized in ultracold atom experiments. We first introduce the \(\epsilon\) expansion technique based on a systematic expansion in terms of the dimensionality of space. We apply this technique to compute the thermodynamic quantities, the quasiparticle cum, and the criticl temperature of UFG. We then discuss consequences of the scale and conformal invariance of UFG. We prove a correspondence between primary operators in nonrelativistic conformal field theories and energy eigenstates in a harmonic potential. We use this correspondence to compute energies of fermions at unitarity in a harmonic potential. The scale and conformal invariance together with the general coordinate invariance constrains the properties of UFG. We show the vanishing bulk viscosities of UFG and derive the low-energy effective Lagrangian for the superfluid UFG. Finally we propose other systems exhibiting the nonrelativistic scaling and conformal symmetries that can be in principle realized in ultracold atom experiments.
2MASS J05185995–2828372: Discovery of an Unresolved L/T Binary

We present the peculiar near-infrared spectrum of the newly discovered brown dwarf 2MASS J05185995-2828372, identified in the Two Micron All Sky Survey. Features characteristic of both L and T dwarfs are present, namely, strong carbon monoxide absorption in the K band, strong methane absorption in the J and H bands, and red near-infrared colors. We consider several scenarios that could produce these features and conclude that the object is most likely to be an unresolved L/T binary system. We discuss how the estimated photometric properties of this object are consistent with the observed J-band brightening of brown dwarfs between late-L and early-T dwarfs, making detailed study of this system an important probe of the L/T transition.
Successive convexification of non-convex optimal control problems and its convergence properties

This paper presents an algorithm to solve non-convex optimal control problems, where non-convexity can arise from nonlinear dynamics, and non-convex state and control constraints. This paper assumes that the state and control constraints are already convex or convexified, the proposed algorithm convexifies the nonlinear dynamics, via a linearization, in a successive manner. Thus at each succession, a convex optimal control subproblem is solved. Since the dynamics are linearized and other constraints are convex, after a discretization, the subproblem can be expressed as a finite dimensional convex programming subproblem. Since convex optimization problems can be solved very efficiently, especially with custom solvers, this subproblem can be solved in time-critical applications, such as real-time path planning for autonomous vehicles. Several safe-guarding techniques are incorporated into the algorithm, namely virtual control and trust regions, which add another layer of algorithmic robustness. A convergence analysis is presented in continuous-time setting. By doing so, our convergence results will be independent from any numerical schemes used for discretization. Numerical simulations are performed for an illustrative trajectory optimization example.
Heterogeneous Stochastic Interactions for Multiple Agents in a Multi-armed Bandit Problem

We define and analyze a multi-agent multi-armed bandit problem in which decision-making agents can observe the choices and rewards of their neighbors. Neighbors are defined by a network graph with heterogeneous and stochastic interconnections. These interactions are determined by the sociability of each agent, which corresponds to the probability that the agent observes its neighbors. We design an algorithm for each agent to maximize its own expected cumulative reward and prove performance bounds that depend on the sociability of the agents and the network structure. We use the bounds to predict the rank ordering of agents according to their performance and verify the accuracy analytically and computationally.
Photoacoustic ultrasound sources from diffusion-limited aggregates

Metallic diffusion-limited aggregate (DLA) films are well-known to exhibit near-perfect broadband optical absorption. We demonstrate that such films also manifest a substantial and relatively material-independent photoacoustic response, as a consequence of their random nanostructure. We theoretically and experimentally analyze the photoacoustic phenomena in DLA films and show that they can be used to create broadband air-coupled acoustic sources. These sources are inexpensive and simple to fabricate and work into the ultrasonic regime. We illustrate the device possibilities by building and testing an optically addressed acoustic phased array capable of producing virtually arbitrary acoustic intensity patterns in air.
Entanglement in Higher-Radix Quantum Systems

Entanglement is an important phenomenon that enables quantum information processing algorithms and quantum communications protocols. Although entangled quantum states are often described in radix-2, higher-radix qudits can become entangled as well. In this work, we both introduce partial entanglement, a concept that does not exist for radix-2 quantum systems, and differentiate between partial and maximal entanglement within non-binary quantum information processing systems. We also develop and present higher-radix maximal entanglement generator circuits that are analogous to the well-known Bell state generator for binary quantum systems. Because higher-dimensioned qudits can be subjected to entangling processes that result in either partially or maximally entangled states, we demonstrate how higher-radix qudit circuits can be composed to generate these varying degrees of partial quantum entanglement. Theoretical results are provided for the general case where the radix is greater than two, and specific results based on a nair of radix-4 audits are described.
Asymptotically hyperbolic black holes in Horava gravity

Solutions of Hořava gravity that are asymptotically Lifshitz are explored. General near boundary expansions allow the calculation of the mass of these spacetimes via a Hamiltonian method. Both analytic and numeric solutions are studied which exhibit a causal boundary called the universal horizon, and are therefore black holes of the theory. The thermodynamics of an asymptotically Anti-de Sitter Hořava black hole are verified.
A Quantitative Vainberg Method for Black Box Scattering

We give a quantitative version of Vainberg’s method relating pole free regions to propagation of singularities for black box scatterers. In particular, we show that there is a logarithmic resonance free region near the real axis of size \({\tau}\) with polynomial bounds on the resolvent if and only if the wave propagator gains derivatives at rate \({\tau}\). Next we show that if there exist singularities in the wave trace at times tending to infinity which smooth at rate \({\tau}\), then there are resonances in logarithmic strips whose width is given by \({\tau}\). As our main application of these results, we give sharp bounds on the size of resonance free regions in scattering on geometrically nontrapping manifolds with conic points. Moreover, these bounds are generically optimal on exteriors of nontrapping polygonal domains.
Remarks on the arithmetic fundamental lemma

W. Zhang's arithmetic fundamental lemma (AFL) is a conjectural identity between the derivative of an orbital integral on a symmetric space with an arithmetic intersection number on a unitary Rapoport-Zink space. In the minuscule case, Rapoport-Terstiege-Zhang have verified the AFL conjecture via explicit evaluation of both sides of the identity. We present a simpler way for evaluating the arithmetic intersection number, thereby providing a new proof of the AFL conjecture in the minuscule case.
Predicting protein dynamics from structural ensembles

The biological properties of proteins are uniquely determined by their structure and dynamics. A protein in solution populates a structural ensemble of metastable configurations around the global fold. From overall rotation to local fluctuations, the dynamics of proteins can cover several orders of magnitude in time scales. We propose a simulation-free coarse-grained approach which utilizes knowledge of the important metastable folded states of the protein to predict the protein dynamics. This approach is based upon the Langevin Equation for Protein Dynamics (LE4PD), a Langevin formalism in the coordinates of the protein backbone. The linear modes of this Langevin formalism organize the fluctuations of the protein, so that more extended dynamical cooperativity relates to increasing energy barriers to mode diffusion. The accuracy of the LE4PD is verified by analyzing the predicted dynamics across a set of seven different proteins for which both relaxation data and NMR solution structures are available. Using experimental NMR conformers as the input structural ensembles, LE4PD predicts quantitatively accurate results, with correlation coefficient ρ = 0.93 to NMR backbone relaxation measurements for the seven proteins. The NMR solution structure derived ensemble and predicted dynamical relaxation is compared with molecular dynamics simulation-derived structural ensembles and LE4PD predictions and is consistent in the time scale of the simulations. The use of the experimental NMR conformers frees the approach from computationally demanding simulations.
Energy flow polynomials: a complete linear basis for jet substructure

We introduce the energy flow polynomials: a complete set of jet substructure observables which form a discrete linear basis for all infrared- and collinear-safe observables. Energy flow polynomials are multiparticle energy correlators with specific angular structures that are a direct consequence of infrared and collinear safety. We establish a powerful graph-theoretic representation of the energy flow polynomials which allows us to design efficient algorithms for their computation. Many common jet observables are exact linear combinations of energy flow polynomials, and we demonstrate the linear spanning nature of the energy flow basis by performing regression for several common jet observables. Using linear classification with energy flow polynomials, we achieve excellent performance on three representative jet tagging problems: quark/gluon discrimination, boosted W tagging, and boosted top tagging. The energy flow basis provides a systematic framework for complete investigations of jet substructure using linear methods.
P Wave Arrival Picking and First-Motion Polarity Determination With Deep Learning

Determining earthquake hypocenters and focal mechanisms requires precisely measured P wave arrival times and first‐motion polarities. Automated algorithms for estimating these quantities have been less accurate than estimates by human experts, which are problematic for processing large data volumes. Here we train convolutional neural networks to measure both quantities, which learn directly from seismograms without the need for feature extraction. The networks are trained on 18.2 million manually picked seismograms for the Southern California region. Through cross validation on 1.2 million independent seismograms, the differences between the automated and manual picks have a standard deviation of 0.023 s. The polarities determined by the classifier have a precision of 95% when compared with analyst‐determined polarities. We show that the classifier picks more polarities overall than the analysts, without sacrificing quality, resulting in almost double the number of focal mechanisms. The remarkable precision of the trained networks indicates that they can perform as well, or better, than expert seismologists.
Approximate support recovery of atomic line spectral estimation: A tale of resolution and precision

Abstract This work investigates the parameter estimation performance of super-resolution line spectral estimation using atomic norm minimization. The focus is on analyzing the algorithm's accuracy of inferring the frequencies and complex magnitudes from noisy observations. When the Signal-to-Noise Ratio is reasonably high and the true frequencies are separated by O ( 1 n ) , the atomic norm estimator is shown to localize the correct number of frequencies, each within a neighborhood of size O ( log ⁡ n / n 3 σ ) of one of the true frequencies. Here n is half the number of temporal samples and σ 2 is the Gaussian noise variance. The analysis is based on a primal–dual witness construction procedure. The obtained error bound matches the Cramer–Rao lower bound up to a logarithmic factor. The relationship between resolution (separation of frequencies) and precision or accuracy of the estimator is highlighted. Our analysis also reveals that the atomic norm minimization can be viewed as a convex way to solve a l 1 -norm regularized, nonlinear and nonconvex least-squares problem to global optimality.
PARTISAN REPRESENTATION IN CONGRESS AND THE GEOGRAPHIC DISTRIBUTION OF FEDERAL FUNDS

EW researchers have examined whether a legislator’s party membership may influence the kind or amount of government funds her district receives. Party membership is known to have a strong effect on the voting behavior of U.S. members of Congress (Lee, Moretti, & Butler, 2004; Albouy, 2011), but it is unclear whether party membership influences actual funding, either because of ideological differences or because of power imbalances between parties. Existing theories of distributional politics give little theoretical guidance as to how or why funding might be influenced by party membership, and empirical studies have yet to establish that party membership does make a difference at the federal level. This article investigates both theoretically and empirically how party membership of legislators in Congress may influence the distribution of federal funds in the United States. The theoretical investigation introduces two political parties to the game-theoretic legislative bargaining model of Baron and Ferejohn (1989, henceforth BF), enriching the model in a number of significant ways. First, majority status may confer greater proposal, or agenda-setting, power to legislators, increasing their access to federal funds. Second, if legislators prefer to form voting coalitions with members of the same party, members of the majority can procure additional funding through a party-coalition effect, which increases with the majority’s size. Beyond the effects due to imbalances in bargaining power, differences in ideology, or taste, between parties may mean that a district will receive a different assortment of funding types depending on the party membership of its representatives. These taste differences may also explain why members of the same party prefer forming coalitions with each other.
A Takayama-type extension theorem

We prove a theorem on the extension of holomorphic sections of powers of adjoint bundles from submanifolds of complex codimension 1 having non-trivial normal bundle. The first such result, due to Takayama, considers the case where the canonical bundle is twisted by a line bundle that is a sum of a big and nef line bundle and a -divisor that has Kawamata log terminal singularities on the submanifold from which extension occurs. In this paper we weaken the positivity assumptions on the twisting line bundle to what we believe to be the minimal positivity hypotheses. The main new idea is an L 2 extension theorem of Ohsawa–Takegoshi type, in which twisted canonical sections are extended from submanifolds with non-trivial normal bundle.
Delegating Quantum Computation in the Quantum Random Oracle Model

A delegation scheme allows a computationally weak client to use a server’s resources to help it evaluate a complex circuit without leaking any information about the input (other than its length) to the server. In this paper, we consider delegation schemes for quantum circuits, where we try to minimize the quantum operations needed by the client. We construct a new scheme for delegating a large circuit family, which we call “C+P circuits”. “C+P” circuits are the circuits composed of Toffoli gates and diagonal gates. Our scheme is non-interactive, requires small amount of quantum computation from the client (proportional to input length but independent of the circuit size), and can be proved secure in the quantum random oracle model, without relying on additional assumptions, such as the existence of fully homomorphic encryption. In practice the random oracle can be replaced by an appropriate hash function or block cipher, for example, SHA-3, AES.
Radioactive Heating and Late Time Kilonova Light Curves

Compact object mergers can produce a thermal electromagnetic counterpart (a "kilonova") powered by the decay of freshly synthesized radioactive isotopes. The luminosity of kilonova light curves depends on the efficiency with which beta-decay electrons are thermalized in the ejecta. Here we derive a simple analytic solution for thermalization by calculating how accumulate electrons lose energy adiabatically and via plasma interactions. The thermalization efficiency is well described by where the timescale is a function of the ejecta mass and velocity and the exponent depends on the electron energies and the thermalization cross-sections. For a statistical distribution of r-process isotopes with radioactive power and n = 1, the late time kilonova luminosity asymptotes to and depends super-linearly on the ejecta mass, . If a kilonova is instead powered by a single dominate isotope, we show that the late time luminosity can deviate substantially from the underlying exponential decay and the heating from the accumulation of trapped electrons eventually exceeds the instantaneous radioactivity. Applied to the kilonova associated with the gravitational wave source GW170817, these results imply that a possible steepening of the light curve at 7 days is unrelated to thermalization effects and instead could mark the onset of translucency in a high opacity component of ejecta. The analytic results should be convenient for estimating the properties of observed kilonovae and assessing the potential late time detectability of future events.
Exploiting problem structure in optimization under uncertainty via online convex optimization

In this paper, we consider two paradigms that are developed to account for uncertainty in optimization models: robust optimization (RO) and joint estimation-optimization (JEO). We examine recent developments on efficient and scalable iterative first-order methods for these problems, and show that these iterative methods can be viewed through the lens of online convex optimization (OCO). The standard OCO framework has seen much success for its ability to handle decision-making in dynamic, uncertain, and even adversarial environments. Nevertheless, our applications of interest present further flexibility in OCO via three simple modifications to standard OCO assumptions: we introduce two new concepts of weighted regret and online saddle point problems and study the possibility of making lookahead (anticipatory) decisions. Our analyses demonstrate that these flexibilities introduced into the OCO framework have significant consequences whenever they are applicable. For example, in the strongly convex case, minimizing unweighted regret has a proven optimal bound of $$O(\mathop {\mathrm{log}}(T)/T)$$, whereas we show that a bound of O(1 / T) is possible when we consider weighted regret. Similarly, for the smooth case, considering 1-lookahead decisions results in a O(1 / T) bound, compared to $$O(1/\sqrt{T})$$ in the standard OCO setting. Consequently, these OCO tools are instrumental in exploiting structural properties of functions and results in improved convergence rates for RO and JEO. In certain cases, our results for RO and JEO match the best known or optimal rates in the corresponding problem classes without data uncertainty.
Abelian 2+1D loop quantum gravity coupled to a scalar field

In order to study 3d loop quantum gravity coupled to matter, we consider a simplified model of abelian quantum gravity, the so-called $$\mathrm {U}(1)^3$$ model. Abelian gravity coupled to a scalar field shares a lot of commonalities with parameterized field theories. We use this to develop an exact quantization of the model. This is used to discuss solutions to various problems that plague even the 4d theory, namely the definition of an inverse metric and the role of the choice of representation for the holonomy-flux algebra.